Identify what the audio leaves unexplained
Review the owned programme for essential information communicated only visually: a demonstrated action, a changed diagram or an on-screen instruction, for example. The production goal is to convey what the audience needs to follow the content. A description of every visible detail can obscure that purpose.
Where appropriate, plan the spoken presentation to include those details from the beginning. W3C WAI describes integrated description as a production option. An instructor saying the button's name and what changes on screen can reduce the later need for an additional narration layer.
Choose a deliverable the destination can use
For an existing programme, decide whether description will be provided in an alternate mix, a separately labelled described version or another supported route. Check the actual destination capability before recording. A description-only recording may not be equivalent to a complete mix containing programme sound and narration.
Write against the approved picture cut and mark the intended narration intervals. Keep the script, voice recording and resulting mix associated with that revision. If the picture later changes, the relationship needs review even when the narration words still appear correct.
Give the information enough room
Identify gaps where narration can be understood without covering essential dialogue or sound. If the required information cannot fit, reconsider the wording, the production structure or an extended described version. Do not solve every timing conflict by speaking faster.
A hypothetical tutorial might reveal a diagram while a presenter speaks continuously. Planning a short explanatory pause can serve the audience better than adding a second competing voice. The choice belongs to the programme's communication goal and should be reviewed with the intended audience where practical.
Review the finished described experience
Listen to the delivered described version without relying on the picture. Check whether the steps can be followed and whether programme sound remains intelligible. Then review it with picture for timing and factual accuracy. These checks serve different purposes.
Confirm that the version is clearly discoverable and labelled in the final destination. Retain the original programme and description assets for revision. This workflow is informed by W3C WAI description guidance; it does not claim complete accessibility conformance or availability on a particular commercial service.
Questions answered
Is a narration-only track always a complete described mix?
No. Establish whether the destination expects a complete alternate mix or a supported separate component.
What if essential description cannot fit between dialogue?
Consider a revised production or extended described version rather than automatically masking important audio.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.