How to remove or smooth away tape header noise with Avisynth?

[VideoFanatic]

Here's a short sample MPEG2.

Normally the noise is at the very bottom of the video and I can just crop 12 pixels off the bottom of the video. However with this video it's taking up quite a lot of room. What's also annoying is that I can still see a good picture below the header noise! So I don't want to crop all that away as I would lose a lot of the picture.

Is there any way I can remove the noise without cropping it away. If not, can I smooth it out so it's less noticeable?

[sanlyn]

That's not tape header noise. THN is an audible signal recorded onto the leader portion of some (not all) video tapes. What you see in the bottom portion of the frame is a combination of tape damage (likely from one of those cheap $20 auto-winders, aka "auto tape destruction toy") and tracking distortion. The bottom 8 pixels are head-switchiong noise.

The damage appears to start at line 366 or so, is worse at line 400 to 454, is distorted by tracking problems below that. There is no "good picture" in the bottom of the frame. The area below the worst of the damage is distorted and discolored, worse in some spots than others. A part of the streaky nature of this kind of distortion has been partially smoothed by whatever line-tbc circuit was in effect when this tape was digitized -- probably in a camera. DVD recorder, or capture card with tbc device.



All you can do is blur or mask the area. Blurring might look rather weird IMO and could be even more distracting. You could mask with a bright-letters-on-dark overlay that has a message such a tape name, event, etc., in a banner stryle. You can smooth the heck out of it, but smoothing to that extent would be the same as blurring. The noise might also just be plain tracking error instead of winder damage, but it seems to me that tracking error would look much worse. With physical damage, there will always be some sort tracking error component anyway, because the machine would literally have difficulty tracking the damaged area. Looks like damage to me because its location and width doesn't change.

[VideoFanatic]

Thanks. I don't want to put a message over it so it seems the only solution is too blur/smooth it unless you have any other suggestions? Could you please suggest a script that would smooth it away?

[sanlyn]

I don't think smooth or blur will buy much. There are many ways to blue and overlay:

MPEG2SOurce("I:\forum\smackdown\Tape Noise Smackdown 14 2000.d2v")

Crop(16,4,-4,-8) 
vcrop=last
vcrop2=vcrop

vcrop2 
GaussianBlur(varY=16.0,varC=16)
GaussianBlur(varY=16.0,varC=16)
GaussianBlur(varY=32.0,varC=32)
Crop(0,396,0,0)
vblur=last
b=Overlay(vcrop,vblur,x=0,y=396).ColorYUV(off_y=-16).AddBorders(10,6,10,6)
return b

result:



Or you can try faking it:

MPEG2SOurce("I:\forum\smackdown\Tape Noise Smackdown 14 2000.d2v")

Crop(16,4,-4,-86)
ColorYUV(off_y=-18)
AddBorders(10,46,10,44)

Someone more knowledgeable might have better ideas.