[FFmpeg-devel] [PATCH] avformat/matroskaenc: do not write timebase as framerate

[wm4]

On Sat, 28 Apr 2018 21:18:47 +0200
Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 2018-04-28 20:05 GMT+02:00, wm4 <nfxjfg at googlemail.com>:
> > On Sat, 28 Apr 2018 19:52:38 +0200
> > Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> >  
> >> 2018-04-28 19:24 GMT+02:00, wm4 <nfxjfg at googlemail.com>:  
> >> > If the API user doesn't set avg_frame_rate, matroskaenc will write the
> >> > current timebase as "default duration" for the video track. This makes
> >> > no sense, because the "default duration" implies the framerate of the
> >> > video. Since the timebase is forced to 1/1000, this will make the
> >> > resulting file claim 1000fps.
> >> >
> >> > Drop it and don't write the element. It's optional, so it's better not
> >> > to write it if the framerate is unknown.  
> >>
> >> (Isn't it default frame duration?)  
> >
> > The Matroska "spec" calls it DefaultDuration.  
> 
> Which sounds more similar to "default frame duration" than
> "framerate"...

It's the same thing, really. Technically the framerate is the inverse
of it.

> >> Please mention ticket #6386 if you commit.  
> >
> > So if this was known to you, and you even made a patch, why
> > did you never send the patch to the list?  
> 
> I am not convinced the patch is correct and the OP claimed
> that it did not fix the reported issue completely.
> 
> (And this was of course not known "to me" but to everybody.)

It definitely does fix the issue that ffmpeg writes files that mkv
demuxers, including ffmpeg's, detect as having video framerate of
1000hz.

I don't know what that issue is about and I don't care, it's just that
you posted a patch there that does exactly the same thing as mine. I'll
gladly leave that to you.

Will push tomorrow.