Linux Virtual Delivery Agent

Audio features

Adaptive audio

With adaptive audio, you don’t need to manually configure the audio quality policies on the VDA. Adaptive audio optimizes settings for your environment and replaces obsolete audio compression formats to provide an excellent user experience.

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.

Audio service considerations

The Linux VDA supports PipeWire in Debian 12.x 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.x, 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.x, 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.

  • If the system language of your Linux machine is not English and the audio service is PipeWire, follow these steps to ensure audio functionality:

    1. Open the file located at: /etc/xdg/autostart/ctxaudio.desktop

    2. Locate the following line: Exec=/opt/Citrix/VDA/bin/ctxaudio

    3. Replace it with: Exec=env LC_ALL=C /opt/Citrix/VDA/bin/ctxaudio

    This change forces ctxaudio to use the C locale, ensuring compatibility with PipeWire in non-English environments.

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 enabled by default. If it is disabled, complete the following steps to re-enable it:

  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.
  4. For direct connections, enable DTLS on VDAs is required.
  5. For remote connections, EDT loss tolerant mode must also be supported on the Citrix Gateway Service or NetScaler Gateway.

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 Diagnostic Command Line Tool

The audio diagnostic command line tool on the VDA can be used to query session data related to audio policies, configuration, and data transport.

Usage

Open a command prompt and run ctxaudiosession from the /opt/Citrix/VDA/bin folder.

Running the tool will display all active ICA session(s) audio information and device redirection status for the current user.

Output

The tool outputs various configuration settings that can help diagnose audio-related issues within a session.

Section Description
Warning Audio service warning messages for device statuses, transport type, audio codec, etc.
State Information Audio state, version, codecs, transport applied to the current session(s), etc.
Policy Settings Audio policies applied to the current session(s).
Local Settings Audio-related configuration stored in the registry or local settings.
Capabilities Audio capabilities results between the CWA and VDA.
Sound Devices Device names, their roles, and their running statuses in the session(s).

Audio Quality Enhancer to Improve Audio Performance

Starting with the 2507 version, audio quality enhancer is enabled by default for adaptive audio.

Audio quality enhancer maintains clear audio during brief network disruptions. This feature adapts to the network conditions to ensure consistent audio performance during playback and recording.

Note:

Both adaptive audio and loss tolerant mode for audio must be enabled for this feature to work.

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.