WebP format is not supported by exif

[balping]

Description

The following code contains a sample webp image with exif metadata embedded. I can read out this data with exiv2 under linux:

$ exiv2 -pe sample.webp 
Exif.Image.ImageWidth                        Long        1  100
Exif.Image.ImageLength                       Long        1  100
Exif.Image.BitsPerSample                     Short       3  8 8 8
Exif.Image.ImageDescription                  Ascii      18  Created with GIMP
Exif.Image.XResolution                       Rational    1  300/1
Exif.Image.YResolution                       Rational    1  300/1
Exif.Image.ResolutionUnit                    Short       1  2
Exif.Image.Software                          Ascii      11  GIMP 3.0.4
Exif.Image.DateTime                          Ascii      20  2025:09:21 15:30:30
Exif.Image.ExifTag                           Long        1  250
Exif.Photo.DateTimeOriginal                  Ascii      20  2025:09:21 15:29:27
Exif.Photo.DateTimeDigitized                 Ascii      20  2025:09:21 15:29:27
Exif.Photo.OffsetTime                        Ascii       7  +02:00
Exif.Photo.OffsetTimeOriginal                Ascii       7  +02:00
Exif.Photo.OffsetTimeDigitized               Ascii       7  +02:00
Exif.Photo.UserComment                       Undefined  25  Created with GIMP
Exif.Photo.ColorSpace                        Short       1  1
Exif.Image.GPSTag                            Long        1  430
Exif.GPSInfo.GPSAltitude                     Rational    1  0/100
Exif.Image.DateTimeOriginal                  Ascii      20  2025:09:21 15:29:27

However the php exif extension does not support webp images:

<?php

// $exif = exif_read_data('sample.webp');

$exif = exif_read_data('data://text/plain;base64,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');

var_dump($exif);

Resulted in this output:

PHP Warning:  exif_read_data(): File not supported in exiftest.php on line 5
bool(false)

But I expected this output instead:

Full EXIF data, similar to the output produced by exiv2.

PHP Version

PHP 8.4.12 (cli) (built: Aug 28 2025 15:30:21) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.4.12, Copyright (c) Zend Technologies
    with Xdebug v3.4.5, Copyright (c) 2002-2025, by Derick Rethans

Operating System

No response

[dtdesign]

@balping The exif_read_data() function does not rely on any library and instead contains a hand-rolled EXIF parser just for JPEGs.

We ran into the same issue of being unable to process EXIF data on the server and extracting them in the client with JS is also painful. Even if you could extract the binary blob using JS, you cannot parse it on the server because exif_read_data() expects either a resource or a binary string of a JPEG that contains the EXIF data.

As a result we have developed a library that is able to process WebP images including the ability to seamless extract and parse EXIF data. It actually relies on exif_read_data() by abusing a tiny JPEG that serves as a host. The library will be used in the upcoming version of our software but is available on Packagist already:

https://packagist.org/packages/woltlab/webp-exif

The library itself is hosted on GitHub at https://github.com/WoltLab/webp-exif, supports PHP 8.1+, 100% test coverage and passes PHPStan level 10. The cherry on top is the MIT license so by all means do whatever you want with it! :)

PS: The library is build for correctness and will refuse to work with malformed WebP files. The reason being that it supports reading and writing of segments that compose a WebP file and we cannot risk damaging files, for example, when stripping EXIF data.