Sustainability of Digital Formats: Planning for Library of Congress Collections

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MXF Format Generic Container

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Material Exchange Format (MXF) -- MXF Generic Container
Description

The native essence container for the MXF file format that carries video, audio, metadata and other "payloads," i.e., bitstreams called essences in the audio-visual community. See Notes for additional information.

The container is described as "streamable," meaning that its audio-visual content can be "continuously decoded through mechanisms such as interleaving essence components with stream-based metadata." (The term does not refer to streaming in sense that this word is used in connection with protocols like the Real-Time Transport Protocol [RTP] and the Real Time Streaming Protocol [RTSP].)

Note about the MXF Constrained Generic Container: This modification of the MXF Generic Container is defined by SMPTE ST 379-2:2010, and it is not described at this Web site at this time. The abstract for the constrained container states: "This standard defines the data structure at the signal interfaces of networks or storage media. This standard does not define internal storage formats for MXF compliant devices."

Production phase Middle-state format for material exchange or archiving; may also be a final state format for use in a delivery context, e.g., broadcasting.
Relationship to other formats
    Used by MXF, Material Exchange Format
    Has subtype MXF_GC_UNC, MXF Generic Container Mapped to Uncompressed Images
    Has subtype MXF_GC_MPEG-2, MXF Generic Container Mapped to MPEG-2 Video Bitstream
    Has subtype MXF_GC_SDTI-CP, MXF Generic Container Mapped to SDTI Content Package
    Has subtype MXF_GC_DV-DIF, MXF Generic Container Mapped to DV-DIF Packets
    Has subtype MXF_GC_JP2, MXF Generic Container Mapped to JPEG 2000
    Has subtype MXF_GC_AES3, MXF Generic Container Mapped to AES3 Audio (LPCM)
    Has subtype MXF generic container mapped to other encodings, not documented at this time.
    Has modified version MXF Constrained Generic Container (SMPTE ST 379-2:2010). Not described at this Web site at this time.

Local use Explanation of format description terms

LC experience or existing holdings See MXF
LC preference See MXF

Sustainability factors Explanation of format description terms

Disclosure Open standard. Developed by the Society of Motion Picture and Television Engineers (SMPTE), a member of the American National Standards Institute (ANSI).
    Documentation SMPTE ST 379-1:2009, Material Exchange Format (MXF) -- MXF Generic Container. For a full list of citations, see Format specifications in MXF.
Adoption See MXF
    Licensing and patents See MXF
Transparency Depends upon encoding.
Self-documentation Extensive system or structural metadata is required to support the use of the various bitstreams placed in the Generic Containers, and this metadata is encoded as KLV (Key-Length-Value) data, and is found with the bitstreams in the container. Descriptive metadata for users is associated with the MXF format itself.
External dependencies None
Technical protection considerations See MXF

Quality and functionality factors Explanation of format description terms

Moving Image
Normal rendering Not applicable
Clarity (high image resolution) Potentially excellent; depends upon encoding.
Functionality beyond normal rendering Not applicable
Sound
Normal rendering Not applicable
Fidelity (high audio resolution) Potentially excellent; depends upon encoding. For example, the specification set includes a mapping of WAVE_LCPM_BWF (a "storage" format; the same encoding is also referred to as the "interface format" AES3) into the MXF Generic Container; see the subtype MXF_AES3.
Multiple channels See MXF
Functionality beyond normal rendering Not applicable

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension Not applicable.   
Internet Media Type Not applicable.   
Other   Item type identifier found at byte 13 in each KLV coded element; varies by essence type.

Notes Explanation of format description terms

General

Selected and paraphrased from pages 2-5 of the specification: "The MXF generic container comprises a contiguous sequence of content packages, each of which has up to five basic components known as items." Types include system items (metadata or control elements related to the container or the other item types), picture items, sound items, data items (for data essences, e.g., closed caption data or tele-text), compound items ("indivisible mixture of different essence types").

Content packages may be of constant or variable length. "Each content package represents the essence and metadata elements interleaved over a defined duration (typically 1 picture frame) and is constructed of up to five items . . . ." The MXF container offers two forms of essence mapping. "In frame-based mapping, there may be one or more content packages in the essence container. If there is only one content package, it shall represent the contents of a single frame or field." "In clip-based mapping, there shall be only one content package in the essence container. The duration of the clip may be one or more frames . . . ."

History See MXF.

Format specifications Explanation of format description terms


Useful references

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Last Updated: 02/21/2017