This app encodes MP3 with LAME.

When NDK r28+ is installed, CMake builds libmp3lame.so and librec_lame.so
from the vendored LAME 3.100 sources under app/src/main/cpp/lame/.
LAME is LGPL. The library is a separate shared object so it can be replaced.

Until that native build is present in the APK, encoding uses Jump3r
(de.sciss:jump3r), a Java port of LAME, also LGPL.

LAME: https://lame.sourceforge.io/
Jump3r: https://github.com/Sciss/jump3r
