How to globally normalize volume of OSX applications?

I'm looking for a way to minimize spikes in the audio volume while watching Netflix or iTunes movies. I'm not talking about Dynamic Range Compression, but something similar to "Loudness Equalization" feature of Windows 7, so it will "increase" audio volume when the sound is quiet, and "decrease" it for some crazy sound effects like gun shots.

The ideal way is to have something similar to volnorm filter in mplayer.

I know we can use SoundFlower as a start to redirect audio output to some application. I tried Audacity to process it, but didn't find any way to perform real time processing.

Audio Hijack Pro seems like nice solution, but I didn't find suitable effect among available ones.

Maybe I was looking in the completely wrong direction? All ideas are welcome, including links to paid applications.

Solution 1:

OK, I finally found a plausible solution for this question—I'm using free volume limiter plugin, LoudMax, which is easier to setup (IMHO) than built-in Apple Audio Unit plugins. I also bought Audio Hijack Pro, which seems to me more convenient than free SoundFlower + AU lab, but latter one works too.