cameras

Camera classes represent a particular capture session or recording duration. A camera is typically created from a capture device, though cameras can also operate independently (e.g. opening a USB device directly via OpenCV). Cameras are started and stopped each time the user begins and ends a recording, while the underlying capture device may remain powered on across multiple recordings.

omgrab.cameras.cameras

Camera module for omgrab.

CameraConfig(fps, width, height) dataclass

Base camera configuration.

Attributes:

Name	Type	Description
fps	int	Target capture frame rate.
width	int	Frame width in pixels.
height	int	Frame height in pixels.

FrameUnavailableError

Bases: RuntimeError

Exception raised when a frame is not available.

Camera(config, enforce_frame_timing=True)

Bases: Generic[FrameT], ABC

Camera class for omgrab.

Initialize the camera.

Parameters:

Name	Type	Description	Default
config	CameraConfig	Camera configuration.	required
enforce_frame_timing	bool	If True, get_next_frame will sleep to enforce the configured FPS. Set to False for queue-based cameras where the hardware already controls frame timing.	True

config property

Get the camera configuration.

get_next_frame(timeout_s=None) abstractmethod

Get the next frame from the camera.

setup() abstractmethod

Setup the camera.

close() abstractmethod

Close the camera.

__enter__()

Enter the context manager.

__exit__(exc_type, exc_value, traceback)

Exit the context manager.

omgrab.cameras.oakd_camera

OAK-D camera implementations.

Camera classes that read frames from queues populated by the OAK-D capture device (see omgrab.devices.oakd_capture_device). Each camera instance represents a single stream (RGB or depth) for the duration of a recording session.

OakDRGBCamera(config, frame_queue)

Bases: QueueReaderCamera[RGBFrame]

OakD RGB camera class.

Initialize the OakD RGB camera.

OakDDepthCamera(config, frame_queue)

Bases: QueueReaderCamera[DepthFrame]

OakD Depth camera class.

Initialize the OakD Depth camera.

omgrab.cameras.queue_reader_camera

Camera implementation that reads frames from a queue.

QueueReaderCamera(config, frame_queue)

Bases: Camera[FrameT], Generic[FrameT]

Camera that reads frames from a queue.

Initialize the queue reader camera.

setup()

Setup the queue reader camera.

close()

Close the queue reader camera.

get_next_frame(timeout_s=None)

Get the next frame from the queue.

flush_queue()

Flush all pending frames from the queue.

Returns:

Type	Description
int	Number of frames flushed.

omgrab.cameras.usb_camera

USB camera implementation using OpenCV VideoCapture.

USBCamera(config, device_path='', usb_port_path='')

Bases: Camera[RGBFrame]

Camera that reads frames from a USB camera via OpenCV.

Initialize the USB camera.

Exactly one of device_path or usb_port_path must be provided.

Parameters:

Name	Type	Description	Default
config	CameraConfig	Camera configuration (fps, width, height).	required
device_path	str	Path to the video device (e.g. '/dev/video2').	''
usb_port_path	str	USB port path (e.g. '3-2'). The device path is resolved from sysfs each time setup() is called.	''

setup()

Open the USB camera and configure resolution/fps.

close()

Release the USB camera.

get_next_frame(timeout_s=None)

Read the next frame from the USB camera.

Parameters:

Name	Type	Description	Default
timeout_s	Optional[float]	Not used. On V4L2 with BUFFERSIZE=1, grab() blocks for at most one frame period (~33ms at 30fps). If the device is disconnected, grab() returns False immediately.	None

Returns:

Type	Description
tuple[RGBFrame, datetime]	Tuple of (frame, timestamp).

Raises:

Type	Description
FrameUnavailableError	If the frame could not be read.