[FFmpeg-devel] [PATCH 3/4] Add setpts filter by Victor Paesa.

[Michael Niedermayer]

On Thu, Jun 17, 2010 at 10:17:17PM +0200, V?ctor Paesa wrote:
> Hi,
> 
> On 2010-06-17, Michael Niedermayer wrote:
> > On Thu, Jun 17, 2010 at 12:48:37AM +0200, Stefano Sabatini wrote:
> >> On date Wednesday 2010-06-09 03:39:04 +0200, Michael Niedermayer encoded:
> >> > On Wed, Jun 09, 2010 at 12:17:35AM +0200, Stefano Sabatini wrote:
> >> > > ---
> >> > >  doc/libavfilter.texi     |   46 +++++++++++++++++
> >> > >  libavfilter/Makefile     |    1 +
> >> > >  libavfilter/allfilters.c |    1 +
> >> > >  libavfilter/vf_setpts.c  |  127
> >> > > ++++++++++++++++++++++++++++++++++++++++++++++
> >> > >  4 files changed, 175 insertions(+), 0 deletions(-)
> >> > >  create mode 100644 libavfilter/vf_setpts.c
> >> > >
> >> > > diff --git a/doc/libavfilter.texi b/doc/libavfilter.texi
> >> > > index 1de27d9..cf53a93 100644
> >> > > --- a/doc/libavfilter.texi
> >> > > +++ b/doc/libavfilter.texi
> >> > > @@ -237,6 +237,52 @@ ratio of the input image.
> >> > >
> >> > >  The default value of @var{width} and @var{height} is 0.
> >> > >
> >> > > + at section setpts
> >> > > +
> >> > > +Change the PTS (presentation timestamp) of the input video frames.
> >> > > +
> >> > > +Accepts in input an expression evaluated through the eval API, which
> >> > > +can contain the following constants:
> >> > > +
> >> > > + at table
> >> > > + at item PTS
> >> > > +the presentation timestamp in input
> >> > > +
> >> > > + at item PI
> >> > > +Greek PI
> >> > > +
> >> > > + at item E
> >> > > +Euler number
> >> > > +
> >> > > + at item AVTB
> >> > > +the FFmpeg Time Base
> >> > > +
> >> > > + at item N
> >> > > +the count of the input frame, starting from 0.
> >> > > +
> >> > > + at item STARTPTS
> >> > > +the PTS of the first video frame
> >> > > + at end table
> >> >
> >> > missing:
> >>
> >> > average fps
> >>
> >> computed in which interval?
> >
> > in the one available
> > a demuxer with index might even set it exactly
> >
> >
> >>
> >> > interlace flag
> >> > file position
> >>
> >> > timebase
> >>
> >> which timebase? As far as I know the timebase in the filterchain is
> >> fixed, and is AV_TIME_BASE.
> >>
> >> > guessed real minimal timebase
> >>
> >> please suggest an algorithm for computing it if you have already an
> >> idea
> >
> > Avfilterwhatever.* = AVStream.*
> >
> >
> >>
> >> > previous input pts
> >> > previous output pts
> >>
> >> I added them in a previous version, but then I didn't know how to deal
> >> with them for the first frame. I suppose they may be set to 0 or
> >> AV_NOPTS_VALUE, but then I need to understand how can I deal with
> >> them, for example in the expression: outpts=prev_outpts+XXX.
> >
> > prev= curr - 1/avg_fps
> >
> >
> >>
> >> > obviously some of these could be usefull
> 
> Would it be possible to add "duration" from AVStream too?
> More than in vf_setps, I think it would be useful in vf_fade, to make
> fade outs at the end of videos.

of course but it might not always be reliable also start_time might be
needed too

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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