Material Exchange Format

Material Exchange Format
Filename extension .mxf
Internet media type application/mxf
Type code "mxf "
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 brief summary of MXF

MXF is a "container" or "wrapper" 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.

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 theoretically 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.

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 subformat 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 (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.

Furthermore, the currently popular MXF export tools (i.e. the ones that are free or cost the least) will not allow the user to create a stereo AES file within the MXF wrapper, nor will they allow the user to add 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 & 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.

Most of the incompatibilities were addressed and ratified in the 2009 version of the standard.[1]

Sony's XDCAM MXF is supported by Adobe After Effects, Adobe Premiere Pro, Apple Final Cut Pro X, Autodesk Smoke, Avid, Capella systems, Dalet, EVS, Harris, Omneon, Quantel, Rhozet, Sony Vegas Pro, Sorenson Squeeze, Telestream FlipFactory, GrassValley EDIUS, Grass Valley K2, and Merging Technologies VCube.

Panasonic's P2 MXF is supported by Adobe After Effects, Adobe Premiere Pro, Apple Final Cut Pro X, Autodesk Smoke, Avid, Dalet, EVS, GrassValley EDIUS,[2] and Grass Valley K2.

Ikegami offers camcorders capable of recording in MXF wrapper using Avid DNxHD video encoding at 145 Mbit/s, as well as MPEG-2 video encoding at 50 Mbit/s 4:2:2 long-GOP and 100 Mbit/s I-frame.

In 2010 Canon released its new lineup of professional file-based camcorders. The recording format used in these camcorders incorporates MPEG-2 video with bitrates up to 50 Mbit/s and 16-bit linear PCM audio in what Canon has called XF codec. Canon claims that its flavor of MXF is fully supported by major NLE systems including Adobe Premiere, Apple Final Cut Pro X, Avid Media Composer, and Grass Valley EDIUS.[3]

MXF is used as the audio and video packaging format for Digital Cinema Package (DCP). It is also used in the STANAG specification documents.[4]

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.

CinemaDNG (intended by Adobe and others to be an open file format for digital cinema files) exploits MXF as one of its options for holding a sequence of raw video images. (The other option is to store a sequence of DNG files in a specified directory).

Tools

NLE and MXF enablers

There are an increasing number of professional NLE's that can work with MXF files natively including Avid Media Composer, Adobe Premiere Pro 3.1 or above, Sony Vegas, and GrassValley EDIUS or via import operations like in Final Cut Pro using the Sony XDCAM Transfer plug-in. Latest versions of Avid editing products store media in Avid MXF Op-Atom and import/export MXF Op1a or using mxfSPEEDRAIL F1000 or Glookast Gloobox Ingester applications that supports any kind of MXF flavour. Pitivi is the first open source video editor to support the Material Exchange Format (MXF).

MXF converters

The MXF standards

Base documents

Operational patterns

Generic containers

Metadata, dictionaries and registries

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. IRT Test Center contains up-to-date information on the status of the SMPTE documents.

See also

References

  1. ↑ Pedro Ferreira (23 July 2010). "MXF - a progress report (2010)" (PDF).
  2. ↑ http://www.grassvalley.com/docs/Comparison_Guides/professional/edius/PRV-4164M-1_EDIUS_Feature_CompGuide.pdf>
  3. ↑ "Introducing the XF305 and XF300: Canon's New Pro Camcorders". 2010-04-09.
  4. ↑ "STANAG 4609 Edition 2" (PDF). Retrieved 2010-08-18.
  5. ↑ "FFmpeg Changelog". 2009-03-03. Retrieved 2010-08-20.
  6. ↑ "FFmpeg". 2008-12-03. Retrieved 2010-08-20.
  7. ↑ "Ingex". Retrieved 2009-08-24.

External links

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