1. Addressing Metadata in the MPEG-21 and PDF-A ISO Standards NISO Workshop: Metadata on the Cutting Edge May 2004 William G. LeFurgy U.S. Library of Congress wlef@loc.gov

2. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata2 Presentation Overview Outline metadata approaches in two developing International Organization for Standardization specifications: –MPEG-21 (ISO 21000) –PDF-A (ISO 19005) Highlight some practical advantages and disadvantages of both My personal views, not those of LC

3. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata3 Issues to Keep in Mind Specs are in process: parts of MPEG-21 await initial approval; PDF-A is not yet approved Limited implementation experience Different communities have not yet compared different standards in detail Landscape is sure to change over next several years

4. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata4 MPEG Background Series of standards from Moving Picture Experts Group MPEG-1, -2: Coding methods to compress A/V streams (DVD, digital TV, MP3 audio) MPEG-4: Compression plus ability to interact with A/V objects (Quicktime 6, iTunes AAC) MPEG-7: Standard way to represent/bundle multimedia objects using XML; useful for indexing, searching, distributing content

5. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata5 MPEG-21 Overview Builds on MPEG-7 use of XML to define/constrain/bundle multimedia objects (text, video, audio, etc.) Also defines how any kind of user can interact with content A comprehensive framework to enable interoperable but controlled use of content from creation, distribution, and consumption Protection of commercial IP rights is central

6. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata6 MPEG-21 Features Multiple modular parts Part 2, Digital Item Declaration Language (DIDL) uses XML to express content elements, e.g.: –Container (items grouped as a logical package) –Item (a logical work) –Statement (descriptive, administrative metadata) Part 3, Digital Item Identification states how to link unique identifiers to items

7. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata7 From: http://www.chiariglione.org/mpeg/standards/mpeg-21/image004.gif

8. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata8 MPEG-21 Rights Expression Language Part 5, Details “machine readable language to declare rights and permissions” Aims to support end-to-end interoperability with access and use controls Uses ContentGuard/Microsoft XrML (Extensible Rights Markup Language) spec

9. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata9 The REL Data Model From: http://www.chiariglione.org/mpeg/standards/mpeg-21/image008.gif

10. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata10 Digital Repositories and MPEG-21 Los Alamos National Laboratory uses spec to represent and manage complex digital objects Serves to package objects for repository submission, storage, and dissemination as outlined in OAIS model Accommodates existing metadata records and enables capture of life cycle management metadata Also used in conjunction with NISO OpenURL and OAI-PMH

11. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata11 MPEG-21 Pros and Cons Pro –International standard –Broad commercial support for earlier MPEG specs –Packages any type of complex digital object per OAIS –Powerful and flexible means to express descriptive, structural, administrative, and other metadata Con –Complex and highly technical –Few tools currently exist –Unclear now the extent to which spec will be adopted –Strong emphasis on commercial rights protection?

12. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata12 PDF-A Background Goal is to define use of Adobe PDF version 1.4 for long-term preservation purposes Effort stems from extensive use of PDF as primary format for records and documents that require long-term retention Standard is being developed by ISO working group with representatives from government, industry, academia

13. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata13 PDF-A Overview Defines a constrained version of PDF that should remain viable for many years: –Audio and video content are forbidden –Javascript and executable file launches are prohibited –All fonts must be embedded and also must be legally embeddable for unlimited, universal rendering –Colorspaces specified in a device-independent manner –Encryption is disallowed Requires a standards-based approach to metadata

14. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata14 PDF-A Metadata Features Based on Adobe Extensible Metadata Platform (XMP) XMP is based on Resource Description Framework (RDF) and XML specifications Adobe has defined core schemas (descriptive, media management, rights management, etc.) XMP permits broad extensibility for defining customized schemas Provides for embedding XML text packets in binary PDF files

15. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata15 Digital Repositories and PDF-A Not yet tested in a repository context… …But repositories are (or will soon be) rife with PDF files from e-government, online publishing, and business workflow activities PDF-A addresses conceptual repository needs for a stable file format with rich descriptive and administrative metadata

16. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata16 PDF-A Pros and Cons Pro –International standard (pending) –Broad commercial support for Adobe PDF spec –Meets many user needs across the digital life cycle –Powerful and flexible means to express descriptive and administrative metadata Con –Complex and highly technical –Few tools currently exist –Unclear now the extent to which spec will be adopted –XMP limitations for validating metadata –Requires another standard to package items per OAIS

17. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata17 Further Information: MPEG-21 MPEG-21 Overview v.5: http://www.chiariglione.org/mpeg/standards/mpeg-21/mpeg-21.htm Using MPEG-21 DIDL to Represent Complex Digital Objects in the Los Alamos National Laboratory Digital Library http://tinyurl.com/22e65 Using MPEG-21 DIP and NISO OpenURL for the Dynamic Dissemination of Complex Digital Objects in the Los Alamos National Laboratory Digital Library http://tinyurl.com/2klwz From MPEG-1 to MPEG-21 http://tinyurl.com/3brc8

18. NISO Workshop, May 2004MPEG-21 and PDF-A Metadata18 Further Information: PDF-A PDF-A Committee web site: http://www.aiim.org/standards.asp?ID=25013 PDF-A: Developing a File Format for Long-Term Preservation http://www.rlg.org/preserv/diginews/diginews7-6.html#feature1 Adobe XMP web site http://www.adobe.com/products/xmp/main.html