质量：自定义AVFoundation相机应用VS。iOS标准相机应用

Question

我使用各种主题和灯光进行了许多测试。每次测试都显示标准的iOS相机应用质量比我自定义的基于AVFoundation的应用明显更好（颜色不褪色，聚焦更好，照明更好，颗粒感更小）。我无法解释巨大的差异。以下是使用两种方法（使用前置摄像头）拍摄的视频的屏幕截图示例。

iOS标准相机应用

自定义AVFoundation录制的视频

自定义实现的代码：

let chosenCameraType = AVCaptureDevicePosition.Front

//get camera
let devices = AVCaptureDevice.devices()
for device in devices
{
    if (!device.hasMediaType(AVMediaTypeVideo))
    {
        continue
    }

    if (device.position != chosenCameraType)
    {
        continue
    }

    camera = (device as? AVCaptureDevice)!
}

do
{
    captureSession = AVCaptureSession()
    captureSession!.sessionPreset = AVCaptureSessionPresetHigh      

    let video = try AVCaptureDeviceInput(device: camera) as AVCaptureDeviceInput
    captureSession!.addInput(video)

    let audio = try AVCaptureDeviceInput(device: AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeAudio)) as AVCaptureDeviceInput
    captureSession!.addInput(audio)

    fileOutput = AVCaptureMovieFileOutput()
    captureSession?.addOutput(fileOutput)

    captureSession!.startRunning()

    let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString

    let name = String(UInt64(NSDate().timeIntervalSince1970 * 1000))
    fileOutput?.startRecordingToOutputFileURL(NSURL(fileURLWithPath: "\(documentsPath)/" + name + ".mov"), recordingDelegate: self)
}
catch let error as NSError
{
    print(error)
}

请试试！您也会看到差异...

Answer 1

我注意到你所描述的内容并查看你的代码，我没有看到你实现：

backCamera.focusPointOfInterest = focusPoint
backCamera.focusMode = AVCaptureFocusMode.autoFocus
backCamera.exposureMode = AVCaptureExposureMode.autoExpose

我在内部实现了这一点touchesBegan，以便相机能够聚焦在用户触摸屏幕的区域。这是该部分代码：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touchPoint = touches.first
        let x = (touchPoint?.location(in: self.view).x)! / self.view.bounds.width
        let y = (touchPoint?.location(in: self.view).y)! / self.view.bounds.height

        let realX = (touchPoint?.location(in: self.view).x)!
        let realY = (touchPoint?.location(in: self.view).y)!

        let focusPoint = CGPoint(x: x, y: y)

        let k = DrawSquare(frame: CGRect(
            origin: CGPoint(x: realX - 75, y: realY - 75),
            size: CGSize(width: 150, height: 150)))


        if backCamera != nil {
            do {
                try backCamera.lockForConfiguration()
                self.previewView.addSubview(k)
            }
            catch {
                print("Can't lock back camera for configuration")
            }
            if backCamera.isFocusPointOfInterestSupported {
                backCamera.focusPointOfInterest = focusPoint
            }
            if backCamera.isFocusModeSupported(AVCaptureDevice.FocusMode.autoFocus) {
                backCamera.focusMode = AVCaptureDevice.FocusMode.autoFocus
            }
            if backCamera.isExposureModeSupported(AVCaptureDevice.ExposureMode.autoExpose) {
                backCamera.exposureMode = AVCaptureDevice.ExposureMode.autoExpose
            }
            backCamera.unlockForConfiguration()

        }
        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(500)) {
            k.removeFromSuperview()
        }
    }

当相机显示暗图像时，用户只需点击屏幕，它就会调整曝光和焦距，使图片变亮。