Quote Originally Posted by noeska
The compression ratio is not controlleable?
Btw it would be nice if you posted some info on how you got GL_COMPRESSED_RGBA working.
When creating your texture with glTexImage2D instead of using GL_RGBA for the internal format, just use GL_COMPRESSED_RGBA. I had a small problem with my compiler not recognizing this, but that was just because I also had to have glext.pas as a unit.

The documentation says that you can choose between a "FASTEST" and "NICEST" compression algorithm via glHint, but they seemed equally artifacty to me and the compressed textures used the same amount of memory (maybe my setup only supported the one compression algorithm - don't know).