Migrate to Camera2

This page identifies the differences between the Extended View System (EVS) and Camera2. It also describes how to set up your Camera2 implementation.

Open and close the camera

EVS

openCamera combines opening the device and configuring a single stream.

Camera2

To open and close a device with Camera2:

1. Select one of these modes:

   • Exclusive mode, use CameraManager.openCamera (Java) or ACameraManager_openCamera on the native development kit (NDK).

   • Shared mode, use openSharedCamera or ACameraManager_openSharedCamera. When you enable camera sharing, provide a shared session configuration.

2. To configure streams, create a capture session with the relevant output surfaces. For example, from an ImageReader or SurfaceView with CameraDevice.createCaptureSession() (Java) or ACameraDevice_createCaptureSession() (NDK).

   Camera2 supports simultaneous multiple streams. Create multiple streams for purposes such as for preview, recording, and image processing. Streams serve as parallel pipelines, sequentially processing raw frames from the camera.

3. To close a camera device, use CameraDevice.close() (Java) or ACameraDevice_close() (NDK).

Consider these sample code snippets:

CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
    manager.openCamera(cameraId, new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice camera) {
            // Camera opened, now create session
        }
        @Override
        public void onDisconnected(@NonNull CameraDevice camera) {}
        @Override
        public void onError(@NonNull CameraDevice camera, int error) {}
    }, handler);
} catch (CameraAccessException e) {
    // Handle exception
}

ACameraManager *cameraManager = ACameraManager_create();
ACameraDevice *cameraDevice = nullptr;
camera_status_t status = ACameraManager_openCamera(
    cameraManager, cameraId, &deviceStateCallbacks, &cameraDevice);

Stream camera data

This section describes how to stream camera data.

EVS

On EVS, to:

1. Initiate streaming, use startVideoStream.
2. Stop streaming, use stopVideoStream.

Camera2

On Camera2, to:

1. Create a CaptureRequest suitable for preview, use TEMPLATE_PREVIEW with CameraDevice.createCaptureRequest() in Java or ACameraDevice_createCaptureRequest() on the NDK.

2. Submit the request for continuous streaming, use CameraCaptureSession.setSingleRepeatingRequest (Java) or ACameraCaptureSession_setRepeatingRequestV2 (NDK).

3. Stop streaming, use CameraCaptureSession.stopRepeating (Java) or ACameraCaptureSession_stopRepeating (NDK).

Buffer management

• On EVS, setMaxFramesInFlight previously controlled buffer count, which could potentially be changed mid-stream. When camera streaming started, EVS furnished a buffer ID for each image frame, which correlated to the same hardware buffer address in memory.

• On Camera2, the maximum number of images for an AImageReader or ImageReader is set with AImageReader_new or ImageReader.newInstance when a session is initialized. This can't be dynamically altered once the session has started. To get a buffer ID for each frame, clients can maintain a map that correlates the hardware buffer address, obtained from the Image object, to a unique identifier.

Pause and resume streaming

• EVS used pauseVideoStream and resumeVideoStream.

• Camera2 has no direct equivalents. Instead, for:

  • Pause, use stopRepeating
  • Resume, use setSingleRepeatingRequest

Camera parameters

• EVS used methods, such as setIntParameter to change the camera capture request parameter.

• On Camera2, to modify parameters, call the set API for the CaptureRequest builder and then submit it.

Consider these code samples:

CaptureRequest.Builder builder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
builder.set(CaptureRequest.CONTROL_EFFECT_MODE, CaptureRequest.CONTROL_EFFECT_MODE_MONO);
// Submit this request

ACaptureRequest_setEntry_i32(captureRequest, ACAMERA_CONTROL_EFFECT_MODE, 1, &effectMode);

Logical cameras

• EVS: For logical cameras, such as Surround View, the EVS Manager opened all associated physical cameras, initiated the video streams, and provided a cohesive array of images.

• Camera2: When similar functionality is needed with Camera2, apps must manage logical cameras, which requires you to:

  • Identify physical sub-cameras associated with a logical camera.
  • Open each necessary physical camera.
  • Initiate streams on each camera.
  • Synchronize frames, if required. Optimally, this is handled at the HAL for hardware-level synchronization.

We'll provide a compatibility library (shim layer) to existing EVS clients to facilitate the transition. The aim being to support Camera2 APIs with minimal changes to code.

Permissions

EVS

Access is restricted to privileged unique identifiers (UID). For example, AID_AUTOMOTIVE_EVS. Deprecated permissions include android.car.permission.USE_CAR_EVS_CAMERA.

Camera2

Camera2 requires android.permission.CAMERA. For special cases:

• android.permission.SYSTEM_CAMERA: To access cameras hidden from 3P apps. Also requires the CAMERA permission. To learn more, see System cameras.

• android.permission.CAMERA_HEADLESS_SYSTEM_USER: Allows access from User 0, crucial for services such as rear view cameras that must run across user switches. Requires a pre-granted CAMERA permission.

• android.permission.CAMERA_PRIVACY_ALLOWLIST: Allows OEMs to exempt certain safety-critical apps from the user-controlled camera privacy toggle.

Safety-critical camera apps must follow the Google built-in pre-grant policies provided in Design for Driving.

Primary and secondary clients

For shared camera access:

• EVS offered explicit APIs, setPrimaryClient and forcePrimaryClient, to manage the primary client, which had the authority to modify parameters.

• Camera2, when the camera is opened in shared mode (Android 16 and higher), the priority of the client accessing the camera determines the primary client. The highest priority client (typically the foreground app) can modify capture request parameters. No direct APIs are used to force primary status. Primary status is managed by the framework.

System cameras

To restrict a camera device to be accessed by system or 1P apps only, declare the ANDROID_REQUEST_AVAILABLE_CAPABILITIES_SYSTEM_CAMERA capability in the Camera HAL for that device. Clients must have the android.permission.SYSTEM_CAMERA in addition to android.permission.CAMERA connecting to this camera device.

CarEVSManager and CarEVSService

For API access, Java apps should use the standard android.hardware.camera2.CameraManager instead of CarEVSManager.

For rear view camera, the logic in CarEVSService that monitors the GEAR_SELECTION VHAL property and launches an activity must be migrated to an OEM-owned app. This app:

• Monitors the GEAR_SELECTION VHAL property.
• Launches the rear view camera activity when reverse gear is engaged.
• Uses Camera2 APIs to display the camera feed.

For a consistent and unobstructed display of the rear view camera, specifically during user transitions or when other apps could obscure the preview, we recommend these guidelines when implementing rear view camera functionality with Camera2:

• Mark the rear view camera as a system camera.

• Run the service or app accessing the camera as User 0 using CAMERA_HEADLESS_SYSTEM_USER permission.

• Add the app to the Camera Privacy Allowlist.

Display rendering

EVS display and automotive display service.

These are deprecated.

Camera2

Use the standard Android rendering methods with Surface, android.hardware.display.DisplayManager, and android.view.Display.

For scenarios needing early camera display, the Camera2 ImageReader can provide direct access to the hardware buffer so you can integrate it with existing DRM-based display implementations for rendering.

This early camera access is exclusively permitted for privileged clients who have the AID_AUTOMOTIVE_EVS_UID and is limited to system cameras located on the exterior of a vehicle.

Emulator HAL (EVS mock HAL)

We plan to deprecate EVS Mock HAL. Instead, OEMs should use the Camera2 emulated camera HAL, hardware/google/camera/devices/EmulatedCamera/, which will be enhanced to support:

• Configurable number of cameras.
• Color bar test patterns.
• Video file emulation.

To include this HAL in the build:

# In device.mk
PRODUCT_SOONG_NAMESPACES += hardware/google/camera/devices/EmulatedCamera
PRODUCT_PACKAGES += com.google.emulated.camera.provider.hal

Appropriate security-enhanced Linux (SELinux) policies are also required to allow cameraserver to interact with the Emulated Camera HAL service.

V4L2 UVC Camera HAL

We plan to deprecate EVS V4L2 HAL. Use Camera2 external camera support for USB cameras (UVC). To learn more, see External USB Cameras.

Early camera access

EVS camera access was limited to privileged clients with the AID_AUTOMOTIVE_EVS UID. For camera access before the Android boot process is complete, provided the UID remains AID_AUTOMOTIVE_EVS. However, early camera access is limited to system cameras located on the exterior of the vehicle.

Ultrasonics APIs

We plan to deprecate the EVS Ultrasonics APIs. Instead, use these VHAL properties introduced in Android 15 for ultrasonic sensor detections.