To get a handle on how to support a subtitle format natively in CMML, it is important to determine the features common to all subtitle formats. These features can be categorised to the following types: Presentation and Semantic Features.

• Semantic Features: Semantic features of subtitles are the fundamental facets that are expected to be found in all subtitles to some degree. These include:
  • Subtitle text
  • Text type (subtitle, caption, transcript, karaoke)
  • Speaker or presenter
• Presentation Features: Presentation features of subtitles are the formatting and timing aspects of a subtitle designed to aid in the readability and understandability of the subtitles to the end user. The choice of presentation features and functionality can be heavily determined by the type of text subtitled and the intended audience.
  • Subtitle timing
  • Subtitle fonts
  • Subtitle colours and dynamic colouring (karaoke)
  • Justification of text
  • Text motion / marquee (scrolling text of a stock market ticker)