1NETWORK AUDIO SYSTEM(1) General Commands Manual NETWORK AUDIO SYSTEM(1)
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6 Network Audio System - a portable, network-transparent audio system
7
9 The Network Audio System service is a network-transparent system devel‐
10 oped at Network Computing Devices for playing, recording, and manipu‐
11 lating audio data over a network. It uses the client/server model to
12 separate application code from the software drivers needed to control
13 specific audio input and output devices.
14
16 The Network Audio System service provides applications with the ability
17 to send and receive audio data such as voice, sound effects, and music
18 in a network environment. A audio server inside the desktop terminal
19 or personal computer controls the various input and output devices in
20 response to messages sent from client programs running on other hosts.
21 A variety of utility programs are provided that can be used to play or
23 record audio using shell scripts or command-line procedures. More am‐
24 bitious applications can communicate directly with the audio server us‐
25 ing a C-language programming library.
26 The Network Audio System service supports a variety of the common for‐
28 mats used to store sound data. Audio inputs and outputs can run at a
29 any of a range of sampling rates. The audio server automatically con‐
30 verts all data to the designed format or rate.
31 Streams of data from multiple inputs can be mixed together and directed
33 to any attached output device. Sounds that are used many times can be
34 stored in the server so that they do not need to be transmitted over
35 the network each time they are played. Furthermore, inputs can be
36 hooked directly to outputs (for example, a CD player can be connected
37 to a set of speakers) so that data can be played without requiring any
38 client intervention or network traffic.
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41 Each audio server has a name that is used by applications in establish‐
42 ing a connection. The format of the name depends upon the type of net‐
43 work being used. In TCP/IP environments, audio server names look like:
44 tcp/hostname:portnum
46 where hostname is the name or numeric IP address of the desktop machine
48 to be contacted and portnum is the port number on which the server is
49 listening. If the ``tcp/'' prefix is not given, 8000 is automatically
50 added to portnum so that the audio server name is compatible with the X
51 Window System display name.
52 In DECnet environments, audio server names look like:
54 decnet/nodename::num
56 where nodename is the name or numeric DECnet address of the desktop ma‐
58 chine to be contacted and num is the DECnet task AUDIO$num. If the
59 ``decnet/'' prefix is omitted, it is automatically added so that the
60 audio server name is compatible with the X Window System display name.
61 Most audio utilities accept a command line argument -audio servername
63 for specifying the audio server to be contacted.
64 % auinfo -audio tcp/ncdunit:8000
66 If no server is specified on the command line, the AUDIOSERVER environ‐
68 ment variable is checked to see if a name has been stored there. Oth‐
69 erwise, the DISPLAY environment variable used by X Window System appli‐
70 cations is checked and the corresponding audio server is used.
71
73 Several sample programs that use the Network Audio System service are
74 provided by NCD:
75 auplay This program simply plays the files listed on its command line.
77 It is typically used from shell scripts, command-line proce‐
78 dures, or other programs that just need to ``dump'' sound data
79 to the audio server.
80 audemo This program allows the user to select and play pre-recorded
82 sound files or to record new sound files. It provides a simple
83 control panel for dynamically changing the volume while a sound
84 is being played and for aborting a sound.
85 audial This program generates North American telephone touch tones
87 correspond to a given string. audial can also recognize touch
88 tones and produce the corresponding string.
89 autool This program is compatible with the Sun audiotool program and
91 is typically used to play prerecorded sound files. Unlike au‐
92 play it provides a graphical interface to allow the user to re‐
93 play or cancel the data.
94 auinfo This program lists information describing the capabilities of
96 an audio server.
97 auctl This program can be used to change various device parameters.
99 auscope This program is an audio protocol filter that can be used to
101 view the network packets being sent between an application and
102 an audio server.
103 aupanel This program provides an X-based window-oriented interface al‐
105 lowing the user to adjust the attributes of the devices pro‐
106 vided by the Network Audio System service.
107 auedit This program provides an X-based window-oriented interface al‐
109 lowing the user to edit audio files.
110 auconvert
112 This program allows the user to perform various conversion op‐
113 erations on sound files.
114 auphone This program provides an X-based window-oriented interface al‐
116 lowing two-way real time voice communication between two audio
117 servers.
118 aurecord
120 This program is used to record audio data from an audio server
121 into a file.
122 auwave This program provides an X-based window-oriented interface
124 demonstrating the use of waveform elements.
125
127 The audio programming library and utility programs can be used to read
128 and write files in any of the following file formats:
129 Sun/NeXT
131 These files typically have a '.au' or '.snd' extension. They
132 are usually produced by Sun or NeXT workstations.
133 Creative Labs
135 These files typically have a '.voc' extension. They are usually
136 produced by by Soundblaster audio cards on IBM PC compatible
137 computers.
138 Microsoft WAVE
140 These files typically have a '.wav' extension. They are usually
141 produced by IBM PC compatible computers.
142 AIFF
144 These files typically have an '.aiff' or '.aif' extension. They
145 are usually produced by SGI workstations or Apple computers.
146 Amiga IFF/8SVX
148 These files typically have an '.iff' extension.
149 Due to the nature of the file formats, only the Sun/NeXT file format
151 can be piped through standard input and/or standard output. The con‐
152 vention for specifying standard input or standard output is to use a
153 hyphen ("-") as the file name.
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156 Application developers may create their own audio clients using the
157 Network Audio System programming library.
158
160 The following environment variables are used by Network Audio System
161 programs:
162 AUDIOSERVER
164 This specifies the name of default audio server to contact if
165 no name is explicitly given on the command line.
166 DISPLAY This specifies the name of an X Window System display that
168 should be assumed to also have a corresponding Network Audio
169 System server.
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172 auplay(1), audemo(1), audial(1), autool(1), auinfo(1), auctl(1), aus‐
173 cope(1), aupanel(1), auedit(1), auconvert(1), auphone(1), aurecord(1),
174 auwave(1)
175 Network Audio System Overview and Programmers Guide
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179 The following copyright and permission notice applies to all files in
180 the Network Audio System application programming libraries and example
181 programs provided in source form by Network Computing Devices:
182 Copyright 1993, 1994 Network Computing Devices, Inc.
184 Permission to use, copy, modify, distribute, and sell this software and
186 its documentation for any purpose is hereby granted without fee, pro‐
187 vided that the above copyright notice appear in all copies and that
188 both that copyright notice and this permission notice appear in sup‐
189 porting documentation, and that the name Network Computing Devices,
190 Inc. not be used in advertising or publicity pertaining to distribution
191 of this software without specific, written prior permission.
192 THIS SOFTWARE IS PROVIDED `AS-IS'. NETWORK COMPUTING DEVICES, INC.,
194 DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING WITH‐
195 OUT LIMITATION ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
196 PARTICULAR PURPOSE, OR NONINFRINGEMENT. IN NO EVENT SHALL NETWORK COM‐
197 PUTING DEVICES, INC., BE LIABLE FOR ANY DAMAGES WHATSOEVER, INCLUDING
198 SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOSS OF USE,
199 DATA, OR PROFITS, EVEN IF ADVISED OF THE POSSIBILITY THEREOF, AND RE‐
200 GARDLESS OF WHETHER IN AN ACTION IN CONTRACT, TORT OR NEGLIGENCE, ARIS‐
201 ING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFT‐
202 WARE.
203
205 NCD, NCD Display Station, and NCDware are all trademarks of Network
206 Computing Devices, Inc.
207 X Window System is a trademark of the Massachusetts Institute of Tech‐
209 nology.
210
212 Greg Renda, Jim Fulton, David Lemke
213 1.9.5 NETWORK AUDIO SYSTEM(1)