(disclaimer: I'm participating in the libRIST development)
RIST! It's a well thought out protocol without technical debt (which SRT has), supports multicast (if you need it), null packet deletion, encryption via PSK or DTLS and multiplexing (multiplexing support in libRIST is not fully there yet, it's on the roadmap together with DTLS).
Next iteration of the RIST protocol will support "backpressure" on your encoder, so if you have too much packet loss your encoding can scale it's video bitrate down, while together with null packet deletion you'll be able to keep your bitrate perfectly CBR.