Why is AVAudioRecorder prepareToRecord Failing? - iphone

Question

I am trying to setup a basic controller that will record user audio input(voice). However, the AVAudioRecorder's prepareToRecord method is failing and I can't figure out why. I have setup the audio session in my app delegate and I do not receive an errors when I instantiate the AVAudioRecorder instance:
// App delegate snippet
AVAudioSession* audioSession = [AVAudioSession sharedInstance];
NSError* audioSessionError = nil;
[audioSession setCategory: AVAudioSessionCategoryPlayAndRecord
error: &audioSessionError];
if (audioSessionError) {
NSLog (#"Error setting audio category: %#", [audioSessionError localizedDescription]);
} else {
NSLog(#"No session errors for setting category");
}
[audioSession setActive:YES error:&audioSessionError];
if (audioSessionError) {
NSLog (#"Error activating audio session: %#", [audioSessionError localizedDescription]);
} else {
NSLog(#"no session errors for setActive");
}
// VIEW DID LOAD IN RECORDERCONTROLLER
- (void)viewDidLoad {
self.navigationItem.title = [NSString stringWithFormat:#"%#", [[MyAppDelegate loadApplicationPlist] valueForKey:#"recorderViewTitle"]];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
target:self
action:#selector(dismiss)];
[self alertIfNoAudioInput];
[self createAVAudioRecorder];
minutesSecondsFormatter = [[SimpleMinutesSecondsFormatter alloc] init];
currentTimeUpdateTimer = [NSTimer scheduledTimerWithTimeInterval:0.1
target:self selector:#selector(updateAudioDisplay)
userInfo:NULL repeats:YES];
[super viewDidLoad];
}
// CREATE AVAUDIORECORDER
- (NSError *)createAVAudioRecorder {
NSError *recorderSetupError = nil;
[audioRecorder release];
audioRecorder = nil;
NSString *timestamp = [NSString stringWithFormat:#"%d", (long)[[NSDate date] timeIntervalSince1970]];
NSString *destinationString = [[MyAppDelegate getAppDocumentsDirectory] stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.caf", timestamp]];
NSLog(#"destinationString: %#", destinationString);
NSURL *destinationUrl = [NSURL fileURLWithPath: destinationString];
audioRecorder = [[AVAudioRecorder alloc] initWithURL:destinationUrl
settings:[[AVRecordSettings sharedInstance] getSettings]
error:&recorderSetupError];
if (recorderSetupError) {
UIAlertView *cantRecordAlert =
[[UIAlertView alloc] initWithTitle:#"Can't record"
message:[recorderSetupError localizedDescription]
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[cantRecordAlert show];
[cantRecordAlert release];
return recorderSetupError;
} else {
NSLog(#"no av setup error");
}
if ([audioRecorder prepareToRecord]) {
recordPauseButton.enabled = YES;
audioRecorder.delegate = self;
} else {
NSLog(#"couldn't prepare to record");
}
NSLog (#"recorderSetupError: %#", recorderSetupError);
return recorderSetupError;
}

Answer 1

The prepareToRecord also fails (silently, without an error) if the directory where you try to save the file doesn't exist. Use NSFileManager to check if the directory already exists.

Answer 2

It is failing because you did not initialize the AVAudioRecorder object using proper settings. Do this before initializing it:
NSDictionary *recordSettings =
[[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey,
nil];
then you can instantiate it using
audioRecorder = [[AVAudioRecorder alloc] initWithURL:destinationUrl
settings:recordSettings
error:&recorderSetupError];