principle: Perceivable
Make sure that everyone can perceive or detect the same content and components. Can people perceive this content with whatever capacity they have?
1.1.1 Non-text Content
Images must have descriptive alternative text.
1.2.1 Audio-only and Video-only (Pre-recorded)
Any audio-only content must also be conveyed in text. Any video content with no audio track must also be described in text, but could also be described with audio.
1.2.2 Captions (Pre-recorded)
The audio in videos must be captioned.
1.2.3 Audio Description or Media Alternative (Pre-recorded)
Actions, descriptions, and other important non-audio content in videos must be described in captions, a separate audio track, or a text-based alternative like a screenplay.
1.2.4 Captions (Live)
Live videos that include audio must be captioned.
1.2.5 Audio Description (Pre-recorded)
Actions, descriptions, and other important non-audio content in videos must be described in captions or a separate audio track.
1.2.6 Sign Language (Pre-recorded)
All prerecorded videos have sign language interpretation.
1.2.7 Extended Audio Description (Pre-recorded)
Video is sometimes paused in order to give enough time for audio descriptions to be conveyed properly.
1.2.8 Media Alternative (Pre-recorded)
A text-based transcription of a video is offered, on top of closed captions and audio description.
1.2.9 Audio-only (Live)
Live captioning is provided for live audio.
