Getting Ahead of
the Curve
SCALABLE, ACCESSIBLE, ENTERPRISE-CLASS VIDEO ON THE WEB
WCAG Requirements

Perceivable

Operable

Understandable

Robust
Media is multi-modal (sight, sound, interactive)
Media Accessibility Checklist
(http://www.w3.org/WAI/PF/media-a11y-reqs/)
Accessible Media Requirements by Type of Disability

Blindness

Low vision

Atypical color perception (color blind)

Deafness

Hard of hearing

Deaf-blind

Physical impairment

Cognitive and neurological disabilities
Production and Delivery
Requirements
Alternative Content Technologies
System Requirements

Captioning

Access to interactive controls / menus

Described video


Text video description
Discovery and activation/deactivation of
available alternative content by the user

Transcripts

Granularity level control for structural
navigation

Extended video descriptions

Time-scale modification

Enhanced captions/subtitles


Sign translation
Requirements on making properties
available to the accessibility interface

Clean audio

Requirements on the use of the viewport

Content navigation by content
structure

Requirements on secondary screens and
other devices
Alternative Content Technologies
Alternative Content Technologies:
Captions
“Captioning is the process of converting the audio
content of a television broadcast, webcast, film,
video, live event, or other productions into text
and displaying the text on a screen or monitor.
Captions not only display words as the textual
equivalent of spoken dialogue or narration, but
they also include speaker identification, sound
effects, and music description.”
(http://www.dcmp.org/captioningkey/)
Alternative Content Technologies:
Captions
It is important that the captions are:
 synchronized and appear at approximately the same
time as the audio is delivered
 equivalent and equal in content to that of the audio,
including speaker identification and sound effects
 accessible and readily available to those who need or
want them
 Captions can be either Open or Closed
While similar in construction, Captions and Sub-Titles are
not the same thing.
Alternative Content Technologies:
Captions

WCAG Success Criteria

S.C. 1.2.2 Captions (Prerecorded) (A)

S.C. 1.2.4 Captions (Live) (AA)

S.C. 3.1.2 Language of Parts (AA)

S.C. 1.4.8 Visual Presentation (AAA)
 UAAG Success Criteria

S.C. 1.1.1 Render Alternative Content (A)

S.C. 1.1.3 Replace Non-Text Content (A)

S.C. 3.1.3 Retrieval Progress (A)

S.C. 2.11.8 Video Contrast and Brightness (AAA)
Alternative Content Technologies:
Captions (Timing and Display)
Formats for captions, subtitles or foreign-language subtitles must:

Render text in a time-synchronized manner, using the media
resource as the time-base master.

Be available in a text encoding. (e.g. UTF-8)

Support positioning in all parts of the screen - either inside the media
viewport but also possibly in a determined space next to the media
viewport.

Permit a range of font faces and sizes. Permit rendered text and
backgrounds in a range of colors, supporting a full range of
opacities.

Additional requirements supporting internationalization and visual
display properties
Alternative Content Technologies:
Captions

Formats

WebVTT (dev.w3.org/html5/webvtt/)

TTML/SMPTE (http://www.w3.org/TR/ttaf1-dfxp /
https://www.smpte.org/sites/default/files/st2052-1-2010.pdf)

Other formats exist:


Scenarist Closed Caption (.scc)
SAMI/SMIL (.smi)

RealText (.rt)

SubRip/SubViewer (.srt/.sbv)
Alternative Content Technologies:
Descriptions
Described video contains descriptive narration of key visual
elements designed to make visual media accessible to
people who are blind or visually impaired.
The descriptions include actions, costumes, gestures, scene
changes or any other important visual information that
someone who cannot see the screen might ordinarily miss.
Alternative Content Technologies:
Descriptions

WCAG Success Criteria

S.C. 2.4.6 Headings and Labels (AA)

S.C. 1.2.5 Audio Description (Prerecorded) (AA)

S.C. 1.4.7 Low or No Background Audio(AAA)

UAAG Success Criteria

S.C. 1.1.1 Render Alternative Content (A)

S.C. 1.1.3 Replace Non-Text Content (A)

S.C. 3.1.3 Retrieval Progress (A)

S.C. 2.11.8 Video Contrast and Brightness (AAA)
Alternative Content Technologies:
Transcripts
A full transcript supports different user needs and is
not a replacement for captioning. A transcript can
either be presented simultaneously with the media
material, which can assist slower readers or those
who need more time to reference context, but it
should also be made available independently of
the media.
Alternative Content Technologies:
Transcripts

WCAG Success Criteria

S.C. 1.2.1 Audio-only and Video-only (Prerecorded) (AA)

S.C. 2.4.6 Headings and Labels (AA)

S.C. 3.1.1 Language of Page (A)

UAAG Success Criteria

S.C. 1.1.1 Render Alternative Content (A)

S.C. 1.1.3 Replace Non-Text Content (A)

S.C. 3.1.3 Retrieval Progress (A)

S.C. 2.11.8 Video Contrast and Brightness (AAA)
Alternative Content Technologies:
Extended and Enhanced
Extended descriptions work by pausing the video and program audio
at key moments, playing a longer description than would normally be
permitted, and then resuming playback when the description is
finished playing. This will naturally extend the timeline of the entire
presentation
Enhanced captions are timed text cues that have been enriched with
further information - examples are glossary definitions for acronyms and
other intialisms, foreign terms (for example, Latin), jargon or descriptions
for other difficult language. They may be age-graded, so that multiple
caption tracks are supplied, or the glossary function may be added
dynamically through machine lookup.
Alternative Content Technologies:
“Above and Beyond”

Clean audio

Content navigation by content structure

Sign translation
Summary of Authoring
Requirements
To be fully conformant to WCAG 2.0 (AA),
you will require the following:
 Captions
 Video
Descriptions
 Transcripts
System Requirements
What is an HTML5 Media Player?
<video width=“800" height=“600" controls>
<source src=“MyVideo.mp4" type="video/mp4" />
<source src=“MyVideo.webm" type="video/webm" />
<track src=“MyCaptions.vtt" kind=“Captions" srclang="en" label="English" />
<!-- fallback for legacy browsers -->
</video>

The browser is the video player – the video player is the browser!

HTML5 anticipates author scripted & customized controls

Many HTML5 video players today use Flash players as a fallback
System Requirements
Access to interactive controls / menus
Interactive controls and menus must be
available to all users for all means in which
the controls are exposed - no matter
whether they are exposed by the user
agent, or are scripted.
Controls must be device independent, so
that control may be achieved by keyboard,
pointing device, speech, etc.
System Requirements
Discovery and activation/deactivation of
available alternative content by the user
Alternative content must be both
discoverable by the user, and accessible in
device agnostic ways.
The development of APIs and user-agent
controls should adhere to UAAG guidance.
System Requirements
Discovery & activation/deactivation of available alternative
content

In cases where the alternative content has different dimensions than
the original content, the user has the option to specify how the
layout/reflow of the document should be handled.

The user can browse the alternatives and switch between them.

Synchronized alternatives for time-based media can be rendered at
the same time as their associated audio tracks and visual tracks

Non-synchronized alternatives can be rendered as replacements for
the original rendered content.

Provide the user with the option to load time-based media content
such that the first frame is displayed (if video), but the content is not
played until explicit user request.
System Requirements
Granularity level control for structural
navigation
A real-time control mechanism must be
provided for adjusting the granularity of the
specific structural navigation point next and
previous.
Users must be able to set the range/scope
of next and previous in real time.
System Requirements
Time-scale modification
While all devices may not support the
capability, a standard control API must
support the ability to speed up or slow down
content presentation without altering audio
pitch.
(This feature has been present on many
devices, especially audiobook players, for
years. )
System Requirements
Making properties available to the
accessibility interface (AAPI)
For user agents supporting accessibility APIs
implemented for a platform, any media
controls need to be connected to that API.
System Requirements
Requirements on the use of the viewport
 The
video viewport traditionally provides a
bounding box for many of the visually
represented alternative-content
technologies, although some alternative
content does not rely on a viewport.
Remember when designing player ‘skins’ is
that the lower-third of the video may be
needed for caption text.
Summary of System Requirements

Controls must be accessible, via platform AAPIs

Alternate content must be discoverable, and
able to be modified by the end user

Content navigation and content display should
allow for personalization
Infrastructure & Production
Requirements
Let’s Do Video!

Producing Accessible videos

Streaming your Accessible videos

Managing your Accessible video library
Caption & Description Resources
Outsourcing


Captions

3PlayMedia (http://3playmedia.com)

Automatic Sync (http://www.automaticsync.com/caption)

CaptionMax (http://captionmax.com/)

National Captioning Institute (http://www.ncicap.org)
Described Video

Bridge Multimedia
(http://www.bridgemultimedia.com/audiodescription/ )

Dicapta (http://www.dicapta.com/)

CaptionMax (http://captionmax.com/)

More resources (http://www.acb.org/adp/services.html)
Producing Accessible videos
Video Captioning Software
MAGpie (http://ncam.wgbh.org/invent_build/web_multimedia/toolsguidelines/magpie)

Media Access Generator is the original free caption and audiodescription authoring tool for making multimedia accessible to
persons with sensory disabilities.
Subtitle Workshop
(http://www.urusoft.net/products.php?amp;cat=sw&lang=1)

The most complete, efficient and convenient freeware subtitle
editing tool. It supports all the subtitle formats you need and has all
the features you would want from a subtitle editing program.
Caption Generator (http://www.vttcaptions.com/)

Caption Generator lets you create, synchronize and edit .vtt
captions.
Producing Accessible videos
Video Description Software
YouDescribe (http://www.youdescribe.org/)

Free web-based tool that allows anyone to record descriptions of
YouTube videos and/or play previously described YouTube videos.
CapScribe Open (http://www.inclusivemedia.ca/captionme/)

Free Mac-based video editor for captioning and description
MAGpie (http://ncam.wgbh.org/invent_build/web_multimedia/toolsguidelines/magpie)

Media Access Generator is the original free caption and audiodescription authoring tool for making multimedia accessible to
persons with sensory disabilities.
Livedescribe (http://www.livedescribe.com/)

Video description software designed, prototyped and developed at
The Center for Learning Technology.
Producing Accessible videos
HTML5
Out of band
<video controls>
<source src=movie.webm>
<source src=movie.mp4>
<track src=english.vtt kind=captions srclang=en>
<track src=french.vtt kind=captions srclang=fr>
<p>Fallback content here with links to download video files</p>
</video>
Producing Accessible videos
HTML5
In Band
Producing Accessible videos
HTML5
In Band - Tools
Handbrake (Captions)
CyberLink Power Director
Sony Movie Studio Pro
iMovie
Adobe Premiere Pro
Streaming your Accessible videos
Adaptive Streaming
Media Server
Adaptive Streaming - HTTP
(http://en.wikipedia.org/wiki/Adaptive_
bitrate_streaming)

MPEG-DASH

Apple HTTP Adaptive Streaming

Microsoft Smooth Streaming

Adobe Dynamic Streaming for Flash
http://www.streamingmedia.com/Articles/Editorial/Featured-Articles/How-to-Produce-forAdaptive-Streaming-81020.aspx
Streaming your Accessible videos
Real Time Streaming Protocol (RTMP)
Media Server
Helix DNA Server / Helix Universal Server :

RealNetworks' streaming server. Comes in both open-source and
proprietary flavors.

RealNetworks commercial streaming server for RTSP, RTMP, iOS,
Silverlight and HTTP streaming media clients
QuickTime Streaming Server:

Apple's closed-source streaming server that ships with Mac OS X Server.
Windows Media Services:

Microsoft streaming server previously included with Windows Server that
uses RTSP modified with Windows Media extensions
Streaming your Accessible videos
Real Time Streaming Protocol (RTMP)
Media Server
Wowza Media Server:

Multi-format streaming server for RTSP/RTP,
RTMP, MPEG-TS, ICY, HTTP (HTTP Live
Streaming, HTTP Dynamic Streaming,
Smooth Streaming)
Managing your Accessible video
library
Not all Media CMS solutions are equal.
An accessible Media CMS supports the following:

Integrated upload and tracking of Captions, Video Descriptions,
Transcripts and of course Videos

Integrated Adaptive Streaming

Supports/converts multiple codecs (.mp4, WebM)
Thanks!
Questions?

John Foliot

john.foliot@Deque.com

@johnfoliot