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Addresses the 1.2.8 exception in the 1.2 Time-based Media guideline #4533

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Addresses the 1.2.8 exception in the 1.2 Time-based Media guideline #4533

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d2ae19d
Addresses 1.2.8 concern in 1.2 Time-based Media Guideline
giacomo-petri Aug 11, 2025
738d710
Merge branch 'main' into giacomo-petri-time-based-media-guideline-1_2_8
bruce-usab Oct 2, 2025
a4fec9b
short name -> name
bruce-usab Oct 2, 2025
f8a68b5
Merge branch 'main' into giacomo-petri-time-based-media-guideline-1_2_8
patrickhlauke Oct 17, 2025
34d71ce
Follow EO style guide for UL
bruce-usab Oct 31, 2025
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Update understanding/20/time-based-media.html
giacomo-petri Nov 4, 2025
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105 changes: 39 additions & 66 deletions understanding/20/time-based-media.html
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</head>
<body>
<h1>Understanding Time-Based Media</h1>


<section id="intent">
<h2>Intent of Time-Based Media</h2>


<p>The purpose of this guideline is to provide access to time-based and synchronized
media. This includes media that is:
<p>
The purpose of this guideline is to provide access to time-based and synchronized media.
This includes media that is:
</p>

<ul>

<li>audio-only</li>

<li>video-only </li>

<li>audio-video </li>

<li>audio and/or video combined with interaction </li>

<li>video-only</li>
<li>audio-video</li>
<li>audio and/or video combined with interaction</li>
</ul>

<p>To make it easy for authors to quickly determine which success criteria apply to their
content, the type of media each success criterion applies to is included in its short
name.
<p>
Media can be <strong>live</strong> or <strong>prerecorded</strong>.
The success criteria names tell you if a success criterion applies to <strong>live</strong> or <strong>prerecorded</strong> media.
</p>

<p>For
<strong>audio-only</strong> or
<strong>video-only</strong> media, you only need to apply the success criteria that say "<strong>audio-only</strong>" or "<strong>video-only</strong>" in their short name. If your media is not
<strong>audio-only</strong> or
<strong>video-only</strong>, then all the rest of the success criteria apply.
<p>
To make it easy for authors to quickly determine which success criteria apply to their content,
the type of media each success criterion applies to is included in the name of the criterion.
</p>

<p>Media can also be
<strong>live</strong> or
<strong>prerecorded</strong>. Each of the success criterion short names clearly tells you if the success criterion
applies to
<strong>live</strong> or
<strong>prerecorded</strong> media.
<p>For <strong>audio-only</strong> or <strong>video-only</strong> media,
you only need to apply the success criteria that include "<strong>audio-only</strong>" or "<strong>video-only</strong>" in their name,
except that at Level AAA, <a href="media-alternative-prerecorded">1.2.8 Media Alternative (Prerecorded)</a> also applies to <strong>video-only</strong> media.
If your media is <em>not</em> <strong>audio-only</strong> or <strong>video-only</strong>, then <em>all</em> of the other of the success criteria apply.
</p>

<p>
Synchronized media is defined in the glossary as:
<block>audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such</block>
</p>

Synchronized media is defined in the glossary as:</p>
<blockquote>audio or video synchronized with another format for presenting information and/or with time-based interactive components,
unless the media is a media alternative for text that is clearly labeled as such.</blockquote>
<p id="copysynchronizedmediadef"></p>

<p>Note that an audio file accompanied by interaction is covered here, as is a video-only
<p>
Note that an audio file accompanied by interaction is covered here, as is a video-only
file that involves interaction. These are covered because interaction must take place
at a particular time. Having a text transcript that said, "for more information, click
now," would not be very helpful since the reader would have no idea when the audio
said, "now." As a result, synchronized captions would be needed.
</p>

<p>Sometimes, there is so much dialogue that audio description cannot fit into existing
<p>
Sometimes, there is so much dialogue that audio description cannot fit into existing
pauses in the dialogue. The option at Level A to provide an alternative for time-based
media instead of audio description for synchronized media would allow access to all
of the information in the synchronized media. This option also allows access to the
visual information in non-visual form when audio description is not provided for some
other reason.
</p>

<p>For synchronized media that includes interaction, interactive elements (for example
links) could be embedded in the alternative for time-based media.
<p>
For synchronized media that includes interaction, interactive elements (for example, links)
could be embedded in the alternative for time-based media.
</p>

<p>This guideline also includes (at Level AAA) sign language interpretation for synchronized
<p>
This guideline also includes (at Level AAA) sign language interpretation for synchronized
media as well as an approach called extended audio description. In extended audio
description, the video is frozen periodically to allow more audio description to take
place than is possible in the existing pauses in the dialogue. This is a case where
higher-level Success Criteria build upon the requirements of lower-level Success Criterion
with the intention of having cumulative, progressively stronger, requirements.


</p>

</section>

<section><h3>Text alternatives and equivalents match the language of the content</h3>
<p>Text alternatives and equivalents should match the human language of the original content (normally the default human language of the page). The <a href="https://www.w3.org/TR/WCAG22/#conformance-reqs">5.2 Conformance Requirements</a> section, through the defined terms used there, states that success criteria be met through accessibility-supported ways (5.2.4), where the technology is used “in the human language of the content.” Where an alternative version is used (5.2.1), it is defined as something that “provides all of the same information and functionality in the same human language.”</p>
<p>For time-based media, that normally means that where the spoken language of the media is, for example, Spanish, the language used in captions, audio descriptions, and media alternatives will also be Spanish.</p>
</p>
<p>
Text alternatives and equivalents should match the human language of the original content (normally the default human language of the page).
The <a href="https://www.w3.org/TR/WCAG22/#conformance-reqs">5.2 Conformance Requirements</a> section,
through the defined terms used there, states that success criteria be met through accessibility-supported ways (5.2.4),
where the technology is used <q>in the human language of the content.</q>
Where an alternative version is used (5.2.1), it is defined as something that <q>provides all of the same information and functionality in the same human language.</q>
</p>
<p>
For time-based media, that normally means that where the spoken language of the media is (for example) Spanish,
the language used in captions, audio descriptions, and media alternatives will also be Spanish.
</p>
</section>

<section id="advisory">
<h3>Additional Techniques (Advisory) for Time-Based Media</h3>


</section>










</body>
</html>