Patent ID: 6088392
Filing Date: 2000-07-11
Classification: H04N

Abstract:
Apparatus for line-by-line feed forward bit-rate control of a differentially quantized signal representing a frame having an array of blocks, said frame having a given number of lines and given number of blocks in each line, each of said blocks having a data value and being in a region, each region having a respective set of available quantizer values for use in quantizing said data value in a block, said apparatus comprising:bit-rate calculating means for iteratively determining a bit rate for each block in each line in the frame;bit-rate control means for determining when the calculated bit rate for the frame exceeds a given target rate;quantizer adjustment means for reducing the quantizer for one region in a next line when the calculated bit rate for the frame does not exceed said given target rate;rate-assist means for reducing four motion vectors to one in edge blocks of the one region that follow blocks in another region and forcing coding of a respective quantizer change value; anda bypass path for bypassing said bit rate calculation means for preventing determination of a bit rate for a block where a respective maximum value in each block is not greater than the respective quantizer value used in a given iteration for quantizing the data value in said block.