If you are short of multicast addresses, you can use the same multicast address for multiple cameras, and assign a different port number to each.
What you should know
Since a multicast address and port number are automatically assigned to a video unit when
it is discovered, you only need to edit the multicast addresses when you do not have enough
of them (certain switches are limited to 128).
NOTE: Using the same multicast
address on multiple encoders is less efficient than using a different address for each
encoder, because it causes more network traffic.