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| >Opening the audio device</H2 |
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| CLASS="PROGRAMLISTING" |
| > 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);</PRE |
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| >Playing audio</H2 |
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| > 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();</PRE |
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