VGA to NTSC line-for-line ?

It's actually 486 displayed lines (of 525 lines in total), although some of those may be not actually be visible (esp. for CRTs).

The main issue is that NTSC is interlaced, VGA isn't. So VGA will have roughly twice the horizontal frequency of NTSC (e.g. 31.46875 kHz for

A simple converter would digitise and store every other input line, then display it at half speed. This doesn't actually eliminate lines; you would use the even lines from one frame and the odd lines from the next, so each line appears in one of the two fields.

OTOH, most PC video hardware is capable of generating NTSC timings directly. The driver probably won't allow it if the card doesn't include a "video-out" (composite, S-Video, etc) connector, as VGA monitors typically can't handle it.

Oh wow, that is a problem that's more complicated than it first appears. Since there are no "pixels" as such in NTSC, the idea of a per-pixel mapping in a LCD is ambiguous. Even the lines themselves have no real meaning unless the LCD is exactly 525 lines (give or take). The best you can do is make the text large enough to be legible. For example, in the '80s, home computers used TVs as their displays. None of them had 80 columns on a TV though. The computers with 80 columns either used monochrome monitors with NTSC-like syncs but no color information in the video, or had dedicated RGBI/CGA-style graphics. (I don't include "80 column" software display modes with tiny 4 pixel wide fonts on s-video monitors, but that's one way of doing it) If you look at the fonts used back then, a low-res computer like a VIC-20 used single pixel wide text and it was legible on TVs. However, machines like the C64 with 320 pixels horizontally had to use fonts with lines two pixels wide. You'll have to try the same idea. Now modern TVs, even CRT-based TV from less than 10 years ago, use all kinds of processing to improve the video. Lots of sharpening and DSP magic lets my clunky old 27 inch Wega display re-scaled 800x600 (from my PC) almost as clearly as 800x600 on a monitor. But this won't happen with a small LCD or less-evolved tube TV.

Now as the other poster mentioned, since VGA is progressive, you'll lose pixels in time. No way around that. Unless you're scrolling fine text, it shouldn't be a problem.

Maybe your problem could be solved easier with a LCD display with a dedicated input with true per-pixel graphics. But that's a whole 'nother kettle of fish.

snipped-for-privacy@netzero.com wrote

I am quite happy to lose lines to make this work 1:1 in the vertical direction.

Certainly I am not going to be building anything, because for a start the line frequencies are different. This job needs a proper frame buffer - just like the $50 boxes which are all over Ebay. They are all seemingly based on the same chip - in the same way that all the RGB to USB converters use a particular chip made by Philips (which has 3

I just wondered if any of these VGA-NTSC converters have the capability to do a vertically-direct pixel translation. This should be easy.

I have an old box from avermedia (an averkey imicro, KOC3) that converts VGA, SVGA, and XGA to NTSC. I can't vouch for line for line, but it works.

I was wondering about that - apparently NTSC is good for 486 lines displayed, so should cover 640x480 VGA.

Cheers! Rich

set your VGA to run at the NTSC frame rate, and then use an RGB to NTSC converter, or get a VGA with a composite output.

Peter, I am curious as to why they made the LCD to use NTSC input? What were they thinking?

What did they intend it to be connected to? Have you tried feeding Composite NTSC from an old VCR into it? Does it just throw away the parts of the NTSC signal it doesn't use?

Are these LCD's available cheap on some surplus market? Got a lead?