我使用AVCaptureVideoDataOutputSampleBufferDelegate和函数**func captureOutput（_ output：AVCaptureOutput，didOutput sampleBuffer：CMSampleBuffer，来自连接：AVCaptureConnection）**我使用AVAssetWriter将接收到的CMSampleBuffers作为视频保存保存到生成的url。我需要让用户看到不断更新的录制视频的能力。我使用calculateSampleBufferSize函数累积CMSampleBuffer以显示，但结果不准确。有人知道如何从CMSampleBuffer中正确计算它吗？谢谢
下面是我实现的代码

func writeBufferVideoToFile(assetWriter: AVAssetWriter,
                                sampleBuffer: CMSampleBuffer) {
        guard isRecoding else {
            return
        }
        // Setup start record
        if assetWriter.status == .unknown {
            totalBytesWritten = 0
            assetWriter.startWriting()
            assetWriter.startSession(atSourceTime: CMSampleBufferGetPresentationTimeStamp(sampleBuffer))
        }
        // Record data
        if let assetWriterInput = assetWriter.currentInput,
           assetWriterInput.isReadyForMoreMediaData {
            // Calculate the total number of bytes written
            totalBytesWritten += Double(calculateSampleBufferSize(sampleBuffer: sampleBuffer))
            // Record
            assetWriterInput.append(sampleBuffer)
        }
    }

    func calculateSampleBufferSize(sampleBuffer: CMSampleBuffer) -> Int {
        guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
            return 0
        }
        
        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
        let size = CVPixelBufferGetDataSize(imageBuffer)
        CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
        
        return size
    }