Product Documentation

Flash Redirection policy settings

Sep 29, 2015

The Flash Redirection section contains policy settings for handling Flash content in user sessions.

Flash acceleration

This setting enables or disables Flash content rendering on user devices instead of the server. By default, client-side Flash content rendering is enabled.

Note: This setting is used for legacy Flash redirection with the Citrix online plug-in 12.1.

When enabled, this setting reduces network and server load by rendering Flash content on the user device. Additionally, the Flash URL compatibility list setting forces Flash content from specific websites to be rendered on the server.

On the user device, the Enable HDX MediaStream for Flash on the user device setting must be enabled as well.

When this setting is disabled, Flash content from all websites, regardless of URL, is rendered on the server. To allow only certain websites to render Flash content on the user device, configure the Flash URL compatibility list setting.

Flash background color list

This setting enables you to set key colors for given URLs.

By default, no key colors are specified.

Key colors appear behind client-rendered Flash and help provide visible region detection. The key color specified should be rare; otherwise, visible region detection might not work properly.

Valid entries consist of a URL (with optional wildcards at the beginning or end) followed by a 24-bit RGB color hexadecimal code. For example: http://citrix.com 000003.

Ensure that the URL specified is the URL for the Flash content, which might be different from the URL of the website. 

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On VDA machines running Windows 8 or Windows 2012, this setting might fail to set key colors for the URL. If this occurs, edit the registry on the VDA machine.

For 32-bit machines, use this registry setting:

[HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\HdxMediaStreamForFlash\Server\PseudoServer] "ForceHDXFlashEnabled"=dword:00000001

For 64-bit machines, use this registry setting:

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\HdxMediaStreamForFlash\Server\PseudoServer]
"ForceHDXFlashEnabled"=dword:00000001

Flash backwards compatibility

This setting enables or disables the use of original, legacy Flash redirection features with older versions of Citrix Receiver (formerly the Citrix online plug-in).

By default, this setting is enabled.

On the user device, the Enable HDX MediaStream for Flash on the user device setting must also be enabled.

Second generation Flash redirection features are enabled for use with Citrix Receiver 3.0. Legacy redirection features are supported for use with the Citrix online plug-in 12.1. To ensure second generation Flash redirection features are used, both the server and the user device must have second generation Flash redirection enabled. If legacy redirection is enabled on either the server or the user device, legacy redirection features are used.

Flash default behavior

This setting establishes the default behavior for second generation Flash acceleration.

By default, Flash acceleration is enabled.

To configure this setting, choose one of the following options:
  • Enable Flash acceleration. Flash Redirection is used.
  • Block Flash Player. Flash Redirection and server-side rendering are not used. The user cannot view any Flash content.
  • Disable Flash acceleration. Flash Redirection is not used. The user can view server-side rendered Flash content if a version of Adobe Flash Player for Windows Internet Explorer compatible with the content is installed on the server.

This setting can be overridden for individual Web pages and Flash instances based on the configuration of the Flash URL compatibility list setting. Additionally, the user device must have the Enable HDX MediaStream for Flash on the user device setting enabled.

Flash event logging

This setting enables Flash events to be recorded in the Windows application event log.

By default, logging is allowed.

On computers running Windows 7 or Windows Vista, a Flash redirection-specific log appears in the Applications and Services Log node.

Flash intelligent fallback

This setting enables or disables automatic attempts to employ server-side rendering for Flash Player instances where client-side rendering is either unnecessary or provides a poor user experience.

By default, this setting is enabled.

Flash latency threshold

This setting specifies a threshold between 0-30 milliseconds to determine where Adobe Flash content is rendered.

By default, the threshold is 30 milliseconds.

During startup, HDX MediaStream for Flash measures the current latency between the server and user device. If the latency is under the threshold, HDX MediaStream for Flash is used to render Flash content on the user device. If the latency is above the threshold, the network server renders the content if an Adobe Flash player is available there.

When enabling this setting, make sure the Flash backwards compatibility setting is also present and set to Enabled.

Note: Applies only when using HDX MediaStream Flash redirection in Legacy mode.

Flash video fallback prevention

This setting specifies if and how "small" flash content is rendered and displayed to users.

By default, this setting is not configured.

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

  • Only small content. Only intelligent fallback content will be rendered on the server; other Flash content will be replaced with an error *.swf.
  • Only small content with a supported client. Only intelligent fallback content will be rendered on the server if the client is currently using Flash Redirection; other content will be replaced with an error *.swf.
  • No server side content. All content on the server will be replaced with an error *swf.

To use this policy setting you should specify an error *.swf file. This error *.swf will replace any content that you do not want to be rendered on the VDA.

Flash video fallback prevention error *.swf

This setting specifies the URL of the error message which is displayed to users to replace Flash instances when the server load management policies are in use. For example:

http://domainName.tld/sample/path/error.swf

Flash server-side content fetching URL list

This setting specifies websites whose Flash content can be downloaded to the server and then transferred to the user device for rendering.

By default, no sites are specified.

This setting is used when the user device does not have direct access to the Internet; the server provides that connection. Additionally, the user device must have the Enable server-side content fetching setting enabled.

Second generation Flash redirection includes a fallback to server-side content fetching for Flash .swf files. If the user device is unable to fetch Flash content from a Web site, and the Web site is specified in the Flash server-side content fetching URL list, server-side content fetching occurs automatically.

When adding URLs to the list:
  • Add the URL of the Flash application instead of the top-level HTML page that initiates the Flash Player.
  • Use an asterisk (*) at the beginning or end of the URL as a wildcard.
  • Use a trailing wildcard to allow all child URLs (http://www.citrix.com/*).
  • The prefixes http:// and https:// are used when present, but are not required for valid list entries.

Flash URL compatibility list

This setting specifies the rules which determine whether Flash content on certain websites is rendered on the user device, rendered on the server, or blocked from rendering.

By default, no rules are specified.

When adding URLs to the list:
  • Prioritize the list with the most important URLs, actions, and rendering locations at the top.
  • Use an asterisk (*) at the beginning or end of the URL as a wildcard.
  • Use a trailing wildcard to refer to all child URLs (http://www.citrix.com/*).
  • The prefixes http:// and https:// are used when present, but are not required for valid list entries.
  • Add to this list websites whose Flash content does not render correctly on the user device and select either the Render on Server or Block options.