Incrementally built in a session with Sonnet 4.6:
mkdir rife
cd rife
python3 -m venv .venv
. .venv/bin/activate
python3 -m pip install vsrife
python3 -m pip install vapoursynth
pip install vssource
pip install vapoursynth-bestsource
#
# Must edit interpolate.vpy first, and put "input_3GS.mp4" as input
#
vspipe interpolate.vpy - -c y4m | \
ffmpeg -i pipe:0 \
-i input_3GS.mp4 \
-map 0:v \
-map 1:a \
-c:v hevc_nvenc \
-cq 31 \
-preset p4 \
-rc-lookahead 20 \
-spatial_aq 1 \
-c:a copy \
/dev/shm/2x.mp4
cd /dev/shm/
mpv 2x.mp4