How to implement a voice changer?

Question

I want to write a app which change the microphone input voice and make it like robot or some funny man\'s voice.It must support send changed voice to all application like IM Sof

Answer 1

You are looking to support VSTi or DXi plugins.
There are tons that also act as vocoders, even for free.
You just need to write the host application. Take a look here :)