Captions, Transcripts, and Audio Descriptions

Captions

Accessible multimedia (visual and auditory content that is synchronized) must include captions—text versions of speech and other important audio content—allowing it to be accessible to people who can't hear all of the audio.

According to US government figures, one person in eight has some functional hearing limitation, and this number will increase as the average age of the population increases. Beyond people with disabilities, captioning helps people who only partially understand the language presented. Captions are also useful in noisy environments like airports, in quiet environments like libraries, and for multimodal learning.

All multimedia content with speech should have accessible captions that are:

• Synchronized to appear at approximately the same time as the corresponding audio.
• Equivalent to the spoken words and other audio information.
• Accessible, or readily available, to those who need it.

The most common type of captions are "Closed" captions, which can be turned on or off. Most countries require most pre-recorded and live television programs to be closed-captioned.

Closed captioning of most pre-recorded television programs is now a legal requirement in most countries. Most live broadcasts (such as news and sports events) and most pre-recorded programs now include closed captions that can be easily enabled and viewed on screen.

On broadcast television, the style and location of the captions depend on the caption decoder built into the viewer's television receiver or streaming device. In online or streaming video, the browser or video player determines how captions will be displayed. Many televisions and video players allow the user to customize caption size, color, font, and location on the screen.

Open captions include the same content as closed captions, but the captions are a permanent part of the video picture and cannot be turned off. The captions are visible to anybody viewing the video clip and give the media producer total control of the presentation. However, with open captions the viewer doesn't have the ability to customize the caption experience or turn the off.

Quality Captions

Accessible captions must do more than accurately reproduce spoken words. They also need to communicate meaningful audio information and be presented in a way that viewers can follow while watching a video.

When creating or reviewing captions, be sure to check that they:

• Accurately convey the dialogue. Check for missing or misspelled words, incorrect terminology, and punctuation errors.
• Identify speakers. Viewers should be able to identify who is speaking, especially when a speaker is offscreen.
• Include meaningful non-speech audio. Identify and represent sounds that provide meaning in a video including music, laughter or a door being slammed shut.
• Are synchronized and readable. Captions should appear with the corresponding video and remain on screen long enough to read. Break lines at natural points in phrases or sentences.
• Don’t cover essential information. Check to make sure that when displayed,the captions don’t cover important visual content in the video.

Automatic, computer-generated captions can be a useful place to start but should always be reviewed and corrected by someone who understands captioning best standards before being published. Paying for captions also doesn’t guarantee quality, be sure to evaluate video captions regardless of how they were produced.

We recommend reviewing captions in the player that your audience will use. Confirm that captions display correctly and for closed captions, that the method to turn them on or off is also accessible.

For more detailed guidance on captioning best practices and examples, see the DCMP Captioning Key and BBC Subtitle Guidelines. These resources provide helpful implementation guidance to provide highly accessible captioned videos.

Transcripts

For multimedia, a transcript can also help users who can neither hear the audio nor see the video. Beyond the spoken words, a transcript should include descriptions of important audio information (like laughter) and visual information (such as someone entering the room). Transcripts help deaf/blind users interact with content using refreshable Braille devices.

Transcripts also allow anyone that cannot access content from either web audio or video (or both) to read a text transcript instead. For most web video, both captions and a text transcript should be provided. For content that is audio only, a transcript will usually suffice—captions are not necessary for audio-only media like a podcast.

Transcripts make multimedia content searchable by search engines and users. Screen reader users also may also prefer a transcript over real-time audio, since most proficient screen reader users set their assistive technology to read at a rate much faster than natural human speech.

Audio Descriptions

Audio descriptions help users with visual disabilities perceive content that is presented only visually, and are necessary for WCAG 2 Level AA conformance. On television, this is often called Descriptive Video Service (DVS). Typically, a narrator describes the visual-only content in the multimedia. Audio descriptions can be provided with the primary video, or in another audio track, or via an alternate version of the video that includes audio descriptions.

Here's a short example of an audio description that you might recognize. Can you visualize what is being described?

Producing audio descriptions can be expensive and time-consuming. However, they are unnecessary if the audio already presents the necessary visual content. If a video displays a list of five important items, the items should be read aloud instead of the audio presenting, "As you can see, there are five important points". Instead of, "Click here and then here," the presenter should describe what is being clicked. This way, no separate audio description track is necessary.