Quantcast Frame-based and line-based TBC - digitalFAQ Forum
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04-15-2016, 01:55 PM
three_jeeps three_jeeps is offline
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I am assembling some gear for video tape transfer and repair and need some clarification wrt TBC. I have a DataVideo TBC-1000 and my understanding is that it does frame-based correction only (True?)

How do I know if I need to use line-based correction? and what are some good units to consider getting?

Comments much appreciated

J
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04-15-2016, 04:52 PM
sanlyn sanlyn is offline
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External line tbc's are found as expensive shop units that require ancillary equipment. And $$$. Usually you get a hlgh-end SVHS VCR with a line tbc built-in. Those aren't cheap, either, and a real trek finding one that hasn't been used to death. The other way to get line tbc activity for $100 or often less is to use an older DVD recorder that can be used as a pass-thru unit. You don't record to a pass-thru -- connect the VCR to the DVDR input, then connect the DVDR output to the rest of the capture chain. You don't record the video, you "play thru" the device. A line tbc has to run in circuit before the signal gets to a frame tbc. Few DVDR's can be used for pass-thru, and most that can will not perform well. The favored models are the Panasonic DMR-ES10 and DMR-ES15.

A common but rather mild example of line "wiggles" produced by typical scanline errors without a line tbc is here: http://forum.videohelp.com/threads/3...=1#post1882662. The "fixed" version shown used a DMR-ES15 for line tbc pass-thru.

More severe examples were posted in several threads here. Below are links to 2 samples of scanline errors. The tape was played with a non-tbc VCR. While the bad demo looks like a severe case, it's not as uncommon as you'd think an often appears as less severe but similar and obvious. This sort of top-border flagging and frame slippage happens often with old tapes. Some tapes will play without this severity, some won't. All VCRs without a line tbc will have scanline errors.

- A1_Sample2_bad.mpg is the original capture encoded to MPEG, with frame size slightly reduced to prevent TV overscan from hiding some of the problems.
http://www.digitalfaq.com/forum/atta...sample2_badmpg

- B1_Sample2_fix.mpg is the tape played with a line tbc pass-thru device.
The "fixed" sample linked is a first-stage test repair with only basic denoising, improved afterwards with a better VCR but here addressing only specific issues. The tape is no longer available.
http://www.digitalfaq.com/forum/atta...sample2_fixmpg

The sample links were last posted in digitalfaq 2 weeks ago.

More: http://forum.videohelp.com/threads/3...hat-do-you-use
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04-24-2016, 11:36 PM
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lordsmurf lordsmurf is offline
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Quote:
Originally Posted by three_jeeps View Post
I am assembling some gear for video tape transfer and repair and need some clarification wrt TBC. I have a DataVideo TBC-1000 and my understanding is that it does frame-based correction only (True?)
How do I know if I need to use line-based correction? and what are some good units to consider getting?
Comments much appreciated
1. Frame sync TBC = cleans the signal, not the image/visual; example: TBC-1000. TBC-100/1000 is full-frame, process 1 frame at a time

2. Line TBC = cleans the image, not the signal; example: built into JVC/Panasoinc S-VHS VCRs. JVC cleans 1 line at a time (100s per frame), and Panasonic is full-field ("multi-line", still 100s per frame)

3. Frame sync = found in some DVD recorders, not true TBC, special image cleaning properties; example: Panasonic ES10

You need both.
line = clean image
external frame = clean signal

See also:
- VCR Buying Guide (S-VHS, D-VHS, Professional) for restoring video
- What is a TBC? Time Base Correction for Videotapes

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
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