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

[Stefano Sabatini]

On date Thursday 2010-06-17 22:33:30 +0200, Michael Niedermayer encoded:
> 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

Updated.
-- 
FFmpeg = Faithless & Fundamentalist Merciless Portable Eccentric Gargoyle