it was not clear to me based on rtpengine module readme if
rtpengine_offer/answer are same kind of sdp manipulation functions as,
for example, sdpops module functions, i.e., will rtpengine functions
pass to rtpengine the sdp as it is after possible earlier sdpops
function calls and will possible sdpops functions calls after rtpengine
function call keep on manipulating the sdp returned from rtpengine
function call.
-- juha