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  "title" : "Track input atom ('  in')"
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# Track input atom ('  in')

An atom that specifies how to use the input data.

## Overview

The track input atom may contain two other types of atoms: input type atoms and object ID atoms. The input type atom is required; it specifies how the data is to be interpreted.

The track input atom layout is as follows:

|Track input atom                                                                              |Bytes|
|----------------------------------------------------------------------------------------------|-----|
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Size``            |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Type`` = `' in'`  |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Atom_ID``         |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Reserved``        |2    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Child_count``     |2    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Reserved_2``      |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Input_type_atom``‡|12   |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Track_input_atom/Object_ID_atom``  |12   |

‡ Required atom.

## Topics

### Data fields

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

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

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

A 32-bit integer that identifies the atom type.

[`Atom ID`](/documentation/quicktime-file-format/Track_input_atom/Atom_ID)

A 32-bit integer relating this track input atom to its secondary input.

[`Reserved`](/documentation/quicktime-file-format/Track_input_atom/Reserved)

A 16-bit integer.

[`Child count`](/documentation/quicktime-file-format/Track_input_atom/Child_count)

A 16-bit integer specifying the number of child atoms in this atom.

[`Reserved`](/documentation/quicktime-file-format/Track_input_atom/Reserved_2)

A 32-bit integer.

[`Input type atom`](/documentation/quicktime-file-format/Track_input_atom/Input_type_atom)

An atom that specifies how to interpret track input data.

[`Object ID atom`](/documentation/quicktime-file-format/Track_input_atom/Object_ID_atom)

An atom that identifies an object, such as a sprite within a sprite track, in a track input atom.


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