Converting PowerPoint to .avi and .3gp format

Question

Dear coders,

I have a powerpoint file with narrations(also called audio recording). I would like to convert the ppt file into a .avi and .3gp format. Am comfortable with C#. I can also learn C++ . I have seen already existing systems that do it all, however their code is not available. :)

How can I move on with developing this application?

It will be helpful to get links to opensource solutions, or tutorials on how one can write an application that does the job.

Regards,
Simon.