Multimedia cho Joomla part 2 doc

Choosing the correct audio format to use on your website is imperative for the efficient delivery of the audio content to your site users... Examples of these are: The Web Content Access

Images can be created, edited, and saved into numerous formats Some of these

formats are more applicable for use on the Web than others

For more detailed image information, please view Chapter 4, Adding and Managing

Image Content.

Audio

Audio (or sound as we know it) can be used to inspire human emotion and deliver

information Audio is a major element of human entertainment, as well as a

contributing element to videos, gaming, and other multimedia presentations

The use of audio can add interest, be informative, and entertain An often overlooked

fact is that audio can also provide an interface for visually impaired users to attain

the information they require:

Internet is now an audio-rich delivery mechanism, with audio being easily

downloaded from websites and application portals Most modern computer setups

now include speakers, which depending on the way you look at it, has helped the

evolution of audio usage within web pages Possibly the equation goes the other way

and greater audio usage on web pages has specified the requirements for computer

users to need speakers

All of that said, gone are the dancing Santas that used to load into web pages,

and play a nasty Christmas MIDI file with no volume control! Now we are talking

about websites containing "podcasts on demand", and "dial up your own personal

radio station playlists", and impressive audio players including time counts and

player controls

Like images, sound files can be created and saved in many formats, including AAC,

MP3, MIDI, WAV, as well as many others Choosing the correct audio format to use

on your website is imperative for the efficient delivery of the audio content to your

site users

Video can be defined as a sequence of still images put together and displayed on a

screen to form the illusion of motion:

Video is one of the most powerful multimedia types, as it incorporates both images

and audio It can also contain text in the form of titles and descriptions

Video has been known as one of the most demanding media types to work with

due to the overheads of processing and working with large file sizes Transmission

and storage of video has often made it an unsuitable medium to use in certain

conditions However, things are changing rapidly, and video is now often linked

to or "streamed" into an application, rather than the files hosted themselves

Video can be saved in a variety of formats and compression types Some of these

will be very applicable, and others you should stay clear of for website use More

information about working with video can be found in Chapter 5, Using Video

within Your Joomla! Website.

Multimedia and web accessibility

Website accessibility means that people who have disabilities can understand,

interact, and navigate through web pages

One of the main principles of web accessibility is to design websites and web software,

which is flexible to meet different users' situations, preferences, and environments

With the Web becoming an increasingly important resource for the sharing of

information, many users are now going online for reference: health, commerce,

government, recreation, media, and many other resources It is essential that

people wanting to utilize the Web have equal access and equal opportunities

to these resources:

Another important consideration when building a website is that web accessibility

has legal obligations in certain countries Besides the important consideration to

all of your site users, there could also be legal reasons why accessibility should be

considered when building and maintaining your website

Can a multimedia website be accessible?

It is possible for a multimedia rich website to also be an accessible website However,

the level of accessibility options you choose to implement into your website are

decisions you need to make for your project The decision basis will often include

factors such as target audiences, country legalities, and project time and budgets

There are a number of accessibility standards used around the Web, which provide

accessibility guidelines and checklists to benchmark against Examples of these are:

The Web Content Accessibility Guidelines (WCAG)

The Web Content Accessibility Guidelines (WCAG) have become a world standard

for web accessibility, and falls into three 'compliance' categories:

1 A (also known as Level 1)

A website must comply with all checkpoints in Level 1 otherwise one or more

user groups will find it impossible to access information or functionality

2 AA (also known as Level 2)

A website should comply with all checkpoints in Level 2 otherwise one

or more groups will experience significant barriers to access information

or functionality

3 AAA (also known as Level 3)

A website may comply with all checkpoints in Level 3 otherwise one or more

groups will find it somewhat difficult to access information in the document

Section 508

Section 508 is a standard created by the US Federal Government It contains 16

checkpoints for testing your website against The first 11 checkpoints are exactly

equivalent to the WCAG A (Level 1) guidelines The last five checkpoints are partly

based on the WCAG guidelines, but are more extensive For further information

about this standard, please search for Section 508 on the Net

Site accessibility features are best considered at the start of a website project, and

then having these addressed during development It is much easier to take this

approach rather than address this issue retrospectively Fixing invalid site code and

You may come across situations where the type of content you wish to offer on your

site pages will never be accessible to certain audiences This is where decisions must

be made whether you make that content available in alternative formats An example

of this may be to include captions when playing a video, or to offer an audio version

of text documents

Throughout the development of your website, numerous software and online

evaluation tools can be used to help determine the accessibility of your website pages

An exhaustive list of these can be found on the Web, or at sites such as

More information on web accessibility

For further information and tools which can help you make your site accessible,

please visit the following resources:

3 http://en.wikipedia.org/wiki/Web_accessibility: Wikipedia's page

on accessibility guidelines

electronic and information technology is accessible to people with disabilities

Web browser support for multimedia

The Web was originally a text only medium, with browsers only being able to

display text in a single font, size, and color

With the explosion of the Internet, website browsers can now view images,

play audio and video A further development of the World Wide Web has been

the evolution of "streaming media" which allows the media playback to begin

without the files being fully downloaded first

There are many web browsers available Some of these are suitable for specific

purposes and others pride themselves on being the most lightweight, or the

fastest browser available

Most browsers have built-in media capabilities, which is an acknowledgement of the

growth of website multimedia Other browsers require plugins to play multimedia

content Plugins are programs, which extend your browser capabilities by making

making them compatible with additional media types When your browser

encounters a multimedia file, it hands over the data to the plugin in order to

play or display that file

You may have heard of the plugin "Adobe Flash Player", which enables you to play

Adobe movies through your web browser, or the "Windows Media Player" browser

plugin, which plays streaming audio, video, and presentations saved in Microsoft

formats Without these plugins installed into the web browser, this

media content on website pages cannot be effectively viewed:

This highlights the importance of offering multimedia material in numerous formats,

or if that is not an option, to provide the site users with clear instructions about the

media trying to load, and when possible, where to go and find a plugin in order to

play it

In this chapter, we have looked at the terminology "multimedia" and how this

description contains numerous types of media content

We have highlighted the Joomla! CMS platform and recognized its built-in

multimedia capabilities, as well as mentioned how these can be enhanced using

Joomla! Extensions As extensions enhance the default Joomla! installation, they

will receive a healthy coverage throughout the chapters

It is important to note website accessibility in this chapter, as it is much easier to

consider and integrate web accessibility into the start of website development, rather

than trying to address accessibility issues retrospectively More information about

accessibility and how it relates to specific media, is covered within each chapter