Overview: Track selection and accessibility

Subtitle selection combines track metadata, language preferences and accessibility needs with the available playback choices.

A default flag, a preferred language and a forced passage describe different reasons to show subtitles. SDH content serves another accessibility purpose. These topics explain how to identify the kind of track the viewer wants before interpreting the server or app's final selection.

• Subtitle track selection
  Subtitle track selection chooses a content track or caption service using language, role, user policy and any explicit or remembered choice.

• Subtitle language preferences
  Subtitle language preferences guide selection through language identifiers, script/region distinctions and the subtitle content role required for viewing.

• Forced subtitles
  Forced subtitle metadata identifies selected content intended to be shown in a viewing context and is distinct from permanent subtitle pixels.

• Subtitles for the deaf and hard of hearing (SDH)
  SDH subtitles include dialogue and relevant speaker, music and sound information for viewers who cannot rely on the soundtrack.