Introduction
to the Internet and World Wide Web
© Copyright Brian Brown, 1998-2000. All rights
reserved.
6.0 Multimedia and
Communication
In this section you will learn about some new
multimedia communication methods that the Internet is using
today.
6.1
What about bits, bytes and bandwidth?
In this section you will learn about bits, bytes and bandwidth.
6.1.1 Bits
A computer stores information in digital format as a series of on
and off states, called logic 1's and logic 0's. The smallest
element of information in a computer is a bit, and can hold
either a 1 or 0.
6.1.2 Bytes
Obviously, a computer using only one bit can hold two states,
either a 1 or a 0. This is not practical for handling a lot of
information! So, more than one bit is grouped together. A Byte is
actually a grouping of 8 bits, and thus as a whole can hold 256
possible values. A computer uses a byte to hold characters, such
as the character 'A' , the digit '3' or the symbol '*'.
In computer language, the symbols K and M are used to denote thousand and million. The symbol B represents bytes and the symbol b represents bits.
From this, we can write the amount of memory in a computer as 64KB, meaning 64 thousand bytes (it can hold roughly 64 thousand characters).
Exercise
How much memory is 4Kb expressed as KB?
How many characters (roughly) can be held in 64MB of memory?
6.1.3 Bandwidth
When we transfer information across the Internet, we talk in
terms of how much information we can send or receive per second.
The maximum amount that can be sent at any one time is a
restriction of the connection we are using, and is called
bandwidth.
The bandwidth of a connection is expressed in terms of so many bits per second. For instance, you might have a dial-up connection to you ISP that supports 56Kbps (56 thousand bits per second). As there are eight bits in every character, dividing 56K by 8 gives us 7KB per second.
Bandwidth is usually expressed in bits per second. The higher the value, the more information that can be sent per second.
6.2 What is streaming audio and video?
Streaming audio and video is the ability to download video and
audio from the Internet and have this play without having to wait
for all of the file to be downloaded. This means streaming audio
and video can support "live" events, and viewers can
watch or listen to events as they occur.
Streaming audio and video requires special servers and software to be installed on your computer.
6.2.1 Streaming audio
The major problem associated with the traditional formats of
waveform audio (such as wave files) is the file size. When you
use a waveform audio file on a web page, the browser must
download the entire file before it can be played. For files of
reasonable size, this leads to long delays for the receiver.
Streaming audio addresses the issue of this delay by allowing the
file to be played whilst it is still being downloaded. Special
players are required for viewing and playing streaming audio
clips.
Streaming audio is primarily associated with Real Networks. "Real Player" supports the playing of streaming audio over the Internet. The advantages of using streaming audio are
When a user selects a streaming audio clip, the streaming audio player contacts the server and establishes the bandwidth and delays between the user computer and the host server. A few seconds of the clip is then downloaded into temporary buffer storage before the clip begins to play. As the clip begins to play, more content is downloaded and placed into temporary storage. If there is a congestion delay in the Internet connection, the clip continues to play using the contents of the buffer storage. Hopefully, before the buffer storage is exhausted, the congestion delay will cease and thus the buffer storage will fill up again. In this manner, the streaming player tries to achieve smooth playback of the clip. Without using storage, gaps or breaks in the audio would be evident when a congestion delay occurred.
A special content provider program is necessary for producing streaming audio clips. A limited free version can be downloaded from the Real Networks web site. In addition, to provide streaming audio clips from a server requires the use of a streaming server.
6.2.2 Streaming Video
Streaming video is very similar to streaming audio. We are faced
with the same problem of file size and the delay involved in
downloading the entire video file before it can be played on the
client computer. Streaming video addresses the issue of this
delay by allowing the file to be played whilst it is still being
downloaded. A special player is required for viewing and playing
streaming video.
Streaming video is primarily associated with Real Networks. "Real Player" and "Real Player G2" support the playing of streaming video (and audio) over the Internet. The advantages of using streaming video are
When a user selects a streaming video clip, the streaming video player contacts the server and establishes the bandwidth and delays between the user computer and the host server. A few seconds of the clip is then downloaded into temporary buffer storage before the clip begins to play. As the clip begins to play, more content is downloaded and placed into temporary storage. If there is a congestion delay in the Internet connection, the clip continues to play using the contents of the buffer storage. Hopefully, before the buffer storage is exhausted, the congestion delay will cease and thus the buffer storage will fill up again. In this manner, the streaming player tries to achieve smooth playback of the clip. Without using storage, gaps or breaks in the video would be evident when a congestion delay occurred.
A special content provider program is necessary for producing streaming video clips. A limited free version can be downloaded from the Real Networks web site. In addition, to provide streaming video clips from a server requires the use of a streaming server.
Try this exercise on streaming video and audio.
6.3 How can I communicate with others?
In this section you will learn about software that allows you to
communicate with others on the Internet.
6.3.1 Microsoft Net meeting
This software product supports the following
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Using the directory, you can find someone to communicate with and call them. If they answer, you can communicate using text chat, video or audio (provided you and they have the necessary hardware support). You can even exchange files such as documents or pictures.
One of the problems with net meeting is the audio tends to drop out (break up and becomes inaudible) when using it on the Internet, though it works fine over a high-speed company network. Net meeting is normally installed with Internet Explorer, or you can download it from http://www.microsoft.com/windows/netmeeting/. There is a web site dedicated to Netmeeting at http://www.netmeet.net/.
Try this exercise on communicating with others using netmeeting.
6.3.2 Ivisit
Ivisit is currently a free video conferencing package that allows
you similar functionality to that of net meeting.
Ivisit supports,
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One good thing about ivisit is the ability to communicate with more than one person at once. Another good feature is the quality of audio that is possible, though the video picture quality does suffer when using slow connections on the Internet. Ivisit can be downloaded from http://www.ivisit.com.
6.3.3 Icq and Powwow
These two programs allow you to communicate with your friends on
the Internet, using text or voice chat.
6.3.3.1 ICQ
One of the problems of talking with friends on the Internet is
knowing if they are online. This program lets you see if your
friends are on-line and provides you the means to contact them.
As soon as they log on, you can be notified.
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ICQ provides the following services
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In addition, ICQ provides a large user directory where you can post information about yourself. This directory can be searched by you or other ICQ users, so you can find people with similar interests. Icq can be downloaded from http://www.icq.com/download/.
6.3.3.2 Powwow
Another product that provides similar functionality to ICQ is
Powwow. It does provide some interesting animated effects in chat
mode, and lets you talk to multiple users at once.
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Powwow provides the following features,
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Powwow can be downloaded from http://ww2.tribal.com/download/default.cfm
6.4 What is a directory server?
A directory server is a host on the Internet that holds a list of
users. Not all directory servers are the same and most support
different products. This means a directory server that supports
Netmeeting will not support users using Ivisit.
6.5 Internet Relay Chat
Internet Relay Chat (IRC) allows you to meet online with people
of similar interests. IRC consists of a large number of channels
(a channel is like a room where messages are exchanged) that
contain group conversations. Channels can be created by anyone,
and users can join channels and exchange messages.
It is text based mode of communication. Users often use cryptic codes and abbreviations to signify phrases of speech, so they do not have to type whole words.
Channels are located on IRC servers, which often talk to each other and share channels, so that messages on one server are relayed to the same channels on other IRC servers.
To access IRC requires the use of an IRC client. One such client is available from http://www.mirc.co.uk/
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