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Definitions of Visual Track and Auditory Track, Etc.

From: Hansen, Eric <ehansen@ets.org>
Date: Thu, 18 May 2000 14:02:56 -0400
To: "'w3c-wai-ua@w3.org'" <w3c-wai-ua@w3.org>
Message-id: <A12997152E36D31187A4000077893CFB036FC26B@rosnt46.ets.org>
Date: 18 May 2000, 13:58 hrs
To: UA List
From: Eric Hansen
Re: Definitions of Visual Track and Auditory Track

I took an assignment to suggest definitions for auditory track and visual
track. In order to do this, I have modified and added other definitions as
shown below.

PART 1: DEFINITIONS

Issue #1-1. Fix and add definition of "multimedia presentation"
The old definition of multimedia presentation is essentially a movie or
animation. That definition was evidently OK for previous WAI documents, but
needs to be refined, I think, to include only those movies and animations
that integrate both visual and auditory information.

Note that this document definition uses the term "track" a bit differently
than in some domains but it is generally consistent with the other WAI
documents.

Note that one could say that "A multimedia presentation has at least one
visual track and at least one auditory track" but instead I say simply "A
multimedia presentation has a visual track and an auditory track." Under
this definition when a different visual track or a different auditory track
is used, then it is a different multimedia presentation. I hope that this is
consistent.

New:

"Multimedia presentation

"For the purposes of this document, a multimedia presentation is a
presentation that synchronizes both auditory and visual information. This
includes, for example, any movie that has sound as well as animations that
present audio. A multimedia presentation has a visual track and an auditory
track.
====
Issue #1-2. Refine the definition of "visual track".
A visual track is the visual portion of a multimedia presentation.
====
Issue #1-3. Refine the definition of "auditory track".
A visual track is the auditory portion of a multimedia presentation.
====
Issue #1-4. Fix the definition of "audio presentation".
This revision makes explicit that an audio presentation may derive from any
numbers of sources: e.g., a local audio file, streaming audio, or text using
speech synthesis. This revision should be reviewed by Madeleine Rothberg and
others.

Old:
"Audio presentation 
"An audio presentation is a stand-alone audio track. Examples of audio
presentations include a musical performance, a radio-style news broadcast,
and a book reading. When an audio presentation includes natural language,
one can create a text equivalent for it (e.g., a text transcript)."

New:
"Audio presentation
"An audio presentation is a standalone audio track. Examples of audio
presentations include a musical performance, a radio-style news broadcast,
and a book reading. Audio presentations may be produced from a variety of
sources, e.g., local audio file, streaming audio, or text for speech
synthesis. When a prerecorded audio presentation includes natural language,
one can create a text equivalent for it (e.g., a text transcript). Note.
Short sounds (such as beeps) are not considered audio presentations."
====

Issue #1-5. Add the definition of "standalone visual track"

This is a new definition that handles visual presentations that lack a
synchronized audio track.  Note that this includes animations that lack a
synchronized audio track. This is necessary because these have different
"minimums" than other presentations.
Note. This is analogous to an "audio presentation", which is a standalone
auditory track. I use the term "standalone visual track" rather than
"standalone visual presentation" since that does not convey the idea of
motion video. I do not use the term "standalone video" since that does not
seem to include animations.

New:
"A standalone visual track is a dynamic visual presentation (e.g., movie or
animation) that lacks an synchronized auditory presentation."

In order to make this definition somewhat parallel to "audio presentation",
it is tempting to add an exclusion, such as by saying that very brief visual
presentations (a fraction of a second to a few seconds) is not considered
standalone visual track. (Of course, static visual presentations, i.e.,
images, are not dynamic.) But that may not be necessary. Comments welcome on
this issue.
====

Issue #1-6. Clarify that what must be done for "loosely synchronized"
multimedia presentations.

I think there deserves to be some discussion (perhaps in WCAG) regarding how
requirements accessibility requirements should be differ between multimedia
presentations that are tightly synchronized (movies) and ones that are
loosely synchronized (e.g., PowerPoint presentation with background music).
There was some discussion on WCAG on this topic some time ago (I think
pre-Recommendation).
====

Issue #1-7. Keep in mind (if not include in the document) several other
definitions.

Here are some other definitions that seemed necessary that but may not need
to appear in the document. (The terms themselves are used in my other
definitions.)

1.	Auditory presentation = a presentation that relies on hearing to
receive

2.	Synchronized auditory presentation = an auditory presentation that
is synchronized with another presentation, especially a dynamic visual
presentation

3.	Visual presentation = a presentation that relies on sight to receive

4.	Dynamic visual presentation = a visual presentation in which the
visual appearance changes over time
====

PART 2: REVISED CHECKPOINTS

As a point of discussion I have changed references to "configure" to
"control". I'd like to get reactions to this.
====

Issue #2-1. Fix the heading for checkpoints 4.5, 4.6, 4.7, 4.8.

OLD:
"Checkpoints for multimedia and audio presentations:"

NEW:
"Checkpoints for multimedia presentations, audio presentations, standalone
visual tracks:"
====

Issue #2-2. Fix checkpoint 4.8.

OLD:
"4.5 Allow the user to slow the presentation rate of audio, video, and
animations. [Priority 1] "
"Refer also to checkpoint 2.4."
"Techniques for checkpoint 4.5"

NEW:
"4.5 Allow the user to slow the presentation rate of multimedia
presentations, audio presentations, and standalone visual tracks. [Priority
1]"
"Refer also to checkpoint 2.4."
"Techniques for checkpoint 4.5"

====
Issue #2-3. Fix checkpoint 4.6.

OLD:
"4.6 Allow the user to start, stop, pause, advance, and rewind audio, video,
and animations. [Priority 1]"
"Techniques for checkpoint 4.6 "

NEW:
"4.6 Allow the user to start, stop, pause, advance, and rewind multimedia
presentations, audio presentations, and standalone visual tracks. [Priority
1]"
"Techniques for checkpoint 4.6"
====

Issue #2-4. Fix checkpoint 4.8.

OLD:
"4.8 Allow the user to configure the audio volume. [Priority 2] 
Techniques for checkpoint 4.8"

NEW:
"4.8 Allow the user to control the audio volume. [Priority 2] "
"Techniques for checkpoint 4.8"
====

Issue #2-5. Fix the heading for checkpoints 4.9, 4.10, and 4.11
Please see definitions for why I chose the term "auditory presentations".

OLD:
"Checkpoints for synthesized speech:"

NEW:
"Checkpoints for synthesized auditory presentations:"
====

Issue #2-6. Fix checkpoint 4.9.

OLD:
4.9 Allow the user to configure synthesized speech playback rate. [Priority
1] 
Techniques for checkpoint 4.9 

NEW:
4.9 Allow the user to control synthesized speech playback rate. [Priority 1]

Techniques for checkpoint 4.9 
====

Issue #2-7. Fix checkpoint 4.10.

OLD:
4.10 Allow the user to configure synthesized speech volume. [Priority 1] 
Techniques for checkpoint 4.10 

NEW:
4.10 Allow the user to control synthesized speech volume. [Priority 1] 
Techniques for checkpoint 4.10 
====

Issue #2-8. Fix checkpoint 4.11.

OLD:
4.11 Allow the user to configure synthesized speech pitch, gender, and other
articulation characteristics. [Priority 2] 
Techniques for checkpoint 4.11

NEW:
4.11 Allow the user to control synthesized speech pitch, gender, and other
articulation characteristics. [Priority 2] 
Techniques for checkpoint 4.11
====

PART 3: REVISED MINIMUM REQUIREMENTS

Important Note. The revised minimum requirements do not fully address the
issue of synthesized speech. I will have to try to tackle that one later.

From Ian (http://www.w3.org/WAI/UA/2000/05/ua-minreqs.html):
Old:
Checkpoint 4.5  Allow the user to slow the presentation rate of audio,
video, and animations. Refer to 9 May teleconference and 11 May
teleconference, Minimum: 
For a visual track (animation or movie): At least one setting between 40%
and 60% of the original speed. 
For a pre-recorded auditory track including stand-alone audio presentations:
At least one setting between 75% - 80% of the original speed. 
For a synchronized multimedia presentation: For any visual track that may be
slowed from 100% to to 80% of its original speed, need to synchronize visual
and auditory tracks. Below 80%, the user agent can drop out the auditory
track. 

New:

Minimum:
For a standalone visual track: At least one setting in the range of 40 to 60
percent of the original speed.
For an audio presentation: At least one setting in the range of 75 to 80
percent of the original speed. 
For a multimedia presentation: At least on setting in the range of 80 to 90
percent of original speed for both the auditory and visual tracks. At any
rate lower than 80 percent of the original speed, the user agent can drop
out the auditory track.

===========================
Eric G. Hansen, Ph.D.
Development Scientist
Educational Testing Service
ETS 12-R
Princeton, NJ 08541
609-734-5615 (Voice)
E-mail: ehansen@ets.org
(W) 609-734-5615 (Voice)
FAX 609-734-1090
Received on Thursday, 18 May 2000 14:04:54 GMT

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