![]() ATRAC was also used on nearly all flash memory Walkman devices until the 8 series. ATRAC reduces the 1.4 Mbit/s of a CD to a 292 kbit/s data stream, roughly a 5:1 reduction. | ATRAC was devised to allow MiniDisc to support the same runtime as a CD. | AUDIO DATA COMPRESSION :The digitally encoded audio signal on a MiniDisc has traditionally been data-compressed using the ATRAC format (Adaptive TRansform Acoustic Coding). Eight-to-Fourteen Modulation (EFM) and a modification of CD´s CIRC code, called Advanced Cross Interleaved Reed-Solomon Code (ACIRC) are employed. The recorded signal of the premastered pits and of the recordable MD are also very similar. | MiniDiscs use a mastering process and optical playback system that is very similar to CDs. 60-minute blanks, which were widely available in the early years of the format´s introduction, were phased out and are now rarely seen. By May 2005, there were 60-minute, 74-minute and 80-minute discs available. Recordable MDs can be rerecorded repeatedly, with Sony claiming up to one million times. Playback is accomplished with the laser alone: taking advantage of the magneto-optic Kerr effect, the player senses the polarization of the reflected light and thus interprets a 1 or a 0. A magnetic head above the disc then alters the polarity of the heated area, recording the digital data onto the disk. Recordable MiniDiscs use a magneto-optical system to write data: a laser below the disc heats a spot to its Curie point, making the material in the disc susceptible to a magnetic field. ![]() MiniDiscs can either be recordable (blank) or premastered. This shutter is opened automatically by a mechanism upon insertion into a drive. | PHYSICAL CHARACTERISTICS : The disc is permanently housed in a cartridge (68×72×5 mm) with a sliding door, similar to the casing of a 3.5" floppy disk. Sony has ceased development of MD devices, with the last of the players sold by March 2013. ![]() | By March 2011 Sony had sold 22 million MD players. MiniDiscs were very popular in Japan and found moderate success in Europe although it was designed to be the successor of the cassette tape, it did not manage to mass replace it globally. Its successor, Hi-MD, would later introduce the option of linear PCM digital recording to meet audio quality comparable to that of a compact disc. The music format was based on ATRAC audio data compression, Sony´s own proprietary compression code. | Sony announced the MiniDisc in September 1992 and released it in November of that year for sale in Japan and in December in Europe, North America, and other countries. MiniDisc (MD) is an erasable magneto-optical disc-based data storage format offering a capacity of 60, 74, and later, 80 minutes of digitized audio. Glossary) Available at : Accessed : 04 aug. minidisc : Type of Magneto-optical-disc, similar to a diskette, developed by Sony for the recording and playback of data-reduced audio signals. minidisc : tipo de disco magneto-óptico, similar a um disquete, desarrollado por Sony para grabaciones y reproducción de señales de audio. O produto (MD) foi licenciado para outras companhias produzirem também, como: Aiwa, JVC, Sharp, Pioneer, Panasonic entre outras. O algum do pouco sucesso nos EUA também era devido ao alto custo na produção de álbuns em MD, alguns álbuns foram realizados pela própria Sony, mas com o tempo houve uma descontinuidade do processo. | Embora o MiniDisc tenha tido sucesso, ele não surpreendeu muito nos EUA como a Sony esperava, porém, no Japão e na Europa era um sucesso absoluto, sendo muito popular. | MD Data, uma versão para armazenar dados de computador foi anunciada pela Sony em 1993, mas isso nunca obteve um grande significado, então, hoje os MDs são usados primariamente para armazenar áudio. O MiniDisc tinha como objetivo repassar o áudio de analógico, como é armazenado num cassete (tape) para o sistema digital de alta fidelidade. A tecnologia foi anunciada pela Sony em 1991 e introduzida em 12 de Janeiro de 1992. É utilizado normalmente para armazenamento de áudio digital. ![]() MiniDisc (MD) é um disco ótico de armazenamento de dados.
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