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authorAlex Converse <alex.converse@gmail.com>2009-01-30 20:15:48 +0000
committerAlex Converse <alex.converse@gmail.com>2009-01-30 20:15:48 +0000
commit686025404486c751c808aa7441da19cacef637b4 (patch)
treeb07c0ab6665aaf6c6c8d081c65a1b4d8832b70a4 /libavcodec
parent9d52d54df35d43b149ed1d1607fc95948df70f8c (diff)
downloadffmpeg-686025404486c751c808aa7441da19cacef637b4.tar.gz
Add the rdft family of transforms (fft/ifft of an all real sequence) to dsputil.
Originally committed as revision 16864 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec')
-rw-r--r--libavcodec/Makefile1
-rw-r--r--libavcodec/dsputil.h31
-rw-r--r--libavcodec/fft.c2
-rw-r--r--libavcodec/rdft.c127
4 files changed, 160 insertions, 1 deletions
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 9abedfc607..7ccf694c2e 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -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
diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h
index 165aef7a09..66557138bf 100644
--- a/libavcodec/dsputil.h
+++ b/libavcodec/dsputil.h
@@ -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)\
diff --git a/libavcodec/fft.c b/libavcodec/fft.c
index db79fc90e9..47ecdb48de 100644
--- a/libavcodec/fft.c
+++ b/libavcodec/fft.c
@@ -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,
};
diff --git a/libavcodec/rdft.c b/libavcodec/rdft.c
new file mode 100644
index 0000000000..36c6f1bf05
--- /dev/null
+++ b/libavcodec/rdft.c
@@ -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);
+}