EXR Linear Workflow Advice

[Andrew Somers]

Yes, “Preserve RGB” is a feature in AE. Media Encoder is more about rendering final compressed video for distribution or batch transcoding. Ive never considered using it for image sequences.

Andrew Somers
VFX & Title Supervisor
https://www.GeneralTitles.com

[Nick West]

Got it, thanks again Andrew.

Here’s a new one for you (it never ends!) I’ve just done a few final exports to h.264/MP4’s via AME.
My exported files match up in various players (Windows 10 player, VLC, MPC etc) which is great, but one thing I did noticed was a very slight hue shift between my exported files and what I’m looking at in After Effects. It’s subtle but its there.

I did a test with an sRGB image as my ‘footage’. My AE project is setup for linear as we’ve discussed (32bpc, Linearize and Use Colour Management both enabled), I then exported to H.264 via AME and I can see the hue shift in the export across various players. I pulled the exported file back into AE and the shift doesnt appear to exist.

The only way I seem to be able to bring AE inline with my exported files is if to turn off ‘Use Colour Management’, disable ‘Linearize working space’ and change the Working Space profile from the stock sRGB oneto my monitor’s calibrated profile. Once I do that the colours in AE are identical to those in VLC etc.

I can’t quite get my head around what’s actually happening here. Any ideas?

Cheers

[Andrew Somers]

Based on what you described, I’m going to guess that your mp4 is at a resolution like 720×480 or smaller? (i.e. standard def size) ?? just a guess, but AME may be using the Rec601 colorspace, which uses very slightly different color primaries than Rec709 (which is what sRGB uses). I’m thinking this because Adobe seems to like to assign colorspaces based on
codec and/or resolution — and you’ll notice that AME give you very few options regarding colorspace, OTHER THAN “NTSC or PAL”. I find it interesting that “HDTV” is no where to be found inside AME.

Just as a point of reference, I NEVER EVER use AME straight out of After Effects. If I am going to use AME to create MP4s, I typically go out to ProRes, and then send that ProRes file into AME.

All that said, Adobe licenses “the guts” of what does all the work inside AME from MainConcept. You can read a sample of what the inner workings are capable of in this sample file here: https://www.mainconcept.com/us/getting-started/samples.html?item=1

As you can see, MainConcept can handle a lot of color spaces, but the HOST app needs to use the API to actually make things “go”.

Does Adobe/After Effects send the correct source color information to AME when encoding though AME? I doubt it because Adobe does not even do that correctly in the AE output module !!!!!!!! (By “correctly” I mean not only transforming the color into the correct destination space but also setting the Atom/Headers in the output file to correctly reflect this with the proper FourCC code or profile information — color managed my axx LOL). I suppose Apple is partly to blame here for creating a media container (QT) that does not enforce listing colorspace information in metadata.

ALL THAT SAID: If you are going to be going out to “small” videos (SD NTSC) then you might want to use a Rec601 profile for the chromacities of your working space. It is my opinion that the best results are had when your working space chromacities are identical to your destination chromacities.

Andrew Somers
VFX & Title Supervisor
https://www.GeneralTitles.com

[Nick West]

Hi Andrew,

I’m actually going out as 1080p H.264’s.

I don’t really have manu options straight out of AE’s exporter (as I’m on a Windows machine) so I am kinda forced to use AME here.

I’m not sure AME is actually changing the colour space because when I drop the exported file back into AE and switch between this and the original it looks identical.

Thanks again

[Duca Simone luchini]

Hallo everybody;

in this video

https://www.youtube.com/watch?v=4P2j1hzD8I8

when the guy is setting up the Linear Workflow in AE, he said at 2:18 said to disable “Linearize working Space” ( the project is full CGI in EXR) otherwise the linear range will be doubled.

But I think this is a mistake as AE recognizes input files with linear dynamic range, such as EXR, and does not modify them, while instead it converts input files sRGB, Rec. Log … to linear.
Therefore “Linearize working Space” should always be enabled. Correct?

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