| 摘要 |
PURPOSE:To improve an encoding efficiency by providing a constant relation between the quantized value of the sample of a predictive error signal and a sample interval in either one of encoding processes, lowering a sample density and compressing the quantity of data in a part in which the change of an input signal is small. CONSTITUTION:An original picture stored in a picture memory 1 is compressed, encoded, the compressed code obtained by compressing and encoding is then decoded and a first reproduced picture is stored in a picture memory 4. The first reproduced picture of the picture memory 4 is subtracted from the original picture of the picture memory 1, the obtained error picture is divided into blocks, the respective blocks are decided one by one to be the block (valid block) large in the error and the block small in the error (invalid block) based on a signal distribution in the block in a valid/invalid decision part 7, only the valid block is compressed and encoded, the obtained compressed code is stored in a code memory 9 together with position information indicating the position of the valid block. Thereby, the efficient encoding can be carried out.
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