Secure Global Desktop 4.31 Administration Guide > Applications, documents and hosts > Enabling sound in X applications

Enabling sound in X applications

Secure Global Desktop Administrators can enable sound in X applications accessed using Secure Global Desktop (SGD). To be able to hear sound in X applications, you may have to configure the client device, the SGD UNIX audio service, the application server and the X application. How you do this is described in the following sections.

Configuring the client device

To be able to hear sound in an X application, the client device must be capable of playing sound.

Users with Solaris Operating System (Solaris OS) or Linux client devices must also have read and write access to the following audio devices:

The /dev/audio device on Solaris Operating System (Solaris OS) platforms.
The /dev/dsp device on Linux platforms.

When running an X application through SGD, users must use a Secure Global Desktop client that can play sound. The Sun Secure Global Desktop Client on all platforms can play sound. See the Secure Global Desktop Release Notes for details of which classic clients can play sound.

Audio mixing on the client device is supported. On Solaris OS workstations, Microsoft Windows and Mac OS X client devices, the client hardware performs the mixing. On Linux and Sun Ray client devices, the Enlightened Sound Daemon (ESD or EsounD) is required to perform mixing.

Configuring the SGD UNIX audio service

To be able to hear sound in an X application, the SGD UNIX audio service must be enabled in the array. The UNIX audio service is disabled by default.

You enable the UNIX audio service as follows:

On the Array properties panel in Array Manager, check the Enable UNIX audio service box.
On the command line, run the tarantella config edit --array-unixaudio 1 command.

Note The audio service only takes effect for new webtop sessions. Users must log out of Secure Global Desktop and log back in again to enable sound in their current X application sessions.

You can also set the audio quality. The default is Medium Quality Audio (sample rate 22.05kHz), which should be sufficient in most cases.

Configuring the application server

To be able to hear sound in an X application, you must install and run the audio module of the SGD Enhancement Module on the application server.

Note If you are using zones on Solaris OS platforms, the audio module must be installed in the global zone.

See the Secure Global Desktop Installation Guide for instructions on installing the audio module. If you did not install the audio module when you installed the Enhancement Module, you must uninstall the Enhancement Module and install it again.

If the audio module is installed, you start the audio service with the install_dir/bin/tem startaudio command. By default, install_dir is /opt/tta_tem.

The audio module installs the SGD audio daemon and audio driver emulator.

Note As the audio module includes an audio driver emulator, the application server itself does not actually need to have a soundcard.

The audio daemon supports the following audio data formats:

u-law and A-law with 8-bit precision
16-bit linear Pulse-code modulation (PCM)

The audio daemon supports any sample rate from 8000Hz to 48 kHz for one or two channels. The audio daemon uses the sample rate specified by the UNIX audio sound quality attribute on the Array properties panel in Array Manager. By default, the sample rate is 22.05kHz.

The SGD audio daemon connects to the SGD server on random ports. If there is a firewall between the application server and the SGD server, the firewall must allow connections on all ports from the application server to the SGD server.

On Linux platforms, the audio driver emulator requires the soundcore module in the kernel. The audio driver emulator is an Open Sound System (OSS) emulator.

Configuring the X application

To be able to hear sound in an X application, the X application may have to be configured to output sound using the right audio device and audio format.

Some X applications are hard-coded to use the /dev/audio or /dev/dsp devices for audio output. You can enable an SGD audio redirection library to force the X application to use the device specified by the SGDAUDIODEV environment variable. To enable the audio redirection library, check the UNIX Audio - enable LD_PRELOAD (--unixaudiopreload true) box on the Advanced panel in Object Manager

The SGD audio driver emulator is an OSS driver. The X application may have to be configured to use OSS. If your system uses the Advanced Linux Sound Architecture (ALSA), you may have to enable the ALSA OSS emulation modules in the kernel.

If the Connection Method (--method) used for the X application is SSH and the application is configured to Display Using (--displayusing) a kiosk window, the Session Ends When (--endswhen) attribute must be set to Script exits or no windows (loginscriptnowindows).

Related topics
Troubleshooting sound in X applications Array properties (array-wide) Audio Protocol Engine properties (server-specific) UNIX Audio - enable LD_PRELOAD (--unixaudiopreload)