Which Encoder is Right for You?

A recent discussion in our forums generated by our friend and neighbor, miTunes75, got me thinking. The thread begins with 75’s concern about the quality of files sold by the iTunes Music Store: Is music encoded at 128kbps in the AAC format good enough? And, if not, what is?

I’ve read rant after rant extolling the virtues of one audio codec over another, demonizing or lionizing variable bit rate encoding, and questioning the patriotism of those who listen to music smushed with any variety of lossy encoder and I’ve yet to be convinced that the answer is more complex than “Find a setting you can tolerate and then crank it up to the point where the music is not only tolerable, but enjoyable.”

Such a setting is purely subjective. If you have finely tuned hearing, you may not be able to stand anything less than music encoded with a lossless encoder. If, on the other hand, you have ears like mine — beaten down by years of playing in loud rock and roll bands — you’ll find files encoded with AAC at 128kbps perfectly acceptable.

The problem is that many of us are susceptible to audio snobbery. We’d like to think that we possess discerning ears and so tend to favor lossless audio or audio compressed at extremely high bit-rates because that preference reflects on our worth. I know people who, for the same reason, drop a load of cash on expensive single-malt scotch when, in a blind tasting, they couldn’t tell the difference between an 18 year old Macallan and a beaker of turpentine.

I’m a big fan of flying blind and if you’re really interested in finding the perfect encoding settings I suggest that you do just that. Rip a CD into a variety of formats — AIFF, Apple Lossless, and MP3 and AAC at bit-rates from 128kbps to 256kbps — and conduct a blind listening test.

Ideally this CD will be well-produced (meaning the instruments are nicely balanced and clean), won’t over-emphasize particular frequencies (electronic dance music, for example, tends to accentuate low frequencies), and feature sound in a broad range of frequencies so you can listen for problems across the audio spectrum. You should also choose a CD that you’re familiar with in a style you’re likely to listen to (it’s all well and good to audition your settings with a classical music CD that features full orchestra, but if you’re going to listen to nothing but thumping hip-hop, use that as your standard).

Plant yourself in front of the best audio system you’ll use to play this music — this can be your home stereo or iPod with the headphones that you normally use — cinch on a blindfold, and ask a willing soul to play each version for you without telling you which is which. Be sure that the songs are played at the same volume. We humans tend to believe that volume = quality — when you play the same song at two different volumes, you’re more likely to prefer the louder rendition.

Rate the versions as you listen and immediately toss out those you don’t like. Narrow your choices down to the point where you can’t tell one from the other (or can tell but find them all pleasing). Take off the blindfold and choose the one that made the quality cut and takes up the least amount of storage space. For example, if you can’t tell the difference between Apple Lossless and AAC encoded at 160kbps, the AAC recording is for you as it produces files far smaller than those compressed with Apple Lossless.

And if it turns out that you have turpentine tastes? Hold your head high knowing that your iPod will hold six times the number of songs as those saddled with ears of gold.