application/x-rtp caps field have different names in the send and receive paths...
Submitted by Olivier Crête
Before 1.0, Wim renamed the "clock-base" and "seqnum-base" fields in GstRtpBasePayload into "timestamp-offset" and "seqnum-offset". But he failed to rename them elsewhere. So that broke RTP dtmf sending in all 1.x releases. I've now fixed it in the master and 1.4 branches, that was bug 738297. But I only changed the elements that are in the "send" path, not those in the receive path. So right now we're in the ugly state where application/x-rtp caps are different for sending and receiving.
Although this is technically an API break and is not strictly necessary, I think we should just bite the bullet and update the receive side caps to match the send-side ones in time for 1.x.
The rtpsource stats also use the name seqnum-base, we may also want to break API there and update the name too.