使用音频队列进行音频播放仅产生白噪声

Question

我尝试使用音频队列简单地播放音频文件。 我从一个教程中获得了这段代码，其中首先录制了音频然后播放，这很好。 修改声音文件路径以指向我的声音文件后，播放时只有白噪声。我尝试过不同的格式并使用我的音频格式设置，但我显然遗漏了一些东西。

另外，我一直在使用Swift学习iOS，但我没能将此代码翻译成Swift，所以我在Swift应用程序中将其桥接。

在线似乎没有太多的例子，链接到的Apple示例项目链接已经死了。

任何建议都非常感谢！

#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