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video levels and specs

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Baz Leffler
video levels and specs
on Jun 19, 2009 at 1:10:00 am

Something that has always bothered me since the adoption of digital video is 'luminance spec'.

For years (yes I go back to the early seventies in broadcasting) camera's were set up with white clippers st to 105% from factory. The program delivery spec was also 105%. Too much luminance and it would get into the sound carrier of the transmission bla bla bla....

With the advent of digital the spec became 100% max luminance. But the camera's kept coming out of the factories set at 105%. In the old days I would set the lineup bars to 105% so it would appear the vision was at 100% and would be accepted.

But now the broadcasters put the tape in the machine set to 'unity' and reject if the lineup is not bang on 100%. So I had to drop that idea and resort to using 'broadcast safe' filters which is a pain as it causes white clipping on some shots thus requiring tweeking shot by shot.

Now I find even the latest HD camera's still have 105% clipping which can be adjusted on the high end camera's but not so easy on the mid range camera's such as the Sony XDCAM's.

Can any of you 'broadcasters' here shed light onto why this discrepency exists? I know that for non-broadcast its great to have that extra 5% but wouldn't it have been easier to have a menu item within the camera that says 'broadcast safe'?

And of course there is the problem with the editing software. In Final Cut pro you have to put the broadcast safe filter on every individual clip in the timeline AND you have to make sure its in the correct pecking order. If you have a colour correction filter in after the broadcast safe filter it could knock it out of safe. I mean how ridiculous is that? If you apply a broadcast safe filter to a clip it should make it 'broadcast safe' regardless of what you do to it later - or better still, have a single timeline option called broadcast safe.

I really am a firm believer that people who write this software don't use it in a real world environment.


What would I do without the 'UNDO' button!!!!

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Bob Zelin
Re: video levels and specs
on Jun 19, 2009 at 3:36:15 am

boy, do I agree with you. Today, without a legalizer, you can get screwed (read: tape rejected) for being at 105. Back in the stone age, the GVG Proc amps had a hard clip function, and it sucked then, and it sucks now. Of course, if you try to light a scene for 100 IRE peak (or .700 mV peak on a digital scope), you lose your contrast ratio, becuase you have to give up too much. So you are forced to clip, and you still get screwed.

Solution - shoot in film !
I feel your pain. Hey, isn't this what generates all the color grading and "on line conform" business anyway. If it were easy, they wouldn't need us !

bob Zelin

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