- From: Ian Jacobs <ij@w3.org>
- Date: Wed, 24 Jan 2001 14:40:13 -0500
- To: w3c-wai-ua@w3.org
Hello,
Per our action item of the 9 Jan 2001 teleconference [1], Eric
and I have discussed the definitions of "animation",
"presentation" in light of issue 430 [2]. Please consider the
following proposals and questions based on that discussion. The
checkpoints in this email are those of the 16 Jan 2001 draft [3].
- Ian
[1]
http://lists.w3.org/Archives/Public/w3c-wai-ua/2001JanMar/0071.html
[2] http://server.rehab.uiuc.edu/ua-issues/issues-linear-lc2.html#430
[3] http://www.w3.org/WAI/UA/WD-UAAG10-20010116/
-------------------------------------------------
Proposal 1: Delete the formal term "presentation"
-------------------------------------------------
A "presentation" may mean a number of things:
- A series of status slides that together convey a story;
- A video-only presentation (e.g., a silent movie);
- An audio-only presentation (e.g., a radio show);
- A synchronized collection of different pieces of content
(e.g., created in SMIL).
This last meaning is the one used in the glossary of the
16 January 2001 draft.
We might limit our usage of the term "presentation" to mean
"content with an inherent time component" (as opposed to one or
more static Web pages), but I don't think that we should. Rather,
I propose that:
a) We use the following terms instead of the catch-all
"presentation": audio, video, animation, animated image,
and synchronized content. I mention these because
they (should) all appear in checkpoints 4.4 and 4.5.
b) We may use the term "presentation" in an informal manner
(as one would in English) in UAAG 1.0, but we should
avoid it where a particular meaning might be inferred.
c) We delete the term "presentation" from the glossary.
-------------------------------------------------
Proposal 2: About animations
-------------------------------------------------
Refer to email sent to Chris Lilley requesting info
on animations:
http://lists.w3.org/Archives/Public/w3c-wai-ua/2001JanMar/0118.html
Suppose for the proposals below that the definition of "animation"
includes "animated images".
--------------------------
Proposal 3: Checkpoint 3.2
--------------------------
1) Do not broaden checkpoint 3.2 to include other animations
than animated images:
<OLD>
Allow the user to configure the user agent not to render
audio, video, or animated images except on explicit request
from the user. In this configuration, provide an option to
render a placeholder in context for each unrendered source
of audio, video, or animated image. When placeholders are
rendered, allow the user to activate each placeholder
individually and replace it with the original
author-supplied content. [Priority 1]
</OLD>
Rationale: The "placeholder" requirements of 3.2 make it
difficult to imagine how this would be done for animations
in general, created through scripts, style sheets, and
markup languages. Note also that the user can control a more
general class of animations per the requirements of Guideline 4.
2) Change the content type label from "Animation" to "Image"
(since this is only about animated images).
--------------------------
Proposal 4: Checkpoint 3.4
--------------------------
1) Delete "motionless," since this is only about blinking.
<OLD>
Allow the user to configure the user agent to render blinking
images as motionless, unblinking images.
</OLD>
<NEW>
Allow the user to configure the user agent to render blinking
images as unblinking images.
</NEW>
2) Change the content type label from "Animation" to "Image"
(since this is only about animated images).
-------------------
Question about checkpoints 4.4/4.5/4.7/4.8
-------------------
Question: For checkpoints 4.4 and 4.5, are these checkpoints
intended to require control of synchronized multimedia
presentations? Here are the checkpoints:
--------
4.4 Allow the user to slow the presentation rate of audio,
video and animations. For a visual track, provide at least
one setting between 40% and 60% of the original speed. For a
prerecorded audio track including audio-only presentations,
provide at least one setting between 75% and 80% of the
original speed. When the user agent allows the user to slow
the visual track of a synchronized multimedia presentation
to between 100% and 80% of its original speed, synchronize
the visual and audio tracks. Below 80%, the user agent is
not required to render the audio track. The user agent is
not required to satisfy this checkpoint for audio, video and
animations whose recognized role is to create a purely
stylistic effect. [Priority 1]
4.5 Allow the user to stop, pause, resume, fast advance, and
fast reverse audio, video, and animations that last three or
more seconds at their default playback rate. The user agent
is not required to satisfy this checkpoint for audio, video
and animations whose recognized role is to create a purely
stylistic effect. [Priority 1]
--------
Note also checkpoint 2.5:
2.5 Respect author-specified synchronization cues during
rendering.
This means that if the user slows down audio per checkpoint
4.4 and that audio is part of a synchronized presentation, then
the user agent should slow down the entire presentation
(respecting synchronization cues). Do other people have
the same understanding?
So:
1) If 4.4 (and/or 4.5) includes control over synchronized content,
should we make this clearer, or is the cross reference to
checkpoint 2.5 sufficient?
2) If 4.4 (and/or 4.5) does not include control over
synchronized content and only is about individual source sof
video, audio, or animation, then should we make this clearer?
I don't have a proposal for changing 4.4 and 4.5; I await
feedback from the WG.
Proposal:
- If animated images are a subclass of animations, then
checkpoints 4.4, 4.5, 4.7, and 4.8 require addition of
the "Image" content type label.
--
Ian Jacobs (jacobs@w3.org) http://www.w3.org/People/Jacobs
Tel: +1 831 457-2842
Cell: +1 917 450-8783
Received on Wednesday, 24 January 2001 14:40:16 UTC