Quantcast Avisynth DeVCR, how to use? - digitalFAQ Forum
  #1  
11-16-2020, 06:29 PM
geordie10 geordie10 is offline
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Hi everyone, hope your all well.

I am in the process of restoring a rare VHS rape that has come to my possession. I am by no means a professional but I have identified some flaws that some Avisynth scripts may be able to correct.

One flaw is the VCR lines at the bottom of the recording, as you will see in the sample. From my research, the Avisynth script DeVCR can potentially correct this. However, try as I might, I cannot get the script to work and there is very little troubleshooting online within forums to reference to.

Therefore, could someone please assist by providing the working .avs file and even a working script that I can use for this recording.

Some more recommendations for this sample would be highly appreciated.

Take care and stay safe!


Attached Files
File Type: avi Jackass.Pilot.Presentation.Raw.avi (69.48 MB, 13 downloads)
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  #2  
11-16-2020, 11:57 PM
Hushpower Hushpower is offline
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That's not a flaw, most VHS captures have this. It's Head Switching Noise.

Crop it.

Last edited by lordsmurf; 11-17-2020 at 05:55 AM. Reason: Don't crop.
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  #3  
11-17-2020, 05:31 AM
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lordsmurf lordsmurf is offline
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The is part of the overscan. Mask it, aka cover with black matte.
DO NOT CROP! Cropping screws up the interlacing, screws up the aspect ratio.

Every tape has head-switching noise, from the VCR. Some VCRs have narrowed noise than others, but it's always present.

This isn't a problem to be fixed. Just a caveat of the format to be understood.

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  #4  
11-17-2020, 05:49 AM
Hushpower Hushpower is offline
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LS, please remove my "Crop it" comment!

Although I will say that that is exactly what I do in my editor when exporting final.
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  #5  
11-17-2020, 06:00 AM
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lordsmurf lordsmurf is offline
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Quote:
Originally Posted by Hushpower View Post
LS, please remove my "Crop it" comment!
Although I will say that that is exactly what I do in my editor when exporting final.
Fixed.

There are times to crop, and times to not crop.
In general, masking is safe.
Cropping requires interlace and aspect ratio considerations, and is generally bad, often unneeded.

I've seen too many documentaries where cropped interlace was resized, and it becomes unwatchable. This also happens on the Cowboy Channel, all of the Lone Ranger re-runs are screwed up from interlaced crop+resize, left interlace mess on progressive feed.

I still see documentaries were an idiot editor loaded a 4:3 720x480 as 1:1 into a 1080p time, so the video was stretched badly. (For a novice, bad, learn to fix. For a professional editor, making a documentary broadcast on TV, hit him upside the head with book on video editing.)

The "I must fill the screen" mentality -- a really, really dumb mentality -- is what often drives the desire to crop needlessly. Stop it. Respect the source.

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  #6  
11-17-2020, 06:25 AM
Hushpower Hushpower is offline
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Quote:
The "I must fill the screen" mentality -- a really, really dumb mentality -- is what often drives the desire to crop needlessly.
Ouch! When I look at a Youtube video (or any video where there is no "TV Safe" area eg computer) and see the black fuzzy vertical edges and the bottom switching noise I think "that's slack". Fair enough getting all the capture in but it doesn't look neat. I do "cheat" and leave it all up to my editor to sort out re-sizing and cropping by dragging out the 4:3 bounding box and hitting "export" because I have read a lot on the cropping, resizing and interlace issues and developed a severe headache!
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  #7  
11-20-2020, 04:35 AM
geordie10 geordie10 is offline
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Thanks for the replies!
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  #8  
11-20-2020, 01:32 PM
latreche34 latreche34 is offline
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Cropping vertically before resizing for online sharing purposes only is okay, However the master files should never be vertically cropped or resized (with the exception of pro captures at 486 lines where the 6 lines must be cropped off).

The only mandatory horizontal crop by D1 standard to really get a perfect 4:3 aspect ratio is a horizontal crop from 720 to 704, Because the 4:3 aspect ratio was calculated based on the 704x480 (704x576) not 720 as a lot of people may think or not aware of, 16 black pixels added to the standard as safety margins after they found out that not all cameras imaging sensors start the scan at the same edge (this was not important back in the day because TV's had an overscan area, even cameras had those overscan lines marked in their viewfinder or monitor).

DV and DVD later on used the full 720 horizontal pixels but they took into consideration the extra 16 pixels to base their 4:3 aspect ratio.

I have proved this with just a consumer camcorder over at VH:
https://forum.videohelp.com/threads/...io#post2584522

Last edited by latreche34; 11-20-2020 at 01:40 PM. Reason: Added a link
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  #9  
11-20-2020, 04:05 PM
traal traal is offline
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So after capture:

1. Crop to 704x480.
2. Mask out the head switching noise and anything else that's distracting.
3. Encode with a PAR of 10:11 to achieve a DAR of 3:4.

This makes me glad I archive all my capture files!
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