Tearing/sync issues

[iuc6]

Hi,

I’m testing out NoMachine Terminal Server as an alternative to Terminal Services to provide remote browser functionality. On playback of videos on Youtube with NoMachine, I’ve found tearing and video sync issues with both Linux and Windows clients. Any suggestions as to what may be the best place to start with resolving this issue?

Thanks,

Rich

[fra81]

Hi Rich,

please provide more info about the Linux distribution in use on the server and the version of the browser, so that we can test the same in our labs. Please also tell if you are running the browser in a Custom session in Floating window mode (single application). Then you can check the CPU usage on client and server side, as well as the available network bandwidth, in order to search for possible bottlenecks.

[iuc6]

Hi,

The Linux Distribution is CentOS 6.7 x86_64. The version of the browser is Chrome 53.0.2785.89; Firefox version is 45.1.0, though Firefox is unusably slow. Hardware acceleration is enabled in both, though I’ve also tried disabling it. The browser is running as a floating window. The CPU usage is low on the client side on both Windows and Linux (less than 10%). The server has a quad core 3.7Ghz CPU, hyperthreaded. It uses about 25% of the total CPU resources. The server has 10Gbit, and the clients are gigabit. dstat shows max 2Mbit of traffic when streaming HD video from server to client and the network is not at all congested. Indeed, I have set up a 2nd instance on another machine on the same LAN and I get the same issues. When I test with terminal services, there are none of these issues. I have increased the framerate to 60FPS and that seemed to help with the tearing, but it still exhibits the video pausing, then speeding up, though audio is in sync. Interestingly, it doesn’t seem to affect the CPU usage on the server.

Please let me know if you need any further details.

Thanks for the help,

Rich

[iuc6]

On further testing, I noticed that tearing is still present on Windows 🙁

[fra81]

After further testing in our labs, I can say that this tearing problem is due to the limitations of the display server that NoMachine uses to render application’s windows in floating window mode on Windows. We are aware of that, and such problems will be solved by this Feature Request: https://www.nomachine.com/FR02N03010.

Note that this problem does not apply to other types of session, so you could run the browser is a virtual desktop for best performance. Additionally, you can disable the ‘X11 vector graphics mode’ in order to use the mode that is specifically optimized for multimedia content and rich graphics.

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