rk35xx-android14/packages/services/DeviceAsWebcam/res/raw

The JSON files in this directory can be overridden by vendors using Runtime Resource Overlays. These serve as an optional mechanism for vendors to modify DeviceAsWebcam behavior if needed.

The details of the overridable files are as follows:

• physical_camera_mapping.json:

  This file contains a mapping of the preferred physical streams that are to be used by DeviceAsWebcam service instead of logical streams, in order to save power during webcam streaming. This mapping is optional. It must be overridden through a static resource overlay by vendors if needed. The format of the mapping is :

  {
    "<logical-camera-id-1>" : {
      "<physical-camera-id-1>" : "<camera-label-1>",
      "<physical-camera-id-2>" : "<camera-label-2>",
      ...
    },
    "<logical-camera-id-2>" : {
      "<physical-camera-id-3>" : "<camera-label-3>",
      "<physical-camera-id-4>" : "<camera-label-4>",
      ...
    },
    ...
  }
  

  The 'camera-label' field here helps DeviceAsWebcam label these physical camera ids in the UI elements of the service. The mapping containing physical camera ids is in order of preference of the physical streams that must be used by DeviceAsWebcam service. Available camera-labels are:

  • UW: Ultra-wide
  • W: Wide
  • T: Telephoto
  • S: Standard
  • O: Other

  For example, if a vendor would like to advertise 2 possible physical streams with camera ids 3(Ultra-wide) and 4(Wide) for the back logical camera the mapping could be:

  {
    "0" : {
      "3" : "UW",
      "4" : "W"
    }
  }
  

• physical_camera_zoom_ratio_ranges.json:

  This file contains the mapping of physical cameras to their zoom ratio ranges. When provided, DeviceAsWebcam will use this zoom ratio range instead of that retrieved from camera characteristics. This is useful when the zoom ratio of the physical camera listed in physical_camera_mapping.json is different from the logical camera it belongs to. Providing this mapping is optional, and only used if physical_camera_mapping,json contains a corresponding entry. The format of the mapping is:

  {
    "<logical-camera-id-1>" : {
      "<physical-camera-id-1>" : ["<zoom-ratio-range-lower-1>", "<zoom-ratio-range-upper-1>"],
      "<physical-camera-id-2>" : ["<zoom-ratio-range-lower-2>", "<zoom-ratio-range-upper-2>"],
      ...
    },
    "<logical-camera-id-2>" : {
      "<physical-camera-id-3>" : ["<zoom-ratio-range-lower-3>", "<zoom-ratio-range-upper-3>"],
      "<physical-camera-id-4>" : ["<zoom-ratio-range-lower-4>", "<zoom-ratio-range-upper-4>"],
      ...
    },
    ...
  }
  

  For example, if a vendor would like to custom 2 possible physical streams' supported zoom ratio ranges with camera ids 3 and 4 for the back logical camera the mapping could be:

  {
    "0" : {
      "3" : ["1.0", "5.0"],
      "4" : ["1.0", "8.0"]
    }
  }
  

• ignored_cameras.json:

  By default, DeviceAsWebcam exposes all backward compatible cameras listed in CameraManager#getCameraIdList() as supported cameras to stream webcam frames from. ignored_cameras.json provides a way to ignore a predetermined set of cameras if they are not expected to be used with DeviceAsWebcam.

  For example, if a vendor would like to ignore camera ids 22 and 66, the ignored cameras array could be:

  [
      "22",
      "66",
      ...
  ]
  

• ignored_v4l2_nodes.json:

  Linux UVC gadget driver mounts a V4L2 node that DeviceAsWebcam service interacts with. To determine this node, DeviceAsWebcam service looks through all /dev/video* nodes, looking for the first V4L2 node that advertises V4L2_CAP_VIDEO_OUTPUT capability.

  This will run into issues if a device has other V4L2 nodes mounted at /dev/video* with V4L2_CAP_VIDEO_OUTPUT capability advertised for other processing purposes.

  ignored_v4l2_nodes.json provides a way for DeviceAsWebcam service to ignore a predetermined set of V4L2 nodes.

  The file format is as follows:

  [
      "/dev/video10",
      "/dev/video12",
      ...
  ]
  

  Note that wildcard patterns are not supported in ignored_v4l2_nodes.json.