W3C home > Mailing lists > Public > public-html@w3.org > November 2010

Re: Categorization of media a11y requirements

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 17 Nov 2010 21:21:54 +1100
Message-ID: <AANLkTin63KZR7LvnUbnoUT8Xecyw=pMbttKMpYGzn+Vy@mail.gmail.com>
To: "HTML Accessibility Task Force (public-html-a11y@w3.org)" <public-html-a11y@w3.org>
Cc: Frank Olivier <Frank.Olivier@microsoft.com>, "public-html@w3.org" <public-html@w3.org>
The spec classifications as proposed by Frank and discussed in this
thread have now found entry into the checklist at
http://www.w3.org/WAI/PF/HTML/wiki/Media_Accessibility_Checklist .

Cheers,
Silvia.

On Fri, Nov 5, 2010 at 11:17 PM, Silvia Pfeiffer
<silviapfeiffer1@gmail.com> wrote:
> On Fri, Nov 5, 2010 at 8:25 PM, Maciej Stachowiak <mjs@apple.com> wrote:
>>
>>
>> On Nov 5, 2010, at 8:50 AM, Maciej Stachowiak wrote:
>>
>>>
>>> (1) What are the kinds of changes needed to the HTML5 spec to support this requirement?
>>
>> Here is my attempt to answer this question for the following items, based on our discussions yesterday:
>>
>>>
>>> On Nov 4, 2010, at 5:55 PM, Frank Olivier wrote:
>>>
>>>> SPECNEW, SPECCED: (SL-1) Support sign-language video either as a track as part of a media resource or as an external file.
>>
>> The <track> element currently only supports textual formats; would need to support video format and an appropriate value for the kind attribute. Another possibility is a mechanism to associate two <video> elements to play in sync.
>
>
> We have bug 9452 for that:
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=9452
>
>
>
>>>> SPECNEW, SPECCED: (SL-2) Support the synchronized playback of the sign-language video with the media resource.
>>
>> Ditto above.
>
>
> Ditto bug 9452.
>
>
>>>> SPECNEW, TRACK: (CC-5) Support positioning in all parts of the screen - either inside the media viewport but also possibly in a determined space next to the media viewport. This is particularly important when multiple captions are on screen at the same time and relate to different speakers, or when in-picture text is avoided.
>>
>> Timed track rendering section does not seem to have provision for positioning timed text outside the media element or its controls.
>
>
> Doesn't look like we've got a bug for this yet, but I have raised it
> in discussion threads on WHATWG.
>
>
>>>> SPECNEW, TRACK: (CN-1) Provide a means to structure media resources so that users can navigate them by semantic content structure.
>>
>> We were not sure whether this is provided for, however, using a <track> element with kind=chapters seems to address this requirement.
>
>
> Yes, it does, but not hierarchically. We can, however, introduce some
> sort of level marker into the chapter tracks to make them hierarchical
> with time-overlapping cues. I've been thinking about proposing that.
>
>
>>>> SPECNEW, UX: (CC-25) Support edited and verbatim captions, if available.
>>
>> We thought the <track> element lacked a way to distinguish verbatim and edited captions in the same language, however, it seems like the label attribute may be sufficient to identify caption tracks as edited or verbatim.
>
>
> The @label is just a user-readable string. Do we need a
> machine-readable means to distinguish between edited and verbatim
> copies or just user readable? If the latter, then it will indeed be
> sufficient. (I'd be happy with that, btw.)
>
>
>>>> SPECNEW, UX: (DV-8) Allow the author to provide fade and pan controls to be accurately synchronized with the original soundtrack.
>>
>> HTML5 does have volume control, but not the ability to pan a soundtrack.
>
>
> This was identified as a "should" level requirement. My suggestion
> would be to not solve this within HTML5 LC, but keep this for a future
> version.
>
>
>>>> SPECNEW: (DAC-5) Non-synchronized alternatives (e.g., short text alternatives, long descriptions) can be rendered as replacements for the original rendered content (UAAG 2.0 3.1.3).
>>
>> HTML5 spec doesn't seem to have specific provision for a textual alternative (as opposed to captions or a transcript) for a video.
>
>
> I think a simple text or hyperlink to a longer text right next to the
> video or audio element will be sufficient to fulfill this need - it's
> what WCAG suggests, too. I don't actually think we need some new
> markup for this.
>
>
>> Also, looking closer at the spec, I believe the following items marked SPECCED are actually *not* yet provided for:
>>
>>>> SPECCED: (CA-1) Support clear audio as a separate, alternative audio track from other audio-based alternative media resources.
>>
>>
>> There is no provision for the <track> element to reference audio, nor is there an appropriate kind value for clear audio.
>
>
> No, but this could be solved with the same multitrack solution as
> earlier and bug 9452. If we are careful, we will introduce a means to
> directly change the volume on different audio tracks through
> JavaScript, so we can satisfy this.
>
>
>>>> SPECCED: (DV-4) Support recordings of real human speech as a track of the media resource, or as an external file.
>>
>>
>> The HTML5 draft has no provision for a video description track in the form of audio rather than text in the <track> element.
>
>
> Agreed. And again, this can be solved with the same multitrack support
> that bug 9452 is asking for.
>
>
>> And I believe the following 4 items may not actually have HTML5 spec impact:
>>
>>>> SPECNEW: (CN-6) Support direct access to any structural element, possibly through URIs. [Media fragment-like issue]
>>
>> Seems addressable through Media Fragments URI: <http://www.w3.org/TR/media-frags/>
>> Does HTML5 need any changes to adopt this?
>
>
> There is some recommendation necessary around the visual display of a
> media fragment in a video or audio element's @src, possibly the
> introduction of some new controls (e.g. loop fragment / loop whole, or
> rewind fragment / rewind whole). And then there is the whole question
> of addressing named fragments over timed fragments. The media
> fragments WG is looking into these issues and preparing a
> recommendation. This is all part of bug 10723
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=10723.
>
>
>>>> SPECNEW: (CN-3) Support both global navigation by the larger structural elements of a media work, and also the most localized atomic structures of that work, even though authors may not have marked-up all levels of navigational granularity.
>>
>> (I don't fully understand this requirement; sounds like maybe it should be in the UX category.)
>
>
> I'm not sure how navigation is possible without having marked-up
> navigation points. Other that that, it is clearly related to the above
> discussion of CN-1 and chapter cues.
>
>
>>>> SPECNEW: (CNS-1) All identified structures, including ancillary content as defined in "Content Navigation" above, must be accessible with the use of "next" and "previous," as refined by the granularity control. [May be handled with cue ranges]
>>
>> (I don't recall why this is a spec requirement rather than UX)
>
>
> It's more an accessibility API requirement than anything else, really.
>
>
>>>> SPECNEW: (DAC-2) The user has a global option to specify which types of alternative content by default and, in cases where the alternative content has different dimensions than the original content, how the layout/reflow of the document should be handled. (UAAG 2.0 3.1.2). [Probably minimal spec text required: Media queries would work nicely here; also UX issue (user sets media query to match)]
>>
>> Seems like this would be an issue for a spec to extend Media Queries; not clear if there is actual HTML5 impact.
>
>
> I almost think this is a case for user preferences, so UX. I'm not
> clear how media queries can help here.
>
>
> Cheers,
> Silvia.
>
Received on Wednesday, 17 November 2010 10:22:51 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 9 May 2012 00:17:16 GMT