[asterisk-dev] Meetme/Timing Basics

[Prakash Rao Kanthi]

Hi There,

I have been working with asterisk code base for a while now. I am well 
versed with asterisk applications, formats and linux low level internals. So 
feel free to put your answer in the terminology you can.

I have a basic question regarding the MeetMe application internals. HOW DOES 
THE TIMING WORK in MEETME? I know its using either ztdummy/rtc or digium 
cards. But i need the details. For example, if there are 3 people in a 
meetme conference, how asterisk/meetme/ztdummy are able to transmit 2 RTP 
streams from 2 of the three participants to the third participant as a 
single 64 kbps channel.

I see that meetme application is setting up pseudo device /dev/zap/pseudo 
with a conference number for the first participant and then on open the 
deivce for read/write for later participants. But it is not clear how the 
RTP is mixed by this pseudo device.

Which part of the code is doing Transcoding?
Any buffering going on? If yes, where in the code?
Which part of the code is doing RTP Mixing? (IN above example 2 RTP streams 
into 1)

You early response is appreciated.

Thanks,
Prakash