Complete corresponding source of the ffmpeg.exe inside Live6ix.exe from release ffmpeg-26327c8-7-1
(FFmpeg n9.0.2-22-g46d8f462ee with gfxcapture-dup-frames.patch, only the components the app uses).

build.sh                      the build script (runs as root in Debian forky)
sources.txt                   every source it uses, with sha256: all of them are in ../../ and ../../deps/
gfxcapture-dup-frames.patch   our change to FFmpeg (gfxcapture's dup_frames option)

Build: put the three files in app/ffmpeg/ of an empty directory, then from that directory
  docker run --rm -v "$PWD:/repo" -w /repo debian:forky@sha256:716a7ceeaf1557c357a3c484839176dab750fbda0c5d0530dbbb18f94ccf826b bash app/ffmpeg/build.sh