Okay, so I have this huge mp3 collection (duh) and I encoded them with several dfiferent encoders over the years. They need to be normalized.

As was already mentioned, Richard Lovejoy's Volume Adjustment Kernel is one possible solution. But before you go any further, let's get one thing absolutely clear...

How certain are you that these files really need to be normalized?

You're probably listening to them in shuffle mode, and discovering that they sound like they're all at different volume levels. Is that it?

Well guess what. They're probably already normalized, and the reason they sound like they're all at different volume levels has nothing whatsoever to do with normalization. Most CD's that you buy are already normalized, and they still sound like they're at different volume levels.

It's the same with the difference between TV commercials and TV shows. The commercials are compressed more than the shows, so they sound louder, but both the shows and the commercials are already normalized to the same peak.

Check out the README.TXT in this file for a discussion of the difference between compression and normalization and how they relate to your situation.

In my experience, Richard's kernel helps take the "edge" off of the volume difference between tracks. It doesn't solve the problem 100 percent, but it goes a long way towards it. And the contents of that file will allow you make it selectable and/or adjustable.

Now, if you're certain that your files really need to be normalized, the best way to do it is to re-rip them. You can't decompress/edit/recompress without inducing more compression artifacts.

There is one other option, MP3Trim. This program has the ability to globally increase the volume of an MP3 file without decompressing and recompressing it. A recent version (I didn't know until I checked just now that he'd added it) even allows peak detection for automatic normalizing. Nifty.

But like I said, I'll bet that your stuff is already normalized and this isn't really going to help you. If your music is already normalized, and your complaint is that the volume is different from album to album, the only solution is dynamic compression.

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Tony Fabris