windowing/gbm: add option to limit gui size

[Kwiboo]

Description

This PR adds a new video setting Limit GUI Size for GBM platform that can be used on devices / SoCs with weaker GPUs in order to improve user experience by limiting the gui plane size used.

This setting is <visible>false</visible> by default and is only intended to be set visible or forced in appliance.xml for devices / SoCs with weaker GPUs.

Motivation and Context

Allows for video to render in 4K using direct-to-plane rendering and having a 720/1080p gui plane for osd / subtitles.

How Has This Been Tested?

This has been included in LibreELEC Rockchip, Allwinner and mainline Amlogic builds for a long time.

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[Kwiboo]

This is now used on Allwinner, Amlogic, Rockchip and RPi4 in LibreELEC. Should be ready for merging unless we want to add support for using 720p as gui size when a 1080p resolution is used, current limits only kicks in when resolution is above 1080p.

[Kwiboo]

I plan on merging this unless anyone have any objection, ping @lrusak

Windows UWP build seems to have failed due to a Python3 issue.

[ksooo]

I plan on merging this unless anyone have any objection, ping @lrusak

Wait! Are you aware that we already have a very similar setting for Android and rpb? I suggest to reuse this setting and its values for gbm.

https://github.com/xbmc/xbmc/blob/master/system/settings/android.xml#L15-L28

https://github.com/xbmc/xbmc/blob/master/addons/resource.language.en_gb/resources/strings.po#L20809-L20812

https://github.com/xbmc/xbmc/blob/master/addons/resource.language.en_gb/resources/strings.po#L20193-L20196

https://github.com/xbmc/xbmc/blob/master/addons/resource.language.en_gb/resources/strings.po#L20834-L20860

https://github.com/xbmc/xbmc/blob/master/addons/resource.language.en_gb/resources/strings.po#L20952-L20955

[Kwiboo]

Yes I am aware, I added a new option and labels because although the videoscreen.limitgui is used for similar purposes the limitations is not applied in the same way.

To my knowledge the videoscreen.limitgui is a hard limit that always applies to GUI regardless of what screen resolution is used.
E.g. with the 720p option selected the GUI would be limited to 720p for any screen resolution above 720p.

This new option was originally intended to only apply for screen resolutions above 1080p (1440p, 2160p etc).
E.g. with the 720p option selected and a screen resolution of 2160p, the GUI would be limited to 720p, and for a 1080p screen resolution the GUI would not be limited and would instead use a 1080p buffer.

The reasoning behind this is that for some embedded devices (RK3328) there is only enough memory bandwidth to display a 2160p video buffer and a 720p gui buffer at the same time for 2160p screen resolutions with refresh rates above 30hz. Using a 2160p video buffer and a 1080p gui buffer may work with 2160p@30hz or less hz. Other devices (RK3399) may have enough memory bandwidth to display 2x 2160p buffers but are instead limited by GPU power and can only cope with GUI at 2160p up to 30fps.

Any suggestions on how to merge both these two options into one is welcomed!

[ksooo]

I think you should at least reuse the strings from strings.po.

[phunkyfish]

@Kwiboo do you want to progress this, close it or put it on the backburner?

[lrusak]

Updated PR here: https://github.com/jernejsk/xbmc/tree/gbm-limitguisize
It seems I have no rights to push to kwiboo's branch.

@jernejsk I tried also but couldn't get it to work. I think it's because his xbmc repo is a fork of plexinc/plex-home-theater-public and not xbmc/xbmc

[Kwiboo]

Thanks @jernejsk, I have pushed your branch now

[lrusak]

added @ksooo again to check if the changes make him happy 😄

[lrusak]

good to go other than that small string change

[jernejsk]

Any objection against merging this in few days?