video-scaling should be set to auto

[Antoine Martin]

We already have speed and quality settings.
Those alone should be enough to drive the amount of video scaling applied.
We can keep the existing heuristics for when video scaling is set to a value.
We may want to expose this via the system tray menu and html5 advanced connection options.

[Antoine Martin]

New heuristics mostly done in r20366 - see commit message for details.
To revert to the previous behaviour, just use --video-scaling=VALUE instead of video-scaling=auto.

This new code targets 1080p at 25fps, more for "video" content, more for high quality or low speed, and less if quality is low or speed is high.
The details of the calculations can be shown with "-d scaling".

Still TODO:

• make target configurable? (XX MPixels/s?)
• take into account fullscreen and maximized flags
• UI updates

[Antoine Martin]

Not going to update the UI (we have too many controls already), and not going to use fullscreen or maximized flags (not sure which way they should favour).

@maxmylyn: FYI, the new heuristics should be easier to use (automatic) and will honour the dynamic quality and speed tuning more accurately.

Somewhat related to #1867, see also #1952.

[Antoine Martin]

Important fixups in r20520.

[J. Max Mena]

Noted and closing.

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/1951