diff --git a/transcoder/src/info.go b/transcoder/src/info.go
index 2caf1536..a1e167fb 100644
--- a/transcoder/src/info.go
+++ b/transcoder/src/info.go
@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"golang.org/x/text/language"
@@ -55,6 +56,9 @@ type MediaInfo struct {
 	Fonts []string `json:"fonts"`
 	/// The list of chapters. See Chapter for more information.
 	Chapters []Chapter `json:"chapters"`
+
+	/// lock used to read/set keyframes of video/audio
+	lock sync.Mutex
 }
 
 type Video struct {
diff --git a/transcoder/src/keyframes.go b/transcoder/src/keyframes.go
index 65c3910a..c13e1c15 100644
--- a/transcoder/src/keyframes.go
+++ b/transcoder/src/keyframes.go
@@ -89,11 +89,17 @@ type KeyframeKey struct {
 }
 
 func (s *MetadataService) GetKeyframes(info *MediaInfo, isVideo bool, idx uint32) (*Keyframe, error) {
+	info.lock.Lock()
+	var ret *Keyframe
 	if isVideo && info.Videos[idx].Keyframes != nil {
-		return info.Videos[idx].Keyframes, nil
+		ret = info.Videos[idx].Keyframes
 	}
 	if !isVideo && info.Audios[idx].Keyframes != nil {
-		return info.Audios[idx].Keyframes, nil
+		ret = info.Audios[idx].Keyframes
+	}
+	info.lock.Unlock()
+	if ret != nil {
+		return ret, nil
 	}
 
 	get_running, set := s.keyframeLock.Start(KeyframeKey{
@@ -111,6 +117,14 @@ func (s *MetadataService) GetKeyframes(info *MediaInfo, isVideo bool, idx uint32
 	}
 	kf.info.ready.Add(1)
 
+	info.lock.Lock()
+	if isVideo {
+		info.Videos[idx].Keyframes = kf
+	} else {
+		info.Audios[idx].Keyframes = kf
+	}
+	info.lock.Unlock()
+
 	go func() {
 		var table string
 		var err error