Audio has a licensing problem that art does not. The non-commercial license is far more common in sound libraries than in model libraries, and an audio file is the asset least likely to be checked before it ships.
#The safe ground
- Kenney publishes sound effect packs under CC0. Simple, game-shaped, and there is nothing to think about.
- Sonniss releases a large royalty-free sound library each year around GDC, permissive for use in games. Enormous, uncompressed, and worth the download.
#The mixed libraries
Freesound is the biggest and the one to be careful with. Every sound carries its own license, chosen by whoever uploaded it, and the mix includes:
| License | What it means for a game you sell |
|---|---|
| CC0 | Use it, no credit needed |
| CC BY | Use it, credit the uploader |
| CC BY-NC | Cannot be used in a commercial game |
| Sampling+ | Older license, read it before relying on it |
The non-commercial ones sit in the same search results as everything else and download into the same folder. Nothing about the file says which it was.
OpenGameArt has the same per-submission model for music and effects.
#Music has its own conventions
Composers who release free music usually do so under CC BY, and they usually specify the exact wording they want in your credits. That wording is on their page, not in the file.
This is worth respecting precisely because it is easy. A composer asking for one line in exchange for a soundtrack is the best deal in game development, and the only way to get it wrong is to lose the note.
#Where it actually goes wrong
Audio does not get checked, for three reasons that compound.
There is no thumbnail, so a folder of sounds is a list of names. Files get renamed early, because
birds_ambience_forest_02.wav becomes ambience_1.wav the moment it enters the project. And
audio is added late, during polish, when nobody is keeping records.
So the file that is most likely to carry a license you cannot ship under is also the one least likely to be traceable at the end.
Tessera previews audio with waveforms so a pack is browsable without a file manager, keeps the pack whole so the license file that came with it is still there, and records the license against every file in it. When the sound is copied into a game, the credit follows automatically.
Install Tessera, or read looking closely and licenses.