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87552d54d3
The previous implementation targeted DTS Coherent Acoustics, which only
requires nbits == 4 (fft16()). This case was (and still is) linked directly
rather than being indirected through ff_fft_calc_vfp(), but now the full
range from radix-4 up to radix-65536 is available. This benefits other codecs
such as AAC and AC3.
The implementaion is based upon the C version, with each routine larger than
radix-16 calling a hierarchy of smaller FFT functions, then performing a
post-processing pass. This pass benefits a lot from loop unrolling to
counter the long pipelines in the VFP. A relaxed calling standard also
reduces the overhead of the call hierarchy, and avoiding the excessive
inlining performed by GCC probably helps with I-cache utilisation too.
I benchmarked the result by measuring the number of gperftools samples that
hit anywhere in the AAC decoder (starting from aac_decode_frame()) or
specifically in the FFT routines (fft4() to fft512() and pass()) for the
same sample AAC stream:
Before After
Mean StdDev Mean StdDev Confidence Change
Audio decode 2245.5 53.1 1599.6 43.8 100.0% +40.4%
FFT routines 940.6 22.0 348.1 20.8 100.0% +170.2%
Signed-off-by: Martin Storsjö <martin@martin.st>
71 lines
2.2 KiB
C
71 lines
2.2 KiB
C
/*
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* Copyright (c) 2009 Mans Rullgard <mans@mansr.com>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/arm/cpu.h"
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#include "libavcodec/fft.h"
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#include "libavcodec/rdft.h"
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#include "libavcodec/synth_filter.h"
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void ff_fft_calc_vfp(FFTContext *s, FFTComplex *z);
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void ff_fft_permute_neon(FFTContext *s, FFTComplex *z);
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void ff_fft_calc_neon(FFTContext *s, FFTComplex *z);
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void ff_imdct_half_vfp(FFTContext *s, FFTSample *output, const FFTSample *input);
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void ff_imdct_calc_neon(FFTContext *s, FFTSample *output, const FFTSample *input);
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void ff_imdct_half_neon(FFTContext *s, FFTSample *output, const FFTSample *input);
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void ff_mdct_calc_neon(FFTContext *s, FFTSample *output, const FFTSample *input);
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void ff_rdft_calc_neon(struct RDFTContext *s, FFTSample *z);
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av_cold void ff_fft_init_arm(FFTContext *s)
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{
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int cpu_flags = av_get_cpu_flags();
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if (have_vfp(cpu_flags) && !have_vfpv3(cpu_flags)) {
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s->fft_calc = ff_fft_calc_vfp;
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#if CONFIG_MDCT
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s->imdct_half = ff_imdct_half_vfp;
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#endif
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}
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if (have_neon(cpu_flags)) {
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s->fft_permute = ff_fft_permute_neon;
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s->fft_calc = ff_fft_calc_neon;
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#if CONFIG_MDCT
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s->imdct_calc = ff_imdct_calc_neon;
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s->imdct_half = ff_imdct_half_neon;
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s->mdct_calc = ff_mdct_calc_neon;
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s->mdct_permutation = FF_MDCT_PERM_INTERLEAVE;
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#endif
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}
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}
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#if CONFIG_RDFT
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av_cold void ff_rdft_init_arm(RDFTContext *s)
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{
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int cpu_flags = av_get_cpu_flags();
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if (have_neon(cpu_flags))
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s->rdft_calc = ff_rdft_calc_neon;
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}
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#endif
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