On Thu, 28 Nov 2019, manuelyuan wrote:
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.
Did you post any reproduction case of what, exactly (which field in which
box), you think is wrong?
Right now, this patch, among other things, breaks the implied last
duration of the last packet in a fragment.
This can be reproduced by with the lavf-movenc test, like this:
$ make libavformat/tests/movenc
$ libavformat/tests/movenc -w
Then inspect vfr-noduration.mp4 (with a suitable tool, e.g. L-SMASH's
boxdumper). Previously, the last packet in each fragment got an
inferred/guessed duration (if the duration field of the AVFrame was zero)
based on earlier frame intervals, but with your patch it is zero.
I'm fairly convinced that most of the changes in your patch shouldn't be
made, but to make the discussion proceed you need to _exactly_ specify
what you think is wrong, in a way that others can reproduce.
// Martin
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