- From: Dave Singer <singer@apple.com>
- Date: Sat, 9 Jun 2007 14:26:09 -0700
At 16:35 +0100 9/06/07, Benjamin Hawkes-Lewis wrote: >Dave Singer wrote: >>we promised to get back to the whatwg with a proposal for a way to >>handle accessibility for timed media, and here it is. sorry it >>took a while... > >Three cheers for Apple for trying to tackle some of the >accessibility issues around video content! :) Many thanks for all your helpful comments! >Without trying to assess whether CSS media queries are the best >approach generally, here's three particular issues I wanted to raise: > >1. Property values > >I honestly don't think the property values are well-named. "either" >is confusing and vague; "dont-want" is a misspelled colloquialism. We struggled with this also; suggestions are welcome. >How about one of the following possibilities: > >captions: wanted >captions: unwanted >captions: no-preference > >(This seems more natural to me than the original proposal.) > >/or/ > >captions: prefer >captions: prefer-not >captions: no-preference > >(Has the consistency of using the same word as the basis for each >value. OTOH "prefer-not" and "no-preference" may be confusing if >your English isn't that good.) > >/or/ > >captions: desired >captions: undesired >captions: no-preference > >("desire" has the minor advantages of being in Ogden's basic English >word list and being common to Romance languages thanks to a Latin >root. OTOH it's slightly longer.) nice (in my personal opinion). > >2. Conflict resolution > >The proposal does not describe how conflicts such as the following >would be resolved: > >User specifies: > >captions: want >high-contrast-video: want > >Author codes: > ><video ... > > <source media="all and (captions: want;high-contrast-video: >dont-want)" ... /> > <source media="all and (captions: dont-want;high-contrast-video: >want)" ... /> ></video> There is no suitable source here; it's best to have something (late) in the list which is less restrictive. >Because style rules cascade, this sort of conflict doesn't matter >when media queries are applied to styles. But you can only view one >video source. > >3. (Even more) special requirements > >The suggested list of media features is (self-confessedly) not >exhaustive. Here's some things that seem to be missing: > >a) I should think sign-language interpretation needs to be in there. > >sign-interpretation: want | dont-want | either (default: want) > >Unless we want to treat sign interpretation as a special form of >subtitling. How is subtitling in various languages to be handled? I think we assume that a language attribute can also be specified, as today. I have to confess I saw the BBC story about sign-language soon after sending this round internally. But I need to do some study on the naming of sign languages and whether they have ISO codes. Is it true that if I say that the human language is ISO 639-2 code XXX, and that it's signed, there is only one choice for what the sign language is (I don't think so -- isn't american sign language different from british)? Alternatively, are there ISO or IETF codes for sign languages themselves? > >b) Would full descriptive transcriptions (e.g. for the deafblind) >fit into this media feature-based scheme or not? > >transcription: want | dont-want | either (default: either) how are these presented to a deafblind user? > >c) How about screening out visual content dangerous to those with >photosensitive epilepsy, an problem that has just made headlines in >the UK: > >http://news.bbc.co.uk/2/hi/uk_news/england/london/6724245.stm > >Perhaps: > >max-flashes-per-second: <integer> | any (default: 3) > >Where the UA must not show visual content if the user is selecting >for a lower number of flashes per second. By default UAs should be >configured not to display content which breaches safety levels; the >default value should be 3 /not/ any. I think we'd prefer not to get into quantitative measures here, but a boolean "this program is unsuitable for those prone to epilepsy induced by flashing lights" might make sense. epilepsy: dont-want -:) > >Compare: > >http://www.w3.org/TR/2007/WD-WCAG20-TECHS-20070517/Overview.html#G19 > >d) Facilitating people with cognitive disabilities within a media >query framework is trickier. Some might prefer content which has >been stripped down to simple essentials. Some might prefer content >which has extra explanations. Some might benefit from a media query >based on reading level. Compare the discussion of assessing >readability levels at: > >http://juicystudio.com/services/readability.php > >reading-level: <integer> | basic | average | complex | any (default: any) > >Where the integer would be how many years of schooling it would take >an average person to understand the content: basic could be (say) 9, >average could be 12, and complex could be 17 (post-graduate). > >This wouldn't be easily testable, but it might be useful nevertheless. Yes, this isn't testable, and is quantitative. > >Postscript: This isn't an accessibility issue but /if/ media queries >are adopted as a mechanism for serving up the best content for a >person's abilities, I wonder if they could also be used to enhance >parental control systems using queries based on PICS: > >http://www.w3.org/PICS/ > >So for example, one <source> might have a music video featuring >uncensored swearing, and another <source> might have the same video >with the swearing beeped out. > >-- >Benjamin Hawkes-Lewis -- David Singer Apple/QuickTime
Received on Saturday, 9 June 2007 14:26:09 UTC