---
title: "Track atom ('trak')"
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/track_atom
---

# Track atom ('trak')

An atom that defines a single track of a movie.

## Overview

Overview Track atoms have an atom type value of 'trak'. The track atom requires a track header atom ('tkhd') and a media atom ('mdia'). Other child atoms are optional, and may include a track clipping atom ('clip'), a track matte atom ('matt'), an edit atom ('edts'), a track reference atom ('tref'), a track load settings atom ('load'), a track input map atom ('imap'), and a user data atom ('udta'). note: The track atom layout contains an optional track profile atom ‘prfl’. Track profile atoms are deprecated in the current version of QuickTime but may be present in existing QuickTime files. The inclusion here documents existing content containing profile atoms, they should not be used for new development. The layout of a track atom is as follows.  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

## Topics

### Data fields

- [Size](quicktime-file-format/track_atom/size.md)
- [Type](quicktime-file-format/track_atom/type.md)
- [Track profile atom](quicktime-file-format/track_atom/track_profile_atom.md)
- [Track header atom](quicktime-file-format/track_atom/track_header_atom.md)
- [Track aperture mode dimensions atom](quicktime-file-format/track_atom/track_aperture_mode_dimensions_atom.md)
- [Clipping atom](quicktime-file-format/track_atom/clipping_atom.md)
- [Track matte atom](quicktime-file-format/track_atom/track_matte_atom.md)
- [Edit atom](quicktime-file-format/track_atom/edit_atom.md)
- [Track reference atom](quicktime-file-format/track_atom/track_reference_atom.md)
- [Track exclude from autoselection atom](quicktime-file-format/track_atom/track_exclude_from_autoselection_atom.md)
- [Track load settings atom](quicktime-file-format/track_atom/track_load_settings_atom.md)
- [Track input map atom](quicktime-file-format/track_atom/track_input_map_atom.md)
- [Media atom](quicktime-file-format/track_atom/media_atom.md)
- [User-defined data atom](quicktime-file-format/track_atom/user-defined_data_atom.md)

## See Also

### Describing tracks

- [Track header atom ('tkhd')](quicktime-file-format/track_header_atom.md)
- [Track exclude from autoselection atom ('txas')](quicktime-file-format/track_exclude_from_autoselection_atom.md)
- [Track aperture mode dimension atoms](quicktime-file-format/track_aperture_mode_dimension_atoms.md)
- [Clipping atom ('clip')](quicktime-file-format/clipping_atom.md)
- [Clipping region atom ('crgn')](quicktime-file-format/clipping_region_atom.md)
- [Track matte atom ('matt')](quicktime-file-format/track_matte_atom.md)
- [Compressed matte atom ('kmat')](quicktime-file-format/compressed_matte_atom.md)
- [Edit atom ('edts')](quicktime-file-format/edit_atom.md)
- [Edit list atom ('elst')](quicktime-file-format/edit_list_atom.md)
- [Playing with edit lists](quicktime-file-format/playing_with_edit_lists.md)
- [Track load settings atom ('load')](quicktime-file-format/track_load_settings_atom.md)
- [Track reference atoms](quicktime-file-format/track_reference_atoms.md)
- [Track input map atoms](quicktime-file-format/track_input_map_atoms.md)