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

[Paul B Mahol]

On 10/30/19, Christopher Kennedy <ckennedy at ellation.com> wrote:
> 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.

Who said that?
C++ module filter in libavfilter dealing with latest OpenCV and well
maintained is always welcome.

>
> 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>
>> >> >> >
>> >> >> > _______________________________________________
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>> >> >> > ffmpeg-devel at ffmpeg.org
>> >> >> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >> >> >
>> >> >> > To unsubscribe, visit link above, or email
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>> >> >
>> >
>