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NETWORK AUDIO SYSTEM(1)     General Commands Manual    NETWORK AUDIO SYSTEM(1)



NAME
       Network Audio System - a portable, network-transparent audio system

SYNOPSIS
       The Network Audio System service is a network-transparent system
       developed at Network Computing Devices for playing, recording, and
       manipulating audio data over a network.  It uses the client/server
       model to separate application code from the software drivers needed to
       control specific audio input and output devices.

DESCRIPTION
       The Network Audio System service provides applications with the ability
       to send and receive audio data such as voice, sound effects, and music
       in a network environment.  A audio server inside the desktop terminal
       or personal computer controls the various input and output devices in
       response to messages sent from client programs running on other hosts.

       A variety of utility programs are provided that can be used to play or
       record audio using shell scripts or command-line procedures.  More
       ambitious applications can communicate directly with the audio server
       using a C-language programming library.

       The Network Audio System service supports a variety of the common
       formats used to store sound data.  Audio inputs and outputs can run at
       a any of a range of sampling rates.  The audio server automatically
       converts all data to the designed format or rate.

       Streams of data from multiple inputs can be mixed together and directed
       to any attached output device.  Sounds that are used many times can be
       stored in the server so that they do not need to be transmitted over
       the network each time they are played.  Furthermore, inputs can be
       hooked directly to outputs (for example, a CD player can be connected
       to a set of speakers) so that data can be played without requiring any
       client intervention or network traffic.

AUDIO SERVER NAMES
       Each audio server has a name that is used by applications in
       establishing a connection.  The format of the name depends upon the
       type of network being used.  In TCP/IP environments, audio server names
       look like:

                                tcp/hostname:portnum

       where hostname is the name or numeric IP address of the desktop machine
       to be contacted and portnum is the port number on which the server is
       listening.  If the ``tcp/'' prefix is not given, 8000 is automatically
       added to portnum so that the audio server name is compatible with the X
       Window System display name.

       In DECnet environments, audio server names look like:

                                decnet/nodename::num

       where nodename is the name or numeric DECnet address of the desktop
       machine to be contacted and num is the DECnet task AUDIO$num.  If the
       ``decnet/'' prefix is omitted, it is automatically added so that the
       audio server name is compatible with the X Window System display name.

       Most audio utilities accept a command line argument -audio servername
       for specifying the audio server to be contacted.

           % auinfo -audio tcp/ncdunit:8000

       If no server is specified on the command line, the AUDIOSERVER
       environment variable is checked to see if a name has been stored there.
       Otherwise, the DISPLAY environment variable used by X Window System
       applications is checked and the corresponding audio server is used.

SAMPLE PROGRAMS
       Several sample programs that use the Network Audio System service are
       provided by NCD:

       auplay  This program simply plays the files listed on its command line.
               It is typically used from shell scripts, command-line
               procedures, or other programs that just need to ``dump'' sound
               data to the audio server.

       audemo  This program allows the user to select and play pre-recorded
               sound files or to record new sound files.  It provides a simple
               control panel for dynamically changing the volume while a sound
               is being played and for aborting a sound.

       audial  This program generates North American telephone touch tones
               correspond to a given string.  audial can also recognize touch
               tones and produce the corresponding string.

       autool  This program is compatible with the Sun audiotool program and
               is typically used to play prerecorded sound files.  Unlike
               auplay it provides a graphical interface to allow the user to
               replay or cancel the data.

       auinfo  This program lists information describing the capabilities of
               an audio server.

       auctl   This program can be used to change various device parameters.

       auscope This program is an audio protocol filter that can be used to
               view the network packets being sent between an application and
               an audio server.

       aupanel This program provides an X-based window-oriented interface
               allowing the user to adjust the attributes of the devices
               provided by the Network Audio System service.

       auedit  This program provides an X-based window-oriented interface
               allowing the user to edit audio files.

       auconvert
               This program allows the user to perform various conversion
               operations on sound files.

       auphone This program provides an X-based window-oriented interface
               allowing two-way real time voice communication between two
               audio servers.

       aurecord
               This program is used to record audio data from an audio server
               into a file.

       auwave  This program provides an X-based window-oriented interface
               demonstrating the use of waveform elements.

AUDIO FILES
       The audio programming library and utility programs can be used to read
       and write files in any of the following file formats:

       Sun/NeXT
              These files typically have a '.au' or '.snd' extension.  They
              are usually produced by Sun or NeXT workstations.

       Creative Labs
              These files typically have a '.voc' extension.  They are usually
              produced by by Soundblaster audio cards on IBM PC compatible
              computers.

       Microsoft WAVE
              These files typically have a '.wav' extension.  They are usually
              produced by IBM PC compatible computers.

       AIFF
              These files typically have an '.aiff' or '.aif' extension.  They
              are usually produced by SGI workstations or Apple computers.

       Amiga IFF/8SVX
              These files typically have an '.iff' extension.

       Due to the nature of the file formats, only the Sun/NeXT file format
       can be piped through standard input and/or standard output.  The
       convention for specifying standard input or standard output is to use a
       hyphen ("-") as the file name.

PROGRAMMING
       Application developers may create their own audio clients using the
       Network Audio System programming library.

ENVIRONMENT VARIABLES
       The following environment variables are used by Network Audio System
       programs:

       AUDIOSERVER
               This specifies the name of default audio server to contact if
               no name is explicitly given on the command line.

       DISPLAY This specifies the name of an X Window System display that
               should be assumed to also have a corresponding Network Audio
               System server.

SEE ALSO
       auplay(1), audemo(1), audial(1), autool(1), auinfo(1), auctl(1),
       auscope(1), aupanel(1), auedit(1), auconvert(1), auphone(1),
       aurecord(1), auwave(1)

       Network Audio System Overview and Programmers Guide

COPYRIGHT
       The following copyright and permission notice applies to all files in
       the Network Audio System application programming libraries and example
       programs provided in source form by Network Computing Devices:

       Copyright 1993, 1994 Network Computing Devices, Inc.

       Permission to use, copy, modify, distribute, and sell this software and
       its documentation for any purpose is hereby granted without fee,
       provided that the above copyright notice appear in all copies and that
       both that copyright notice and this permission notice appear in
       supporting documentation, and that the name Network Computing Devices,
       Inc. not be used in advertising or publicity pertaining to distribution
       of this software without specific, written prior permission.

       THIS SOFTWARE IS PROVIDED `AS-IS'.  NETWORK COMPUTING DEVICES, INC.,
       DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
       WITHOUT LIMITATION ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
       FOR A PARTICULAR PURPOSE, OR NONINFRINGEMENT.  IN NO EVENT SHALL
       NETWORK COMPUTING DEVICES, INC., BE LIABLE FOR ANY DAMAGES WHATSOEVER,
       INCLUDING SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOSS
       OF USE, DATA, OR PROFITS, EVEN IF ADVISED OF THE POSSIBILITY THEREOF,
       AND REGARDLESS OF WHETHER IN AN ACTION IN CONTRACT, TORT OR NEGLIGENCE,
       ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
       SOFTWARE.

TRADEMARKS
       NCD, NCD Display Station, and NCDware are all trademarks of Network
       Computing Devices, Inc.

       X Window System is a trademark of the Massachusetts Institute of
       Technology.

AUTHORS
       Greg Renda, Jim Fulton, David Lemke



                                     1.9.4             NETWORK AUDIO SYSTEM(1)