[FFmpeg-devel] [PATCH] avfilter: add displace video filter

[Stefano Sabatini]

On date Wednesday 2013-10-23 14:47:29 +0000, Paul B Mahol encoded:
> On 10/23/13, Stefano Sabatini <stefasab at gmail.com> wrote:
> > On date Wednesday 2013-10-23 13:25:26 +0000, Paul B Mahol encoded:
> >> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> >> ---
> >>  doc/filters.texi          |  42 ++++++
> >>  libavfilter/Makefile      |   1 +
> >>  libavfilter/allfilters.c  |   1 +
> >>  libavfilter/vf_displace.c | 325
> >> ++++++++++++++++++++++++++++++++++++++++++++++
> >>  4 files changed, 369 insertions(+)
> >>  create mode 100644 libavfilter/vf_displace.c
> >>
> >> diff --git a/doc/filters.texi b/doc/filters.texi
> >> index 7783807..905cb5a 100644
> >> --- a/doc/filters.texi
> >> +++ b/doc/filters.texi
> >> @@ -3100,6 +3100,48 @@ delogo=x=0:y=0:w=100:h=77:band=10
> >>
> >>  @end itemize
> >>
> >> + at section displace
> >> +
> >> +Displace pixels as indicated by second and third input stream.
> >> +
> >> +It takes three input streams and output one stream, the first input is
> >> the
> >> +source and second and third input are displacement maps.
> >> +
> >
> >> +Second input specify for how much to displace pixel at x-axis, while the
> >> +third input specify for how much to displace pixel at y-axis.
> >
> > The second input specifies how much to displace pixels along the
> > x-axis, while the third input specifies how much to displace pixels
> > along the y-axis.
> >
> > Also you should describe what's the meaning of the input maps.
> 
> I think they are already described above.

No they are not, the meaning of the numeric value is not explained at
all.

> 
> >
> >> +
> >> +A description of the accepted options follows.
> >> +
> >> + at table @option
> >> + at item edge
> >> +Set displace behavior for pixels that are out of range.
> >> +
> >> +Available values are:
> >> + at table @samp
> >> + at item blank
> >> +Missing pixels are replaced by black pixels.
> >> +
> >> + at item smear
> >> +Adjacent pixels will spread out to replace missing pixels.
> >> +
> >> + at item wrap
> >> +Out of range pixels are wrapped so they point to pixels of other side.
> >> + at end table
> >> +
> >> +Default is @samp{smear}.
> >> +
> >> + at end table
> >> +
> >> + at subsection Examples
> >> +
> >> + at itemize
> >> + at item
> >> +Add ripple effect to input of video size hd720:
> >> + at example
> >> +ffmpeg -i INPUT -f lavfi -i
> >
> >> nullsrc=s=hd720,geq='r=128+50*sin(2*PI*X/800):g=128+50*sin(2*PI*X/800):b=128+50*sin(2*PI*X/800)'
> >> -f lavfi -i nullsrc=s=hd720,lutrgb=128:128:128
> >
> > -lavfi '[0][2][1]displace' OUTPUT
> >
> > [0][1][2] ?
> 
> Well, effect would then be something else, I could switch inputs if
> that is wanted...

So is this a ripple effect along the y axis? But yes do not invert
order of specified input for improved clarity.

> 
> [...]
> 
> >> +static const AVOption displace_options[] = {
> >> +    { "edge", "set edge mode", OFFSET(edge), AV_OPT_TYPE_INT,
> >> {.i64=EDGE_SMEAR}, 0, EDGE_NB-1, FLAGS, "edge" },
> >> +    {   "blank", "", 0, AV_OPT_TYPE_CONST, {.i64=EDGE_BLANK}, 0, 0,
> >> FLAGS, "edge" },
> >> +    {   "smear", "", 0, AV_OPT_TYPE_CONST, {.i64=EDGE_SMEAR}, 0, 0,
> >> FLAGS, "edge" },
> >> +    {   "wrap" , "", 0, AV_OPT_TYPE_CONST, {.i64=EDGE_WRAP},  0, 0,
> >> FLAGS, "edge" },
> >> +    { NULL }
> >> +};
> >
> > why is this unused?
> 
> I may implement this later (depending on number of bikesheds).

Drop the option if the feature is not implemented.
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