How to make video and audio accessible

This guide explains how to create accessible video and audio. Check who is responsible for making web content accessible.  

Find out more about accessibility and why digital content needs to be accessible. 

Plan accessibility into your project 

Read this guide before creating your video or audio. 
 
It is easier to integrate accessibility into your video or audio before production. After production, it is harder, takes longer and can be more expensive. 

Get video and audio project management advice. 

Need help? 

How Norfolk County Council (NCC) staff can get help to make sure their content is accessible . 

NCC staff should contact the Communications team to publish video or audio on a third-party hosting site such as YouTube. 

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.

Video audio must include all important information shown in the video visuals.  

This helps people who can hear the audio but find it difficult to access information shown in the video visuals. For example, people who: 

• Have a vision impairment 
• Find audio easier to understand than text or other visuals 
• Find it difficult to identify which visuals are important and which they can ignore 

What to include in your video audio 

Your video audio should include important information shown by visual content like: 

• Text 
• Demonstrations that show people how to do something 
• Events and actions taking place 
• Scenery 
• Charts and diagrams 

If you're not sure whether visual content in your video needs to be described in the audio, think about why you included it in your video. If you included it to communicate something to your audience, then you need to mention this in the audio.  

The audio doesn't necessarily have to describe exactly what's happening in the visuals or read out visible text word for word. But it must include the important information the visuals communicate. 

Example one 

This still from the Elective Home Education video shows text and illustrations. 

• The 'Elective Home Education' text tells us what the video is about. This means that the audio must mention that this is what the video is about too. The narrator says 'Elective Home Education' 
• The illustrations don't communicate any important information. This means they don't need to be mentioned in the audio 

Example two 

This still from the Elective Home Education video shows a web page. 

• The web page is included in the video to show that information about services to home educators is on the website. This means that the audio must mention this too. The narrator says 'Further information can be found on the Service to Home Educators web page' 
• The web page includes lots of text information. This is only shown briefly, indicating that viewers aren't expected to read it. This means the text information doesn't need to be mentioned in the audio 

Example three 

This still from the Flourish Pledge video shows footage of a welcome display at a childcare setting. 

• The footage is included in the video to show it is about an outdoor childcare setting. This means that the audio must mention it too. The speaker says it is an 'all outdoor environment' with 'children from 6 months old all the way through to 8 years old playing together in the woods' 
• The footage also shows other information, like flags and the word 'hello' in different languages on the display. This information isn't relevant to the subject matter of the video, so it doesn't need to be mentioned in the audio 

Exceptions 

There are some instances when you don't need to include visual information in your audio: 

• Videos that don't have an audio track (video-only) can either have an audio description or a descriptive transcript
• Live video streams don't need audio description 

How to make sure your video has good audio description 

There are three main ways you can make sure your video has good audio description. You can choose the one you find easiest. 

Option 1: include description in your main audio track 

When you're planning your video, make sure that the audio script includes all the important information that you're planning to show in your visuals. 

This Marathon Mates video is an example of a video with good integrated audio description: 

• The text shown in the video is included in the audio 
• The appearance of the logo at the end of the video is included in the audio 
• The other visuals aren't described in the audio because they don't communicate any extra information 

Option 2: add an additional audio track 

Alternatively, you can add an additional audio description (AD) track to your video. This is additional audio commentary that explains what's happening in the video. 

Most video players let you add this as an alternative audio track, so users can turn it on if they need it: 

• How to add an audio description track in YouTube 
• How to add multiple audio tracks in Vimeo 
• How to use alternative video audio tracks in Clipchamp or SharePoint 

You can use W3C's advice to help you write and record your audio description track. 

Watch the audio described version of RNIB's Before You Ask video to hear an example of a good audio description track. 

Option 3: create an additional video 

Alternatively, you can create a second version of your video that has audio description. This is additional audio commentary that explains what's happening in the video. 

You can use W3C's advice to help you write and record your audio description track. 

Then, publish both versions of the video. You must make it clear how they are different to help users pick the video to watch that best suits them. For example:  

• The RNIB include 'audio described' in the names of their videos with audio description 
• We have published the Before You Ask video on this page below and provided a text link to the audio described version underneath it  

Watch the audio described version of RNIB's Before You Ask video 

A transcript is a text version of a video, available alongside it. 

A transcript should include all the informative audio in your video. This means speech and any other important sounds that help people understand the video - just like video captions. 

Transcripts can help people who: 

• Have a hearing impairment 
• Find text easier to understand than audio 
• Don't have time to watch the video and find reading the transcript quicker 
• Want to check if the video is relevant to them before watching it 

A descriptive transcript is a transcript that describes the video visuals as well as the audio. Descriptive transcripts can particularly help people with vision impairments. 

Example transcript

The Elective Home Education video on YouTube has an interactive transcript.

You can access the transcript by using the 'Show transcript' button in the video description. 

Example descriptive transcript

The W3C video captions video is published on the W3C website. 

The link below the video takes you to a descriptive transcript published in a table further down the web page. 

When and how to use a transcript 

Providing a transcript is an optional way to make your video more accessible. 

Most video players, like YouTube, can create an interactive transcript for your video based on the captions. You must review and edit automatically generated transcripts. This is because they are usually inaccurate and incomplete. 

Alternatively, you need to transcribe your audio. This means putting the informative audio into text. Follow the W3C guide on transcribing audio to text.  

If you're creating a descriptive transcript, you'll need to add descriptions of the video visuals too. 

If you're embedding your video on a web page, you can publish the transcript as web page text. Put the transcript, or a link to it, close to the video to make it easy to find. 

Colour contrast is the difference between two colours. Colours with good contrast stand out from each other. Colours with poor contrast look similar and can be difficult to tell apart.

Factors like tiredness, screen displays, light levels, age and visual impairments can all affect how difficult it is to tell colours with poor contrast apart.

Using good colour contrast in your video means more people can watch and understand it.

Go to YouTube to watch a video on the importance of colour contrast.

What to check

Colour contrast ratio measures the difference between two colours using numbers. You should use colour contrast ratio to check that colour combinations in certain parts of your video have accessible contrast.

Text

Any text in your video must have accessible contrast. This includes captions for video.

Normal text is unbolded text under 18 point/24px and bolded text under 14 point/18.5px. Normal text colour and the colour behind it must have a colour contrast ratio of at least 4.5:1.

Large text is unbolded text that is 18 point/24px and above and bolded text that is 14 point/18.5px and above. Large text colour and the colour behind it must have a colour contrast ratio of at least 3:1.

Links

Links include linked text and images. Link colour and the colour behind it must have a colour contrast ratio of at least 3:1.

Non-text content in informative images

Colours that are next to each other in informative images must have a colour contrast ratio of at least 3:1.

For example, if you had a pie chart in your video, you'd need to make sure that:

• The pie chart's segment colours and the video's background colour have good colour contrast
• The colours of segments next to each other have good colour contrast

Informative images include information that helps people understand your video. For example, charts, graphs, diagrams and visual instructions.

Decorative images and logos do not have to have accessible colour contrast.

How to check colour contrast

WebAIM's Contrast Checker helps you check how accessible any colour combination is. To use this tool, you'll need to know the hex codes for your colours. A hex code is a hash (#) followed by 6 numbers that references a specific colour.

To get a colour's hex code, take a screenshot of the colour you're checking in the video. Then upload it to an online image colour picker, like the Image Color Picker tool, to get the hex code.

How to correct colour contrast

If you find that any colour combinations you use don't have accessible contrast, you must edit your video and fix them. Try these techniques:

Change one or both colours

If you need to improve text or text link colour contrast, try changing the text colour, the background colour, or both.

If one colour is very light, try making the other colour darker. For example, try changing red text on a white background to a darker red.

Add a thick border or white space between the colours

If you're trying to make sure non-text content in an informative image has good colour contrast, try adding a thick border or white space between colours.

For example, if you're trying to make sure that all segments in a pie chart have good colour contrast with the colour of the segments next to them, try adding a thick border between each segment. Or you could separate them all using white space.

Then, you just need to make sure that all the segment colours have good contrast with the border colour or white space. For example, you could make all the segment colours light colours and the border colour a dark colour.

Read more

• The Who Can Use tool shows you how colour contrast can affect different people with visual impairments
• Minimum colour contrast ratio for text (Web Content Accessibility Guidelines (WCAG) website)
• Minimum colour contrast ratio for non-text elements (WCAG website)

Audio-only content includes podcasts and recordings of poetry, speeches and interviews. Unlike video, it does not have any visual content.

Audio-only content must have a basic transcript. This is a text version of the speech and non-speech audio information that people need to understand the content.

Providing a basic transcript helps people who can't or find it difficult to hear audio. It also helps people who find it difficult to process audio information and prefer to read it.

How to add a basic transcript

To create your basic transcript, you need to transcribe your audio. This means putting the informative audio into text. Follow the W3C guide on transcribing audio to text.

Once you have created your basic transcript, you should make it easy for people to find.

If you're embedding your audio-only content on a web page, we recommend publishing the descriptive transcript directly underneath the video. Or you can link to it instead.

For example, there is a transcript link on each episode page on the This American Life podcast website. This link takes the user to a page where the basic transcript text is published as web page text.

Background audio is sound that doesn't add information to your video or audio-only content. It's audio you wouldn't feature in your video captions or basic transcript for audio-only content.

Informative audio is sound that does add information to your video or audio-only content. Informative audio includes:

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

If your audio includes background audio, you must make sure it doesn't make it difficult to hear and understand the informative audio:

• Make sure that background audio is at least 20 decibels (about four times) quieter than informative audio; or
• Remove background audio 

This will help everyone listening to your audio. It will especially help people who find it difficult to understand speech or distinguish between informative and background audio.

Examples of flashing in video include footage of strobe lighting or lightening in a thunderstorm.

We recommend avoiding including flashing visuals in your video.

This is because they can cause people to have seizures or feel dizzy, nauseous or disorientated.

If you still want to include flashes in your video, you must make sure that there aren't more than three flashes per second.

You should also keep flashes small and make sure they have low colour contrast with other content. This can help to reduce risk to viewers.