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[FFmpeg-devel,9/9] avformat/matroskaenc: Fix ReferenceBlock timestamp

Message ID 20191015111737.14246-9-andreas.rheinhardt@gmail.com
State Superseded
Headers show

Commit Message

Andreas Rheinhardt Oct. 15, 2019, 11:17 a.m. UTC
In order to indicate that the frames in a BlockGroup are not keyframes,
one has to add a ReferenceBlock element containing the timestamp of a
reference block that has already been written. The timestamp ought to be
relative to the timestamp of the block it is attached to. Yet the
Matroska muxer used the relative timestamp of the preceding block of the
track, i.e. the timestamp of the preceding block relative to the
timestamp of the cluster containing said block (that need not be the
cluster containing the current block). This has been fixed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
 libavformat/matroskaenc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 1a3d337e5b..cb608f3297 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -2182,9 +2182,9 @@  static void mkv_write_block(AVFormatContext *s, AVIOContext *pb,
     if (blockid == MATROSKA_ID_BLOCK && !keyframe) {
-        put_ebml_sint(pb, MATROSKA_ID_BLOCKREFERENCE, track->last_timestamp);
+        put_ebml_sint(pb, MATROSKA_ID_BLOCKREFERENCE, track->last_timestamp - ts);
-    track->last_timestamp = ts - mkv->cluster_pts;
+    track->last_timestamp = ts;
     if (discard_padding) {
         put_ebml_sint(pb, MATROSKA_ID_DISCARDPADDING, discard_padding);