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IRE and Video/Data levels.

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Martin Gaumond
IRE and Video/Data levels.
on Feb 20, 2014 at 1:23:12 am

I'm new to resolve, coming from smoke and the occasional lustre. I am trying to get something straight in my head. It never really occurred to me until I got a new flanders monitor and scopes.

I pop up the standard color bar test pattern and check the levels on my waveform (not the software scopes).When I set the levels to video the blackest black on the waveform sits on the 0. When I put the video levels to data the blackest black goes below zero by a few points.

So is the 16-235=0-100IRE and 0-255= -10-120IRE? I'm just trying to understand this. IRE hasn't really been in my work up until now. Been using software scopes and computer monitors.

On a side note. It seems like my flanders is displaying video levels, how can I make it display data if that is even possible and a desired workflow. Is it better to work in full RGB range then clip or remap it to video levels if the delivery requires it? Or should I stick to video all the way. I've read differing opinion on the matter.

How do you work?

Thanks guys!


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Joseph Owens
Re: IRE and Video/Data levels.
on Feb 20, 2014 at 10:36:23 pm

[Martin Gaumond] "So is the 16-235=0-100IRE and 0-255= -10-120IRE?"

Yes, that is pretty much the way Y'CbCr is mapped and is appropriate for HD video workflows destined for broadcast. It allows for "overshoot" and "undershoot", and is a kind of hangover from the days of composite baseband video.

If you are dealing with RGB media, Animation codec, ProRes4444, dpx scans or rendered graphics, then you might want to choose the full scale rendition... 0-255 in 8-bit, 0-1023 in 10-bit... and then pick the correct SDI interpretation for export to a viewing environment. Most of the time, at least for broadcast, we are interested in 709, but that is only one delivery destination. Different if you are delivering thatrical -- for some it is more appropriate to view in XYZ DCI space, and then, of course you need to pick the right monitor mode.

Different horses for different courses.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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