Playing and editing Cinematic mode video

At a glance

Project structure

Source bundle/
└── CinematicVideoPlaybackAndEditing/
    ├── CinematicVideoPlaybackAndEditingApp.swift
    ├── ContentView.swift
    ├── AssetView.swift
    ├── CinematicPlayer.swift
    ├── PlayerLayerView.swift
    ├── SampleCustomCompositor.swift
    ├── CinematicAssetReader.swift
    ├── CinematicAsset.swift
    ├── CinematicAssetData.swift
    ├── CinematicEditHelper.swift
    ├── CinematicEditor.swift
    └── PlayerLayerContainer.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Metal, Swift.
• The verified tree contains 4 project/configuration file(s) and 18 source declaration(s).

Overall architecture

flowchart LR
    N1["CinematicVideoPlaybackAndEditingApp"]
    N2["ContentView"]
    N3["CinematicPlayer"]
    N4["Cinematic APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

CinematicVideoPlaybackAndEditing/CinematicVideoPlaybackAndEditingApp.swift:10 — architecture anchor

@main
struct CinematicVideoPlaybackAndEditingApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into Cinematic.

Ownership and state

classDiagram
    ContentView *-- PhotosPickerItem : selectedPickerItem
    ContentView *-- CinematicAsset : selectedAsset
    ContentView *-- AsyncStream : continuation
    AssetView o-- CinematicAsset : asset

Ownership evidence

CinematicVideoPlaybackAndEditing/ContentView.swift:13 — stored dependency or nearest verified ownership anchor

struct ContentView: View {
    // ...
    @State private var selectedPickerItem: PhotosPickerItem?
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

CinematicVideoPlaybackAndEditing/CinematicAsset.swift:37 — representative execution boundary

    init?(localIdentifier: String) async {
        // ...
        self.localIdentifier = localIdentifier
        // ...
    }

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

CinematicVideoPlaybackAndEditing/ViewRepresentable.swift:21 — representative type boundary

public protocol ViewRepresentable: PlatformViewRepresentable {
    // ...
    associatedtype ViewType: PlatformView
    // ...
}

The source explicitly defines local protocol relationships: PlayerLayerContainer → ViewRepresentable.

Access control

Reference code

CinematicVideoPlaybackAndEditing/CinematicEditHelper.swift:54 — representative boundary

    private func texture(from outputBuffer: CVPixelBuffer) -> MTLTexture? {
        var image: CVMetalTexture?
        // ...
    }

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Main application flow

sequenceDiagram
    participant CinematicAsset
    participant CNAssetInfo
    participant CNRenderingSession
    participant CNScript
    participant cinematicAssetInfo
    CinematicAsset->>CNAssetInfo: CNAssetInfo()
    CinematicAsset->>CNRenderingSession: Attributes()
    CinematicAsset->>CNScript: CNScript()
    CinematicAsset->>cinematicAssetInfo: load()
    CinematicAsset->>cinematicAssetInfo: load()

Reference code

CinematicVideoPlaybackAndEditing/CinematicAsset.swift:112 — loadData()

    static private func loadData(from asset: AVAsset, pathComponent: String) async throws -> CinematicAssetData {
        // ...
        let cinematicAssetInfo = try await CNAssetInfo(asset: asset)
        let renderingSessionAttributes = try await CNRenderingSession.Attributes(asset: asset)
        guard let renderingCommandQueue = MTLCreateSystemDefaultDevice()?.makeCommandQueue() else {
            fatalError("Couldn't create command queue")
        }
        let renderingSession = CNRenderingSession(commandQueue: renderingCommandQueue,
                                                  sessionAttributes: renderingSessionAttributes,
                                                  preferredTransform: cinematicAssetInfo.preferredTransform,
                                                  quality: CNRenderingQuality.export)
        let cinematicScript = try await CNScript(asset: asset)
        let url = try FileManager.default.url(for: .applicationSupportDirectory,
                                              in: .userDomainMask, appropriateFor: nil,
                                              create: false)
        let fileURL = url.appendingPathComponent(pathComponent, conformingTo: .archive)
        if FileManager.default.fileExists(atPath: fileURL.path) {
            let scriptFileData = try Data(contentsOf: fileURL)
            let cinematicScriptChanges = CNScript.Changes(dataRepresentation: scriptFileData)
            cinematicScript.reload(changes: cinematicScriptChanges)
        }
        let nominalFrameRate = try await cinematicAssetInfo.frameTimingTrack.load(.nominalFrameRate)
        let naturalTimeScale = try await cinematicAssetInfo.frameTimingTrack.load(.naturalTimeScale)
        let cinematicAssetData = CinematicAssetData(avAsset: asset,
                                                    assetInfo: cinematicAssetInfo,
                                                    renderingSessionAttributes: renderingSessionAttributes,
                                                    renderingSession: renderingSession,
                                                    commandQueue: renderingCommandQueue,
                                                    script: cinematicScript,
                                                    nominalFrameRate: nominalFrameRate,
                                                    naturalTimeScale: naturalTimeScale)
        return cinematicAssetData
    }

Naming conventions

• Types: App: CinematicVideoPlaybackAndEditingApp; Player: CinematicPlayer; View: AssetView, ContentView, PlayerLayerView.
• Protocols: ViewRepresentable.
• Methods: refreshPlayer, setVideoComposition, refreshFrame, renderContextChanged, startRequest, drawFocusDetections, setupForReading, cancelReading.
• Files: CinematicVideoPlaybackAndEditing/CinematicVideoPlaybackAndEditingApp.swift, CinematicVideoPlaybackAndEditing/ContentView.swift, CinematicVideoPlaybackAndEditing/AssetView.swift, CinematicVideoPlaybackAndEditing/CinematicPlayer.swift, CinematicVideoPlaybackAndEditing/PlayerLayerView.swift, CinematicVideoPlaybackAndEditing/SampleCustomCompositor.swift.

Architecture takeaways

• CinematicVideoPlaybackAndEditingApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches AVFoundation, SwiftUI, Cinematic, CoreMedia through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation