We add a new signal, get-rollover-counter, to the SRTP encoder. Given a ssrc the signal will return the currently internal SRTP rollover counter for the given stream. For the SRTP decoder we have a new SRTP caps parameter "roc" that needs to be set when a new SRTP stream is created for a given SSRC. https://bugzilla.gnome.org/show_bug.cgi?id=726861