Mercurial > sdl-ios-xcode
annotate docs/html/sdlconvertaudio.html @ 3261:72b542f34739
The new, cleaner, version of the atomic operations. The dummy code is what you should start working with to port atomic ops.
The linux code appears to be complete and *should* be the base of all Unix and GCC based versions. The macosx and win32 versions
are currently just copies of the dummy code. I will begin working on the windows version as soon as this check in is done. I
need someone to work on the Mac OS X version.
I'm afraid that this check in will break QNX (Sorry!)
| author | Bob Pendleton <bob@pendleton.com> |
|---|---|
| date | Thu, 17 Sep 2009 20:35:12 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
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| 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 1.76b+ |
| 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 | |
|
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31 SUMMARY="Header navigation table" |
| 0 | 32 WIDTH="100%" |
| 33 BORDER="0" | |
| 34 CELLPADDING="0" | |
| 35 CELLSPACING="0" | |
| 36 ><TR | |
| 37 ><TH | |
| 38 COLSPAN="3" | |
| 39 ALIGN="center" | |
| 40 >SDL Library Documentation</TH | |
| 41 ></TR | |
| 42 ><TR | |
| 43 ><TD | |
| 44 WIDTH="10%" | |
| 45 ALIGN="left" | |
| 46 VALIGN="bottom" | |
| 47 ><A | |
| 48 HREF="sdlbuildaudiocvt.html" | |
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49 ACCESSKEY="P" |
| 0 | 50 >Prev</A |
| 51 ></TD | |
| 52 ><TD | |
| 53 WIDTH="80%" | |
| 54 ALIGN="center" | |
| 55 VALIGN="bottom" | |
| 56 ></TD | |
| 57 ><TD | |
| 58 WIDTH="10%" | |
| 59 ALIGN="right" | |
| 60 VALIGN="bottom" | |
| 61 ><A | |
| 62 HREF="sdlmixaudio.html" | |
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63 ACCESSKEY="N" |
| 0 | 64 >Next</A |
| 65 ></TD | |
| 66 ></TR | |
| 67 ></TABLE | |
| 68 ><HR | |
| 69 ALIGN="LEFT" | |
| 70 WIDTH="100%"></DIV | |
| 71 ><H1 | |
| 72 ><A | |
| 73 NAME="SDLCONVERTAUDIO" | |
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74 ></A |
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75 >SDL_ConvertAudio</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN7048" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_ConvertAudio -- Convert audio data to a desired audio format.</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN7051" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN7052" |
| 0 | 95 ></A |
| 96 ><P | |
| 97 ></P | |
| 98 ><PRE | |
| 99 CLASS="FUNCSYNOPSISINFO" | |
| 100 >#include "SDL.h"</PRE | |
| 101 ><P | |
| 102 ><CODE | |
| 103 ><CODE | |
| 104 CLASS="FUNCDEF" | |
| 105 >int <B | |
| 106 CLASS="FSFUNC" | |
| 107 >SDL_ConvertAudio</B | |
| 108 ></CODE | |
| 109 >(SDL_AudioCVT *cvt);</CODE | |
| 110 ></P | |
| 111 ><P | |
| 112 ></P | |
| 113 ></DIV | |
| 114 ></DIV | |
| 115 ><DIV | |
| 116 CLASS="REFSECT1" | |
| 117 ><A | |
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118 NAME="AEN7058" |
| 0 | 119 ></A |
| 120 ><H2 | |
| 121 >Description</H2 | |
| 122 ><P | |
| 123 ><TT | |
| 124 CLASS="FUNCTION" | |
| 125 >SDL_ConvertAudio</TT | |
| 126 > takes one parameter, <TT | |
| 127 CLASS="PARAMETER" | |
| 128 ><I | |
| 129 >cvt</I | |
| 130 ></TT | |
| 131 >, which was previously initilized. Initilizing a <A | |
| 132 HREF="sdlaudiocvt.html" | |
| 133 ><SPAN | |
| 134 CLASS="STRUCTNAME" | |
| 135 >SDL_AudioCVT</SPAN | |
| 136 ></A | |
| 137 > is a two step process. First of all, the structure must be passed to <A | |
| 138 HREF="sdlbuildaudiocvt.html" | |
| 139 ><TT | |
| 140 CLASS="FUNCTION" | |
| 141 >SDL_BuildAudioCVT</TT | |
| 142 ></A | |
| 143 > along with source and destination format parameters. Secondly, the <SPAN | |
| 144 CLASS="STRUCTNAME" | |
| 145 >cvt</SPAN | |
| 146 >-><TT | |
| 147 CLASS="STRUCTFIELD" | |
| 148 ><I | |
| 149 >buf</I | |
| 150 ></TT | |
| 151 > and <SPAN | |
| 152 CLASS="STRUCTNAME" | |
| 153 >cvt</SPAN | |
| 154 >-><TT | |
| 155 CLASS="STRUCTFIELD" | |
| 156 ><I | |
| 157 >len</I | |
| 158 ></TT | |
| 159 > fields must be setup. <SPAN | |
| 160 CLASS="STRUCTNAME" | |
| 161 >cvt</SPAN | |
| 162 >-><TT | |
| 163 CLASS="STRUCTFIELD" | |
| 164 ><I | |
| 165 >buf</I | |
| 166 ></TT | |
| 167 > should point to the audio data and <SPAN | |
| 168 CLASS="STRUCTNAME" | |
| 169 >cvt</SPAN | |
| 170 >-><TT | |
| 171 CLASS="STRUCTFIELD" | |
| 172 ><I | |
| 173 >len</I | |
| 174 ></TT | |
| 175 > should be set to the length of the audio data in bytes. Remember, the length of the buffer pointed to by <TT | |
| 176 CLASS="STRUCTFIELD" | |
| 177 ><I | |
| 178 >buf</I | |
| 179 ></TT | |
| 180 > show be <TT | |
| 181 CLASS="STRUCTFIELD" | |
| 182 ><I | |
| 183 >len</I | |
| 184 ></TT | |
| 185 >*<TT | |
| 186 CLASS="STRUCTFIELD" | |
| 187 ><I | |
| 188 >len_mult</I | |
| 189 ></TT | |
| 190 > bytes in length.</P | |
| 191 ><P | |
| 192 >Once the <SPAN | |
| 193 CLASS="STRUCTNAME" | |
| 194 >SDL_AudioCVT</SPAN | |
| 195 >structure is initilized then we can pass it to <TT | |
| 196 CLASS="FUNCTION" | |
| 197 >SDL_ConvertAudio</TT | |
| 198 >, which will convert the audio data pointer to by <SPAN | |
| 199 CLASS="STRUCTNAME" | |
| 200 >cvt</SPAN | |
| 201 >-><TT | |
| 202 CLASS="STRUCTFIELD" | |
| 203 ><I | |
| 204 >buf</I | |
| 205 ></TT | |
| 206 >. If <TT | |
| 207 CLASS="FUNCTION" | |
| 208 >SDL_ConvertAudio</TT | |
| 209 > returned <SPAN | |
| 210 CLASS="RETURNVALUE" | |
| 211 >0</SPAN | |
| 212 > then the conversion was completed successfully, otherwise <SPAN | |
| 213 CLASS="RETURNVALUE" | |
| 214 >-1</SPAN | |
| 215 > is returned.</P | |
| 216 ><P | |
| 217 >If the conversion completed successfully then the converted audio data can be read from <SPAN | |
| 218 CLASS="STRUCTNAME" | |
| 219 >cvt</SPAN | |
| 220 >-><TT | |
| 221 CLASS="STRUCTFIELD" | |
| 222 ><I | |
| 223 >buf</I | |
| 224 ></TT | |
| 225 >. The amount of valid, converted, audio data in the buffer is equal to <SPAN | |
| 226 CLASS="STRUCTNAME" | |
| 227 >cvt</SPAN | |
| 228 >-><TT | |
| 229 CLASS="STRUCTFIELD" | |
| 230 ><I | |
| 231 >len</I | |
| 232 ></TT | |
| 233 >*<TT | |
| 234 CLASS="STRUCTFIELD" | |
| 235 ><I | |
| 236 >cvt</I | |
| 237 ></TT | |
| 238 >-><SPAN | |
| 239 CLASS="STRUCTNAME" | |
| 240 >len_ratio</SPAN | |
| 241 >.</P | |
| 242 ></DIV | |
| 243 ><DIV | |
| 244 CLASS="REFSECT1" | |
| 245 ><A | |
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246 NAME="AEN7093" |
| 0 | 247 ></A |
| 248 ><H2 | |
| 249 >Examples</H2 | |
| 250 ><PRE | |
| 251 CLASS="PROGRAMLISTING" | |
| 252 >/* Converting some WAV data to hardware format */ | |
| 253 void my_audio_callback(void *userdata, Uint8 *stream, int len); | |
| 254 | |
| 255 SDL_AudioSpec *desired, *obtained; | |
| 256 SDL_AudioSpec wav_spec; | |
| 257 SDL_AudioCVT wav_cvt; | |
| 258 Uint32 wav_len; | |
| 259 Uint8 *wav_buf; | |
| 260 int ret; | |
| 261 | |
| 262 /* Allocated audio specs */ | |
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263 desired = malloc(sizeof(SDL_AudioSpec)); |
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264 obtained = malloc(sizeof(SDL_AudioSpec)); |
| 0 | 265 |
| 266 /* Set desired format */ | |
| 267 desired->freq=22050; | |
| 268 desired->format=AUDIO_S16LSB; | |
| 269 desired->samples=8192; | |
| 270 desired->callback=my_audio_callback; | |
| 271 desired->userdata=NULL; | |
| 272 | |
| 273 /* Open the audio device */ | |
| 274 if ( SDL_OpenAudio(desired, obtained) < 0 ){ | |
| 275 fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError()); | |
| 276 exit(-1); | |
| 277 } | |
| 278 | |
| 279 free(desired); | |
| 280 | |
| 281 /* Load the test.wav */ | |
| 282 if( SDL_LoadWAV("test.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){ | |
| 283 fprintf(stderr, "Could not open test.wav: %s\n", SDL_GetError()); | |
| 284 SDL_CloseAudio(); | |
| 285 free(obtained); | |
| 286 exit(-1); | |
| 287 } | |
| 288 | |
| 289 /* Build AudioCVT */ | |
| 290 ret = SDL_BuildAudioCVT(&wav_cvt, | |
| 291 wav_spec.format, wav_spec.channels, wav_spec.freq, | |
| 292 obtained->format, obtained->channels, obtained->freq); | |
| 293 | |
| 294 /* Check that the convert was built */ | |
| 295 if(ret==-1){ | |
| 296 fprintf(stderr, "Couldn't build converter!\n"); | |
| 297 SDL_CloseAudio(); | |
| 298 free(obtained); | |
| 299 SDL_FreeWAV(wav_buf); | |
| 300 } | |
| 301 | |
| 302 /* Setup for conversion */ | |
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303 wav_cvt.buf = malloc(wav_len * wav_cvt.len_mult); |
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304 wav_cvt.len = wav_len; |
| 0 | 305 memcpy(wav_cvt.buf, wav_buf, wav_len); |
| 306 | |
| 307 /* We can delete to original WAV data now */ | |
| 308 SDL_FreeWAV(wav_buf); | |
| 309 | |
| 310 /* And now we're ready to convert */ | |
| 311 SDL_ConvertAudio(&wav_cvt); | |
| 312 | |
| 313 /* do whatever */ | |
| 314 . | |
| 315 . | |
| 316 . | |
| 317 . | |
| 318 </PRE | |
| 319 ></DIV | |
| 320 ><DIV | |
| 321 CLASS="REFSECT1" | |
| 322 ><A | |
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323 NAME="AEN7096" |
| 0 | 324 ></A |
| 325 ><H2 | |
| 326 >See Also</H2 | |
| 327 ><P | |
| 328 ><A | |
| 329 HREF="sdlbuildaudiocvt.html" | |
| 330 ><TT | |
| 331 CLASS="FUNCTION" | |
| 332 >SDL_BuildAudioCVT</TT | |
| 333 ></A | |
| 334 >, | |
| 335 <A | |
| 336 HREF="sdlaudiocvt.html" | |
| 337 ><TT | |
| 338 CLASS="FUNCTION" | |
| 339 >SDL_AudioCVT</TT | |
| 340 ></A | |
| 341 ></P | |
| 342 ></DIV | |
| 343 ><DIV | |
| 344 CLASS="NAVFOOTER" | |
| 345 ><HR | |
| 346 ALIGN="LEFT" | |
| 347 WIDTH="100%"><TABLE | |
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348 SUMMARY="Footer navigation table" |
| 0 | 349 WIDTH="100%" |
| 350 BORDER="0" | |
| 351 CELLPADDING="0" | |
| 352 CELLSPACING="0" | |
| 353 ><TR | |
| 354 ><TD | |
| 355 WIDTH="33%" | |
| 356 ALIGN="left" | |
| 357 VALIGN="top" | |
| 358 ><A | |
| 359 HREF="sdlbuildaudiocvt.html" | |
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360 ACCESSKEY="P" |
| 0 | 361 >Prev</A |
| 362 ></TD | |
| 363 ><TD | |
| 364 WIDTH="34%" | |
| 365 ALIGN="center" | |
| 366 VALIGN="top" | |
| 367 ><A | |
| 368 HREF="index.html" | |
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369 ACCESSKEY="H" |
| 0 | 370 >Home</A |
| 371 ></TD | |
| 372 ><TD | |
| 373 WIDTH="33%" | |
| 374 ALIGN="right" | |
| 375 VALIGN="top" | |
| 376 ><A | |
| 377 HREF="sdlmixaudio.html" | |
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378 ACCESSKEY="N" |
| 0 | 379 >Next</A |
| 380 ></TD | |
| 381 ></TR | |
| 382 ><TR | |
| 383 ><TD | |
| 384 WIDTH="33%" | |
| 385 ALIGN="left" | |
| 386 VALIGN="top" | |
| 387 >SDL_BuildAudioCVT</TD | |
| 388 ><TD | |
| 389 WIDTH="34%" | |
| 390 ALIGN="center" | |
| 391 VALIGN="top" | |
| 392 ><A | |
| 393 HREF="audio.html" | |
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394 ACCESSKEY="U" |
| 0 | 395 >Up</A |
| 396 ></TD | |
| 397 ><TD | |
| 398 WIDTH="33%" | |
| 399 ALIGN="right" | |
| 400 VALIGN="top" | |
| 401 >SDL_MixAudio</TD | |
| 402 ></TR | |
| 403 ></TABLE | |
| 404 ></DIV | |
| 405 ></BODY | |
| 406 ></HTML | |
| 407 > |