This IS the Avid L2: Re: [Avid-L2] Color Correction Gamma Points, and Blu Rays

Thursday, September 8, 2016

Re: [Avid-L2] Color Correction Gamma Points, and Blu Rays

"Note: when it comes to final deliverables you almost always want to go 'Video' (or 'Legal') range (unless explicitly told otherwise)"

All my deliverables are legal level but I have found that when I take a DNX 175X timeline and export a QT Ref from Avid to process in Adobe Media Encoder I have to check the box for Full Range, or old school avid terminology RGB when I'm creating an XDCam50 422 file for delivery.

If I don't check Full range when I ama link back to the processed XDCam50 the video essence is washed out and low in level just like a file that is legal range but then incorrectly scaled from Full Range to legal range.

As long as I export the QT Ref expanded to Full Range then AME make a correct legal level XDCam50 file. It seems the AME really wants a Full Range file in this particular workflow. I don't know if the use of a QT Ref is creating this behavior but I don't think I see the same behavior if I'm just processing an DNX file out of AME. It's been a while since I checked other AME formats and workflows but In know for a fact this is how the DNX-175X to XDCam50 responds in AME on my system.

I'd sure like to know if there is a simple rule for AME that it always wants and Full Range file or if it's a codec by codec decision.

---In Avid-L2@yahoogroups.com, <elists@...> wrote :

On Thu, Sep 8, 2016 at 10:18 AM, David Dodson davaldod@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

I took a very direct path. I imported the ProRes4444 exported out of Baselight into Encore directly and encoded to H264 at Maximum Quality transcoding and writing directly to the Blu ray disc.

As a colorist who's used to having clients blame these problems on him...

My first troubleshooting step whenever a client says they're using ProRes444 is to have them test their pipeline—but using a ProRes422HQ export.

Why? Because ProRes444 defines both 'Full Range' and 'Legal Range' as acceptable bit values and different pro apps make different default assumptions about which set of code values it is using. ProRes422HQ is ONLY 'Legal Range' and almost all professional software correctly interprets how to handle that codec. By testing your pipeline with ProRes422HQ you can quickly identify if one app in the workflow is misinterpreting the 444 code values, resulting is an incorrect final image.

You don't have to do the test on the entire program... just a scene where it's really easy to see the problem.

If everything looks fine with the ProRes422HQ test, then your job is to figure out which app is kinking up your pipeline by misinterpreting the 444 export. Note: when it comes to final deliverables you almost always want to go 'Video' (or 'Legal') range (unless explicitly told otherwise) - so start with the app doing the initial render.

BTW - linear grayscale ramps are terrific for troubleshooting this type of stuff. Comparing Waveforms will often tell you the story. And Resolve is a great free app for easily toggling footage between Full and Legal range to help troubleshoot.

HTH

- patrick

- -
Patrick inhofer
Colorist / Finisher / Owner, Fini.tv

Coach

MixingLight.com

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