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# Base media info atom ('gmin')

An atom that defines the media’s control information, including graphics mode and balance information.

## Overview

The base media info atom, contained in the base media information header atom (`'gmhd'`), defines the media’s control information, including graphics mode and balance information.

The layout of the base media info atom is as follows.

|Base media info atom                                                                           |Bytes|
|-----------------------------------------------------------------------------------------------|-----|
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Size``         |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Type``         |4    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Version``      |1    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Flags``        |3    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Graphics_mode``|2    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Opcolor``      |6    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Balance``      |2    |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Base_media_info_atom/Reserved``     |2    |

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/Base_media_info_atom/Size)

A 32-bit integer that specifies the number of bytes in this base media info atom.

[`Type`](/documentation/quicktime-file-format/Base_media_info_atom/Type)

A 32-bit integer that identifies the atom type.

[`Version`](/documentation/quicktime-file-format/Base_media_info_atom/Version)

A 1-byte specification of the version of this base media information header atom.

[`Flags`](/documentation/quicktime-file-format/Base_media_info_atom/Flags)

A 3-byte space for base media information flags.

[`Graphics mode`](/documentation/quicktime-file-format/Base_media_info_atom/Graphics_mode)

A 16-bit integer that specifies the transfer mode.

[`Opcolor`](/documentation/quicktime-file-format/Base_media_info_atom/Opcolor)

Three 16-bit values that specify the red, green, and blue colors for the transfer mode operation indicated in the graphics mode field.

[`Balance`](/documentation/quicktime-file-format/Base_media_info_atom/Balance)

A 16-bit integer that specifies the sound balance of this media.

[`Reserved`](/documentation/quicktime-file-format/Base_media_info_atom/Reserved)

Reserved for use by Apple.


---

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