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Compressing music files Having come across a number of persons using winrar or zip to compress music files, I feel compelled to explain how music file compression works. It is not at all similar to the compression methods employed by compression software such as winrar or winzip which are used for regular data files. A user would notice that there is hardly any change in file size if he or she attempts to compress music or even video files for that matter, with regular compression tools.
The trick to compressing audio or video files is lowering the bitrate. A music file (except audio CD files) depends on the bitrate for quality as well as the size. The bitrate is the amount of data being read from the file per second. It is typically expressed in Kbps (Kilobits per second) or Mbps (Megabits per second) for lossless files. We should understand that there are two types of codecs which are used to compress audio files, the first type are known as lossy codecs, such as MP3 (Mpeg Layer-3), WMA (Windows Media Audio). These are called lossy codecs since there occurs a loss in quality (some higher frequencies are removed from the audio) of the audio file if they are compressed using these codecs. The second type of codecs are lossless codecs such as WMA lossless, FLAC (Free Lossless Audio Codec) which preserve the audio quality and hence are not very efficient at music compression such as MP3. Typical file sizes for lossless files (~1Mbps) are 30-40MB for a 5min music file while MP3 files at 320kbps are as low as 10MB.
As I explained earlier, the file size depends on the bitrate, the lower the bitrate, the lower the size and most often a lower quality audio. A bitrate of 320 Kbps is considered near-lossless. To compress audio files, what you would need is software such as Nero Wave Editor (it is paid but free choices exist). You can select any codec you want and then select the bitrate you want your file, and encode and save it accordingly. What this encoding does is that it cuts off certain frequencies that are mostly inaudible to the human ear from the music, which is most sensitive to 20Hz to 20KHz. Any frequencies higher or lower than this range can be omitted, having little to no effect on the music quality, but beware this applies only to bitrates down to 256kbps, going lower will in most cases, if not all, result in some amount of quality loss though there are many variables involved.
A bitrate of 128kbps is sufficient to play on a mobile phone or portable music player. Higher bitrates or lossless files result in better user experience on high-end systems like a home theatre or even your computer’s HD audio.
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