Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs to permit text equivalent [TTML IMSC 1.0]

> However,  I would suggest that a ‘useful’ implementation might make the text
> available to another process or output device whilst also still decoding the images.

An application that wish to make text available to an output device
for use by a user can provide a separate Text Profile document. I do
not see a reason to introduce another means of delivering Timed Text
to the user.

Best,

-- Pierre

On Mon, Jun 16, 2014 at 8:33 AM, John Birch <John.Birch@screensystems.tv> wrote:
> I find it difficult to reconcile a design decision with a requirement…
> unless the original CFF(?) use case explicitly demanded a single
> document…(which is not clear from below) ;-)
>
>
>
> Regardless… I understand the desire to simplify the implicit requirements on
> a notional processor to only loading, decoding and rendering a single
> document and therefore I do generally support the forcedDisplayMode concept.
>
> For me this is the inclusion of two logical streams of (connected) content
> within a single document. Further, I do see this as setting a precedent. J
>
>
>
> With regards to adding text to the image profile, the proposal was only ever
> to consider the text as ‘alternative content’. However,  I would suggest
> that a ‘useful’ implementation might make the text available to another
> process or output device whilst also still decoding the images. (e.g.
> support text output to a braille display simultaneously to image rendering).
> I agree that the text should not be considered ‘normal TTML text’ as (under
> that specification) it would need to be displayed. Instead I suggest that
> the (equivalent) alternative text should be included as an attribute of the
> image… and thus could not have an independent existence from an image?
>
>
>
> Ideally I would like this to be a change to the current IMSC specification.
>
>
>
> Best regards,
>
> John
>
>
>
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>
>
> From: Michael Dolan [mailto:mdolan@newtbt.com]
> Sent: 12 June 2014 14:21
>
>
> To: 'Timed Text Working Group'
> Subject: RE: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs
> to permit text equivalent [TTML IMSC 1.0]
>
>
>
> In this case, it is less about whether we agree.  I am clarifying what the
> requirements are in the liaison. The design for a single document with
> forcedDisplayMode was developed by a collection of movie subtitle authoring
> companies, and a collection of device manufacturers.  Us debating
> alternative designs doesn’t change the requirements. If W3C designs
> something else that requires simultaneous multiple document decoding and
> merged presentations, that would fail to meet the requirements.
>
>
>
> Regarding adding text to the image profile:
>
>
>
> “…including text in image profile documents would be an acceptable solution
> to you.”
>
>
>
> Yes, as long as it is not required, and it is clearly signaled as
> “alternative” text in some manner.  It would be incorrect to include normal
> TTML text since that would have to be displayed and thus result in totally
> incorrect output.
>
>
>
> Regards,
>
>
>
>                 Mike
>
>
>
> From: Nigel Megitt [mailto:nigel.megitt@bbc.co.uk]
> Sent: Thursday, June 12, 2014 5:51 AM
> To: Michael Dolan; 'Timed Text Working Group'
> Subject: Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs
> to permit text equivalent [TTML IMSC 1.0]
>
>
>
> I understand the argument but I don't agree. This may come down to a 'system
> model' difference.
>
>
>
> They are both schemes in which multiple conceptually different content
> streams need to be made available, and the presentation of one or or more
> from the group is conditional on settings in the decoder, perhaps defined by
> the user.
>
>
>
> One could equally well generate a solution in which for 'forced display'
> content the content provider must provide two or more documents and ensure
> that the combined content of the group never exceeds the constraints of a
> single document, in complexity, overlapping regions, xml identifiers etc.
> Then the decoder must select the content from the appropriate documents and
> combine them client-side for display, which could be a defined
> 'pre-processing' task.
>
>
>
> If necessary we could even signal within documents 'this forms part of a
> group that may be combined for collective presentation' with a new 'group
> identifier'. Documents with different group identifiers would offer no
> guarantee that they may successfully be combined in this way.
>
>
>
> A solution like this would be extensible for live streams in which a group
> of temporally consecutive documents could be assigned the same group
> identifier and successfully combined for presentation – in that case they
> would probably be exclusive to each other temporally rather than spatially.
>
>
>
>
>
> By the way, Mike, I note that you've previously indicated that including
> text in image profile documents would be an acceptable solution to you.
>
>
>
>
>
> Kind regards,
>
>
>
> Nigel
>
>
>
>
>
> On 12/06/2014 12:34, "Michael Dolan" <mdolan@newtbt.com> wrote:
>
>
>
> They are not the same.
>
>
>
> forcedDisplayMode text is embedded in a single document since otherwise a
> decoder would have *simultaneously* decode two documents (one with forced
> content and one with non-forced content) and merge the output over the
> visual object.
>
>
>
> The desire to force the image profile to contain alternate text is solved
> with a text profile document.  Only one or the other document is decoded and
> presented since they each produce substantively the same visual results.
> And, even if it is desirable to decode both simultaneously, they would not
> have to be merged onto the visual object.
>
>
>
> Regards,
>
>
>
>                 Mike
>
>
>
> From: Nigel Megitt [mailto:nigel.megitt@bbc.co.uk]
> Sent: Thursday, June 12, 2014 4:10 AM
> To: 'Timed Text Working Group'
> Subject: Re: ISSUE-309 (Image profile fails WCAG 1.2): Image profile needs
> to permit text equivalent [TTML IMSC 1.0]
>
>
>
> I've updated this issue with the following note:
>
>
>
> The proposed resolution to this is not consistent with the approach taken
> for forcedDisplay (see also Issue-312). In the latter case it is stated that
> the two types of content must be provided in the same document. In this case
> it is stated that the content provider may optionally provide multiple
> documents.
>
> A simple resolution to this would be to permit text to be included in the
> image profile.
>
>
>
> Nigel
>
>
>
>
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Received on Tuesday, 17 June 2014 15:42:20 UTC