Well, it depends on what you want to do and what files you want to use. First of all, freesound lets the user select 3 one of three licenses for his sounds. And, we used to have a 4th license, which complicates matters. Depending on the license there are things you can and can't do with the files. Let's start with the licenses. Creative commons has a really nice page explaining them:
We aren't lawyers so this isn't legal advice, but here's our summary: for "zero" you can do pretty much what you want with the sound. You could even sell the sound, ... but you can't claim you are the author! For attribution you should always mention the original creators of the sounds when you use them. Noncommercial works like attribution, but you can't earn any money with the piece of work you create! As with all licenses the original creator can give you permission to use the sound outside of the original license.
In freesound "1" we had an additional license called Sampling+:
Our interpretation: you can do pretty much what you could do with the attribution noncommercial license, but additionally you can't make commercial adds with the sound. You can't make a track with Sampling+ samples to sell a car, for example. Sampling+ is being removed by creative commons because it's a difficult license to interpret,
see below for more on that.
Now I can already hear you saying, "attribution", how should I do that, so see the next section!
How do I credit/attribute?
Crediting people is easy, just say something like this:
This [video/theatre piece/...] uses these sounds from freesound:
sound1 by user1 (
http://freesound.org/people/user1/ )
sound2, sound3 by user2 (
http://freesound.org/people/user2/ )
etc..
If you want to know which files you have downloaded since you joined freesound, you can see this in the attribution list
attribution list.
If you have a particularly long list of files or very little space to attribute sounds you can always do:
This [video/theatre piece/...] uses many sounds from freesound,
for the full list see here:
http://www.mysite.com/work-credits.html
If you want to see a
practical example from the movie Children of Men.
