Quantcast Color flickering on deinterlaced VHS capture? - digitalFAQ Forum
  #1  
02-13-2021, 08:57 AM
thunderbirds93 thunderbirds93 is offline
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Hi,

I tried using QTGMC to deinterlace this VHS capture only to find that I'm getting flickering colors.

The video seems to have the correct colors on the odd-frames, and distorted colors on the even-frames.

Does anyone know what's causing this and if it can be fixed?

Could it have something to do with the VHS being PAL? I don't know myself, but I hope someone does

Here is the .avs script I used:
Code:
AVISource("Original.avi")
AssumeTFF()
ConverttoYV12(interlaced=true)
QTGMC(preset="medium", FPSDivisor=2)
MCTemporalDenoise(settings="low")

The tape is also a bit noisy, and I'm wondering if there are any ways to improve that. I'm new to Avisynth, so apologies for the very basic script.

Attached images show the color flicker between alternating frames.

Attached videos below are:
1. The original interlaced file
2. QTGMC deinterlaced clip

I hope someone knows what's going wrong - I have a feeling it might be my VCR


Thanks so much for reading all this,
Michael


Attached Images
File Type: jpg Image 1.jpg (121.4 KB, 16 downloads)
File Type: jpg Image 2.jpg (113.3 KB, 13 downloads)
File Type: jpg Image 3.jpg (113.1 KB, 9 downloads)
File Type: jpg Image 4.jpg (126.8 KB, 7 downloads)
Attached Files
File Type: avi Original.avi (95.79 MB, 17 downloads)
File Type: avi QTGMC Deinterlace.avi (85.46 MB, 13 downloads)
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  #2  
02-13-2021, 12:02 PM
themaster1 themaster1 is offline
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Have a look at the script i've posted in the topic below, that should do it
Horizontal chroma noise?
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  #3  
02-13-2021, 08:55 PM
thunderbirds93 thunderbirds93 is offline
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Hi,

Thanks so much for that script. I tried it on the clip and it removed a lot of the flickering.

Although there is still some remaining color flicker. I don't know if that can be fixed or not - can it?


I've attached images below to show the color flickering.

I've also attached the video after using your amazing script!

Thanks,
Michael


Attached Images
File Type: jpg Image 1.jpg (121.4 KB, 11 downloads)
File Type: jpg Image 2.jpg (113.3 KB, 5 downloads)
File Type: jpg Image 3.jpg (113.1 KB, 5 downloads)
File Type: jpg Image 4.jpg (126.8 KB, 4 downloads)
Attached Files
File Type: avi Horizontal Chroma Noise Script.avi (84.64 MB, 17 downloads)
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  #4  
02-15-2021, 12:33 PM
themaster1 themaster1 is offline
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Try this then instead (with ttempsmooth filter it does a better job for your video it seems) you can tweak the settings like maxr and strength but careful, it can remove deep reds easily.

Quote:
AVISource("Horizontal Chroma Noise Script.avi")
assumetff()
converttoyv12(interlaced=true)

ConvertToYV16(interlaced=true)
orig=last
ev=orig.assumetff().separatefields().selecteven()
od=orig.assumetff().separatefields().selectodd()
ev
ue_chroma = UToY(ev).ttempsmooth(maxr=6,lthresh=150, strength=6)
ve_chroma = VToY(ev).ttempsmooth(maxr=6,lthresh=150, strength=6)
YToUV(ue_chroma, ve_chroma)
MergeLuma(ev)
ev_filtered=last
od
uo_chroma = UToY(od).ttempsmooth(maxr=6,lthresh=150, strength=6)
vo_chroma = VToY(od).ttempsmooth(maxr=6,lthresh=150, strength=6)
YToUV(uo_chroma, vo_chroma)
MergeLuma(od)
od_filtered=last
interleave(ev_filtered,od_filtered)
assumefieldbased().assumetff().weave()
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  #5  
02-20-2021, 09:44 PM
Spellbinder_Jack Spellbinder_Jack is offline
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I faced the same issue. I was using Panasonic MV-FS200 (which was thought to be the issue in another topic), but it seems like those lines were on a tape before (at least on my old captures i can see pink tint on some surfaces as well).

I took a closer look at interlaced footage and noticed pink lines are at odd fields, and they present all the time, just their intensity can change frame by frame. After deinterlacing (with QTGMC) they look like pink flicker (shimmer) when one frame is ok, and next one has a strong pink tint to it.

I did test the script, provided by themaster1, it made those lines kinda more blurry, but they are still there.

I'm attaching a piece of original capture, where its best seen (look at white walls). I noticed slight pink shimmer after deinterlacing on other captures (also noticed it on wall surface), but it wasn't that strong as on this capture. Also attaching processed capture, and a screenshot of close up of those lines (i added contrast and hue to make them more visible to the part of screenshot).

I'm using Edius NX for capture.

Referenced here: Horizontal chroma noise?

If you need a recorder with LSI chip to get rid of those lines, which ones has a pass through ability, without affecting picture quality much(like ES10) ?

Test captures and screenshot is here: https://1drv.ms/u/s!Am87w74ZKuE2jJdG...ydWJw?e=ixnzSI
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  #6  
02-21-2021, 07:51 AM
hodgey hodgey is online now
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The noise filtering in the LSI logic chips is only active when encoding to mpeg2 as far as I know. At least on any of the PAL ones I've used. The Video decoder chip is separate from the LSI system/mpeg2 chip, and varies between models. Not aware of any LSI-based ones that use one that can stabilize jitter like panasonic chips can either. Some use Philips/NXP chips which are good at not loosing sync, but do little horizontal correction, the jvc ones use some custom jvc chip which also does some mild jitter correction, and some use TI chips that dont handle unstable video well at all.

If it's some signal issue rather I suppose it's possible that a different A/D chip would be able to reduce it, but it depends on the source.
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  #7  
02-22-2021, 04:08 AM
Spellbinder_Jack Spellbinder_Jack is offline
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I made some research, and found a possible solution. It was suggested to try loading video using DirectShowSource, i was using FFMPEGSource2, and did try AVIsource, both gave me flickering after QTGMC. DirectShowSource didn't give me flickering, at least wasn't noticeable by eye.

Regarding pink scanlines, they are written on tape and not a part of a playback problem as far as i can tell. They appear on some surfaces for me (like walls or sky), that pink hue is sometimes very noticeable, and that i would correct later.
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avisynth, qtgmc, restoration, vhs, virtualdub

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