The android.hardware.camera2 package provides an interface to individual camera devices connected to an Android device. It replaces the deprecated
This package models a camera device as a pipeline, which takes in input requests for capturing a single frame, captures the single image per the request, and then outputs one capture result metadata packet, plus a set of output image buffers for the request. The requests are processed in-order, and multiple requests can be in flight at once. Since the camera device is a pipeline with multiple stages, having multiple requests in flight is required to maintain full framerate on most Android devices.
To enumerate, query, and open available camera devices, obtain a
CameraDevices provide a set of static property information that describes the hardware device and the available settings and output parameters for the device. This information is provided through the
CameraCharacteristics object, and is available through
To capture or stream images from a camera device, the application must first create a
camera capture session with a set of output Surfaces for use with the camera device, with
createCaptureSession(List, CameraCaptureSession.StateCallback, Handler). Each Surface has to be pre-configured with an
appropriate size and format (if applicable) to match the sizes and formats available from the camera device. A target Surface can be obtained from a variety of classes, including
Generally, camera preview images are sent to
TextureView (via its
SurfaceTexture). Capture of JPEG images or RAW buffers for
DngCreator can be done with
ImageReader with the
The application then needs to construct a
CaptureRequest, which defines all the capture parameters needed by a camera device to capture a single image.
Once the request has been set up, it can be handed to the active capture session either for a one-shot
capture or for an endlessly
repeating use. Both methods also have a variant that accepts a list of requests to use as a burst capture / repeating burst. Repeating requests have a lower priority than captures, so a request submitted through
capture() while there’s a repeating request configured will be captured before any new instances of the currently repeating (burst) capture will begin capture.
After processing a request, the camera device will produce a
TotalCaptureResult object, which contains information about the state of the camera device at time of capture, and the final settings used. These may vary somewhat from the request, if rounding or resolving contradictory parameters was necessary. The camera device will also send a frame of image data into each of the output
Surfaces included in the request. These are produced asynchronously relative to the output CaptureResult, sometimes substantially later.