How to Normalize MP3s With MP3Gain

Posted on Thursday 18 October 2007

So as I mentioned in my article the other day, I found a treasure trove of really great sites with literally tons of old radio shows in MP3 formats. I downloaded about 30 half hour shows (which only filled up about a fifth of the disk) and put them in my DVD player to test before my wife got home with the car (most DVD’s today can play MP3 audios). Right away a major problem jumped out at me.

Even though I had downloaded all the recordings from just one sight, they played back at different levels! So if you had to turn the volume down for one show because it was too loud, then the next one was too quiet and you had to turn the volume back up. Having to do this every 30 minutes or so might not be a major problem. However if you were driving, the blare from a loud recording coming in after a quiet one could be enough to cause you to drive off the road!

This is a normal problem when mixing different pieces of music and I normally tackle it before I record any CD. Matter of fact I think my Nero CD burning software actually has this utility built in. Unfortunately, I had nothing that worked on MP3s.

What I wanted to do was to “normalize” the recordings so that they all had approximately the same volume level. I also wanted to soften any that were recorded so loud that they actually distorted during playback. Lastly, I also needed to do it in bulk and not one at a time (as by now I was garnering a fairly hefty collection) and of course I wanted it to be a free or freeware. So off to Google I went.

Sometimes life is good, and my first Google search hit pay-dirt. A wonderful little utility called MP3Gain. It’s been around for a few years now and they have created versions for Windows and Macintosh. Their description does a better job of describing it than I can…

MP3Gain does not just do peak normalization, as many normalizers do. Instead, it does some statistical analysis to determine how loud the file actually sounds to the human ear.

Also, the changes MP3Gain makes are completely lossless. There is no quality lost in the change because the program adjusts the mp3 file directly, without decoding and re-encoding.

The author, Dave Sawyer, has given us an awesome tool! It will run on just one file, or directories of files. It comes set up with an excellent default mode, but it also has many options and over-rides if you like to experiment. The only big caveat is, like most normalizers, the file will be replaced! So if you are experimenting with it and would like to keep your original files, make sure you back them up elsewhere!

It took less than 20 minutes to analyze and then perfectly normalize over 200 various MP3 files. This one definitely rates five stars in my book!

End Article
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