VMMaker / Switchres issue using Nanao MS-2931 preset

[xga]

Hi All,

I’m having a few issues with my newly installed Groovymame set-up and I'm hoping for a bit of assistance from the kind folks here.   A bit of background info, I'm using Windows XP 64 bit along with an ATI 4890 video card and the intent is to use it with a Nanao MS-2931 CRT monitor in the near future.  For testing purposes, I am using a multisync LCD monitor (accepts 15khz / 24khz / 31khz signals and above) until I have everything configured correctly so as not to cause any damage to the Nanao MS-2931 CRT monitor.  I’m also using an Extron RGB interface to verify both the horizontal and vertical frequencies and that games are operating in their native resolution.

These are the steps that I have completed so far :

Installed Windows XP 64 bit, including all updates and drivers, but excluded the video card driver.
Installed MAME 64 bit.
Installed GroovyMAME 64 bit executable over MAME 64 bit executable. 
Installed CRT_Emudriver and VMMaker updates. 
Edited VMMAKER.INI file.
Changed MameExe so that it's pointing to the correct path for Groovymame 64 bit. 
Changed Monitortype to "CUSTOM"
Included the following monitor presets for the Nanao MS-2931 monitor :

monitor_specs0    15450.00-16050.00, 55-65, 3.19, 4.75, 6.45, 0.191, 0.191, 1.164, 0, 0, 288, 448
monitor_specs1    23900.00-24900.00, 55-65, 2.87, 3.0, 4.44, 0.451, 0.164, 1.148, 0, 0, 480, 768
monitor_specs2    31000.00-32000.00, 55-65, 0.33, 3.58, 1.75, 0.316, 0.063, 1.137, 0, 0, 576, 768

Saved and closed the VMMAKER.INI file.
Ran VMMAKER.EXE.
Edited MAME.INI.
Changed monitor to custom with the below presets

      crt_range0  15450-16050, 50-65, 3.190, 4.750, 6.450, 0.191, 0.191, 1.164, 0, 0, 192, 288, 448, 576
      crt_range1  23900-24900, 50-65, 2.870, 3.000, 4.440, 0.451, 0.164, 1.148, 0, 0, 384, 400, 0, 0
      crt_range2  31000-32000, 50-65, 0.330, 3.580, 1.750, 0.316, 0.063, 1.137, 0, 0, 480, 512, 0, 0

Rebooted.

The majority of 15khz games seem to operate fine in their native resolution, but I’m still having some problems with certain games and this is where I require some assistance from the Groovymame / VMMaker experts here!

With my current configuration, I can start the medium resolution (496x384) Sega game “Bonanza Bros” and it plays in it’s native resolution.  If I start Street Fighter II, Switchres reports that the closest resolution to the native resolution (384x224) is 384x240.  If I then change the value of “YresMin_XML” from 240 to 224 in VMMaker.ini, run VMMaker.exe again, reboot, start MAME and load Street Fighter II again, Switchres then displays that it will operate at the correct native resolution of 384x224.  However, if I now attempt to play Bonanza Bros again, Switchres reports the resolution as 640x480, which is way off the mark (31khz, instead of 24khz!).

What am I doing wrong and how can I fix it? 

Thanks in advance for any assistance you can provide!

[cools]

Dropping YRes_min will create more low resolution modes in the list and drop the less popular medium res ones.

There is no visible difference between playing 224p games in 224p resolution or in a 240p resolution, GM simply fills the blank space with black.

Leave YRes_min alone.

[xga]

Many thanks for your response, cools.

I'm still somewhat confused by your comment

There is no visible difference between playing 224p games in 224p resolution or in a 240p resolution, GM simply fills the blank space with black

  Are you able to elaborate or explain it more simply for a Luddite like me, please? 

I performed a bit more testing today, this time using the Nanao MS-2931 CRT monitor.  With YresMin_XML set to 240 and Switchres reporting 384x240p, the Extron RGB interface reported the game running at 15.72khz horizontally and 59.5hz vertically.  I then run VMMaker.exe again, this time with YresMin_XML set to 224.  After rebooting, Switchres reported the game running at 384x224p and the Extron RGB interface reported 15.37k horizontally and 59.6hz vertically (only slight differences between the two). 

With this in mind, are both the 224p and 240p resolutions running pixel perfect with no scaling and no difference to the game speed?  The MS2931 monitor definitely knows that the signals are different as it remembers the geometry settings for the 224p resolution that I manually configured, each time I change to 224p and it changes to a default geometry setting for the 240p resolution.  If it's recommended to keep YresMin_XML set at 240 to allow for the widest resolution compatibility, is it posssible to configure individual ini files per game (like Street Fighter) to use their native resolution or does this go against the whole point of using Groovymame?

I apologise for my CRT noobness, I just want to ensure that I am not scaling any resolutions and everything is as close to being pixel perfect as possible, thus the reason I'm using Groovymame.  Perhaps I'm going about this the wrong way or I've missed a certain tutorial or something... 

[cools]

Read this: http://forum.arcadecontrols.com/index.php/topic,139901
Which also links to this: http://forum.arcadecontrols.com/index.php/topic,131471
Of which the most pertinent post is: http://forum.arcadecontrols.com/index.php/topic,131471.msg1348221.html#msg1348221

It's actually really hard to get GM to do fractional scaling, it will scale integer (pixel perfect) and match the refresh rate without you needing to worry about it.

There's a bit of faith required initially, as the established idea of "native resolution" isn't what GM is about. In fact if it *did* go for native timings you'd be adjusting the monitor geometry controls constantly.