[qyot27]

It's not entirely the way I wrote the guide. The guide assumes you're building FFmpeg for a distro that doesn't actually use --enable-avisynth, so it's a fully functional build of FFmpeg (albeit lacking many of the external libraries it can use). But because the FFmpeg is built static, that's the more important part as far as FFMS2 is concerned. The 'minimal' FFmpeg I'm referring to in the case of something specifically for FFMS2 (or L-SMASH-Works, same deal) is this:

cd ffmpeg && \
mkdir ffmpeg-build-for-ffms2 && \
cd ffmpeg-build-for-ffms2 && \
    ../../configure \
    --prefix=$HOME/ffmpeg_build_for_ffms2 \
    --enable-gpl \
    --enable-version3 \
    --disable-encoders \
    --disable-muxers \
    --disable-doc \
    --disable-debug \
    --disable-devices \
    --disable-avdevice \
    --enable-libdav1d \
    --extra-cflags="-march=native" && \
make -j$(nproc) && \
make install

Aside from the zlib/bzip2/lzma/iconv stuff that FFmpeg automatically pulls in from the system if present, the only external library is libdav1d, and all the outputs are disabled, it's built as static, and installed to a spot in $HOME rather than the system.

At which point you'd simply change the PKG_CONFIG_PATH given to FFMS2 to $HOME/ffmpeg_build_for_ffms2/lib/pkgconfig.