Mercurial > sdl-ios-xcode

comparison docs/html/sdlconvertaudio.html @ 0:74212992fb08

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
parents
children 55f1f1b3e27d
comparison
equal deleted inserted replaced
-1:000000000000 0:74212992fb08
1 <HTML
2 ><HEAD
3 ><TITLE
4 >SDL_ConvertAudio</TITLE
5 ><META
6 NAME="GENERATOR"
7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
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
76 NAME="AEN6426"
77 ></A
78 ><H2
79 >Name</H2
80 >SDL_ConvertAudio&nbsp;--&nbsp;Convert audio data to a desired audio format.</DIV
81 ><DIV
82 CLASS="REFSYNOPSISDIV"
83 ><A
84 NAME="AEN6429"
85 ></A
86 ><H2
87 >Synopsis</H2
88 ><DIV
89 CLASS="FUNCSYNOPSIS"
90 ><A
91 NAME="AEN6430"
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
115 NAME="AEN6436"
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 >-&#62;<TT
144 CLASS="STRUCTFIELD"
145 ><I
146 >buf</I
147 ></TT
148 > and <SPAN
149 CLASS="STRUCTNAME"
150 >cvt</SPAN
151 >-&#62;<TT
152 CLASS="STRUCTFIELD"
153 ><I
154 >len</I
155 ></TT
156 > fields must be setup. <SPAN
157 CLASS="STRUCTNAME"
158 >cvt</SPAN
159 >-&#62;<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 >-&#62;<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 >-&#62;<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 >-&#62;<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 >-&#62;<TT
226 CLASS="STRUCTFIELD"
227 ><I
228 >len</I
229 ></TT
230 >*<TT
231 CLASS="STRUCTFIELD"
232 ><I
233 >cvt</I
234 ></TT
235 >-&#62;<SPAN
236 CLASS="STRUCTNAME"
237 >len_ratio</SPAN
238 >.</P
239 ></DIV
240 ><DIV
241 CLASS="REFSECT1"
242 ><A
243 NAME="AEN6471"
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-&#62;freq=22050;
265 desired-&#62;format=AUDIO_S16LSB;
266 desired-&#62;samples=8192;
267 desired-&#62;callback=my_audio_callback;
268 desired-&#62;userdata=NULL;
269
270 /* Open the audio device */
271 if ( SDL_OpenAudio(desired, obtained) &#60; 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", &#38;wav_spec, &#38;wav_buf, &#38;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(&#38;wav_cvt,
288 wav_spec.format, wav_spec.channels, wav_spec.freq,
289 obtained-&#62;format, obtained-&#62;channels, obtained-&#62;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(&#38;wav_cvt);
309
310 /* do whatever */
311 .
312 .
313 .
314 .
315 &#13;</PRE
316 ></DIV
317 ><DIV
318 CLASS="REFSECT1"
319 ><A
320 NAME="AEN6474"
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 >