Audio Compression
General Terms - Audio Compression
Audio compression refers to a form of data compression method designed to reduce the size of audio files. Audio compression algorithms are implemented in the form of audio codecs. There are two types of audio compression methods: lossy compression and lossless compression. Both methods focus on reducing information redundancy using methods such as coding, pattern recognition and linear prediction.
Lossy audio compression
Lossy audio compression algorithms provide higher compression ratios, resulting in 5 percent to 20 percent of the original stream, by discarding less critical data. They are used in wide range of applications including mp3 players, video DVDs, digital televisions, satellite and cable radios, and terrestrial radio broadcasts. Lossy compression is irreversible, since a small portion of the original data is lost due to compression.
Lossy compression results in increasing degradation of quality if data are decompressed, then recompressed using lossy compression.
Lossless audio compression
Lossless audio compression preserves an exact copy of the original files. Compression ratios are around 50 to 60 percent of the original size and substantially less than that for lossy compression. Lossless compression finds the best use in audio archiving and editing. Losslessly compressed data also avoids compression artifacts. Hence they are preferred by audiophiles.
Important lossless audio compression formats include Shorten, Free Lossless Audio Codec (FLAC), Apple’s Apple Lossless, MPEG-4 ALS, Monkey’s Audio, and TTA. Some audio formats feature a combination of a lossy format and a lossless correction. In this, a lossy file can be created by stripping the correction. Examples of such formats include MPEG-4 SLS, WavPack, and OptimFROG DualStream.
