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-rw-r--r--media/ffvpx/libavcodec/rdft.c120
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diff --git a/media/ffvpx/libavcodec/rdft.c b/media/ffvpx/libavcodec/rdft.c
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+/*
+ * (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 <stdlib.h>
+#include <math.h>
+#include "libavutil/error.h"
+#include "libavutil/mathematics.h"
+#include "rdft.h"
+
+/**
+ * @file
+ * (Inverse) Real Discrete Fourier Transforms.
+ */
+
+/** 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
+ */
+static void rdft_calc_c(RDFTContext *s, FFTSample *data)
+{
+ int i, i1, i2;
+ FFTComplex ev, od, odsum;
+ 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) {
+ s->fft.fft_permute(&s->fft, (FFTComplex*)data);
+ s->fft.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];
+
+#define RDFT_UNMANGLE(sign0, sign1) \
+ 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[i2 ]-data[i1 ]); \
+ 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 */ \
+ odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \
+ odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \
+ data[i1 ] = ev.re + odsum.re; \
+ data[i1+1] = ev.im + odsum.im; \
+ data[i2 ] = ev.re - odsum.re; \
+ data[i2+1] = odsum.im - ev.im; \
+ }
+
+ if (s->negative_sin) {
+ RDFT_UNMANGLE(+,-)
+ } else {
+ RDFT_UNMANGLE(-,+)
+ }
+
+ data[2*i+1]=s->sign_convention*data[2*i+1];
+ if (s->inverse) {
+ data[0] *= k1;
+ data[1] *= k1;
+ s->fft.fft_permute(&s->fft, (FFTComplex*)data);
+ s->fft.fft_calc(&s->fft, (FFTComplex*)data);
+ }
+}
+
+av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)
+{
+ int n = 1 << nbits;
+ int ret;
+
+ s->nbits = nbits;
+ s->inverse = trans == IDFT_C2R || trans == DFT_C2R;
+ s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
+ s->negative_sin = trans == DFT_C2R || trans == DFT_R2C;
+
+ if (nbits < 4 || nbits > 16)
+ return AVERROR(EINVAL);
+
+ if ((ret = ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C)) < 0)
+ return ret;
+
+ ff_init_ff_cos_tabs(nbits);
+ s->tcos = ff_cos_tabs[nbits];
+ s->tsin = ff_cos_tabs[nbits] + (n >> 2);
+ s->rdft_calc = rdft_calc_c;
+
+#if ARCH_ARM
+ ff_rdft_init_arm(s);
+#endif
+
+ return 0;
+}
+
+av_cold void ff_rdft_end(RDFTContext *s)
+{
+ ff_fft_end(&s->fft);
+}