Skip SIDX in fMP4 HLS segments

Prevent FFmpeg's SIDX path from rewriting open-GOP boundary packet timestamps. HLS uses the media playlist for segment indexing and does not require the SIDX box.

1 files changed, 3 insertions, 2 deletions

diff --git a/Jellyfin.Api/Controllers/DynamicHlsController.cs b/Jellyfin.Api/Controllers/DynamicHlsController.cs
index 838f48949d..4aa728b5bf 100644
--- a/Jellyfin.Api/Controllers/DynamicHlsController.cs
+++ b/Jellyfin.Api/Controllers/DynamicHlsController.cs
@@ -1607,8 +1607,9 @@ public class DynamicHlsController : BaseJellyfinApiController
 
             if (state.VideoStream is not null && state.IsOutputVideo)
             {
-                // 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";
+                // fMP4 needs frag_discont to write the audio packet DTS/PTS including the initial delay into MOOF::TRAF::TFDT
+                // HLS does not use SIDX, and skipping it avoids FFmpeg rewriting open-GOP boundary packet PTS
+                hlsArguments += $" {(useLegacySegmentOption ? "-hls_ts_options" : "-hls_segment_options")} movflags=+frag_discont+skip_sidx";
             }
 
             segmentFormat = "fmp4" + outputFmp4HeaderArg;