[asterisk-dev] [Code Review]: Adjust formats of chan_local when channel we proxying changes

irroot reviewboard at asterisk.org
Thu Sep 29 16:15:15 CDT 2011



> On Sept. 29, 2011, 3:51 p.m., David Vossel wrote:
> > /trunk/channels/chan_local.c, lines 615-619
> > <https://reviewboard.asterisk.org/r/1137/diff/8/?file=20921#file20921line615>
> >
> >     don't do this :)

im worried about locking in here and seemed like a good idea at the time ... its not critical and if we miss a frame or few ...


> On Sept. 29, 2011, 3:51 p.m., David Vossel wrote:
> > /trunk/channels/chan_local.c, lines 606-629
> > <https://reviewboard.asterisk.org/r/1137/diff/8/?file=20921#file20921line606>
> >
> >     This kind of constant checking of the format fields would work, but it is very expensive to do this on every audio frame.  Isn't there a way we can detect if we start getting a different audio format than we did in the past and use that to trigger that something needs to be updated?

Something like a "lastframe" in the pvt structure could be easy enough.

this is a fringe case the only time i have seen it was with a reinvite from low band to g711
on faxtone so its not common the idea is to fix it to prevent loss of audio.


- irroot


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On Sept. 29, 2011, 9:43 a.m., irroot wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/1137/
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> 
> (Updated Sept. 29, 2011, 9:43 a.m.)
> 
> 
> Review request for Asterisk Developers and David Vossel.
> 
> 
> Summary
> -------
> 
> This is a most annoying pain and tripped me up no end testing the T38 gateway patch for res_fax.
> 
> Scenario :-
> 
> i have a Linksys 2102 on a fax machine that uses G.729 and switches to ALAW on CNG and then negotiates T.38
> this is awesome as i can now Chat/Fax from same terminal using most effective bandwidth [these are to be deployed
> on sugar cane farms surrounding the kruger park here in south africa over wi-fi]
> 
> for testing purposes im using a local channel into T.30 fax app in res_fax.
> 
> Problem :-
> 
> when the device reinvites ALAW then T.38 it leaves the nativeformat on chan_local as G.729 this will not work
> as it is transcoding the FAX from G.729 to SLIN this will not work and took me a while to spot the problem.
> 
> Soloution :-
> 
> Check the format on the proxy and adjust it if it changes this should be what Local does been a proxy of the channel
> it should follow changes ...
> 
> 
> Diffs
> -----
> 
>   /trunk/channels/chan_local.c 338435 
> 
> Diff: https://reviewboard.asterisk.org/r/1137/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> irroot
> 
>

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