possible to fix vertical color stripe?

[spiritgumm]

I had to use a video "stabilizer" box to enable recording a VHS tape to dvd recorder. The VHS tape color is somewhat muted but looks okay, with no edge stripe when VCR played direct to TV. The dvd recording is washed out so I was going to adjust/boost the dvd recording color with Avisynth. After doing a test sample, I noticed a vertical red/green stripe on the left edge. The stripe is there before processing, but not as noticeable. I'm thinking it was from the stabilizer box.

Plugin Chromashift isnt appropriate, and FixChromaBleeding avs didnt help. I tried cropping the left edge into a mask (before boosting color), then overlaying it over color-boosted video, but the mask stands out too much (even after some adjustment).

Here's a pic from an xvid after boosting the color. Red/green stripe on left edge extends in almost to the man's wristwatch. The xvid was deinterlaced, cropped/resized, but the stripe was there before processing.

[poisondeathray]

What "stabilizer box"? Can you use a different one ?

What is the pattern? e.g. Does strip move over time? Is it constant, fixed ?

You're better off fixing it earlier in the chain, especially since there is no defect on the original VHS (either different box, different transfer, and only if you have to - filter before deinterlacing or encoding to xvid)

This was check on RGB screenshot (so it might not be accurate), but it looks like the defect occurs only in U and V (you can check with utoy() or vtoy() ). Also, Y is clear (you can check with greyscale() ), so one way to treat it is to use a UV smoothed overlay to cover it up

Another way is to use a feathered mask with variable gradient opacity - so it blends in the rough transition edges. This is a single screenshot, so it's hard to tell, but on moving video you might see abrupt transition


e.g

WhateverSource()
ConvertToYV12() # if you are in YV12 already, you shouldn't need this, it's only for your screenshot example
main=last

main
crop(0,0,-480,0,true)
smoothuv(radius=5)
#tweak(sat=1, coring=false) #you may have to adjust the sat, depending on the strength of smoothing
leftoverlay=last

overlay(main, leftoverlay, opacity=1) 
#you can modulate the effect by changing the opacity of overlay. Eg. 0.9 would give 90%

[spiritgumm]

thanks. poison. I'll check out your suggestions. The strip stays in place. Upon closer inspection, it's possible it might be on the VHS, but it's so faint it's hard to detect.
I only have one "stabilizer" (ie copyguard remover).

[spiritgumm]

the overlay with Smoothuv(radius=7) worked best, but then I finally noticed the whole video had color noise. Applying Smoothuv over the whole picture improved everything (although hard to see in the resized video). Should have been using it long ago. Many thanks! That is, if this is an appropriate use for the plugin. I deinterlaced first in my tests, but should I use SmoothUV first instead?
I'm also unclear on how to interpret the results of SWAP (UToY and VToY).
Top is left-edge with smoothuv applied. Bottom is whole picture with smoothuv.

[poisondeathray]

As a general rule it's a bad idea to use such high smoothuv settings on the whole thing (too damaging) , small fine color detail and edges will be obliterated - color edges will become blurry and not sharp. But of course if the source is low resolution chroma to begin with you might not notice. On higher quality source you will definitely notice. There are other chroma smoothers/denoisers you can try as well

It doesn't matter what I think - It's your eyes

[jagabo]

If you have an all white shot (maybe even an all black shot) you can add the inverted chroma channels to the rest of the video to eliminate the consistent discolorations. I would average together several frames to eliminate random noise.

[spiritgumm]

I dont know how to implement jagabo's suggestion, and didnt have immediate good results trying some chroma denoisers so I'll postpone reencoding to dvd. For xvid, I used SmoothUV(Rad=5) over the whole picture, and added radius=2 to the overlay (as radius=7 worked best for the stripe). It's 29.97i, so I had to deinterlace to 29.97 for xvid.

Have a confusing PC playback question. The xvid plays with no problem on my old PC, and dvd player/TV.
On my newer PC (Win7 64 bit) it will only play normally using Windows Media Player; it plays slow using MPC and VLC, especially noticeable if you enlarge the player to full screen. Other xvids play fine. Seems to be this specific xvid with these players on the new PC. Is there a rendering or buffering setting I need to change? Sample attached.
sample.avi