CSV file is used to input multiple uri, such as file or rtsp.
If you want to use usb camera as input, please use the following item as reference.
[source0]
enable=1
#Type - 1=CameraV4L2 2=URI 3=MultiURI
type=1
camera-width=640
camera-height=480
camera-fps-n=30
camera-fps-d=1
camera-v4l2-dev-node=0
You also refer this FAQ for usb camera