What is a TBC? Time Base Correction for Videotapes

[latreche34]

I'm aware that this thread is few months old, but since I have a question about TBC I didn't want to create a new thread for it.
Since full frame TBC's digitize the analog video and convert it back to analog after fixing it, Do they make TBC's that skip the last step and send digitized frames to the computer? Is there any noticeable loss of quality from going from A to D and then D to A inside the TBC and then from A to D in the capture card ?

[msgohan]

Yes, they do. Every broadcast-level TBC that has SDI output, for example.

"Noticeable" is subjective, and the quality loss will depend on how good the DAC of the TBC is, how good the ADC of your capture card is, and your ability to configure it to minimize losses.

[latreche34]

I have the VMC-1 except from being a DV device it does not convert back to analog only in a stand alone TBC configuration - see attached picture - So basically it takes the analog video applies the AGC and converts to digital at 10bit and then applies the full frame sync//TBC//3D Y/C processing and route the digital signal to the DV encoder, The same digital signal goes to a D/A 10bit chip and out to analog output needed if used as a stand alone TBC.
Why they don't make such device with MPEG2-4 instead of DV for non studio use?

VMC-1 Top Diagram.jpg

[msgohan]

Quote:

Originally Posted by latreche34

Why they don't make such device with MPEG2-4 instead of DV for non studio use?

They did, in Japan. (But for MPEG-4 only Simple Profile, not AVC.) Doesn't help those of you with PAL sources...

You were asking about TBCs before, not encoding devices.

[latreche34]

Yes, the two questions are related, Can a TBC be a digital converter? sort of a question.
What is the name of the Japanese device?

[msgohan]

Oh, these two specific cards do support PAL.

http://www.expandore.com/product/edi.../MVRD2200V.htm
http://www.expandore.com/product/edi...s/MVRD4400.htm ("Developer" board: no software to make it work)

[latreche34]

Quote:

Originally Posted by msgohan

Oh, these two specific cards do support PAL.

http://www.expandore.com/product/edi.../MVRD2200V.htm
http://www.expandore.com/product/edi...s/MVRD4400.htm ("Developer" board: no software to make it work)

Thanks for the links, I don't have any means to use PCI cards, Do they output 4:2:2 losseless though?

[msgohan]

First you want MPEG-2/4 and then you want 4:2:2...

They aren't intended to.

[latreche34]

Is there a limit on how many questions you ask in the forum?

[hot_denim]

It is mentioned that the Cypress CTB-100 has a defective chipset?

What symptoms of the defective chip would there be (what will I see on the screen)?

How do I compare a Good unit with a Defective unit?

[lordsmurf]

Quote:

Originally Posted by latreche34

Is there a limit on how many questions you ask in the forum?

Yes. You may only post 65535 questions before the site self destructs! But seriously, no, no limit.
In 10+ years, nobody has ever asked that.

Quote:

Originally Posted by hot_denim

It is mentioned that the Cypress CTB-100 has a defective chipset?
What symptoms of the defective chip would there be (what will I see on the screen)?
How do I compare a Good unit with a Defective unit?

See: http://www.digitalfaq.com/forum/vcr-...-8710-doa.html

[Master Tape]

Without the use of a TBC, will a capture card freeze up trying to capture static VHS noise? (Usually on the part of a tape that has been recorded over) If so would the ES-10 capture everything on screen, without losing frames?

[lordsmurf]

Quote:

Originally Posted by Master Tape

Without the use of a TBC, will a capture card freeze up trying to capture static VHS noise? (Usually on the part of a tape that has been recorded over)

Often, yes.

Quote:

If so would the ES-10 capture everything on screen, without losing frames?

Not necessarily, no.
The DMR-ES10 is not a TBC.
It has some TBC-like abilities, which should only be used when certain conditions exist (tearing, unstable visual timing, etc).

FYI: If you need a TBC, I have a TBC-1000 available. PM me.

[Master Tape]

Quote:

Originally Posted by lordsmurf

Often, yes.

Not necessarily, no.
The DMR-ES10 is not a TBC.
It has some TBC-like abilities, which should only be used when certain conditions exist (tearing, unstable visual timing, etc).

FYI: If you need a TBC, I have a TBC-1000 available. PM me.

Thanks. I may do in future, but don't need it at the moment. Still to buy/build a capturing rig, and get my main pc up and running that i built (after much trial and error!)

Ah crumbs, i bought the ES10 a little while back, thinking i got a really good TBC for a cheap price.. knew it was too good to be true But it has it's uses.

[sanlyn]

There are varying degrees of tbc power and action. The ES10 has a powerful line-tbc function, and somehwat nominal frame sync function. A "true" frame-level external tbc has more powerful frame sync as well as signal timing cleanup that defeats Macrovision. The ES10 won't defeat copy protection but it does have an effective line tbc -- and you'd better disable its input line DNR, which causes ghosting and excessive posterizing. You need the Panasonic's remote to do that. You should know the difference between the two types of tbc, both of which are needed for analog tape capture. Don't even think about capturing analog tape without a line tbc of some kind, either builtin to the VCR or as pass-thru with your ES10.

[Master Tape]

Quote:

Originally Posted by sanlyn

There are varying degrees of tbc power and action. The ES10 has a powerful line-tbc function, and somehwat nominal frame sync function. A "true" frame-level external tbc has more powerful frame sync as well as signal timing cleanup that defeats Macrovision. The ES10 won't defeat copy protection but it does have an effective line tbc -- and you'd better disable its input line DNR, which causes ghosting and excessive posterizing. You need the Panasonic's remote to do that. You should know the difference between the two types of tbc, both of which are needed for analog tape capture. Don't even think about capturing analog tape without a line tbc of some kind, either builtin to the VCR or as pass-thru with your ES10.

Here was interesting post on another thread over from the videohelp forum.

Quote:

It handles record drops just fine. You can throw anything at it, even fast forward/rewind a tape while capturing and it won't cause any trouble.

Anything about bad picture quality refers to it's MPEG2 encoder, which only applies when you are using it to record directly to DVD. But of course we don't do that, just use it in passthrough between VCR and capture device.

That was what convinced to buy one really. But not having full frame tbc functionality, this is false information surely?

And then there's the issue of posterization. I think i'll only use it for tearing, or for some dodgy tapes recorded in LP mode, as they are more prone to shaking/jittering.

[sanlyn]

You can avoid problems by turning off the ES10's input and playback DNR. This aggressive noise reduction is common with many components, including VCR's with heavy-duty builtin DNR like JVC and Panasonic players, as well as many TV sets. The noise reduction in these components is primitive compared to shop-grade units and to denoising in software with something like Avisynth. Also, bear in mind that the frame syc function in DVD recorders is there to help ensure a/v sync and frame rates, not to defeat copy protection, so these pass-thru units do have some level of frame sync.

Analog tapes are noisy crummy awful dirty source signals to begin with. Clever denoising in post processing is used to defeat it, and this itself can cause posterization and hard gradient edges. There are plenty of filtering techniques that avoid or fix it, especially with anime. Complaints about posterizing usually rise from users who don't know what they're doing, or who expect a perfect capture and final output with Step #1 of their projects and are too lazy to realize that analog sources are lousy and require some cleanup work. Their wok is often characterized by no cleanup at all, or by overkill such as over filtering, over sharpening, illegal video levels, and other boo-boo's resulting from sloppy work done in a rush.

[Master Tape]

I read from others that the ES10 can still have some posterization, even with the DNR turned off? Those users must have their VCR's DNR turned on then. Though i do have a Panasonic NV-HS860, where you can turn it off, but still have the TBC on, which is nice.

[lordsmurf]

Quote:

Originally Posted by sanlyn

Also, bear in mind that the frame syc function in DVD recorders is there to help ensure a/v sync and frame rates, not to defeat copy protection, so these pass-thru units do have some level of frame sync.

Also bear this in mind: "Copy protection" is nothing more than artificially injected errors into the video signal. Then video equipment is trained to either listen to, or ignore correction of, those types of errors. And there are many types of copy protection. What this means is that actual video errors can trip up "copy protection", even when no such protection exists.

At its most basic, frames syncs hold a frame until the next frame is fed to it. So yes, I'm sure it does have this minimal ability. But frames syncs can do more, which all DVD recorders lack. Note that "frame sync" isn't TBC, but TBC can be frame sync (but not necessarily). For example, the DataVideo TBC-100/1000/3000/4000 are true frame sync TBC.

Note to all: I have some extra TBCs that I'm parting with. PM if interested.

Quote:

Analog tapes are noisy crummy awful dirty source signals to begin with.

Not just visually, but signal-wise, too!

Quote:

Originally Posted by Master Tape

I read from others that the ES10 can still have some posterization, even with the DNR turned off? Those users must have their VCR's DNR turned on then.

I'm one of those users ... so no.

I'd know better.

[sanlyn]

I agree with lordsmurf. The frame sync "TBC" in pas-thru units are OK for helping to stop dropped frames and bad audio sync, but as lordsmurf says there are other signal problems that require a "rel" TBC like man AVT-8710 or TBC 100/1000/*. One example is a project I've spent sometime on, a VHS recorded on cheap tape at 6-hour speed with a abd cable signal and a really cheap VCR.

I recorded this msyelkf off a really crummy cable signal, so you'd expect to copy protection problems. Right? Wrong. This home tape was obviously not Macrovision, but playing it with a non-tbc VCR I used the ES10 as a line-tbc pass-thru. I was getting good frame rate and a/v sync, no sync problems, no dropped frames, etc. But I was getting the kind of top-border flashing that looked like Macrovision. Clue: the signal had so much imbedded noise that the capture chain was picking up false-positives that looked like Macrovision. Fix: I used the ES10 for line-tbc and the AVT-8710 for signal-cleaning tbc. So I couldn't take the cheap lazy way out and had to use both the pass-thru and the full frame-sync tbc. I then tried that same tape with an AG-1980 and it's builtin line tbc but no AVT -- result: I still got false Macrovision detection.

Moral: sooner or later, whether you use a VCR with line tbc or a pass-thru line tbc, you're going to need a full-fledged external frame-level TBC. People are always trying to beat City Hall on this. Sometimes they succeed, but many times they don't. People have known this for a very long time, but you still have outlaws who try to trick the system. Pros and experienced users don't just hook up stuff because it looks cool. Every piece has its function.