[Freeswitch-users] In-call artifacts with PCMA/PCMU

[Anthony Minessale]

Also mind the hardware timing settings in the xen.  Virtual machines need
extra care for voip.
On Oct 17, 2014 10:03 AM, "Michael Jerris" <mike at jerris.com> wrote:

> The bad udp checksum can happen with cards that offload udp checksumming,
> which is common.  If you are not transcoding, we are not doing any digital
> modification of the codec payload, and its unlikely that the issue is
> related to anything freeswitch is doing.  You can confirm this by examining
> the audio stream of the incoming and outgoing rtp stream in wireshark.
>
>
> Mike
>
> On Oct 17, 2014, at 8:49 AM, Iskren Hadzhinedev <
> iskren.hadzhinedev at ikiji.com> wrote:
>
> Hello,
> Apologies for the late reply.
> I don’t think there’s any transcoding, as the endpoint negotiation is set
> to “generous” and examining the SDPs shows that both endpoints negotiate on
> PCMA/PCMU. I got a pcap of the RTP streams with tcpdump and I see that from
> the 126500 packets, 62964 are marked with “bad udp cksum”. All packets with
> bad udp checksum are originating from the FreeSWITCH box. Is this
> information helpful at all and what else can I do to figure out the reason
> behind these issues? Thank you!
>
>
> Kind regards,
> --
> Iskren Hadzhinedev
>
>
>
> On Tuesday 14 October 2014 10:03:32 Michael Jerris wrote:
>
> 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 at 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.
>
>
>
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>
> 
> 
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