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