---
title: "Track header atom ('tkhd')"
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/track_header_atom
---

# Track header atom ('tkhd')

An atom that specifies the characteristics of a single track within a movie.

## Overview

Overview The track header atom specifies the characteristics of a single track within a movie. A track header atom contains a size field that specifies the number of bytes and a type field that indicates the format of the data (defined by the atom type 'tkhd'). The layout of a track header atom is as follows.  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  The track header atom contains the track characteristics for the track, including temporal, spatial, and volume information.

## Topics

### Data fields

- [Size](quicktime-file-format/track_header_atom/size.md)
- [Type](quicktime-file-format/track_header_atom/type.md)
- [Version](quicktime-file-format/track_header_atom/version.md)
- [Flags](quicktime-file-format/track_header_atom/flags.md)
- [Creation time](quicktime-file-format/track_header_atom/creation_time.md)
- [Modification time](quicktime-file-format/track_header_atom/modification_time.md)
- [Track ID](quicktime-file-format/track_header_atom/track_id.md)
- [Reserved](quicktime-file-format/track_header_atom/reserved.md)
- [Duration](quicktime-file-format/track_header_atom/duration.md)
- [Reserved](quicktime-file-format/track_header_atom/reserved_2.md)
- [Layer](quicktime-file-format/track_header_atom/layer.md)
- [Alternate group](quicktime-file-format/track_header_atom/alternate_group.md)
- [Volume](quicktime-file-format/track_header_atom/volume.md)
- [Reserved](quicktime-file-format/track_header_atom/reserved_3.md)
- [Matrix structure](quicktime-file-format/track_header_atom/matrix_structure.md)
- [Track width](quicktime-file-format/track_header_atom/track_width.md)
- [Track height](quicktime-file-format/track_header_atom/track_height.md)

## See Also

### Describing tracks

- [Track atom ('trak')](quicktime-file-format/track_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)