- 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>
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 UTC