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

Microsoft’s xCloud game streaming seems to drop to a lower visual quality setting when running on Linux. The apparent downgrade across operating systems was noticed by a Reddit user over the holiday weekend and confirmed in Ars’ test this morning.

To compare how xCloud handles a Linux machine vs. a Windows machine, an Edge extension was used during 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

Tests were performed on the latest version of Microsoft Edge (version 103.0.1264.44, 64-bit) running on a Windows 10 PC. All tests were run on a wired internet connection that recorded download speeds of 120 Mbps and ~ 9 ms latency, according to spot tests on Fast.com.

A GIF that compares a corner of the image in two xCloud-streamed sessions where only the User-Agent string switches between them.

A GIF that compares a corner of the image in two xCloud-streamed sessions where only the User-Agent string switches between them.

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

What happens here?

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

That decline in Linux quality has led some to speculate that Microsoft is trying to reserve the best xCloud streaming performance for Windows machines in an attempt to attract more users to its own operating system. However, using a Macintosh User-Agent string provides streaming performance similar to that of Windows, which would seem like a big omission if this theory were true. Microsoft has also not released any kind of “best on Windows” -like marketing to promote xCloud streaming, which would apparently be a key component in trying to attract new Windows users.

(The difference in quality could be a spin-off attempt to get Linux users to switch to the Edge browser, where Clarity Boost offers the best possible quality. But that still would not fully explain why Windows users on other browsers, without Clarity Boost, too get better streaming quality than their Linux brothers.)

Others have suggested that the downgrade could simply be an error caused by Microsoft’s naive parsing of the User-Agent strings. This is because the User-Agent strings for Android browsers generally identify themselves as a version of Linux (“Linux; Android 11; HD1905,” for example). Microsoft’s xCloud code might just see “Linux” in the string, assume the user is running Android, and then automatically throttle the streaming quality to account for the (presumably) reduced screen size of an Android phone or tablet.

As Microsoft refuses to comment on Ars Technica, we are still stuck in theorizing what lies behind this apparent problem. For now, though, Linux users who want the best xCloud performance will switch to Microsoft Edge with Clarity Boost or at least falsify their User-Agent settings to pretend they’re running Windows.

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