Recommendations
Preamble: Multimedia
Let’s be realistic
- It’s unrealistic to expect authors to caption all their videoclips right away.
- They don’t have the expertise and certainly should not be encouraged to guess or dabble.
- Player complications are significant, and if the author provides video in multiple formats, then multiple incompatible caption formats will also be required.
- Authoring tools for Web captioning and description simply are not up to the task. Captioning itself is difficult and captioning software makes things worse.
- Sending video out of house for captioning costs hundreds or thousands of dollars per program hour. For many small and medium-size Web publishers, that constitutes undue hardship right there.
- In some languages and countries, there is no tradition or practice of captioning at all, even on television.
- It’s even more unrealistic to expect authors to describe all their videoclips right away.
- While captioning requires, at root, reading and transcription skills, description requires specific creative-writing ability plus a voice amenable to description and a means to record and mix that voice. (Using a speech synthesizer for description is not currently done and should be discouraged. Blind people listen to enough robotic speech already.)
- There are very few languages and countries in which audio description has a tradition or practice.
- Some programming genres, especially as found on the Web, do not urgently need description. Fictional narrative programming and documentaries – two genres classically associated with audio description – are uncommon online and will probably stay that way.
Improvement and phase-in
Those conditions will eventually improve. It will eventually become more common, and presumably easier and less expensive, to provide captions and descriptions online.
But multimedia online is unlike other Web content. Similarly, accessibility for multimedia is also different.
Consider the case of authors with inaccessible sites. They’re faced with going from 0% of compliant content (or some other low proportion) to 100%.
- It’s possible for authors to give themselves a deadline by which they will have fixed everything up in order to meet WCAG 2.0 – for content other than multimedia.
- But it would be highly unusual for an author to be able to meet multimedia requirements by a specific day (save for the case where very little multimedia is offered). That’s because captioning and description are time-consuming, expensive, and technically error-prone.
Thus, for content original to the Web, a phase-in period is required. For content reused from other media, though, captions and descriptions can be provided immediately with no phase-in. That kind of reused accessibility will in itself increase the available quantity of captioned and/or described online media by orders of magnitude.
Transcription
- Transcription is not the way to make video accessible. The correct accessibility methods are captioning and audio description.
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A transcript is an artifact separate from the original, just as a talking book or large-print or Braille edition is separate from a printed book. But audiovisual media can and must carry their accessibility features with them.
- If an online video segment is provided with captions, a transcript can be added and offered later. A transcript must never be the sole method of accessibility for deaf and hard-of-hearing viewers. At best it can be supplemental.
- “Text descriptions” are meaningless and unheard of in audio description. They are a figment of the imagination with no benefit whatsoever to a blind or visually-impaired viewer. The medium of accessibility for that audience is sound and voice, not the written word. WCAG’s own guidelines require synchronized media equivalents. Transcripts are not synchronized.
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A “combined” caption transcript plus audio-description script has been attempted exactly once in known history (for a demonstration project that was never completed). There is no method to combine those two sources due, among other reasons, to a lack of interchange formats. The idea is a non-starter.
Reuse of existing captions and descriptions
- Authors should be required to reuse any captions or descriptions that were created for the original program.
- That means all TV programming captioned or described for television must carry its accessibility over to the Web.
- It’s technically straightforward, inexpensive, and almost immediately achievable, even for audio description.
- It’s already being done now.
Phase-in
- It’s unrealistic for WCAG to require all or even a specific percentage of captioned and described video immediately upon an author’s adoption of WCAG.
- It’s unrealistic to expect authors to zoom from a probable state of zero captioning and description to 100% or some other percentage overnight.
- Because of the unique nature of captioning and description – as with multimedia itself, both fields are dissimilar to other Web content – a phase-in period is required.
Multimedia: Recommendations
Reuse of captions and descriptions
Video content with a soundtrack that has been captioned and/or described in another medium must be captioned and/or described when presented online.
- Content that meets requirements for captioning and/or audio description in another medium will be deemed to meet these requirements if captions and/or descriptions are preserved and made available online.
- To comply with this exemption, content must be substantially identical both in the original medium and on the Web.
Techniques
Captioning
- For a video presentation that was closed- or open-captioned in another medium (e.g., television, video, DVD), retain and reuse the captions.
- Use a caption decoder and digitize a copy of the video with captions decoded (open or burned in). If necessary, produce an open-captioned submaster tape and digitize that.
- For presentations with bitmap captions (e.g., DVD or DVB originals), digitize a copy with the bitmaps open or burned in.
- If an uncaptioned version is available immediately and a captioned version available only later, provide the captioned version as soon as reasonably possible after it becomes available.
- Captioning may be optional or mandatory. Authors may provide separate captioned and uncaptioned streams or a single captioned stream.
- For an optional stream, give the visitor an accessible method of selecting captioned or uncaptioned video.
- For any stream with captions, provide a statement, in an accessible form, that the video is captioned.
Audio description
- For a video presentation that was closed- or open-described in another medium (e.g., television, video, DVD), retain and reuse the descriptions.
- Use the described audio mix (main program audio plus descriptions) along with the original video images.
- If an undescribed version is available immediately and a described version available only later, provide the described version as soon as reasonably possible after it becomes available.
- Description may be optional or mandatory. Authors may provide separate described and undescribed streams or a single described stream.
- For an optional stream, give the visitor an accessible method of selecting described or undescribed video.
- For any stream with descriptions, provide a statement, in an accessible form, that the video is described.
Original Web content
- Authors must provide captioning and audio description for video content with a soundtrack that is original or new to the Web (i.e., it appears online first or has never been captioned or described in another medium).
- Develop and publish, in an accessible format, a schedule of commitments to increase the proportion of video that is captioned or described. Meet the commitments stated in the schedule.
- At the end of the schedule, the proportion of video that is captioned and described must be 100%, unless such a proportion would represent undue hardship.
- The schedule must phase in captioning and description over a reasonable but limited time. It must state its opening and closing dates (the first and last dates on which the schedule has effect).
- The schedule must state whether or not material provide before the schedule’s opening date will be provided with captions and descriptions, and if so, in what proportion. Meet those commitments.
- Requests for the addition of captioning and/or description to material provided before the opening date must be honoured unless doing so would represent undue hardship.
- Use methods of captioning and audio description that are likely to be compatible with technologies used by a broad range of viewers.
- Open captioning or open description may be used, with separate streams for captioned and/or described video or a single stream that always has captions and/or descriptions. Any method an author creates to select any specific feed must meet accessibility guidelines for functions of that type.
- Closed captioning or closed description may be used. Any method an author creates to activate and deactivate captions or descriptions must meet accessibility guidelines for functions of that type.
- Transcripts may optionally be provided in addition to captioning.
Exemptions
- Silent videoclips may be exempted from description requirements in some circumstances. Adding a soundtrack purely for description involves a significant alteration of the source – much more so than adding (more) voice to an existing soundtrack.
- Audio-only presentations should have no captioning requirements. They have no visual form. (Analogy: Music videos must be captioned but music need not be.) A transcript may be optionally provided later, but, as with video presentations, cannot be a requirement.
- Live video and audio presentations should require captioning or description only if the source is already captioned or described. Adding real-time captions is an onerous process online, reliant on proprietary JavaScript methods; it’s also expensive. Live description has almost never been attempted.
Colour
Recommendations
- Don’t use colour as the sole method of indicating structure.
- Don’t use colour in a way that is likely to cause confusion among viewers with common colour deficiencies.
- Use foreground/background colour combinations that are likely to be legible for viewers with colour deficiencies. Optionally, include an accessible method by which the viewer can alter foreground/background combinations.
Techniques
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Use correct semantic elements for the content being marked up. Add colour through the use of stylesheets.
- Examples. Here, the stylesheet declaration
.red { color: red; }
is used throughout.
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Improper
-
<font color="red">
Deadlines</font>
-
font
is a deprecated element that does not indicate any kind of structure.
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Improved
-
<span class="red">Deadlines</span>
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span
, like div
, is “a generic mechanism for adding structure to documents,” and provides limited semantic value. Its use for colour specification indicates to user agents that the content it encloses is a “generic structure.” If colour is unavailable, user agents may not be able to extract structural meaning from the markup.
- Preferred
<strong class="red">Deadlines</strong>
-
The use of the HTML element
strong
provides semantic markup for the content that will remain available to user agents even if colour is not available.
- Confusable colour pairs are those likely to be confounded or mistaken by people with common forms of colourblindness. Red–green, red–black, and blue–green are confusable colour pairs.
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Do not set confusable pairs on top of each other (e.g., a red foreground on a green background).
- Use confusable colour pairs only for items, areas, or design elements that do not carry meaning.
- Example: Background or border colours that are separated or distant from text or other foreground content may use confusable colours.
- If it is necessary to use confusable colour pairs for structural elements or other meaningful content, ensure that the use of colour would be unlikely to cause actual confusion.
- Example: Red and green interface buttons can be placed alongside each other as long as their text or meaning can be understood even if their exact colour cannot be distinguished.
- Use the Brewer Palette – colour combinations known to cause little, if any, confusion among viewers with colour deficiencies.
- Red/blue
- Increments: Dark red; medium red; light red; light blue; medium blue; dark blue
- Orange/blue
- Increments: Dark orange; medium orange; light orange; light blue; medium blue; dark blue
- Orange/purple
- Increments: Dark orange; medium orange; light orange; light purple; medium purple; dark purple
- Yellow/purple
- Steps (note the restricted list): Yellow; light purple; medium purple; dark purple
- Brown/blue
- Increments: Dark brown; medium brown; light brown; light blue; medium blue; dark blue
- Yellow/blue
- Increments: Yellow; light blue; medium blue; dark blue
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Do not refer to content by its colour alone.
- Example: Indicating new additions to a listing (as of files, albums, books, or other items). Here, the stylesheet declaration
.red { color: red; }
is used throughout.
-
Improper
-
Listings in
<font color="#FF0000">
red</font>
indicate new releases added this week.
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The red listings will be indiscernible to some viewers. Since no structural markup is in use, it’s impossible for user agents to interpret structure even without colour.
- Improved
- Listings in
<span color="#FF0000">
red</span>
indicate new releases added this week.
span
markup provides generic structure for the reference to colour and to the content marked up with colour.
- Preferred
- Listings in
<ins class="red">
red</ins>
indicate new releases added this week.
- Using the correct HTML element –
ins
for insertion, with a separate style declaration for colour – lets user agents recognize the new entries purely from the underlying structure even if a viewer cannot discern the colour.
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For foreground and background colours, dark-on-light and light-on-dark combinations are better than dark-on-dark or light-on-light combinations.
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Where possible, provide a stylesheet-switcher or other means by which the viewer may adjust colour combinations.