The Ups and Downs of Audio Format Selection
Lossy or lossless? MP3 or WMA? Here are the pros and cons of the most common digital audio formats.
Audio Format Selection
April 02, 2008 by Dennis Burger

The digital music revolution was supposed to make our lives easier, wasn’t it? Music that follows you wherever you go, easy-to-use playlists, massive amounts of tunes in the palm of your hand—it all sounds so deliciously enticing until you try to decide what form you want that digital music to take. Do you want your music stored in lossy or lossless format? What does that even mean? Is disk-space more important to you than sound quality? Or would you rather have better sound, at the expense of being able to store fewer songs. Or are both of those qualities secondary to being able to rip (or buy) your music once and play it on virtually any audio device you can get your hands on?

The choices are so numerous that a beginner might be inclined to run screaming back to the safety of CDs. The following brief breakdown of the most common digital audio formats—with emphasis on the strengths and weaknesses of each—should clear up some of the confusion and allow even the greenest of neophytes to pick the right format to meet his or her needs.

AAC (Advanced Audio Coding): Although most often associated with the iPod, this MPEG-4 audio format was actually poised by its creators (including Bell Laboratories, Dolby, Fraunhofer, Nokia, and Sony—not Apple) as the universal successor to the aging-but-popular MP3 format. 

AAC is a lossy audio codec (coder-decoder), meaning it uses complex calculations based on the strengths and weaknesses of human hearing to remove (or lose) unimportant information from the original audio source. This greatly reduces the size of an audio file without noticeably impacting audio quality for most listeners. For example, at a bitrate of 192 kilobits per second (kbit/s), the point at which most people cannot distinguish a song encoded with AAC from the CD, the AAC file will chew up less than 15% of the disk space as the original.

The Highs: More sophisticated and efficient than MP3, meaning it can generate equal or better sound quality without hogging as much disk space. Supported by virtually all name-brand personal digital music players and current-generation game consoles, as well as many software players, distributed audio servers such as Escient Fireballs, and wireless music systems made by Sonos and SqueezeBox. 

The Lows: Unsupported by popular ReQuest music servers. Also can’t be streamed to a Windows Media Center Extender without a lot of fuss and unofficial add-on programs. Advantages over MP3 diminish at higher bitrates. AAC files purchased from iTunes before the advent of iTunes Plus come with pesky copy protection that limits how, where, and on which devices you can play the music.

FLAC (Free Lossless Audio Codec): As its name implies FLAC differs from AAC (and MP3, Ogg Vorbis, WMA, and many other codecs) in that it offers lossless audio compression. Instead of forever removing audio information from the file to save disk space, such lossless codecs simply find different ways of packing the digital information more efficiently, while still being capable of recreating the original audio signal bit-for-bit. For example, you can generally expect FLAC to reduce the disk space required for full CD-quality audio from 1411 kilobits per second of audio down to 700 to 800 kbit/s—a 40-50% reduction, depending upon the complexity of the music. And again, this is with absolutely no reduction in quality, perceived or otherwise.

The Highs: Produces a sonically perfect recreation of your CDs, while still reducing disk space as compared to uncompressed formats such as WAV and AIFF. Open source, so it’s available on many platforms. Supported by music servers from both Escient and ReQuest, popular wireless music systems from Sonos and SqueezeBox, as well as many popular software players like WinAmp, MediaMonkey, and AlbumPlayer. Playback is also faster and less processor-intensive than many other lossless audio formats. 

The Lows: Limited support on personal digital music players, unless you want to resort to unsupported (and potentially dangerous) third-party firmware. Not recognized by music management programs that most people use: iTunes, Windows Media Player, etc. 

MP3: The granddaddy of all lossy digital music codecs, MP3 isn’t going anywhere soon. In fact, its name has become synonymous with the whole concept of digital music. Think about it: have you ever heard a kid ask for an AAC or WMA player for Christmas? An Ogg Vorbis player? I thought not. These days, if it makes noise, it’s pretty safe to assume that it supports MP3. Due to name recognition alone, the format will most likely outlive many of the codecs intended to replace it, superior though they may be. 

The Highs: The format you’re most likely to use, no matter what you read in this article. Sounds perfectly fine to the vast majority of people at bitrates of 128 kbit/s and above. Nigh-universal support, due to its massive installed base: MP3s can be played by just about every music player, computer program, toaster, tennis shoe, pack of gum, and gaming console in the world (except, interestingly enough, the Wii, which just scrapped MP3 playback in favor of AAC exclusivity).  Its lack of DRM (digital rights management, or copy protection) also leads to fewer playback hiccups and compatibility issues. 

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