|Internet media type|
|Initial release||22 September 2004|
SMPTE ST 377-1:2019
28 January 2020
|Type of format||Container format|
|Container for||Audiovisual material, rich metadata|
Material Exchange Format (MXF) is a container format for professional digital video and audio media defined by a set of SMPTE standards. A typical example of its use is for delivering advertisements to TV stations and tapeless archiving of broadcast TV programs. It is also used as part of the Digital Cinema Package for delivering movies to commercial theaters.
MXF, when used in the form of "Operational Pattern OP1A" or "OPAtom", can be used as a container, wrapper or reference file format which supports a number of different streams of coded "essence", encoded in any of a variety of video and audio compression formats, together with a metadata wrapper which describes the material contained within the MXF file. Other "Operational Patterns" can contain or reference multiple materials, just like a simple timeline of a video editing program.
MXF has full timecode and metadata support and is intended as a platform-agnostic stable standard for future professional video and audio applications.
MXF was developed to carry a subset of the Advanced Authoring Format (AAF) data model, under a policy known as the Zero Divergence Directive (ZDD). This theoretically enables MXF/AAF workflows between non-linear editing (NLE) systems using AAF and cameras, servers, and other devices using MXF.
From 2004 onwards, MXF was in the process of evolving from standard to deployment. The breadth of the standard was subject to lead to interoperability problems, as vendors implement different parts of the standard or interpret misleading parts of the standard differently.
MXF is fairly effective at the interchange of D10 (IMX) material, mainly because of the success of the Sony eVTR and Sony's eVTR RDD to SMPTE. Workflows combining the eVTR, Avid NLE systems, and broadcast servers using MXF in coordination with AAF are now possible.
Long-GOP MPEG-2 material interchange between video servers is possible, as broadcasters develop application specifications they expect their vendors to implement.
As of autumn 2005, there were major interoperability problems with MXF in broadcast post-production use. The two data-recording camera systems which produced MXF at that time, Sony's XDCAM and Panasonic's DVCPRO P2, produced mutually incompatible files due to opaque sub-format options obscured behind the MXF file extension. Without advanced tools, it was impossible to distinguish these incompatible formats.
Additionally, many MXF systems produce split-file A/V (video and audio stored in separate files), and use a file naming convention which relies on randomly generated filenames to link them. Not only does this exacerbate the issue of knowing exactly what is in an MXF file without specialized tools, but it breaks the functionality of standard desktop computer techniques. These techniques are generally used to manipulate data on a level as fundamental as moving, copying, renaming, and deleting. Using a randomly generated filename is uninformative to the user, but changing the name breaks the loose database structure between files.[original research?]
One example problem that caused interoperability problems[with whom?] in 2004 was when popular MXF export tools (i.e. the ones that are free or cost the least)[which?][relevant?] would not allow the user to create a stereo AES file within the MXF wrapper, nor allow the user to add a free-text annotation to the MXF file so created (in order, for instance, that the next user of the file be able to interpret his or her intentions). Thus, an MXF file received and unwrapped may reveal SMPTE D10 compliant essence with eight mono AES audio components; the recipient has no way of knowing whether these components are multiple stereo pairs, 5.1 or serve some other purpose.
Some of the incompatibilities were addressed and ratified in the 2009 version of the standard.
MXF is used as the audio and video packaging format for Digital Cinema Package (DCP). It is also used in the STANAG specification documents.
The file extension for MXF files is ".mxf". The Macintosh File Type Code registered with Apple for MXF files is "mxf ", including a trailing space.
This list represents some examples of free and open source[why?] products that support the MXF standard:
SMPTE's top standards page has information, for the ordering of CD-ROMs, which would hold formal copy of the SMPTE standards. Judging by SMPTE's index, all of the standards, referenced above, would be contained on those CD-ROMs, as available from SMPTE. IRT Test Center contains up-to-date information on the status of the SMPTE documents.
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