diff --git a/transcoder/main.go b/transcoder/main.go
index 2c3d20db..562bdfa6 100644
--- a/transcoder/main.go
+++ b/transcoder/main.go
@@ -189,7 +189,7 @@ func (h *Handler) GetInfo(c echo.Context) error {
 //
 // Path: /:path/attachment/:name
 func (h *Handler) GetAttachment(c echo.Context) error {
-	path, sha, err := GetPath(c)
+	_, sha, err := GetPath(c)
 	if err != nil {
 		return err
 	}
@@ -198,12 +198,6 @@ func (h *Handler) GetAttachment(c echo.Context) error {
 		return err
 	}
 
-	wait, err := src.Extract(path, sha)
-	if err != nil {
-		return err
-	}
-	<-wait
-
 	ret := fmt.Sprintf("%s/%s/att/%s", src.Settings.Metadata, sha, name)
 	return c.File(ret)
 }
@@ -214,7 +208,7 @@ func (h *Handler) GetAttachment(c echo.Context) error {
 //
 // Path: /:path/subtitle/:name
 func (h *Handler) GetSubtitle(c echo.Context) error {
-	path, sha, err := GetPath(c)
+	_, sha, err := GetPath(c)
 	if err != nil {
 		return err
 	}
@@ -223,12 +217,6 @@ func (h *Handler) GetSubtitle(c echo.Context) error {
 		return err
 	}
 
-	wait, err := src.Extract(path, sha)
-	if err != nil {
-		return err
-	}
-	<-wait
-
 	ret := fmt.Sprintf("%s/%s/sub/%s", src.Settings.Metadata, sha, name)
 	return c.File(ret)
 }
diff --git a/transcoder/src/extract.go b/transcoder/src/extract.go
index 536b1e1d..79bf3603 100644
--- a/transcoder/src/extract.go
+++ b/transcoder/src/extract.go
@@ -9,60 +9,67 @@ import (
 
 var extracted = NewCMap[string, <-chan struct{}]()
 
-func Extract(path string, sha string) (<-chan struct{}, error) {
-	ret := make(chan struct{})
-	existing, created := extracted.GetOrSet(sha, ret)
-	if !created {
-		return existing, nil
+const ExtractVersion = 1
+
+func (s MetadataService) ExtractSubs(info *MediaInfo) (interface{}, error) {
+	get_running, set := s.extractLock.Start(info.Sha)
+	if get_running != nil {
+		return get_running()
 	}
 
-	go func() {
-		defer printExecTime("Starting extraction of %s", path)()
-		info, err := GetInfo(path, sha)
-		if err != nil {
-			extracted.Remove(sha)
-			close(ret)
-			return
-		}
-		attachment_path := fmt.Sprintf("%s/%s/att", Settings.Metadata, sha)
-		subs_path := fmt.Sprintf("%s/%s/sub", Settings.Metadata, sha)
-		os.MkdirAll(attachment_path, 0o755)
-		os.MkdirAll(subs_path, 0o755)
-
-		// If there is no subtitles, there is nothing to extract (also fonts would be useless).
-		if len(info.Subtitles) == 0 {
-			close(ret)
-			return
-		}
-
-		cmd := exec.Command(
-			"ffmpeg",
-			"-dump_attachment:t", "",
-			// override old attachments
-			"-y",
-			"-i", path,
-		)
-		cmd.Dir = attachment_path
-
-		for _, sub := range info.Subtitles {
-			if ext := sub.Extension; ext != nil {
-				cmd.Args = append(
-					cmd.Args,
-					"-map", fmt.Sprintf("0:s:%d", sub.Index),
-					"-c:s", "copy",
-					fmt.Sprintf("%s/%d.%s", subs_path, sub.Index, *ext),
-				)
-			}
-		}
-		log.Printf("Starting extraction with the command: %s", cmd)
-		cmd.Stdout = nil
-		err = cmd.Run()
-		if err != nil {
-			extracted.Remove(sha)
-			fmt.Println("Error starting ffmpeg extract:", err)
-		}
-		close(ret)
-	}()
-
-	return ret, nil
+	err := extractSubs(info)
+	if err != nil {
+		return set(nil, err)
+	}
+	_, err = s.database.NamedExec(
+		`update info set ver_extract = :version where sha = :sha`,
+		map[string]interface{}{
+			"sha":     info.Sha,
+			"version": ExtractVersion,
+		},
+	)
+	return set(nil, err)
+}
+
+func extractSubs(info *MediaInfo) error {
+	defer printExecTime("Starting extraction of %s", info.Path)()
+
+	attachment_path := fmt.Sprintf("%s/%s/att", Settings.Metadata, info.Sha)
+	subs_path := fmt.Sprintf("%s/%s/sub", Settings.Metadata, info.Sha)
+
+	os.MkdirAll(attachment_path, 0o755)
+	os.MkdirAll(subs_path, 0o755)
+
+	// If there is no subtitles, there is nothing to extract (also fonts would be useless).
+	if len(info.Subtitles) == 0 {
+		return nil
+	}
+
+	cmd := exec.Command(
+		"ffmpeg",
+		"-dump_attachment:t", "",
+		// override old attachments
+		"-y",
+		"-i", info.Path,
+	)
+	cmd.Dir = attachment_path
+
+	for _, sub := range info.Subtitles {
+		if ext := sub.Extension; ext != nil {
+			cmd.Args = append(
+				cmd.Args,
+				"-map", fmt.Sprintf("0:s:%d", sub.Index),
+				"-c:s", "copy",
+				fmt.Sprintf("%s/%d.%s", subs_path, sub.Index, *ext),
+			)
+		}
+	}
+	log.Printf("Starting extraction with the command: %s", cmd)
+	cmd.Stdout = nil
+	err := cmd.Run()
+	if err != nil {
+		fmt.Println("Error starting ffmpeg extract:", err)
+		return err
+	}
+	return nil
 }
diff --git a/transcoder/src/metadata.go b/transcoder/src/metadata.go
index 77c12687..13cc7063 100644
--- a/transcoder/src/metadata.go
+++ b/transcoder/src/metadata.go
@@ -8,6 +8,7 @@ type MetadataService struct {
 	database  *sqlx.DB
 	lock      *RunLock[string, *MediaInfo]
 	thumbLock *RunLock[string, interface{}]
+	extractLock *RunLock[string, interface{}]
 }
 
 func (s MetadataService) GetMetadata(path string, sha string) (*MediaInfo, error) {
@@ -19,6 +20,9 @@ func (s MetadataService) GetMetadata(path string, sha string) (*MediaInfo, error
 	if ret.Versions.Thumbs < ThumbsVersion {
 		go s.ExtractThumbs(path, sha)
 	}
+	if ret.Versions.Extract < ExtractVersion {
+		go s.ExtractSubs(ret)
+	}
 
 	return ret, nil
 }