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

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

On Sat, Jan 15, 2022 at 9:25 AM Paul B Mahol <onemda@gmail.com> wrote:

>
>
> 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.
>
> Also why filter description only shows SI part and TI part is missing?


>
>> -Thilo
>>
>>
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>
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