Should I use a custom resolution with a TV? (eg. 640x432?)

[sofakng]

I've read from various places that when you use a TV-out card (with a TV, obviously) that you should set the resolution to something like 640x432.  Is this true?  What is the benefit to doing that?

My arcade PC has an ATI RADEON 7500 (AGP) card and I'm thinking about installing the Omega drivers (www.omegadrivers.net) since they support custom resolutions, but I'm not sure what the point would be...

Can anybody explain this to me?

[ericball]

Normal NTSC is 525 lines at 29.97fps (59.94fps interlaced), PAL is 625 @ 25fps.  This includes vertical blanking; only around 480 lines NTSC | 576 line PAL are really useable (and some of those may be lost to overscan).  Some TVs are better than others in handling out of spec signals (too many or too few lines), but I suspect the TV-out on most graphics cards isn't capable of generating anything other than 525/625.  Therefore, I suspect what us being attempted is to reduce the number of active lines to eliminate any overscan problems.

Horizontal resolution is another issue entirely.  What is important is both the number of onscreen pixels and the total number of pixels per line (including horizontal blanking) or the dot-clock.  For reference DVDs use 720/858, which includes a fair amount of overscan and is about the limit for active versus blanking.

[Steamboat]

When using a tv-out (s-video) what should the resolution be for the best picture?  I've seen may different things and I am try to figure out what is best in most cases. 

If it matters I am using an ATI 9200se to a 27inch TV.  Some games are looking OK, but others are really not that good.

Thanks!

[hatrick]

I'm interested to hear the best setting too since I will be using an ATI 7200 with S-video to 27" TV. 

 

[ericball]

Typical TV out settings are 640x480 since that's the best match to NTSC.  However, some cards/systems don't seem to be able to go lower than 800x600.  Just be aware that anything above ~480 lines will have to be scaled down to <=480 for TV out.  Maximum horizontal resolution will depend on the output format.  Composite is ~320, S-Video is ~640, component could go much higher.

Digital TVs (LCD, Plasma, DLP) and HDTVs will be limited both but the connection type and the "native" resolution of the display.

[Lilwolf]

What I found (not all that much testing)..

most TV-out cards will scale to one resolution.  You should try and set it to exactly that much... otherwise your scaling in software... then scaling in hardware.

Mame does a GREAT job of HWScaling on most cards.  So setting the real resolution and hwstretching is pretty good.  Create an INI with forcing close as possible to native resolution and use hwstretching.

..then..

set mame to switch to closest resolution and see how it does.   This means that your ATI card will do all the stretching. 

You will probably see a difference.  If the resolution works with the card it should be the best (since both ways your video card is stretching and you know you have the right resolution).

I believe all video cards handle 640x480 btw... Its XP that doesn't show support (but can be enabled... heck, you can have your desktop at 320x240 if you want... but don't expect to be able to hit accept on the Display Properties window to get it back to a normal resolution.

[sofakng]

Ok, if I understand correctly then I should try to use 640x480 as much as possible since 800x600 is actually downscaled to ???x480.

However, when I use 640x480 or 800x600, it seems as though about 3/4 of an inch are cut off from the bottom of my screen.  Is this just a driver problem of some sort?  I'm using an ATI Radeon 7500 (AGP) in case you're wondering... (w/latest Catalyst drivers).

[jimboc]

I have a Radeon 7500 w/s-video out, with a good quality 20" s-video TV and have gone NUTS trying to get the display to my overall liking. I've finally found settings that have worked for me, and I found them to look quite good in composite as well as s-video.

Just FYI, I prefer jaggy crispness to blurry anti-aliasing.

MAME display tweaks:
I definitely like 800x600 for the best "all-around" resolution.. I find the downsampling/stretch pattern to be better than 640x480 or other weird custom resolutions.