That’s an interesting problem and I appreciate it deeply since some of our projects here at Epic can mean 200+GB perforce sync’s.
Ogg Vorbis (and other compression formats) are employed during the cook process.
This is relevant to packaging, but in the Editor, during development, an uncompressed version is stored in the SoundWave asset. This allows users to set Compression Quality levels for their game and then to change their minds later.
For example, if you leave the Compression Quality setting for your birds at 40/100 which is default and then later on, you realize that your birds should be less compressed because you’re getting some lossy artifacting in the high frequency range, then you want to be able to change your mind about that quality setting.
If you imported and stored the file in its compressed state and treated that as your original file, then you would never be able to back-track. You would only be able to lower the compression quality, never raise it.
This is why the best practice is to keep uncompressed versions of your sounds in your project until you’re ready to cook.
Our long-term road map includes expanding the formats supported for import, and along these lines, we’ve already licensed libsndfile. These will likely be the first ones we support before we get to mp3.
I think mp3 could be interesting for a project that uses user music, like a game that plays the user’s music library or something, but as a designer, I cannot advise someone to store their original sound source files in a compressed lossy format.