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Level Clipping when exporting Quicktimes
I create Quicktimes from material on FCP that I want to grade on an external system. (In this case a Nucoda Filmaster.)
As is often the case with video rushes there are some illegal levels (mainly super-white)and I have to preserve these so I can correct them in the grade.
If I re-import (round-trip) this material straight back into FCP all the levels are exactly the same as they were before – bit for bit. So all the video is there in the QT.
When I import into the Filmaster the file is scaled so the legal video range (black 64, white 940) become full range (black 0, white 1023). All sub-black and super-white are clipped.- so I can’t pull the detail back.
The Filmaster exports and reads its own QTs perfectly – The levels track bit for bit.- no scaling, so it is treating the FCP QTs differently.
I have tested with Avid Symphony and Avid DS – some codecs don’t work right, but I can get material into the Filmaster ‘bit for bit’ correct.(and out again !)
So I know that all the video levels are in the FCP exported QT’s, but I can’t get them into the Filmaster unclipped.
I’m working round by playing out to tape and re-capturing, but I really need to get this working.
FYI I am not very experienced FCP wise – so be gentle!
Any help on this gratefully received!
PS If I open the FCP QTs in Photoshop CS3 – I get the same result – legal levels go ‘full-range’ -sub black and super-white are clipped.- same behaviour as Filmaster.
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1 Reply
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Maybe, just maybe (and it’s just a thought so I’ll happily accept I’m wrong!) the codec you’re using is one of those that comes with the video card you’re using, eg Aja-ProRes(HQ). So the QT might have some metadata that can restore the super-levels but only in FCP….. I can think of many reasons for this not to be the case, though. Either that or there’s a bit in the data word that’s being lost by the external software (I suppose that could be related to the idea of avoiding hardware accelerated codecs as mentioned). This is vague, I know, but my only suggestion is to look at using the codecs in the pull-down list that are only supplied by Quicktime when you install it; so keep to ProRes but make sure it’s Apple’s one…. Having said that I’ve got Combustion on my machine and have never noticed clipping, but my eyes aren’t what they were! 🙂
Hope this is of some help!
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