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-   -   Does anyone make an S-VHS VCR with TBC with USB/digital output? (http://www.digitalfaq.com/forum/video-capture/4235-make-vhs-vcr.html)

dantheman73 05-28-2012 01:59 PM

Does anyone make an S-VHS VCR with TBC with USB/digital output?
 
I was thinking it would be about ideal for S-VHS/VHS restorationists and others to have an S-VHS deck with built-in TBC that has a digital/USB output to send the digital capture data from the TBC directly to a computer without converting to analog again and back to digital via a computer capture card. This would eliminate the need for a separate capture card and have fewer steps in the signal chain. Does anyone know of such a VCR or expect that there is enough demand for one ever to be made before my VHS tapes all deteriorate too much to make it advantageous to wait?

lordsmurf 05-28-2012 02:12 PM

The problem with this is that such a piece of hardware would severely limit the abilities of archivists and restoration experts.

USB has very minimal bandwidth, compared against other communication protocols. That's one reason DV format video must be transferred across IEEE1394 (Firewire) connections, as Firewire is able to sustain proper bandwidth. While USB devices can sustain something like lossless Huffyuv, it's not guaranteed.

The other issue is that an external encoder like this would have to be purely hardware-based encoding. You'd be locked into a format, and manufacturers would choose the least common denominator: DV, AVC Intra, MPEG-2 @ DVD-Video or sub-broadcast specs, and similar borderline professional/consumer formats. A computer is required to make hardware more versatile, which is why many capture cards can capture using both internalized hardware (MPEG-2 hardware chipsets, for example), as well as fully uncompressed or lossless formats.

Such a device would be viewed by true professionals as a boondoggle more than a useful tool.

The inclusion of a TBC would also invite the wrath of the ridiculous anti-copy regime, who would accuse these devices of bypassing copy protection. Nevermind that such devices would be far outside the budget of your average "Blockbuster copier" (ignoring the fact that rental stores with VHS tapes is rare), and professional users don't care about copying readily-available commercial content. Zealots cannot be dealt with rationally.

VHS tapes have a realistic lifespan of 35-65 years, before the tapes begin to degrade in a meaningful way. That assumes proper storage, however -- air conditioned and heated homes or offices. People who put their tapes in barns, garages, attics and basements will see degradation in 10-20 years, in most cases -- but that's their fault, not the fault of the tapes or the VHS format. It's a videotape, not a garden rake!

The closest devices that exist are the JVC D-VHS VCRs or the JVC Professional DV/S-VHS combo decks. These have MPEG-2 output and/or DV output, in addition to having the line TBC of higher end JVC S-VHS VCRs. However, it's a line TBC, not a full frame TBC, meaning there's still room for signal-incurred quality loss or capture rejection. An external TBC is still suggested, and you'll have to loopback on the Professional-series combo decks, in order to allow the external TBC.

dantheman73 05-28-2012 03:37 PM

Quote:

The problem with this is that such a piece of hardware would severely limit the abilities of archivists and restoration experts.

USB has very minimal bandwidth, compared against other communication protocols. That's one reason DV format video must be transferred across IEEE1394 (Firewire) connections, as Firewire is able to sustain proper bandwidth. While USB devices can sustain something like lossless Huffyuv, it's not guaranteed.

Read more: http://www.digitalfaq.com/forum/newr...#ixzz1wCJbtdMu
Are you assuming that I was referring to first-generation USB? From what I've read online SD-SDI is 270 Mbps. USB 2.0 is 480 Mbps (more bandwidth than IEEE1394) - is that not fast enough? Of course there is always USB 3.0.

Quote:

The other issue is that an external encoder like this would have to be purely hardware-based encoding. You'd be locked into a format, and manufacturers would choose the least common denominator: DV, AVC Intra, MPEG-2 @ DVD-Video or sub-broadcast specs, and similar borderline professional/consumer formats. A computer is required to make hardware more versatile, which is why many capture cards can capture using both internalized hardware (MPEG-2 hardware chipsets, for example), as well as fully uncompressed or lossless formats.
Who said anything about an external encoder? Although that could be an option. But I would think that compressing via software would be a preferred method.

Quote:

The inclusion of a TBC would also invite the wrath of the ridiculous anti-copy regime, who would accuse these devices of bypassing copy protection. Nevermind that such devices would be far outside the budget of your average "Blockbuster copier" (ignoring the fact that rental stores with VHS tapes is rare), and professional users don't care about copying readily-available commercial content. Zealots cannot be dealt with rationally.

Read more: http://www.digitalfaq.com/forum/newr...#ixzz1wCKvc4AW
The digital output could be automatically disabled if Macrovision is present, in which case only the analog signal would be available.

Quote:

The closest devices that exist are the JVC D-VHS VCRs or the JVC Professional DV/S-VHS combo decks. These have MPEG-2 output and/or DV output, in addition to having the line TBC of higher end JVC S-VHS VCRs. However, it's a line TBC, not a full frame TBC, meaning there's still room for signal-incurred quality loss or capture rejection. An external TBC is still suggested, and you'll have to loopback on the Professional-series combo decks, in order to allow the external TBC.
Thanks for the info. For many tapes, wouldn't the advantage not re-digitizing outweigh the likelihood of signal incurred quality loss or capture rejection?

lordsmurf 05-28-2012 03:49 PM

Quote:

Originally Posted by dantheman73 (Post 20975)
USB 2.0 is 480 Mbps (more bandwidth than IEEE1394) - is that not fast enough? Of course there is always USB 3.0.

USB is a burst method of data transfer. It can be 480 Mbps, or it can be less than half of that. The keyword is "sustained" data rate transfer. Not burst. USB also pulls against the CPU, as it's not fully integrated into chipsets. In fact, not all chipsets are created equal -- notice the popularity, respect and demand given to Oxford chipsets, versus the others.

Quote:

Who said anything about an external encoder? Although that could be an option. But I would think that compressing via software would be a preferred method.
It would have to be an option. There's no other way to digitally pass out data from an analog device. In order to output over USB, Firewire or anything else, it has to be digitized inside the device first. Therefore it would require hardware encoding to enable this. There wouldn't be much point in embedding a capture card inside a VCR, which still requires a computer to function. An external VCR like this would essentially be combining several hardware appliances (TBC, encoder, VCR). And it would incur the downside of combo units, too -- namely that of 100% loss of infrastructure should a single piece die.

Devices similar to this do exist -- just not for VHS or consumer formats.

Quote:

The digital output could be disabled if Macrovision is present, in which case only the analog signal would be available.
This just isn't possible. "Macrovision" is nothing more than an artificial video error. Natural video errors get caught up in the same draconian dragnet, which is why so many consumers cannot transfer their home-shot family movies (junior eating peas, grandma blowing out her birthday cake candles, etc). It's "video error detection" more than "Macrovision detection", and any detected error makes the capture barf and halt.

Quote:

For many tapes, wouldn't the advantage not re-digitizing outweigh the likelihood of signal incurred quality loss or capture rejection?
I don't see where re-digitizing would come in.

Lack of pre-capture processing causes capture rejection. Digital devices expect perfect sync and signal from an erratic analog source. To make that happen, it must be properly processed first.

And then quality "loss" is almost a backwards way to look at it, when the topic is inferior video quality from an analog-to-digital process. It's actually an issue of the source not being processed prior to capture, which then forever embeds the analog errors into the digital version.

Loss also comes from hamfisted editing/re-encoding once it is captured/digitized. Transcoding itself does not necessarily incur loss -- it's the settings and methods used that cause loss. It's easier to make bad video than it is to retain quality, hence the numerous butcher jobs we see on Youtube, or from homemade DVDs created on cheap/junky video hardware from Walmart, Best Buy or the local office supply store (Office Depot, OfficeMax, Staples, etc).

Separate devices is actually a preferred method, because of two reasons:
1. Ability to customize the workflow.
2. Longevity of good hardware; replacement ability of bad/dead hardware. (Combo units throw out the baby with the bathwater.)

Make sense? :)

volksjager 05-28-2012 04:45 PM

no USB Super-VHS VCR exists, and no company is going to spend the money to make one for a very tiny niche market.
the firewire on the JVC D-VHS decks is as close as you will get and even that isnt as good as running the s-video into an external TBC and a capture card.

dantheman73 05-28-2012 08:28 PM

I'm quite unknowledgeable about TBCs (even after reading about them), but could there (theoretically) be some sort of standalone TBC that accomplished the same thing as the combination of both a built-in line TBC and a standalone full frame TBC (but only digitizing information once through the whole process) and had an SD-SDI output that could be fed into an SD-SDI capture card? If so, it seems that that would more than do what I was thinking of in effect (I was originally only thinking of having a digital output for a built-in line TBC).

The main thing I was thinking of avoiding is the conversion from analog video (VHS source) to digital (built-in line TBC) back to analog for output, then to digital (full frame TBC) then back to analog for output, then to digital via a capture card.

kpmedia 05-28-2012 09:56 PM

The loss from multiple ADC (or DAC) use is negligible. And it's not that the image data is digitized, but rather than the signal is digitized -- as opposed to the frame-by-frame capture of the visually constructed image, as happens during the video capturing process. So the loss you'd equate to image degradation is therefore not always applicable to signal manipulation.

If anything, altering the signal with corrective filters should improve the visual, as the visual can now be reconstructed properly.

(Technically speaking, yes, ADC/DAC does affect the underlying signal data that builds the visual image, but that makes for a complex discussion. While there is theoretical chance of loss due to ADC/DAC, that only happens when the ADC/DAC is of low quality. Much of this is solved by sampling higher than is needed, and then running a low-pass filter. Not everything in the signal is valid towards audio-visual material -- sometimes it's just noise.)

You have to mentally separate signal and image. :)

There's also something to be said for net improvement. The sacrifice of multiple ADC/DAC is tiny and inconsequential compared to the advantages of the corrected timing and sync.

dantheman73 05-28-2012 11:33 PM

Thank you for your well-written and informative response!

msgohan 05-14-2013 01:28 PM

Quote:

Originally Posted by dantheman73 (Post 20978)
I'm quite unknowledgeable about TBCs (even after reading about them), but could there (theoretically) be some sort of standalone TBC that accomplished the same thing as the combination of both a built-in line TBC and a standalone full frame TBC (but only digitizing information once through the whole process) and had an SD-SDI output that could be fed into an SD-SDI capture card? If so, it seems that that would more than do what I was thinking of in effect (I was originally only thinking of having a digital output for a built-in line TBC).

The main thing I was thinking of avoiding is the conversion from analog video (VHS source) to digital (built-in line TBC) back to analog for output, then to digital (full frame TBC) then back to analog for output, then to digital via a capture card.

I hope that it's okay to resurrect this, given that it's a very niche topic. This user hasn't been around for a year but I'm sure someone else has had the same thoughts.

http://www.digitalfaq.com/forum/vide...al-output.html

My method has:
  1. Line jitter correction
  2. Only one analog-to-digital conversion
  3. But, not much in the way of full-frame TBC (sync loss results in a blank HDMI signal being fed to the capture card)
  4. And the more pressing downside, which LS alluded to here: you're stuck with the adjustments the manufacturer allows you to make

For a while now I've also wondered whether the few VCR/DVD units that allow VHS to be output over HDMI do any horizontal jitter correction.

lordsmurf 07-26-2014 07:15 AM

I'm seeing some discussions of VCRs with digital output lately, so I wanted to bump this. :congrats:


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