Designing for Accessibility - Multimedia

Table of Contents

Overview

Layout and Structure

Navigation

Non Textual Content

Images

Image Maps

Rich Media

Flash

Multimedia

Tables

Forms

Scripting

Electronic Documents

Other

Validating for Accessibility

Resources

NCAM- Captioning Multimedia

WGBH- Captioning FAQ

W3C Synchronized Multimedia

FCC Consumer: Facts Closed Captioning

Joe Clack- Best Practices Online Captioning

Multimedia Presentations

Multimedia includes all audio, video, (including VHS tapes, DVDs, audio tapes) flash animations, slide shows, shockwave movies etc. On the web all multimedia should be captioned or at least have a text transcript or text descriptor.

Text Transcripts

A text transcript is a written version of the spoken word. Transcripts must be provided for all podcasts placed on public pages. Creating a text transcript can be time consuming and can be expensive. Transcripts can be created:

• From a script created prior to development of the multimedia presentation.
• By manually typing the text version of the audio file.
• By using voice recognition technology like DragonDictate or ViaVoice. These products are user specific and require the user to train the system. These technologies give individual users an easier process by which to create transcripts of their audio content.
• By using a technique called "shadowing" where a hearing person shadows the speakers words into a voice recognition system trained to their voice.
• By using a thrid party transcription services like eScriptionist.com or Casting Words. The price at these two services ranges between $0.75/ minute to $2.25 minute depending on number of speakers and turn around time.

Captions

Captions are on-screen text equivalents of audio content synchronized with the audio / video track to provide an equivalent access to people with hearing impairments. Captions are either open or closed. Open captions are always in view and cannot be turned off, whereas closed captions are under user control. On the web, captions are typically displayed through a client-side media player.

All major media players allow for automatic streaming of captions with the video content. The captions are stored in a secondary file which is delivered synchronized with the media track. Captioning is a two step process requiring

• Creating a text transcript of the audio track
• Synchronizing the transcript with the multimedia presentation.
  • This can be done manually using tools like NCAM MAGPie 2 or HiCaption. These are windows based tools that can add captions to SAMI, QucikTime and RealText. These help create the timed caption file synchronized to audio file and add it to the media
  • Automated using server side services like CaptionSync or CPC Captioning Software that provide synchronized caption file for the major media players.
• Use thrid party service like CaptionSync for complete captioning service.

Text Descriptions

These convey visual information of video or multimedia content. They are required for individuals with visual impairments and they also help expand visual awareness of people with learning and processing deficits. Text description can be presented:

• as alt attribute if less then 50 words
• a separate link (d-link)
• link to descriptive audio file

Descriptive Video

Audio Descriptions (AD) are simply additional narrative tracks that describe the current scene or setting. Described video intersperses explanations of important video with the normal audio of a multimedia presentation. For more information on Audio Descriptions