This IS the Avid L2: Re: [Avid-L2] Embedded Arri Look files?

Friday, April 22, 2016

Re: [Avid-L2] Embedded Arri Look files?

You were surprised to find out that embedded LUTs apply even with Auto turned off, but if you go back a few emails, you'll see that I wrote you that information in our back and forth about Auto Add LUTs…

On Fri, Apr 22, 2016 at 10:41 PM, John Moore bigfish@pacbell.net [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

Thanks to help from Oliver Peters I figured out that the Arri Alexa ProRes 444 files I've been getting from a New York crew have an embedded Look File Meta Data. I've been having good results with Arri Alexa and Avid's standard Arri LogC to Rec 709. I had been suggested in an earlier thread this week to disable the auto application of a source LUT when Avid thinks it knows the camera your linking to because Avid sometimes gets it wrong. My experience with Arri has been solid but I took the suggestion and was surprised to find out that even with the auto LUT application off in color management setting it seems the Arri embedded data still gets applied. I was also surprised to see that these files added two items into the process box in source settings. One item was Levels scaling (video levels to full range) and the 2nd item was ARRI 709.AML (embedded).

I learned from Mr. Oliver that Arri has software that allows the field folks to grab frames and in some cases moving pic files to do color tweaks and feed that to the camera to have it embedded into the meta data of the files. I'm assuming that's what I have received in this case. I find it curious that the embedding adds two items in the process box especially since one looks to expand to full range and the second looks to bring back to 709. Why expand and then contract. Perhaps this allows for proper full range work in the app but I'm just guessing. I'm starting to believe that the way Resolve deals with image levels is it's working full range inside itself and then scaling back to video levels when baking things out. That seems to explain to me why I see the LUTs made with Resolve in the field that look like RGB space in 709 world. If I export the Resolve LogC to Rec 709 LUT and use it in Avid on LogC material then compare that to the levels of media actually baked out with the LUT from Resolve the Resolve baked media is higher in setup and lower in peak white in much the same way RGB and 709 levels differ.

Here's a link about the Arri look files that I got from Mr. Oliver. It even includes an email link to ask questions. Man I really like professional companies that support their product. Here's the link:

http://www.arri.com/camera/alexa/workflow/working_with_hd_video/hd_video/arri_look_file/

John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net