ENCODING DEVICE AND ENCODING METHOD
An encoding device is disclosed in which frequency domain converters ( 701, 702 ) acquire a conversion coefficient in which a frequency band is divided between low end and high end, a sub-band energy calculator ( 703 ) divides either the low end or the high end frequency band of the conversion coefficient into a plurality of sub-bands, an importance assessment unit ( 704 ) sets a degree of importance for each sub-band, a sparse processor ( 705 ), according to the set importance, sets the amplitude value of a specific number of conversion coefficients, from among the plurality of conversion coefficients included in each sub-band, at zero, and a correlation analysis unit ( 706 ) calculates the correlation between the corrected conversion coefficient of one frequency band and the conversion coefficient of the other frequency band.
1 . A coding apparatus comprising:
an acquisition section that acquires transform coefficients whose frequency band is divided between a low-band part and a high-band part;
a division section that divides one frequency band of the low-band part and the high-band part of the transform coefficients into a plurality of subbands;
a setting section that sets a degree of importance for each of the subbands;
a changing section that changes, to zero, amplitude values of a predetermined number of transform coefficients of a plurality of the transform coefficients included in each of the subbands, in accordance with the set degree of importance; and
a calculation section that calculates a correlation between the changed transform coefficients in the one frequency band and the transform coefficients in the other frequency band.
2 . The coding apparatus according to claim 1 , wherein the changing section sets a smaller number of transform coefficients whose amplitude value is changed to zero, for a subband whose degree of importance is higher.
3 . The coding apparatus according to claim 1 , wherein the setting section sets the degree of importance based on energy of each of the subbands.
4 . The coding apparatus according to claim 3 , wherein the setting section sets a higher degree of importance for a subband whose energy is larger.
5 . The coding apparatus according to claim 1 , wherein the changing section changes, to zero, the amplitude values of the predetermined number of transform coefficients whose amplitude value is smaller, among the plurality of transform coefficients in each of the subbands.
6 . The coding apparatus according to claim 1 , wherein the calculation section calculates the correlation for obtaining an amount of shift indicating the transform coefficients in the low-band part most similar to the transform coefficients in the high-band part.
7 . The coding apparatus according to claim 1 , wherein the setting section sets the degrees of importance such that the respective degrees of importance of the subbands are always different from one another.
8 . A communication terminal apparatus comprising the coding apparatus according to claim 1 .
9 . A base station apparatus comprising the coding apparatus according to claim 1 .
10 . A coding method comprising:
acquiring transform coefficients whose frequency band is divided between a low-band part and a high-band part;
dividing one frequency band of the low-band part and the high-band part of the transform coefficients into a plurality of subbands;
setting a degree of importance for each of the subbands;
changing, to zero, amplitude values of a predetermined number of transform coefficients of a plurality of the transform coefficients included in each of the subbands, in accordance with the set degree of importance; and
calculating a correlation between the changed transform coefficients in the one frequency band and the transform coefficients in the other frequency band.