MP4 processing uses the unmodified @ffmpeg/ffmpeg 0.12.15 wrapper (MIT) and @ffmpeg/core 0.12.10 (GPL-2.0-or-later, with the applicable licenses of FFmpeg and its included libraries). The WASM is gzip-compressed for transport only; it is not modified.
Source references include the FFmpeg libraries and external codecs pinned by the upstream build recipe. No license rights of those components are replaced by EMX branding.