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Discussion Starter · #1 ·
Thought somebody in this forum might be an expert at low definition as well as high definition recording.


Can the horizontal jitter that is so noticeable on consumer svhs vcrs be

satisfactorily ameliorated with the use of a TBC? If so, any thoughts on this one?

http://www.avtoolbox.com./avt-8710.htm


I currently use a crt projector, but may go bulb sometime. Do any or all of the new digital projectors have built- in TBCs?


Tom
 

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Not sure if its only the TBC. I've go a low end S-VHS vcr with TBC and I still get jitter. My JVC D-VHS vcr has absolutely no jitter when playing back analog tapes. So build quality may play an important part too.
 

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A TBC is designed to correct timing errors in the horizontal line timing that are created by minute inconsistencies of the servo motor. It works for that purpose. A VCR's timing is regulated by a motor which is not very accurate by TV standards. This timing error can best be seen on vertical lines in the picture that squiggle as the tape plays. Other timing errors such as vertical jumping are usually caused by other issues not related to the servo motor inconsistencies. A TBC can sumetimes correct these vertical sync errors as well if they are not too disruptive.

You use the term "horizontal jitter" I'm not sure I know exactly what you are referring to by this but there is a phenomena known as judder which I believe has to do with artifacts that can be caused by horizontal motion in the video that has field separation as the motion increases speed in the horizontal direction. Thjis can be caused by editing issues that was exacerbated by improper field order rendering in the edit process as well as 3-2 pull down in a film 24 frame to 29.97 fps conversion. A TBC will not fix this error.


Another device we use to fix some timing errors in bad video is a Frame Store synchronizer. This works much better in syncrronizing errors in the vertical sync than the TBC and sometimes we use this ahead of a TBC to do an initial correction so the TBC will lock on to the bad video. IT is all about windows of error correction and once the video is outside that window there is nothing that can be done with a TBC or FS.


Again, the squiggles in vertical line images that you see can and will most often be fixed with a TBC. But let me caution you about this. If the video is not recorded from a time base corrected source such as a camera original or broadcast signal but rather recorded as a straight dub from another VCR and you try a TBC on the second generation, it will not correct the time base errors from that first generation.


Some other rules of thumb to know. As a standard practice, TBC's built into VCR's are on the playback side and not used in the inbound record side.


Buying a TBC for consumer VCR use must be a full frame TBC and not a 2 line or 4 line field corrected TBC. Those are for use on professional VCR's only. A full frame TBC will delay the video from the audio by 1/30 of a second for each pass through the TBC.


mrwilson- The JVC has a built in TBC as do all DVHS VCR's.


Not all SVHS VCR's have the built in TBC. Most don't. At that price you mentioned in the link, Tom, I'd buy one and see if it does the job. You may also discover that it will remove Macrovision artifacts depending on it's design. :)


Hope this helps.
 

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Discussion Starter · #4 ·
Don & mrwilson


Thanks for the informative responses. My 'horz jitter' is the vert line

squiggle. Believe this term is sometimes used in the literature. Scan lines

are jittering in the horz direction because their timing is off. At any rate, telephone poles jittering, squiggling or wiggling can get old. I noticed this problem the very first time I saw a VHS VCR operate in 1976 and have been

bothered by it ever since.


My SVHS VCR is low end. Apparently the AVT unit is what I need if it performs as advertised. If I get one, I'll make a report. An upgrade to a DVHS VCR might make more sense, but it will be a while before I have anything digital to record.


Tom
 

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Tom. you might want to keep an eye on ebay. You can find some really good deals on TBC's. Look for Hotronics, Prime Image and Fora. They wont be as small and cute as the one you are looking at but probably better unit and often found for less money.


Bob H.
 

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Tom- Sounds like you would benefit from a full frame TBC, such as the one you posted the link to. If you decide to go the route suggested by Robert, just be careful you know what you are buying as not all TBC's are universal and many of the high end ones are specific to particular broadcast and professional VCR's with sync control capability. These do not work with SVHS consumer VCR's.
 

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Try upgrading to a JVC VCR with built in TBC. I believe mine is the lowest end one, the 4800, which was about $250 or less. Same price range as a standalone TBC and probably more useful (you can sell your other VCR).


-Tom
 
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