Musepack (MPC) is an open source audio codec based on the lossy scheme. Formerly known as MPEGplus, MPEG+ or MP+, it has been optimized for transparent compression of stereo audio at bitrates of 160-180 kbit/s. The codec was developed with the MP2 codec as a starting point and has been updated since then. The encoders and decoders are available for Macintosh OS X, Microsoft Windows and Linux.
The technical features of Musepack include subband-wise selectable M/S encoding, Huffman coding, noise substitution techniques and pure variable bitrate between 0 and 1300 kbit/s. The psychoacoustic model of Musepack is based on MPEG ISO model 2 with an extension of clear voice detection (CVD).
Adaptive noise shaping is utilized to overcome the low frequency resolution of the polyphase quadrature filter bands. This spectral shaping of the noise is performed by the quantization algorithm of the MPC encoder. The codec uses the APEv2 tag metadata container. It is a container-independent format and enables stream encoding.
PocketPC and devices running Palm OS, Windows, Windows CE, Symbian OS or Windows Mobile are capable of MPC playback. Musepack files can also be played by devices supporting The Core Pocket Media Player. Devices with software audio decoding supported by Rockbox can play Musepack files while playback on Roku Photobridge HD is supported with a plugin.