Encoding method, encoding apparatus, decoding method, decoding apparatus, and recording medium

An encoding apparatus for encoding 8-bit data into a 10-bit code, comprising:

• storage means for storing 8-bit data and a 10-bit code related to the respective 8-bit data;
• setting means for setting the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code to 6, said setting means configured to set the RDS at the start point in the RDS trellis 10-bit code to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• and
• inhibiting means for inhibiting the RDS at the 9th bit counted from the start point from having a value equal to the minimum RDS value +1 when the RDS at the start point is equal to the minimum RDS value +2, and for inhibiting the 9th bit counted from the start point from having a value equal to the maximum RDS value -1 when the RDS at the start point is equal to the maximum RDS value -2;
• wherein said setting means is configured to set the RDS at the end point of said RDS trellis to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.

A decoding method of decoding a 10-bit code into 8-bit data, characterized in that:

• the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code is set to 6;
• the RDS at the start point in the RDS trellis representing the change in the RDS associated with said 10-bit code is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• when the RDS at the start point is equal to the minimum RDS value +2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the minimum RDS value +1;
• when the RDS at the start point is equal to the maximum RDS value -2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the maximum RDS value -1;
• and
• the RDS at the end point of said RDS trellis is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.

A decoding apparatus for decoding a 10-bit code into 8-bit data, comprising:

• storage means for storing all possible 10-bit codes and also 8-bit data related to the respective 10-bit code;
• setting means for setting the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code to 6, said setting means further configured to set the RDS at the start point in the RDS trellis representing the change in the RDS associated with said 10-bit code to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• and
• inhibiting means for inhibiting the RDS at the 9th bit counted from the start point from having a value equal to the minimum RDS value +1 when the RDS at the start point is equal to the minimum RDS value +2, and for inhibiting the RDS at the 9th bit counted from the start point from having a value equal to the maximum RDS value -1 when the RDS at the start point is equal to the maximum RDS value -2,
• wherein the setting means is configured to set the RDS at the end point of said RDS trellis to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.

A recording medium on which a 10-bit code obtained by encoding 8-bit data is recorded for use in a data reproduction method said recording medium being characterized in that said 10-bit code is generated using an RDS trellis, and further, said data reproduction method characterized in that

• the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code is set to 6;
• the RDS at the start point in the RDS trellis representing the change in the RDS associated with said 10-bit code is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• when the RDS at the start point is equal to the minimum RDS value +2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the minimum RDS value +1;
• when the RDS at the start point is equal to the maximum RDS value 2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the maximum RDS value -1;
• and
• the RDS at the end point of said RDS trellis is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.

A decoding method of decoding a partial response code into an original partitioned MSN (matched spectral null) code by means of Viterbi decoding according to a detection trellis representing state transitions, said partial response code being obtained by applying a partial response characteristic represented by a transfer polynomial in the form of (1+D)n, where D is a bit-period delay operator, and n is a positive integer, to said partitioned MSN code, said method comprising the steps of:

• detecting an invalid state transition in said detection trellis, which cannot be generated by said partitioned MSN code, on the basis of the number of 1s or 0s included in said partitioned MSN code;
• removing said invalid state transition from said detection trellis;
• and
• performing said Viterbi decoding according to the resultant detection trellis;
• wherein said partitioned MSD code is a 10-bit code;
• wherein the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code is set to 6;
• wherein the RDS at the start point in the RDS trellis representing the change in the RDS associated with said 10-bit code is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• wherein when the RDS at the start point is equal to the minimum RDS value +2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the minimum RDS value +1;
• wherein when the RDS at the start point is equal to the maximum RDS value -2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the maximum RDS value -1;
• and further
• wherein the RDS at the end point of said RDS trellis is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.

A decoding apparatus for decoding a partial response code into an original partitioned MSN (matched spectral null) code by means of Viterbi decoding according to a detection trellis representing state transitions, said partial response code being obtained by applying a partial response characteristic represented by a transfer polynomial in the form of (1+D)n, where D is a bit-period delay operator, and n is a positive integer, to said partitioned MSN code, comprising:

• a detection unit for detecting an invalid state transition in said detection trellis which cannot be generated by said partitioned MSN code on the basis of the number of 1s or 0s included in said partitioned MSN code;
• a controller for removing said invalid state transition from said detection trellis;
• and
• a Viterbi decoder for performing Viterbi decoding according to the resultant detection trellis;
• wherein said partitioned MSD code is a 10-bit code;
• wherein the difference between a maximum RDS (running digital sum) value indicating a maximum value of the RDS associated with said 10-bit code and a minimum RDS value indicating a minimum value of the RDS associated with said 10-bit code is set to 6;
• wherein the RDS at the start point in the RDS trellis representing the change in the RDS associated with said 10-bit code is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2;
• wherein when the RDS at the start point is equal to the minimum RDS value +2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the minimum RDS value +1;
• wherein when the RDS at the start point is equal to the maximum RDS value -2, the RDS at the 9th bit counted from the start point is inhibited from having a value equal to the maximum RDS value -1;
• and further
• wherein the RDS at the end point of said RDS trellis is set to a value equal to the minimum RDS value +2 or equal to the maximum RDS value -2.