iOS：创建简单的音频波形动画

我正在尝试用AVAudioRecorder录制音频.我需要创建一个这样的简单波形：

当用户对着麦克风说话时,圆圈表示用户语音的等级.我尝试使用此代码测量语音,但代码未检测到任何缓冲区而无法正常工作：

func levelTimerCallback(timer:Timer) {

    //we have to update meters before we can get the metering values
    audioRecorder.updateMeters()

    //print to the console if we are beyond a threshold value. Here I've used -7
    if audioRecorder.averagePower(forChannel: 1) > -7 {

        print(" level I'm hearin' you in dat mic ")
        print(audioRecorder.averagePower(forChannel: 0))
    }
}

录制音频：

func startRecording() {

        let audioSession = AVAudioSession.sharedInstance()
        do {

       // Audio Settings
            settings = [
                AVFormatIDKey: Int(kAudioFormatMPEG4AAC),AVSampleRateKey: 12000,AVNumberOfChannelsKey: 1,AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
            ]


            audioRecorder = try AVAudioRecorder(url: self.directoryURL(),settings: settings)
            audioRecorder.delegate = self
            audioRecorder.preparetoRecord()
            audioRecorder.isMeteringEnabled = true


        } catch {

            finishRecording(success: false)
        }

        do {

            try audioSession.setActive(true)
            audioRecorder.record()

            TIMERRRRR = Timer.scheduledTimer(timeInterval: 0.02,target: self,selector: #selector(ViewController.levelTimerCallback),userInfo: nil,repeats: true)

        } catch {

        }

    }

解决方法

我能看到的两个问题.

第一个是您在函数levelTimerCallback中使用错误的通道编号进行测试.您的测试应该是针对频道0.

另一个是-7的值实际上非常响亮. averagePower返回介于-160和0之间的浮点数.尝试针对-160进行测试以开始并增加该值以降低灵敏度.

这会将您的测试更改为：

if audioRecorder.averagePower(forChannel: 1) > -160 {
    ...
}

输入只有一个通道,计数从0开始.稍后您在调用audioRecorder.averagePower时就可以了.

要获得线性比例,您需要进行插值.更改比例值以更改范围.比例将介于0和比例之间.

let lowerLimit: Float = -100.0

func levelTimerCallback(timer:Timer) {

    audioRecorder.updateMeters()

    let power = audioRecorder.averagePower(forChannel: 0)
    if power > lowerLimit {
        // proportion will have a value between 0 and scale
        let scale: Float = 10.0
        let proportion = -scale * (power - lowerLimit) / lowerLimit
    }
}

编辑：修正比例计算