Quantcast Horizontal chroma noise? - digitalFAQ Forum
  #1  
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?
thanks


Attached Files
File Type: avi Pink_stripes.avi (59.74 MB, 13 downloads)
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  #2  
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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  #3  
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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  #4  
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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  #5  
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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  #6  
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)

Quote:
AVISource("Pink_stripes.avi")
assumetff()

ConvertToYV16(interlaced=true)
orig=last
ev=orig.assumetff().separatefields().selecteven()
od=orig.assumetff().separatefields().selectodd()
ev
ue_chroma = UToY(ev).SpotLessUV()
ve_chroma = VToY(ev).SpotLessUV()
YToUV(ue_chroma, ve_chroma)
MergeLuma(ev)
ev_filtered=last
od
uo_chroma = UToY(od).SpotLessUV()
vo_chroma = VToY(od).SpotLessUV()
YToUV(uo_chroma, vo_chroma)
MergeLuma(od)
od_filtered=last
interleave(ev_filtered,od_filtered)
assumefieldbased().assumetff().weave()
converttoyv12(interlaced=true)

qtgmc("fast")
selecteven()
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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  #7  
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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