Colorspace and bits

I feel like this has been asked by others, but I can’t find a clear answer here in the support forum.

I’m working with 10 bit DPX files in log format, written in the nucoda library. I have no problem importing and using them in mocha. It’s when rendering clips back out to files (as in the remove module) that I run into problems.

I have my clips set up in the clip tab with appropriate values. After removal, when I render out to DPX, I get 10bit log files, but in After Effects it’s clear I’ve lost information. Whites are being clipped at 1. In the original DPX, bringing down the whites with an exposure filter dials in all the detail. Using the exposure filter on a rendered DPX from mocha only makes all the whites flat grey. Using a difference blend over the original DPX sequence shows the same thing: everything is black except the hdr values.

I know there have been a few answers here where you suggest rendering back out to 16 bit TIFFs. But unless I’m mistaken, 16 bit TIFFs also clip HDR values at 1.

My solution was to “convert to float” in the clip tab. Seemed like the intuitive answer. However, rendering now yields 32 bit DPXs, which After Effects cannot natively read. EXR works, but the tradeoff is that it renders everything in sRGB linear.

If I have to use EXR I have to, but as the colorist has asked for everything back as I received it, is there a reason mocha won’t give me 10bit DPX log files that are not clipped at 1? What am I missing?

 

Thank you,

David

Hi David,

Are you always using “Export Rendered Clips” for your output, or are you just taking the renders from the Results folder?

Hi Martin.

 

Thanks for the reply. I always use the Export Rendered Clip function.

I have noticed on occasion that mocha has rendered both 16 bit DPXs and 32 bit DPXs in both log and lin, when I have convert to float checked. Not sure why either happens and I have yet to figure the steps to know why it gives me one flavor or the other. But I can’t open either natively in AE. I determine the bit depth and colorspace by opening one of the frames in Invisor (media metadata reader).

Thanks,

David