Ernest Raspberry wrote:
Hello,
I'm experiencing some problems with running IAX2 protocol on quite reliable link with G729A codec. My customer has 2mb FR link to the Internet used in about 20%. Ping statistics:
50 packets transmitted, 49 received, 2% packet loss, time 49496ms rtt min/avg/max/mdev = 9.308/13.126/33.307/4.851 ms
Everything would be great, but the quality isn't good enough. I have 2mb/512kb DSL line, on which voice calls are working muuch better.
I've checked it on many ways. Hping tells me, that the average UDP packet loss rate is about 8-15%. Is that too much for IAX retransmissions ability? I've setup jitter with default settings from iax.conf, but the quality remains almost the same - it's still tooo jiiiiitttteery every few seconds.
I ran out of ways to test it. The conclusion remains the same - delays and delay changes should be good enough, but the packet losses remain too. I see some VNAK requests in my log files, but no more than 3-4 during ~40 seconds connection.
So should I fight the packet losses or tune my iax.conf options?
Presently, there's not much you can do with the quality in asterisk for this situation. IAX2 should keep the call up fine, but it can't conceal the lost packets at all.
I have been working on just this problem in iaxclient, and have just committed experimental code to work with this situation to iaxclient-cvs. Once it is ironed out there, it should be straightforward to add the jitterbuffer itself to asterisk (hopefully, to RTP channels as well as IAX channels, or even put it somewhere else within asterisk), as well as the packet loss concealment stuff (which would be a bit more work, as it involves modifying all the translators to understand that a voice frame with data length=0 to be a request for concealment.
The results, though, with packet loss in that range, are a huge improvement -- there's still noticable quality degradation, but no dropouts in audio.
-SteveK
_______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
