It’s not easy to view NTSC video input on a Windows box, but thanks to Ask MetaFilter I figured out how. Here’s what you need:

• Video capture hardware. I have a GeForce4 Ti4200 video card (from ASUS) which has a video-in/video-out (VIVO) box.
• S-Video source. The video card can take in composite or S-video input, but the colours in composite are so awful that it’s not worth the effort. S-Video isn’t too bad.
• A WDM driver for the video capture hardware.
• Software to display the video capture. I like ATV2000, but I’m still looking for alternatives.

Put it all together and your video is now showing on your screen, where you can watch it, record it, filter it, etc. Some tweaking improves quality. I found that it looked best if I ran the capture at 640x480 and my display at 1280x960@60Hz. That’s a nice even 2x size multiple and (almost) the same refresh rate as the source. Running at, say, 1024x768@85Hz introduced lots of ugly interlace-related shimmer.

It’s amazing how complicated this is. It’s a lot of data: I’m surprised my PC can record full motion video to hard drive. And the NTSC input is in an awful format. The interlacing is the worst of it, here’s a nice visual explanation. There’s a neat program called DScaler that tries to deinterlace the video before displaying. That gives a much sharper still picture but in regions of high motion you get awful judder. I gave up on it.

Progressive scan HDTV is the only rational thing.