Digital audio is not a standard, and there are several (and very different) formats, technologies and playback products available. When you purchase songs from Apple’s iTunes store or download from peer-to-peer networks, for example, most of the time you are getting digital files that are compressed versions of the originals. This compression allows you to rip thousands of songs to your computer hard drive and not overwhelm your storage space. It also means you are giving up some of the audio quality of the original file.
Depending on your taste, you can rip CDs and download music in varying digital sizes and quality. Keep in mind that the larger the streamed data rate of the file (measured in kilobits per second, or kbps), the higher quality it will be. Here is a simple breakdown of the different audio levels in kbps.
CD quality: 1,411 kbps
Near-CD quality: 192 to 320 kbps
Minimum levels for most listeners: 128 kbps
Apple employs the AAC (advanced audio coding) format, which streams its data rate at 128 kbps. Apple recently began offering higher-quality 256-kbps-level downloads for songs that have no digital rights management restrictions (DRM), meaning that they can be played on more devices than just your iPod. All of the downloads at Amazon.com’s MP3 store are of the DRM-free variety as well.
Other popular digital music formats include WMA (Windows Media Audio), developed by Microsoft; FLAC (Free Lossless Audio Codec), a format that minimizes compression to maintain CD audio quality; and ALAC (Apple Lossless Audio Encoder), developed by Apple to preserve CD quality at a lossless data compression rate when you rip your tunes.
The MP3 format, perhaps the most familiar digital music type, is part of the MPEG family of standards and is typically employed with data rates of 128, 192, 256 and 320 kbps.
There are a handful of music download sites, including those of AIX Records and MusicGiants, that offer high-resolution data rates. MusicGiants states that its downloads range from 470 to 1,100 kbps. AIX’s download site iTrax.com goes even further, offering high-resolution downloads in 5.1 surround sound.
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