void SDL_MixAudio(Uint8*       dst, 
                  const Uint8* src,
                  Uint32       len, 
                  int          volume)

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;

/* Empty any old data in the buffer */
    SDL_memset(stream, 0, len);

/* 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();

SDL_MixAudioFormat(dst, src, format, len, volume);