Patent ID: 6574275
Filing Date: 2003-06-03
Classification: H04N

Abstract:
A decoding apparatus comprising:data input means for inputting image data compressed by a motion compensation predictive coding and a DCT (Discrete Cosine Transformation); variable length decoding means for decoding various parameters and quantization DCT coefficients from the data input means; inverse quantizing means for inversely quantizing the quantization DCT coefficients; inverse DCT means for inversely DCT transforming the DCT coefficients which were inversely quantized; motion compensation predicting means for obtaining a motion compensation predictive value; arithmetic operating means for adding reference data which was motion compensated by the motion compensation predicting means and an output of the inverse DCT means; an image memory for storing the reference data which is used for the motion compensation prediction and data for display; and data output means for outputting decoded image data, wherein the image memory comprises a front stage, for compressing the reference data for storage in the image memory, and a post stage, for decompressing the compressed reference data stored in the image memory; wherein the front stage performs data compression based on a combination of a fixed compression system, in which a ratio of a data amount before compression and a data amount after the compression is always constant, and an orthogonal transformation; and wherein the post stage performs data decompression based on a combination of a fixed decompression system, in which a ratio of a data amount before decompression and a data amount after the decompression is always constant, and an inverse orthogonal transformation.