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Manual page for GAINTOOL(6)

gaintool - audio control panel

SYNOPSIS

gaintool

AVAILABILITY

This command is only available with the Demos installation option. Refer to [a manual with the abbreviation INSTALL] for information on how to install optional software.

DESCRIPTION

gaintool is a SunView demonstration program that controls various characteristics of the SPARCstation 1 audio device, see audio.4s Operations performed by gaintool affect all audio programs; for instance, adjusting the Play Volume instantly changes the output gain, regardless of which program is playing. gaintool also detects audio state changes made by other programs, and updates its display accordingly, keeping gaintool in sync with the current device configuration.

gaintool demonstrates an important principle involved in the integration of audio in the desktop environment: by enabling global control of important characteristics, it is not necessary for every application to provide an interface for these parameters. For instance, since audio output may be paused from the control panel, it is not strictly necessary that output applications display a Pause button of their own. However, such applications may detect that audio output has been paused, and take appropriate action.

Control Panel

Play Volume: This slider adjusts the output volume. Volume levels between 0 and 100 may be selected, where 0 represents infinite attenuation and 100 is maximum gain.
Record Volume: This slider adjusts the recording gain level in the range 0 to 100.
Monitor Volume: This slider adjusts the monitor gain level in the range 0 to 100. Monitor gain controls the amount of audio input signal that is fed through to the output port. For instance, if an audio source (such as a radio or CD-player) is connected directly to the input port, the input signal may be monitored through either the built-in speaker or the headphone jack.
Output: This selector switches the audio output port between the built-in speaker and the external headphone jack.
Pause Play: This button may be used to suspend and resume audio output. If audio output is in progress when Pause is clicked, it is stopped immediately and subsequent output data remains queued. The button then switches to a Resume button that, when clicked, resumes audio output at the point that it was suspended.
: If no process has the device open for output when Pause is clicked, gaintool holds the device open itself, thereby denying other processes output access. Audio programs that simply open and write to the audio device will typically be suspended when they attempt to open the device. Programs that asynchronously poll the device will discover that it is ``busy'' and may take appropriate action.

Audio Device Status Panel

: Pressing the PROPS (L3) key brings up a status panel that shows the current state with the its display accordingly, audio applications. Selecting ``Done'' from the panel menu (or pressing the (L7) key) removes the panel.
: Ordinarily, the device status is updated only when a SIGPOLL signal is delivered to gaintool (see audio.4s Because of this, the Active and Samples indicators are not necessarily kept up-to-date. However, when the mouse is positioned over the panel, status is continually updated.

BUGS

Record Volume should be controlled by a separate panel that also provides automatic gain level adjustment capabilities.

WARNINGS

This program is furnished on an as is basis as a demonstration of audio applications programming.