Bug: Color shift in RGBA ffmpeg consumer/producer

[Sidonai-1]

Observed Behavior

When playing and/or recording a QTRLE video with alpha on CasparCG, the color shift is very noticeable. When recording I tried to add all types of color space flags but no luck.

As a baseline I took the exports from Premiere and VLC, which were equivalent (except for SpeedHQ codec, but not relevant now) so I left only Premiere in a table to compare.

I'm working with 3 files.
The original
And two recordings of the original, the one played and recorded with 2.4.3, and the one played and recorded with 2.0.7

To record 'REC-2.4.3.mov' :
ADD 1 FILE "REC-2.4.3.mov" -codec:a ac3 -codec:v qtrle -filter:v fps=25,format=rgba

To record 'REC-2.0.7' :
ADD 1 FILE "REC-2.0.7.mov" -vcodec qtrle

As we can see in the table just by playing it with 2.4.3 the color is already a bit off, and when we record it, it's also shifting; if I play the recorded file the color shifts even more.

Here's all the pngs I produced in case you want to take a closer look.

Environment

• Server version: 2.4.3 vs 2.0.7
• Channel: 1080i50
• Operating system: Windows 10

[Sidonai-1]

I tried converting the original file to ProRes4444 with Adobe Media Enconder to see what the results were.

Playing the ProRes file on 2.4.3 does not suffer from the same issue:

However, recording ProRes files is out of the question in most cases, as it needs so much more resources to not get constant drops.
I recorded REC-ProRES2.4.3.mov with ADD 1 FILE "REC-ProRES2.4.3.mov" -codec:v prores -codec:a ac3 -filter:v fps=25.
The resulting file does not have an alpha channel that Premiere can understand, and while the alpha seems to play normally on Caspar 2.4.3 (keep in mind it's a static video), there is a quality drop and a color shift in the other direction; and when I generate an image we get a deep fried png.