Metadata: The keys to the kingdom
Jun 7, 2006 1:38 PM, Transition to Digital e-newsletter
A rose is a rose
Key to storage and retrieval is metadata. Standardization of metadata terminology is the means to interoperability among systems that use content, such as MAMs, editing applications and eventually home digital networks.
To attain this ideal, SMPTE has implemented a Metadata Registry. The EBU/SMPTE Task Force, who’s final report was published in 1998 introduced the concept of content = essence + metadata, that is now central to the production profession and infrastructure. Today, W25 carries on the work.
The SMPTE Registration Authority (http://www.smpte-ra.org/) provides a public repository for several labeling standards, including the SMPTE Metadata Registry, SMPTE Unique Material Identifiers (UMIDs), and MPEG Format Identifiers.
Communication
eXtensible Markup Language (XML) is the communication protocol used to convey metadata among applications. Rapidly becoming the document industry metadata exchange standard, XML text files are both human and machine-readable.
Key Length Value (KLV) SMPTE 336M syntax is now expressed in XML. Self-documenting XML files communicate technical, descriptive, administration and rights information between applications and equipment.
Publicly accessible metadata registries are necessary to facilitate interoperability of metadata dictionaries. By including dictionary references, access information and registry location, a cataloging application can find relevant metadata and the sought after material.
For libraries and long-term preservation of digital assets, the Open Archival Information System (OAIS) is developing a reference model to enable exchange of metadata among registries. If MPEG-7 and MPEG-21 attain the global acceptance and longevity that MARC has, the issue of metadata compatible schemes may vanish.
Traversing the chain
How is all this information linked through the media chain? How does a download purchase of content by a consumer, propagate metadata and transaction information up the chain such that rights information in the original AAF file generates a payment to the copyright holder?
Consider a consumer watching his favorite situation comedy. For the moment, let us assume that a means to convey information to the program originator exists. We will also assume that iTV T-commerce exists. The consumer loves a song that is played in the show. Using iTV features, a window with a purchase song button is displayed. At this moment, the receiver must know, via metadata in the delivered content 1) what song will be downloaded and 2) what program contains the song. The song info can be time code indexed in program metadata. The program can be identified by its V-ISAN.
In this example, the V-ISAN metadata field is the link from the consumer through the distribution channel, which carries the V-ISAN. The MXF file that wrapped the essence transmitted contains the V-ISAN in its metadata and is linked to the ISO ISAN. Moving back up the content lifecycle chain, the ISAN points to an AAF file that contains information necessary to locate any audio or video element contained in the program. Ultimately, the song in the program is reached.
Program (V-ISAN) and song (Title) information have been communicated from the consumer to the program originator via the backchannel. The content provider must now correlate the V-ISAN with the ISAN and then locate the AAF file that contains (or point to) the song essence and its metadata.
Rights information and usage fee payment directions facilitate automated royalty payment to the songwriter and publisher. The consumer completes the transaction in a Web-like transaction session. The song is then downloaded.
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