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# Object ID atom ('obid')

An atom that identifies an object, such as a sprite within a sprite track, in a track input atom.

## Overview

If the input is operating on an object within the track (for example, a sprite within a sprite track), an object ID atom must be included in the track input atom to identify the object.

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/Object_ID_atom/Size)

A 32-bit integer that specifies the number of bytes in this object ID atom.

[`Type`](/documentation/quicktime-file-format/Object_ID_atom/Type)

A 32-bit integer that identifies the atom type.

[`Object ID`](/documentation/quicktime-file-format/Object_ID_atom/Object_ID)

A 32-bit integer identifying the object.


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