[FFmpeg-devel] [PATCH] ffmpeg: drop format specific stream copy heuristics
michael at niedermayer.cc
Tue Sep 6 18:23:10 EEST 2016
On Tue, Sep 06, 2016 at 11:32:24AM -0300, James Almer wrote:
> On 9/6/2016 9:57 AM, Clément Bœsch wrote:
> >> We don't have time_base in codecpar, so why do we need ticks per frame in it?
> >> >
> >> > Which time_base does it modify the interpretation of? The field should
> >> > be bundled with that, then.
> > When do we have a mismatch of st->time_base and that "codec time base"?
> st->time_base can be anything. Matroska for example is always 1/1000,
> and mpegps 1/90000.
> "Codec time_base" seems to be codec frame_rate * ticks_per_frame, so
> usually the same as frame_rate, except for codecs like h264 and mpeg2
> where it's twice that.
this only works when codecs use the frame or field rate as basis for
With some codecs that is syntactically not even possible
MPEG4 (ISO/IEC 14496-2) stores its timebase as 1/N not M/N for vfr
with for example 30000/1001 that would be different (1/30000) than the
frame rate (30000/1001) (which may be variable)
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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