|author||Vignesh Venkatasubramanian <email@example.com>||Tue May 23 13:59:21 2023 -0700|
|committer||Vignesh Venkatasubramanian <firstname.lastname@example.org>||Thu May 25 09:44:01 2023 -0700|
Force keyframe for alpha if color is a keyframe When the encoder supports it (as of now only libaom does), disable lagged output when encoding animated images with alpha channel. When the utput of the color planes is a keyframe, force a keyframe on the alpha channel as well. While the spec does not enforce this, and the libavif decoder can handle files without this requirement just fine, this change is still an enhancement because most decoders look at whether or not the color frame is a keyframe to determine seek points. Fixes: Issue #841
This library aims to be a friendly, portable C implementation of the AV1 Image File Format, as described here:
It is a work-in-progress, but can already encode and decode all AOM supported YUV formats and bit depths (with alpha).
For now, it is recommended that you check out/use tagged releases instead of just using the master branch. I will regularly create new versions as bugfixes and features are added.
Please see the examples in the “examples” directory. If you're already building
libavif, enable the CMake option
AVIF_BUILD_EXAMPLES in order to build and run the examples too.
Building libavif requires CMake.
No AV1 codecs are enabled by default. Enable them by enabling any of the following CMake options (e.g.
AVIF_CODEC_AOMfor libaom (encoder and decoder)
AVIF_CODEC_DAV1Dfor dav1d (decoder)
AVIF_CODEC_LIBGAV1for libgav1 (decoder)
AVIF_CODEC_RAV1Efor rav1e (encoder)
AVIF_CODEC_SVTfor SVT-AV1 (encoder)
These libraries (in their C API form) must be externally available (discoverable via CMake‘s
FIND_LIBRARY) to use them, or if libavif is a child CMake project, the appropriate CMake target must already exist by the time libavif’s CMake scripts are executed.
ext/ subdirectory contains a handful of basic scripts which each pull down a known-good copy of an AV1 codec and make a local static library build. Most scripts require CMake, Ninja and NASM. dav1d uses Meson instead of CMake, and rav1e uses cargo (Rust). Check each library's documentation for an exact list of requirements.
If you want to statically link any codec into your local (static) build of libavif, building using one of these scripts and then enabling the associated
AVIF_LOCAL_* is a convenient method, but you must make sure to disable
BUILD_SHARED_LIBS in CMake to instruct it to make a static libavif library.
If you want to build/install shared libraries for AV1 codecs, you can still peek inside of each script to see where the current known-good SHA is for each codec.
A few tests written in C can be built by enabling the
AVIF_BUILD_TESTS CMake option.
The remaining tests can be built by enabling the
AVIF_ENABLE_GTEST CMake options. They require GoogleTest to be built locally with ext/googletest.cmd or installed on the system.
If you're building on Windows with Visual Studio 2022 and want to try out libavif without going through the build process, static library builds for both Debug and Release are available on AppVeyor.
libavif is written in C99.
Use clang-format to format the C sources from the top-level folder:
clang-format -style=file -i \ apps/*.c apps/shared/avifexif.* apps/shared/avifjpeg.* \ apps/shared/avifpng.* apps/shared/avifutil.* apps/shared/y4m.* \ examples/*.c include/avif/*.h src/*.c tests/*.c \ tests/gtest/*.h tests/gtest/*.cc tests/oss-fuzz/*.cc
Use cmake-format to format the CMakeLists.txt files from the top-level folder:
cmake-format -i \ CMakeLists.txt \ tests/CMakeLists.txt \ cmake/Modules/Find*.cmake \ contrib/CMakeLists.txt \ contrib/gdk-pixbuf/CMakeLists.txt \ android_jni/avifandroidjni/src/main/jni/CMakeLists.txt
Released under the BSD License.
Copyright 2019 Joe Drago. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.