Are TBC (Time-Base Corrector) digital or analog?
 

Hail forum,

I'm looking at a really nice Betacam SP deck, it's a BVW-75. However, I'm concerned about the machine performing inconspicuous analog to digital conversion. I've had terrible experiences with devices that do this kind of thing (analog to digital, I've never used a deck with a built-in TBC before).

Would the BVW-75 likely have a digital TBC, or some other kinds of digital processing?

Maybe, since the BVW-75 doesn't (I assume) apply any digital compression to the video, would I even notice the digital conversion to begin with?

Thanks!

A "digital TBC" (software) does not exist.

All modern TBCs are "digital" because an analog signal is input, processed in a buffer (computer RAM), and an analog signal is output. It does not output digital data, because that's not it's function. It cannot output digital data, as it's not that simple. That's what capture is for (A>D).

Not all A>D is the same kind of A>D. I have a feeling your experience was with a crappy capture device, and not the A>D>A of a TBC.

This is a really good video on how a TBC works:

Kramer SP-11D spends the signal also in Digitally [SDI]
and also in FBAS / S. video and YUV

http://www.hdtvsupply.com/kr-sp11d.html

My Betacam SP has only SDI for picture.
Audio is by XLR.
My Betacam.... Digital -S with 4:2:2 is also separated audio in XLR
However, has not used these recorders for a long time any more.


Digitally also goes with the Snell & Wilcox NRS50
http://www.kitplus.com/FORSALE/Conve...s_/148464.html

Only analogously from goes with the AVT8710 and the TBC Enhancer of Electronic design [colour shift + and minus]
vertically and horizontally

So, if I were to use my (I just bought it!) BVW-70's TBC bypass switch, I shouldn't encounter much, if any, digital processing?

In practice, you won't notice any difference in video processed by a TBC outside of correcting the actual time-base errors. The unit's built into VTRs tend to be pretty transparent in operation. They do not "compress" video, it is stored in a buffer of roughly 4-6MB of RAM (for a full frame TBC). One nice feature the TBC in this VTR has is dropout compensation, so small tape defects will be automatically masked.

Most of the video artifacts you see here with high end TBC decks tend to come from the dynamic noise reduction systems the decks also have. If a deck like the BVW-70 has DNR, there will be a switch to disable it as well.

Would the video DNR be the same sort of thing as Dolby C?

Not the same. Dolby C requires the source material to be encoded in order for it to work. The DNR circuits in VTRs analyze video and remove what it believes to be artifacts/noise on the fly.