Thank you Are_ .
Edit: A few notes for anyone else trying to compile:
1. Looking at the newer source on the official page, it looks likes vc's fix for the issue pointed out in post #9 is to comment out both lines. This seems fine, since the variable is unused anyway.
2. It looks like there's another bug. The for loop at the bottom of Factorize.cpp is missing its {}s. I *think* the closing brace should go on line 52 (???).
3. libfftw3f_threads is a dependency (at least for the fixed version). If you don't link it at compile time, core.vcfreq.Sharp() will crash with an undefined symbol error for fftwf_init_threads.
4. I was able to compile with
Code:
g++ -Wall -shared -fPIC -I. -L/usr/local/lib/vsplugins/lib -lfftw3f_threads -o libvcfreq.so vcfreq.cpp
after copying the vapoursynth headers into the working directory.
(My libfftw3f_threads.so is in usr/local/lib/vsplugins/lib; adjust accordingly.)