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NAME
soundtool - audio waveform display demo
SYNOPSIS
/usr/demo/SOUND/bin/soundtool
DISCLAIMER
This program is furnished on an AS IS basis as a demonstra-
tion of audio applications programming.
DESCRIPTION
soundtool is an XView demonstration program that allows
recording, playing, and simple editing of audio data. The
display consists of six regions: a play/record control
panel, a function control panel, an oscilloscope, a display
control panel, a waveform display panel, and a pop-up audio
status panel.
Play/Record Control Panel
Play/Stop
Clicking this button plays the currently selected
region of data. While data is playing this button
becomes a Stop button. If audio output is busy when
Play is started, this button displays Waiting. When
the device is available, the button switches to Stop
and audio output begins. Clicking on the Waiting but-
ton resets the tool to the idle state.
Record/Stop
Clicking this button starts the recording of data from
the audio input port that is wired to the 8-pin mini-
DIN connector on the back of the workstation. While
recording is in progress, this button becomes a Stop
button. If audio input is busy when Record is
selected, an alert pops up and the tool resets to the
idle state. A maximum of 5 minutes may be recorded at
a time.
Pause Clicking this button while playing or recording
suspends the current operation. The button becomes a
Resume button that may be selected to continue the
suspended operation.
Describe
Clicking this button brings up the ``Audio Status
Panel''. If the panel was already visible, clicking
this button removes it.
Quit Clicking this button causes soundtool to exit.
Play Volume
This slider adjusts the playback 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 level in the range
0 to 100.
Output To
This selector switches the audio output port between
the built-in speaker and the external headphone jack.
Looping
When Looping is disabled, the current data region
(that is, the data between the two markers in the
waveform display) is played once. If Looping is
enabled, the selected data will be played endlessly
until the Stop button is pressed.
Function Control Panel
Load Clicking Load will read in the audio file specified by
the Directory and File fields. If the named file does
not contain a valid audio header, the raw data is
copied into the buffer and an alert is displayed.
Clicking the Store button at that point will rewrite
the file with the proper audio file header.
Arbitrarily large audio files may be loaded. However,
system swap space resources may be depleted (one
minute of audio data consumes roughly .5 Mbyte of swap
space).
Store Clicking Store will write the selected data region
into the file specified by the Directory and File
fields. If the named file exists, an alert will
request confirmation of the operation.
Append
Clicking Append will append the selected data region
to the file specified by the Directory and File
fields. The named file must contain a valid audio
file header.
Directory
The Directory field specifies a directory path in
which to look for audio files.
File The File field designates the file to be loaded from,
stored to, or appended to. Holding down the right
mouse button on this field presents a menu of audio
files in the currently designated directory. All files
that contain a valid audio file header, or whose names
have the suffix .au or .snd, are listed.
Oscilloscope
When the program is in the idle state and the cursor is in
the waveform display panel, the oscilloscope acts as a mag-
nifying glass, displaying the region of the audio waveform
that is currently under the cursor. When the program is
playing or recording, the oscilloscope displays the data
that is currently being transferred. Notice that there is a
small time lag in the display of recorded data, due to the
fact that the audio device driver buffers input data and
delivers it to the application in discrete segments.
Display Control Panel
Zoom The Zoom slider adjusts the compression factor used in
the display of the waveform. The upper compression
limit is chosen so that the entire waveform will fit
in the waveform display panel. (The lower limit is
restricted by the ability to manipulate large scrol-
ling regions in XView.) Adjustment of the Zoom slider
ordinarily results in data compression or expansion
around the center of the currently displayed waveform.
If the waveform display contains one or both data
selection markers, an attempt is made to keep at least
a portion of the selected data region in the window.
The magnified waveform presented in the oscilloscope
display is unaffected by the Zoom value. However, cur-
sor movement over the waveform reflects the current
compression; that is, lower Zoom values result in
finer granularity of mouse movement.
Waveform Display Panel
The waveform display shows all or part of the current
waveform, depending on the current Zoom value. Scrolling of
the waveform may be achieved either by using the scrollbar
or by dragging the waveform to the right or left while hold-
ing the middle mouse button down. Notice that scrolling is
disabled when the entire waveform is being displayed (that
is, when the Zoom value is at its maximum).
In some cases, it is desirable to identify a subset of the
waveform. For instance, the Play, Store, and Append func-
tions operate on a selected region, rather than the entire
waveform. The currently selected region of interest is del-
imited by dashed vertical lines. A new region may be
selected by clicking the left or right mouse button and
dragging it across the desired region of interest. Alterna-
tively, a single click on the left (or right) mouse buttons
adjusts the start (or end) point.
Audio Status Panel
This panel is displayed (or removed) when the Describe but-
ton is pressed. It contains fields that describe the data in
the buffer.
Sample Rate
This field displays the sampling frequency, in samples
per second.
Channels
This field denotes the number of interleaved channels
of audio data.
Precision
This field identifies the encoding precision, in bits
per sample.
Encoding
This field displays the encoding format.
Total Length
This field shows the length of the entire data buffer,
in the form hh:mm:ss.dd.
Selection
This field identifies the start and end times of the
currently selected region of interest.
Info String
When an audio file is loaded, the first 80 characters
of the information field of the audio header are
displayed in this field. This string may be edited,
though the new information is only written out when
the Store operation is performed.
BUGS
Currently, soundtool is capable of displaying only 8-bit
mu-law encoded data (as in the Greek letter mu).
Audio files should be mapped in order to reduce the swap
space requirements. The limit on recording length should
also be removed.
There are problems with scrollbars that operate on very
large canvases. This constraint is the reason for the lower
limit on zooming. Also, there are some problems with the
display of very large audio files with a low zoom factor.
Region selections made over the waveform display panel work
best when the click and drag paradigm is used. Adjusting
the start or end points by a single click is susceptible to
error; that is, if the mouse moves slightly between the
button down and up events, the result will be a very small
selection.
SEE ALSO
audioconvert(1), gaintool(6)
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