Resources for Asterisk Application Development

Hi

I am currently developing an Asterisk application for my purpose that will capture frames from an incoming channel, process the frames and send back the frames on the outbound channel. But without a proper background in the fundamentals of Asterisk channels,frames etc., it is proving to be a hard task. Could anyone let me know some good resources from where I can get my fundamentals straightened? I have the book by O’Reilly but have not found any detailed material in it that may help me in developing my own application.
Thanks - Harshat

I would suggest looking at the source code for dahdi and libpri. I am not sure that you can do what you want with Asterisk directly.