Re: [Iaxclient-devel] codec support

[Adam H. <ad...@te...>]

Steve Kann wrote:

>
> I'd just look at asterisk's implementation for ideas [although not 
> code, because asterisk is GPL].
>
> The 20ms frame size vs 30ms preferred frame size for iLBC will be an 
> issue that needs to be dealt with when you make codecs modularized.  
> Personally, I'd say that one should start with G711a/u, because the 
> implementation of that will be about 50 lines of C code for coding and 
> decoding (maybe less), and the bulk of the work will be in just 
> modularization.   To be sure you get the modularization right, make 
> G711 work with 20ms or 30ms frame sizes.  Then once that's working 
> (and you haven't broken GSM, because you'll need to modularize that as 
> well), adding any of the other codecs will be just a matter of the 
> proper cross-platform Makefile-fu plus a small amount of glue code, 
> and you'll have two examples of how to do the glue code.
>
> An experienced programmer should be able to do this (G711, GSM, iLBC) 
> in somewhere like 5 - 20 hours or so. 
>
>
Unforunately, Asterisk only supports 30ms iLBC frame size :|  I was 
going to try and fix it but I'm always wary of changing asterisk in many 
places. If you modularise codecs, it's very easy to add new ones. I 
added g729 and g723.1 in a few hours. (as dlls though :p) I'll do speex 
when I can be bothered.