# Media atoms Atoms that describe and define a track’s media type and sample data. ## Overview The media atom contains information that specifies: - The media type, such as sound, video or timed metadata - The media handler component used to interpret the sample data - The media timescale and track duration - Media-and-track-specific information, such as sound volume or graphics mode - The media data references, which typically specify the file where the sample data is stored - The sample table atoms, which, for each media sample, specify the sample description, duration, and byte offset from the data reference ## Topics ### Describing media [`Media atom ('mdia')`](/documentation/quicktime-file-format/Media_atom) An atom that describes and defines a track’s media type and sample data. [`Media header atom ('mdhd')`](/documentation/quicktime-file-format/Media_header_atom) An atom that specifies the characteristics of a media, including time scale and duration. [`Extended language tag atom ('elng')`](/documentation/quicktime-file-format/Extended_language_tag_atom) An atom that represents media language information. [`Handler reference atom ('hdlr')`](/documentation/quicktime-file-format/Handler_reference_atom) An atom that specifies the media handler component that is to be used to interpret the media’s data. [Media information atoms](/documentation/QuickTime-File-Format/Media_information_atoms) An atom that contains a number of other atoms that define specific characteristics of the video media data. [`Video media information atom ('minf')`](/documentation/quicktime-file-format/Video_media_information_atom) An atom that contains a number of other atoms that define specific characteristics of the video media data. [`Video media information header atom ('vmhd')`](/documentation/quicktime-file-format/Video_media_information_header_atom) An atom that defines specific color and graphics mode information. [`Sound media information atom ('minf')`](/documentation/quicktime-file-format/Sound_media_information_atom) An atom that contains a number of other atoms that define specific characteristics of the sound media data. [`Sound media information header atom ('smhd')`](/documentation/quicktime-file-format/Sound_media_information_header_atom) An atom that stores the sound media’s control information, such as balance. [`Base media information atom ('minf')`](/documentation/quicktime-file-format/Base_media_information_atom) An atom that stores the media information for media types such as timed metadata, text, MPEG, time code, and music. [`Base media information header atom ('gmhd')`](/documentation/quicktime-file-format/Base_media_information_header_atom) An atom that indicates that this media information atom pertains to a base media. [`Base media info atom ('gmin')`](/documentation/quicktime-file-format/Base_media_info_atom) An atom that defines the media’s control information, including graphics mode and balance information. [`Data information atom ('dinf')`](/documentation/quicktime-file-format/Data_information_atom) An atom that specifies the data handler component that provides access to the media data. [`Media data reference atom ('dref')`](/documentation/quicktime-file-format/Media_data_reference_atom) An atom that contains tabular data that instructs the data handler component how to access the media’s data. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)