To facilitate the diversity of network and end-user devices, bit allocation technology must be combined with scalable high efficiency video coding (SHVC) to achieve continuous bitrate variation. However, to date, the multilayer coding feature in SHVC has not been fully utilized. In this paper, a bit allocation algorithm is proposed for the enhancement layer in SHVC. The algorithm includes two parts: a bit allocation method for the initial frame and another for subsequent frames. The bit allocation method for the initial frame consists of a bit allocation factor model constructed based on investigation of the influence of the initial target bitrate on the overall coding performance. For the bit allocation of the subsequent frames, alternate GOP coding is designed and implemented to fully exploit the inter layer correlation. In addition, an adaptive frame layer bit allocation ratio model is deduced according to the rate distortion optimization theory. Experimental results show that the proposed algorithm can improve PSNR by 0.44 dB and 0.41 dB under low delay and random-access configurations, respectively, and achieve high bitrate control accuracy. The algorithm also outperforms the state-of-the-art algorithms in term of PSNR improvement.

为了促进网络和最终用户设备的多样性，必须将比特分配技术与可伸缩的高效视频编码（SHVC）结合使用，以实现连续的比特率变化。但是，迄今为止，SHVC中的多层编码功能尚未得到充分利用。本文针对SHVC中的增强层提出了一种比特分配算法。该算法包括两部分：一个用于初始帧的位分配方法，另一个用于后续帧的位分配方法。初始帧的比特分配方法由一个比特分配因子模型组成，该模型是基于调查初始目标比特率对整体编码性能的影响而构建的。对于后续帧的比特分配，设计并实现了备用GOP编码，以充分利用层间相关性。此外，根据速率失真优化理论推导了自适应帧层比特分配比模型。实验结果表明，该算法在低延迟和随机接入配置下，可以分别提高PSNR 0.44 dB和0.41 dB，并达到较高的比特率控制精度。在PSNR改善方面，该算法还优于最新算法。