Audio and Video
Allow users to control media playback
User control is an important aspect of universal usability. Users must be able to control their environment and to make decisions about what happens on a Web page, and when. This holds true for audio and video content. Given the demands that these elements place on users, audio and video should not appear within the content of a standard Web page. Loading an audio or video file should happen only when the user elects to access the file by clicking on a link. As discussed above, access to video and audio should come with multiple options so users can choose the size and format that best suit their needs.
In addition to controlling when to load media files, users must be in control of media playback. Web pages containing audio and video that is set to play automatically can cause usability problems. For example, some Web pages contain background music that plays automatically when the page is loaded. Imagine accessing a page with background music in a public setting, such as the library, or trying to make sense of it using a screen reader. Without a way to control playback—to pause or control the volume setting—users may be forced to leave the page to regain control of their environment. As with the choice to load media elements, the choice to play audio or video should always be user-driven. Present media elements with playback controls (Figure 12.6). Do not automatically play media; instead, wait for the user to activate the play button.
Figure 12.6: Media must always display with controls that allow users to control media playback. Here, the Real interface used on the POV site allows users to control playback, volume, and toggle captions display. www.pbs.org/pov