| 摘要 |
<p>A method and apparatus are provided for regulating the bit stream generated by a hybrid DPCM/DCT video codec so that the compressed bit stream at a variable rate can be transmitted over a fixed rate channel. The bit rate regulation is accomplished by appropriately quantizing the DCT coefficients where the quantization stepsize is obtained by multiplying a fixed weighting matrix by a scaling factor. For each frame, a single quantization scaling factor is determined by iteratively comparing the output bit rate with the target bit rate which is based upon the desirable bit rate, frame code mode and scene changes. The iterative comparison guarantees a quantization scaling factor which results in a minimum accumulated bit rate difference from the target bit rate for each frame.</p> |
