Understanding Audio Data Compression: MP3s, AACs, and more

April 25, 2011 9:12:32 PM PDT

Other Alternatives

While MP3 is the most popular data compression format, there are countless other formats available. Each uses a different type of algorithm to determine what data to discard, and the resulting differences in sound can range from subtle to fairly obvious. There are far too many different encoding formats to name them all, but here are a few of the more commonly used ones.


WMA (Windows Media Audio) was created by Microsoft, and is often offered as an alternative to MP3 on music and video download sites. It’s also common on sites that offer streaming audio and video files compatible with Windows Media Player. While many people feel the sonic quality is superior to MP3, WMA files tend to sound overly bright and brittle, with less than optimal stereo imaging.

AAC (Advanced Audio Coding) was designed to be a successor to MP3, and although it is a sonic improvement, its popularity has never really taken off. AAC is a default standard for iTunes, the iPod, the iPhone, as well as PlayStation and Nintendo DS. It’s also often used as the audio component for Apple’s QuickTime and MP4 video formats. Generally speaking, if you’re going to offer a second encoding format online, AAC is the one to consider.

AC3 is a format developed by Dolby and is often used for video soundtracks due to its superior stereo imaging and ability to handle multitrack formats like 5.1 surround. Because of this, many consumer-grade DVD players support AC3 format.

RA (Real Audio) is a fairly good-sounding codec, but is on the decline due to the fact that the files only play on Real Audio’s proprietary player. Many people refuse to install the Real Audio player due to its excessive advertising and high-CPU demands.

Ogg Vorbis is an open standard audio format that delivers a very high-quality sound. Unfortunately, like many open standard projects, it has had a hard time catching on among users.

FLAC (Free Lossless Audio Codec) is one of the few audio formats that delivers truly lossless compression. FLAC is similar to a ZIP file, but is designed specifically for audio. FLAC is also open-source, and FLAC files can be played back on most MP3-compatible players. (There are several other lossless formats, including Apple Lossless, WMA 9 Lossless, Monkey’s Audio and MPEG-4ALS, but none offer the open compatibility of FLAC.)

— Daniel Keller