[FFmpeg-devel] [PATCH] add phqm filter and img_hash

[Christopher Kennedy]

On Sat, Oct 26, 2019 at 9:15 AM Paul B Mahol <onemda at gmail.com> wrote:
>
> On 10/26/19, Christopher Kennedy <ckennedy at ellation.com> wrote:
> > On Sat, Oct 26, 2019 at 8:22 AM Paul B Mahol <onemda at gmail.com> wrote:
> >>
> >> On 10/26/19, Christopher Kennedy <ckennedy at ellation.com> wrote:
> >> > This is a reference/encode comparison filter with two files input like
> >> > the psnr or vmaf filter.
> >> > So it is completely different and uses the C++ OpenCV API since this
> >> > img_hash library is not in the C API.
> >> > It's unique to what the OCV filter does, and has more research
> >> > implications from my talk at Demuxed 2019.
> >>
> >> I do not see how that is relevant.
> >>
> >> There should be generic opencv filter which could do this above in
> >> generic way, and not by adding yet another filter that uses only some
> >> part of opencv.
> >
> > Is it really possible to do framesync() operations like dual input filters
> > like psnr/vmaf and also handle input/output rendering of the frames too?
> > This sounds odd to me but I would love to understand how this is possible.
>
> framesync is nothing special, its just used a lot, there are video
> filters that do not use it and still operate on multiple inputs.
>
> >
> > The C OpenCV API is not recommended so this does the OpenCV part
> > in C++ which allows it to be fully utilized and supported. So that seems
> > better to me than using the API OpenCV won't really support and doesn't
> > allow usage of img_hash (it is NOT in the C API of OpenCV, impossible to
> > use).
> >
> > The OpenCV C++ img_hash library is the fastest implementation and does
> > work best in OpenCV. So implementing this in C directly isn't a task I
> > believe
> > is good to do.
>
> I do not care how generic opencv filter is done, it can be C++ just fine.
>
> >
> > So should the current OpenCV stuff be merged into this filter, is that
> > possible?
>
> Current opencv stuff in libavfilter is pretty dead and not maintained at all.
> So I'm not really fond of adding yet another opencv filter that not
> gonna be maintained.

Well I would maintain it, but maybe I should instead run a Fork of FFmpeg with
C++ and OpenCV properly done.

Yes the current OCV stuff is dead and not supported by OpenCV or maintained
it sounds like.

So if we can't put C++ into FFmpeg (yet we already have with decklink filters,
so that is unfair to say).

And we can't switch to use OpenCV C++ yet the C API is dead and not supported.

The only solution I see is to run a fork which is sad to have to do.

This just seems really unreasonable overall :(.

Thanks,
Christopher.


>
> > If so, then your saying the PSNR filter could also alter frames and output
> > them
> > too from the reference/encode or one or the other? I need to understand
> > this
> > better, I want to make it right so am listening.
>
> I'm not sure what you really want. Native psnr filter does not alter video,
> it just takes two inputs and output first one unmodified and reports
> via log and metadata psnr values it measured.
>
> Also, I'm of opinion that hashing images is so trivial operation that
> could be done native to libavfilter.
>
> >
> > Thanks
> > Christopher
> >
> >>
> >> >
> >> > Christopher
> >> >
> >> > On Sat, Oct 26, 2019 at 7:38 AM Paul B Mahol <onemda at gmail.com> wrote:
> >> >>
> >> >> Why is this not generic filter like already existing opencv filter?
> >> >>
> >> >> On 10/26/19, ckennedy at ellation.com <ckennedy at ellation.com> wrote:
> >> >> > From: Christopher Kennedy <ckennedy at ellation.com>
> >> >> >
> >> >> > this adds a phqm filter and OpenCV img_hash based resource usable
> >> >> > by the phqm and future filters using image hash functionality
> >> >> > from OpenCV.
> >> >> >
> >> >> > C++ to C handling so that full OpenCV functionality and API can
> >> >> > be used instead of the C versions (which are incomplete and
> >> >> > don't always exist).
> >> >> >
> >> >> > Example command line:
> >> >> >
> >> >> > ffmpeg -i encode.mp4 -i reference.mp4 \
> >> >> >            -filter_complex "[0:v][1:v]phqm=stats_file=out.log" \
> >> >> >            -y -f null /dev/null
> >> >> >
> >> >> > Signed-off-by: Christopher Kennedy <ckennedy at ellation.com>
> >> >> >
> >> >> > _______________________________________________
> >> >> > ffmpeg-devel mailing list
> >> >> > ffmpeg-devel at ffmpeg.org
> >> >> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >> >> >
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> >> >
> >