Mercurial > sdl-ios-xcode
annotate docs/html/sdlconvertaudio.html @ 181:e5bc29de3f0a
Updated from the SDL Documentation Project
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Fri, 14 Sep 2001 02:41:09 +0000 |
| parents | 55f1f1b3e27d |
| children | 355632dca928 |
| rev | line source |
|---|---|
| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_ConvertAudio</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
|
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.64 |
| 0 | 8 "><LINK |
| 9 REL="HOME" | |
| 10 TITLE="SDL Library Documentation" | |
| 11 HREF="index.html"><LINK | |
| 12 REL="UP" | |
| 13 TITLE="Audio" | |
| 14 HREF="audio.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_BuildAudioCVT" | |
| 17 HREF="sdlbuildaudiocvt.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_MixAudio" | |
| 20 HREF="sdlmixaudio.html"></HEAD | |
| 21 ><BODY | |
| 22 CLASS="REFENTRY" | |
| 23 BGCOLOR="#FFF8DC" | |
| 24 TEXT="#000000" | |
| 25 LINK="#0000ee" | |
| 26 VLINK="#551a8b" | |
| 27 ALINK="#ff0000" | |
| 28 ><DIV | |
| 29 CLASS="NAVHEADER" | |
| 30 ><TABLE | |
| 31 WIDTH="100%" | |
| 32 BORDER="0" | |
| 33 CELLPADDING="0" | |
| 34 CELLSPACING="0" | |
| 35 ><TR | |
| 36 ><TH | |
| 37 COLSPAN="3" | |
| 38 ALIGN="center" | |
| 39 >SDL Library Documentation</TH | |
| 40 ></TR | |
| 41 ><TR | |
| 42 ><TD | |
| 43 WIDTH="10%" | |
| 44 ALIGN="left" | |
| 45 VALIGN="bottom" | |
| 46 ><A | |
| 47 HREF="sdlbuildaudiocvt.html" | |
| 48 >Prev</A | |
| 49 ></TD | |
| 50 ><TD | |
| 51 WIDTH="80%" | |
| 52 ALIGN="center" | |
| 53 VALIGN="bottom" | |
| 54 ></TD | |
| 55 ><TD | |
| 56 WIDTH="10%" | |
| 57 ALIGN="right" | |
| 58 VALIGN="bottom" | |
| 59 ><A | |
| 60 HREF="sdlmixaudio.html" | |
| 61 >Next</A | |
| 62 ></TD | |
| 63 ></TR | |
| 64 ></TABLE | |
| 65 ><HR | |
| 66 ALIGN="LEFT" | |
| 67 WIDTH="100%"></DIV | |
| 68 ><H1 | |
| 69 ><A | |
| 70 NAME="SDLCONVERTAUDIO" | |
| 71 >SDL_ConvertAudio</A | |
| 72 ></H1 | |
| 73 ><DIV | |
| 74 CLASS="REFNAMEDIV" | |
| 75 ><A | |
|
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76 NAME="AEN6660" |
| 0 | 77 ></A |
| 78 ><H2 | |
| 79 >Name</H2 | |
| 80 >SDL_ConvertAudio -- Convert audio data to a desired audio format.</DIV | |
| 81 ><DIV | |
| 82 CLASS="REFSYNOPSISDIV" | |
| 83 ><A | |
|
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84 NAME="AEN6663" |
| 0 | 85 ></A |
| 86 ><H2 | |
| 87 >Synopsis</H2 | |
| 88 ><DIV | |
| 89 CLASS="FUNCSYNOPSIS" | |
| 90 ><A | |
|
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91 NAME="AEN6664" |
| 0 | 92 ></A |
| 93 ><P | |
| 94 ></P | |
| 95 ><PRE | |
| 96 CLASS="FUNCSYNOPSISINFO" | |
| 97 >#include "SDL.h"</PRE | |
| 98 ><P | |
| 99 ><CODE | |
| 100 ><CODE | |
| 101 CLASS="FUNCDEF" | |
| 102 >int <B | |
| 103 CLASS="FSFUNC" | |
| 104 >SDL_ConvertAudio</B | |
| 105 ></CODE | |
| 106 >(SDL_AudioCVT *cvt);</CODE | |
| 107 ></P | |
| 108 ><P | |
| 109 ></P | |
| 110 ></DIV | |
| 111 ></DIV | |
| 112 ><DIV | |
| 113 CLASS="REFSECT1" | |
| 114 ><A | |
|
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115 NAME="AEN6670" |
| 0 | 116 ></A |
| 117 ><H2 | |
| 118 >Description</H2 | |
| 119 ><P | |
| 120 ><TT | |
| 121 CLASS="FUNCTION" | |
| 122 >SDL_ConvertAudio</TT | |
| 123 > takes one parameter, <TT | |
| 124 CLASS="PARAMETER" | |
| 125 ><I | |
| 126 >cvt</I | |
| 127 ></TT | |
| 128 >, which was previously initilized. Initilizing a <A | |
| 129 HREF="sdlaudiocvt.html" | |
| 130 ><SPAN | |
| 131 CLASS="STRUCTNAME" | |
| 132 >SDL_AudioCVT</SPAN | |
| 133 ></A | |
| 134 > is a two step process. First of all, the structure must be passed to <A | |
| 135 HREF="sdlbuildaudiocvt.html" | |
| 136 ><TT | |
| 137 CLASS="FUNCTION" | |
| 138 >SDL_BuildAudioCVT</TT | |
| 139 ></A | |
| 140 > along with source and destination format parameters. Secondly, the <SPAN | |
| 141 CLASS="STRUCTNAME" | |
| 142 >cvt</SPAN | |
| 143 >-><TT | |
| 144 CLASS="STRUCTFIELD" | |
| 145 ><I | |
| 146 >buf</I | |
| 147 ></TT | |
| 148 > and <SPAN | |
| 149 CLASS="STRUCTNAME" | |
| 150 >cvt</SPAN | |
| 151 >-><TT | |
| 152 CLASS="STRUCTFIELD" | |
| 153 ><I | |
| 154 >len</I | |
| 155 ></TT | |
| 156 > fields must be setup. <SPAN | |
| 157 CLASS="STRUCTNAME" | |
| 158 >cvt</SPAN | |
| 159 >-><TT | |
| 160 CLASS="STRUCTFIELD" | |
| 161 ><I | |
| 162 >buf</I | |
| 163 ></TT | |
| 164 > should point to the audio data and <SPAN | |
| 165 CLASS="STRUCTNAME" | |
| 166 >cvt</SPAN | |
| 167 >-><TT | |
| 168 CLASS="STRUCTFIELD" | |
| 169 ><I | |
| 170 >len</I | |
| 171 ></TT | |
| 172 > should be set to the length of the audio data in bytes. Remember, the length of the buffer pointed to by <TT | |
| 173 CLASS="STRUCTFIELD" | |
| 174 ><I | |
| 175 >buf</I | |
| 176 ></TT | |
| 177 > show be <TT | |
| 178 CLASS="STRUCTFIELD" | |
| 179 ><I | |
| 180 >len</I | |
| 181 ></TT | |
| 182 >*<TT | |
| 183 CLASS="STRUCTFIELD" | |
| 184 ><I | |
| 185 >len_mult</I | |
| 186 ></TT | |
| 187 > bytes in length.</P | |
| 188 ><P | |
| 189 >Once the <SPAN | |
| 190 CLASS="STRUCTNAME" | |
| 191 >SDL_AudioCVT</SPAN | |
| 192 >structure is initilized then we can pass it to <TT | |
| 193 CLASS="FUNCTION" | |
| 194 >SDL_ConvertAudio</TT | |
| 195 >, which will convert the audio data pointer to by <SPAN | |
| 196 CLASS="STRUCTNAME" | |
| 197 >cvt</SPAN | |
| 198 >-><TT | |
| 199 CLASS="STRUCTFIELD" | |
| 200 ><I | |
| 201 >buf</I | |
| 202 ></TT | |
| 203 >. If <TT | |
| 204 CLASS="FUNCTION" | |
| 205 >SDL_ConvertAudio</TT | |
| 206 > returned <SPAN | |
| 207 CLASS="RETURNVALUE" | |
| 208 >0</SPAN | |
| 209 > then the conversion was completed successfully, otherwise <SPAN | |
| 210 CLASS="RETURNVALUE" | |
| 211 >-1</SPAN | |
| 212 > is returned.</P | |
| 213 ><P | |
| 214 >If the conversion completed successfully then the converted audio data can be read from <SPAN | |
| 215 CLASS="STRUCTNAME" | |
| 216 >cvt</SPAN | |
| 217 >-><TT | |
| 218 CLASS="STRUCTFIELD" | |
| 219 ><I | |
| 220 >buf</I | |
| 221 ></TT | |
| 222 >. The amount of valid, converted, audio data in the buffer is equal to <SPAN | |
| 223 CLASS="STRUCTNAME" | |
| 224 >cvt</SPAN | |
| 225 >-><TT | |
| 226 CLASS="STRUCTFIELD" | |
| 227 ><I | |
| 228 >len</I | |
| 229 ></TT | |
| 230 >*<TT | |
| 231 CLASS="STRUCTFIELD" | |
| 232 ><I | |
| 233 >cvt</I | |
| 234 ></TT | |
| 235 >-><SPAN | |
| 236 CLASS="STRUCTNAME" | |
| 237 >len_ratio</SPAN | |
| 238 >.</P | |
| 239 ></DIV | |
| 240 ><DIV | |
| 241 CLASS="REFSECT1" | |
| 242 ><A | |
|
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243 NAME="AEN6705" |
| 0 | 244 ></A |
| 245 ><H2 | |
| 246 >Examples</H2 | |
| 247 ><PRE | |
| 248 CLASS="PROGRAMLISTING" | |
| 249 >/* Converting some WAV data to hardware format */ | |
| 250 void my_audio_callback(void *userdata, Uint8 *stream, int len); | |
| 251 | |
| 252 SDL_AudioSpec *desired, *obtained; | |
| 253 SDL_AudioSpec wav_spec; | |
| 254 SDL_AudioCVT wav_cvt; | |
| 255 Uint32 wav_len; | |
| 256 Uint8 *wav_buf; | |
| 257 int ret; | |
| 258 | |
| 259 /* Allocated audio specs */ | |
| 260 desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
| 261 obtained=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
| 262 | |
| 263 /* Set desired format */ | |
| 264 desired->freq=22050; | |
| 265 desired->format=AUDIO_S16LSB; | |
| 266 desired->samples=8192; | |
| 267 desired->callback=my_audio_callback; | |
| 268 desired->userdata=NULL; | |
| 269 | |
| 270 /* Open the audio device */ | |
| 271 if ( SDL_OpenAudio(desired, obtained) < 0 ){ | |
| 272 fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError()); | |
| 273 exit(-1); | |
| 274 } | |
| 275 | |
| 276 free(desired); | |
| 277 | |
| 278 /* Load the test.wav */ | |
| 279 if( SDL_LoadWAV("test.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){ | |
| 280 fprintf(stderr, "Could not open test.wav: %s\n", SDL_GetError()); | |
| 281 SDL_CloseAudio(); | |
| 282 free(obtained); | |
| 283 exit(-1); | |
| 284 } | |
| 285 | |
| 286 /* Build AudioCVT */ | |
| 287 ret = SDL_BuildAudioCVT(&wav_cvt, | |
| 288 wav_spec.format, wav_spec.channels, wav_spec.freq, | |
| 289 obtained->format, obtained->channels, obtained->freq); | |
| 290 | |
| 291 /* Check that the convert was built */ | |
| 292 if(ret==-1){ | |
| 293 fprintf(stderr, "Couldn't build converter!\n"); | |
| 294 SDL_CloseAudio(); | |
| 295 free(obtained); | |
| 296 SDL_FreeWAV(wav_buf); | |
| 297 } | |
| 298 | |
| 299 /* Setup for conversion */ | |
| 300 wav_cvt.buf=(Uint8 *)malloc(wav_len*wav_cvt.len_mult); | |
| 301 wav_cvt.len=wav_len; | |
| 302 memcpy(wav_cvt.buf, wav_buf, wav_len); | |
| 303 | |
| 304 /* We can delete to original WAV data now */ | |
| 305 SDL_FreeWAV(wav_buf); | |
| 306 | |
| 307 /* And now we're ready to convert */ | |
| 308 SDL_ConvertAudio(&wav_cvt); | |
| 309 | |
| 310 /* do whatever */ | |
| 311 . | |
| 312 . | |
| 313 . | |
| 314 . | |
| 315 </PRE | |
| 316 ></DIV | |
| 317 ><DIV | |
| 318 CLASS="REFSECT1" | |
| 319 ><A | |
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320 NAME="AEN6708" |
| 0 | 321 ></A |
| 322 ><H2 | |
| 323 >See Also</H2 | |
| 324 ><P | |
| 325 ><A | |
| 326 HREF="sdlbuildaudiocvt.html" | |
| 327 ><TT | |
| 328 CLASS="FUNCTION" | |
| 329 >SDL_BuildAudioCVT</TT | |
| 330 ></A | |
| 331 >, | |
| 332 <A | |
| 333 HREF="sdlaudiocvt.html" | |
| 334 ><TT | |
| 335 CLASS="FUNCTION" | |
| 336 >SDL_AudioCVT</TT | |
| 337 ></A | |
| 338 ></P | |
| 339 ></DIV | |
| 340 ><DIV | |
| 341 CLASS="NAVFOOTER" | |
| 342 ><HR | |
| 343 ALIGN="LEFT" | |
| 344 WIDTH="100%"><TABLE | |
| 345 WIDTH="100%" | |
| 346 BORDER="0" | |
| 347 CELLPADDING="0" | |
| 348 CELLSPACING="0" | |
| 349 ><TR | |
| 350 ><TD | |
| 351 WIDTH="33%" | |
| 352 ALIGN="left" | |
| 353 VALIGN="top" | |
| 354 ><A | |
| 355 HREF="sdlbuildaudiocvt.html" | |
| 356 >Prev</A | |
| 357 ></TD | |
| 358 ><TD | |
| 359 WIDTH="34%" | |
| 360 ALIGN="center" | |
| 361 VALIGN="top" | |
| 362 ><A | |
| 363 HREF="index.html" | |
| 364 >Home</A | |
| 365 ></TD | |
| 366 ><TD | |
| 367 WIDTH="33%" | |
| 368 ALIGN="right" | |
| 369 VALIGN="top" | |
| 370 ><A | |
| 371 HREF="sdlmixaudio.html" | |
| 372 >Next</A | |
| 373 ></TD | |
| 374 ></TR | |
| 375 ><TR | |
| 376 ><TD | |
| 377 WIDTH="33%" | |
| 378 ALIGN="left" | |
| 379 VALIGN="top" | |
| 380 >SDL_BuildAudioCVT</TD | |
| 381 ><TD | |
| 382 WIDTH="34%" | |
| 383 ALIGN="center" | |
| 384 VALIGN="top" | |
| 385 ><A | |
| 386 HREF="audio.html" | |
| 387 >Up</A | |
| 388 ></TD | |
| 389 ><TD | |
| 390 WIDTH="33%" | |
| 391 ALIGN="right" | |
| 392 VALIGN="top" | |
| 393 >SDL_MixAudio</TD | |
| 394 ></TR | |
| 395 ></TABLE | |
| 396 ></DIV | |
| 397 ></BODY | |
| 398 ></HTML | |
| 399 > |