audemo - Network Audio System record and play demo

audemo [-audio servername] [-toolkitoption ...] [directory]

audemo provides an X-based window-oriented user interface to the Network Audio System service. It allows the user to play pre-recorded sound files, record new sound files and to manipulate Network Audio System buckets.

audemo uses the X Toolkit Intrinsics and the Athena Widget Set. For more information, see the Athena Widget Set documentation.

audemo starts out with a single window divided into several areas:

o

A collection of command buttons.

o

A left and right level meter.

o

A volume indicator and control slider.

o

An information window.

o

An editable field containing the directory to be searched for sound files.

o

An editable field containing a list of sound files to search for.

o

A window containing the list of sound files that may be selected for playing or loading into buckets.

To play a sound file you must first select it from the list of files in the file window. You can control which files are listed in this window by editing the Directory and/or Template fields and clicking on the Rescan button. To select a file, single-click on the filename. This will highlight the filename and display information about the file in the information window. The information displayed includes:

Filename

The full pathname of the file.

File Format

The file format of the audio file.

Data Format

The encoding format of the audio data.

Tracks

The number of tracks of audio data.

Frequency

The frequency at which the audio data was sampled.

Duration

The duration of the audio data in seconds.

Text

Any text information stored in the file.

Once the file has been selected, you can start it playing by clicking on the Play command button. A shortcut for playing a file is to double-click on the file name. This will select the file and start it playing. When a file is playing, the Play command button is highlighted. To stop the playing of a file, click on the highlighted Play button. To enable the left and right level meters, click on the Meter button before starting to play the file. To disable the left and right level meters, click again on the highlighted Meter button. To adjust the volume level, use the volume slider.

audemo can record sound files in any supported file and data format. To record a sound file you must first bring up the record window by clicking on the Record command button. This will bring up a window containing the following fields and controls:

Filename

The name of the file you wish to create. Unless a path is specified here, the file will be created in the current directory.

File Format

A menu of file formats.

Data Format

A menu of data formats. Note that each file format does not necessarily support all of the data formats listed.

Max Duration

See RECORDING TO A BUCKET.

Read Only

See RECORDING TO A BUCKET.

Frequency

The sampling rate (in hertz) for the recording. Higher sampling rates yield better quality sound but take up more disk and memory space. Common sampling rates are 8000 (good for voice annotations), 11000, 22000, and 44000.

Mic(rophone)

This button tells the audio server if you've got a microphone attached to the audio input jack. Clicking this button will highlight it and cause the audio server to boost the input gain to a level suitable for recording with a microphone.

Comment

Text (such as a description) you wish to put into the audio file.

Gain

This slider is used to adjust the recording gain level.

Record

This button starts or stops the recording.

Monitor

This button enables or disables monitoring.

New Bucket

See RECORDING TO A BUCKET.

Dismiss

This button stops recording and monitoring and closes the record window.

Once you have selected the filename, file and data formats, frequency, mic level, comment and gain, you are ready to record. To listen in on the audio that will be recorded you can click on the Monitor button. This will direct all the audio received from the audio input jack to be played on the speaker. When you're ready to record, click on the Record button. All the audio received from the audio input jack will now be recorded into the file. The recording will continue until you click on the Record button again or click on the Dismiss button. NOTE: Audio data can accumulate very rapidly, especially at high sampling rates, resulting in large files.

The Network Audio System service provides the capability to create server resident sound objects called buckets. audemo allows the user to create buckets, record into them, play from them, load them with data from a file and dump their contents into a file. Note that buckets created by audemo are destroyed when audemo is terminated. These options are available when you bring up the buckets window by clicking on the Buckets button in the main window. The buckets windows is divided into two areas:

o

A collection of command buttons.

o

A table of buckets currently accessible. This table contains the following columns:

Description

The text description.

Duration

The duration of the audio data in seconds.

Tracks

The number of tracks of audio data.

Frequency

The frequency at which the audio data was sampled.

Format

A code letter indicating the encoding format of the audio data. A key to the format code letters can be displayed by clicking on the Format Key button.

Access

A combination of code letters indicating the access mode of the bucket. A key to the access code letters can be displayed by clicking on the Access Key button.

To create a bucket from from an audio data file, select the filename from the list of files in the file window then click the Load button in the buckets window. The first line of the buckets table should now contain the information about the newly created bucket.

To play a bucket, select the bucket you wish to play by clicking on it's information in the buckets table. The entry you click on should be highlighted. Then click on the Play button in the buckets window. A shortcut for playing from a bucket is to double-click on the bucket information. This will select the bucket and start playing from it. To stop the playing of a bucket, click on the highlighted Play button in the buckets window. The level meters and volume level can be controlled in the same way as when playing from a file.

To record into a new bucket, click on the Record button in the buckets window. This will bring up the record window. This record window is the same as the one used for recording to files. Instead of specifying a filename, in the Max Duration field, enter the maximum duration (in seconds) of data that the bucket is to hold. Clicking on the Read Only button will prevent other applications from writing into or destroying the bucket. The frequency, mic level, format and comment are used in the same way as when recording to files. Once all of the fields are set appropriately, click the New Buckett button. This will create a new bucket according to the specifications given. The first line of the buckets table should now contain the information about the newly created bucket. To begin recording into the bucket, select the bucket by clicking on it's information in the buckets table. Then click the Record button in the record window. All the audio received from the audio input jack will now be recorded into the bucket. The recording will continue until you click on the Record button again, click on the Dismiss or the bucket is filled. The Gain slider and the Monitor button operate the same as when recording to a file.

To save a bucket to a file, first select the bucket by clicking on its information in the buckets table. Then click on the Save button in the buckets window. A dialog box will pop up prompting you for the name of the file in which to save the bucket data, and the file format. The data format used will be that of the bucket. Note that each file format may only support selected data formats. If no path is given in the filename, the file will be created in the current directory. Clicking on Ok or pressing the RETURN key will cause the file to be created and the data from the bucket to be written to the file.

To delete a bucket, first select the bucket by clicking on it's information in the buckets table. Then click on the Delete button in the buckets window. If the audemo has the appropriate access permissions for the bucket, the bucket will be deleted and it's information will be removed from the bucket table.

Clicking on the Quit button will cause audemo to exit, stopping any playing or recording operations and destroying any buckets that were created.

-audio servername

This option specifies the Network Audio System server to which audemo should connect.

directory

The directory name that audemo will use to build the list of selectable file names. When directory is not specified on the command line, the current working directory is used.

In the following example, in a TCP/IP network, mcxterm is the name of the desktop machine running the audio server. The default port is 8000 and sound files are located in ~/snd:

audemo -audio tcp/mcxterm:8000 ~/snd

In the following example, the shortened form of the audio server name is used and sound files from the current working directory will be used:

audemo -audio mcxterm:0

In addition to the standard toolkit environment variables, the following environment variables are used by audemo:

AUDIOSERVER

This variable specifies the default audio server to contact if -audio is not specified on the command line. If this variable is not set and the -audio is not specified on the command line, audemo will attempt to connect to the audio server running on the X Window System display.

Warning: audemo is the xterm of the Network Audio System. It was written to test features as the Network Audio System was being developed. It was also the author's first Xt program. Consequently, it's pretty ugly and should be completely re-written from scratch.

nas(1), X(1)

Copyright 1993, 1994 Network Computing Devices, Inc.

Greg Renda, Network Computing Devices, Inc.