.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\&..PPOnce 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\&..PPIf 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