annotate src/audio/SDL_audiocvt.c @ 252:e8157fcb3114

Updated the source with the correct e-mail address
author Sam Lantinga <slouken@libsdl.org>
date Fri, 14 Dec 2001 12:38:15 +0000
parents 74212992fb08
children f6ffac90895c
rev   line source
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with this library; if not, write to the Free
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17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 Sam Lantinga
252
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20 slouken@libsdl.org
0
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21 */
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22
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23 #ifdef SAVE_RCSID
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24 static char rcsid =
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25 "@(#) $Id$";
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26 #endif
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27
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28 /* Functions for audio drivers to perform runtime conversion of audio format */
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29
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30 #include <stdio.h>
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31
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32 #include "SDL_error.h"
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33 #include "SDL_audio.h"
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34
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35
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36 /* Effectively mix right and left channels into a single channel */
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37 void SDL_ConvertMono(SDL_AudioCVT *cvt, Uint16 format)
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38 {
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39 int i;
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40 Sint32 sample;
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41
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42 #ifdef DEBUG_CONVERT
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43 fprintf(stderr, "Converting to mono\n");
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44 #endif
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45 switch (format&0x8018) {
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46
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47 case AUDIO_U8: {
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48 Uint8 *src, *dst;
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49
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50 src = cvt->buf;
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51 dst = cvt->buf;
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52 for ( i=cvt->len_cvt/2; i; --i ) {
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53 sample = src[0] + src[1];
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54 if ( sample > 255 ) {
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55 *dst = 255;
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56 } else {
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57 *dst = sample;
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58 }
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59 src += 2;
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60 dst += 1;
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61 }
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62 }
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63 break;
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64
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65 case AUDIO_S8: {
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66 Sint8 *src, *dst;
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67
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68 src = (Sint8 *)cvt->buf;
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69 dst = (Sint8 *)cvt->buf;
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70 for ( i=cvt->len_cvt/2; i; --i ) {
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71 sample = src[0] + src[1];
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72 if ( sample > 127 ) {
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73 *dst = 127;
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74 } else
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75 if ( sample < -128 ) {
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76 *dst = -128;
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77 } else {
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78 *dst = sample;
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79 }
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80 src += 2;
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81 dst += 1;
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82 }
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83 }
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84 break;
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85
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86 case AUDIO_U16: {
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87 Uint8 *src, *dst;
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88
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89 src = cvt->buf;
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90 dst = cvt->buf;
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91 if ( (format & 0x1000) == 0x1000 ) {
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92 for ( i=cvt->len_cvt/4; i; --i ) {
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93 sample = (Uint16)((src[0]<<8)|src[1])+
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94 (Uint16)((src[2]<<8)|src[3]);
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95 if ( sample > 65535 ) {
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96 dst[0] = 0xFF;
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97 dst[1] = 0xFF;
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98 } else {
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99 dst[1] = (sample&0xFF);
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100 sample >>= 8;
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101 dst[0] = (sample&0xFF);
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102 }
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103 src += 4;
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104 dst += 2;
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105 }
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106 } else {
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107 for ( i=cvt->len_cvt/4; i; --i ) {
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108 sample = (Uint16)((src[1]<<8)|src[0])+
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109 (Uint16)((src[3]<<8)|src[2]);
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110 if ( sample > 65535 ) {
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111 dst[0] = 0xFF;
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112 dst[1] = 0xFF;
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113 } else {
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114 dst[0] = (sample&0xFF);
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115 sample >>= 8;
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116 dst[1] = (sample&0xFF);
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117 }
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118 src += 4;
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119 dst += 2;
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120 }
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121 }
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122 }
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123 break;
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124
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125 case AUDIO_S16: {
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126 Uint8 *src, *dst;
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127
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128 src = cvt->buf;
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129 dst = cvt->buf;
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130 if ( (format & 0x1000) == 0x1000 ) {
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131 for ( i=cvt->len_cvt/4; i; --i ) {
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132 sample = (Sint16)((src[0]<<8)|src[1])+
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133 (Sint16)((src[2]<<8)|src[3]);
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134 if ( sample > 32767 ) {
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135 dst[0] = 0x7F;
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136 dst[1] = 0xFF;
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137 } else
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138 if ( sample < -32768 ) {
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139 dst[0] = 0x80;
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140 dst[1] = 0x00;
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141 } else {
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142 dst[1] = (sample&0xFF);
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143 sample >>= 8;
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144 dst[0] = (sample&0xFF);
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145 }
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146 src += 4;
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147 dst += 2;
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148 }
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149 } else {
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150 for ( i=cvt->len_cvt/4; i; --i ) {
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151 sample = (Sint16)((src[1]<<8)|src[0])+
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152 (Sint16)((src[3]<<8)|src[2]);
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153 if ( sample > 32767 ) {
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154 dst[1] = 0x7F;
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155 dst[0] = 0xFF;
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156 } else
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157 if ( sample < -32768 ) {
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158 dst[1] = 0x80;
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159 dst[0] = 0x00;
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160 } else {
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161 dst[0] = (sample&0xFF);
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162 sample >>= 8;
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163 dst[1] = (sample&0xFF);
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164 }
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165 src += 4;
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166 dst += 2;
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167 }
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168 }
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169 }
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170 break;
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171 }
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172 cvt->len_cvt /= 2;
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173 if ( cvt->filters[++cvt->filter_index] ) {
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174 cvt->filters[cvt->filter_index](cvt, format);
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175 }
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parents:
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176 }
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parents:
diff changeset
177
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178
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179 /* Duplicate a mono channel to both stereo channels */
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180 void SDL_ConvertStereo(SDL_AudioCVT *cvt, Uint16 format)
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181 {
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182 int i;
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183
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184 #ifdef DEBUG_CONVERT
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185 fprintf(stderr, "Converting to stereo\n");
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186 #endif
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187 if ( (format & 0xFF) == 16 ) {
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188 Uint16 *src, *dst;
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189
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190 src = (Uint16 *)(cvt->buf+cvt->len_cvt);
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191 dst = (Uint16 *)(cvt->buf+cvt->len_cvt*2);
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192 for ( i=cvt->len_cvt/2; i; --i ) {
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193 dst -= 2;
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194 src -= 1;
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195 dst[0] = src[0];
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196 dst[1] = src[0];
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197 }
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198 } else {
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199 Uint8 *src, *dst;
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200
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201 src = cvt->buf+cvt->len_cvt;
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202 dst = cvt->buf+cvt->len_cvt*2;
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203 for ( i=cvt->len_cvt; i; --i ) {
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204 dst -= 2;
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205 src -= 1;
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206 dst[0] = src[0];
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207 dst[1] = src[0];
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208 }
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209 }
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210 cvt->len_cvt *= 2;
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211 if ( cvt->filters[++cvt->filter_index] ) {
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212 cvt->filters[cvt->filter_index](cvt, format);
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213 }
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214 }
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215
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216 /* Convert 8-bit to 16-bit - LSB */
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217 void SDL_Convert16LSB(SDL_AudioCVT *cvt, Uint16 format)
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218 {
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219 int i;
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220 Uint8 *src, *dst;
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221
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222 #ifdef DEBUG_CONVERT
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223 fprintf(stderr, "Converting to 16-bit LSB\n");
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224 #endif
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225 src = cvt->buf+cvt->len_cvt;
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226 dst = cvt->buf+cvt->len_cvt*2;
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227 for ( i=cvt->len_cvt; i; --i ) {
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228 src -= 1;
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229 dst -= 2;
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230 dst[1] = *src;
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231 dst[0] = 0;
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diff changeset
232 }
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233 format = ((format & ~0x0008) | AUDIO_U16LSB);
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234 cvt->len_cvt *= 2;
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diff changeset
235 if ( cvt->filters[++cvt->filter_index] ) {
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236 cvt->filters[cvt->filter_index](cvt, format);
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237 }
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parents:
diff changeset
238 }
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
239 /* Convert 8-bit to 16-bit - MSB */
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diff changeset
240 void SDL_Convert16MSB(SDL_AudioCVT *cvt, Uint16 format)
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241 {
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242 int i;
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diff changeset
243 Uint8 *src, *dst;
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parents:
diff changeset
244
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diff changeset
245 #ifdef DEBUG_CONVERT
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246 fprintf(stderr, "Converting to 16-bit MSB\n");
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diff changeset
247 #endif
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248 src = cvt->buf+cvt->len_cvt;
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249 dst = cvt->buf+cvt->len_cvt*2;
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diff changeset
250 for ( i=cvt->len_cvt; i; --i ) {
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diff changeset
251 src -= 1;
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Sam Lantinga <slouken@lokigames.com>
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diff changeset
252 dst -= 2;
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diff changeset
253 dst[0] = *src;
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254 dst[1] = 0;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
255 }
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Sam Lantinga <slouken@lokigames.com>
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diff changeset
256 format = ((format & ~0x0008) | AUDIO_U16MSB);
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diff changeset
257 cvt->len_cvt *= 2;
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Sam Lantinga <slouken@lokigames.com>
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diff changeset
258 if ( cvt->filters[++cvt->filter_index] ) {
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
259 cvt->filters[cvt->filter_index](cvt, format);
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Sam Lantinga <slouken@lokigames.com>
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diff changeset
260 }
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
261 }
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
262
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
263 /* Convert 16-bit to 8-bit */
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
264 void SDL_Convert8(SDL_AudioCVT *cvt, Uint16 format)
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
265 {
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parents:
diff changeset
266 int i;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
267 Uint8 *src, *dst;
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parents:
diff changeset
268
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parents:
diff changeset
269 #ifdef DEBUG_CONVERT
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diff changeset
270 fprintf(stderr, "Converting to 8-bit\n");
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
271 #endif
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
272 src = cvt->buf;
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Sam Lantinga <slouken@lokigames.com>
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diff changeset
273 dst = cvt->buf;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
274 if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
275 ++src;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
276 }
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
277 for ( i=cvt->len_cvt/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
278 *dst = *src;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
279 src += 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
280 dst += 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
281 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
282 format = ((format & ~0x9010) | AUDIO_U8);
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
283 cvt->len_cvt /= 2;
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
284 if ( cvt->filters[++cvt->filter_index] ) {
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
285 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
286 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
287 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
288
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
289 /* Toggle signed/unsigned */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
290 void SDL_ConvertSign(SDL_AudioCVT *cvt, Uint16 format)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
291 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
292 int i;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
293 Uint8 *data;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
294
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
295 #ifdef DEBUG_CONVERT
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
296 fprintf(stderr, "Converting audio signedness\n");
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Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
297 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
298 data = cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
299 if ( (format & 0xFF) == 16 ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
300 if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
301 ++data;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
302 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
303 for ( i=cvt->len_cvt/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
304 *data ^= 0x80;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
305 data += 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
306 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
307 } else {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
308 for ( i=cvt->len_cvt; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
309 *data++ ^= 0x80;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
310 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
311 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
312 format = (format ^ 0x8000);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
313 if ( cvt->filters[++cvt->filter_index] ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
314 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
315 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
316 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
317
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
318 /* Toggle endianness */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
319 void SDL_ConvertEndian(SDL_AudioCVT *cvt, Uint16 format)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
320 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
321 int i;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
322 Uint8 *data, tmp;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
323
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
324 #ifdef DEBUG_CONVERT
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
325 fprintf(stderr, "Converting audio endianness\n");
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
326 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
327 data = cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
328 for ( i=cvt->len_cvt/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
329 tmp = data[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
330 data[0] = data[1];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
331 data[1] = tmp;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
332 data += 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
333 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
334 format = (format ^ 0x1000);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
335 if ( cvt->filters[++cvt->filter_index] ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
336 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
337 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
338 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
339
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
340 /* Convert rate up by multiple of 2 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
341 void SDL_RateMUL2(SDL_AudioCVT *cvt, Uint16 format)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
342 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
343 int i;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
344 Uint8 *src, *dst;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
345
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
346 #ifdef DEBUG_CONVERT
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
347 fprintf(stderr, "Converting audio rate * 2\n");
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
348 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
349 src = cvt->buf+cvt->len_cvt;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
350 dst = cvt->buf+cvt->len_cvt*2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
351 switch (format & 0xFF) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
352 case 8:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
353 for ( i=cvt->len_cvt; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
354 src -= 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
355 dst -= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
356 dst[0] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
357 dst[1] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
358 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
359 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
360 case 16:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
361 for ( i=cvt->len_cvt/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
362 src -= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
363 dst -= 4;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
364 dst[0] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
365 dst[1] = src[1];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
366 dst[2] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
367 dst[3] = src[1];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
368 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
369 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
370 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
371 cvt->len_cvt *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
372 if ( cvt->filters[++cvt->filter_index] ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
373 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
374 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
375 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
376
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
377 /* Convert rate down by multiple of 2 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
378 void SDL_RateDIV2(SDL_AudioCVT *cvt, Uint16 format)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
379 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
380 int i;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
381 Uint8 *src, *dst;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
382
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
383 #ifdef DEBUG_CONVERT
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
384 fprintf(stderr, "Converting audio rate / 2\n");
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
385 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
386 src = cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
387 dst = cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
388 switch (format & 0xFF) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
389 case 8:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
390 for ( i=cvt->len_cvt/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
391 dst[0] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
392 src += 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
393 dst += 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
394 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
395 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
396 case 16:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
397 for ( i=cvt->len_cvt/4; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
398 dst[0] = src[0];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
399 dst[1] = src[1];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
400 src += 4;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
401 dst += 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
402 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
403 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
404 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
405 cvt->len_cvt /= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
406 if ( cvt->filters[++cvt->filter_index] ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
407 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
408 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
409 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
410
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
411 /* Very slow rate conversion routine */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
412 void SDL_RateSLOW(SDL_AudioCVT *cvt, Uint16 format)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
413 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
414 double ipos;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
415 int i, clen;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
416
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
417 #ifdef DEBUG_CONVERT
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
418 fprintf(stderr, "Converting audio rate * %4.4f\n", 1.0/cvt->rate_incr);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
419 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
420 clen = (int)((double)cvt->len_cvt / cvt->rate_incr);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
421 if ( cvt->rate_incr > 1.0 ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
422 switch (format & 0xFF) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
423 case 8: {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
424 Uint8 *output;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
425
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
426 output = cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
427 ipos = 0.0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
428 for ( i=clen; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
429 *output = cvt->buf[(int)ipos];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
430 ipos += cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
431 output += 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
432 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
433 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
434 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
435
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
436 case 16: {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
437 Uint16 *output;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
438
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
439 clen &= ~1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
440 output = (Uint16 *)cvt->buf;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
441 ipos = 0.0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
442 for ( i=clen/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
443 *output=((Uint16 *)cvt->buf)[(int)ipos];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
444 ipos += cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
445 output += 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
446 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
447 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
448 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
449 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
450 } else {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
451 switch (format & 0xFF) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
452 case 8: {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
453 Uint8 *output;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
454
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
455 output = cvt->buf+clen;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
456 ipos = (double)cvt->len_cvt;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
457 for ( i=clen; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
458 ipos -= cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
459 output -= 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
460 *output = cvt->buf[(int)ipos];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
461 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
462 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
463 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
464
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
465 case 16: {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
466 Uint16 *output;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
467
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
468 clen &= ~1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
469 output = (Uint16 *)(cvt->buf+clen);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
470 ipos = (double)cvt->len_cvt/2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
471 for ( i=clen/2; i; --i ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
472 ipos -= cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
473 output -= 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
474 *output=((Uint16 *)cvt->buf)[(int)ipos];
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
475 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
476 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
477 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
478 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
479 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
480 cvt->len_cvt = clen;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
481 if ( cvt->filters[++cvt->filter_index] ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
482 cvt->filters[cvt->filter_index](cvt, format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
483 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
484 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
485
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
486 int SDL_ConvertAudio(SDL_AudioCVT *cvt)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
487 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
488 /* Make sure there's data to convert */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
489 if ( cvt->buf == NULL ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
490 SDL_SetError("No buffer allocated for conversion");
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
491 return(-1);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
492 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
493 /* Return okay if no conversion is necessary */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
494 cvt->len_cvt = cvt->len;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
495 if ( cvt->filters[0] == NULL ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
496 return(0);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
497 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
498
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
499 /* Set up the conversion and go! */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
500 cvt->filter_index = 0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
501 cvt->filters[0](cvt, cvt->src_format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
502 return(0);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
503 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
504
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
505 /* Creates a set of audio filters to convert from one format to another.
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
506 Returns -1 if the format conversion is not supported, or 1 if the
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
507 audio filter is set up.
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
508 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
509
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
510 int SDL_BuildAudioCVT(SDL_AudioCVT *cvt,
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
511 Uint16 src_format, Uint8 src_channels, int src_rate,
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
512 Uint16 dst_format, Uint8 dst_channels, int dst_rate)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
513 {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
514 /* Start off with no conversion necessary */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
515 cvt->needed = 0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
516 cvt->filter_index = 0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
517 cvt->filters[0] = NULL;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
518 cvt->len_mult = 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
519 cvt->len_ratio = 1.0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
520
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
521 /* First filter: Endian conversion from src to dst */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
522 if ( (src_format & 0x1000) != (dst_format & 0x1000)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
523 && ((src_format & 0xff) != 8) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
524 cvt->filters[cvt->filter_index++] = SDL_ConvertEndian;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
525 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
526
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
527 /* Second filter: Sign conversion -- signed/unsigned */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
528 if ( (src_format & 0x8000) != (dst_format & 0x8000) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
529 cvt->filters[cvt->filter_index++] = SDL_ConvertSign;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
530 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
531
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
532 /* Next filter: Convert 16 bit <--> 8 bit PCM */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
533 if ( (src_format & 0xFF) != (dst_format & 0xFF) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
534 switch (dst_format&0x10FF) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
535 case AUDIO_U8:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
536 cvt->filters[cvt->filter_index++] =
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
537 SDL_Convert8;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
538 cvt->len_ratio /= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
539 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
540 case AUDIO_U16LSB:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
541 cvt->filters[cvt->filter_index++] =
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
542 SDL_Convert16LSB;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
543 cvt->len_mult *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
544 cvt->len_ratio *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
545 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
546 case AUDIO_U16MSB:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
547 cvt->filters[cvt->filter_index++] =
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
548 SDL_Convert16MSB;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
549 cvt->len_mult *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
550 cvt->len_ratio *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
551 break;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
552 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
553 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
554
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
555 /* Last filter: Mono/Stereo conversion */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
556 if ( src_channels != dst_channels ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
557 while ( (src_channels*2) <= dst_channels ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
558 cvt->filters[cvt->filter_index++] =
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
559 SDL_ConvertStereo;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
560 cvt->len_mult *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
561 src_channels *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
562 cvt->len_ratio *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
563 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
564 /* This assumes that 4 channel audio is in the format:
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
565 Left {front/back} + Right {front/back}
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
566 so converting to L/R stereo works properly.
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
567 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
568 while ( ((src_channels%2) == 0) &&
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
569 ((src_channels/2) >= dst_channels) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
570 cvt->filters[cvt->filter_index++] =
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
571 SDL_ConvertMono;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
572 src_channels /= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
573 cvt->len_ratio /= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
574 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
575 if ( src_channels != dst_channels ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
576 /* Uh oh.. */;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
577 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
578 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
579
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
580 /* Do rate conversion */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
581 cvt->rate_incr = 0.0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
582 if ( (src_rate/100) != (dst_rate/100) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
583 Uint32 hi_rate, lo_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
584 int len_mult;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
585 double len_ratio;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
586 void (*rate_cvt)(SDL_AudioCVT *cvt, Uint16 format);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
587
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
588 if ( src_rate > dst_rate ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
589 hi_rate = src_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
590 lo_rate = dst_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
591 rate_cvt = SDL_RateDIV2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
592 len_mult = 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
593 len_ratio = 0.5;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
594 } else {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
595 hi_rate = dst_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
596 lo_rate = src_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
597 rate_cvt = SDL_RateMUL2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
598 len_mult = 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
599 len_ratio = 2.0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
600 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
601 /* If hi_rate = lo_rate*2^x then conversion is easy */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
602 while ( ((lo_rate*2)/100) <= (hi_rate/100) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
603 cvt->filters[cvt->filter_index++] = rate_cvt;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
604 cvt->len_mult *= len_mult;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
605 lo_rate *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
606 cvt->len_ratio *= len_ratio;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
607 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
608 /* We may need a slow conversion here to finish up */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
609 if ( (lo_rate/100) != (hi_rate/100) ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
610 #if 1
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
611 /* The problem with this is that if the input buffer is
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
612 say 1K, and the conversion rate is say 1.1, then the
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
613 output buffer is 1.1K, which may not be an acceptable
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
614 buffer size for the audio driver (not a power of 2)
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
615 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
616 /* For now, punt and hope the rate distortion isn't great.
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
617 */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
618 #else
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
619 if ( src_rate < dst_rate ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
620 cvt->rate_incr = (double)lo_rate/hi_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
621 cvt->len_mult *= 2;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
622 cvt->len_ratio /= cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
623 } else {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
624 cvt->rate_incr = (double)hi_rate/lo_rate;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
625 cvt->len_ratio *= cvt->rate_incr;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
626 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
627 cvt->filters[cvt->filter_index++] = SDL_RateSLOW;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
628 #endif
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
629 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
630 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
631
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
632 /* Set up the filter information */
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
633 if ( cvt->filter_index != 0 ) {
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
634 cvt->needed = 1;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
635 cvt->src_format = src_format;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
636 cvt->dst_format = dst_format;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
637 cvt->len = 0;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
638 cvt->buf = NULL;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
639 cvt->filters[cvt->filter_index] = NULL;
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
640 }
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
641 return(cvt->needed);
74212992fb08 Initial revision
Sam Lantinga <slouken@lokigames.com>
parents:
diff changeset
642 }