How to play looping sound with OpenAL on iPhone - iphone

Question

I'm following a tutorial about playing sound with OpenAL. Now everything works fine except I can't make the sound looping. I believe that I've used AL_LOOPING for the source. Now it can only play once and when it finishes playing, the app will block(doesn't response to my tap on the play button). Any ideas about what's wrong with the code?
// start up openAL
// init device and context
-(void)initOpenAL
{
// Initialization
mDevice = alcOpenDevice(NULL); // select the "preferred device"
if (mDevice) {
// use the device to make a context
mContext = alcCreateContext(mDevice, NULL);
// set my context to the currently active one
alcMakeContextCurrent(mContext);
}
}
// open the audio file
// returns a big audio ID struct
-(AudioFileID)openAudioFile:(NSString*)filePath
{
AudioFileID outAFID;
// use the NSURl instead of a cfurlref cuz it is easier
NSURL * afUrl = [NSURL fileURLWithPath:filePath];
// do some platform specific stuff..
#if TARGET_OS_IPHONE
OSStatus result = AudioFileOpenURL((CFURLRef)afUrl, kAudioFileReadPermission, 0, &outAFID);
#else
OSStatus result = AudioFileOpenURL((CFURLRef)afUrl, fsRdPerm, 0, &outAFID);
#endif
if (result != 0) NSLog(#"cannot openf file: %#",filePath);
return outAFID;
}
// find the audio portion of the file
// return the size in bytes
-(UInt32)audioFileSize:(AudioFileID)fileDescriptor
{
UInt64 outDataSize = 0;
UInt32 thePropSize = sizeof(UInt64);
OSStatus result = AudioFileGetProperty(fileDescriptor, kAudioFilePropertyAudioDataByteCount, &thePropSize, &outDataSize);
if(result != 0) NSLog(#"cannot find file size");
return (UInt32)outDataSize;
}
- (void)stopSound
{
alSourceStop(sourceID);
}
-(void)cleanUpOpenAL:(id)sender
{
// delete the sources
alDeleteSources(1, &sourceID);
// delete the buffers
alDeleteBuffers(1, &bufferID);
// destroy the context
alcDestroyContext(mContext);
// close the device
alcCloseDevice(mDevice);
}
-(IBAction)play:(id)sender
{
alSourcePlay(sourceID);
}
#pragma mark -
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
[self initOpenAL];
// get the full path of the file
NSString* fileName = [[NSBundle mainBundle] pathForResource:#"sound" ofType:#"caf"];
// first, open the file
AudioFileID fileID = [self openAudioFile:fileName];
// find out how big the actual audio data is
UInt32 fileSize = [self audioFileSize:fileID];
// this is where the audio data will live for the moment
unsigned char * outData = malloc(fileSize);
// this where we actually get the bytes from the file and put them
// into the data buffer
OSStatus result = noErr;
result = AudioFileReadBytes(fileID, false, 0, &fileSize, outData);
AudioFileClose(fileID); //close the file
if (result != 0) NSLog(#"cannot load effect: %#", fileName);
//NSUInteger bufferID; // buffer is defined in head file
// grab a buffer ID from openAL
alGenBuffers(1, &bufferID);
// jam the audio data into the new buffer
alBufferData(bufferID, AL_FORMAT_STEREO16, outData, fileSize, 8000);
//NSUInteger sourceID; // source is defined in head file
// grab a source ID from openAL
alGenSources(1, &sourceID);
// attach the buffer to the source
alSourcei(sourceID, AL_BUFFER, bufferID);
// set some basic source prefs
alSourcef(sourceID, AL_PITCH, 1.0f);
alSourcef(sourceID, AL_GAIN, 1.0f);
alSourcei(sourceID, AL_LOOPING, AL_TRUE);
// clean up the buffer
if (outData)
{
free(outData);
outData = NULL;
}
}

Answer 1

You should be able to release outData right after your alBufferData() call. It exclude it as the culprit, you can try the static extension and manage the memory yourself. It's something like:
alBufferDataStaticProcPtr alBufferDataStaticProc = (alBufferDataStaticProcPtr)alcGetProcAddress(0, (const ALCchar *)"alBufferDataStatic");
alBufferDataStaticProc(bufferID, bitChanFormat, audioData, audioDataSize, dataFormat.mSampleRate);