Data compression methods and systems with quantization distortion measurement means

Claim 2

A data transmission system comprising: quantizing means for quantizing a data signal into quantized data to be transmitted; decoding means operative to generate a decoded data signal from the quantized data; distortion measurement means for measuring distortion of said quantized data based upon the data signal and the decoded data signal; first quantization step size control means for controlling the step size of quantization in said quantizing means based upon the distortion measured by the distortion measurement means, the step size of quantization controlled to maintain the distortion constant; data quantity measurement means for measuring a quantity of said quantized data; second quantization step size control means for controlling the step size of quantization in said quantizing means according to said quantity of quantized data to be transmitted; and switching means for switching an input of the quantizing means between a first quantization step size control signal output from said first quantization step size control means and a second quantization step size control signal output from said second quantization step size control means.

Claim 3

The data transmission system according to claim 1, wherein said decoding means further comprises: inverse quantizing means operative to inverse quantize the quantized data; and an addition circuit having a first input coupled to an output of the inverse quantizing means, a second input coupled to an output of a delay circuit, the delay circuit having an input coupled to an output of the addition circuit.

Claim 4

The data transmission system according to claim 2, wherein said decoding means further comprises: means for applying the output of said addition circuit to a subtraction circuit to obtain differential data between said output of said addition circuit and said data signal to be transmitted, and for applying said differential data to the distortion measurement means.

Claim 5

The data transmission system according to claim 3, wherein said distortion measurement means further comprises: a distortion measurement judgment circuit including a square calculation circuit operative to square said differential data, an integration circuit operative to integrate an output of said square calculation circuit and a square root calculation circuit operative to calculate the square root of an output of said integration circuit.

Claim 6

The data transmission system according to claim 1, wherein said switching means further comprises: means for selecting for input to the quantizing means said first quantization step size control signal when the information quantity per a predetermined unit time of said quantized data does not exceed a predetermined reference value and selecting for input to the quantizing means said second quantization step size control signal when the information quantity per a predetermined unit time of said quantized data exceeds said predetermined reference value.

Claim 7

A data transmission system producing quantized data from an information signal via quantizing means and transmitting said quantized data, said system comprising: first quantization step size control means for controlling the quantization step size of said quantizing means to a constant; generated information quantity measurement means for measuring generated information quantity of said quantized data; second quantization step size control means for controlling the quantization step size of said quantizing means on the basis of the generated information quantity so that the generated information quantity of said quantized data is kept to a constant; first switching means selecting and outputting, in accordance with the generated information quantity of said quantized data, between a first quantization step size control signal provided by said first quantization step size control means and a second quantization step size control signal provided by said second quantization step size control means; and second switching means for selecting between the selected output provided by the first switching means and the first quantization step size control signal, and for outputting a signal selected by the second switching means to said quantizing means.

Claim 8

A data transmission system producing quantized data from an information signal via quantizing means and transmitting said quantized data, said system comprising: first quantization step size control means for controlling the quantization step size of said quantizing means to a constant; generated information quantity measurement means for measuring generated information quantity of said quantized data; second quantization step size control means for controlling the quantization step size of said quantizing means on the basis of the generated information quantity so that the generated information quantity of said quantized data is kept to a constant; first switching means selecting and outputting, in accordance with the generated information quantity of said quantized data, between a first quantization step size control signal provided by said first quantization step size control means and a second quantization step size control signal provided by said second quantization step size control means; and second switching means for selecting between the selected output provided by the first switching means and the first quantization step size control signal, and for outputting a signal selected by the second switching means to said quantizing means.

Claim 11

The method of transmitting data according to claim 7, wherein the step of decoding the quantized data further comprises the steps of: inverse quantizing the quantized data; delaying an output of an adder; and adding the delayed output of the adder to the inverse quantized quantized data to thereby generate the output of the adder.

Claim 12

The method of transmitting data according data transmission system according to claim 8, wherein the step of decoding the quantized data further comprises the steps of: subtracting the output of the adder from the data signal to generate differential data representative of distortion of the quantized data.

Claim 13

A method of transmitting data according to claim 9, wherein the step of measuring distortion further comprises the steps of: squaring the differential data; integrating the squared differential data; and determining the square root of the integrated squared differential data.

Claim 14

The method of transmitting data according to claim 7, wherein step of selectively switching further comprises the steps of: selecting a first quantization step size when information quantity representing the information quantity per a predetermined unit time of said quantized data does not exceed a predetermined reference value and selecting a second quantization step size when the information quantity representing the information quantity per a predetermined unit time of said quantized data exceeds said predetermined reference value.

Claim 17

A data transmission system comprising: quantizing means for quantizing a data signal into quantized data to be transmitted; decoding means operative to generate a decoded data signal from the quantized data; distortion measurement means for measuring distortion of said quantized data based upon the data signal and the decoded data signal; first means for controlling the step size of quantization in said quantizing means based upon the distortion measured by the distortion measurement means, the step size of quantization controlled to maintain the distortion constant; data quantity measurement means for measuring a quantity of the quantized data to be transmitted; second means for controlling the step size of quantization in said quantizing means according to said quantity of quantized data to be transmitted; third means for controlling the step size of quantization in said quantizing means to be constant; first switching means for switching an input of the quantizing means between a first quantization step size control signal from the first quantization step size control means and a third quantization step size control signal from the third quantization step size control means; second switching means for switching the input of the quantizing means between an output of the first switching means and a second quantization step size control signal from the second quantization step size control means; and third switching means for switching the input of the quantizing means between the first switching means and the second switching means.

Claim 18

A data transmission system comprising: quantizing means for quantizing a data signal into quantized data to be transmitted; decoding means operative to generate a decoded data signal from the quantized data; distortion measurement means for measuring distortion of said quantized data based upon the data signal and the decoded data signal; first means for controlling the step size of quantization in said quantizing means based upon the distortion measured by the distortion measurement means, the step size of quantization controlled to maintain the distortion constant; data quantity measurement means for measuring a quantity of the quantized data to be transmitted; second means for controlling the step size of quantization in said quantizing means according to said quantity of quantized data to be transmitted; third means for controlling the step size of quantization in said quantizing means to be constant; first switching means for switching an input of the quantizing means between a first quantization step size control signal from the first quantization step size control means and a third quantization step size control signal from the third quantization step size control means; second switching means for switching the input of the quantizing means between an output of the first switching means and a second quantization step size control signal from the second quantization step size control means; and third switching means for switching the input of the quantizing means between the first switching means and the second switching means.