Patent ID: 8345767

Claim:
A video encoding method, comprising: a binary-sequence conversion step of converting syntax data of an image block into a binary sequence; a binary arithmetic encoding step of encoding each symbol of the binary sequence subject to its corresponding context; an estimation step of estimating a bit number required for binary arithmetic encoding of the syntax data of the image block; a coded data decision step of deciding whether or not to encode said syntax data of the image block in said binary arithmetic encoding step and to output it responding to the bit number estimated in said estimation step; and a context update step of updating said context corresponding to the syntax data of the image block decided to be encoded in said binary arithmetic encoding step and to be outputted in said coded data decision step, and not updating said context corresponding to the syntax data of the image block not to be encoded in said binary arithmetic encoding step and not to be outputted in said coded data decision step, wherein, in said estimation step, a maximum value of the number of binary arithmetic encoding output bits for its input symbols is defined as said number of bits; and wherein, in the estimation step, the maximum value of the number of the arithmetic encoding output bits is obtained on the basis of one-symbol-unit calculation of a minimum value of less-probable-symbol occurrence probabilities, and plural-symbol-unit calculation of a minimum value of a product of less-probable-symbol occurrence probabilities in a case where less-probable-symbols occur successively.