Multimedia policy settings 编辑

The Multimedia section includes policy settings for managing streaming HTML5 and Windows audio and video in user sessions.

Warning

Editing the registry incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix can’t guarantee that problems resulting from the incorrect use of the Registry Editor can be solved. Use the Registry Editor at your own risk. Be sure to back up the registry before you edit it.

Multimedia policies

By default, all multimedia policies set on the Delivery Controller are stored in these registries:

Machine policies:

HKEY_LOCAL_MACHINE\Software\Policies\Citrix\MultimediaPolicies

User policies:

HKEY_LOCAL_MACHINE\Software\Policies\Citrix{User Session ID}\User\MultimediaPolicies

To locate the current user session ID, issue the qwinsta command on the Windows command line.

HTML5 video redirection

Controls and optimizes the way Citrix Virtual Apps and Desktops servers deliver HTML5 multimedia web content to users.

By default, this setting is disabled.

In this release, this feature is available for controlled webpages only. It requires the addition of JavaScript to the webpages where the HTML5 multimedia content is available, for example, videos on an internal training site.

To configure HTML5 video redirection:

1. Copy the file, HdxVideo.js, from %Program Files%/Citrix/ICA Service/HTML5 Video Redirection on the VDA install to the location of your internal webpage.
2. Insert this line into your webpage (if your webpage has other scripts, include HdxVideo.js before those scripts): <script src="HdxVideo.js" type="text/javascript"\></script>

Note: If HdxVideo.js isn’t in the same location as your webpage, use the src attribute to specify the full path to it.

Consider that the JavaScript isn’t added to your controlled webpages and the user plays an HTML5 video. In this case, Citrix Virtual Apps and Desktops default to server side rendering.

For redirection of HTML5 videos to work, allow Windows Media Redirection. This policy is mandatory for Server Fetch Client Render, and necessary for Client Side Fetching. Client Side Fetching in turn also requires Windows Media client-side content fetching to be Allowed.

Microsoft Edge doesn’t support this feature.

HdxVideo.js replaces the browser HTML5 Player controls with its own. To check that the HTML5 video redirection policy is in effect on a certain website, compare the player controls to a scenario where the HTML5 video redirection policy is Prohibited:

(Citrix custom controls when the policy is Allowed)

(Native webpage controls when the policy is Prohibited or not configured)

The following video controls are supported:

• play
• pause
• seek
• repeat
• audio
• full screen

You can view an HTML5 video redirection test page at https://www.citrix.com/virtualization/hdx/html5-redirect.html.

TLS, HTML5 video redirection, and browser content redirection

You can use HTML5 video redirection to:

• Redirect videos from HTTPS websites
• Or
• Browser content redirection to redirect the entire website

The JavaScript injected into those websites must establish a TLS connection to the Citrix HDX HTML5 Video Redirection Service (WebSocketService.exe) running on the VDA. Citrix HDX HTML5 Video Redirection Service in the certificate store on the VDA generates two custom certificates to:

• Achieve video redirection
• Maintain the TLS integrity of the webpage

HdxVideo.js uses Secure WebSockets to communicate with WebSocketService.exe running on the VDA. This process runs as a Local System account, and does SSL termination and user session mapping.

WebSocketService.exe is listening on 127.0.0.1 port 9001.

Limit video quality

This setting applies only to Windows Media and not to HTML5. It requires you enable Optimization for Windows Media multimedia redirection over WAN.

This setting specifies the maximum video quality level allowed for an HDX connection. When configured, maximum video quality is limited to the specified value, ensuring that multimedia Quality of Service (QoS) is maintained within an environment.

By default, this setting isn’t configured.

To limit the maximum video quality level allowed, choose one of the following options:

• 1080p/8.5mbps
• 720p/4.0mbps
• 480p/720kbps
• 380p/400kbps
• 240p/200kbps

Playing multiple videos simultaneously on the same server consumes large amounts of resources and can impact server scalability.

Microsoft Teams redirection

This setting enables optimization of Microsoft Teams, based on the HDX technology.

If this policy is enabled, and you’re using a supported version of Citrix Workspace app, this registry key is set to 1 on the VDA. The Microsoft Teams application reads the key to load in VDI mode. Note it is not required to set the registry key manually.

HKEY_CURRENT_USER\Software\Citrix\HDXMediaStream

Name: MSTeamsRedirSupport

Value: DWORD (1 - on, 0 - off)

Note:

Consider that you’re using version 1906.2 VDAs or later with older versions of the Controller, which do not have the policy available in Studio. An example for an older version of the controller is version 7.15. In this case, HDX optimization is enabled by default on the VDA. If the Workspace app version is 1907 or later, Microsoft Teams launches in optimized mode. For information about caveats in mixing 7.15 LTSR Controllers and CR VDAs, see Knowledge Center article CTX205549.

In this case, to disable the feature for specific users, you can override the registry setting. Override the registry settings by using a group policy to apply a logon script to the user’s organizational unit.

By default, Microsoft Teams redirection is enabled.

Multimedia conferencing

This setting allows or prevents the use of optimized webcam redirection technology by video conferencing applications.

By default, video conferencing support is allowed.

When adding this setting to a policy, verify that the Windows Media redirection setting is present and set to Allowed (the default).

When using Multimedia conferencing, verify that the following conditions are met:

• Manufacturer-supplied drivers for the webcam used for multimedia conferencing are installed on the client.
• Connect the webcam to the user device before starting a video conferencing session. The server uses only one installed webcam at any given time. If multiple webcams are installed on the user device, the server attempts to use each webcam in succession. This attempt continues until a video conferencing session is created successfully.

This policy isn’t needed when redirecting the web cam using Generic USB redirection. In that case, install the webcam drivers on the VDA.

Optimization for Windows Media multimedia redirection over WAN

This setting applies only to Windows Media and not to HTML5. The setting enables the following:

• Real-time multimedia transcoding
• Allows audio and video media streaming to mobile devices over degraded networks
• Enhances the user experience by improving how Windows Media content is delivered over a WAN.

By default, the delivery of Windows Media content over the WAN is optimized.

When adding this setting to a policy, make sure the Windows Media Redirection setting is present and set to Allowed.

When this setting is enabled, real-time multimedia transcoding is deployed automatically as needed to enable media streaming. Also, provide a seamless user experience even in extreme network conditions.

Use GPU for optimizing Windows Media multimedia redirection over WAN

This setting applies only to Windows Media and enables real-time multimedia transcoding to be done in the Graphics Processing Unit (GPU) on the Virtual Delivery Agent (VDA). It improves server scalability. GPU transcoding is available only if the VDA has a supported GPU for hardware acceleration. Otherwise, transcoding falls back to the CPU.

Note: GPU transcoding is supported only on NVIDIA GPUs.

By default, using the GPU on the VDA to optimize the delivery of Windows Media content over the WAN is prohibited.

When adding this setting to a policy, make sure that the following settings are present and set to Allowed:

• Windows Media redirection
• Optimization for Windows Media multimedia redirection over WAN settings

Windows Media fallback prevention

This setting applies to browser content redirection, HTML5, and Windows Media. For it to support HTML5, set the HTML5 video redirection policy to Allowed.

Administrators can use the Windows Media fallback prevention policy setting to specify the methods that is attempted to deliver streamed content to users.

By default, this setting isn’t configured. When the setting is set to Not Configured, the behavior is the same as Play all content.

To configure this setting, choose one of the following options:

• Play all content. Attempt client-side content fetching, then Windows Media Redirection. If unsuccessful, play content on the server.
• Play all content only on client. Attempt client-side fetching, then Windows Media Redirection. If unsuccessful, the content does not play.
• Play only client-accessible content on client. Attempt only client-side fetching. If unsuccessful, the content does not play.

When the content does not play, the following error message displays in the player window (for a default duration of 5 seconds):

"Company has blocked video because of lack of resources"