Linux Virtual Delivery Agent

Audio features

Adaptive audio

Adaptive audio is enabled by default. It supports the following Citrix Workspace app clients:

  • Citrix Workspace app for Windows – 2109 and later versions
  • Citrix Workspace app for Linux – 2109 and later versions
  • Citrix Workspace app for Mac – 2109 and later versions

Adaptive audio falls back to legacy audio when you use a client not included on the list.

Adaptive audio dynamically adjusts audio sampling bitrates based on network conditions to enhance the audio experience, eliminating the need for manual configuration of audio quality policies on the VDA.

The following table shows a comparison between adaptive audio and legacy audio:

Adaptive audio Legacy audio
Max. audio sample rate: 48 kHz Max. audio sample rate: 8 kHz
Stereo channel Mono channel

Audio service considerations

The Linux VDA supports PipeWire in Debian 12.5, RHEL 9.x, Rocky Linux 9.x, and Ubuntu 24.04, where it is the default audio service. For the other distributions, continue using PulseAudio.

PulseAudio

  • Use PulseAudio 13.99 or later on RHEL 8.x and Rocky Linux 8.x.

PipeWire

The Linux VDA supports PipeWire only in Debian 12.5, RHEL 9.x, Rocky Linux 9.x, and Ubuntu 24.04. Here are some considerations to take:

  • If you have the Linux VDA version 2407 or later installed on Debian 12.5, RHEL 9.x, or Rocky Linux 9.x, you are using PipeWire.

  • If you have the Linux VDA version 2411 or later installed on Ubuntu 24.04, you are using PipeWire.

  • If you have a version of the Linux VDA earlier than 2407 installed on RHEL 9.x or Rocky Linux 9.x, you are using PulseAudio. To continue using PulseAudio, do nothing. To switch to PipeWire, complete the following steps:

    1. Replace the PulseAudio package with pipewire-pulseaudio:

      dnf swap --allowerasing pulseaudio pipewire-pulseaudio
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    2. Enable PipeWire-related services globally:

      systemctl --global --now enable pipewire pipewire-pulse pipewire-pulse.socket wireplumber
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    3. Restart the Linux VDA.

Loss tolerant mode for audio

The loss tolerant mode supports audio. This feature increases the user experience for real-time streaming and improves audio quality over EDT when users are connecting through networks with high latency and packet loss.

For more information about the loss tolerant mode and EDT, see Additional information in the Citrix Virtual Apps and Desktops documentation.

Enable the loss tolerant mode for audio feature

Loss tolerant mode for audio is disabled by default. To enable it, complete the following steps:

  1. Enable adaptive transport by setting the HDX adaptive transport policy. Adaptive transport is enabled by default.
  2. Enable adaptive audio by setting the Adaptive audio policy. Adaptive audio is enabled by default.
  3. Enable the loss tolerant mode (EDT unreliable transport) by setting the Loss tolerant mode for audio policy. Loss tolerant mode for audio is disabled by default.
  4. (Optional) For remote connections, Citrix Gateway Service is required.

Client requirements and settings

To use loss tolerant mode for audio, ensure that your Citrix Workspace app supports and is configured to enable this feature; otherwise, audio defaults to EDT Reliable transport.

The following are the minimum Citrix Workspace app versions that support loss tolerant mode:

  • Citrix Workspace app for Windows minimum version 2309
  • Citrix Workspace app for Linux minimum version 2311
  • Citrix Workspace app for Mac minimum version 2311

Audio quality enhancer for adaptive audio (preview)

Starting with the 2411 version, audio quality enhancer (V2) is added for adaptive audio.

Audio quality enhancer effectively manages short periods of packet loss and disruptions by intelligently reconstructing audio from previous samples, thus preventing noticeable degradation in quality. Furthermore, it intelligently and adaptively recovers lost audio packets, if and only when needed. It enables and disables itself adaptively when packet loss increases and decreases for a sustained period. Audio quality enhancer optimizes audio playback and recording quality in both good and bad network conditions.

To enable audio quality enhancer, complete the following steps on the VDA:

  1. Enable adaptive audio.
  2. Enable loss tolerant mode for audio.
  3. Enable the feature:

    sudo /opt/Citrix/VDA/bin/ctxreg create -k "HKLM\System\CurrentControlSet\Control\Citrix\VirtualChannels\Audio" -v "fEnablePacketLossConcealment" -t REG_DWORD -d 1 --force
     
    sudo /opt/Citrix/VDA/bin/ctxreg create -k "HKLM\System\CurrentControlSet\Control\Citrix\VirtualChannels\Audio" -v "fEnableNetStat" -t REG_DWORD -d 1 --force
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  4. Enable audio quality enhancer on the client as well, which is required to fully enable the feature. That is, audio quality enhancer must be enabled on both the VDA and Citrix Workspace app sides to function end-to-end for audio playback and recording.

To disable audio quality enhancer, complete the following steps on the VDA:

  1. Disable the feature:

    sudo /opt/Citrix/VDA/bin/ctxreg update -k "HKLM\System\CurrentControlSet\Control\Citrix\VirtualChannels\Audio" -v "fEnablePacketLossConcealment" -d 0 
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    sudo /opt/Citrix/VDA/bin/ctxreg update -k "HKLM\System\CurrentControlSet\Control\Citrix\VirtualChannels\Audio" -v "fEnableNetStat" -d 0
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  2. Disable audio quality enhancer on the client as well, which is required to fully disable the feature.

Support for multiple audio devices

Overview

Starting with Version 2311, the Linux VDA introduces an audio redirection feature. The feature allows multiple audio devices on the client machine where Citrix Workspace app is installed to be redirected to the remote Linux VDA session.

With the feature enabled:

  • All local audio devices on the client machine are displayed in a session. Instead of CitrixAudioSink (audio output) or CitrixAudioSource (audio input), the audio devices appear with their respective device names.

  • Audio devices within sessions update dynamically when you plug in or remove one.

Configuration

To use the feature, enable it on the Linux VDA and choose a supported Citrix Workspace app.

Enable the feature on the Linux VDA

Multiple audio device support is enabled by default. To disable or re-enable the feature, run the following commands, respectively:

sudo /opt/Citrix/VDA/bin/ctxreg update -k "HKLM\\System\\CurrentControlSet\\Control\\Citrix\\VirtualChannels\\Audio" -v "fEnableAudioRedirectionV4" -d "0"
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sudo /opt/Citrix/VDA/bin/ctxreg update -k "HKLM\\System\\CurrentControlSet\\Control\\Citrix\\VirtualChannels\\Audio" -v "fEnableAudioRedirectionV4" -d "1"
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Client requirements and settings

The feature is supported only for the following clients:

  • Citrix Workspace app for Windows
  • Citrix Workspace app for Linux minimum version 2212
  • Citrix Workspace app for HTML5 minimum version 2306
  • Citrix Workspace app for Chrome minimum version 2306
  • Citrix Workspace app for Mac minimum version 2311
  • Citrix Workspace app for Android minimum version 2405

Proper settings are required on Citrix Workspace app to make the feature function as expected. For more information, see the Citrix Workspace app documentation.

Known issues

Due to the issue with PulseAudio, attempts to switch between audio devices might fail in a Ubuntu 22.04 session. To address the issue, remove the PulseAudio configuration for the current session user from the VDA and then reopen the session. To remove the PulseAudio configuration, run the $ rm -r ~/.config/pulse command.