Confused about writing a media converter

I want to write my own media converter application using ffmpeg. I have a couple of questions

1. Can I use a command line to make the conversion. I don't think that would work if the user hasn't installed ffmpeg on to his system. If that's the case, how'd I over开发者_开发百科come it. I don't believe their API has anything for media conversion.

2. Is it possible to write it in Java?

You can provide an ffmeg binary with your application, and use the ProcessBuilder and/or Runtime class to invoke it. You would need a different binary for each OS you intend to target though.