Musepack

Introduction

Musepack is a lossy audio compression scheme created by Andree Buschmann. It is strongly based on the MPEG-1 Layer-2 (MP2) algorithms. Informal listening tests have demonstrated that MPC is the best lossy audio encoder at ~140kbps and above bitrates, but competes less well at lower, 'streaming' bitrates such as 32/48/64kbps. This is due to MPC being a subband codec as well as the fact that very little optimization has gone into such low bitrates. As can be seen in various 128kbit/s listening tests (see below), despite the fact that MPC has been optimized little for such bitrates it is in the same class of other modern competitors such as AAC and Ogg Vorbis.

Pros

• Best lossy encoder for mid-high bitrates
• Suffers from far less "problem cases" than other formats.
• Very fast encoding/decoding
• Designed to be transparent by default at --standard setting.
• Open source encoder

Cons

• Marginal support (yet) on portable players
• No multichannel
• No specification available
• Seeking is imperfect (to be fixed in SV7.5)
• Not streamable
• Can't be cut/edited
• No support for sampling rates above 48khz

Technical details

Supported input formats (SV7)

• channels: 1 or 2
• bit depths: 1 to 32 bit linear PCM
• sample rates: 32kHz, 37.8kHz, 44.1kHz, 48kHz (44.1 and 48 are highly tuned)
• WAV, raw PCM, a lot of lossless compressed audio formats like FLAC, LPAC, APE, OptimFROG, SZIP and Shorten (SHN)

Encoder Functions

MPC Encoder Functions

Links

User oriented links

• Musepack.net - a general info, news and software site.
• Case's page (Winamp plug-ins and more).
• Frank Klemm's official page (out of order now)
• Mirrored at: http://hydrogenaudio.org/musepack/klemm/www.personal.uni-jena.de/~pfk/mpp/
• BetaPlayer, the first Musepack-able player on PocketPCs

Technical links

• Frank Klemm's official page
• MPC at AudioCodingWiki
• libmusepack portable musepack decoding library (in progress)

Listening test involving MPC

• ff123's 128kbit/s group listening test
• ff123's second 128kbit/s group listening test
• rjamorim's 128kbit/s test

Please note that some of these tests, while valid, used versions of the encoders in almost all of the formats tested which have now been superseded. You should make your own decision about the comparative quality of MPC, listening to clips of music in the style you prefer.

Also note that these are tests at low bitrates; an area where MPC is not particularly optimized. The encoder was designed by the author to be transparent at the --standard setting, thus little to no low bitrate tuning has gone into the codec, opposite to that of AAC, Ogg Vorbis, WMA and others which focus more on this region. However, as can be seen in the various listening test pages, MPC competes surprisingly well with the rest of them.