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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
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20 slouken@devolution.com
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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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176 }
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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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232 }
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233 format = ((format & ~0x0008) | AUDIO_U16LSB);
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234 cvt->len_cvt *= 2;
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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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238 }
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239 /* Convert 8-bit to 16-bit - MSB */
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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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243 Uint8 *src, *dst;
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244
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245 #ifdef DEBUG_CONVERT
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246 fprintf(stderr, "Converting to 16-bit MSB\n");
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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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250 for ( i=cvt->len_cvt; i; --i ) {
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251 src -= 1;
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252 dst -= 2;
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253 dst[0] = *src;
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254 dst[1] = 0;
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255 }
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256 format = ((format & ~0x0008) | AUDIO_U16MSB);
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257 cvt->len_cvt *= 2;
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258 if ( cvt->filters[++cvt->filter_index] ) {
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259 cvt->filters[cvt->filter_index](cvt, format);
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260 }
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261 }
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262
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263 /* Convert 16-bit to 8-bit */
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264 void SDL_Convert8(SDL_AudioCVT *cvt, Uint16 format)
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265 {
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266 int i;
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267 Uint8 *src, *dst;
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268
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269 #ifdef DEBUG_CONVERT
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270 fprintf(stderr, "Converting to 8-bit\n");
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271 #endif
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272 src = cvt->buf;
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273 dst = cvt->buf;
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274 if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
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275 ++src;
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276 }
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277 for ( i=cvt->len_cvt/2; i; --i ) {
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278 *dst = *src;
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279 src += 2;
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280 dst += 1;
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281 }
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282 format = ((format & ~0x9010) | AUDIO_U8);
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283 cvt->len_cvt /= 2;
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284 if ( cvt->filters[++cvt->filter_index] ) {
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285 cvt->filters[cvt->filter_index](cvt, format);
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286 }
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287 }
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288
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289 /* Toggle signed/unsigned */
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290 void SDL_ConvertSign(SDL_AudioCVT *cvt, Uint16 format)
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291 {
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292 int i;
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293 Uint8 *data;
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294
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295 #ifdef DEBUG_CONVERT
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296 fprintf(stderr, "Converting audio signedness\n");
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297 #endif
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298 data = cvt->buf;
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299 if ( (format & 0xFF) == 16 ) {
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300 if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
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301 ++data;
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302 }
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303 for ( i=cvt->len_cvt/2; i; --i ) {
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304 *data ^= 0x80;
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305 data += 2;
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306 }
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307 } else {
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308 for ( i=cvt->len_cvt; i; --i ) {
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309 *data++ ^= 0x80;
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310 }
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311 }
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312 format = (format ^ 0x8000);
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313 if ( cvt->filters[++cvt->filter_index] ) {
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314 cvt->filters[cvt->filter_index](cvt, format);
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315 }
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316 }
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317
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318 /* Toggle endianness */
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319 void SDL_ConvertEndian(SDL_AudioCVT *cvt, Uint16 format)
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320 {
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321 int i;
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322 Uint8 *data, tmp;
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323
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324 #ifdef DEBUG_CONVERT
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325 fprintf(stderr, "Converting audio endianness\n");
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326 #endif
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327 data = cvt->buf;
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328 for ( i=cvt->len_cvt/2; i; --i ) {
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329 tmp = data[0];
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330 data[0] = data[1];
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331 data[1] = tmp;
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332 data += 2;
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333 }
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334 format = (format ^ 0x1000);
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335 if ( cvt->filters[++cvt->filter_index] ) {
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336 cvt->filters[cvt->filter_index](cvt, format);
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337 }
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338 }
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339
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340 /* Convert rate up by multiple of 2 */
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341 void SDL_RateMUL2(SDL_AudioCVT *cvt, Uint16 format)
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342 {
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343 int i;
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344 Uint8 *src, *dst;
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345
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346 #ifdef DEBUG_CONVERT
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347 fprintf(stderr, "Converting audio rate * 2\n");
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348 #endif
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349 src = cvt->buf+cvt->len_cvt;
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350 dst = cvt->buf+cvt->len_cvt*2;
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351 switch (format & 0xFF) {
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352 case 8:
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353 for ( i=cvt->len_cvt; i; --i ) {
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354 src -= 1;
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355 dst -= 2;
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356 dst[0] = src[0];
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357 dst[1] = src[0];
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358 }
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359 break;
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360 case 16:
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361 for ( i=cvt->len_cvt/2; i; --i ) {
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362 src -= 2;
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363 dst -= 4;
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364 dst[0] = src[0];
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365 dst[1] = src[1];
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366 dst[2] = src[0];
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367 dst[3] = src[1];
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368 }
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369 break;
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370 }
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371 cvt->len_cvt *= 2;
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372 if ( cvt->filters[++cvt->filter_index] ) {
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373 cvt->filters[cvt->filter_index](cvt, format);
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374 }
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375 }
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376
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377 /* Convert rate down by multiple of 2 */
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378 void SDL_RateDIV2(SDL_AudioCVT *cvt, Uint16 format)
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379 {
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380 int i;
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381 Uint8 *src, *dst;
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382
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383 #ifdef DEBUG_CONVERT
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384 fprintf(stderr, "Converting audio rate / 2\n");
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385 #endif
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386 src = cvt->buf;
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387 dst = cvt->buf;
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388 switch (format & 0xFF) {
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389 case 8:
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390 for ( i=cvt->len_cvt/2; i; --i ) {
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391 dst[0] = src[0];
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392 src += 2;
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393 dst += 1;
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394 }
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395 break;
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396 case 16:
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397 for ( i=cvt->len_cvt/4; i; --i ) {
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398 dst[0] = src[0];
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399 dst[1] = src[1];
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400 src += 4;
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401 dst += 2;
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402 }
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403 break;
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404 }
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405 cvt->len_cvt /= 2;
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406 if ( cvt->filters[++cvt->filter_index] ) {
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407 cvt->filters[cvt->filter_index](cvt, format);
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408 }
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409 }
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410
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411 /* Very slow rate conversion routine */
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412 void SDL_RateSLOW(SDL_AudioCVT *cvt, Uint16 format)
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413 {
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414 double ipos;
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415 int i, clen;
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416
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417 #ifdef DEBUG_CONVERT
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418 fprintf(stderr, "Converting audio rate * %4.4f\n", 1.0/cvt->rate_incr);
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419 #endif
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420 clen = (int)((double)cvt->len_cvt / cvt->rate_incr);
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421 if ( cvt->rate_incr > 1.0 ) {
|
|
|
422 switch (format & 0xFF) {
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|
|
423 case 8: {
|
|
|
424 Uint8 *output;
|
|
|
425
|
|
|
426 output = cvt->buf;
|
|
|
427 ipos = 0.0;
|
|
|
428 for ( i=clen; i; --i ) {
|
|
|
429 *output = cvt->buf[(int)ipos];
|
|
|
430 ipos += cvt->rate_incr;
|
|
|
431 output += 1;
|
|
|
432 }
|
|
|
433 }
|
|
|
434 break;
|
|
|
435
|
|
|
436 case 16: {
|
|
|
437 Uint16 *output;
|
|
|
438
|
|
|
439 clen &= ~1;
|
|
|
440 output = (Uint16 *)cvt->buf;
|
|
|
441 ipos = 0.0;
|
|
|
442 for ( i=clen/2; i; --i ) {
|
|
|
443 *output=((Uint16 *)cvt->buf)[(int)ipos];
|
|
|
444 ipos += cvt->rate_incr;
|
|
|
445 output += 1;
|
|
|
446 }
|
|
|
447 }
|
|
|
448 break;
|
|
|
449 }
|
|
|
450 } else {
|
|
|
451 switch (format & 0xFF) {
|
|
|
452 case 8: {
|
|
|
453 Uint8 *output;
|
|
|
454
|
|
|
455 output = cvt->buf+clen;
|
|
|
456 ipos = (double)cvt->len_cvt;
|
|
|
457 for ( i=clen; i; --i ) {
|
|
|
458 ipos -= cvt->rate_incr;
|
|
|
459 output -= 1;
|
|
|
460 *output = cvt->buf[(int)ipos];
|
|
|
461 }
|
|
|
462 }
|
|
|
463 break;
|
|
|
464
|
|
|
465 case 16: {
|
|
|
466 Uint16 *output;
|
|
|
467
|
|
|
468 clen &= ~1;
|
|
|
469 output = (Uint16 *)(cvt->buf+clen);
|
|
|
470 ipos = (double)cvt->len_cvt/2;
|
|
|
471 for ( i=clen/2; i; --i ) {
|
|
|
472 ipos -= cvt->rate_incr;
|
|
|
473 output -= 1;
|
|
|
474 *output=((Uint16 *)cvt->buf)[(int)ipos];
|
|
|
475 }
|
|
|
476 }
|
|
|
477 break;
|
|
|
478 }
|
|
|
479 }
|
|
|
480 cvt->len_cvt = clen;
|
|
|
481 if ( cvt->filters[++cvt->filter_index] ) {
|
|
|
482 cvt->filters[cvt->filter_index](cvt, format);
|
|
|
483 }
|
|
|
484 }
|
|
|
485
|
|
|
486 int SDL_ConvertAudio(SDL_AudioCVT *cvt)
|
|
|
487 {
|
|
|
488 /* Make sure there's data to convert */
|
|
|
489 if ( cvt->buf == NULL ) {
|
|
|
490 SDL_SetError("No buffer allocated for conversion");
|
|
|
491 return(-1);
|
|
|
492 }
|
|
|
493 /* Return okay if no conversion is necessary */
|
|
|
494 cvt->len_cvt = cvt->len;
|
|
|
495 if ( cvt->filters[0] == NULL ) {
|
|
|
496 return(0);
|
|
|
497 }
|
|
|
498
|
|
|
499 /* Set up the conversion and go! */
|
|
|
500 cvt->filter_index = 0;
|
|
|
501 cvt->filters[0](cvt, cvt->src_format);
|
|
|
502 return(0);
|
|
|
503 }
|
|
|
504
|
|
|
505 /* Creates a set of audio filters to convert from one format to another.
|
|
|
506 Returns -1 if the format conversion is not supported, or 1 if the
|
|
|
507 audio filter is set up.
|
|
|
508 */
|
|
|
509
|
|
|
510 int SDL_BuildAudioCVT(SDL_AudioCVT *cvt,
|
|
|
511 Uint16 src_format, Uint8 src_channels, int src_rate,
|
|
|
512 Uint16 dst_format, Uint8 dst_channels, int dst_rate)
|
|
|
513 {
|
|
|
514 /* Start off with no conversion necessary */
|
|
|
515 cvt->needed = 0;
|
|
|
516 cvt->filter_index = 0;
|
|
|
517 cvt->filters[0] = NULL;
|
|
|
518 cvt->len_mult = 1;
|
|
|
519 cvt->len_ratio = 1.0;
|
|
|
520
|
|
|
521 /* First filter: Endian conversion from src to dst */
|
|
|
522 if ( (src_format & 0x1000) != (dst_format & 0x1000)
|
|
|
523 && ((src_format & 0xff) != 8) ) {
|
|
|
524 cvt->filters[cvt->filter_index++] = SDL_ConvertEndian;
|
|
|
525 }
|
|
|
526
|
|
|
527 /* Second filter: Sign conversion -- signed/unsigned */
|
|
|
528 if ( (src_format & 0x8000) != (dst_format & 0x8000) ) {
|
|
|
529 cvt->filters[cvt->filter_index++] = SDL_ConvertSign;
|
|
|
530 }
|
|
|
531
|
|
|
532 /* Next filter: Convert 16 bit <--> 8 bit PCM */
|
|
|
533 if ( (src_format & 0xFF) != (dst_format & 0xFF) ) {
|
|
|
534 switch (dst_format&0x10FF) {
|
|
|
535 case AUDIO_U8:
|
|
|
536 cvt->filters[cvt->filter_index++] =
|
|
|
537 SDL_Convert8;
|
|
|
538 cvt->len_ratio /= 2;
|
|
|
539 break;
|
|
|
540 case AUDIO_U16LSB:
|
|
|
541 cvt->filters[cvt->filter_index++] =
|
|
|
542 SDL_Convert16LSB;
|
|
|
543 cvt->len_mult *= 2;
|
|
|
544 cvt->len_ratio *= 2;
|
|
|
545 break;
|
|
|
546 case AUDIO_U16MSB:
|
|
|
547 cvt->filters[cvt->filter_index++] =
|
|
|
548 SDL_Convert16MSB;
|
|
|
549 cvt->len_mult *= 2;
|
|
|
550 cvt->len_ratio *= 2;
|
|
|
551 break;
|
|
|
552 }
|
|
|
553 }
|
|
|
554
|
|
|
555 /* Last filter: Mono/Stereo conversion */
|
|
|
556 if ( src_channels != dst_channels ) {
|
|
|
557 while ( (src_channels*2) <= dst_channels ) {
|
|
|
558 cvt->filters[cvt->filter_index++] =
|
|
|
559 SDL_ConvertStereo;
|
|
|
560 cvt->len_mult *= 2;
|
|
|
561 src_channels *= 2;
|
|
|
562 cvt->len_ratio *= 2;
|
|
|
563 }
|
|
|
564 /* This assumes that 4 channel audio is in the format:
|
|
|
565 Left {front/back} + Right {front/back}
|
|
|
566 so converting to L/R stereo works properly.
|
|
|
567 */
|
|
|
568 while ( ((src_channels%2) == 0) &&
|
|
|
569 ((src_channels/2) >= dst_channels) ) {
|
|
|
570 cvt->filters[cvt->filter_index++] =
|
|
|
571 SDL_ConvertMono;
|
|
|
572 src_channels /= 2;
|
|
|
573 cvt->len_ratio /= 2;
|
|
|
574 }
|
|
|
575 if ( src_channels != dst_channels ) {
|
|
|
576 /* Uh oh.. */;
|
|
|
577 }
|
|
|
578 }
|
|
|
579
|
|
|
580 /* Do rate conversion */
|
|
|
581 cvt->rate_incr = 0.0;
|
|
|
582 if ( (src_rate/100) != (dst_rate/100) ) {
|
|
|
583 Uint32 hi_rate, lo_rate;
|
|
|
584 int len_mult;
|
|
|
585 double len_ratio;
|
|
|
586 void (*rate_cvt)(SDL_AudioCVT *cvt, Uint16 format);
|
|
|
587
|
|
|
588 if ( src_rate > dst_rate ) {
|
|
|
589 hi_rate = src_rate;
|
|
|
590 lo_rate = dst_rate;
|
|
|
591 rate_cvt = SDL_RateDIV2;
|
|
|
592 len_mult = 1;
|
|
|
593 len_ratio = 0.5;
|
|
|
594 } else {
|
|
|
595 hi_rate = dst_rate;
|
|
|
596 lo_rate = src_rate;
|
|
|
597 rate_cvt = SDL_RateMUL2;
|
|
|
598 len_mult = 2;
|
|
|
599 len_ratio = 2.0;
|
|
|
600 }
|
|
|
601 /* If hi_rate = lo_rate*2^x then conversion is easy */
|
|
|
602 while ( ((lo_rate*2)/100) <= (hi_rate/100) ) {
|
|
|
603 cvt->filters[cvt->filter_index++] = rate_cvt;
|
|
|
604 cvt->len_mult *= len_mult;
|
|
|
605 lo_rate *= 2;
|
|
|
606 cvt->len_ratio *= len_ratio;
|
|
|
607 }
|
|
|
608 /* We may need a slow conversion here to finish up */
|
|
|
609 if ( (lo_rate/100) != (hi_rate/100) ) {
|
|
|
610 #if 1
|
|
|
611 /* The problem with this is that if the input buffer is
|
|
|
612 say 1K, and the conversion rate is say 1.1, then the
|
|
|
613 output buffer is 1.1K, which may not be an acceptable
|
|
|
614 buffer size for the audio driver (not a power of 2)
|
|
|
615 */
|
|
|
616 /* For now, punt and hope the rate distortion isn't great.
|
|
|
617 */
|
|
|
618 #else
|
|
|
619 if ( src_rate < dst_rate ) {
|
|
|
620 cvt->rate_incr = (double)lo_rate/hi_rate;
|
|
|
621 cvt->len_mult *= 2;
|
|
|
622 cvt->len_ratio /= cvt->rate_incr;
|
|
|
623 } else {
|
|
|
624 cvt->rate_incr = (double)hi_rate/lo_rate;
|
|
|
625 cvt->len_ratio *= cvt->rate_incr;
|
|
|
626 }
|
|
|
627 cvt->filters[cvt->filter_index++] = SDL_RateSLOW;
|
|
|
628 #endif
|
|
|
629 }
|
|
|
630 }
|
|
|
631
|
|
|
632 /* Set up the filter information */
|
|
|
633 if ( cvt->filter_index != 0 ) {
|
|
|
634 cvt->needed = 1;
|
|
|
635 cvt->src_format = src_format;
|
|
|
636 cvt->dst_format = dst_format;
|
|
|
637 cvt->len = 0;
|
|
|
638 cvt->buf = NULL;
|
|
|
639 cvt->filters[cvt->filter_index] = NULL;
|
|
|
640 }
|
|
|
641 return(cvt->needed);
|
|
|
642 }
|
