@ Karlos
I know iprefs use the ruddy useless things (datatypes) I was meaning for viewing GFX or playing audio, I prefer to use a dedicated util for such things.
I've never read much of the docs for MorphOS and can't tell you which versions I tried as I deleted them all a long time ago, yep still no RTG board.
Most of the time I run a plain old 640 x 256 128 colour screen for Workbench and for GFX or DTP (ImageFX, DPaint, Pagestream, Final Writer etc..) I usually use 640 x 512 or higher.
Quick example of Lame V3.92, encoding an MP3 (10 seconds Audio)
Plain PPC = 31 seconds
MorphOS = 46 seconds
FrodoC64 emulator
Plain PPC Version = full screen GFX, full framerate + Audio
MorphOS Version = Window on Workbench no option for full screen/ skip every 2 to 3 frames (depending on game) No Audio
All I know is after years of testing I have found the best way for me to get every bit of speed I can out of my set up and tried all sorts things and different versions of various software along the way, but as I've said before I've disassembled a lot of stuff along the way and optimised it for my own use including the roms. I know from helping out others over the years unless your using the exact same set up as me then the way my miggies are set up you'd never get be able to get the same speed or use some of the modified code I use...
