在P域的码率控制中，由于编码比特尺和一帧图像的变换量化系数中的零的百分比之间的关系起着非常重要的作用，因此为了更好地进行码率控制，首先研究了线性率失真函数在可分级视频编码（scalable video coding，SVC）中基本层上的可适用性，然后分别对模型参数进行统计，结果表明，统计曲线显示了在同一个时间子带上的帧有着相近的线性模型参数。结合以上特征，通过最小二乘法实现了线性模型在SVC基本层上的码率控制应用，并且在JSVM1．0上实现了该算法。实验表明，该码率控制算法很有效，与TM5算法相比，峰值信噪比（Peak signal noise ratio．PSNR）增加。

The relationship of the coding bit rateRandρ, the percentage of zeros in a frame, plays an important role in ρ domain sourcemodeling rate contro.l TheR2D model is verified for Scalable Video Coding(SVC) at first. Then we studied the characteristic of the ρ2 Rcurve of pictures when encoding various test sequences with scalable video coding. We find that the model parameter of the pictures at the same temporal level have a close valve. Then an adaptive estimation scheme to estimate this model parameter is provided. Combining with its encoding feature, we propose an effective rate control scheme for the base layer of the scalable codec. We implement our algorithm in JSVM 1.0. The experimental results demonstrate that the outputbit stream of encoder is controlled accurately.