Musepack or MPC is an

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized so ...

lossy audio codec, specifically optimized for transparent compression of stereo audio at bitrates of 160–180 (manual set allows bitrates up to 320) 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 (MDT) with assistance from Buschmann and Klemm. Encoders and decoders are available for

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

and

Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lap ...

, and plugins for several third-party media players available from the Musepack website, licensed under the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

(LGPL) or

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, 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 (as in AAC) *

Huffman coding In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code proceeds by means of Huffman coding, an algo ...

(as in

MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Origin ...

and AAC, but more efficient). Since SV8 the bitstream is compressed by highly optimized canonical huffman tables that yields 2% smaller files and faster decoding * noise substitution techniques (as in ATSC A-52 and

MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related t ...

AAC V2) * pure variable bitrate between 0 and 1300 kbit/s (when needed) The psychoacoustic model of MPC is based on MPEG ISO model 2, but is extended by CVD (clear voice detection). The quantization algorithm of the MPC encoder performs spectral shaping of the noise, called '' adaptive noise shaping'' (ANS), in order to overcome the low frequency resolution of the polyphase quadrature filter bands. MPC uses the APEv2 tag

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

container. Musepack is mainly optimized for transparent encoding at the "--standard" preset (175-185 kbit/s). Very few optimisations have been made at lower bitrates (like 128 kbit/s). 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 (e.g. MKA/MKV, NUT). * Sample-accurate, fast seeking independent of file length. * Sample-accurate cutting. Application included in download package (mpccut) allows losslessly cutting stream segments based on selected start/end samples. * Chapters. Chapter editor (mpcchap) 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

double-blind In a blind or blinded experiment, information which may influence the participants of the experiment is withheld until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expec ...

listening tests (as reported on Slashdot) suggested that Musepack and Ogg Vorbis (which was the 1.1 "aoTuV" fork at the time) were the two best available codecs for high-quality audio compression at bitrates around 128kbit/s, beating

, AAC, WMA, and

ATRAC Adaptive Transform Acoustic Coding (ATRAC) is a family of proprietary audio compression algorithms developed by Sony. MiniDisc was the first commercial product to incorporate ATRAC in 1992. ATRAC allowed a relatively small disc like MiniDisc to h ...

. 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

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Symbian Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS ...

OS,

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for se ...

Windows CE Windows Embedded Compact, formerly Windows Embedded CE, Windows Powered and Windows CE, is an operating system subfamily developed by Microsoft as part of its Windows Embedded family of products. Unlike Windows Embedded Standard, which is base ...

and

Windows Mobile Windows Mobile is a discontinued family of mobile operating systems developed by Microsoft for smartphones and personal digital assistants. Its origin dated back to Windows CE in 1996, though Windows Mobile itself first appeared in 2000 as Pock ...

(

Pocket PC A Pocket PC (P/PC, PPC) is a class of personal digital assistant (PDA) that runs the Windows Mobile or Windows Embedded Compact operating system that has some of the abilities of modern desktop PCs. The name was introduced by Microsoft in 200 ...

). All devices with software audio decoding that are supported by Rockbox, including older revisions of

iPod The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes wa ...

, can also play Musepack files. Playback on

Roku Roku ( ) is a brand of hardware digital media players manufactured by American company Roku, Inc. They offer access to streaming media content from online services. The first Roku model, developed in collaboration with Netflix, was introduced ...

Photobridge HD is supported with a plugin. There is a plethora of media players for Android supporting Musepack (among them is the ported Rockbox media player). Musepack distributes the ''libmpcdec'' library for decoding MPC content. Various plugins have been developed, using that library, including for the XMMS player (on

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...

). Asunder and Jack! The Knife allows ripping Audio CD tracks directly into Musepack files.

References

External links

*
Software supporting Musepack

Hydrogen Audio Wiki's article on Musepack
{{Compression software implementations Free audio codecs Open formats