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Camera Feed

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In addition to sensor data, the SDK DataSource provides access to recorded and live frames from the device camera. This is useful for both live camera feeds and recorded logs.

tip

Recorded logs with camera data are MP4 files that can be played back using standard video players. Using external players such as video_player is the preferred approach for most log-playback scenarios, as they can provide better performance.

Camera Player Widget​

The GemCameraPlayer widget can be used to display the camera feed on screen. Wrap the widget in a SizedBox or similar to control its size. The GemCameraPlayer takes the following parameters:

  • controller — the GemCameraPlayerController that drives playback and provides camera frames. Required. Connects the widget to the source of frames, exposes playback status (loading, playing, error, ended), and is used internally to start/stop rendering and request frame updates. See more information below.
  • fallbackWidget — optional widget shown when a frame cannot be decoded or an error state is reported by the controller. Useful for showing an error placeholder or retry affordance.
  • loadingWidget — optional widget shown while the player is waiting for the first frame or otherwise in a loading state. Commonly a spinner or shimmer to indicate work in progress.
  • endWidget — optional widget shown once the camera feed or recording has finished and the controller reports an ended state. Useful for displaying a replay button or end-of-stream message.
  • fit — optional BoxFit describing how the decoded image should be sized into the available space. Defaults to a cover-like behavior when not supplied. See the BoxFit API reference for more information.

Camera Player Controller​

The GemCameraPlayerController is the main interface for controlling camera feed playback and accessing frames. It is created via the constructor, which takes a DataSource as a required parameter. Optionally, you can provide a CameraConfiguration to the configurationOverride parameter to customize the frame size.

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The DataSource provided to the GemCameraPlayerController must have the DataType.camera data type enabled. Providing a DataSource without camera data will result in an error state in the controller and cause the fallbackWidget to be shown in the GemCameraPlayer.

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When presenting the live camera feed, a video recording session must be active on the DataSource. See the Video Recording guide for more information on starting a video recording session.

Camera Player Controller Properties​

The GemCameraPlayerController exposes the following properties:

  • datasource: the DataSource provided during construction. It can be used to query additional information about the source of camera frames and to control the playback session.
  • size: the size of the camera frames being provided by the controller, taking into account any configuration overrides.
  • status: the current playback status of the controller. The following statuses are possible:
    • loading: the controller is waiting for the first frame to be available. If the controller is used within a GemCameraPlayer, the loadingWidget will be shown during this state.
    • error: an error occurred while trying to provide frames (for example, the data source does not provide camera data or the raw camera frame data is in an unsupported format). If the controller is used within a GemCameraPlayer, the fallbackWidget will be shown during this state.
    • playing: the controller is actively providing frames. If the controller is used within a GemCameraPlayer, the camera feed will be rendered on screen during this state.
    • paused: the controller has paused frame delivery. If the controller is used within a GemCameraPlayer, the last rendered frame will remain on screen during this state.
    • ended: the camera feed or recording has finished. If the controller is used within a GemCameraPlayer, the endWidget will be shown during this state.
  • camera: the Camera instance providing camera parameters such as intrinsics and extrinsics. It will be null if no camera data is available from the DataSource.

Pause and Resume Camera Feed​

The GemCameraPlayerController provides methods to pause and resume the camera feed:

  • pause(): Pauses the camera feed. The controller's status will change to paused.
  • resume(): Resumes the camera feed if it was paused. The controller's status will change back to playing.

Pausing and resuming the camera feed does not affect the underlying DataSource playback or recording session; it only controls the delivery of camera frames to the controller. Use the Playback API available on the DataSource to control overall playback or recording for log data sources.

Listening to Camera Player Controller Changes​

The GemCameraPlayerController extends ValueNotifier, so you can listen to it for changes in playback status and update your UI accordingly. The GemCameraPlayerValue provides access to the data source, the current playback status, the current Camera (if available), and the data source listener used internally to receive camera frames. With this, you can listen for changes in the controller's value and react to status updates or errors.

Lifecycle Management​

Remember to dispose of the GemCameraPlayerController when it is no longer needed to free up resources. Disposing the controller will stop the internal data source listener and release any associated resources. The GemCameraPlayer widget does not automatically dispose of the controller, so ensure you manage its lifecycle appropriately in your application. Dispose of both the controller and the player widget when appropriate, as they can consume significant resources.

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