I've done a bit of searching around for this but I'm not quite sure what to call my issue. Long story short I'm building a cabinet and using a pi with piplay as the guts of the machine. I have sorted out most of what I need, that being rotating the monitor 90 in the config.txt as well as playing about with the framebuffer width and height settings so that mame will launch without issue. Now the piplay menu is fine and fills the screen not problem but the games themselves take up about a third of the screen?
What I'd like to do though is get roms to boot to a bigger size i.e. I'd like the gameplay to be in the standard 19" (I have a 21-ish" monitor) in the proper 3:4 (because its rotated) ratio or close to.