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# MPEG-4 elementary stream descriptor atom ('esds')

A required extension to the video sample description for MPEG-4 video.

## Overview

This atom contains an MPEG-4 elementary stream descriptor atom. This is a required extension to the video sample description for MPEG-4 video. This extension appears in video sample descriptions only when the codec type is `'mp4v'`.

> Note: The elementary stream descriptor which this atom contains is defined in the MPEG-4 specification ISO/IEC FDIS 14496-1.

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/MPEG-4_elementary_stream_descriptor_atom/Size)

An unsigned 32-bit integer holding the size of the elementary stream descriptor atom.

[`Type`](/documentation/quicktime-file-format/MPEG-4_elementary_stream_descriptor_atom/Type)

An unsigned 32-bit field.

[`Version`](/documentation/quicktime-file-format/MPEG-4_elementary_stream_descriptor_atom/Version)

An unsigned 8-bit integer set to zero.

[`Flags`](/documentation/quicktime-file-format/MPEG-4_elementary_stream_descriptor_atom/Flags)

A 24-bit field reserved for flags, currently set to zero.

[`Elementary stream descriptor`](/documentation/quicktime-file-format/MPEG-4_elementary_stream_descriptor_atom/Elementary_stream_descriptor)

An elementary stream descriptor for MPEG-4 video.


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