[FFmpeg-devel] [PATCH 3/3] avfilter/vf_framerate: add SIMD functions for frame blending

[Henrik Gramner]

On Sat, Jan 13, 2018 at 10:57 PM, Marton Balint <cus at passwd.hu> wrote:
> +    .loop:
> +        movu            m0, [src1q + xq]
> +        movu            m1, [src2q + xq]
> +        punpckl%1%2     m5, m0, m2         ; 0e0f0g0h
> +        punpckh%1%2     m0, m2             ; 0a0b0c0d
> +        punpckl%1%2     m6, m1, m2         ; 0E0F0G0H
> +        punpckh%1%2     m1, m2             ; 0A0B0C0D
> +        pmull%2         m0, m3
> +        pmull%2         m5, m3
> +        pmull%2         m1, m4
> +        pmull%2         m6, m4
> +        padd%2          m0, m7
> +        padd%2          m5, m7
> +        padd%2          m0, m1
> +        padd%2          m5, m6

pmaddubsw should work here for the 8-bit case. pmaddwd might work for
the 16-bit case depending on how many bits are actually used.

> +    pinsrw    xm3, r8m, 0                   ; factor1
> +    pinsrw    xm4, r9m, 0                   ; factor2
> +    pinsrw    xm7, r10m, 0                  ; half
> +    SPLATW     m3, xm3
> +    SPLATW     m4, xm4
> +    SPLATW     m7, xm7

vpbroadcast* from memory on avx2, otherwise movd instead of pxor+pinsrw.

> +    pxor       m3, m3
> +    pxor       m4, m4
> +    pxor       m7, m7
> +    pinsrw    xm3, r8m, 0                   ; factor1
> +    pinsrw    xm4, r9m, 0                   ; factor2
> +    pinsrw    xm7, r10m, 0                  ; half
> +    XSPLATD       3
> +    XSPLATD       4
> +    XSPLATD       7

Ditto.

> +    neg word r11m                           ; shift = -shift
> +    add word r11m, 16                       ; shift += 16
> +    pxor       m2, m2
> +    pinsrw    xm2, r11m, 0                  ; 16 - shift
> +    pslld      m3, xm2
> +    pslld      m4, xm2
> +    pslld      m7, xm2

You probably want to use a temporary register instead of doing slow
load-modify-store instructions.

Doing this in SIMD might be an option as well, e.g. load data directly
into vector regs from the stack, shift, then splat.