ios - 如何在 Swift 中使用 avfoundation 录制视频？

Question

我想弄清楚如何在 Swift 中使用 AVFoundation 录制视频。我已经创建了一个自定义相机，但我只知道如何用它拍摄静态照片，但我不知道如何录制视频。据我了解，您必须使用 AVCaptureVideoDataOutput 从录制中获取数据，但我不知道如何开始录制和实现委托(delegate)方法。

整个 AVFoundation 编程指南/静态和视频媒体捕获都在 Objective-C 中，我似乎无法破译它。这是我完成此任务的尝试:

首先我设置了相机/捕获 session

override func viewDidLoad() {
    super.viewDidLoad()

    captureSession.sessionPreset = AVCaptureSessionPresetHigh
    let devices = AVCaptureDevice.devices()
    for device in devices {
        if (device.hasMediaType(AVMediaTypeVideo)) {
            if(device.position == AVCaptureDevicePosition.Back) {
                captureDevice = device as? AVCaptureDevice
                if captureDevice != nil {
                    beginSession()
                }
            }
        }
    }

}

然后一旦 beginSession() 被调用，我就会设置实时提要

func beginSession() {
    var err : NSError? = nil
    captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err))
    if err != nil {
        println("error: \(err?.localizedDescription)")
    }
    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    self.cameraView.layer.addSublayer(previewLayer)
    self.cameraView.bringSubviewToFront(takePhotoButton)
    self.cameraView.bringSubviewToFront(self.snappedPicture)
    self.cameraView.bringSubviewToFront(self.backButton)
    previewLayer?.frame = self.cameraView.layer.frame
    captureSession.startRunning()
}

这是我卡在用户按下录制以实际录制和捕获视频的地方:

@IBAction func takeVideoAction(sender: AnyObject) {

    var recordingDelegate:AVCaptureFileOutputRecordingDelegate? = self

    var videoFileOutput = AVCaptureMovieFileOutput()
    self.captureSession.addOutput(videoFileOutput)

    let filePath = NSURL(fileURLWithPath: "filePath")

    videoFileOutput.startRecordingToOutputFileURL(filePath, recordingDelegate: recordingDelegate)

}

然后我调用 self.videoFileOutput.stopRecording()。

最后是委托(delegate)方法

func captureOutput(captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAtURL outputFileURL: NSURL!, fromConnections connections: [AnyObject]!, error: NSError!) {
    return
}

func captureOutput(captureOutput: AVCaptureFileOutput!, didStartRecordingToOutputFileAtURL fileURL: NSURL!, fromConnections connections: [AnyObject]!) {
    return
}

并没有像你想象的那样发生，因为我不知道如何正确地实现它。

Answer 1

我试过你的代码。当设置一个有意义的 filePath 时，一切都会好起来的。像这样更改您的 filePath，您将调用委托(delegate)方法:

    let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
    let filePath = documentsURL.URLByAppendingPathComponent("temp")

    // Do recording and save the output to the `filePath`
    videoFileOutput.startRecordingToOutputFileURL(filePath, recordingDelegate: recordingDelegate)