Quantcast Panasonic AG-1980 head-switching noise on top of image? - digitalFAQ Forum
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  #1  
07-12-2015, 08:48 PM
premiumcapture premiumcapture is offline
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Perhaps hard to tell from the sample, but about 6 lines down, there is rainbow head-switching noise. Is it normal for the 1980 to show this on top? It should also be noted that the bottom noise is only 2-4 pixels. I have no issue cropping it out, just seems odd.

Thanks.



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File Type: png Switch Noise.png (430.4 KB, 180 downloads)
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  #2  
07-14-2015, 10:57 PM
NJRoadfan NJRoadfan is offline
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Well within the crop range, I wouldn't worry about it. Also, you have some obvious chroma ghosting, likely from the DNR circuit.
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  #3  
07-15-2015, 07:35 AM
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Quote:
Originally Posted by NJRoadfan View Post
Well within the crop range, I wouldn't worry about it. Also, you have some obvious chroma ghosting, likely from the DNR circuit.
Exactly my thoughts, I just figured I would ask as I'm not too familiar with this model's quirks. Yes, that would be the DNR, but I have come to find that even with this issue I haven't found any unit that produces as consistent good results as this. The only unit I have seen without the DNR ghosting is the JVC 9800, which when tracks well is easily my #1
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  #4  
07-15-2015, 02:40 PM
msgohan msgohan is offline
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So is this with all tapes played in this VCR?
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  #5  
07-15-2015, 04:55 PM
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Quote:
Originally Posted by msgohan View Post
So is this with all tapes played in this VCR?
No, it varies by tape and varies by section of the tape. I am convinced it is part of the tracking method it uses, but I haven't seen it reported before so I wanted to see if it was only this unit. Due to it being so close to the edge, it is tolerable.
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  #6  
04-09-2016, 07:10 AM
msgohan msgohan is offline
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Premiumcapture PM'd me the other day asking whether my SwitchHead function could be altered to work on the top of the image instead. I'm guessing it was related to the topic of this thread. (Note: As I allude to in the link, this still won't actually work properly with interlaced video, but for telecined animation like this it shouldn't cause problems.)

In theory the two functions (bottom and top) could be combined, but I can't bothered since this is a one-off.

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There is some random magenta at the top, but in the screenshot it's nearly invisible. Maybe you don't want to keep the original top color in the actual video itself.

Code:
ImageSource("Switch Noise.png").ConvertToYV24()

# Correct the bottom.
SwitchHead(2)

full = last

# Correct the top.
# This is inefficient (slow) and an ugly way to script this.

good = 3

full.Crop(0,good,-0,-0) # crop off "good" lines at the very top
SwitchHead_Top(1) # actual correction
StackVertical(full.Crop(0,0,-0,good),last) # stack the original "good" lines with the lower corrected lines



# SwitchHead v1.0
#
#   Parameters are number of discolored bottom-lines to correct, and the method to be used.
#
#   method = 0: grab N lines from above correction area, *reflect* them downward to fill correction area
#   method = 1: grab N lines from above correction area, *stretch* them downward to fill correction area
#   
#   Note: lines parameter must adhere to cropping requirements for the input pixel format (mod2 for YV12).
#
function SwitchHead(clip c, int lines, int "method") {
   method = Default(method,0)

   U = c.UtoY() # separate U channel
   V = c.VtoY() # separate V channel

   U = U.Crop(0,0,-0,-lines) # remove discolored portion
   extra1 = U.FlipVertical().Crop(0,0,-0,lines) # the last 'lines' pixels of the U channel *reflected*
   extra2 = U.Crop(0,U.height-lines,-0,-0).PointResize(U.width,lines) # the last 'lines' pixels of the U channel *stretched*
   U1 = StackVertical(U,extra1)
   U2 = StackVertical(U,extra2)

   V = V.Crop(0,0,-0,-lines) # remove discolored portion
   extra1 = V.FlipVertical().Crop(0,0,-0,lines) # the last 'lines' pixels of the V channel *reflected*
   extra2 = V.Crop(0,V.height-lines,-0,-0).PointResize(V.width,lines) # the last 'lines' pixels of the V channel *stretched*
   V1 = StackVertical(V,extra1)
   V2 = StackVertical(V,extra2)

   method == 0 ? YtoUV(U1,V1,c) : YtoUV(U2,V2,c) # mix the separate U and V with the original Y
}

# SwitchHead_Top v1.0
#
#   Parameters are number of discolored top-lines to correct, and the method to be used.
#
#   See SwitchHead for more info...
#
function SwitchHead_Top(clip c, int lines, int "method") {
   method = Default(method,0)
   
   U = c.UtoY() # separate U channel
   V = c.VtoY() # separate V channel
   
   U = U.Crop(0,lines,-0,-0) # remove discolored portion
   extra1 = U.Crop(0,0,-0,lines).FlipVertical() # the first 'lines' pixels of the U channel *reflected*
   extra2 = U.Crop(0,0,-0,lines).PointResize(U.width,lines) # the first 'lines' pixels of the U channel *stretched*
   U1 = StackVertical(U,extra1)
   U2 = StackVertical(U,extra2)
   
   V = V.Crop(0,lines,-0,-0) # remove discolored portion
   extra1 = V.Crop(0,0,-0,lines).FlipVertical() # the first 'lines' pixels of the V channel *reflected*
   extra2 = V.Crop(0,0,-0,lines).PointResize(V.width,lines) # the first 'lines' pixels of the V channel *stretched*
   V1 = StackVertical(V,extra1)
   V2 = StackVertical(V,extra2)
   
   method == 0 ? YtoUV(U1,V1,c) : YtoUV(U2,V2,c) # mix the separate U and V with the original Y
}


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File Type: png Switch Noise - better color.png (446.1 KB, 117 downloads)

Last edited by msgohan; 04-09-2016 at 07:28 AM.
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  #7  
04-09-2016, 10:56 AM
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Exactly what I was looking for - thanks a lot!

I noticed it still treated the bottom - is it running the method twice in different places?

Also, what do you recommend as a chain - looks like I could probably detelecine here and apply it, but for straight 59.97i, does QTGMC followed by this sound right?

Thanks again
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04-09-2016, 03:02 PM
msgohan msgohan is offline
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The script is included in the post, including comments identifying each stage of processing. Yes, I ran it on the bottom two lines in addition to the separate top pass.

You don't need to deinterlace for proper interlaced handling in this case. You can SeparateFields, run the filter, then Weave. I was intending to include that as part of the function, but thinking about it, things would get confusing when you're looking at the full interlaced frame and wanting to correct an odd number of lines. I think advising the user to Separate and Weave is preferable.
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  #9  
04-10-2016, 09:18 PM
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Quote:
Originally Posted by msgohan View Post
The script is included in the post, including comments identifying each stage of processing. Yes, I ran it on the bottom two lines in addition to the separate top pass.

You don't need to deinterlace for proper interlaced handling in this case. You can SeparateFields, run the filter, then Weave. I was intending to include that as part of the function, but thinking about it, things would get confusing when you're looking at the full interlaced frame and wanting to correct an odd number of lines. I think advising the user to Separate and Weave is preferable.
Got it, thanks!

As someone who doesnt pull AviSynth scripts from forums all that often, I am having difficulty actually copying this and keeping the formatting. I am not sure that it even affects how it runs, but notepad and wordpad seem to hate it, which I have traditionally used for scripting. Is there a best way to copy this?
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  #10  
04-10-2016, 09:47 PM
msgohan msgohan is offline
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Well that's certainly annoying. I think it's an interaction between the CODE tag and the Javascript that adds the "Read more" link to the end of all copy-pastes.

In future, you can work around this by hitting the QUOTE button and then copying from the reply text box. This bypasses the Javascript. I didn't save the script file, so I used this workaround to re-post it on Pastebin for you.
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  #11  
04-24-2016, 11:49 PM
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Chroma offset and chroma noise is partially to blame here.

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04-26-2016, 03:54 PM
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Quote:
Originally Posted by lordsmurf View Post
Chroma offset and chroma noise is partially to blame here.
I could be mistaken, but I believe this is how the Panasonic tracks this tape as well as some others. This was played using a TGrant machine.
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  #13  
05-30-2017, 03:03 PM
msgohan msgohan is offline
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Having experienced this myself now, I can say that it's indeed related to head-switching noise.

For some reason, the AG-1980 outputs this chroma error at the top of the image when the head-switching point is set "too low". The error can be removed by adjusting a potentiometer to raise the switching point higher into the bottom of the frame. But then of course, you will see more skewed lines at the bottom.

In theory, for particularly important content, you could do two captures and combine them:
  1. no head-switching noise at the bottom but chroma errors near the top
  2. head-switching skew and chroma errors at the bottom but clear top

I'll try this later.
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  #14  
06-01-2017, 04:13 AM
Quasipal Quasipal is offline
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Why not just adjust the PG Shifter pot viewing the image on a display showing the overscan? I usually have to set up any VCR I buy as the PG is always to high or low. Saying that you can actually adjust the PG for each tape so you won't have to crop any of the image. The position is not always the same as it depends on the setup of the recording VCR.
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06-01-2017, 08:34 AM
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With some of my recordings, it seems that no position of PG Shifter can keep both the top and bottom of the image clear in the case of the AG-1980.

With the Panasonic PV-S4670, I also just noticed that the top 10-15 lines of the image are very slightly brightened in the cap where I removed the noise from the bottom. Whereas they are correct in the cap with HSW noise where PG SHIFT was at its original position. But it's possible there is a good position for that one. I haven't tried since noticing this artifact. Very subtle.

Do you know specifically why it varies based on the recording VCR? Is it due to the recording VCR's PG adjustment?
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06-01-2017, 10:07 AM
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Quote:
Originally Posted by msgohan View Post
With some of my recordings, it seems that no position of PG Shifter can keep both the top and bottom of the image clear in the case of the AG-1980.

With the Panasonic PV-S4670, I also just noticed that the top 10-15 lines of the image are very slightly brightened in the cap where I removed the noise from the bottom. Whereas they are correct in the cap with HSW noise where PG SHIFT was at its original position. But it's possible there is a good position for that one. I haven't tried since noticing this artifact. Very subtle.

Do you know specifically why it varies based on the recording VCR? Is it due to the recording VCR's PG adjustment?
Yes, the setting of the PG in the record VCR dictates where it appears in the picture when using another VCR. Playing back on the recording VCR never shows this but when the record VCR has PG too low, it can appear outside the overscan when played on other VCR's with correct PG.

I don't know about AG1980, nothing like that in PAL region - but on my Panasonic F70 I can shift the PG out of the visible image most times. I have added an external pot with knob and flying leads so I can adjust without taking the lid off.
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  #17  
06-01-2017, 08:12 PM
msgohan msgohan is offline
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Quote:
Originally Posted by Quasipal View Post
I don't know about AG1980, nothing like that in PAL region - but on my Panasonic F70 I can shift the PG out of the visible image most times. I have added an external pot with knob and flying leads so I can adjust without taking the lid off.
NV-FS200 is PAL AG-1980.

Can you provide any more info on your mod? The AG-1980 trimpot is actually on the bottom because the mainboard is mounted upside-down. Very awkward to adjust. Would be nice to have it externally controllable.
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  #18  
06-02-2017, 08:38 AM
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Quote:
Originally Posted by msgohan View Post
NV-FS200 is PAL AG-1980.

Can you provide any more info on your mod? The AG-1980 trimpot is actually on the bottom because the mainboard is mounted upside-down. Very awkward to adjust. Would be nice to have it externally controllable.
Is the NV-FS200 really related to PAL AG-1980? Seems to be quite a few obvious differences:

FS200 G Deck, AG-1980 K deck (huge mechanical difference)
FS200 does not have regular capacitor issues, AG-1980 has on almost all units. FS200 has no SMD caps.
Internal PCB's are completely different shape.
FS200 has different front panel controls and layout to AG-1980 (AG-1980 is closer to FS100)
FS200 is from 1992, AG-1980 is from 1995
FS200 has very different remote with jog and shuttle built in and supplied with barcode reader

I will share how I did my mod, but really need to tidy up the work so as it looks good enough to share here - looks a bit scrappy at the mo!
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  #19  
06-02-2017, 09:03 AM
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Quote:
Originally Posted by Quasipal View Post
Is the NV-FS200 really related to PAL AG-1980? Seems to be quite a few obvious differences:
The NV-FS200 is comparable to the AG-1980P is performance.

But so is the NV-HS1000. Is that one more mechanically comparable to the AG-1980?

I've never had a chance to own these. My informatino on PAL Panasonics comes from several knowledgeable peers. My hands-on PAL is with non-SVHS Panasonics (mostly worldwides) and JVC S-VHS models. So I will defer to you on this exact subject.

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06-02-2017, 09:34 AM
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Quote:
Originally Posted by lordsmurf View Post
The NV-FS200 is comparable to the AG-1980P is performance.

But so is the NV-HS1000. Is that one more mechanically comparable to the AG-1980?

I've never had a chance to own these. My informatino on PAL Panasonics comes from several knowledgeable peers. My hands-on PAL is with non-SVHS Panasonics (mostly worldwides) and JVC S-VHS models. So I will defer to you on this exact subject.
HS1000 is same mechanics as AG-1980 but again different inside - all IC's, less components.

Someone with both PAL and NTSC units needs to do a proper evaluation, find out what is what, but that would not help with converting old tapes to digital so it would just be a by-the-way.

HS1000 is different to FS200 (I have both). FS200 is more 'old fashioned' in its image, less cleaning, but has the better mechanism with brass impedance roller - the HS1000 is less tolerant of worn tapes.

Anyone in PAL area have an AG-1980 and FS200 to compare?
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