In Exterior View System (EVS) 1.1, the logical camera device that consists of multiple physical camera devices is supported. To use this virtual device, device implementations must support the Synchronization Framework.
Enumerate, Open, and Close Logical Camera Device
The application can use the same
IEvsEnumerator methods to use the
available logical camera devices. The returned
EvsCamera object, which
represents a logical camera device, must contain the following items in the metadata:
If a returned EvsCamera object represents a logical camera, its camera metadata must contain this capability key in its
ANDROID_LOGICAL_MULTI_CAMERA_PHYSICAL_IDSfield lists physical camera device identifiers.
ANDROID_LOGICAL_MULTI_CAMERA_SENSOR_SYNC_TYPEfield can have either of below enum values:
ANDROID_LOGICAL_MULTI_CAMERA_SENSOR_SYNC_TYPE_APPROXIMATEis for sensors in master-master mode, no hardware shutter/exposure sync.
ANDROID_LOGICAL_MULTI_CAMERA_SENSOR_SYNC_TYPE_CALIBRATEDis for sensors in master-slave mode, hardware shutter/exposure sync. Synchronized GMSL2 cameras must have this value.
The application can retrieve a descriptor of physical camera devices through
IEvsCamera in the new
/** * Returns the description of the physical camera device that backs this * logical camera. * * If a requested device does not either exist or back this logical device, * this method returns a null camera descriptor. And, if this is called on * a physical camera device, this method is the same as getCameraInfo_1_1() * method if a given device ID is matched. Otherwise, this will return a * null camera descriptor. * * @param deviceId Physical camera device identifier string. * @return info The description of a member physical camera device. * This must be the same value as reported by * EvsEnumerator::getCameraList_1_1(). */ getPhysicalCameraInfo(string deviceId) generates (CameraDesc info);
Configuring Multi-Camera Support
All logical cameras are required to be defined statically and must be enumerated through a configuration manager implementation. As EVS allows each device in the group to be configured differently, EVS provides a list of member devices and indicates whether or not the image capture is synchronized.
<!-- camera group 0 --> <group id='group0' synchronized='CALIBRATED'> <caps> <!-- list of supported controls supported by all physical devices --> <supported_controls> <control name='BRIGHTNESS' min='0' max='255'/> <control name='CONTRAST' min='0' max='255'/> </supported_controls> <!-- list of stream configuration supported by all physical devices --> <stream id='0' width='640' height='480' format='RGBA_8888' framerate='30'/> </caps> <!-- list of parameters --> <characteristics> <parameter name='REQUEST_AVAILABLE_CAPABILITIES' type='enum' size='1' value='LOGICAL_MULTI_CAMERA' /> <parameter name='LOGICAL_MULTI_CAMERA_PHYSICAL_IDS' type='byte' size='2' value='/dev/video3,/dev/video4' /> </characteristics> </group>