Software Support > GroovyMAME
groovymame and midway/mk games screen centering on TV.
Calamity:
--- Quote from: Paradroid on April 26, 2012, 06:04:41 pm ---So, what's going on here? At 59 Hz it's cut but at 55 Hz there's a full image? If that's the case, perhaps the TV is switching between PAL and NTSC mode automatically like the Loewes do...
--- End quote ---
It's definitely the dreaded PAL/NTSC mode switching issue but there's something more. On the Loewes the trigger factor seems to be the vertical refresh but here I think it's the total number of lines. In the first log he posted GroovyMAME was creating a 400x256@55 video mode and it was cut too. But when regular MAME accidentally picks 400x272@55 it turns out that the Sony TV adjusts the vertical size so the 256 lines do fit in the screen. That's very interesting. So Oliver, did you need to use the service menu at all?
oliver:
I know how to acces the service menu, but for now, all values are set to default. Even better, At 400x272, I can see a few spare black lines at the bottom of the screen (I believe).
Paradroid:
So, the TV is definitely omitting those extra vertical lines? It's not just a matter of overscan? Experimenting with the vertical size in the Service Menu will confirm this.
The trick will be, as Calamity has alluded to, to discover the logic your TV is using each modeline.
Calamity:
--- Quote from: Paradroid on April 26, 2012, 09:23:51 pm ---So, the TV is definitely omitting those extra vertical lines? It's not just a matter of overscan?
--- End quote ---
Well it's not omitting them because he's seeing black bands up and down. What happens is that MAME automatically centers the 256 active lines in the middle of the 272 usable lines, leaving 8 black lines above and below.
Basically, we have 2 situations:
- Input signal: 400x256@55Hz (256 active lines + 21 blanking = 277 total lines). The TV thinks: hey, this must be a NTSC signal (262,5 lines, 224 active), let's set v-size very wide so the picture covers the screen. Result -> our 256 lines are cut.
- Input signal: 400x272@55Hz (272 active lines + 21 blanking = 292 total lines). The TV thinks: mmmm, this looks like PAL (312,5 lines, 288 active), let's apply my v-size PAL preset so that the picture fits the screen. Result -> black lines up and down.
Of course there could be some intermediate cases, it's a matter of testing.
oliver:
--- Quote from: Paradroid on April 26, 2012, 09:23:51 pm ---So, the TV is definitely omitting those extra vertical lines? It's not just a matter of overscan? Experimenting with the vertical size in the Service Menu will confirm this.
The trick will be, as Calamity has alluded to, to discover the logic your TV is using each modeline.
--- End quote ---
I would say there are too many missing lines to be an overscan problem. I tried using the service menu to modify vsize and vcenter and even with the lowest values, there is a lot missing at the top and bonntom of the screen.
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