question: @ RequiresPermission ( Manifest . permission . CAMERA ) public CameraSource start ( ) throws IOException { synchronized ( mCameraLock ) { if ( mCamera != null ) { return this ; } mCamera = createCamera ( ) ; if ( Build . VERSION . SDK_INT >= Build . VERSION_CODES . HONEYCOMB ) { mDummySurfaceTexture = new SurfaceTexture ( DUMMY_TEXTURE_NAME ) ; mCamera . setPreviewTexture ( mDummySurfaceTexture ) ; } else { mDummySurfaceView = new SurfaceView ( mContext ) ; mCamera . setPreviewDisplay ( mDummySurfaceView . getHolder ( ) ) ; } mCamera . startPreview ( ) ; mProcessingThread = new Thread ( mFrameProcessor ) ; mFrameProcessor . setActive ( true ) ; mProcessingThread . start ( ) ; } return this ; }
target:  Opens the camera and starts sending preview frames to the underlying detector.  The preview frames are not displayed.