Function is_subtitle_adaptation

pub fn is_subtitle_adaptation(a: &&AdaptationSet) -> bool

Returns true if this AdaptationSet contains subtitle content.

For now, it contains subtitles if the @mimeType attribute is “text/vtt” (WebVTT) or “application/ttml+xml” or “application/x-sami” (SAMI). Further work needed to handle an Adaptation that contains a Representation with @contentType=“text” and @codecs=“stpp” or a subset like @codecs=“stpp.ttml.im1t” (fragmented TTML in an MP4 container) or @codecs=“wvtt” (fragmented VTTcue in an MP4 container).

The DVB-DASH specification also allows for closed captions for hearing impaired viewers in an AdaptationSet with Accessibility node having @SchemeIdUri = “urn:tva:metadata:cs:AudioPurposeCS:2007” and @value=2.