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What is IntranetRadio?
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IntranetRadio is a program designed for transferring sound signals over 
local area networks (LANs). The main sphere of application - office 
networks, school, university and other educational LANs. For example, 
you can organize your own "radio broadcast" on your LAN. Install 
IntranetRadio Server onto the computer, that will be as "sound server" 
and input a sound signal from radio receiver, CD-audio player, 
microphone or any other sound source. Now if you execute IntranetRadio 
Player on other computers in the network you can listen the sound 
transmitted by the server. Because of using broadcasting technology, the 
transmitted sound can be received by some computers simultaneously.

Since IntranetRadio Player in stand-by mode takes no CPU ticks, it can 
be set to be started automatically when the computer turn on, and the 
IntranetRadio system can be used for broadcasting advertisements, audio 
messages, music etc.

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Main features
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1. Broadcasting addresses

The main question which needs resolution under the designing such 
programs is that it is necessary to have wide channel for transmitting 
sound signals. For example, to send  16-bit stereo sound, sampled with 
44,1 kHz frequency, you need a channel with about 1.4 Mbit/sec flow 
rate. On using Ethernet LAN with 10 Mbit/sec, net loading will be about 
14%. And if you need to transmit sound signal to some computers, net 
loading increases in proportion to the numbers of receiving machines, 
i.e. having an Ethernet LAN you can transmit sound only to 7 computers 
simultaneously. In this case the net is used only for sound 
transferring, and really the same data is multiple transmitted on the 
net.

The only way to solve the above described problem is to use broadcast 
IP-addresses. In this case the server sends sound data only once, and 
all client machines in network can receive them. The main feature of 
IntranetRadio compared with similar systems (RealAudio, Xing StreamWorks 
products) is namely supporting broadcasting IP addresses. In the case 
net loading makes 14% regardless of the number of computers receiving 
the sound flow.

2. Sound compression

Further improvement of the sound transfer system is in using sound 
compression. Even 14% of net loading is sensible, and sometimes it is 
necessary to transmit some independent sound channels. Usage of sound 
compression permits decreasing of net loading approximately by the 
factor of 10. Now wide-known MPEG compression algorithms, based on the 
features of human perception of the sound, are the most popular. More 
advanced algorithms provide 10-times sound compressing and quality 
distortion is practically imperceptible. However, sound compression on a 
MPEG algorithm has significant computational complexity, and real-time 
compression needs enough fast CPU (e.g. real-time compressing with the 
most popular MPEG Layer-3 algorithm requires Pentium-II CPU and above). 
It makes compressor program to be high sensitive to the other programs. 
Really, for the program you need to have a special fast computer.

As a compromise, you can choose less complex algorithms of sound 
compression, such as MPEG Layer-1 or MPEG Layer-2. Usage of them doesn't 
require such processor resources as for compression as well as for 
decompression, and satisfactory quality of the sound is provided.

Under the experiments as initial point for IntranetRadio was chosen the 
following: MPEG Layer-1 algorithm with the resulting bitrate 128 
kbit/sec (about 0.12 Mbit/sec). Net loading of a 10-Mbit/sec makes 
approx. 1% and sound quality is sufficient for transmitting and playing 
voice and sound signals received over radio.

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System requirements
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- Processor
For using IntranetRadio Server with sound data compression according to 
the ISO Psychoacoustic Model I, you need at least a Pentium-200 class 
CPU. However, compression with using simplified psychoacoustic model and 
compression without psychoacoustic model may be procceded with 
relatively slow computers.

Because decompressing is relatively more simple process, there is no 
need so fast processor for IntranetRadio Player. However, some sound 
losses may take place because of great loading of the CPU and, 
especially of using DOS boxes.

- Audio Input/Output
A 16-bit sound card is required. The card's driver should support 44,1 
kHz sampling frequency.

- Memory
About 256 kB free physical memory must be available, because both Server 
and Player buffers about 3 seconds of sound data.

- Operating System
Windows 95, Windows 98, Windows NT.

- Network
A TCP/IP network must be installed

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Installing the IntranetRadio
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Execute the setup.exe. After the acception your wish to continue the 
process the installing program asks you for a folder you would like to 
install IntranetRadio to. If you agree the proposed folder simple click 
the 'Next' button, otherwise change the folder.

The next (and the last) question - selecting the Start menu group, where 
IntranetRadio programs shortcuts will be added. Same as above, you can 
accept the suggested name or change it.

Now that's all you need to make the installation. Confirm the 
installation and everything is over.

Now you can execute IntranetRadio Server or IntranetRadio Player from 
the corresponding group of the Start menu.

To start the IntranetRadio automatically

The IntranetRadio Server or Player program can be started automatically 
when your system reboots.

Add the IntranetRadio program Irserver.exe or Irplayer.exe to your 
Startup menu. See your Windows documentation for information on adding 
programs to your Startup menu. 

When you have added the IntranetRadio program to your Startup menu, the 
next time the system is rebooted your IntranetRadio starts 
automatically.

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Working with the Server
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On starting the server first time it automatically turn into the 
configuring mode. Select the appropriate parameters and click the Apply 
button. Now IntranetRadio Server is ready to action. To execute the 
recording process click the ON/OFF button. (Next time, you start the 
Server it will start the recording automatically).

Server main window contains some visual and control elements. Recording 
indicator displays the state of the recording process. Graphical display 
shows frequency distribution of the recorded sound signal. Overload 
indicator appears if input signal overload is detected. To avoid signal 
distortion recording level should be adjusted by recording gain control.

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Configuring the Server
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From the server main window push the settings button to start the 
settings dialog. Switch between tabs to configure different settings 
sections.

Audio tab 
This section describes the settings in the Audio tab's fields.

- Sound input device
Determines wave input device used for sound sampling.
- Sampling parameters:
Determines parameters of sampling. In current version only 44,1 kHz, 16-
bit, mono sound is supported.
- Mixer device:
Determines mixer device used for recording gain adjusting.

Compression tab
This section describes the settings in the Compression tab's fields.

- Main algorithm
MPEG Layer I is only supported yet.
- Psychoacoustic model
Determines psychoacoustic model used while sound compressing. Now there 
are three models presented: ISO Psychoacoustic model I, Simplified 
psychoacouctic model (same as ISO except some calculating reduction) and 
"No psychoanalize" (only absolute thresolds of hearing used while 
calculating).
- Bitrate
Adjusts the resulting bitrate of compressed audio data. In current 
version only 128 kBit/sec is supported.

Network Tab 
This section describes the settings in the Network Tab's

- Network Address
Determines IP address which compressed audio stream is sent to. It may 
be a broadcast IP address (such as 10.4.1.255).
- Port
This field defines the IP port. It must be the same on both the server 
and client side.

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Working with the Player
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On starting the player first time it automatically turn into the 
configuring mode. Select the appropriate parameters and click the Apply 
button. Now IntranetRadio Player is ready to receive sound data. To 
execute the receiving process click the ON/OFF button. (Next time, you 
start the Player it will start the receiving automatically).

Player main window contains some visual and control elements. Receiving 
indicator displays the state of the receiving process. Graphical display 
shows frequency distribution of the received audio signal. Overload 
indicator appears if output signal clipping is happened in the 
decompressing process. To control output level of the sound output gain 
track bar may be used.

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Configuring the Player
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From the player main window push the settings button to start the 
settings dialog.

- Sound output device
Determines sound output device used for sound playing.
- Playing parameters
Determines parameters of playing. In alpha version only 44,1 kHz, 16-
bit, mono sound is supported.
- Port
This field defines the IP port. It must be the same on both the server 
and client side.

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Error messages
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No sound input/output devices in system

This error takes place if there are no sound card presented in your 
computer. Unfortunately if you computer hasn't a compatible sound card, 
IntranetRadio should not work. See system requirements for necessary 
sound card capabilities.

Sound input/output device error
The specified audio device is currently in use by another application. 
Close other applications using this audio device and try again. If the 
problem persists, reboot your computer.

No enough memory
There are not enough free memory for sound buffering. Please close 
unused applications to free the memory.

Winsock version 1.1 required
The IntranetRadio Server could not initialize the system network 
transport software. Make sure all of your networking systems are 
configured properly. 

Error while processing the socket
An error has come from a socket processing function. Make sure all your 
networking systems are configured properly. Make sure that the 
IntranetRadio program and another application are not trying to use the 
same port.

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Authors of the IntranetRadio
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The IntranetRadio programs are developed by SanychSoft company.

Please take a look to our main web page http://sanych.amur.ru 
to know last news about the products, download the last versions of the 
IntranetRadio and other programs and more...

Thank you for using IntranetRadio!
Copyright (c) 1999 SanychSoft company.
