Network Working Group                                         T. Edwards
Request for Comments: 4539                                           PBS
Category: Informational                                         May 2006


                   Media Type Registration for the
     Society of Motion Picture and Television Engineers (SMPTE)
                    Material Exchange Format (MXF)

Status of This Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard of any kind.  Distribution of this
  memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (2006).

Abstract

  This document serves to register a media type for the Society of
  Motion Picture and Television Engineers (SMPTE) Material Exchange
  Format (MXF).  MXF, defined by SMPTE 377M, is a standard wrapper
  format developed for the interchange of audiovisual material,
  including both audiovisual essence and rich metadata.

Table of Contents

  1. Introduction ....................................................2
  2. Security Considerations .........................................3
  3. IANA Considerations .............................................3
     3.1. Media Type for SMPTE Material Exchange Format (MXF) ........3
  4. References ......................................................5
     4.1. Normative References .......................................5
     4.2. Informative References .....................................5















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1.  Introduction

  The present document registers a media type for SMPTE Material
  Exchange Format (MXF).  MXF, defined by SMPTE 377M [SMPTE377M], is a
  standard wrapper format developed for the interchange of audiovisual
  material, including both audiovisual essence and rich metadata.

  Essence is the raw video, audio, and data streams contained and
  described by MXF.  Metadata carried by MXF includes structural
  metadata and descriptive metadata.  Structural metadata relates to
  the structure and capabilities of the MXF file and is generally
  required for proper decoding.  Some examples of structural metadata
  are descriptions of essence types, information to help synchronize
  playout of audio and video, and content length.  Descriptive metadata
  gives information about the program content in the file and is not
  essential for decoding.  Some examples of descriptive metadata are
  program title, actors, and scene descriptions.  The essence in MXF
  files may itself carry data, such as vertical blanking interval data
  used for carriage of Closed Captioning and other purposes.

  MXF is an important tool in providing interoperation between
  different video systems as well as digital cinema systems.  MXF also
  aids in the development of video production and distribution
  workflows that are more efficient, multi-vendor, file based, and IT
  oriented.

  SMPTE currently has standards for the mapping of the following
  essence types to the MXF generic container: MPEG (including MPEG-1
  and MPEG-2 video streams, as well as MPEG audio), DV-DIF (Digital
  Video Digital Interface Format for the DV family of related video
  encodings), Uncompressed Pictures, SDTI-CP (Serial Digital Transport
  Interface Content Package for delivering packetized audiovisual
  content over the SDI interface), D-10 (a specialized video stream
  incorporating MPEG-2 4:2:2P@ML), D-11 (a high-definition video
  compression standard), AES3 audio, Broadcast Wave audio, and A-Law
  audio.  The flexibility of the MXF generic container allows for the
  possibility of mappings of additional essence types in the future.

  The media type defined here is needed to correctly identify MXF files
  when they are served over HTTP or other network connections, included
  in multi-part documents, indexed by operating systems and digital
  asset management systems, or used in other places where media types
  are used.








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2.  Security Considerations

  Security requirements for the application/mxf media type are
  discussed in the IANA media type registration (Section 3.1).

3.  IANA Considerations

  The IANA has registered the media type application/mxf as specified
  in Section 3.1.  The registration uses the template present in
  [RFC4288].

3.1.  Media Type for SMPTE Material Exchange Format (MXF)

  To: [email protected]
  Subject: Registration of media type application/mxf

  Type name: application

  Subtype name: mxf

  Required parameters: none

  Optional parameters: ULs

  The optional parameter ULs is a single Uniform Resource Name (URN),
  or a comma-separated list of multiple URNs of SMPTE Universal Labels
  (which are defined by SMPTE 400M [SMPTE400M]).

  This optional parameter provides hints to the decoder regarding the
  structure of the MXF file, which could include Operational Pattern,
  essence types, descriptive metadata schemes, and other elements that
  are identified by their SMPTE Universal Label.

  SMPTE Universal Labels are Object Identifiers (OIDs), as specified by
  [ASN1].  Thus, a URN of a SMPTE Universal Label can use the OID URN
  namespace specified in [RFC3061], or any other future URN namespace
  that is appropriate for SMPTE Universal Labels.

  Note that, per [RFC2045], some characters (including the comma used
  to separate multiple values) require that the entire parameter value
  be enclosed in quotes.

  Below is an example of use of the optional parameter.  The two SMPTE
  Universal Labels indicate that the MXF file uses the OP1a Operational
  Pattern and contains IEC DV video at 25 Mbps, 525 lines, 59.94 fps
  interlaced essence.





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     Content-Type:  application/mxf;
        ULs="urn:oid:1.3.52.4.1.1.1.13.1.2.1.1.1,
        urn:oid:1.3.52.4.1.1.1.4.1.2.2.2.1.1"

  Encoding considerations: binary

  Security considerations: Application/mxf objects are not signed but
  may be partially encrypted internally.  External security mechanisms
  must be employed to ensure content confidentiality.  MXF, through
  metadata extensions, may allow executable code to be transferred in
  the file.  It is suggested that no unauthenticated executables
  decoded from an MXF file be executed.  Some compressed essence types
  carried in MXF may carry a risk that certain pathological bitstreams
  could lead to potential denial-of-service attacks against these
  essence decoders.

  Interoperability considerations: MXF provides a standard wrapping for
  a number of audio and video essence types according to a number of
  different Operational Patterns (OP).  Thus, interoperability depends
  upon whether the MXF file decoder has the capability to match the
  features of the MXF file encoder.  An Application Specification (AS)
  can ensure that MXF encoders and decoders can interoperate
  effectively.

  Published specification: RFC 4539, SMPTE 377M [SMPTE377M]

  Applications that use this media type: MXF is a wrapper for many
  types of audio and video essence types in use by many applications in
  the broadcast and digital cinema industries.  These include
  non-linear editing systems, video servers, video camera systems,
  digital asset management systems, and digital video distribution
  systems.

  Additional information:

     Magic number(s): none

     File extension(s): .mxf

     Macintosh File Type Code(s): "mxf "

  Person & email address to contact for further information:
  Thomas Edwards
  email: [email protected]

  Intended usage: COMMON

  Restrictions on usage: none



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  Author/Change controller:

  Thomas Edwards
  email: [email protected]

4.  References

4.1.  Normative References

  [SMPTE377M] Society of Motion Picture and Television Engineers,
              "Material Exchange Format (MXF) File Format
              Specification", SMPTE 377M-2004, <http://www.smpte.org>.

  [SMPTE400M] Society of Motion Picture and Television Engineers,
              "SMPTE Labels Structure", SMPTE 400M-2004,
              <http://www.smpte.org>.

4.2.  Informative References

  [ASN1]      International Telephone and Telegraph Consultative
              Committee, "Specification of Basic Encoding Rules for
              Abstract Syntax Notation One (ASN.1)",
              CCITT Recommendation X.209, January 1988.

  [RFC2045]   Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

  [RFC3061]   Mealling, M., "A URN Namespace of Object Identifiers",
              RFC 3061, February 2001.

  [RFC4288]   Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", BCP 13, RFC 4288, December
              2005.

Author's Address

  Thomas G. Edwards
  PBS
  6453 Stephenson Way
  Alexandria, VA  22312
  US

  Phone: +1 703 739 5000
  EMail: [email protected]
  URI:   http://www.pbs.org





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Full Copyright Statement

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Acknowledgement

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