---
title: Extension atoms
framework: quicktime-file-format
role: symbol
role_heading: Data field
path: quicktime-file-format/sidecompressionparam_atom/extension_atoms
---

# Extension atoms

Atoms containing the necessary out-of-band decompression parameters for the sound decompressor.

## Overview

Overview For MPEG-4 audio ('mp4a'), this includes elementary stream descriptor ('esds'), format ('frma'), and terminator atoms.

## See Also

### Data fields

- [Size](quicktime-file-format/sidecompressionparam_atom/size.md)
- [Type](quicktime-file-format/sidecompressionparam_atom/type.md)