Identify this type of VHS video defect?

[Phthalocyanine]

As shown in the uploaded screen captures, the defect begins with black horizontal lines that then turn into large blocks of video noise in green and blue.

I've encountered these on commercial VHS movie tapes -- but just barely commercial. These are EP releases of the dregs of Mexican Cinema, "Film Coleccion" from Roca's Distribution. So this defect could be in the mastering or the manufacturing of the tapes. The tapes are probably at least 20 years old, although several were still factory wrapped. Not all of these tapes exhibit this defect but the only time I have seen this defect in any VHS tape has been in these series of tapes.

My equipment is good (JVC SVHS 9500) and the defect does not appear in any other tapes I've transferred.
Is this the kind of defect (like drop-outs) that can be improved by playing and re-winding and playing again?

[msgohan]

The green & blue blocks look like a digital error. Try playing it in a plain-jane VCR instead of the fancy JVC. People here give them away on Craigslist multiple times a week; perhaps the same is true where you live.

[Phthalocyanine]

Hi Msgohan,

I appreciate the prompt reply, thanks!

I was interested to hear that this does appear to be an unusual defect. I've transferred more than 100 commercial and home-made tapes at this point and have not seen anything like this before.

You make an excellent point about trying the tape in a VHS player with no (or much less) digital noise reduction or time based corrector circuitry than is found in the JVC SVHS players. That could rule out this being a digital artifact created by the player. If I can borrow such a player I can try at some point. (But my wife will kill me if I bring in another VHS player permanently!) I did try the tape in another JVC I had at hand, a HR-S5911U, which does not have a time-based corrector. The same defects appear at the same places. But this deck is also a late series JVC SVHS with digital noise reduction circuitry, so your point stands. Also, I had the TBC turned off when I did the capture with the JVC 9500, because, in my experience, the TBC causes problems with low quality EP recordings.

Clearly, the green and blue blocks represent areas where information has been lost, and is being filled in in a way that looks like what a digital device would do with lost information. The question is whether this occurred during the tape mastering or is a defect on the surface of the tape now. I notice increased noise crackling during these defects, which might point to damage on the surface of the tape.

Here are two more screen captures showing even more severe instances of this defect on the same tape.

[msgohan]

Quote:

Originally Posted by Phthalocyanine

I did try the tape in another JVC I had at hand, a HR-S5911U, which does not have a time-based corrector. The same defects appear at the same places. But this deck is also a late series JVC SVHS with digital noise reduction circuitry

Nah it's a plain consumer VCR, just with S-VHS playback. JVC didn't advertise any DNR feature, which they always coupled with their TBC except in the "broadcast" models where they were separated.

A 5-second video sample attachment of the same portion played on both VCRs would be more useful than screenshots, but I doubt there is much more anyone can say even with samples. Unless someone has seen this artifact before.

I take it you've never viewed these tapes before.

[Phthalocyanine]

I never viewed these tape before so I have no idea if this defect was always there or is the result of deterioration. I picked these tapes up cheap (like 25 cents cheap) at a videos store that is dumping massive numbers of tapes. In Northern California where I live even the Goodwill stores have stopped carrying VHS tapes. The vast majority of commercial tapes (which includes a lot of former rental store stock) is now going down a giant vortex into landfill or overseas or wherever non-recyclable waste goes these days. I'm just trying to catch a few quirky specimens as they spiral down into oblivion.

I had a Sima color corrector box in my capture chain (VHS player to Sima box to Magnavox (Finai) 2160A HDD DVD Recorder). I just tried by-passing the Sima box in case it was the culprit, but it made no difference.

Now that we've ascertained that the JVC HR-S5911U is as plain Jane a VCR as one could want for testing, it seems that the defect must be in the tape. Given the very dubious manufacturing origins of these tapes, the defect could have been there from the beginning (defective mastering), or has emerged as the tape deteriorated.

[msgohan]

Quote:

Originally Posted by Phthalocyanine

the defect could have been there from the beginning (defective mastering), or has emerged as the tape deteriorated.

Thought you were using a cap card, not a DVD recorder. As I see it there are two possibilities, with VCR circuitry and external correction boxes ruled out:

1. "Digital blocking" was recorded this way to the tape and would have always looked like this to anyone who viewed it on any VCR. (90%)
2. DVD recorder is adding the "digital blocking" due to misinterpretation of an analog signal problem coming off the tape. (10%)

I assign a 0% probability to the deterioration theory. If it was just the black lines, that would be possible.

Watching the plain VCR playback connected directly to TV should rule out or confirm the DVD recorder. Preferably a CRT, since any pixel-based display also has to digitize the signal.

Looking very carefully at the two recordings / Subtract filter in AVS would help determine whether the artifacts appear exactly the same or just nearly identical.

[Phthalocyanine]

Yes you make a good point. Analog deterioration does not look like this. I'm satisfied that this was an error in the tape mastering process, which involved some sort of digital processing.

One additional note about the JVC HR-S5911U. Although it does not have a TBC or DNR, it does have the picture control "filters": AUTO(NORM)/EDIT/SOFT/SHARP.

I've never really understood whether these were based on digital processing or not.

The JVC HR-S5911U represents the inverse of the HR-S9500U, which has the TBC and digiPure DNR, but does not have the picture control filters (which is fine with me since I always set the picture control to "edit" which is equivalent to no filter).