is there even any transcoding involved in your scenario?  Are the artifacts present in the inbound stream as well.  I would get a tcpdump and analyze the inbound and outbound streams to see a bit more detail of what is going on.

Mike

On Oct 14, 2014, at 5:12 AM, Iskren Hadzhinedev <iskren.hadzhinedev@ikiji.com> wrote:

Hi everyone,

 

Some of the calls using PCMA/PCMU have artifacts (distorted sound, “robotic” voice, stutter) on what looks like a random basis. The other codecs I have tried don’t have issues (tried GSM, iLBC,G722, G729, SILK). Apart from FreeSWITCH, the only other thing running on the machine is a static webpage served by nginx and the load is almost always at 0. Any help or advise on how to chase down this issue is highly appreciated!

 

System specs:
Machine: Xen VM
RAM: 1GB
CPU: Dualcore 2.4 Ghz 64bit
OS: CentOS 6.5
FreeSWITCH Version: 1.5.13b+git~20140621T003222Z~47891d5caa~64bit

 

Max # simultaneous calls: 12
Calls per second: at most 3

 

Endpoints used for testing:
Hardware phones: Yealink T42G, Yealink T48G, Gigaset DE900, Cisco 7975 (with SIP firmware)
Softphones: CounterPath Bria for Android, CsipSimple (android), Linphone, Jitsi
Mobile provider and a landline via gateway.