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

From: Janina Sajka (janina@rednote.net) <(janina@rednote.net)>
Date: Tue, 13 Jul 2021 09:19:50 -0400
To: public-apa-admin@w3.org
Message-ID: <YO2S9jskj5iP9uNK@rednote.net>
+1

Janina

Janina Sajka writes:
> 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).
> 
> *REQUESTS*
> 
> 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
> 

-- 

Janina Sajka
https://linkedin.com/in/jsajka

Linux Foundation Fellow
Executive Chair, Accessibility Workgroup:	http://a11y.org

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Co-Chair, Accessible Platform Architectures	http://www.w3.org/wai/apa
Received on Tuesday, 13 July 2021 13:20:34 UTC

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