> vcpkg install ffmpeg[opencl]:x64-windows-static
...
-- Building ffmpeg for Release
CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:72 (message):
    Command failed: D:/vcpkg/downloads/tools/msys2/msys64/usr/bin/bash.exe --noprofile --norc D:/vcpkg/ports/ffmpeg\build.sh D:/vcpkg/buildtrees/ffmpeg/x64-windows-static-rel D:/vcpkg/buildtrees/ffmpeg/src/n4.2-02d8c63f80 D:/vcpkg/packages/ffmpeg_x64-windows-static "--enable-asm --enable-yasm --disable-doc --enable-debug --enable-runtime-cpudetect --disable-openssl --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-libvpx --disable-libx264 --enable-opencl --disable-lzma --disable-bzlib --enable-avresample  --extra-cflags=-DHAVE_UNISTD_H=0  --extra-cflags=-MT --extra-cxxflags=-MT"
    Working Directory: D:/vcpkg/buildtrees/ffmpeg/x64-windows-static-rel
    Error code: 1
...
> type buildtrees\ffmpeg\build-x64-windows-static-rel-out.log
=== CONFIGURING ===
ERROR: opencl not found
...