[FFmpeg-devel] [PATCH] lavfi: add fade filter

[Stefano Sabatini]

On date Monday 2011-02-21 18:06:50 +0100, Michael Niedermayer encoded:
> On Mon, Feb 21, 2011 at 03:58:17PM +0100, Stefano Sabatini wrote:
> > On date Monday 2011-02-21 14:24:52 +0100, Michael Niedermayer encoded:
> > > On Mon, Feb 21, 2011 at 12:02:57PM +0100, Stefano Sabatini wrote:
> > > > From: Brandon Mintern <bmintern at gmail.com>
> > > > 
> > > > Port fade filter from libavfilter soc repo, with minor fixes by
> > > > Stefano.
> > > > ---
> > > >  doc/filters.texi         |   33 +++++++++
> > > >  libavfilter/Makefile     |    1 +
> > > >  libavfilter/allfilters.c |    1 +
> > > >  libavfilter/vf_fade.c    |  170 ++++++++++++++++++++++++++++++++++++++++++++++
> > > >  4 files changed, 205 insertions(+), 0 deletions(-)
> > > >  create mode 100644 libavfilter/vf_fade.c
> > > 
> > > commited
> > > 
> > > ideas for future work:
> > 
> > > allow multiple fade in / out per filter
> > 
> > Not sure about what you mean here.
> 
> fade=in:10:20,fade=out:50:60
> could be supported as:
> fade=in:10:20:50:60
> 
> and
> fade=out:10:20:50:60
> to black a part out (currently not supported with individual filters easily)
> 
> and more than 2, that is N such fade in/outs in a single filter would also be
> usefull
> for example consider that someone concatenates videos from several scenes to
> make a movie. She might want to create fade out+fade in at the transitions

Uhm, so it may support a list:
fade=out=S:D;in=S:D;out=S:D;...

the list is translated to a struct array, after each iteration you
have:
factor_i+1 *= factor * factor_i;

";" is special in the filtergraph syntax, so this will require
escaping:
-vf "foo, bar, fade='...'"
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