ChangeProposal/Issue194

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Change Proposal

Introduce a new attribute: @transcript

Summary

This Change Proposal seeks to introduce a new attribute to the <video> element, @transcript, which would takes as a value either an URI to a separate page, or a fragment identifier to a location elsewhere on the same page. Creating a specific attribute removes any ambiguity of the linking mechanism – making it a DOM identifiable node. As an attribute of the video element, it provides a mechanism for linking to the transcript without forcing a visual encumbrance on the design aesthetic.


Rationale

Raised from bug https://www.w3.org/Bugs/Public/show_bug.cgi?id=12964

Full transcripts give people with disabilities a way to access audio/video content. Transcripts are often provided as a separate resource, because they're often too lengthy to be included on the same page as the audio/video they're associated with.

A mechanism that creates an association between an audio/video element and a full (off page) transcript would have many benefits. These include discoverability for assistive technology users, programmatic identification for search engine indexing, design aesthetic, and content syndication or embedding..

Details

A high-level prose description of the changes to be made follows:

Linking to an external transcript:

<video controls transcript="_path_to_transcript_(relative or absolute)_">
  <source="_path_to_WebM_file_" type="video/webm">
  <source="_path_to_mp4_file_" type="video/mp4">
  <track="_path_to_TTML_file_" kind="captions">
    (etc.)
</video>

Linking to a transcript on the same page:

<video controls transcript="#transcript">
  <source="_path_to_WebM_file_" type="video/webm">
  <source="_path_to_mp4_file_" type="video/mp4">
  <track="_path_to_TTML_file_" kind="captions">
    (etc.)
</video>

<div id="transcript"> -- Insert Transcript here -- </div>

Note: While authors can insert the transcript into the parent page of the video, and then use any number of hiding techniques to place it off screen, author Best Practices should discourage this, for the following reasons:

  • transcripts benefit more than just non-sighted users - in fact users with cognitive disabilities are actually one of the main beneficiaries of full transcripts.
  • full transcripts can often contain a large amount of text, which will add some weight [sic] to the page, slowing downloads and using un-needed bandwidth when a transcript is not required.

Impact

Positive Effects

  • A dedicated, programmatic linking mechanism that ensures access to a full transcript of the video is maintained
  • Does not force content authors to place a visible link to the transcript on-screen, respecting design considerations often present

Negative Effects

  • Requires that browsers and other user-agents provide a mechanism for users to discover the link to the transcript, and the ability to access the transcript on demand.
  • Like @longdesc, some authors may misunderstand how to use the @transcript mechanism - this can be mitigated with good authoring instructions and examples.

Conformance Classes Changes

  • Unknown

Risks

  • Unknown

References