[Freeswitch-users] Doubts over G729 passthru for 50ms ptimes

[Kristian Kielhofner]

RTP timestamps = ptime x 8, so:

PTIME:timestamp increment
10:80
20:160
30:240
40:320
50:400

  Your endpoints seem to be writing their RTP timestamps correctly.
For the endpoint that's all over the place, check the hardware.  I've
seen bad DSPs, etc cause strange RTP skew before.

On Tue, Dec 4, 2012 at 3:40 PM, Ben <ben122uk at gmail.com> wrote:
> Hi Brian,
>
> I looked at the timestamps for both RTP streams that are being sent by each
> client, it appears that the timestamp increments by a value of 400 for each
> packet, for both streams.  I can also see this in FS for each stream -
>
> 2012-12-03 15:51:03.374955 [DEBUG] sofia_glue.c:5094 Audio Codec Compare
> [G729:18:8000:50:8000]/[G729:18:8000:50:8000]
> 2012-12-03 15:51:03.374955 [DEBUG] sofia_glue.c:3077 Set Codec
> sofia/internal/1002 at 192.168.17.154 G729/8000 50 ms 400 samples 8000 bits
>
> Looking at the Freeswitch log, I'm guessing that the timestamps set by the
> client correlate to the sample rate set by Freeswitch?  Or am I not on the
> right track with what you were suggesting?
>
> I've also noticed that when using 50ms ptimes, one of the RTP streams from a
> client is not very 'steady'.  One stream seems acceptable, with only one or
> two packets straying to 60ms, and jitter hovers around 2-3ms.  However the
> other stream really struggles, the delta(ms) values in wireshark are all
> over the place.  This is the summary of a 20 second RTP stream in wireshark
> -
>
> Max delta = 120.95 ms at packet no. 1250
> Max jitter = 22.00 ms. Mean jitter = 18.12 ms.
> Max skew = 65.24 ms.
>
> This seems odd since the test I did was all internal on the same LAN.  I'll
> try and track down the cause tomorrow by switching around some kit so that
> it cuts out any potential problems.
>
> Are there tolerance levels in Freeswitch for RTP streams that are affected
> during transit?  If so, how does Freeswitch react when one of these
> tolerance levels is exceeded?  My FS server seems to just hang during call
> setup, and no RTP stream is sent out the server to the clients.
>
> Thanks for the help, I'll let you know how I get on tomorrow with some
> further tests.
>
> Regards,
>
> Ben
>
>
> -----Original Message-----
> From: freeswitch-users-bounces at lists.freeswitch.org
> [mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of Brian
> West
> Sent: 04 December 2012 15:11
> To: FreeSWITCH Users Help
> Subject: Re: [Freeswitch-users] Doubts over G729 passthru for 50ms ptimes
>
> PCAP's will show you.... I suspect something is telling a lie about the
> timestamps.  Very common.
> --
> Brian West
> brian at freeswitch.org
> FreeSWITCH Solutions, LLC
> PO BOX PO BOX 2531
> Brookfield, WI 53008-2531
> Twitter: @FreeSWITCH_Wire
> T: +1.918.420.9266  |  F: +1.918.420.9267  |  M: +1.918.424.WEST
> iNUM: +883 5100 1420 9266
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> ISN: 410*543
>
>
>
>
>
> On Dec 3, 2012, at 9:31 AM, Ben <ben122uk at gmail.com> wrote:
>
>> I tried setting the {passthru_ptime_mismatch=true} variable in the
> dialplan, but no joy unfortunately.  I'm also fairly sure that the codecs
> are matched on both call legs, so shouldn't be having that sort of issue.
>>
>> I'm going to gather up some evidence and console logs/traces etc so that I
> can put something together for a bug report on Jira.  Is there anything else
> that someone can suggest I try before it goes on Jira?  Is anyone able to
> re-produce the same problem?  Admittedly, I'm not on the latest GIT, but I'm
> on a recent (last couple of months) stable release.
>>
>> Thanks in advance for any assistance!
>>
>> Regards,
>>
>> Ben
>>
>
>
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-- 
Kristian Kielhofner