Audio-only and Video-only (Prerecorded)

Understanding WCAG2.0

Specify that the audio / video is substituting the existing text.

It can be said that recorded voices of lectures are providing "equivalent information" by preparing transcribed texts. When raising a text, it is necessary to describe in detail as much as possible, such as "a buzz of the audience" "(laugh)".

Since it is an image without sound, when raising a text, it is necessary to describe what is happening on the screen as much as possible.

If possible, it is still better if there is explanation by voice comment on what is happening on the screen.

Principle Perceivable Information and user interface components must be presentable to users in ways they can perceive.
Guideline Time-based Media Provide alternatives for time-based media.
Criterion Audio-only and Video-only (Prerecorded)
(1.2.1 A)
Consideration about media containing only recorded sounds and media containing only recorded images.

URL of Techniques for WCAG 2.0