[FFmpeg-devel] [GSoC] Motion Interpolation

[Davinder Singh]

On Mon, Aug 29, 2016 at 12:20 PM Clément Bœsch <u at pkh.me> wrote:

> On Sun, Aug 28, 2016 at 11:31:10AM +0200, Paul B Mahol wrote:
> > On Sat, Aug 27, 2016 at 2:45 PM, Robert Krüger <krueger at lesspain.software
> >
> > wrote:
> > >
> > > what is the way to best contribute with test cases? I have two samples
> that
> > > I use for testing, so far the results look very, very promising but
> there
> > > are still a few artefact problems, so these could maybe serve as a good
> > > test case. In some cases the artefacts almost certainly look like
> there is
> > > a bug in motion vector calculation as a very large area suddenly
> begins to
> > > move in which really only a small part is/should be moving.
> > >
> > > How do I make this available to you or other devs at this stage? Just
> trac
> > > tickets or is it too early for that and you would like to work on this
> > > differently? After all it is always a grey area, when this can be
> > > considered solved, as it is a process of gradual improvements, so maybe
> > > it's not well-suited for a ticket.
> > >
> > > Let me know. Happy to contribute samples and some testing time here and
> > > there.
> >
> >
> > You can provide them either publicly or privately to any of devs
> interested.
> > I'm always interested in short samples exhibiting the problem.
>
> Using http://b.pkh.me/sfx-sky.mov and comparing:
>
>   ./ffplay -flags2 +export_mvs sfx-sky.mov -vf codecview=mv=pf
>
> with
>
>   ./ffplay sfx-sky.mov -vf mestimate,codecview=mv=pf
>
> The encoded mvs looks much more meaningful that the ones found with
> mestimate. Typically, if you're looking for a global motion of some sort,
> the "native" mvs makes much more clear that there is a mostly static area
> at the bottom and a panning one on top with its direction pretty obvious.
> With mestimate, it just looks like small noise. Any plan to improve this?
>
> --
> Clément B
>

that's probably because the mestimate doesn't use penalty term as used in
minterpolate and encoders to make the motion field smooth. mestimate just
stores the best match. it can be easily done by adding
https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/vf_minterpolate.c#L274
to
default function
https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/motion_estimation.c#L59

The reason I didn't do that yet, we've plans to make Motion Estimation API
and the cost function doesn't seem to be correct place for penalty term.