[FFmpeg-devel] [PATCH] swscale/aarch64/output: Implement neon assembly for yuv2nv12cX_c()

Harshitha Sarangu Suresh harshitha at multicorewareinc.com
Mon Jun 2 07:36:14 EEST 2025


>From 7260822a578130a713c1455cca6cdd06f1540db8 Mon Sep 17 00:00:00 2001
From: Harshitha Suresh <harshitha at multicorewareinc.com>
Date: Mon, 19 May 2025 22:37:20 +0530
Subject: [PATCH] swscale/aarch64/output: Implement neon assembly for yuv2nv12cX_c()

yuv2nv12cX_2_512_accurate_c:                          3508.8 ( 1.00x)
yuv2nv12cX_2_512_accurate_neon:                        369.2 ( 9.50x)
yuv2nv12cX_2_512_approximate_c:                       3499.0 ( 1.00x)
yuv2nv12cX_2_512_approximate_neon:                     370.2 ( 9.45x)
yuv2nv12cX_4_512_accurate_c:                          4683.0 ( 1.00x)
yuv2nv12cX_4_512_accurate_neon:                        568.8 ( 8.23x)
yuv2nv12cX_4_512_approximate_c:                       4682.6 ( 1.00x)
yuv2nv12cX_4_512_approximate_neon:                     569.9 ( 8.22x)
yuv2nv12cX_8_512_accurate_c:                          7243.0 ( 1.00x)
yuv2nv12cX_8_512_accurate_neon:                        937.6 ( 7.72x)
yuv2nv12cX_8_512_approximate_c:                       7235.9 ( 1.00x)
yuv2nv12cX_8_512_approximate_neon:                     938.3 ( 7.71x)
yuv2nv12cX_16_512_accurate_c:                        13749.7 ( 1.00x)
yuv2nv12cX_16_512_accurate_neon:                      1708.1 ( 8.05x)
yuv2nv12cX_16_512_approximate_c:                     13750.0 ( 1.00x)
yuv2nv12cX_16_512_approximate_neon:                   1708.6 ( 8.05x)
---
 libswscale/aarch64/output.S  | 308 +++++++++++++++++++++++++++++++++++
 libswscale/aarch64/swscale.c |  18 ++
 2 files changed, 326 insertions(+)

diff --git a/libswscale/aarch64/output.S b/libswscale/aarch64/output.S
index 190c438870..8eb89e8b54 100644
--- a/libswscale/aarch64/output.S
+++ b/libswscale/aarch64/output.S
@@ -226,3 +226,311 @@ function ff_yuv2plane1_8_neon, export=1
         b.gt            2b                              // loop until width consumed
         ret
 endfunc
+
+// void ff_yuv2nv12cX_neon(enum AVPixelFormat dstFormat, const uint8_t *chrDither,
+//                         const int16_t *chrFilter, int chrFilterSize,
+//                         const int16_t **chrUSrc, const int16_t **chrVSrc,
+//                         uint8_t *dest, int chrDstW)
+
+function ff_yuv2nv12cX_notswapped_neon, export=1
+    // x0 - dstFormat (unused)
+    // x1 - uint8_t *chrDither
+    // x2 - int16_t *chrFilter
+    // x3 - int chrFilterSize
+    // x4 - int16_t **chrUSrc
+    // x5 - int16_t **chrVSrc
+    // x6 - uint8_t *dest
+    // x7 - int chrDstW
+
+    // Load dither pattern and compute U and V dither vectors
+    ld1     {v0.8b}, [x1]               // chrDither[0..7]
+    ext     v1.8b, v0.8b, v0.8b, #3      // Rotate for V: (i+3)&7
+
+    uxtl    v0.8h, v0.8b
+    uxtl    v1.8h, v1.8b
+
+    ushll    v2.4s, v0.4h, #12         // U dither low
+    ushll2   v3.4s, v0.8h, #12         // U dither high
+    ushll    v4.4s, v1.4h, #12         // V dither low
+    ushll2   v5.4s, v1.8h, #12         // V dither high
+
+    // Check if we can process 16 pixels at a time
+    tst     w7, #15                    // Check if chrDstW % 16 == 0
+    b.ne    .Lprocess_8_pixels          // If not, use 8-pixel version
+
+    // =============================================
+    // 16-pixel processing path
+    // =============================================
+    mov     x8, #0                     // i = 0
+.Lloop_16_pixels:
+
+    mov     v16.16b, v2.16b            // U acc low
+    mov     v17.16b, v3.16b            // U acc high
+    mov     v18.16b, v4.16b            // V acc low
+    mov     v19.16b, v5.16b            // V acc high
+
+    mov     v20.16b, v2.16b
+    mov     v21.16b, v3.16b
+    mov     v22.16b, v4.16b
+    mov     v23.16b, v5.16b
+
+    mov     w9, w3                      // chrFilterSize counter
+    mov     x10, x2                     // chrFilter pointer
+    mov     x11, x4                     // chrUSrc base
+    mov     x12, x5                     // chrVSrc base
+
+.Lfilter_loop_16:
+    ldr     h6, [x10], #2               // Load filter coefficient
+
+    ldr     x13, [x11], #8              // chrUSrc[j]
+    ldr     x14, [x12], #8              // chrVSrc[j]
+    add     x13, x13, x8, lsl #1        // &chrUSrc[j][i]
+    add     x14, x14, x8, lsl #1        // &chrVSrc[j][i]
+    add     x15, x13, #16               // x15 = &chrUSrc[j][i+8] (8 samples * 2 bytes)
+    add     x16, x14, #16
+
+    ld1     {v24.8h}, [x13]             // U samples 0-7
+    ld1     {v25.8h}, [x14]             // V samples 0-7
+
+    ld1     {v26.8h}, [x15]             // U samples 8-15
+    ld1     {v27.8h}, [x16]             // V samples 8-15
+
+    smlal   v16.4s, v24.4h, v6.h[0]
+    smlal2  v17.4s, v24.8h, v6.h[0]
+    smlal   v18.4s, v25.4h, v6.h[0]
+    smlal2  v19.4s, v25.8h, v6.h[0]
+
+    smlal   v20.4s, v26.4h, v6.h[0]
+    smlal2  v21.4s, v26.8h, v6.h[0]
+    smlal   v22.4s, v27.4h, v6.h[0]
+    smlal2  v23.4s, v27.8h, v6.h[0]
+
+    subs    w9, w9, #1
+    b.gt    .Lfilter_loop_16
+
+    // Process and store first 8 pixels
+    sqshrun  v28.4h, v16.4s, #16
+    sqshrun2 v28.8h, v17.4s, #16
+    sqshrun  v29.4h, v18.4s, #16
+    sqshrun2 v29.8h, v19.4s, #16
+    uqshrn   v30.8b, v28.8h, #3        // U
+    uqshrn   v31.8b, v29.8h, #3        // V
+
+    // Process and store next 8 pixels
+    sqshrun  v28.4h, v20.4s, #16
+    sqshrun2 v28.8h, v21.4s, #16
+    sqshrun  v29.4h, v22.4s, #16
+    sqshrun2 v29.8h, v23.4s, #16
+    uqshrn   v24.8b, v28.8h, #3        // U
+    uqshrn   v25.8b, v29.8h, #3        // V
+
+    // Store both 8-pixel blocks
+    st2     {v30.8b, v31.8b}, [x6], #16
+    st2     {v24.8b, v25.8b}, [x6], #16
+
+    subs    w7, w7, #16
+    add     x8, x8, #16
+    b.gt    .Lloop_16_pixels
+    ret
+
+    // =============================================
+    // 8-pixel processing path (original code)
+    // =============================================
+.Lprocess_8_pixels:
+    mov     x8, #0                     // i = 0
+.Lloop_8_pixels:
+    // Initialize accumulators with dither
+    mov     v16.16b, v2.16b            // U acc low
+    mov     v17.16b, v3.16b            // U acc high
+    mov     v18.16b, v4.16b            // V acc low
+    mov     v19.16b, v5.16b            // V acc high
+
+    mov     w9, w3                      // chrFilterSize counter
+    mov     x10, x2                     // chrFilter pointer
+    mov     x11, x4                     // chrUSrc base
+    mov     x12, x5                     // chrVSrc base
+
+.Lfilter_loop_8:
+    ldr     h6, [x10], #2               // Load filter coefficient
+
+    ldr     x13, [x11], #8              // chrUSrc[j]
+    ldr     x14, [x12], #8              // chrVSrc[j]
+    add     x13, x13, x8, lsl #1        // &chrUSrc[j][i]
+    add     x14, x14, x8, lsl #1        // &chrVSrc[j][i]
+
+    ld1     {v20.8h}, [x13]             // U samples
+    ld1     {v21.8h}, [x14]             // V samples
+
+    smlal   v16.4s, v20.4h, v6.h[0]
+    smlal2  v17.4s, v20.8h, v6.h[0]
+    smlal   v18.4s, v21.4h, v6.h[0]
+    smlal2  v19.4s, v21.8h, v6.h[0]
+
+    subs    w9, w9, #1
+    b.gt    .Lfilter_loop_8
+
+    // Final processing and store
+    sqshrun  v26.4h, v16.4s, #16
+    sqshrun2 v26.8h, v17.4s, #16
+    sqshrun  v27.4h, v18.4s, #16
+    sqshrun2 v27.8h, v19.4s, #16
+    uqshrn   v28.8b, v26.8h, #3        // U
+    uqshrn   v29.8b, v27.8h, #3        // V
+
+    st2     {v28.8b, v29.8b}, [x6], #16
+
+    subs    w7, w7, #8
+    add     x8, x8, #8
+    b.gt    .Lloop_8_pixels
+    ret
+endfunc
+
+function ff_yuv2nv12cX_swapped_neon, export=1
+    // x0 - dstFormat (unused)
+    // x1 - uint8_t *chrDither
+    // x2 - int16_t *chrFilter
+    // x3 - int chrFilterSize
+    // x4 - int16_t **chrUSrc
+    // x5 - int16_t **chrVSrc
+    // x6 - uint8_t *dest
+    // x7 - int chrDstW
+
+    ld1     {v0.8b}, [x1]               // chrDither[0..7]
+    ext     v1.8b, v0.8b, v0.8b, #3      // Rotate for V: (i+3)&7
+
+    uxtl    v0.8h, v0.8b
+    uxtl    v1.8h, v1.8b
+
+    ushll    v2.4s, v0.4h, #12         // U dither low
+    ushll2   v3.4s, v0.8h, #12         // U dither high
+    ushll    v4.4s, v1.4h, #12         // V dither low
+    ushll2   v5.4s, v1.8h, #12         // V dither high
+
+    // Check if we can process 16 pixels at a time
+    tst     w7, #15                    // Check if chrDstW % 16 == 0
+    b.ne    .Lswapped_process_8_pixels // If not, use 8-pixel version
+
+    // =============================================
+    // 16-pixel processing path
+    // =============================================
+    mov     x8, #0                     // i = 0
+.Lswapped_loop_16_pixels:
+
+    mov     v16.16b, v2.16b            // U acc low
+    mov     v17.16b, v3.16b            // U acc high
+    mov     v18.16b, v4.16b            // V acc low
+    mov     v19.16b, v5.16b            // V acc high
+
+    mov     v20.16b, v2.16b
+    mov     v21.16b, v3.16b
+    mov     v22.16b, v4.16b
+    mov     v23.16b, v5.16b
+
+    mov     w9, w3                      // chrFilterSize counter
+    mov     x10, x2                     // chrFilter pointer
+    mov     x11, x4                     // chrUSrc base
+    mov     x12, x5                     // chrVSrc base
+
+.Lswapped_filter_loop_16:
+    ldr     h6, [x10], #2               // Load filter coefficient
+
+    // Load pointers for first 8 pixels
+    ldr     x13, [x11], #8              // chrUSrc[j]
+    ldr     x14, [x12], #8              // chrVSrc[j]
+    add     x13, x13, x8, lsl #1        // &chrUSrc[j][i]
+    add     x14, x14, x8, lsl #1        // &chrVSrc[j][i]
+    add     x15, x13, #16               // x15 = &chrUSrc[j][i+8] (8 samples * 2 bytes)
+    add     x16, x14, #16
+
+    ld1     {v24.8h}, [x13]             // U samples 0-7
+    ld1     {v25.8h}, [x14]             // V samples 0-7
+
+    ld1     {v26.8h}, [x15]             // U samples 8-15
+    ld1     {v27.8h}, [x16]             // V samples 8-15
+
+    smlal   v16.4s, v24.4h, v6.h[0]
+    smlal2  v17.4s, v24.8h, v6.h[0]
+    smlal   v18.4s, v25.4h, v6.h[0]
+    smlal2  v19.4s, v25.8h, v6.h[0]
+
+    smlal   v20.4s, v26.4h, v6.h[0]
+    smlal2  v21.4s, v26.8h, v6.h[0]
+    smlal   v22.4s, v27.4h, v6.h[0]
+    smlal2  v23.4s, v27.8h, v6.h[0]
+
+    subs    w9, w9, #1
+    b.gt    .Lswapped_filter_loop_16
+
+    sqshrun  v28.4h, v16.4s, #16
+    sqshrun2 v28.8h, v17.4s, #16
+    sqshrun  v29.4h, v18.4s, #16
+    sqshrun2 v29.8h, v19.4s, #16
+    uqshrn   v30.8b, v28.8h, #3        // U
+    uqshrn   v31.8b, v29.8h, #3        // V
+
+    sqshrun  v28.4h, v20.4s, #16
+    sqshrun2 v28.8h, v21.4s, #16
+    sqshrun  v29.4h, v22.4s, #16
+    sqshrun2 v29.8h, v23.4s, #16
+    uqshrn   v24.8b, v28.8h, #3        // U
+    uqshrn   v25.8b, v29.8h, #3        // V
+
+    // Store both 8-pixel blocks
+    st2     {v30.8b, v31.8b}, [x6], #16
+    st2     {v24.8b, v25.8b}, [x6], #16
+
+    subs    w7, w7, #16
+    add     x8, x8, #16
+    b.gt    .Lswapped_loop_16_pixels
+    ret
+
+    // =============================================
+    // 8-pixel processing path
+    // =============================================
+.Lswapped_process_8_pixels:
+    mov     x8, #0                     // i = 0
+.Lswapped_loop_8_pixels:
+    // Initialize accumulators with dither
+    mov     v16.16b, v2.16b            // U acc low
+    mov     v17.16b, v3.16b            // U acc high
+    mov     v18.16b, v4.16b            // V acc low
+    mov     v19.16b, v5.16b            // V acc high
+
+    mov     w9, w3                      // chrFilterSize counter
+    mov     x10, x2                     // chrFilter pointer
+    mov     x11, x4                     // chrUSrc base
+    mov     x12, x5                     // chrVSrc base
+
+.Lswapped_filter_loop_8:
+    ldr     h6, [x10], #2               // Load filter coefficient
+
+    ldr     x13, [x11], #8              // chrUSrc[j]
+    ldr     x14, [x12], #8              // chrVSrc[j]
+    add     x13, x13, x8, lsl #1        // &chrUSrc[j][i]
+    add     x14, x14, x8, lsl #1        // &chrVSrc[j][i]
+
+    ld1     {v20.8h}, [x13]             // U samples
+    ld1     {v21.8h}, [x14]             // V samples
+
+    smlal   v16.4s, v20.4h, v6.h[0]
+    smlal2  v17.4s, v20.8h, v6.h[0]
+    smlal   v18.4s, v21.4h, v6.h[0]
+    smlal2  v19.4s, v21.8h, v6.h[0]
+
+    subs    w9, w9, #1
+    b.gt    .Lswapped_filter_loop_8
+
+    sqshrun  v26.4h, v16.4s, #16
+    sqshrun2 v26.8h, v17.4s, #16
+    sqshrun  v27.4h, v18.4s, #16
+    sqshrun2 v27.8h, v19.4s, #16
+    uqshrn   v28.8b, v26.8h, #3        // U
+    uqshrn   v29.8b, v27.8h, #3        // V
+
+    st2     {v28.8b, v29.8b}, [x6], #16
+
+    subs    w7, w7, #8
+    add     x8, x8, #8
+    b.gt    .Lswapped_loop_8_pixels
+    ret
+endfunc
diff --git a/libswscale/aarch64/swscale.c b/libswscale/aarch64/swscale.c
index 6e5a721c1f..0e57112f42 100644
--- a/libswscale/aarch64/swscale.c
+++ b/libswscale/aarch64/swscale.c
@@ -168,6 +168,16 @@ void ff_yuv2plane1_8_neon(
         const uint8_t *dither,
         int offset);

+void ff_yuv2nv12cX_notswapped_neon(enum AVPixelFormat dstFormat, const uint8_t *chrDither,
+    const int16_t *chrFilter, int chrFilterSize,
+    const int16_t **chrUSrc, const int16_t **chrVSrc,
+    uint8_t *dest, int chrDstW);
+
+void ff_yuv2nv12cX_swapped_neon(enum AVPixelFormat dstFormat, const uint8_t *chrDither,
+    const int16_t *chrFilter, int chrFilterSize,
+    const int16_t **chrUSrc, const int16_t **chrVSrc,
+    uint8_t *dest, int chrDstW);
+
 #define ASSIGN_SCALE_FUNC2(hscalefn, filtersize, opt) do {              \
     if (c->srcBpc == 8) {                                               \
         if(c->dstBpc <= 14) {                                           \
@@ -201,6 +211,12 @@ void ff_yuv2plane1_8_neon(
     default: break;                                                     \
     }

+#define ASSIGN_YUV2NV12_FUNC(yuv2nv12fn, opt, dstFormat)               \
+    if(!isSwappedChroma(dstFormat))                                    \
+        yuv2nv12fn = ff_yuv2nv12cX_notswapped_  ## opt;                \
+    else                                                               \
+        yuv2nv12fn = ff_yuv2nv12cX_swapped_  ## opt;
+
 #define NEON_INPUT(name) \
 void ff_##name##ToY_neon(uint8_t *dst, const uint8_t *src, const uint8_t *, \
                         const uint8_t *, int w, uint32_t *coeffs, void *); \
@@ -275,7 +291,9 @@ av_cold void ff_sws_init_swscale_aarch64(SwsInternal *c)
         ASSIGN_VSCALE_FUNC(c->yuv2plane1, neon);
         if (c->dstBpc == 8) {
             c->yuv2planeX = ff_yuv2planeX_8_neon;
+            ASSIGN_YUV2NV12_FUNC(c->yuv2nv12cX, neon, c->opts.dst_format);
         }
+
         switch (c->opts.src_format) {
         case AV_PIX_FMT_ABGR:
             c->lumToYV12 = ff_abgr32ToY_neon;
--
2.36.0.windows.1



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