ID 462232 - From Editorial: Adjust ffmpeg and DNxHD Converter colourspaces to avoid ref panel colour 'pop' and dimming

Problem summary
Thumbnails created from movs and those created from still images seem to be rendered with different colourspaces. This is obvious when publishing back to Flix using Render All Frames, compared to using Hold First Frame. 

ffmpeg should use the same colourspace as the DNxHD Converter when creating thumbnails.

Update: this also seems to be a problem when using Premiere as refs look dimmer than the original panels.

Customer reported version
Flix 6.3.4

Steps to reproduce
1) Create a panel in Photoshop and use the colour picker on at least 3 different colours of the panel so you can see the colour parameters.

2) Send this to Flix, then publish it to Editorial (for example Avid). Sending panels to Avid in Full or in Legal range does have a slight difference in how the colours will then come back, but both methods will reproduce the bug.

3) Add a paint effect on the panel in Avid without altering or covering the colours you got parameters for in PS.

4) Publish this back to Flix using Render All Frames.

5) Open the ref panel in PS (this will automatically use the thumbnail as the artwork for the ref will be a mov) and compare it to the original panel.

Original panel from Flix:

Panel sent to Avid in Full range, added paint effect there, and brought back in Flix using Render All Frames:

Expected behaviour

The colour parameters should be either the very same, or at least the difference should be so slight it's not noticeable.

Actual behaviour

The difference in colour between the two is very obvious at first glance, and parameters are quite off.

It seems ffmpeg and the DNxHD converter use two different colourspaces. When using Render All Frames during an AAF import, any refs will have a slight colour 'pop' compared to their original art.

Reproduced by support

6.3.6 - macOS 10.14 Client - CentOS 7 Server