The Horizon Blast ADMX template file (hzn_blast.admx) contains policy settings for the Horizon Blast display protocol. After you apply the policy, the system stores the settings in the registry key HKLM\Software\Policies\Omnissa\Horizon\Blast\Config.
These settings apply to Horizon Web Client and all Omnissa Horizon Client platforms.
For information relating to Horizon Blast support for 120 FPS, see Additional Max Frame Rate information.
Horizon Blast Policy Settings
| Setting | Description |
|---|---|
| Audio playback | Specifies whether audio playback is activated for remote desktops. This setting is to activate audio playback. |
| Audio Volume Level Forward | Controls whether the volume level of the audio output device in the virtual desktop should be forwarded and applied to the physical devices on the client host. Note: Changing the client-side volume level is not applied to remote sessions. This feature applies to VDI sessions only. |
| Blast Codec Quality | The minimum and maximum values of the Quantization Parameter (QP) control the image quality of the remoted display when using Horizon Blast Codec compression. The QP values range [1-8] and roughly map to the JPEG quality value in the range [20-88]. This quantization applies to non-text regions and has no bearing on text compression. The highest QP value is added to the low JPEG quality configuration. If the highest QP value is zero, the low JPEG quality configuration overrides the configuration. The minimum QP is mapped to the high JPEG quality configuration, and a value of zero for minimum QP results in overriding the configuration by the high JPEG quality configuration. |
| Blast Encoders Global Quality | This setting controls the remoted display image quality level across all Horizon Blast encoders.
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| Blast Optimizer | A single configuration for Horizon Blast users to choose between defaults that provide a better user experience or resource efficiency.
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| Build to Lossless | When this setting is activated, Horizon Blast uses build-to-lossless mode, which results in the highest display quality. This mode disables any GPU encoding acceleration and potentially increases CPU usage and network bandwidth consumption on both the client and agent. If this setting is not activated or not configured, the build-to-lossless is not available. This setting is not configured by default. |
| Cookie Cleanup Interval | Determines how often, in milliseconds, the system deletes cookies associated with inactive sessions. The default is 100 ms. |
| Cursor warping | When this setting is activated, the cursor warping feature is activated. When activated and the mouse is in absolute mode, the remote agent detects sudden cursor movements and reflects them to the client by moving the local cursor. If this setting is not activated, the client ignores sudden cursor movements in the remote agent. This setting is deactivated by default. |
| DSCP Marking | When activated or not configured, this setting allows Differentiated Services Code Point (DSCP) values to be established in outgoing Horizon Blast network traffic, as specified by the various individual settings for each network hop. When deactivated, DSCP values are not established in Horizon Blast network traffic.
When activated, you can set a numeric value in the range 0-63 for the following network connections:
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| Enable Vvc Raw Channel | Enables or disables the Vvc Raw Channel used by Blast for MKS and audio. When enabled, both MKS and audio data are sent over a separate raw channel connection, no matter which Blast connection is used. This raw channel carries the VNC protocol payload and supports beat (Blast Extreme Adaptive Transport)), tcp, or vvc (default) as transport protocols. To configure transport mode, use the RawChannelType registry key. The registry value is not created by default and must be added manually. This setting is available starting with Horizon Agent 2506. |
| Encoder Image Cache Size (KB) | Maximum size of the encoder image cache.
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| H.264 | Specifies whether to use H.264 encoding or JPEG/PNG encoding. The default is to use H.264 encoding. With NVIDIA VideoSDK 13, H.264 now supports 10-bit encoding and YUV 4:2:2 for improved color fidelity and compression efficiency. Legacy SDK 8 is no longer supported. |
| H.264 High Color Accuracy | Increases color accuracy when using H.264 encoding. Select from YUV 4:4:4 (highest color accuracy), YUV 4:2:2 (new in SDK 13), or 4:2:0. This setting may reduce performance at very high resolutions or with multiple monitors. Hardware GPU acceleration is required to take full advantage of 10-bit or YUV 4:2:2 modes. |
| H.264 | Specifies whether to use H.264 encoding or JPEG/PNG encoding. The default is to use H.264 encoding. |
| H.264 High Color Accuracy | Increases color accuracy when using H.264 encoding by using the YUV 4:4:4 colorspace instead of 4:2:0. This setting might result in degraded performance at very high resolutions or with multiple monitors. |
| H.264 Quality | Specifies the image quality for the remote display configured to use H.264 encoding. You can specify the minimum and maximum quantization values that determine how much an image is controlled for lossy compression. You can specify a minimum quantization value for the best image quality. You can specify a maximum quantization value for the lowest image quality. You can specify the following settings:
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| HEVC High Color Accuracy | Activate this setting to request increased color accuracy by using the YUV 4:4:4 colorspace instead of 4:2:0 with HEVC encoding. The client requires hardware HEVC 4:4:4 support for this policy to take effect. This setting is activated by default. |
| HEVC | Activate or do not configure this setting to allow HEVC encoding for remoting the desktop. Deactivate this setting to use H.264 or JPEG/PNG for encoding. |
| HTTP Service | Specifies the port that is used for secure communication (HTTPS) between the Access Point appliance and a desktop. The firewall must be configured to have this port open. The default is 22443. |
| Image Quality | Specifies the image quality of the remote display. You can specify two low-quality settings, two high-quality settings, and a mid-quality setting. The low-quality settings are for areas of the screen that change often, for example, when scrolling occurs. The high-quality settings are for areas of the screen that are more static, resulting in a better image quality. You can specify the following settings:
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| Keyboard locale synchronization | Specifies whether to synchronize a client's keyboard locale list and default keyboard locale to the remote desktop or application. If this setting is activated, synchronization occurs. This setting applies to Horizon Agent only. |
| Max Frame Rate | Specifies the maximum rate of screen updates. Use this setting to manage the average bandwidth that users consume. The default is 30 updates per second. |
| Max Session Bandwidth | Specifies the maximum bandwidth, in kilobits per second (kbps), for a Horizon Blast session. The bandwidth includes all imaging, audio, virtual channel, USB, and Horizon Blast control traffic. The default is 1 Gbps. |
| Max Session Bandwidth kbit/s Megapixel Slope | Specifies the maximum bandwidth slope, in kilobits per second (kbps), reserved for a Horizon Blast session. The minimum value is 100. The maximum value is 100000. The default value is 6200. |
| Min Session Bandwidth | Specifies the minimum bandwidth, in kilobits per second (kbps), reserved for a Horizon Blast session. The default is 256 kbps. |
| PNG | If you activate or do not configure this setting, PNG encoding is available for remote sessions. If you deactivate this setting, only JPEG encoding is used for encoding in JPEG/PNG mode. This policy does not apply when the H.264 encoder is active. This setting is not configured by default. |
| Raw Channel Protocol Mode | Specifies the transport protocol (TCP or BEAT) used by the Vvc Raw Channel. This setting can be used to pin the MKS and audio payload to a specific transport protocol TCP or BEAT (UDP). Valid values are beat, tcp, or vvc (default). The registry value is not created by default and must be added manually. Available in Horizon Agent 2506 and later. |
| Screen Blanking | Specifies whether to have the desktop VM's console show the actual desktop that the user sees or to show a blank screen when the desktop has an active session. The default is to show a blank screen. |
| UDP Protocol | Specifies whether to use the UDP or the TCP protocol. The default is to use the UDP protocol. The setting takes effect when a user performs a session login-logoff on the Horizon Agent machine on which the registry key exists. This setting does not apply to Horizon Web Client, which always uses the TCP protocol. |
Vvc Raw Channels Support in Horizon Blast
Vvc Raw Channels are a newer version of Vvc channels intended for a single data stream rather than multiplexed streams, using dedicated network connections. This model is used by Blast MKS and Audio unified stream, and it improves performance and scalability.
Starting with Horizon Agent 2506, Vvc Raw Channels are enabled by default. This feature can be disabled using either a GPO or a local Windows Agent configuration registy key. GPO settings are recommended for consistent management across all agents, while the registy-based method offers per-agent control when GPO is not used.
Supported Platforms
The following outlines current platform support and limitations for Vvc raw channels:
- Windows Agent only. Linux agents are not supported.
- Deployments using Blast Secure Gateway (BSG) are supported with UAG only. BSG running on Connection Server is not supported.
- Vvc raw channels are supported on desktop clients for Windows, Linux, and Mac, and on mobile clients.
- Both the client and agent must be using Horizon 2506 or later. For Mac clients, Mobile clients and BSG, the version must be 2512 or later.
- Raw channels are disabled during collaboration sessions or when QoS is set on the network connection.
Windows Agent Configuration via Group Policy
GPO Setting Name: Vvc Raw Channels
Registry Path: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Omnissa\Horizon\Blast\vvc\RawChannelsEnabled
Type: REG_SZ
Values:
- 1 – Enabled (default)
- 0 – Disabled
If you enable or do not configure this policy setting, the Vvc Raw Channels feature is enabled. If you disable the setting, the feature is turned off.
When this Group Policy Object (GPO) setting is present, it takes precedence over the non-GPO registry key in HKLM\Software\Omnissa\Horizon\Blast\vvc\RawChannelsEnabled.
Windows Agent Configuration via Registry
VVC Raw Channels (feature killswitch)
Registry Path: HKLM\Software\Omnissa\Horizon\Blast\vvc\RawChannelsEnabled
Type: REG_SZ
Values:
- 1 – Enabled (default)
- 0 – Disabled
This registry key allows per-agent control of the Vvc Raw Channels feature in environments where GPO enforcement is not applied. If the GPO setting is not configured, this registry value determines the feature behavior.
If the GPO setting is not configured, this value determines whether the feature is enabled. If both are present, the GPO setting takes precedence.
Raw Channel Transport Protocols
The Vvc Raw Channel supports three protocol modes for transporting real-time data. This is controlled by using the optional registry value RawChannelType and can be either tcp, beat or vvc. If this value is not set, the default behavior is used: raw channels start with BEAT and automatically switch to TCP if network conditions permit.
Raw Channel Protocol Mode
Registry Path: HKLM\Software\Omnissa\Horizon\Blast\vvc\rawChannelType
Type: REG_SZ
Values:
vvc(default) - Raw channels initially use BEAT and automatically switch to TCP if network conditions support it.beat(Blast Extreme Adaptive Transport)tcp
Note: None of the above registry values are created by the Horizon Agent installer. They must be added manually if you want to override the default behavior.
Additional Consideration: Client-Side Configuration
Although rarely used, client-side support for Vvc Raw Channels can be toggled using the same key and value:
Client Registry Path: HKLM\Software\Omnissa\Horizon\Blast\vvc\RawChannelsEnabled
Type: REG_SZ
Values:
- 1 – Enabled (default)
- 0 – Disabled
BEAT Payload Size Configuration
The Configurable BEAT Payload Size feature allows setting the maximum UDP datagram size in BEAT to prevent connection instability, and can be configured on either the client or the agent.
BEAT Payload Size Configuration
Registry Path: HKLM\Software\Omnissa\Horizon\Blast\Config\UDPPathMTU
Type: REG_SZ
Values:
0 - Killswitch. Forces both sides to use the default (1328).
-1 - (default) Use peer's (client) configured value. If both client and agent are configured to use -1, the existing UDP Path MTU default value (1328) is used.
Minimum: 576 and Maximum: 1328 (rounded down to nearest multiple of 4).
Note: It applies to both the Windows agent and the Windows client.
Additional Consideration: Client-Side Configuration
The configuration can also be done by the config file.
Windows:
C:\ProgramData\Omnissa\Horizon\Omnissa Horizon\config.iniRemoteDisplay.udpPathMTU=<value>- Note: If the file doesn't exist, create a new file with the name config.ini.
Mac:
~/Library/Preferences/Horizon/configRemoteDisplay.udpPathMTU=<value>
Linux
/etc/omnissa/configRemoteDisplay.udpPathMTU=<value>
Note: The entry is the same for Linux client and Linux agent.
Note: It cannot be configured on mobile clients.
Applying Horizon Blast Policy Settings
If the following Horizon Blast policies change during a client session, Horizon Client detects the change and immediately applies the new setting.
H.264Audio PlaybackMax Frame RateImage QualityAudio Volume Level ForwardMax Session BandwidthMin Session Bandwidth
The Max Session Bandwidth and Min Session Bandwidth settings take effect when a user performs a connect or login to a session on the Horizon Agent machine on which the setting exists. Any change made to these settings during a client session applies immediately.
For all other Horizon Blast policies, Microsoft GPO update rules apply. GPOs can be updated manually or by restarting the Horizon Agent machine. For more information, see the Microsoft documentation.
Additional Max Frame Rate information
To achieve 120 FPS in a Horizon session, the client machine must have supported hardware.
To enable this feature, you need to add an advanced configuration option on the vGPU VMs in vCenter.
With the VM powered off, navigate to VM > Edit Settings > Advanced Parameters, then add pciPassthru0.cfg.frl_config with a value of 120.
To support 120fps, additional network bandwidth is required. Add the MaxBandwidthKbpsPerMegaPixelSlope registry key and set its value to 0, in addition to setting the EncoderMaxFPS registry in the Windows agent VM.
To enable this feature in a Linux agent VM, set the RemoteDisplay.maxFPS configuration key.
Windows 10 or Windows 11
- Ensure the machine has a monitor and GPU that support 120 FPS.
- Set the monitor capable of 120 FPS as the primary display.
- Go to System > Display > Advanced Display Settings and select 120 Hz from the Refresh Rate dropdown menu.
Note: Some monitors may limit 120fps support to specific resolutions, such as 2560x1440 or 1920x1080.
OSX
- The machine must support ProMotion.
- Set ProMotion in System Settings > Displays from the Refresh Rate dropdown menu.
- For more information, see Apple Support article Change the refresh rate on your MacBook Pro or Apple Pro Display XDR.
Linux
- Ensure the machine has a monitor and GPU that support 120 FPS.
- Consult your Linux distribution and GPU vendor guides for configuration details.
Troubleshooting
- Ensure there are no conflicting settings in group policies and registry policy locations for `EncoderMaxFPS` or `MaxBandwidthKbpsPerMegaPixelSlope` settings.
- Verify that registry entries are correctly formatted as strings and spelled accurately.
- Nvidia GRID 16.1 components have a known issue with the frame rate limiter, causing it to be capped at 60fps regardless of configured settings. See Cannot disable Frame Rate Limiter on L40.
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