Editing Musepack

{{Short description|Open-source lossy audio codec}}
{{Infobox file format
| name = Musepack (formerly MPEGplus, MPEG+, MP+)
| icon = 
| logo = 
| caption = 
| extension = .mpc, .mp+, .mpp
| mime = audio/x-musepack<br>audio/musepack
| type code = 
| uniform type = 
| magic = MPCK, MP+
| owner = 
| latest release version = r475 (SV8)
| latest release date = {{Start date and age|2011|08|10}}
| type = [[Lossy compression|Lossy]] [[Audio file format|audio]]
| container for = 
| contained by = [[Matroska|MKA/MKV]], [[FFmpeg#NUT|NUT]]
| extended from = [[MPEG-1 Audio Layer II|MP2]]
| extended to = 
| standard =
| open = Yes
| free = Yes
| url = {{URL|www.musepack.net}}
}}

'''Musepack''' or '''MPC''' is an [[open source]] [[audio data compression#Lossy|lossy audio codec]], specifically optimized for [[transparency (data compression)|transparent]] compression of stereo audio at bitrates of 160&ndash;180 (manual set allows bitrates up to 320) [[bit rate|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]], [[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]] (LGPL) or [[BSD licenses]], and an extensive list of programs supporting the format.<ref>{{cite web |url=http://www.musepack.net/index.php?pg=src |title=Source Code/Libs |publisher=musepack.net |access-date=27 August 2010}}</ref>

== Technical details ==
Musepack was developed using the [[MP2 (format)|MP2]] codec as a starting point, but many features have since been added, including:
* subband selectable M/S encoding (as in [[Advanced Audio Coding|AAC]])
* [[Huffman coding]] (as in [[MP3]] 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]] AAC V2)
* pure variable bitrate between 0 and 1300&nbsp;kbit/s (when needed)

The [[psychoacoustics|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]] container.<ref>{{cite web|url=http://trac.musepack.net/musepack/wiki/SV8Specification |title=SV8 specification |publisher=Musepack.net |date=2009-02-24 |access-date=2020-02-14}}</ref>

Musepack is mainly optimized for transparent encoding at the "--standard" preset (175-185&nbsp;kbit/s). Very few optimisations have been made at lower bitrates (like 128&nbsp;kbit/s). Nevertheless, various [[codec listening test|listening tests]] have been conducted in which Musepack has performed well at both lower and higher bitrates.<ref>{{cite web|url=http://soundexpert.org/encoders-128-kbps |title=Audio quality of encoders at 128 kbit/s |publisher=Soundexpert.org |access-date=2011-04-25}}</ref><ref>{{cite web |url=http://audiotests.free.fr/tests/2004.07/hq1 |title=MPC vs OGG VORBIS vs MP3 at 175 kbps, listening test on non-killer samples |publisher=Audiotests.free.fr |access-date=2011-04-25 |archive-url=https://web.archive.org/web/20110719184141/http://audiotests.free.fr/tests/2004.07/hq1/ |archive-date=2011-07-19 |url-status=dead }}</ref>

== 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. [[Matroska|MKA/MKV]], [[FFmpeg#NUT|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==
{{see also|Codec listening test#Results}}

Despite being optimized for 100% transparency at moderately high bitrates, MPC has also scored highly on many 128&nbsp;kbit/s tests. In May 2004, a series of [[high fidelity#Listening tests|double-blind]] listening tests<ref name="rjamorim.com">{{cite web|url=http://listening-tests.freetzi.com/html/Multiformat_128kbps_public_listening_test_results.htm |title=Results of Multiformat at 128kbit/s Listening Test |publisher=Listening-tests.freetzi.com |access-date=2011-10-04}}</ref> (as reported on Slashdot<ref>{{cite web|url=http://slashdot.org/articles/04/05/24/0623247.shtml?tid=141&tid=185&tid=188 |title=Vorbis And Musepack Win 128kbps Multiformat Test |publisher=Slashdot |date=2004-05-24 |access-date=2011-04-25}}</ref>) 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 128&nbsp;kbit/s, beating [[MP3]], [[Advanced Audio Coding|AAC]], [[Windows Media Audio|WMA]], and [[ATRAC]].

Listening tests of MPC:
* 2004 – rjamorim's second 128&nbsp;kbit/s group listening test – between 14 and 27 listeners. MPC and Vorbis tied for first.<ref name="rjamorim.com"/>
* 2003 – rjamorim's first 128&nbsp;kbit/s group listening test – between 14 and 29 listeners. AAC, MPC, Vorbis, and WMA tied for first.<ref>{{cite web|url=http://listening-tests.freetzi.com/html/128kbps_Extension_public_listening_test_results.htm |title=Results of 128kbit/s Extension Listening Test |publisher=Listening-tests.freetzi.com |access-date=2011-10-04}}</ref>
* 2002 – ff123's second 128&nbsp;kbit/s group listening test<ref>{{cite web |url=http://ff123.net/128test/instruct.html |title=128 kbit/s Blind Listening Tests |publisher=Ff123.net |access-date=2011-04-25 |url-status=dead |archive-url=https://web.archive.org/web/20110517111516/http://ff123.net/128test/instruct.html |archive-date=2011-05-17 }}</ref>
* 2001 – ff123's 128&nbsp;kbit/s group listening test<ref>{{cite web |url=http://ff123.net/128tests.html |title=Group Listening Tests of Various Formats at 128 kbit/s |publisher=Ff123.net |access-date=2011-04-25 |url-status=dead |archive-url=https://web.archive.org/web/20110517111522/http://ff123.net/128tests.html |archive-date=2011-05-17 }}</ref>

==Hardware and software support==
Devices supporting [[The Core Pocket Media Player]] can play MPC. This includes devices running [[Palm OS]], [[Symbian]] OS, [[Microsoft Windows|Windows]], [[Windows CE]] and [[Windows Mobile]] ([[Pocket PC]]). 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 (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]]). [[Asunder (software)|Asunder]] and Jack! The Knife allows ripping Audio CD tracks directly into Musepack files.

==References==
{{reflist|2}}

== External links ==
* {{Official website}}
* [http://musepack.net/index.php?pg=pro Software supporting Musepack]
* [http://wiki.hydrogenaud.io/index.php?title=Musepack Hydrogen Audio Wiki's article on Musepack]

{{Compression formats}}
{{Compression software implementations}}

[[Category:Free audio codecs]]
[[Category:Open formats]]