Well, I went ahead and took the time to write up specific instructions regarding how to install the projectM standalone visualizer app on Mac OS X, along with instructions regarding how to use VLC with it. So here you go, folks:
1. Download the "projectM-jack" DMG file from this URL:
https://dl.dropboxusercontent.com/u/468 ... ackOSX.dmg
2. Mount the DMG file on your desktop and drag the "projectM-jack" app to your "Applications" folder. It will not work if you place it in any other location.
3. Download the appropriate "JackOSX 0.90" installer package from the URL below. If you are on Yosemite, grab the first binary under the Mac OS X section:
http://jackaudio.org/downloads/
NOTE: Step 3 is included here because I received an on-screen error message when I tried to use the JackOSX installer that is included in the aforementioned DMG file. The installer package I am directing you to does work on Yosemite.
4. After installing JackOSX, restart your computer when prompted to do so.
5. Launch the "JackPilot" app which is located inside "Applications/Jack".
6. Click the "Start" button in the "JackPilot" window.
7. Launch the "System Preferences" app and select the "Sound" preferences pane.
8. When the "Sound" prefs pane opens, select the "Output" tab.
9. You should now see "JackRouter" as a sound output device. Select it.
10. Open VLC.
11. Under the "Audio" menu, select "Audio Device/JackRouter".
12. Begin playing a song.
13. Launch the "projectM-jack" app in the "Applications" folder.
14. Assuming that everything was installed properly, you should now see a window on your screen with the project-M logo in it. Within seconds, it will be replaced by actual visualizations which move in sync with the currently playing song.
15. The visualizations are based on 529 ".milk" preset files which are located in the application bundle here:
/Applications/projectM-jack/Contents/Resources/presets
16. You can use the following keys to control the "projectM" visualizer app. I believe the app starts up in "random preset" mode by default:
f - Toggle fullscreen
y - Toggle shuffle
l - Lock/Unlock the current preset
n - Next preset
p - Previous preset
r - Random preset
m - Open the menu (for organizing playlists)
That's it. Enjoy your new VLC visualizer.
BTW, this projectM-jack setup should work with some other Mac audio players as well, if they allow you to choose your audio device like VLC does.