MP3 encoding uses Alex Zhukov’s unmodified lamejs 1.2.1, a JavaScript port of the LAME MP3 encoder, distributed separately under LGPL-3.0. The encoder can be replaced at vendor/lame.min.js.
LGPL v3 · GPL v3 · Upstream notice · Complete source package
WAV export is encoded directly from the stereo audio mix. All exports are processed locally on your device.
MP4 encoding uses Mediabunny 1.65.0 (MPL-2.0) and its AAC encoder extension (MPL-2.0). The AAC encoder includes FFmpeg AAC code under LGPL-2.1 (license; additional notices).