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# Track input map atoms

Atoms that define how data being sent to this track from its nonprimary sources is to be interpreted.

## Overview

Track input map atoms define how data being sent to this track from its nonprimary sources is to be interpreted. Track references of type `'ssrc'` define a track’s secondary data
sources. These sources provide additional data that is to be used when processing the track. Track input map atoms have an atom type value of `'imap'`.

## Topics

### Atoms for track input

[`Track input map atom ('imap')`](/documentation/quicktime-file-format/Track_input_map_atom)

An atom that defines how data being sent to this track from its nonprimary sources is to be interpreted.

[`Track input atom ('  in')`](/documentation/quicktime-file-format/Track_input_atom)

An atom that specifies how to use the input data.

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

An atom that specifies how to interpret track input data.

[`Object ID atom ('obid')`](/documentation/quicktime-file-format/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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