Blackmagic Forum

My workflow is 10 bit 422 uncompressed RGB avi from Premiere Pro CS6 into Davinci Resolve for grading then exported back out as 10 bit 422 uncompressed RGB from Resolve back into Premiere for rendering my final output.

I'm viewing Resolve on a separate TV monitor via an Intensity 4k output card for the grading and the image on that looks great (as it does on the main computer monitor screen as well). However the exported file post-grading is much darker to the point of being unusable. Any suggestions as to what the problem may be or how to work around it?

EDIT UPDATE: I've changed the title because the problem is with the file that Resolve is creating, not with Premiere. I reimported the 10 bit file to Resovle and it was dark there too. I've attached two still images - the lighter one is a Resolve grab from the graded timeline and the darker one is a grab from the timeline from the 10 bit RGB output file reimported to Resolve. As you caa see my atmospheric lighting is gone and the image is just way too dark!



ANOTHER UPDATE!

I've just outputted that same shot in a variety of formats and I have some that work! All the AVI formats came out dark but Quicktime H264 and Grass Valley HQ were a match for my timeline (but lossy). Quicktime 422 YUV 10 bit uncompressed was a match as well. Quicktime RGB 10 bit uncompressed was actually a little lighter than my timeline! Now I'm really confused!

I noticed that the timeline colourspace was set to rec709 - should that be on sRGB? Does it make a difference to the output?

Thanks again for any help you can offer

Pete

Pete Tomkies wrote:I noticed that the timeline colourspace was set to rec709 - should that be on sRGB? Does it make a difference to the outpu

Have you tried exporting your Quicktimes in "Linear Video" rather than "Auto" or.... because your output is showing up much darker, its probable that the image values are being re-mapped into RGB space, resulting in *below-zero* IRE values. Its a problem. Worse when an OPerating System gets hold of it and starts applying colorSync profiles. But NLEs don't have many checks and balances for determining the correct 0-100 IRE scaling for RGB vs. Y'CbCr sources.

jPo

How is the monitor calibrated?

How do the rendered files look on a scope? Use a few seconds of SMPTE bars and 10-step grayscale, and make sure what you render out is where it needs to be.

Gamma shifts happen, and those are often responsible for things coming out too dark or too bright in rendered files. I blame Apple for its hit-or-miss implementation of QuickTime in the operating system and how different software interprets the gamma space differently. (Some flavors of Avid DNxHD have the same issues.)

BTW, note that QuickTime 422 is compressed. Just maybe not as compressed as the other file formats.

Thanks both for your help and advice. The description of the Quicktime codec as uncompressed is Resolve's terminology not mine

Give me a page number in the v12 manual that calls QuickTime "uncompressed." I just did a fast search, and everytime I saw the word "uncompressed," there was a comma between it and QuickTime. Even ProRes 444HQ is still compressed by about 4:1 (which I think is very mild):



Apple's white paper on ProRes goes into the bitrate distinctions very well:

https://www.apple.com/final-cut-pro/doc ... _Paper.pdf