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annotate docs/man3/SDL_ConvertAudio.3 @ 4159:a1b03ba2fcd0 SDL-1.2
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author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 08 Dec 2008 00:25:42 +0000 |
parents | 4e3b250c950e |
children | 1238da4a7112 |
rev | line source |
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Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
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1 .TH "SDL_ConvertAudio" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
4107
4e3b250c950e
Erik Heckers fixed bug #493
Sam Lantinga <slouken@libsdl.org>
parents:
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3 SDL_ConvertAudio \- Convert audio data to a desired audio format\&. |
0 | 4 .SH "SYNOPSIS" |
5 .PP | |
6 \fB#include "SDL\&.h" | |
7 .sp | |
8 \fBint \fBSDL_ConvertAudio\fP\fR(\fBSDL_AudioCVT *cvt\fR); | |
9 .SH "DESCRIPTION" | |
10 .PP | |
11 \fBSDL_ConvertAudio\fP takes one parameter, \fBcvt\fR, which was previously initilized\&. Initilizing a \fI\fBSDL_AudioCVT\fR\fR is a two step process\&. First of all, the structure must be passed to \fI\fBSDL_BuildAudioCVT\fP\fR along with source and destination format parameters\&. Secondly, the \fBcvt\fR->\fBbuf\fR and \fBcvt\fR->\fBlen\fR fields must be setup\&. \fBcvt\fR->\fBbuf\fR should point to the audio data and \fBcvt\fR->\fBlen\fR should be set to the length of the audio data in bytes\&. Remember, the length of the buffer pointed to by \fBbuf\fR show be \fBlen\fR*\fBlen_mult\fR bytes in length\&. | |
12 .PP | |
13 Once the \fBSDL_AudioCVT\fRstructure is initilized then we can pass it to \fBSDL_ConvertAudio\fP, which will convert the audio data pointer to by \fBcvt\fR->\fBbuf\fR\&. If \fBSDL_ConvertAudio\fP returned \fB0\fR then the conversion was completed successfully, otherwise \fB-1\fR is returned\&. | |
14 .PP | |
15 If the conversion completed successfully then the converted audio data can be read from \fBcvt\fR->\fBbuf\fR\&. The amount of valid, converted, audio data in the buffer is equal to \fBcvt\fR->\fBlen\fR*\fBcvt\fR->\fBlen_ratio\fR\&. | |
16 .SH "EXAMPLES" | |
17 .PP | |
18 .nf | |
19 \f(CW/* Converting some WAV data to hardware format */ | |
20 void my_audio_callback(void *userdata, Uint8 *stream, int len); | |
21 | |
22 SDL_AudioSpec *desired, *obtained; | |
23 SDL_AudioSpec wav_spec; | |
24 SDL_AudioCVT wav_cvt; | |
25 Uint32 wav_len; | |
26 Uint8 *wav_buf; | |
27 int ret; | |
28 | |
29 /* Allocated audio specs */ | |
30 desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
31 obtained=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec)); | |
32 | |
33 /* Set desired format */ | |
34 desired->freq=22050; | |
35 desired->format=AUDIO_S16LSB; | |
36 desired->samples=8192; | |
37 desired->callback=my_audio_callback; | |
38 desired->userdata=NULL; | |
39 | |
40 /* Open the audio device */ | |
41 if ( SDL_OpenAudio(desired, obtained) < 0 ){ | |
42 fprintf(stderr, "Couldn\&'t open audio: %s | |
43 ", SDL_GetError()); | |
44 exit(-1); | |
45 } | |
46 | |
47 free(desired); | |
48 | |
49 /* Load the test\&.wav */ | |
50 if( SDL_LoadWAV("test\&.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){ | |
51 fprintf(stderr, "Could not open test\&.wav: %s | |
52 ", SDL_GetError()); | |
53 SDL_CloseAudio(); | |
54 free(obtained); | |
55 exit(-1); | |
56 } | |
57 | |
58 /* Build AudioCVT */ | |
59 ret = SDL_BuildAudioCVT(&wav_cvt, | |
60 wav_spec\&.format, wav_spec\&.channels, wav_spec\&.freq, | |
61 obtained->format, obtained->channels, obtained->freq); | |
62 | |
63 /* Check that the convert was built */ | |
64 if(ret==-1){ | |
65 fprintf(stderr, "Couldn\&'t build converter! | |
66 "); | |
67 SDL_CloseAudio(); | |
68 free(obtained); | |
69 SDL_FreeWAV(wav_buf); | |
70 } | |
71 | |
72 /* Setup for conversion */ | |
73 wav_cvt\&.buf=(Uint8 *)malloc(wav_len*wav_cvt\&.len_mult); | |
74 wav_cvt\&.len=wav_len; | |
75 memcpy(wav_cvt\&.buf, wav_buf, wav_len); | |
76 | |
77 /* We can delete to original WAV data now */ | |
78 SDL_FreeWAV(wav_buf); | |
79 | |
80 /* And now we\&'re ready to convert */ | |
81 SDL_ConvertAudio(&wav_cvt); | |
82 | |
83 /* do whatever */ | |
84 \&. | |
85 \&. | |
86 \&. | |
87 \&. | |
88 | |
89 \fR | |
90 .fi | |
91 .PP | |
92 .SH "SEE ALSO" | |
93 .PP | |
94 \fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_AudioCVT\fP\fR | |
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Updated from the SDL Documentation Project
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parents:
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95 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |