Swift 4-在Mac OS上使用AVAssetWriter进行AVFoundation屏幕和音频录制-视频冻结 [英] Swift 4 - avfoundation screen and audio recording using AVAssetWriter on mac os - video frozen

问题描述

我正在使用Aperture在屏幕上录制音频和视频.我们需要降低视频的比特率，所以我试图重写它并使用AVAssetWriter录制视频.我的实现基于CustomCamera项目，并且几乎可以正常工作.问题出在视频中，虽然音频在起作用，但几秒钟后就被冻结了.请问你能帮帮我吗?我不知道问题出在哪里，也许这是缓冲区或垃圾收集器收集一些变量的问题.谢谢.

I'm using Aperture to record audio and video from screen. We need to lower the bitrate of video, so i'm trying to rewrite it and record video with AVAssetWriter. My implementation is based on CustomCamera project and is almost working. The problem is in video, after few seconds it is frozen, althought audio is working. Could you help me please? I dont know where the problem is, maybe it is problem with buffers or garbage collector collect some variable. thanks.

这是代码:

//
//  ViewController.swift
//  CustomCamera
//
//  Created by Taras Chernyshenko on 6/27/17.
//  Copyright © 2017 Taras Chernyshenko. All rights reserved.
//
import AVFoundation
import Photos

class NewRecorder: NSObject,
  AVCaptureAudioDataOutputSampleBufferDelegate,
AVCaptureVideoDataOutputSampleBufferDelegate {

  private var session: AVCaptureSession = AVCaptureSession()
  private var deviceInput: AVCaptureScreenInput?
  private var previewLayer: AVCaptureVideoPreviewLayer?
  private var videoOutput: AVCaptureVideoDataOutput = AVCaptureVideoDataOutput()
  private var audioOutput: AVCaptureAudioDataOutput = AVCaptureAudioDataOutput()

  //private var videoDevice: AVCaptureDevice = AVCaptureScreenInput(displayID: 69731840) //AVCaptureDevice.default(for: AVMediaType.video)!
  private var audioConnection: AVCaptureConnection?
  private var videoConnection: AVCaptureConnection?

  private var assetWriter: AVAssetWriter?
  private var audioInput: AVAssetWriterInput?
  private var videoInput: AVAssetWriterInput?

  private var fileManager: FileManager = FileManager()
  private var recordingURL: URL?

  private var isCameraRecording: Bool = false
  private var isRecordingSessionStarted: Bool = false

  private var recordingQueue = DispatchQueue(label: "recording.queue")


  func setup() {
    self.session.sessionPreset = AVCaptureSession.Preset.high

    self.recordingURL = URL(fileURLWithPath: "\(NSTemporaryDirectory() as String)/file.mp4")
    if self.fileManager.isDeletableFile(atPath: self.recordingURL!.path) {
      _ = try? self.fileManager.removeItem(atPath: self.recordingURL!.path)
    }

    self.assetWriter = try? AVAssetWriter(outputURL: self.recordingURL!,
                                          fileType: AVFileType.mp4)
    self.assetWriter!.movieFragmentInterval = kCMTimeInvalid
    self.assetWriter!.shouldOptimizeForNetworkUse = true

    let audioSettings = [
      AVFormatIDKey : kAudioFormatMPEG4AAC,
      AVNumberOfChannelsKey : 2,
      AVSampleRateKey : 44100.0,
      AVEncoderBitRateKey: 192000
      ] as [String : Any]

    let videoSettings = [
      AVVideoCodecKey : AVVideoCodecType.h264,
      AVVideoWidthKey : 1920,
      AVVideoHeightKey : 1080
      /*AVVideoCompressionPropertiesKey: [
        AVVideoAverageBitRateKey:  NSNumber(value: 5000000)
      ]*/
      ] as [String : Any]

    self.videoInput = AVAssetWriterInput(mediaType: AVMediaType.video,
                                         outputSettings: videoSettings)
    self.audioInput = AVAssetWriterInput(mediaType: AVMediaType.audio,
                                         outputSettings: audioSettings)

    self.videoInput?.expectsMediaDataInRealTime = true
    self.audioInput?.expectsMediaDataInRealTime = true

    if self.assetWriter!.canAdd(self.videoInput!) {
      self.assetWriter?.add(self.videoInput!)
    }

    if self.assetWriter!.canAdd(self.audioInput!) {
      self.assetWriter?.add(self.audioInput!)
    }

    //self.deviceInput = try? AVCaptureDeviceInput(device: self.videoDevice)
    self.deviceInput = AVCaptureScreenInput(displayID: 724042646)
    self.deviceInput!.minFrameDuration = CMTimeMake(1, Int32(30))
    self.deviceInput!.capturesCursor = true
    self.deviceInput!.capturesMouseClicks = true

    if self.session.canAddInput(self.deviceInput!) {
      self.session.addInput(self.deviceInput!)
    }

    self.previewLayer = AVCaptureVideoPreviewLayer(session: self.session)

    //importent line of code what will did a trick
    //self.previewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill

    //let rootLayer = self.view.layer
    //rootLayer.masksToBounds = true
    //self.previewLayer?.frame = CGRect(x: 0, y: 0, width: 1920, height: 1080)

    //rootLayer.insertSublayer(self.previewLayer!, at: 0)

    self.session.startRunning()

    DispatchQueue.main.async {
      self.session.beginConfiguration()

      if self.session.canAddOutput(self.videoOutput) {
        self.session.addOutput(self.videoOutput)
      }

      self.videoConnection = self.videoOutput.connection(with: AVMediaType.video)
      /*if self.videoConnection?.isVideoStabilizationSupported == true {
        self.videoConnection?.preferredVideoStabilizationMode = .auto
      }*/
      self.session.commitConfiguration()

      let audioDevice = AVCaptureDevice.default(for: AVMediaType.audio)
      let audioIn = try? AVCaptureDeviceInput(device: audioDevice!)

      if self.session.canAddInput(audioIn!) {
        self.session.addInput(audioIn!)
      }

      if self.session.canAddOutput(self.audioOutput) {
        self.session.addOutput(self.audioOutput)
      }

      self.audioConnection = self.audioOutput.connection(with: AVMediaType.audio)
    }
  }

  func startRecording() {
    if self.assetWriter?.startWriting() != true {
      print("error: \(self.assetWriter?.error.debugDescription ?? "")")
    }

    self.videoOutput.setSampleBufferDelegate(self, queue: self.recordingQueue)
    self.audioOutput.setSampleBufferDelegate(self, queue: self.recordingQueue)
  }

  func stopRecording() {
    self.videoOutput.setSampleBufferDelegate(nil, queue: nil)
    self.audioOutput.setSampleBufferDelegate(nil, queue: nil)

    self.assetWriter?.finishWriting {
      print("Saved in folder \(self.recordingURL!)")
      exit(0)
    }
  }
  func captureOutput(_ captureOutput: AVCaptureOutput, didOutput
    sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

    if !self.isRecordingSessionStarted {
      let presentationTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
      self.assetWriter?.startSession(atSourceTime: presentationTime)
      self.isRecordingSessionStarted = true
    }

    let description = CMSampleBufferGetFormatDescription(sampleBuffer)!

    if CMFormatDescriptionGetMediaType(description) == kCMMediaType_Audio {
      if self.audioInput!.isReadyForMoreMediaData {
        //print("appendSampleBuffer audio");
        self.audioInput?.append(sampleBuffer)
      }
    } else {
      if self.videoInput!.isReadyForMoreMediaData {
        //print("appendSampleBuffer video");
        if !self.videoInput!.append(sampleBuffer) {
          print("Error writing video buffer");
        }
      }
    }
  }
}

推荐答案

所以我通过移动此代码对其进行了修复

So I fixed it by moving this code

if self.session.canAddInput(self.deviceInput!) {
  self.session.addInput(self.deviceInput!)
}

在调用self.session.beginConfiguration()之后，所以

after the call self.session.beginConfiguration(), so

self.session.beginConfiguration()
  if self.session.canAddInput(self.deviceInput!) {
    self.session.addInput(self.deviceInput!)
  }

  if self.session.canAddOutput(self.videoOutput) {
    self.session.addOutput(self.videoOutput)
  }

  self.videoConnection = self.videoOutput.connection(with: AVMediaType.video)

  self.session.commitConfiguration()

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