[FFmpeg-devel] [PATCH v6 2/4] avfilter/vf_framerate: if metadata lavfi.scd.mafd exists, we'll use it first

[Paul B Mahol]

On 5/15/20, lance.lmwang at gmail.com <lance.lmwang at gmail.com> wrote:
> On Fri, May 15, 2020 at 11:27:00AM +0200, Paul B Mahol wrote:
>> On 5/15/20, lance.lmwang at gmail.com <lance.lmwang at gmail.com> wrote:
>> > On Fri, May 15, 2020 at 10:27:35AM +0200, Paul B Mahol wrote:
>> >> On 5/15/20, lance.lmwang at gmail.com <lance.lmwang at gmail.com> wrote:
>> >> > On Thu, May 14, 2020 at 09:00:21PM +0200, Marton Balint wrote:
>> >> >>
>> >> >>
>> >> >> On Thu, 14 May 2020, Marton Balint wrote:
>> >> >>
>> >> >> >
>> >> >> >
>> >> >> > On Thu, 14 May 2020, Nicolas George wrote:
>> >> >> >
>> >> >> > > Marton Balint (12020-05-14):
>> >> >> > > > I am not a huge fan of this patch, mafd refers to a score
>> >> >> > > > between this
>> >> >> > frame
>> >> >> > > > and the previous frame, we cannot ensure that there were no
>> >> >> > > > additional
>> >> >> > frame
>> >> >> > > > processing between scdet and this filter which may have
>> >> >> > > > duplicated
>> >> >> > > > or
>> >> >> > > > removed frames. So I'd rather not add this feature.
>> >> >> > >
>> >> >> > > It can only happen if the user has put filters in the middle. I
>> >> >> > > move
>> >> >> > > we
>> >> >> > > trust users who insert such obscure filters to do what they want
>> >> >> > > to,
>> >> >> > > or
>> >> >> > > to fix their issues if they have some.
>> >> >> >
>> >> >> > Fine, I am not blocking this if null pointer deref issues are
>> >> >> > fixed.
>> >> >> >
>> >> >> > I think we can also assume that if the metadata exists, it will
>> >> >> > contain
>> >> >> > a valid number, so I suggest this code:
>> >> >> >
>> >> >> >         e_mafd = av_dict_get(next->metadata, "lavfi.scd.mafd",
>> >> >> > NULL,
>> >> >> > AV_DICT_MATCH_CASE);
>> >> >> >         if (e_mafd) {
>> >> >> >             mafd = strtod(e_mafd->value, NULL);
>> >> >> >         } else {
>> >> >> >             s->sad(crnt->data[0], crnt->linesize[0],
>> >> >> > next->data[0],
>> >> >> > next->linesize[0], crnt->width, crnt->height, &sad);
>> >> >> >             emms_c();
>> >> >> >             mafd = (double)sad * 100.0 / (crnt->width *
>> >> >> > crnt->height)
>> >> >> > /
>> >> >> > (1 << s->bitdepth);
>> >> >> >         }
>> >> >>
>> >> >> Why this patch was committed without a recent review???
>> >> >
>> >> > Sorry, I consider it's reviewed old patchset, but it seems it's
>> >> > incomplete.
>> >>
>> >> Also it uses scd for metadata filter name, which is bad. It should use
>> >> full filter name.
>> >
>> > Sorry, in fact I intentionally did not use the filter name. At that
>> > time, I
>> > considered
>> > that there may be different filters for scene detection, but for filters
>> > that use the metadata,
>> > the processing method should be the same. So I didn't use the filter
>> > name.
>>
>> That is really bad explanation, Different filters writting to same
>> metadata entry is invalid.
>
> Maybe my thoughts isn't complete as I assume user should choose one scene
> detect filter.
> One example is facedetect, now we have opencv facedetect, in future, we may
> add
> dnn facedetect and even more, for example, the drawbox care for the face
> detect
> result instead of which filter detect I think. That's my consideration.

facedetect is not scene change detection.


>
>
>>
>> >
>> >
>> >>
>> >> >
>> >> >>
>> >> >> Thanks,
>> >> >> Marton
>> >> >> _______________________________________________
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>> >> >> ffmpeg-devel at ffmpeg.org
>> >> >> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >> >>
>> >> >> To unsubscribe, visit link above, or email
>> >> >> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>> >> >
>> >> > --
>> >> > Thanks,
>> >> > Limin Wang
>> >> > _______________________________________________
>> >> > ffmpeg-devel mailing list
>> >> > ffmpeg-devel at ffmpeg.org
>> >> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >> >
>> >> > To unsubscribe, visit link above, or email
>> >> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>> >> _______________________________________________
>> >> ffmpeg-devel mailing list
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>> >
>> > --
>> > Thanks,
>> > Limin Wang
>> > _______________________________________________
>> > ffmpeg-devel mailing list
>> > ffmpeg-devel at ffmpeg.org
>> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> > To unsubscribe, visit link above, or email
>> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
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>
> --
> Thanks,
> Limin Wang
> _______________________________________________
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