Microsoft’s xCloud game streaming looks worse on Linux than Windows

Microsoft’s xCloud game streaming seems to dip into a lower visual quality setting when running on Linux. The apparent OS downgrade was noted by a Reddit user over the holiday weekend and confirmed during testing of Ars this morning.

To compare how xCloud handles a Linux machine versus a Windows machine, an Edge extension was used in testing to force the browser’s User-Agent string to present itself as a Linux browser:

  • Windows User-Agent tested: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.5060.66 Safari/537.36 Edg/103.0.1264.44
  • Linux User-Agent tested: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.27 Safari/537.36 Edg/102.0.1245.7

The tests were performed on the latest version of Microsoft Edge (build 103.0.1264.44, 64-bit) running on a Windows 10 PC. All tests were run over a wired internet connection recording download speeds of 120 Mbps and latency around 9ms, based on spot testing on Fast.com.

A GIF comparing a corner of the image in two sessions served by xCloud, only the User-Agent string changing between them.

The difference in streaming quality can be seen in the gallery above (expand the images to full screen for a better view). With Linux User-Agent, edges are generally less sharp and colors are a little more washed out. The difference is even more apparent if you zoom in on the Forza logo and menu text, which shows a significant reduction in clarity.

What is happening here?

Interestingly, the quality drop seems to go away if you enable “Clarity Boost, an Edge-exclusive feature that” provides[es] the optimal look and feel while playing Xbox games from the cloud,” according to Microsoft. This is great for Linux users who upgraded to Microsoft Edge when it launched on Linux last November. But Linux users who stick with Firefox, Chrome, or other browsers are currently stuck with seemingly reduced streaming quality.

This drop in Linux quality has led some to speculate that Microsoft is trying to reserve the best xCloud streaming performance for Windows machines in a bid to attract more users to its own operating system. But using a Macintosh User-Agent chain provides Windows-like streaming performance, which would seem like a big omission if that theory were true. Microsoft also hasn’t released any “better on Windows” type marketing to promote xCloud streaming, which is reportedly a key element in trying to attract new Windows users.

(The quality difference could be a backdoor attempt to get Linux users to switch to the Edge browser, where Clarity Boost offers the best possible quality. But that still wouldn’t fully explain why Windows users on other browsers, without Clarity Boost, also get better streaming quality than their Linux brethren.)

Others have suggested that the downgrade might just be a bug caused by Microsoft’s naïve parsing of User-Agent strings. This is because User-Agent strings for Android browsers typically identify as a version of Linux (“Linux; Android 11; HD1905”, for example). Microsoft’s xCloud code can just see the “Linux” in that string, assume the user is running Android, and then automatically limit the quality of the stream to account for the (presumably) small screen size of a phone or an Android tablet.

With Microsoft declining to comment on Ars Technica, we’re still stuck theorizing what’s behind this apparent issue. For now, however, Linux users who want the best xCloud performance will want to upgrade to Microsoft Edge with Clarity Boost or at least fake their user agent settings to pretend they’re running Windows.


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Steven L. Nielsen