Musepack or MPC is an open sourcelossy audio codec, specifically optimized for transparent compression of stereo audio at bitrates of 160-180 kbit/s. It was formerly known as MPEGplus, MPEG+ or MP+. Development of MPC was initiated in 1997 by Andree Buschmann and later assumed by Frank Klemm, and as of 2004 is maintained by the Musepack Development Team with assistance from Buschmann and Klemm. Encoders and decoders are available for Microsoft Windows, Linux and Mac OS X, and plugins for several third-party media players available from the Musepack website, licensed under the GNU Lesser General Public License or BSD licenses, and an extensive list of programs supporting the format.
Technical details
Musepack was developed using the MP2 codec as a starting point, but many features have since been added, including:
subband selectable M/S encoding
Huffman coding. Since SV8 the bitstream is compressed by highly optimized canonical huffman tables that yields 2% smaller files and faster decoding
The psychoacoustic model of MPC is based on MPEG ISO model 2, but is extended by CVD. The quantization algorithm of the MPC encoder performs spectral shaping of the noise, called adaptive noise shaping, in order to overcome the low frequency resolution of the polyphase quadrature filter bands. MPC uses the APEv2 tagmetadata container. Musepack is mainly optimized for transparent encoding at the "--standard" preset. Very few optimisations have been made at lower bitrates. Nevertheless, various listening tests have been conducted in which Musepack has performed well at both lower and higher bitrates.
Features
Container-independent format. An SV8 MPC is a container file for a Musepack stream. Raw stream encoding is possible.
Packetized stream allows muxing into audio and video containers.
Sample-accurate, fast seeking independent of file length.
Sample-accurate cutting. Application included in download package allows losslessly cutting stream segments based on selected start/end samples.
Chapters. Chapter editor included, for embedding chapters into MPC files.
No internal clipping.
Streamable.
Test results
Despite being optimized for 100% transparency at moderately high bitrates, MPC has also scored highly on many 128 kbit/s tests. In May 2004, a series of listening tests suggested that Musepack and Ogg Vorbis were the two best available codecs for high-quality audio compression at bitrates around 128kbit/s, beating MP3, AAC, WMA, and ATRAC. Listening tests of MPC:
2004 – rjamorim's second 128 kbit/s group listening test – between 14 and 27 listeners. MPC and Vorbis tied for first.
2003 – rjamorim's first 128 kbit/s group listening test – between 14 and 29 listeners. AAC, MPC, Vorbis, and WMA tied for first.
2002 – ff123's second 128 kbit/s group listening test
2001 – ff123's 128 kbit/s group listening test
Hardware and software support
Devices supporting The Core Pocket Media Player can play MPC. This includes devices running Palm OS, Symbian OS, Windows, Windows CE and Windows Mobile. All devices with software audio decoding that are supported by Rockbox, including older revisions of iPod, can also play Musepack files. Playback on Roku Photobridge HD is supported with a plugin. There is a plethora of media players for Android supporting Musepack. Musepack distributes the libmpcdec library for decoding MPC content. Various plugins have been developed, using that library, including for the XMMS player. Asunder and Jack! The Knife allows ripping Audio CD tracks directly into Musepack files.
