Caption AI demo replays so every viewer can follow them

Know what captions are

Captions are a text version of the speech and non-speech audio information needed to understand the content, synchronised with the audio. Captions are in the same language as the speech; subtitles translate it into another language. Closed captions can be turned on or off by viewers, while open captions are always visible.

For a demonstration, non-speech information matters. A notification sound, a typing pause or an error tone may be part of the story, and the caption should say so when it is needed to understand what happens.

Edit automatic captions

Automatically generated captions do not meet user needs or accessibility requirements unless they have been confirmed as fully accurate, and the automatic text is often wrong. Technical terms, product names and code are where errors cluster in AI demos.

Review the captions against the recording, fix terms and speaker names, and check timing so each caption appears while its words are spoken. Identifying speakers helps when a host and a guest talk over each other.

Meet the relevant standard

Under the Web Content Accessibility Guidelines, captions for prerecorded video with needed audio are required at Level A, and captions for live video are required at Level AA. For audio-only recordings, a transcript is the Level A requirement. A replay page can carry both captions and a transcript, and the transcript also helps viewers who want to search or skim.

• Start from automatic captions, then edit every line.
• Include non-speech sounds that matter to the demo.
• Check technical terms, names and code carefully.
• Synchronise captions with the speech.
• Offer a transcript alongside the replay.