---
title: Key_size
framework: quicktime-file-format
role: symbol
role_heading: Data field
path: quicktime-file-format/metadata_item_keys_atom/key_size
---

# Key_size

A 32-bit integer indicating the size of the entire structure containing a key definition.

## Overview

Overview The key_size = sizeof(key_size) + sizeof(key_namespace) + sizeof(key_value). Since key_size and key_namespace are both 32 bit integers, together they have a size of 8 bytes. Hence, the key_value structure will be equal to key_size - 8.

## See Also

### Data fields

- [Size](quicktime-file-format/metadata_item_keys_atom/size.md)
- [Type](quicktime-file-format/metadata_item_keys_atom/type.md)
- [Version](quicktime-file-format/metadata_item_keys_atom/version.md)
- [Flags](quicktime-file-format/metadata_item_keys_atom/flags.md)
- [Entry_count](quicktime-file-format/metadata_item_keys_atom/entry_count.md)
- [Key_namespace](quicktime-file-format/metadata_item_keys_atom/key_namespace.md)
- [Key_value[Key_size-8]](quicktime-file-format/metadata_item_keys_atom/key_value_key_size-8.md)