Add extra movflags to fMP4 to take initial audio delay into account

Signed-off-by: nyanmisaka <nst799610810@gmail.com>

Jellyfin.Api/Controllers/DynamicHlsController.cs

@@ -46,6 +46,7 @@ public class DynamicHlsController : BaseJellyfinApiController
 
     private readonly Version _minFFmpegFlacInMp4 = new Version(6, 0);
     private readonly Version _minFFmpegX265BframeInFmp4 = new Version(7, 0, 1);
+    private readonly Version _minFFmpegHlsSegmentOptions = new Version(5, 0);
 
     private readonly ILibraryManager _libraryManager;
     private readonly IUserManager _userManager;
@@ -1606,6 +1607,7 @@ public class DynamicHlsController : BaseJellyfinApiController
         var segmentFormat = string.Empty;
         var segmentContainer = outputExtension.TrimStart('.');
         var inputModifier = _encodingHelper.GetInputModifier(state, _encodingOptions, segmentContainer);
+        var hlsArguments = $"-hls_playlist_type {(isEventPlaylist ? "event" : "vod")} -hls_list_size 0";
 
         if (string.Equals(segmentContainer, "ts", StringComparison.OrdinalIgnoreCase))
         {
@@ -1621,6 +1623,11 @@ public class DynamicHlsController : BaseJellyfinApiController
                 false => " -hls_fmp4_init_filename \"" + outputFileNameWithoutExtension + "-1" + outputExtension + "\""
             };
 
+            var useLegacySegmentOption = _mediaEncoder.EncoderVersion < _minFFmpegHlsSegmentOptions;
+
+            // fMP4 needs this flag to write the audio packet DTS/PTS including the initial delay into MOOF::TRAF::TFDT
+            hlsArguments += $" {(useLegacySegmentOption ? "-hls_ts_options" : "-hls_segment_options")} movflags=+frag_discont";
+
             segmentFormat = "fmp4" + outputFmp4HeaderArg;
         }
         else
@@ -1642,8 +1649,6 @@ public class DynamicHlsController : BaseJellyfinApiController
                 Path.GetFileNameWithoutExtension(outputPath));
         }
 
-        var hlsArguments = $"-hls_playlist_type {(isEventPlaylist ? "event" : "vod")} -hls_list_size 0";
-
         return string.Format(
             CultureInfo.InvariantCulture,
             "{0} {1} -map_metadata -1 -map_chapters -1 -threads {2} {3} {4} {5} -copyts -avoid_negative_ts disabled -max_muxing_queue_size {6} -f hls -max_delay 5000000 -hls_time {7} -hls_segment_type {8} -start_number {9}{10} -hls_segment_filename \"{11}\" {12} -y \"{13}\"",