mpap is a MPEG Audio Player
Version: 2b1mpap is a MPEG Audio Player used for playing "mp3" files.
Operating System: Mac OS X
mpap allows you to play MPEG audio files on OpenStep/Mach 4.2 (Intel only; NeXT hardware isn't fast enough to decode mp3's in realtime), MacOS X dp4, and MacOS X Server (PowerPC).
The most common use of this would be for playing "mp3" files, which proliferate wildly on the internet.