| 摘要 |
PURPOSE:To simplify the control sequence of a generating code quantity controlled variable quantizer and to realize high speed picture with a simple circuit by adding a fixed quantizer of a quantization step size in a CCITT recommendation (H.261) video encoder. CONSTITUTION:A signal transformed by a discrete cosine transformation device 103 is inputted to a fixed quantizer 202, a recorder A203 and a variable quantizer 204 through an input 201. The signal is quantized at the fixed quantizer 202 by a step size 8. The result of quantization by the fixed quantizer 202 and the variable quantizer 204 is inputted to a quantization step size decision device 205, the signals are rearranged in each block and subject to zigzag scanning. Then 2nd to 64th values in figure are used to obtain a generated code quantity in the case of Huffman encoding is obtained by a Huffman coding quantity table 206. Then the optimum quantization step size is obtained by designating the generated code quantity in matching with the transmission line. |
