What is the actual capture size?

[Roginator]

Just how big an area can TV cards capture? My old STB card can be forced to a custom setting of 720x480 in VirtualDub, but it appears it is only being stretched in the horizontal direction compared to 640x480 (apparently the maximum possible).

The Capture Card list claims it can do 720x480.

How about the ATi All-in-Wonder Pro 128? I'm about to start tinkering with that and would like to know if it can REALLY show more picture area at settings greater than 640x480.

[tacosalad]

The 740 capture probably looks stretched because you've exceeded the bandwidth of the video signal itself. A typical video signal has a bandwidth of only 6 MHz (more or less) which is adequate for about 300 distinct pixels. Hence the common term of 300 lines of video resolution.

That doesn't mean there's no point in capturing above 300 pixels per line--if nothing else it gives you a more precise sampling of the signal. But as you raise the capturing resolution, you don't get as many distinctly separate pixels, so the image just looks more and more stretched.