Re: [FFmpeg-devel] Subject: Request for Support of Cineon Log Transfer Function in FFmpeg

[compn <ff@hawaiiantel.net>]

On Thu, 23 Jan 2025 18:46:51 +0100 (CET), ATERstudio wrote:

> Dear FFmpeg Development Team, 
> I hope this email finds you well. I am reaching out to request the addition of support for the Cineon log transfer function in FFmpeg, specifically for the DPX files that use this format. Currently, while FFmpeg supports other transfer functions like gamma 2.2 or 2.4-Rec709, there is no option to correctly specify Cineon log for color grading and restoration purposes when processing DPX images. 
> As part of a film restoration project, I work with DPX files that are encoded with Cineon log gamma, and it would be extremely beneficial to be able to work with these files natively in FFmpeg, preserving the intended color characteristics for accurate post-production. 
> Is it possible to consider adding an option for Cineon log in the -color_trc parameter, or perhaps any other solution that would allow FFmpeg to correctly interpret and handle these files for professional restoration workflows? 
> Thank you for your time and consideration. I greatly appreciate the work that the FFmpeg team has done in advancing open-source video processing, and I look forward to your response. 
> Best regards, 
> 
> MIRELA Budimic 
> colorist/digital restoration artist 

hi, its possible. although i dont know if any developers want to take
this feature on. it might be worth it to offer a bounty for unsupported
features. you dont have to go into details here, but offering a
job/bounty and that any interested developers can inquire within.

can you please link to a few samples , preferably smaller samples, that
have the cineon log gamma? is there any sample that you can make
which shows the difference in what the video looks like converted with
the cineon log vs without it?

its also helpful if you can link to any software that we can compare
ffmpeg to. an official software or specify which software you use to
handle these files would be helpful.

to be clear, you want to support the demux, decode and conversion
of cineon log gamma , not just report that a file has cineon log gamma?

if you have any documentation about the cineon log , be it an official
specification or source code, anything , that would also be helpful for
developers to look into.

https://air.unimi.it/retrieve/1c6693d8-9bc9-4aed-a9b8-e7402092b377/Color%20Research%20Application%20-%202024%20-%20Plutino%20-%20Color%20systems%20for%20motion%20picture%20film%20digitization%20A%20critical%20review.pdf

i'm curious which colorspace you would want to convert cineon log into?
or do you only want to convert cineon to cineon ?

p.s. i see you are a colorist, please no more orange/teal.
http://theabyssgazes.blogspot.com/2010/03/teal-and-orange-hollywood-please-stop.html

thanks
-compn
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