AGOCG logo
Graphics Multimedia VR Visualization Contents
Training Reports Workshops Briefings Index

Accessible Multimedia


Although the number of students with some disability is difficult to assess, they are significantly under represented in Higher Education. Estimates in the Dearing report put the number of students with some disability between two to four percent in H.E., compared with ten to twenty percent of the general population. As there is increasing emphasis on lifelong learning and widening participation, it is important that resources are available to all students. This need has been recognised with the founding of several groups, including DISinHE (Disability Information Systems in Higher Education) at the University of Dundee (see resources).

In recent years multimedia has become an important part of many training materials and other resources. It has the potential to offer many benefits, including improved quality of learning, wider access, greater flexibility for students and staff, and effectively engaging students interest. For users with impairment of one or more of their senses, multimedia has many advantages. For example, for those with visual impairment, text presented on the screen can be read out using a synthetic speech program, or a tone played when an error message appears. Usually, however, although applications and documentation may be multimedia overall, particular parts of the information are often bound to one media type.

There are a number of things both end-users and application designers can do to make multimedia, and computers in general, more accessible, with both software and hardware solutions (assistive technology). Providing such solutions not only benefits disabled students, but anyone who is handicapped by their environment. For example, users of Personal Digital Assistants have restricted visual capabilities.

This report looks at some of the guidelines that have been produced for delivering accessible multimedia documents and applications.

User Groups

Disabilities with regard to computer use can be broadly split into three main groups: visual impairments, hearing impairments, and motor impairments. Much of computing is very visual, this is the most developed area of multimedia technology, and there has been a great increase in the amount of graphics, video and animation used in applications. Consequently it is often the visually impaired who are in danger of being most disadvantaged by the increase in the use of multimedia.

Visual Impairments

Visual impairment includes the blind, those with reduced vision, and other visual problems such as colour blindness. Assistive technology to help the visually impaired has been available for sometime, for example screen readers and Braille output and input devices. These have mainly been concerned with reading simple text screens. However, with multimedia applications an increasing amount of information is being presented visually.

Colour blindness in some degree is the most common form of visual impairment. Although it need not present any problems, it is often overlooked when designing software. The easiest way to prevent this being a problem is to design all screens without using colour. Although colour is a very useful way of presenting additional information, where possible it should be redundant.

Hearing Impairments

Hearing impairment generally presents less of a problem for users of multimedia applications, as sound is usually used as an additional source of data, rather than the sole source. As with visual impairment, the easiest modification an application producer can make is to build in redundancy, for example, never providing audio speech clips without a text translation.

Motion Impairments

In this context impairments in the arms are the most important, restricting keyboard and mouse access, and therefore making computer use generally difficult. The simplest aids include altering certain key functions, such as turning off automatic key repeats, so that keys are not pressed accidentally. Adaptations include voice recognition software and predictive text entry, allowing text to be entered with few keystrokes.

Accessible Software

There has been a significant increase in the availability and use of multimedia courseware in recent years. One reason often stated for its use is the flexibility such materials can provide, allowing students to study in their own time at their own pace. However, unless such software is designed with accessibility for all its potential users in mind, it can pose significant problems for some students.

Several groups, including the Multimedia Enabling Technologies Group at the Open University, and Microsoft have developed general guidelines for the production of multimedia materials to ensure their wider accessibility. These include:

Screen layouts

  • Screens should be clear and uncluttered.
  • Information should be ordered consistently within the application to aid navigation.
  • Be consistent between applications, for example applications running under Windows follow Windows guidelines.
User-defined preferences
  • Users should be able to control sound selection and its alternative representation
  • Users should be able to customise font size in applications and documentation. Do not tune your application to a specific font size.
  • If possible, line widths should also be user definable.
  • Allow text to be saved as required by the user so that it can be read using other utilities.
  • Allow the user to customise all user interface timings, for example the maximum time allowed to respond where keyboard input is required.
Navigation and manipulation
  • Provide consistent keyboard access to all functions.
  • Provide mouse shortcuts for commonly used features.
  • If possible, provide customisable keyboard shortcuts.
Ease of reading screens
  • Avoid multiple columns where possible.
  • Icons need to be designed to be clearly visible and be customisable in size.
  • Use colour only as a redundant means of encoding information, and use a high contrast to ensure readability.
  • Do not put text over complex background images or patterns.
  • Add text labels to objects, buttons and icons, and be consistent in their placement.
  • Provide all documentation in an accessible electronic form, such as ASCII text or HTML.
  • Auditory information and cues
  • Where possible, the user should be able to select text and obtain speech output.
  • All information provided through sound should be available in a visual form as well. Build in redundancy.
  • Compatibility with enabling technologies
  • Applications should use and not conflict with special enabling features of the operating system (e.g. 'sticky' keys). Accessibility features are included with Mac OS 8.5, Windows 95 and NT 4, with additional features in Windows 98.


Since its conception in 1990 the Web has grown to form a huge body of hypermedia information. The underlying structure of web documents has the potential to make them very accessible. However, they are often not, with design considerations overriding structure and accessibility.

The Web Accessibility Initiative (WAI) provides guidelines for both page authors and those designing clients and authoring tools. Basic guidelines for writing accessible web pages include:

  • Every graphic image should have text associated with it, using the ALT tag.
  • Provide a text alternative to image maps.
  • Use a clear and consistent page structure to assist navigation.
  • Make link text descriptive, it should make sense when read alone.
  • Summarise Content or use the LONGDESC attribute (see below).
  • Provide captions or transcripts of audio content, and text or audio descriptions of video content.
  • Provide alternate content for scripting, applets or plug-ins so that no important information is lost when unsupported or turned off.
  • Avoid using tables to format text columns. Make sure cell-by-cell reading order makes sense for tabular data.
  • Validate the HTML & CSS (Cascading Style Sheets) of your site. Check accessibility with available tools, and with images, sounds & animations off. A good tool is Bobby (see Resources).
  • Test your pages using different browsers.

Recent developments, such as Cascading Style Sheets and HTML 4.0 have been designed to allow authors greater flexibility without sacrificing structure.

HTML 4.0

HTML 4.0 has additional structural elements. These allow tools to as search engines and screen readers to extract more information from the document. Examples include:
  • LONGDESC field allows a longer description to be added to an image.
  • FIELDSET and LEGEND elements organise form controls into semantically related groups.
  • OPTGROUP element groups menu options into related groups. Grouping menu options improves navigability.
  • Several new elements (THEAD, TBODY, TFOOT, COLGROUP, and COL) have been added to group table rows and columns into meaningful sections. Several new attributes ("scope", "headers", and "axes") label table cells so that non-visual browsers can render the table more easily.
  • OBJECT can be used to include any type of object, and if the browser cannot render it, it will render the OBJECT's marked up content instead. For example, with a client side image map, if the graphical version is not supported, a textual version of the image map can be provided.

Style sheets

Cascading Style Sheets were developed to provide more flexibility for page designers, and are fully integrated with HTML 4.0. By using style sheets the same HTML document can be tailored to display differently for different users, for example those requiring large print, using Braille readers, or speech synthesisers. They also remove the need to use structural elements to design pages, for example using heading tags to change the font size, which can lead to misleading representation in non-visual browsers.

The most recent version of style sheets, CSS2, allows the user to supply a style sheet which will override that provided by the page author, ensuring that the users needs are met. These style sheets are not restricted to standard items such as font, but could also be used to enhance the aural rendering of a document.

SMIL (Synchronized Multimedia Integration Language)

This is a simple XML (extended markup language) based language, similar in style to HTML, to allow control over media elements in a streamed multimedia presentation. As it is a plain text file, it is easy to create, even on the fly by Java servlets or CGI scripts, allowing the presentation to personalised, and potentially supporting users with different needs. The first commercial SMIL player is RealNetworks RealPlayer G2.

Java Accessibility

The Java programming language has become widely accepted, particularly in conjunction with Web applications. The Java Accessibility API is one of the core parts of the Java Foundation Classes (J.F.C.), allowing developers to write in support for assistive technology and devices.

Java applications run on a variety of platforms, using 'Virtual Machines'. These operating systems already have their own assistive technology. A bridge is needed between them and the Java accessibility support within the Java Virtual Machine. This bridge is currently being developed for the Win32 platform, and others will follow.


SAMI is Microsoft's Synchronized Accessible Media Interchange. It is an open standard, developed to allow closed captioning on a range of multimedia applications.

The caption information is provided in a separate file, allowing it to be added to existing media, and provide captions in several languages. The captioning file is time-synchronized to the media source file, which is played through the Windows Media Player.


Phone: 01382 345050
Fax: 01382 345509
DIS-in-HE is the Higher Education community's national clearing house for Disability Information Systems, funded by the Joint Information Systems Committee (JISC).

The Support Centre works closely with institutions to ensure the provision of appropriate technological support and advice for students and staff with disabilities.

It provides advice on support initiatives, accessibility and technology, and through its web site, it will provide a gateway to other relevant information, an index of current research, good practice guides and case studies.

Currently available guides include 'Teaching Everyone', which provides guidelines for using IT to assist in integrating students with disabilities in the learning environment.

Multimedia Enabling Technologies Group

Open University
Research and development in the Multimedia Enabling Technologies (MET) Group will focus on applications of information technology for teaching and learning that draw on innovations in multimedia and enabling technologies.

Web Accessibility Initiative (WAI)
The Web Accessibility Initiative (WAI), in co-ordination with other organisations, is pursuing accessibility of the Web through five primary areas of work: technology, guidelines, tools, education & outreach, and research & development.

CSS2 Specification
The full W3C Cascading Style Sheets level 2 recommendation.

National Center for Accessible Media
This is a research and development facility that works to make media accessible to underserved populations such as disabled persons, minority-language users, and people with low literacy skills.

Microsoft Accessibility
Details of Microsoft Accessibility products and information for developers, writers and testers to help create accessible products.

Apple - Disability Resources
Details of the Mac Universal Access software and a catalogue of third party accessibility products for the Mac.

Sun - Accessibility Site
Sun Microsystems' Enabling Technologies Program, providing details of Java Accessibility.

A web based tool to analyse web pages for their accessibility. The analysis of accessibility is based on the working draft of the W3C's WAI Page Author guidelines.

Graphics     Multimedia      Virtual Environments      Visualisation      Contents