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Black Levels!
Does anyone know of a way to have FCP clip the blacks so that I do not have values below 7.5 units when outputting with an aja io?
read on for specifics…
The people at AJA swiftly responded to this in their tech department:
> In regards to black levels: The Io does not clip
> super black video levels;
> however it does rescale the luminance on capture and
> playback.
>
> In the case of betacam, 7.5 IRE is scaled to 0 IRE
> on capture; scaled back
> to 7.5 IRE on playback. In other words: Black in FCP
> is 0 IRE; Black with
> betacam is 7.5 IRE – again the Io handles the
> scaling but does not clip the
> super black.
>I do understand the technical explanation given by AJA, however I believe there must be a method, or one should be developed to ensure no illegal black levels. If there is no such thing as below zero in FCP, and the AJAio scales all zero blacks to 7.5, then how can a “superblack” exist, and how can I end up with analog video values below 7.5. Based on this information it should not be possible.
They suggested trying the broadcast safe filter which, unfortunately does not have any effect on the blacks (FCP4.5).
Is there another suggestion for not allowing black levels below 7.5?
I can go in and tweak each shot, but the point is that they have noisy greys, that we want to have disappear into black. Making the shot legal by raising the blacks, ruins the aesthetic. Clipping the blacks at 7.5 is the desirable option here.
I have been using Media 100 for many years, which does not allow analog video values below 7.5 units. I suppose I could digitize the entire program into the Media 100 from the AJA io to legalize the blacks (LOL – sort of).
Thanks, hopefully there might be another suggestion.
Tim
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2 Replies
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Blacks should be at 0% in the FCP waveform monitor. Are you seeing black below this? If so, can you arrange to send me a very small clip, and I’ll write a filter that will do what you want, but I need the footage to test it on.
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP
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Have you output a copy to tape and messured that tape with scopes? If all you are using is fcp as a messure before Aja changes things back to 7.5 how do you know what is out of spec?
Chris
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