FFmpeg is distributed under the terms of the GNU Lesser General Public License (LGPL), version 2.1:
https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html

FFmpeg is a trademark of Fabrice Bellard, originator of the FFmpeg project.
Copyright (c) 2000-2019 Fabrice Bellard, et al.
For more information, see https://www.ffmpeg.org/.

FFmpeg-master.zip contains full source code of FFmpeg v4.1. FFmpeg source code originally downloaded from: https://github.com/FFmpeg/FFmpeg
Branch: Master
Date: 05-June-2019

FFmpeg (FFmpeg dynamic libraries) distributed with CAST's Software was built using the following configuration options:
--target-os=win64 --arch=amd64 --toolchain=msvc --disable-static --enable-shared --x86asmexe=yasm.exe

See file FFmpeg-master/configure for default configuration options not specified above.