Question

在我的应用中，我需要检测脸部并记录每5秒持续时间的3组视频。基本上用于前，左和右脸。我已经使用Firebase MLKit成功检测到人脸，并且一切正常，现在只需要录制视频即可。因此，当用户使用录制功能时，他可以选择录制视频，因此，如果正确检测到正面，则将开始5秒钟的录制，并在5秒钟后提示用户将脸部方向更改为右，然后再进行录制，即为左。我正在使用AVAssetWriter进行录制。我可以录制，但问题是最终输出，其中包括完整的持续时间，包括第二次录制未开始的时间。因此，我当前的最终输出有5秒的正面视频，之后该帧显示为卡住了一段时间，然后播放了接下来的5秒的视频，依此类推。因此，总持续时间现在显示超过1分钟！ AVAssetWriter似乎没有暂停，我是刚接触AVAssetWriter的人，所以不确定在这里做错了什么，下面是我的代码供参考。基本上，我使用的是isRecording变量，并且当录制处于非活动状态时，我不会调用该方法来编写帧。

fileprivate var videoWriterInput: AVAssetWriterInput!

func captureOutput(
    _ output: AVCaptureOutput,
    didOutput sampleBuffer: CMSampleBuffer,
    from connection: AVCaptureConnection
) {
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
        print("Failed to get image buffer from sample buffer.")
        return
    }
    if isRecording {
            let writable = canWrite()
            if writable,
                sessionAtSourceTime == nil {
                sessionAtSourceTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
                videoWriter.startSession(atSourceTime: sessionAtSourceTime!)
            }

            if writable,
                (videoWriterInput.isReadyForMoreMediaData) {
                videoWriterInput.append(sampleBuffer)
            }
        }

}

func startRecording() {
        guard !isRecording else { return }
        isRecording = true
        sessionAtSourceTime = nil
        setUpWriter()
        startTimer()
    }

func stopRecording() {
        videoWriterInput.markAsFinished()
        videoWriter.finishWriting { [weak self] in
            self?.sessionAtSourceTime = nil
            if self?.videoWriter.status == .writing {
                print("status writing")
            } else if self?.videoWriter.status == .failed {
                print("status failed")
            } else if self?.videoWriter.status == .cancelled {
                print("status cancelled")
            } else if self?.videoWriter.status == .unknown {
                print("status unknown")
            } else {
                print("status completed")
                self?.showVideo()
            }
        }
        captureSession.stopRunning()
    }

func setUpWriter() {
        do {
            outputFileLocation = videoFileLocation()
            videoWriter = try AVAssetWriter(outputURL: outputFileLocation, fileType: AVFileType.mp4)
            let vidSize = getVideoSize()
                videoWriterInput = AVAssetWriterInput(mediaType: AVMediaType.video, outputSettings: [
                    AVVideoCodecKey : AVVideoCodecH264,
                    AVVideoWidthKey : NSNumber(value: Float(vidSize.width)),
                    AVVideoHeightKey : NSNumber(value: Float(vidSize.height)),
                    AVVideoCompressionPropertiesKey : [
                        AVVideoAverageBitRateKey : 2300000,
                    ],
                    ])

            videoWriterInput.expectsMediaDataInRealTime = true
            videoWriterInput.transform = getVideoTransform()

            if videoWriter.canAdd(videoWriterInput) {
                videoWriter.add(videoWriterInput)
                print("video input added")
            } else {
                print("no input added")
            }
            videoWriter.startWriting()
        } catch let error {
            debugPrint(error.localizedDescription)
        }
    }

    func canWrite() -> Bool {
        return isRecording && videoWriter != nil && videoWriter?.status == .writing
    }

在AVAssetwriter中暂停视频

0 个答案: