Reference


Menus

There are three menu items in the menu bar: File, View and Help.  This is the Help menu and therefore, is not documented here.
 

File

Mixer mode menu option allows you to enable and disable audio mixing.  Audio mixing enables you to listen to two or more audio channels simultaneously.  For example, while listening to a Sun Microsystems broadcast you will also be able to hear the tone alerting you that you have new mail.  If the Mixer mode menu option is greyed out, the audio driver or audio device does not support audio mixing.

File is also where you will find the Exit command when you are ready to quit Audio Control.
 

View

The View menu contains the Applications Controls and Status menu options. The Applications Control menu option allows you to toggle (i.e. open and close) the Application Controls panel.  The Application Controls panel is used to control individual audio channels.  The Status menu option displays a status window used for viewing the status of the audio device.
 

Help

Provides you with assistance in all areas of Audio Control.
 
 


Tabs

There are two tabs,  Playback and Record. Audio Control detects the type of device being used, and displays the appropriate tab. The Playback window appears if used with a play-only device, such as speakers. The Record tab appears when used with a record-only device, such as a microphone.


 

Application controls will be unchecked and greyed out if the audio device driver or audio hardware does not support audio mixing.


 
 

Playback Tab

Master Output Panel

The following controls are provided on the Master Output panel:

Output ports

The output ports list contains a list of available output ports. You check and uncheck ports to turn them on and off. The list of available choices depend on the device used.  Some ports may be checked and disabled (greyed out) as they are not modifiable.  Audio output to these ports is always heard.  The output port list can contain additional ports depending on the audio device.  Volume and balance levels apply to all output ports.
 

Volume Slider

This is for setting the master volume for the audio device.  Setting the Master volume affects the volume of the audio device and therefore affects all audio channels. The current volume level is displayed in a text label next to the control. The displayed value changes as the slider is moved up and down or as the audio device volume is changed via some external control, such as CDE sdtaudio.
 

Balance Slider

 Use the slider for setting the balance of the audio device.
 

Mute

Select this to mute all output ports.
 

Playback using the Master and Application Output



 

The Application Output panel lists the all the audio channels currently running audio.

The Application Output panel lets you control individual channels audio output parameters.  You can access it by selecting  the Application Controls option from the View menu while the Playback tab is active. The new controls provided are  exactly the same as those provided for the Master Output, with the exception that they are provided for one channel  at a time, rather than for an entire audio device. Open audio channels are displayed in the list box at the top of the panel.  By selecting an audio channel, you can individually control the volume, balance, and muting of that audio channel.

Each process that opens the audio device gets a virtual device called an audio channel.  Audio channels list may be empty, for example, when mixer mode is deselected or not supported on the hardware.
 
 

Record Tab

Master Input Panel

You can control master recording parameters on the Master Recording window.  Audio Control displays the Record tab in response to record-only devices. The controls provided are:


 

Input ports

This panel contains a list of the available input ports.  You can choose only one input ports at a time.  The choices are hardware dependent.
 

Gain slider

Use the slider for setting the master gain (recording volume). The current level is displayed next to the control. The displayed value changes as the slider is moved up and down or as the audio device volume is changed via some external control such as the CDE sdtaudio.
 

Monitor slider

Use this slider for adjusting the volume of the incoming audio that is sent to the output device(s). It allows you to monitor the audio as it is being recorded.
 

Balance slider

Use this slider for setting the recording balance for the selected port.
 

Recording Using the Master and Application Input


The Application Input panel lists the all the audio the channels currently running audio.

The controls provided behave exactly the same as those provided for the Master input, with the exception that  they are provided for one process at a time, rather than for an entire audio device. Processes that are currently using audio are displayed in the Application input list box at the top of the panel.  By selecting an audio channel, you can individually control the gain and balance of that process. The Monitor volume is controllable only at the master level, so there is no Monitor volume slider on the  Application Input panel.
 
 


Status Dialog

This dialog allows you to view playback and recording status for the Master channel or for each audio channel. You can access the Status dialog by selecting Status from the View menu. Audio Control detects the type of device in use. If the device supports playback, the Playback Status appears; if the device supports recording, the Record Status appears.


 

Continuous Update checkbox

Check the Continuous Update checkbox causes the status for the selected audio channel or the Master channel to be continuously monitored and updated.

Update Now button

If Continuous Update is not enabled, you can update the display by clicking the Update Now button.
 

Playback and Record Panels

These two panels indicate the status of playing or recording audio channels.  The following list defines the audio parameters monitored.

Open

The device is open by a process. The device may be opened read only, write only, or read and write. Which is why there is an open for  play and one for record. These will be used only when mixing is disabled.

Paused

The applications has commanded the device to pause playing or recording. Just like Open, you can have one direction paused while the other is active. Also, this will be used only when mixing is disabled.

Active

Sound is being played or recorded. In mixer mode this means at least one stream is playing or recording. It is possible that other streams will be paused. When the mixer is off then there can be only a single play and record stream, so this means that single stream is active.

Underflow

When playing there wasn't enough audio available so the device underflowed and there is silence. With the mixer this means that the stream didn't have enough sound to mix into the audio stream that is  being played, so that one stream will have silence.

Open-Waiting

When the mixer is turned of this means a process is trying to open the audio device and can't because another process already has the device open. When the mixer is enabled it means a process is either trying to open the audio device a second time for the same direction, or the mixer is out of resources and is waiting for another process to close the audio device and free up a resource for use.

EOF Count

When playing it is possible to mark the audio stream so that you know when a segment has been played. This is done by doing a zero sized write and accepting signal. Each time this marker is encountered while playing the EOF Count will be incremented by one and a signal will be sent to the application.

Samples

The number of sample frames that has been played or recorded. A sample frame is all samples to play one sample time. For example, playing a mono audio stream means that one sample frame has one sample, but  playing a stereo stream means that one sample frame has two samples. One for the left port and one for the right port.

Encoding

This combines two audio format properties, precision and encoding. Precision is the number of bits each sample uses. We support 16 bits and 8 bits. The encoding method determines any processing of the audio sample. This is usually done to compress the size of the audio stream so not as much data needs to be sent over the network or stored on disk. We support "linear" which is linear pulse code modulation, AKA linear PCM. We also support u-Law (u is for the Greek letter mu, which can't be reproduces in simple text like this, but it can in  postscript), and A-Law. When combined together with precision we support 16-bit Linear PCM, 8-bit Linear PCM, 8-bit u-Law, and 8-bit A-Law. Also, linear PCM may be signed or unsigned, we support only signed.

Sample Rate

The number of times a second the audio stream is sampled and thus converted from an analog signal to a digital number for recording. Or converted from a digital number to an analog signal when playing.  The higher the number the greater the accuracy of the digital signal. But a higher number also means more disk space is needed for storage or network bandwidth is needed to transfer the data.

Channels

The number of samples in a sample frame. Currently supported: 1 (mono) or 2 (stereo).

Close

Dismisses the Status dialog.