Libav
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00001 /* 00002 * copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at> 00003 * 00004 * This file is part of FFmpeg. 00005 * 00006 * FFmpeg is free software; you can redistribute it and/or 00007 * modify it under the terms of the GNU Lesser General Public 00008 * License as published by the Free Software Foundation; either 00009 * version 2.1 of the License, or (at your option) any later version. 00010 * 00011 * FFmpeg is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00014 * Lesser General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU Lesser General Public 00017 * License along with FFmpeg; if not, write to the Free Software 00018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00019 */ 00020 00021 #include "fft.h" 00022 #include "synth_filter.h" 00023 00024 static void synth_filter_float(FFTContext *imdct, 00025 float *synth_buf_ptr, int *synth_buf_offset, 00026 float synth_buf2[32], const float window[512], 00027 float out[32], const float in[32], float scale, float bias) 00028 { 00029 float *synth_buf= synth_buf_ptr + *synth_buf_offset; 00030 int i, j; 00031 00032 ff_imdct_half(imdct, synth_buf, in); 00033 00034 for (i = 0; i < 16; i++){ 00035 float a= synth_buf2[i ]; 00036 float b= synth_buf2[i + 16]; 00037 float c= 0; 00038 float d= 0; 00039 for (j = 0; j < 512 - *synth_buf_offset; j += 64){ 00040 a += window[i + j ]*(-synth_buf[15 - i + j ]); 00041 b += window[i + j + 16]*( synth_buf[ i + j ]); 00042 c += window[i + j + 32]*( synth_buf[16 + i + j ]); 00043 d += window[i + j + 48]*( synth_buf[31 - i + j ]); 00044 } 00045 for ( ; j < 512; j += 64){ 00046 a += window[i + j ]*(-synth_buf[15 - i + j - 512]); 00047 b += window[i + j + 16]*( synth_buf[ i + j - 512]); 00048 c += window[i + j + 32]*( synth_buf[16 + i + j - 512]); 00049 d += window[i + j + 48]*( synth_buf[31 - i + j - 512]); 00050 } 00051 out[i ] = a*scale + bias; 00052 out[i + 16] = b*scale + bias; 00053 synth_buf2[i ] = c; 00054 synth_buf2[i + 16] = d; 00055 } 00056 *synth_buf_offset= (*synth_buf_offset - 32)&511; 00057 } 00058 00059 av_cold void ff_synth_filter_init(SynthFilterContext *c) 00060 { 00061 c->synth_filter_float = synth_filter_float; 00062 00063 if (ARCH_ARM) ff_synth_filter_init_arm(c); 00064 }