Realsoft 3D r3ffmpeg plugin module uses libraries from the FFmpeg project under the LGPLv2.1.
Realsoft 3D™ is a trademark of Realsoft Graphics Oy and Realsoft Oy. FFmpeg™ is a trademark of Fabrice Bellard, originator of the FFmpeg project.
As described in the FFmpeg's https://www.ffmpeg.org/legal.html / License Compliance Checklist
Realsoft 3D uses FFmpeg libraries built without "--enable-gpl" and without "--enable-nonfree" configuration option and uses only LGPL related features of FFmpeg.
Dynamic linking for linking with FFmpeg libraries is used.