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Add the rdft family of transforms (fft/ifft of an all real sequence) to dsputil.

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Originally committed as revision 16864 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Alex Converse 16 years ago
parent 9d52d54df3
commit 6860254044
5 changed files with 162 additions and 1 deletions
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  1. 2
      configure
  2. 1
      libavcodec/Makefile
  3. 31
      libavcodec/dsputil.h
  4. 2
      libavcodec/fft.c
  5. 127
      libavcodec/rdft.c

2
configure vendored
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@ -102,6 +102,7 @@ show_help(){
echo " --disable-fft disable FFT code"
echo " --disable-golomb disable Golomb code"
echo " --disable-mdct disable MDCT code"
echo " --disable-rdft disable RDFT code"
echo " --enable-hardcoded-tables use hardcoded tables instead of runtime generation"
echo " --enable-memalign-hack emulate memalign, interferes with memory debuggers"
echo " --enable-beos-netserver enable BeOS netserver"
@ -781,6 +782,7 @@ CONFIG_LIST="
nonfree
postproc
powerpc_perf
rdft
shared
small
static

1
libavcodec/Makefile
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@ -29,6 +29,7 @@ OBJS-$(CONFIG_ENCODERS) += faandct.o jfdctfst.o jfdctint.o
OBJS-$(CONFIG_FFT) += fft.o
OBJS-$(CONFIG_GOLOMB) += golomb.o
OBJS-$(CONFIG_MDCT) += mdct.o
OBJS-$(CONFIG_RDFT) += rdft.o
OBJS-$(CONFIG_OLDSCALER) += imgresample.o
# decoders/encoders

31
libavcodec/dsputil.h
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@ -674,6 +674,8 @@ typedef struct FFTContext {
void (*imdct_half)(struct MDCTContext *s, FFTSample *output, const FFTSample *input);
} FFTContext;
extern FFTSample* ff_cos_tabs[13];
/**
* Sets up a complex FFT.
* @param nbits log2 of the length of the input array
@ -759,6 +761,35 @@ void ff_imdct_half_sse(MDCTContext *s, FFTSample *output, const FFTSample *input
void ff_mdct_calc(MDCTContext *s, FFTSample *out, const FFTSample *input);
void ff_mdct_end(MDCTContext *s);
/* Real Discrete Fourier Transform */
enum RDFTransformType {
RDFT,
IRDFT,
RIDFT,
IRIDFT,
};
typedef struct {
int nbits;
int inverse;
int sign_convention;
/* pre/post rotation tables */
FFTSample *tcos;
FFTSample *tsin;
FFTContext fft;
} RDFTContext;
/**
* Sets up a real FFT.
* @param nbits log2 of the length of the input array
* @param trans the type of transform
*/
int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans);
void ff_rdft_calc(RDFTContext *s, FFTSample *data);
void ff_rdft_end(RDFTContext *s);
#define WRAPPER8_16(name8, name16)\
static int name16(void /*MpegEncContext*/ *s, uint8_t *dst, uint8_t *src, int stride, int h){\
return name8(s, dst , src , stride, h)\

2
libavcodec/fft.c
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@ -42,7 +42,7 @@ DECLARE_ALIGNED_16(FFTSample, ff_cos_8192[4096]);
DECLARE_ALIGNED_16(FFTSample, ff_cos_16384[8192]);
DECLARE_ALIGNED_16(FFTSample, ff_cos_32768[16384]);
DECLARE_ALIGNED_16(FFTSample, ff_cos_65536[32768]);
static FFTSample *ff_cos_tabs[] = {
FFTSample *ff_cos_tabs[] = {
ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256, ff_cos_512, ff_cos_1024,
ff_cos_2048, ff_cos_4096, ff_cos_8192, ff_cos_16384, ff_cos_32768, ff_cos_65536,
};

127
libavcodec/rdft.c
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@ -0,0 +1,127 @@
/*
* (I)RDFT transforms
* Copyright (c) 2009 Alex Converse <alex dot converse at gmail dot com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include "dsputil.h"
/**
* @file rdft.c
* (Inverse) Real Discrete Fourier Transforms.
*/
/* sin(2*pi*x/n) for 0<=x<n/4, followed by n/2<=x<3n/4 */
DECLARE_ALIGNED_16(FFTSample, ff_sin_16[8]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_32[16]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_64[32]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_128[64]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_256[128]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_512[256]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_1024[512]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_2048[1024]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_4096[2048]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_8192[4096]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_16384[8192]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_32768[16384]);
DECLARE_ALIGNED_16(FFTSample, ff_sin_65536[32768]);
FFTSample *ff_sin_tabs[] = {
ff_sin_16, ff_sin_32, ff_sin_64, ff_sin_128, ff_sin_256, ff_sin_512, ff_sin_1024,
ff_sin_2048, ff_sin_4096, ff_sin_8192, ff_sin_16384, ff_sin_32768, ff_sin_65536,
};
av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)
{
int n = 1 << nbits;
int i;
const double theta = (trans == RDFT || trans == IRIDFT ? -1 : 1)*2*M_PI/n;
s->nbits = nbits;
s->inverse = trans == IRDFT || trans == IRIDFT;
s->sign_convention = trans == RIDFT || trans == IRIDFT ? 1 : -1;
if (nbits < 4 || nbits > 16)
return -1;
if (ff_fft_init(&s->fft, nbits-1, trans == IRDFT || trans == RIDFT) < 0)
return -1;
s->tcos = ff_cos_tabs[nbits-4];
s->tsin = ff_sin_tabs[nbits-4]+(trans == RDFT || trans == IRIDFT)*(n>>2);
for (i = 0; i < (n>>2); i++) {
s->tcos[i] = cos(i*theta);
s->tsin[i] = sin(i*theta);
}
return 0;
}
/** Map one real FFT into two parallel real even and odd FFTs. Then interleave
* the two real FFTs into one complex FFT. Unmangle the results.
* ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
*/
void ff_rdft_calc_c(RDFTContext* s, FFTSample* data)
{
int i, i1, i2;
FFTComplex ev, od;
const int n = 1 << s->nbits;
const float k1 = 0.5;
const float k2 = 0.5 - s->inverse;
const FFTSample *tcos = s->tcos;
const FFTSample *tsin = s->tsin;
if (!s->inverse) {
ff_fft_permute(&s->fft, (FFTComplex*)data);
ff_fft_calc(&s->fft, (FFTComplex*)data);
}
/* i=0 is a special case because of packing, the DC term is real, so we
are going to throw the N/2 term (also real) in with it. */
ev.re = data[0];
data[0] = ev.re+data[1];
data[1] = ev.re-data[1];
for (i = 1; i < (n>>2); i++) {
i1 = 2*i;
i2 = n-i1;
/* Separate even and odd FFTs */
ev.re = k1*(data[i1 ]+data[i2 ]);
od.im = -k2*(data[i1 ]-data[i2 ]);
ev.im = k1*(data[i1+1]-data[i2+1]);
od.re = k2*(data[i1+1]+data[i2+1]);
/* Apply twiddle factors to the odd FFT and add to the even FFT */
data[i1 ] = ev.re + od.re*tcos[i] - od.im*tsin[i];
data[i1+1] = ev.im + od.im*tcos[i] + od.re*tsin[i];
data[i2 ] = ev.re - od.re*tcos[i] + od.im*tsin[i];
data[i2+1] = -ev.im + od.im*tcos[i] + od.re*tsin[i];
}
data[2*i+1]=s->sign_convention*data[2*i+1];
if (s->inverse) {
data[0] *= k1;
data[1] *= k1;
ff_fft_permute(&s->fft, (FFTComplex*)data);
ff_fft_calc(&s->fft, (FFTComplex*)data);
}
}
void ff_rdft_calc(RDFTContext *s, FFTSample *data)
{
ff_rdft_calc_c(s, data);
}
av_cold void ff_rdft_end(RDFTContext *s)
{
ff_fft_end(&s->fft);
}
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