diff --git a/i18n/en.json b/i18n/en.json
index 97f4575567..d6ffd0dfc8 100644
--- a/i18n/en.json
+++ b/i18n/en.json
@@ -399,6 +399,10 @@
     "transcoding_preferred_hardware_device_description": "Applies only to VAAPI and QSV. Sets the dri node used for hardware transcoding.",
     "transcoding_preset_preset": "Preset (-preset)",
     "transcoding_preset_preset_description": "Compression speed. Slower presets produce smaller files, and increase quality when targeting a certain bitrate. VP9 ignores speeds above 'faster'.",
+    "transcoding_realtime": "Real-time Transcoding [EXPERIMENTAL]",
+    "transcoding_realtime_description": "Allows transcoding to be performed in real-time as the video is being streamed. Enables quality switching, but may cause higher playback latency and stuttering depending on server capabilities.",
+    "transcoding_realtime_enabled": "Enable real-time transcoding",
+    "transcoding_realtime_enabled_description": "If disabled, the server will refuse to start new real-time transcoding sessions.",
     "transcoding_reference_frames": "Reference frames",
     "transcoding_reference_frames_description": "The number of frames to reference when compressing a given frame. Higher values improve compression efficiency, but slow down encoding. 0 sets this value automatically.",
     "transcoding_required_description": "Only videos not in an accepted format",
diff --git a/mobile/openapi/README.md b/mobile/openapi/README.md
index ecc75dd945..5772b6803d 100644
--- a/mobile/openapi/README.md
+++ b/mobile/openapi/README.md
@@ -103,12 +103,16 @@ Class | Method | HTTP request | Description
 *AssetsApi* | [**deleteBulkAssetMetadata**](doc//AssetsApi.md#deletebulkassetmetadata) | **DELETE** /assets/metadata | Delete asset metadata
 *AssetsApi* | [**downloadAsset**](doc//AssetsApi.md#downloadasset) | **GET** /assets/{id}/original | Download original asset
 *AssetsApi* | [**editAsset**](doc//AssetsApi.md#editasset) | **PUT** /assets/{id}/edits | Apply edits to an existing asset
+*AssetsApi* | [**endSession**](doc//AssetsApi.md#endsession) | **DELETE** /assets/{id}/video/stream/{sessionId} | End HLS streaming session
 *AssetsApi* | [**getAssetEdits**](doc//AssetsApi.md#getassetedits) | **GET** /assets/{id}/edits | Retrieve edits for an existing asset
 *AssetsApi* | [**getAssetInfo**](doc//AssetsApi.md#getassetinfo) | **GET** /assets/{id} | Retrieve an asset
 *AssetsApi* | [**getAssetMetadata**](doc//AssetsApi.md#getassetmetadata) | **GET** /assets/{id}/metadata | Get asset metadata
 *AssetsApi* | [**getAssetMetadataByKey**](doc//AssetsApi.md#getassetmetadatabykey) | **GET** /assets/{id}/metadata/{key} | Retrieve asset metadata by key
 *AssetsApi* | [**getAssetOcr**](doc//AssetsApi.md#getassetocr) | **GET** /assets/{id}/ocr | Retrieve asset OCR data
 *AssetsApi* | [**getAssetStatistics**](doc//AssetsApi.md#getassetstatistics) | **GET** /assets/statistics | Get asset statistics
+*AssetsApi* | [**getMainPlaylist**](doc//AssetsApi.md#getmainplaylist) | **GET** /assets/{id}/video/stream/main.m3u8 | Get HLS main playlist
+*AssetsApi* | [**getMediaPlaylist**](doc//AssetsApi.md#getmediaplaylist) | **GET** /assets/{id}/video/stream/{sessionId}/{variantIndex}/playlist.m3u8 | Get HLS media playlist
+*AssetsApi* | [**getSegment**](doc//AssetsApi.md#getsegment) | **GET** /assets/{id}/video/stream/{sessionId}/{variantIndex}/{filename} | Get HLS segment or init file
 *AssetsApi* | [**playAssetVideo**](doc//AssetsApi.md#playassetvideo) | **GET** /assets/{id}/video/playback | Play asset video
 *AssetsApi* | [**removeAssetEdits**](doc//AssetsApi.md#removeassetedits) | **DELETE** /assets/{id}/edits | Remove edits from an existing asset
 *AssetsApi* | [**runAssetJobs**](doc//AssetsApi.md#runassetjobs) | **POST** /assets/jobs | Run an asset job
@@ -594,6 +598,7 @@ Class | Method | HTTP request | Description
  - [SystemConfigBackupsDto](doc//SystemConfigBackupsDto.md)
  - [SystemConfigDto](doc//SystemConfigDto.md)
  - [SystemConfigFFmpegDto](doc//SystemConfigFFmpegDto.md)
+ - [SystemConfigFFmpegRealtimeDto](doc//SystemConfigFFmpegRealtimeDto.md)
  - [SystemConfigFacesDto](doc//SystemConfigFacesDto.md)
  - [SystemConfigGeneratedFullsizeImageDto](doc//SystemConfigGeneratedFullsizeImageDto.md)
  - [SystemConfigGeneratedImageDto](doc//SystemConfigGeneratedImageDto.md)
diff --git a/mobile/openapi/lib/api.dart b/mobile/openapi/lib/api.dart
index 1769c8af75..b5953388f4 100644
--- a/mobile/openapi/lib/api.dart
+++ b/mobile/openapi/lib/api.dart
@@ -340,6 +340,7 @@ part 'model/sync_user_v1.dart';
 part 'model/system_config_backups_dto.dart';
 part 'model/system_config_dto.dart';
 part 'model/system_config_f_fmpeg_dto.dart';
+part 'model/system_config_f_fmpeg_realtime_dto.dart';
 part 'model/system_config_faces_dto.dart';
 part 'model/system_config_generated_fullsize_image_dto.dart';
 part 'model/system_config_generated_image_dto.dart';
diff --git a/mobile/openapi/lib/api/assets_api.dart b/mobile/openapi/lib/api/assets_api.dart
index 691c57cd3e..66e24e969d 100644
--- a/mobile/openapi/lib/api/assets_api.dart
+++ b/mobile/openapi/lib/api/assets_api.dart
@@ -416,6 +416,75 @@ class AssetsApi {
     return null;
   }
 
+  /// End HLS streaming session
+  ///
+  /// Releases server resources for the streaming session.
+  ///
+  /// Note: This method returns the HTTP [Response].
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<Response> endSessionWithHttpInfo(String id, String sessionId, { String? key, String? slug, }) async {
+    // ignore: prefer_const_declarations
+    final apiPath = r'/assets/{id}/video/stream/{sessionId}'
+      .replaceAll('{id}', id)
+      .replaceAll('{sessionId}', sessionId);
+
+    // ignore: prefer_final_locals
+    Object? postBody;
+
+    final queryParams = <QueryParam>[];
+    final headerParams = <String, String>{};
+    final formParams = <String, String>{};
+
+    if (key != null) {
+      queryParams.addAll(_queryParams('', 'key', key));
+    }
+    if (slug != null) {
+      queryParams.addAll(_queryParams('', 'slug', slug));
+    }
+
+    const contentTypes = <String>[];
+
+
+    return apiClient.invokeAPI(
+      apiPath,
+      'DELETE',
+      queryParams,
+      postBody,
+      headerParams,
+      formParams,
+      contentTypes.isEmpty ? null : contentTypes.first,
+    );
+  }
+
+  /// End HLS streaming session
+  ///
+  /// Releases server resources for the streaming session.
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<void> endSession(String id, String sessionId, { String? key, String? slug, }) async {
+    final response = await endSessionWithHttpInfo(id, sessionId,  key: key, slug: slug, );
+    if (response.statusCode >= HttpStatus.badRequest) {
+      throw ApiException(response.statusCode, await _decodeBodyBytes(response));
+    }
+  }
+
   /// Retrieve edits for an existing asset
   ///
   /// Retrieve a series of edit actions (crop, rotate, mirror) associated with the specified asset.
@@ -809,6 +878,247 @@ class AssetsApi {
     return null;
   }
 
+  /// Get HLS main playlist
+  ///
+  /// Returns an HLS main playlist with all available variants for the asset.
+  ///
+  /// Note: This method returns the HTTP [Response].
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<Response> getMainPlaylistWithHttpInfo(String id, { String? key, String? slug, }) async {
+    // ignore: prefer_const_declarations
+    final apiPath = r'/assets/{id}/video/stream/main.m3u8'
+      .replaceAll('{id}', id);
+
+    // ignore: prefer_final_locals
+    Object? postBody;
+
+    final queryParams = <QueryParam>[];
+    final headerParams = <String, String>{};
+    final formParams = <String, String>{};
+
+    if (key != null) {
+      queryParams.addAll(_queryParams('', 'key', key));
+    }
+    if (slug != null) {
+      queryParams.addAll(_queryParams('', 'slug', slug));
+    }
+
+    const contentTypes = <String>[];
+
+
+    return apiClient.invokeAPI(
+      apiPath,
+      'GET',
+      queryParams,
+      postBody,
+      headerParams,
+      formParams,
+      contentTypes.isEmpty ? null : contentTypes.first,
+    );
+  }
+
+  /// Get HLS main playlist
+  ///
+  /// Returns an HLS main playlist with all available variants for the asset.
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<String?> getMainPlaylist(String id, { String? key, String? slug, }) async {
+    final response = await getMainPlaylistWithHttpInfo(id,  key: key, slug: slug, );
+    if (response.statusCode >= HttpStatus.badRequest) {
+      throw ApiException(response.statusCode, await _decodeBodyBytes(response));
+    }
+    // When a remote server returns no body with a status of 204, we shall not decode it.
+    // At the time of writing this, `dart:convert` will throw an "Unexpected end of input"
+    // FormatException when trying to decode an empty string.
+    if (response.body.isNotEmpty && response.statusCode != HttpStatus.noContent) {
+      return await apiClient.deserializeAsync(await _decodeBodyBytes(response), 'String',) as String;
+    
+    }
+    return null;
+  }
+
+  /// Get HLS media playlist
+  ///
+  /// Returns an HLS media playlist for one variant of the streaming session.
+  ///
+  /// Note: This method returns the HTTP [Response].
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [int] variantIndex (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<Response> getMediaPlaylistWithHttpInfo(String id, String sessionId, int variantIndex, { String? key, String? slug, }) async {
+    // ignore: prefer_const_declarations
+    final apiPath = r'/assets/{id}/video/stream/{sessionId}/{variantIndex}/playlist.m3u8'
+      .replaceAll('{id}', id)
+      .replaceAll('{sessionId}', sessionId)
+      .replaceAll('{variantIndex}', variantIndex.toString());
+
+    // ignore: prefer_final_locals
+    Object? postBody;
+
+    final queryParams = <QueryParam>[];
+    final headerParams = <String, String>{};
+    final formParams = <String, String>{};
+
+    if (key != null) {
+      queryParams.addAll(_queryParams('', 'key', key));
+    }
+    if (slug != null) {
+      queryParams.addAll(_queryParams('', 'slug', slug));
+    }
+
+    const contentTypes = <String>[];
+
+
+    return apiClient.invokeAPI(
+      apiPath,
+      'GET',
+      queryParams,
+      postBody,
+      headerParams,
+      formParams,
+      contentTypes.isEmpty ? null : contentTypes.first,
+    );
+  }
+
+  /// Get HLS media playlist
+  ///
+  /// Returns an HLS media playlist for one variant of the streaming session.
+  ///
+  /// Parameters:
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [int] variantIndex (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<String?> getMediaPlaylist(String id, String sessionId, int variantIndex, { String? key, String? slug, }) async {
+    final response = await getMediaPlaylistWithHttpInfo(id, sessionId, variantIndex,  key: key, slug: slug, );
+    if (response.statusCode >= HttpStatus.badRequest) {
+      throw ApiException(response.statusCode, await _decodeBodyBytes(response));
+    }
+    // When a remote server returns no body with a status of 204, we shall not decode it.
+    // At the time of writing this, `dart:convert` will throw an "Unexpected end of input"
+    // FormatException when trying to decode an empty string.
+    if (response.body.isNotEmpty && response.statusCode != HttpStatus.noContent) {
+      return await apiClient.deserializeAsync(await _decodeBodyBytes(response), 'String',) as String;
+    
+    }
+    return null;
+  }
+
+  /// Get HLS segment or init file
+  ///
+  /// Streams an HLS init segment (init.mp4) or media segment (seg_N.m4s).
+  ///
+  /// Note: This method returns the HTTP [Response].
+  ///
+  /// Parameters:
+  ///
+  /// * [String] filename (required):
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [int] variantIndex (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<Response> getSegmentWithHttpInfo(String filename, String id, String sessionId, int variantIndex, { String? key, String? slug, }) async {
+    // ignore: prefer_const_declarations
+    final apiPath = r'/assets/{id}/video/stream/{sessionId}/{variantIndex}/{filename}'
+      .replaceAll('{filename}', filename)
+      .replaceAll('{id}', id)
+      .replaceAll('{sessionId}', sessionId)
+      .replaceAll('{variantIndex}', variantIndex.toString());
+
+    // ignore: prefer_final_locals
+    Object? postBody;
+
+    final queryParams = <QueryParam>[];
+    final headerParams = <String, String>{};
+    final formParams = <String, String>{};
+
+    if (key != null) {
+      queryParams.addAll(_queryParams('', 'key', key));
+    }
+    if (slug != null) {
+      queryParams.addAll(_queryParams('', 'slug', slug));
+    }
+
+    const contentTypes = <String>[];
+
+
+    return apiClient.invokeAPI(
+      apiPath,
+      'GET',
+      queryParams,
+      postBody,
+      headerParams,
+      formParams,
+      contentTypes.isEmpty ? null : contentTypes.first,
+    );
+  }
+
+  /// Get HLS segment or init file
+  ///
+  /// Streams an HLS init segment (init.mp4) or media segment (seg_N.m4s).
+  ///
+  /// Parameters:
+  ///
+  /// * [String] filename (required):
+  ///
+  /// * [String] id (required):
+  ///
+  /// * [String] sessionId (required):
+  ///
+  /// * [int] variantIndex (required):
+  ///
+  /// * [String] key:
+  ///
+  /// * [String] slug:
+  Future<MultipartFile?> getSegment(String filename, String id, String sessionId, int variantIndex, { String? key, String? slug, }) async {
+    final response = await getSegmentWithHttpInfo(filename, id, sessionId, variantIndex,  key: key, slug: slug, );
+    if (response.statusCode >= HttpStatus.badRequest) {
+      throw ApiException(response.statusCode, await _decodeBodyBytes(response));
+    }
+    // When a remote server returns no body with a status of 204, we shall not decode it.
+    // At the time of writing this, `dart:convert` will throw an "Unexpected end of input"
+    // FormatException when trying to decode an empty string.
+    if (response.body.isNotEmpty && response.statusCode != HttpStatus.noContent) {
+      return await apiClient.deserializeAsync(await _decodeBodyBytes(response), 'MultipartFile',) as MultipartFile;
+    
+    }
+    return null;
+  }
+
   /// Play asset video
   ///
   /// Streams the video file for the specified asset. This endpoint also supports byte range requests.
diff --git a/mobile/openapi/lib/api_client.dart b/mobile/openapi/lib/api_client.dart
index 103a5db5f4..a0a3f606bd 100644
--- a/mobile/openapi/lib/api_client.dart
+++ b/mobile/openapi/lib/api_client.dart
@@ -726,6 +726,8 @@ class ApiClient {
           return SystemConfigDto.fromJson(value);
         case 'SystemConfigFFmpegDto':
           return SystemConfigFFmpegDto.fromJson(value);
+        case 'SystemConfigFFmpegRealtimeDto':
+          return SystemConfigFFmpegRealtimeDto.fromJson(value);
         case 'SystemConfigFacesDto':
           return SystemConfigFacesDto.fromJson(value);
         case 'SystemConfigGeneratedFullsizeImageDto':
diff --git a/mobile/openapi/lib/model/job_name.dart b/mobile/openapi/lib/model/job_name.dart
index 444b080c12..6251c13050 100644
--- a/mobile/openapi/lib/model/job_name.dart
+++ b/mobile/openapi/lib/model/job_name.dart
@@ -52,6 +52,7 @@ class JobName {
   static const librarySyncFilesQueueAll = JobName._(r'LibrarySyncFilesQueueAll');
   static const librarySyncFiles = JobName._(r'LibrarySyncFiles');
   static const libraryScanQueueAll = JobName._(r'LibraryScanQueueAll');
+  static const hlsSessionCleanup = JobName._(r'HlsSessionCleanup');
   static const memoryCleanup = JobName._(r'MemoryCleanup');
   static const memoryGenerate = JobName._(r'MemoryGenerate');
   static const notificationsCleanup = JobName._(r'NotificationsCleanup');
@@ -110,6 +111,7 @@ class JobName {
     librarySyncFilesQueueAll,
     librarySyncFiles,
     libraryScanQueueAll,
+    hlsSessionCleanup,
     memoryCleanup,
     memoryGenerate,
     notificationsCleanup,
@@ -203,6 +205,7 @@ class JobNameTypeTransformer {
         case r'LibrarySyncFilesQueueAll': return JobName.librarySyncFilesQueueAll;
         case r'LibrarySyncFiles': return JobName.librarySyncFiles;
         case r'LibraryScanQueueAll': return JobName.libraryScanQueueAll;
+        case r'HlsSessionCleanup': return JobName.hlsSessionCleanup;
         case r'MemoryCleanup': return JobName.memoryCleanup;
         case r'MemoryGenerate': return JobName.memoryGenerate;
         case r'NotificationsCleanup': return JobName.notificationsCleanup;
diff --git a/mobile/openapi/lib/model/system_config_f_fmpeg_dto.dart b/mobile/openapi/lib/model/system_config_f_fmpeg_dto.dart
index ecf2e5da4a..79da8da97f 100644
--- a/mobile/openapi/lib/model/system_config_f_fmpeg_dto.dart
+++ b/mobile/openapi/lib/model/system_config_f_fmpeg_dto.dart
@@ -25,6 +25,7 @@ class SystemConfigFFmpegDto {
     required this.maxBitrate,
     required this.preferredHwDevice,
     required this.preset,
+    required this.realtime,
     required this.refs,
     required this.targetAudioCodec,
     required this.targetResolution,
@@ -79,6 +80,8 @@ class SystemConfigFFmpegDto {
   /// Preset
   String preset;
 
+  SystemConfigFFmpegRealtimeDto realtime;
+
   /// References
   ///
   /// Minimum value: 0
@@ -122,6 +125,7 @@ class SystemConfigFFmpegDto {
     other.maxBitrate == maxBitrate &&
     other.preferredHwDevice == preferredHwDevice &&
     other.preset == preset &&
+    other.realtime == realtime &&
     other.refs == refs &&
     other.targetAudioCodec == targetAudioCodec &&
     other.targetResolution == targetResolution &&
@@ -147,6 +151,7 @@ class SystemConfigFFmpegDto {
     (maxBitrate.hashCode) +
     (preferredHwDevice.hashCode) +
     (preset.hashCode) +
+    (realtime.hashCode) +
     (refs.hashCode) +
     (targetAudioCodec.hashCode) +
     (targetResolution.hashCode) +
@@ -158,7 +163,7 @@ class SystemConfigFFmpegDto {
     (twoPass.hashCode);
 
   @override
-  String toString() => 'SystemConfigFFmpegDto[accel=$accel, accelDecode=$accelDecode, acceptedAudioCodecs=$acceptedAudioCodecs, acceptedContainers=$acceptedContainers, acceptedVideoCodecs=$acceptedVideoCodecs, bframes=$bframes, cqMode=$cqMode, crf=$crf, gopSize=$gopSize, maxBitrate=$maxBitrate, preferredHwDevice=$preferredHwDevice, preset=$preset, refs=$refs, targetAudioCodec=$targetAudioCodec, targetResolution=$targetResolution, targetVideoCodec=$targetVideoCodec, temporalAQ=$temporalAQ, threads=$threads, tonemap=$tonemap, transcode=$transcode, twoPass=$twoPass]';
+  String toString() => 'SystemConfigFFmpegDto[accel=$accel, accelDecode=$accelDecode, acceptedAudioCodecs=$acceptedAudioCodecs, acceptedContainers=$acceptedContainers, acceptedVideoCodecs=$acceptedVideoCodecs, bframes=$bframes, cqMode=$cqMode, crf=$crf, gopSize=$gopSize, maxBitrate=$maxBitrate, preferredHwDevice=$preferredHwDevice, preset=$preset, realtime=$realtime, refs=$refs, targetAudioCodec=$targetAudioCodec, targetResolution=$targetResolution, targetVideoCodec=$targetVideoCodec, temporalAQ=$temporalAQ, threads=$threads, tonemap=$tonemap, transcode=$transcode, twoPass=$twoPass]';
 
   Map<String, dynamic> toJson() {
     final json = <String, dynamic>{};
@@ -174,6 +179,7 @@ class SystemConfigFFmpegDto {
       json[r'maxBitrate'] = this.maxBitrate;
       json[r'preferredHwDevice'] = this.preferredHwDevice;
       json[r'preset'] = this.preset;
+      json[r'realtime'] = this.realtime;
       json[r'refs'] = this.refs;
       json[r'targetAudioCodec'] = this.targetAudioCodec;
       json[r'targetResolution'] = this.targetResolution;
@@ -207,6 +213,7 @@ class SystemConfigFFmpegDto {
         maxBitrate: mapValueOfType<String>(json, r'maxBitrate')!,
         preferredHwDevice: mapValueOfType<String>(json, r'preferredHwDevice')!,
         preset: mapValueOfType<String>(json, r'preset')!,
+        realtime: SystemConfigFFmpegRealtimeDto.fromJson(json[r'realtime'])!,
         refs: mapValueOfType<int>(json, r'refs')!,
         targetAudioCodec: AudioCodec.fromJson(json[r'targetAudioCodec'])!,
         targetResolution: mapValueOfType<String>(json, r'targetResolution')!,
@@ -275,6 +282,7 @@ class SystemConfigFFmpegDto {
     'maxBitrate',
     'preferredHwDevice',
     'preset',
+    'realtime',
     'refs',
     'targetAudioCodec',
     'targetResolution',
diff --git a/mobile/openapi/lib/model/system_config_f_fmpeg_realtime_dto.dart b/mobile/openapi/lib/model/system_config_f_fmpeg_realtime_dto.dart
new file mode 100644
index 0000000000..1a8669912e
--- /dev/null
+++ b/mobile/openapi/lib/model/system_config_f_fmpeg_realtime_dto.dart
@@ -0,0 +1,100 @@
+//
+// AUTO-GENERATED FILE, DO NOT MODIFY!
+//
+// @dart=2.18
+
+// ignore_for_file: unused_element, unused_import
+// ignore_for_file: always_put_required_named_parameters_first
+// ignore_for_file: constant_identifier_names
+// ignore_for_file: lines_longer_than_80_chars
+
+part of openapi.api;
+
+class SystemConfigFFmpegRealtimeDto {
+  /// Returns a new [SystemConfigFFmpegRealtimeDto] instance.
+  SystemConfigFFmpegRealtimeDto({
+    required this.enabled,
+  });
+
+  /// Enable real-time HLS transcoding (alpha)
+  bool enabled;
+
+  @override
+  bool operator ==(Object other) => identical(this, other) || other is SystemConfigFFmpegRealtimeDto &&
+    other.enabled == enabled;
+
+  @override
+  int get hashCode =>
+    // ignore: unnecessary_parenthesis
+    (enabled.hashCode);
+
+  @override
+  String toString() => 'SystemConfigFFmpegRealtimeDto[enabled=$enabled]';
+
+  Map<String, dynamic> toJson() {
+    final json = <String, dynamic>{};
+      json[r'enabled'] = this.enabled;
+    return json;
+  }
+
+  /// Returns a new [SystemConfigFFmpegRealtimeDto] instance and imports its values from
+  /// [value] if it's a [Map], null otherwise.
+  // ignore: prefer_constructors_over_static_methods
+  static SystemConfigFFmpegRealtimeDto? fromJson(dynamic value) {
+    upgradeDto(value, "SystemConfigFFmpegRealtimeDto");
+    if (value is Map) {
+      final json = value.cast<String, dynamic>();
+
+      return SystemConfigFFmpegRealtimeDto(
+        enabled: mapValueOfType<bool>(json, r'enabled')!,
+      );
+    }
+    return null;
+  }
+
+  static List<SystemConfigFFmpegRealtimeDto> listFromJson(dynamic json, {bool growable = false,}) {
+    final result = <SystemConfigFFmpegRealtimeDto>[];
+    if (json is List && json.isNotEmpty) {
+      for (final row in json) {
+        final value = SystemConfigFFmpegRealtimeDto.fromJson(row);
+        if (value != null) {
+          result.add(value);
+        }
+      }
+    }
+    return result.toList(growable: growable);
+  }
+
+  static Map<String, SystemConfigFFmpegRealtimeDto> mapFromJson(dynamic json) {
+    final map = <String, SystemConfigFFmpegRealtimeDto>{};
+    if (json is Map && json.isNotEmpty) {
+      json = json.cast<String, dynamic>(); // ignore: parameter_assignments
+      for (final entry in json.entries) {
+        final value = SystemConfigFFmpegRealtimeDto.fromJson(entry.value);
+        if (value != null) {
+          map[entry.key] = value;
+        }
+      }
+    }
+    return map;
+  }
+
+  // maps a json object with a list of SystemConfigFFmpegRealtimeDto-objects as value to a dart map
+  static Map<String, List<SystemConfigFFmpegRealtimeDto>> mapListFromJson(dynamic json, {bool growable = false,}) {
+    final map = <String, List<SystemConfigFFmpegRealtimeDto>>{};
+    if (json is Map && json.isNotEmpty) {
+      // ignore: parameter_assignments
+      json = json.cast<String, dynamic>();
+      for (final entry in json.entries) {
+        map[entry.key] = SystemConfigFFmpegRealtimeDto.listFromJson(entry.value, growable: growable,);
+      }
+    }
+    return map;
+  }
+
+  /// The list of required keys that must be present in a JSON.
+  static const requiredKeys = <String>{
+    'enabled',
+  };
+}
+
diff --git a/open-api/immich-openapi-specs.json b/open-api/immich-openapi-specs.json
index badf9ce25d..dffccc0bdd 100644
--- a/open-api/immich-openapi-specs.json
+++ b/open-api/immich-openapi-specs.json
@@ -4288,6 +4288,351 @@
         "x-immich-state": "Stable"
       }
     },
+    "/assets/{id}/video/stream/main.m3u8": {
+      "get": {
+        "description": "Returns an HLS main playlist with all available variants for the asset.",
+        "operationId": "getMainPlaylist",
+        "parameters": [
+          {
+            "name": "id",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "key",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "slug",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/vnd.apple.mpegurl": {
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
+            "description": ""
+          }
+        },
+        "security": [
+          {
+            "bearer": []
+          },
+          {
+            "cookie": []
+          },
+          {
+            "api_key": []
+          }
+        ],
+        "summary": "Get HLS main playlist",
+        "tags": [
+          "Assets"
+        ],
+        "x-immich-history": [
+          {
+            "version": "v3",
+            "state": "Added"
+          },
+          {
+            "version": "v3",
+            "state": "Alpha"
+          }
+        ],
+        "x-immich-permission": "asset.view",
+        "x-immich-state": "Alpha"
+      }
+    },
+    "/assets/{id}/video/stream/{sessionId}": {
+      "delete": {
+        "description": "Releases server resources for the streaming session.",
+        "operationId": "endSession",
+        "parameters": [
+          {
+            "name": "id",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "key",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "sessionId",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "slug",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "204": {
+            "description": ""
+          }
+        },
+        "security": [
+          {
+            "bearer": []
+          },
+          {
+            "cookie": []
+          },
+          {
+            "api_key": []
+          }
+        ],
+        "summary": "End HLS streaming session",
+        "tags": [
+          "Assets"
+        ],
+        "x-immich-history": [
+          {
+            "version": "v3",
+            "state": "Added"
+          },
+          {
+            "version": "v3",
+            "state": "Alpha"
+          }
+        ],
+        "x-immich-permission": "asset.view",
+        "x-immich-state": "Alpha"
+      }
+    },
+    "/assets/{id}/video/stream/{sessionId}/{variantIndex}/playlist.m3u8": {
+      "get": {
+        "description": "Returns an HLS media playlist for one variant of the streaming session.",
+        "operationId": "getMediaPlaylist",
+        "parameters": [
+          {
+            "name": "id",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "key",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "sessionId",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "slug",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "variantIndex",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "minimum": 0,
+              "maximum": 9007199254740991,
+              "type": "integer"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/vnd.apple.mpegurl": {
+                "schema": {
+                  "type": "string"
+                }
+              }
+            },
+            "description": ""
+          }
+        },
+        "security": [
+          {
+            "bearer": []
+          },
+          {
+            "cookie": []
+          },
+          {
+            "api_key": []
+          }
+        ],
+        "summary": "Get HLS media playlist",
+        "tags": [
+          "Assets"
+        ],
+        "x-immich-history": [
+          {
+            "version": "v3",
+            "state": "Added"
+          },
+          {
+            "version": "v3",
+            "state": "Alpha"
+          }
+        ],
+        "x-immich-permission": "asset.view",
+        "x-immich-state": "Alpha"
+      }
+    },
+    "/assets/{id}/video/stream/{sessionId}/{variantIndex}/{filename}": {
+      "get": {
+        "description": "Streams an HLS init segment (init.mp4) or media segment (seg_N.m4s).",
+        "operationId": "getSegment",
+        "parameters": [
+          {
+            "name": "filename",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "pattern": "^(init\\.mp4|seg_\\d+\\.m4s)$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "id",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "key",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "sessionId",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "format": "uuid",
+              "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12})$",
+              "type": "string"
+            }
+          },
+          {
+            "name": "slug",
+            "required": false,
+            "in": "query",
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "variantIndex",
+            "required": true,
+            "in": "path",
+            "schema": {
+              "minimum": 0,
+              "maximum": 9007199254740991,
+              "type": "integer"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "content": {
+              "application/octet-stream": {
+                "schema": {
+                  "format": "binary",
+                  "type": "string"
+                }
+              }
+            },
+            "description": ""
+          }
+        },
+        "security": [
+          {
+            "bearer": []
+          },
+          {
+            "cookie": []
+          },
+          {
+            "api_key": []
+          }
+        ],
+        "summary": "Get HLS segment or init file",
+        "tags": [
+          "Assets"
+        ],
+        "x-immich-history": [
+          {
+            "version": "v3",
+            "state": "Added"
+          },
+          {
+            "version": "v3",
+            "state": "Alpha"
+          }
+        ],
+        "x-immich-permission": "asset.view",
+        "x-immich-state": "Alpha"
+      }
+    },
     "/auth/admin-sign-up": {
       "post": {
         "description": "Create the first admin user in the system.",
@@ -18082,6 +18427,7 @@
           "LibrarySyncFilesQueueAll",
           "LibrarySyncFiles",
           "LibraryScanQueueAll",
+          "HlsSessionCleanup",
           "MemoryCleanup",
           "MemoryGenerate",
           "NotificationsCleanup",
@@ -24040,6 +24386,9 @@
             "description": "Preset",
             "type": "string"
           },
+          "realtime": {
+            "$ref": "#/components/schemas/SystemConfigFFmpegRealtimeDto"
+          },
           "refs": {
             "description": "References",
             "maximum": 6,
@@ -24090,6 +24439,7 @@
           "maxBitrate",
           "preferredHwDevice",
           "preset",
+          "realtime",
           "refs",
           "targetAudioCodec",
           "targetResolution",
@@ -24102,6 +24452,18 @@
         ],
         "type": "object"
       },
+      "SystemConfigFFmpegRealtimeDto": {
+        "properties": {
+          "enabled": {
+            "description": "Enable real-time HLS transcoding (alpha)",
+            "type": "boolean"
+          }
+        },
+        "required": [
+          "enabled"
+        ],
+        "type": "object"
+      },
       "SystemConfigFacesDto": {
         "properties": {
           "import": {
diff --git a/packages/sdk/src/fetch-client.ts b/packages/sdk/src/fetch-client.ts
index e82074d02c..8b5588f245 100644
--- a/packages/sdk/src/fetch-client.ts
+++ b/packages/sdk/src/fetch-client.ts
@@ -2227,6 +2227,10 @@ export type DatabaseBackupConfig = {
 export type SystemConfigBackupsDto = {
     database: DatabaseBackupConfig;
 };
+export type SystemConfigFFmpegRealtimeDto = {
+    /** Enable real-time HLS transcoding (alpha) */
+    enabled: boolean;
+};
 export type SystemConfigFFmpegDto = {
     accel: TranscodeHWAccel;
     /** Accelerated decode */
@@ -2250,6 +2254,7 @@ export type SystemConfigFFmpegDto = {
     preferredHwDevice: string;
     /** Preset */
     preset: string;
+    realtime: SystemConfigFFmpegRealtimeDto;
     /** References */
     refs: number;
     targetAudioCodec: AudioCodec;
@@ -4184,6 +4189,82 @@ export function playAssetVideo({ id, key, slug }: {
         ...opts
     }));
 }
+/**
+ * Get HLS main playlist
+ */
+export function getMainPlaylist({ id, key, slug }: {
+    id: string;
+    key?: string;
+    slug?: string;
+}, opts?: Oazapfts.RequestOpts) {
+    return oazapfts.ok(oazapfts.fetchBlob<{
+        status: 200;
+        data: string;
+    }>(`/assets/${encodeURIComponent(id)}/video/stream/main.m3u8${QS.query(QS.explode({
+        key,
+        slug
+    }))}`, {
+        ...opts
+    }));
+}
+/**
+ * End HLS streaming session
+ */
+export function endSession({ id, key, sessionId, slug }: {
+    id: string;
+    key?: string;
+    sessionId: string;
+    slug?: string;
+}, opts?: Oazapfts.RequestOpts) {
+    return oazapfts.ok(oazapfts.fetchText(`/assets/${encodeURIComponent(id)}/video/stream/${encodeURIComponent(sessionId)}${QS.query(QS.explode({
+        key,
+        slug
+    }))}`, {
+        ...opts,
+        method: "DELETE"
+    }));
+}
+/**
+ * Get HLS media playlist
+ */
+export function getMediaPlaylist({ id, key, sessionId, slug, variantIndex }: {
+    id: string;
+    key?: string;
+    sessionId: string;
+    slug?: string;
+    variantIndex: number;
+}, opts?: Oazapfts.RequestOpts) {
+    return oazapfts.ok(oazapfts.fetchBlob<{
+        status: 200;
+        data: string;
+    }>(`/assets/${encodeURIComponent(id)}/video/stream/${encodeURIComponent(sessionId)}/${encodeURIComponent(variantIndex)}/playlist.m3u8${QS.query(QS.explode({
+        key,
+        slug
+    }))}`, {
+        ...opts
+    }));
+}
+/**
+ * Get HLS segment or init file
+ */
+export function getSegment({ filename, id, key, sessionId, slug, variantIndex }: {
+    filename: string;
+    id: string;
+    key?: string;
+    sessionId: string;
+    slug?: string;
+    variantIndex: number;
+}, opts?: Oazapfts.RequestOpts) {
+    return oazapfts.ok(oazapfts.fetchBlob<{
+        status: 200;
+        data: Blob;
+    }>(`/assets/${encodeURIComponent(id)}/video/stream/${encodeURIComponent(sessionId)}/${encodeURIComponent(variantIndex)}/${encodeURIComponent(filename)}${QS.query(QS.explode({
+        key,
+        slug
+    }))}`, {
+        ...opts
+    }));
+}
 /**
  * Register admin
  */
@@ -7082,6 +7163,7 @@ export enum JobName {
     LibrarySyncFilesQueueAll = "LibrarySyncFilesQueueAll",
     LibrarySyncFiles = "LibrarySyncFiles",
     LibraryScanQueueAll = "LibraryScanQueueAll",
+    HlsSessionCleanup = "HlsSessionCleanup",
     MemoryCleanup = "MemoryCleanup",
     MemoryGenerate = "MemoryGenerate",
     NotificationsCleanup = "NotificationsCleanup",
diff --git a/server/src/config.ts b/server/src/config.ts
index 999e1e45bc..48a7f8aa36 100644
--- a/server/src/config.ts
+++ b/server/src/config.ts
@@ -45,6 +45,9 @@ export type SystemConfig = {
     accel: TranscodeHardwareAcceleration;
     accelDecode: boolean;
     tonemap: ToneMapping;
+    realtime: {
+      enabled: boolean;
+    };
   };
   job: Record<ConcurrentQueueName, { concurrency: number }>;
   logging: {
@@ -224,6 +227,9 @@ export const defaults = Object.freeze<SystemConfig>({
     tonemap: ToneMapping.Hable,
     accel: TranscodeHardwareAcceleration.Disabled,
     accelDecode: true,
+    realtime: {
+      enabled: false,
+    },
   },
   job: {
     [QueueName.BackgroundTask]: { concurrency: 5 },
diff --git a/server/src/constants.ts b/server/src/constants.ts
index 9f8cdbefdb..16b7731dce 100644
--- a/server/src/constants.ts
+++ b/server/src/constants.ts
@@ -1,7 +1,15 @@
 import { readFileSync } from 'node:fs';
 import { dirname, join } from 'node:path';
 import { SemVer } from 'semver';
-import { ApiTag, AudioCodec, DatabaseExtension, ExifOrientation, VectorIndex } from 'src/enum';
+import {
+  ApiTag,
+  AudioCodec,
+  DatabaseExtension,
+  ExifOrientation,
+  TranscodeHardwareAcceleration,
+  VectorIndex,
+  VideoCodec,
+} from 'src/enum';
 
 export const IMMICH_SERVER_START = 'Immich Server is listening';
 
@@ -202,3 +210,32 @@ export const AUDIO_ENCODER: Record<AudioCodec, string> = {
   [AudioCodec.Opus]: 'libopus',
   [AudioCodec.PcmS16le]: 'pcm_s16le',
 };
+
+export const SUPPORTED_HWA_CODECS: Record<TranscodeHardwareAcceleration, VideoCodec[]> = {
+  [TranscodeHardwareAcceleration.Nvenc]: [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Av1],
+  [TranscodeHardwareAcceleration.Qsv]: [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Vp9, VideoCodec.Av1],
+  [TranscodeHardwareAcceleration.Vaapi]: [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Vp9, VideoCodec.Av1],
+  [TranscodeHardwareAcceleration.Rkmpp]: [VideoCodec.H264, VideoCodec.Hevc],
+  [TranscodeHardwareAcceleration.Disabled]: [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Vp9, VideoCodec.Av1],
+};
+
+export const HLS_BACKPRESSURE_PAUSE_SEGMENTS = 30;
+export const HLS_BACKPRESSURE_RESUME_SEGMENTS = 15;
+export const HLS_CLEANUP_INTERVAL_MS = 60 * 1000;
+export const HLS_INACTIVITY_TIMEOUT_MS = 5 * 60 * 1000;
+export const HLS_LEASE_DURATION_MS = 30 * 60 * 1000;
+export const HLS_PLAYLIST_CONTENT_TYPE = 'application/vnd.apple.mpegurl';
+export const HLS_SEGMENT_DURATION = 2;
+export const HLS_SEGMENT_FILENAME_REGEX = /^seg_(\d+)\.m4s$/;
+export const HLS_VARIANTS = [
+  { resolution: 480, codec: VideoCodec.Av1, bitrate: 1_000_000, codecString: 'av01.0.04M.08' },
+  { resolution: 480, codec: VideoCodec.Hevc, bitrate: 1_200_000, codecString: 'hvc1.1.6.L90.B0' },
+  { resolution: 480, codec: VideoCodec.H264, bitrate: 2_500_000, codecString: 'avc1.64001e' },
+  { resolution: 720, codec: VideoCodec.Av1, bitrate: 2_000_000, codecString: 'av01.0.08M.08' },
+  { resolution: 720, codec: VideoCodec.Hevc, bitrate: 2_500_000, codecString: 'hvc1.1.6.L93.B0' },
+  { resolution: 720, codec: VideoCodec.H264, bitrate: 5_000_000, codecString: 'avc1.64001f' },
+  { resolution: 1080, codec: VideoCodec.Av1, bitrate: 4_000_000, codecString: 'av01.0.09M.08' },
+  { resolution: 1080, codec: VideoCodec.Hevc, bitrate: 4_500_000, codecString: 'hvc1.1.6.L120.B0' },
+  { resolution: 1080, codec: VideoCodec.H264, bitrate: 8_000_000, codecString: 'avc1.640028' },
+];
+export const HLS_VERSION = 7;
diff --git a/server/src/controllers/index.ts b/server/src/controllers/index.ts
index dc3754ce24..336ea1cf91 100644
--- a/server/src/controllers/index.ts
+++ b/server/src/controllers/index.ts
@@ -35,6 +35,7 @@ import { TimelineController } from 'src/controllers/timeline.controller';
 import { TrashController } from 'src/controllers/trash.controller';
 import { UserAdminController } from 'src/controllers/user-admin.controller';
 import { UserController } from 'src/controllers/user.controller';
+import { VideoStreamController } from 'src/controllers/video-stream.controller';
 import { ViewController } from 'src/controllers/view.controller';
 import { WorkflowController } from 'src/controllers/workflow.controller';
 
@@ -76,6 +77,7 @@ export const controllers = [
   TrashController,
   UserAdminController,
   UserController,
+  VideoStreamController,
   ViewController,
   WorkflowController,
 ];
diff --git a/server/src/controllers/video-stream.controller.ts b/server/src/controllers/video-stream.controller.ts
new file mode 100644
index 0000000000..8707584361
--- /dev/null
+++ b/server/src/controllers/video-stream.controller.ts
@@ -0,0 +1,79 @@
+import { Controller, Delete, Get, Header, HttpCode, HttpStatus, Next, Param, Res } from '@nestjs/common';
+import { ApiProduces, ApiTags } from '@nestjs/swagger';
+import { NextFunction, Response } from 'express';
+import { HLS_PLAYLIST_CONTENT_TYPE } from 'src/constants';
+import { Endpoint, HistoryBuilder } from 'src/decorators';
+import { AuthDto } from 'src/dtos/auth.dto';
+import { HlsSegmentParamDto, HlsSessionParamDto, HlsVariantParamDto } from 'src/dtos/streaming.dto';
+import { ApiTag, Permission, RouteKey } from 'src/enum';
+import { Auth, Authenticated, FileResponse } from 'src/middleware/auth.guard';
+import { LoggingRepository } from 'src/repositories/logging.repository';
+import { HlsService } from 'src/services/hls.service';
+import { sendFile } from 'src/utils/file';
+import { UUIDParamDto } from 'src/validation';
+
+@ApiTags(ApiTag.Assets)
+@Controller(RouteKey.Asset)
+export class VideoStreamController {
+  constructor(
+    private logger: LoggingRepository,
+    private service: HlsService,
+  ) {}
+
+  @Get(':id/video/stream/main.m3u8')
+  @Authenticated({ permission: Permission.AssetView, sharedLink: true })
+  @Header('Cache-Control', 'no-cache')
+  @Header('Content-Type', HLS_PLAYLIST_CONTENT_TYPE)
+  @ApiProduces(HLS_PLAYLIST_CONTENT_TYPE)
+  @Endpoint({
+    summary: 'Get HLS main playlist',
+    description: 'Returns an HLS main playlist with all available variants for the asset.',
+    history: new HistoryBuilder().added('v3').alpha('v3'),
+  })
+  getMainPlaylist(@Auth() auth: AuthDto, @Param() { id }: UUIDParamDto) {
+    return this.service.getMainPlaylist(auth, id);
+  }
+
+  @Get(':id/video/stream/:sessionId/:variantIndex/playlist.m3u8')
+  @Authenticated({ permission: Permission.AssetView, sharedLink: true })
+  @Header('Cache-Control', 'no-cache')
+  @Header('Content-Type', HLS_PLAYLIST_CONTENT_TYPE)
+  @ApiProduces(HLS_PLAYLIST_CONTENT_TYPE)
+  @Endpoint({
+    summary: 'Get HLS media playlist',
+    description: 'Returns an HLS media playlist for one variant of the streaming session.',
+    history: new HistoryBuilder().added('v3').alpha('v3'),
+  })
+  getMediaPlaylist(@Auth() auth: AuthDto, @Param() { id, sessionId }: HlsVariantParamDto) {
+    return this.service.getMediaPlaylist(auth, id, sessionId);
+  }
+
+  @Get(':id/video/stream/:sessionId/:variantIndex/:filename')
+  @FileResponse()
+  @Authenticated({ permission: Permission.AssetView, sharedLink: true })
+  @Endpoint({
+    summary: 'Get HLS segment or init file',
+    description: 'Streams an HLS init segment (init.mp4) or media segment (seg_N.m4s).',
+    history: new HistoryBuilder().added('v3').alpha('v3'),
+  })
+  async getSegment(
+    @Auth() auth: AuthDto,
+    @Param() { id, sessionId, variantIndex, filename }: HlsSegmentParamDto,
+    @Res() res: Response,
+    @Next() next: NextFunction,
+  ) {
+    await sendFile(res, next, () => this.service.getSegment(auth, id, sessionId, variantIndex, filename), this.logger);
+  }
+
+  @Delete(':id/video/stream/:sessionId')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  @Authenticated({ permission: Permission.AssetView, sharedLink: true })
+  @Endpoint({
+    summary: 'End HLS streaming session',
+    description: 'Releases server resources for the streaming session.',
+    history: new HistoryBuilder().added('v3').alpha('v3'),
+  })
+  async endSession(@Auth() auth: AuthDto, @Param() { id, sessionId }: HlsSessionParamDto) {
+    await this.service.endSession(auth, id, sessionId);
+  }
+}
diff --git a/server/src/cores/storage.core.ts b/server/src/cores/storage.core.ts
index d40518762d..8802145020 100644
--- a/server/src/cores/storage.core.ts
+++ b/server/src/cores/storage.core.ts
@@ -35,6 +35,10 @@ export interface MoveRequest {
 
 export type ThumbnailPathEntity = { id: string; ownerId: string };
 
+export type HlsSessionFolder = { ownerId: string; sessionId: string };
+
+export type HlsVariantFolder = { ownerId: string; sessionId: string; variantIndex: number };
+
 export type ImagePathOptions = { fileType: AssetFileType; format: ImageFormat | RawExtractedFormat; isEdited: boolean };
 
 let instance: StorageCore | null;
@@ -125,6 +129,14 @@ export class StorageCore {
     return StorageCore.getNestedPath(StorageFolder.EncodedVideo, asset.ownerId, `${asset.id}.mp4`);
   }
 
+  static getHlsSessionFolder({ ownerId, sessionId }: HlsSessionFolder) {
+    return StorageCore.getNestedPath(StorageFolder.EncodedVideo, ownerId, sessionId);
+  }
+
+  static getHlsVariantFolder({ ownerId, sessionId, variantIndex }: HlsVariantFolder) {
+    return join(StorageCore.getHlsSessionFolder({ ownerId, sessionId }), variantIndex.toString());
+  }
+
   static getAndroidMotionPath(asset: ThumbnailPathEntity, uuid: string) {
     return StorageCore.getNestedPath(StorageFolder.EncodedVideo, asset.ownerId, `${uuid}-MP.mp4`);
   }
diff --git a/server/src/dtos/streaming.dto.ts b/server/src/dtos/streaming.dto.ts
new file mode 100644
index 0000000000..5270e45fc2
--- /dev/null
+++ b/server/src/dtos/streaming.dto.ts
@@ -0,0 +1,26 @@
+import { createZodDto } from 'nestjs-zod';
+import z from 'zod';
+
+const HlsSessionParamSchema = z.object({
+  id: z.uuidv4(),
+  sessionId: z.uuidv4(),
+});
+
+export class HlsSessionParamDto extends createZodDto(HlsSessionParamSchema) {}
+
+const HlsVariantParamSchema = z.object({
+  id: z.uuidv4(),
+  sessionId: z.uuidv4(),
+  variantIndex: z.coerce.number().int().min(0),
+});
+
+export class HlsVariantParamDto extends createZodDto(HlsVariantParamSchema) {}
+
+const HlsSegmentParamSchema = z.object({
+  id: z.uuidv4(),
+  sessionId: z.uuidv4(),
+  variantIndex: z.coerce.number().int().min(0),
+  filename: z.string().regex(/^(init\.mp4|seg_\d+\.m4s)$/, { error: 'Invalid HLS segment filename' }),
+});
+
+export class HlsSegmentParamDto extends createZodDto(HlsSegmentParamSchema) {}
diff --git a/server/src/dtos/system-config.dto.ts b/server/src/dtos/system-config.dto.ts
index 94c1aa36b0..efb31f92a3 100644
--- a/server/src/dtos/system-config.dto.ts
+++ b/server/src/dtos/system-config.dto.ts
@@ -79,6 +79,11 @@ const SystemConfigFFmpegSchema = z
     accel: TranscodeHardwareAccelerationSchema,
     accelDecode: configBool.describe('Accelerated decode'),
     tonemap: ToneMappingSchema,
+    realtime: z
+      .object({
+        enabled: configBool.describe('Enable real-time HLS transcoding (alpha)'),
+      })
+      .meta({ id: 'SystemConfigFFmpegRealtimeDto' }),
   })
   .meta({ id: 'SystemConfigFFmpegDto' });
 
diff --git a/server/src/enum.ts b/server/src/enum.ts
index bc52e65f83..42d428500e 100644
--- a/server/src/enum.ts
+++ b/server/src/enum.ts
@@ -452,11 +452,7 @@ export enum VideoCodec {
 
 export const VideoCodecSchema = z.enum(VideoCodec).describe('Target video codec').meta({ id: 'VideoCodec' });
 
-export enum VideoSegmentCodec {
-  Av1 = 'av1',
-  Hevc = 'hevc',
-  H264 = 'h264',
-}
+export type VideoSegmentCodec = VideoCodec.Av1 | VideoCodec.Hevc | VideoCodec.H264;
 
 export enum AudioCodec {
   Mp3 = 'mp3',
@@ -826,6 +822,8 @@ export enum JobName {
   LibrarySyncFiles = 'LibrarySyncFiles',
   LibraryScanQueueAll = 'LibraryScanQueueAll',
 
+  HlsSessionCleanup = 'HlsSessionCleanup',
+
   MemoryCleanup = 'MemoryCleanup',
   MemoryGenerate = 'MemoryGenerate',
 
@@ -919,6 +917,7 @@ export enum DatabaseLock {
   MaintenanceOperation = 621,
   MemoryCreation = 777,
   VersionCheck = 800,
+  HlsSessionCleanup = 850,
 }
 
 export enum MaintenanceAction {
diff --git a/server/src/queries/video.stream.repository.sql b/server/src/queries/video.stream.repository.sql
index c77882d77d..714e138ce8 100644
--- a/server/src/queries/video.stream.repository.sql
+++ b/server/src/queries/video.stream.repository.sql
@@ -7,6 +7,7 @@ from
   "video_stream_session"
 where
   "id" = $1
+  and "expiresAt" > $2
 
 -- VideoStreamRepository.getVariant
 select
@@ -27,11 +28,13 @@ where
 
 -- VideoStreamRepository.getExpiredSessions
 select
-  "id"
+  "video_stream_session"."id",
+  "asset"."ownerId"
 from
   "video_stream_session"
+  inner join "asset" on "asset"."id" = "video_stream_session"."assetId"
 where
-  "expiresAt" <= $1
+  "video_stream_session"."expiresAt" <= $1
 
 -- VideoStreamRepository.extendSession
 update "video_stream_session"
@@ -44,3 +47,253 @@ where
 delete from "video_stream_session"
 where
   "id" = $1
+
+-- VideoStreamRepository.getForMainPlaylist
+select
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_video"."index",
+          "asset_video"."codecName",
+          "asset_video"."profile",
+          "asset_video"."level",
+          "asset_video"."bitrate",
+          "asset_exif"."exifImageWidth" as "width",
+          "asset_exif"."exifImageHeight" as "height",
+          "asset_video"."pixelFormat",
+          "asset_video"."frameCount",
+          "asset_exif"."fps" as "frameRate",
+          "asset_video"."timeBase",
+          case
+            when "asset_exif"."orientation" = '6' then -90
+            when "asset_exif"."orientation" = '8' then 90
+            when "asset_exif"."orientation" = '3' then 180
+            else 0
+          end as "rotation",
+          "asset_video"."colorPrimaries",
+          "asset_video"."colorMatrix",
+          "asset_video"."colorTransfer",
+          "asset_video"."dvProfile",
+          "asset_video"."dvLevel",
+          "asset_video"."dvBlSignalCompatibilityId"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_video"."assetId" is not null
+      ) as obj
+  ) as "videoStream",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_keyframe"."pts" as "keyframePts",
+          "asset_keyframe"."accDuration" as "keyframeAccDuration",
+          "asset_keyframe"."ownDuration" as "keyframeOwnDuration",
+          "asset_keyframe"."totalDuration",
+          "asset_keyframe"."packetCount",
+          "asset_keyframe"."outputFrames"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_keyframe"."assetId" is not null
+      ) as obj
+  ) as "packets"
+from
+  "asset"
+  inner join "asset_exif" on "asset"."id" = "asset_exif"."assetId"
+  inner join "asset_video" on "asset"."id" = "asset_video"."assetId"
+  inner join "asset_keyframe" on "asset"."id" = "asset_keyframe"."assetId"
+where
+  "asset"."id" = $1
+
+-- VideoStreamRepository.getForMediaPlaylist
+select
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_video"."index",
+          "asset_video"."codecName",
+          "asset_video"."profile",
+          "asset_video"."level",
+          "asset_video"."bitrate",
+          "asset_exif"."exifImageWidth" as "width",
+          "asset_exif"."exifImageHeight" as "height",
+          "asset_video"."pixelFormat",
+          "asset_video"."frameCount",
+          "asset_exif"."fps" as "frameRate",
+          "asset_video"."timeBase",
+          case
+            when "asset_exif"."orientation" = '6' then -90
+            when "asset_exif"."orientation" = '8' then 90
+            when "asset_exif"."orientation" = '3' then 180
+            else 0
+          end as "rotation",
+          "asset_video"."colorPrimaries",
+          "asset_video"."colorMatrix",
+          "asset_video"."colorTransfer",
+          "asset_video"."dvProfile",
+          "asset_video"."dvLevel",
+          "asset_video"."dvBlSignalCompatibilityId"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_video"."assetId" is not null
+      ) as obj
+  ) as "videoStream",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_keyframe"."pts" as "keyframePts",
+          "asset_keyframe"."accDuration" as "keyframeAccDuration",
+          "asset_keyframe"."ownDuration" as "keyframeOwnDuration",
+          "asset_keyframe"."totalDuration",
+          "asset_keyframe"."packetCount",
+          "asset_keyframe"."outputFrames"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_keyframe"."assetId" is not null
+      ) as obj
+  ) as "packets"
+from
+  "asset"
+  inner join "asset_exif" on "asset"."id" = "asset_exif"."assetId"
+  inner join "video_stream_session" on "asset"."id" = "video_stream_session"."assetId"
+  inner join "asset_video" on "asset"."id" = "asset_video"."assetId"
+  inner join "asset_keyframe" on "asset"."id" = "asset_keyframe"."assetId"
+where
+  "asset"."id" = $1
+  and "video_stream_session"."id" = $2
+  and "video_stream_session"."expiresAt" > $3
+
+-- VideoStreamRepository.getForTranscoding
+select
+  "asset"."originalPath",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_audio"."index",
+          "asset_audio"."codecName",
+          "asset_audio"."profile",
+          "asset_audio"."bitrate"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_audio"."assetId" is not null
+      ) as obj
+  ) as "audioStream",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_video"."index",
+          "asset_video"."codecName",
+          "asset_video"."profile",
+          "asset_video"."level",
+          "asset_video"."bitrate",
+          "asset_exif"."exifImageWidth" as "width",
+          "asset_exif"."exifImageHeight" as "height",
+          "asset_video"."pixelFormat",
+          "asset_video"."frameCount",
+          "asset_exif"."fps" as "frameRate",
+          "asset_video"."timeBase",
+          case
+            when "asset_exif"."orientation" = '6' then -90
+            when "asset_exif"."orientation" = '8' then 90
+            when "asset_exif"."orientation" = '3' then 180
+            else 0
+          end as "rotation",
+          "asset_video"."colorPrimaries",
+          "asset_video"."colorMatrix",
+          "asset_video"."colorTransfer",
+          "asset_video"."dvProfile",
+          "asset_video"."dvLevel",
+          "asset_video"."dvBlSignalCompatibilityId"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_video"."assetId" is not null
+      ) as obj
+  ) as "videoStream",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_video"."formatName",
+          "asset_video"."formatLongName",
+          "asset"."duration",
+          "asset_video"."bitrate"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_video"."assetId" is not null
+      ) as obj
+  ) as "format",
+  (
+    select
+      to_json(obj)
+    from
+      (
+        select
+          "asset_keyframe"."pts" as "keyframePts",
+          "asset_keyframe"."accDuration" as "keyframeAccDuration",
+          "asset_keyframe"."ownDuration" as "keyframeOwnDuration",
+          "asset_keyframe"."totalDuration",
+          "asset_keyframe"."packetCount",
+          "asset_keyframe"."outputFrames"
+        from
+          (
+            select
+              1
+          ) as "dummy"
+        where
+          "asset_keyframe"."assetId" is not null
+      ) as obj
+  ) as "packets"
+from
+  "asset"
+  inner join "asset_exif" on "asset"."id" = "asset_exif"."assetId"
+  left join "asset_audio" on "asset"."id" = "asset_audio"."assetId"
+  inner join "asset_video" on "asset"."id" = "asset_video"."assetId"
+  inner join "asset_keyframe" on "asset"."id" = "asset_keyframe"."assetId"
+where
+  "asset"."id" = $1
diff --git a/server/src/repositories/event.repository.ts b/server/src/repositories/event.repository.ts
index 713828cd95..5de5cdfe29 100644
--- a/server/src/repositories/event.repository.ts
+++ b/server/src/repositories/event.repository.ts
@@ -92,6 +92,14 @@ type EventMap = {
 
   AuthChangePassword: [{ userId: string; currentSessionId?: string; invalidateSessions?: boolean }];
 
+  // hls streaming events
+  HlsSegmentRequest: [{ sessionId: string; assetId: string; variantIndex: number; segmentIndex: number }];
+  HlsSegmentResult: [{ sessionId: string; variantIndex: number; segmentIndex: number; error?: string }];
+  HlsHeartbeat: [{ sessionId: string; variantIndex?: number; segmentIndex?: number }];
+  HlsSessionRequest: [{ sessionId: string; assetId: string; ownerId: string }];
+  HlsSessionResult: [{ sessionId: string; error?: string }];
+  HlsSessionEnd: [{ sessionId: string }];
+
   // websocket events
   WebsocketConnect: [{ userId: string }];
 };
diff --git a/server/src/repositories/media.repository.ts b/server/src/repositories/media.repository.ts
index fa08ba8701..c2ec95636a 100644
--- a/server/src/repositories/media.repository.ts
+++ b/server/src/repositories/media.repository.ts
@@ -490,18 +490,43 @@ export class MediaRepository {
     return this.parseInt(b.bit_rate) - this.parseInt(a.bit_rate);
   }
 
+  /* Ported from https://code.ffmpeg.org/FFmpeg/FFmpeg/src/commit/5c44245878e235ae64fe87fb9877644856d33d1d/fftools/ffmpeg_filter.c
+   * SPDX-License-Identifier: LGPL-2.1-or-later
+   * Copyright (c) FFmpeg authors and contributors — https://ffmpeg.org/
+   * Modifications: TS port operating on probe-derived packet metadata rather than decoded AVFrames. */
   private cfrOutputFrames(packets: { pts: number; duration: number }[], slotsPerTick: number) {
-    // Packets may be out of PTS order due to B-frames
     packets.sort((a, b) => a.pts - b.pts);
     const firstPts = packets[0].pts;
     let outputFrames = 0;
     let nextPts = 0;
+    const history = [0, 0, 0];
     for (const pkt of packets) {
-      const delta = (pkt.pts - firstPts) * slotsPerTick - nextPts + pkt.duration * slotsPerTick;
-      const nb = delta < -1.1 ? 0 : delta > 1.1 ? Math.round(delta) : 1;
+      const syncIpts = (pkt.pts - firstPts) * slotsPerTick;
+      const duration = pkt.duration * slotsPerTick;
+      let delta0 = syncIpts - nextPts;
+      const delta = delta0 + duration;
+
+      if (delta0 < 0 && delta > 0) {
+        delta0 = 0;
+      }
+
+      let nb = 1;
+      let nbPrev = 0;
+      if (delta < -1.1) {
+        nb = 0;
+      } else if (delta > 1.1) {
+        nb = Math.round(delta);
+        if (delta0 > 1.1) {
+          nbPrev = Math.round(delta0 - 0.6);
+        }
+      }
       outputFrames += nb;
       nextPts += nb;
+      history[2] = history[1];
+      history[1] = history[0];
+      history[0] = nbPrev;
     }
-    return outputFrames;
+    const median = history.sort((a, b) => a - b)[1];
+    return outputFrames + median;
   }
 }
diff --git a/server/src/repositories/process.repository.ts b/server/src/repositories/process.repository.ts
index 9d8cac1f40..928531408f 100644
--- a/server/src/repositories/process.repository.ts
+++ b/server/src/repositories/process.repository.ts
@@ -1,12 +1,10 @@
 import { Injectable } from '@nestjs/common';
-import { ChildProcessWithoutNullStreams, fork, spawn, SpawnOptionsWithoutStdio } from 'node:child_process';
+import { fork, spawn, SpawnOptionsWithoutStdio } from 'node:child_process';
 import { Duplex } from 'node:stream';
 
 @Injectable()
 export class ProcessRepository {
-  spawn(command: string, args?: readonly string[], options?: SpawnOptionsWithoutStdio): ChildProcessWithoutNullStreams {
-    return spawn(command, args, options);
-  }
+  spawn = spawn;
 
   spawnDuplexStream(command: string, args?: readonly string[], options?: SpawnOptionsWithoutStdio): Duplex {
     let stdinClosed = false;
diff --git a/server/src/repositories/storage.repository.ts b/server/src/repositories/storage.repository.ts
index 1d3971fd28..9604372fbe 100644
--- a/server/src/repositories/storage.repository.ts
+++ b/server/src/repositories/storage.repository.ts
@@ -10,6 +10,7 @@ import {
   existsSync,
   mkdirSync,
   ReadOptionsWithBuffer,
+  watch,
 } from 'node:fs';
 import fs from 'node:fs/promises';
 import path from 'node:path';
@@ -277,6 +278,8 @@ export class StorageRepository {
     return () => watcher.close();
   }
 
+  watchDir = watch; // Native fs.watch without chokidar overhead
+
   private asGlob(pathToCrawl: string): string {
     const escapedPath = escapePath(pathToCrawl).replaceAll('"', '["]').replaceAll("'", "[']").replaceAll('`', '[`]');
     const extensions = `*{${mimeTypes.getSupportedFileExtensions().join(',')}}`;
diff --git a/server/src/repositories/video-stream.repository.ts b/server/src/repositories/video-stream.repository.ts
index e23ee4ca4c..43c5ef80f0 100644
--- a/server/src/repositories/video-stream.repository.ts
+++ b/server/src/repositories/video-stream.repository.ts
@@ -8,6 +8,7 @@ import {
   VideoStreamSessionTable,
   VideoStreamVariantTable,
 } from 'src/schema/tables/video-stream.table';
+import { withAudioStream, withVideoFormat, withVideoPackets, withVideoStream } from 'src/utils/database';
 
 @Injectable()
 export class VideoStreamRepository {
@@ -27,7 +28,12 @@ export class VideoStreamRepository {
 
   @GenerateSql({ params: [DummyValue.UUID] })
   getSession(id: string) {
-    return this.db.selectFrom('video_stream_session').selectAll().where('id', '=', id).executeTakeFirst();
+    return this.db
+      .selectFrom('video_stream_session')
+      .selectAll()
+      .where('id', '=', id)
+      .where('expiresAt', '>', new Date())
+      .executeTakeFirst();
   }
 
   @GenerateSql({ params: [DummyValue.UUID] })
@@ -47,7 +53,12 @@ export class VideoStreamRepository {
 
   @GenerateSql()
   getExpiredSessions() {
-    return this.db.selectFrom('video_stream_session').select(['id']).where('expiresAt', '<=', new Date()).execute();
+    return this.db
+      .selectFrom('video_stream_session')
+      .innerJoin('asset', 'asset.id', 'video_stream_session.assetId')
+      .select(['video_stream_session.id', 'asset.ownerId'])
+      .where('video_stream_session.expiresAt', '<=', new Date())
+      .execute();
   }
 
   @GenerateSql({ params: [DummyValue.UUID, DummyValue.DATE] })
@@ -59,4 +70,50 @@ export class VideoStreamRepository {
   async deleteSession(id: string) {
     await this.db.deleteFrom('video_stream_session').where('id', '=', id).execute();
   }
+
+  @GenerateSql({ params: [DummyValue.UUID] })
+  async getForMainPlaylist(id: string) {
+    return this.db
+      .selectFrom('asset')
+      .innerJoin('asset_exif', 'asset.id', 'asset_exif.assetId')
+      .where('asset.id', '=', id)
+      .innerJoin('asset_video', 'asset.id', 'asset_video.assetId')
+      .innerJoin('asset_keyframe', 'asset.id', 'asset_keyframe.assetId')
+      .select((eb) => withVideoStream(eb).$notNull().as('videoStream'))
+      .select((eb) => withVideoPackets(eb).$notNull().as('packets'))
+      .executeTakeFirst();
+  }
+
+  @GenerateSql({ params: [DummyValue.UUID, DummyValue.UUID] })
+  async getForMediaPlaylist(id: string, sessionId: string) {
+    return this.db
+      .selectFrom('asset')
+      .innerJoin('asset_exif', 'asset.id', 'asset_exif.assetId')
+      .innerJoin('video_stream_session', 'asset.id', 'video_stream_session.assetId')
+      .where('asset.id', '=', id)
+      .where('video_stream_session.id', '=', sessionId)
+      .where('video_stream_session.expiresAt', '>', new Date())
+      .innerJoin('asset_video', 'asset.id', 'asset_video.assetId')
+      .innerJoin('asset_keyframe', 'asset.id', 'asset_keyframe.assetId')
+      .select((eb) => withVideoStream(eb).$notNull().as('videoStream'))
+      .select((eb) => withVideoPackets(eb).$notNull().as('packets'))
+      .executeTakeFirst();
+  }
+
+  @GenerateSql({ params: [DummyValue.UUID] })
+  async getForTranscoding(id: string) {
+    return this.db
+      .selectFrom('asset')
+      .innerJoin('asset_exif', 'asset.id', 'asset_exif.assetId')
+      .where('asset.id', '=', id)
+      .leftJoin('asset_audio', 'asset.id', 'asset_audio.assetId')
+      .innerJoin('asset_video', 'asset.id', 'asset_video.assetId')
+      .innerJoin('asset_keyframe', 'asset.id', 'asset_keyframe.assetId')
+      .select('asset.originalPath')
+      .select((eb) => withAudioStream(eb).as('audioStream'))
+      .select((eb) => withVideoStream(eb).$notNull().as('videoStream'))
+      .select((eb) => withVideoFormat(eb).$notNull().as('format'))
+      .select((eb) => withVideoPackets(eb).$notNull().as('packets'))
+      .executeTakeFirst();
+  }
 }
diff --git a/server/src/repositories/websocket.repository.ts b/server/src/repositories/websocket.repository.ts
index b4a0fcc00a..4f2ab07ced 100644
--- a/server/src/repositories/websocket.repository.ts
+++ b/server/src/repositories/websocket.repository.ts
@@ -16,7 +16,16 @@ import { AppRestartEvent, ArgsOf, EventRepository } from 'src/repositories/event
 import { LoggingRepository } from 'src/repositories/logging.repository';
 import { handlePromiseError } from 'src/utils/misc';
 
-export const serverEvents = ['ConfigUpdate', 'AppRestart'] as const;
+export const serverEvents = [
+  'ConfigUpdate',
+  'AppRestart',
+  'HlsSegmentRequest',
+  'HlsSegmentResult',
+  'HlsHeartbeat',
+  'HlsSessionRequest',
+  'HlsSessionResult',
+  'HlsSessionEnd',
+] as const;
 export type ServerEvents = (typeof serverEvents)[number];
 
 export interface ClientEventMap {
diff --git a/server/src/schema/enums.ts b/server/src/schema/enums.ts
index 73f8133441..ecf559c39d 100644
--- a/server/src/schema/enums.ts
+++ b/server/src/schema/enums.ts
@@ -1,12 +1,5 @@
 import { registerEnum } from '@immich/sql-tools';
-import {
-  AlbumUserRole,
-  AssetStatus,
-  AssetVisibility,
-  ChecksumAlgorithm,
-  SourceType,
-  VideoSegmentCodec,
-} from 'src/enum';
+import { AlbumUserRole, AssetStatus, AssetVisibility, ChecksumAlgorithm, SourceType, VideoCodec } from 'src/enum';
 
 export const album_user_role_enum = registerEnum({
   name: 'album_user_role_enum',
@@ -35,5 +28,5 @@ export const asset_checksum_algorithm_enum = registerEnum({
 
 export const video_stream_variant_codec_enum = registerEnum({
   name: 'video_stream_variant_codec_enum',
-  values: Object.values(VideoSegmentCodec),
+  values: [VideoCodec.Av1, VideoCodec.Hevc, VideoCodec.H264],
 });
diff --git a/server/src/services/hls.service.spec.ts b/server/src/services/hls.service.spec.ts
new file mode 100644
index 0000000000..6a6b998df5
--- /dev/null
+++ b/server/src/services/hls.service.spec.ts
@@ -0,0 +1,333 @@
+import { BadRequestException, NotFoundException } from '@nestjs/common';
+import { TranscodeHardwareAcceleration } from 'src/enum';
+import { HlsService } from 'src/services/hls.service';
+import { eiffelTower, train, waterfall } from 'test/fixtures/media.stub';
+import { factory } from 'test/small.factory';
+import { newTestService, ServiceMocks } from 'test/utils';
+
+// EXTINF values come from FFmpeg's playlist to enforce an exact match
+const eiffelExpectedMediaPlaylist = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-TARGETDURATION:2
+#EXT-X-MEDIA-SEQUENCE:0
+#EXT-X-PLAYLIST-TYPE:VOD
+#EXT-X-MAP:URI="init.mp4"
+#EXTINF:2.007222,
+seg_0.m4s
+#EXTINF:2.007222,
+seg_1.m4s
+#EXTINF:2.007222,
+seg_2.m4s
+#EXTINF:2.007222,
+seg_3.m4s
+#EXTINF:2.007222,
+seg_4.m4s
+#EXTINF:2.007222,
+seg_5.m4s
+#EXTINF:2.007222,
+seg_6.m4s
+#EXTINF:2.007222,
+seg_7.m4s
+#EXTINF:2.007222,
+seg_8.m4s
+#EXTINF:2.007222,
+seg_9.m4s
+#EXTINF:2.007222,
+seg_10.m4s
+#EXTINF:0.281011,
+seg_11.m4s
+#EXT-X-ENDLIST
+`;
+
+const waterfallExpectedMediaPlaylist = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-TARGETDURATION:2
+#EXT-X-MEDIA-SEQUENCE:0
+#EXT-X-PLAYLIST-TYPE:VOD
+#EXT-X-MAP:URI="init.mp4"
+#EXTINF:2.011405,
+seg_0.m4s
+#EXTINF:2.011405,
+seg_1.m4s
+#EXTINF:2.011405,
+seg_2.m4s
+#EXTINF:2.011405,
+seg_3.m4s
+#EXTINF:2.011405,
+seg_4.m4s
+#EXTINF:0.301711,
+seg_5.m4s
+#EXT-X-ENDLIST
+`;
+
+const trainExpectedMediaPlaylist = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-TARGETDURATION:2
+#EXT-X-MEDIA-SEQUENCE:0
+#EXT-X-PLAYLIST-TYPE:VOD
+#EXT-X-MAP:URI="init.mp4"
+#EXTINF:2.000000,
+seg_0.m4s
+#EXTINF:2.000000,
+seg_1.m4s
+#EXTINF:2.000000,
+seg_2.m4s
+#EXTINF:2.000000,
+seg_3.m4s
+#EXTINF:2.000000,
+seg_4.m4s
+#EXTINF:2.000000,
+seg_5.m4s
+#EXTINF:2.000000,
+seg_6.m4s
+#EXTINF:2.000000,
+seg_7.m4s
+#EXTINF:2.000000,
+seg_8.m4s
+#EXTINF:2.000000,
+seg_9.m4s
+#EXTINF:1.733333,
+seg_10.m4s
+#EXT-X-ENDLIST
+`;
+
+const sessionId = '00000000-0000-0000-0000-000000000000';
+
+const eiffelExpectedMasterDisabled = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=480x852,CODECS="av01.0.04M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/0/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=1200000,RESOLUTION=480x852,CODECS="hvc1.1.6.L90.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/1/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=480x852,CODECS="avc1.64001e,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/2/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=720x1280,CODECS="av01.0.08M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/3/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=720x1280,CODECS="hvc1.1.6.L93.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/4/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=5000000,RESOLUTION=720x1280,CODECS="avc1.64001f,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/5/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=4000000,RESOLUTION=1080x1920,CODECS="av01.0.09M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/6/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=4500000,RESOLUTION=1080x1920,CODECS="hvc1.1.6.L120.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/7/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=8000000,RESOLUTION=1080x1920,CODECS="avc1.640028,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/8/playlist.m3u8
+`;
+
+const eiffelExpectedMasterRkmpp = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-STREAM-INF:BANDWIDTH=1200000,RESOLUTION=480x852,CODECS="hvc1.1.6.L90.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/1/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=480x852,CODECS="avc1.64001e,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/2/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=720x1280,CODECS="hvc1.1.6.L93.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/4/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=5000000,RESOLUTION=720x1280,CODECS="avc1.64001f,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/5/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=4500000,RESOLUTION=1080x1920,CODECS="hvc1.1.6.L120.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/7/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=8000000,RESOLUTION=1080x1920,CODECS="avc1.640028,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=24.910
+${sessionId}/8/playlist.m3u8
+`;
+
+const waterfallExpectedMasterDisabled = `#EXTM3U
+#EXT-X-VERSION:6
+#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=480x852,CODECS="av01.0.04M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/0/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=1200000,RESOLUTION=480x852,CODECS="hvc1.1.6.L90.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/1/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=480x852,CODECS="avc1.64001e,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/2/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=720x1280,CODECS="av01.0.08M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/3/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=720x1280,CODECS="hvc1.1.6.L93.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/4/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=5000000,RESOLUTION=720x1280,CODECS="avc1.64001f,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/5/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=4000000,RESOLUTION=1080x1920,CODECS="av01.0.09M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/6/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=4500000,RESOLUTION=1080x1920,CODECS="hvc1.1.6.L120.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/7/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=8000000,RESOLUTION=1080x1920,CODECS="avc1.640028,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/8/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=7000000,RESOLUTION=1440x2560,CODECS="av01.0.12M.08,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/9/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=8000000,RESOLUTION=1440x2560,CODECS="hvc1.2.4.L150.B0,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/10/playlist.m3u8
+#EXT-X-STREAM-INF:BANDWIDTH=16000000,RESOLUTION=1440x2560,CODECS="avc1.640032,mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=29.830
+${sessionId}/11/playlist.m3u8
+`;
+
+describe(HlsService.name, () => {
+  let sut: HlsService;
+  let mocks: ServiceMocks;
+
+  beforeEach(() => {
+    ({ sut, mocks } = newTestService(HlsService));
+  });
+
+  describe('getMainPlaylist', () => {
+    const auth = factory.auth();
+    const assetId = 'asset-1';
+
+    const setup = (asset: typeof eiffelTower | typeof waterfall, accel: TranscodeHardwareAcceleration) => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { realtime: { enabled: true }, accel } });
+      mocks.videoStream.getForMainPlaylist.mockResolvedValue(asset);
+      mocks.crypto.randomUUID.mockReturnValue(sessionId);
+      mocks.websocket.serverSend.mockImplementation((event, ...rest) => {
+        if (event === 'HlsSessionRequest') {
+          const { sessionId: id } = rest[0] as { sessionId: string };
+          queueMicrotask(() => sut.onSessionResult({ sessionId: id }));
+        }
+      });
+    };
+
+    it('returns main playlist for eiffel-tower (1080p portrait, no acceleration)', async () => {
+      setup(eiffelTower, TranscodeHardwareAcceleration.Disabled);
+      await expect(sut.getMainPlaylist(auth, assetId)).resolves.toBe(eiffelExpectedMasterDisabled);
+    });
+
+    it('returns main playlist for eiffel-tower with RKMPP (no AV1 variants)', async () => {
+      setup(eiffelTower, TranscodeHardwareAcceleration.Rkmpp);
+      await expect(sut.getMainPlaylist(auth, assetId)).resolves.toBe(eiffelExpectedMasterRkmpp);
+    });
+
+    it('returns main playlist for waterfall (4K landscape) with no acceleration', async () => {
+      setup(waterfall, TranscodeHardwareAcceleration.Disabled);
+      await expect(sut.getMainPlaylist(auth, assetId)).resolves.toBe(waterfallExpectedMasterDisabled);
+    });
+
+    it('throws BadRequestException when realtime transcoding is disabled', async () => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { realtime: { enabled: false } } });
+      await expect(sut.getMainPlaylist(auth, assetId)).rejects.toBeInstanceOf(BadRequestException);
+    });
+
+    it('throws NotFoundException when asset is not yet ready for streaming', async () => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { realtime: { enabled: true } } });
+      await expect(sut.getMainPlaylist(auth, assetId)).rejects.toBeInstanceOf(NotFoundException);
+    });
+  });
+
+  describe('getMediaPlaylist', () => {
+    const auth = factory.auth();
+    const assetId = 'asset-1';
+    const fixtures = [
+      { data: eiffelTower, playlist: eiffelExpectedMediaPlaylist },
+      { data: waterfall, playlist: waterfallExpectedMediaPlaylist },
+      { data: train, playlist: trainExpectedMediaPlaylist },
+    ];
+
+    it.each(fixtures)('matches FFmpeg for $data.originalPath', async ({ data, playlist }) => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      mocks.videoStream.getForMediaPlaylist.mockResolvedValue(data);
+      await expect(sut.getMediaPlaylist(auth, assetId, sessionId)).resolves.toBe(playlist);
+    });
+
+    it('throws NotFoundException when the session/asset cannot be loaded', async () => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      await expect(sut.getMediaPlaylist(auth, assetId, sessionId)).rejects.toBeInstanceOf(NotFoundException);
+    });
+  });
+
+  describe('getSegment', () => {
+    const auth = factory.auth();
+    const assetId = 'asset-1';
+    const variantIndex = 0;
+
+    beforeEach(() => {
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      mocks.videoStream.getSession.mockResolvedValue({ id: sessionId, assetId } as never);
+      mocks.storage.checkFileExists.mockResolvedValue(true);
+    });
+
+    it('emits HlsHeartbeat with segmentIndex 0 for the first init.mp4 request', async () => {
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'init.mp4');
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId,
+        variantIndex,
+        segmentIndex: 0,
+      });
+    });
+
+    it('emits HlsHeartbeat with the parsed segment number for seg_K.m4s', async () => {
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'seg_5.m4s');
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId,
+        variantIndex,
+        segmentIndex: 5,
+      });
+    });
+
+    it('returns lastRequested + 1 for init.mp4 after a segment has been served', async () => {
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'seg_5.m4s');
+      mocks.websocket.serverSend.mockClear();
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'init.mp4');
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId,
+        variantIndex,
+        segmentIndex: 6,
+      });
+    });
+
+    it('updates lastRequested on a backward-seek segment request', async () => {
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'seg_5.m4s');
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'seg_3.m4s');
+      mocks.websocket.serverSend.mockClear();
+      await sut.getSegment(auth, assetId, sessionId, variantIndex, 'init.mp4');
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId,
+        variantIndex,
+        segmentIndex: 4,
+      });
+    });
+
+    it('tracks segment state per session independently', async () => {
+      await sut.getSegment(auth, assetId, 'session-a', variantIndex, 'seg_5.m4s');
+      await sut.getSegment(auth, assetId, 'session-b', variantIndex, 'seg_2.m4s');
+      mocks.websocket.serverSend.mockClear();
+      await sut.getSegment(auth, assetId, 'session-a', variantIndex, 'init.mp4');
+      await sut.getSegment(auth, assetId, 'session-b', variantIndex, 'init.mp4');
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId: 'session-a',
+        variantIndex,
+        segmentIndex: 6,
+      });
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsHeartbeat', {
+        sessionId: 'session-b',
+        variantIndex,
+        segmentIndex: 3,
+      });
+    });
+
+    it('rejects pending waiters for the previous variant on variant change', async () => {
+      mocks.storage.checkFileExists.mockResolvedValueOnce(false);
+
+      const pending = sut.getSegment(auth, assetId, sessionId, 0, 'seg_1.m4s');
+      await new Promise((resolve) => setImmediate(resolve));
+      await sut.getSegment(auth, assetId, sessionId, 1, 'seg_1.m4s');
+
+      await expect(pending).rejects.toThrow('Variant changed');
+    });
+
+    it('throws NotFoundException when the session does not exist', async () => {
+      mocks.videoStream.getSession.mockReset();
+      await expect(sut.getSegment(auth, assetId, sessionId, variantIndex, 'init.mp4')).rejects.toBeInstanceOf(
+        NotFoundException,
+      );
+    });
+  });
+
+  describe('endSession', () => {
+    it('emits HlsSessionEnd', async () => {
+      const auth = factory.auth();
+      const assetId = 'asset-1';
+      mocks.access.asset.checkOwnerAccess.mockResolvedValue(new Set([assetId]));
+      await sut.endSession(auth, assetId, sessionId);
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsSessionEnd', { sessionId });
+    });
+  });
+});
diff --git a/server/src/services/hls.service.ts b/server/src/services/hls.service.ts
new file mode 100644
index 0000000000..fba8b8e060
--- /dev/null
+++ b/server/src/services/hls.service.ts
@@ -0,0 +1,198 @@
+import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
+import { constants } from 'node:fs';
+import { join } from 'node:path';
+import {
+  HLS_SEGMENT_DURATION,
+  HLS_SEGMENT_FILENAME_REGEX,
+  HLS_VARIANTS,
+  HLS_VERSION,
+  SUPPORTED_HWA_CODECS,
+} from 'src/constants';
+import { StorageCore } from 'src/cores/storage.core';
+import { OnEvent } from 'src/decorators';
+import { AuthDto } from 'src/dtos/auth.dto';
+import { SystemConfigFFmpegDto } from 'src/dtos/system-config.dto';
+import { CacheControl, ImmichWorker, Permission } from 'src/enum';
+import { ArgOf } from 'src/repositories/event.repository';
+import { BaseService } from 'src/services/base.service';
+import { VideoPacketInfo, VideoStreamInfo } from 'src/types';
+import { PendingEvents } from 'src/utils/event';
+import { ImmichFileResponse } from 'src/utils/file';
+import { getOutputSize } from 'src/utils/media';
+
+type AssetWithStreamInfo = { videoStream: VideoStreamInfo & { timeBase: number }; packets: VideoPacketInfo };
+type ApiSession = { lastRequestedSegment: number | null; lastVariantIndex: number | null };
+
+@Injectable()
+export class HlsService extends BaseService {
+  private pendingSegments = new PendingEvents<'HlsSegmentResult'>({ timeoutMs: 15_000 });
+  private pendingSessions = new PendingEvents<'HlsSessionResult'>({ timeoutMs: 5000 });
+  private sessions = new Map<string, ApiSession>();
+
+  @OnEvent({ name: 'HlsSessionResult', server: true, workers: [ImmichWorker.Api] })
+  onSessionResult(event: ArgOf<'HlsSessionResult'>) {
+    this.pendingSessions.complete(event.sessionId, event);
+    if (event.error) {
+      this.sessions.delete(event.sessionId);
+      this.pendingSegments.rejectByPrefix(`${event.sessionId}:`, event.error);
+    }
+  }
+
+  @OnEvent({ name: 'HlsSessionEnd', server: true, workers: [ImmichWorker.Api] })
+  onSessionEnd({ sessionId }: ArgOf<'HlsSessionEnd'>) {
+    this.sessions.delete(sessionId);
+    this.pendingSegments.rejectByPrefix(`${sessionId}:`, 'Session ended');
+  }
+
+  @OnEvent({ name: 'HlsSegmentResult', server: true, workers: [ImmichWorker.Api] })
+  onSegmentResult(event: ArgOf<'HlsSegmentResult'>) {
+    this.pendingSegments.complete(this.getSegmentKey(event), event);
+  }
+
+  async getMainPlaylist(auth: AuthDto, assetId: string) {
+    await this.requireAccess({ auth, permission: Permission.AssetView, ids: [assetId] });
+    const { ffmpeg } = await this.getConfig({ withCache: true });
+    if (!ffmpeg.realtime.enabled) {
+      throw new BadRequestException('Real-time transcoding is not enabled');
+    }
+
+    const asset = await this.videoStreamRepository.getForMainPlaylist(assetId);
+    if (!asset) {
+      throw new NotFoundException('Asset is not yet ready for streaming');
+    }
+
+    // Sharing the sessionId allows only one microservices worker to successfully insert to the session table.
+    // The microservices worker that creates a session owns the transcoding lifecycle for it.
+    const sessionId = this.cryptoRepository.randomUUID();
+    this.websocketRepository.serverSend('HlsSessionRequest', { sessionId, assetId, ownerId: auth.user.id });
+    await this.pendingSessions.wait(sessionId);
+    this.trackSession(sessionId);
+
+    return this.generateMainPlaylist(sessionId, ffmpeg, asset);
+  }
+
+  async getMediaPlaylist(auth: AuthDto, assetId: string, sessionId: string) {
+    await this.requireAccess({ auth, permission: Permission.AssetView, ids: [assetId] });
+
+    const asset = await this.videoStreamRepository.getForMediaPlaylist(assetId, sessionId);
+    if (!asset) {
+      throw new NotFoundException('Asset not found or not yet ready for streaming');
+    }
+
+    return this.generateMediaPlaylist(asset);
+  }
+
+  async getSegment(auth: AuthDto, assetId: string, sessionId: string, variantIndex: number, filename: string) {
+    await this.requireAccess({ auth, permission: Permission.AssetView, ids: [assetId] });
+
+    const session = await this.videoStreamRepository.getSession(sessionId);
+    if (!session) {
+      throw new NotFoundException('Session not found');
+    }
+
+    const variantDir = StorageCore.getHlsVariantFolder({ ownerId: auth.user.id, sessionId, variantIndex });
+    const path = join(variantDir, filename);
+    const response = new ImmichFileResponse({
+      path,
+      contentType: 'video/mp4',
+      cacheControl: CacheControl.PrivateWithCache,
+    });
+
+    const apiSession = this.trackSession(sessionId, variantIndex);
+    const segmentIndex = this.getSegmentIndex(apiSession, filename);
+    this.websocketRepository.serverSend('HlsHeartbeat', { sessionId, variantIndex, segmentIndex });
+
+    if (await this.storageRepository.checkFileExists(path, constants.R_OK)) {
+      return response;
+    }
+
+    this.websocketRepository.serverSend('HlsSegmentRequest', { sessionId, assetId, variantIndex, segmentIndex });
+    await this.pendingSegments.wait(this.getSegmentKey({ sessionId, variantIndex, segmentIndex }));
+
+    return response;
+  }
+
+  async endSession(auth: AuthDto, assetId: string, sessionId: string): Promise<void> {
+    await this.requireAccess({ auth, permission: Permission.AssetView, ids: [assetId] });
+
+    this.websocketRepository.serverSend('HlsSessionEnd', { sessionId });
+  }
+
+  private generateMainPlaylist(sessionId: string, ffmpeg: SystemConfigFFmpegDto, asset: AssetWithStreamInfo) {
+    const fps = ((asset.packets.packetCount * asset.videoStream.timeBase) / asset.packets.totalDuration).toFixed(3);
+    const sourceResolution = Math.min(asset.videoStream.height, asset.videoStream.width);
+    const targetResolution = Math.max(sourceResolution, HLS_VARIANTS[0].resolution);
+    const lines = ['#EXTM3U', `#EXT-X-VERSION:${HLS_VERSION}`];
+    for (let i = 0; i < HLS_VARIANTS.length; i++) {
+      const { resolution, bitrate, codec, codecString } = HLS_VARIANTS[i];
+      if (resolution > targetResolution || !SUPPORTED_HWA_CODECS[ffmpeg.accel].includes(codec)) {
+        continue;
+      }
+      const { width, height } = getOutputSize(asset.videoStream, resolution);
+      lines.push(
+        `#EXT-X-STREAM-INF:BANDWIDTH=${bitrate},RESOLUTION=${width}x${height},CODECS="${codecString},mp4a.40.2",VIDEO-RANGE=SDR,FRAME-RATE=${fps}`,
+        `${sessionId}/${i}/playlist.m3u8`,
+      );
+    }
+    lines.push('');
+
+    if (lines.length === 3) {
+      throw new NotFoundException('No supported variants for this video');
+    }
+
+    return lines.join('\n');
+  }
+
+  private generateMediaPlaylist({ videoStream, packets }: AssetWithStreamInfo) {
+    const fps = (packets.packetCount * videoStream.timeBase) / packets.totalDuration;
+    const framesPerSegment = Math.ceil(HLS_SEGMENT_DURATION * fps);
+    const fullSegmentDuration = framesPerSegment / fps;
+    const segmentCount = Math.ceil(packets.outputFrames / framesPerSegment);
+    const lastSegmentFrames = packets.outputFrames - framesPerSegment * (segmentCount - 1);
+    const lastSegmentDuration = lastSegmentFrames / fps;
+
+    const lines = [
+      '#EXTM3U',
+      `#EXT-X-VERSION:${HLS_VERSION}`,
+      `#EXT-X-TARGETDURATION:${HLS_SEGMENT_DURATION}`,
+      '#EXT-X-MEDIA-SEQUENCE:0',
+      '#EXT-X-PLAYLIST-TYPE:VOD',
+      '#EXT-X-MAP:URI="init.mp4"',
+    ];
+
+    for (let i = 0; i < segmentCount - 1; i++) {
+      lines.push(`#EXTINF:${fullSegmentDuration.toFixed(6)},`, `seg_${i}.m4s`);
+    }
+    lines.push(`#EXTINF:${lastSegmentDuration.toFixed(6)},`, `seg_${segmentCount - 1}.m4s`, '#EXT-X-ENDLIST', '');
+
+    return lines.join('\n');
+  }
+
+  private getSegmentKey({ sessionId, variantIndex, segmentIndex }: ArgOf<'HlsSegmentResult'>) {
+    return `${sessionId}:${variantIndex}:${segmentIndex}`;
+  }
+
+  private getSegmentIndex(session: ApiSession, filename: string) {
+    if (filename.endsWith('.mp4')) {
+      return (session.lastRequestedSegment ?? -1) + 1;
+    }
+    const segmentIndex = Number.parseInt(HLS_SEGMENT_FILENAME_REGEX.exec(filename)![1]);
+    session.lastRequestedSegment = segmentIndex;
+    return segmentIndex;
+  }
+
+  private trackSession(id: string, variantIndex: number | null = null) {
+    const session = this.sessions.get(id);
+    if (!session) {
+      const newSession = { lastRequestedSegment: null, lastVariantIndex: variantIndex };
+      this.sessions.set(id, newSession);
+      return newSession;
+    }
+
+    if (session.lastVariantIndex !== null && session.lastVariantIndex !== variantIndex) {
+      this.pendingSegments.rejectByPrefix(`${id}:${session.lastVariantIndex}:`, 'Variant changed');
+    }
+    session.lastVariantIndex = variantIndex;
+    return session;
+  }
+}
diff --git a/server/src/services/index.ts b/server/src/services/index.ts
index b733483aa8..3c23e723bc 100644
--- a/server/src/services/index.ts
+++ b/server/src/services/index.ts
@@ -11,6 +11,7 @@ import { DatabaseBackupService } from 'src/services/database-backup.service';
 import { DatabaseService } from 'src/services/database.service';
 import { DownloadService } from 'src/services/download.service';
 import { DuplicateService } from 'src/services/duplicate.service';
+import { HlsService } from 'src/services/hls.service';
 import { JobService } from 'src/services/job.service';
 import { LibraryService } from 'src/services/library.service';
 import { MaintenanceService } from 'src/services/maintenance.service';
@@ -39,6 +40,7 @@ import { SystemMetadataService } from 'src/services/system-metadata.service';
 import { TagService } from 'src/services/tag.service';
 import { TelemetryService } from 'src/services/telemetry.service';
 import { TimelineService } from 'src/services/timeline.service';
+import { TranscodingService } from 'src/services/transcoding.service';
 import { TrashService } from 'src/services/trash.service';
 import { UserAdminService } from 'src/services/user-admin.service';
 import { UserService } from 'src/services/user.service';
@@ -61,6 +63,7 @@ export const services = [
   DatabaseService,
   DownloadService,
   DuplicateService,
+  HlsService,
   JobService,
   LibraryService,
   MaintenanceService,
@@ -89,6 +92,7 @@ export const services = [
   TagService,
   TelemetryService,
   TimelineService,
+  TranscodingService,
   TrashService,
   UserAdminService,
   UserService,
diff --git a/server/src/services/queue.service.spec.ts b/server/src/services/queue.service.spec.ts
index d4c425e8bd..48c61c0951 100644
--- a/server/src/services/queue.service.spec.ts
+++ b/server/src/services/queue.service.spec.ts
@@ -41,6 +41,7 @@ describe(QueueService.name, () => {
         { name: JobName.PersonCleanup },
         { name: JobName.MemoryCleanup },
         { name: JobName.SessionCleanup },
+        { name: JobName.HlsSessionCleanup },
         { name: JobName.AuditTableCleanup },
         { name: JobName.MemoryGenerate },
         { name: JobName.UserSyncUsage },
diff --git a/server/src/services/queue.service.ts b/server/src/services/queue.service.ts
index ba6f4c5f3b..d11c9180b2 100644
--- a/server/src/services/queue.service.ts
+++ b/server/src/services/queue.service.ts
@@ -269,6 +269,7 @@ export class QueueService extends BaseService {
         { name: JobName.PersonCleanup },
         { name: JobName.MemoryCleanup },
         { name: JobName.SessionCleanup },
+        { name: JobName.HlsSessionCleanup },
         { name: JobName.AuditTableCleanup },
       );
     }
diff --git a/server/src/services/system-config.service.spec.ts b/server/src/services/system-config.service.spec.ts
index c9a8492b5d..a76829fd39 100644
--- a/server/src/services/system-config.service.spec.ts
+++ b/server/src/services/system-config.service.spec.ts
@@ -72,6 +72,9 @@ const updatedConfig = Object.freeze<SystemConfig>({
     accel: TranscodeHardwareAcceleration.Disabled,
     accelDecode: true,
     tonemap: ToneMapping.Hable,
+    realtime: {
+      enabled: false,
+    },
   },
   logging: {
     enabled: true,
diff --git a/server/src/services/transcoding.service.spec.ts b/server/src/services/transcoding.service.spec.ts
new file mode 100644
index 0000000000..738ad9c0af
--- /dev/null
+++ b/server/src/services/transcoding.service.spec.ts
@@ -0,0 +1,516 @@
+import {
+  HLS_BACKPRESSURE_PAUSE_SEGMENTS,
+  HLS_BACKPRESSURE_RESUME_SEGMENTS,
+  HLS_CLEANUP_INTERVAL_MS,
+  HLS_INACTIVITY_TIMEOUT_MS,
+  HLS_LEASE_DURATION_MS,
+} from 'src/constants';
+import { TranscodingService } from 'src/services/transcoding.service';
+import { VIDEO_STREAM_SESSION_PK_CONSTRAINT } from 'src/utils/database';
+import { eiffelTower, train, waterfall } from 'test/fixtures/media.stub';
+import { mockSpawn, newTestService, ServiceMocks } from 'test/utils';
+import { vi } from 'vitest';
+
+describe(TranscodingService.name, () => {
+  let sut: TranscodingService;
+  let mocks: ServiceMocks;
+
+  const sessionId = 'session-1';
+  const assetId = 'asset-1';
+  const ownerId = 'user-1';
+
+  const completeSegment = (index: number) => {
+    const listener = vi.mocked(mocks.storage.watchDir).mock.lastCall?.[1];
+    expect(listener).toBeDefined();
+    listener!('rename', `seg_${index}.m4s`);
+  };
+
+  const completeSegmentsThrough = (start: number, end: number) => {
+    for (let i = start; i <= end; i++) {
+      completeSegment(i);
+    }
+  };
+
+  beforeEach(() => {
+    ({ sut, mocks } = newTestService(TranscodingService));
+    mocks.systemMetadata.get.mockResolvedValue({ ffmpeg: { realtime: { enabled: true } } });
+    mocks.videoStream.getForTranscoding.mockResolvedValue(eiffelTower);
+  });
+
+  describe('onSessionRequest', () => {
+    it('creates the session row and emits HlsSessionResult on success', async () => {
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+
+      expect(mocks.videoStream.createSession).toHaveBeenCalledWith({
+        id: sessionId,
+        assetId,
+        expiresAt: expect.any(Date),
+      });
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsSessionResult', { sessionId });
+    });
+
+    it('treats a primary-key conflict as a no-op for replay tolerance', async () => {
+      mocks.videoStream.createSession.mockRejectedValue({ constraint_name: VIDEO_STREAM_SESSION_PK_CONSTRAINT });
+
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+
+      expect(mocks.websocket.serverSend).not.toHaveBeenCalled();
+    });
+
+    it('emits HlsSessionResult with an error on other DB failures', async () => {
+      mocks.videoStream.createSession.mockRejectedValue(new Error('database is down'));
+
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsSessionResult', {
+        sessionId,
+        error: 'Failed to create HLS session',
+      });
+    });
+  });
+
+  describe('onSessionEnd', () => {
+    it('removes the session, kills the transcode, and deletes the dir + DB row', async () => {
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+      const process = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValue(process);
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 0 });
+
+      await sut.onSessionEnd({ sessionId });
+
+      expect(process.kill).toHaveBeenCalled();
+      expect(mocks.storage.unlinkDir).toHaveBeenCalled();
+      expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith(sessionId);
+    });
+
+    it('is a no-op when the session is unknown', async () => {
+      await sut.onSessionEnd({ sessionId: 'never-created' });
+
+      expect(mocks.videoStream.deleteSession).not.toHaveBeenCalled();
+      expect(mocks.storage.unlinkDir).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('onHeartbeat', () => {
+    it('extends the DB lease when remaining time falls below half', async () => {
+      vi.useFakeTimers();
+      try {
+        await sut.onSessionRequest({ sessionId, assetId, ownerId });
+        vi.setSystemTime(Date.now() + HLS_LEASE_DURATION_MS / 2 + 1);
+
+        await sut.onHeartbeat({ sessionId });
+
+        expect(mocks.videoStream.extendSession).toHaveBeenCalledWith(sessionId, expect.any(Date));
+      } finally {
+        vi.useRealTimers();
+      }
+    });
+
+    it('does not extend the lease while it is still fresh', async () => {
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+
+      await sut.onHeartbeat({ sessionId });
+
+      expect(mocks.videoStream.extendSession).not.toHaveBeenCalled();
+    });
+
+    it('is a no-op when the session is unknown', async () => {
+      await sut.onHeartbeat({ sessionId: 'never-created' });
+
+      expect(mocks.videoStream.extendSession).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('onSegmentRequest', () => {
+    beforeEach(async () => {
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+      mocks.websocket.serverSend.mockClear();
+    });
+
+    it('spawns FFmpeg on the first request', async () => {
+      mocks.process.spawn.mockReturnValue(mockSpawn(0, '', ''));
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 0 });
+
+      expect(mocks.process.spawn).toHaveBeenCalledTimes(1);
+      expect(mocks.process.spawn).toHaveBeenCalledWith('ffmpeg', expect.any(Array), expect.any(Object));
+    });
+
+    it('kills and respawns when the variant changes', async () => {
+      const first = mockSpawn(0, '', '');
+      const second = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValueOnce(first).mockReturnValueOnce(second);
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 0 });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 1, segmentIndex: 0 });
+
+      expect(first.kill).toHaveBeenCalled();
+      expect(mocks.process.spawn).toHaveBeenCalledTimes(2);
+    });
+
+    it('kills and respawns when seeking before the start segment', async () => {
+      const first = mockSpawn(0, '', '');
+      const second = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValueOnce(first).mockReturnValueOnce(second);
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 5 });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 2 });
+
+      expect(first.kill).toHaveBeenCalled();
+      expect(mocks.process.spawn).toHaveBeenCalledTimes(2);
+    });
+
+    it('kills and respawns when the requested segment is too far ahead', async () => {
+      const first = mockSpawn(0, '', '');
+      const second = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValueOnce(first).mockReturnValueOnce(second);
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 0 });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 5 });
+
+      expect(first.kill).toHaveBeenCalled();
+      expect(mocks.process.spawn).toHaveBeenCalledTimes(2);
+    });
+
+    it('does not spawn when the session is unknown', async () => {
+      await sut.onSegmentRequest({ sessionId: 'never-created', assetId, variantIndex: 0, segmentIndex: 0 });
+
+      expect(mocks.process.spawn).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('backpressure', () => {
+    let proc: ReturnType<typeof mockSpawn>;
+
+    beforeEach(async () => {
+      proc = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValue(proc);
+
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 0 });
+    });
+
+    it('pauses the transcode once the lead exceeds HLS_BACKPRESSURE_PAUSE_SEGMENTS', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+
+      expect(proc.kill).toHaveBeenCalledWith('SIGSTOP');
+    });
+
+    it('does not pause when the lead equals the pause threshold', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS);
+
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+
+      expect(proc.kill).not.toHaveBeenCalled();
+    });
+
+    it('resumes once the lead drops below HLS_BACKPRESSURE_RESUME_SEGMENTS', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+      expect(proc.kill).toHaveBeenCalledWith('SIGSTOP');
+      vi.mocked(proc.kill).mockClear();
+
+      const requested = HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1 - (HLS_BACKPRESSURE_RESUME_SEGMENTS - 1);
+      await sut.onHeartbeat({ sessionId, segmentIndex: requested });
+
+      expect(proc.kill).toHaveBeenCalledWith('SIGCONT');
+    });
+
+    it('stays paused while the lead is in the dead-band', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+      vi.mocked(proc.kill).mockClear();
+
+      const requested = HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1 - HLS_BACKPRESSURE_RESUME_SEGMENTS;
+      await sut.onHeartbeat({ sessionId, segmentIndex: requested });
+
+      expect(proc.kill).not.toHaveBeenCalled();
+    });
+
+    it('is a no-op when no segment has completed yet', async () => {
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+
+      expect(proc.kill).not.toHaveBeenCalled();
+    });
+
+    it('is a no-op when the heartbeat omits segmentIndex', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+
+      await sut.onHeartbeat({ sessionId });
+
+      expect(proc.kill).not.toHaveBeenCalled();
+    });
+
+    it('resumes the paused transcode when the client requests the next in-range segment', async () => {
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+      expect(proc.kill).toHaveBeenCalledWith('SIGSTOP');
+      vi.mocked(proc.kill).mockClear();
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex: 1 });
+
+      expect(proc.kill).toHaveBeenCalledWith('SIGCONT');
+      expect(mocks.process.spawn).toHaveBeenCalledTimes(1);
+    });
+
+    it('does not re-pause a freshly spawned transcode after a seek-driven restart', async () => {
+      const newProc = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValueOnce(newProc);
+
+      completeSegmentsThrough(0, HLS_BACKPRESSURE_PAUSE_SEGMENTS + 1);
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+      expect(proc.kill).toHaveBeenCalledWith('SIGSTOP');
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 1, segmentIndex: 0 });
+      vi.mocked(newProc.kill).mockClear();
+
+      await sut.onHeartbeat({ sessionId, segmentIndex: 0 });
+
+      expect(newProc.kill).not.toHaveBeenCalled();
+    });
+
+    it('ignores stale segment events from the prior transcode after a backward seek', async () => {
+      const newProc = mockSpawn(0, '', '');
+      mocks.process.spawn.mockReturnValueOnce(newProc);
+
+      const completedAhead = HLS_BACKPRESSURE_PAUSE_SEGMENTS + 5;
+      completeSegmentsThrough(1, completedAhead); // seg_0 was emitted in beforeEach
+
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 1, segmentIndex: 0 });
+
+      vi.mocked(newProc.kill).mockClear();
+      mocks.websocket.serverSend.mockClear();
+      completeSegment(completedAhead + 1);
+
+      expect(mocks.websocket.serverSend).not.toHaveBeenCalledWith(
+        'HlsSegmentResult',
+        expect.objectContaining({ segmentIndex: completedAhead + 1 }),
+      );
+      expect(newProc.kill).not.toHaveBeenCalled();
+
+      completeSegment(0);
+      expect(mocks.websocket.serverSend).toHaveBeenCalledWith(
+        'HlsSegmentResult',
+        expect.objectContaining({ segmentIndex: 0 }),
+      );
+    });
+  });
+
+  describe('inactivity sweeper', () => {
+    it('reaps a session whose last activity exceeds the inactivity timeout', async () => {
+      vi.useFakeTimers();
+      try {
+        await sut.onSessionRequest({ sessionId, assetId, ownerId });
+        mocks.websocket.serverSend.mockClear();
+        await vi.advanceTimersByTimeAsync(HLS_INACTIVITY_TIMEOUT_MS + HLS_CLEANUP_INTERVAL_MS);
+
+        expect(mocks.websocket.serverSend).toHaveBeenCalledWith('HlsSessionEnd', { sessionId });
+        expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith(sessionId);
+      } finally {
+        vi.useRealTimers();
+      }
+    });
+  });
+
+  describe('onShutdown', () => {
+    it('ends every active session', async () => {
+      await sut.onSessionRequest({ sessionId: 'session-a', assetId, ownerId });
+      await sut.onSessionRequest({ sessionId: 'session-b', assetId, ownerId });
+
+      await sut.onShutdown();
+
+      expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith('session-a');
+      expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith('session-b');
+    });
+  });
+
+  describe('onHlsSessionCleanup', () => {
+    it('reaps DB-expired sessions under a database lock', async () => {
+      mocks.database.withLock.mockImplementation(async (_, fn) => fn());
+      mocks.videoStream.getExpiredSessions.mockResolvedValue([
+        { id: 'expired-1', ownerId: 'user-a' },
+        { id: 'expired-2', ownerId: 'user-b' },
+      ]);
+
+      await sut.onHlsSessionCleanup();
+
+      expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith('expired-1');
+      expect(mocks.videoStream.deleteSession).toHaveBeenCalledWith('expired-2');
+      expect(mocks.storage.unlinkDir).toHaveBeenCalledTimes(2);
+    });
+  });
+
+  describe('FFmpeg full command', () => {
+    const baseCommand = [
+      '-nostdin',
+      '-nostats',
+      '-i',
+      'eiffel-tower.mp4',
+      '-map',
+      '0:0',
+      '-map_metadata',
+      '-1',
+      '-map',
+      '0:1',
+      '-g',
+      '50',
+      '-keyint_min',
+      '50',
+      '-crf',
+      '23',
+      '-copyts',
+      '-r',
+      '50130000/2012441',
+      '-avoid_negative_ts',
+      'disabled',
+      '-f',
+      'hls',
+      '-hls_time',
+      '2',
+      '-hls_list_size',
+      '0',
+      '-hls_segment_type',
+      'fmp4',
+      '-hls_fmp4_init_filename',
+      'init.mp4',
+      '-hls_segment_options',
+      'movflags=+frag_discont',
+      '-hls_flags',
+      'temp_file',
+      '-start_number',
+      '0',
+    ];
+
+    it.each([
+      {
+        variantIndex: 6,
+        expected: [
+          ...baseCommand,
+          '-c:v',
+          'libsvtav1',
+          '-c:a',
+          'aac',
+          '-preset',
+          '12',
+          '-svtav1-params',
+          'hierarchical-levels=3:lookahead=0:enable-tf=0:mbr=4000k',
+          '-hls_segment_filename',
+          '/data/encoded-video/user-1/se/ss/session-1/6/seg_%d.m4s',
+          '/data/encoded-video/user-1/se/ss/session-1/6/playlist.m3u8',
+        ].sort(),
+      },
+      {
+        variantIndex: 4,
+        expected: [
+          ...baseCommand,
+          '-c:v',
+          'hevc',
+          '-c:a',
+          'aac',
+          '-tag:v',
+          'hvc1',
+          '-preset',
+          'ultrafast',
+          '-maxrate',
+          '2500k',
+          '-bufsize',
+          '5000k',
+          '-x265-params',
+          'no-scenecut=1:no-open-gop=1',
+          '-vf',
+          'scale=720:-2',
+          '-hls_segment_filename',
+          '/data/encoded-video/user-1/se/ss/session-1/4/seg_%d.m4s',
+          '/data/encoded-video/user-1/se/ss/session-1/4/playlist.m3u8',
+        ].sort(),
+      },
+      {
+        variantIndex: 2,
+        expected: [
+          ...baseCommand,
+          '-c:v',
+          'h264',
+          '-c:a',
+          'aac',
+          '-preset',
+          'ultrafast',
+          '-maxrate',
+          '2500k',
+          '-bufsize',
+          '5000k',
+          '-sc_threshold:v',
+          '0',
+          '-vf',
+          'scale=480:-2',
+          '-hls_segment_filename',
+          '/data/encoded-video/user-1/se/ss/session-1/2/seg_%d.m4s',
+          '/data/encoded-video/user-1/se/ss/session-1/2/playlist.m3u8',
+        ].sort(),
+      },
+    ])('builds the expected FFmpeg command for $codec (variant $variantIndex)', async ({ variantIndex, expected }) => {
+      mocks.process.spawn.mockReturnValue(mockSpawn(0, '', ''));
+
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex, segmentIndex: 0 });
+
+      expect(mocks.process.spawn.mock.calls[0][1].toSorted()).toEqual(expected);
+    });
+  });
+
+  describe('FFmpeg seek per segment', () => {
+    const eiffelSeeks = [
+      0, 1.987_15, 3.994_372_222_222_222, 6.001_594_444_444_444, 8.008_816_666_666_666, 10.016_038_888_888_888,
+      12.023_261_111_111_111, 14.030_483_333_333_333, 16.037_705_555_555_554, 18.044_927_777_777_776,
+      20.052_149_999_999_997, 22.059_372_222_222_223,
+    ];
+    const waterfallSeeks = [
+      0, 1.994_642_826_321_467, 4.006_047_357_065_803, 6.017_451_887_810_139_5, 8.028_856_418_554_476,
+      10.040_260_949_298_812,
+    ];
+    const trainSeeks = [
+      0, 1.991_666_666_666_666_7, 3.991_666_666_666_666_7, 5.991_666_666_666_666, 7.991_666_666_666_666,
+      9.991_666_666_666_667, 11.991_666_666_666_667, 13.991_666_666_666_667, 15.991_666_666_666_667,
+      17.991_666_666_666_667, 19.991_666_666_666_667,
+    ];
+    const cases = [
+      ...eiffelSeeks.map((expected, segmentIndex) => ({
+        name: `${eiffelTower.originalPath} K=${segmentIndex}`,
+        fixture: eiffelTower,
+        segmentIndex,
+        expected,
+      })),
+      ...waterfallSeeks.map((expected, segmentIndex) => ({
+        name: `${waterfall.originalPath} K=${segmentIndex}`,
+        fixture: waterfall,
+        segmentIndex,
+        expected,
+      })),
+      ...trainSeeks.map((expected, segmentIndex) => ({
+        name: `${train.originalPath} K=${segmentIndex}`,
+        fixture: train,
+        segmentIndex,
+        expected,
+      })),
+    ];
+
+    it.each(cases)('$name', async ({ fixture, segmentIndex, expected }) => {
+      mocks.videoStream.getForTranscoding.mockResolvedValue(fixture);
+      mocks.process.spawn.mockReturnValue(mockSpawn(0, '', ''));
+
+      await sut.onSessionRequest({ sessionId, assetId, ownerId });
+      await sut.onSegmentRequest({ sessionId, assetId, variantIndex: 0, segmentIndex });
+
+      const args = mocks.process.spawn.mock.calls[0][1] as string[];
+      if (expected === 0) {
+        expect(args).toEqual(expect.arrayContaining(['-copyts', '-avoid_negative_ts', 'disabled']));
+        expect(args).not.toContain('-ss');
+      } else {
+        expect(args).toEqual(
+          expect.arrayContaining(['-ss', String(expected), '-copyts', '-avoid_negative_ts', 'disabled']),
+        );
+      }
+    });
+  });
+});
diff --git a/server/src/services/transcoding.service.ts b/server/src/services/transcoding.service.ts
new file mode 100644
index 0000000000..6b38c6f026
--- /dev/null
+++ b/server/src/services/transcoding.service.ts
@@ -0,0 +1,386 @@
+import { Injectable } from '@nestjs/common';
+import { ChildProcess } from 'node:child_process';
+import { join } from 'node:path';
+import {
+  HLS_BACKPRESSURE_PAUSE_SEGMENTS,
+  HLS_BACKPRESSURE_RESUME_SEGMENTS,
+  HLS_CLEANUP_INTERVAL_MS,
+  HLS_INACTIVITY_TIMEOUT_MS,
+  HLS_LEASE_DURATION_MS,
+  HLS_SEGMENT_DURATION,
+  HLS_SEGMENT_FILENAME_REGEX,
+  HLS_VARIANTS,
+} from 'src/constants';
+import { StorageCore } from 'src/cores/storage.core';
+import { OnEvent, OnJob } from 'src/decorators';
+import { DatabaseLock, ImmichWorker, JobName, QueueName, TranscodeTarget } from 'src/enum';
+import { ArgOf } from 'src/repositories/event.repository';
+import { BaseService } from 'src/services/base.service';
+import { VideoInterfaces } from 'src/types';
+import { isVideoStreamSessionPkConstraint } from 'src/utils/database';
+import { BaseConfig } from 'src/utils/media';
+
+type Session = {
+  assetId: string;
+  expiresAt: Date;
+  id: string;
+  lastActivityTime: Date;
+  lastClientRequestedSegment: number | null;
+  lastCompletedSegment: number | null;
+  ownerId: string;
+  paused: boolean;
+  process: ChildProcess | null;
+  startSegment: number | null;
+  variantIndex: number | null;
+};
+
+@Injectable()
+export class TranscodingService extends BaseService {
+  private sessions = new Map<string, Session>();
+  private videoInterfaces: VideoInterfaces = { dri: [], mali: false };
+  private cleanupInterval: NodeJS.Timeout | null = null;
+
+  @OnEvent({ name: 'AppBootstrap', workers: [ImmichWorker.Microservices] })
+  async onBootstrap() {
+    const [videoInterfaces] = await Promise.all([this.storageCore.getVideoInterfaces(), this.removeExpiredSessions()]);
+    this.videoInterfaces = videoInterfaces;
+  }
+
+  @OnEvent({ name: 'AppShutdown', workers: [ImmichWorker.Microservices] })
+  onShutdown() {
+    if (this.cleanupInterval) {
+      clearInterval(this.cleanupInterval);
+      this.cleanupInterval = null;
+    }
+    return Promise.all([...this.sessions.values()].map(({ id }) => this.onSessionEnd({ sessionId: id })));
+  }
+
+  @OnJob({ name: JobName.HlsSessionCleanup, queue: QueueName.BackgroundTask })
+  onHlsSessionCleanup() {
+    return this.removeExpiredSessions();
+  }
+
+  @OnEvent({ name: 'HlsSessionRequest', server: true, workers: [ImmichWorker.Microservices] })
+  async onSessionRequest({ assetId, sessionId, ownerId }: ArgOf<'HlsSessionRequest'>) {
+    try {
+      const expiresAt = new Date(Date.now() + HLS_LEASE_DURATION_MS);
+      await this.videoStreamRepository.createSession({ id: sessionId, assetId, expiresAt });
+      this.sessions.set(sessionId, {
+        assetId,
+        expiresAt,
+        id: sessionId,
+        lastActivityTime: new Date(),
+        lastClientRequestedSegment: null,
+        lastCompletedSegment: null,
+        ownerId,
+        paused: false,
+        process: null,
+        startSegment: null,
+        variantIndex: null,
+      });
+      this.cleanupInterval ??= setInterval(() => void this.removeInactiveSessions(), HLS_CLEANUP_INTERVAL_MS);
+      this.websocketRepository.serverSend('HlsSessionResult', { sessionId });
+    } catch (error) {
+      // If insertion failed due to a PK constraint, another worker has already created a session for this ID.
+      if (!isVideoStreamSessionPkConstraint(error)) {
+        this.logger.error(`Failed to create HLS session ${sessionId}: ${error}`);
+        this.websocketRepository.serverSend('HlsSessionResult', { sessionId, error: 'Failed to create HLS session' });
+      }
+    }
+  }
+
+  @OnEvent({ name: 'HlsSessionEnd', server: true, workers: [ImmichWorker.Microservices] })
+  async onSessionEnd({ sessionId }: ArgOf<'HlsSessionEnd'>) {
+    const session = this.sessions.get(sessionId);
+    if (!session) {
+      return;
+    }
+    this.sessions.delete(sessionId);
+    if (this.cleanupInterval && this.sessions.size === 0) {
+      clearInterval(this.cleanupInterval);
+      this.cleanupInterval = null;
+    }
+    this.stopTranscode(session);
+    await this.removeSessionDir(session);
+    await this.videoStreamRepository.deleteSession(sessionId);
+  }
+
+  @OnEvent({ name: 'HlsHeartbeat', server: true, workers: [ImmichWorker.Microservices] })
+  async onHeartbeat({ sessionId, segmentIndex }: ArgOf<'HlsHeartbeat'>) {
+    const session = this.sessions.get(sessionId);
+    if (!session) {
+      return;
+    }
+
+    session.lastActivityTime = new Date();
+
+    if (segmentIndex !== undefined) {
+      session.lastClientRequestedSegment = segmentIndex;
+      this.applyBackpressure(session);
+    }
+
+    const remaining = session.expiresAt.getTime() - Date.now();
+    if (remaining < HLS_LEASE_DURATION_MS / 2) {
+      session.expiresAt = new Date(Date.now() + HLS_LEASE_DURATION_MS);
+      await this.videoStreamRepository.extendSession(sessionId, session.expiresAt);
+    }
+  }
+
+  @OnEvent({ name: 'HlsSegmentRequest', server: true, workers: [ImmichWorker.Microservices] })
+  async onSegmentRequest({ sessionId, variantIndex, segmentIndex }: ArgOf<'HlsSegmentRequest'>) {
+    const session = this.sessions.get(sessionId);
+    if (!session) {
+      return;
+    }
+
+    session.variantIndex ??= variantIndex;
+    session.startSegment ??= segmentIndex;
+    const curSegment = session.lastCompletedSegment === null ? session.startSegment : session.lastCompletedSegment + 1;
+    const needsRestart =
+      session.variantIndex !== variantIndex || segmentIndex < session.startSegment || segmentIndex > curSegment + 1;
+    if (needsRestart) {
+      this.stopTranscode(session);
+      session.variantIndex = variantIndex;
+      session.startSegment = segmentIndex;
+    } else if (session.process) {
+      this.resumeTranscode(session);
+      return;
+    }
+
+    const process = await this.startTranscode(session, variantIndex, segmentIndex);
+    if (process) {
+      session.process = process;
+    }
+  }
+
+  private applyBackpressure(session: Session) {
+    if (session.lastCompletedSegment === null || session.lastClientRequestedSegment === null) {
+      return;
+    }
+    const lead = session.lastCompletedSegment - session.lastClientRequestedSegment;
+    this.logger.debug(`Session ${session.id} lead is ${lead} segments`);
+    if (!session.paused && lead > HLS_BACKPRESSURE_PAUSE_SEGMENTS) {
+      this.pauseTranscode(session);
+    } else if (session.paused && lead < HLS_BACKPRESSURE_RESUME_SEGMENTS) {
+      this.resumeTranscode(session);
+    }
+  }
+
+  private async startTranscode(session: Session, variantIndex: number, startSegment: number) {
+    const { ffmpeg } = await this.getConfig({ withCache: true });
+
+    const asset = await this.videoStreamRepository.getForTranscoding(session.assetId);
+    if (!asset) {
+      this.logger.error(`Asset ${session.assetId} not found for HLS transcoding`);
+      return;
+    }
+
+    if (session.variantIndex !== variantIndex || session.startSegment !== startSegment) {
+      return;
+    }
+
+    const variant = HLS_VARIANTS[variantIndex];
+    if (!variant) {
+      this.logger.error(`Variant ${variantIndex} out of range for asset ${session.assetId}`);
+      await this.failSession(session, `Invalid variant index ${variantIndex}`);
+      return;
+    }
+
+    const variantDir = StorageCore.getHlsVariantFolder({
+      ownerId: session.ownerId,
+      sessionId: session.id,
+      variantIndex,
+    });
+    this.storageRepository.mkdirSync(variantDir);
+
+    // Encoder runs at fps = packetCount × timeBase / totalDuration with
+    // gop = ceil(SEGMENT_DURATION × fps). To start segment K's content at
+    // exactly cfr slot K × gop, seek to the midpoint between slots K×gop−1 and
+    // K×gop. accurate_seek's "discard < target" then keeps the source frame
+    // that quantizes to slot K×gop and discards the one quantizing to K×gop−1.
+    const fps = (asset.packets.packetCount * asset.videoStream.timeBase) / asset.packets.totalDuration;
+    const gop = Math.ceil(HLS_SEGMENT_DURATION * fps);
+    const seekSeconds = startSegment > 0 ? (startSegment * gop - 0.5) / fps : 0;
+
+    let config;
+    try {
+      config = BaseConfig.create(
+        {
+          ...ffmpeg,
+          targetVideoCodec: variant.codec,
+          targetResolution: String(variant.resolution),
+          maxBitrate: `${Math.round(variant.bitrate / 1000)}k`,
+          gopSize: gop,
+        },
+        this.videoInterfaces,
+        { strictGop: true, lowLatency: true },
+      );
+    } catch (error: any) {
+      this.logger.error(
+        `Failed to create transcode config for variant ${variantIndex} asset ${session.assetId}: ${error?.message ?? error}`,
+      );
+      await this.failSession(session, `Failed to start transcode: ${error?.message ?? 'unknown error'}`);
+      return;
+    }
+    const args = config.getHlsCommand(
+      {
+        initFilename: 'init.mp4',
+        inputPath: asset.originalPath,
+        packetCount: asset.packets.packetCount,
+        playlistFilename: join(variantDir, 'playlist.m3u8'),
+        seekSeconds,
+        segmentDuration: HLS_SEGMENT_DURATION,
+        segmentFilename: join(variantDir, 'seg_%d.m4s'),
+        startSegment,
+        target: TranscodeTarget.All,
+        timeBase: asset.videoStream.timeBase,
+        totalDuration: asset.packets.totalDuration,
+      },
+      asset.videoStream,
+      asset.audioStream ?? undefined,
+    );
+    this.logger.log(
+      `Starting HLS transcode for asset ${session.assetId} variant ${variantIndex} with command: ffmpeg ${args.join(' ')}`,
+    );
+    const process = this.processRepository.spawn('ffmpeg', args, { stdio: ['ignore', 'ignore', 'pipe'] });
+    this.attachProcessHandlers(process, session, variantIndex);
+    return process;
+  }
+
+  private failSession(session: Session, error: string) {
+    this.websocketRepository.serverSend('HlsSessionResult', { sessionId: session.id, error });
+    return this.onSessionEnd({ sessionId: session.id });
+  }
+
+  private attachProcessHandlers(process: ChildProcess, session: Session, variantIndex: number) {
+    let stderr = '';
+    const variantDir = StorageCore.getHlsVariantFolder({
+      ownerId: session.ownerId,
+      sessionId: session.id,
+      variantIndex,
+    });
+
+    // hlsenc writes each segment as `seg_K.m4s.tmp` then renames to
+    // `seg_K.m4s`. The rename event fires the moment the renamed file is
+    // observable — the only signal we need to tell the API worker the
+    // segment is ready to serve.
+    const watcher = this.storageRepository.watchDir(variantDir, (eventType, filename) => {
+      if (eventType !== 'rename' || !filename || session.process !== process) {
+        return;
+      }
+      const match = HLS_SEGMENT_FILENAME_REGEX.exec(filename);
+      if (!match) {
+        return;
+      }
+      const segmentIndex = Number.parseInt(match[1]);
+      const expected = session.lastCompletedSegment === null ? session.startSegment : session.lastCompletedSegment + 1;
+      // Ignore stale events from old process after seek
+      if (expected === null || segmentIndex !== expected) {
+        return;
+      }
+      session.lastCompletedSegment = segmentIndex;
+      this.websocketRepository.serverSend('HlsSegmentResult', {
+        sessionId: session.id,
+        variantIndex,
+        segmentIndex,
+      });
+      this.applyBackpressure(session);
+    });
+    watcher.on('error', (error) => {
+      this.logger.error(`watcher error for ${variantDir}: ${error}`);
+    });
+
+    process.stderr!.on('data', (chunk: Buffer) => {
+      if (session.process !== process) {
+        return;
+      }
+      stderr += chunk.toString();
+    });
+
+    process.on('exit', (code) => {
+      watcher.close();
+      if (session.process !== process || session.variantIndex !== variantIndex) {
+        return;
+      }
+      session.paused = false;
+      session.process = null;
+      if (code) {
+        this.logger.error(
+          `FFmpeg exited with code ${code} for variant ${variantIndex} asset ${session.assetId}\n${stderr}`,
+        );
+        void this.failSession(session, `Transcoding process exited unexpectedly with code ${code}`).catch((error) =>
+          this.logger.error(`Failed to end session ${session.id} after ffmpeg exit: ${error}`),
+        );
+      }
+    });
+  }
+
+  private stopTranscode(session: Session) {
+    if (!session.process) {
+      return;
+    }
+    // SIGTERM makes it rename .tmp segments to .m4s even if they're still incomplete
+    session.process.kill('SIGKILL');
+    session.process = null;
+    session.lastCompletedSegment = null;
+    session.paused = false;
+    this.logger.debug(`Stopped transcoding for session ${session.id}`);
+  }
+
+  private pauseTranscode(session: Session) {
+    if (session.paused || !session.process) {
+      return;
+    }
+    session.process.kill('SIGSTOP');
+    session.paused = true;
+    this.logger.debug(`Paused transcoding for session ${session.id}`);
+  }
+
+  private resumeTranscode(session: Session) {
+    if (!session.paused || !session.process) {
+      return;
+    }
+    session.process.kill('SIGCONT');
+    session.paused = false;
+    this.logger.debug(`Resumed transcoding for session ${session.id}`);
+  }
+
+  private async removeSessionDir(session: { ownerId: string; id: string }) {
+    const dir = StorageCore.getHlsSessionFolder({ ownerId: session.ownerId, sessionId: session.id });
+    try {
+      await this.storageRepository.unlinkDir(dir, { recursive: true, force: true });
+    } catch (error) {
+      if ((error as NodeJS.ErrnoException)?.code !== 'ENOENT') {
+        throw error;
+      }
+      this.logger.warn(`Session dir ${dir} does not exist.`);
+    }
+  }
+
+  private removeInactiveSessions() {
+    const cutoff = Date.now() - HLS_INACTIVITY_TIMEOUT_MS;
+    const inactiveSessions = [...this.sessions.values()].filter((s) => s.lastActivityTime.getTime() < cutoff);
+    return Promise.all(
+      inactiveSessions.map(async (session) => {
+        try {
+          this.websocketRepository.serverSend('HlsSessionEnd', { sessionId: session.id });
+          await this.onSessionEnd({ sessionId: session.id });
+        } catch (error) {
+          this.logger.error(`Failed to sweep inactive HLS session ${session.id}: ${error}`);
+        }
+      }),
+    );
+  }
+
+  private removeExpiredSessions() {
+    return this.databaseRepository.withLock(DatabaseLock.HlsSessionCleanup, async () => {
+      const expiredSessions = await this.videoStreamRepository.getExpiredSessions();
+      await Promise.all(
+        expiredSessions.map(async (session) => {
+          await this.removeSessionDir(session);
+          await this.videoStreamRepository.deleteSession(session.id);
+        }),
+      );
+    });
+  }
+}
diff --git a/server/src/types.ts b/server/src/types.ts
index c7dc1f5e18..9d83d844e4 100644
--- a/server/src/types.ts
+++ b/server/src/types.ts
@@ -28,7 +28,6 @@ import {
   SystemMetadataKey,
   TranscodeTarget,
   UserMetadataKey,
-  VideoCodec,
   WorkflowTrigger,
   WorkflowType,
 } from 'src/enum';
@@ -162,6 +161,25 @@ export interface TranscodeCommand {
   };
 }
 
+export interface VideoTuning {
+  strictGop: boolean;
+  lowLatency: boolean;
+}
+
+export interface HlsCommandOptions {
+  initFilename: string;
+  inputPath: string;
+  packetCount: number;
+  playlistFilename: string;
+  seekSeconds?: number;
+  segmentDuration: number;
+  segmentFilename: string;
+  startSegment: number;
+  target: TranscodeTarget;
+  timeBase: number;
+  totalDuration: number;
+}
+
 export interface BitrateDistribution {
   max: number;
   target: number;
@@ -177,14 +195,11 @@ export interface ImageBuffer {
 export interface VideoCodecSWConfig {
   getCommand(
     target: TranscodeTarget,
-    videoStream: VideoStreamInfo,
-    audioStream?: AudioStreamInfo,
+    video: VideoStreamInfo,
+    audio?: AudioStreamInfo,
     format?: VideoFormat,
   ): TranscodeCommand;
-}
-
-export interface VideoCodecHWConfig extends VideoCodecSWConfig {
-  getSupportedCodecs(): Array<VideoCodec>;
+  getHlsCommand(options: HlsCommandOptions, video: VideoStreamInfo, audio?: AudioStreamInfo): string[];
 }
 
 export interface ProbeOptions {
@@ -371,6 +386,7 @@ export type JobItem =
 
   // Cleanup
   | { name: JobName.SessionCleanup; data?: IBaseJob }
+  | { name: JobName.HlsSessionCleanup; data?: IBaseJob }
 
   // Tags
   | { name: JobName.TagCleanup; data?: IBaseJob }
diff --git a/server/src/utils/database.ts b/server/src/utils/database.ts
index fbf32c0ac2..cb942b5366 100644
--- a/server/src/utils/database.ts
+++ b/server/src/utils/database.ts
@@ -71,10 +71,13 @@ export const removeUndefinedKeys = <T extends object>(update: T, template: unkno
 };
 
 export const ASSET_CHECKSUM_CONSTRAINT = 'UQ_assets_owner_checksum';
+export const VIDEO_STREAM_SESSION_PK_CONSTRAINT = 'video_stream_session_pkey';
 
-export const isAssetChecksumConstraint = (error: unknown) => {
-  return (error as PostgresError)?.constraint_name === 'UQ_assets_owner_checksum';
-};
+export const isAssetChecksumConstraint = (error: unknown) =>
+  (error as PostgresError)?.constraint_name === ASSET_CHECKSUM_CONSTRAINT;
+
+export const isVideoStreamSessionPkConstraint = (error: unknown) =>
+  (error as PostgresError)?.constraint_name === VIDEO_STREAM_SESSION_PK_CONSTRAINT;
 
 export function withDefaultVisibility<O>(qb: SelectQueryBuilder<DB, 'asset', O>) {
   return qb.where('asset.visibility', 'in', [sql.lit(AssetVisibility.Archive), sql.lit(AssetVisibility.Timeline)]);
diff --git a/server/src/utils/event.ts b/server/src/utils/event.ts
new file mode 100644
index 0000000000..fd791620de
--- /dev/null
+++ b/server/src/utils/event.ts
@@ -0,0 +1,50 @@
+import { ArgOf, EmitEvent } from 'src/repositories/event.repository';
+
+export class PendingEvents<T extends { [T in EmitEvent]: ArgOf<T> extends { error?: string } ? T : never }[EmitEvent]> {
+  private pending = new Map<string, { completers: PromiseWithResolvers<ArgOf<T>>[]; timeout: NodeJS.Timeout }>();
+  private timeoutMs: number;
+
+  constructor({ timeoutMs }: { timeoutMs: number }) {
+    this.timeoutMs = timeoutMs;
+  }
+
+  wait(key: string): Promise<ArgOf<T>> {
+    const completer = Promise.withResolvers<ArgOf<T>>();
+    const existing = this.pending.get(key);
+    if (existing) {
+      existing.completers.push(completer);
+      return completer.promise;
+    }
+
+    const timeout = setTimeout(() => this.complete(key, { error: 'Request timed out' }), this.timeoutMs);
+    this.pending.set(key, { completers: [completer], timeout });
+    return completer.promise;
+  }
+
+  complete(key: string, value: ArgOf<T> | { error: string }) {
+    const pending = this.pending.get(key);
+    if (!pending) {
+      return;
+    }
+    clearTimeout(pending.timeout);
+    this.pending.delete(key);
+    if ('error' in value) {
+      const error = new Error(value.error);
+      for (const completer of pending.completers) {
+        completer.reject(error);
+      }
+    } else {
+      for (const completer of pending.completers) {
+        completer.resolve(value);
+      }
+    }
+  }
+
+  rejectByPrefix(prefix: string, error: string) {
+    for (const key of this.pending.keys()) {
+      if (key.startsWith(prefix)) {
+        this.complete(key, { error });
+      }
+    }
+  }
+}
diff --git a/server/src/utils/media.ts b/server/src/utils/media.ts
index 49e11edab7..b3a617c36e 100644
--- a/server/src/utils/media.ts
+++ b/server/src/utils/media.ts
@@ -1,4 +1,4 @@
-import { AUDIO_ENCODER } from 'src/constants';
+import { AUDIO_ENCODER, SUPPORTED_HWA_CODECS } from 'src/constants';
 import { SystemConfigFFmpegDto } from 'src/dtos/system-config.dto';
 import {
   ColorMatrix,
@@ -13,38 +13,56 @@ import {
 import {
   AudioStreamInfo,
   BitrateDistribution,
+  HlsCommandOptions,
   TranscodeCommand,
-  VideoCodecHWConfig,
   VideoCodecSWConfig,
   VideoFormat,
   VideoInterfaces,
   VideoStreamInfo,
+  VideoTuning,
 } from 'src/types';
 
+export const isVideoRotated = (videoStream: VideoStreamInfo): boolean => Math.abs(videoStream.rotation) === 90;
+
+export const isVideoVertical = (videoStream: VideoStreamInfo): boolean =>
+  videoStream.height > videoStream.width || isVideoRotated(videoStream);
+
+export const getOutputSize = (videoStream: VideoStreamInfo, targetRes: number) => {
+  const factor = Math.max(videoStream.height, videoStream.width) / Math.min(videoStream.height, videoStream.width);
+  let larger = Math.round(targetRes * factor);
+  if (larger % 2 !== 0) {
+    larger -= 1;
+  }
+  return isVideoVertical(videoStream) ? { width: targetRes, height: larger } : { width: larger, height: targetRes };
+};
+
 export class BaseConfig implements VideoCodecSWConfig {
   readonly presets = ['veryslow', 'slower', 'slow', 'medium', 'fast', 'faster', 'veryfast', 'superfast', 'ultrafast'];
-  protected constructor(protected config: SystemConfigFFmpegDto) {}
+  protected constructor(
+    protected config: SystemConfigFFmpegDto,
+    protected tune: VideoTuning = { strictGop: false, lowLatency: false },
+  ) {}
 
-  static create(config: SystemConfigFFmpegDto, interfaces: VideoInterfaces): VideoCodecSWConfig {
+  static create(config: SystemConfigFFmpegDto, interfaces: VideoInterfaces, tune?: VideoTuning) {
     if (config.accel === TranscodeHardwareAcceleration.Disabled) {
-      return this.getSWCodecConfig(config);
+      return this.getSWCodecConfig(config, tune);
     }
-    return this.getHWCodecConfig(config, interfaces);
+    return this.getHWCodecConfig(config, interfaces, tune);
   }
 
-  private static getSWCodecConfig(config: SystemConfigFFmpegDto) {
+  private static getSWCodecConfig(config: SystemConfigFFmpegDto, tune?: VideoTuning): VideoCodecSWConfig {
     switch (config.targetVideoCodec) {
       case VideoCodec.H264: {
-        return new H264Config(config);
+        return new H264Config(config, tune);
       }
       case VideoCodec.Hevc: {
-        return new HEVCConfig(config);
+        return new HEVCConfig(config, tune);
       }
       case VideoCodec.Vp9: {
-        return new VP9Config(config);
+        return new VP9Config(config, tune);
       }
       case VideoCodec.Av1: {
-        return new AV1Config(config);
+        return new AV1Config(config, tune);
       }
       default: {
         throw new Error(`Codec '${config.targetVideoCodec}' is unsupported`);
@@ -52,72 +70,122 @@ export class BaseConfig implements VideoCodecSWConfig {
     }
   }
 
-  private static getHWCodecConfig(config: SystemConfigFFmpegDto, interfaces: VideoInterfaces) {
-    let handler: VideoCodecHWConfig;
+  private static getHWCodecConfig(config: SystemConfigFFmpegDto, interfaces: VideoInterfaces, tune?: VideoTuning) {
+    if (!SUPPORTED_HWA_CODECS[config.accel].includes(config.targetVideoCodec)) {
+      throw new Error(
+        `${config.accel.toUpperCase()} acceleration does not support codec '${config.targetVideoCodec.toUpperCase()}'. Supported codecs: ${SUPPORTED_HWA_CODECS[config.accel]}`,
+      );
+    }
+
+    let handler: VideoCodecSWConfig;
     switch (config.accel) {
       case TranscodeHardwareAcceleration.Nvenc: {
         handler = config.accelDecode
-          ? new NvencHwDecodeConfig(config, interfaces)
-          : new NvencSwDecodeConfig(config, interfaces);
+          ? new NvencHwDecodeConfig(config, interfaces, tune)
+          : new NvencSwDecodeConfig(config, interfaces, tune);
         break;
       }
       case TranscodeHardwareAcceleration.Qsv: {
         handler = config.accelDecode
-          ? new QsvHwDecodeConfig(config, interfaces)
-          : new QsvSwDecodeConfig(config, interfaces);
+          ? new QsvHwDecodeConfig(config, interfaces, tune)
+          : new QsvSwDecodeConfig(config, interfaces, tune);
         break;
       }
       case TranscodeHardwareAcceleration.Vaapi: {
         handler = config.accelDecode
-          ? new VaapiHwDecodeConfig(config, interfaces)
-          : new VaapiSwDecodeConfig(config, interfaces);
+          ? new VaapiHwDecodeConfig(config, interfaces, tune)
+          : new VaapiSwDecodeConfig(config, interfaces, tune);
         break;
       }
       case TranscodeHardwareAcceleration.Rkmpp: {
         handler = config.accelDecode
-          ? new RkmppHwDecodeConfig(config, interfaces)
-          : new RkmppSwDecodeConfig(config, interfaces);
+          ? new RkmppHwDecodeConfig(config, interfaces, tune)
+          : new RkmppSwDecodeConfig(config, interfaces, tune);
         break;
       }
       default: {
         throw new Error(`${config.accel.toUpperCase()} acceleration is unsupported`);
       }
     }
-    if (!handler.getSupportedCodecs().includes(config.targetVideoCodec)) {
-      throw new Error(
-        `${config.accel.toUpperCase()} acceleration does not support codec '${config.targetVideoCodec.toUpperCase()}'. Supported codecs: ${handler.getSupportedCodecs()}`,
-      );
-    }
 
     return handler;
   }
 
-  getCommand(
-    target: TranscodeTarget,
-    videoStream: VideoStreamInfo,
-    audioStream?: AudioStreamInfo,
-    format?: VideoFormat,
-  ) {
+  getCommand(target: TranscodeTarget, video: VideoStreamInfo, audio?: AudioStreamInfo, format?: VideoFormat) {
     const options = {
-      inputOptions: this.getBaseInputOptions(videoStream, format),
-      outputOptions: [...this.getBaseOutputOptions(target, videoStream, audioStream), '-v', 'verbose'],
+      inputOptions: this.getBaseInputOptions(video, format),
+      outputOptions: [
+        ...this.getBaseOutputOptions(target, video, audio),
+        ...this.getPresetOptions(),
+        ...this.getBitrateOptions(),
+        ...this.getEncoderOptions(),
+        '-movflags',
+        'faststart',
+        '-fps_mode',
+        'passthrough',
+        '-v',
+        'verbose',
+      ],
       twoPass: this.eligibleForTwoPass(),
-      progress: { frameCount: videoStream.frameCount, percentInterval: 5 },
+      progress: { frameCount: video.frameCount, percentInterval: 5 },
     } as TranscodeCommand;
     if ([TranscodeTarget.All, TranscodeTarget.Video].includes(target)) {
-      const filters = this.getFilterOptions(videoStream);
+      const filters = this.getFilterOptions(video);
       if (filters.length > 0) {
         options.outputOptions.push('-vf', filters.join(','));
       }
     }
 
-    options.outputOptions.push(
+    return options;
+  }
+
+  getHlsCommand(options: HlsCommandOptions, video: VideoStreamInfo, audio?: AudioStreamInfo) {
+    const args: string[] = this.getBaseInputOptions(video);
+    if (options.seekSeconds) {
+      args.push('-ss', String(options.seekSeconds));
+    }
+    args.push(
+      '-nostdin',
+      '-nostats',
+      '-i',
+      options.inputPath,
+      ...this.getBaseOutputOptions(options.target, video, audio),
       ...this.getPresetOptions(),
-      ...this.getOutputThreadOptions(),
       ...this.getBitrateOptions(),
+      ...this.getEncoderOptions(),
+      '-copyts',
+      '-r',
+      `${options.packetCount * options.timeBase}/${options.totalDuration}`,
+      '-avoid_negative_ts',
+      'disabled',
+      '-f',
+      'hls',
+      '-hls_time',
+      String(options.segmentDuration),
+      '-hls_list_size',
+      '0',
+      '-hls_segment_type',
+      'fmp4',
+      '-hls_fmp4_init_filename',
+      options.initFilename,
+      '-hls_segment_options',
+      'movflags=+frag_discont',
+      '-hls_flags',
+      'temp_file',
+      '-hls_segment_filename',
+      options.segmentFilename,
+      '-start_number',
+      String(options.startSegment),
     );
 
-    return options;
+    if ([TranscodeTarget.All, TranscodeTarget.Video].includes(options.target)) {
+      const filters = this.getFilterOptions(video);
+      if (filters.length > 0) {
+        args.push('-vf', filters.join(','));
+      }
+    }
+    args.push(options.playlistFilename);
+    return args;
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
@@ -129,23 +197,7 @@ export class BaseConfig implements VideoCodecSWConfig {
     const videoCodec = [TranscodeTarget.All, TranscodeTarget.Video].includes(target) ? this.getVideoCodec() : 'copy';
     const audioCodec = [TranscodeTarget.All, TranscodeTarget.Audio].includes(target) ? this.getAudioEncoder() : 'copy';
 
-    const options = [
-      '-c:v',
-      videoCodec,
-      '-c:a',
-      audioCodec,
-      // Makes a second pass moving the moov atom to the
-      // beginning of the file for improved playback speed.
-      '-movflags',
-      'faststart',
-      '-fps_mode',
-      'passthrough',
-      '-map',
-      `0:${videoStream.index}`,
-      '-map_metadata',
-      '-1',
-    ];
-
+    const options = ['-c:v', videoCodec, '-c:a', audioCodec, '-map', `0:${videoStream.index}`, '-map_metadata', '-1'];
     if (audioStream) {
       options.push('-map', `0:${audioStream.index}`);
     }
@@ -157,18 +209,22 @@ export class BaseConfig implements VideoCodecSWConfig {
     }
     if (this.getGopSize() > 0) {
       options.push('-g', `${this.getGopSize()}`);
+      if (this.tune.strictGop) {
+        options.push('-keyint_min', `${this.getGopSize()}`);
+      }
     }
-
-    if (
-      this.config.targetVideoCodec === VideoCodec.Hevc &&
-      (videoCodec !== 'copy' || videoStream.codecName === 'hevc')
-    ) {
+    const isHvc = (videoCodec === 'copy' ? videoStream.codecName : videoCodec) === VideoCodec.Hevc;
+    if (isHvc) {
       options.push('-tag:v', 'hvc1');
     }
 
     return options;
   }
 
+  getEncoderOptions(): string[] {
+    return [];
+  }
+
   getFilterOptions(videoStream: VideoStreamInfo) {
     const options = [];
     if (this.shouldScale(videoStream)) {
@@ -272,25 +328,7 @@ export class BaseConfig implements VideoCodecSWConfig {
 
   getScaling(videoStream: VideoStreamInfo, mult = 2) {
     const targetResolution = this.getTargetResolution(videoStream);
-    return this.isVideoVertical(videoStream) ? `${targetResolution}:-${mult}` : `-${mult}:${targetResolution}`;
-  }
-
-  getSize(videoStream: VideoStreamInfo) {
-    const smaller = this.getTargetResolution(videoStream);
-    const factor = Math.max(videoStream.height, videoStream.width) / Math.min(videoStream.height, videoStream.width);
-    let larger = Math.round(smaller * factor);
-    if (larger % 2 !== 0) {
-      larger -= 1;
-    }
-    return this.isVideoVertical(videoStream) ? { width: smaller, height: larger } : { width: larger, height: smaller };
-  }
-
-  isVideoRotated(videoStream: VideoStreamInfo) {
-    return Math.abs(videoStream.rotation) === 90;
-  }
-
-  isVideoVertical(videoStream: VideoStreamInfo) {
-    return videoStream.height > videoStream.width || this.isVideoRotated(videoStream);
+    return isVideoVertical(videoStream) ? `${targetResolution}:-${mult}` : `-${mult}:${targetResolution}`;
   }
 
   isBitrateConstrained() {
@@ -353,23 +391,18 @@ export class BaseConfig implements VideoCodecSWConfig {
   }
 }
 
-export class BaseHWConfig extends BaseConfig implements VideoCodecHWConfig {
+export class BaseHWConfig extends BaseConfig {
   protected device: string;
-  protected interfaces: VideoInterfaces;
 
   constructor(
     protected config: SystemConfigFFmpegDto,
-    interfaces: VideoInterfaces,
+    protected interfaces: VideoInterfaces,
+    tune?: VideoTuning,
   ) {
-    super(config);
-    this.interfaces = interfaces;
+    super(config, tune);
     this.device = this.getDevice(interfaces);
   }
 
-  getSupportedCodecs() {
-    return [VideoCodec.H264, VideoCodec.Hevc];
-  }
-
   validateDevices(devices: string[]) {
     if (devices.length === 0) {
       throw new Error('No /dev/dri devices found. If using Docker, make sure at least one /dev/dri device is mounted');
@@ -474,24 +507,32 @@ export class ThumbnailConfig extends BaseConfig {
 }
 
 export class H264Config extends BaseConfig {
-  getOutputThreadOptions() {
-    const options = super.getOutputThreadOptions();
-    if (this.config.threads === 1) {
-      options.push('-x264-params', 'frame-threads=1:pools=none');
+  getEncoderOptions(): string[] {
+    const out = this.getOutputThreadOptions();
+    if (this.tune.strictGop) {
+      out.push('-sc_threshold:v', '0');
     }
-
-    return options;
+    if (this.config.threads === 1) {
+      out.push('-x264-params', 'frame-threads=1:pools=none');
+    }
+    return out;
   }
 }
 
 export class HEVCConfig extends BaseConfig {
-  getOutputThreadOptions() {
-    const options = super.getOutputThreadOptions();
-    if (this.config.threads === 1) {
-      options.push('-x265-params', 'frame-threads=1:pools=none');
+  getEncoderOptions(): string[] {
+    const out: string[] = this.getOutputThreadOptions();
+    const params: string[] = [];
+    if (this.tune.strictGop) {
+      params.push('no-scenecut=1', 'no-open-gop=1');
     }
-
-    return options;
+    if (this.config.threads === 1) {
+      params.push('frame-threads=1', 'pools=none');
+    }
+    if (params.length > 0) {
+      out.push('-x265-params', params.join(':'));
+    }
+    return out;
   }
 }
 
@@ -520,8 +561,8 @@ export class VP9Config extends BaseConfig {
     return [`-${this.useCQP() ? 'q:v' : 'crf'}`, `${this.config.crf}`, '-b:v', `${bitrates.max}${bitrates.unit}`];
   }
 
-  getOutputThreadOptions() {
-    return ['-row-mt', '1', ...super.getOutputThreadOptions()];
+  getEncoderOptions(): string[] {
+    return ['-row-mt', '1', ...this.getOutputThreadOptions()];
   }
 
   eligibleForTwoPass() {
@@ -543,23 +584,22 @@ export class AV1Config extends BaseConfig {
   }
 
   getBitrateOptions() {
-    const options = ['-crf', `${this.config.crf}`];
-    const bitrates = this.getBitrateDistribution();
-    const svtparams = [];
-    if (this.config.threads > 0) {
-      svtparams.push(`lp=${this.config.threads}`);
-    }
-    if (bitrates.max > 0) {
-      svtparams.push(`mbr=${bitrates.max}${bitrates.unit}`);
-    }
-    if (svtparams.length > 0) {
-      options.push('-svtav1-params', svtparams.join(':'));
-    }
-    return options;
+    return ['-crf', `${this.config.crf}`];
   }
 
-  getOutputThreadOptions() {
-    return []; // Already set above with svtav1-params
+  getEncoderOptions(): string[] {
+    const params: string[] = [];
+    if (this.tune.lowLatency) {
+      params.push('hierarchical-levels=3', 'lookahead=0', 'enable-tf=0');
+    }
+    if (this.config.threads > 0) {
+      params.push(`lp=${this.config.threads}`);
+    }
+    const bitrates = this.getBitrateDistribution();
+    if (bitrates.max > 0) {
+      params.push(`mbr=${bitrates.max}${bitrates.unit}`);
+    }
+    return params.length > 0 ? ['-svtav1-params', params.join(':')] : [];
   }
 
   eligibleForTwoPass() {
@@ -572,10 +612,6 @@ export class NvencSwDecodeConfig extends BaseHWConfig {
     return '0';
   }
 
-  getSupportedCodecs() {
-    return [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Av1];
-  }
-
   getBaseInputOptions() {
     return ['-init_hw_device', `cuda=cuda:${this.device}`, '-filter_hw_device', 'cuda'];
   }
@@ -652,6 +688,14 @@ export class NvencSwDecodeConfig extends BaseHWConfig {
     return [];
   }
 
+  getEncoderOptions(): string[] {
+    const out = this.getOutputThreadOptions();
+    if (this.tune.strictGop) {
+      out.push('-forced-idr', '1');
+    }
+    return out;
+  }
+
   getRefs() {
     const bframes = this.getBFrames();
     if (bframes > 0 && bframes < 3 && this.config.refs < 3) {
@@ -703,8 +747,8 @@ export class NvencHwDecodeConfig extends NvencSwDecodeConfig {
     return ['-threads', '1'];
   }
 
-  getOutputThreadOptions() {
-    return [];
+  getEncoderOptions(): string[] {
+    return this.tune.strictGop ? ['-forced-idr', '1'] : [];
   }
 }
 
@@ -749,10 +793,6 @@ export class QsvSwDecodeConfig extends BaseHWConfig {
     return options;
   }
 
-  getSupportedCodecs() {
-    return [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Vp9, VideoCodec.Av1];
-  }
-
   // recommended from https://github.com/intel/media-delivery/blob/master/doc/benchmarks/intel-iris-xe-max-graphics/intel-iris-xe-max-graphics.md
   getBFrames() {
     if (this.config.bframes < 0) {
@@ -775,6 +815,14 @@ export class QsvSwDecodeConfig extends BaseHWConfig {
   getScaling(videoStream: VideoStreamInfo): string {
     return super.getScaling(videoStream, 1);
   }
+
+  getEncoderOptions(): string[] {
+    const out = this.getOutputThreadOptions();
+    if (this.tune.strictGop) {
+      out.push('-idr_interval', '0');
+    }
+    return out;
+  }
 }
 
 export class QsvHwDecodeConfig extends QsvSwDecodeConfig {
@@ -888,13 +936,17 @@ export class VaapiSwDecodeConfig extends BaseHWConfig {
     return options;
   }
 
-  getSupportedCodecs() {
-    return [VideoCodec.H264, VideoCodec.Hevc, VideoCodec.Vp9, VideoCodec.Av1];
-  }
-
   useCQP() {
     return this.config.cqMode !== CQMode.Icq || this.config.targetVideoCodec === VideoCodec.Vp9;
   }
+
+  getEncoderOptions(): string[] {
+    const out = this.getOutputThreadOptions();
+    if (this.tune.strictGop) {
+      out.push('-idr_interval', '0');
+    }
+    return out;
+  }
 }
 
 export class VaapiHwDecodeConfig extends VaapiSwDecodeConfig {
@@ -988,10 +1040,6 @@ export class RkmppSwDecodeConfig extends BaseHWConfig {
     return ['-rc_mode', 'CQP', '-qp_init', `${this.config.crf}`];
   }
 
-  getSupportedCodecs() {
-    return [VideoCodec.H264, VideoCodec.Hevc];
-  }
-
   getVideoCodec(): string {
     return `${this.config.targetVideoCodec}_rkmpp`;
   }
diff --git a/server/test/fixtures/media.stub.ts b/server/test/fixtures/media.stub.ts
index f034ab873d..7edd1c2dee 100644
--- a/server/test/fixtures/media.stub.ts
+++ b/server/test/fixtures/media.stub.ts
@@ -597,7 +597,7 @@ export const train = {
   packets: {
     totalDuration: 12_290,
     packetCount: 1229,
-    outputFrames: 1303,
+    outputFrames: 1304,
     keyframePts: [
       0, 601, 1201, 1802, 2402, 3003, 3604, 4204, 4805, 5405, 6006, 6607, 7207, 7808, 8408, 9009, 9609, 10_210, 10_811,
       11_411, 12_062, 12_703,
diff --git a/server/test/repositories/storage.repository.mock.ts b/server/test/repositories/storage.repository.mock.ts
index 334d7d0d53..c1fb7ceaa6 100644
--- a/server/test/repositories/storage.repository.mock.ts
+++ b/server/test/repositories/storage.repository.mock.ts
@@ -75,5 +75,6 @@ export const newStorageRepositoryMock = (): Mocked<RepositoryInterface<StorageRe
     copyFile: vitest.fn(),
     utimes: vitest.fn(),
     watch: vitest.fn().mockImplementation(makeMockWatcher({})),
+    watchDir: vitest.fn().mockImplementation(() => ({ close: vitest.fn(), on: vitest.fn() })),
   };
 };
diff --git a/server/test/utils.ts b/server/test/utils.ts
index 75ada7b551..e707971aad 100644
--- a/server/test/utils.ts
+++ b/server/test/utils.ts
@@ -181,7 +181,11 @@ export const automock = <T>(
   const mocks: Mock[] = [];
 
   const instance = new Dependency(...args);
-  for (const property of Object.getOwnPropertyNames(Dependency.prototype)) {
+  const propertyNames = new Set([
+    ...Object.getOwnPropertyNames(Dependency.prototype),
+    ...Object.getOwnPropertyNames(instance),
+  ]);
+  for (const property of propertyNames) {
     if (property === 'constructor') {
       continue;
     }
@@ -346,7 +350,7 @@ export const getMocks = () => {
     trash: automock(TrashRepository),
     user: automock(UserRepository, { strict: false }),
     versionHistory: automock(VersionHistoryRepository),
-    videoStream: automock(VideoStreamRepository),
+    videoStream: automock(VideoStreamRepository, { strict: false }),
     view: automock(ViewRepository),
     // eslint-disable-next-line no-sparse-arrays
     websocket: automock(WebsocketRepository, { args: [, loggerMock], strict: false }),
@@ -500,6 +504,7 @@ export const mockSpawn = vitest.fn((exitCode: number, stdout: string, stderr: st
         callback(exitCode);
       }
     }),
+    kill: vitest.fn(),
   } as unknown as ChildProcessWithoutNullStreams;
 });
 
diff --git a/server/tsconfig.json b/server/tsconfig.json
index e087544f6b..c3aede3e5b 100644
--- a/server/tsconfig.json
+++ b/server/tsconfig.json
@@ -8,9 +8,9 @@
     "experimentalDecorators": true,
     "allowSyntheticDefaultImports": true,
     "resolveJsonModule": true,
-    "target": "es2022",
+    "target": "es2024",
     "moduleResolution": "node16",
-    "lib": ["dom", "es2023"],
+    "lib": ["dom", "es2024"],
     "sourceMap": true,
     "outDir": "./dist",
     "incremental": true,
diff --git a/web/src/routes/admin/system-settings/FFmpegSettings.svelte b/web/src/routes/admin/system-settings/FFmpegSettings.svelte
index 2fbc45ce2a..33d6ba84f6 100644
--- a/web/src/routes/admin/system-settings/FFmpegSettings.svelte
+++ b/web/src/routes/admin/system-settings/FFmpegSettings.svelte
@@ -388,6 +388,22 @@
             />
           </div>
         </SettingAccordion>
+
+        <SettingAccordion
+          key="realtime-transcoding"
+          title={$t('admin.transcoding_realtime')}
+          subtitle={$t('admin.transcoding_realtime_description')}
+        >
+          <div class="ms-4 mt-4 flex flex-col gap-4">
+            <SettingSwitch
+              title={$t('admin.transcoding_realtime_enabled')}
+              subtitle={$t('admin.transcoding_realtime_enabled_description')}
+              bind:checked={configToEdit.ffmpeg.realtime.enabled}
+              isEdited={configToEdit.ffmpeg.realtime.enabled !== configToEdit.ffmpeg.realtime.enabled}
+              {disabled}
+            />
+          </div>
+        </SettingAccordion>
       </div>
 
       <div class="ms-4">