[whatwg] Feature Request: Media Elements as Targets for Links

[Nils Dagsson Moskopp]

Excuse me if I am doing something wrong by submitting this by mail. I
am doing this for the first time, trying to fill in the template given
at <http://wiki.whatwg.org/wiki/Problem_Solving> as good as I could.

Use Case Description:

  Linking to specific fragments of media is possible via media fragment
  URIs [1]. However, it is not possible to apply a link to embedded
  media declaratively, for example to link to a specific point in time
  for a media element on a page.

  [1] <http://www.w3.org/TR/media-frags/>

- Current Limitations:

  Linking to media using media fragment URIs changes browsing context.

- Current Usage and Workarounds: 

  1. metavid (Videos of United States Congress) uses JavaScript, even
  though they have CMML transcripts and SRT.

  2. I have a podcast ”Warum nicht?“ generated by a software called
  redokast. Annotations need JavaScript: Click on the timestamps.
  <http://warumnicht.dieweltistgarnichtso.net/wn-15.html>
  <https://github.com/erlehmann/redokast>

- Benefits: Declarative markup would make referring to timed
  annotations easier. Referring to a specific point in time in a podcast
  on the same comments, for example, could be possible.

Proposed Solutions:

- My Solution:
  Give HTML media elements a name attribut. Make them valid targets for
  links with a target attribut.

  - Processing Model:
    Processing for media elements and the <a> element needs to change.

    <http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#attr-hyperlink-target>
    Change “The target attribute, if present, must be a valid browsing
    context name or keyword. It gives the name of the browsing context
    that will be used.” to “The target attribute, if present, must be a
    valid browsing context name or keyword or the name of a media
    element in the current browsing context. It gives the name of the
    browsing context or media element that will be used.”

    <http://www.whatwg.org/specs/web-apps/current-work/multipage/links.html#following-hyperlinks-0>
    Append after “If the user indicated a specific browsing context when
    following the hyperlink, or if the user agent is configured to
    follow hyperlinks by navigating a particular browsing context, then
    that must be the browsing context that is navigated.” the paragraph
    “If the user indicated a media element on the current page when
    following the hyperlink, then change the currentSrc attribute of
    the media element to the absolute URL given by the href attribute
    relative to the URL given by the currentSrc of the media element.”.

    (I am unsure about relative URIs. Would we need to change only the
    media fragment, and not re-run the initialization steps? What about
    the media formats given by <source> elements?)

  - Limitations
    (No idea.)

  - Implementation:
    (I am not a very clever guy. Someone would need to fill this in.)

  - Adoption:
    Users could easily link to parts of media resources on a page. The
    solution would be backwards compatible for existing UAs that are
    able to process media fragment URIs as long as absolute URIs are
    used. A JavaScript polyfill could be used while not all UAs support
    this feature. Consumers of web pages could easily see what a
    discussion about a media resource refers to.

-- 
Nils Dagsson Moskopp // erlehmann
<http://dieweltistgarnichtso.net>