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

[lance.lmwang@gmail.com]

On Tue, Mar 22, 2022 at 02:28:10PM +0100, Andreas Rheinhardt wrote:
> lance.lmwang@gmail.com:
> > On Fri, Mar 11, 2022 at 05:16:09PM +0100, Andreas Rheinhardt wrote:
> >> 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. 
> >>>
> >>
> >> You stated that you think that both files are valid, but you also said
> >> that you don't even know what this byte that is different actually means.
> >>
> >>> 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).  
> >>>
> >>
> >> The text about Timecode Sample Description reads as follows: "Frame
> >> duration: A 32-bit integer that indicates how long each frame lasts in
> >> real time." This implies that only one of the two files can be
> >> spec-compliant. I am not a mov/ISOBMFF expert, but it seems to me that
> >> the current way of doing things is wrong. But I wonder about whether
> >> your patch is correct for vfr content. Doesn't the property of being vfr
> >> need to be reflected in the timecodes somehow (with different durations
> >> for different packets)?
> > 
> > Andreas, I have updated the patch and remove the fate difference which is
> > caused by duration, do you have any other comments for v2 patch?
> > 
> 
> No.

Thanks, then will apply the v2 patchsetet.

> 
> - Andreas
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-- 
Thanks,
Limin Wang
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