Have you ever wanted to watch a live event but couldn't find your headphones,                 so you turned on the captions? Or maybe you didn't quite catch the last few                 talking points from your favourite podcast, so you decided to read the                 transcript instead? If so, you probably understand the importance and                 convenience of having alternative ways to access audio and video content.

While your role at your company or organization may not require you to create                 audio and video content directly, it's important to know the basics of                 accessibility requirements for media.                 This knowledge will help you design and build the appropriate layouts and                 features to accommodate users with different environmental and sensory needs,                 such as the millions of people with hearing loss or visual impairment                 worldwide.

Alternative media types

Alternative media types were developed to support the media needs of people                 with disabilities. This gives people additional formats to choose from when                 accessing audio and video content.

The alternative media types you must include                 with your media files depend on:

                
• The type of media you are supporting—audio-only, video-only, or video                 with audio (multimedia) formats
                
• Whether the media is live or pre-recorded
                
• The version and level of WCAG compliance you are targeting
                
• Any additional media-related user needs
                

To create accessible audio and video content                 for websites and apps, there are four main types of alternative media types:                 captions, transcripts,                 audio descriptions, and                 sign language interpretation.

Captions

One of the most widely used alternative media types are                 captions. Captions are written                 text synchronized with multimedia content for people who can't hear or                 understand spoken words. They are presented in the same language as the main                 audio track and include important non-speech information, such as sound                 effects, background noises, and essential music.

Captions benefit people who are deaf, hard of hearing, or have cognitive                 disabilities, but are useful to many other people as well.

Captions come in two forms—open or closed.

                
• Closed captions (CC) are text on top of a video that can be turned on or off                 by the viewer and, depending on the media player, styled in a way that fits                 the user's needs.
                
• Open captions (OC) are text burned into the video and cannot be turned off or                 styled differently.
                

One method might be preferable, depending on the situation or how the                 multimedia will be consumed.

People often confuse captions with subtitles, but they aren't synonymous. Both                 are text synchronized with multimedia content, often appearing at the bottom of                 the media. Captions can be thought of as a transcription of dialogue and other                 essential sounds for people with disabilities. Subtitles are visual text for                 people who can hear the audio track but may not understand what was said, such                 as when watching a foreign language film.

                                    

                  

Compare screenshots from this video, with and without captions.

                                 

                  

                   

                 

                                    

                 

                                    

                

                  

                                  

Transcripts

Close cousins to captions,                 transcripts are detailed,                 text-based documents that capture all essential words, sounds, and important                 visual information in your media. Transcripts primarily help people who are                 hard of hearing or deaf, and descriptive transcripts help people who are                 deafblind.

Transcripts are also useful for people with cognitive disabilities or people                 who want to review the content at their speed.

While transcripts are typically more detailed than captions, they are very                 similar in format and purpose. They are so similar that many people first add                 captions to their media, export them and then use them as the foundation of                 their transcripts. Repurposing your captions to build your transcripts saves                 time versus creating everything from scratch.

Search bots can't access your captions but can crawl your text transcripts.                 When you include transcripts with your media files, your search engine                 optimization gets a boost. It's one of those rare exceptions when                 duplicate content isn't confusing to users or penalized by search engine                 algorithms.

Every media player handles transcripts differently. Some providers may                 not have that functionality built into their media player, and even when they                 do, some users may not be able to access the transcript interface. You can                 ensure you've made your transcript available to all users by:

                
• Including the transcript text directly in context, on the page with the                 embedded video.
                
• Adding a link to an accessible PDF containing the transcript.
                
• Linking out to the copy on another page.
                
• Including a link to the transcript, wherever it lives, within the video                 description on whatever media player platform you've used (such as YouTube or                 Vimeo).
                

For example, visit YouTube to watch Password Problems? | There's no place like Chrome and review an example of a transcript.

                                                  

Audio descriptions

Another alternative media used to support people with disabilities is                 audio description. This type                 of alternative media utilizes a narrator to explain important visual                 information to people who can't see the visual content. These descriptions                 include nonverbal information such as facial expressions, unspoken actions, and                 the background environment in video-only and multimedia content.

Sometimes audio descriptions need to be very detailed due to the large amount                 of information that needs to be shared with the viewer. If there aren't enough                 natural pauses in the video for audio descriptions, extended audio descriptions                 are used. In extended audio descriptions, a video will pause to give a narrator                 enough time to convey all the information in the media before playing the rest                 of the video.

Audio descriptions and extended audio descriptions help people who are blind or                 have low vision, but could help people with some cognitive disorders as well.

Sign language interpretation

Another major alternative media type you may encounter is sign language                 interpretation, where                 an interpreter narrates the auditory portion of the audio-only or multimedia                 content using sign language. This is very important for many people who are                 deaf, as sign language is their first and most fluent language.

Sign language interpretation is often more expressive and detailed than writing                 documents, providing a much richer experience than captions or transcripts                 alone.

That said, sign language interpretation can be time-consuming and                 cost-prohibitive to many organizations. And even if you have the time and                 budget to add sign language interpretation to your media, there are                 over 300 different sign languages                 worldwide. Adding one sign language interpretation to your media wouldn't be                 enough to support a global audience.