[FFmpeg-devel] [PATCH] aarch64/h26x: optimize sao_band_filter

Zhao Zhili quinkblack at foxmail.com
Tue Apr 15 13:01:42 EEST 2025


From: Zhao Zhili <zhilizhao at tencent.com>

int8_t[] is enough for offset_table of 8 bit streams.

On rpi5:
                             Before               After
hevc_sao_band_8_8_c:          252.3 ( 1.00x)     252.3 ( 1.00x)
hevc_sao_band_8_8_neon:        95.8 ( 2.63x)      61.0 ( 4.14x)
hevc_sao_band_16_8_c:         875.2 ( 1.00x)     864.9 ( 1.00x)
hevc_sao_band_16_8_neon:      317.5 ( 2.76x)     150.0 ( 5.76x)
hevc_sao_band_32_8_c:        3853.5 ( 1.00x)    3871.6 ( 1.00x)
hevc_sao_band_32_8_neon:     1222.3 ( 3.15x)     550.6 ( 7.03x)
hevc_sao_band_48_8_c:        8203.6 ( 1.00x)    8182.6 ( 1.00x)
hevc_sao_band_48_8_neon:     2685.7 ( 3.05x)    1185.8 ( 6.90x)
hevc_sao_band_64_8_c:       14023.0 ( 1.00x)   14038.9 ( 1.00x)
hevc_sao_band_64_8_neon:     4783.2 ( 2.93x)    2078.4 ( 6.75x)
---
 libavcodec/aarch64/h26x/dsp.h             |  4 +
 libavcodec/aarch64/h26x/sao_neon.S        | 93 ++++++++++++++---------
 libavcodec/aarch64/hevcdsp_init_aarch64.c |  4 +-
 libavcodec/aarch64/vvc/dsp_init.c         |  5 +-
 4 files changed, 65 insertions(+), 41 deletions(-)

diff --git a/libavcodec/aarch64/h26x/dsp.h b/libavcodec/aarch64/h26x/dsp.h
index 0fefb4d70f..6ea6a8d36a 100644
--- a/libavcodec/aarch64/h26x/dsp.h
+++ b/libavcodec/aarch64/h26x/dsp.h
@@ -28,6 +28,10 @@ void ff_h26x_sao_band_filter_8x8_8_neon(uint8_t *_dst, const uint8_t *_src,
                                         ptrdiff_t stride_dst, ptrdiff_t stride_src,
                                         const int16_t *sao_offset_val, int sao_left_class,
                                         int width, int height);
+void ff_h26x_sao_band_filter_16x16_8_neon(uint8_t *_dst, const uint8_t *_src,
+                                        ptrdiff_t stride_dst, ptrdiff_t stride_src,
+                                        const int16_t *sao_offset_val, int sao_left_class,
+                                        int width, int height);
 void ff_hevc_sao_edge_filter_16x16_8_neon(uint8_t *dst, const uint8_t *src, ptrdiff_t stride_dst,
                                           const int16_t *sao_offset_val, int eo, int width, int height);
 void ff_hevc_sao_edge_filter_8x8_8_neon(uint8_t *dst, const uint8_t *src, ptrdiff_t stride_dst,
diff --git a/libavcodec/aarch64/h26x/sao_neon.S b/libavcodec/aarch64/h26x/sao_neon.S
index c43820135e..60c026fe95 100644
--- a/libavcodec/aarch64/h26x/sao_neon.S
+++ b/libavcodec/aarch64/h26x/sao_neon.S
@@ -35,48 +35,67 @@
 //                      int16_t *sao_offset_val, int sao_left_class,
 //                      int width, int height)
 function ff_h26x_sao_band_filter_8x8_8_neon, export=1
-        stp             xzr, xzr, [sp, #-64]!
+        stp             xzr, xzr, [sp, #-32]!
         stp             xzr, xzr, [sp, #16]
-        stp             xzr, xzr, [sp, #32]
-        stp             xzr, xzr, [sp, #48]
         mov             w8,  #4
-0:      ldrsh           x9, [x4,  x8, lsl #1]      // sao_offset_val[k+1]
-        subs            w8,  w8,  #1
-        add             w10, w8,  w5               // k + sao_left_class
+0:
+        ldrsh           x9, [x4, x8, lsl #1]        // sao_offset_val[k+1]
+        subs            w8, w8, #1
+        add             w10, w8, w5                 // k + sao_left_class
         and             w10, w10, #0x1F
-        strh            w9, [sp, x10, lsl #1]
+        strb            w9, [sp, x10]
         bne             0b
-        add             w6,  w6,  #7
-        bic             w6,  w6,  #7
-        ld1             {v16.16b-v19.16b}, [sp], #64
-        sub             x2,  x2,  x6
-        sub             x3,  x3,  x6
-        movi            v20.8h,   #1
-1:      mov             w8,  w6                    // beginning of line
-2:      // Simple layout for accessing 16bit values
-        // with 8bit LUT.
-        //
-        //   00  01  02  03  04  05  06  07
-        // +----------------------------------->
-        // |xDE#xAD|xCA#xFE|xBE#xEF|xFE#xED|....
-        // +----------------------------------->
-        //    i-0     i-1     i-2     i-3
-        ld1             {v2.8b}, [x1], #8          // dst[x] = av_clip_pixel(src[x] + offset_table[src[x] >> shift]);
-        subs            w8, w8,  #8
-        uxtl            v0.8h,  v2.8b              // load src[x]
-        ushr            v2.8h,  v0.8h, #3          // >> BIT_DEPTH - 3
-        shl             v1.8h,  v2.8h, #1          // low (x2, accessing short)
-        add             v3.8h,  v1.8h, v20.8h      // +1 access upper short
-        sli             v1.8h,  v3.8h, #8          // shift insert index to upper byte
-        tbx             v2.16b, {v16.16b-v19.16b}, v1.16b // table
-        add             v1.8h,  v0.8h, v2.8h       // src[x] + table
-        sqxtun          v4.8b,  v1.8h              // clip + narrow
-        st1             {v4.8b}, [x0], #8          // store
-        // done 8 pixels
+        ldp             q16, q17, [sp], #32
+1:
+        ld1             {v2.8b}, [x1], x3
+        subs            w7, w7, #1
+        uxtl            v0.8h, v2.8b
+        ushr            v3.8b, v2.8b, #3          // >> BIT_DEPTH - 3
+        tbx             v3.8b, {v16.16b-v17.16b}, v3.8b
+        sxtl            v2.8h, v3.8b
+        add             v0.8h, v0.8h, v2.8h         // src[x] + table
+        sqxtun          v0.8b, v0.8h                // clip + narrow
+        st1             {v0.8b}, [x0], x2
+        bne             1b
+        ret
+endfunc
+
+function ff_h26x_sao_band_filter_16x16_8_neon, export=1
+        stp             xzr, xzr, [sp, #-32]!
+        stp             xzr, xzr, [sp, #16]
+        mov             w8,  #4
+0:
+        ldrsh           x9, [x4, x8, lsl #1]        // sao_offset_val[k+1]
+        subs            w8,  w8, #1
+        add             w10, w8, w5                 // k + sao_left_class
+        and             w10, w10, #0x1F
+        strb            w9, [sp, x10]
+        bne             0b
+        add             w6, w6, #15
+        bic             w6, w6, #15
+        ldp             q16, q17, [sp], #32
+        sub             x2, x2, x6
+        sub             x3, x3, x6
+1:
+        mov             w8, w6                      // beginning of line
+2:
+        ldr             q2, [x1], #16
+        subs            w8, w8, #16
+        uxtl            v0.8h, v2.8b
+        uxtl2           v1.8h, v2.16b
+        ushr            v3.16b, v2.16b, #3          // >> BIT_DEPTH - 3
+        tbx             v3.16b, {v16.16b-v17.16b}, v3.16b
+        sxtl            v2.8h, v3.8b
+        sxtl2           v3.8h, v3.16b
+        add             v0.8h, v0.8h, v2.8h         // src[x] + table
+        add             v1.8h, v1.8h, v3.8h
+        sqxtun          v0.8b, v0.8h                // clip + narrow
+        sqxtun2         v0.16b, v1.8h
+        str             q0, [x0], #16
         bne             2b
-        subs            w7, w7,  #1                // finished line, prep. new
-        add             x0, x0,  x2                // dst += stride_dst
-        add             x1, x1,  x3                // src += stride_src
+        subs            w7, w7, #1
+        add             x0, x0, x2                  // dst += stride_dst
+        add             x1, x1, x3                  // src += stride_src
         bne             1b
         ret
 endfunc
diff --git a/libavcodec/aarch64/hevcdsp_init_aarch64.c b/libavcodec/aarch64/hevcdsp_init_aarch64.c
index 5dd470baaa..0b159d1886 100644
--- a/libavcodec/aarch64/hevcdsp_init_aarch64.c
+++ b/libavcodec/aarch64/hevcdsp_init_aarch64.c
@@ -157,11 +157,11 @@ av_cold void ff_hevc_dsp_init_aarch64(HEVCDSPContext *c, const int bit_depth)
         c->idct_dc[2]                  = ff_hevc_idct_16x16_dc_8_neon;
         c->idct_dc[3]                  = ff_hevc_idct_32x32_dc_8_neon;
         c->transform_4x4_luma          = ff_hevc_transform_luma_4x4_neon_8;
-        c->sao_band_filter[0]          =
+        c->sao_band_filter[0]          = ff_h26x_sao_band_filter_8x8_8_neon;
         c->sao_band_filter[1]          =
         c->sao_band_filter[2]          =
         c->sao_band_filter[3]          =
-        c->sao_band_filter[4]          = ff_h26x_sao_band_filter_8x8_8_neon;
+        c->sao_band_filter[4]          = ff_h26x_sao_band_filter_16x16_8_neon;
         c->sao_edge_filter[0]          = ff_hevc_sao_edge_filter_8x8_8_neon;
         c->sao_edge_filter[1]          =
         c->sao_edge_filter[2]          =
diff --git a/libavcodec/aarch64/vvc/dsp_init.c b/libavcodec/aarch64/vvc/dsp_init.c
index 2c99ba206b..9a171234f6 100644
--- a/libavcodec/aarch64/vvc/dsp_init.c
+++ b/libavcodec/aarch64/vvc/dsp_init.c
@@ -197,8 +197,9 @@ void ff_vvc_dsp_init_aarch64(VVCDSPContext *const c, const int bd)
         c->inter.dmvr[1][1] = ff_vvc_dmvr_hv_8_neon;
         c->inter.apply_bdof = apply_bdof_8;
 
-        for (int i = 0; i < FF_ARRAY_ELEMS(c->sao.band_filter); i++)
-            c->sao.band_filter[i] = ff_h26x_sao_band_filter_8x8_8_neon;
+        c->sao.band_filter[0] = ff_h26x_sao_band_filter_8x8_8_neon;
+        for (int i = 1; i < FF_ARRAY_ELEMS(c->sao.band_filter); i++)
+            c->sao.band_filter[i] = ff_h26x_sao_band_filter_16x16_8_neon;
         c->sao.edge_filter[0] = ff_vvc_sao_edge_filter_8x8_8_neon;
         for (int i = 1; i < FF_ARRAY_ELEMS(c->sao.edge_filter); i++)
             c->sao.edge_filter[i] = ff_vvc_sao_edge_filter_16x16_8_neon;
-- 
2.46.0



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