Can you recompress MP3s and still have good sound? No way

Yes, indeed, you can squeeze the daylights out of your current MP3 files. But you'll end up with music that sounds like it got run over by a cement truck.

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Can you recompress MP3s and still have good sound? No way

May 19, 2013

By Al Fasoldt
Copyright © 2013, Al Fasoldt
Copyright © 2013, The Post-Standard

Earlier this month I wrote about squeezing multi-megabyte CD audio tracks into tiny files that are much smaller than MP3 audio files of the same quality, using a compression method called AAC HE. (That column can be read here: www.technofileonline.com/texts/tec050513.html.)

This lit up the old light bulb for some of you, and I got letters asking if the same method could be applied to MP3 files that already exist. In other words, could you turn your 5MB MP3 files into 2MB AAC HE versions? That would save an immense amount of hard drive space for those with hundreds or even thousands of MP3 files.

The answer? Yes, indeed, you can squeeze the daylights out of your current MP3 files. But you'll end up with music that sounds like it got run over by a cement truck.

The principle involved is older than any of us. As your momma told you, there's no such thing as a free lunch.

Here's the point. Nothing -- I repeat, NOTHING AT ALL -- can maintain, much less improve, the sound of existing MP3s while squeezing them down to almost nothing. This applies to Apple's regular AAC files (used in iTunes) just as much as it does to MP3s. Nobody's exempt.

You see, audio compression by MP3 and AAC works by removing sounds you aren't likely to miss, such as a quiet violin playing at the same time as a loud cymbal crash. Once music has gone through the MP3 wringer, there's nothing more to take out -- or, more accurately, nothing more that can be taken out without really messing up the sound.

The resulting sound can get really bad. Kelly Clarkson could end up idle, and Michael Buble could be just another Vancouver hockey fan.

So you'll have to give up on the idea of using AAC HE to cut those 3,000 MP3s in your collection down to size. That will just make them sound worse. Much worse, in fact. If you want to make your digital tracks smaller, you have two choices -- get more hard drive space (hey, it's cheap!), or do all that CD ripping again using AAC HE. The directions on how to do that is in the earlier column.

But while you're at it, give your momma a hug. Tell her she was right.