Audio description (described video) is a separate narration track that describes important visual elements - actions, scene changes, on-screen text - in the gaps between dialogue, so blind and low-vision viewers can follow the content. It is the visual-accessibility counterpart to captions.
Delivering it means carrying an additional audio track through the encoding ladder, packaging, and player, with UI to select it, plus the production work of authoring the descriptions. Audio description is increasingly mandated by accessibility law for certain content and is part of the broader accessibility obligation - alongside captions and WCAG conformance - that OTT platforms must plan for rather than retrofit.
The handbook · 7 volumes
Fora Soft Video Engineering Handbook
Audio description adds narration of key visuals for blind and low-vision viewers, and it has to sit in its own track with correct mixing and labels. We wrote seven volumes on the video stack; for audio description start with Volume 4 on accessibility, channel layouts, and loudness, then Volume 3 on track selection in players, with encoding in Volume 1. Written by Nikolay Sapunov, CEO at Fora Soft.
Adding audio description tracks to meet accessibility law on your OTT service?
We will review your audio track setup and send a plan for production, packaging, and player support. 250+ video products shipped since 2005.
