[Freeswitch-dev] Freeswitch communication delay after three hours

[Anthony Minessale]

you could set autoflush=true in the sofia profile so if it detects
prolonged packet build up it flushes the buffers.
VoIP is fun ain't it!

On Thu, Aug 26, 2010 at 7:59 AM, David Knell <dave at 3c.co.uk> wrote:
> On Thu, 2010-08-26 at 05:11 -0700, Bret McDanel wrote:
>> On Thu, 2010-08-26 at 13:19 +0200, Achim Stamm wrote:
>> > Mathieu Rene schrieb:
>> > > Hi,
>> > >
>> > > Lange nicht gesprochen. What can happen, usually, is network
>> > congestion causing a delay buildup over time (FS times its reads at
>> > every 20ms and returns a comfort noise frame if it can't get an RTP
>> > frame immediately). If frames come in 2-3 ms delayed because of
>> > congestion, delay can build up over time. If you are in a C module,
>> > you can send a message to the channel so it drops frames (essentially
>> > reads until EWOULDBLOCK).
>> > >
>>
>>
>> I am unsure if your explanation is correct.  If there is a delay of 2-3
>> ms 1 comfort noise frame should be generated (unless its doing
>> discontinuous media), after that it should have a buffer built up of
>> received frames so another delay of 2-3 ms would not cause an
>> interleaving of CNG and audio (which would degrade call quality).
>
> Have to agree with Bret here - the thing which causes noticeable delays
> to start to appear on long calls is a mismatch in clocks between two
> points on the chain.  One end sending packets slightly faster than the
> other processes them will result in an indefinite buildup in delay over
> time, unless:
> - the jitter buffering's clever enough to notice this, and chuck packets
> away;
> - the sender has silence suppression on (as in send nothing, not send
> CNG frames), and the party at that end occasionally stops talking (cue
> mother-in-law joke) at which point things get back in sync;
> - (possibly) there's a non-zero amount of packet loss, and the receiver
> doesn't try to fill the gaps by duplicating previous packets.
>
> --Dave
>
> --
> David Knell, Director, 3C Limited
> T: +44 20 3298 2000
> E: dave at 3c.co.uk
> W: http://www.3c.co.uk
>
>
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-- 
Anthony Minessale II

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