Some compression formats are able to reduce the size of an audio file without discarding any data. This is lossless compression.3.6When the resulting compressed file is decompressed, it is identical to the original uncompressed audio file. Lossless compression can be used to distribute and archive digital audio, and digital players can decode the most common audio formats for playback. The rate of reduction varies generally between 25 percent and 50 percent, depending on the content of the source file.
Because they reduce the size of an average compact-disc audio file by no more than 50 percent, however, lossless compression formats are generally impractical for use in streaming--at least over networks slower than 600 kbps. Their primary application is in the archiving of master recordings, where it is essential both to preserve content and to save storage space. With lossless compression, if the original media is lost or damaged, an exact duplicate of the original can be recovered at any time.
Most lossless encoders offer various levels of compression. The tradeoff is between file size and the amount of time required to encode a file; higher compression comes at the cost of speed. Often the encoding software will offer guidance in selecting an appropriate compression level to suit your needs.