Ensure Technology Supports Multimedia Content

Reading: Ensure technology supports multimedia content

Ensure technology supports multimedia content

Inside this reading:

Servers

Web servers

Server types and capacity

Bandwidth considerations

Bandwidth and download times

Compression techniques

Streaming

Plug-ins

Plug-in players

Multimedia protocols

Interoperability

Summary

Servers

Multimedia includes graphics, animation, audio, and video. Its use can greatly enhance the appeal of a web site and help fulfil business needs. An important part of web site production is ensuring that appropriate technology is available for the multimedia content to display and function correctly.

A server is a software application that carries out a task (meaning, it provides a service) on behalf of yet another piece of software called a client. A web server carries out tasks for browsers, such as Mozilla, Netscape, Internet Explorer and Safari (the clients). A web server is a computer with Internet broadcasting software installed that is connected to the Internet or Intranet 24 hours a day via a high speed, high bandwidth connection.

Other server (and client) software exists for other services such as email, printing, remote login, and even displaying graphical output. This is usually divided into file serving, allowing users to store and access files on a common computer; and application serving, where the software runs a computer program to carry out some task for the users. This was the original meaning of the term ‘server’. Web, mail, and database servers are what most people access when using the Internet. Server platforms are the operating systems (the underlying software and hardware) that drive the servers.

Types of servers include those in Table 2 below.

Table 2: Servers and what they do

Server type / Service provided
Application servers / remote access to software applications; sometimes called middleware application servers they work between database servers and the end user and often connect the two
Audio/Video servers / bring multimedia capabilities to web sites by enabling them to broadcast streaming multimedia content
Chat servers / enable a large number of users to interact in an environment similar to Internet newsgroups, with real-time discussion; includes Internet Relay Chat (IRC servers), which consists of various separate networks (or ‘nets’) of servers that allow users to connect to each other
Database servers / database processing and access
Fax servers / fax resources for documents (reducing reliance on phone resources for big companies)
File and print servers / file storage and printing services and include File Transfer Protocol (FTP) servers which are one of the Internet’s oldest services
Groupware servers / allow users to collaborate and work together in a virtual atmosphere via the Internet or an intranet
List servers / help manage mailing lists for public discussion or one-way lists that deliver announcements, newsletters or advertising
Mail servers / move and store mail over corporate networks and across the Internet
News servers / act as a distribution and delivery source for the thousands of public news groups currently accessible over the USENET news network
Proxy servers / sit between a client program (such as a web browser) and an external server (such as another server on the web) to filter requests, improve performance and share connections
Telnet servers / enable users to log on to a host computer and perform tasks as if they’re working on the remote computer itself
Web servers / are used to display multimedia content via the Internet; a web server basically serves static content to a web browser by loading a file from a disk and serving it across the network using http

Web servers

When a web site has been built and is ready to ‘go live’ its files need to be uploaded to a web server.

A professional web site will usually be hosted by a professional web host or ISP (Internet Service Provider). A corporate Intranet site is usually hosted internally within the organisation. It is essential that your web site is hosted on a server that is up to the job.

Server types and capacity

The type of server you use will mostly depend on the type of content your site contains. For example, if your site has streaming media it will need to be hosted on a streaming media server—one that uses specialised streaming software, streaming protocols and is capable of delivering multiple ‘streams’ of data simultaneously.

As a general rule, the more multimedia content, the faster and more powerful your server will need to be. If you believe your multimedia content may be accessed by large numbers of people at the same time, you will need to state this when selecting a host server. If necessary, liaise directly with the hosting company to confirm that multimedia formats, file sizes and estimated traffic can be accommodated.

Bandwidth considerations

Bandwidth refers to the amount of data that can be sent through a connection in a given time. As a web developer or quality assurance officer you need to know the bandwidth required by your web site’s users, as well as the bandwidth needs for the web site’s server.

For example, a home modem described as 56Kbps theoretically can transmit 56 kilobits (56000 bits) of data in one second. This speed is referred to as the ‘bit rate’ or ‘baud rate’. Bandwidth is often described as being a bit like a water pipe—the wider the pipe the more water can travel through it in a given period of time. Likewise, the bigger the bandwidth the more data can be transported along the connection. With higher bandwidth, web pages will download faster.

Bandwidth and download times

The following formula can calculate the length of time taken to download a web page at a given bandwidth.

/ Where:
t is time in seconds
f is file size in bits (1Kilobyte = 8,192 bits, 1Megabyte = 8,388,608 bits, 1Gigabyte = 8,589,934,592 bits)
bps is connection speed in bits per second

Download times and bandwidth: Calculations

How long would it take to download a 10MB video file using a 33Kbps dial up Internet connection or a 1.5Mbps ADSL connection?

Dial up connection

Step 1. Convert the file from Megabytes to bits bits

Step 2. Convert connection speed to bits per second 33Kbps = 33000bps

Step 3.Calculate the download time:

It will take 2,542 seconds, or over 43 minutes, to download a 10MB file using a 33Kbps dial up connection.

ADSL connection

Step 1. Convert the file from Megabytes to bits bits

Step 2. Convert connection speed to bits per second
1.5Mbps =1,572,864

Step 3.Calculate the download time:

It will take 53 seconds or less than 1 minute to download a 10MB file using a 1.5Mbps ADSL connection.

Hint: There is an easy way to convert bytes to bits using Google. In the Google search field enter ‘convert x to y’ where x is the number to be converted and y is the number to convert too and click search. Example ‘convert 1.5Mb to bits’, ‘convert 100MB to bits’, ‘convert 2542 seconds to minutes’.

Generally, the more multimedia content a web site has, the more bandwidth the server (and the user or client) will need. If your web site has good quality sound or video, your server will need a high level connection, meaning plenty of bandwidth. Likewise, if you expect your users to view video from your web site they’ll need a broadband connection. Keep in mind the number of users you expect to be accessing your site’s multimedia content at any given time, as this will also influence required bandwidth. If you anticipate heavy traffic, you may wish to check that your server is connected to the Internet via an Optical Carrier (optic fibre) line, which can transmit up to 622 Megabits per second.

Hosting deals often specify how much data/ bandwidth your web site can ‘use up’ in a given period of time—usually a month. Make sure that this amount will be adequate and that if you do exceed the bandwidth cap the penalty charges will be within the budget of the project.

Note: An intranet site usually has a faster download speed than a regular web site.

Compression techniques

Multimedia files are usually very large and when created for the web they are mostly compressed for storage and for streaming to minimise file size and reduce download time.

There are many kinds of compression techniques for different purposes. Jpegs for example are a compression technique invented to make photographs small enough for the web without losing too much quality. Sound formats such as mp3, wav and AIFF reduce file size by sampling the audio rather then playing ‘the whole thing’.

Each compression format has it own pros and cons. Ultimately it’s up to the developer to make sure a suitable compression format is used to produce the smallest possible file size while maintaining a satisfactory quality.

The user often needs to have a player installed on their computer that can decompress and play the file. Players sometimes come packaged with a browser, otherwise they need to be installed—usually by downloading them from the software maker’s web site.

Streaming

Audio, and particularly video, produce large files that can take a long time to download. Streaming media was developed to deal with this.

The media is sent to the client computer in a continuous stream and the viewer does not have to wait for the whole file to download before it starts to play. A media stream can be on demand or live. On demand streams are stored on a server for a long period of time, and are available to be transmitted at a user’s request. Live streams are only available at one particular time. You should check your project’s technical specifications for maximum multimedia file sizes and required file formats and compression techniques.

Plug-ins

A plug-in is software that adds new functionality to an existing piece of software. Thousands of plug-ins are available for all sorts of purposes. Your users will probably not be able to view your multimedia content unless they have installed a plug-in that uses the appropriate codec to decompress a file and play it.

A cautionary note: Sometimes users will already have the plug-in installed and there will be no problem, but there is a first time for everything. Complications associated with downloading and installing a plug-in can undermine the user’s experience of your web site.

Plug-in players

‘Players’ are some of the most common plug-ins available, they extend the functionality of web browsers by allowing video, audio and animations to play.

Figure 1: Media player plug-in

The use of plug-ins is an aspect of Internet evolution. The first web browser could only display text, although attempts to display media on computers date back to the earliest days of computing in the mid-20th century. By the early 1990s browsers were capable of displaying graphics. Now sounds, video and animations have become widespread and subsequently, so have plug-in players.

Consideration needs to be given to the availability of plug-ins, the complexity of installing them and their performance on different hardware and software configurations. It is generally unwise to expect users to download new or unusual plug-ins. Unless the site is experimental or ‘cutting-edge’, stick with plug-ins that are tried and true

Providing links to plug-ins

Plug-ins must be available to those users who do not already have them installed or who need to update an older version. Plug-ins are often free or offer a free version. Most developers choose to include a link to a web site where the user can download the plug-in. This link should be placed close to where the multimedia content sits on the web page.

Note: Many file types are playable by more than one plug-in application. For example, Real Media player, Windows Media Player and QuickTime Player can play an mp3 file type. It may be that the user does not need to download a new plug-in.

Some of the most common plug-ins for multimedia content on the web are:

Flash player (Flash animations)
Windows Media Player (video and audio)
Real player (audio and video)
QuickTime (audio and video)
Shockwave player (Games and multimedia created in Macromedia Director).

Multimedia protocols

When the Internet first began it was not about audio, video or animations—there weren’t even still images, though as mentioned there were early attempts to display media, the hardware wasn’t up to it at the time. The Internet was purely a tool for sharing text-based data.

With the invention of the World Wide Web and technological advances, people started adding photos, animations and sounds. These days we have audio and video, real time broadcasts, streaming media and even video conferencing.

Interoperability

As each new media capability is added, new Internet protocols are developed to ensure that information can be shared and understood by different technology. This is known as ‘interoperability’. Problems with web site multimedia can be the result of not complying with protocols.

The original web protocol is TCP/IP. This was enough for sending text. Since then many more have been created to deal with the various media types that have been added to the Internet’s capabilities. Some are:

RTP (Real-time Transport Protocol) for the transport of real-time data, including audio and video
RTSP (Real-time Streaming Protocol) for video and audio, which allows the end user to rewind, fast forward, play and stop media; RealPlayer is an example of an RTSP application.
ICQ for chat and other communication on the web
VoIP (Voice over Internet Protocol) for the routing of voice conversations over the Internet or any other IP-based network.

Summary

The Internet is now offering users a rich multimedia experience. This has come about by adding to the technological capabilities of the Internet and web browsers. An integral part of testing or quality assurance is ensuring that the multimedia content of a web site is supported by the available technology. This includes server capacity, bandwidth, plug-ins, protocols and compression techniques.

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