VHS transfer+digital noise reduction

[keithm]

I don't know whether anyone has pondered over this: my latest SVHS recorder has digital noise reduction. When you switch this on it rather effectively reduces colour noise on playback: black looks blacker and all other colours lose the colour noise that is evident in VHS recordings. What has this got to do with computer based video editing?

Well: if you want to convert VHS to Mpeg (for vcd/svcd or DVD) the cleaner the picture the better: an mpeg converter has no way of knowing the difference between colour noise and picture detail (although I know some converters do have noise reduction built in); the converter will work much harder converting ares of colour that are dirty with noise.

The effect on tests I have done is a reduction in blocking on the encoded mpeg. This makes sense because if areas of colour are very noisy, especially with moving noise, the encoder will have to encode the noise.

On a different note: anyone transferring older HiFi vhs recordings to mpeg maybe in for a few shocks: I'm finding it very difficult to succesfully track older recording and have to revert to the mono soundtrack on mnay occasions

[Brian Ellis]

Keith

In theory, you are quite right but, in practice, I don't think it will make much difference. Noise reduction does just that, it doesn't pretend to eliminate it. If you have a grey background of, say, 127,127,127 and you have speckling with, say, 100,100,100, the reduction may change it to 120,120,120, if it is effective, and this would make it almost invisible (the same with colour). However, the speckles will not render to 127,127,127 and the bandwidth required will be exactly the same, whether they are 120 or 100.

I confirmed this by taking a short, noisy clip (taken by hazy moonlight) and applying all sorts of noise manipulation in MSP. I also tried a similar exercise on a still in PhotoPaint, which has much more sophisticated noise manipulation algorithms. In both cases, noise reduction gave a much better visual impression, but the file sizes were quasi-identical.

What is HiFi VHS?

[az]

I think he means the HiFi stereo track of VHS recordings, as opposed to the LoFi mono track.

There are several good noise reduction etc. filters for virtualDub. C't had a good article about how to get old VHS tapes into the PC with VirtualDub, which filters to apply, etc.

If you want, I'll dig it out & post the important parts here. (i.e. which filters they suggest, etc.)

AZ

[keithm]

Yes: I do mean HiFi Stereo VHS. If a recorder mistracks it you can hear the soundtrack crackle or worse still drop in and out of to the mono soundtrack. still think the noise reduction on the VHS helps. I am tranferring some old sci fi episodes and the black of space looks better on the vhs and the converted mpeg with it switched on.

[wkulecz]

If anyone is serious about capturing old tapes to DVD-R or DVD+R I strongly recommend an SVHS deck with digital noise reduction and time base corrector like the JVC 9800 (~$350 if you shop carefully).

Record your TV shows to it on SVHS tape while waiting for the standalone recorders to get cheaper and offer decent menu/chapter setups.

--wally.

[az]

What is the time base corrector used for?

AZ

[Dr Mordrid]

Restoring synch pulses to video frames where they have degraded or been modified by older forms of analog copy protection. Synch pulses tell the display/capture device when to start a new frame.

Some are plain TBC's and can be had as a PCI card or in a box. They are also found in higher end SVCD decks. JVC's from the 7900 series and up have them.

Others can be found in combo devices and include other features like colorburst restoration, color channel modification & amplification, superblack etc. etc. One such mixed device is the Elite Video BVP-4+. I have one of these for cleaning up video from old/degraded sources and it can work wonders.

Dr. Mordrid

[Technoid]

how much do they usualy cost ?

[Dr Mordrid]

What? The BVP4+? Around $800 USD now, but I got mine for $739 a while back.

http://www.elitevideo.com/evbvp4.htm

PCI mounted TBC's (they only use the PCI slot fo rpower) can be had for about $200 or so.

TBC equipped SVHS decks like the JVC 7900's street for about $300 USD.

Dr. Mordrid

[BrianP]

As it turns out, this week I have been archiving my old (mid-1980's and up) VHS to D8. I borrowed a Panasonic SVHS deck and rented a TBC. (The SVHS deck is a beast-- it weighs close to 30 lbs. It has noise reduction, but not internal TBC). I didn't bother to test with/without the TBC, but everyone suggested I use one, so that's what I did.

Anyone know if some of the prosumer cameras like the VX1000/2000 have built-in TBC? I remember reading that even some of the better comsumer camcorders have them these days. Unfortunately my D8 is an older model that definitely does not have built-in TBC.

[Karen St Martin]

For anyone who is interested.

I got a JVC HR-S7800 Super VHS VCR for $199 from www.crutchfield.com. This VCR includes Time Base Correction and Digital Noise Reduction, it also weighs a lot less than 30 lbs <G>. I have used it to transfer tapes that my cheaper decks wouldn't touch.

Hope this helps!

Karen