Mercurial > sdl-ios-xcode
annotate docs/html/sdlconvertaudio.html @ 55:55f1f1b3e27d
Added new docs for SDL 1.2.1
author | Sam Lantinga <slouken@lokigames.com> |
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date | Sun, 10 Jun 2001 19:31:57 +0000 |
parents | 74212992fb08 |
children | e5bc29de3f0a |
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 1.64 |
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="AEN6501" |
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="AEN6504" |
0 | 85 ></A |
86 ><H2 | |
87 >Synopsis</H2 | |
88 ><DIV | |
89 CLASS="FUNCSYNOPSIS" | |
90 ><A | |
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91 NAME="AEN6505" |
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="AEN6511" |
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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diff
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243 NAME="AEN6546" |
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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parents:
0
diff
changeset
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320 NAME="AEN6549" |
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 > |