Avid Clipping values over 235 IRE

Daygola814

Daygola814

Well-known member
When I render out to After Effects, I use a Quicktime Reference File. WHen I bring this into After Effect, I notice that the values are clipped if they're above 235. I also captured the same video with Premiere (as an avi) and brought that into After Effects and the values over 235 (up to 255) are present.

I'm not sure what's happening here. I tried exporting 601 and RGB but both gave me the same results. If it's a Quicktime reference file, then I'm going to assume that Avid is clipping these values upon capture.

Anyone have any idea what I'm doing wrong?

I'm on Avid Media Composer 2.5.
 
If you're coming in digital, it is taking everything it is given. When you look at the values in the color corrector, what do the white values say?

Michael
 
avidcc.jpg



So the values arent being clipped on capture. It must be the Quicktime Reference, but if that's the case, how is that so? I thought the QT Reference was a reference to the captured MXF file.
 
Not sure what format you're coming from, but, in my tests with XDCAM EX, avid mc305 and QTref, importing RGB will remap all values to RGB 16-235, while importing 601 will allow RGB 0-255.

Exporting is a whole different story. Different codecs function differently according to the input flags. It might well be the way AE is responding to the flags set on the QTRef.

edit: if you're source footage is DV, then it will be RGB16-235 by default.
 
Last edited:
cuervo said:
edit: if you're source footage is DV, then it will be RGB16-235 by default.
Click to expand...

So basically, if I'm capturing DV, the values from 101%-110% will be clipped regardless of what I do?

If I capture in Premiere, I still have access to those values.

Man, that kinda sucks...
 
Don't use quicktime reference. Create an uncompressed quicktime and, under export settings, choose rgb for the color space.

This will solve your issues.
 
several things to consider...
1-superwhites add very little detail info and, for all intents can be ignored. i would be more concerned about the shadow data RGB0-16
2-avid imports full range RGB by remapping all values to 16-235. so, you're not clipping, you're remapping...no data lost. just be sure under import options, you select RGB, not 601.
 
Use the curves in color corrector to create a smooth arc while pulling all your highlights to be no more than 235 if you want to be legal digital video and preserve whatever details might exist in that range. The color corrector is showing you have values above 100% from capture which is good - the full range - now use the color corrector to keep what you want.

Michael
 
Jim2000 said:
Don't use quicktime reference. Create an uncompressed quicktime and, under export settings, choose rgb for the color space.

This will solve your issues.
Click to expand...

I did this and this seems to work. Not sure why the Quicktime Reference wasn't working.

Also, I tried exporting an AAF to After Effects but AE couldn't import the Avid MXF files. If this is so, how does Automatic Duck work? You need to export an AAF first, right?
 
QTreference won't work with long form GOP, which is what mxf is. After importing your mxf file, transcode it to something like DNx165 or uncompressed if you prefer, then you'll be able to export with QTref.
 
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