[Asterisk-Users] Re: OPAL now supports IAX2

[Peter Nixon]

On Sunday 07 August 2005 04:05, Brian West wrote:
> > What are the advantages of using woomera IAX2 instead of native IAX2?
>
> Put woomera aside right now, This is something that brings a cross
> platform IAX2 stack that can for example be used in Gnomemeeting or
> anything else that uses OPAL, using a closed and open familiar API.
> This can be used on windows, linux and anything that OPAL and PWLIB
> can be used on without any changes.  Its a step in the right
> direction in my opinion.

To clarify things a little, OPAL is a cross platform (Unix, Linux, Mac and 
Windows) telephony library written in C++ which among other things 
supports H323, SIP and now IAX2 thanks to Derek Smithies. It (and its 
older brother OpenH323) allows you to use a large number of Open Source 
Audio (including wideband) and Video codecs as well as commercial ones 
(like g729) as it is distributed under the MPL license.

The design of the API allows things like codec translation (GSM-g711) 
applications or protocol translation (SIP-H323-IAX2) applications to be 
written in 20-30 lines of code. (Video codec translation is also possible 
of course)

These and many other features can be used from client applications 
(SoftPhones, IP Phones, Gateways) and from servers like Asterisk. Thanks 
to woomera (another app from Craig Southeren) and chan_woomera (an 
Asterisk channel by Anthony Minessale) the VoIP Signalling and Media 
handling (RTP or IAX2) can be offloaded onto OPAL or OpenH323, thus 
bypassing many of the stability issues caused by the  poor locking and 
thread model in Asterisk.

Of cause an added bonus is that you may use commercial/patented/closed 
source VoIP codecs without voilating Asterisk'S GPL license.

A second implementation of the IAX2 protocol also helps with finding bugs 
(and other problems) in the reference implementation in Asterisk.

Although the IAX2 code in OPAL is still very new, the heavily multithread 
object nature of OPAL should allow much higher scalability than the 
existing library allows.

I hope that helps explain some of the possibilities

-- 

Peter Nixon
http://www.peternixon.net/
PGP Key: http://www.peternixon.net/public.asc