Noise in capture process, coming from where?

[jake6922]

I am using a DVD recorder to capture old VHS tapes (I realise this is not ideal, but I can't afford to splash out on a capture card or conversion services etc). Take a look at the following snapshot from a capture of my VHS's settings menu:


[Attachment 38473 - Click to enlarge]

See the noise in what should be a completely clear picture? I'm not sure where this noise is coming from. If I plug my VCR directly into my TV, using the same cables that I plug into my DVD recorder, there is no noise. I have tried a couple of different cables, with all of them I end up with the same noise, but if I bypass the DVD recorder and plug straight into the TV, I no longer get this noise. I've tried two different TVs, with the same result. If you're not sure what I'm talking about, I've included a 2x nearest neighbour upscale of the most visible part:


[Attachment 38474 - Click to enlarge]

Look at the 'fuzz' in between the letters on the yellow line, the dirt within the white M, N and U letters, the random pixels towards the top of the yellow line. None of this appears when I plug directly into my TV (of course, I can't send a screenshot of that), the clarity is far superior.

Where would this be coming from? The cabling? The DVD recorder input? I'm using composite cables (red, white, yellow) since that's the only output my VCR offers. But if the VCR output was the issue, then surely the noise would show up on the TV? How can I get rid of this noise to make sure it doesn't affect my captures?

[Pinto007]

It looks like a dot crawl. You don't see it on TV, because TV has better comb filter apparently. To resolve this issue you can:
- get a S-VHS VCR and connect to DVD recorder via s-video cable
- or get a better recorder with 3D comb filter

[jake6922]

Thanks. Is comb filtering something I can do with VirtualDub or AviSynth? I'd like to avoid buying expensive equipment if possible.

[Pinto007]

Oh yes, I forgot about software There are some threads in RESTORATION about Avisynth methods.

[jagabo]

With VHS caps you can can nearly eliminate dot crawl artifacts by simply resizing the frame to half width then back up to full width. That doesn't hurt the underlying picture much since VHS doesn't even have 360 lines of resolution horizontally.

Spline36Resize(width/2,height).Spline36Resize(width/height)

or

Spline36Resize(width/2,height).TurnRight().nnedi3(dh=true).TurnLeft()

A little sharpening can be added if necessary.

There are specific dot crawl removal filters like CheckMate() but they sometimes cause other damage.

[Cornucopia]

As dot crawl is a somewhat random playback-originated noise effect, you should be able to nearly eliminate it (without otherwise losing quality), by multi-capturing and using MEDIAN on synced copies.

Scott