[FFmpeg-devel] [PATCH 2/2] avformat/matroskadec: adjust the cluster time to the track timebase

[Steve Lhomme]

The Block timestamp read in matroska_parse_block() is in track timebase and is
passed on as such to the AVPacket which uses this timebase.

In the normal case the Cluster and Track timebases are the same because the
track->time_scale is 1.0. But when it is not the case, the values in Cluster
timebase need to be transformed in Track timebase so they can be added
together.
---
 libavformat/matroskadec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index ba0e2956df..137674c068 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -3581,7 +3581,8 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, AVBufferRef *buf
 
     if (cluster_time != (uint64_t) -1 &&
         (block_time >= 0 || cluster_time >= -block_time)) {
-        timecode = cluster_time + block_time - track->codec_delay_in_track_tb;
+        uint64_t timecode_cluster_in_track_tb = (double) cluster_time / track->time_scale;
+        timecode = timecode_cluster_in_track_tb + block_time - track->codec_delay_in_track_tb;
         if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE &&
             timecode < track->end_timecode)
             is_keyframe = 0;  /* overlapping subtitles are not key frame */
-- 
2.26.2