ios - captureOutput() 函数从未被调用 swift4

Question

我正在尝试实时捕获相机帧，以便使用 Firebase ML KIT 进行处理。我已成功显示相机 View ，但似乎无法调用 captureOutput 委托(delegate)函数。

P.s 我是 iOS 开发新手。

private func startLiveVideo() {

    self.session.sessionPreset = AVCaptureSession.Preset.photo
    let captureDevice = AVCaptureDevice.default(for: AVMediaType.video)
    let deviceInput = try! AVCaptureDeviceInput(device: captureDevice!)

     self.session.addInput(deviceInput)

    let deviceOutput = AVCaptureVideoDataOutput()

    deviceOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA)]
    deviceOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "videoQueue"))

    self.session.addOutput(AVCaptureVideoDataOutput())
    let imageLayer = AVCaptureVideoPreviewLayer(session: session)


    imageLayer.frame = CGRect(x: 0, y: 0, width: self.imageView.frame.size.width + 100, height: self.imageView.frame.size.height)
    imageLayer.videoGravity = .resizeAspectFill
    imageView.layer.addSublayer(imageLayer)

    self.session.startRunning()

}

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
    print("Frame captured")
}

Answer 1

您添加代表

let deviceOutput = AVCaptureVideoDataOutput() 
deviceOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA)]
deviceOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "videoQueue"))

但在此处添加另一个实例

self.session.addOutput(AVCaptureVideoDataOutput())

所以将其替换为

self.session.addOutput(deviceOutput)