[FFmpeg-cvslog] avcodec/avcodec: more verbose documentation for time_base

[Michael Niedermayer]

On Thu, Oct 16, 2014 at 09:56:49AM +0200, Clément Bœsch wrote:
> On Thu, Oct 16, 2014 at 01:43:27AM +0200, Michael Niedermayer wrote:
> > ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Thu Oct 16 00:13:45 2014 +0200| [7b6a97edd1b50c03ec9b30f5806a72036923bee4] | committer: Michael Niedermayer
> > 
> > avcodec/avcodec: more verbose documentation for time_base
> > 
> > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > 
> > > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7b6a97edd1b50c03ec9b30f5806a72036923bee4
> > ---
> > 
> >  libavcodec/avcodec.h |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > index cb0e744..3d6f7b9 100644
> > --- a/libavcodec/avcodec.h
> > +++ b/libavcodec/avcodec.h
> > @@ -1346,6 +1346,8 @@ typedef struct AVCodecContext {
> >       * of which frame timestamps are represented. For fixed-fps content,
> >       * timebase should be 1/framerate and timestamp increments should be
> >       * identically 1.
> 
> > +     * This often, but not always is the inverse of the frame rate or field rate
> > +     * for video.
> 
> Can you provide examples where it's not?

I would have thought that is quite widely known that timebases arent
always the inverse of framerates & fieldrates.
but if you want an example, lets pick mpeg4 (ISO/IEC 14496-2)
for variable fps material it stores timebases in the form 1/m
thus that would be 1/30000 for 30000/1001 based material with frame
drops or "duplicated fields/frames"

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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