I thought VHS, S-VHS, and DVD have about the same resolution

[Hypersonic1]

NTSC VHS and S-VHS have 486 lines (interlaced) and NTSC DVD has 480 lines (interlaced). What am I missing here?

[manono]

The horizontal 'resolution', for one. Resolution isn't defined only by the vertical.

[Hypersonic1]

It's part of the resolution. The other part of the resolution is commonly 720 for all three of them.

[Cornucopia]

You are quite wrong (about the 720 common to all), Hypersonic1...

+1 with manono.

Take it with a grain of salt, but the Wikipedia page about resolutions gives a good indicator of the differences:

Your list, in descending order of resolution:
DVD: 720x480 (or 704x480)
SVHS: ~530x480
NTSC: ~440x480
VHS: ~320x480

This is why capturing at/for DVD resolution can encompass all those (non-professional) analog formats: it's better than all of them.

Scott

[newpball]

VHS: ~320x480

And a dismal color resolution of about 40 lines.

[Cornucopia]

...More like 120-200, but yes, dismal.

Scott

[newpball]

By the way 320 lines for standard VHS is that not a bit too optimistic?

[Cornucopia]

No, that's about right: 300-360, but usually 320 or 330 seems to be the agreed determination (based on luminance bandwidth, kell factor, interlacing, comb filtering and a few lesser characteristics). BTW, the Wikipedia article on VHS/SVHS that cites "40 lines" for color doesn't take into account the fact that the chroma bandwidth starts at 3.58MHz but then is heterodyned for the "color-under" recording system (and then reversed on playback). This means it has more than a true 400kHz bandwidth would lead one to determine, but less than the true 3.58MHz (due to losses & comb filtering, etc).

VHS was poor but it was watchable, otherwise it wouldn't have been as popular as it was.

Scott

<edit>Here is a clip to demonstrate (showing luma+chroma equiv horizontal res comparison)...</edit>

[2Bdecided]

It doesn't really matter Hypersonic1, you're going to capture and work at 720x480 or 704x480 unless you've got a VERY good reason not to.

You can't get those six extra analogue lines into the consumer digital domain, so forget about them. They're junk on most consumer analogue recordings anyway.

It's true that VHS has a lower horizontal resolution, but even so, it doesn't make much sense to use a lower digital resolution. Just stick with the standard 720x480 unless you have a VERY good reason not to.


Capture a tape, and put it onto a DVD. Play back the original tape (directly: VCR connected straight to TV) and DVD on the same TV. Use an old CRT if you can, as well as a modern TV. Watch the video then the DVD on one TV, then watch the video then DVD on the other TV. Look out for noise, wobbling picture, straight lines, cropping, lost details in bright and dark areas, audio-video synchronisation problems (watch someone talking), macroblocking, mosquito noise, chroma shifts, etc. Make sure the DVD doesn't look or sound any worse than the tape on either TV.

When you can manage that, then come back and worry about doing a better job, if necessary.


Trying to get each individual stage perfect as you go along, without ever having got to the end of the job on a single tape, is a recipe for disaster.

Cheers,
David.

[jagabo]

40 lines for VHS chroma is about right:
https://forum.videohelp.com/threads/319420-Who-uses-a-DVD-recorder-as-a-line-TBC-and-wh...=1#post1981589

analysis based on the VHS images in this post:
https://forum.videohelp.com/threads/319420-Who-uses-a-DVD-recorder-as-a-line-TBC-and-wh...=1#post1980652