ios - 有没有办法将语音处理io音频单元路由到蓝牙设备？

Question

我正在开发一个应用程序，需要语音处理 io 音频单元来完成一些回声消除工作。它工作正常，但事实证明音频输出无法路由到蓝牙设备(它不是免提蓝牙设备，而是蓝牙立体声扬声器)。以下是我如何启动音频内容

AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_VoiceProcessingIO;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;

AudioComponent comp = AudioComponentFindNext(NULL, &desc);
AudioComponentInstanceNew(comp, &_audioUnit);

UInt32 one = 1;

AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = recordingCallback;
callbackStruct.inputProcRefCon = (__bridge void *)self;

AudioUnitSetProperty(_audioUnit, kAudioOutputUnitProperty_SetInputCallback,
                                 kAudioUnitScope_Global,
                                 kInputBus,
                                 &callbackStruct,
                                 sizeof(callbackStruct));

_audioFormat.mSampleRate = kSampleRate;
_audioFormat.mFormatID = kAudioFormatLinearPCM;
_audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
_audioFormat.mFramesPerPacket = 1;
_audioFormat.mChannelsPerFrame = 1;
_audioFormat.mBitsPerChannel = 16;
_audioFormat.mBytesPerPacket = 2;
_audioFormat.mBytesPerFrame = 2;

AudioUnitSetProperty(_audioUnit, kAudioUnitProperty_StreamFormat,
                                 kAudioUnitScope_Output,
                                 kInputBus,
                                 &_audioFormat,
                                 sizeof(_audioFormat));
AudioUnitSetProperty(_audioUnit, kAudioUnitProperty_StreamFormat,
                                 kAudioUnitScope_Input,
                                 kOutputBus,
                                 &_audioFormat,
                                 sizeof(_audioFormat));
AudioUnitSetProperty(_audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, 1, &one, sizeof(one));
AudioUnitSetProperty(_audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Output, 0, &one, sizeof(one));


// Configure the audio session
AVAudioSession *sessionInstance = [AVAudioSession sharedInstance];
[sessionInstance setCategory:AVAudioSessionCategoryPlayAndRecord
                 withOptions:AVAudioSessionCategoryOptionDuckOthers | AVAudioSessionCategoryOptionAllowBluetooth
                       error:NULL];

[sessionInstance overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:nil];

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(handleRouteChange:)
                                             name:AVAudioSessionRouteChangeNotification
                                           object:nil];

[[AVAudioSession sharedInstance] setActive:YES error:NULL];
AudioUnitInitialize(_audioUnit);
AudioOutputUnitStart(_audioUnit);

我还将输出路由到扬声器，而不是默认的耳机扬声器，该扬声器的音量非常低。但是，我未能实现将输出路由到蓝牙。有人能帮我解决这个问题吗？谢谢。

Answer 1

所以这实际上取决于蓝牙设备的类型，无论是BluetoothHFP(输入和输出)、BluetoothA2DP(仅输出)还是BluetoothLE(仅输出)。如果设备仅输出，您将无法连接和路由 kAudioSessionCategory_PlayAndRecord 类别中的音频。