Any .wav you import get’s compressed into some other format anyway and is decoded at runtime. I always thought they compressed to .ogg in the engine anyway, which is why I’m baffled you can’t import them straight off.
Full-size audio files are way too massive to ship otherwise, it’s better to compress it and decompress at runtime.
Seems Hevedy is correct, Vorbis is completely open-source:
Thanks for that link actually, that probably suits my playlist system better in the long run!