[FFmpeg-devel] [PATCH 3/3] lavfi: fix doxygen doc for AVFilterLink.time_base
stefasab at gmail.com
Fri Sep 16 21:29:36 CEST 2011
On date Friday 2011-09-16 12:49:57 +0200, Stefano Sabatini encoded:
> On date Friday 2011-09-16 11:55:27 +0200, Stefano Sabatini encoded:
> > On date Monday 2011-09-12 03:05:59 +0200, Michael Niedermayer encoded:
> > > On Sun, Sep 11, 2011 at 01:47:29PM +0200, Stefano Sabatini wrote:
> > [...]
> > > > Subject: [PATCH] lavfi: drop AVFilterLink.sample_rate at the next major bump
> > > >
> > > > Use time_base instead for storing such information.
> > > >
> > > > This avoids duplication of information, and simplifies PTS handling for
> > > > the unified API, as time_base can be used for computing both audio and
> > > > video buffers timestamps.
> > >
> > > iam ok with this, just one note to make sure we dont by mistake run in
> > > an issue with it
> > >
> > > mpeg-ps has a timebase of 90khz and samplerates of 44.1,48,22.05, ...
> > > that means if we want to preserve this through the filter chains
> > > (and i dont know if we want or dont want...)
> > > then we need both timebase & sample_rate
> > > otoh i dont mind at all to drop that extra complexity and use a
> > > timebase equal to the samplerate
> > Uhm, no strong opinion on this, in general timebase can be different
> > from 1/samplerate, so I'm not against keeping both fields if it makes
> > sense (does it?).
> > In case we want to follow this path: how to set correctly the
> > sample_rate/time_base in the link?
> > I suppose a possible approach may be:
> > 1. if both sample_rate and time_base are set, do nothing
> > 2. if the sample_rate is not set and time_base is, set the samplerate
> > to the value of time_base.den
> > 3. if time_base is not set and time_base is, set the time_base to
> > 1/samplerate.
> > 4. fail otherwise
> > So a source may decide to set either only the sample_rate or only the
> > time_base in an output link.
> > So it may set the time_base (in this case samplerate is set as
> > time_base.den), or the samplerate (in this case timebase is
> > set to 1/samplerate).
> This one should be simpler.
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