AccessGrid.org

Getting the Sound Working

The following steps provides information on how to get audio working on an Access Grid

Getting the sound working for your Access Grid will probably be the most difficult part of this whole process. The setup will vary, as many computer workstations generally will have different sound cards.

Audio Setup

With the release of Fedora 8, "PulseAudio is now installed and enabled by default. PulseAudio is an advanced sound server compatible with nearly all existing Linux sound systems. PulseAudio allows for hot-switching audio outputs, individual volume controls for each audio stream, networked audio, and more." as quoted from Release Highlights.

For more information about PulseAudio, it is suggested to visit the PulseAudio website.

PulseAudio Trouble Shooting

Unfortunately it has been found that there are still some outstanding issues which causes many thing to not work correctly, in the case of the Access Grid, "rat" hasn't worked correctly on a number of tested machines.

By executing the command within a terminal session (as super user)

yum remove alsa-plugins-pulseaudio

It have been found that this solves a number of issues.

For other sound difficulties, it is suggested to visit http://www.pulseaudio.org/wiki/PerfectSetup.

Note: If you do some future updates, you may have to remove "alsa-plugins-pulseaudio" again, as it may get re-installed, especially if updating KDE.

Rat Configurations

  1. Before you start to setup the sound, there is an option that needs configuring. In RAT, click on the “Options” button. This will bring up a window similar to the one below.

    fc5install-sound-setup1

  2. Click on the button “personal” and select “audio”. This will bring up another window.

    fc5install-sound-setup2

  3. Silence Suppression may be on “Automatic” by default. It is recommended that you configure this option to be “Off”. It is also recommended that the option echo Suppression is turned off as well. Once these options have been selected, click on the "Apply" Button. This will bring you back to the RAT window.

  4. To set up the sound you will need to watch the talk and listen meter levels in RAT. You will probably want to see the talk and listen meters move up until about 2-3 bars from the end when someone is talking in their normal voice, as seen below in the second.

  5. It is best to get the sound working collaboratively with other people. If the talk levels in RAT are not moving when you talk, you will need to change the input levels. When other people are talking your RAT "Listen" meter should be moving. If the meter in RAT does not move, you will need to adjust the output levels. These setting can be adjusted using Kmix and Alsamixer.

    • Another possible setting to check and test, is in the options menu within RAT: Category->Audio, check that a Audio Device is present.

    • Additionally, It has been found that using the OSS device produces the best sound quality.

  6. This guide will provide you with CQU’s settings and will hopefully get you on the right track to setting up your sound.

Alsamixer Configuration

This section of the guide describes Alsamixer configuration. (Note that different settings might be displayed if using a different sound Card)

One of the best tools that you can use to configure your audio properties is "alsamixer".

To use alsamixer, simply type the following command within a terminal sesison:

alsamixer -V all

You should have all devices displayed and be able to change the capture settings as well.


For one particular machine, the above screen capture was taken, where the "Capture" setting adjusted the gain levels for talk within rat.

Additional Settings

  1. If you are experiencing loop-back audio, or you find changing the "talk" gain has no real effect, you may have to change the “force_ac97” setting within the AudioService. This can be achieve by running the VenueClient, then selecting “Preferences” -> “Manage My Node” options within the menu.

    Then by selecting the audio service and right click and select the "Configure" option, this will display the Audio Config Dialog.

    AG 2.xfc5install-sound-setup9 AG 3.xfc5install-sound-setup10

  2. Then change the setting to “true” for the force_ac97 option. Click on the “OK” button. You will then need to store the node configuration on the “Access Grid Node Management” for the changes to be saved. Remmeber to ensure this is kept standard, you will have to make the same change to both AG2.x and AG3.x software.

 

Delaying Rat

If you find that switching from Venue to Venue sometimes causes rat to revert to using the ALSA driver, rather than continue to use the OSS driver, a possible solution for this problem is to delay the starting up of Rat.

The following implementation provides a simple "hack" to delay the starting of rat:

  • With "root permissions", delete the simlink /usr/bin/rat.

  • Create the file /usr/bin/rat and add the following contents:

#!/bin/bash

sleep 3

exec /usr/bin/rat-4.4.00 "$@"

  • Make the file /usr/bin/rat executable, but issuing the command chmod 755 /usr/bin/rat

  • Now every time rat starts, it will be delayed for 3 seconds before executing.

 

 

 

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