Created by: vidartf
This PR includes several features to fix compiling with MSVC, and several features to fix compiling without pkg-config.
Thanks for taking the effort to merge the previous PRs nicely! This is my final "major" PR for this. With this one, everything works nicely for me with both MinGW and MSVC with the official ffmpeg distros. I'll try to write up an updated install/build instruction when you've had the chance to review/merge.