[FFmpeg-devel] [PATCH v2] avcodec/aarch64/vvc: Optimize vvc_avg{8, 10, 12}

Martin Storsjö martin at martin.st
Fri Mar 7 15:56:21 EET 2025


On Mon, 3 Mar 2025, Krzysztof Pyrkosz via ffmpeg-devel wrote:

> This patch replaces integer widening with halving addition, and
> multi-step "emulated" rounding shift with a single asm instruction doing
> exactly that.
>
> Benchmarks before and after:
> A78
> avg_8_64x64_neon:                                     2686.2 ( 6.12x)
> avg_8_128x128_neon:                                  10734.2 ( 5.88x)
> avg_10_64x64_neon:                                    2536.8 ( 5.40x)
> avg_10_128x128_neon:                                 10079.0 ( 5.22x)
> avg_12_64x64_neon:                                    2548.2 ( 5.38x)
> avg_12_128x128_neon:                                 10133.8 ( 5.19x)
>
> avg_8_64x64_neon:                                      897.8 (18.26x)
> avg_8_128x128_neon:                                   3608.5 (17.37x)
> avg_10_32x32_neon:                                     444.2 ( 8.51x)
> avg_10_64x64_neon:                                    1711.8 ( 8.00x)
> avg_12_64x64_neon:                                    1706.2 ( 8.02x)
> avg_12_128x128_neon:                                  7010.0 ( 7.46x)
>
> A72
> avg_8_64x64_neon:                                     5823.4 ( 3.88x)
> avg_8_128x128_neon:                                  17430.5 ( 4.73x)
> avg_10_64x64_neon:                                    5228.1 ( 3.71x)
> avg_10_128x128_neon:                                 16722.2 ( 4.17x)
> avg_12_64x64_neon:                                    5379.1 ( 3.51x)
> avg_12_128x128_neon:                                 16715.7 ( 4.17x)
>
> avg_8_64x64_neon:                                     2006.5 (10.61x)
> avg_8_128x128_neon:                                   9158.7 ( 8.96x)
> avg_10_64x64_neon:                                    3357.7 ( 5.60x)
> avg_10_128x128_neon:                                 12411.7 ( 5.56x)
> avg_12_64x64_neon:                                    3317.5 ( 5.67x)
> avg_12_128x128_neon:                                 12358.5 ( 5.58x)
>
> A53
> avg_8_64x64_neon:                                     8327.8 ( 5.18x)
> avg_8_128x128_neon:                                  31631.3 ( 5.34x)
> avg_10_64x64_neon:                                    8783.5 ( 4.98x)
> avg_10_128x128_neon:                                 32617.0 ( 5.25x)
> avg_12_64x64_neon:                                    8686.0 ( 5.06x)
> avg_12_128x128_neon:                                 32487.5 ( 5.25x)
>
> avg_8_64x64_neon:                                     6032.3 ( 7.17x)
> avg_8_128x128_neon:                                  22008.5 ( 7.69x)
> avg_10_64x64_neon:                                    7738.0 ( 5.68x)
> avg_10_128x128_neon:                                 27813.8 ( 6.14x)
> avg_12_64x64_neon:                                    7844.5 ( 5.60x)
> avg_12_128x128_neon:                                 26999.5 ( 6.34x)
> ---
> libavcodec/aarch64/vvc/inter.S | 177 ++++++++++++++++++++++++---------
> 1 file changed, 130 insertions(+), 47 deletions(-)
>
> diff --git a/libavcodec/aarch64/vvc/inter.S b/libavcodec/aarch64/vvc/inter.S
> index 0edc861f97..b2f44697d3 100644
> --- a/libavcodec/aarch64/vvc/inter.S
> +++ b/libavcodec/aarch64/vvc/inter.S
> @@ -24,9 +24,9 @@
> #define BDOF_BLOCK_SIZE 16
> #define BDOF_MIN_BLOCK_SIZE 4
>
> -.macro vvc_avg type, bit_depth
> +.macro vvc_avg bit_depth
>
> -.macro vvc_\type\()_\bit_depth\()_2_4 tap
> +.macro vvc_w_avg_\bit_depth\()_2_4 tap
> .if \tap == 2
>         ldr             s0, [src0]
>         ldr             s2, [src1]
> @@ -34,18 +34,11 @@
>         ldr             d0, [src0]
>         ldr             d2, [src1]
> .endif
> -
> -.ifc \type, avg
> -        saddl           v4.4s, v0.4h, v2.4h
> -        add             v4.4s, v4.4s, v16.4s
> -        sqshrun         v4.4h, v4.4s, #(15 - \bit_depth)
> -.else
>         mov             v4.16b, v16.16b
>         smlal           v4.4s, v0.4h, v19.4h
>         smlal           v4.4s, v2.4h, v20.4h
>         sqshl           v4.4s, v4.4s, v22.4s
>         sqxtun          v4.4h, v4.4s
> -.endif
>
> .if \bit_depth == 8
>         sqxtun          v4.8b, v4.8h
> @@ -68,7 +61,7 @@
>         add             dst, dst, dst_stride
> .endm
>
> -function ff_vvc_\type\()_\bit_depth\()_neon, export=1
> +function ff_vvc_w_avg_\bit_depth\()_neon, export=1
>         dst             .req x0
>         dst_stride      .req x1
>         src0            .req x2
> @@ -78,9 +71,6 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
>
>         mov             x10, #(VVC_MAX_PB_SIZE * 2)
>         cmp             width, #8
> -.ifc \type, avg
> -        movi            v16.4s, #(1 << (14 - \bit_depth))
> -.else
>         lsr             x11, x6, #32        // weight0
>         mov             w12, w6             // weight1
>         lsr             x13, x7, #32        // offset
> @@ -91,9 +81,8 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
>         dup             v20.8h, w12
>         dup             v16.4s, w13
>         dup             v22.4s, w14
> -.endif // avg
>
> - .if \bit_depth >= 10
> +.if \bit_depth >= 10
>         // clip pixel
>         mov             w6, #((1 << \bit_depth) - 1)
>         dup             v17.8h, w6
> @@ -105,25 +94,17 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
>         b.eq            4f
> 2:      // width == 2
>         subs            height, height, #1
> -        vvc_\type\()_\bit_depth\()_2_4 2
> +        vvc_w_avg_\bit_depth\()_2_4 2
>         b.ne            2b
>         b               32f
> 4:      // width == 4
>         subs            height, height, #1
> -        vvc_\type\()_\bit_depth\()_2_4 4
> +        vvc_w_avg_\bit_depth\()_2_4 4
>         b.ne            4b
>         b               32f
> 8:      // width == 8
>         ld1             {v0.8h}, [src0], x10
>         ld1             {v2.8h}, [src1], x10
> -.ifc \type, avg
> -        saddl           v4.4s, v0.4h, v2.4h
> -        saddl2          v5.4s, v0.8h, v2.8h
> -        add             v4.4s, v4.4s, v16.4s
> -        add             v5.4s, v5.4s, v16.4s
> -        sqshrun         v4.4h, v4.4s, #(15 - \bit_depth)
> -        sqshrun2        v4.8h, v5.4s, #(15 - \bit_depth)
> -.else
>         mov             v4.16b, v16.16b
>         mov             v5.16b, v16.16b
>         smlal           v4.4s, v0.4h, v19.4h
> @@ -134,7 +115,6 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
>         sqshl           v5.4s, v5.4s, v22.4s
>         sqxtun          v4.4h, v4.4s
>         sqxtun2         v4.8h, v5.4s
> -.endif
>         subs            height, height, #1
> .if \bit_depth == 8
>         sqxtun          v4.8b, v4.8h
> @@ -153,20 +133,6 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
> 17:
>         ldp             q0, q1, [x7], #32
>         ldp             q2, q3, [x8], #32
> -.ifc \type, avg
> -        saddl           v4.4s, v0.4h, v2.4h
> -        saddl2          v5.4s, v0.8h, v2.8h
> -        saddl           v6.4s, v1.4h, v3.4h
> -        saddl2          v7.4s, v1.8h, v3.8h
> -        add             v4.4s, v4.4s, v16.4s
> -        add             v5.4s, v5.4s, v16.4s
> -        add             v6.4s, v6.4s, v16.4s
> -        add             v7.4s, v7.4s, v16.4s
> -        sqshrun         v4.4h, v4.4s, #(15 - \bit_depth)
> -        sqshrun2        v4.8h, v5.4s, #(15 - \bit_depth)
> -        sqshrun         v6.4h, v6.4s, #(15 - \bit_depth)
> -        sqshrun2        v6.8h, v7.4s, #(15 - \bit_depth)
> -.else   // avg
>         mov             v4.16b, v16.16b
>         mov             v5.16b, v16.16b
>         mov             v6.16b, v16.16b
> @@ -187,7 +153,6 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
>         sqxtun          v6.4h, v6.4s
>         sqxtun2         v4.8h, v5.4s
>         sqxtun2         v6.8h, v7.4s
> -.endif  // w_avg
>         subs            w6, w6, #16
> .if \bit_depth == 8
>         sqxtun          v4.8b, v4.8h
> @@ -217,12 +182,130 @@ function ff_vvc_\type\()_\bit_depth\()_neon, export=1
> endfunc
> .endm
>
> -vvc_avg avg, 8
> -vvc_avg avg, 10
> -vvc_avg avg, 12
> -vvc_avg w_avg, 8
> -vvc_avg w_avg, 10
> -vvc_avg w_avg, 12
> +vvc_avg 8
> +vvc_avg 10
> +vvc_avg 12
> +
> +.macro vvc_avg2 bit_depth

Instead of naming this vvc_avg2, and the old one (which only produces the 
w_avg function now) vvc_avg, we could rename the old one to vvc_w_avg, and 
the new one to plain vvc_avg.

I did that change and pushed this patch now, thanks!

// Martin



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