FFmpeg: libavcodec/mdct_fixed.c Source File

00001 /*
00002  * This file is part of FFmpeg.
00003  *
00004  * FFmpeg is free software; you can redistribute it and/or
00005  * modify it under the terms of the GNU Lesser General Public
00006  * License as published by the Free Software Foundation; either
00007  * version 2.1 of the License, or (at your option) any later version.
00008  *
00009  * FFmpeg is distributed in the hope that it will be useful,
00010  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012  * Lesser General Public License for more details.
00013  *
00014  * You should have received a copy of the GNU Lesser General Public
00015  * License along with FFmpeg; if not, write to the Free Software
00016  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00017  */
00018 
00019 #define CONFIG_FFT_FLOAT 0
00020 #include "mdct.c"
00021 
00022 /* same as ff_mdct_calcw_c with double-width unscaled output */
00023 void ff_mdct_calcw_c(FFTContext *s, FFTDouble *out, const FFTSample *input)
00024 {
00025     int i, j, n, n8, n4, n2, n3;
00026     FFTDouble re, im;
00027     const uint16_t *revtab = s->revtab;
00028     const FFTSample *tcos = s->tcos;
00029     const FFTSample *tsin = s->tsin;
00030     FFTComplex *x = s->tmp_buf;
00031     FFTDComplex *o = (FFTDComplex *)out;
00032 
00033     n = 1 << s->mdct_bits;
00034     n2 = n >> 1;
00035     n4 = n >> 2;
00036     n8 = n >> 3;
00037     n3 = 3 * n4;
00038 
00039     /* pre rotation */
00040     for(i=0;i<n8;i++) {
00041         re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);
00042         im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);
00043         j = revtab[i];
00044         CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
00045 
00046         re = RSCALE( input[2*i]    - input[n2-1-2*i]);
00047         im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);
00048         j = revtab[n8 + i];
00049         CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
00050     }
00051 
00052     s->fft_calc(s, x);
00053 
00054     /* post rotation */
00055     for(i=0;i<n8;i++) {
00056         FFTDouble r0, i0, r1, i1;
00057         CMULL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
00058         CMULL(i0, r1, x[n8+i  ].re, x[n8+i  ].im, -tsin[n8+i  ], -tcos[n8+i  ]);
00059         o[n8-i-1].re = r0;
00060         o[n8-i-1].im = i0;
00061         o[n8+i  ].re = r1;
00062         o[n8+i  ].im = i1;
00063     }
00064 }