Re: [FFmpeg-devel] [PATCH] avfilter: Added siti filter

[Paul B Mahol <onemda@gmail.com>]

On Fri, Jan 14, 2022 at 5:22 PM Thilo Borgmann <thilo.borgmann@mail.de>
wrote:

> Hi,
>
> Am 19.01.21 um 05:49 schrieb Lynne:
> > Jan 19, 2021, 01:07 by borbarak@fb.com:
> >
> >> Calculate Spatial Info (SI) and Temporal Info (TI) scores for a video,
> as defined
> >> in ITU-T P.910: Subjective video quality assessment methods for
> multimedia
> >> applications.
> >>
> >> Update: Fixed bracket style.
> >>
> >
> > Thanks, looks much neater now.
> >
> >
> >
> >> I'm already adding the data to the frame's metadata, is the suggestion
> to remove the file option altogether?
> >>
> >
> > Yes. We want to avoid filters having their own file in/out options rather
> > than using generic ones.
>
> Updated the patch to apply to git HEAD.
> Removed file output.
> Made printing summary to console optional.
>
>
> >> +
> >> +#include "libavutil/imgutils.h"
> >> +#include "libavutil/internal.h"
> >> +#include "libavutil/opt.h"
> >> +
> >> +#include "avfilter.h"
> >> +#include "formats.h"
> >> +#include "internal.h"
> >> +#include "video.h"
> >> +
> >> +static const int X_FILTER[9] = {
> >> +    1, 0, -1,
> >> +    2, 0, -2,
> >> +    1, 0, -1
> >> +};
> >> +
> >> +static const int Y_FILTER[9] = {
> >> +    1, 2, 1,
> >> +    0, 0, 0,
> >> +    -1, -2, -1
> >> +};
> >>
> >
> > We have optimized assembly to apply 3x3 matrices. Check out
> > libavfilter/x86/vf_convolution.asm:ff_filter_3x3_sse4
> >  vf_convolution already applies a sobel filter that way. Maybe
> > look into sharing some DSP code with it?
>
> I checked a bit since I also want a common sobel for vf_edgedetect / my
> patch for vf_blurriness.
>
> For sobel, there is no direct asm implementation. We have a generic
> filter_3x3 with sse4 optimization. To use sobel with that, you'd need to
> run two times filter_3x3 plus one pass for gradient calculation.
>
> As another difference, this filter (SITI) does on-the-fly conversion to
> full-range pixel values during its sobel. While vf_edgedetect /
> vf_bluriness use an abbreviation for the gradients during its sobel. Which
> makes them both distinct enough not to fit into a general filter_3x3 or
> filter_sobel from vf_convolution easily (and more overhead). So I think
> it's not worth the effort to force them into a common function? (Especially
> since we don't have a sobel_sse4 or something)
>
> Patch without a common sobel attached.
>
>

Violations of code style.



> -Thilo
>
>
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