[Asterisk-Dev] SIP/IAX repacking cpu cost?

Kevin P. Fleming kpfleming at starnetworks.us
Fri Feb 18 09:15:10 MST 2005


Andrew Kohlsmith wrote:

> I realize there's a performance hit to convert the audio from RTP to IAX2 
> audio but I am curious as to whether Asterisk has to actually do any work to 
> the audio itself or if it can just strip the RTP headers and prepend the IAX2 
> audio headers.

I haven't looked in detail, but I don't know of any reason why Asterisk 
would actually have to manipulate the audio data itself, unless 
transcoding is occurring.

It will have to pull timestamps out and package the data into IAX2 
frames, and if the IAX2 peers are using trunking then there is more 
overhead to queue the frames and trunk them together. None of this is a 
problem, of course, but it is a limiting factor to how many audio 
streams a single box can handle.



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