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

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
<https://www.w3.org/AudioVideo/TT/tracker/issues/312> 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