[Speex-dev] Re: [Iaxclient-devel] iaxclient & speex

[Alexander Chemeris]

Hello,

On 5/4/07, Jean-Marc Valin <jean-marc.valin at usherbrooke.ca> wrote:
> > As far as gain changes messing up the rest of the preprocessing chain:
> > It would seem to mess up the denoiser, the VAD logic, etc., as well as
> > the echo canceller.  It might be possible (as I wrote earlier) to give
> > the filter chain some hints about what the effects of the changes are,
> > but it probably won't be perfect, because it would be difficult or
> > impossible to predict the exact response of gain adjustments, and the
> > delay after which they will actually take effect.
>
> Well, I guess you could:
> 1) say "freeze!" to everyone
> 2) increase the analogue gain
> 3) let everyone know by how much the gain was increased
> 4) wait a little while (e.g. 100 ms)
> 5) unfreeze everyone

Similar (same may be) mechanism may be used to prevent AEC
upset in case user change mic or speaker (analog) gain manually.
Application might detect all HW mixer changes and report them to speex
library even if AAGC would not be used. Speex library will do essential
actions to prevent AEC mess. So, there should be some generic API
to notify Speex about HW mixer level changes. What do you think?


-- 
Regards,
Alexander Chemeris.

SIPez LLC.
SIP VoIP, IM and Presence Consulting
http://www.SIPez.com
tel: +1 (617) 273-4000