[FFmpeg-devel] [FFmpeg-cvslog] avfilter: add vmafmotion filter

[Michael Niedermayer]

On Fri, Oct 06, 2017 at 10:03:16AM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Thu, Oct 5, 2017 at 7:52 PM, Michael Niedermayer <michael at niedermayer.cc>
> wrote:
> 
> > On Sat, Sep 30, 2017 at 03:51:41PM +0000, Ashish Singh wrote:
> > > ffmpeg | branch: master | Ashish Singh <ashk43712 at gmail.com> | Sat Sep
> > 16 02:35:58 2017 +0530| [148c8e88c43cfbabd6aee9f01ef30942cee9d359] |
> > committer: Ronald S. Bultje
> > >
> > > avfilter: add vmafmotion filter
> > >
> > > Signed-off-by: Ashish Singh <ashk43712 at gmail.com>
> > > Signed-off-by: Ronald S. Bultje <rsbultje at gmail.com>
> > >
> > > > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=
> > 148c8e88c43cfbabd6aee9f01ef30942cee9d359
> > > ---
> > >
> > >  Changelog                   |   1 +
> > >  doc/filters.texi            |  14 ++
> > >  libavfilter/Makefile        |   1 +
> > >  libavfilter/allfilters.c    |   1 +
> > >  libavfilter/vf_vmafmotion.c | 365 ++++++++++++++++++++++++++++++
> > ++++++++++++++
> > >  libavfilter/vmaf_motion.h   |  58 +++++++
> > >  6 files changed, 440 insertions(+)
> > [...]
> > > +static av_cold int init(AVFilterContext *ctx)
> > > +{
> > > +    VMAFMotionContext *s = ctx->priv;
> > > +
> > > +    if (s->stats_file_str) {
> > > +        if (!strcmp(s->stats_file_str, "-")) {
> >
> > > +            s->stats_file = stdout;
> >
> > Using stdout can interfere with the user application using the filter
> >
> >
> > > +        } else {
> >
> > > +            s->stats_file = fopen(s->stats_file_str, "w");
> >
> > Opening a filter parameter provided string for writing is a dangerous
> > way to output data. It allows one with access to the parameters to
> > overwrite any writable file
> >
> > data should only be output in a safe way
> >
> 
> The same mechanism is present in ssim/psnr filters. I'm open to any
> alternative method you suggest. These are only settable using explicit user
> interaction (and are disabled by default) so I don't particularly see the
> problem.

With this a filter graph can never be taken from an untrusted source

One filter that outputs statistics without writing to a user specified
filename is libavfilter/af_astats.c



[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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