It's not allowed to have multiple instances of CameraManager. This requirement is not easy for GStreamer were the device monitor and the camerasrc, or two camerasrc instances don't usually have any interaction between each other. Fix this by implementing a minimalist singleton around CameraManager constructor and start()/stop() operations. Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>