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Media--Technical Implications of Our User Requirements

From: Janina Sajka <janina@rednote.net>
Date: Tue, 13 Jul 2010 23:51:55 -0400
To: HTML Accessibility Task Force <public-html-a11y@w3.org>
Message-ID: <20100714035155.GF2455@sonata.rednote.net>
Colleagues:

The following is a first-pass, high level description of the content types and API mechanisms our user requirements expose.  It is meant to be a list of
things we need to support in our eventual change proposal. it is intentionally agnostic
regarding any particular technology.

ASSUMPTION: A "default" media content type (video or audio) is presumed in all
cases.



          + 2.1 Audio Description

One or more audio tracks

Multiple audio tracks may be present to support audio description in
various languages, e.g. EN, FR, DE, JP, etc, or to support multiple
levels of description.

          + 2.2 Texted Audio Description

Text content with the ability to contain semantic and style
instructions.

Multiple documents may be present to support texted audio description in
various languages, e.g. EN, FR, DE, JP, etc, or to support multiple
levels of description.

          + 2.3 Extended audio description

Same as "2.1 Audio Description

          + 2.4 Clear audio

An audio "track."

          + 2.5 Content Navigation by Content Structure

A structured data file.

NOTE: Data in this file is used to synchronize all media representations
available for a given content publication, i.e. whatever audio, video, and
text document--default and alternative--versions may be provided.

          + 2.6 Captioning

Text content with the ability to contain hyperlinks, and semantic and style
instructions.

QUESTION: Are subtitles separate documents? Or are they combined with captions
in a single document, in which case multiple documents may be present to
support subtitles and captions in various languages, e.g. EN, FR, DE, JP, etc.
 
          + 2.7 Extended Captioning

Same as 2.6 Captioning

          + 2.8 Sign Translation

A video "track."

Multiple video tracks may be present to support sign translation in
various signing languages, e.g. ASL, BSL, NZSL, etc. Note that the
example signing languages given here are all translations of English.

          + 2.9 Transcripts

Text content with the ability to contain semantic and style
instructions.
 
          + 3.1 Access to interactive controls / menus

An API providing access to:

Stop/Start
Pause
Fast Forward and Rewind (time based)
time-scale modification control
volume (for each available audio track)
pan location (for each available audio track)
pitch-shift control
audio filters
Next and Previous (structural navigation)
Granularity Adjustment Control (Structural Navigation)
Viewport content selection, on screen location and sizing control
Font selection, foreground/background color, bold, etc configuration/selection
Extended descriptions and extended captions configuration/control
Ancillary content configuration/control

          + 3.5 Discovery and activation/deactivation of available alternative content by the user

A discovery mechanism and presentation of available media options for user selection.

          + 3.8 Requirements on the parallel use of alternate content on potentially multiple devices in parallel

A discovery mechanism of available OS provided output device options for user selection.

-- 

Janina Sajka,	Phone:	+1.443.300.2200
		sip:janina@asterisk.rednote.net

Chair, Open Accessibility	janina@a11y.org	
Linux Foundation		http://a11y.org

Chair, Protocols & Formats
Web Accessibility Initiative	http://www.w3.org/wai/pf
World Wide Web Consortium (W3C)
Received on Wednesday, 14 July 2010 03:52:26 GMT

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