StreamBridge makes subtitles with FFmpeg n9.0.2 and LAME 3.100,
both under the GNU Lesser General Public License, version 2.1 (LICENSE).
The libraries in lib/ are built from their unmodified source:
  https://git.ffmpeg.org/ffmpeg.git, tag n9.0.2
  https://downloads.sourceforge.net/project/lame/lame/3.100/lame-3.100.tar.gz
You may replace them with your own build of the same versions.
