It's often UDP/RTP delivery with SAP/SDP for announcement/discovery, then you use an IGMP join to attach to the stream. The important thing about why you'd use

It's often UDP/RTP delivery with SAP/SDP for announcement/discovery, then you use an IGMP join to attach to the stream. The important thing about why you'd use IGMP Multicast instead of unicast is that you get a more assured latency which is important for audio sync.