php-deluxe.net - description Musepack

Musepack

Musepack or MPC is an open source audio data compression#Lossy compression, specifically optimized for transparency (data compression) compression of stereo audio at bitrates of 160-180 bit rate. It was formerly known as MPEGplus, MPEG+ or MP+.

Development of MPC was initiated in 1997 by Andree Buschmann and later taken over by Frank Klemm, and is currently maintained by the Musepack Development Team (MDT) with assistance from Frank Klemm. Encoders and decoders are available for Microsoft Windows, Linux and Mac OS X, along with plugins for many third-party media players. Most of these are available from the MPC project website, licensed under the LGPL or BSD licenses.

= Technical details =

Musepack was developed using the MP2 (format) codec as a starting point, but many features have since been added, including:

subband-wise selectable M/S encoding (as in Advanced Audio Coding)

Huffman coding (as in MP3 and AAC)

noise substitution techniques (as in ATSC A-52 and MPEG-4 AAC V2)

pure variable bitrate between 3 and 1300 kbit/s (when needed)

The psychoacoustics 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.

In the past, MPC has been under suspicion of violating multiple patents (MP2, PNS, subband) [http://www.hydrogenaudio.org/forums/index.phpshowtopic=6473]. According to the developers of MPC, all patented code has been removed and it is now believed to be free of patent encumbrance. However, one PNS patent application is still active [http://appft1.uspto.gov/netacgi/nph-ParserSect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220050004791%22.PGNR.&OS=DN/20050004791&RS=DN/20050004791], and it is not trivial to know if MPC s own noise substitution techniques avoid its scope or not. Only a careful examination by a patent lawyer would say whether Musepack is truly patentless or not.

MPC uses the APEv2 tag Metadata container.

= Test results=

Despite being optimized for 100% transparency at moderately high bitrates, many 128 kbit/s tests have rated MPC highly. In May 2004, a series of .

Listening tests of MPC:

2005 - 185 kbps test [http://www.hydrogenaudio.org/forums/index.phpshowtopic=36465] based on 18 classical music samples – MPC comes second to Vorbis aoTUV.

2004 - rjamorim s second 128 kbit/s group listening test [http://www.rjamorim.com/test/multiformat128/results.html] - between 14 and 27 listeners. MPC and Vorbis tied for first.

2004 - High bitrate tests [http://www.hydrogenaudio.org/forums/index.phpshowtopic=18397] (thread by a Musepack developer)

2003 - rjamorim s first 128 kbit/s group listening test [http://www.rjamorim.com/test/128extension/results.html] - between 14 and 29 listeners. AAC, MPC, Vorbis, and WMA tied for first.

2002 - ff123 s second 128 kbit/s group listening test [http://ff123.net/128test/instruct.html]

2001 - ff123 s 128 kbit/s group listening test [http://ff123.net/128tests.html]

= External links =

[http://www.musepack.net Musepack.net] – Official website of the Musepack project (encoders, decoders, plugins for XMMS, Beep Media Player and Winamp, forums)

[http://xmixahlx.dyndns.org/audio/files/linux/musepack/klemm/www.personal.uni-jena.de/~pfk/mpp/ Frank Klemm s MPC page] (mirror)

[http://www.hydrogenaudio.org/forums/index.phpshowforum=56 Musepack forum] at Hydrogenaudio.org

[http://www.sacredchao.net/quodlibet Pymusepack] Python bindings for libmpcdec (BSD decoder library). Used by Quod Libet