[Asterisk-Dev] Silence suppression in asterisk/chan_sip?

[Kevin P. Fleming]

Olle E. Johansson wrote:

> Interestingly enough, and a lot of people have missed this, the RTP 
> driver changes to zaptel timer if we are put on hold and goes back later 
> on when the caller comes back. This was done to support MOH. Maybe 
> anyone with better insight than me in the RTP driver can look and check 
> if that would work for silence suppression as well... Switch temporarily 
> to zaptel timer and then back when we get the feed from the other end...

I've thought about this too, but I think the overhead of every RTP 
stream using the timer separately would just be too much. I think the 
best solution is for rtp.c to create a thread when it loads, use the 
zaptel timer to clock that thread, and have all outbound RTP sent by 
that thread based on a reliable clock source.

This would also help with RTP bridging, since there would only be one 
bridging thread, not one for each call.