←API Reference

playback

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Classes

Name	Type	Summary
AssetPlaybackDatasetLoader	AssetPlaybackDatasetLoader	Loads playback dataset data from the app's [Context.getAssets] directory. Use a subdirectory that contains a capture JSON file and the frame images (and optional depth files). Example: place a dataset in src/main/assets/playback/my_capture/ with capture.json, frame_00000000.jpg, etc. Then use AssetPlaybackDatasetLoader(context, "playback/my_capture").
PlaybackBackgroundView	PlaybackBackgroundView	A view that displays the current playback frame image as the background. Place this view behind your 3D/GL surface when in playback mode and call [setPlaybackFrame] whenever a new [PlaybackFrame] is delivered so the recorded camera image is shown. Orientation is corrected so that the image (which may be stored in sensor/landscape layout) is rotated to match the current device orientation using [ImageMath.displayTransform]. Use with [PlaybackSession] and a frame listener: when the session delivers a frame, build [FrameData] for NSDK and call [setPlaybackFrame] to update this view.
PlaybackCamera	PlaybackCamera	Camera representation for playback, built from frame [metadata]. Exposes transform, intrinsics, resolution, tracking state, and orientation. Use [toArCorePose] to build a [Pose] for [FrameData.cameraPose]. Use [getViewMatrix] and [getProjectionMatrix] to drive a virtual camera for playback rendering.
PlaybackDataset	PlaybackDataset	A playback dataset loaded from a capture JSON file. Uses on-demand loading for frame images and depth: only the requested frame is loaded and cached (1-frame cache). Create via [PlaybackDataset.loadFrom] with a [PlaybackDatasetSource] (e.g. [AssetPlaybackDatasetLoader]). Use [loadFrom][PlaybackDataset.loadFrom] with a custom [imageDecoder] in unit tests to avoid [BitmapFactory] (not mocked on JVM). Thread safety: This class is NOT thread-safe. All methods must be called from a single thread. The 1-frame cache ([cachedFrameIndex], [cachedImageBytes], [cachedDepthData], [cachedConfidenceData]) is not protected by a lock; concurrent reads and writes will produce inconsistent results. [PlaybackSession] satisfies this constraint by funneling all frame loads through a single coroutine dispatcher. If you introduce additional callers, ensure they are serialized. Cache fields are marked [@Volatile][Volatile] so that a value written on a background thread is immediately visible to any thread that subsequently reads it (e.g. the main thread checking [cachedFrameIndex] before deciding to reload). This is a visibility guarantee only — it does not make compound check-then-act sequences atomic.
PlaybackDatasetError	PlaybackDatasetError	Errors that can occur when loading or accessing playback dataset data.
abstract PlaybackDatasetLoader	PlaybackDatasetLoader	Base class for loading playback dataset data from various sources. Subclasses override [loadCaptureJson], [loadImage], [loadDepthData], [loadDepthConfidence] to provide concrete implementations. Use [loadDataset] to parse the capture JSON and create a [PlaybackDataset] that uses this loader for on-demand frame loading.
PlaybackSession	PlaybackSession	Runs a timed loop over a [PlaybackDataset], loading one frame per tick and notifying a listener. Use [play] to begin playback and [pause] to stop; the loop wraps to frame 0 at end. Call [setOnFrameListener] before [play] to receive each [PlaybackFrame]; the listener may be invoked from a background thread (post to main in the sample if needed).

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Interfaces

Name	Type	Summary
PlaybackDatasetSource	PlaybackDatasetSource	Abstraction for loading playback dataset data from a source (assets, file, etc.). Used for on-demand frame loading: [PlaybackDataset] calls these methods when frames are requested.

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Data Classes

Name	Type	Summary
CaptureMetadata	CaptureMetadata	Optional capture-level metadata.
CaptureRoot	CaptureRoot	Root structure for the capture JSON file. Required fields per spec; optional may be null.
FrameMetadata	FrameMetadata	Per-frame metadata from the capture JSON. Required fields per spec; optional may be null.
LocationMetadata	LocationMetadata	Location metadata for a frame. All fields optional for varying capture formats.
PlaybackFrame	PlaybackFrame	One frame of playback: metadata, camera representation, optional image and depth. Created when a frame is loaded (e.g. by [PlaybackSession]). Use [camera] for pose/intrinsics and [metadata] for building [FrameData].
PlaybackGpsLocation	PlaybackGpsLocation	GPS location from playback metadata (no Android dependency). Use [toLocation] to obtain [android.location.Location] for [FrameData.location]. Testable without mocking Android.

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