Apple Immersive Video Live Production Tools

import AVFoundation
import VideoToolbox
import CoreMedia

class ImmersiveLiveRecorder {
    private var assetWriter: AVAssetWriter?
    private var videoInput: AVAssetWriterInput?
    private let outputURL: URL

    init(outputURL: URL) {
        self.outputURL = outputURL
    }

    func startRecording(width: Int, height: Int, frameRate: CMTimeScale) throws {
        // Remove any existing file at the output URL
        try? FileManager.default.removeItem(at: outputURL)

        let writer = try AVAssetWriter(outputURL: outputURL, fileType: .mov)

        // ProRes 4444 for maximum fidelity — matches live 2110-22 stream payload
        let videoSettings: [String: Any] = [
            AVVideoCodecKey: AVVideoCodecType.proRes4444,
            AVVideoWidthKey: width,
            AVVideoHeightKey: height,
            AVVideoCompressionPropertiesKey: [
                // Required: marks the MOV as Apple Immersive Video (writes vexu box)
                kVTProjectionKind_AppleImmersiveVideo as String: true
            ] as [String: Any]
        ]

        let input = AVAssetWriterInput(
            mediaType: .video,
            outputSettings: videoSettings
        )
        input.expectsMediaDataInRealTime = true  // Critical for live production

        guard writer.canAdd(input) else {
            throw RecorderError.cannotAddInput
        }
        writer.add(input)

        self.assetWriter = writer
        self.videoInput = input

        writer.startWriting()
        writer.startSession(atSourceTime: .zero)
    }

    /// Called once per ProRes frame received from the 2110-22 network stream.
    /// Frames are copied directly — no re-encode, no quality loss.
    func appendFrame(_ sampleBuffer: CMSampleBuffer) {
        guard
            let input = videoInput,
            input.isReadyForMoreMediaData
        else { return }
        input.append(sampleBuffer)
    }

    func stopRecording() async throws {
        videoInput?.markAsFinished()
        await assetWriter?.finishWriting()
        if let error = assetWriter?.error {
            throw error
        }
        print("Immersive MOV saved to: \(outputURL.path)")
    }

    enum RecorderError: Error {
        case cannotAddInput
    }
}