Accessible Video in the Enterprise

A (Very) Brief History1999 – 2005: Competing, incompatible delivery platforms

2005: Launch of YouTube & Flash-based player brings some commonality to delivery platform

A (Very) Brief History2012/2014: W3C’s Standardization of HTML5 Apple drops Flash support / advances in Major Browsers

Consideration #1 - Streaming

Users Start Giving Up on Streaming Video If It Takes Two Seconds to Load: (http://gizmodo.com/5959553/users-start-giving-up-on-streaming-video-if-it-takes-two-seconds-to-load)

Research Data: http://people.cs.umass.edu/~ramesh/Site/HOME_files/imc208-krishnan.pdf University of Massachusetts, Amherst & Akamai Technologies

Consideration #1 - StreamingProtocols:HTTP (hyper text transfer protocol):

• chops web pages into packets for fast, asynchronous deliveryRTSP (Real Time Streaming Protocol):

• delivers continuous stream of multimedia data• requires specialized streaming media server

Adaptive Bit-Rate - HTTP Live Streaming, Smooth Streaming and HTTP Dynamic Streaming:• HTTP Live Streaming is backed by Apple, Smooth Streaming is

backed by Microsoft and HTTP Dynamic Streaming is backed by Adobe

• emergent solutions that are not yet standardized – not all platforms are supported

• “fakes out” streaming by delivering “chunks” of content delivered via HTTP that self-adjusts delivery packets

• requires additional production overhead and asset management

Consideration #1 - Streaming

Adaptive bit-rate:This delivery method is beginning to have a massive impact on every aspect of Internet video delivery because it allows the stream to actually adapt the video experience to the quality of the network and the device's CPU.

Consideration #1 - Streaming

Essentially, the video stream can increase or decrease the bit rate and resolution of the video (its quality) in real time so that it’s always streaming the best possible quality the available network connection can support. The better the network connection, the better the video image quality. The fact that the stream handles all of this complexity means the mobile video viewer doesn’t have to do anything; everything is left to the stream and the player.

Consideration #1 - Streaming

Consideration #1 - Streaming

http://www.w3.org/TR/2013/WD-media-source-20130905/

Consideration #1 - Streaming

http://www.longtailvideo.com/html5/mediasource/

Consideration #2: Encoding Considerations

H.264: considered to be the front-runner / industry standard Licensed codec via MPEG LA – Royalty status remains vagueWebM: “free” codec developed by Google Royalty free for use by content producersOgg Theora: Open Source codec Considered ‘dated’ and support diminishing in favor of WebM

Consideration #2: Encoding Considerations

The Bottom Line?To provide full support today to all users and user-platforms we will need to consider encoding videos at least twice, in 2 formats.

Recommendation?H.264 & WebM codecs

Consideration #3: Security

There are at least 2 types of security concerns with video delivery on the web:

Script Injections: Since many video controls and captions use some form of scripting, caution must be taken to ensure that they do not introduce security holes that can be exploited.

Consideration #3: Security

http vs. https: Since the video and all related assets (captions, transcripts, video descriptions) are traditionally served to the web browser as discrete files, when we look to embed a video on a secure page, those supplemental files will also need to be served securely to avoid User Security Warnings.

Consideration #4: Accessibility

The W3C have produced a detailed list of all requirements various user-groups would need for full and complete access to multi-media.

http://www.w3.org/WAI/PF/media-a11y-reqs/

Consideration #4: Accessibility

At a minimum, users require accessible media player controls (start, stop, pause, mute, etc), as well as time-synched captions, descriptive audio, and full transcripts of all content delivered.

Consideration #4: AccessibilityWCAG 1.2.1 Provide alternatives for Prerecorded Video: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content. (A)

WCAG 1.2.2 Captions: Captions are provided for all prerecorded audio content in synchronized media. (A)

Consideration #4: AccessibilityWCAG 1.2.3 Audio Description or Media Alternative: An alternative for time-based media or audio description of the prerecorded video content is provided for synchronized media. (A)

WCAG 1.2.5 Audio Description: Audio description is provided for all prerecorded video content in synchronized media. (AA)

Definitions:Closed Captions / Open Captions: Closed captions can be turned “on or off” by the end user Open Captions remain on-screen for all users

Captions capture onscreen dialog and basic sound effects (<<clapping>>, <<music>>, <<laughter>>, etc.)

Resource: http://www.dcmp.org/captioningkey/

Definitions:Caption Formats: TTML (Timed Text Markup Language) – XML based (includes DFXP, a standard for Flash players)

WebVTT (Web Video Timed Text) – emergent standard, text based, favored by browser vendors

Other formats exist – conversion from one format to the other is a mechanical process

Definitions:Transcripts: Loosely defined in the web space Generally are more complete than captions – includes additional on-screen information (descriptions of charts or other visual assets for example) Traditionally offered as a complementary piece to the media asset (unlike captions which are delivered in a synchronous fashion with the media) Usually provided as HTML or downloadable text formats such as accessible PDF

Definitions:Descriptive Audio: Supplemental audio track, provided on demand, which describes on-screen actions to the non-sighted.

Specified as a WCAG requirement (1.2.5), delivery technologies remain rudimentary with little practical support in the wild.

Consideration #4: AccessibilityRe: WCAG 1.2.5 Audio Description:At this time, delivering on this AA Requirement is severely frustrated due to the lack of robust native support in browsers and mobile devices. Many entities are choosing to NOT require this Success Criteria, including the Governments of Canada, Ontario and Quebec.

The Access Board in the US will likely seek to maintain the current requirement in provision 1194.24(b) that ICT hardware support audio description , which might improve the current situation. Fingers crossed.

Accessibility Production Requirements:The most labor-intensive

aspect of ensuring accessible media is the generation of the text that represents the audio (and in some cases descriptions of on-screen activity), to be subsequently integrated into the final on-screen delivery to the end client. Videos created from an approved script will already have text

to work with, however when no script is available the process of ensuring accurate text transcription remains a manual process.

Accessibility Production Requirements:

While advances in speech to text have come a long way, and continue to evolve in terms or accuracy, at this time the only dependable way of ensuring accuracy is through the involvement of human input.

Accessibility Production Requirements:• Support for “Closed

Captions” on mobile devices today is practically non-existent.• This means that for the mobile platform today, we will need to be able to offer the end user a choice of the non-captioned video, or an Open Captioned video prior to the launch of the video itself.

• The same technical limitations currently impact the provisioning of descriptive audio as well.

Recap:• Streaming solutions like Adaptive Bit-Rate

delivery are emerging as absolute requirements to address different screen resolutions, bandwidth considerations, etc.

• There are existing proprietary solutions in the market-place that address some, but not all needs

• W3C’s Media Source Extension specification is at Last Call, with minimal browser support today

Recap:• The “codec wars” remain at a stalemate,

necessitating multiple encodings to support HTML5’s <video> element

• H.264 and WebM codecs are the recommended choices today

• Caution should be exercised with regard to security considerations. Beware of script injection holes

• Videos served from a secure environment will need to ensure that all supporting assets are also served securely

Recap:• At a minimum, users require accessible

media player controls (start, stop, pause, mute, etc), as well as time-synched captions, descriptive audio, and full transcripts of all content delivered.

• There is currently no native support in the browsers to satisfy WCAG 1.2.5 (AA)

• The creation of text based alternatives remains for the most part a manual process today

• Delivering Captioned videos on mobile currently requires Open Caption alternatives

Recap:

Kind of disappointing, right?While problems still exist, there is forward movement

at a decent pace.Remember, patience is a

virtue.

Exciting developments to watch:

The A11yMetadata Project seeks to extend schema.org by including new properties to address the accessibility and discoverability of resources on the Web.

http://www.w3.org/wiki/WebSchemas/Accessibility

The A11yMetadata Project

Specifying content features of the resource, such as accessible media and alternatives:<meta itemprop="mediaFeature" content="alternativeText">

PROPOSED VALUES:alternativeTextaudioDescriptionbraillecaptionsChemMLdescribedMathdisplayTransformability

haptichighContrastlargePrintlatexlongDescriptionMathMLmusicBraillemusicLargePrint

nemethBraillesignLanguagestructuralNavigationtactileGraphictactileObjecttranscript

Exciting developments to watch:

The Descriptive Video Exchange project focuses on crowd-sourced techniques for describing DVD media. CSD will expand DVX to include Internet-based media such as YouTube, iTunes U, and other streamed video found on a wide variety of web sites.

http://www.vdrdc.org/research/csd

Exciting developments to watch:

This new project aims to demonstrate the inclusion of enhancements in ways that are both visual and non-visual, all of which are screen-reader accessible and delivered using HTML5, JavaScript and the Popcorn.js HTML5 Media Framework.

http://ncamftp.wgbh.org/rd/hgp/

Using HTML5 and JavaScript to Deliver Accessible Supplemental Materials

Thank youQuestions?

Contact Mejohn@foliot.cahttp://john.foliot.ca

Accessible Video in the Enterprise September, 2013