Re: [FFmpeg-devel] [PATCH 1/2] avformat/movenc: initialize pts/dts/duration of timecode packet

[lance.lmwang@gmail.com]

On Fri, Mar 11, 2022 at 03:04:32PM +0100, Andreas Rheinhardt wrote:
> lance.lmwang@gmail.com:
> > On Wed, Mar 02, 2022 at 09:58:31PM +0800, lance.lmwang@gmail.com wrote:
> >> From: Limin Wang <lance.lmwang@gmail.com>
> >>
> >> Fix below error message when timecode packet is written.
> >> "Application provided duration: -9223372036854775808 / timestamp: -9223372036854775808 is out of range for mov/mp4 format"
> >>
> >> try to reproduce by:
> >> ffmpeg -y -f lavfi -i color -metadata "timecode=00:00:00:00" -t 1 test.mov
> >>
> >> Note although error message is printed, the timecode packet will be written anyway. So
> >> the patch 2/2 will try to change the log level to warning.
> >>
> >> The first two test case of fate-lavf-ismv have timecode setting, so the crc of ref data is different.
> >> Fixes ticket #9488
> >>
> >> Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
> >> ---
> >>  libavformat/movenc.c | 2 ++
> >>  tests/ref/lavf/ismv  | 4 ++--
> >>  2 files changed, 4 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> >> index 4c86891..74b94cd 100644
> >> --- a/libavformat/movenc.c
> >> +++ b/libavformat/movenc.c
> >> @@ -6383,6 +6383,8 @@ static int mov_create_timecode_track(AVFormatContext *s, int index, int src_inde
> >>      pkt->data = data;
> >>      pkt->stream_index = index;
> >>      pkt->flags = AV_PKT_FLAG_KEY;
> >> +    pkt->pts = pkt->dts = av_rescale_q(tc.start, av_inv_q(rate), (AVRational){1,mov->movie_timescale});
> >> +    pkt->duration = av_rescale_q(1, av_inv_q(rate), (AVRational){1,mov->movie_timescale});
> >>      pkt->size = 4;
> >>      AV_WB32(pkt->data, tc.start);
> >>      ret = ff_mov_write_packet(s, pkt);
> >> diff --git a/tests/ref/lavf/ismv b/tests/ref/lavf/ismv
> >> index ac7f72b..723b432 100644
> >> --- a/tests/ref/lavf/ismv
> >> +++ b/tests/ref/lavf/ismv
> >> @@ -1,7 +1,7 @@
> >> -48fb8d7a5d19bd60f3a49ccf4b7d6593 *tests/data/lavf/lavf.ismv
> >> +7a24b73c096ec0f13f0f7a2d9101c4c1 *tests/data/lavf/lavf.ismv
> >>  313169 tests/data/lavf/lavf.ismv
> >>  tests/data/lavf/lavf.ismv CRC=0x9d9a638a
> >> -d19cd8e310a2e94fe0a0d11c5dc29217 *tests/data/lavf/lavf.ismv
> >> +79646383fd099d45ad0d0c2791c601dd *tests/data/lavf/lavf.ismv
> >>  322075 tests/data/lavf/lavf.ismv
> >>  tests/data/lavf/lavf.ismv CRC=0xe8130120
> >>  3b6023766845b51b075aed474c00f73c *tests/data/lavf/lavf.ismv
> >> -- 
> >> 1.8.3.1
> >>
> > 
> > will apply the patch set tomorrow unless there are any objections.
> > 
> 
> You have not really answered whether the current files or the new files
> are spec-incompliant; you have just reported that one byte is different.

Sorry, I think I have said both current and new file is spec-compliant in the last
email. 

By Quicktime file format specs:
Section Timecode Sample Description, all tmcd field isn't used pts/dts.

As for where is the different for one byte, it's caused by pkt->duration. The
old is 0(uninitialized), after the patch it's 33(1 frame duration).  

> 
> - Andreas
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-- 
Thanks,
Limin Wang
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