iOS - 采集音视频及写入文件

// 懒加载一个session，所有的操作都需要session来执行
fileprivate lazy var session: AVCaptureSession = AVCaptureSession()
// 保存�视频输出
fileprivate var videoOutput: AVCaptureVideoDataOutput?
// 保存视频输入
fileprivate var videoInput: AVCaptureDeviceInput?
// 保存预览图层
fileprivate var previewLayer: AVCaptureVideoPreviewLayer?

// 设置视频输入源
guard let devices = AVCaptureDevice.devices() as? [AVCaptureDevice] else { return }
// 获取我们的前置摄像头(后置为.back)
guard let device = devices.filter({ $0.position == .front }).first else { return }
guard let input = try? AVCaptureDeviceInput(device: device) else { return }
self.videoInput = input

// 设置视频输出源
let output = AVCaptureVideoDataOutput()
let queue = DispatchQueue.global()
// 设置代理，并在代理中获取采集到的数据，需要遵守 AVCaptureVideoDataOutputSampleBufferDelegate
output.setSampleBufferDelegate(self, queue: queue)
self.videoOutput = output

// 设置音频的输入源
guard let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeAudio) else { return }
guard let input = try? AVCaptureDeviceInput(device: device) else {return}

// 设置音频输出源
let output = AVCaptureAudioDataOutput()
let queue = DispatchQueue.global()
// 需要遵守 AVCaptureAudioDataOutputSampleBufferDelegate
output.setSampleBufferDelegate(self, queue: queue)

// 添加输入与输出

// 注意：每次对session进行设置之前都需要调用session的【beginConfiguration】方法
// 来告诉系统你现在要开始进行配置，结束配置后再调用【commitConfiguration】方法来提交配置
session.beginConfiguration()
if session.canAddInput(input) {
    session.addInput(input)
}
if session.canAddOutput(output) {
    session.addOutput(output)
}
session.commitConfiguration()

// This convenience method returns the first AVCaptureConnection in the receiver's
// connections array that has an AVCaptureInputPort of the specified mediaType. If 
// no connection with the specified mediaType is found, nil is returned.

open func connection(withMediaType mediaType: String!) -> AVCaptureConnection!

extension ViewController: AVCaptureVideoDataOutputSampleBufferDelegate, AVCaptureAudioDataOutputSampleBufferDelegate {
    func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
        if videoOutput?.connection(withMediaType: AVMediaTypeVideo) == connection {
            print("视频数据")
        } else {
            print("音频数据")
        }
    }
}

// 创建预览图层
guard let previewLayer = AVCaptureVideoPreviewLayer(session: session) else {return}
previewLayer.frame = view.bounds

// 将图层添加到控制器的view的layer中
view.layer.insertSublayer(previewLayer, at: 0)
self.previewLayer = previewLayer

// 开始录制
session.startRunning()
// 结束录制
session.stopRunning()

// 1.取出之前镜头的方向
guard let videoInput = videoInput else { return }
let position: AVCaptureDevicePosition = videoInput.device.position == .front ? .back : .front

guard let devices = AVCaptureDevice.devices() as? [AVCaptureDevice] else { return }
guard let device = devices.filter({ $0.position == position }).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

fileprivate var movieOutput: AVCaptureMovieFileOutput?

// 开始写入文件 

// 1、创建写入文件的输出
let fileOutput = AVCaptureMovieFileOutput()
self.movieOutput = fileOutput // 保存起来，用于停止写入文件

// 设置类型，不然报错(这两句很重要)
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)

// 停止写入文件
movieOutput?.stopRecording()