[FFmpeg-devel] [PATCH] fftools/ffmpeg: Restore DTS correction for VP9 copies

[Danny Wu]

Fixes ticket 9086.

Since early 2021, some of YouTube's VP9 encodes have non-monotonous DTS.
This makes ffmpeg fatally fail when trying to copy or encode the V9 video.

ffmpeg already includes functionality to correct this, however it was
disabled without explanation for VP9 stream copies in
2e6636aa87303d37b112e79f093ca39500f92364

This patch restores the DTS correction logic, and allows ffmpeg to correctly
encode (invalid) videos produced by youtube.com. I have verified that frames
are NOT being cut (so it does not re-introduce 4313).
---
 fftools/ffmpeg.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 3ad11452da..67deb7762f 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -823,7 +823,6 @@ static void write_packet(OutputFile *of, AVPacket
*pkt, OutputStream *ost, int u
         }
         if ((st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO ||
st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO ||
st->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE) &&
             pkt->dts != AV_NOPTS_VALUE &&
-            !(st->codecpar->codec_id == AV_CODEC_ID_VP9 && ost->stream_copy) &&
             ost->last_mux_dts != AV_NOPTS_VALUE) {
             int64_t max = ost->last_mux_dts + !(s->oformat->flags &
AVFMT_TS_NONSTRICT);
             if (pkt->dts < max) {
-- 
2.17.1