GIF compression engine: licenses and source
Our browser compression engine is built from FFmpeg 5.1.4 and ffmpeg.wasm sources. The engine runs as a separate WebAssembly file on your device.
- FFmpeg is copyright its authors and is built here under the GNU LGPL 2.1 or later. The build enables no GPL components or external codec libraries.
- The ffmpeg.wasm wrapper and build project are copyright © 2019 Jerome Wu and contributors; see the MIT license. The bundled FFmpeg command-line source files retain their own notices.
Source and build instructions
Download FFmpeg 5.1.4 source, ffmpeg.wasm source and bindings, the build script and modified link script. The link script removes SDL and postproc from the upstream script because this build does not use them.
Extract both source archives. Activate Emscripten SDK 3.1.40, set FFMPEG_DIR and WRAPPER_DIR to the extracted directories and OUTPUT_DIR to a writable directory, then run bash build.sh. The build script modifies the extracted FFmpeg directory. Emscripten sources and notices are available from its 3.1.40 source tree.
The replaceable distributed engine files are ffmpeg-core.js and ffmpeg-core.wasm.