[FFmpeg-devel] [PATCH] lavf/movenc: Replace dts by pts to calculate duration

[mypopy at gmail.com]

On Fri, Nov 29, 2019 at 3:44 PM manuelyuan <manuelyuan at 163.com> wrote:
>
> Of course I did，and I can give you the bad case videos for your analysis if you need.
> How can I give them to you？
>
> At 2019-11-28 14:38:34, "Carl Eugen Hoyos" <ceffmpeg at gmail.com> wrote:
> >
> >
> >> Am 28.11.2019 um 03:34 schrieb manuelyuan <manuelyuan at 163.com>:
> >>
> >> In this case, the input video is of dynamic frame rate and we don't want to
> >> duplicate or drop frames, but the output video duration calculated by DTS is
> >> incorrect, I solved it by using PTS.
> >> There are many UGC videos with dynamic frame rates, which are represented by
> >> PTS jumps. After transcoding with ffmpeg -vsync 0 or -vsync 2, the output
> >> video duration becomes longer.By reading the code of x264/encoder/encoder.c,
> >> I found that in order to predict the B frame, x264 needs to ensure that there
> >> are enough reference frames when DTS = 0, so the DTS of these reference frames
> >> will subtract the cache time. However, the cache time includes the part of PTS
> >> jumps, which results in the abnormal small DTS.
> >
> >Do you have access to a stream analyser to verify the output file with your patch?
> >
I think you can open a ticket in trac (https://trac.ffmpeg.org/) and
upload/attached the sample to the ticket