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# MPEG-1 media

Store MPEG-1 video streams, MPEG-1, layer 2 audio streams, and multiplexed MPEG-1 audio and video streams in QuickTime movies.

## Overview

MPEG-1 media is used to store MPEG-1 video streams, MPEG-1, layer 2 audio streams, and multiplexed MPEG-1 audio and video streams in QuickTime movies. It has a media type of `'MPEG'`.

## MPEG-1 Sample Description

The MPEG-1 sample description uses the standard sample description header, as described in [`Sample description atom`](/documentation/quicktime-file-format/Sample_description_atom).

The data format field in the sample description is always set to `'MPEG'`. The MPEG-1 media handler adds no additional fields to the sample description.

> Note: This data format is not used for MPEG-1, layer 3 audio, however (see MPEG-1 Layer 3 (MP3) Codecs in <doc://com.apple.qtff/documentation/QuickTime-File-Format/Sound_sample_data>).

## MPEG-1 Sample Data

Each sample in an MPEG-1 media is an entire MPEG-1 stream. This means that a single MPEG-1 sample may be several hundred megabytes in size. The MPEG-1 encoding used by QuickTime corresponds to the ISO standard, as described in ISO document CD 11172.

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