[Serusers] rtpproxy logs

hello, how can I access/enable/find logs from rtpproxy ? I see in rtpproxy sources that logs are being generated with "rtpp_log_write", but where are there or how can I "enable" them. I am interested to see when a session is "active", when a packet from both caller/callee are received in order to track down a problem I have with 2 UAs. something else: when everything is OK how many ports should be opened for s single proxy session ? 2 (1 RTP+1 RTCP) or 4 (2RTP + 2RTCP) ? when two UAs can not come to an agreement regarding a codec, is there any RTP traffic between the two, or media negotiation is based solely on SDP messages contained within INVITE/OK SIP messages ? thanks, razvan radu