exiftool-vendored

exiftool-vendored

Efficient, cross-platform node access to ExifTool.

Unique Features

1. Uses -stay_open mode by default, which can be up to 60x faster than other packages*

2. Parsing of

   • dates (even though EXIF doesn't include timezone offset data)
   • latitudes & longitudes into proper floats (where negative values indicate W or S of the meridian)

3. Robust type definitions of the top 99.5% of tags used by over 3,000 different camera makes and models

4. Auditable ExifTool source code (the "vendored" code is verifiable)

5. Automated updates to ExifTool (as new versions come out monthly)

6. Tested on node v6+ on Linux, Mac, & Windows.

Installation

npm install --save exiftool-vendored

The vendored version of ExifTool relevant for your platform will be installed via platform-dependent-modules.

Usage

// `exiftool` is a singleton instance of the `ExifTool` class
import { exiftool } from "exiftool-vendored"
// ExifTool.read() returns a Promise<Tags>
exiftool.read("path/to/file.jpg").then(tags => {
  console.log(`Make: ${metadata.Make}, Model: ${metadata.Model}`)
})

Official EXIF tag names are PascalCased, like AFPointSelected and ISO. ("Fixing" the field names to be camelCase, would result in ungainly aFPointSelected and iSO atrocities).

Dates

Generally, EXIF tags encode dates and times with no timezone offset. Presumably the time is captured in local time, but this means parsing the same file in different parts of the world results in a different absolute timestamp for the same file.

Rather than returning a Date, which always includes a timezone, this library returns classes that encode the date, the time of day, or both, with an optional tzoffset. It's up to you, then to do what's right.

It's not all bad news, though! In cases where a GPS UTC timestamp is encoded with the image (like from most smartphone cameras), the timezone offset can be inferred, and will be encoded in the related ExifDates for those files.

const d /*: ExifDate*/ = metadata.DateTimeOriginal
// if you simply must have a Date
const onlyCorrectIfSmartphoneOrYouTookThePhotoInTheSameTimezoneOffsetAsItIsLocally: Date = 
  d.toDate()

stay_open

Starting the perl version of ExifTool is expensive, and is especially expensive on the Windows version of ExifTool.

On Windows, a distribution of Perl and the ~1000 files that make up ExifTool are extracted into a temporary directory for every invocation. Windows virus scanners that wedge reads on these files until they've been determined to be safe make this approach even more costly.

Using -stay_open we can reuse a single instance of ExifTool across all requests, which drops response latency dramatically.

Tags

The tags.ts file is autogenerated by parsing through images of more than 3,000 different camera makes and models taken from the ExifTool site. It groups tags, their type, frequency, and example values such that your IDE can autocomplete

Versioning

I wanted to include the ExifTool's version number explicitly in the version number, but npm requires strict compliance with SemVer. Given that ExifTool sometimes includes patch releases, there aren't always enough spots to encode an API version and the ExifTool version.

Given those constraints, version numbers follow the following scheme:

  $API.$UPDATE.$PATCH

• Breaking API changes to this package will increment API.
• Any bugfix or new release of ExifTool will increment UPDATE.
• Metadata changes or trivial bugfixes will increment PATCH.

Note that the platform dependent modules use the ExifTool version with an optional patch release.

v0.1.0

Initial Release. Packages ExifTool v10.31.

Changelog

v0.1.1

🌱✨ Initial Release. Packages ExifTool v10.31.