ACCESSIBILITY OF MULTIMEDIA RESOURCES IN WEB

Lourdes Moreno, Ana Iglesias and Paloma Martínez

Computer Science Department, Universidad Carlos III de Madrid,

Avda. Universidad 30 28911 Madrid, Spain

Keywords: Multimedia accessibility, usability, user interfaces, user needs, adaptability, caption, audio description.

Abstract: This paper emphasises the importance of providing accessibility of Web-based information resources for

everybody, not only for people with disabilities. Due to the continuous technical and social changes of the

Web, it is necessary to have in mind that new scenarios and user behaviour are appearing. Nowadays, most

of Web sites use multimedia resources and it is indispensable to provide accessibility not only to the

resource content, but the access to the resource in the Web site. This work summarises some items to take

into account in order to make accessible a multimedia resource and present some best practices including

on-line multimedia resources in a Web site.

1 INTRODUCTION

Due to the obvious increment in the use of

information technology, such as Internet, it is

necessary to have in mind accessibility issues when

new elements are included in the Web, as

audiovisual contents. Nowadays, most of Web sites

include audiovisual resources (audio, video,

animations etc.). Moreover, thanks to the

convergence of Internet with television, mobile

telephones, videogames, etc., which is transforming

the areas of communication, we can find Web-sites

collections as “Web 2.0” (O'Reilly, 2005) where the

majority of the Webs are based on a shared

collection of visual and audiovisual resources (p.e.

Flickr (Flickr, 2006), Youtube (YouTube, Inc.

2006), etc.). The presence of these new

technological elements in the Web when

accessibility issues are not taken into account

increments the digital breach and creates access

barriers not only for disabled people but for all of us.

2 TECHNOLOGIES FOR

DEVELOPING ACCESSIBLE

MULTIMEDIA CONTENTS

Technological resources are useful for developing

and using accessible contents. For instance, user

agents give access to the Web information; software

for developing and editing accessible contents; or

authoring tools for making easier the production of

accessible resources or adapting non-accessible

contents

Assistive technologies are very useful for

accessing Web resources. As far as research in

accessibility issues in technology is concerned, we

can highlight the potential of the eXtensible Markup

Language (XML) (W3C, 2006b) with the use of

metadata. This language is able to provide

adaptability of contents according to the user profile.

This is a good solution and it goes beyond the Web

accessibility in the multimedia contents.

On the other hand, inclusive and standard

methodologies (Lawton, 2006) are also useful for

developing accessible products. For instance, World

Wide Web Consortium (W3C) (W3C,

1994)provides standards for becoming the Web a

universal space of information. Different standards

470

Moreno L., Iglesias A. and Martínez P. (2007).

ACCESSIBILITY OF MULTIMEDIA RESOURCES IN WEB.

In Proceedings of the Third International Conference on Web Information Systems and Technologies - Web Interfaces and Applications, pages 470-473

DOI: 10.5220/0001288704700473

 SciTePress

can be applied, as the markup languages: XML,

eXtensible Hypertext Markup Language (XHTML)

or Cascading Style Sheets (CSS).

Specifications about audiovisual accessibility can

be applied too, as the Synchronized Multimedia

Integration Language (SMIL) to synchronize audio

and video (see section 3.2); Scalable Vector

Graphics (SVG) to describe XML Graphics; or the

Web Accessibility Initiative (WAI) which develops

guidelines to accessibility for different components.

Multimedia and audiovisual contents are specially

treated in WCAG 1.0 (W3C, 1999a). Nowadays,

they are working in the WCAG 2.0 (W3C, 2006a), it

demands alternative contents (caption, audio

description, extended audio descriptions and sign

language interpretation) to achieve different levels

of accessibility.

Nowadays there exist a great number of tools

oriented to the development and support of

multimedia on the Web. In this way, authoring tools

help us to create audiovisual contents integrating

caption and/or audio description, or help us to edit

them so that prerecorded multimedia can be included

(NCAM, 2006).

Due to these possibilities (languages, players,

editors, etc.) are not always compatible some with

others that the task of making multimedia accessible

is sometimes really difficult, but it is not impossible.

3 ACCESS TO MULTIMEDIA

WEB CONTENTS

Going back to the accessibility definition, a

multimedia content is accessible when a user can

access that content, regardless whether his access

characteristics and context of use. Sometimes we

can find in Web-sites accessible contents (offering

alternatives as captions and/or audio description),

but non-accessible resources because they are

reproduced via a control that does not appear in

every navigator. Or vice-versa, sometimes it is

possible to access the multimedia resource, but the

resource’s content is not accessible because it does

not offer alternative contents. In conclusion, we need

to ensure two different requirements for

accessibility:

- That the multimedia content is accessible

- That the access to the multimedia resource is

accessible.

Moreover, we can not forgot the necessity of

integrate the multimedia contents in an accessible

and usable user interface (Web page, player, etc.).

Then, the contrast of colours, accessible buttons for

control (alternative texts), etc. in the interface must

be taken into account. Furthermore, the user should

be allowed to interact with every hypermedia

element in the interface, controlling them device-

independently.

4 CASE STUDY

The case of study has been carried out in “The

Spanish Centre of Captioning and Audio description

(CESyA)” (CESyA, 2005). One of the main goals of

this centre is to study how to integrate accessible

multimedia resources in the media. This paper

presents some experiments studying the best way to

integrate a multimedia resource (a video called

“Nicolás”) in Internet in an accessible way.

This section describes how to make accessible

the video’s content and how to integrate the video in

the Web interface maintaining the accessibility.

Making accessible the video’s content means to

follow the current Web Content Accessibility

Guidelines (WCAG) and to provide synchronized

alternative contents such as caption and audio

description. Two different options can be

implemented for making accessible the video:

1. Video with open audio description and

caption. This option permits to create accessible

videos, but it has a big inconvenience: the user will

have not possibility of controlling the resource

reproduction, choosing if s/he prefers or not to play

the video or audio means separately in each moment.

2. Video with closed audio description and

caption, separating audio and text. There are

different options to create and edit a resource in

different formats. In this case, the system provides

the control to the user, allowing to adapt the

reproduction of the video according to his/her

current necessities.

This second option is more usable, because it

provides more control of the video reproduction and

adapts better to the user necessities.

Our studies implement this option. We have used

SMIL (W3C, 2006c) for the implementation,

following the recommendations of W3C, and the

video edition has been performed. The first step of

the edition was to separate the soundtrack from the

video.

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Table1: Advantages and Disadvantages implementing accessibility in multimedia resources.

Next, we put our attention in finding a

compatible format for captions and finally, the

accessible video was created with SMIL.

4.1 Integrating the Video Resource in

an Accessible Way

The experiment being carried out here has been

defined in a Inclusive Design methodological

framework, with the application of techniques such

as User Profiles, Person, Scenarios in order to

contemplate access characteristics and contexts of

use with every kind of users when accessing the

multimedia Web resources. This research is based

on fictions users but with real information. As a

result of this analysis it was decided to implement

the following possibilities as alternatives to make

easier the accessible access to the multimedia

resources which are going to be shown next and

summarised in Table 1.

1. Integrate a multimedia resource associating it

with a player integrated by a control found on the

Web page. This implementation option is

independent from the resource format. The most

common method to include multimedia elements on

a Web page is using the element <embed> (Clark,

2004), but it does not form part of the specifications

of the HyperText Markup Language (HTML) or

XHTML. If <embed> is used on a Web page, the

code is not accessible according to WCAG. Most of

Web designers prefer to use the element <object>

(W3C, 1999b) to add multimedia fulfilling guideline

of WCAG. But there are navigators that are not able

to correctly interpret this element. There is another

option to include multimedia using this design

(McLellan, 2002) and is frequently used by the Web

designers. This technique edits the code so that the

video can be reproduced as a Flash resource. Finally,

the implementation option studied in our experiment

used SMIL and the element <object> to include

multimedia into the Web page.

2. Integrate an audiovisual content using Flash in

the browser without having an associated player.

The implementation of this option can be done

editing the video with Flash (Adobe, 2006) having in

mind the accessibility criteria given by Adobe

Macromedia Flash. Although Flash is not a public-

domain software, this software is compatible with

most of the navigators. This option permits to use

the connector integrated without the necessity of

installing a new player. Moreover, Flash allows to

define captions and reproduce them.

3. Integrate an audiovisual content with SMIL in

the code XHTML. Other implementation

possibility is to use the profile SMIL+XHTML de

SMIL 2.0 (W3C, 2002). This option has a problem:

currently, this profile can only be reproduced using

user agent Internet Explorer (version 6.0 and

higher), but it is supposed that in the future other

navigators will permit it too. On the other hand, this

implementation has a big advantage: it can be

Access Method Advantages Disadvantages

Player integrated

into the Web page

- <object> or <embed>

- <object> in Flash

- <object> in XHTML

- <object> in SMIL

- Compatible with any

player

- No control of the reproduction

- An integrated player is needed

- <object> or <embed> are not

completely accessible

Flash + player - <object> in XHTML - Compatible with most

of navigators

- An integrated player is

not needed

- Flash is not public-domain

software

- The adaptability and

reproduction control depends on

the resource design

SMIL+XHTML SMIL+XHTML profile - Provides adaptability by

controlling the video

reproduction

- Currently only user agent

Internet Explorer can reproduce

External player SMIL - Provides adaptability by

controlling the video

reproduction

- Each player detect different

characteristics of SMIL

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472

directly integrated in the XHTML code without any

player associated via the <object> element.

4. Associate the reproduction of an audiovisual

content to an external player. In order to include

adaptability to the user, providing him/her some

control on the reproduction of the video, we can use

SMIL combined with any external player compatible

with this language. In our experiment, we have use

RealPlayer (Realnetworks, 2006) as external player.

The implemented interface shown in Figure 1

provides different alternatives for the video

reproduction (including audio description, captions,

both or none).

The user can choose in every moment of the

interaction which media want to reproduce, adapting

him/herself the interface according his/her current

necessities of access. Nowadays, we are still

working on the Web page design, improving its

usability and accessibility.

Figure 1: Interface of implementation SMIL with the user

control in RealPlayer.

As a conclusion, different implementation

options have been studied for integrating accessible

videos into Web pages. All the implementation

options provide high level of accessibility to the

multimedia resources, but there exist different

accessibility advantages and disadvantages when

different technology is used. Table 1 summarizes

this information.

This work has been partially supported by the “The

Spanish Centre of Captioning and Audio description

(CESyA)”.

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