Audio Examples

Opening the audio device (using linear 16 bit stereo audio at 22050 Hz)

#include <SDL_audio.h>
#include <SDL_error.h>

        SDL_AudioSpec wanted;
        extern void fill_audio(void *udata, Uint8 *stream, int len);

        /* Set the audio format */
        wanted.freq = 22050;
        wanted.format = AUDIO_S16;
        wanted.channels = 2;    /* 1 = mono, 2 = stereo */
        wanted.samples = 1024;  /* Good low-latency value for callback */
        wanted.callback = fill_audio;
        wanted.userdata = NULL;

        /* Open the audio device, forcing the desired format */
        if ( SDL_OpenAudio(&wanted, NULL) < 0 ) {
                fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
                return(-1);
        }
        return(0);

Playing audio using a callback function

This example assumes you have opened the audio device and have the audio data you want to play already stored in the audio_chunk pointer.

#include <SDL_audio.h>
#include <SDL_timer.h>

static Uint8 *audio_chunk;
static Uint32 audio_len;
static Uint8 *audio_pos;

/* The audio function callback takes the following parameters:
    stream:  A pointer to the audio buffer to be filled
    len:     The length (in bytes) of the audio buffer
*/
void fill_audio(void *udata, Uint8 *stream, int len)
{
        /* Only play if we have data left */
        if ( audio_len == 0 )
                return;

        /* Mix as much data as possible */
        len = ( len > audio_len ? audio_len : len );
        SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME)
        audio_pos += len;
        audio_len -= len;
}

        /* Load the audio data ... */
        ;;;;;
        audio_pos = audio_chunk;

        /* Let the callback function play the audio chunk */
        SDL_PauseAudio(0);

        /* Do some processing */
        ;;;;;

        /* Wait for sound to complete */
        while ( audio_len > 0 ) {
                SDL_Delay(100);         /* Sleep 1/10 second */
        }
        SDL_CloseAudio();