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# Track matte atom ('matt')

An atom you use to visually blend the track’s image when it is displayed.

## Overview

Track matte atoms are used to visually blend the track’s image when it is displayed.

Track matte atoms have an atom type value of `'matt'`.

The layout of a track matte atom is as follows.

|Track matte atom                                                                                   |Bytes   |
|---------------------------------------------------------------------------------------------------|--------|
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_matte_atom/Size``                 |4       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_matte_atom/Type``                 |4       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_matte_atom/Compressed_matte_atom``|Variable|

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/Track_matte_atom/Size)

A 32-bit integer that specifies the number of bytes in this track matte atom.

[`Type`](/documentation/quicktime-file-format/Track_matte_atom/Type)

A 32-bit integer that identifies the atom type.

[`Compressed matte atom`](/documentation/quicktime-file-format/Track_matte_atom/Compressed_matte_atom)

An atom that specifies the image description structure and the matte data associated with a particular matte atom.


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