Using FFmpeg native libraries with Android-NDK

Question

I could write a simple "Hello World" app and got it to compile and run ok, I know how to setup basic structure of an Android project to use native libraries. Could any one tell me how to use FFmpeg libraries to decode a video;

• How to write a .cpp file to decode a video file using the libraries(Open, Decode, Save)
• How to setup source files(in my case .cpp files) with Android.mk file

Please could anyone help.