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Old February 24th, 2010, 08:29 AM   #1
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Black levels for video (0 IRE and 7.5 IRE)

I stumbled across this 5 minnute tutorial by JVC and it's made me think ... which I am not sure that I really like to have to do.

Have a look at http://pro.jvc.com/pro/attributes/pr...p/JVC_DEMO.swf

The question is ... is this still and issue and how exactly can we tell if the black levels issue is going to bite us?

Andrew
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Old February 25th, 2010, 12:12 PM   #2
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Both questions are fully answered right there in the tutorial. Yes, this is an issue and will bite you if you don't pay attention.

How can you tell? Easy - look at your scopes in the NLE.
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Old February 25th, 2010, 01:32 PM   #3
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IF you stay purely digital you don't have to worry. All digital is effectively 0 IRE. You still do have to manage the levels though as it is all too easy with colour correction etc to exceed the levels at both top and bottom making even the digital signal invalid. If you use the current set of consumer or Prosumer cameras they will all be set at 0 IRE. If you then edit and make DVD's or Bluray's then you need to stay at 0 IRE ( its really 16 as the tutorial says ). But you need to ensure that the range of your NLE output is still correct after colour correcting etc so you will need to use the Scopes in the NLE to make sure the final output is within digital 16 to 235 range.
IF you are going to record to or from analogue tape then you do have to manage the levels. Just as described in the tutorial.

Ron Evans
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Old February 26th, 2010, 02:44 AM   #4
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I suppose what I was really asking was .... is this an old tutorial/issue and has the issue been corrected by manufacturers in the meantime?

Andrew
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Old February 26th, 2010, 08:36 AM   #5
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The issue is real today. Meaning if you use analogue tape or broadcast in North America you will have these issues. It has nothing to do with manufacturers product ( unless you mean the 7.5 setup switches on cameras). These are broadcast analogue specs for NTSC North America. Not true for digital as noted in tutorial etc. IF you shoot digital and stay digital then there is no problem. The playback equipment will correct if needed. IF you capture and mix analogue tape and digital then you need to make sure the levels are correct in the digital mix.

Ron Evans
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