视频采集篇

• 相关框架
  iOS中关于音视频的类都在AVFoundation,做音视频,首先导入这个框架

• 开发步骤

• 1创建捕捉会话（AVCaptureSession）

• 2设置视频输入源&输出源

• 3设置音频输入源&输出源

• 4添加预览图层（可选）

• 5开始采集即可

实现代码

class ViewController: UIViewController {
    
    fileprivate lazy var session : AVCaptureSession = AVCaptureSession()
    fileprivate var videoOutput : AVCaptureVideoDataOutput?
    fileprivate var previewLayer : AVCaptureVideoPreviewLayer?
    fileprivate var videoInput : AVCaptureDeviceInput?
    fileprivate var movieOutput : AVCaptureMovieFileOutput?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 1.初始化视频的输入&输出
        setupVideoInputOutput()
        
        // 2.初始化音频的输入&输出
        setupAudioInputOutput()
        
        // 3.初始化一个预览图层
        setupPreviewLayer()
    }

    @IBAction func rotateCamera() {
        // 1.取出之前镜头的方向
        guard let videoInput = videoInput else {
            return
        }
        let postion : AVCaptureDevicePosition = videoInput.device.position == .front ? .back : .front
        guard let devices = AVCaptureDevice.devices() as? [AVCaptureDevice] else { return }
        guard let device = devices.filter({ $0.position == postion }).first else { return }
        guard let newInput = try? AVCaptureDeviceInput(device: device) else { return }
        
        
        // 2.移除之前的input, 添加新的input
        session.beginConfiguration()
        session.removeInput(videoInput)
        if session.canAddInput(newInput) {
            session.addInput(newInput)
        }
        session.commitConfiguration()
        
        // 3.保存最新的input
        self.videoInput = newInput
    }
}


// MARK:- 对采集的控制器方法
extension ViewController {
    @IBAction func startCapturing() {
        session.startRunning()
        
        setupPreviewLayer()
        
        // 录制视频, 并且写入文件
        setupMovieFileOutput()
    }
    
    @IBAction func stopCapturing() {
        
        movieOutput?.stopRecording()
        
        session.stopRunning()
        previewLayer?.removeFromSuperlayer()
    }
}


// MARK:- 初始化方法
extension ViewController {
    fileprivate func setupVideoInputOutput() {
        // 1.添加视频的输入
        guard let devices = AVCaptureDevice.devices() as? [AVCaptureDevice] else { return }
        guard let device = devices.filter({ $0.position == .front }).first else { return }
        guard let input = try? AVCaptureDeviceInput(device: device) else { return }
        self.videoInput = input
        
        // 2.添加视频的输出
        let output = AVCaptureVideoDataOutput()
        let queue = DispatchQueue.global()
        output.setSampleBufferDelegate(self, queue: queue)
        self.videoOutput = output
        
        // 3.添加输入&输出
        addInputOutputToSesssion(input, output)
    }
    
    fileprivate func setupAudioInputOutput() {
        // 1.创建输入
        guard let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeAudio) else { return }
        guard let input = try? AVCaptureDeviceInput(device: device) else { return }
        
        // 2.创建输出
        let output = AVCaptureAudioDataOutput()
        let queue = DispatchQueue.global()
        output.setSampleBufferDelegate(self, queue: queue)
        
        // 3.添加输入&输出
        addInputOutputToSesssion(input, output)
    }
    
    private func addInputOutputToSesssion(_ input : AVCaptureInput, _ output : AVCaptureOutput) {
        session.beginConfiguration()
        if session.canAddInput(input) {
            session.addInput(input)
        }
        if session.canAddOutput(output) {
            session.addOutput(output)
        }
        session.commitConfiguration()
    }
    
    fileprivate func setupPreviewLayer() {
        // 1.创建预览图层
        guard let previewLayer = AVCaptureVideoPreviewLayer(session: session) else { return }
        
        // 2.设置previewLayer属性
        previewLayer.frame = view.bounds
        
        // 3.将图层添加到控制器的View的layer中
        view.layer.insertSublayer(previewLayer, at: 0)
        self.previewLayer = previewLayer
    }
    
    fileprivate func setupMovieFileOutput() {
        
        session.removeOutput(self.movieOutput)
        
        // 1.创建写入文件的输出
        let fileOutput = AVCaptureMovieFileOutput()
        self.movieOutput = fileOutput
        
        let connection = fileOutput.connection(withMediaType: AVMediaTypeVideo)
        connection?.automaticallyAdjustsVideoMirroring = true
        
        if session.canAddOutput(fileOutput) {
            session.addOutput(fileOutput)
        }
        
        // 2.直接开始写入文件
        let filePath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first! + "/abc.mp4"
        let fileURL = URL(fileURLWithPath: filePath)
        fileOutput.startRecording(toOutputFileURL: fileURL, recordingDelegate: self)
    }
}


//通过代理监听采集的数据,可在这里使用GPUimage进行美颜处理
extension ViewController : AVCaptureVideoDataOutputSampleBufferDelegate, AVCaptureAudioDataOutputSampleBufferDelegate {
    func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
        if videoOutput?.connection(withMediaType: AVMediaTypeVideo) == connection {
            print("视频")
        } else {
            print("音频")
        }
    }
}


// MARK:- 通过代理监听开始写入文件, 以及结束写入文件
extension ViewController : AVCaptureFileOutputRecordingDelegate {
    func capture(_ captureOutput: AVCaptureFileOutput!, didStartRecordingToOutputFileAt fileURL: URL!, fromConnections connections: [Any]!) {
        print("开始写入")
    }
    
    func capture(_ captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAt outputFileURL: URL!, fromConnections connections: [Any]!, error: Error!) {
        print("完成写入")
    }
}