如何仅在录制时将音频输入添加到AVCaptureSession,而不中断视频预览?

我的捕获会话初始化相当一般,所以我不会粘贴它(值得注意的是,我已经 captureSession.automaticallyConfiguresApplicationAudioSession = false line和shared AVAudioSession的修改如下 AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord, mode: AVAudioSessionModeVideoRecording, options: [.mixWithOthers]) ),但我将发布切换音频输入的尝试:

func addAudioInput() {
    self.sessionQueue.async { [unowned self] in
        self.captureSession.beginConfiguration()
        let microphone = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeAudio)
        if let audioInput = try? AVCaptureDeviceInput(device: microphone), self.captureSession.canAddInput(audioInput) {
            self.captureSession.addInput(audioInput)
        }
        self.captureSession.commitConfiguration()
    }
}

func removeAudioInput() {
    self.sessionQueue.async { [unowned self] in
        if let audioInput = self.captureSession.inputs.first(where: { ($0 as? AVCaptureDeviceInput)?.device.deviceType == .builtInMicrophone }) as? AVCaptureDeviceInput {
            self.captureSession.beginConfiguration()
            self.captureSession.removeInput(audioInput)
            self.captureSession.commitConfiguration()
        }
    }
}