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

This overview provides insight into MXF, the universal preservation format wrapper that combines essence and metadata elements, and explores the search for the appropriate video file wrapper for digital public television preservation. It also includes information on coding, formats, codecs, and source code links.

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

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  1. An Overview of MXF and the Search for the Video File Wrapper. NDIIPP Preserving Digital Public Television JTS 2007 Toronto

  2. Self describing storage Must know the coding of the file. Must know the coding of the essence within the file. Universal Preservation Format

  3. Wrapper contains both essence and metadata Must know the location of the essence and metadata within the file. Universal Preservation Format

  4. Report on File Formats and Packages http://www.ptvdigitalarchive.org VLAN http://www.videolan.org/ FFMPEG http://ffmpeg.sourceforge.net/index.php Open Source Codecs

  5. 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_Alternative.htm http://dirac.sourceforge.net/ http://www.avid.com/forms/DNxHDinfo.asp Source Code Links

  6. Thomas Edwards PBS MXF Background & MXF - AS/PBS

  7. 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 MXF – What is It?

  8. 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 What can you do with MXF?

  9. 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 • < 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

  10. KLV Using SMPTE MDD 06.0E.2B.34.01.01.01.02.01.05.08.00.00.00.00.00 14 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)

  11. MXF files can be very simple “Just wrap up my essence” E-VTRs, Video Servers MXF files can be very complex EDL’s, alternate packages Self-referential clips Software implementations Simple Versus Complex

  12. 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

  13. 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 Doesn’t change over entire output e.g. Show title, producer, etc. Time-Dependent Metadata Timeline or Event e.g. “This part was shot by Bob” Metadata in MXF

  14. Packages A logical grouping of metadata sets Material Package Represents output timeline Owns Tracks File Package Represents actual essence in the file MXF Object Model

  15. physical - how the bytes are stored (essence container) logical - what the bytes are intended to represent (packages) Physical vs Logical

  16. MXF Object Model cont.

  17. KLV Wrapping of Essence “Frame Wrapped” “Clip Wrapped”

  18. 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) MXF Standards

  19. 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 Why Bother?

  20. Distribute long-form, broadcast-quality video as files To 180 independent public television organizations Five major video server vendors, and some smaller vendors PBS File Delivery Project(NGIS)

  21. NGIS in Operation

  22. 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 MXF Format Woes

  23. 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 MXF – AS/PBS

  24. 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 AS-PBS Development

  25. Video essence type: MPEG-2 4:2:0 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 MXF/AS-PBS Essence

  26. OP1a Partitions no longer than 30 minutes Index Table segments in partition after the Essence they index MXF/AS-PBSMXF Features

  27. To be defined: HD Version Archive version MXF/AS-PBS Future

  28. 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@pbs.org MXF/AS-PBS

  29. Carl Fleischhauer National Digital Information Infrastructure and Preservation Program Library of Congress Stake

  30. Video Reformatting at the National Audio-Visual Conservation Center

  31. From SMPTE 390M

  32. Concern for born-digital content

  33. Born digital examples (not moving image) Web harvest GIS Still image Mark Yankus

  34. http://www.ptvdigitalarchive.org/

  35. Interoperability very important From-the-hip scorecards for Wrapper Essence Profiles/Application Specs Metadata Preservation FormattingWorking Scorecard

  36. 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 Wrapper Scorecard

  37. 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 Picture Essence Scorecard

  38. Important part of MPEG family from an early day Several ISO/IEC profiles and levels SMPTE added one for 4:2:2 @ 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 Profile/App Spec Scorecard

  39. 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 Metadata Scorecard

  40. http://www.ptvdigitalarchive.org/ Preserving DigitalPublic Television

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