From: Krzysztof Pyrkosz via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
To: ffmpeg-devel@ffmpeg.org
Cc: Krzysztof Pyrkosz <ffmpeg@szaka.eu>
Subject: [FFmpeg-devel] [PATCH] swscale/aarch64/rgb24toyv12: skip early right shift by 2
Date: Tue, 11 Feb 2025 22:43:11 +0100
Message-ID: <20250211214310.116203-2-ffmpeg@szaka.eu> (raw)
It's a minor improvement that shaves off 5-8% from the execution time.
Instead of shifting by 2 right away and by 7 soon after, shift by 9 one
time.
Times before and after:
A78:
rgb24toyv12_16_200_neon: 5366.8 ( 3.62x)
rgb24toyv12_128_60_neon: 13574.0 ( 3.34x)
rgb24toyv12_512_16_neon: 14463.8 ( 3.33x)
rgb24toyv12_1920_4_neon: 13508.2 ( 3.34x)
rgb24toyv12_1920_4_negstride_neon: 13525.0 ( 3.34x)
rgb24toyv12_16_200_neon: 5293.8 ( 3.66x)
rgb24toyv12_128_60_neon: 12955.0 ( 3.50x)
rgb24toyv12_512_16_neon: 13784.0 ( 3.50x)
rgb24toyv12_1920_4_neon: 12900.8 ( 3.49x)
rgb24toyv12_1920_4_negstride_neon: 12902.8 ( 3.49x)
A72:
rgb24toyv12_16_200_neon: 9695.8 ( 2.50x)
rgb24toyv12_128_60_neon: 20286.6 ( 2.70x)
rgb24toyv12_512_16_neon: 22276.6 ( 2.57x)
rgb24toyv12_1920_4_neon: 19154.1 ( 2.77x)
rgb24toyv12_1920_4_negstride_neon: 19055.1 ( 2.78x)
rgb24toyv12_16_200_neon: 9214.8 ( 2.65x)
rgb24toyv12_128_60_neon: 20731.5 ( 2.65x)
rgb24toyv12_512_16_neon: 21145.0 ( 2.70x)
rgb24toyv12_1920_4_neon: 17586.5 ( 2.99x)
rgb24toyv12_1920_4_negstride_neon: 17571.0 ( 2.98x)
A53:
rgb24toyv12_16_200_neon: 12880.4 ( 3.76x)
rgb24toyv12_128_60_neon: 27776.3 ( 3.94x)
rgb24toyv12_512_16_neon: 29411.3 ( 3.94x)
rgb24toyv12_1920_4_neon: 27253.1 ( 3.98x)
rgb24toyv12_1920_4_negstride_neon: 27474.3 ( 3.95x)
rgb24toyv12_16_200_neon: 12196.3 ( 3.95x)
rgb24toyv12_128_60_neon: 26943.1 ( 4.07x)
rgb24toyv12_512_16_neon: 28642.3 ( 4.07x)
rgb24toyv12_1920_4_neon: 26676.6 ( 4.08x)
rgb24toyv12_1920_4_negstride_neon: 26713.8 ( 4.07x)
---
libswscale/aarch64/rgb2rgb_neon.S | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/libswscale/aarch64/rgb2rgb_neon.S b/libswscale/aarch64/rgb2rgb_neon.S
index 22ecdf7ac8..97dd781378 100644
--- a/libswscale/aarch64/rgb2rgb_neon.S
+++ b/libswscale/aarch64/rgb2rgb_neon.S
@@ -99,15 +99,16 @@ endconst
// convert rgb to 16-bit y, u, or v
// uses v3 and v4
-.macro rgbconv16 dst, b, g, r, bc, gc, rc
+
+.macro rgbconv16 dst, b, g, r, bc, gc, rc, shr_bits
smull v3.4s, \b\().4h, \bc
smlal v3.4s, \g\().4h, \gc
smlal v3.4s, \r\().4h, \rc
smull2 v4.4s, \b\().8h, \bc
smlal2 v4.4s, \g\().8h, \gc
smlal2 v4.4s, \r\().8h, \rc // v3:v4 = b * bc + g * gc + r * rc (32-bit)
- shrn \dst\().4h, v3.4s, #7
- shrn2 \dst\().8h, v4.4s, #7 // dst = b * bc + g * gc + r * rc (16-bit)
+ shrn \dst\().4h, v3.4s, \shr_bits
+ shrn2 \dst\().8h, v4.4s, \shr_bits // dst = b * bc + g * gc + r * rc (16-bit)
.endm
// void ff_rgb24toyv12_neon(const uint8_t *src, uint8_t *ydst, uint8_t *udst,
@@ -171,8 +172,8 @@ function ff_rgb24toyv12_neon, export=1
uxtl2 v21.8h, v28.16b // v21 = R12
// calculate Y values for first line
- rgbconv16 v24, v16, v17, v18, BY, GY, RY // v24 = Y11
- rgbconv16 v25, v19, v20, v21, BY, GY, RY // v25 = Y12
+ rgbconv16 v24, v16, v17, v18, BY, GY, RY, #7 // v24 = Y11
+ rgbconv16 v25, v19, v20, v21, BY, GY, RY, #7 // v25 = Y12
// load second line
ld3 {v26.16b, v27.16b, v28.16b}, [x10], #48
@@ -191,25 +192,22 @@ function ff_rgb24toyv12_neon, export=1
uxtl2 v21.8h, v28.16b // v21 = R22
// calculate Y values for second line
- rgbconv16 v26, v16, v17, v18, BY, GY, RY // v26 = Y21
- rgbconv16 v27, v19, v20, v21, BY, GY, RY // v27 = Y22
+ rgbconv16 v26, v16, v17, v18, BY, GY, RY, #7 // v26 = Y21
+ rgbconv16 v27, v19, v20, v21, BY, GY, RY, #7 // v27 = Y22
// pairwise add rgb values to calculate average
addp v16.8h, v16.8h, v19.8h
addp v17.8h, v17.8h, v20.8h
addp v18.8h, v18.8h, v21.8h
- // calculate average
+ // calculate sum of r, g, b components in 2x2 blocks
add v16.8h, v16.8h, v5.8h
add v17.8h, v17.8h, v6.8h
add v18.8h, v18.8h, v7.8h
- ushr v16.8h, v16.8h, #2
- ushr v17.8h, v17.8h, #2
- ushr v18.8h, v18.8h, #2
// calculate U and V values
- rgbconv16 v28, v16, v17, v18, BU, GU, RU // v28 = U
- rgbconv16 v29, v16, v17, v18, BV, GV, RV // v29 = V
+ rgbconv16 v28, v16, v17, v18, BU, GU, RU, #9 // v28 = U
+ rgbconv16 v29, v16, v17, v18, BV, GV, RV, #9 // v29 = V
// add offsets and narrow all values
addhn v24.8b, v24.8h, Y_OFFSET.8h
--
2.47.2
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