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A Proposal for Multimedia-Related Terms

From: Eric Hansen <ehansen7@hotmail.com>
Date: Thu, 29 Jun 2000 02:22:07 EDT
Message-ID: <20000629062207.35664.qmail@hotmail.com>
To: w3c-wai-ua@w3.org
Date: 29 June 2000, 2:11 hrs
To: UA List
From: Eric Hansen
Re:  A Proposal for Multimedia-Related Terms

I have read Ian Jacob's memo "Thoughts on multimedia and some definitions" 
[1] and Al Gilman's comments on that memo [2]. I found Ian's memo to provide 
a good summary of the conversation and issues raised. I have minor comments, 
mostly about word usage but may communicate them later if warranted. I think 
I agree with most of what I heard Al saying. In both these memos I see an 
emphasis on the importance of construct of "message". I think that certain 
areas of agreement are emerging.

This memo proposes a new/refined definition for multimedia related terms. I 
wish I had more time to explain what I am thinking but I generally feel good 
about what I have proposed. I think I see light at the end of the tunnel. 
Essentially, I'd like to expand the definition multimedia presentation to 
cover a greater variety of presentations and also to give developers of Web 
content and of user agents greater flexibility in deconstructing multimedia 
presentations into there constituent parts if necessary for the purpose of 
developing accessibility content.

Objects, presentations, multimedia presentation, auditory presentation, 
visual presentation, tactile presentation, etc.

1. Audio or audio object - output from an audio viewport [NOTE. I am not 
certain enough of the "viewport" model to know if this is fully accurate and 
consistent. Same for the next two sentences. In any case, I think we 
recognize the importance of this base-level construct that is somewhat 
divorced from the notion of "message".]
2. Visual object - visual output (may include graphics, texts, and visual 
portions of movies and animations); output from a visual viewport
3. Tactile object - tactile output (via braille, raised-line drawing, or 
manipulable) from a tactile viewport

4. Presentation - information intended to deliver a message, i.e., to 
communicate a coherent body of information to a user.

5. Audio track - an audio object that is intended as a whole or partial 
presentation. An audio track can, but does not necessarily correspond to a 
single audio channel (left or right audio channel).
6. Visual track - a visual object that is intended as a whole or partial 
presentation. A visual track does not necessarily correspond to a single 
physical or software object. A visual track can be text-based or graphic, 
static or animated. [This idea of it possibly being static is important and, 
I think, necessary.]
7. Tactile track - a tactile object that is intended as a whole or partial 
presentation. This does not necessarily correspond to a single physical or 
logical track on the storage or delivery media.

8. Audio-only presentation - audio presentation; a presentation consisting 
exclusively of one or more audio tracks presented concurrently or in series
9. Visual-only presentation - visual presentation (NEW); a presentation 
consisting exclusively of one or more visual tracks presented concurrently 
or in series
10. Tactile presentation - a tactile-only presentation; a presentation 
consisting exclusively of one or more tactile tracks presented concurrently 
or in series
11. Multimedia presentation - virtually every other kind of presentation, 
except audio-only presentations and visual-only presentations.

Special or legacy terms:
1. Auditory track - an audio track that is part of a multimedia presentation
2. Audio presentation - audio-only presentation
3. Standalone visual track - a visual presentation consisting of one visual 
track

Requirements for Different Types of Presentations
1. Audio-only presentation - provide a text equivalent (text transcript) and 
captions [captions is implied in WCAG 1.0]
2. Visual-only presentation - provide a text equivalent of the visual track
3. Multimedia presentation - provide auditory descriptions, captions, 
collated text transcript

====

Some varieties of multimedia presentation are as follows:

Heavy Reliance on Both Auditory and Visual Tracks. This kind of multimedia 
presentation places heavy reliance on both the auditory and visual tracks in 
order to convey its message. Understanding such presentations typically 
requires both the visual and auditory tracks and the tracks typically must 
be closely synchronized. Imagine an instructional multimedia presentation 
designed to teach how to cook a certain meal. The visual track shows the 
instructor preparing and heating the ingredients and then arranging the 
finished items on a platter. The auditory track must be closely synchronized 
with the visual track since the meaning of the instructors' comments would 
not make sense to the student unless it was apparent which items were being 
referred to and at what stage of the process. Most movies and television 
programs fall into this category.

Auditory Track With "Background" Visual Track. This kind of multimedia 
presentation places heavy reliance on the auditory track and light or 
negligible reliance on visual track to convey its message.

Visual Track With "Background" Auditory Track. This kind of multimedia 
presentation places heavy reliance on the visual track and light or 
negligible reliance on the auditory track to convey its message.


REFERENCES

[1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0517.html
[2] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0520.html

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Received on Thursday, 29 June 2000 02:22:39 GMT

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