Cross-platform Audio Streaming - Android NDK Game Development - page 124

12. To avoid handling the complete RIFF WAVE ile format, we prepare a speciic ile
containing a single block of uncompressed audio data; the format of this data is a 22
kHz monophonic 16-bit sound. We pass Data+sizeof(sWAVHeader) as the audio
data, and the size of the audio data is obviously DataSize-sizeof(sWAVHeader) :
PlayBuffer( Data + sizeof( sWAVHeader ),
DataSize - sizeof( sWAVHeader ));
13. Then we call the IsPlaying() function in a spin loop to detect when OpenAL stops
playing the sound:
while ( IsPlaying() ) {}
14. Once the sound playback is complete, we delete all the objects we have created:
alSourceStop( FSourceID );
alDeleteSources( 1, &FSourceID );
alDeleteBuffers( 1, &FBufferID );
alcDestroyContext( FContext );
alcCloseDevice( FDevice );
15. Finally, we unload the OpenAL library on Windows:
UnloadAL();
16. On Android, it is very important to free the allocated resource and release the audio
device. Otherwise, audio will keep playing in the background. To avoid writing Java
code in this small example, we just terminate our native activity with the exit() call:
exit( 0 );
}
17. The code above uses the function IsPlaying() to check if the audio source is busy:
bool IsPlaying()
{
int State;
alGetSourcei( FSourceID, AL_SOURCE_STATE, &State );
return State == AL_PLAYING;
}
18. The function PlayBuffer() feeds the audio data to the audio source:
void PlayBuffer(const unsigned char* Data, int DataSize)
{
alGenBuffers( 1, &FBufferID );
alBufferData( FBufferID, AL_FORMAT_MONO16,
Data, DataSize, 22050 );
alSourcei( FSourceID, AL_BUFFER, FBufferID );
alSourcePlay( FSourceID );
}
};