iOS输入麦克风输出蓝牙设备

Question

我正在尝试使用audioRouteOverride从麦克风获取输入并将其输出到我的蓝牙设备，但没有成功。iPhone麦克风的输出仍然传输到iPhone内置扬声器。我期望kAudioSessionOutputRoute_BluetoothA2DP是关键所在，但它并没有按照预期工作。

以下是我正在使用的代码：

- (id) init {
    self = [super init];

    OSStatus status;

    // Describe audio component
    AudioComponentDescription desc;
    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_RemoteIO;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;

    // Get component
    AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);

    // Get audio units
    status = AudioComponentInstanceNew(inputComponent, &audioUnit);
    checkStatus(status);

    // Enable IO for recording
    UInt32 flag = 1;
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioOutputUnitProperty_EnableIO, 
                                  kAudioUnitScope_Input, 
                                  kInputBus,
                                  &flag, 
                                  sizeof(flag));
    checkStatus(status);

    // Enable IO for playback
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioOutputUnitProperty_EnableIO, 
                                  kAudioUnitScope_Output, 
                                  kOutputBus,
                                  &flag, 
                                  sizeof(flag));
    checkStatus(status);

    // Describe format
    AudioStreamBasicDescription audioFormat;
    audioFormat.mSampleRate         = 44100.00;
    audioFormat.mFormatID           = kAudioFormatLinearPCM;
    audioFormat.mFormatFlags        = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
    audioFormat.mFramesPerPacket    = 1;
    audioFormat.mChannelsPerFrame   = 1;
    audioFormat.mBitsPerChannel     = 16;
    audioFormat.mBytesPerPacket     = 2;
    audioFormat.mBytesPerFrame      = 2;

    // Apply format
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioUnitProperty_StreamFormat, 
                                  kAudioUnitScope_Output, 
                                  kInputBus, 
                                  &audioFormat, 
                                  sizeof(audioFormat));
    checkStatus(status);
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioUnitProperty_StreamFormat, 
                                  kAudioUnitScope_Input, 
                                  kOutputBus, 
                                  &audioFormat, 
                                  sizeof(audioFormat));
    checkStatus(status);


    // Set input callback
    AURenderCallbackStruct callbackStruct;
    callbackStruct.inputProc = recordingCallback;
    callbackStruct.inputProcRefCon = self;
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioOutputUnitProperty_SetInputCallback, 
                                  kAudioUnitScope_Global, 
                                  kInputBus, 
                                  &callbackStruct, 
                                  sizeof(callbackStruct));
    checkStatus(status);

    // Set output callback
    callbackStruct.inputProc = playbackCallback;
    callbackStruct.inputProcRefCon = self;
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioUnitProperty_SetRenderCallback, 
                                  kAudioUnitScope_Global, 
                                  kOutputBus,
                                  &callbackStruct, 
                                  sizeof(callbackStruct));
    checkStatus(status);

    // Disable buffer allocation for the recorder (optional - do this if we want to pass in our own)
    flag = 0;
    status = AudioUnitSetProperty(audioUnit, 
                                  kAudioUnitProperty_ShouldAllocateBuffer,
                                  kAudioUnitScope_Output, 
                                  kInputBus,
                                  &flag, 
                                  sizeof(flag));

    NSLog(@"%ld",(long)status);
    // Allocate our own buffers (1 channel, 16 bits per sample, thus 16 bits per frame, thus 2 bytes per frame).
    // Practice learns the buffers used contain 512 frames, if this changes it will be fixed in processAudio.
    tempBuffer.mNumberChannels = 1;
    tempBuffer.mDataByteSize = 512 * 2;
    tempBuffer.mData = malloc( 512 * 2 );

    UInt32 audioCategory = kAudioSessionCategory_PlayAndRecord;
    status = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(audioCategory), &audioCategory);
    NSLog(@"%ld",(long)status);


    UInt32 allowMixing = true;
    status = AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(allowMixing), &allowMixing);

    UInt32 audioRouteOverride = kAudioSessionOutputRoute_BluetoothA2DP; //kAudioSessionOverrideAudioRoute_Speaker;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);

    status = AudioUnitInitialize(audioUnit);
    checkStatus(status);

    return self;
}

- Avi The Undertaker

---

你不能这样做。我曾经尝试过同样的事情，说实话，我能够追踪到右上角的麦克风，以便将输入路由到扬声器输出。就蓝牙而言，据我所知，它是成对出现的——即对于蓝牙输入，您应该有蓝牙输出，反之亦然。 - madLokesh

use-audio-unit-i-o-to-create-audio-on-the-fly - madLokesh

AudioUnitSetProperty已被弃用，您应该使用AVAudioSession的适当方法。同时请查看此类似问题。 - Terry

刚刚与苹果确认，这是不可能实现的。蓝牙始终成对出现，麦克风和扬声器一起连接。;) - Avi The Undertaker

Answer 1

我已经向苹果确认过了。这是不可能实现的。蓝牙始终需要同时配对麦克风和扬声器;)

- Avi The Undertaker

Answer 2

这是完全可行的（我已经在我的一个应用程序中实现了这一点）。只需使用以下代码更改输出音频路由即可。

+ (void) startBTAudio
{
    UInt32 allowBluetoothInput = 1;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryEnableBluetoothInput, sizeof(allowBluetoothInput), &allowBluetoothInput);  
}


+ (void) stopBTAudio
{
    UInt32 allowBluetoothInput = 0;
    AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryEnableBluetoothInput, sizeof(allowBluetoothInput), &allowBluetoothInput);
}

- Partho Biswas