What is maximum TV resolution without using interlace?

[adder]

hi all so i was messing around with my pc connected to my crt tv, using a vga to scart cable

i was testing 640x480 interlace mode

can anyone tell me, what is the max resolution i can set in powerstrip without having to use interlace

note: the resolution must be 60hz

[MonMotha]

This will depend on your TV and, to some degree, your tolerance for risk.

You can pick any number you like for the horizontal resolution.  The TV won't know or care.  You just have to consider that only a number that is 4/3 of the number of lines (vertical resolution) will give you square pixels, which may be what some software expects.

For the vertical resolution, you have to identify a maximum horizontal scanrate you're willing to subject your TV to.  NTSC TV runs at 15.734kHz, but you can potentially fudge things a bit higher without breaking things.  As you go higher, some TVs will eventually not sync up while other TVs may sync up but damage themselves, hence your tolerance for risk coming in to play.  You can generally get to at least 15.75kHz on an NTSC TV without breaking anything.  I wouldn't go much above 16kHz.

You also have to identify how many blanked lines you need.  Again, this depends on your TV and tolerance for risk.  NTSC specifies a lot, but most TVs don't need anywhere near all of them to work right.  The VESA CVT formulas are a great place to start, but they'll tend to shove your vertical refresh rate around for reasons you probably don't care about, so you probably only want to use it for porch calculations.

tl;dr, anything over 256 lines of visible image is probably pushing it too far.  That works out to 16.2kHz at 60Hz if you use a total line count of 270 (4 lines each of front and back port + 3 for sync).

[adder]

thanks for your response, so if i understood you correct, to be safe the maximum shouldnt really be more than:

340 x 255 @ 60hz

ok? (if i can go a bit higher in resolution and probably not cause damage, let me know by how much )

hmm, this is interesting as it means (i think) i could play a vertical game like terra cresta which is 224x256, but display it horizontally on the screen and only lose one line...

[MonMotha]

Basically, you're probably good to (anything)x256 @ 60Hz, so 340x255 is *probably* OK.  That would be near the extreme end of what I'd push a normal TV to at 60Hz.  Of course YMMV.  If your TV makes bad noises, turn it off right away.

Any higher than that and start to run a real risk of breaking the TV.  256 visible lines at 60Hz is already ~16.2kHz, which is well above the 15.75kHz used by NTSC (PAL is 15.625kHz) but probably within what most TVs can handle.

If you've got a European TV (or even many US TVs), you can reduce the refresh rate and get more resolution.  Same tradeoff PAL TV made.  Of course, you'll probably want to match whatever game you're emulating.  In general, if a standard res arcade monitor would do it, a TV is probably OK with it as they have similar capabilities.

[adder]

hmm, this is interesting, i wonder then what would the maximum 'safe' resolution be at 57hz?

i ask because, something like mameuifx or cabmame etc, lets you force all games to run at 60hz smoothly without sound hiccups etc (by using soundsync feature)

imagine if it was changed so that instead of 60hz you could force all games to run at 57hz smoothly. there wouldnt be too much of a difference in game speed for a 3hz drop, but that would give some increase in possible max resolution?

mind you, then of course the tv would have to be able to handle 57hz (which forum wiz rcadegaming says is ok )

anyway, its kinda cool i notice when running vertical games horizontally on a tv, that for certain games over 255 lines tall eg. CONTRA 224x280, in mame you can go into the Slider Controls menu, and move the game screen up or down, so eg.. with contra, you can simply choose not to display the top part of the screen, which is not important anyway unless you care about the score (See pic below.. the red box is 255 lines high):



this works for a lot of games... even pacman at 224x288 (however, you can only just about see how many lives you have remaining )

[rCadeGaming]

Yeah, you shouldn't be picking a refresh rate and trying to force the game to it.  You should be adjusting the output refresh rate to that of the original game.  Doing this and using -syncrefresh will be the way to ensure the game is running at original speed, without sound issues (soundsync not needed), scrolling smoothly without -waitvsync and -triplebuffer (which cause lag) and without frameskipping.

As far as how high many lines you can get your out of your 15kHz TV, pushing it is not likely to damage anything, it will just lose sync before that point if you push the scan rates outside of what it can handle.  As MonMotha says, you can trade off some of the front and back porch lines (same as blanking lines) to use as active lines.  Doubling horizontally is useful in some cases to keep pixel clock in line.

As far as actually being able to see these extra lines on the TV, you'll have to reduce the vertical stretch on the TV itself to see much more than 240 lines, and that will make your 240 line or less resolutions squished.

I can run R-Type (256 lines), but a few lines are cut off at the top and bottom (same issue you're showing with Contra and Pac Man there).  I just shift it up a bit to see the info at the bottom, as there's not much going on at the top.

Sometimes there's room for a compromise like that, sometimes not.  With most vertical games, you need to actually rotate the monitor, or just scale them in 480i.

Edit: I originally said R-Type is 288 lines.  It was a typo/brain fart.  Everything still applies.

[adder]

I can run R-Type (288 lines)

? perhaps u meant another game, rtype = 384x256 horiz

With most vertical games, you need to actually rotate the monitor, or just scale them in 480i

im kind of undecided with vertical games at the moment. im not actually too keen on physically rotating the screen as i find with a large rotated screen eg. 21" the screen is almost too tall, especially if you have a cab where your face is close to the screen. so you end up having to look up and down the screen all the time instead of being able to see the screen all at once as a whole (which i prefer)

so instead i think i prefer displaying vertical games horizontally on a 21" screen, so overall it looks more like how the game would look if it was displayed vertically on say, a rotated 16" screen. it just makes it easier to see the game action all at once. plus you dont have to keep rotating the monitor all day and manual degaussing (its not too hard to add a manual deguass button to any tv by the way, see here: http://www.ukvac.com/forum/plz-help-me-add-manual-degauss-button-to-circuit_topic328792.html
..and also no need to own 2 cabs

as for then having black borders on the left and the right of the image (perhaps also top and bottom for some games), that doesnt bother me too much.

mind you, the big downside of course as we all know... loss of lines, interlace, scaling etc

anyway i dont know, we'll see (im still in early stages of mame cabbing )

[rCadeGaming]

? perhaps u meant another game, rtype = 384x256 horiz

Son of a b*tch, you're right.  I did mean R-Type, but remembered the resolution wrong.  Brain fart, hadn't worked on that in a while.  Everything still applies though.  As I said, it's hard to get much over 240 lines.  I had to do that vertical shifting just to see everything at the top of R-Type's 256. 

I could easily reduce the vertical stretch in the TV's service menu, but that affects everything.  I let the rarer cases take the compromises, in favor of allowing more common resolutions to be perfect.  For me it's really the console games that dictate the TV geometry.  They have fixed timing values obviously, so I adjust the PC around what works for them.

im not actually too keen on physically rotating the screen as i find with a large rotated screen eg. 21" the screen is almost too tall, especially if you have a cab where your face is close to the screen.

On most candy cabs you sit very close to a 29" monitor, and that includes vertical games!  Some people seem to be fine with it, and others say it's a problem.  My cabs are going to be candy cab style with 27" TV's, but the control panel will be a little different to keep you sitting much further back.  I'll try and use tinted glass to keep brightness down too.

I know what you mean about being too close and looking up and down the screen, and I'm also worried about burning my eyes out.  I'm going to set up a makeshift draft of my cabs to try out the ergonomics for a few weeks before committing.

plus you dont have to keep rotating the monitor all day and manual degaussing (its not too hard to add a manual deguass button to any tv by the way, see here: http://www.ukvac.com/forum/plz-help-me-add-manual-degauss-button-to-circuit_topic328792.html

Yeah, I wouldn't want a constantly rotating CRT in a cab.  Thanks for the link though, I was actually thinking about that today.

..and also no need to own 2 cabs

For me 2 cabs is necessary to run vertical games in native res.  You could do native res vertical games on a horizontal monitor with MAME in 25kHz on a Tri-Sync monitor, but that wouldn't work for console games or PCB's, both of which I want to support.

mind you, the big downside of course as we all know... loss of lines, interlace, scaling etc

That's why I need separate horizontal vertical and cabs!

anyway i dont know, we'll see (im still in early stages of mame cabbing )

Me too, I've been tinkering for five years, and no progress on the physical cabinet yet!