MiniDisc

MiniDisc [MD] is a magneto - optical disc-based data storage device initially intended for storage of up to 74 minutes and, later, 80 minutes, of digitized audio. In the form of Hi-MD, it has also developed into a general-purpose storage medium. MiniDisc was announced by Sony in September 1992 and released that November for sale in Japan and in December for the USA and Europe. The music format was originally based exclusively on ATRAC audio data compression, but the option of linear PCM recording was later introduced to attain audio quality comparable to that of a compact disc. MiniDiscs were very popular in Japan but made a limited impact elsewhere. {wikipedia}

~~~~~~~ 1999 ~~~~~~~

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In 2000, Sony announced MDLP (MiniDisc Long Play), which added new recording modes based on a new codec called ATRAC3. In addition to the standard, high-quality mode, now called SP, MDLP adds LP2 mode, which allows twice as much recording time (160 minutes on an 80 minute disc) of good-quality stereo sound, and LP4, which allows four times more recording time (320 minutes on an 80 minute disc) of medium-quality stereo sound. 

The bitrate of the standard SP mode is 292 kbit/s, and it uses separate stereo coding with discrete left and right channels. LP2 mode uses a bitrate of 132 kbit/s and also uses separate stereo coding. The last mode, LP4 has a bitrate of 66 kbit/s and uses joint stereo coding. The sound quality is noticeably poorer than the first two modes, but is sufficient for many users. 

Tracks recorded in LP2 or LP4 mode play back as silence on non-MDLP players.

~~~~~ 2003 ~~~~~

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