Patent ID: 6292817
Filing Date: 2001-09-18
Classification: G06F

Abstract:
A discrete cosine transformation circuit for use in a digital audio recording/reproducing device, for carrying out discrete cosine transformation from time series audio data to frequency component data and inverted discrete cosine transformation from frequency component data to time series audio data, comprising:a first memory for storing the frequency component data which is data before conversion at beginning of reproduction;a coefficient supplier for supplying a proportional coefficient for multiplication with the data read from the first memory;a multiplier connected to the first memory and the coefficient supplier;an adder/subtracter having first input terminal and second input terminal, connected to an output of the multiplier;a second memory connected on the output side to the first input terminal of the adder/subtracter, for storing the time series audio data which is data before conversion at beginning of recording;an addition-subtraction result register for storing an output from the adder/subtracter; andan addition-subtraction result selector connected on the output side to the second input terminal of the adder/subtracter, for outputting either contents of the addition-subtraction result register or a value ""0"",the frequency component data being transformed to the time series audio data for reproduction,the addition-subtraction result selector outputting the value ""0"" when data read from the second memory is supplied intact to the second input terminal of the adder/subtracter so that an output from the multiplier is stored intact in the addition-subtraction result register,the time series audio data being transformed to the frequency component data for recording.