Quantcast Horizontal chroma noise? - digitalFAQ Forum
01-17-2021, 04:48 AM
lupin981 lupin981 is offline
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Hi, I'm doing some testing with various workflows.
This video is acquired starting from a commercial vhs, a documentary. Losslessy Huffyuv avi.
Panasonic NV-FS200 -> PC with Ati AIW 9000
Connecting via Y/C S-Video cable I see these intermittent horizontal pink lines even before capture. If I connect in composite they are not seen ...
The cables and connectors are clean and tight. It doesn't look like a bad cable. I also tried to change the video source, connecting a digital terrestrial decoder on the fly (which does not come out natively in S-video), obviously I see the video in black and white but always with those intermittent lines. Same thing, with the composite no lines..
Have you had any cases similar to this?

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File Type: avi Pink_stripes.avi (59.74 MB, 13 downloads)
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01-17-2021, 12:08 PM
latreche34 latreche34 is online now
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It's most likely a faulty VCR. I've seen this artifact on camcorders and the caps are the culprit.
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01-17-2021, 03:04 PM
lupin981 lupin981 is offline
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I would exclude it because in composite it doesn't, and for safety I also changed source, with a DVB-T it does the same thing.
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01-17-2021, 03:11 PM
latreche34 latreche34 is online now
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I quite don't understand your problem, samples from different sources may give us an idea, I know for a fact that analog video is interlaced, so the appearance of alternating lines is normal.
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01-17-2021, 04:13 PM
lupin981 lupin981 is offline
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It's not interlacing, I mean the pink lines that appear intermittent on the video. I noticed that they are visible on 2 consecutive frames, alternating with 2 clean frames

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File Type: png Noise.png (282.3 KB, 9 downloads)
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01-17-2021, 05:10 PM
themaster1 themaster1 is offline
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Might be a YUY2 vs Yv12 mismatch. You have captured the video as YUY2 huffyuv yet it seems to be YV12 because when i convert it with avisynth the bars disapears

There is something else strange (perhaps related) the colors (on the water for example) seem to vary from frame to frame

last edit:
I found the trick, spotlessUV (the new version from Stainless)


ue_chroma = UToY(ev).SpotLessUV()
ve_chroma = VToY(ev).SpotLessUV()
YToUV(ue_chroma, ve_chroma)
uo_chroma = UToY(od).SpotLessUV()
vo_chroma = VToY(od).SpotLessUV()
YToUV(uo_chroma, vo_chroma)

Function SpotLessUV(clip c,int "RadT",int "ThSAD",int "ThSAD2",int "pel",bool "chroma", int "BlkSz",Int "Olap",bool "tm",Bool "glob",Float "bBlur") {
myName = "SpotLess: "
RadT = Default(RadT,1) # Temporal radius. (MCompensate arg)
ThSAD = Default(ThSAD,10000) # SAD threshold at radius 1 (Default Nearly OFF).
ThSAD2 = Default(ThSAD2,ThSAD) # SAD threshold at radius RadT.
Pel = Default(pel,2) # Default 2. 1, 2, or 4. Maybe set 1 for HD+. (1=precision to pixel, 2=precision to half pixel, 4=quarter pixel)
Chroma = Default(chroma,True) # MAnalyse chroma arg. If set to true, use chroma in block matching.
BlkSz = Default(BlkSz,8) # Default 8. MAnalyse BlkSize. Bigger blksz quicker and perhaps better, esp for HD clips. Maybe also better where BIG noise.
OLap = Default(OLap, BlkSz/2) # Default half of BlkSz.
Tm = Default(tm,True) # TrueMotion, Some folk swear MAnalyse(truemotion=false) is better.
Glob = Default(glob,True) # Default True, Allow set MAnalyse(global) independently of TrueMotion.
Bblur = Default(bblur,0.0) # Default OFF
Assert(1 <= RadT,myName + " 1 <= RadT")
Assert(0.0 <= bblur <= 1.58, myName + "0.0 <= bblur <= 1.58")
Assert(pel==1 || pel==2 || pel==4, myName + "pel==1 || pel==2 || pel==4")
pad = max(BlkSz,8)
sup = (bBlur<=0.0 ? c : c.blur(bblur)).MSuper(hpad=pad,vpad=pad,pel=pel,sh arp=2)
sup_rend = (bBlur<=0.0) ? sup : c.MSuper(hpad=pad,vpad=pad,pel=pel,sharp=2,levels= 1) # Only 1 Level required where not MAnalyse-ing.
MultiVec = sup.MAnalyse(multi=true, delta=RadT,blksize=BlkSz,overlap=OLap,chroma=Chrom a,truemotion=Tm,global=Glob)
c.MCompensate(sup_rend, MultiVec, tr=RadT, thSad=ThSAD, thSad2=ThSAD2)
MedianBlurTemporal(radiusY=0,radiusU=0,radiusV=0,t emporalradius=RadT) # Temporal median blur only [not spatial]
SelectEvery(RadT*2+1,RadT) # Return middle frame
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01-17-2021, 05:42 PM
lupin981 lupin981 is offline
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I investigate in this sense, however to clarify as soon as I am in capture mode in virtualdub I already see the intermittent colored lines. If I connect in composite they are not there. I took another test. I added a panasonic ES15 in the middle (connected all in Y/C) and it manages to remove them.
With this avisynth function can I remove it? Is there a default function or should it be added? Thanks for now
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