---
title: Tween sample data
framework: quicktime-file-format
role: article
role_heading: Article
path: quicktime-file-format/tween_sample_data
---

# Tween sample data

## Overview

Overview Tween sample data is stored in QT atom structures. At the root level, there are one or more tween entry atoms; these atoms have an atom type value of 'twen'. Each tween entry atom completely describes one interpolation operation. These atoms should be consecutively numbered starting at 1, using the atom ID field. Each tween entry atom contains several more atoms that describe how to perform the interpolation. The atom ID field in each of these atoms must be set to 1. The following table shows all currently defined tween types. All tween types are currently supported using linear interpolation.  |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  |  Each tween type is distinguished from other types by these characteristics: Input values or structures of a particular type A particular number of input values or structures (most often one or two) Output values or structures of a particular type A particular algorithm used to derive the output values Tween operations for each tween type are performed by a tween component that is specific to that type or, for a number of tween types that are native to QuickTime, by QuickTime itself. Movies and applications that use tweening do not need to specify the tween component to use; QuickTime identifies a tween type by its tween type identifier and automatically routes its data to the correct tween component or to QuickTime. When a movie contains a tween track, the tween media handler invokes the necessary component (or built-in QuickTime code) for tween operations and delivers the results to another media handler. The receiving media handler can then use the values it receives to modify its playback. For example, the data in a tween track can be used to alter the volume of a sound track. Tweening can also be used outside of movies by applications or other software that can use the values it generates.

## See Also

### Storing tween media

- [Tween sample description](quicktime-file-format/tween_sample_description.md)
- [Tween type categories](quicktime-file-format/tween_type_categories.md)
- [Tween QT atom container](quicktime-file-format/tween_qt_atom_container.md)