udpsrc: multicast optimization on Linux
As of now, we bind the udpsrc multicast socket to ANY. As a side effect, we receive all packets from all joined groups on the same port and filter them. This is can degenerate quickly in term of performance in specific scenario. I propose that on Linux, we replace all this filtering by using IP_MULTICAST_ALL socket option. If the sending of address is disable, we could likely skip retrieving the packet info.