The NEW Build Your Own Arcade Controls

Main => Monitor/Video Forum => Topic started by: Mordy Ovits on October 14, 2002, 02:19:11 pm

Title: Non-square pixels cause odd scaling?
Post by: Mordy Ovits on October 14, 2002, 02:19:11 pm

I compiled the latest prerelease of xmame on linux.  It has newly added Xv support, which gives awesomely fast hardware scaling and fullscreen mode.  For the first time, it fills my 1280x1024 screen w/o frame drops.  It even drops CPU usage to 50%!

Here's where it gets weird.  I'm playing the games that I remember from my high school days.  I vividly recall that these games were played on  a 4:3 ratio monitor.  Yet the games have a resolution of 384x224, which is about 1.7:1, not 1.33:1.  That means that the original game had nonsquare picxels?!?!  The result is that Xv's scaling assumes proportional scaling, leaving black bars on top and bottom of the screen.

Before I go modify the Xv code, does anyone know how the original arcade worked?  Were the pixels non-square, or is my memory faulty?

Title: Re:Non-square pixels cause odd scaling?
Post by: MameFan on October 14, 2002, 03:19:55 pm

Remember.. In the old days, monitors didn't have all the esoteric geometric controls (pincussion, trapezoid, rotation, linearity), let allow full width and height horizontal/vertical sizing!

I remember many a game (and have picked up a few with burn-in patterns to match) that left a good 1/2" gap around all sides of the tube untouched, or crunched to one corner of the screen.

You'd be hard pressed to find a game scaled to match the exact pixel ratio.  Differences in magnetic location with respect to the earth, fluctations in power line frequency and of course, drift due to heat/use of the tube overtime, it would have been dumb for mfg's, let alone arcade owners adjust a tube so the pattern filled the screen 100% edge to edge, even if the hardware had allowed them to do it.  Because they'd be spending time every few weeks adjusting them back onto the screen, because if the playfield was clipped, you're not going to get someone dropping quarters in!

I frequently remember seeing MoonPatrol appear in a SQUARE screen (almost like a vertical game drawn in the middle of a horizontal monitor!) rather than a wide horizontal one.

Looking at the awesome controls of the Electrohome G07 monitor that has all of 3 jumpers to set vertial and horizontal size, no wonder there were strange aspect ratios to the games we all remember playing!

Title: Re:Non-square pixels cause odd scaling?
Post by: Mordy Ovits on October 14, 2002, 03:33:15 pm

I guess I'll just hack Xv to scale as I like it.  I'll probably make a -nomaxpect argument.