7.5 ire

J

Jeff In Ocala

Active member
Hi all I shoot mainly SD 60i onto p2's with my hvx, then import directly into edius and it comes in at zero ire. 99% of my stuff is for broadcast so I always have to bump up the black level in post. Does anyone know what setting I could bump up in the camera to save the step of raising the black level in post. Any help is appreciated
Thanks
 
The camera records at 0 ire.
What you need to do for broadcast is
monitor on a calibrated NTSC monitor
that is usually output from
a tape deck.
Most cards that go back to a deck
will add the set-up back in when
you record on tape....
 
Hi Jeff,

You should NEVER raise the black level to 7.5 ire in post.
Black is 0 value ( ire ) in digital domaine.


7.5 ire applies ONLY when you bump to analog tape.

Same for DVD, the DVD players raise blacks from 0 to 7.5 automatically.


...so that way, you keep ALL digital info intact, from 0 (black) to 235 ( 100 ire) digital value.
 
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thanks for the replies my workflow most of the time is shoot p2, injest mxf into edius, edit, output to a pvw2800 beta sp deck for distribution to local broadcast and cable outlets. the output of my computer usually goes from component out to the beta deck or S video out to the beta deck and the card doesn't bump it up to 7.5 automatically. Can i make a scene file for the cam for when I know what i shoot will be output to beta sp and have the blacks set to 7.5? or is it better to just bump them in post for output to the deck?
 
there is confusion in the 0 black !!
the digital video NTSC 601 spec says the blacks are 0 ire ..looking more into 601 it is based on the scale being 16rgb to 235rgb ( 0 to 100ire) .. in the analog world 16rgb translates to 7.5ire ... so it appear the digital video 601 spec (16rgb = 0 ire but in analog is 7.5) really just have "set up" already built into it ??
 
Yeah, that part is a little condufing, but you can ignore it.

There is no set-up in digital video, ever. It is only part of the analog NTSC signal.

Your computer card *should* add the 7.5ire setup when it outputs an analog signal. Unfortunaly not all cards do. The only one correct solution is to use a seperate device (like a Proc-amp (found in any good TBC)) to bump to the levels. A Proc-amp before, and a set of scopes after, your output record deck is always a good idea anyway when outputting material for broadcast.

Shootign "setup" to your cards means that any image processing you do will also affect the set up. Gamma curves will be wrong, color correction will effect the "set up" black, computer generated material will have wrong levels, etc, etc.. Set-up is meant to be outside the affected signal, don't bring it into the digital domain.

- Mikko
 
Thanks Mikko, I do use scopes and a proc amp, and now I understand your point, I should just let the cam shoot at zero, do all my post work then on final output adjust for broadcast.
 
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