[Media] MAUR Clarification from BBC

Forwarding Nigel's response to our edits ...

Nigel Megitt writes:
> Dear PFWG,
> 
> Thank you for processing our review comments so promptly. I would like to
> highlight one edit that appears to be a small misunderstanding of our
> comment, albeit with a large impact:
> 
> For VP-5 in section 4.7, our proposal was:
> 
> "If there are several types of overlapping overlays, they should be
> positioned as far as possible to avoid obscuring editorially important
> parts of the underlying video such as burned in text, mouths etc. Users
> typically expect controls to appear at the bottom of the viewport.
> Controls should not be prevented from becoming usable due to
> repositioning."
> 
> The edited result is:
> 
> 
> "If there are several types of overlapping overlays, they should be
> positioned as far as possible from editorially important content. In
> particular, they should avoid obscuring video components such as mouths,
> "burned in text" (embedded captions or other annotations in the main video
> stream), etc. Users typically expect controls to appear at the bottom of
> the viewport. Controls should not be prevented from becoming usable due to
> repositioning."
> 
> 
> 
> Looking at the first sentence: it was not our intent that the distance
> between the rendered position of overlays and the editorially important
> content should be maximised. Rather, we meant that, in a constrained
> environment in which it is not in general possible in all cases to avoid
> obscuring all editorially important parts of the underlying video, all
> possible efforts should be made to avoid it. In other words, maximise the
> avoidance of obscuring editorially important parts of the video, not
> maximise the distance.
> 
> Maximising the distance does have a negative effect in that it means that
> the viewer's eyes may need to track a longer distance. Some experiments (I
> can't provide a reference) have demonstrated that putting captions as
> close as possible to the mouths of the relevant speakers hugely enhances
> the experience and helps viewers to feel connected to the editorial
> content.
> 
> However advising that the distance should be minimised seems too strong a
> statement at the current time.
> 
> Kind regards,
> 
> Nigel
> 
> 
> 
> On 04/12/2014 14:59, "Nigel Megitt" <nigel.megitt@bbc.co.uk> wrote:
> 
> >Dear PFWG,
> >
> >Please see the following review comments from the BBC on the MAUR document
> >[1].
> >
> >[1] http://w3c.github.io/pfwg/media-accessibility-reqs/
> >
> >==========
> >General comment: the writers may wish to consider this user experience
> >good practices document drafted by BBC:
> >http://www.bbc.co.uk/guidelines/futuremedia/accessibility/subtitling_guide
> >s
> >/online_sub_editorial_guidelines_vs1_1.pdf
> >==========
> >General comment: The BBC would like to commend the activity of creating
> >this very useful document.
> >==========
> >
> >
> >
> >
> >
> >Section 3.6 Captioning
> >
> >==========
> >[CC-10] Render a background in a range of colors, supporting a full range
> >of opacity levels.
> >
> >Comment: It enhances readability if the bounding box of the background
> >area is not tightly aligned with the text edges, i.e. that some background
> >space is visible especially at each end of a line area, for example the
> >equivalent of the width of half a space in the selected font.
> >
> >Proposal: Add a new requirement:-
> >
> >"Enable the bounding box of the background area to be extended by a
> >present distance relative to the foreground text contained within that
> >background area."
> >
> >==========
> >[CC-11] Render text in a range of colors.
> >NOTE
> >The user should have final control over rendering styles like color and
> >fonts; e.g., through user preferences.
> >
> >Comment: A default palette of colours suitable for colour blind users
> >should be available to distinguish editorial concepts, such as speakers.
> >There are likely to be conflicting requirements between different users
> >with differing cognitive conditions to maximise the accessibility of
> >content, so full colour customisation should be available. For example
> >users with cognitive conditions such as dyslexia (itself an umbrella label
> >for a variety of conditions), ADHD and Asperger's may find that viewing
> >content that is given a particular colour cast, akin to viewing through
> >blue spectacles, say, helps them to read presented text. Whilst further
> >research is needed in this area, we should recommend that full colour
> >customisation is available.
> >
> >
> >==========
> >[CC-12] Enable rendering of text with a thicker outline or a drop shadow
> >to allow for better contrast with the background.
> >
> >Comment: It's correct that this should be enabled however it should not be
> >presented as a suitable general alternative to displaying text on a
> >non-transparent background, from a legibility perspective. For example,
> >white text with drop shadows on a transparent background is not readable
> >over a white video, such as footage of snow.
> >
> >
> >Comment: The use of drop shadows increases the sense of 'busyness' that
> >can have negative impacts for viewers with some cognitive conditions.
> >In general it is preferable not to use drop shadows for the purpose of
> >improving text legibility.
> >
> >==========
> >[CC-13] Where a background is used, it is preferable to keep the caption
> >background visible even in times where no text is displayed, such that it
> >minimizes distraction. However, where captions are infrequent the
> >background should be allowed to disappear to enable the user to see as
> >much of the underlying video as possible.
> >
> >
> >Comment: this is a cultural/editorial feature that is not accepted
> >globally and is likely to result in unnecessarily obscured video.
> >
> >Proposal 1: Remove this requirement.
> >
> >Proposal 2 (in case Proposal 1 is rejected): Change 'it is preferable' to
> >'it should be possible'.
> >
> >==========
> >[CC-14] Allow the use of mixed display styles‹ e.g., mixing paint-on
> >captions with pop-on captions‹ within a single caption cue or in the
> >caption stream as a whole. Pop-on captions are usually one or two lines of
> >captions that appear on screen and remain visible for one to several
> >seconds before they disappear. Paint-on captions are individual characters
> >that are "painted on" from left to right, not popped onto the screen all
> >at once, and usually are verbatim. Another often-used caption style in
> >live captioning is roll-up - here, cue text follows double chevrons
> >("greater than" symbols), and are used to indicate different speaker
> >identifications. Each sentence "rolls up" to about three lines. The top
> >line of the three disappears as a new bottom line is added, allowing the
> >continuous rolling up of new lines of captions.
> >
> >
> >Proposal: Add a Note to this section:
> >
> >"The comprehension and appreciation of captions and subtitles depends on
> >how well matched they are to the related video content, editorially. In
> >particular the pacing of the content should be reflected in the caption
> >text; for example a fast paced drama or is likely to benefit from
> >relatively short captions that change more often in comparison to a slow
> >paced one. In extremis very fast changing short subtitles do cause
> >readability problems because they can prevent viewers from having enough
> >attention to consider the video; such extremes should be avoided."
> >
> >Proposal: Add a Note to this section:
> >"When displaying captions in the paint-on style care should be taken to
> >ensure that the final words that are displayed are visible for enough time
> >that they can be read."
> >
> >==========
> >
> >[CC-15] Support positioning such that the lowest line of captions appears
> >at least 1/12 of the total screen height above the bottom of the screen,
> >when rendered as text in a right-to-left or left-to-right language.
> >
> >
> >Comment: this rule is not global and, in the measurement of 1/12 appears
> >to be arbitrary. We agree that a gap does help readability, but propose
> >that the specific distance requirement should be removed.
> >
> >==========
> >Comment: The legibility of rendered text depends on the size of the text
> >as perceived by the viewer, which is in turn dependent on the display size
> >and the distance between display and viewer. I propose adding:
> >
> >Proposal: Add a new requirement:-
> >"Enable responsive choice of text size based on display size and expected
> >distance between display and viewer."
> >
> >==========
> >
> >Comment: To maximise readability of text it is often beneficial to use a
> >font that is optimised for the technology used within the platform and
> >display. For example the approach to handling multiple screen sizes in
> >Android means that unmodified general purpose fonts such as Helvetica do
> >not always render well - in that case the Roboto font may be preferable.
> >
> >Proposal: Add a new requirement:-
> >"Enable fonts optimised for readability on the display in use to be
> >preferred where they are available."
> >==========
> >
> >
> >
> >
> >Section 4.7 Requirements on the use of the viewport
> >
> >
> >==========
> >
> >[VP-5] Captions and subtitles traditionally occupy the lower third of the
> >video, where controls are also usually rendered. The user agent must avoid
> >overlapping of overlay content and controls on media resources. This must
> >also happen if, for example, the controls are only visible on demand.
> >
> >NOTE
> >
> >If there are several types of overlapping overlays, the controls should
> >stay on the bottom edge of the viewport and the others should be moved
> >above this area, all stacked above each other.
> >
> >
> >Comment: It is also important to avoid captions and subtitles overlapping
> >editorially important content areas such as mouths, burned in text etc.
> >
> >
> >Comment: We strongly disagree with the stacking approach described in the
> >Note. In many cases the best location for the captions/subtitles in this
> >scenario is towards the top of the viewport, where it is less likely to
> >obscure mouths etc.
> >
> >Proposal: Remove or edit the note to reflect these comments, for example
> >resulting in:
> >
> >"If there are several types of overlapping overlays, they should be
> >positioned as far as possible to avoid obscuring editorially important
> >parts of the underlying video such as burned in text, mouths etc. Users
> >typically expect controls to appear at the bottom of the viewport.
> >Controls should not be prevented from becoming usable due to
> >repositioning."
> >
> >==========
> >
> >
> >Kind regards,
> >
> >Nigel Megitt
> >
> >-- 
> >Nigel Megitt
> >Lead Technologist, BBC Technology, Distribution & Archives
> >BC4 A3 Broadcast Centre, Media Village, 201 Wood Lane, London W12 7TP
> >
> >
> >
> 

-- 

Janina Sajka, Phone: +1.443.300.2200
   sip:janina@asterisk.rednote.net
  Email: janina@rednote.net

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

The World Wide Web Consortium (W3C), Web Accessibility Initiative (WAI)
Chair, Protocols & Formats http://www.w3.org/wai/pf
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Received on Monday, 15 December 2014 02:11:40 UTC