如何使用 AVFoundation 和相机视图更改 fps 和隐藏状态栏

Question

我正在使用 AVFoundation 制作全屏相机视图。我似乎无法更改 fps 并隐藏状态栏。我希望将 fps 设置为 140 fps（对于 iPhone 7）并且我还希望隐藏状态栏（我已经在故事板文件和 Xcode 应用程序设置。我怎样才能做到这一点？提前致谢！（我正在使用 Swift 3.0，希望在 Swift 3（如果可能）中得到答案）

ViewController 代码：`class ViewController: UIViewController {

@IBOutlet var cameraView: UIImageView!
let captureSession = AVCaptureSession()
let stillImageOutput = AVCaptureStillImageOutput()
var previewLayer : AVCaptureVideoPreviewLayer?

var captureDevice : AVCaptureDevice?

func beginSession() {

    do {
        try captureSession.addInput(AVCaptureDeviceInput(device: captureDevice))
        stillImageOutput.outputSettings = [AVVideoCodecKey:AVVideoCodecJPEG]

        if captureSession.canAddOutput(stillImageOutput) {
            captureSession.addOutput(stillImageOutput)
        }

    }
    catch {
        print("error: \(error.localizedDescription)")
    }

    guard let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession) else {
        print("no preview layer")
        return
    }

    self.view.layer.addSublayer(previewLayer)
    previewLayer.frame = self.view.layer.frame
    captureSession.startRunning()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    captureSession.sessionPreset = AVCaptureSessionPresetHigh

    if let devices = AVCaptureDevice.devices() as? [AVCaptureDevice] {
        // Loop through all the capture devices on this phone
        for device in devices {
            // Make sure this particular device supports video
            if (device.hasMediaType(AVMediaTypeVideo)) {
                // Finally check the position and confirm we've got the back camera
                if(device.position == AVCaptureDevicePosition.back) {
                    captureDevice = device
                    if captureDevice != nil {
                        print("Capture device found")
                        beginSession()
                    }
                }
            }
        }
    }


} 

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

`

Answer 1

1) 要隐藏状态栏，您应该添加对 UIViewController 的 prefersStatusBarHidden: 方法的覆盖：

override var prefersStatusBarHidden : Bool {
    return true
}

2) 要设置恒定 FPS，您可以使用 AVCaptureDevice 实例的 activeVideoMinFrameDuration and activeVideoMaxFrameDuration 属性：

func setFrameRate(_ captureDevice: AVCaptureDevice) {
    do {
        try captureDevice.lockForConfiguration()
        captureDevice.activeVideoMinFrameDuration = CMTimeMake(1, 140)
        captureDevice.activeVideoMaxFrameDuration = CMTimeMake(1, 140)
        captureDevice.unlockForConfiguration()
    } catch {
        NSLog("An Error occurred: \(error.localizedDescription))")
    }
}

如何使用 AVFoundation 和相机视图更改 fps 和隐藏状态栏

How to change fps and hide status bar using AVFoundation and a camera view

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