Video encoding method and apparatus for estimating a code amount based on bit string length and symbol occurrence frequency

Abstract

A video encoding apparatus includes a frequency transform unit for executing an orthogonal transform on a prediction difference or an original image; a quantizing unit for quantizing transform coefficients outputted by the frequency transform unit; a variable-length coder for executing variable-length encoding on a bit string generated from the quantized transform coefficients; a rate controller for performing a rate control to control a code bit stream outputted by the variable-length coder to be maintained at a bit rate; and a code amount estimating unit for estimating a code amount to be generated by the variable-length coder based on a length of the bit string and an occurrence frequency of symbol in the bit string. The rate controller executes the rate control based on the estimated code amount.