Guideline 1.2: Time-based Media (part 2)

On Principle 1: Perceivable

Criterion 1.2.1 [Audio-only and Video-only (Prerecorded)]

For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such: (Level A)

  • Prerecorded Audio-only: An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content.
  • Prerecorded Video-only: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.

How to. Mandatory techniques

  • Provide an alternative for time-based media for audio-only content (prerecorded audio-only)
  • Provide an alternative for time-based media for video-only content (prerecorded video-only)
  • Provide audio that describes the important video content and describing it as such

Additional, Advisory Techniques

  • Provide a transcript of a live audio only presentation after the fact
  • Link to textual information that provides comparable information (e.g., for a traffic Webcam, a municipality could provide a link to the text traffic report.)

Common Failures

  • Using alternative text that are not descriptive. E.g. alt=”spacer” , alt=”icon.jpg”, alt=”image2″…
  • Providing long descriptions for non-text content that does not serve the same purpose or does not present the same information

Criterion 1.2.2 [Captions (Prerecorded)]

Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A)

How to. Mandatory techniques

  • Providie open (always visible) captions
  • Provide closed captions using any readily available media format that has a video player that supports closed captioning
  • Provide closed captions using SMIL 1.0 (SMIL) or SMIL 2.0 (SMIL)

Additional, Advisory Techniques

  • Provide a note saying “No sound is used in this clip” for video-only clips
  • Use SMIL 1.0 or SMIL 2.0 to provide captions for all languages for which there are audio tracks

Common Failures

  • Captions omitting some dialogue or important sound effects
  • Providing synchronized media without captions when the synchronized media presents more information than is presented on the page
  • Not labeling a synchronized media alternative to text as an alternative

Criterion 1.2.3 [Audio Description or Media Alternative (Prerecorded)]

How to. Mandatory techniques

  • Provide an alternative for time based media linking to the alternative for time-based media immediately next to the non-text content; or using the body of the object element (HTML)
  • Provide a second, user-selectable, audio track that includes audio descriptions
  • Provide a version of a movie with audio descriptions using SMIL 1.0 or SMIL 2.0 or using any player that supports audio and video
  • Provide a movie with extended audio descriptions using SMIL 1.0 or SMIL 2.0 or using any player that supports audio and video

Additional, Advisory Techniques

  • Use SMIL 1.0 or SMIL 2.0 to provide audio description in multiple languages

Criterion 1.2.4 [Captions (Live)]

Captions are provided for all live audio content in synchronized media. (Level AA)

How to. Mandatory techniques

  • Create captions for live synchronized media and provide open (always visible) captions
  • Create captions for live synchronized media and closed captions using any readily available media format that has a video player that supports closed captioning
  • Create captions for live synchronized media and provide closed captions using SMIL 1.0 or SMIL 2.0

Criterion 1.2.5 [Audio Description (Prerecorded)]

Audio description is provided for all prerecorded video content in synchronized media. (Level AA)

How to. Mandatory techniques

  • Provide a second, user-selectable, audio track that includes audio descriptions
  • Providing a version of a movie with audio descriptions using SMIL 1.0 or SMIL 2.0 or using any player that supports audio and video
  • Provide a movie with extended audio descriptions using SMIL 1.0 or SMIL 2.0 or using any player that supports audio and video

Additional, Advisory Techniques

  • Provide audio description in multiple languages in SMIL 1.0 or SMIL 2.0
  • Provide audio description for live synchronized media

Criterion 1.2.6 [Sign Language (Prerecorded)]

How to. Mandatory techniques

  • Include a sign language interpreter in the video stream
  • Provide a synchronized video of the sign language interpreter that can be displayed in a different viewport or overlaid on the image by the player using SMIL 1.0 or SMIL 2.0

Additional, Advisory Techniques

  • Use metadata to associate sign language alternatives of a video to enable choice of sign language. E.g. provide, in metadata, URI(s) that point to several English sign language translations (ASL, SASL, BSL, Auslan, ISL, NZSL) of a Web page.

Criterion 1.2.7 [Extended Audio Description (Prerecorded)]

Where pauses in foreground audio are insufficient to allow audio descriptions to convey the sense of the video, extended audio description is provided for all prerecorded video content in synchronized media. (Level AAA)

How to. Mandatory techniques

  • Provide a movie with extended audio descriptions using SMIL 1.0 or SMIL 2.0 or using any player that supports audio and video

Additional, Advisory Techniques

  • Add extended audio description in multiple languages in SMIL 1.0 or SMIL 2.0

Criterion 1.2.8 [Media Alternative (Prerecorded)]

An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media. (Level AAA)

How to. Mandatory techniques

If the content is prerecorded synchronized media:
  • Place a link to the alternative for time-based media immediately next to the non-text content OR
  • Link to the alternative using the body of the object element (HTML)
Situation B: If the content is prerecorded video-only:
  • Provide an alternative for time-based media for video-only content

Additional, Advisory Techniques

  • Use noembed with embed (HTML)
  • Provide a corrected script
  • Add detail to audio description

Common Failures

  • Not labeling a synchronized media alternative to text as an alternative

Criterion 1.2.9 [Audio-only (Live)]

An alternative for time-based media that presents equivalent information for live audio-only content is provided. (Level AAA)

How to. Mandatory techniques

  • Provide a link to a text transcript of a prepared statement or script if the script is followed
  • Provide text based alternatives for live audio-only content
  • Incorporate a live audio captioning service into a Web page

Additional, Advisory Techniques

  • Use metadata to associate text transcriptions with audio-only conten. E.g. provide, in metadata, URI(s) that point to several text transcripts (English, French, Dutch) of an audio file.

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