GitHub - strukturag/libheif: libheif is an HEIF and AVIF file format decoder and encoder.

libheif

libheif is an ISO/IEC 23008-12 HEIF and AVIF (AV1 Image File Format) file format decoder and encoder. HEIC and AVIF are new image file formats employing HEVC (H.265) or AV1 image coding, respectively, for the best compression ratios currently possible.

On top of HEIC and AVIF, libheif also supports HEIF images coded with VVC, AVC, JPEG, JPEG-2000, and ISO/IEC 23001-17. The ISO/IEC 23001-17 codec is built-in to libheif and allows to store lossless images and video in many different formats.

libheif makes use of various codec libraries for implementing each compression format. For HEIC, libde265 is used by default for decoding and x265 for encoding. For AVIF, libaom, dav1d, svt-av1, or rav1e are used as codecs. libheif can be built with a subset of the supported codecs to keep the size and the number of dependencies low. Alternatively, the libheif codecs can also be built as separate plugins that can be installed and loaded dynamically when used.

Supported features

libheif has support for:

HEIC, AVIF, VVC, AVC, JPEG-in-HEIF, JPEG2000, uncompressed (ISO/IEC 23001-17:2024) codecs
alpha channels, depth maps, thumbnails, auxiliary images
multiple images in a file
HEIF image sequences and MP4 video, including alpha channels
tiled images with decoding individual tiles and encoding tiled images by adding tiles one after another
HDR images, correct color transform according to embedded color profiles
image transformations (crop, mirror, rotate), overlay images
plugin interface to add alternative codecs
reading EXIF and XMP metadata
region annotations and mask images
streaming of images and video by requesting data from the network through a data-reader interface

Supported codecs:

Format	Decoders	Encoders
HEIC	libde265, ffmpeg	x265, kvazaar
AVIF	libaom, dav1d	libaom, rav1e, svt-av1
VVC	vvdec	vvenc, uvg266
AVC	openh264, ffmpeg	x264
JPEG	libjpeg(-turbo)	libjpeg(-turbo)
JPEG2000	OpenJPEG	OpenJPEG
HTJ2K	OpenJPEG	OpenJPH
uncompressed	built-in	built-in

Programming API

The library has a C API for easy integration and wide language support.

The decoder automatically supports both HEIF and AVIF (and the other compression formats) through the same API. The same decoding code can be used to decode any of them. The encoder can be switched between HEIF and AVIF simply by setting heif_compression_HEVC or heif_compression_AV1 to heif_context_get_encoder_for_format(), or using any of the other compression formats.

Loading the primary image from a HEIF file

heif_context* ctx = heif_context_alloc();
heif_context_read_from_file(ctx, input_filename, nullptr);

// get a handle to the primary image
heif_image_handle* handle;
heif_context_get_primary_image_handle(ctx, &handle);

// decode the image and convert colorspace to RGB, saved as 24bit interleaved
heif_image* img;
heif_decode_image(handle, &img, heif_colorspace_RGB, heif_chroma_interleaved_RGB, nullptr);

int stride;
const uint8_t* data = heif_image_get_plane_readonly(img, heif_channel_interleaved, &stride);

// ... process data as needed ...

// clean up resources
heif_image_release(img);
heif_image_handle_release(handle);
heif_context_free(ctx);

Writing a HEIF file

heif_context* ctx = heif_context_alloc();

// get the default encoder
heif_encoder* encoder;
heif_context_get_encoder_for_format(ctx, heif_compression_HEVC, &encoder);

// set the encoder parameters
heif_encoder_set_lossy_quality(encoder, 50);

// encode the image
heif_image* image; // code to fill in the image omitted in this example
heif_context_encode_image(ctx, image, encoder, nullptr, nullptr);

heif_encoder_release(encoder);

heif_context_write_to_file(ctx, "output.heic");

heif_context_free(ctx);

Get the EXIF data from a HEIF file

heif_item_id exif_id;

int n = heif_image_handle_get_list_of_metadata_block_IDs(image_handle, "Exif", &exif_id, 1);
if (n==1) {
  size_t exifSize = heif_image_handle_get_metadata_size(image_handle, exif_id);
  uint8_t* exifData = malloc(exifSize);
  struct heif_error error = heif_image_handle_get_metadata(image_handle, exif_id, exifData);
}

Image sequences, MP4 video

See the image sequences API documentation.

Since HEIF image sequences are very similar to MP4 video, libheif can also read and write MP4 video (without audio) with all supported codecs.

High-resolution tiled images

For very large resolution images, it is not always feasible to process the whole image. In this case, libheif can process the image tile by tile. See the image tiling API documentation.

More documenation

See the header files for the complete C API.

There is also a C++ API which is a header-only wrapper to the C API. Hence, you can use the C++ API and still be binary compatible. Code using the C++ API is much less verbose than using the C API directly.

Compiling

This library uses the CMake build system (the earlier autotools build files have been removed in v1.16.0).

For a minimal configuration, we recommend to use the codecs libde265 and x265 for HEIC and AOM for AVIF. Make sure that you compile and install libde265 first, so that the configuration script will find this. Also install x265 and its development files if you want to use HEIF encoding, but note that x265 is GPL. An alternative to x265 is kvazaar (BSD).

The basic build steps are as follows (--preset argument needs CMake >= 3.21):

mkdir build
cd build
cmake --preset=release ..
make

There are CMake presets to cover the most frequent use cases.

release: the preferred preset which compiles all codecs as separate plugins. If you do not want to distribute some of these plugins (e.g. HEIC), you can omit packaging these.
release-noplugins: this is a smaller, self-contained build of libheif without using the plugin system. A single library is built with support for HEIC and AVIF.
testing: for building and executing the unit tests. Also the internal library symbols are exposed. Do not use for distribution.
fuzzing: all codecs like in release build, but configured into a self-contained library with enabled fuzzers. The library should not distributed.

You can optionally adapt these standard configurations to your needs. This can be done, for example, by calling ccmake . from within the build directory.

CMake configuration variables

Libheif supports many different codecs. In order to reduce the number of dependencies and the library size, you can choose which of these codecs to include. Each codec can be compiled either as built-in to the library with a hard dependency, or as a separate plugin file that is loaded dynamically.

For each codec, there are two configuration variables:

WITH_{codec}: enables the codec
WITH_{codec}_PLUGIN: when enabled, the codec is compiled as a separate plugin.

In order to use dynamic plugins, also make sure that ENABLE_PLUGIN_LOADING is enabled. The placeholder {codec} can have these values: LIBDE265, X265, AOM_DECODER, AOM_ENCODER, SvtEnc, DAV1D, OpenH264, X264, FFMPEG_DECODER, JPEG_DECODER, JPEG_ENCODER, KVAZAAR, OpenJPEG_DECODER, OpenJPEG_ENCODER, OPENJPH_ENCODER, VVDEC, VVENC, UVG266, WEBCODECS.

Further options are:

WITH_UNCOMPRESSED_CODEC: enable support for uncompressed images according to ISO/IEC 23001-17:2024. This is experimental and not available as a dynamic plugin. When enabled, it adds a dependency to zlib, and optionally will use brotli.
WITH_HEADER_COMPRESSION: enables support for compressed metadata. When enabled, it adds a dependency to zlib. Note that header compression is not widely supported yet.
WITH_LIBSHARPYUV: enables high-quality YCbCr/RGB color space conversion algorithms (requires libsharpyuv, e.g. from the third-party directory).
ENABLE_EXPERIMENTAL_FEATURES: enables functions that are currently in development and for which the API is not stable yet. When this is enabled, a header heif_experimental.h will be installed that contains this unstable API. Distributions that rely on a stable API should not enable this.
ENABLE_MULTITHREADING_SUPPORT: can be used to disable any multithreading support, e.g. for embedded platforms.
ENABLE_PARALLEL_TILE_DECODING: when enabled, libheif will decode tiled images in parallel to speed up compilation.
PLUGIN_DIRECTORY: the directory where libheif will search for dynamic plugins when the environment variable LIBHEIF_PLUGIN_PATH is not set.
WITH_REDUCED_VISIBILITY: only export those symbols into the library that are public API. Has to be turned off for running some tests.

macOS

Install dependencies with Homebrew

brew install cmake make pkg-config x265 libde265 libjpeg libtool

Configure and build project (--preset argument needs CMake >= 3.21):
```
mkdir build
cd build
cmake --preset=release ..
./configure
make
```

Windows

You can build and install libheif using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.bat
./vcpkg integrate install
./vcpkg install libheif

The libheif port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Adding libaom encoder/decoder for AVIF

Run the aom.cmd script in the third-party directory to download libaom and compile it.

When running cmake or configure, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/aom/dist/lib/pkgconfig.

Adding rav1e encoder for AVIF

Install cargo.
Install cargo-c by executing

cargo install --force cargo-c

Run the rav1e.cmd script in the third-party directory to download rav1e and compile it.

When running cmake, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/rav1e/dist/lib/pkgconfig.

Adding dav1d decoder for AVIF

Install meson.
Run the dav1d.cmd script in the third-party directory to download dav1d and compile it.

When running cmake, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/dav1d/dist/lib/x86_64-linux-gnu/pkgconfig.

Adding SVT-AV1 encoder for AVIF

You can either use the SVT-AV1 encoder libraries installed in the system or use a self-compiled current version. If you want to compile SVT-AV1 yourself,

Run the svt.cmd script in the third-party directory to download SVT-AV1 and compile it.

You have to enable SVT-AV1 with CMake.

When running cmake, make sure that the environment variable PKG_CONFIG_PATH includes the absolute path to third-party/SVT-AV1/Build/linux/install/lib/pkgconfig. You may have to replace linux in this path with your system's identifier.

Codec plugins

Starting with v1.14.0, each codec backend can be compiled statically into libheif or as a dynamically loaded plugin. You can choose this individually for each codec backend in the CMake settings using WITH_{codec}_PLUGIN options. Compiling a codec backend as dynamic plugin will generate a shared library that is installed in the system together with libheif. The advantage is that only the required plugins have to be installed and libheif has fewer dependencies.

The plugins are loaded from the colon-separated (semicolon-separated on Windows) list of directories stored in the environment variable LIBHEIF_PLUGIN_PATH. If this variable is empty, they are loaded from a directory specified in the CMake configuration. You can also add plugin directories programmatically.

Codec specific notes

The FFMPEG decoding plugin can make use of h265 hardware decoders. However, it currently (v1.17.0, ffmpeg v4.4.2) does not work correctly with all streams. Thus, libheif still prefers the libde265 decoder if it is available.
The "webcodecs" HEVC decoder can only be used in emscripten builds since it uses the web-browser's API. For the same reason, it is not available as a plugin.

Usage

libheif comes with a set of command line tools:

heif-dec for decoding HEIF images to JPEG or PNG. It can also decode image sequences or MP4 video.
heif-enc for encoding JPEG, PNG, TIFF, or Y4M images to HEIF images, image sequences or MP4 video.
heif-info for getting some overview information about the HEIF file or (using the -d option) to dump the full box structure of the file.
heif-view for displaying HEIF image sequences

`heif-enc` command line tool

You can find more documentation for the heif-enc tool on the wiki page.

Security limits

Libheif defines some security limits that prevent that very large images exceed the available memory or malicious input files can be used for a denial-of-service attack. When you are programming against the libheif API and you need to process very large images, you can set the heif_security_limits individually. When using heif-dec, there is the option to switch off security limits with --disable-limits. In case a third-party software is using libheif, but does not give you a way to switch off the limits, you can set an environment variable LIBHEIF_SECURITY_LIMITS=off to switch it off globally. Clearly, only do this if you know what you are doing and you are sure not to process malicious files.

Encoder benchmark

A current benchmark of the AVIF encoders (as of 14 Oct 2022) can be found on the Wiki page AVIF encoding benchmark.

Language bindings

.NET Platform (C#, F#, and other languages): libheif-sharp
C++: part of libheif
Go: libheif-go, the wrapper distributed with libheif is deprecated
JavaScript: by compilation with emscripten (see below)
NodeJS module: libheif-js
Python: pyheif, pillow_heif
Rust: libheif-sys
Swift: libheif-Xcode
JavaFX: LibHeifFx

Languages that can directly interface with C libraries (e.g., Swift, C#) should work out of the box.

Compiling to JavaScript / WASM

libheif can also be compiled to JavaScript using emscripten. It can be built like this (in the libheif directory):

mkdir buildjs
cd buildjs
USE_WASM=0 ../build-emscripten.sh ..

Set USE_WASM=1 to build with WASM output. See the build-emscripten.sh script for further options.

Online demo

Check out this online demo. This is libheif running in JavaScript in your browser.

Example programs

Some example programs are provided in the examples directory. The program heif-dec converts all images stored in an HEIF/AVIF file to JPEG or PNG. heif-enc lets you convert JPEG files to HEIF/AVIF. The program heif-info is a simple, minimal decoder that dumps the file structure to the console.

For example convert example.heic to JPEGs and one of the JPEGs back to HEIF:

cd examples/
./heif-dec example.heic example.jpeg
./heif-enc example-1.jpeg -o example.heif

In order to convert example-1.jpeg to AVIF use:

./heif-enc example-1.jpeg -A -o example.avif

There is also a GIMP plugin using libheif here.

HEIF/AVIF thumbnails for the Gnome desktop

The program heif-thumbnailer can be used as an HEIF/AVIF thumbnailer for the Gnome desktop. The matching Gnome configuration files are in the gnome directory. Place the files heif.xml and avif.xml into /usr/share/mime/packages and heif.thumbnailer into /usr/share/thumbnailers. You may have to run update-mime-database /usr/share/mime to update the list of known MIME types.

gdk-pixbuf loader

libheif also includes a gdk-pixbuf loader for HEIF/AVIF images. 'make install' will copy the plugin into the system directories. However, you will still have to run gdk-pixbuf-query-loaders --update-cache to update the gdk-pixbuf loader database.

Software using libheif

Packaging status

License

The libheif is distributed under the terms of the GNU Lesser General Public License. The sample applications are distributed under the terms of the MIT License.

See COPYING for more details.