There is a segment of our nerdy online society that is trying desperately to sell the average consumer on the “Wonders” of lossless encoding. However, I believe that lossless encoding of music is a giant waste of hard drive space. I am not going to try to make any sort of scientific claims. There are a number of studies available that do a much better job than I can about perception in audio quality. I will merely go out on a limb and state that the vast majority of human beings cannot distinguish a difference between a sufficiently high bit rate MP3/AAC file versus a lossless audio file.
Now that we have lossless compression out of the way, let’s choose which lossy audio codec we want to use. MP3 and AAC are the two most well known lossy audio codecs, so let’s stick with them. MP3 is the most widely known and used format in today’s market. Just about every media player can play back MP3s, but there are some issues. MP3 is an aging technology. It isn’t as efficient at compressing audio as newer codecs are. Because of that, it takes a higher bit rate MP3 to stack up to an AAC file of equal perceptual quality. AAC is a newer technology that is quickly being adopted in many media players. Every Mac, iPod, and iPhone plays back AAC files with no problem. Unless you’re running very old hardware, I would recommend going with AAC.
If you have some time, I suggest encoding a song from a CD at different bit rates. To configure your encoding in iTunes, press Cmd+, to bring up the preferences. Under the General tab, press the button labeled Import Settings….
After having encoded multiple versions, compare them using the speakers or headphones you plan on using the most. Keep going until you finally notice a drop in sound quality. Now you know where you can begin to perceive a difference. Choose the lowest bit rate that doesn’t have a perceptual drop in quality for you. That, my friend, is your perfect compression.
If you don’t have the time to fool around, I suggest just setting the AAC encoder in iTunes to “iTunes Plus,” and then forgetting about it. It will be more than good enough quality for just about anyone.
Photo Credit: jnyemb