Method of compression-coding a motion picture and an apparatus for same

Abstract

A method and an apparatus for compression-coding of thinned-out motion picture frame are described. A received motion picture data is subject to DCT (discrete cosine transformation). The DCT coefficients are stored in a frame memory, and also accumulated over a frame of the received motion picture concerned. The accumulated value is used as a predicted code amount of the received frame concerned. The DCT coefficients stored in the frame memory are read and quantized two times. A first quantization step for the first quantization is selected based on a reference code amount, the accumulated value and the final code amount (described below) of the motion picture frame received immediately before the frame concerned. After the first quantization, the quantized DCT coefficients are variable-length-coded to produce a first series of codes of a first code amount. A coarse quantization step is selected as a second quantization step for second quantization when the first code amount is larger than the reference code amount, and when the first code amount is vice versa, a fine quantization step is selected. The DCT coefficients read for the second time are quantized according to the second quantization step, variable-length-coded to produce a second series of codes of a second code amount. Of the two code amounts, the code amount closer to the reference code amount is determined as a final code amount and the series of codes having the final code amount is outputted as variable-length-codes of the motion picture frame concerned.