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https://github.com/FFmpeg/FFmpeg.git
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e8f054b095
Required minimal changes to the code so made sense to implement. FFT and MDCT tested, the output of both was properly rounded. Fun fact: the non-power-of-two fixed-point FFT and MDCT are the fastest ever non-power-of-two fixed-point FFT and MDCT written. This can replace the power of two integer MDCTs in aac and ac3 if the MIPS optimizations are ported across. Unfortunately the ac3 encoder uses a 16-bit fixed point forward transform, unlike the encoder which uses a 32bit inverse transform, so some modifications might be required there. The 3-point FFT is somewhat less accurate than it otherwise could be, having minor rounding errors with bigger transforms. However, this could be improved later, and the way its currently written is the way one would write assembly for it. Similar rounding errors can also be found throughout the power of two FFTs as well, though those are more difficult to correct. Despite this, the integer transforms are more than accurate enough.
159 lines
5.8 KiB
C
159 lines
5.8 KiB
C
/*
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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
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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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* 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 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 FFmpeg; 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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#ifndef AVUTIL_TX_PRIV_H
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#define AVUTIL_TX_PRIV_H
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#include "tx.h"
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#include <stddef.h>
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#include "thread.h"
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#include "mem.h"
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#include "avassert.h"
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#include "attributes.h"
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#ifdef TX_FLOAT
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#define TX_NAME(x) x ## _float
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#define SCALE_TYPE float
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typedef float FFTSample;
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typedef AVComplexFloat FFTComplex;
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#elif defined(TX_DOUBLE)
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#define TX_NAME(x) x ## _double
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#define SCALE_TYPE double
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typedef double FFTSample;
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typedef AVComplexDouble FFTComplex;
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#elif defined(TX_INT32)
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#define TX_NAME(x) x ## _int32
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#define SCALE_TYPE float
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typedef int32_t FFTSample;
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typedef AVComplexInt32 FFTComplex;
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#else
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typedef void FFTComplex;
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#endif
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#if defined(TX_FLOAT) || defined(TX_DOUBLE)
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#define MUL(x, y) ((x)*(y))
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#define CMUL(dre, dim, are, aim, bre, bim) do { \
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(dre) = (are) * (bre) - (aim) * (bim); \
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(dim) = (are) * (bim) + (aim) * (bre); \
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} while (0)
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#define SMUL(dre, dim, are, aim, bre, bim) do { \
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(dre) = (are) * (bre) - (aim) * (bim); \
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(dim) = (are) * (bim) - (aim) * (bre); \
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} while (0)
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#define RESCALE(x) (x)
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#define FOLD(a, b) ((a) + (b))
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#elif defined(TX_INT32)
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#define MUL(x, y) ((int32_t)(((int64_t)(x) * (int64_t)(y) + 0x40000000) >> 31))
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/* Properly rounds the result */
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#define CMUL(dre, dim, are, aim, bre, bim) do { \
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int64_t accu; \
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(accu) = (int64_t)(bre) * (are); \
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(accu) -= (int64_t)(bim) * (aim); \
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(dre) = (int)(((accu) + 0x40000000) >> 31); \
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(accu) = (int64_t)(bim) * (are); \
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(accu) += (int64_t)(bre) * (aim); \
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(dim) = (int)(((accu) + 0x40000000) >> 31); \
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} while (0)
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#define SMUL(dre, dim, are, aim, bre, bim) do { \
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int64_t accu; \
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(accu) = (int64_t)(bre) * (are); \
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(accu) -= (int64_t)(bim) * (aim); \
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(dre) = (int)(((accu) + 0x40000000) >> 31); \
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(accu) = (int64_t)(bim) * (are); \
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(accu) -= (int64_t)(bre) * (aim); \
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(dim) = (int)(((accu) + 0x40000000) >> 31); \
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} while (0)
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#define RESCALE(x) (lrintf((x) * 2147483648.0))
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#define FOLD(x, y) ((int)((x) + (unsigned)(y) + 32) >> 6)
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#endif
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#define BF(x, y, a, b) do { \
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x = (a) - (b); \
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y = (a) + (b); \
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} while (0)
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#define CMUL3(c, a, b) \
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CMUL((c).re, (c).im, (a).re, (a).im, (b).re, (b).im)
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#define COSTABLE(size) \
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DECLARE_ALIGNED(32, FFTSample, TX_NAME(ff_cos_##size))[size/2]
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/* Used by asm, reorder with care */
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struct AVTXContext {
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int n; /* Nptwo part */
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int m; /* Ptwo part */
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int inv; /* Is inverted */
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int type; /* Type */
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FFTComplex *exptab; /* MDCT exptab */
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FFTComplex *tmp; /* Temporary buffer needed for all compound transforms */
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int *pfatab; /* Input/Output mapping for compound transforms */
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int *revtab; /* Input mapping for power of two transforms */
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};
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/* Shared functions */
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int ff_tx_type_is_mdct(enum AVTXType type);
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int ff_tx_gen_compound_mapping(AVTXContext *s);
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int ff_tx_gen_ptwo_revtab(AVTXContext *s);
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/* Also used by SIMD init */
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static inline int split_radix_permutation(int i, int n, int inverse)
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{
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int m;
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if (n <= 2)
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return i & 1;
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m = n >> 1;
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if (!(i & m))
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return split_radix_permutation(i, m, inverse)*2;
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m >>= 1;
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if (inverse == !(i & m))
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return split_radix_permutation(i, m, inverse)*4 + 1;
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else
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return split_radix_permutation(i, m, inverse)*4 - 1;
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}
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/* Templated functions */
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int ff_tx_init_mdct_fft_float(AVTXContext *s, av_tx_fn *tx,
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enum AVTXType type, int inv, int len,
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const void *scale, uint64_t flags);
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int ff_tx_init_mdct_fft_double(AVTXContext *s, av_tx_fn *tx,
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enum AVTXType type, int inv, int len,
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const void *scale, uint64_t flags);
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int ff_tx_init_mdct_fft_int32(AVTXContext *s, av_tx_fn *tx,
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enum AVTXType type, int inv, int len,
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const void *scale, uint64_t flags);
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typedef struct CosTabsInitOnce {
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void (*func)(void);
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AVOnce control;
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} CosTabsInitOnce;
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#endif /* AVUTIL_TX_PRIV_H */
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