[FFmpeg-devel] [PATCH] ffmpeg: drop format specific stream copy heuristics

[Clément Bœsch]

On Tue, Sep 06, 2016 at 02:39:11PM +0200, Hendrik Leppkes wrote:
> On Tue, Sep 6, 2016 at 2:21 PM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > On Tue, Sep 06, 2016 at 02:18:35PM +0200, Michael Niedermayer wrote:
> >> On Tue, Sep 06, 2016 at 04:57:06AM +0200, Michael Niedermayer wrote:
> >> > On Mon, Sep 05, 2016 at 10:04:35PM -0300, James Almer wrote:
> >> > > On 9/5/2016 12:41 PM, Michael Niedermayer wrote:
> >> > > > On Mon, Sep 05, 2016 at 04:41:52PM +0200, Clément Bœsch wrote:
> >> > > >> From: Clément Bœsch <clement at stupeflix.com>
> >> > > >>
> >> > > >> These adjusted codec fields do not seem to be in use anymore and prevent
> >> > > >> the convert of ffmpeg*.c to codecpar.
> >> > > >
> >> > > >  ./ffmpeg  -i ~/tickets/4914/xdcam8mp2-1s_small.ts -c:v copy out.mxf
> >> > > > fails, no output anymore
> >> > > >
> >> > > > ./ffmpeg -i matrixbench_mpeg2.mpg -c:v copy -t 1 test.avi
> >> > > > the output now has 600fps
> >> > >
> >> > > Even with this code in place the resulting stream in the avi is reported
> >> > > as 100 fps.
> >> >
> >> > that seems to be a regression since
> >> > 6f69f7a8bf6a0d013985578df2ef42ee6b1c7994
> >> >
> >> > IIRC the intended timebase is 1/50 for this kind of content
> >> > (allowing the support of interlaced and field duplicated content to
> >> >  appear later)
> >> >
> >> >
> >> > > And with or without the code, the resulting files play the
> >> > > same with the players i tried.
> >> >
> >> > Higher framerates / finer timebases need noticably more space to
> >> > be stored in avi, thats not the case for other formats and thats
> >> > one reason why avi is treated as a special case.
> >> >
> >> > ill try to look tomorrow why its 100fps since the previous
> >> > codecpar patches. Though 100fps is not nearly as bad as 600fps
> >> > 600 has ~6 times the overhead
> >>
> >> This regression is caused by ticks_per_frame beiing incorrect
> >>
> >> Ill send a patch to fix this
> >
> > patch attached
> >
> 
> 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"?

What if the ticks_per_frame was at AVStream level?

-- 
Clément B.