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https://github.com/FFmpeg/FFmpeg.git
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0886e50c6b
Implement NEON optimization for HEVC dequant at 8-bit depth. The NEON implementation uses srshr (Signed Rounding Shift Right) which does both the add with offset and right shift in a single instruction. Optimization details: - 4x4 (16 coeffs): Single load-process-store sequence - 8x8 (64 coeffs): Fully unrolled, no loop overhead - 16x16 (256 coeffs): Pipelined load/compute/store to hide memory latency - 32x32 (1024 coeffs): Pipelined with all available NEON registers Performance benchmark on Apple M4: ./tests/checkasm/checkasm --test=hevc_dequant --bench hevc_dequant_4x4_8_c: 11.3 ( 1.00x) hevc_dequant_4x4_8_neon: 6.3 ( 1.78x) hevc_dequant_8x8_8_c: 33.9 ( 1.00x) hevc_dequant_8x8_8_neon: 6.6 ( 5.11x) hevc_dequant_16x16_8_c: 153.8 ( 1.00x) hevc_dequant_16x16_8_neon: 9.0 (17.02x) hevc_dequant_32x32_8_c: 78.1 ( 1.00x) hevc_dequant_32x32_8_neon: 31.9 ( 2.45x) Note on Performance Anomaly: The observation that hevc_dequant_32x32_8_c is faster than 16x16 (78.1 vs 153.8) is due to Clang auto-vectorizing only for sizes >= 32x32. Compiler: Apple clang version 17.0.0 (clang-1700.6.3.2) Signed-off-by: Jun Zhao <barryjzhao@tencent.com>
77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
/*
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* Copyright (c) 2024 FFmpeg contributors
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with FFmpeg; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <string.h>
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mem_internal.h"
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#include "libavcodec/hevc/dsp.h"
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#include "checkasm.h"
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#define randomize_buffers(buf, size) \
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do { \
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int j; \
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for (j = 0; j < size; j++) { \
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int16_t r = rnd() & 0x7FFF; \
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if (rnd() & 1) r = -r; \
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AV_WN16A(buf + j, r); \
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} \
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} while (0)
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static void check_dequant(HEVCDSPContext *h, int bit_depth)
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{
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int i;
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LOCAL_ALIGNED(32, int16_t, coeffs0, [32 * 32]);
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LOCAL_ALIGNED(32, int16_t, coeffs1, [32 * 32]);
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for (i = 2; i <= 5; i++) {
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int block_size = 1 << i;
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int size = block_size * block_size;
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declare_func(void, int16_t *coeffs, int16_t log2_size);
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randomize_buffers(coeffs0, size);
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memcpy(coeffs1, coeffs0, sizeof(*coeffs0) * size);
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if (check_func(h->dequant, "hevc_dequant_%dx%d_%d",
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block_size, block_size, bit_depth)) {
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call_ref(coeffs0, i);
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call_new(coeffs1, i);
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if (memcmp(coeffs0, coeffs1, sizeof(*coeffs0) * size))
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fail();
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bench_new(coeffs1, i);
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}
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}
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}
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void checkasm_check_hevc_dequant(void)
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{
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int bit_depth;
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for (bit_depth = 8; bit_depth <= 12; bit_depth += 2) {
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HEVCDSPContext h;
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ff_hevc_dsp_init(&h, bit_depth);
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check_dequant(&h, bit_depth);
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}
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report("dequant");
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}
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