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)