US 6,308,194 B1 · Discrete cosine transform circuit and operation method thereof

Abstract

There is disclosed a discrete cosine transform circuit for use in a voice recording/reproducing device to solve problems that RAM in which data is stored is frequently accessed and that the power consumption is large. In discrete cosine transform, an algorithm can be constituted to include four or less items of operand data in one operation equation. Correspondingly, four registers 62-1 to 62-4 are arranged on the output side of RAM 60. The discrete cosine transform includes a predetermined regularity. For example, a plurality of operation equations using the same operand data are included in the processing. By continuously processing all of the operation equations, the data read into the registers 62-1 to 62-4 can be reused without being overwritten in another processing, so that accesses to RAM 60 can be suppressed.

Claims9

Dependent claims

A discrete cosine transform circuit provided with a multiplier and an adder/subtracter and performing discrete cosine transform represented by the following relational equation between 2M items of time series voice data y(n) represented by a time index of continuous integer n and M items of frequency component data X(k) represented by a wave number index of continuous integer k:

y ⁡ ( n ) = ∑ K = 0 M - 1 ⁢ X ⁡ ( k ) ⁢ cos ⁡ ( π ⁡ ( 2 ⁢ k + 1 ) ⁢ ( 2 ⁢ n + M + 1 ) 4 ⁢ M ) ⁢ ⁢ ( 0 ≤ n < 2 ⁢ M )
said discrete cosine transform circuit comprising:
an operand data memory for storing operand data based on either data before conversion of said time series voice data y(n) or said frequency component data X(k);
four operand data registers able to hold the operand data read from said calculated data memory;
and
an operand data selector for selecting any one of said four operand data registers to transmit the value held by the selected register to said multiplier.

3 more elements

A discrete cosine transform circuit provided with a multiplier and an adder/subtracter, performing discrete cosine transform represented by the following relational equation between 2M items of time series voice data y(n) represented by a time index of continuous integer n and M items of frequency component data X(k) represented by a wave number index of continuous integer k:

y ⁡ ( n ) = ∑ K = 0 M - 1 ⁢ X ⁡ ( k ) ⁢ cos ⁡ ( π ⁡ ( 2 ⁢ k + 1 ) ⁢ ( 2 ⁢ n + M + 1 ) 4 ⁢ M ) ⁢ ⁢ ( 0 ≤ n < 2 ⁢ M )
and performing transform processing including arithmetic operation for obtaining functional values G(j) and G(M−1−j) from two functional values F1(j) and F2(j) (argument j being an integer, and 0≦j<M/2) obtained based on said time series voice data y(n) or said frequency component data X(k) by following operation equation:
G(j)=a0•F1(j)+a1•F1(M/2−1−j)
+a2•F2(j)+a3•F2(M/2−1−j)
G(M−1−j)=a4•F1(j)+a5•F1(M/2−1−j)
+a6•F2(j)+a7•F2(M/2−1−j),
(a0 to a7 being proportional coefficients),
said discrete cosine transform circuit comprising:
an operand data memory for storing said functional values F1(j) and F2(j);
four operand data registers able to hold the value read from said operand data memory;
and
an operand data selector for selecting any one of said four operand data registers to transmit the value held by the selected register to said multiplier.

9 more elements

Dependencies are inferred from the claim text.

Discrete cosine transform circuit and operation method thereof

Life of this patent

Discrete cosine transform circuit and operation method thereof

Life of this patent

Abstract

Claims9