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Movie Atoms

This chapter provides a general introduction to QuickTime movie atoms, as well as specific details on the layout and usage of these atoms. Each atom type discussed in this chapter is shown with an accompanying illustration that contains offset information, followed by field descriptions.

This chapter is divided into the following major sections:

• “Overview of Movie Atoms” discusses QuickTime movie atoms, which act as containers for information that describes a movie’s data. A conceptual illustration is provided that shows the organization of a simple, one-track QuickTime movie. Profile atoms, color table atoms, and user data atoms are also discussed.

• “Track Atoms” describes track atoms, which define a single track of a movie. Track profile atoms, track user data atoms, and hint tracks are also discussed.

• “Media Atoms” discusses media atoms, which define a track’s movie data, such as the media type and media time scale.

• “Sample Atoms” discusses sample table atoms, which specify where media samples are located, their duration, and so on. The section also includes examples of how you use these atoms.

  Note: Media atoms and sample atoms do not contain actual sample data, such as video frames or audio samples. They contain metadata used to locate and interpret such samples.

• “Compressed Movie Resources” discusses compressed movie resources, in which a lossless compression algorithm is used to compress the contents of the movie atom, including any track, media, or sample atoms. The contents must be decompressed before the movie atom can be parsed.

• “Reference Movies” discusses movies that contain a reference movie atom (a list of references to alternate movies, as well as the criteria for selecting the correct movie from a list of alternates). Movie atoms that contain a reference movie atom do not necessarily contain track, media, or sample atoms.

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