Color profile quirk in monitors?

[Harald Albrecht]

Hi,

there may be a color profile quirk in Kdenlive's monitors which I 
noticed while working on my latest project. I'm not exactly sure, but it 
loooks like a quirk and I would like to hear what the devs think about 
it. Maybe it's a Kdenlive (clip) monitor setup issue?

Anyway, take an MP4 container with an H.264 video stream using the 
BT.601 "color profile" (is this even the correct term? shame on me). 
Please notice that it's not the famous BT.709 so common with HD content, 
but good old "TV" BT.601. The source actually is a screen recording done 
on a recent Android 7.0 Samsung device.

Now when I add this video file to Kdenlive's project bin, then click on 
another bin item, and come back to this video file, the clip monitor 
will show the wrong colors. To me it looks like the clip monitor 
initially always apply BT.709. However, the clip properties tab 
correctly shows BT.601. Next, if I play, scrub or reposition the 
playhead of the clip monitor, then it shows the correct colors applying 
BT.601. Only once in a time a color-shifted frame will appear. Clicking 
away on another bin clip, and then coming back again shows the wrong colors.

Timeline playback seems to be correct, as seems rendering.

Could this be an issue with the AV correction initially not getting 
applied when selecting a clip anew for the clip monitor to show?

Best regards,
Harald