Audio compression involves data compression to reduce the transmission bandwidth requirement of digital audio streams and the storage size of audio files. Lossless compression produces digital data that can be expanded to an exact duplicate of the original audio stream. Compression ratios of lossless compression formats are similar to those for generic lossless data compression and yield around 50-60% of the original size.
Lossless compressed formats require more processing time when compared to uncompressed formats but are more efficient in space usage. In this format, the music occupies a marginally smaller file and the silence takes up no space at all when being encoded. The format is intended to reduce processing time and maintain a good compression ratio.
The different types of lossless compression formats provide a compression ratio of about 2:1. These types include:
- FLAC – Free Lossless Audio Codec is an audio codec for lossless audio data compression. It accomplishes data compression, keeping the integrity of the audio source intact. Audio sources encoded to FLAC are reduced to 50-60% of their original size and a digital audio recording converted by the codec can be decompressed into an identical copy of the audio data. It is suitable for everyday playback and archival and is well-supported by many software applications.
- WavPack – It is a free, open source lossless audio compression format that can compress 8-, 16-, 24- and 32-bit floating point audio files in the .wav file format. WavPack can support surround sound streams and high frequency sampling rates. The data reduction rate is generally between 30-70% for popular music and a little better than that for classical music and sources with greater dynamic range.
- Monkey’s Audio – This file format for audio data compression is employed to reduce bandwidth, file transfer time and storage requirements. A digital recording encoded to this format can be decompressed into an identical copy of the original audio data. The files coded to the format are reduced to about half their original size. The filename extension used by Monkey’s Audio files is .ape for audio and .apl for track metadata.
- ALAC/ Apple Lossless – The audio codec was developed for lossless data compression of digital music. Apple Lossless data is stored with the filename extension .m4a. The compressed files are about 40-60% the original size depending on the kind of music. Currently, all iPod players can play Apple Lossless-encoded files.