How to make video and audio accessible

Captions are text versions of speech and sound effects that appear at the same time. They help:

• People who are Deaf or have a hearing impairment
• People who find reading text easier than listening to audio
• People who want the sound off when watching a video. For example, if you're in a quiet place

Subtitles are different to captions - subtitles translate the video's language.

See more information on captions on the W3.org website.

When to use captions

Pre-recorded video 

Pre-recorded videos with informative audio must have captions. Informative audio includes:

• Speech
• Important sounds that help people understand the video, like laughter, sounds indicating something happening off-screen and music that is relevant to the video mood or topic

Pre-recorded videos don't need captions if:

• The video doesn't have audio
• The video has audio but it doesn't add information to the video. This type of audio is also known as background audio.

For example, this Swap2Save video does not need captions. This is because the audio - music and sound effects - is only background audio. It does not provide information to help you understand the video.

If your video does not need captions, we recommend adding the following text to the video description or close to where it is embedded on a webpage:

'Captions not needed: any audio in this video does not add meaning'.

Please note that videos that do not need captions, like this Swap2Save video, are unlikely to be accessible. They will only be accessible if an alternative version of the video is available that has audio description.

Live video 

Live video streams don't need captions.

How to write good captions

Your captions must accurately reflect the video audio. This means they must:

• Include all speech
• Include all important sounds (in brackets)
• Have accurate spelling and punctuation
• Appear roughly at the same time as the audio
• Be visible for at least one second
• Not hide any important visuals

Captions must also alert the user to change of speaker if:

• The identity of the speaker affects the meaning of the audio; and
• The visuals don't show who is speaking

If you're finding it difficult to decide what audio to include in your captions, remember that the main purpose of captions is to provide the information that you hear to people who cannot hear the audio.

For example, the captions in this Royal National Institute of Blind People (RNIB) video include background sounds and music lyrics as well as speech, because they add meaning to video.

How to add captions

You can add captions to your video as open or closed captions.

Open captions are built into your video when it's being created. They are always displayed and can't be turned off. They benefit people who need or like to use captions.

Closed captions are added to your video after it's been created. People can use video player settings to turn them on and off. Some video players also allow people to customise the appearance of closed captions. Being able to turn captions off or customise them benefits people who might find captions unhelpful or have a visual impairment.

Most video hosting sites, like YouTube and Vimeo, have the option to add closed captions when you upload your video.

Watch how to add captions when uploading a video on YouTube.

If someone else is adding your video to a hosting site, they might ask you to provide the closed captions text in a separate file. The file is usually called a subtitle, closed captions or transcript file.

• Tips for creating a transcript file for YouTube
• Subtitle and closed caption file types supported by YouTube

Colour contrast

When you add captions to your video, you must make sure that the text colour contrasts enough with the background colour. This will help people read your captions.

We recommend presenting captions as white text in a black box. This meets colour contrast requirements.

If you want to present your captions in a different way, you must check that the colours you use meet contrast requirements. Find out how to check colour contrast.

Auto-generated captions

Some hosting sites, like YouTube, add captions to videos automatically.

Auto-generated captions can be a starting point to help you add good captions to your video. But you must review and edit these captions as they are usually inaccurate and incomplete.

Follow our advice on how to write good captions to help you improve auto-generated captions. Google Support also explains how to edit captions on YouTube.