How to "tweak" interlaced resolutions?

[emubastard]

So I finally figured out what I was doing wrong with my BVM.  The upside is, I can use the standard NTSC crt range and it works great  between 224p and 288p.  However, after learning how to force groovymame to ignore higher resolutions and generate 480i I noticed that, sadly, the 480i image was incorrect.  It's flickering horribly.  Towards the bottom of the screen the image is vertically misaligned by 3 or 4 scan lines making for terrible flicker and a rediculous look picture.

The one modiication I made to the crt range for NTSC was to allow it to generate interlaced up to 512 lines.

Now, when I play a game in groovymame that displays at 512i, like Journey, or Discs of Tron, there is very little flickering and the odd and even fields seem to be lined up really well.  In fact it looks fantastic.  It just seems that the 480i fields are not aligned right for whatever reason.

I surmise that this is because the crt range is just that, a range, and I need to manually tweak the 480i resolution in Arcade OSD after I run vmmaker, as is talked about in the documentation.

Sadly, because I have a 480p defined as a crt range, vmmaker generated a 480p resolution, and not a 480i that I can tweak with Arcade OSD.  Now I know I can remove the 480p modeline, then manualy tweak 480i in arcade osd, but then if I want to use 480p, I'll loose my 480i tweaks when I re-run vmmaker to add back the 480p resolution.

So I think I really need to get in and adjust the vertical sync width in the 480i resolution (I think that's the cause), but if I do that, it gets overwriten when I run vmmaker later to add 480p back in to the mix.

Does this make any sense?

What the best way to go about dealing with this issue?

-Emubastard

[Calamity]

Hi emubastard,

As and advice when opening a new thread, refresh our memory about your settings (video card, etc).

Interlaced modes just don't work properly in some configurations for unknown reasons. I bet that if you plugged that signal to another monitor it would display fine.

That said, you can move around your modeline tweaks without worrying about vmmaker ovewriting things. When you exit GM, open notepad, press CTRL+V and there it is the last modeline used. Open Arcade OSD, select "Modeline from clipboard" and it will display the modeline in clipboard to allow tweaking. Once modified, select "Copy modeline to clipboard", then paste it back to notepad. You will get one modeline and one custom ready made crt_range. Now you have two options, either drop that raw modeline into the game's ini, or use the crt_range (better: use only the horizontal and vertical geometry settings from this crt_range rather than the frequency ranges).

[emubastard]

Monitor: BVM-D24E1WU
Video Card (recent upgrade): ATI Radeon HD 4870 X2
Other:  Devils Canyon build, Windows 7 x64
Driver: crt_emudriver 2.0b3

I would like to think it's not the monitors fault, even if pluggin into a different one would work.  I say this because it's a video production monitor, that was used in television studies and inherently runs 480i.

Manual: "Multiformat
The monitor supports the principal formats (480I/
480P/720P/1080I) for the digital broadcasts, NTSC
and PAL color systems, and a wide variety of signals3)
whose horizontal frequency is between 15 kHz and 45
kHz."

I also witnesses this very recently on my older ATI Radeon HD 4850 graphics card I was using just a few days ago so I was hoping there was something crt_emudriver related I could do.

But at any rate, I'll play around with it some more.  I have had both 480i and 512i working perfectly in the past using non-NTSC timings, but they were a horrible mess and I recently figured out that I could use NTSC timings (duh).  I achevied this by messing about with the vertical sync width.  So I know it can be done, I'm just trying to figure out the best way of doing it.

Thanks.

[emubastard]

When you exit GM, open notepad, press CTRL+V and there it is the last modeline used.

Hmmm, this isn't working for me.  I launched groovymame from a desktop shortcut, ran the rom, exitid, then run the rom directly on the command line and exited.

In both cases, the only thing that pastes into my clipboard is not a modeline, but that last thing I manually copied.

I went and looked in my dotrone.cfg and found a modeline, maybe that will work.

[emubastard]

Well I was able to get it working.  By modifying the vertical sync width, and playing with the vertical positioning on the extron 203, I was able to get a clean interlaced picture in both 480i and 512i.  I was also able to do this on a per game basis with crt_range if I wanted to.

So it seems it can be correct, at least in my case.

I suspect the issue is not the monitor, but something to do with the signal not being quite to spec when being generated by the video card and then translated to rgb through the Extron 203.  The Extron 203 does indeed modify the signal to the users prefered vertical and horizontal positioning.

For anyone reading this that doesn't know, The Extron 203 is a device that takes in a VGA analog signal, and converts it to RGB+Sync output for BNC RGB monitors.  It has the advantage of that it seems to be able to remember an endlessw amount of resolutions in regards to the users preferered vertical and horizontal positioning of the image.  It's really quite fantastic, but it probably does have something to do with needing to tweak the sync width, unless it's just the nature of trying to get that exact signal out of the video card.

At any rate, a little persitence is all it took.

Thanks.