Hi. My problem is:
With every video i tried i have color distortion. This affects the editing stage and rendering result.
Here is how it looks:
Video in player vs Cinelerra:
https://encrptd.com/image/83aY
https://encrptd.com/image/8J1j
Better to open links in Firefox, because Chrome based browser forces srgb color profile.
UBUNTU 20.04 x64, Acer Aspire 5750zg, Intel integrated video + Nvidia GT520m discrete
Cin built: Oct 31 2020 11:54:55
this may be related to the fact that Cinelerra displays the colors correctly (0-255) , but all players and also Firefox does the typical clipping for PC playback (16-235).
I am not sure yet how to set Cinelerra, maybe other users can say more about it.
The only thing that is certain is that there are different color spaces for different reproduction systems. These are called, for example: Studio-RGB or Computer-RGB.
Hans
Unfortunately CinGG does not have a global Color Management. For some hints try to read the manual in 17.3:
https://cinelerra-gg.org/download/CinelerraGG_Manual/Color_Space_Color_Range_Aff.html
Here is an attempt (incomplete and probably with errors) to understand how CinGG works with colors:
Hallo, unfortunately I do not understand enough about color management. Also the hints from andreapaz overwhelm me.
Earlier I had learned with Vegas Pro that this software displays the colors, i.e. the pixels exactly as they are. This was very good, but had the disadvantage that Vegas did not easily show the picture as a media player on a PC will show it later. There was a plugin for that. With that, you could choose to see the true colors, or have the higher contrast view that typical media players show.
So my question is: How does Cinelerra display the colors? 0-255 or, as it is common on PC: 16-235? Does anyone of you know?
Oh, thanks @andreapaz, i opened the first link you specified, saw a picture with the color settings of the composer, and now I dont understand how I didnt notice this in the settings of the program before.
I changed JPEG to MPEG and the color became almost exactly the same as in the player. And It suits me, thank you for the tip! 
Ah, I think I understand. When I choose in the Settings > Preferences > Appearance > Color: YUV color range: MPEG, then CIN GG will display the video as a media player on a PC will do later, namely (16-235).
If thats true, then Ive taken a big step forward.
Many thanks