Material Exchange Format

Last updated

Material Exchange Format
Filename extension
.mxf
Internet media type
application/mxf
Type code "mxf"
Initial release22 September 2004;19 years ago (2004-09-22)
Latest release
SMPTE ST 377-1:2019
28 January 2020;4 years ago (2020-01-28)
Type of format Container format
Container for Audiovisual material, rich metadata
Open format?Yes
Free format?Yes [1]

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. [2] It is also used as part of the Digital Cinema Package for delivering movies to commercial theaters.

Contents

Summary

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.

Usage

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.

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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. [ citation needed ]

Some of the incompatibilities were addressed and ratified in the 2009 version of the standard. [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.

Tools

MXF converters

This list represents some examples of free and open source[ why? ] products that support the MXF standard:

  • Note that up to 2019, FFmpeg implements only the base MXF standard but does not provide vendor specific profiles, e.g. one cannot produce a MXF File that is compatible to Sony XDCAM devices due to missing header metadata entries (for further information see ffmpeg trac ticket 5097)

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

Related Research Articles

An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data is called the audio coding format and can be uncompressed, or compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with defined storage layer.

<span class="mw-page-title-main">DV (video format)</span> Digital video codecs and tape formats

DV is a family of codecs and tape formats used for storing digital video, launched in 1995 by a consortium of video camera manufacturers led by Sony and Panasonic. It includes the recording or cassette formats DV, MiniDV, DVCAM, Digital8, HDV, DVCPro, DVCPro50 and DVCProHD. DV has been used primarily for video recording with camcorders in the amateur and professional sectors.

A video file format is a type of file format for storing digital video data on a computer system. Video is almost always stored using lossy compression to reduce the file size.

MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938. This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description Interface. Thus, it is not a standard which deals with the actual encoding of moving pictures and audio, like MPEG-1, MPEG-2 and MPEG-4. It uses XML to store metadata, and can be attached to timecode in order to tag particular events, or synchronise lyrics to a song, for example.

Digital Picture Exchange (DPX) is a common file format for digital intermediate and visual effects work and is a SMPTE standard. The file format is most commonly used to represent the density of each colour channel of a scanned negative film in an uncompressed "logarithmic" image where the gamma of the original camera negative is preserved as taken by a film scanner. For this reason, DPX is the worldwide-chosen format for still frames storage in most digital intermediate post-production facilities and film labs. Other common video formats are supported as well, from video to purely digital ones, making DPX a file format suitable for almost any raster digital imaging applications. DPX provides, in fact, a great deal of flexibility in storing colour information, colour spaces and colour planes for exchange between production facilities. Multiple forms of packing and alignment are possible. The DPX specification allows for a wide variety of metadata to further clarify information stored within each file.

The Advanced Authoring Format (AAF) is a file format for professional cross-platform data interchange, designed for the video post-production and authoring environment. It was created by the Advanced Media Workflow Association (AMWA), and is now being standardized through the Society of Motion Picture and Television Engineers (SMPTE).

DVR-MS is a proprietary video and audio file container format, developed by Microsoft used for storing TV content recorded by Windows XP Media Center Edition, Windows Vista and Windows 7.

<span class="mw-page-title-main">XDCAM</span> Series of products for digital recording

XDCAM is a series of products for digital recording using random access solid-state memory media, introduced by Sony in 2003. Four different product lines – the XDCAM SD, XDCAM HD, XDCAM EX and XDCAM HD422 – differ in types of encoder used, frame size, container type and in recording media.

A container format or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files and formats used for multimedia playback. Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format.

These tables compare features of multimedia container formats, most often used for storing or streaming digital video or digital audio content. To see which multimedia players support which container format, look at comparison of media players.

Broadcast Wave Format (BWF) is an extension of the popular Microsoft WAV audio format and is the recording format of most file-based non-linear digital recorders used for motion picture, radio and television production. It was first specified by the European Broadcasting Union in 1997, and updated in 2001 and 2003. It has been accepted as the ITU recommendation ITU-R BS.1352-3, Annex 1.

Avid DNxHD is a lossy high-definition video post-production codec developed by Avid for multi-generation compositing with reduced storage and bandwidth requirements. It is an implementation of SMPTE VC-3 standard.

General eXchange Format (GXF) is a file exchange format for the transfer of simple and compound clips between television program storage systems. It is a container format that can contain Motion JPEG (M-JPEG), MPEG, or DV-based video compression standards, with associated audio, time code, and user data that may include user-defined metadata.

Ingex is an open-source (GPL) suite of software for the digital capture of audio and video data, without the need for traditional audio or video tape or cassettes. Serial digital interface (SDI) capture is supported, as well as real-time transcoding. Portions of the software suite also act as a network file server for media files, as well as archiving to LTO-3 data tape. Audio and video media files can also be stored on USB hard drives or Network Attached Storage. The software is heavily used by the BBC, and was developed by the BBC Research Laboratory.

A Digital Cinema Package (DCP) is a collection of digital files used to store and convey digital cinema (DC) audio, image, and data streams.

Windows Recorded TV Show (WTV) is a proprietary video and audiovisual file container format, developed by Microsoft used for storing TV content recorded by Windows Media Center. It is used in Windows Vista starting with Windows Media Center TV Pack 2008, and all Windows Media Center editions of Windows 7. The WTV format is the successor to the earlier DVR-MS file format that was used in Windows XP Media Center Edition.

The Advanced Media Workflow Association (AMWA) is an industry association focused on the content creation industry's move to IP-based architectures. AMWA promotes industry standards that allow diverse devices to discover and interoperate with each other reliably and securely.

Interoperable Master Format (IMF) is a container format for the standardized digital delivery and storage of finished audio-visual masters, including movies, episodic content and advertisements.

<span class="mw-page-title-main">Audiovisual archive</span>

In archives, the term "audiovisual" is frequently used generically to denote materials other than written documents. Films, videos, audio recordings, pictures, and other audio and visual media are collected in audiovisual archives. A vast amount of knowledge is included in audiovisual records, which are considered cultural treasures and must be preserved for future use. Print materials would not have the same reach across various audiences as audiovisual resources.

References

  1. Material Exchange Format (MXF) (Full draft). Sustainability of Digital Formats. Washington, D.C.: Library of Congress. 17 January 2012. Retrieved 13 December 2021.
  2. "Technical Specifications – Commercial File Delivery" (PDF). Archived from the original on 20 December 2016. Retrieved 14 December 2016.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  3. Pedro Ferreira (23 July 2010). "MXF – a progress report (2010)" (PDF).
  4. "STANAG 4609 Edition 2" (PDF). Archived from the original (PDF) on 10 November 2010. Retrieved 18 August 2010.
  5. "FFmpeg Changelog". 3 March 2009. Retrieved 20 August 2010.
  6. "FFmpeg". 3 December 2008. Retrieved 20 August 2010.
  7. "Ingex" . Retrieved 24 August 2009.