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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 devel- oped at Network Computing Devices for playing, recording, and manipu- lating 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 am- bitious applications can communicate directly with the audio server us- ing a C-language programming library. The Network Audio System service supports a variety of the common for- mats used to store sound data. Audio inputs and outputs can run at a any of a range of sampling rates. The audio server automatically con- verts 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 establish- ing a connection. The format of the name depends upon the type of net- work 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 ma- chine 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 environ- ment variable is checked to see if a name has been stored there. Oth- erwise, the DISPLAY environment variable used by X Window System appli- cations 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 proce- dures, 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 au- play it provides a graphical interface to allow the user to re- play 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 al- lowing the user to adjust the attributes of the devices pro- vided by the Network Audio System service. auedit This program provides an X-based window-oriented interface al- lowing the user to edit audio files. auconvert This program allows the user to perform various conversion op- erations on sound files. auphone This program provides an X-based window-oriented interface al- lowing 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 con- vention 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), aus- cope(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, pro- vided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in sup- porting 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 WITH- OUT LIMITATION ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NONINFRINGEMENT. IN NO EVENT SHALL NETWORK COM- PUTING 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 RE- GARDLESS OF WHETHER IN AN ACTION IN CONTRACT, TORT OR NEGLIGENCE, ARIS- ING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFT- WARE. 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 Tech- nology. AUTHORS Greg Renda, Jim Fulton, David Lemke 1.9.4 NETWORK AUDIO SYSTEM(1)
NAME | SYNOPSIS | DESCRIPTION | AUDIO SERVER NAMES | SAMPLE PROGRAMS | AUDIO FILES | PROGRAMMING | ENVIRONMENT VARIABLES | SEE ALSO | COPYRIGHT | TRADEMARKS | AUTHORS
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