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

Hendrik Leppkes h.leppkes at gmail.com
Tue Sep 6 15:39:11 EEST 2016


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.

- Hendrik


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