Quantcast Working with color bars on old tapes? - digitalFAQ Forum
  #1  
11-21-2017, 12:45 PM
koberulz koberulz is online now
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One of the tapes I'm working on was kind enough to cut to this:
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Is there a way I can use this? I know what's supposed to go where on a vectorscope, at least for the most part, but I'm not sure how to go about getting it there.


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  #2  
11-21-2017, 01:51 PM
NJRoadfan NJRoadfan is offline
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In a studio setting, normally you would have a waveform monitor and vectorscope attached to the video deck along with a proc amp to adjust the output. I wouldn't trust the color bars on most tapes produced by anything less then a broadcast studio (high schools, etc). Many times they just recorded the bars and tone off their main video switcher because "thats the procedure", but didn't actually calibrate their equipment!
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  #3  
11-22-2017, 08:00 AM
koberulz koberulz is online now
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It is from a TV broadcast.

There are three camera angles with wildly different colors, so I was hoping to use the color bars to try and hit a reasonable middle point.
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12-04-2017, 06:51 AM
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You assume the color bar was calibrated. Don't. As NJRoadfan said.

TV broadcast means nothing. Cable and broadcast operators were sometimes extremely sloppy, so it depends on whether you know for sure that the facility was being run correctly. Just a pattern non a tape means little.

For fun, sure, you can scope it. But do not trust it if it looks wonky. Odds are the pattern is nonsense.

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12-05-2017, 05:16 AM
koberulz koberulz is online now
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Well the whole picture looks wonky at the moment.

If the tools exist to drag each of the points involved to the correct spot on a vectorscope, I see no reason not to give it a shot. Worst-case I spend half an hour and make it differently awful, discard the results and start over. Best-case it magically fixes everything. Anywhere in the middle could be helpful at least as a frame of reference.
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12-05-2017, 07:33 AM
dpalomaki dpalomaki is offline
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Bars and tone, if they were accurate, can give you an idea what the record/play cycle in the VCRs (and as applicable your capture device) did to the original signal fed to the recorder, but they tell you nothing about how accurate the colors were in the program material fed to the recorder. From your initial post it sounds as though at least 2 if not all 3 of the cameras used were not accurate.

FWIW: bars provided by consumer/prosumer gear (e.g., video mixers, signal generators, camcorders, etc.) are hit or miss. Some are quite close to spec, others are not.

Waveform and Vector scope software is available (and built into many NLEs) that can let you see what is going on in the the captured file. You could use a proc amp ahead of the capture device to to adjust the signal to put the captured bars to correct levels/phase. Assuming the bars fed to the recorder were reasonably accurate, the original program signal was well behaved and within the VCRs' limits, and the VCRs did not exercise their own creativity with the signal, that could give you a capture that is close to the original signal fed to the recorder.

Good luck and enjoy.
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12-05-2017, 01:00 PM
NJRoadfan NJRoadfan is offline
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I just noticed this is a PAL capture. In theory, PAL broadcasts and recordings shouldn't need hue adjustments (the whole point of color bars and a vectorscope) due to how the color encoding system works. If the various cameras are wildly different in color, its likely they were not white balanced before recording began. Professional cameras require manual white balance and that is usually done with someone holding up a white card in the room under the current lighting. All the camera operators are supposed to fill their viewfinder with the white card and hit the "balance" button on their camera or remote control unit (usually in the control room).
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  #8  
12-06-2017, 02:19 AM
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Quote:
Originally Posted by NJRoadfan View Post
I just noticed this is a PAL capture. In theory, PAL broadcasts and recordings shouldn't need hue adjustments (the whole point of color bars and a vectorscope)
I overlook that too.

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  #9  
12-06-2017, 06:30 AM
sanlyn sanlyn is offline
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From previous posts it also appears that most of the tapes are multigeneration tape dubs.
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