For my design, it starts with subscribing to the multicast stream

You then initiate a TCP connection to the source as a “management” connection, you get the latest packet ID

For a low-latency high-throughput system, you see if there are any packet ID gaps and request.

If you go low-throughput, you may include constant empty messages (which will increase B/W, and higher rate of empty messages = faster recovery from loss)

You can also do a client ack system if you do not have a very high amount of clients for lower B/W usage

You also have buffer memory for retransmits, and that can run out, so clients that cannot recover fast enough need to start over (causing complete loss of the stream)