The following are Open-Source projects that are similar to this project.
The projects I'm aware of only handle WAV files and are best for use when
ripping discs, before MP3-ing them (or Ogg Vorbis-ing them), another use is
before burning a collection disc.
The first normalizing program I encountered was the
WavNorm by Duncan,
It is a pretty simple program that simply normalizes the file by making the
peaks be at the maximum level, It is pretty good but the volume not always
sounds the same.
The second program I found and based my plugin on was
Normalize by Chris Vaill,
it uses the RMS (Root Mean Square) method with a smoothing filter to get the result,
and it works very well. It's not perfect but it does an overall very good job.
The third is a snippet I was referred to by a user of my program, this is
code for the EMpeg machine written by Richard Lovejoy.
[ Homepage ]
The fourth is a program based on WavNorm, called
and extends WavNorm by having additional algorithms to choose from. I am yet
to test it on actual sound to compare it to to the others.