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synth_filter.c
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1 /*
2  * copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "fft.h"
22 #include "synth_filter.h"
23 
24 static void synth_filter_float(FFTContext *imdct,
25  float *synth_buf_ptr, int *synth_buf_offset,
26  float synth_buf2[32], const float window[512],
27  float out[32], const float in[32], float scale)
28 {
29  float *synth_buf= synth_buf_ptr + *synth_buf_offset;
30  int i, j;
31 
32  imdct->imdct_half(imdct, synth_buf, in);
33 
34  for (i = 0; i < 16; i++){
35  float a= synth_buf2[i ];
36  float b= synth_buf2[i + 16];
37  float c= 0;
38  float d= 0;
39  for (j = 0; j < 512 - *synth_buf_offset; j += 64){
40  a += window[i + j ]*(-synth_buf[15 - i + j ]);
41  b += window[i + j + 16]*( synth_buf[ i + j ]);
42  c += window[i + j + 32]*( synth_buf[16 + i + j ]);
43  d += window[i + j + 48]*( synth_buf[31 - i + j ]);
44  }
45  for ( ; j < 512; j += 64){
46  a += window[i + j ]*(-synth_buf[15 - i + j - 512]);
47  b += window[i + j + 16]*( synth_buf[ i + j - 512]);
48  c += window[i + j + 32]*( synth_buf[16 + i + j - 512]);
49  d += window[i + j + 48]*( synth_buf[31 - i + j - 512]);
50  }
51  out[i ] = a*scale;
52  out[i + 16] = b*scale;
53  synth_buf2[i ] = c;
54  synth_buf2[i + 16] = d;
55  }
56  *synth_buf_offset= (*synth_buf_offset - 32)&511;
57 }
58 
60 {
62 
63  if (ARCH_ARM) ff_synth_filter_init_arm(c);
64 }