Inside Macintosh: QuickTime /

Chapter 4 - Movie Resource Formats / Overview of the Movie Resource Atom

Track Matte Atoms

Track matte atoms specify the mattes for tracks. (A track matte is a pixel map that defines the blending of visual track data. See the chapter "Movie Toolbox" in this book for details.) Figure 4-14 shows the layout of track matte atoms.

Figure 4-14 The layout of a track matte atom

You define a track matte atom by specifying these elements:

• Size. A long integer that specifies that number of bytes in this track matte atom.
• Type. A long integer that specifies the type of this track matte atom (defined by the 'matt' atom type).
• Compressed matte atom. The compressed matte atom, which is described in the next section.