Method and apparatus of modulating/demodulating data for an optical recording medium

A method of modulating a source data to a code data under conditions of a given code rate and run length limited (rll), said method comprising:

• (a) modulating the source data into the code data based on a bit sequence of the source data by using a map table and an additional table,
• wherein the map table comprises source data of 2 bits to be converted into code data of 3 bits, source data of 4 bits to be converted into code data of 6 bits, source data of 6 bits to be converted into code data of 9 bits, and source data of 8 bits to be converted into cede data of 12 bits and the additional table comprises source data to be converted into additional code data, the source data in the additional table including at least a bit sequence of source data which is not included in the map table,
• wherein the modulating step (a) includes selecting the additional code data as code data based on at least a sequence of a next modulated data;
• (b) converting the code data into NRZI data to produce channel data;
• and
• (c) recording the channel data onto a recording medium.

A method of demodulating a code data written onto a recording medium, the method comprising:

• (a) reading the code data from the recording medium, the code data having been modulated, before written onto the recording medium, from a source data based on at least a bit sequence of the source data by using a map table and an additional table,
• wherein the map table comprises source data of 2 bits to be converted into code data of 3 bits, source data of 4 bits to be converted into code data of 6 bits, source data data of 3 bits, source data of 4 bits to be converted into code data of 6 bits, source data of 6 bits to be converted into code data of 9 bits, and source data of 8 bits to be converted into code data of 12 bits, the additional table comprises source data to be converted into additional code data, the source data in the additional table includes at least a bit sequence of source data which is not included in the map table, and the additional code data is selected as code data based on at least a sequence of a next modulated data;
• and
• (b) demodulating the read code data by converting code data of 3 bits into source data of 2 bits, code data of 6 bits into source data of 4 bits, code data of 9 bits into source data of 6 bits, and code data of 12 bits into source data of 8 bits based on at least the bit sequence of the read code data.

An apparatus for demodulating a code data written onto a recording medium, the apparatus comprising:

• a detector adapted to read the code data from the recording medium;
• and
• a decoder adapted to demodulate the code data by converting code data of 3 bits into source data of 2 bits, code data of 6 bits into source data of 4 bits, code data of 9 bits into source data of 6 bits, and code data of 12 bits into source data of 8 bits based on at least a bit sequence of the read code data,
• wherein the source data is modulated, before written onto the recording medium, into the code data based on a bit sequence of the source data by using a map table and an additional table, and
• wherein the map table comprises source data of 2 bits to be converted into code data of 3 bits, source data of 4 bits to be converted into code data of 6 bits, source data of 6 bits to be converted into code data of 9 bits, and source data of 8 bits to be converted into code data of 12 bits, the additional table comprises source data to be converted into additional code data, the source data in the additional table includes at least a bit sequence of source data which is not included in the map table, and the additional code data is selected as code data based on at least a sequence of a next modulated data.