AVAssetWriter 视频输出不播放附加音频

Question

我有一个 avassetwriter 可以录制带有应用滤镜的视频，然后通过 avqueueplayer 播放。

我的问题是音频输出附加到音频输入，但播放时没有声音播放。还没有遇到任何现有的解决方案，如果有任何可用的指导，我们将不胜感激..

其次，我必须循环播放的 .AVPlayerItemDidPlayToEndTime 通知观察器也没有触发..

AVCaptureSession 设置

func setupSession() {
    
    let session = AVCaptureSession()
    session.sessionPreset = .medium
    
    guard
        let camera = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front),
        let mic = AVCaptureDevice.default(.builtInMicrophone, for: .audio, position: .unspecified),
        let videoInput = try? AVCaptureDeviceInput(device: camera),
        let audioInput = try? AVCaptureDeviceInput(device: mic),
        session.canAddInput(videoInput), session.canAddInput(audioInput) else { return }
    
            
    let videoOutput = AVCaptureVideoDataOutput()
    let audioOutput = AVCaptureAudioDataOutput()
    guard session.canAddOutput(videoOutput), session.canAddOutput(audioOutput) else { return }
    let queue = DispatchQueue(label: "recordingQueue", qos: .userInteractive)
    videoOutput.setSampleBufferDelegate(self, queue: queue)
    audioOutput.setSampleBufferDelegate(self, queue: queue)
    
    session.beginConfiguration()
    
    session.addInput(videoInput)
    session.addInput(audioInput)
    session.addOutput(videoOutput)
    session.addOutput(audioOutput)
    
    session.commitConfiguration()
            
    if let connection = videoOutput.connection(with: AVMediaType.video) {
        if connection.isVideoStabilizationSupported { connection.preferredVideoStabilizationMode = .auto }
        connection.isVideoMirrored = true
        connection.videoOrientation = .portrait
    }
    
    _videoOutput = videoOutput
    _audioOutput = audioOutput
    _captureSession = session
    
    DispatchQueue.global(qos: .default).async { session.startRunning() }
}

AVAssetWriter 设置 + didOutput 委托

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
            
    let timestamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer).seconds

if output == _videoOutput {
    if connection.isVideoOrientationSupported { connection.videoOrientation = .portrait }
            
    guard let cvImageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
    let ciImage = CIImage(cvImageBuffer: cvImageBuffer)
    
    guard let filteredCIImage = applyFilters(inputImage: ciImage) else { return }
    self.ciImage = filteredCIImage
    
    guard let cvPixelBuffer = getCVPixelBuffer(from: filteredCIImage) else { return }
    self.cvPixelBuffer = cvPixelBuffer
            
    self.ciContext.render(filteredCIImage, to: cvPixelBuffer, bounds: filteredCIImage.extent, colorSpace: CGColorSpaceCreateDeviceRGB())
            
    metalView.draw()
   }
            
    switch _captureState {
    case .start:
        
        guard let outputUrl = tempURL else { return }
        
        let writer = try! AVAssetWriter(outputURL: outputUrl, fileType: .mp4)
        
        let videoSettings = _videoOutput!.recommendedVideoSettingsForAssetWriter(writingTo: .mp4)
        let videoInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings)
        videoInput.mediaTimeScale = CMTimeScale(bitPattern: 600)
        videoInput.expectsMediaDataInRealTime = true
        
        let pixelBufferAttributes = [
            kCVPixelBufferCGImageCompatibilityKey: NSNumber(value: true),
            kCVPixelBufferCGBitmapContextCompatibilityKey: NSNumber(value: true),
            kCVPixelBufferPixelFormatTypeKey: NSNumber(value: Int32(kCVPixelFormatType_32ARGB))
        ] as [String:Any]
        
        let adapter = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoInput, sourcePixelBufferAttributes: pixelBufferAttributes)
        if writer.canAdd(videoInput) { writer.add(videoInput) }
                                
        let audioSettings = _audioOutput!.recommendedAudioSettingsForAssetWriter(writingTo: .mp4) as? [String:Any]
        let audioInput = AVAssetWriterInput(mediaType: .audio, outputSettings: audioSettings)
        audioInput.expectsMediaDataInRealTime = true
        if writer.canAdd(audioInput) { writer.add(audioInput) }
    
        _filename = outputUrl.absoluteString
        _assetWriter = writer
        _assetWriterVideoInput = videoInput
        _assetWriterAudioInput = audioInput
        _adapter = adapter
        _captureState = .capturing
        _time = timestamp
                    
        writer.startWriting()
        writer.startSession(atSourceTime: .zero)
        
    case .capturing:
        
        if output == _videoOutput {
            if _assetWriterVideoInput?.isReadyForMoreMediaData == true {
                let time = CMTime(seconds: timestamp - _time, preferredTimescale: CMTimeScale(600))
                _adapter?.append(self.cvPixelBuffer, withPresentationTime: time)
            }
        } else if output == _audioOutput {
            if _assetWriterAudioInput?.isReadyForMoreMediaData == true {
                _assetWriterAudioInput?.append(sampleBuffer)
            }
        }
        break
        
    case .end:
        
        guard _assetWriterVideoInput?.isReadyForMoreMediaData == true, _assetWriter!.status != .failed else { break }
        
        _assetWriterVideoInput?.markAsFinished()
        _assetWriterAudioInput?.markAsFinished()
        _assetWriter?.finishWriting { [weak self] in
            
            guard let output = self?._assetWriter?.outputURL else { return }
            
            self?._captureState = .idle
            self?._assetWriter = nil
            self?._assetWriterVideoInput = nil
            self?._assetWriterAudioInput = nil
            
            
            self?.previewRecordedVideo(with: output)
        }
        
    default:
        break
    }
}

Answer 1

从您遇到的第一个音频或视频样本缓冲区的演示时间戳开始您的时间线：

writer.startSession(atSourceTime: CMSampleBufferGetPresentationTimeStamp(sampleBuffer))

之前您从零开始时间线，但捕获的样本缓冲区具有时间戳，通常似乎与自系统启动以来经过的时间量相关，因此在文件“开始”（ sourceTime for AVAssetWriter) 以及视频和音频出现时。

你的问题并没有说你不看视频，而且我希望一些视频播放器能够跳过一大堆内容直到您的样本开始的时间线，但无论如何文件都是错误的。

AVAssetWriter 视频输出不播放附加音频

AVAssetWriter Video Output Does Not Play Appended Audio

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