[FFmpeg-devel] [PATCH RFC 0/6] MP4 editlist and HEVC decoder

[FFmpeg-devel] [PATCH RFC 0/6] MP4 editlist and HEVC decoder

[Zhao Zhili]

From: Zhao Zhili <zhilizhao@tencent.com>

Fix #11510

#11510 revealed multiple issues related to mp4 demuxer, hevc decoder
and videotoolbox.

1. mp4 demuxer output packets have rewind due to editlist,

POC		 POC
916 -----------> 944

then rewind back to

916 -----------> 944 942

2. Both POC 916 and POC 944 are CRA nalu, so no flush on output.

3. When decoding POC the second time, POC still inside DPB buffer.

Patch 1/6 fix videotoolbox which shouldn't reset when confronted with
    ReferenceMissingErr

Patch 2/6 is trial.

Patch 3/6 allow duplicated POC in DPB buffer. I'm not quite sure the
side effect.

Patch 4 to 6 add a flag to indicate the start of a new sequence, so
the decoder can flush on output. I know it looks suspicious, please
comment.

There are more general stream rewind issues to be resolved.

Zhao Zhili (6):
  avcodec/vt: Don't restart decoder when confronted with
    ReferenceMissingErr
  avformat/mov: generalize sgpd_sync index lookup
  avcodec/hevc: Don't drop packet with duplicate POC
  avcodec/packet: Add AV_PKT_FLAG_NEW_SEQUENCE flag
  avformat/mov: Notify new sequence at the start of editlist
  avcodec/hevc: Check AV_PKT_FLAG_NEW_SEQUENCE and flush pictures out

 libavcodec/hevc/hevcdec.c |  3 +++
 libavcodec/hevc/refs.c    |  4 ++--
 libavcodec/packet.h       | 10 ++++++++++
 libavcodec/videotoolbox.c | 10 ++++++----
 libavformat/avformat.h    |  2 ++
 libavformat/mov.c         | 21 ++++++++++++++-------
 6 files changed, 37 insertions(+), 13 deletions(-)

-- 
2.46.0

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Re: [FFmpeg-devel] [PATCH RFC 0/6] MP4 editlist and HEVC decoder

[Zhao Zhili]

> On Mar 18, 2025, at 20:58, Zhao Zhili <quinkblack-at-foxmail.com@ffmpeg.org> wrote:
> 
> From: Zhao Zhili <zhilizhao@tencent.com>
> 
> Fix #11510
> 
> #11510 revealed multiple issues related to mp4 demuxer, hevc decoder
> and videotoolbox.
> 
> 1. mp4 demuxer output packets have rewind due to editlist,
> 
> POC		 POC
> 916 -----------> 944
> 
> then rewind back to
> 
> 916 -----------> 944 942
> 
> 2. Both POC 916 and POC 944 are CRA nalu, so no flush on output.
> 
> 3. When decoding POC the second time, POC still inside DPB buffer.

I mean when decoding POC 944 the second time, POC 944 still inside
DPB buffer.

> 
> Patch 1/6 fix videotoolbox which shouldn't reset when confronted with
>    ReferenceMissingErr
> 
> Patch 2/6 is trial.
> 
> Patch 3/6 allow duplicated POC in DPB buffer. I'm not quite sure the
> side effect.
> 
> Patch 4 to 6 add a flag to indicate the start of a new sequence, so
> the decoder can flush on output. I know it looks suspicious, please
> comment.
> 
> There are more general stream rewind issues to be resolved.
> 
> Zhao Zhili (6):
>  avcodec/vt: Don't restart decoder when confronted with
>    ReferenceMissingErr
>  avformat/mov: generalize sgpd_sync index lookup
>  avcodec/hevc: Don't drop packet with duplicate POC
>  avcodec/packet: Add AV_PKT_FLAG_NEW_SEQUENCE flag
>  avformat/mov: Notify new sequence at the start of editlist
>  avcodec/hevc: Check AV_PKT_FLAG_NEW_SEQUENCE and flush pictures out
> 
> libavcodec/hevc/hevcdec.c |  3 +++
> libavcodec/hevc/refs.c    |  4 ++--
> libavcodec/packet.h       | 10 ++++++++++
> libavcodec/videotoolbox.c | 10 ++++++----
> libavformat/avformat.h    |  2 ++
> libavformat/mov.c         | 21 ++++++++++++++-------
> 6 files changed, 37 insertions(+), 13 deletions(-)
> 
> -- 
> 2.46.0
> 
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> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

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