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FCP Video Waveform Accuracy
While I’m still trying to wrap my head around quicktimes and gamma differences between rgb Qt’s and 422 Qt’s—there is still something I see & I don’t understand.
If I convert my RGB QT which has a 32 step grey chart to 10Bit 422 Uncompressed QT. How come FCP & QT’s viewer only displays the 0-100 range yet the scopes show all the steps (3 above 100).
In Shake & Nuke-I only see 0-100 on the waveform/histograms.
Why do the scopes show this?
thanks for any thoughts,
Tom
Tom Tomlinson
Telecine Ass’t.
NYC -
5 Replies
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Google the article of Nattress “Video Levels in Final Cut Pro”.
Shake, and I guess NUKE too, works in RGB. No way for values over 100%.
Rafael -
Thanks Rafael. I did find that. Its a great find.
But what I find odd is that if the original 33 step rgb chart got converted to 422 and clipped. What I see on the viewers are the middle 29 steps. What I see in the histogram/waveforms of shake & nuke is 29 steps. But what I see in fcp’s viewer only displays 29 steps but the fcp waveform shows 33 steps from -10 to 110.
So does qt & FCP block that extra info–basically “proc it” but the waveform is “pre-proc amp”?
thanks,
TomTom Tomlinson
Telecine Ass’t.
NYC -
Hi Tom,
Can you tell me the specs of the file of the original chart?
If you are getting these “off-specs” values, your chart must be, at least, 10b RGB.
8b RGB doesn’t let you pass nothing over 100% or below 0%.[Tom Tomlinson] ” But what I see in fcp’s viewer only displays 29 steps but the fcp waveform shows 33 steps from -10 to 110. “
This indicates that there are some super-whites and super blacks.
In the Canvas, you can not tell Super-whites from whites. They look the same: White.
Same happens with Blacks and Super-blacks.
In the Canvas they look just like black, but the Videoscope can see the difference.
Rafael -
Its a dpx sequence that I rendered from baselight color correction. I rendered a 10 bit 422 uncompressed qt and an 8 bit one.
They both display clipped white on the viewer yet on fcp waveform/parade they are not clipped and show 33 steps.
I am trying to get a solution for color accurate 422 Quicktimes from color corrected rgb dpx files to satisfy client deliverables.
Tom
Tom Tomlinson
Telecine Ass’t.
NYC -
[Tom Tomlinson] “They both display clipped white on the viewer yet on fcp waveform/parade they are not clipped and show 33 steps. “
I guess this is due to a shortcoming in QT/FC on displaying.
The display is done in 8b RGB, so you get the clipping, however the clipping doesn’t happens on exporting.
I had this issue (drove me nuts for a few days) when applying certain filters (NeatVideo). SuperWhites are slashed in Viewer and Canvas (and even in the Videoscope) but are preserved on exporting.
Trust the Videoscope.
Rafael
PS: This is not a question for the FC Basic Forum.
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