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thp at westhawk.co.uk
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 Posted: Thu Feb 07, 2008 6:00 am Post subject: [asterisk-users] Preventing IAX frame concatenation |
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On 7 Feb 2008, at 09:17, David Hogan wrote:
| Quote: | Hi all,
I have spent some time searching, but I haven?t found a way to
prevent * from concatenating two frames into one IAX packet.
I have a situation where I make an IAX GSM call to *, which
transcodes to an iLBC SIP call. Every second voice packet the IAX
client receives contains 2x 20ms frames, the other containing only
one. I presume this is related to the mismatch of 20ms GSM vs 30ms
iLBC. What is odd, is that this doesn?t happen when I use G711 on
the IAX leg ? each packet contains 20ms.
Anyway, the IAX client I am using isn?t handling the 40 ms packets
gracefully. Is there something I can configure on * to prevent the
concatenation?
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As a hack, you could try forcing asterisk to transcode to slin, either
by recording the call or putting it into a conference.
There is also a recent change where you can force a jitter buffer on
the local channel which might help.
eg:
exten => _100[0-4],1,dial(Local/${EXTEN}@games_call/nj)
[games_call]
exten => _100[0-4],1,meetme(${EXTEN},nT)
Alternatively you could fix the client 
(We've recently fixed it for our web-based implementation on www.phonefromhere.com/tesco/
where we had the same
problem)
There are quite a few situations where asterisk sends IAX audio frames
that aren't the length that you 'expect'
It's best to have the client cope.
Tim. |
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david.hogan at freshte...
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| Posted: Thu Feb 07, 2008 7:39 pm Post subject: [asterisk-users] Preventing IAX frame concatenation |
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| Quote: | Alternatively you could fix the client
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Heh Although it's a situation that won't happen in (our) production,
for the sake of completeness I'll probably upgrade the client.
Cheers,
Dave |
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thp at westhawk.co.uk
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| Posted: Fri Feb 08, 2008 4:40 am Post subject: [asterisk-users] Preventing IAX frame concatenation |
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On 8 Feb 2008, at 00:39, David Hogan wrote:
| Quote: | | Quote: | Alternatively you could fix the client
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Heh Although it's a situation that won't happen in (our)
production,
for the sake of completeness I'll probably upgrade the client.
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Actually, it does (assuming you guys still run Tesco's UK service).
The first frame
in a GSM call is often 66 bytes, but there is only one of it and it is
at the
beginning of the call, so it's hardly a major problem.
Tim. |
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