Screenshots -> Video file

Question

I want to convert a folder full of screenshots into a movie (.avi file) with a certain frame rate, is this possible?

Say the folder has 48 images and the frame rate is 24 frames per second, that would then result with a 2 second long video.

Also, would it be possible to then add sounds to specific points in the video? Say, play "explosion.wav" after 10 seconds?

NOTE: I am not looking for a program that does this, I know they exist. I want to know how to do this with C# code.