# Video and audio 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 favorite 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](https://www.w3.org/WAI/WCAG21/Understanding/time-based-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](https://www.w3.org/WAI/media/av/planning/#wcag-standard) 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](https://www.w3.org/WAI/media/av/) for websites and apps, there are four main types of alternative media types: [captions](#captions), [transcripts](#transcripts), [audio descriptions](#audio-descriptions), and [sign language interpretation](#sign-language-interpretation). ## Captions One of the most widely used alternative media types are [captions](https://www.w3.org/WAI/media/av/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. There are some geographical differences in what are considered captions and subtitles, so be sure to check the terminology in your location.
Features Subtitles Closed captions Open captions
Visual text matches audio track No Yes Yes
Includes essential background sounds No Yes Yes
Ability to toggle on/off Yes Yes No
https://www.youtube.com/watch?v=pXc_w49fsmI
Check out an example of captions in this video, Google — A CODA Story. Toggle the CC button to On to see the closed captions on this video.
Compare screenshots from this video, with and without captions.
*Video with captions.*
*Video without captions.*
## Transcripts Close cousins to captions, [transcripts](https://www.w3.org/WAI/media/av/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 for people who want to review the content at their own 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 in a different way. 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_](https://www.youtube.com/watch?v=SlGuvC5nnTA) and review an example of a transcript.
*Video on YouTube with Transcript in the right panel. The steps to access the transcript are highlighted in blue.*
Under the video title, click ... and select Show transcript from the dropdown menu. The transcripts will show up to the right or bottom of the video, depending on your screen size.
## Audio descriptions Another alternative media used to support people with disabilities is [audio description](https://www.w3.org/WAI/media/av/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.
https://www.youtube.com/watch?v=fNq5jWyEeWo
Here's an example of an illustrated video with an audio description, titled [Audio Described] Get started with Lookout from Google | Android.
## Sign language interpretation Another major alternative media type you may encounter is [sign language interpretation](https://www.w3.org/WAI/media/av/sign-languages/), 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 written 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](https://en.wikipedia.org/wiki/List_of_sign_languages) worldwide. Adding one sign language interpretation to your media wouldn't be enough to support a global audience.
https://www.youtube.com/watch?v=MbHuSHGZf5U
See how sign language interpreters narrated the story of Google sustainability in the video Google Presents: Search On '22.