I am using SIP Communicator(Version-sip-communicator-src-1.0-alpha3-nightly.build.2164) on Windows Vista with a locally installed SIP server in our Intranet for a POC and experiencing very bad Audio quality during Video call between 2 SipComm clients.
There is lot of jitter/stutter in the received Voice as well as loud screeching is heard intermittently. Also, voice quality differs from call to call; sometimes the jitter is so much that voice is un-intelligible but sometimes screeching noise is prominent. Currently using the Javasound implementation in Media options tab.
I tested the voice call using the Xlite and MS Office Communicator client in the same setup and obtained much better voice quality with them.
On analyzing the wireshark traces of calls, I found that SipComm is using 30 ms packetization period and sending 2 RTP packets together every 60 ms. I hope that would just add to negligent delay (call is happening in local network) and not the jitter.
Please let me know if there has been any fix done after alpha3 release which has resolved this issue.