iphone - AudioUnitInitialize 在初始化 AudioComponentInstance 时抛出错误

Question

我正在使用以下代码来初始化我的音频组件。

-(void) startListeningWithCoreAudio
{
     NSError *error = nil;

     [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayAndRecord error:&error];
     if (error) 
          NSLog(@"error setting up audio session: %@", [error localizedDescription]);

     [[AVAudioSession sharedInstance] setDelegate:self];

     OSStatus status = AudioSessionSetActive(YES);
     checkStatus(status);

          // Find the apple mic
    AudioComponentDescription desc;
    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_VoiceProcessingIO;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;

    AudioComponent inputComponent = AudioComponentFindNext( NULL, &desc );
    status = AudioComponentInstanceNew( inputComponent, &kAudioUnit );
    checkStatus( status );

          // enable mic output as our input
    UInt32 flag = 1;
    status = AudioUnitSetProperty( kAudioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, kInputBus, &flag, sizeof(flag) );
    checkStatus(status);


          // Define mic output audio format
    AudioStreamBasicDescription audioFormat;
    audioFormat.mSampleRate         = 16000.0;
    audioFormat.mFormatID           = kAudioFormatLinearPCM;
    audioFormat.mFormatFlags        = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    audioFormat.mFramesPerPacket    = 1;
    audioFormat.mChannelsPerFrame   = 1;
    audioFormat.mBitsPerChannel     = 16;
    audioFormat.mBytesPerPacket     = 2;
    audioFormat.mBytesPerFrame      = 2;

    status = AudioUnitSetProperty( kAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, kInputBus, &audioFormat, sizeof(audioFormat) );
    checkStatus(status);

          // Define our callback methods
    AURenderCallbackStruct callbackStruct;
    callbackStruct.inputProc = recordingCallback;
    callbackStruct.inputProcRefCon = self;
    status = AudioUnitSetProperty( kAudioUnit, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Global, kInputBus, &callbackStruct, sizeof(callbackStruct) );
    checkStatus(status);

          // By pass voice processing
     UInt32 audiobypassProcessing = [[NSUserDefaults standardUserDefaults] boolForKey:VOICE_BY_PASS_PROCESSING];
     status = AudioUnitSetProperty(kAudioUnit, kAUVoiceIOProperty_BypassVoiceProcessing, 
                                   kAudioUnitScope_Global, kInputBus, &audiobypassProcessing, sizeof(audiobypassProcessing));
     checkStatus(status);

          // Automatic Gain Control
     UInt32 audioAGC = [[NSUserDefaults standardUserDefaults]boolForKey:VOICE_AGC];
     status = AudioUnitSetProperty(kAudioUnit, kAUVoiceIOProperty_VoiceProcessingEnableAGC, 
                                   kAudioUnitScope_Global, kInputBus, &audioAGC, sizeof(audioAGC));
     checkStatus(status);

          //Non Audio Voice Ducking
     UInt32 audioDucking = [[NSUserDefaults standardUserDefaults]boolForKey:VOICE_DUCKING];
     status = AudioUnitSetProperty(kAudioUnit, kAUVoiceIOProperty_DuckNonVoiceAudio, 
                                   kAudioUnitScope_Global, kInputBus, &audioDucking, sizeof(audioDucking));
     checkStatus(status);

          //Audio Quality
     UInt32 quality = [[NSUserDefaults standardUserDefaults]integerForKey:VOICE_QUALITY];
     status = AudioUnitSetProperty(kAudioUnit, kAUVoiceIOProperty_VoiceProcessingQuality, 
                                   kAudioUnitScope_Global, kInputBus, &quality, sizeof(quality));
     checkStatus(status);

     status = AudioUnitInitialize(kAudioUnit);
     checkStatus(status);

    status = AudioOutputUnitStart( kAudioUnit );
    checkStatus(status);

    UInt32 audioRoute = (UInt32)kAudioSessionOverrideAudioRoute_Speaker;
    status = AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute, sizeof (audioRoute), &audioRoute);
    checkStatus(status);     
}


-(void) stopListeningWithCoreAudio
{ 
    OSStatus     status = AudioUnitUninitialize( kAudioUnit );
     checkStatus(status);

     status = AudioOutputUnitStop( kAudioUnit );
    checkStatus( status );

//     if(kAudioUnit)
//     {
//          status = AudioComponentInstanceDispose(kAudioUnit);
//          checkStatus(status);
//          kAudioUnit = nil;
//     }

    status = AudioSessionSetActive(NO);
     checkStatus(status);

     NSError *error = nil;
    [[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategorySoloAmbient error:&error];
    if (error)
          NSLog(@"error setting up audio session: %@", [error localizedDescription]);
}

第一次使用效果很好。我的意思是 startListeningWithCoreAudio 由按钮按下事件调用。它可以很好地记录/处理音频。在其他事件中，我正在调用 stopListeningWithCoreAudio 来停止录制/处理音频。

当我再次尝试调用函数startListeningWithCoreAudio 时，问题来了。它为两个函数抛出错误。 AudioUnitInitialize 和 AudioOutputUnitStart 从 startListeningWithCoreAudio 调用。

谁能帮我看看这是什么问题？

Answer 1

我找到了解决方案。如果我们连续调用以下函数，就会产生问题。

extern OSStatus AudioUnitUninitialize(AudioUnit inUnit)                     
extern OSStatus AudioComponentInstanceDispose(AudioComponentInstance inInstance)

因此，我通过以下方式在主线程上调用了 dispose 方法。

[self performSelectorOnMainThread:@selector(disposeCoreAudio) withObject:nil waitUntilDone:NO];

-(void) disposeCoreAudio
{
     OSStatus status = AudioComponentInstanceDispose(kAudioUnit);
     kAudioUnit = nil;
}

问题解决了。因此，正确的顺序是停止记录、取消初始化记录器并在主线程上处理记录器。