Oct 05, 2016

Citrix HDX includes a broad set of technologies that provide a high-definition user experience.

At the device

HDX leverages the computing capacity of user devices to enhance and optimize the user experience. HDX MediaStream technology ensures users receive a smooth, seamless experience with multimedia content in their virtual desktops or applications. Workspace control enables users to pause virtual desktops and applications and resume working from a different device at the point where they left off.

On the network

HDX incorporates advanced optimization and acceleration capabilities to deliver the best performance over any network, including low-bandwidth and high-latency WAN connections.

HDX features adapt to changes in the environment, balancing performance and bandwidth by applying the best technologies for each unique user scenario, whether the desktop or application is accessed locally on the corporate network or remotely from outside the corporate firewall.

In the datacenter

HDX leverages the processing power and scalability of servers to deliver advanced graphical performance, regardless of the capabilities of the client device. Compressed multimedia information is sent directly to the user device in its native format.

HDX channel monitoring provided by Citrix Director displays the status of connected HDX channels on user devices.

HDX Insight, the integration of EdgeSight Network Inspector and EdgeSight Performance management with Director, captures data about ICA traffic and provides a dashboard view of real-time and historical details such as client-side and server-side ICA session latency, bandwidth use of ICA channels, and the ICA round trip time value of each session.

To experience HDX capabilities from your virtual desktop:

  • See how HDX delivers rich video content to virtual desktops: View a video on a web site containing high definition videos, such as http://www.microsoft.com/silverlight/iis-smooth-streaming/demo/.
  • See how Flash Redirection accelerates delivery of Flash multimedia content:
    1. Download Adobe Flash player (http://get.adobe.com/flashplayer/) and install it on both the virtual desktop and the user device.
    2. On the Desktop Viewer toolbar, click Preferences. In the Desktop Viewer Preferences dialog box, click the Flash tab and select Optimize content.
    3. To experience how Flash Redirection accelerates the delivery of Flash multimedia content to virtual desktops, view a video on your desktop from a web site containing Flash videos, such as YouTube. Flash Redirection is designed to be seamless so that users do not know when it is running. You can check to see whether Flash Redirection is being used by looking for a block of color that appears momentarily before the Flash player starts.
  • See how HDX delivers high definition audio:
    1. Configure your Citrix client for maximum audio quality; see the Receiver documentation for details.
    2. Play music files with a digital audio player (such as iTunes) on your desktop.

HDX provides a superior graphics and video experience for most users by default, with no configuration required. Citrix policy settings that provide the best out-of-the-box experience for the majority of use cases are enabled by default.

  • HDX automatically selects the best delivery method based on the client, platform, application, and network bandwidth, and then self-tunes based on changing conditions.
  • HDX optimizes the performance of 2D and 3D graphics and video.
  • HDX delivers a Windows Aero experience to virtual desktop users on any client.
  • HDX enables user devices to stream multimedia files directly from the source provider on the Internet or Intranet, rather than through the host server. If the requirements for this client-side content fetching are not met, media delivery falls back to Windows Media redirection to play media run-time files on user devices rather than the host server. In most cases, no adjustments to the Windows Media feature policies are needed.

Good to know:

  • For support and requirements information for HDX features, see System requirements for XenApp and XenDesktop 7.6 LTSR. Except where otherwise noted, HDX features are available for supported Windows Server OS and Windows Desktop OS machines, plus Remote PC Access desktops.
  • This content describes how to further optimize the user experience, improve server scalability, or reduce bandwidth requirements. For information about working with Citrix policies and policy settings, see the Citrix policies documents for this release.
  • For instructions that include working with the registry, use caution: editing the registry incorrectly can cause serious problems that may require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

Reduce the bandwidth needed for Windows desktops

By default, HDX delivers a highly responsive Windows Aero or Windows 8 desktop experience to virtual desktops accessed from supported Windows user devices. To do that, HDX leverages the graphics processing unit (GPU) or integrated graphics processor (IGP) on the user devices for local DirectX graphics rendering. This feature, named desktop composition redirection, maintains high scalability on the server. For details, see What to do with all these choices in http://blogs.citrix.com/2013/11/06/go-supersonic-with-xendesktop-7-x-bandwidth-supercodecs/.

To reduce the bandwidth required in user sessions, consider adjusting the following Citrix policy settings. Keep in mind that changing these settings can reduce the quality of the user experience.

  • Desktop Composition Redirection. Applies only to Windows Desktop OS machines accessed from Windows user devices and applies only to the composition of the Windows desktop. Application windows are rendered on the server unless the Citrix policy setting Allow local app access (LTSR: not supported) is Allowed.
  • Desktop Composition Redirection graphics quality. Uses high-quality graphics for desktop composition unless seamless applications or Local App Access (LTSR: not supported) are enabled. To reduce bandwidth requirements, lower the graphics quality.
  • Dynamic windows preview. Controls the display of seamless windows in Flip, Flip 3D, taskbar preview, and peek window preview modes. To reduce bandwidth requirements, disable this policy setting.

Improve the image quality sent to user devices

The following visual display policy settings control the quality of images sent from virtual desktops to user devices.

  • Visual quality. Controls the visual quality of images displayed on the user device: medium, high, always lossless, build to lossless (default = medium).
  • Target frame rate. Specifies the maximum number of frames per second that are sent from the virtual desktop to the user device (default = 30). In many circumstances, you can improve the user experience by specifying a higher value. For devices with slower CPUs, specifying a lower value can improve the user experience.
  • Display memory limit. Specifies the maximum video buffer size for the session in kilobytes (default = 65536 KB). For connections requiring more color depth and higher resolution, increase the limit. You can calculate the maximum memory required. Color depths other than 32-bit are available only if the Legacy graphics mode policy setting is enabled.

Improve video conference performance

HDX webcam video compression improves bandwidth efficiency and latency tolerance for webcams during video conferencing in a session. This technology streams webcam traffic over a dedicated multimedia virtual channel; this uses significantly less bandwidth compared to the isochronous HDX Plug-n-Play support, and works well over WAN connections.

Receiver users can override the default behavior by choosing the Desktop Viewer Mic & Webcam setting Don’t use my microphone or webcam. To prevent users from switching from HDX webcam video compression, disable USB device redirection with the policy settings under ICA policy settings > USB Devices policy settings.

HDX webcam video compression is enabled by default on Receiver for Windows but must be configured on Receiver for Linux. For more information, refer to the Receiver documentation. HDX webcam video compression requires that the following policy settings be enabled (all are enabled by default).

  • Client audio redirection
  • Client microphone redirection
  • Multimedia conferencing
  • Windows Media Redirection

If a webcam supports H.264 hardware encoding, HDX video compression uses the hardware encoding by default. Hardware encoding uses additional bandwidth and is not suitable for a low bandwidth network. To force software compression over low bandwidth networks, add the following DWORD key value to the registry key: HKCU\Software\Citrix\HdxRealTime: DeepCompress_ForceSWEncode=1.

Choose server scalability over user experience

For deployments where server scalability is of greater concern than user experience, you can use the legacy graphics system by adding the Legacy graphics mode policy setting and configuring the individual legacy graphics policy settings. Use of the legacy graphics system affects the user experience over WAN and mobile connections.