---
title: "Track input atom ('  in')"
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/track_input_atom
---

# Track input atom ('  in')

An atom that specifies how to use the input data.

## Overview

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:  |   |   |   |   |   |   |   |   |  ‡ Required atom.

## Topics

### Data fields

- [Size](quicktime-file-format/track_input_atom/size.md)
- [Type](quicktime-file-format/track_input_atom/type.md)
- [Atom ID](quicktime-file-format/track_input_atom/atom_id.md)
- [Reserved](quicktime-file-format/track_input_atom/reserved.md)
- [Child count](quicktime-file-format/track_input_atom/child_count.md)
- [Reserved](quicktime-file-format/track_input_atom/reserved_2.md)
- [Input type atom](quicktime-file-format/track_input_atom/input_type_atom.md)
- [Object ID atom](quicktime-file-format/track_input_atom/object_id_atom.md)

## See Also

### Atoms for track input

- [Track input map atom ('imap')](quicktime-file-format/track_input_map_atom.md)
- [Input type atom ('  ty')](quicktime-file-format/input_type_atom.md)
- [Object ID atom ('obid')](quicktime-file-format/object_id_atom.md)