Too much TBC?

[SyncroScales]

I was wondering if a person can have too much TBC? Using something that has frame level TBC like the AVT-8710 or TBC-1000 and using it with line level TBC VCR's (http://www.tgrantphoto.com/sales/index.php/categories/professional-vcrs or the Hauppauge Colossus.

Will anything happen or are there problems associated with doing that?

[pandy]

? Don't understand question - how TBC can be too much? this simple solution where incoming data are aligned based on position for rising (falling) edge of H Sync pulse.

[SyncroScales]

I am unsure if frame level and line level could interfere with each other, or produce some problems.

So if they don't and both can be used, ok.

Does the picture look better with both?

[usually_quiet]

Line TBCs and full-frame TBCs correct different problems. A line TBC fixes some problems with the picture. A full-frame TBC corrects some problems with the signal. Then there is a DVD recorder's "TBC", which may be a frame synchronizer, used specifically to correct tearing or flagging which neither a line TBC nor a full-frame TBC can correct. See http://www.digitalfaq.com/forum/video-restore/2251-tbc-time-base.html

Both types of TBCs can be used, but often only a line TBC is needed. You shouldn't use more equipment than necessary, because each device you add has some detrimental effects as well as positive effects. Also, the picture needs to be corrected first, then the signal, so if using both, the signal needs to be passed through the full-frame TBC last. This means using a full-frame TBC won't be useful with the Hauppauge Colossus, because the Colossus's encoder has a built-in line TBC, but a DVD recorder used as a pass-though might still be helpful if it is needed to correct tearing.

Join at DigitalFAQ if you need technical advice on this kind of equipment. The site is run by some people who restore video for a living.

[orsetto]

Short answer: technically (on paper) the two types of TBC (three if you include a pass-thru device such as a DVD recorder) should be usable at the same time and not cause problems. Practically, in the real world, using more than one at the same can and does cause small or big problems. To a large extent, how well or how badly the several TBCs work together depends on your specific videotapes and your particular encoding device. But as a general rule, consumer-level TBCs all degrade the image somewhat. The line TBC in a VCR will remove noise and geometric distortion, but also soften the overall picture. A traditional external TBC like DataVideo TBC-1000 or AVT-8710 will stabilize "invisible" signal problems like frame dropping, etc, but again will also noticeably soften the picture. So connecting a line TBC + frame TBC in series can potentially compound softening artifacts into an unacceptable final image quality.

Contributors to the DigitalFAQ site are of two polarized mindsets on using multiple TBCs, so I don't think you'll get much enlightenment pursuing this question there. The answer is subjective, and you would be stunned how many "experts" think video that looks like it was shot thru vaseline is "amazing pro quality". Like many questions in life, you may need to work this out on your own: mix and match your hardware, then see what YOU think of the results. There isn't a universally "right" answer: some of the samples presented here on VH that get praised to the skies strike me as unwatchable, and vice versa. I personally tend to follow usually_quiet's maxim of "don't use more equipment than absolutely necessary" - if the line TBC in your Hauppauge seems to be competent on its own, don't add the AVT-8710 unless you experience the specific problems the AVT is designed to cure (frame dropping, loss of sync). Note the AVT has developed a reputation for being a peculiar design that sometimes fixes one problem while causing others: scrutinize your results with extra care to be sure all is well after using an AVT-8710. This also applies with the DataVideo, although the DataVideo is easier to troubleshoot: it either works or it doesn't. The AVT has tendency to half-work which can make it harder to evaluate results.

[usually_quiet]

I shouldn't have said a full-frame TBC won't be useful with the Hauppauge Colossus. It might actually be necessary to use one with some tapes to get a signal that is stable enough to capture, however the Colossus line TBC probably won't be able to correct the picture in that case.

[SyncroScales]

This is what I need to know.

I'll take the advice, do my tests and figure it out. But I want to know about some of the issues because there is no reason to reproduce the same problems people have had for years. Or waste money and time for no reason.

I don't want to over process anything or wreck something by trying to "fix" it too much.

When using the professional equipment compared to non-professional equipment, is it a different situation? Or are they dealing with the same things?