RealityKit 中录制视频和音频并保存的实现方法详解

回答：

在 RealityKit 中录制视频和音频并保存是一个复杂的任务，因为 RealityKit 本身并不直接提供录制功能。你需要结合 AVFoundation 框架来实现这一功能。以下是一个详细的实现方法和代码示例。

步骤 1: 设置 RealityKit 视图

首先，设置一个 RealityKit 视图并加载一个简单的场景。

import UIKit
import RealityKit
import AVFoundation

class ViewController: UIViewController {
    var arView: ARView!
    var videoOutput: AVAssetWriter!
    var videoInput: AVAssetWriterInput!
    var audioInput: AVAssetWriterInput!
    var pixelBufferAdaptor: AVAssetWriterInputPixelBufferAdaptor!
    var isRecording = false

    override func viewDidLoad() {
        super.viewDidLoad()
        
        arView = ARView(frame: view.bounds)
        view.addSubview(arView)
        
        // 加载一个简单的 RealityKit 场景
        let boxAnchor = try! Experience.loadBox()
        arView.scene.anchors.append(boxAnchor)
    }
}

步骤 2: 设置视频录制

接下来，设置视频录制的相关配置。

extension ViewController {
    func startRecording() {
        let outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("output.mov")
        try? FileManager.default.removeItem(at: outputURL)
        
        videoOutput = try! AVAssetWriter(outputURL: outputURL, fileType: .mov)
        
        let videoSettings: [String: Any] = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: NSNumber(value: Float(arView.bounds.width)),
            AVVideoHeightKey: NSNumber(value: Float(arView.bounds.height))
        ]
        
        videoInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings)
        videoInput.expectsMediaDataInRealTime = true
        videoOutput.add(videoInput)
        
        let sourcePixelBufferAttributes: [String: Any] = [
            kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA),
            kCVPixelBufferWidthKey as String: NSNumber(value: Float(arView.bounds.width)),
            kCVPixelBufferHeightKey as String: NSNumber(value: Float(arView.bounds.height))
        ]
        
        pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoInput, sourcePixelBufferAttributes: sourcePixelBufferAttributes)
        
        videoOutput.startWriting()
        videoOutput.startSession(atSourceTime: .zero)
        
        isRecording = true
    }
    
    func stopRecording() {
        isRecording = false
        videoInput.markAsFinished()
        videoOutput.finishWriting {
            print("Video recording finished")
        }
    }
}

步骤 3: 设置音频录制

设置音频录制的相关配置。

extension ViewController {
    func setupAudioRecording() {
        let audioSettings: [String: Any] = [
            AVFormatIDKey: kAudioFormatMPEG4AAC,
            AVNumberOfChannelsKey: 1,
            AVSampleRateKey: 44100.0,
            AVEncoderBitRateKey: 64000
        ]
        
        audioInput = AVAssetWriterInput(mediaType: .audio, outputSettings: audioSettings)
        audioInput.expectsMediaDataInRealTime = true
        videoOutput.add(audioInput)
        
        let audioSession = AVAudioSession.sharedInstance()
        try! audioSession.setCategory(.playAndRecord, mode: .default, options: [])
        try! audioSession.setActive(true)
        
        let audioInputNode = audioSession.inputNode
        let recordingFormat = audioInputNode.outputFormat(forBus: 0)
        
        audioInputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer, time) in
            if self.isRecording {
                self.audioInput.append(buffer, withPresentationTime: time)
            }
        }
    }
}

步骤 4: 将视频和音频数据写入文件

在 RealityKit 的渲染循环中捕获视频帧并写入文件。

extension ViewController {
    func captureFrame() {
        guard isRecording else { return }
        
        let currentTime = CMTime(seconds: CACurrentMediaTime(), preferredTimescale: 600)
        
        if let pixelBufferPool = pixelBufferAdaptor.pixelBufferPool {
            var pixelBufferOut: CVPixelBuffer?
            CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pixelBufferOut)
            
            if let pixelBuffer = pixelBufferOut {
                let ciContext = CIContext()
                let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
                ciContext.render(ciImage, to: pixelBuffer)
                
                pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: currentTime)
            }
        }
    }
}

步骤 5: 启动和停止录制

在适当的地方调用启动和停止录制的方法。

extension ViewController {
    @IBAction func startButtonTapped(_ sender: UIButton) {
        startRecording()
        setupAudioRecording()
    }
    
    @IBAction func stopButtonTapped(_ sender: UIButton) {
        stopRecording()
    }
}

总结

以上代码展示了如何在 RealityKit 中结合 AVFoundation 实��视频和音频的录制。请注意，这只是一个基本的示例，实际应用中可能需要更多的错误处理和优化。希望这能帮助你实现你的需求。