Read this first
The last SVP version supporting 10.10 is 4.2.146!
It's impossible now to install Vapoursynth libs (and mpv with Vapoursynth support obviously) via Homebrew due to missing zimg dependency - Homebrew says
zimg: macOS El Capitan or newer is required.
What we can do? We can build zimg, Vapoursynth and mpv manually and place them into Homebrew's "cellar".
So, considering a clean OS X install, the following should work:
1. Install Homebrew
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
2. Install all the mpv dependecies:
brew install libass tesseract python3 mpv
this can take a while, especially on 10.9
3. Remove installed mpv cause we gonna replace it with our own build:
brew unlink mpv
rm -fR /usr/local/Cellar/mpv
4. Unpack .tgz with pre-built zimg, vapoursynth and mpv into /usr/local/Cellar
5. Link our binaries into /usr/local:
brew link --overwrite zimg vapoursynth mpv
6. Restart SVP