Re: [FFmpeg-devel] [PATCH v2 3/3] avfilter/vf_colordetect: add x86 SIMD implementation

[James Almer <jamrial@gmail.com>]

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On 7/16/2025 1:24 PM, Niklas Haas wrote:
> +cglobal detect_alpha%1_%3, 6, 7, 6, color, color_stride, alpha, alpha_stride, width, height, x
> +    pxor m0, m0
> +    add colorq, widthq
> +    add alphaq, widthq
> +    neg widthq
> +%ifidn %3, limited
> +%if ARCH_X86_64
> +    movq xm3, r6mp ; p
> +    movq xm4, r7mp ; q
> +    movq xm5, r8mp ; k

They are int arguments, so no point using movq.

> +%else
> +    movd xm3, r6mp ; p
> +    movd xm4, r7mp ; q
> +    movd xm5, r8mp ; k
> +%endif
> +    vpbroadcast%2 m3, xm3
> +    vpbroadcast%2 m4, xm4
> +    vpbroadcast%2 m5, xm5
> +%endif
> +.lineloop:
> +    mov xq, widthq
> +    .loop:
> +    %ifidn %3, full
> +        movu m1, [colorq + xq]
> +        movu m2, [alphaq + xq]
> +        pmaxu%1 m1, m2
> +    %else
> +        pmovzx%1%2 m1, [colorq + xq]
> +        pmovzx%1%2 m2, [alphaq + xq]
> +        pmull%2 m1, m3
> +        pmull%2 m2, m4

pmulld is painfully slow, so try to instead use pmaddwd. It should be 
doable because the input are words.


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