Watching demos in an NTSC zone (sync problems).

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mbricout
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Watching demos in an NTSC zone (sync problems).

Postby mbricout » Wed Feb 04, 2004 4:02 pm

Wasn't really sure in which forum to post this topic: hardware, demos, games?...

I am in an NSTC zone (in Canada to be specific). I recently got my hands on a 1040 STf and on a TV modulator called the Video Key (so that I could get color out of the machine, since it came with a B&W monitor).

GEM applications work fine.

Demos are another story. It seems like most of them force the ST video output to 50Hz, which my 60Hz TV doesn't like at all (I get a "scrolling" picture). I guess that forcing the refresh rate is necessary for certain effects such as overscan or syncscroll.

Some demos that work run two fast (those that rely on the Vsync for timing I guess), like the Poltergeist Demo: most obvious symptom is that the music is way too fast (they play at a ratio of 6/5 of the original speed, of course).

Some demos work, like the recent "Moving into Darkness".

I suppose I'll have the same problems with games (even though I hope that some of them that allow to switch the sync rate, such as Wings Of Death, will work).

Any feedback from anyone on this subject ? Are NTSC users condamned to an eternity of emulation? STeem and SainT are great, but nothing can replace the real machine :).

Thanks for reading,
Michael

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Postby simonsunnyboy » Wed Feb 04, 2004 4:25 pm

You're right. Overscan effects all use rapid switching between 50 and 60 Hz.
Music seems faster due to the fact that the replayer routines are hooked up into the VBL which occures *hey* 50 times or 60 times a second. As most demos want 50Hz for proper time, the music player gets called more often on NTSC displays hence why music is faster. You can observe the same effect running RGB demos on a VGA falcon, there the music is also faster.

A workaround would be a monitor or TV capable of 50Hz.
You're not condemned to emulation but as most ST users used 50Hz displays, most software using the hardware assumes you have 50Hz.
Actually here in Europe it's sometimes the other way round.
Due to a cheap 50Hz only TV I cannot get 60Hz on my 1040 which would be much more convenient while coding.
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Postby Ragstaff » Fri Feb 06, 2004 8:44 am

Couldn't you just use a program to switch the hertz? I think one was called *drumroll* 5060htz.prg ... or something obvious like that, it came with a lot Spectrum512 slidehows.
DC Boot IT may also be able to help you...

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Postby simonsunnyboy » Fri Feb 06, 2004 9:29 am

That wouldn't help as his TV seems not to be able to display 50Hz at all. Demos and games switch Hz by themselves in most cases.
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Postby mbricout » Fri Feb 06, 2004 10:30 am

That's right, the problem is with the TV itself (and/or perhaps the modulator).
Back in Europe, I had a great Thomson Scart monitor that could do both 50 and 60Hz: anyone knows if the SC 1224 color monitors sold in North America are 50 Hz compatible ?

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Postby simonsunnyboy » Fri Feb 06, 2004 10:34 am

I would suppose american SC1224 do both. Here in Europe they do and I don't think there were different production lines.
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Postby Sauron » Sat Feb 07, 2004 8:55 am

My old ST's never had any problems with running in 50hz mode, although you will notice the screen flicker a little, and the picture might need a little adjusting to get centered. Going back to 60hz will put it right back to where it was, though.

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Postby mbricout » Mon Feb 09, 2004 12:09 am

Thanks to all for your help. I'll now start a quest for a SC1224 monitor. Won't be easy... Seems like most STs where sold with B&W monitors in here (at least all the ones I could track down were).


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