isAuxiliaryContent
A media characteristic that indicates a track or media selection option includes content its author indicates is auxiliary to the asset’s presentation.
Declaration
static let isAuxiliaryContent: AVMediaCharacteristicDiscussion
An example of auxiliary content is audio commentary about the presentation.
The value of this characteristic is public.auxiliary-content.
For QuickTime movies and .m4v files, a media option has this characteristic only if the media’s author tags it that way, or if it belongs to an alternate track group that excludes its associated track from autoselection.