ios - 在 swift 4 中使用摄像头进行实时面部跟踪

Question

我希望能够从摄像头源中跟踪用户的面部。我看过this所以发帖。我使用了答案中给出的代码，但它似乎没有做任何事情。听说过

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!)

已在 swift 4 中更改为其他内容。这可能是代码的问题吗？

在进行面部跟踪时，我还想使用 CIFaceFeature 监控面部特征。我该怎么做？

Answer 1

我在这里找到了一个起点:https://github.com/jeffreybergier/Blog-Getting-Started-with-Vision .

基本上，您可以像这样声明一个惰性变量来实例化视频捕获 session :

private lazy var captureSession: AVCaptureSession = {
    let session = AVCaptureSession()
    session.sessionPreset = AVCaptureSession.Preset.photo
    guard
        let frontCamera = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front),
        let input = try? AVCaptureDeviceInput(device: frontCamera)
        else { return session }
    session.addInput(input)
    return session
}()

然后在 viewDidLoad 中启动 session

self.captureSession.startRunning()

最后你可以在里面执行你的请求

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

例如:

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: 
    CMSampleBuffer, from connection: AVCaptureConnection) {
    guard
        // make sure the pixel buffer can be converted
        let pixelBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
        else { return }

    let faceRequest = VNDetectFaceRectanglesRequest(completionHandler: self.faceDetectedRequestUpdate)

    // perform the request
    do {
        try self.visionSequenceHandler.perform([faceRequest], on: pixelBuffer)
    } catch {
        print("Throws: \(error)")
    }
}

然后定义您的 faceDetectedRequestUpdate 函数。

无论如何，我不得不说，我无法弄清楚如何从这里创建一个工作示例。我找到的最好的工作示例在 Apple 的文档中:https://developer.apple.com/documentation/vision/tracking_the_user_s_face_in_real_time