| 摘要 |
PURPOSE:To reduce the quantity of arithmetic operation by dividing picture data of one frame into macro blocks each comprising a predetermined number of picture elements, quantizing and coding the data in terms of macro blocks so as to reduce the number of picture elements to be accessed when the activity is obtained. CONSTITUTION:A coded data quantity is controlled by controlling a quantization width thereby controlling a data transfer speed after coding by a variable length coding section 5. A conversion coefficient quantized by a qudntization section 4 is outputted to a coding section 5, and the coefficient quantized by the coding section 5 is variable length coded and the result is transferred to a bit allocation section 8. On the other hand, a picture interleave section 6 interleaves picture elements of picture data of a macro block received from a block division section 1 and the interleaved data are given to an activity calculation section 10 being an activity decision means, in which the activity is obtained in the unit of macro blocks and it is outputted to a quantization width decision section 7. The decision section 7 consists of a normalizing section 11, a multiplier section 12 and a mean value calculation section 13 to obtain the normalized activity. |
