tools/webcam/README.md
What's needed:
USE_WEBCAM=1 system/manager/manager.py
Use the ROAD_CAM (default 0) and optional DRIVER_CAM, WIDE_CAM environment variables to specify which camera is which (ie. ROAD_CAM=1 uses /dev/video1, on Ubuntu, for the road camera):
USE_WEBCAM=1 ROAD_CAM=1 system/manager/manager.py