---
title: Atom ID
framework: quicktime-file-format
role: symbol
role_heading: Data field
path: quicktime-file-format/track_input_atom/atom_id
---

# Atom ID

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

## Overview

Overview The value of this field corresponds to the index of the secondary input in the track reference atom. That is, the first secondary input corresponds to the track input atom with an atom ID value of 1; the second to the track input atom with an atom ID of 2, and so on.

## See Also

### Data fields

- [Size](quicktime-file-format/track_input_atom/size.md)
- [Type](quicktime-file-format/track_input_atom/type.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)