US 5,847,977 AGranted

Method for performing an inverse modified discrete cosine transform

AssigneeSamsung Electronic Co., Ltd.

InventorYon-Hong Jhung

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Abstract

A method of performing an inverse modified discrete cosine transform (IMDCT) which reduces the amount of calculation, in which IMDCT values y.sub.m (r) expressed in vector form as Y.sub.m =CX.sub.m, where Y.sub.m, C, and X.sub.m represent matrices are obtained by defining values of X.sub.k (m) for ##EQU1## calculating values of y.sub.m (r) for ##EQU2## with respect to an upper half of an upper portion of Y.sub.m by performing calculation with respect to an upper part of an upper portion of a left half of C and with respect to an upper half of X.sub.m ; calculating values of y.sub.m (r) with respect to a lower half of the upper portion of Y.sub.m by inverting the values of y.sub.m (r) with respect to the upper half of the upper portion of Y.sub.m and arranging the inverted values in a reverse manner; calculating the values of y.sub.m (r) for ##EQU3## with respect to an upper half of a lower portion of Y.sub.m by performing calculation with respect to an upper part of a lower portion of the left half of C and with respect to the upper half of X.sub.m ; and calculating values of y.sub.m (r) with respect to a lower half of the lower portion of Y.sub.m arranging values of y.sub.m (r) in a reverse manner with respect to the upper half of the lower portion of Y.sub.m.

Claims8

Dependent claims

A method of performing an inverse modified discrete cosine transform (IMDCT) whereby values of the IMDCT represented by y.sub.m (r) are obtained according to the following equation:

##EQU44## where k is a number of subband channels, x.sub.k (m) are IMDCT coefficients, ##EQU45## and 0.ltoreq.r.ltoreq.K-1, and Y.sub.m =CX.sub.m
where Y.sub.m is a matrix of order 1.times.K(=2M), C is a matrix of order K.times.K, and X.sub.m is a matrix of order 1.times.K, the method comprising:
providing a computing device;
supplying the IMDCT coefficients for ##EQU46## to said computing device;
using said computing device to calculate values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU47## with respect to an upper half of an upper portion of the matrix Y.sub.m by performing calculation with respect to an upper part of an upper portion of a left half of the matrix C and with respect to an upper half of the matrix X.sub.m ;
using said computing device to calculate the values of y.sub.m (r) with respect to a lower half of the upper portion of the matrix Y.sub.m by inverting the values of y.sub.m (r) with respect to the upper half of the upper portion of the matrix Y.sub.m and by arranging the inverted values in a reverse manner;
using said computing device to calculate the values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU48## with respect to an upper half of a lower portion of the matrix Y.sub.m by performing calculation with respect to an upper part of a lower portion of the left half of the matrix C and with respect to the upper half of the matrix X.sub.m ;
using said computing device to calculate values of y.sub.m (r) with respect to a lower half of the lower portion of the matrix Y.sub.m by arranging the values of y.sub.m (r) in a reverse manner with respect to the upper half of the lower portion of the matrix Y.sub.m and;
outputting from said computing device said values of y.sub.m (r) with respect to the upper half of the upper portion of the matrix Y.sub.m, said values with respect to the lower half of the upper portion of the matrix Y.sub.m, said values with respect to the upper half of the lower portion of the matrix Y.sub.m and said values of y.sub.m (r) with respect to the lower half of the lower portion of the matrix Y.sub.m.

6 more elements

A method of performing an inverse modified discrete cosine transform (IMDCT) whereby values of the IMDCT are represented by y.sub.m (r) which are obtained according to the following equation:

##EQU49## where, k is a number of subband channels, x.sub.k (m) are IMDCT coefficients, ##EQU50## and 0.ltoreq.r.ltoreq.K-1, and Y.sub.m =CX.sub.m
where Y.sub.m is a matrix of order 1.times.K(=2M) , C is a matrix of order K.times.K, and X.sub.m is a matrix of order 1.times.K, the method comprising:
providing a computing device;
supplying the IMDCT coefficients for ##EQU51## to said computing device;
using said computing device to calculate values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU52## with respect to a lower half of an upper portion of the matrix Y.sub.m by performing a calculation with respect to a lower part of an upper portion of a left half of the matrix C and with respect to an upper half of the matrix X.sub.m ;
using said computing device to calculate values of y.sub.m (r) with respect to an upper half of the upper portion of the matrix Y.sub.m by inverting the values of y.sub.m (r) with respect to the lower half of the upper portion of the matrix Y.sub.m and by arranging the inverted values in a reverse manner;
using said computing device to calculate the values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU53## with respect to a lower half of a lower portion of the matrix Y.sub.m by performing calculation with respect to a lower part of a lower portion of the left half of the matrix C and with respect to the upper half of the matrix X.sub.m ;
using said computing device to calculate the values of y.sub.m (r) with respect to an upper half of the lower portion of the matrix Y.sub.m by arranging the values of y.sub.m (r) in a reverse manner with respect to the lower half of the lower portion of the matrix Y.sub.m ;
and
outputting from said computing device said values of y.sub.m (r) with respect to the lower half of the upper portion of the matrix Y.sub.m, said values with respect to the upper half of the upper portion of the matrix Y.sub.m said values with respect to the lower half of the lower portion of the matrix Y.sub.m and said values of Y.sub.m (r) with respect to the upper half of the lower portion of the matrix Y.sub.m.

7 more elements

A method of performing an inverse modified discrete cosine transform (IMDCT) whereby values of the IMDCT represented by y.sub.m (r) are obtained according to the following equation ##EQU54## where, k is a number of subband channels, x.sub.k (m) are IMDCT coefficients, ##EQU55## and 0.ltoreq.r.ltoreq.K-1, and Y.sub.m =CX.sub.m

where, Y.sub.m is a matrix of order 1.times.K(=2M) , C is a matrix of order K.times.K, and X.sub.m is a matrix of order 1.times.K, the method comprising:
providing a computing device;
supplying the IMDCT coefficients for ##EQU56## to said computing device;
using said computing device to calculate values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU57## with respect to a lower half of an upper portion of the matrix Y.sub.m by performing calculation with respect to a lower part of an upper portion of a left half of the matrix C and with respect to an upper half of the matrix X.sub.m ;
using said computing device to calculate the values of y.sub.m (r) with respect to an upper half of the upper portion of the matrix Y.sub.m by inverting the values of y.sub.m (r) with respect to the lower half of the upper portion of the matrix Y.sub.m and by arranging the inverted values in a reverse manner;
using said computing device to calculate the values of y.sub.m (r) based on the IMDCT coefficients according to the X equation for ##EQU58## with respect to an upper half of a lower portion of the matrix Y.sub.m by performing calculation with respect to an upper part of a lower portion of the left half of the matrix C and with respect to the upper half of the matrix X.sub.m ;
using said computing device to calculate the values of y.sub.m (r) with respect to a lower half of the lower portion of the matrix Y.sub.m by arranging the values of y.sub.m (r) in a reverse manner with respect to the upper half of the lower portion of the matrix Y.sub.m ;
and
outputting from said computing device said values of Y.sub.m with respect to the lower half of the upper portion of the matrix Y.sub.m said values with respect to the upper half of the upper portion of the matrix Y.sub.m, said values with respect to the upper half of the lower portion of the matrix Y.sub.m and said values of Y.sub.m (r) with respect to the lower half of the lower portion of the matrix Y.sub.m.

6 more elements

A method of performing an inverse modified discrete cosine transform (IMDCT) whereby values of the IMDCT represented by y.sub.m (r) are obtained according to a following equation ##EQU59## where k is a number of subband channels, x.sub.k (m) are IMDCT coefficients ##EQU60## and 0.ltoreq.r.ltoreq.K-1, and Y.sub.m =CX.sub.m

where, Y.sub.m is a matrix of order 1.times.K(=2M) , C is a matrix of order K.times.K, and X.sub.m is a matrix of order 1.times.K, the method comprising:
providing a computing device;
supplying the IMDCT coefficients for ##EQU61## to said computing device;
using said computing device to calculate values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU62## with respect to an upper half of an upper portion of the matrix Y.sub.m by performing calculation with respect to an upper part of an upper portion of a left half of the matrix C and with respect to an upper half of the matrix X.sub.m ;
using said computing device to calculate the values of y.sub.m (r) with respect to a lower half of the upper portion of the matrix Y.sub.m by inverting the values of y.sub.m (r) with respect to the upper half of the upper portion of the matrix Y.sub.m and by arranging the inverted values in a reverse manner;
using said computing device to calculate the values of y.sub.m (r) based on the IMDCT coefficients according to the equation for ##EQU63## with respect to a lower half of a lower portion of the matrix Y.sub.m by performing calculation with respect to a lower part of a lower portion of the left half of the matrix C and with respect to the upper half of the matrix X.sub.m ;
and
using said computing device to calculate the values of y.sub.m (r) with respect to an upper half of the lower portion of the matrix Y.sub.m by arranging the values of y.sub.m (r) in a reverse manner with respect to the lower half of the lower portion of the matrix Y.sub.m ;
and
outputting from said computing device said values o f Y.sub.m (r) with respect to the upper half of the upper portion of the matrix Y.sub.m said values with respect to the lower half of the upper portion of the matrix Y.sub.m, said values with respect to the lower half of the lower portion of the matrix Y.sub.m, and said values of Y.sub.m (r) with respect to the upper half of the lower portion of the matrix Y.sub.m.

7 more elements

Dependencies are inferred from the claim text.