[FFmpeg-devel] [PATCH] add signature filter for MPEG7 video signature

[Clément Bœsch]

On Mon, Mar 21, 2016 at 12:27:13AM +0100, Gerion Entrup wrote:
> On Sonntag, 20. März 2016 16:52:36 CET Clément Bœsch wrote:
> > On Sun, Mar 20, 2016 at 12:00:13PM +0100, Gerion Entrup wrote:
> > > Good day,
> > > 
> > > I attached the patch. The MPEG7 video signature is a method to calculate a
> > > fingerprint of a video and to compare two or more of this fingerprints.
> > > Most of the standard is implemented. I've done this work as part of my
> > > bachelor thesis.
> > > 
> > > The method is designed mainly for fast caculation of the fingerprint, so
> > > it is blockbased and not very robust to some geometric modification.
> > > 
> > > 
> > > Further details can be found at
> > > http://epubs.surrey.ac.uk/531590/1/MPEG-7%20Video%20Signature%20Author%27s
> > > %20Copy.pdf
> > 
> > use a @see in the code (typically in the @file section)
> Wrap the url, too?
> 

What do you mean?

> > > +Calculates the MPEG-7 Video Signature. The filter could handle more than 
> one input. In this case the matching between the inputs could be calculated. 
> The filter passthrough the first input. The output is written in XML.
> > > +
> > 
> > please wrap the text, same below
> Also wrap the commands in the example section?
> 

Not the verbatim/pre/blockcode, just the text

> > > 
> > > diff --git a/libavfilter/signature.h b/libavfilter/signature.h
> > > new file mode 100644
> > > index 0000000..6f0584b
> > > --- /dev/null
> > > +++ b/libavfilter/signature.h
> > > @@ -0,0 +1,569 @@
> > > +/*
> > > + * Copyright (c) 2016 Gerion Entrup
> > > + *
> > > + * This file is part of FFmpeg.
> > > + *
> > > + * FFmpeg is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + *
> > > + * FFmpeg is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > + * GNU General Public License for more details.
> > > + *
> > > + * You should have received a copy of the GNU General Public License
> > > along
> > > + * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
> > > + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> > > + */
> > > +
> > 
> > GPL?
> This is intended.
> 

don't forget to update the LICENSE file.

> > > +/**
> > > + * @file
> > > + * MPEG-7 video signature calculation and lookup filter
> > > + */
> > > +
> > > +#include <float.h>
> > > +#include "libavutil/opt.h"
> > > +#include "libavutil/timestamp.h"
> > > +#include "avfilter.h"
> > > +#include "internal.h"
> > > 
> > > +#include <stdbool.h>
> > 
> > please no, use ints.
> Done. For interest, why? This is not related to performance, I guess.
> I find bools a lot of more readable.
> 

first, because we don't use it anywhere else in the code, so for
consistency at least. There is also risk of incompatibility. And then you
end up using bool in various places assuming you know the size, where it
could actually be platform dependant. So typically using it with
AV_OPT_TYPE_BOOL could actually lead to invalid size writing/reading
(similar issue as with using enum instead of ints).

[...]

-- 
Clément B.
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