1:1 pixelsharp, 1:1 color, part of screen, not easy to configure ...

[newbie-02]

hello @ all,
can assume question has already been discussed, alas didn't find it ( newbie ).
My helpless attempts in screen recording suffer from aliasing, limited colors,
different codecs ... the hell ...
I'd like to be able to record part of the screen, and:
- get pixelsharp 1:1 video, e.g. recording a 1280x720 area of a 1920x1080 screen
and have 1280x720 output pixels 1:1 as had been on screen ... 'lossless'.
- in same manner get lossless color forwarding screen -> obs -> media player
( preferred VCL ).
And found no 'newbie-howto', stumble through preview scaling, windows too
wide, codecs ... I'm lost. Is there a simple help available anywhere?
In a further step I'd like to be able to perform a clean 2:1 downscaling, record e.g.
2560x1440 area of a hidpi screen, and apply a simple 4px -> 1px compression
to produce 1280x720 output. But first would need to get above steps working
without becoming a victim of well-meaning but disruptive 'improvement attempts'.

TIA for any hints ... b.

 

[newbie-02]

Gathered some insight, will try to collect it here as sort of 'wiki', for review by pros
and help for others who'd like to achieve similar.

Target is to produce a recording which uploaded to video hosters like youtube
will provide good readability. There will be other ways, for me it's essential to
have access to any single step to avoid mixup of optimizations where it's difficult
to understand or judge the final result.

Step 1.) Learn magnifying your screen, in Kali Linux with XFCE desktop I found two
options:
Screen zoom by a selectable control key and mouse scroll or two finger
scrolling on touchpad. Settings Manager - Window Manager Tweaks - Accessibility -
select control key, alas any is conflicting with scrolling in one or other application.
( May require installation of Window Manager Tweaks )
VMG, 'sudo apt install vmg', a 'screen lens'.

Step 2.) Learn about your source, get a clear view on what you want to record,
a source which is like pic_01 in normal view ( a ~25 percent window on a 4k screen ):

may look like pic_02 in detail / enlarged ( with default font anti-aliasing ), note the yellow / blueish colored seams:

or pic_03 ( anti-aliasing off ):

or pic_04 ( anti aliasing on, hinting off, Sub-Pixel Order still active ):

or pic_05 ( Sub-Pixel Order also 'none' ), note that the anti-aliasing is performed without color messup:

set anti aliasing in Settings Manager - Appearance - Fonts, annoying is that it requires to log out and back in to activate changes ...