An Overview of MXF and the Search for the Video File Wrapper'

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An Overview of MXF and the Search for the Video
File Wrapper.

• NDIIPP
• Preserving Digital Public Television
• JTS 2007
• Toronto

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Universal Preservation Format

• Self describing storage
• Must know the coding of the file.
• Must know the coding of the essence within the
  file.

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Universal Preservation Format

• Wrapper contains both essence and metadata
• Must know the location of the essence and
  metadata within the file.

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Open Source Codecs

• Report on File Formats and Packages
• http//www.ptvdigitalarchive.org
• VLAN
• http//www.videolan.org/
• FFMPEG
• http//ffmpeg.sourceforge.net/index.php

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Source Code Links

• http//www.free-codecs.com/
• http//www.avsmedia.com/downloads/codecs.aspx
• http//forum.doom9.org/
• http//sourceforge.net/projects/libdv/
• http//www.openquicktime.org/
• http//www.free-codecs.com/download/QuickTime_Alte
  rnative.htm
• http//dirac.sourceforge.net/
• http//www.avid.com/forms/DNxHDinfo.asp

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MXF Background MXF - AS/PBS

• Thomas Edwards
• PBS

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MXF What is It?

• Material eXchange Format
• Influenced by the EBU/SMPTE Joint Task Force for
  Harmonised Standards for the Exchange of
  Television Programmes as bit streams
• A wrapper format that ties together essence and
  metadata elements into a coherent whole

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What can you do with MXF?

• Store simple completed works with metadata
• Store files in a streamable format
• Wrap up a playlist/EDL and essence with
  synchronization information
• Wrap a wide variety of compression formats

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KLV Coding (SMPTE 336M)

• K Key a unique identifier
• L Length how long is the field
• Encoded with ASN.1 BER, so can be as big as
  needed
• lt 0x80 is actual length (0-127 decimal)
• 0x8Y implies next Y bytes contain actual length
• Example 0x82.10.00, length is 0x1000 4096
  decimal
• V Value what is the value of the field

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KLV Using SMPTE MDD
06.0E.2B.34.01.01.01.02.01.05.08.00.00.00.00.00
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47 6F 6E 65 20 57
SMPTE Designator
Length
Value
SMPTE Item
Version Title
Colonial House (in ISO-7 bit code)
UL SMPTE Universal Label (16 bytes)
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Simple Versus Complex

• MXF files can be very simple
• Just wrap up my essence
• E-VTRs, Video Servers
• MXF files can be very complex
• EDLs, alternate packages
• Self-referential clips
• Software implementations

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Simple MXF File

• Partitions
• Logical division of a file for easier parsing
• Header
• Has metadata about whole file
• Body
• Contains essence
• Footer
• Terminates file can have updated metadata

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Metadata in MXF

• Structural Metadata
• Capability of a file how it is constructed
• Descriptive Metadata
• Editorial aspects of the file
• Several schemes available, such as DMS-1
• Dark Metadata
• Metadata unknown by some applications
• Static Metadata
• Doesnt change over entire output
• e.g. Show title, producer, etc.
• Time-Dependent Metadata
• Timeline or Event
• e.g. This part was shot by Bob

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MXF Object Model

• Packages
• A logical grouping of metadata sets
• Material Package
• Represents output timeline
• Owns Tracks
• File Package
• Represents actual essence in the file

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Physical vs Logical

• physical - how the bytes are stored (essence
  container)
• logical - what the bytes are intended to
  represent (packages)

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MXF Object Model cont.
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KLV Wrapping of Essence
Frame Wrapped
Clip Wrapped
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MXF Standards

• SMPTE 377M MXF File Format Specification
• Essence Containers
• SMPTE 385M SDTI-CP
• SMPTE 381M MPEG (including long-GOP)
• SMPTE 382M AES3 and Broadcast Wave Audio
• SMPTE 383M DV 25/50
• SMPTE 386M D-10 (IMX 50 Mbps I-frame MPEG2)
• SMPTE 387M D-11 (HDCAM)
• Descriptive Metadata
• SMPTE 380M MXF Descriptive Metadata Scheme - 1
  (DMS-1)

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Why Bother?

• MXF is a good way to wrap up video essence into
  files
• MXF is a good way to link rich metadata to video
  essence
• MXF has support from many vendors for
  interoperation (but this is a work-in-progress)
• MXF and file transfer may provide significant
  benefits for an IT-oriented workflow

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PBS File Delivery Project(NGIS)

• Distribute long-form, broadcast-quality video as
  files
• To 180 independent public television
  organizations
• Five major video server vendors, and some smaller
  vendors

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NGIS in Operation
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MXF Format Woes

• MXF can wrap many different types of audio and
  video essence
• There are a number of ways that variable size
  edit unit essence can be indexed
• MXF has ten different Operational Patterns
  (OPs)
• MXF can carry a wide range of descriptive
  metadata schemes

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MXF AS/PBS

• An MXF Application Specification for PBS
• Base Requirements
• Single file per program distribution mechanism.
• Direct play back (or import) into MXF compatible
  servers
• Otherwise easy to translate into non-MXF
  compatible servers

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AS-PBS Development

• Began in 2004 based on AS-CNN
• Five key server vendors to public television
  initially involved
• Expanded to include other server and translation
  vendors
• Iterative process w. teleconferences and email
  distribution
• SD targeted first

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MXF/AS-PBS Essence

• Video essence type
• MPEG-2 420
• Video bitrate
• 8 Mbps
• Audio essence type
• Uncompressed, 16-bit PCM audio in BWF
• VBI (CC/XDS)
• SMPTE 334M ANC carried in SMPTE 436M for MXF

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MXF/AS-PBSMXF Features

• OP1a
• Partitions no longer than 30 minutes
• Index Table segments in partition after the
  Essence they index

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MXF/AS-PBS Future

• To be defined
• HD Version
• Archive version

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MXF/AS-PBS

• Short Golden Files available
• Actual full-length program example to be
  distributed shortly (MPEG pre-charge issue being
  worked out)
• AS-PBS specification is available to those who
  want to see it, email
• tedwards_at_pbs.org

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Library of Congress Stake

• Carl Fleischhauer
• National Digital Information Infrastructure and
  Preservation Program

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Video Reformatting at the National Audio-Visual
Conservation Center
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From SMPTE 390M
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Concern for born-digital content
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Born digital examples (not moving image)
Web harvest
GIS
Still image Mark Yankus
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http//www.ptvdigitalarchive.org/
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Preservation FormattingWorking Scorecard

• Interoperability very important
• From-the-hip scorecards for
• Wrapper
• Essence
• Profiles/Application Specs
• Metadata

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Wrapper Scorecard

• No-wrapper vs. with-wrapper
• Proprietary vs. open specification
• Sizing up ISO/IEC 15444-3
  Motion JPEG 2000
• AAF/MXF is attractive
• How settled in the community? Moderately

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Picture Essence Scorecard

• MPEG (ITU-T) family
• MPEG-2 (H.262)
• MPEG-4 (H.263 but mostly H.264)
• All I-frame possible (preservation value)
• JPEG 2000 family
• Frame image encoding
• Possible wrapper
• Less adoption in still photography than some wish
• How settled in the community? Not bad, no need
  for one size to fit all

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Profile/App Spec Scorecard

• Important part of MPEG family from an early day
• Several ISO/IEC profiles and levels
• SMPTE added one for 422 _at_ high level
• MXF is complex
• Will benefit from application specification
• Good example from PBS discussed today
• JPEG 2000 family
• Digital Cinema Initiative has established two
  profiles
• LC has one for its newspaper scanning project
• How settled in the community? In the early stages

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Metadata Scorecard

• Metadata for management, support long-term
  preservation
• Technical characteristics
• SMPTE RP-210 data dictionary (parametrics)
• Public Broadcasting PB Core (instantiation)
• Preservation support
• Includes preceding
• Library community PREMIS project, e.g., fixity
• Specifications, source code for
  readers/transformers
• How settled in the community? Not very

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Preserving DigitalPublic Television

• http//www.ptvdigitalarchive.org/