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-   -   Complete video/audio dropouts on Betamax tapes? (https://www.digitalfaq.com/forum/video-restore/3624-complete-video-audio.html)

moxiecat 11-03-2011 09:01 AM

Complete video/audio dropouts on Betamax tapes?
 
This isn't a question so much as a need for further analysis/explanation.

I'm transferring some Betamax tapes that are quite old. On some of the tapes, the video and audio often completely vanish. For example: the video will play for about five seconds, then the screen goes completely black and silent, during which the counter doesn't move. After a second or two, the picture and audio comes back and the counter again counts. But it's obvious that some video has been skipped (the missing video creates a jump cut, so to speak).

On some tapes, these errors clear up a few minutes into the tape, but on others, this keeps happening. Often it happens just after edit points (where the camcorder or VCR recording was stopped and started again). I have tried the tapes on three different Betamaxes, and the black screens happen at exactly the same spots on the tape. So I have ruled out machine error for that reason.

I completely understand that the likely explanation is that the magnetic particles have disappeared from these spots on the tapes, so there is literally no video or audio there anymore. But up until today, I called this phenomenon "dropouts," and now I see that term actually refers to streaks in the picture.

So I'm looking for a term for this. I have looked everywhere online and can't find a good explanation. I was hoping someone here could give me a better description as to what is (likely) happening, so I can share it with the owner of the tapes--especially if I'm mistaken in my own analysis above.

Thank you for your help.

kpmedia 11-03-2011 09:11 AM

Yes, "dropouts" refer to the static streaks in the video image.

What you're seeing is unrelated to magnetic particle loss. That error you've described is a recording-time error. The video was not properly recorded to the tape in some sort of mechanical interval. The camera or VCR was not recording the signal properly. There's even a chance that something was causing the head to build up a static charge that was dispersed in an interval, thereby erasing segments on the tape, instead of recording to them.

I have a tape here, but VHS, with the same error. No amount of restoration can overcome missing signal. For these people, it's unfortunately a lost memory. We can't do anything to help them. It's never an enjoyable task to tell a client that their videos of grandma or whoever are gone and irrecoverable.

I'm not aware of any single-word term to describe this scenario.

moxiecat 11-03-2011 09:27 AM

See, this is why I checked here first!

I always thought, though, that when the oxide on the tape was gone, that also resulted in the complete loss of the video and audio. I have some other Betamax tapes here that literally have the "black" missing from the physical tape (in other words, the plastic tape is just clear in those spots). These tapes also play with 100% black screens when those areas pass over the heads--and it's obvious why. Isn't it possible the same thing could be going on here?

But I do think you may well be right as well in that they were misrecorded. I am having a lot of trouble playing these tapes with an intact Hi-Fi signal, which is also rare in my experience with Betas--usually when you get the tracking set, the Hi-Fi comes along OK too. I also believe they are dubs. And BIII, which doesn't help!

I am just worried that the person will swear that these tapes used to play fine...in which case wouldn't it likely be some type of degradation?

Just my thoughts on this. Thanks again for your insight.

kpmedia 11-03-2011 09:55 AM

If the tape is physically clear (blank), and missing the oxide layer -- sure -- then that would be the issue. If the tape is still black and looks clean, then it's a recording/signal issue.

I've learned to not trust (not believe) anybody that claims that a tape was "fine" at any point in the past. I've found that most people:
  • Record video and never watch it off the tape.
  • Have tapes that were only "watched" once or twice. And "watching" is quoted because the term is only used loosely. The video was more like background music at a family gathering than anything that was watched with an eagle eye. It wasn't given the same treatment as if you were quiet and sitting in a movie theatre with nothing else to do (no distractions).
  • Have tapes that were ruined without their knowledge. Children playing with the VCR, for example.
I can only remember 1-2 incidents in the past decade where somebody insisted that they were without fault, and that our VCRs must've "damaged" their tapes in some way. All ridiculous, of course. When countered with the above three reasons, the people usually got more defensive, angry that we "accused them of lying". Also ridiculous. People can swear all they want, but the fact remains that they're probably mistaken ("misremembering") or unaware of third-party abuse.

It's the same issue with people who insist data "disappeared" from their DVDs. The cheap discs were never used, played, tested, etc. Some people swear and promise they're not mistaken, but when pressed for specific details, they're never able to give any. It's just assumptions compounded by poor memory, and further compounded with being stubborn and close-minded (anti-science). And that's on them, not on you.

There's nothing special about Beta vs any other tapes (VHS, DV, whatever). Tape is tape, on this topic.

moxiecat 11-03-2011 10:39 AM

Checked the tape, and it's perfectly black. I can't see any visible damage with my naked eye.

The only reason I ask about the "I KNOW it used to work!" defense is because I have a Betamax tape from my childhood that is similar to this situation. At the very end of this tape (within the last half hour of the BIII, 4 1/2 hr. running time), is a cartoon I used to love. I watched it a lot back in the '80s. When I went to transfer the cartoon to DVD five years ago or so, it had this exact error: short sections of black/silent screen, albeit all at the very end of the program (and thus, the VERY end of the tape). I chalked it up to wear/aging, especially since the major problems happened within the last five minutes of the tape itself. But this cartoon DID play fine when it was in its prime. (I watched it enough to remember. :)

So that's the reason for my question. But in any event, the video is not recoverable, and that's all that really matters. And I'll have a few potential reasons to give her, so that's really good.

Thank you so much for your help!

-- merged --

May I pick your brain on one more thing with this tape?

First of all, the good news: the middle 2+ hours of the tape play surprisingly well. There are a couple brief black screen moments, but not too bad. Much of the videotape is actually usable and plays consistently.

But at the end of the tape, I ran into something else: a black screen that just lasts and lasts. The video picture never comes back. At first I thought nothing was recorded there. BUT then I found the video is visible upon pause, rewind, and FF. I spun the tracking dial back and forth, and tried the same section of tape in another Betamax, but the exact same behavior occurs in both machines (always at the exact same spots, so this is definitely an issue ON the tape itself).

This makes me think even more that the video signal was not recorded properly (as you noted). But couldn't this possibly be an alignment error that was present on the original recording device? The earlier black screens were too brief for me to test if the video was there or not, but now I bet they are--and not rubbed away. Just unplayable/inaccessible.

Any thoughts?

NJRoadfan 11-03-2011 04:43 PM

Are all these Betamax decks Sony models? There is a possibility your "ACE" head (reads linear audio and control track) is dirty or failing. I had a similar problem with some Beta-III tapes in my SL-HF860D, you can sometimes see video when cueing, and for about 3 seconds after you press play and "bam" the screen goes black and no audio. Cleaning the ACE head fixed the problem for me, your mileage may vary. In my case all the affected tapes played with no problem in my Sanyo machines (completely different threading and transport system from Sonys). One thing I also noticed is that while Sony's threading system is less stressful to tape (compared to VHS's M-load system), the machine tends to have more problems playing back less then perfect tapes (ex: ones with creases) and they are more likely to have playback/tracking alignment problems if tape tension is off. It appears the Sanyo machines have a tighter tape wrap around the drum and seems to make better contact with the fixed ACE head when the machine encounters tape damage (they seem much more forgiving).

More info here about the ACE head problems: http://www.mrbetamax.com/AskMrBQ&A.htm#Question%209

moxiecat 11-03-2011 06:21 PM

That's interesting about the ACE and the Sanyo decks. Definitely stuff I didn't know.

Yes, all my decks are Sonys. Two of the three units I tried with this tape were actually serviced within the last couple months by Mr. Betamax, and haven't been used too much since then. So I kind of doubt that the ACE head is to blame since he would have caught that--and it's unlikely that both would have the same problem as well. Plus, the black screens happen at the same time in the video on both decks. So the problem is either the tape itself, or how the Sony apparatus handles the tape.

And also--much of this tape DID play just fine, and other tapes do as well. But I'd love to know what condition causes these certain sections of video to only be visible on pause/FF/RW. This must be indicative of some specific issue, whether a misrecording or something similar.

deter 11-03-2011 07:54 PM

Have a bunch of old Betamax tapes (20+ years) some tapes are better than others.

A bunch of the Betamax tapes have the OXIDE / VIDEO DROP OUT PROBLEMS.

Been working on this for a few years now and have asked tons of Questions over at Video Help.

BLACK SCREEN COMPLETE LOSS OF PICTURE FOR MORE THAN A FEW SECONDS, NO IDEA, WOULD JUST EDIT THAT OUT OF THE VIDEO OR TRY TO BLEND THE VIDEO TOGETHER.

Found using a basic script has helped some of the videos.

Code:

LoadPlugin("c:\program files (x86)\avisynth 2.5\plugins\RemoveDirt.dll")
LoadPlugin("C:\Program Files (x86)\AviSynth 2.5\Plugins\removegrain.dll")
LoadPlugin("C:\Program Files (x86)\AviSynth 2.5\Plugins\despot.dll")

function RemoveDirt(clip input, bool "_grey", int "repmode")
{
    _grey=default(_grey, false)
    repmode=default(repmode, 16)
    clmode=17
    clensed=Clense(input, grey=_grey, cache=4)
    sbegin = ForwardClense(input, grey=_grey, cache=-1)
    send = BackwardClense(input, grey=_grey, cache=-1)
    alt=Repair(SCSelect(input, sbegin, send, clensed, debug=true), input, mode=repmode, modeU = _grey ? -1 : repmode )
    restore=Repair(clensed, input, mode=repmode, modeU = _grey ? -1 : repmode)
    corrected=RestoreMotionBlocks(clensed, restore, neighbour=input, alternative=alt, gmthreshold=70, dist=1, dmode=2, debug=false, noise=10, noisy=12, grey=_grey)
    return RemoveGrain(corrected, mode=clmode, modeU = _grey ? -1 : clmode )
}   

DirectShowSource("c:\XXXXX.mpg") #open your video
ConvertToYV12()
RemoveDirt()

Sometimes use different scripts

This filter can take out good detail out of the video, it will clean up most of the drop outs.

Maybe other people have better scripts they use or something that is less harsh on the details.

OLD FILM that was converted to VIDEO, those Drop outs are not fixed w/ this method.

With the Betamax tapes found that the dropouts are caused by errors or loss of data on the tapes, and you restore them after you capture the video.

-- merged --

One more thing, had a tape with really bad oxide shedding and it almost wrecked two of my VCR's. It was a royal pain cleaning up the mess it left behind.

HEAVY OXIDE SHEDDING = MESSED UP VIDEO HEADS AND PLAYBACK

BAD TAPES = DO NOT PLAY IN THE VCR !!!

YOU SHOULD CLEAN YOUR HEADS AFTER CAPTURING ANY TAPE THAT HAS SHEDDING

This is a hard thing to get around, wanted to do tape-baking but never found a place to bake VHS or Betamax tapes. I tried it myself and melted the reel on the tape. Set the baker at the specific temp it needed to be.

I am not good enough to pull the tape from the reel and re-set it....I think tape baking would help and would let some bad tapes play ok for a short period of time, just don't know how to do it or found a place that would/could bake them.

Yes I was sent a link to a tape baker from this site, but that guy is crazy and wouldn't help or let me send him a tape. He will not tell you how he does any of his work either.

Maybe you will have better luck....

http://www.videointerchange.com/tape.htm#Tape Baking

kpmedia 11-04-2011 05:11 AM

Quote:

Originally Posted by moxiecat (Post 17906)
a black screen that just lasts and lasts. The video picture never comes back. At first I thought nothing was recorded there. BUT then I found the video is visible upon pause, rewind, and FF. I spun the tracking dial back and forth, and tried the same section of tape in another Betamax, but the exact same behavior occurs in both machines

On the VHS format, this often happens on cheap consumer VCRs made in the late 1990s and early 2000s, after LP mode lost popularity and was no longer included in decks. The signal was observable when the tape was run across the heads quickly, but normal playback was black or snow because the VCR did not understand LP recording mode. This could be the situation with your Betamax tape.

If a preset speed isn't the issue, then it could be an issue with off-speed recording by a malfunctioning VCR.

Because the signal is helical scan, and not linear, this loss of image can happen. Compare it to audio tapes, which are linear. If an audio tape is recorded off-speed, then the person/music just sounds "chipmunk" or "drunk". I have some audio tapes recorded in the 70s and 80s, from my personal collection, that were made on a recorder that was apparently dying at the time (or never good to begin with). I have to experiment with speed-up in Sound Forge, and waiting until it sounds good to my ears.

The "ACE" head issue described above is comparable to the LP mode issue. Not "the same", but same overall family of problem.

@deter and anybody else reading this:

Do not use DirectShowSource in Avisynth! It's not reliable. Instead use ffmpegsource for MPEG videos, as it generates its own dgindex. Realize it's going to be slow to open a video, as this index is built on longer "movie length" type clips (1+ hours of content), so walk away from the computer for 10-15 minutes while it builds. Shorter clips won't really be too noticeable on open lag/delay.

Here's a similar script that was recently used as part of a project:

Code:

function RemoveDirt(clip input, bool "_grey", int "repmode")
{
    _grey=default(_grey, false)
    repmode=default(repmode, 16)
    clmode=17
    clensed=Clense(input, grey=_grey, cache=4)
    sbegin = ForwardClense(input, grey=_grey, cache=-1)
    send = BackwardClense(input, grey=_grey, cache=-1)
    alt=Repair(SCSelect(input, sbegin, send, clensed, debug=true), input, mode=repmode, modeU = _grey ? -1 : repmode )
    restore=Repair(clensed, input, mode=repmode, modeU = _grey ? -1 : repmode)
    corrected=RestoreMotionBlocks(clensed, restore, neighbour=input, alternative=alt, gmthreshold=70, dist=1, dmode=2, debug=false, noise=10, noisy=12, grey=_grey)
    # return RemoveGrain(corrected, mode=clmode, modeU = _grey ? -1 : clmode )
    return corrected
}   

AVISource("C:\Clip.avi") # use for AVI sources
# ffvideosource("C:\Clip.m2v") # use for MPEG sources, must be demuxed
ConvertToYV12()

Cnr2("xoo",4,5,255) # remove heavy chroma banding noise, wide UV setting
# Cnr2("xoo",4,2,64) # remove light chroma banding noise, wide UV setting

# TurnLeft() # these 3 lines optional for heavy scratch damage
# DeScratch(mindif=5)
# TurnRight()

DeGrainMedian(limitY=15,limitUV=7,mode=0) # remove heavy videotape grain, but may create plastic look

DeSpot(p1=35, p2=14, pwidth=200, pheight=30, mthres=25, mwidth=20, mheight=15, interlaced=false, merode=33, ranked=false, p1percent=0, dilate=0, fitluma=false, blur=4, motpn=false, seg=0)
# DeSpot(p1=35, p2=14, pwidth=70, pheight=70, mthres=25, mwidth=20, mheight=15, interlaced=false, merode=33, ranked=false, p1percent=0, dilate=0, fitluma=false, blur=4, motpn=false, seg=0) 
# DeSpot(p1=35, p2=14, pwidth=70, pheight=70, mthres=25, mwidth=20, mheight=15, interlaced=false, merode=33, ranked=false, p1percent=0, dilate=0, fitluma=false, blur=4, motpn=false, seg=0, tsmooth=3)

RemoveDirt()

Deblock() # remove macroblocks

# TTempSmooth(maxr=5, lthresh=16, cthresh=4, strength=4) # temporal NR
# FFT3DFilter(sigma=4, bt=3, plane=3) # denoiser
Deen() # remove edge noise

spline36resize(720,480) # resize to D1 for DVD

You'll need to have Avisynth 2.5x 32-bit installed for this, as well as added filters. We're currently working on a massive Avisynth restoration section for the site, which covers common scenarios in detail with guides and downloadable "Avisynth kits" for ready-to-use usage (MT versions, 64-bit, 32-bit, etc). Some of the more advanced guides may be available only to Premium Members, too.

Not for the faint of heart. This gets complex quickly. :eek:

moxiecat 11-04-2011 07:17 AM

All that script stuff is beyond me, frankly. :)

I'm more and more sure that this was a recording error. Betamaxes only had three recording speeds, as far as I know: Beta I, Beta II, and Beta III. Beta I was the best quality setting, but I don't know if I've ever seen it on any tape--I believe many units couldn't record to it, only play it back. Beta II was the "better" setting that people used if they wanted good-quality video. (Both are sort of analogous with SP; Beta II is not the same as LP, since it was far more standard.) Beta III was the EP/SLP equivalent, and that's the speed used on these tapes.

Now, I don't know if non-Sony machines had different settings than these--I doubt it--but can anyone post if they know?

This tape also does not have a Hi-Fi soundtrack, which is very odd for a Betamax tape in my experience. So I have no idea what VCR was used to tape this video (I think it's dubbed footage from a camcorder). Maybe it was not a Sony deck but some random cheapie unit. And it was probably 25 years ago that it was done, so I doubt there's even anyone who remembers the specifics.

Well, I think I have enough information to work with here. Thanks for all your help, everyone.

deter 11-04-2011 08:01 AM

Interesting reading, with this Betamax problem.

Beta has modes, I,II & III and SuperBeta.

Most of my stuff is, Beta II or III and the audio is mono.
(They contain a lot of hiss)

None of the Recordings are Beta I

One of the machines, SL-HFR-70, would sometimes have picture play back problems with some of the old tapes. Thinking back a few years....

This was kind of weird, the SL-HFR-70 would have an error like you wrote about or create different errors.

Would try the tape in another machine, that error would show up again. (It would grain tracking problems or other rare playback issues)

Would wait a few days, try the tape again on another machine, SL-HF860D, and it would play fine.

Can recall on a few tapes the SL-HFR-70, would only play a black or snowy screen, can't recall about the audio.

With the SL-HF860D, had the pinch rollers adjusted, the heads cleaned and a few other adjustments to the machine, it has only been about 1 year, but have not had any playback issues since. (However don't use this machine very often.)

The SL-HFR-70 model is now only used to rewind / fast foward tapes.

One last thing of note, have sometimes found a weak signal from the Betamax machines, some of the tapes do need the use of an external TBC to fix some of the picture errors. However going direct to the TBC sometimes will create a complete signal loss. To fix this, run the picture through a JVC 7900U SVHS player and than S-Video to the TBC.

Was not aware of this DirectShowSource problem. What types of issues does it cause?

Trying to think back, cause I use five computers to do video work.

On one machine, windows7, ran this script and it only ran through 1/2 the video. That was before NetFrame 4.0 was installed on that machine. Don't use Avisynth that often. (Betamax Recordings and Old Film)

On the XP and Vista Machines, can't recall ever having any script or Avisynth problems. (They are pretty much the machines that are used to do the scripting.)

The final copies of the videos have turned out fine.

kpmedia 11-04-2011 08:18 AM

Quote:

Was not aware of this DirectShowSource problem. What types of issues does it cause?
Out of order frames, for example. The problem is that DSS relies on system-wide DirectShow settings, instead of closed known-good libraries. And for that reason, any number of issues can happen. DS long ago fell out of favor, because it requires system-wide codec installations (the main reason those silly "codec packs" came into being). Librarying of codecs is the ideal way to approach video, and is how something like VLC or FFMPEG functions.

jmac698 11-04-2011 09:37 AM

@kpmedia
This is more of an issue for unknown computer setups. I only ever install ffdshow/hali splitter and directshowcourse works fine for me. My mpegs are decoded by ffdshow/libav and they're fine. This is the same library used in ffmpegsource.
Now for random seeking, there might be issues, but encoding, even with temportal filters, avisynth cache takes care of that.

ps I purposely made recordings with +20% speed in the 80's, it gives much better performance. Some decks had this speed adjust for DJ's I guess. To hear them now I can adjust it in Audacity.

@deter
I thought we discussed before about "dropouts". These are not always oxide falling off, but more of a weak signal level problem. The dropouts appear in different spots on the video. It's easy to fix, and perfectly, just by merging 2 or more recordings.

http://screenshotcomparison.com/comparison.php?id=84395

http://screenshotcomparison.com/comparison.php?id=84396

tomswift 05-24-2013 05:45 PM

I just got my SL-HF900 back from Mr.Betamax yesterday (after getting it reconditioned), and yesterday I recorded a test on a tape and it recorded an played back fine (it was on a blank tape that he sent back with the VCR along with the test tape) and it plays fine today, along with the test tape and a store-bought Daffy Duck tape. But I had picked up a box of tapes that someone had recorded on years ago (one has an ad for the 1983 New Year's Rose Bowl Parade on it; there were tapes by Scotch, Maxell, BASF, Fuji and a Super Beta Demo tape) and even though I had fast-forwarded/rewound the tapes first, now that I read this, I wonder if there was still shedding happening and now my ACE is so clogged, that even the Copyright Cleaning Tape I have can not clear the blockage, and the only way is to manually clean it?

Anyone think this would correct th problem of not recording properly?


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