Fix A/V desync when resuming HLS with video transcode + audio copy (#16580)

Fix A/V desync when resuming HLS with video transcode + audio copy

2 files changed, 7 insertions, 6 deletions

diff --git a/MediaBrowser.Model/Configuration/EncodingOptions.cs b/MediaBrowser.Model/Configuration/EncodingOptions.cs
index 98fc2e632f..f5bb5330ed 100644
--- a/MediaBrowser.Model/Configuration/EncodingOptions.cs
+++ b/MediaBrowser.Model/Configuration/EncodingOptions.cs
@@ -61,7 +61,7 @@ public class EncodingOptions
         SubtitleExtractionTimeoutMinutes = 30;
         AllowOnDemandMetadataBasedKeyframeExtractionForExtensions = ["mkv"];
         HardwareDecodingCodecs = ["h264", "vc1"];
-        HlsAudioSeekStrategy = HlsAudioSeekStrategy.DisableAccurateSeek;
+        HlsAudioSeekStrategy = HlsAudioSeekStrategy.TrimCopiedAudio;
     }
 
     /// <summary>
@@ -307,6 +307,6 @@ public class EncodingOptions
     /// <summary>
     /// Gets or sets the method used for audio seeking in HLS.
     /// </summary>
-    [DefaultValue(HlsAudioSeekStrategy.DisableAccurateSeek)]
+    [DefaultValue(HlsAudioSeekStrategy.TrimCopiedAudio)]
     public HlsAudioSeekStrategy HlsAudioSeekStrategy { get; set; }
 }
diff --git a/MediaBrowser.Model/Configuration/HlsAudioSeekStrategy.cs b/MediaBrowser.Model/Configuration/HlsAudioSeekStrategy.cs
index 49feeb435f..c9155faeb1 100644
--- a/MediaBrowser.Model/Configuration/HlsAudioSeekStrategy.cs
+++ b/MediaBrowser.Model/Configuration/HlsAudioSeekStrategy.cs
@@ -7,11 +7,12 @@ namespace MediaBrowser.Model.Configuration
     public enum HlsAudioSeekStrategy
     {
         /// <summary>
-        /// If the video stream is transcoded and the audio stream is copied,
-        /// seek the video stream to the same keyframe as the audio stream. The
-        /// resulting timestamps in the output streams may be inaccurate.
+        /// When video is transcoded and audio is copied, use a bitstream filter
+        /// to drop copied audio packets before the seek point, aligning them
+        /// with the accurately-seeked video. Timestamps are accurate and audio
+        /// remains stream-copied (no re-encoding overhead).
         /// </summary>
-        DisableAccurateSeek = 0,
+        TrimCopiedAudio = 0,
 
         /// <summary>
         /// Prevent audio streams from being copied if the video stream is transcoded.