[Asterisk-Dev] High resolution timers using POSIX clocks instead of zaptel

Steven critch at basesys.com
Tue Jun 7 11:11:19 MST 2005

On Tue, 2005-06-07 at 13:54 -0400, Steve Kann wrote:
> If things are designed well, and you have 100ms of buffering ability on 
> inputs, you can do everything you need to with a 100ms timer;  Just 
> process whatever is there at the time.
> For example, if you have generators generating audio to be sent via 
> VoIP, then you just do it like this:
> time 0: send nothing.
> time 100, send frames 0, 20, 40, 60, 80.
> time 200, send frames 100, 120, 140, 160, 180
> ...
> Same thing for conferencing, etc.
> There's some more latency involved in using a longer timer length, but 
> there's also a lot more efficiency, not just from reducing context 
> switches, but also from cache locality, etc.

Ewww, echo. 100ms of input buffer and up to 20-200ms of transmit time
and you have a pretty nasty time of cleaning up that echo. How deep do
you think your echo canceler needs to look to clean up the call?

That is a great step backwards for those not on VoIP.

I doubt any efficiency you gain by consolidating your work would be more
than the extra created echo canceler work load.
Steven <critch at basesys.com>

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