Libav 0.7.1
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00001 /* 00002 * Atrac common functions 00003 * Copyright (c) 2006-2008 Maxim Poliakovski 00004 * Copyright (c) 2006-2008 Benjamin Larsson 00005 * 00006 * This file is part of Libav. 00007 * 00008 * Libav is free software; you can redistribute it and/or 00009 * modify it under the terms of the GNU Lesser General Public 00010 * License as published by the Free Software Foundation; either 00011 * version 2.1 of the License, or (at your option) any later version. 00012 * 00013 * Libav is distributed in the hope that it will be useful, 00014 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00016 * Lesser General Public License for more details. 00017 * 00018 * You should have received a copy of the GNU Lesser General Public 00019 * License along with Libav; if not, write to the Free Software 00020 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00021 */ 00022 00027 #include <math.h> 00028 #include <stddef.h> 00029 #include <stdio.h> 00030 00031 #include "avcodec.h" 00032 #include "dsputil.h" 00033 #include "atrac.h" 00034 00035 float ff_atrac_sf_table[64]; 00036 static float qmf_window[48]; 00037 00038 static const float qmf_48tap_half[24] = { 00039 -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269, 00040 0.0002422519, -0.00085293897,-0.0005205574, 0.0020340169, 00041 0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944, 00042 -0.000061169922,-0.01344162, 0.0024626821, 0.021736089, 00043 -0.007801671, -0.034090221, 0.01880949, 0.054326009, 00044 -0.043596379, -0.099384367, 0.13207909, 0.46424159 00045 }; 00046 00051 void atrac_generate_tables(void) 00052 { 00053 int i; 00054 float s; 00055 00056 /* Generate scale factors */ 00057 if (!ff_atrac_sf_table[63]) 00058 for (i=0 ; i<64 ; i++) 00059 ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0); 00060 00061 /* Generate the QMF window. */ 00062 if (!qmf_window[47]) 00063 for (i=0 ; i<24; i++) { 00064 s = qmf_48tap_half[i] * 2.0; 00065 qmf_window[i] = qmf_window[47 - i] = s; 00066 } 00067 } 00068 00069 00082 void atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp) 00083 { 00084 int i, j; 00085 float *p1, *p3; 00086 00087 memcpy(temp, delayBuf, 46*sizeof(float)); 00088 00089 p3 = temp + 46; 00090 00091 /* loop1 */ 00092 for(i=0; i<nIn; i+=2){ 00093 p3[2*i+0] = inlo[i ] + inhi[i ]; 00094 p3[2*i+1] = inlo[i ] - inhi[i ]; 00095 p3[2*i+2] = inlo[i+1] + inhi[i+1]; 00096 p3[2*i+3] = inlo[i+1] - inhi[i+1]; 00097 } 00098 00099 /* loop2 */ 00100 p1 = temp; 00101 for (j = nIn; j != 0; j--) { 00102 float s1 = 0.0; 00103 float s2 = 0.0; 00104 00105 for (i = 0; i < 48; i += 2) { 00106 s1 += p1[i] * qmf_window[i]; 00107 s2 += p1[i+1] * qmf_window[i+1]; 00108 } 00109 00110 pOut[0] = s2; 00111 pOut[1] = s1; 00112 00113 p1 += 2; 00114 pOut += 2; 00115 } 00116 00117 /* Update the delay buffer. */ 00118 memcpy(delayBuf, temp + nIn*2, 46*sizeof(float)); 00119 } 00120