---
title: "Metadata handler atom ('hdlr')"
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/metadata_handler_atom
---

# Metadata handler atom ('hdlr')

An atom that defines the structure used for all types of metadata stored within the metadata atom.

## Mentioned in

QuickTime File Format change log

## Overview

Overview The metadata handler atom is a full atom with an atom type of ‘hdlr’. It defines the structure used for all types of metadata stored within the metadata atom. note: A reader parsing a metadata atom should confirm the handler type in the metadata handler atom is ‘mdta’ before interpreting any other structures in the metadata atom according to the specification presented here. If the handler type is not ‘mdta’, the interpretation is defined by another specification.

## Topics

### Data fields

- [Size](quicktime-file-format/metadata_handler_atom/size.md)
- [Type](quicktime-file-format/metadata_handler_atom/type.md)
- [Version](quicktime-file-format/metadata_handler_atom/version.md)
- [Flags](quicktime-file-format/metadata_handler_atom/flags.md)
- [Predefined](quicktime-file-format/metadata_handler_atom/predefined.md)
- [Handler type](quicktime-file-format/metadata_handler_atom/handler_type.md)
- [Reserved](quicktime-file-format/metadata_handler_atom/reserved.md)
- [Name](quicktime-file-format/metadata_handler_atom/name.md)

## See Also

### Metadata structure

- [Metadata atom ('meta')](quicktime-file-format/metadata_atom.md)
- [Metadata header atom ('mhdr')](quicktime-file-format/metadata_header_atom.md)