Video for VI Learners
Extending existing video materials
What Audio Subtitling is and when it is useful
Audio subtitling (or Audio Description)
is like a Greek Chorus. A narrator uses any gaps in the main action dialogue
to describe what is going on. The narrator is chosen so that his or her
voice is easily distinguishable from the actors, commentators, or narrators
in the video itself.
View video without (6.4 M) and
with (6.3 M) Audio Description
Audio subtitling is of most use to blind video audiences, although the
cues given can help less visually impaired viewers too. Since its increasing
success in American public service broadcasting, the technique has spread
beyond video and TV. For example, audio subtitlers are being employed
in theatre productions, using a closed loop audio transmission system
like those set up for hard-of-hearing audiences.
How it works
Like text subtitles, audio subtitling on linear formats like VHS comes
in two flavours - open and closed.
- Open audio subtitles are mixed into the overall soundtrack. Once there,
the whole audience has to listen to both action and commentary.
- Closed subtitles are carried on a separate track, and can be switched
off when not needed. So a video for general
consumption can have a closed track which a VI learner can use for private
- Non-linear and digital formats
are much more flexible.
What you need to add audio subtitles
If you have access to editing suites, so much the better. Synchronisation
and merging of your new material with the old will be much easier.
The most important need is for a good script. Creating one is a non-trivial
problem, and you will need all the advice you can get. We have an introductory
checklist, but we urge you to read more before you start. The Audio
Subtitlers have been refining their art for a while now, and if your computer
is linked to the Internet then a helpful Web site is The Audio Description
Home Page. The RNIB also have good advice to offer, and we have links
to these and other resources in the Refernces section.