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Re: Call for Consensus (CfC): APA Comment on Media Hints

From: Becky Gibson <gibson.becky@gmail.com>
Date: Wed, 7 Jul 2021 13:01:47 -0400
Cc: "Janina Sajka (janina@rednote.net)" <janina@rednote.net>, Accessible Platform Architectures Administration <public-apa-admin@w3.org>
Message-Id: <951EC769-20E3-4AC7-AE05-1A81A6929C86@gmail.com>

> On Jul 7, 2021, at 12:12 PM, Amy @ Digilou <hello@digilou.tech> wrote:
> +1
> ´╗┐On 7/6/21, 11:12 AM, "Janina Sajka (janina@rednote.net)" <janina@rednote.net> wrote:
>    Colleagues:
>    This is a Call for Consensus (CfC) to the Accessible Platform
>    Architectures (APA) Working Group testing whether we have group
>    consensus on comments and suggested edits on the MediaStreamTrack
>    Content Hints draft specification, at
>    https://www.w3.org/TR/mst-content-hint/.
>    <beginning of suggested comment>
>    *TITLE *
>    APA comments on the MediaStreamTrack Content Hints draft specification, at
>    https://www.w3.org/TR/mst-content-hint/.
>    *OVERVIEW *
>    *Content hint attributes defined in this specification will benefit
>    consumers who rely on assistive technology (AT) and personalization. *The
>    specification notes its focus on end-users' experience: "Adding a media
>    -content hint provides a way for a web application to help track consumers
>    make more informed decision[s]...." Content authors can author contentHint
>    <https://t.sidekickopen90.com/s3t/c/5/f18dQhb0S7kF8cFFTBW4T_qld2zGCwVN8Jbw_8QsRtKVn1vXj1p1kknW16gGBN41Jd6G101?te=W3R5hFj4cm2zwW4mKLS-4mbkbhW49Ldrl308ybGW4fdgvc41YylgW4fdgXQ41YszVW3H90C_3_SMDQW3zh2Fq3K1LvHW49HR8w1Gy-qYW4fGC1K3R0JW00&si=8000000004174048&pi=58151f60-5af3-4f61-ebc9-364d322a7e5a>
>     with the experience of AT users in mind, or UAs acting on behalf of
>    users.  This specification's introduction would be a good place to
>    clarify this as a further benefit of content hints. Content authors may
>    author content hints with AT in mind. In addition, we encourage User Agents
>    to make this hint available to downstream consumers via API,
>    *The specification make no mention of hints regarding support files *(captions,
>    audio descriptions) that often accompany media content, either linked to it
>    in HTML externally (using the <track> element) or furnished 'in-band',
>    e.g., contained within the .MP4 wrapper (HasCaptions: T/F,
>    HasAudioDescription: T/F). If either return True, THEN they need to be
>    exposed in the UI: essentially as 'active' buttons in the Controls. Such
>    support files can be critical to the accessibility of a media track, as for
>    example when an American Sign Language video is supplied seperately, but
>    linked. Did the WG consider whether hints could also usefully convey
>    whether the media content has such supporting files?
>    Regarding Section 4: *The specification's hints could address more directly
>    some common **audio and video formats that are often encountered with
>    content that has been made accessible. *For clarity, such formats could
>    propose hints such as these (these are examples for clarity only, we leave
>    you to define such hints):
>    *For Audio, an additional hint to indicate the presence of
>    audio-description *(or some similar label as you find appropriate).
>    Audio-description is audio that resembles speech-recognition, but does not
>    contain data for the purpose of speech recognition by a machine.
>    Audio-description is audio that resembles "speech" but it will likely not
>    be appropriate to apply noise suppression or boost intelligibility of the
>    incoming signal.
>    In the language of the specification (4.1) , "A track with content
>    hint "audio-description"
>    should be treated as if it contains audio data, without background noise,
>    describing in words the activity in the video."
>    *For Video, an additional hint to indicate the presence of transcription
>    embedded in the video*, e.g., motion-with-transcription (or some similar
>    label as you find appropriate). motion-with-transcription would refer to a
>    motion video that has, embedded, transcription data, either a
>    picture-in-picture showing a sign language interpreter, or text captions
>    embedded in the video.
>    In the language of the specification (4.2): A content hint of
>    motion-with-transcription should be treated such that one region of the
>    video frame has details that are extra important, and in that region that
>    significant sharp edges and areas of consistent color can occur frequently
>    (the area with sign language interpretation, or the area with onscreen
>    captioned text). This screen region would optimize for detail in the
>    resulting individual frames rather than smooth playback. Artefacts from
>    quantization or downscaling should be avoided.
>    *Regarding section 5, the degradation preference does not address regions.*
>    Picture regions may be very significant for accessibility. Consider a video
>    with sign language interpretation embedded (e.g., in the upper right
>    corner), or a video with captions "burned-in" or embedded (e.g., in the
>    bottom of the picture area). (While APA does not advocate for such embedded
>    captions, they are common particularly on social media where the default
>    user behavior is audio "off." These regions would benefit from different
>    encoding decisions than the rest of the frame.  Regions may be encoded and
>    decoded quite differently: for example in AVC, "it is also possible to
>    create truly lossless-coded regions within lossy-coded pictures." *We would
>    find it useful and supportive of accessible content to make this
>    information available as an RTCDegradationPreference.*
>    Lastly, how are these hints communicated? We note that MP4 files can
>    contain metadata as defined by the format standard, and in addition, can
>    contain Extensible Metadata Platform (XMP) metadata. (source::
>    https://en.wikipedia.org/wiki/MPEG-4_Part_14).
>    Correct these two typos:
>       - Abstract: change "make more informed decision" to either "make a more
>       informed decision" or "make more informed decisions"
>       - Section 2. change "they appear" to "it appears"
>    Add to the introduction that content hint attributes defined in this
>    specification will benefit consumers who rely on assistive technology (AT)
>    and personalization.
>    The WG to ensure that the specification covers use cases with support
>    files, and that hints can be provided for those files.
>    In section 4, ensure that hints support the use-cases mentioned above.
>    In section 5.2 ensure that the specification supports regions particularly
>    when such regions are important for accessibility.
>       <end suggested comment>
>    ***Action to Take***
>    This CfC is now open for objection, comment, as well as statements of
>    support via email. Silence will be interpreted as support, though
>    messages of support are certainly welcome.
>    If you object to this proposed action, or have comments concerning this
>    proposal, please respond by replying on list to this message no later
>    than 23:59 (Midnight) Boston Time, Wednesday 14 July.
>    NOTE: This Call for Consensus is being conducted in accordance with the
>    APA Decision Policy published at:
>    http://www.w3.org/WAI/APA/decision-policy
>    We thank Lionel Wolberger for reviewing this specification on our behalf
>    and for helping lead our teleconference discussions on this
>    specification.
>    Janina and Becky
>    --
>    Janina Sajka
>    Linux Foundation Fellow
>    Executive Chair, Accessibility Workgroup:	http://a11y.org
>    The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
>    Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa

Becky Gibson

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Co-Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa

Received on Wednesday, 7 July 2021 17:04:43 UTC

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