Adding Controls for QuickTime Caption and Audio Description Tracks

QuickTime movies with additional tracks for captions or audio descriptions give people with visual or auditory impairments the opportunity to access content that might otherwise be completely inaccessible. QuickTime Pro users can toggle tracks on and off to meet their needs. Unfortunately, most QuickTime users do not buy the 'Pro' version, and unless they do, the ability to toggle tracks on and off is unavailable. These users view the presentation with which ever tracks the author enabled at the time of the last save.

Two scenarios highlight potential problems with this situation:

Scenario 1: A blind user links to a video which contains audio descriptions, but the track containing the audio descriptions was off when the movie was saved. The developer intentionally saved the movie with this track off because he was concerned that the audio descriptions would be distracting to sighted viewers. The blind user may not own QuickTime Pro to turn the needed track on, or even if he does, the steps necessary to enable the track require that the user use the mouse to select the correct track.

Scenario 2: A sighted user links to a video which was saved with a caption track on. The user wishes to turn the track off. This is an easy 3-step task if the user has QuickTime Pro, but impossible otherwise.

Fortunately, there is a solution. Using software such as LiveStage from Totally Hip Software, developers can create control elements to insert into the QuickTime movie which allow the viewer to turn tracks on or off, even if they do not own QuickTime Pro. You can even associate keyboard commands with the control elements so users can turn tracks on or off without using the mouse. The image below shows a QuickTime movie with control elements for toggling captions and audio-descriptions on and off.

A captioned QuickTime movie, with control elements

Adding Control Elements

To add control elements to a QuickTime movie, you will either need the following:

QuickTime Pro
control elements (download ours or make your own)
A QuickTime movie

For this brief tutorial, we will assume that you are using our control elements. Follow the steps below to add the elements to your QuickTime movie:

Open your QuickTime movie
Rename any caption track "captions" and rename any audio description track "audiodesc".
Find the control element that you will use, and open it in QuickTime.
Choose 'Copy' from the 'Edit' menu.
Click once on the window for your captioned or described movie
Hold the 'Option' and 'Shift' keys on the keyboard ('Control', 'Alt', and 'Shift' in Windows), select 'Add Scaled' from the 'Edit' menu.
You will need to reposition the control element. Since the area of the element is small, it is difficult to click an area that allows the element to be dragged rather than resized. For each control element, there are two layers that need to be moved -- one layer has the text, and the other has the actual 'hot spots'. Make sure to move both.

Download Control Elements

Download control elements from NCAM's FTP server.

cc_on_at_start.mov -- Control element for use if captions are on by default.
cc_off_at_start.mov -- Control element for use if captions are off by default.
ad_on_at_start.mov -- Control element for use if audio descriptions are on by default.
ad_off_at_start.mov -- Control element for use if audio descriptions are off by default.

At this time, none of the downloadable control elements have keystrokes associated with them.