（Swift）将视频输出保存到文件

Question

I'm capturing video, audio, and photos in one view controller, ideally with one capture session.

The issue I'm currently having is with recording video. It displays output to my preview fine. I have the AVCaptureFileOutputRecordingDelegate enabled and the following method implemented.

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

---

var outputUrl = NSURL(fileURLWithPath: NSTemporaryDirectory() + "test.mp4")
movieOutput?.startRecordingToOutputFileURL(outputUrl, recordingDelegate: self)

I'm getting this error when I run the above code though:

'NSInvalidArgumentException', reason: '*** -[AVCaptureMovieFileOutput startRecordingToOutputFileURL:recordingDelegate:] - no active/enabled connections.'

My configuration:

func configureCaptureSession() {
    capturedPhoto.contentMode = .ScaleAspectFill
    capturedPhoto.clipsToBounds = true
    capturedPhoto.hidden = true

    captureSession = AVCaptureSession()

    captureSession!.beginConfiguration()

    captureSession!.sessionPreset = AVCaptureSessionPresetPhoto


    var error: NSError?

    AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryRecord, error: &error)
    AVAudioSession.sharedInstance().setActive(true, error: &error)

    var audioDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeAudio)
    var audioInput = AVCaptureDeviceInput(device: audioDevice, error: &error)

    if error == nil && captureSession!.canAddInput(audioInput) {
        captureSession!.addInput(audioInput)
    }

    photoCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
    photoDeviceInput = AVCaptureDeviceInput(device: photoCaptureDevice, error: &error)

    if error == nil && captureSession!.canAddInput(photoDeviceInput) {
        captureSession!.addInput(photoDeviceInput)

        stillImageOutput = AVCaptureStillImageOutput()
        stillImageOutput!.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]
        if captureSession!.canAddOutput(stillImageOutput) {
            captureSession!.addOutput(stillImageOutput)
        }

        movieOutput = AVCaptureMovieFileOutput()
        if captureSession!.canAddOutput(movieOutput) {
            captureSession!.addOutput(movieOutput)
        }

        photoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        photoPreviewLayer!.videoGravity = AVLayerVideoGravityResizeAspectFill
        photoPreviewLayer!.connection?.videoOrientation = AVCaptureVideoOrientation.Portrait

        cameraView.layer.addSublayer(photoPreviewLayer)

        contentView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "focusPhoto:"))

    }

    captureSession!.commitConfiguration()
    captureSession!.startRunning()
}

Answer 1

I found two problems in your code.

Duplicated file

As per Apple documentation of startRecordingToOutputFileURL:recordingDelegate: :

Starts recording to a given URL. The method sets the file URL to which the receiver is currently writing output media. If a file at the given URL already exists when capturing starts, recording to the new file will fail.

In iOS, this frame accurate file switching is not supported. You must call stopRecording before calling this method again to avoid any errors. When recording is stopped either by calling stopRecording, by changing files using this method, or because of an error, the remaining data that needs to be included to the file will be written in the background. Therefore, you must specify a delegate that will be notified when all data has been written to the file using the captureOutput:didFinishRecordingToOutputFileAtURL:fromConnections:error: method.

In your case, if test.mp4 is already exist when you start a new recording, it will fail. So it's better to give the recorded file an unique name each time. For example, use the current timestamp.

Session preset

In your code, you set sessionPreset to AVCaptureSessionPresetPhoto :

captureSession!.sessionPreset = AVCaptureSessionPresetPhoto

But according to my personal experience, it is not suitable for an video output and will result in your error. Change to AVCaptureSessionPresetHigh and try again. Also it's recommended to call canSetSessionPreset: and apply the preset only if canSetSessionPreset: returns YES .

Sample code

Apple offers a nice sample code on the usage of AVFoundation , you may want to check it out.