Alternatives for audio and visual contentMust
Alternative delivery, such as subtitles, sign language, audio description and transcripts, must be provided with embedded media when available.
Some users may not be able to hear audible content. Some users may not be able to see visual content. Having an alternative delivery, in addition to the media that can be perceived, supports comprehension. Multiple delivery formats also help cognitively impaired users.
This guideline applies to all forms of audio and visual content, regardless of length or format, as appropriate for the content:
- Subtitles must be provided where feasible, when they were included with a pre-recorded broadcast, or if content is for public facing corporate communications, employment or suppliers;
- Audio described or sign language versions must be provided if they were included with an original broadcast;
- For interactive content, such as games, narrative and instructions must be available both visually and audibly, for example using subtitles;
- In addition to other alternative delivery, transcripts can be provided for all types of audio and visual content.
iOS provides support for multiple audio tracks (which can be used for audio description) and caption support using the standard video playback views and a supported codec. See the Multimedia Programming Guide for further details. Captions may not be available in full screen mode. Use the Apple Media player with closed or open captions and support audio description.
Android does not handle multiple audio tracks or captions automatically therefore developers must incorporate support for these features into their application using a codec supported by the Android MediaPlayer API or a custom player. Incorporate closed captions and audio description into a multimedia video. All BBC products should be using the Standard Media Player delivered via BUMP
Use a media player that supports captions/subtitles. Provide correctly labelled controls to turn on and off the captions/subtitles. Flash is not supported on many devices and thus HTML 5 based media players will likely need to be used to deliver captions and audio description via HTML.
There are several different options to deliver captions and audio descriptions, including different caption formats. The caption format may be dependent on the media player used. The audio description format can either by text synchronization (this is not currently supported), a secondary audio file, or a secondary video with an enhanced audio track.
The BBC Standard Media Player, delivered via BUMP, should be used for all bbc.co.uk embedded video or audio content.
For other interactive media use visible text and cues to support audio narrative or instructions, and ensure this is provided as text or as a text alternative so it can be spoken by screen readers.
The key aim will be to verify that:
- any audible content necessary for understanding is provided visually;
- and any visual content necessary for understanding is provided in a way that can be audible.
- Activate the app or webpage.
- Locate media.
- Determine if the media has audio content that contains important information - such as a spoken narrative.
- Check that any audible information necessary for understanding the media is also provided via subtitles/open or closed captions in conjunction and synchronized with the audio.
- Determine if the media has visual content that contains important information - such as a sign or new character entering.
- Check that any visual information necessary for understanding the media is also described as part of the audio or is provided through a separate track containing the audio descriptions and is synchronised with the video. This may be via a screen reader where appropriate.
The following checks must be true:
- Media provides subtitles/opened or closed captions that are synchronised with any audio content that contains important information;
- Visual content necessary for understanding the media is described using an audio which is synchronised with the video content (Video description), or where appropriate provides textual content for a screen reader.