Watch OS :麦克风和音频处理

Question

是否可以访问手表麦克风并处理现场音频流，以获得特定信息(分贝水平和当前频率)？我知道使用swift presentAudioRecorderController可以在手表上录制音频。但是，我不想展示它附带的默认语音备忘录UI。即使我使用它，它也不能提供对实时流的访问。取而代之的是，我想在后台持续默默地听。

Answer 1

你当然可以只使用手表来记录。只需记住将相应的NSMicrophoneUsageDescription添加到plist中即可。

下面是一些可以帮助您入门的代码。然后，您可以从audioRecorder获得平均功率，并将其用于在UI上制作一些魔术。

    func startRecording () {
        if isRecording {
            recordButton.setBackgroundImage(UIImage(named: "stopImage"))
            let fileGuid = "\(UUID().uuidString)s.m4a"
            let audioFilename = getDocumentsDirectory().appendingPathComponent(fileGuid)
            fileOutputPath = audioFilename

            let audioSession = AVAudioSession.sharedInstance()
            do {
                try audioSession.setCategory(category, mode: .spokenAudio)
            } catch let sessionError {}

            let settings: [String: Int] = [
                AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
                AVSampleRateKey: 48000,
                AVEncoderBitRateKey: 256000,
                AVNumberOfChannelsKey: 2,
                AVEncoderAudioQualityKey: .max
            ]

            do {
                audioRecorder = try AVAudioRecorder(url: audioFilename, settings: settings)
                audioRecorder?.prepareToRecord()
                audioRecorder?.isMeteringEnabled = true
                audioRecorder?.record()
            } catch {}
        } else {
            recordButton.setBackgroundImage(UIImage(named: "recordImage"))
            do {
                try AVAudioSession.sharedInstance().setActive(false, options: .notifyOthersOnDeactivation)
            } catch let sessionError {
                print(sessionError)
            }
            audioRecorder?.stop()
            send()
        }
    }

    func send() {
        // waking app if its not running in the background
        session.sendMessage(["wake": "up"], replyHandler: { _ in
            self.session.transferFile(self.fileOutputPath, metadata: nil)
        }, errorHandler: { _ in
            // waking up device failed. Still, we should try putting the file into the queue so it eventually gets synced to the device
            self.session.transferFile(self.fileOutputPath, metadata: nil)
        })
    }