+++ /dev/null
-/*
- * MDCT/IMDCT transforms
- * Copyright (c) 2002 Fabrice Bellard.
- *
- * This library 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 of the License, or (at your option) any later version.
- *
- * This library 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 this library; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- */
-#include "dsputil.h"
-
-/**
- * @file mdct.c
- * MDCT/IMDCT transforms.
- */
-
-/**
- * init MDCT or IMDCT computation.
- */
-int ff_mdct_init(MDCTContext *s, int nbits, int inverse)
-{
- int n, n4, i;
- float alpha;
-
- memset(s, 0, sizeof(*s));
- n = 1 << nbits;
- s->nbits = nbits;
- s->n = n;
- n4 = n >> 2;
- s->tcos = av_malloc(n4 * sizeof(FFTSample));
- if (!s->tcos)
- goto fail;
- s->tsin = av_malloc(n4 * sizeof(FFTSample));
- if (!s->tsin)
- goto fail;
-
- for(i=0;i<n4;i++) {
- alpha = 2 * M_PI * (i + 1.0 / 8.0) / n;
- s->tcos[i] = -cos(alpha);
- s->tsin[i] = -sin(alpha);
- }
- if (fft_init(&s->fft, s->nbits - 2, inverse) < 0)
- goto fail;
- return 0;
- fail:
- av_freep(&s->tcos);
- av_freep(&s->tsin);
- return -1;
-}
-
-/* complex multiplication: p = a * b */
-#define CMUL(pre, pim, are, aim, bre, bim) \
-{\
- float _are = (are);\
- float _aim = (aim);\
- float _bre = (bre);\
- float _bim = (bim);\
- (pre) = _are * _bre - _aim * _bim;\
- (pim) = _are * _bim + _aim * _bre;\
-}
-
-/**
- * Compute inverse MDCT of size N = 2^nbits
- * @param output N samples
- * @param input N/2 samples
- * @param tmp N/2 samples
- */
-void ff_imdct_calc(MDCTContext *s, FFTSample *output,
- const FFTSample *input, FFTSample *tmp)
-{
- int k, n8, n4, n2, n, j;
- const uint16_t *revtab = s->fft.revtab;
- const FFTSample *tcos = s->tcos;
- const FFTSample *tsin = s->tsin;
- const FFTSample *in1, *in2;
- FFTComplex *z = (FFTComplex *)tmp;
-
- n = 1 << s->nbits;
- n2 = n >> 1;
- n4 = n >> 2;
- n8 = n >> 3;
-
- /* pre rotation */
- in1 = input;
- in2 = input + n2 - 1;
- for(k = 0; k < n4; k++) {
- j=revtab[k];
- CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
- in1 += 2;
- in2 -= 2;
- }
- fft_calc(&s->fft, z);
-
- /* post rotation + reordering */
- /* XXX: optimize */
- for(k = 0; k < n4; k++) {
- CMUL(z[k].re, z[k].im, z[k].re, z[k].im, tcos[k], tsin[k]);
- }
- for(k = 0; k < n8; k++) {
- output[2*k] = -z[n8 + k].im;
- output[n2-1-2*k] = z[n8 + k].im;
-
- output[2*k+1] = z[n8-1-k].re;
- output[n2-1-2*k-1] = -z[n8-1-k].re;
-
- output[n2 + 2*k]=-z[k+n8].re;
- output[n-1- 2*k]=-z[k+n8].re;
-
- output[n2 + 2*k+1]=z[n8-k-1].im;
- output[n-2 - 2 * k] = z[n8-k-1].im;
- }
-}
-
-/**
- * Compute MDCT of size N = 2^nbits
- * @param input N samples
- * @param out N/2 samples
- * @param tmp temporary storage of N/2 samples
- */
-void ff_mdct_calc(MDCTContext *s, FFTSample *out,
- const FFTSample *input, FFTSample *tmp)
-{
- int i, j, n, n8, n4, n2, n3;
- FFTSample re, im, re1, im1;
- const uint16_t *revtab = s->fft.revtab;
- const FFTSample *tcos = s->tcos;
- const FFTSample *tsin = s->tsin;
- FFTComplex *x = (FFTComplex *)tmp;
-
- n = 1 << s->nbits;
- n2 = n >> 1;
- n4 = n >> 2;
- n8 = n >> 3;
- n3 = 3 * n4;
-
- /* pre rotation */
- for(i=0;i<n8;i++) {
- re = -input[2*i+3*n4] - input[n3-1-2*i];
- im = -input[n4+2*i] + input[n4-1-2*i];
- j = revtab[i];
- CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
-
- re = input[2*i] - input[n2-1-2*i];
- im = -(input[n2+2*i] + input[n-1-2*i]);
- j = revtab[n8 + i];
- CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
- }
-
- fft_calc(&s->fft, x);
-
- /* post rotation */
- for(i=0;i<n4;i++) {
- re = x[i].re;
- im = x[i].im;
- CMUL(re1, im1, re, im, -tsin[i], -tcos[i]);
- out[2*i] = im1;
- out[n2-1-2*i] = re1;
- }
-}
-
-void ff_mdct_end(MDCTContext *s)
-{
- av_freep(&s->tcos);
- av_freep(&s->tsin);
- fft_end(&s->fft);
-}
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