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 35float sf_table[64]; 36float qmf_window[48]; 37 38static 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 51void 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 82void 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} 120 121