We have a similar interest in getting RTP functionality in GNU Radio.
Phil Karn recently wrote and published an SDR package for Phase 4 Ground that includes RTP multicast functionality. We have been talking about getting this functionality into GNU Radio. Another person interested in seeing this happen is David Rowetel from FreeDV. He and Phil have started talking about this.
Ron and Marcus are of course correct in that RTP streams are already handled pretty well in GNU Radio. No, we do not want to reinvent the wheel.
We would like to combine Opus/CODEC2 and RTP multicast to have stereo field audio. The sources of the audio appear at different points in the stereo field, so that a roundtable conversation feels more like a roundtable, or so that two streams from two different SDRs are distinct.
Everyone is welcome to comment and contribute. The repository with the RTP multicast code from Phil Karn is here:
https://github.com/phase4ground/ka9q-sdrIf it can be done without a new block, then great. If there is value in handling bookkeeping, or functions in RTP multicast that would be much easier or much more useful in flowgraphs with a new block, then that's what we want to do. I have advice that it would be useful to get it into blocks. We want to do the right thing and we want comment and critique.
Phase 4 Ground will have a "block party" at GNU Radio Conference 2018. The overall goal of Phase 4 Ground is to get DVB-S2 and DVB-S2X receive in GNU Radio. We have a dedicated room/lab for the week of the conference and will bring as much test equipment as we can fit into a minivan. Several satellite/modem/DVB docents have signed up and we're working on swag! If you have interest or expertise in any area of DVB-S2 receiver design, then we enthusiastically welcome you. We have a Slack and a mailing list.
https://lists.openresearch.institute/One of the hard parts of the receiver is the LDPC FEC decode. We have one working implementation from Charles Brain, written for a GPU. It needs some work to get adaptive coding and modulation (we want ACM) working due to the architectural choices. It's a big achievement and it puts success more within reach. There are other hard parts in this receiver, but LDPC is challenging work. Having an open source version is a big step forward.
Aside from ACM, we want to use generic stream encapsulation or GSE, which replaces the MPEG transport layer with a protocol that supports, well, you guessed it, generic data. This makes the downlink much more useful as a multiple access amateur radio system, which is where we're trying to go with all this work. Several of us have contributed GSE work that can be found in Wireshark and in GNU Radio, so working with GSE streams can be easier.