I tried using various separate versions and the retroarch versions of mupen and all have the same result, except one. They are all quite pixelated to some degree or another and the video quality is spotty. I assumed all the versions of Mupen were this way until I tried oxMupen64. With the few games I tried, this was very clean with crisp lines and good video quality. My primary game used for testing is Mario Kart 64. Unfortunately this version does not seem to be well supported and I am having issues making some basic changes, such as controller layout. I also can't figure out how to set stuff up to auto run. When I select the game to play out of big box, it loads the emulator but then I have to select the game from the list in the emulator.
How can I make either the well supported stand alone versions of Mupen or the Retroarch version of Mupen run smoothly with little pixelation?