Patent ID: 7209593
Filing Date: 2007-04-24
Classification: H03M

Abstract:
1. An encoding apparatus for storing an interval size and an interval limit value, dividing an interval set on a number line, selecting a sub-interval corresponding to an occurring symbol, updating the interval to the sub-interval selected, and based on the sub-interval selected, updating the interval size and the interval limit value with a limited precision, and encoding a coordinate within the interval, comprising: a probability learning unit for learning occurrence probability of a symbol and storing an occurrence probability of the symbol learned in a storage area; a sub-interval computing unit for obtaining a sub-interval size using the occurrence probability of the symbol stored at the probability learning unit, and for computing a sub-interval limit value corresponding to the sub-interval size; a first renormalizing unit for renormalizing the sub-interval size so that the sub-interval size obtained at the sub-interval computing unit is equal to or greater than a predetermined value; a second renormalizing unit for renormalizina the sub-interval limit value with a same expansion rate as one used at the first renormalizing unit; a correction value computing unit for computing a size correction value which corrects the sub-interval size and a limit correction value which corrects the sub-interval limit value; an interval correcting unit for correcting the sub-interval size renormalized at the first renormalizing unit using the size correction value computed at the correction value computing unit and outputting the sub-interval size corrected as the interval size; and an interval limit value correcting unit for correcting the sub-interval limit value renormalized at the second renormalizing unit using the limit correction value computed at the correction value computing unit and outputting the sub-interval limit value corrected as the interval limit value; and wherein the interval size and the interval limit value are corrected whenever the symbol is encoded; wherein the limited precision used for computing the interval size of the set interval is defined as a previous managing precision and the limited precision used for computing the sub-interval size is defined as a current managing precision, wherein the sub-interval computing unit sets the current managing precision higher than the previous managing precision and obtains the sub-interval size by computing a product of the interval size of the set interval and the occurrence probability of the symbol based on the current managing precision set, and wherein the correction value computing unit computes a difference between the previous managing precision and the current managing precision as an additional precision and computes the size correction value and the limit correction value based on the additional precision computed.