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[FFmpeg-devel,2/2] swscale/aarch64: add vscale specializations

Message ID fb9f751291d84d36bc66b0c65028e741@EX13D07UWB004.ant.amazon.com
State Superseded
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Series [FFmpeg-devel,1/2] swscale/aarch64: add hscale specializations | expand

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Commit Message

Swinney, Jonathan April 15, 2022, 9:37 p.m. UTC
This commit adds new code paths for vscale when filterSize is 2, 4, or 8. By
using specialized code with unrolling to match the filterSize we can improve
performance.

| (seconds)   | c6g   |       |       |
| ------------| ----- | ----- | ----- |
| filterSize  | 2     | 4     | 8     |
| original    | 0.581 | 0.974 | 1.744 |
| optimized   | 0.399 | 0.569 | 1.052 |
| improvement | 31.1% | 41.6% | 39.7% |

Signed-off-by: Jonathan Swinney <jswinney@amazon.com>
---
 libswscale/aarch64/output.S  | 147 +++++++++++++++++++++++++++++++++--
 libswscale/aarch64/swscale.c |  12 +++
 2 files changed, 153 insertions(+), 6 deletions(-)

Comments

Martin Storsjö April 16, 2022, 9:32 p.m. UTC | #1
On Fri, 15 Apr 2022, Swinney, Jonathan wrote:

> This commit adds new code paths for vscale when filterSize is 2, 4, or 8. By
> using specialized code with unrolling to match the filterSize we can improve
> performance.
>
> | (seconds)   | c6g   |       |       |
> | ------------| ----- | ----- | ----- |
> | filterSize  | 2     | 4     | 8     |
> | original    | 0.581 | 0.974 | 1.744 |
> | optimized   | 0.399 | 0.569 | 1.052 |
> | improvement | 31.1% | 41.6% | 39.7% |
>
> Signed-off-by: Jonathan Swinney <jswinney@amazon.com>
> ---
> libswscale/aarch64/output.S  | 147 +++++++++++++++++++++++++++++++++--
> libswscale/aarch64/swscale.c |  12 +++
> 2 files changed, 153 insertions(+), 6 deletions(-)

I'll have a closer look at the assembly itself at a later time, but first:

The checkasm tests in tests/checkasm/sw_scale.c does test yuv2planeX, but 
there's no testing of yuv2plane1, can you extend it to cover that too? And 
that existing test only tests filter sizes 1, 4, 8, 16, but apparently 
should be extended to test size 2 too?

// Martin
Martin Storsjö April 19, 2022, 9:12 p.m. UTC | #2
On Fri, 15 Apr 2022, Swinney, Jonathan wrote:

> This commit adds new code paths for vscale when filterSize is 2, 4, or 8. By
> using specialized code with unrolling to match the filterSize we can improve
> performance.
>
> | (seconds)   | c6g   |       |       |
> | ------------| ----- | ----- | ----- |
> | filterSize  | 2     | 4     | 8     |
> | original    | 0.581 | 0.974 | 1.744 |
> | optimized   | 0.399 | 0.569 | 1.052 |
> | improvement | 31.1% | 41.6% | 39.7% |
>
> Signed-off-by: Jonathan Swinney <jswinney@amazon.com>
> ---
> libswscale/aarch64/output.S  | 147 +++++++++++++++++++++++++++++++++--
> libswscale/aarch64/swscale.c |  12 +++
> 2 files changed, 153 insertions(+), 6 deletions(-)
>
> diff --git a/libswscale/aarch64/output.S b/libswscale/aarch64/output.S
> index af71de6050..9c99c3bea9 100644
> --- a/libswscale/aarch64/output.S
> +++ b/libswscale/aarch64/output.S
> @@ -21,12 +21,27 @@
> #include "libavutil/aarch64/asm.S"
>
> function ff_yuv2planeX_8_neon, export=1
> +// x0 - const int16_t *filter,
> +// x1 - int filterSize,
> +// x2 - const int16_t **src,
> +// x3 - uint8_t *dest,
> +// x4 - int dstW,
> +// x5 - const uint8_t *dither,
> +// x6 - int offset
> +
>         ld1                 {v0.8B}, [x5]                   // load 8x8-bit dither
>         cbz                 w6, 1f                          // check if offsetting present
>         ext                 v0.8B, v0.8B, v0.8B, #3         // honor offsetting which can be 0 or 3 only
> 1:      uxtl                v0.8H, v0.8B                    // extend dither to 16-bit
>         ushll               v1.4S, v0.4H, #12               // extend dither to 32-bit with left shift by 12 (part 1)
>         ushll2              v2.4S, v0.8H, #12               // extend dither to 32-bit with left shift by 12 (part 2)
> +        cmp                 w1, #8                          // if filterSize == 8, branch to specialized version
> +        b.eq                5f
> +        cmp                 w1, #4                          // if filterSize == 4, branch to specialized version
> +        b.eq                7f
> +        cmp                 w1, #2                          // if filterSize == 2, branch to specialized version
> +        b.eq                9f
> +
>         mov                 x7, #0                          // i = 0
> 2:      mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
>         mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
> @@ -34,16 +49,15 @@ function ff_yuv2planeX_8_neon, export=1
>         mov                 x9, x2                          // srcp    = src
>         mov                 x10, x0                         // filterp = filter
> 3:      ldp                 x11, x12, [x9], #16             // get 2 pointers: src[j] and src[j+1]
> +        ld2r                {v16.8H, v17.8H}, [x10], #4     // read 2x16-bit coeff X and Y at filter[j] and filter[j+1]
>         add                 x11, x11, x7, lsl #1            // &src[j  ][i]
>         add                 x12, x12, x7, lsl #1            // &src[j+1][i]
>         ld1                 {v5.8H}, [x11]                  // read 8x16-bit @ src[j  ][i + {0..7}]: A,B,C,D,E,F,G,H
>         ld1                 {v6.8H}, [x12]                  // read 8x16-bit @ src[j+1][i + {0..7}]: I,J,K,L,M,N,O,P
> -        ld1r                {v7.8H}, [x10], #2              // read 1x16-bit coeff X at filter[j  ] and duplicate across lanes
> -        ld1r                {v16.8H}, [x10], #2             // read 1x16-bit coeff Y at filter[j+1] and duplicate across lanes
> -        smlal               v3.4S, v5.4H, v7.4H             // val0 += {A,B,C,D} * X
> -        smlal2              v4.4S, v5.8H, v7.8H             // val1 += {E,F,G,H} * X
> -        smlal               v3.4S, v6.4H, v16.4H            // val0 += {I,J,K,L} * Y
> -        smlal2              v4.4S, v6.8H, v16.8H            // val1 += {M,N,O,P} * Y
> +        smlal               v3.4S, v5.4H, v16.4H            // val0 += {A,B,C,D} * X
> +        smlal2              v4.4S, v5.8H, v16.8H            // val1 += {E,F,G,H} * X
> +        smlal               v3.4S, v6.4H, v17.4H            // val0 += {I,J,K,L} * Y
> +        smlal2              v4.4S, v6.8H, v17.8H            // val1 += {M,N,O,P} * Y
>         subs                w8, w8, #2                      // tmpfilterSize -= 2
>         b.gt                3b                              // loop until filterSize consumed
>
> @@ -55,4 +69,125 @@ function ff_yuv2planeX_8_neon, export=1
>         add                 x7, x7, #8                      // i += 8
>         b.gt                2b                              // loop until width consumed
>         ret
> +
> +5:      // fs=8
> +        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
> +        ldp                 x7, x9, [x2, #16]               // load 2 pointers: src[j+2] and src[j+3]
> +        ldp                 x10, x11, [x2, #32]             // load 2 pointers: src[j+4] and src[j+5]
> +        ldp                 x12, x13, [x2, #48]             // load 2 pointers: src[j+6] and src[j+7]
> +
> +        // load 8x16-bit values for filter[j], where j=0..7 and replicated across lanes
> +        ld4r                {v16.8H, v17.8H, v18.8H, v19.8H}, [x0], #8
> +        ld4r                {v20.8H, v21.8H, v22.8H, v23.8H}, [x0]

Instead of ld4r like this, would it make things better (or kept similar, 
or worse?) if this just would be a regular load, and you'd change the 
smlal instructions to take the third operand in the form of e.g. v0.h[0]? 
It'd save one instruction when loading the filter coefficients here, but 
I'm not sure if there's any other difference...

> +6:
> +        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
> +        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
> +
> +        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
> +        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
> +        ld1                 {v26.8H}, [x7], #16             // load 8x16-bit values for src[j + 2][i + {0..7}]
> +        ld1                 {v27.8H}, [x9], #16             // load 8x16-bit values for src[j + 3][i + {0..7}]
> +        ld1                 {v28.8H}, [x10], #16            // load 8x16-bit values for src[j + 4][i + {0..7}]
> +        ld1                 {v29.8H}, [x11], #16            // load 8x16-bit values for src[j + 5][i + {0..7}]
> +        ld1                 {v30.8H}, [x12], #16            // load 8x16-bit values for src[j + 6][i + {0..7}]
> +        ld1                 {v31.8H}, [x13], #16            // load 8x16-bit values for src[j + 7][i + {0..7}]
> +
> +        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
> +        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
> +        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
> +        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
> +        smlal               v3.4S, v26.4H, v18.4H           // val0 += src[2][i + {0..3}] * filter[2]
> +        smlal2              v4.4S, v26.8H, v18.8H           // val1 += src[2][i + {4..7}] * filter[2]
> +        smlal               v3.4S, v27.4H, v19.4H           // val0 += src[3][i + {0..3}] * filter[3]
> +        smlal2              v4.4S, v27.8H, v19.8H           // val1 += src[3][i + {4..7}] * filter[3]
> +        smlal               v3.4S, v28.4H, v20.4H           // val0 += src[4][i + {0..3}] * filter[4]
> +        smlal2              v4.4S, v28.8H, v20.8H           // val1 += src[4][i + {4..7}] * filter[4]
> +        smlal               v3.4S, v29.4H, v21.4H           // val0 += src[5][i + {0..3}] * filter[5]
> +        smlal2              v4.4S, v29.8H, v21.8H           // val1 += src[5][i + {4..7}] * filter[5]
> +        smlal               v3.4S, v30.4H, v22.4H           // val0 += src[6][i + {0..3}] * filter[6]
> +        smlal2              v4.4S, v30.8H, v22.8H           // val1 += src[6][i + {4..7}] * filter[6]
> +        smlal               v3.4S, v31.4H, v23.4H           // val0 += src[7][i + {0..3}] * filter[7]
> +        smlal2              v4.4S, v31.8H, v23.8H           // val1 += src[7][i + {4..7}] * filter[7]
> +
> +        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
> +        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
> +        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
> +        st1                 {v3.8b}, [x3], #8               // write to destination
> +        subs                w4, w4, #8                      // dstW -= 8
> +        b.gt                6b                              // loop until width consumed

For code like this, I'd usually prefer to move the subs instruction 
somewhere else earlier, e.g. between the uqshrn and st1 (where there's a 
stall anyway), which moves setting of the condition codes from the subs 
further away from the b.gt that uses it.

> +        ret
> +
> +7:      // fs=4
> +        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
> +        ldp                 x7, x9, [x2, #16]               // load 2 pointers: src[j+2] and src[j+3]
> +
> +        // load 4x16-bit values for filter[j], where j=0..3 and replicated across lanes
> +        ld4r                {v16.8H, v17.8H, v18.8H, v19.8H}, [x0]
> +8:
> +        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
> +        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
> +
> +        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
> +        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
> +        ld1                 {v26.8H}, [x7], #16             // load 8x16-bit values for src[j + 2][i + {0..7}]
> +        ld1                 {v27.8H}, [x9], #16             // load 8x16-bit values for src[j + 3][i + {0..7}]
> +
> +        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
> +        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
> +        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
> +        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
> +        smlal               v3.4S, v26.4H, v18.4H           // val0 += src[2][i + {0..3}] * filter[2]
> +        smlal2              v4.4S, v26.8H, v18.8H           // val1 += src[2][i + {4..7}] * filter[2]
> +        smlal               v3.4S, v27.4H, v19.4H           // val0 += src[3][i + {0..3}] * filter[3]
> +        smlal2              v4.4S, v27.8H, v19.8H           // val1 += src[3][i + {4..7}] * filter[3]
> +
> +        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
> +        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
> +        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
> +        st1                 {v3.8b}, [x3], #8               // write to destination
> +        subs                w4, w4, #8                      // dstW -= 8
> +        b.gt                8b                              // loop until width consumed
> +        ret
> +
> +9:      // fs=2
> +        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
> +
> +        // load 2x16-bit values for filter[j], where j=0..1 and replicated across lanes
> +        ld2r                {v16.8H, v17.8H}, [x0]
> +10:
> +        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
> +        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
> +
> +        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
> +        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
> +
> +        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
> +        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
> +        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
> +        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
> +
> +        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
> +        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
> +        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
> +        st1                 {v3.8b}, [x3], #8               // write to destination
> +        subs                w4, w4, #8                      // dstW -= 8
> +        b.gt                10b                             // loop until width consumed
> +        ret
> +endfunc
> +function ff_yuv2plane1_8_neon, export=1

Nitpick: It'd be nice with an empty line before this new function

> +        ld1                 {v0.8B}, [x5]                   // load 8x8-bit dither
> +        cbz                 w6, 1f                          // check if offsetting present
> +        ext                 v0.8B, v0.8B, v0.8B, #3         // honor offsetting which can be 0 or 3 only
> +1:      uxtl                v0.8H, v0.8B                    // extend dither to 16-bit
> +
> +
> +2:
> +        ld1                 {v5.8H}, [x0], #16              // read 8x16-bit @ src[j  ][i + {0..7}]: A,B,C,D,E,F,G,H
> +        add                 v3.8H, v0.8H, v5.8H
> +
> +        uqshrn              v3.8b, v3.8h, #7                // clip8(val>>7)
> +        st1                 {v3.8b}, [x1], #8               // write to destination
> +        subs                w2, w2, #8                      // dstW -= 8
> +        b.gt                2b                              // loop until width consumed
> +        ret
> endfunc

Same thing about placement of subs here, I'd prefer to move it up a line 
(or maybe even to directly after the ld1?).

> diff --git a/libswscale/aarch64/swscale.c b/libswscale/aarch64/swscale.c
> index 2ea4ccb3a6..0cc821bf11 100644
> --- a/libswscale/aarch64/swscale.c
> +++ b/libswscale/aarch64/swscale.c
> @@ -40,6 +40,12 @@ ALL_SCALE_FUNCS(neon);
> void ff_yuv2planeX_8_neon(const int16_t *filter, int filterSize,
>                           const int16_t **src, uint8_t *dest, int dstW,
>                           const uint8_t *dither, int offset);
> +void ff_yuv2plane1_8_neon(
> +        const int16_t *src,
> +        uint8_t *dest,
> +        int dstW,
> +        const uint8_t *dither,
> +        int offset);
>
> #define ASSIGN_SCALE_FUNC2(hscalefn, filtersize, opt) do {              \
>     if (c->srcBpc == 8 && c->dstBpc <= 14) {                            \
> @@ -56,6 +62,11 @@ void ff_yuv2planeX_8_neon(const int16_t *filter, int filterSize,
>                ASSIGN_SCALE_FUNC2(hscalefn, X8, opt);                   \
>            break;                                                       \
>   }
> +#define ASSIGN_VSCALE_FUNC(vscalefn, opt1)                              \
> +    switch(c->dstBpc){                                                  \
> +    case 8: vscalefn = ff_yuv2plane1_8_  ## opt1;  break;               \
> +    default: break;                                                     \
> +    }

Why "opt1" and not just "opt"? Please add spaces between parentheses and 
breaces.

Overall this patch looks quite straightforward without anything 
significant to add, but I'd like to have the tests extended to cover the 
new function and the existing tests extended to cover the filtersize=2 
case too.

// Martin
diff mbox series

Patch

diff --git a/libswscale/aarch64/output.S b/libswscale/aarch64/output.S
index af71de6050..9c99c3bea9 100644
--- a/libswscale/aarch64/output.S
+++ b/libswscale/aarch64/output.S
@@ -21,12 +21,27 @@ 
 #include "libavutil/aarch64/asm.S"
 
 function ff_yuv2planeX_8_neon, export=1
+// x0 - const int16_t *filter,
+// x1 - int filterSize,
+// x2 - const int16_t **src,
+// x3 - uint8_t *dest,
+// x4 - int dstW,
+// x5 - const uint8_t *dither,
+// x6 - int offset
+
         ld1                 {v0.8B}, [x5]                   // load 8x8-bit dither
         cbz                 w6, 1f                          // check if offsetting present
         ext                 v0.8B, v0.8B, v0.8B, #3         // honor offsetting which can be 0 or 3 only
 1:      uxtl                v0.8H, v0.8B                    // extend dither to 16-bit
         ushll               v1.4S, v0.4H, #12               // extend dither to 32-bit with left shift by 12 (part 1)
         ushll2              v2.4S, v0.8H, #12               // extend dither to 32-bit with left shift by 12 (part 2)
+        cmp                 w1, #8                          // if filterSize == 8, branch to specialized version
+        b.eq                5f
+        cmp                 w1, #4                          // if filterSize == 4, branch to specialized version
+        b.eq                7f
+        cmp                 w1, #2                          // if filterSize == 2, branch to specialized version
+        b.eq                9f
+
         mov                 x7, #0                          // i = 0
 2:      mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
         mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
@@ -34,16 +49,15 @@  function ff_yuv2planeX_8_neon, export=1
         mov                 x9, x2                          // srcp    = src
         mov                 x10, x0                         // filterp = filter
 3:      ldp                 x11, x12, [x9], #16             // get 2 pointers: src[j] and src[j+1]
+        ld2r                {v16.8H, v17.8H}, [x10], #4     // read 2x16-bit coeff X and Y at filter[j] and filter[j+1]
         add                 x11, x11, x7, lsl #1            // &src[j  ][i]
         add                 x12, x12, x7, lsl #1            // &src[j+1][i]
         ld1                 {v5.8H}, [x11]                  // read 8x16-bit @ src[j  ][i + {0..7}]: A,B,C,D,E,F,G,H
         ld1                 {v6.8H}, [x12]                  // read 8x16-bit @ src[j+1][i + {0..7}]: I,J,K,L,M,N,O,P
-        ld1r                {v7.8H}, [x10], #2              // read 1x16-bit coeff X at filter[j  ] and duplicate across lanes
-        ld1r                {v16.8H}, [x10], #2             // read 1x16-bit coeff Y at filter[j+1] and duplicate across lanes
-        smlal               v3.4S, v5.4H, v7.4H             // val0 += {A,B,C,D} * X
-        smlal2              v4.4S, v5.8H, v7.8H             // val1 += {E,F,G,H} * X
-        smlal               v3.4S, v6.4H, v16.4H            // val0 += {I,J,K,L} * Y
-        smlal2              v4.4S, v6.8H, v16.8H            // val1 += {M,N,O,P} * Y
+        smlal               v3.4S, v5.4H, v16.4H            // val0 += {A,B,C,D} * X
+        smlal2              v4.4S, v5.8H, v16.8H            // val1 += {E,F,G,H} * X
+        smlal               v3.4S, v6.4H, v17.4H            // val0 += {I,J,K,L} * Y
+        smlal2              v4.4S, v6.8H, v17.8H            // val1 += {M,N,O,P} * Y
         subs                w8, w8, #2                      // tmpfilterSize -= 2
         b.gt                3b                              // loop until filterSize consumed
 
@@ -55,4 +69,125 @@  function ff_yuv2planeX_8_neon, export=1
         add                 x7, x7, #8                      // i += 8
         b.gt                2b                              // loop until width consumed
         ret
+
+5:      // fs=8
+        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
+        ldp                 x7, x9, [x2, #16]               // load 2 pointers: src[j+2] and src[j+3]
+        ldp                 x10, x11, [x2, #32]             // load 2 pointers: src[j+4] and src[j+5]
+        ldp                 x12, x13, [x2, #48]             // load 2 pointers: src[j+6] and src[j+7]
+
+        // load 8x16-bit values for filter[j], where j=0..7 and replicated across lanes
+        ld4r                {v16.8H, v17.8H, v18.8H, v19.8H}, [x0], #8
+        ld4r                {v20.8H, v21.8H, v22.8H, v23.8H}, [x0]
+6:
+        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
+        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
+
+        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
+        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
+        ld1                 {v26.8H}, [x7], #16             // load 8x16-bit values for src[j + 2][i + {0..7}]
+        ld1                 {v27.8H}, [x9], #16             // load 8x16-bit values for src[j + 3][i + {0..7}]
+        ld1                 {v28.8H}, [x10], #16            // load 8x16-bit values for src[j + 4][i + {0..7}]
+        ld1                 {v29.8H}, [x11], #16            // load 8x16-bit values for src[j + 5][i + {0..7}]
+        ld1                 {v30.8H}, [x12], #16            // load 8x16-bit values for src[j + 6][i + {0..7}]
+        ld1                 {v31.8H}, [x13], #16            // load 8x16-bit values for src[j + 7][i + {0..7}]
+
+        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
+        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
+        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
+        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
+        smlal               v3.4S, v26.4H, v18.4H           // val0 += src[2][i + {0..3}] * filter[2]
+        smlal2              v4.4S, v26.8H, v18.8H           // val1 += src[2][i + {4..7}] * filter[2]
+        smlal               v3.4S, v27.4H, v19.4H           // val0 += src[3][i + {0..3}] * filter[3]
+        smlal2              v4.4S, v27.8H, v19.8H           // val1 += src[3][i + {4..7}] * filter[3]
+        smlal               v3.4S, v28.4H, v20.4H           // val0 += src[4][i + {0..3}] * filter[4]
+        smlal2              v4.4S, v28.8H, v20.8H           // val1 += src[4][i + {4..7}] * filter[4]
+        smlal               v3.4S, v29.4H, v21.4H           // val0 += src[5][i + {0..3}] * filter[5]
+        smlal2              v4.4S, v29.8H, v21.8H           // val1 += src[5][i + {4..7}] * filter[5]
+        smlal               v3.4S, v30.4H, v22.4H           // val0 += src[6][i + {0..3}] * filter[6]
+        smlal2              v4.4S, v30.8H, v22.8H           // val1 += src[6][i + {4..7}] * filter[6]
+        smlal               v3.4S, v31.4H, v23.4H           // val0 += src[7][i + {0..3}] * filter[7]
+        smlal2              v4.4S, v31.8H, v23.8H           // val1 += src[7][i + {4..7}] * filter[7]
+
+        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
+        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
+        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
+        st1                 {v3.8b}, [x3], #8               // write to destination
+        subs                w4, w4, #8                      // dstW -= 8
+        b.gt                6b                              // loop until width consumed
+        ret
+
+7:      // fs=4
+        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
+        ldp                 x7, x9, [x2, #16]               // load 2 pointers: src[j+2] and src[j+3]
+
+        // load 4x16-bit values for filter[j], where j=0..3 and replicated across lanes
+        ld4r                {v16.8H, v17.8H, v18.8H, v19.8H}, [x0]
+8:
+        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
+        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
+
+        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
+        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
+        ld1                 {v26.8H}, [x7], #16             // load 8x16-bit values for src[j + 2][i + {0..7}]
+        ld1                 {v27.8H}, [x9], #16             // load 8x16-bit values for src[j + 3][i + {0..7}]
+
+        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
+        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
+        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
+        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
+        smlal               v3.4S, v26.4H, v18.4H           // val0 += src[2][i + {0..3}] * filter[2]
+        smlal2              v4.4S, v26.8H, v18.8H           // val1 += src[2][i + {4..7}] * filter[2]
+        smlal               v3.4S, v27.4H, v19.4H           // val0 += src[3][i + {0..3}] * filter[3]
+        smlal2              v4.4S, v27.8H, v19.8H           // val1 += src[3][i + {4..7}] * filter[3]
+
+        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
+        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
+        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
+        st1                 {v3.8b}, [x3], #8               // write to destination
+        subs                w4, w4, #8                      // dstW -= 8
+        b.gt                8b                              // loop until width consumed
+        ret
+
+9:      // fs=2
+        ldp                 x5, x6, [x2]                    // load 2 pointers: src[j  ] and src[j+1]
+
+        // load 2x16-bit values for filter[j], where j=0..1 and replicated across lanes
+        ld2r                {v16.8H, v17.8H}, [x0]
+10:
+        mov                 v3.16B, v1.16B                  // initialize accumulator part 1 with dithering value
+        mov                 v4.16B, v2.16B                  // initialize accumulator part 2 with dithering value
+
+        ld1                 {v24.8H}, [x5], #16             // load 8x16-bit values for src[j + 0][i + {0..7}]
+        ld1                 {v25.8H}, [x6], #16             // load 8x16-bit values for src[j + 1][i + {0..7}]
+
+        smlal               v3.4S, v24.4H, v16.4H           // val0 += src[0][i + {0..3}] * filter[0]
+        smlal2              v4.4S, v24.8H, v16.8H           // val1 += src[0][i + {4..7}] * filter[0]
+        smlal               v3.4S, v25.4H, v17.4H           // val0 += src[1][i + {0..3}] * filter[1]
+        smlal2              v4.4S, v25.8H, v17.8H           // val1 += src[1][i + {4..7}] * filter[1]
+
+        sqshrun             v3.4h, v3.4s, #16               // clip16(val0>>16)
+        sqshrun2            v3.8h, v4.4s, #16               // clip16(val1>>16)
+        uqshrn              v3.8b, v3.8h, #3                // clip8(val>>19)
+        st1                 {v3.8b}, [x3], #8               // write to destination
+        subs                w4, w4, #8                      // dstW -= 8
+        b.gt                10b                             // loop until width consumed
+        ret
+endfunc
+function ff_yuv2plane1_8_neon, export=1
+        ld1                 {v0.8B}, [x5]                   // load 8x8-bit dither
+        cbz                 w6, 1f                          // check if offsetting present
+        ext                 v0.8B, v0.8B, v0.8B, #3         // honor offsetting which can be 0 or 3 only
+1:      uxtl                v0.8H, v0.8B                    // extend dither to 16-bit
+
+
+2:
+        ld1                 {v5.8H}, [x0], #16              // read 8x16-bit @ src[j  ][i + {0..7}]: A,B,C,D,E,F,G,H
+        add                 v3.8H, v0.8H, v5.8H
+
+        uqshrn              v3.8b, v3.8h, #7                // clip8(val>>7)
+        st1                 {v3.8b}, [x1], #8               // write to destination
+        subs                w2, w2, #8                      // dstW -= 8
+        b.gt                2b                              // loop until width consumed
+        ret
 endfunc
diff --git a/libswscale/aarch64/swscale.c b/libswscale/aarch64/swscale.c
index 2ea4ccb3a6..0cc821bf11 100644
--- a/libswscale/aarch64/swscale.c
+++ b/libswscale/aarch64/swscale.c
@@ -40,6 +40,12 @@  ALL_SCALE_FUNCS(neon);
 void ff_yuv2planeX_8_neon(const int16_t *filter, int filterSize,
                           const int16_t **src, uint8_t *dest, int dstW,
                           const uint8_t *dither, int offset);
+void ff_yuv2plane1_8_neon(
+        const int16_t *src,
+        uint8_t *dest,
+        int dstW,
+        const uint8_t *dither,
+        int offset);
 
 #define ASSIGN_SCALE_FUNC2(hscalefn, filtersize, opt) do {              \
     if (c->srcBpc == 8 && c->dstBpc <= 14) {                            \
@@ -56,6 +62,11 @@  void ff_yuv2planeX_8_neon(const int16_t *filter, int filterSize,
                ASSIGN_SCALE_FUNC2(hscalefn, X8, opt);                   \
            break;                                                       \
   }
+#define ASSIGN_VSCALE_FUNC(vscalefn, opt1)                              \
+    switch(c->dstBpc){                                                  \
+    case 8: vscalefn = ff_yuv2plane1_8_  ## opt1;  break;               \
+    default: break;                                                     \
+    }
 
 av_cold void ff_sws_init_swscale_aarch64(SwsContext *c)
 {
@@ -64,6 +75,7 @@  av_cold void ff_sws_init_swscale_aarch64(SwsContext *c)
     if (have_neon(cpu_flags)) {
         ASSIGN_SCALE_FUNC(c->hyScale, c->hLumFilterSize, neon);
         ASSIGN_SCALE_FUNC(c->hcScale, c->hChrFilterSize, neon);
+        ASSIGN_VSCALE_FUNC(c->yuv2plane1, neon);
         if (c->dstBpc == 8) {
             c->yuv2planeX = ff_yuv2planeX_8_neon;
         }