any workarounds for these common VHS problems?

[Fullasoul]

Hi,

Excuse me for not having all the technical lingo down, but I'm wondering if anyone here has established any kind of solutions to a couple of very common problems associated with VHS sources. The first one is that stripe of color that can sometimes occupy (as much as) 1/8th of the top of the image....especially with weaker (or copied) videotapes. The second one, once again associated with *nth generation copies (leaving a very weak signal of course) is the wavy effect...whereas even stationary vertical objects on screen appear to look wavy.

I realize the odds are that there are probably no real solutions to these problems (the everpopular 'garbage in-garbage out' line), but I've learned a LOT about this stuff from people in this forum, so I thought there would be no harm in asking if maybe someone here has found some way to minimize these effects???

[mf]

fxVHS (http://www.neuron2.net/flaxen/flaxen.html).

[Fullasoul]

hmmm....i was never able to get far with this filter. If I recall, it allows chroma shifting (which i can do adequately with other filters i use), and chroma noise reduction (again, i've used other filters that can do this just fine), and a "stabilize" function which i was never able to determine how to use, or even WHAT it does for that matter. Do any of these functions apply to the 2 problems i mentioned??

[mf]

Well, there aren't many filters that have gone unnoticed to me (before AVISynth I went through the homepage of every single vdub filter developer linked on neuron2's page), and this is the only filter that does specific VHS things iirc.

[scharfis_brain]

forget about fxVHS!

it is just a Filter-combo of
- spatio-temporal denoiser (bad denoiser)
- chroma-shifter
- sharpener


better use AVISynth-denoisers for the denoising.

btw. I've never seen that kind of wrong-colored stripe on the top of the frame on my PAL-Tapes, but on many NTSC-Tapes (even 1st generation Commercial Tapes), so I assume this is a NTSC-Typical thing.

the horizontal line kitter may be reduced with multiple capturing.

[FredThompson]

Get a good VCR with digital correction and TBC. An additional TBC might be needed to clean up the top lines. What you are describing is so screwed up that filters aren't going to do that much to help. nth-generation copies might be unfixable, so to speak because if the equipment used was low or average quality, you've got wiggly copies of wiggly copies. There isn't an easy way to fix this.

[mustardman]

I've had these very problems as well (with PAL), and the tapes I had were originals! (ie: videocamera tapes, where I took the tape out of the camera myself).

The colour at the top of the frame : it seemed to shift red/orange/yellow colours to green. This was apparent with a TBC turned on, as the shakes of the operator caused unreliable captures without the TBC.

Wriggly vertical lines : Another (different) tape, different camera too... The recording environment was very loud and the camera was being jostled. Known straight objects, like telegraph poles, become more like crinkle cut chips! Other tapes again have these wriggles, seemingly always caused by physical shock or vibration to the camera, which is after all a mechanical recording system! (VHS/Hi8 analog)

I found no solution to fix these things, so I eventually decided to just put up with them!

PS: The "wavy lines" also appeared on the 'black bars' to the right & left of the image. I figured the "wavyness" could be corrected by looking at the 'black to picture' transition and making this straight. But, I'm no programmer, and interest is low. I have no idea how you would fix the colour problem!

[Mug Funky]

the black border method will fall over with poorly mastered tapes or dark scenes.

there was a thread aboot this a while ago. the only surefire way to fix this is with a hardware solution, or if some genius could find a capture method that keeps the overscan sync pulses (which cause the problem).

if the overscan areas were available a filter could be written to do the "black border" method... offset each line to a predefined position with some accuracy.

DV footage _seems_ to record the overscan lines, but i don't know about the sync pulses (we can only infer that DV records the off screen lines because of macrovision tapes that have been captured but were not able to be put back on VHS)

[FredThompson]

I was part of the thread you mention. Long story short, it's not as simple as lining up the black edges because those are also somewhat variable and you'd have to be inside the player to get a good set of data anyhow. There's a piece of post-processing equipment from a British firm that's supposed to help with this. That was in the thread as well. Sorry, I don't remember enough about it to recall any key terms or I'd have hunted it down and provided a link.