There is no explanation about what OpenAL actually is and you first have to follow quite a lot of links and download an SDK (from the Creative site) to get information about what OpenAL actually is, but here is what I understand it is:
It's a new standard to create a kind of 3D sound landscape in the way that OpenGL creates a visual 3D landscape. It's not a general sound card interface (as I was looking for). It doesn't handle MIDI and it can't handle sound input (yet).
I was hoping that I could experiment with a kind of homebrewed VoIP with this library but that's not the case.
BTW. The "links to the DLL", don't actually lead to an DLL and finding one is very hard and I haven't found one yet, but at least I know now that I don't have to search any further.
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