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Incorrect refresh rates for TI994a and Coleco/Adam #34088 09/28/07 06:03 AM
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Jonah Offline OP
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Both the TI 99/4a and ColecoVision/Adam are listed as using a 60hz refresh rate. This is also the refresh rate I'm using on my LCD monitor, but I have noticed the following issues:

With automatic frame skipping enabled, the speed fluctuates between 98 and 102%. Just as MAME does when you are running an emulation with a refresh rate higher than the display you are using.

If automatic frame skipping is disabled the speed runs at 99%, but with occasional audio hiccups.

If I enabled cheats, hit ~ and lower the refresh rate to 59HZ, then the speed runs perfectly at 100% with no audio issues.

Is there a problem with my system/settings, or is it possible the true refresh rate of both these systems (both use the same display chip, IIRC) is something closer to 59hz, but MESS is set to run it incorrectly at 60hz.

Re: Incorrect refresh rates for TI994a and Coleco/Adam [Re: Jonah] #34106 09/28/07 08:28 PM
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Justin Online Content
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If you have triplebuffer or vsync turned on try turning them off.

Re: Incorrect refresh rates for TI994a and Coleco/Adam [Re: Justin] #34118 09/29/07 04:03 PM
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Jonah Offline OP
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That seems to have fixed the problem, it now runs at a perfect 100% and the video seems smooth, which confuses me.

This is a new computer for me. My old 1ghz/Geforce4 machine I ran both MAME and MESS at 640x480 @ 60hz with Triple Buffering turned on using Direct Draw. Now I use an LCD monitor set at 1440x900 @ 60hz using Direct3D. I must say, one of the things I LOVED was that MAME keeps the aspect ratio 4:3 on my 16:9 monitor by default. It's nice to see video done correctly.

But I'm having trouble getting 100% smooth results in both MAME and MESS. A frequent test I use is the arcade game Strider. The search lites at the beginning of the level pulse at 30hz. They flicker perfectly, except for a period of about 1.5 seconds every 12 seconds it becomes imperfect. I do not recall having this problem on my older system, but then again, I could not run the newer versions of MAME on my older machine.

Perhaps I'm being too anal. I'm actually more curious if 100% timing accurate video is even possible on the PC. And now, I'm puzzled as to why I get smooth video WITHOUT Triple Buffering or Vsync. D3D is less reliant on these?

Re: Incorrect refresh rates for TI994a and Coleco/Adam [Re: Jonah] #34119 09/29/07 04:24 PM
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R. Belmont Online Content
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Frankly, tearing is less noticable on LCDs than CRTs. I'm not sure why, but I find no-vsync perfectly fine since I switched. As far as the pause every 12 seconds that sounds like maybe some sort of antivirus or something waking up and stealing some CPU time. That stuff can be hard to track down though.

Re: Incorrect refresh rates for TI994a and Coleco/Adam [Re: R. Belmont] #34120 09/29/07 04:51 PM
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Ahh.... Triple Buffer wasn't required because I have VSYNC forced on in the 'Nvidia Control Panel'. When I force it off, I get tearing again, with or without Triple Buffering.

Either way, it's rockin' now. :-) Thanks guys.


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