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sadkkf
07-03-2009, 10:12 AM
Hey--

I'm trying to make some DVDs from old VHS tapes, but see some tracking errors in the video monitor in VT, but it looks fine on my TV. I can adjust the tracking on the VCR, but it does nothing.

I've also tried adjusting the Horizontal Tracking Loop Frequency in the Proc Amp, but it generally makes it worse by dropping frames like mad.

Any ideas?

:sadkkf

ScorpioProd
07-03-2009, 04:09 PM
If you mean you're getting a skewing on top, change your capture from main to program. That enables the VT's TBC, capturing main does not.

That may fix your problem. If not, I would recommend a high-end consumer JVC S-VHS deck which has a TBC built-in. Or any TBC in-line before the VT for that matter.

Scott Bates
07-04-2009, 08:33 AM
Exactly why I still have a TBC-IV in an Amiga 2500 in my "capture path" (and a spare on the shelf), indespensable for all the VHS/8mm tapes that customers still bring me.

sadkkf
07-05-2009, 09:51 AM
If you mean you're getting a skewing on top, change your capture from main to program. That enables the VT's TBC, capturing main does not.

That may fix your problem. If not, I would recommend a high-end consumer JVC S-VHS deck which has a TBC built-in. Or any TBC in-line before the VT for that matter.

Hm...If you mean changing the Input on the Capture panel from Main In to Program Out, there's no change. Looks like it's time to upgrade my VCR.

Thanks!

:kevin

sadkkf
07-05-2009, 02:22 PM
Well, I've got a workaround...just using my video camera as a pass-through. Not ideal, but it works.

So what's this all about? What's causing this and what exactly is TBC?

ScorpioProd
07-05-2009, 04:28 PM
Ah, using your video camera to convert to DV you mean? Yeah, the camera's pass-thru may clean it up, probably has a sort of TBC in it.

A TBC is what we all needed to do all of this before video became digital. :)

A Time Base Corrector does what the name implies, fixes timing problems with analog video. In the analog world, those hundreds of lines of resolution drawing across the old CRT are never actually the EXACT same length. That makes analog video decrease in quality very quickly across generations without a TBC. Just think of what would happen if every line was getting more and more offset from the others in each generation.

This can also make picture data start to bleed into sync areas, and such. TBCs also remove all the sync signals and regenerate them cleanly.

They were also the only way to genlock multiple video sources together. Genlock as in match their timing so that you can switch them without a glitch in the switch.

With the Amiga Video Toaster you needed a TBC card for EVERY input going into it for genlocking multiple sources. Each TBC card at the time was about half the price of a Toaster, so they added up quick.

Nowadays, it's pretty cheap to put in a TBC (or similar) in most devices. But the VT card was designed a while ago, and it does a TBC in software, but in my experience, it can't fix as many problems as a real TBC (even compared to a cheap one in a consumer deck).

fboulene
07-06-2009, 12:16 AM
Wrong post

sadkkf
07-07-2009, 08:30 AM
Thanks, Eugene. Great explanation!

I really look forward to the day when we can all stop using tape. :)