Multi-Crate Tag Database Architecture

Overview

The OxiDex tag database is split into 6 domain-specific crates for faster compilation:

• exiftool-tags-core - Universal standards (EXIF, XMP, IPTC, GPS)
• exiftool-tags-camera - Camera manufacturers (Canon, Nikon, Sony, etc.)
• exiftool-tags-media - Audio/video formats (QuickTime, FLAC, MPEG)
• exiftool-tags-image - Image formats (PNG, GIF, JPEG2000)
• exiftool-tags-document - Document formats (PDF, fonts, archives)
• exiftool-tags-specialty - Medical/scientific (DICOM, FITS, MRC)
• exiftool-tags - Facade crate re-exporting everything

Data Format

Tags are stored as YAML files embedded at compile time and parsed lazily:

tables:
  - name: Canon
    tags:
      - id: "0x0001"
        name: CanonCameraSettings
        writable: true
        type: int16u
        description: "Camera settings"

Build Process

1. build.rs downloads ExifTool Perl source
2. Parses tag definitions from Perl modules
3. Routes tags to appropriate domain based on table name
4. Generates compact YAML files (not Rust code)
5. Each crate embeds YAML with include_str!()
6. Runtime lazy parsing on first access

Performance

• Build time: 3-5x faster vs monolithic crate
• Parallelization: 6 crates compile simultaneously
• Incremental: Changes to main code don't trigger tag recompilation
• Runtime overhead: <10ms one-time YAML parsing

API Compatibility

The facade crate maintains full API compatibility:

use exiftool_tags::*;

// Global search across all domains
let table = get_tag_table("Canon");

// Domain-specific access
let canon = camera::get_tag_table("Canon");