Mednafen is a portable, command-line driven, multi-system emulator utilising OpenGL and SDL. Mednafen has the ability to remap hotkey functions and virtual system inputs to a keyboard, a joystick, or both simultaneously. Save states are supported as is real-time game rewinding. Screen snapshots may be taken, in the PNG file format, at the press of a button. Mednafen can record audiovisual movies in the QuickTime file format, with several different lossless codecs supported.
Don't use offical package, it's fairly archaic.
Instead use AUR which includes a man page based on official documentation.AUR available from the