XMP Specification Part 3: Storage in Files - Adobe

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3.2.1 User-defined keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.2.2 Resolving metadata conflicts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.3 Native metadata in dynamic media formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.3.1 Native metadata in ASF (WMA, WMV). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.3.2 Native metadata in AVI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.3.3 Native metadata in MPEG-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.3.4 Native metadata in WAV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.4 Native metadata in digital photography formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.4.1 Reconciliation issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 3.4.2 Encoding of text in metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 4 Digital photography native metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 4.1 Metadata storage in native formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.1.1 TIFF metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.1.2 Exif metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.1.3 Photoshop image resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.1.4 IPTC (IIM) metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.2 Reconciling metadata properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 4.2.1 Photoshop image resources for metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 4.2.2 IPTC DataSets for metadata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.2.3 TIFF and Exif tags for metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.3 Metadata storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 4.3.1 Metadata storage in JPEG files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.3.2 Metadata storage in Photoshop files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.3.3 Metadata storage in Mac OS file resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 4 ©Adobe Systems Incorporated, 2010
Preface This document set provides a complete specification for the Extensible Metadata Platform (XMP), which provides a standard format for the creation, processing, and interchange of metadata, for a wide variety of applications. The specification has three parts: • Part 1, Data Model, Serialization, and Core Properties, covers the basic metadata representation model that is the foundation of the XMP standard format. The data model prescribes how XMP metadata can be organized; it is independent of file format or specific usage. The serialization model prescribes how the data model is represented in XML, specifically RDF/XML. Core properties are those XMP properties that have general applicability across a broad range of resources; these include general-purpose namespaces such as Dublin Core. This document also provides details needed to implement a metadata manipulation system such as the XMP Toolkit (which is available from Adobe®). • Part 2, Additional Properties, provides detailed property lists and descriptions for standard XMP metadata namespaces beyond the core properties; these include special-purpose namespaces for Adobe applications such as Adobe Photoshop®. It also provides information on extending existing namespaces and creating new namespaces. • Part 3, Storage in Files, provides information about how serialized XMP metadata is packaged into XMP packets and embedded in different file formats. It includes information about how XMP relates to and incorporates other metadata formats, and how to reconcile values that are represented in multiple metadata formats. About this document This document, Adobe XMP Specification Part 3: Storage in Files, describes how XMP metadata is embedded within various file formats. This includes information about the reconciliation of XMP metadata with other forms of metadata, referred to as native (or sometimes legacy) metadata. The intended audience of this document is developers writing file I/O code, users who need to understand the relationship between XMP and native metadata, or others requiring detailed knowledge of file content. How this document is organized This document has the following sections: • “Introduction” provides an overview of the issues and problems associated with storing metadata in or with different file formats. It includes an introduction to the subject of native metadata formats, and a discussion of external metadata storage. • 1, “XMP packets”, describes the format of the XMP packet, which wraps serialized XMP for storage in files. • 2, “Embedding XMP metadata in application files”, provides basic information about how XMP packets are embedded in various file formats. • 3, “Handling native metadata”, explains general policies of how to reconcile metadata values among XMP and native metadata formats. It provides details of native metadata for simpler cases, and introduces the complexities of native metadata for the digital-photography formats (JPEG, TIFF, and PSD). • 4, “Digital photography native metadata”, provides details of metadata formats used in the digitalphotography formats (TIFF/Exif, IPTC, and PSIR), and specifics of how properties in those formats map to XMP properties. Document history This release of this document (April 2010) has changed in these ways since the previous release (2008, SDK 4.4.2): • Placement rules clarified for XMP and PSIR/IPTC in JPEG files. • Generic and specific metadata reconciliation policies modified to reflect Metadata Working Group (MWG) guidelines. ©Adobe Systems Incorporated, 2010 5
Page 1 and 2: XMP SPECIFICATION PART 3 STORAGE IN
Page 3: Contents 1 XMP packets. . . . . . .
Page 7 and 8: Introduction This document discusse
Page 9 and 10: 1 XMP packets The XMP packet wrappe
Page 11 and 12: 1.1.2 XMP data The bytes of the XMP
Page 13 and 14: The scanner now has enough informat
Page 15 and 16: 2 Embedding XMP metadata in applica
Page 17 and 18: accordingly, eventually arriving so
Page 19 and 20: Byte offset, length 2, 2 bytes 2 +
Page 21 and 22: NOTE TIFF, JPEG, and PSD share comp
Page 23 and 24: 4, 4bytes Offset of the first (0th)
Page 25 and 26: • ASF (WMA, WMV) • AVI • FLV
Page 27 and 28: There appear to be no uses in ASF o
Page 29 and 30: 2.2.4 MOV (QuickTime) The QuickTime
Page 31 and 32: An SWF file consists of a file head
Page 33 and 34: In this example, the files 00001.mp
Page 35 and 36: C0002M01.XMP The top-level folder M
Page 37 and 38: 2.4.2.1 Finding XMP in an InDesign
Page 39 and 40: fSequenceNumber The master page seq
Page 41 and 42: TIFF, JPEG, and PSD share complex i
Page 43 and 44: 2.5.2 XML XMP metadata, because it
Page 45 and 46: The marker must be at the beginning
Page 47 and 48: 2.6.2.1.4Avoiding name conflicts In
Page 49 and 50: into the PDF document information d
Page 51 and 52: 3 Handling native metadata There is
Page 53 and 54: 3.1.3 Use of native metadata digest
Page 55 and 56:
The ASF specification says that the
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A known genre should be mapped to X
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• In JPEG, the APPn sections also
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4 Digital photography native metada
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The image resources need not be sor
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Table 30 — Photoshop image resour
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2:20 photoshop:SupplementalCategori
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The encoding header is the first 8
Page 71 and 72:
Table 39 — Mapping of outer TIFF
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Table 40 — Mapping of inner Exif
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TIFF Tag 33723 in the 0th IFD; Phot
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As mentioned earlier, the IFDs used
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Each additional item has the struct
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XMP Specification Part 3: Storage in Files - Adobe

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