Xpra: Ticket #2052: downscaling server side - not just for video

When the client is using a desktop-scaling value lower than 1.0, we end up sending pixels that aren't all used client-side since we end up downscaling the picture to display it. (the render target is smaller than the picture the client receives)

It would be better if the client could tell the server about the scaling factor it is using then the server can:

Wed, 21 Nov 2018 10:18:01 GMT - Antoine Martin: status, summary changed

Wed, 20 Mar 2019 05:06:15 GMT - Antoine Martin: milestone changed

Milestone renamed

Sun, 20 Oct 2019 15:28:00 GMT - Antoine Martin:

See also #2458.

Thu, 30 Jan 2020 14:08:28 GMT - leo60228:

I'd argue that a major reason for this feature is shadowing. Currently, there isn't any way to use a shadowed desktop of a higher resolution than the client (at least in HTML5, the only client I use).

Sat, 15 Feb 2020 12:29:57 GMT - Antoine Martin: milestone changed

Tue, 09 Jun 2020 16:41:09 GMT - Antoine Martin:

Mostly done in:

Still TODO:

... at least in HTML5, the only client I use ...

@leo60228: there is no support for any window scaling in the HTML5 client, feel free to create a new ticket for that.

Wed, 10 Jun 2020 09:15:55 GMT - Antoine Martin: owner, status changed


@stdedos: I am re-assigning this ticket to you because you will see huge improvements in bandwidth usage and performance when using desktop-scaling values lower than 1.0. Feel free to just close. (this requires 4.1-r26668 or later on both client and server)

Wed, 10 Jun 2020 10:37:34 GMT - stdedos:

I can keep it open, and I cannot test it (my OS update plan for the server is late June to August)

Fri, 31 Jul 2020 15:45:00 GMT - Antoine Martin: owner, status changed

This has caused a regression for normal windows when we resize them up: the render-size does not get updated server side, and we end up downscaling when we don't need to..

Fri, 31 Jul 2020 16:13:09 GMT - Antoine Martin: status changed; resolution set

... the render-size does not get updated server side ..

Fixed in r27044.

Side effect: we now call update_encoding_selection from set_client_properties, even when the render-size is identical to the window size, which is a little bit of a waste.

stdedos: I'm going to close this ticket for 4.1 - try it when you get a chance.

Wed, 23 Sep 2020 04:46:06 GMT - Antoine Martin:

This causes problems with windows that don't fit the sizing constraints exactly: we end up downscaling them to the client render size (which is often only a few pixels off) and that makes it blurry. Also makes us use pillow (png) instead of the faster options (webp, jpeg). r27525 fixes that using a threshold.

Sat, 23 Jan 2021 05:40:54 GMT - migration script:

this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2052