---
title: Track atoms
framework: quicktime-file-format
role: collectionGroup
role_heading: API Collection
path: quicktime-file-format/track_atoms
---

# Track atoms

Atoms that define a single track of a movie.

## Overview

Overview Track atoms define a single track of a movie. A movie may consist of one or more tracks. Each track is independent of the other tracks in the movie and carries its own temporal and spatial information. Each track atom contains its associated media atom. Tracks are used specifically for the following purposes: To contain media data references and descriptions (media tracks). To contain modifier tracks (tweens, and so forth). To contain packetization information for streaming protocols (hint tracks). Hint tracks may contain references to media sample data or copies of media sample data. For more information about hint tracks, refer to Hint media. note: A QuickTime movie cannot consist solely of hint tracks or modifier tracks; there must be at least one media track. Furthermore, media tracks cannot be deleted from a hinted movie, even if the hint tracks contain copies of the media sample data—in addition to the hint tracks, the entire unhinted movie must remain.

## Topics

### Describing tracks

- [Track atom ('trak')](quicktime-file-format/track_atom.md)
- [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)

## See Also

### Movies

- [Movie atoms](quicktime-file-format/movie_atoms.md)
- [Media atoms](quicktime-file-format/media_atoms.md)
- [Sample atoms](quicktime-file-format/sample_atoms.md)
- [Structuring movie data and features](quicktime-file-format/structuring_movie_data_and_features.md)