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Musepack or MPC is an open source 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 2011 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.〔(【引用サイトリンク】title=Source Code/Libs )〕 == 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 (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 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. In the past, MPC has been under suspicion of violating multiple patents (MP2, PNS, subband). 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, and it is not trivial to know if MPC's own "noise substitution techniques" avoid its scope or not. MPC uses the APEv2 tag metadata 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Musepack」の詳細全文を読む スポンサード リンク
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