[FFmpeg-devel] [PATCH 6/7] Implement settb filter.

Michael Niedermayer michaelni
Thu Jul 22 17:25:35 CEST 2010


On Thu, Jul 22, 2010 at 04:34:29PM +0200, Stefano Sabatini wrote:
> On date Thursday 2010-07-22 14:09:28 +0200, Michael Niedermayer encoded:
> > On Wed, Jul 21, 2010 at 06:00:05PM +0200, Stefano Sabatini wrote:
> > > ---
> > >  doc/filters.texi         |   19 +++++++++
> > >  libavfilter/Makefile     |    1 +
> > >  libavfilter/allfilters.c |    1 +
> > >  libavfilter/vf_settb.c   |   92 ++++++++++++++++++++++++++++++++++++++++++++++
> > >  4 files changed, 113 insertions(+), 0 deletions(-)
> > >  create mode 100644 libavfilter/vf_settb.c
> > 
> > i think a single filter that can modify timestamps and timebase would make
> > more sense than spliting this operation?
> > modifying tb implicates recaling timestamps anyway ...
> 
> I see these as two different operations, changing timebase is not
> implying a change of the absolute temporal value of the timestamps.
> 
> Alternatively we could have a setpts filter which accepts:
> outpts_expression:tb_num:tb_den
> 
> but I tend to prefer to keep distinct the two problems (and keep
> simple both filters).  Also note that in the case of settb the
> rescaling is done implicitely by the filter framework
> (avfilter_start_frame()).

if the filters are seperate then this will cause 2 rescalings to be
done, one for settb and one for changing pts. This would make it
impossible to change both while minimizing rounding errors

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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