Metadata: The keys to the kingdom
Jun 7, 2006 1:38 PM, Transition to Digital e-newsletter
To be able to assemble program elements for broadcast you have to be able to find them. In a tapeless environment there are no labels on the spines of tapes. Clips and graphic elements reside on a disk. A simple hierarchical directory structure may suffice in the short term, but how do you find a clip or graphics element from last year?
Disk storage is expensive so moving content off to a tape archive is prudent business practice. But you can’t manually search through a robotic tape archive by loading each tape and checking the volume table of contents via a directory or folder listing.
It gets worse. Let’s suppose you want every presidential speech in the last decade that mentioned unemployment. How do you find these clips when they are scattered over numerous archived tapes? Even if the content is on disks, this is still a virtually impossible task.
Now let’s add constraint. These speeches cannot be State of the Union speeches and must have been delivered at luncheons. It would be like searching for needles in a number of haystacks.
On your mark
Broadcasters and the media industry are not the first to be confronted with this dilemma. In the pre-PC age, libraries kept track of their books by using the Dewey Decimal System and an extensive card catalog that listed title, author, subject and publication date, among other information. In the 1960s the Library of Congress initiated the Machine Readable Catalog project. Under the direction of Herriette Avram, the MARC Project computerized the entire LoC book catalog.
But the project did not stop there. It was an international effort and became an ISO standard. Libraries all around the world were networked and able to browse the catalogs of any member library. Until the advent of the Internet, this was the largest public freely distributed information database in existence. And the amazing thing is that the MARC system has been augmented and is still in use today.
Babel
Compare this accomplishment to the state of metadata standards in broadcasting today. During the transition to digital production, many metadata implementations have come into being. Generally proprietary, once a system is installed, you are often locked into only that vendor’s solutions.
Compatibility and interoperability of various metadata implementations is now becoming a reality. Efforts such as the Advanced Authoring Format (AAF) and the Material eXchange Format (MXF) are gaining widespread industry acceptance.
AAF is intended for use during production and editing. It includes a rich set of technical, descriptive and rights metadata. AAF files can reference and incorporate other AAF files. In this way a log of the creative history of the piece or clip is maintained.
MXF is a subset of AAF and intended for distribution and archive processes. Essence files are wrapped with MXF metadata. The structure of an MXF file is independent of the format of the essence. MXF files are self-contained and do not reference other external MXF files. The MXF commonality allows transfer of the file to any MXF capable device. Yet to open and use the content, an appropriate decoder must be accessible.
The SMPTE MXF Implementers Working Group is a subgroup of the SMPTE W25 Wrappers and Metadata Committee. The objectives of Working Group include:
- Promote interoperability between MXF implementations.
- Provide a platform for users and industry to pose questions and requests for guidance and best practices on MXF implementation.
- Identify areas where new MXF standards are required and provide adequate SMPTE due process specifications
- Provide Advisory notes/reports which aid the MXF implementation community.
Open source MXF tools are available.
Unique Material Identifiers (UMID) defined in SMPTE 330-2000 are another potential link through the content lifecycle. Recommended use of UMIDs is described in RP 205.
Version- International Standard Audiovisual Number (V-ISAN), ATSC A/57 identifies programs, episodes and versions of content delivered in MPEG transport streams.
In the consumer environment, various metadata schemes are proliferating. Compatibility between systems is an issue. Of paramount concern at this point in the content lifecycle is the application of rights management. But perhaps a bigger problem is long-term archival storage on media whose lifetimes are uncertain.
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