Green Flicker

[ChrisNicols]

I've started noticing a weird green flickering artifact at the top of my Betacam tapes. At first I thought it was just a series of tapes with a unique tracking problem. I ran it through a different Betacam machine and didn't see the flickering green artifact anymore, so now I'm starting to worry my Sony Betacam UVW-1800 is dying. I'm a little doubtful of that, though, because this green flicker doesn't show up on all tapes in that machine and only appeared recently.

I've tried thoroughly cleaning the video head with both a cotton swab and static/lint free wipes with isopropyl alcohol, but there doesn't seem to be any difference. I am including some examples of the flicker.

[kieranjol]

Looks like it could be a tbc error,but that's usually straight lines,yours looks like quite a distinctive pattern. We have the same deck and I haven't seen it show up.could you share a video in the original encoding of the error with a few frames either side?I'd love to see it in qctools..

[ChrisNicols]

This is probably not the best way to do it, but below is a 30 second video of it. The flicker isn't something that shows up for 15 seconds and then disappears, its always present.
Here is the QCTools report on the 30 second video. Green_TEST.mov.qctools.xml.gz

https://www.youtube.com/watch?v=ptogAuUHlq4&feature=youtu.be

[kieranjol]

Thanks for sharing! I won't really be able to help any further, but it would be great if you could share an uncompressed/lossless version of that clip on the internet archive. I think even two or three seconds would suffice. I'd still like to investigate it further, and more knowledgeable people than me could have better insight with a higher res clip. I'd like to see the original interlaced version and some extra detail in the chroma channels rather than the 4:2:0 youtube version.

…

On Wed, Jun 6, 2018 at 8:20 PM, ChrisNicols ***@***.***> wrote: This is probably not the best way to do it, but here is a 30 second video of it. The flicker isn't something that shows up for 15 seconds and then disappears, its always present. https://www.youtube.com/watch?v=ptogAuUHlq4&feature=youtu.be — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#200 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABEyvhByhCDhN0ggUe_-WqT1jwZIdD-Aks5t6Ct9gaJpZM4UdNKw> .

[ablwr]

Aliens 👽

[kieranjol]

Ah,only seeing the qctools report in your edited comment now.

[ChrisNicols]

I will upload the video tomorrow. Its taking a long while to upload to the Internet Archive

[michaelangeletti]

Hi, everybody. Chris, does it only happen with a series of tapes from a certain collection, or does it happen randomly with tapes that are from different collections, recorded in different machines? Because of the location and color of the artifact, I would guess that this could be due to a difference in mechanical alignment between the machine that recorded the tape and your UVW-1800. It looks like the tape might not be making good/even contact with the video drum after it passes the entrance guide. I usually associate that type of muted green flickering artifact in Betacam playback with an error that is not fully correctable by the integrated TBC, as opposed to a recorded-in-souce problem or a physical tape defect (more saturated green can show up even with small head clogs and dropout in Betacam, though). If this isn’t happening in other Betacam machines with the same tapes, you might want to have an alignment check on your 1800. - Michael A. On Jun 6, 2018, at 12:35 PM, kieranjol <notifications@github.com<mailto:notifications@github.com>> wrote: Thanks for sharing! I won't really be able to help any further, but it would be great if you could share an uncompressed/lossless version of that clip on the internet archive. I think even two or three seconds would suffice. I'd still like to investigate it further, and more knowledgeable people than me could have better insight with a higher res clip. I'd like to see the original interlaced version and some extra detail in the chroma channels rather than the 4:2:0 youtube version.

On Wed, Jun 6, 2018 at 8:20 PM, ChrisNicols ***@***.******@***.***>> wrote: This is probably not the best way to do it, but here is a 30 second video of it. The flicker isn't something that shows up for 15 seconds and then disappears, its always present. https://www.youtube.com/watch?v=ptogAuUHlq4&feature=youtu.be — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#200 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABEyvhByhCDhN0ggUe_-WqT1jwZIdD-Aks5t6Ct9gaJpZM4UdNKw> .

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#200 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/AIZAni6ZFFf-c3y3SOdCzYCJ2xqv1Lakks5t6C8TgaJpZM4UdNKw>.

[ChrisNicols]

Thanks, Michael. I will get to a more detailed response tomorrow, but I'm just about to leave for the day. In the mean time, here is a link to the video file itself:
https://archive.org/download/GreenTEST

[ablwr]

@ChrisNicols can you add this error to the AVAA? 😺

[ChrisNicols]

Michael,

Thank you for your detailed response. I have digitized around 50 tapes on this particular UVW-1800 and only started seeing the problem with this most recent set of tapes. When I go back and play old tapes I know worked, the green flicker issue does not occur. I would think it must be the tapes then, but for two things: 1. When played through another UVW-1800, the green flicker issue does not manifest, and 2. Some of the tapes from the same collection or set do not exhibit the green flicker issue.

I am reluctant to trust the results of the second UVW-1800 because it is also experiencing some unrelated issues on every tape, exhibiting drop out on tapes that I know do not suffer from dropout. I tried running the first UVW-1800 through my DPS-290 after turning off the internal TBC, but there doesn't seem to be any improvement.

I agree that generally, it seems like the tapes are not making full contact with the video head. At the very beginning of some of these tapes, the green flicker dips down even further in the picture and the color information is lost on the upper third of the screen for a second or two. The green flicker does not seem to be consistent in shape.

I'm afraid I don't know which tapes were recorded in which machines. The only provenance I have is from the holding repository. The tapes have been stored in poor conditions for the last 20 years- 60-70F and 60-70% RH, with fluctuations in the summer months of 20-70% RH every day/night cycle. I have seen a lot of skew errors on other tapes all going off to the left, so I'm worried that the tapes have deformed over time and thats just made some special conditions with these tapes even worse.

If its just this selection of tapes, then I guess what I need to do is fix the dropout issue with my second Betacam machine and just capture these tapes in that one, since its alignment doesn't seem to have a problem. I've cleaned the head with static/lint free wipes and cotton swabs as much as I can, but there's still no difference or reduction in dropout. Sometimes, the little dropout flickers actually look almost like that green flicker- like its not quite flush with the video head. This flicker is at a different part of the screen, though, it doesn't look like its part of some larger, descending problem.

[ChrisNicols]

@ablwr I will add the error this afternoon.

EDIT: Actually, on second thought, I will wait until I've gathered more info. I dont want to create redundant articles if its a pre-existing issue.

[ablwr]

😺 😺 😺

[ChrisNicols]

Should I start a new entry about Head Misalignment?

[ablwr]

HELL YEA

[ChrisNicols]

Actually, just as a follow up, does anyone know how to access the tracking control function of a UVW-1800 Sony Betacam machine? Someone suggested it might help with the problem.