[FFmpeg-devel] [PATCH v3] lavf/vf_find_rect: add the dual input support function

[Limin Wang]

On Fri, Jun 28, 2019 at 09:49:27AM +0200, Michael Niedermayer wrote:
> On Thu, Jun 27, 2019 at 05:40:31PM +0800, lance.lmwang at gmail.com wrote:
> > From: Limin Wang <lance.lmwang at gmail.com>
> > 
> > Please using the below command for the testing:
> > ./ffmpeg -i input.ts -i ref.png -filter_complex find_rect,cover_rect=cover.jpg:mode=cover output.ts
> > 
> > I have updated the help document for the function change.
> > 
> > Reviewed-by: Moritz Barsnick <barsnick at gmx.net>
> > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > ---
> >  doc/filters.texi           |  12 +--
> >  libavfilter/version.h      |   2 +-
> >  libavfilter/vf_find_rect.c | 173 +++++++++++++++++++++++--------------
> >  3 files changed, 118 insertions(+), 69 deletions(-)
> > 
> > diff --git a/doc/filters.texi b/doc/filters.texi
> > index 2d9af46a6b..92e1dee07e 100644
> > --- a/doc/filters.texi
> > +++ b/doc/filters.texi
> > @@ -10156,12 +10156,14 @@ Set color for pixels in fixed mode. Default is @var{black}.
> >  
> >  Find a rectangular object
> >  
> > +This filter takes in two video inputs, the first input is considered
> > +the "main" source and is passed unchanged to the output. The "second"
> > +input is used as a rectangular object for finding. Now the "second"
> > +input will be auto converted to gray8 format.
> > +
> >  It accepts the following options:
> >  
> >  @table @option
> > - at item object
> > -Filepath of the object image, needs to be in gray8.
> > -
> >  @item threshold
> >  Detection threshold, default is 0.5.
> >  
> > @@ -10178,7 +10180,7 @@ Specifies the rectangle in which to search.
> >  @item
> >  Cover a rectangular object by the supplied image of a given video using @command{ffmpeg}:
> >  @example
> > -ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
> > +ffmpeg -i file.ts -i newref.pgm -filter_complex find_rect,cover_rect=cover.jpg:mode=cover new.mkv
> 
> It will be needed to support the old syntax until the next 2 major API bumps
> at minimum.
I haven't find a good way to support the old the syntax. With the dual
input, the input has been configured with two input(main and
find_object), so it'll report error if with old syntax.

Or how about to create a new video filter like find_logo and keep the find_rect
filter untouch as I plan to improve it for logo detection. 

> That is first it would need to be deprecated and then we need 2 major API bumps
> before it can be removed.
> Keep in mind users both of the command line tools as well as the API would
> need to have their scripts / software updated/changed for this.
> also to make the transition easy both variants should be supported at the
> samw time so people can switch to the new syntax "immedeatly" and do not
> need to time it with a specific version bump
> Yes i know thats a bit annoying ...
> 
> Theres of course no need to support newly added features with the old syntax
> 
> thanks
> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> If a bugfix only changes things apparently unrelated to the bug with no
> further explanation, that is a good sign that the bugfix is wrong.



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