|
1 .TH "SDL_ConvertAudio" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
|
2 .SH "NAME" |
|
3 SDL_ConvertAudio \- Convert audio data to a desired audio format\&. |
|
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 |
|
95 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |