Creating Video Available Objective
A primer around the world wide web accessibility requirements because they relate to video and creating your videos compliant with individuals criteria.
Introduction
Web accessibility refers to your practice of doing websites usable for all customers, in particular for all those with disabilities, guaranteeing that most people has equal access to all internet content. The entire world Extensive Website consortium (W3C) has established a set of pointers recognized as Website Written content Accessibility Tips, which attempts to provide a standardized and definitive set of principles for tips on how to establish available using the web articles.
Contents Accessibility Recommendations Accessibility Instance Illustration Codes Solution Ways Authoring Tools Accessibility Pointers
Let's first have a look at accessibility for the physically disabled. The W3C consortium has developed a set of guidelines recognised as the internet Articles Accessibility Tips (WCAG 1.0).Introduced in 1999, these guidelines have since been widely adopted. A second version (WCAG 2.0) was published in December of 2008. Here's an overview of the current expectations:
WCAG 1.0 WCAG 2.0 importance of the subject matter A AA AAA A AA AAA (closed) captions X X X X* X X (closed) audio description X X X X* X X full text substitute X* X sign language X
* Choose at least one of the three options.
As you can see, according for the W3C, captions should be available for every published video clip. Captions are defined as "synchronized text equivalents of audio information in the same language as the audio, conveying not only speech content, but also non-speech information such as sound effects,
Windows 7 X86 Key, music, laughter, and speaker identification and location." Closed captions must possess the option of being turned on or off at will. Non-closed (open) captions are printed around the video clip itself
The second important element is audio description, which makes video accessible towards the visually impaired. It provides information about movements or actions that are important to comprehending the information and cannot be understood from the audio information alone. WCAG 1.0 always requires an audio description, while WCAG 2.0 permits you to replace it with a text description, but only for your least important content material.
In addition on the requirements in the table above, two other generally accepted rules of thumb are:
Don't enable autoplay (audiovideo should be user-activated). Don't substitute HTML or text files for captions and audio descriptions
Note that the WCAG 1.0 contains less requirements for live video clip, decorative video and audio. Eric Velleman from Accessibility.nl has written a detailed document on this topic,
Office 2010 Standard Key, which is also available in Dutch.
Accessibility Instance
A properly accessible video clip should contain captions and an audio description. Let's see how this works in a real-life illustration. The video below shows an excerpt from ITV's Coronation Street, as shown about the RNIB website:
playpause the video clip muteunmute the video clip rewind and stop the video
The video clip is played back in the JW Player for Flash. It's one of the few players that can display both closed captions and a closed audio description. Since it is built in Adobe's Flash, 95-99% of your visitors will be able to watch it.
Other accessibility features of this player are its keyboard controls (using the TAB and SPACE controls), its screen reader-labeled buttons and the full-screen button. Also,
Office 2010 License, immediately above the player, hidden controls allow screen reader users to control the basic functionality of the player (Play Mute Stop).
This instance uses the SWFObject JavaScript to detect if your visitors have the right Flash plugin (and JavaScript) installed. If so, the player is shown. If not, the player falls back to show an image linking to a downloadable video clip file. You can see a demonstration of how this works by turning off your browser’s JavaScript and reloading this page. Again, both the image and link have a text label for screen readers.
Instance Codes
Here's the actual code used for the accessibility example above.
<p id="video"> <a href="corrie.mp4" title="download the MP4 excerpt"> <img src="corrie.jpg" width="470" height="300" alt="a small excerpt from ITV's Coronation Street" > <a>
<p> <script type="textjavascript"> var sa = new SWFObject('player.swf','mpl','470','300','9'); sa.addParam("allowfullscreen","true"); sa.addParam("allowscriptaccess","always"); sa.addParam("seamlesstabbing","true"); sa.addParam("flashvars","file=uploadcorrie.flv&ima ge=uploadcorrie.jpg&captions.file=uploadcorrie.xml &audiodescription.file=uploadcorrie.mp3&plugins=ca ptions-1,audiodescription-1"); sa.write('video');
<script>
And this is what the TimedText XML file looks like:
<tt xmlns=" <body> <div xml:id="captions"> <p begin="00:08" end="00:10">- Nothing is going on.<p> <p begin="00:10" end="00:12.5">You liar!<p> <p begin="00:13" end="00:15">Are you?<p> <p begin="00:17" end="00:20">Violet, please,
Office Home And Student 2010 Keygen!<br>- I am not your babe!<p> <p begin="00:24" end="00:29">You stupid cow,<br>look what you gone and done now, ay.<p> <p begin="00:34" end="00:36">Vi, please.<br>- Leave me alone!<p> <p begin="00:36" end="00:38.5">- We need to talk.<br>- Jason, are you deaf?!<p> <p begin="00:41" end="00:43">What's going on?<p> <p begin="00:43" end="00:45">Get out there and try to salvage this!<p> <div> <body>
<tt>
This setup can be tweaked a bit to further enhance the quality. Some methods are listed below:
Use the captions.fontsize FlashVar to change the size of the captions font. (default = 14). Set the captions.back FlashVar to "true" to show a semitransparent backdrop that makes the captions more readable. Set the captions.state FlashVar to "false" to turn off the captions by default. Use the audiodescription.volume FlashVars to change the volume of the audio description (default = 90). Set the audiodescription.state FlashVar to "false" to turn off audio descriptions by default. Use a full JavaScript API to extend the hidden controls above the player. Use the upcoming Accessibility plugin to toggle on off audio and captions. Solution Methods
Besides the JW Player for Flash, Windows Media and QuickTime both support closed captions,
Office 2010 Professional Plus 32 Bit, with SAMI format and QTtext 3GPP Text support, respectively. However, neither of these players support a closed audio description.
Note that the downloadable video clip file is an MP4. This is a high-quality format, which is very popular among mobile devices such as iPods iPhones, the PSP and many smart phones. The MP4 format, though, isn't very useful if your target audience has older browsers or devices. It's fairly new and isn't supported by the default Windows installations. If your goal is to maximize reach, it’s best to encode any download as an MPG; its quality relative to file size is poor, but it’s able to play on just about everything. If you want to maximize accessibility even further, you can always hard code the captions and audio description into the video clip.
Authoring Instruments
There's a whole range of applications that can transcode your original video files into any format you’d like (e.g. FLV, MP4, WMV, MPG). There’s a helpful list of links to some interesting applications in the internet Video clip Compression guide.
Unfortunately, there are only few applications available for creating closed captions:
NCAM's magPIE (free, also for MAC) URUSoft's Subtitle Workshop (free) Manitu Group's Captionate ($60) VideoToolShed's SubBits subtitler ($199)
Both magPIE and Subtitle Workshop support the export of captions to W3C's TimedText (Flash), SMILQTtext (Quicktime) and ASXSAMI (Windows Media). For Subtitle Workshop you need the TimedText output script (available from Naomi Spirit). Captionate, (intended for FLV video clip) can only export to W3C's TimedText, though it can also save captions as metadata.
Only magPIE has support for recording audio descriptions, but it’s somewhat limited. You cannot record to MP3 and cannot merge recorded samples or integrate them with a video clip. For now, a full-fledged audiovideo suite, like Adobe's Premiere Audition or Apple's iMovieGarageBand, is needed for creating closed audio descriptions.