SVHS Resolution?

[davidian]

I asked a question before, and got the answer that VHS has a resolution at ~320x288. What is the resolution of SVHS then..? Just curious.

[Darkbird]

Vertical resolution is about 400 lines. Don't know about the apparent horizontal resolution.

[RemoteCtrl]

This is definitely a FAQ.

When someone talks about the number of _vertical_ lines, he means _horizontal_ resolution. It is rather obvious when you think about it.

Vertical lines do not really exist on a TV screen, they are used only as a measurement of resolution. However, horizontal lines do exist because that is how the image is drawn to the screen. Their number is fixed and equals to 625 in PAL and 525 in NTSC SDTV systems.

The actual image size is less, about 576/480 lines respectively. This is the maximum vertical resolution that gets digitized to a computer. Both VHS and S-VHS systems generate a few lines of noise to the bottom of the image, so those must be deducted to get the actual amount.

Horizontal resolution isn't as accurate, so it must be measured. A common result for an average VCR is about 240 vertical lines in VHS and 400 in S-VHS. However, this measurement is made assuming a square screen. The figure must be multiplied with the standard 4:3 aspect ratio to get the true resolution, which is about 320 pixels for VHS and 530 for S-VHS. Capture resolutions should be somewhat higher to make sure no detail is lost in (poor) scaling.

[davidian]

Ok, thanks for the answer!

[ironwood321]

From experience no matter what the file format resolution restrictions are you get a better capture if you capture in the highest possible resolution for your format and reduce down to you desired format. Sometimes the on board chip don't make a good job of reducing pixels.

I capture at either 720 x 576 or 768 x 576 and reduce down by Precise bilinear filters to my desired output format. You tend to reduce artefacts like Hanover bars a lot better this way and end up with a clear looking capture.

Also does someone know why the new range of capture cards from Hauppauge and ati only support a maximum resolution of 704 in PAL?