Best-of-class cross-platform performance and reliability.
Expect an order of magnitude faster performance than other packages.
Proper extraction of
- dates with correct timezone offset encoding, when available)
- latitudes & longitudes as floats (where negative values indicate west or south of the meridian)
Auditable ExifTool source code (the vendored code is checksum verified)
Automated updates to ExifTool (as new versions come out monthly)
yarn add exiftool-vendored
npm install --save exiftool-vendored
exiftool-vendored provides an installation of ExifTool relevant
for your local platform through
You shouldn't include either the
exiftool-vendored.pl as direct dependencies to your project.
See the CHANGELOG for breaking changes since you last updated.
Major version bumps
I bump the major version if there's a chance existing code might be affected.
I've been bit too many times by my code breaking when I pull in minor or patch upgrades with other libraries. I think it's better to be pessimistic in code change impact analysis: "over-promise and under-deliver" your breaking-code changes.
When you upgrade to a new major version, please take a bit more care in validating your own systems, but don't be surprised when everything still works.
There are many configuration options to ExifTool, but all values have (more or less sensible) defaults.
Those defaults have been used to create the
Feel free to review the ExifTool constructor
and override default values where appropriate if the defaults wont' work for
you, but you should use your singleton to minimize system load. Note that if you
don't use the default singleton, you don't need to
// We're using the singleton here for convenience:const exiftool = exiftool// And to verify everything is working:exiftoolversion
ExifTool.read() returns a Promise to a Tags instance. Note
that errors may be returned either by rejecting the promise, or for less
severe problems, via the
All other public ExifTool methods return
Promise<void>, and will reject
the promise if the operation is not successful.
Errors and Warnings
ExifTool has a pretty exhaustive set of error checking, and many "errors" are actually non-fatal warnings about invalid tag structures that seem to be regularly found in otherwise-not-corrupt images.
If we rejected every
write when any error happened, this would
prevent reading and/or writing to otherwise-ok files. To "demote" errors to be
warnings that don't reject the underlying task, you can provide either a
minorErrorsRegExp, or an
Either of these parameters are provided to the
Logging and events
ExifTool instances emits events for "startError", "taskError", "endError", "beforeEnd", and "end" that you can register listeners for, using on.
Extracting embedded images
Extract the low-resolution thumbnail in
path/to/image.jpg, write it to
path/to/thumbnail.jpg, and return a
Promise<void> that is fulfilled
when the image is extracted:
Preview image (only found in some images):
JpgFromRaw image (found in some RAW images):
Extract the binary value from "tagname" tag in
and write it to
dest.bin (which cannot exist already
and whose parent directory must already exist):
Note that only a portion of tags are writable. Refer to the documentation and look under the "Writable" column.
If you apply malformed values or ask to write to tags that aren't
supported, the returned
Promise will be rejected.
Only string and numeric primitive are supported as values to the object
Write a comment to the given file so it shows up in the Windows Explorer Properties panel:
Change the DateTimeOriginal, CreateDate and ModifyDate tags (using the AllDates shortcut) to 4:56pm UTC on February 6, 2016:
Always Beware: Timezones
If you edit a timestamp tag, realize that the difference between the
changed timestamp tag and the GPS value is used by
infer the timezone.
In other words, if you only edit the
CreateDate and don't edit the
timestamps, your timezone will either be incorrect or missing. See the
section about Dates below for more information.
You may find that some of your images have corrupt metadata, and that writing new dates, or editing the rotation information, for example, fails. ExifTool can try to repair these images by rewriting all the metadata into a new file, along with the original image content. See the documentation for more details about this functionality.
rewriteAllTags returns a void Promise that will be rejected if there are any
Remember to call
ExifTool processes consume system resources. If you're done with it, turn
it off with
.end(), which returns a
Promise<void> if you want to wait
for the shutdown to be complete.
If you use mocha v4 or later, and you don't call
exiftool.end(), you will find that your test suite hangs. The relevant
change is described here,
and can be solved by adding an
after block that shuts down the instance
of ExifTool that your tests are using:
// assuming your singleton is called `exiftool`
The date metadata in all your images and videos are, most likely, underspecified.
Images and videos rarely specify a time zone in their dates. If all your files were captured in your current time zone, defaulting to the local time zone is a safe assumption, but if you have files that were captured in different parts of the world, this assumption will not be correct. Parsing the same file in different parts of the world results in a different times for the same file.
Prior to version 7, heuristic 1 and 3 was applied.
As of version 7.0.0,
exiftool-vendored uses the following heuristics. The
highest-priority heuristic to return a value will be used as the timezone offset
for all datetime tags that don't already have a specified timezone.
Heuristic 1: explicit metadata
If the EXIF
TimeZoneOffset tag is present it will be applied as per the spec to
DateTimeOriginal, and if there are two values, the
ModifyDate tag as well.
Heuristic 2: GPS location
If GPS latitude and longitude is present and valid (the value of
0, 0 is
considered invalid), the
tz-lookup library will be used to determine the time
zone name for that location.
Heuristic 3: GPS timestamp delta
GPSDateTime is present, the delta with the dates found within the file, as
long as the delta is valid, is used as the timezone offset. Deltas of > 14 hours
are considered invalid.
ExifDate and ExifDateTime
Because datetimes have this optionally-set timezone, and some tags only specify
the date, this library returns classes that encode the date, the time of day, or
both, with an optional timezone and an optional tzoffset:
ExifTime. It's up to you, then, to determine what's correct for your
Note also that some smartphones record timestamps with microsecond precision
(not just millis!), and both
ExifTime have floating point
The Tags interface is
autogenerated by the
mktags script, which parses through over 6,000 unique
camera make and model images, in large part sourced from the ExifTool site.
mktags groups tags, extracts their type, popularity, and example values such
that your IDE can autocomplete.
For an example of a group of tags, see the EXIFTags interface.
Tags marked with "★★★★", like MIMEType, should be found in most files. Of the several thousand metadata tags, realize less than 50 are found generally. You'll need to do your own research to determine which tags are valid for your uses.
Note that if parsing fails (for, example, a datetime string), the raw string will be returned. Consuming code should verify both existence and type as reasonable for safety.
npm run mktags target reads all tags found in a batch of sample images and
parses the results.
Read 2236 unique tags from 3011 files.Parsing took 16191ms # win32, core i7, maxProcs 4Parsing took 27141ms # ubuntu, core i3, maxProcs 1Parsing took 12545ms # ubuntu, core i3, maxProcs 4
exiftool npm package takes 7x longer (and doesn't work on Windows):
Reading 3011 files...Parsing took 85654ms # ubuntu, core i3
Starting the perl version of ExifTool is expensive, and is especially expensive on the Windows version of ExifTool.
On Windows, for every invocation,
exiftool installs a distribution of
Perl and extracts the ~1000 files that make up ExifTool, and then runs
the perl script. Windows virus scanners prevent reads on these files while they
are scanned, which makes this approach even more costly.
-stay_open batch mode means we can reuse a single
instance of ExifTool across many requests, dropping response latency
dramatically as well as reducing system load.
To avoid overwhelming your system, the
exiftool singleton is configured with a
maxProcs set to a quarter the number of CPUs on the current system (minimally
1); no more than
maxProcs instances of
exiftool will be spawned. If the
system is CPU constrained, however, you may want a smaller value. If you have
very fast disk IO, you may see a speed increase with larger values of
maxProcs, but note that each child process can consume 100 MB of RAM.
See the CHANGELOG on github.