Proposals and questions about "presentations" and "animations" [Issue 430] from Ian Jacobs on 2001-01-24 (w3c-wai-ua@w3.org from January to March 2001) (original) (raw)

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].

[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

Do not broaden checkpoint 3.2 to include other animations than animated images:

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]

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.

Change the content type label from "Animation" to "Image" (since this is only about animated images).

Proposal 4: Checkpoint 3.4

Delete "motionless," since this is only about blinking.

Allow the user to configure the user agent to render blinking images as motionless, unblinking images. Allow the user to configure the user agent to render blinking images as unblinking images.

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:

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?
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