Rendered mp4 are being read as Rec 709?

[suzanne_doherty]

Quick one, when I import the rendered mp4 files into After Effects, After Effects will interoperate the footage as Rec 709, rather than sRGB.

When I manually change the interoperate footage settings from Rec 709 to sRGB the footage is identical, so I don't see why the mp4 files are being read as Rec 709.

The reason why this is an issue is that we're using the mp4 files for pre-vis, then replacing the footage in After Effects for the rendered exr files. However we're having to manually change the interoperate footage setting for ever file, which is time consuming, and prone to user error too.

Dean

[npg]

Thanks for pointing this out. Until now we had left the colorspace metadata unspecified. We are now going to set it explicitly and this should be included in the next update.

Are you referring to the "Interpret footage" dialog in After Effects? It might be helpful if you can share screenshots of what you see in the AE UI now and what you expected to see, so we can verify that the change has the desired effect.

[suzanne_doherty]

Hi Nikola,

I have attached 3 screen shots.

The first shows the mp4 in the project panel, and notice how it says it's Rec 907, which I presume is what After Effects defaults to when the color space is unspecified.

The 2nd shot shows the mp4 color setting in the Interpret Footage dialogue.

The 3rd shows how the mp4 should look in the Interpret Footage dialogue.


I thought the footage might not have been assigned a colour space, which is fine by itself, the issue happens when we use the Replace Footage function. There might be a way to script this in After Effects, but would be handy for it to be in sRGB from the start.

Thanks,
Dean

[npg]

We are now writing the colorspace to the mp4 file, but AE is still being weird and we can't quite understand how this interpretation thing works. Other software like Premiere and VLC recognizes the color space.

[suzanne_doherty]

if you want to send me a new mp4 file to test I can.

[npg]

OK, here is one: https://drive.google.com/file/d/165r...ew?usp=sharing
And an alternative version: https://drive.google.com/file/d/1WJ4...ew?usp=sharing

The difference is that the second file sets exactly the same flags as OBS, found in their sources: https://github.com/obsproject/obs-st...peg-mux.c#L169
The first version sets AVCOL_SPC_RGB which is commented as "sRGB" in ffmpeg.

[suzanne_doherty]

those mp4s are still being read in After Effects as Rec 709, not sRGB....

[npg]

This is what I meant with "AE being weird". The way I understand this dialog, it doesn't detect the file as "Rec.709", it detects it as "Media Color Space: None". The line with Rec.709 is a user-defined override and 709 is probably just the default override. The documentation says "If a footage item does not have an embedded color profile, you can assign an input color profile using the Interpret Footage dialog box or by adding or modifying a rule in the interpretation rules file (interpretation rules.txt)". So I think "Media Color Space: None" means it didn't detect an ICC profile. We don't intend to embed ICC profiles at this point.

This may be relevant: https://community.adobe.com/t5/after...9/m-p/11259258

[s.balabanov]

Hi suzanne_doherty, could you share an mp4 file that you are able to import in After Effects and automatically interpret it as sRGB? And please specify the exact version of After Effects you are using (Help / About After Effects).

Thanks,
Simeon

[npg]

And you said

When I manually change the interoperate footage settings from Rec 709 to sRGB the footage is identical

so is there really a need to set anything? Our video files match the "Working Color Space" seen in your screenshots, so they should match it without conversion.

[suzanne_doherty]

And you said so is there really a need to set anything? Our video files match the "Working Color Space" seen in your screenshots, so they should match it without conversion.

If we were just using the footage, then there wouldn't be a problem, it's when we replace the mp4s for exrs (from vray GPU). The exrs take on the color settings from the mp4s.

[suzanne_doherty]

This may be relevant: https://community.adobe.com/t5/after...9/m-p/11259258

Ok so it would appear that it's an After Effects issue, where it will default to Rec 709 on imported mp4s.

[suzanne_doherty]

Just tested with a png sequence from Vantage, and this imports fine.

I've also then exported the sequence as a mp4 file, and then imported the mp4 back in, and even this mp4 file is now reading as Rec 709, even though there is no Rec 709 being used or applied anywhere! Madness from Adobe.

I guess my solution is to use png sequences at the pre-vis stage, rather than mp4s.

[suzanne_doherty]

I'm almost certain it's an After Effects thing, when I open the mp4 in Photoshop it reads the file as sRGB.

I have also imported the file into Premiere Pro, and I can get the issue as After Effects.

Anyway, thanks for your help guys, seems like there's not much we can do (