release/src/router/ffmpeg/libavcodec/atrac.c

   1 /*
   2  * Atrac common functions
   3  * Copyright (c) 2006-2008 Maxim Poliakovski
   4  * Copyright (c) 2006-2008 Benjamin Larsson
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file
  25  */
  26
  27 #include <math.h>
  28 #include <stddef.h>
  29 #include <stdio.h>
  30
  31 #include "avcodec.h"
  32 #include "dsputil.h"
  33 #include "atrac.h"
  34
  35 float sf_table[64];
  36 float qmf_window[48];
  37
  38 static const float qmf_48tap_half[24] = {
  39    -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
  40     0.0002422519,  -0.00085293897,-0.0005205574,  0.0020340169,
  41     0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
  42    -0.000061169922,-0.01344162,    0.0024626821,  0.021736089,
  43    -0.007801671,   -0.034090221,   0.01880949,    0.054326009,
  44    -0.043596379,   -0.099384367,   0.13207909,    0.46424159
  45 };
  46
  47 /**
  48  * Generate common tables
  49  */
  50
  51 void atrac_generate_tables(void)
  52 {
  53     int i;
  54     float s;
  55
  56     /* Generate scale factors */
  57     if (!sf_table[63])
  58         for (i=0 ; i<64 ; i++)
  59             sf_table[i] = pow(2.0, (i - 15) / 3.0);
  60
  61     /* Generate the QMF window. */
  62     if (!qmf_window[47])
  63         for (i=0 ; i<24; i++) {
  64             s = qmf_48tap_half[i] * 2.0;
  65             qmf_window[i] = qmf_window[47 - i] = s;
  66         }
  67 }
  68
  69
  70 /**
  71  * Quadrature mirror synthesis filter.
  72  *
  73  * @param inlo      lower part of spectrum
  74  * @param inhi      higher part of spectrum
  75  * @param nIn       size of spectrum buffer
  76  * @param pOut      out buffer
  77  * @param delayBuf  delayBuf buffer
  78  * @param temp      temp buffer
  79  */
  80
  81
  82 void atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
  83 {
  84     int   i, j;
  85     float   *p1, *p3;
  86
  87     memcpy(temp, delayBuf, 46*sizeof(float));
  88
  89     p3 = temp + 46;
  90
  91     /* loop1 */
  92     for(i=0; i<nIn; i+=2){
  93         p3[2*i+0] = inlo[i  ] + inhi[i  ];
  94         p3[2*i+1] = inlo[i  ] - inhi[i  ];
  95         p3[2*i+2] = inlo[i+1] + inhi[i+1];
  96         p3[2*i+3] = inlo[i+1] - inhi[i+1];
  97     }
  98
  99     /* loop2 */
 100     p1 = temp;
 101     for (j = nIn; j != 0; j--) {
 102         float s1 = 0.0;
 103         float s2 = 0.0;
 104
 105         for (i = 0; i < 48; i += 2) {
 106             s1 += p1[i] * qmf_window[i];
 107             s2 += p1[i+1] * qmf_window[i+1];
 108         }
 109
 110         pOut[0] = s2;
 111         pOut[1] = s1;
 112
 113         p1 += 2;
 114         pOut += 2;
 115     }
 116
 117     /* Update the delay buffer. */
 118     memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
 119 }
 120