tree e757fbf579959d6859259e6c24be5d83ca549de9
parent 1ada2c2d804a28b7244923fa72f25d6ac92c372f
author Jayant Chowdhary <jchowdhary@google.com> 1673605332 +0000
committer Jayant Chowdhary <jchowdhary@google.com> 1676562763 -0800

DeviceAsWebcam

This system app performs the function of advertising the
android device as a webcam to other hosts - currently as
a UVC camera over USB.

The system app broadly consists of 2 parts :
1) Foreground Service : The system app receives the
   ACTION_USB_STATE broadcast from the system when the
   user wants the device to behave like a webcam. Upon
   receiving the broadcast and confirming that the webcam
   function was selected starts a foreground service which
   through JNI, uses the linux kernel's UVC gadget driver
   to listen to events on a /dev/video* v4l2 node the first
   one which has the VIDEO_OUTPUT capability). Through
   processing exceptional or write events on these nodes
   the native service starts the capturing frames using
   the camera2 sdk api and writes them to buffers requested
   from the UVC gadget driver.

2) Camera preview activity : This activity displays camera
   preview for framing the scene and viewing the webcam stream
   that will be sent over to the host. This preview can run
   independantly of the webcam actually streaming. As a result,
   the user can frame the scene before opening up a client
   app on the host that will request the webcam stream.

Bug: 242344221
Test: Select 'Webcam' option from the USB preferences page
      on the Settings App -> Open preview to frame
      scene -> use various apps on major host OSes to use
      the webcam stream.

Change-Id: I7a81c30f2756ef123cbd652b0942c58374b33df5
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>