Objective C: OpenAL changing Pitch issue - objective-c

Question

im having a hard time on OpenAL framework... i just want to change the pitch in playback action... what code is missing in my project.. im new in objective c,iOS development. hoping for your kind consideration, thanks in advance.. here is my code for the three button (RECORD,STOP,Play)..
-(void)startRecording:(UIButton *)sender
{ //for recording
recStopBtn.hidden = NO;
recStopBtn.enabled =YES;
playRecBtn.enabled = NO;
loading.hidden = NO;
[loading startAnimating];
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *err = nil;
[audioSession setCategory :AVAudioSessionCategoryPlayAndRecord error:&err];
if(err)
{
NSLog(#"audioSession: %# %d %#", [err domain], [err code], [[err userInfo] description]);
return;
}
[audioSession setActive:YES error:&err];
err = nil;
if(err)
{
NSLog(#"audioSession: %# %d %#", [err domain], [err code], [[err userInfo] description]);
return;
}
recordSetting = [[NSMutableDictionary alloc] init];
// We can use kAudioFormatAppleIMA4 (4:1 compression) or kAudioFormatLinearPCM for nocompression
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
// We can use 44100, 32000, 24000, 16000 or 12000 depending on sound quality
[recordSetting setValue:[NSNumber numberWithFloat:16000.0] forKey:AVSampleRateKey];
// We can use 2(if using additional h/w) or 1 (iPhone only has one microphone)
[recordSetting setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];
// These settings are used if we are using kAudioFormatLinearPCM format
//[recordSetting setValue :[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
//[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
//[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];
recorderFilePath = [NSString stringWithFormat:#"%#/MySound.caf", DOCUMENTS_FOLDER];
NSLog(#"recorderFilePath: %#",recorderFilePath);
NSURL *url = [NSURL fileURLWithPath:recorderFilePath];
err = nil;
NSData *audioData = [NSData dataWithContentsOfFile:[url path] options: 0 error:&err];
if(audioData)
{
NSFileManager *fm = [NSFileManager defaultManager];
[fm removeItemAtPath:[url path] error:&err];
}
err = nil;
recorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSetting error:&err];
if(!recorder){
NSLog(#"recorder: %# %d %#", [err domain], [err code], [[err userInfo] description]);
UIAlertView *alert =
[[UIAlertView alloc] initWithTitle: #"Warning"
message: [err localizedDescription]
delegate: nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alert show];
return;
}
//prepare to record
[recorder setDelegate:self];
[recorder prepareToRecord];
recorder.meteringEnabled = YES;
BOOL audioHWAvailable = audioSession.inputIsAvailable;
if (! audioHWAvailable) {
UIAlertView *cantRecordAlert =
[[UIAlertView alloc] initWithTitle: #"Warning"
message: #"Audio input hardware not available"
delegate: nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[cantRecordAlert show];
return;
}
// start recording
[recorder record];
lblStatusMsg.text = #"Recording...";
//recIcon.image = [UIImage imageNamed:#"rec_icon.png"];
//progressView.progress = 0.0;
//timer = [NSTimer scheduledTimerWithTimeInterval:6.0 target:self selector:#selector(handleTimer) userInfo:nil repeats:YES];
}
-(void)stopRecord:(UIButton *)sender
{
loading.hidden = YES;
[loading stopAnimating];
recStartBtn.enabled = YES;
recStartBtn.hidden = NO;
playRecBtn.hidden = NO;
playRecBtn.enabled = YES;
recStopBtn.enabled = NO;
recStopBtn.hidden = YES;
[recorder stop];
[timer invalidate];
lblStatusMsg.text = #"Stopped";
// recIcon.image = [UIImage imageNamed:#"rec_icon2.png"];
}
-(void)playRecord:(UIButton *)sender
{
recorderFilePath = [NSString stringWithFormat:#"%#/MySound.caf", DOCUMENTS_FOLDER];
NSURL *urlRecord = [NSURL fileURLWithPath:recorderFilePath isDirectory:NO];
NSError *errorRecord;
soundRecord = [[AVAudioPlayer alloc] initWithContentsOfURL:urlRecord error:&errorRecord];
[soundRecord play];
}
-(void)changePitch:(UIButton *)sender
{
alSourcef(recorderFilePath, AL_PITCH, 1.2f);//this kinda troubles me,the source. =(
[soundRecord play];//this one also...
}

Answer 1

The first argument of the alSourcef method isn't an NSString file path, it's an ALuint representing an audio source.
See the example oalTouch (specifically the oalPlayback class) for how to set up an OpenAL source from a URL.