Audio Description vs Subtitles: Who Each Serves

Two gaps, two solutions

A video carries information through two channels. Sound carries dialogue, narration, music and effects; the picture carries actions, faces, settings, charts and on-screen text. Anyone who misses one channel misses part of the content.

Subtitles and captions fill the gap for viewers who miss the sound, whether because they are deaf or hard of hearing, watching muted or don't understand the spoken language. Audio description fills the gap for viewers who miss the picture, chiefly blind and low-vision people. The distinctions between captions and subtitles themselves are covered in captions vs subtitles; here both count as the text-on-screen side.

What audio description adds

Audio description is an extra layer of narration that describes what is happening visually, usually placed in natural pauses between dialogue so it doesn't talk over the speakers. A good description is selective: it tells the listener what they need to follow the content, such as who entered, what a chart shows or what a sign says, without interpreting or editorializing.

Standard description: Narration fitted into existing pauses. The video's timing is unchanged.
Extended description: The video pauses so a longer description can play, used when the natural gaps are too short.
Descriptive transcript: A text document combining speech, sound cues and visual descriptions, readable with a screen reader or braille display.
Delivery: A separate described audio track, a described version of the video, or, less commonly, a text track read aloud by assistive technology.

Many broadcasters and streaming services offer described tracks on at least part of their catalog, selectable from the same menu as audio languages. On your own platform, support for a second audio track varies, so a separate described version of the video is often the practical route.

What subtitles and captions add

Subtitles present spoken words as timed text. Captions go further for deaf and hard-of-hearing viewers by identifying speakers and noting meaningful sounds like laughter, alarms or music. Either way, the information flows from the audio channel into the visual one.

That means subtitles do nothing for a blind viewer. They also leave a gap for deaf viewers if the visuals are hard to follow, but that is a design problem rather than a captioning one. A sighted, hearing viewer may benefit from both for convenience, but the core audiences are distinct.

Where the two meet: foreign-language video

A subtitled foreign-language film is largely inaccessible to a blind viewer, because the translation exists only as text on screen. Some broadcasters address this with spoken subtitles, where a voice reads the subtitles aloud, and dubbing solves it more completely by putting the translation in the audio channel.

This is one place where translated audio, including AI dubbing, overlaps with accessibility: a dubbed lecture or training video lets a blind viewer follow speech in their language. It still doesn't describe the visuals, so a video that relies on slides or demonstrations needs description in the target language as well.

Deciding what your video needs

A talking-head video where everything important is spoken: captions are essential; description may add little if the narration already covers the visuals.
A tutorial that says "click here" or "as you can see": captions plus description, or better, rewrite the narration so it names what's on screen.
A video with key text on screen, such as phone numbers, warnings or chart values: description, or narration that reads the text aloud.
A silent or music-only video with meaning in the visuals: description is the main need; captions may only note the music.
A video in a language the audience doesn't speak: translated subtitles for sighted viewers, a dubbed or voiced version for blind viewers.

Accessibility standards treat these as separate requirements. WCAG 2, for example, has distinct success criteria for captions on prerecorded video, for audio description or a media alternative, and for extended description at its highest level. Which level applies to you depends on your sector and jurisdiction, so check your organization's policy; the education-specific view is in captions for educational video accessibility. This is general information, not legal advice.

Example: a safety video that needs both

Example: a 6-minute workplace safety video

A facilities team films a fire-evacuation walkthrough. The presenter says "go through here, then follow these to the exit" while pointing at a door and floor signs. Captions make the speech available to deaf staff, but a blind employee hears only "through here" and "these". The team re-records two lines to name the stairwell door and the green exit signs, then writes three short descriptions for the remaining visual-only moments.

In that walk-through, the cheapest fix was in the script, not in post-production. Describing visuals in the narration itself, sometimes called integrated description, serves every viewer and leaves fewer gaps for a separate description track to fill.

Planning both for one video

List every moment where meaning lives only in the picture: on-screen text, gestures, demonstrations, charts and scene changes.
Where you still can, change the script so the speaker names those things aloud.
Produce captions or subtitles from the final audio and correct names, numbers and terms.
Write descriptions for the remaining visual-only moments, fitted to pauses; mark where extended description would be needed.
Record or synthesize the description, mix it with the program audio, and publish a described version or an additional audio track.
Offer a descriptive transcript as well, combining speech, sound cues and visual descriptions.
Test with blind, low-vision, deaf and hard-of-hearing users if you can; they will catch gaps a checklist misses.

Limits of automating description

Automatic captioning is now routine, but automatic audio description is much harder. Speech recognition transcribes something that is already there; description requires judging which visual details matter, in what order and in how few words, then fitting them into gaps. Systems that generate visual descriptions exist and are improving, but they can describe the wrong things, miss the point of a scene or state guesses as facts. Treat machine-generated description as a draft for a human describer to rewrite, and involve blind reviewers where the stakes are high. The broader picture of where AI helps and hurts is in AI and video accessibility.

What mydubly covers, and what it doesn't

mydubly works only with the audio in your file. It does not create audio description, does not analyze the picture and does not translate on-screen text. What it can contribute is the speech side: the subtitle generator produces a transcript, a timestamped transcript and SRT and VTT subtitles from your video, in the spoken language or a chosen target language. Subtitle cues have no speaker labels or sound descriptions, so captions for deaf viewers need those added during review. If your player supports WebVTT, the VTT generator page explains that output.

The timestamped transcript can also be the starting point for a descriptive transcript: you add descriptions of the visuals between the speech segments. For foreign-language audiences, AI dubbing gives a translated voice track that blind viewers can follow, with the limits noted above: one voice for the whole video, and the original music and effects are replaced. The 6-minute safety video would cost 6 credits (0.6¢) for subtitles, or 300 credits (30¢) for a dubbed version.

Start from the gaps in your video

Watch your video once with the sound off and once with your eyes closed. What you miss the first time is what captions must cover; what you miss the second time is what description must cover. Begin with the speech side using the subtitle generator, and plan description as a separate, human-led task.

Frequently asked questions

Is audio description the same as a voice-over?

No. A voice-over usually replaces or overlays the original speech, for example a translated narration. Audio description is added alongside the original soundtrack and only describes visual information, fitted into pauses so the original dialogue is still heard. A described version keeps all the original audio.

Can a text-to-speech voice read audio description?

Yes, synthetic voices are used for description by some producers, and many blind listeners are used to screen reader voices. The quality of the description script matters far more than the voice. Keep the voice clear and consistent, and check pronunciation of names and technical terms before publishing.

Do short social media clips need audio description?

If meaning lives in the visuals, such as text overlays or demonstrations, blind followers miss it. Many creators handle short clips by describing visuals in the caption text or voiceover, or by keeping key information in the narration. Check the accessibility features your platform offers, as they change over time.

Who writes audio description scripts?

Professional describers, sometimes called audio describers or description writers, script most broadcast and streaming description. For internal or educational video, trained staff can write description following published guidelines from accessibility organizations. Review by blind or low-vision users is the most reliable test of whether a description works.

Does a transcript count as audio description?

A plain transcript of speech does not, because it contains no visual information. A descriptive transcript, which adds visual descriptions to the speech and sound cues, can serve as a media alternative in some standards, but rules differ by level and context. Check the specific requirement your organization follows.