Coding device

Claim 2

A coding device comprising: (a) input means for inputting a value to be quantized; and (b) quantizing means for converting the value to be quantized which was input from the input means into a coding code of n bits, wherein the quantizing means can output (2 n-1 - 1) coding codes corresponding to positive quantization representative values, (2 n-1 - 1) coding codes correspond­ing to negative quantization representative values, a coding code corresponding to the quantization represent­ative value of a difference value "0", and a special coding code selectively corresponding to the positive and negative quantization representative values.

Claim 3

A device according to claim 1, further comprising switching means for switching the quantizing means between a first mode to make the special coding code correspond to the positive quantization represent­ative value and a second mode to make the special coding code correspond to the negative quantization representative value.

Claim 4

A device according to claim 2, wherein the input means includes: an arithmetic operating circuit for operating the difference value of a sample value and its predictive value and for supplying the difference value as the value to be quantized to the quantizing means; an inverse quantization circuit for converting the coding code into the quantization representative value corresponding to the difference value; a decoding circuit for operating a decoded value by using both of an output of the inverse quantiza­tion circuit and the predictive value; and a predicting circuit for forming the predictive value by using the decoded value.

Claim 5

A device according to claim 3, wherein the switching means switches the quantizing means between the first and second modes in accordance with whether the predictive value is a predetermined value or more or not.

Claim 6

A device according to claim 4, wherein the switching means includes a circuit to extract the most significant bit of the predictive value.

Claim 7

A device according to claim 4, wherein the switching means includes a comparison circuit to compare the predictive value and the predetermined value.

Claim 8

A coding device comprising: (a) input means for inputting a value to be quantized; and (b) quantizing means for converting the value to be quantized which was input from the input means into a coding code of n bits, wherein the quantizing means can output the coding code corresponding to a predetermined quantization representative value and a special coding code selectively corresponding to positive and negative quantization representative values in accordance with positive and negative symmetrical midtread type quantization characteristics.

Claim 9

A coding device comprising: (a) input means for inputting a value to be quantized; and (b) quantizing means for converting the value to be quantized which was input from the input means into a coding code of n bits, wherein the quantizing means can output the coding code corresponding to a predetermined quantization representative value and a special coding code selectively corresponding to positive and negative quantization representative values in accordance with positive and negative symmetrical midtread type quantization characteristics.

Claim 10

A device according to claim 7, further comprising switching means for switching the quantizing means between a first mode to make the special coding code correspond to the positive quantization represent­ative value and a second mode to make the special coding code correspond to the negative quantization represent­ative value.

Claim 11

A device according to claim 8, wherein the input means includes: arithmetic operating circuit for operating a difference value between a sample value and its predictive value and for supplying the difference value as the value to be quantized to the quantizing means; an inverse quantization circuit to convert the coding code into the quantization representative value corresponding to the difference value; a decoding circuit for operating a decoded value by using an output of the inverse quantization circuit and the predictive value; and a predicting circuit to form the predictive value by using the decoded value.

Claim 12

A device according to claim 9, wherein the switching means switches the quantizing means between the first and second modes in accordance with whether the predictive value is a predetermined value or more or not.

Claim 13

A coding device comprising: (a) an inputting circuit to input a sample value; (b) an arithmetic operating circuit to operate a difference value between the sample value and its predictive value; (c) a quantization circuit to convert the difference value into a coding code; (d) a discriminating circuit to discriminate whether a range of a value which the difference value can be set is wide for either a positive value or a negative value; and (e) a switching circuit to switch the quantiza­tion circuit in accordance with an output of the discriminating circuit between a first mode in which the number of coding codes corresponding to the positive quantization representative values is larger than the number of coding codes corresponding to negative quantiza­tion representative values and a second mode in which the number of coding codes corresponding to the negative quantization representative values is larger than the number of coding codes corresponding to the positive quantization representative values.

Claim 14

A coding device comprising: (a) an inputting circuit to input a sample value; (b) an arithmetic operating circuit to operate a difference value between the sample value and its predictive value; (c) a quantization circuit to convert the difference value into a coding code; (d) a discriminating circuit to discriminate whether a range of a value which the difference value can be set is wide for either a positive value or a negative value; and (e) a switching circuit to switch the quantiza­tion circuit in accordance with an output of the discriminating circuit between a first mode in which the number of coding codes corresponding to the positive quantization representative values is larger than the number of coding codes corresponding to negative quantiza­tion representative values and a second mode in which the number of coding codes corresponding to the negative quantization representative values is larger than the number of coding codes corresponding to the positive quantization representative values.

Claim 15

A device according to claim 11, wherein the switching circuit switches the quantization circuit between the first and second modes in accordance with whether the predictive value is a predetermined value or more or not.

Claim 16

A device according to claim 12, wherein the switching circuit includes a circuit to extract the most significant bit of the predictive value.

Claim 17

A device according to claim 12, wherein the switching circuit includes a comparison circuit to compare the predictive value and the predetermined value.

Claim 18

A device according to claim 11, wherein in the first and second modes, all of the coding codes excluding the special coding code correspond to common quantization representative values.