XMP RDF/XML metadata parser.

Extracts a flat %{String.t() => String.t()} map keyed by /Info-compatible names ("Title", "Author", "Subject", "Description", "Creator", "Producer", "CreationDate", "ModDate", "Keywords") from a catalog /Metadata XMP packet.

Recognized namespaces (URI-based, not prefix-based)

• http://purl.org/dc/elements/1.1/ (dc) — Dublin Core
• http://ns.adobe.com/xap/1.0/ (xmp) — XMP Basic
• http://ns.adobe.com/pdf/1.3/ (pdf) — PDF
• http://www.w3.org/1999/02/22-rdf-syntax-ns# (rdf) — RDF containers

Mapping to /Info keys

• dc:title → "Title"
• dc:creator (rdf:Bag, first element only) → "Author"
• dc:subject (rdf:Bag, first element) → "Subject"
• dc:description (rdf:Alt) → "Description" (distinct from "Subject")
• xmp:CreateDate → "CreationDate"
• xmp:ModifyDate → "ModDate"
• xmp:CreatorTool → "Creator"
• pdf:Producer → "Producer"
• pdf:Keywords → "Keywords"

Error handling

Malformed XML returns {:error, :malformed_xmp} — never raises. Empty rdf:RDF document returns {:ok, %{}}.

Spec references

• PDF 1.7 (ISO 32000-1) § 14.3.2 — Metadata Streams: https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/pdfstandards/pdf/PDF32000_2008.pdf
• XMP Specification Part 1 (data model, serialization): https://github.com/adobe/xmp-docs/raw/master/XMPSpecificationPart1.pdf
• W3C RDF/XML Syntax Specification: https://www.w3.org/TR/rdf-syntax-grammar/