Audio playback with Audio Queue produces only white noise - ios

Question

I'm trying to simply playback an audio file in my bundle with Audio Queue.
I've got this code from a tutorial where audio was first recorded and then played back, which worked fine.
After modifying the sound file path to point at my sound file there is only white noise when playing back. I've tried different formats and played around with my audio format settings but I'm obviously missing something.
Also, I've been learning iOS with Swift, and I failed to translate this code to Swift, so I bridged it in my Swift app.
There seem to be not many examples online, the Apple example project links linked to are dead.
Any advice much appreciated!
#import "ViewController.h"
typedef NS_ENUM(NSUInteger, AudioQueueState) {
AudioQueueState_Idle,
AudioQueueState_Recording,
AudioQueueState_Playing,
};
#import AVFoundation;
#interface ViewController ()
#property AudioQueueState currentState;
#property (strong, nonatomic) NSURL *audioFileURL;
#end
#define NUM_BUFFERS 10
#implementation ViewController
void AudioOutputCallback(void *inUserData,
AudioQueueRef outAQ, // a reference to the audio queue
AudioQueueBufferRef outBuffer) { // the buffers
ViewController *viewController = (__bridge ViewController*)inUserData;
if (viewController.currentState != AudioQueueState_Playing) {
return;
}
// Read the data out of the audio file in order to fill the buffers with it.
UInt32 numBytes = 16000;
OSStatus status = AudioFileReadBytes(audioFileID, false, currentByte, &numBytes, outBuffer->mAudioData);
if (status != noErr && status != kAudioFileEndOfFileError) {
printf("Error\n");
return;
}
// If data has been read successfully tell the audio queue that the buffer is ready to play.
if (numBytes > 0) {
outBuffer->mAudioDataByteSize = numBytes;
OSStatus statusOfEnqueue = AudioQueueEnqueueBuffer(queue, outBuffer, 0, NULL);
if (statusOfEnqueue != noErr) {
printf("Error\n");
return;
}
currentByte += numBytes;
}
// Check if it's at the end of the file.
if (numBytes == 0 || status == kAudioFileEndOfFileError) {
AudioQueueStop(queue, false);
AudioFileClose(audioFileID);
viewController.currentState = AudioQueueState_Idle;
}
}
static SInt64 currentByte;
static AudioStreamBasicDescription audioFormat;
static AudioQueueRef queue;
static AudioQueueBufferRef buffers [NUM_BUFFERS];
static AudioFileID audioFileID;
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self setupAudio];
}
- (void) setupAudio {
audioFormat.mSampleRate = 44100.00;
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
audioFormat.mFramesPerPacket = 1;
audioFormat.mChannelsPerFrame = 1;
audioFormat.mBitsPerChannel = 16;
audioFormat.mBytesPerFrame = audioFormat.mChannelsPerFrame * sizeof(SInt16);
audioFormat.mBytesPerPacket = audioFormat.mFramesPerPacket * audioFormat.mBytesPerFrame;
self.currentState = AudioQueueState_Idle;
}
- (IBAction)playButtonPressed:(id)sender {
// Set up the audio session.
[[AVAudioSession sharedInstance] setActive:YES error:&error];
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&error];
[self startPlayback];
}
- (void) startPlayback {
NSString *resourcePath = [[NSBundle mainBundle] pathForResource:#"MyAudioFileName" ofType:#"wav"];
NSLog(#"path: %#", resourcePath);
self.audioFileURL = [NSURL fileURLWithPath:resourcePath];
currentByte = 0;
OSStatus status = AudioFileOpenURL((__bridge CFURLRef) (self.audioFileURL), kAudioFileReadPermission, kAudioFileWAVEType, &audioFileID);
status = AudioQueueNewOutput(&audioFormat, AudioOutputCallback, (__bridge void*)self, CFRunLoopGetCurrent(), kCFRunLoopCommonModes, 0, &queue);
self.currentState = AudioQueueState_Playing;
for (int i = 0; i < NUM_BUFFERS && self.currentState == AudioQueueState_Playing; i++) {
status = AudioQueueAllocateBuffer(queue, 16000, &buffers[i]);
AudioOutputCallback((__bridge void*)self, queue, buffers[i]);
}
status = AudioQueueStart(queue, NULL);
}
- (void) stopPlayback {
self.currentState = AudioQueueState_Idle;
for (int i = 0; i < NUM_BUFFERS; i++) {
AudioQueueFreeBuffer(queue, buffers[i]);
}
AudioQueueDispose(queue, true);
AudioFileClose(audioFileID);
}
#end