Where can I lay my hands on short musical pieces to add to short video productions? I would need them to be royalty-free and to be certain that I'm not infringing on anyone's copyright.

They would only have to be anything between 30 seconds and a couple of minutes in length. I would like to find instrumental and orchestral pieces and want to compile a very varied collection of resources.

I don't need anything with lyrics, just music that I can use without restrictions where I don't need to worry that I'm not supposed to. If they are totally free of both cost and restrictions that would be even better.

I wouldn't mind crediting the composer at the end of the video in exchange for its use if there are any youngsters out there that would like to give their music more exposure in the productions. This is a future project.

Suggestions on ways to go would be appreciated. Thanks!