Cook is a codec with loss of audio compression developed by RealNetworks. It is also known as Cooker, Gecko, RealAudio G2, and RealAudio 8 low bitrate (RA8LBR).
Introduced in 1998, the cook codec was the first audio codec developed by RealNetworks in-house, and was named after its author, Ken Cooke. The design is largely based on G. 722.1. It is a pure transformation codec based on the discrete transform of the modified cosine with a single block size.
In 2003, RealNetworks introduced a cook version with surround sound, called RealAudio Multichannel. This was initially designated by the four-character code 'whrl', but is now identified as 'cook', as mono / stereo files.
Although RealNetworks has never published a technical description of the Cook codec, others have made a technical description of the format, and as of December 2005, FFmpeg libavcodec contains a decoder capable of playing codecs of the Cook codec. As of July 2009, Rockbox is able to play Cook-encoded files.
wiki
