Material Exchange Format
Material eXchange Format (MXF) is a container format for professional digital video and audio media defined by a set of SMPTE standards.
A brief summary of MXF
MXF is a "container" or "wrapper" format which supports a number of different streams of coded "essence", encoded with any of a variety of codecs, together with a metadata wrapper which describes the material contained within the MXF file.
MXF has been designed to address a number of problems with non-professional formats. 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 enables MXF/AAF workflows between non-linear editing (NLE) systems using AAF and cameras, servers, and other devices using MXF.
MXF in use
MXF is in the process of evolving from standard to deployment. The breadth of the standard can lead to interoperability problems as vendors implement different parts of the standard.
Currently, 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 improving, especially 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 produce MXF, Sony's XDCAM and Panasonic's DVCPRO P2, produce files which are mutually incompatible due to opaque subformat options obscured behind the MXF file extension. Without advanced tools, it is impossible to distinguish these incompatible formats.
Additionally, many MXF systems produce split-file A/V (that is, the 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 which 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.
Also, MXF is not supported by several prominent applications, including Adobe After Effects. The implementation in other products, including Avid Newscutter, is particularly wanting, and highlights the identification issue by easily confusing XDCAM and P2 MXF flavours. Despite MXF's purpose as an easily archivable format, importing split-file MXF with external XML metadata intact can be brutally complicated.
The file extension for MXF files is ".mxf". The Macintosh File Type Code registered with Apple for MXF files is "mxf " (note the trailing space) .
Software
HPA Media Tool is a windows based software to import and export D10 files via AAF in Digidesign, Pro Tools. There is an increasing number of professional NLE's that can work with MXF files natively including Sony Vegas, GrassValley Edius, and Adobe Premiere Pro with Matrox Axio. Latest versions of AVID editing products store media in MXF Op-Atom and import/export MXF Op1a or using a new application called Toboggan MediaTransfer that supports any kind of MXF flavour. There are also a number of MXF SDKs available such as MXFLib, MXFTk and the MXF::SDK.
The MXF Standards
- Base Documents
- SMPTE 377M: The MXF File Format Specification (the overall master document)
- SMPTE EG41: MXF Engineering Guide (A guide explaining how to use MXF)
- SMPTE EG42: MXF Descriptive Metadata (A guide explaining how to use descriptive metadata in MXF)
- Operational Patterns
- SMPTE 390M: OP-Atom (a very simple and highly constrained layout for simple MXF files)
- SMPTE 378M: OP-1a (the layout options for a minimal simple MXF file)
- SMPTE 391M: OP-1b
- SMPTE 392M: OP-2a
- SMPTE 393M: OP-2b
- SMPTE 407M: OP-3a, OP-3b
- SMPTE 408M: OP-1c, OP-2c, OP-3c
- Generic Containers
- SMPTE 379M: Generic Container (the way that essence is stored in MXF files)
- SMPTE 381M: GC-MPEG (how to store MPEG essence data in MXF using the Generic Container)
- SMPTE 383M: GC-DV (how to store DV essence data in MXF using the Generic Container)
- SMPTE 385M: GC-CP (how to store SDTI-CP essence data in MXF using the Generic Container)
- SMPTE 386M: GC-D10 (how to store SMPTE D10 essence data in MXF using the Generic Container)
- SMPTE 387M: GC-D11 (how to store SMPTE D11 essence data in MXF using the Generic Container)
- SMPTE 382M: GC-AESBWF (how to store AES/EBU and Broadcast Wave audio essence data in MXF using the Generic Container)
- SMPTE 384M: GC-UP (how to store Uncompressed Picture essence data in MXF using the Generic Container)
- SMPTE 388M: GC-AA (how to store A-law coded audio essence data in MXF using the Generic Container)
- SMPTE 389M: Generic Container Reverse Play System Element
- SMPTE 394M: System Item Scheme-1 for Generic Container
- SMPTE 405M: Elements and Individual Data Items for the GC SI Scheme 1
- Metadata, Dictionaries and Registries
- SMPTE 380M: DMS1 (a standard set of descriptive metadata to use with MXF files)
- SMPTE 436M: MXF Mappings for VBI Lines and Ancillary Data Packets
- SMPTE RP210: SMPTE Metadata Dictionary (the latest version is available here: http://www.smpte-ra.org/mdd/index.html )
- SMPTE RP224: Registry of SMPTE Universal Labels
Availability of Standards
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.
See also
- AAF, Advanced Authoring Format
- BWF, broadcast Wave Format