Quantcast All you ever wanted to know about TBCs - digitalFAQ Forum
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10-14-2021, 11:00 AM
drzapp drzapp is offline
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Apparently, someone named Turkus at NYU did their master's thesis on TBCs, and it's very detailed. I couldn't find this mentioned in any other posts, and thought it was worthy of a sticky.

https://miap.hosting.nyu.edu/program...s_Thesis_y.pdf
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10-14-2021, 11:19 AM
RobustReviews RobustReviews is offline
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Looks like an interesting article, I have skimmed it but will have a read sometime.

Potentially a useful resource and nice to read something based on objective facts rather than subjective opinions.
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10-14-2021, 11:49 AM
msgohan msgohan is offline
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It's interesting, but doesn't touch on the consumer videocassette formats at all.

Quote:
Originally Posted by RobustReviews View Post
Potentially a useful resource and nice to read something based on objective facts rather than subjective opinions.
I read it before, and that's not how I would characterize it. From the conclusion:

"This paper has been an effort:
(1) to explain what time base correctors are,
(2) to provide a brief technological and historical background on these critical
components of the process of digitizing analog videotapes (which is essential to
preserve an important part of our cultural heritage), and
(3) to summarize a personal journey undertaken to learn some of the rudimentary skills required to
repair this aging equipment."
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  #4  
10-14-2021, 01:15 PM
latreche34 latreche34 is offline
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I just skimmed it too but it basically summarizes a TBC as a process not as a device, A process that corrects line timing errors, frame timing errors, chroma shift, luma gain, sync multiple cameras and so on and so forth, later on in the D1 era when digital started to take place in the studios digital frame synchronizers were used.

In the consumer arena those things are not meant to mess with and are optimized inside the machines for most of the tapes, First generation VCR's relied heavily on CRT TV's timing corrections that used analog line delays, later on when VHS editing became a thing for consumers we started to see VCR's with line and field TBC's and video mixing consoles with TBC's and an assortment of video corrections, So TBC for consumer gear could mean anything and was never defined without adding its function to its name.

https://www.youtube.com/user/latoak34/videos
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10-14-2021, 01:24 PM
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Quote:
Originally Posted by latreche34 View Post
I just skimmed it too but it basically summarizes a TBC as a process not as a device, A process that corrects line timing errors, frame timing errors, chroma shift, luma gain, sync multiple cameras and so on and so forth, later on in the D1 era when digital started to take place in the studios digital frame synchronizers were used.

In the consumer arena those things are not meant to mess with and are optimized inside the machines for most of the tapes, First generation VCR's relied heavily on CRT TV's timing corrections that used analog line delays, later on when VHS editing became a thing for consumers we started to see VCR's with line and field TBC's and video mixing consoles with TBC's and an assortment of video corrections, So TBC for consumer gear could mean anything and was never defined without adding its function to its name.
Indeed.

I'm never sure with the remarks made in various places about "professional TBCs are designed for clean sources" etc, I can't help thinking these people have never struggled with UMatic... I daresay a lot of 'modern' good quality VHS machines have far more signal stability and fewer timing issues than UMatic and I daresay early Betacam too.

Just an opinion, maybe one of the studio heads would like to chip in?
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  #6  
10-14-2021, 02:02 PM
drzapp drzapp is offline
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Ok, I can see I should have titled this "Everything you wanted to know about TBC theory" LoL
I'm a scientist, so I like theory, but I can understand most here are interested in more practical info.
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  #7  
10-14-2021, 02:13 PM
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Quote:
Originally Posted by RobustReviews View Post
objective facts rather than subjective opinions.
Pffft. No.

This is just a student, doing what students often do. They snatch information from varying places, to appease the footnote requirement. And then tend to somewhat twist up the facts a bit. This student, like most others, had no real-world experience to pull from. And no, playing with a broken rackmount unit doesn't count. It's very obvious that he didn't know what he didn't know.

Right now, much of it reads like multiple Wikipedia entries pasted together. It's very meandering and disjointed. In terms of being a thesis, it's crap. It doesn't really put forth a clear position, then back it. It mostly plods along, pooping out fact nuggets along the way. It takes him all the way until pg10 to get to the point (and it's better repeated in the last few sentences): TBCs are getting rarer, harder to find. (That's something I've been saying for years now.) We face a real problem in the future, unless this gear is repaired. Though he failed to connect that rarity is related to trashing/recycling units, rather than repair.

In terms of consumer analog videotape formats (VHS, etc), it's entirely useless.

It has some relevance to broadcast formats like U-matic, but only very partially, the info presented here would still not result in a quality playback or conversion.

While I hope the author has since learned far more about TBCs, most student thesis are one-off topics that they never revisit.

Quote:
Originally Posted by RobustReviews View Post
I'm never sure with the remarks made in various places about "professional TBCs are designed for clean sources" etc, I can't help thinking these people have never struggled with UMatic... I daresay a lot of 'modern' good quality VHS machines have far more signal stability and fewer timing issues than UMatic and I daresay early Betacam too.
"Cleaner" isn't the same as "clean".

It is very true that pro formats are vastly cleaner than consumer formats. Pro gear didn't have to compensate for the level of crappiness that you get from consumer formats like VHS. So TBCs (and other gear) had to be modified for consumer sources. This is both factual, and easily seen anecdotally. For example, it's why "pizza box" rackmount TBCs are fairly worthless for VHS tapes, something many people have seen first-hand in the past two decades of digital conversion. A DataVideo TBC-1000 may be equally useless for certain pro formats.

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