(RFC 4539 published May 2006, subtype last updated May 2006)

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.

   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: tedwards&pbs.org

Intended usage: COMMON

Restrictions on usage: none

Author/Change controller:

Thomas Edwards
email: tedwards&pbs.org