Do Signal Boosters Improve VHS Picture Quality?

[Teshia]

See this shot I grabbed from my capture card?

http://www.interzone23.com/fun/badvideo.jpg

It looks like crap. The top of the picture bends off to the left and the colours get all out of whack along the top. These are from VHS tapes from the mid-80s of sci-fi shows off television - this is NOT Macrovision related.

When I play from VCR to TV, the picture looks stable. Old, but stable. When I play from VCR to capture card, it looks like this, like it was copied down another generation or two onto another tape.

So I hear about these gadgets. Radio Shack sells 'em, so do lots of other places:

http://www.globalsemi.com/cat99/videoaccess121.html

But do they work? I know they improve signal quality in cable channels, but what about if I'm capturing through the coax port? I have my VCR's coax out hooked up to my capture card's coax in and it thinks it's capturing channel 3, but it's just output from the VCR, which is great. Would these signal boosters improve the picture quality so that it looked as good as when the VCR is playing to TV?

Before anybody mentions Time Base Correction, stop. I know. I don't want to pay $300 or more to improve the picture. I just want it to look as good as it does when it's playing from VCR to TV.

Any ideas if these coax signal boosters are worth their salt at all?

[BJ_M]

no -- they will not help your case at all

[Teshia]

Okay, now the big question...why?

Do these signal boosters just boost cable channels? Do they consider VHS output a separate thing and not touch it?

[offline]

Why? Because they enhance the video signal as is without
color correction.

What you are looking for is: http://www.simacorp.com/scc.html

or use the color correction settings in tmpgenc, Virtual Dub. or
through avisynth filters.

None of the above will get rid of that top line btw - > that is
just overscan info (not meant to be displayed on TV)
and can be blacked out with a thin border when encoding to mpeg.

[Teshia]

Well, it's actually skewing, even if it's in the tv overscan area. Skewing (or flagging) is a bending of picture at top or bottom of television screen caused by the changing of the video track angles on the tape from the time of recording to the time of playback. This occurs as a result of poor tension regulation by the VCR or by ambient conditions which affect the tape. TV's compensate for this but VCRs can't, so they need Time Base Correctors to help them out.

http://www.sparkysworld.co.uk/tbc.htm

I'm not actually looking to improve the colour so much, just get rid of skewing along the top and black barring it is not an option for me. What I need to know is why these coax signal boosters don't boost the video signal as well as the cable signal.

[vhelp]

teshia,


In reference to your scanline/MV issues:
I have a theory of my own. (my two cents worth)

TV was never revised (afaik) to compinsate for macrovision**
But, VCRs were! If memory serves me, they changed the way VCR operate
to COMPENSATE for the new Copyright or MV that are NOW are VHS tapes
(incl DVDs) TVs aren't affected by MV (and YOUR old 1980's tapes play)
because it does NOT have this MV circuitry or what-have-you. So,
when you play your old tapes and watch them on your TV, or even commercial/
store bought movies (which have MV on those [not your 1980's recorded ones])
you wont see any issues. In fact, quality will be at it's best!
BUT, when you try:
* record to another vcr, or
* capture from a VCR (or dvd for that matter)

There is where the issue is (and hence, your problem, even though you don't
have any MV on YOUR tapes) Because these VCRs are designed w/ MV'enization,
when you play your non-MV tapes through your capture card, your quality goes
down, all because those VCRs are DESIGNED to "flaw" your tapes.
IMO, those wavy video output that you see (as I see them on mine too) via
your capture card (and not your TV) is mostly MV messing w/ the signal as a
standard practice - again, in the name of MV. Even though you tapes have
NO MV on them, your VCRs are operating as though it has, even if it senses
that it HAS NOT any traces of MV.
IMO, Here is where we all went to sleep, and only some of us are waiking up
to this realization of MV'enization...
Before MV, there was VCRs and TVs. They play beautiful music together.
around 1992 (give or take) they revised the VCR standards to omit a jamming
feature (hence your: color; wavy; bared issues) It became the norm. But, we,
as users weren't really effected by this (just yet) - - till we started
noticing quality issues when we capture from VCRs. Actually, some people
here even, don't realize it still. I notice it very so.
I believe that there is NOTHING you or I can do w/ this issue (MV) unless
we use a device DESIGNED to delete it or kill it or stop it (call it what you
want) - these devices being TRUE MV removers, or TBC. I'm not sure how a TBC
will really work, that is, if it REALLY works! ...and works, I mean, as you
SEE the FULL quality on your TV, then, when you (capture and encode) it, you
SHOULD see THE SAME level of quality, W/OUT the Fuzzy, and Wavy and Color
and anything else I missed here, issues. It should be JUST like you see it
on your TV, except that you have captured it and encoded it. Now, when you
play back the encoded clip, THAT clip SHOULD look THE SAME as the TV view when
play directly to TV (vcr to tv)

I hope that by now, you all understand a little more clearly what has happed
in the last 10 or so years w/ VCR (VHS) quality. There are NO ISSUES when you
play a tape from your VCR to your TV. It's when you take that source, and route
it to another recepter, ie capture card, or another vcr etc. There is where
the issue begins (MV that is) EVEN THOUGH/IF YOUR VHS TAPE(S) HAVE NO MV ON
THEM. it just doesn't matter any more! You will suffer the same symtom just
because its a tape and you are focusing/routing the signal elsewhere, rather
than a TV's input.

I too suffer from this issue and then some, w/ my store bought movies that I
purposely buy for this hobby of mine. I buy them for $5 and transfer them to
CD and play. However, I know that the quality can be improved if it weren't
for MV on ALL vcrs of today.
I've learned some tricks to minimize such, but they still leave plenty of room
for improvements.
Example of some would be:
* Filtering. Learning filtering techniques will definately help, but in the
name of TIME - and plenty of it!
* devices, ie color correctors, or video stablizers etc. (be warey of these)
* and last, TBCs. I've not had the pleasure of working w/ these items just
yet. I'm searching for an inexpansive one, IF I CAN FIND ONE for under $200
Anyone knows of any, please let me (us) know, tanx.

My recommendation, at this point, is to buy the DC10+ card. This card isn't
affected by MV (to some degree) there still is the issue w/ the videos
stability (as w/ ANY capture card) However, I DID/HAVE found a way to make the
video as stable as you would see it on your TV set. But, the downside is, MV
is al over the place, ie color bards, lines, etc. but the picture looks like
you were watching it directly from vcr-to-tv. This is what I'm after, in my
VHS-to-CD (CVD) projects (my hobby) ...but this idea still needs further
testing, and at the moment, I'm working on it. If I can get rid of the MV
or color bars showing up when I capture it, I think I'l have as close as I can
w/ my VHS-to-CD (CVD) 's. But for now, none of MY boxes removes these
blastid MV lines.
...well, till next time.

Thank your for your attention to this matter.
Try and have a nice day. he, he...
-vhelp

[snowmoon]

Although I despize MV as much as the next person on this forum, it does not appear to be what is affecthing the person who posted the question.

I doubt that MV processing is affecting this signal in any ways because the problem s could more easly be explained through tape wear, poor input source, and possibly a dirty VCR.

TBC units would help, but cost alot of money. I have not seen a TBC tools for vdub yet, althoug that would be NICE.

[Tbear]

Those are RF amplifiers they just boost the Radio Frequency not the info on them. They are best if you want to run several TV's off one VCR. What you need is a Time Base Corector. JVC makes VCR with them built in.

[sterno]

Signal boosters improve cable TV quality mostly because the cable jacks in most houses and apartments are wired the "lazy" way: outside line to first jack, cheap splitter with one line to the wall jack and one to the next jack which has another cheap splitter, etc. Splitters (especially the cheaper ones) really reduce the signal strength.

Putting a signal booster on a VCR connection is sort of like taking an old cassette or record that's been played a few too many times and turning the volume up to improve the quality.

[Teshia]

So you're implying that is DOES affect the output of the VCR to the capture card if a coax signal booster sits in between them? If so, what exactly gets boosted? Will I not see the annoying skewing/flagging effect at the top of the screen?

[MikeV]

Teshia,
You should be able to capture from the RF out (ch 3 or 4) to your capture card. If you have to use the RF output make sure you use at least RG-6 cable and go directly from the VCR RF out to the capture card RF input and try not to have a long run. A better way is to use the SVHS or composite out to your capture card. Then you could use the SIMA SCC Color Corrector (I use one) to tweak in your video for the best picture possible.

[sterno]

So you're implying that is DOES affect the output of the VCR to the capture card if a coax signal booster sits in between them?

Yes, it will affect the signal coming from the VCR. But you won't see any change in the picture because your problems are in the source material. Most signal boosters just increase the signal strength, but in the few feet of cable you'll have going directly from a VCR to a capture card the loss should be negligible. It's possible, though unlikely, that you might even lose a little quality because the signal's going through an extra round of processing.

Your problems are not related to that. I was trying to explain why a signal booster will help cable TV and not a VCR connection. The cable source is generally clean, but it's weak because of bad wiring. If your source material is bad, a signal booster will just result in a stronger signal carrying a bad picture. If you have a scratchy record, turning the volume up on your player makes the static louder right along with the music. There is no $10 magic bullet that will fix a bad source tape.

[Dragonsf]

My DataVideo amplifier both boosts the Video-Signal (color signal restauration) and eliminates the MV signal.Nevertheless the top lines of my captured video is skewed anyway.This doesn't effect the reslut (SVCD) in any way, it plays perfectly on my TV (thru standalone DVD player).TBC only solves certain sync probs, but sometimes things get worse, i.e. on old tape I'm getting more bad frames with TBC than without.
ANd the skewing is visible even withou using a tape- just a sat receiver to the VCR to the HW Bridge.