.TH "SDL_ConvertAudio" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" 

.SH "NAME"

SDL_ConvertAudio \- Convert audio data to a desired audio format\&.

.SH "SYNOPSIS"

.PP

\fB#include "SDL\&.h"

.sp

\fBint \fBSDL_ConvertAudio\fP\fR(\fBSDL_AudioCVT *cvt\fR);

.SH "DESCRIPTION"

.PP

\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\&.

.PP

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\&.

.PP

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\&.

.SH "EXAMPLES"

.PP

.nf

\f(CW/* Converting some WAV data to hardware format */

void my_audio_callback(void *userdata, Uint8 *stream, int len);

SDL_AudioSpec *desired, *obtained;

SDL_AudioSpec wav_spec;

SDL_AudioCVT  wav_cvt;

Uint32 wav_len;

Uint8 *wav_buf;

int ret;

/* Allocated audio specs */

desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec));

obtained=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec));

/* Set desired format */

desired->freq=22050;

desired->format=AUDIO_S16LSB;

desired->samples=8192;

desired->callback=my_audio_callback;

desired->userdata=NULL;

/* Open the audio device */

if ( SDL_OpenAudio(desired, obtained) < 0 ){

  fprintf(stderr, "Couldn\&'t open audio: %s

", SDL_GetError());

  exit(-1);

}

free(desired);

/* Load the test\&.wav */

if( SDL_LoadWAV("test\&.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){

  fprintf(stderr, "Could not open test\&.wav: %s

", SDL_GetError());

  SDL_CloseAudio();

  free(obtained);

  exit(-1);

}

/* Build AudioCVT */

ret = SDL_BuildAudioCVT(&wav_cvt,

                        wav_spec\&.format, wav_spec\&.channels, wav_spec\&.freq,

                        obtained->format, obtained->channels, obtained->freq);

/* Check that the convert was built */

if(ret==-1){

  fprintf(stderr, "Couldn\&'t build converter!

");

  SDL_CloseAudio();

  free(obtained);

  SDL_FreeWAV(wav_buf);

}

/* Setup for conversion */

wav_cvt\&.buf=(Uint8 *)malloc(wav_len*wav_cvt\&.len_mult);

wav_cvt\&.len=wav_len;

memcpy(wav_cvt\&.buf, wav_buf, wav_len);

/* We can delete to original WAV data now */

SDL_FreeWAV(wav_buf);

/* And now we\&'re ready to convert */

SDL_ConvertAudio(&wav_cvt);

/* do whatever */

\&.

\&.

\&.

\&.

\fR

.fi

.PP

.SH "SEE ALSO"

.PP

\fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_AudioCVT\fP\fR

...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58