[ttml2] deprecate use of pixel units unless tts:extent on root element is in pixels

• From: Glenn Adams via GitHub <sysbot+gh@w3.org>
• Date: Wed, 24 May 2017 21:38:48 +0000
• To: public-tt@w3.org
• Message-ID: <issues.opened-231179173-1495661927-sysbot+gh@w3.org>

skynavga has just created a new issue for https://github.com/w3c/ttml2:

== deprecate use of pixel units unless tts:extent on root element is in pixels ==
At present, TTML1 allows a document to use pixel units when expressing ``<length>`` terms, even when the author has not defined the resolution of the document coordinate space by specifying a pixel based ``tts:extent`` on the ``<tt>`` element. I propose that this behavior be deprecated in TTML2, as it leads to potential interoperability problems when presenting TTML content. Note that a number of profiles, including IMSC1 and EBU-TT, require that a pixel based ``tts:extent`` be present when pixel units are used in content.

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/330 using your GitHub account

Received on Wednesday, 24 May 2017 21:38:55 UTC