Rate control algorithms aim to achieve perceivable video quality for real-time video communication applications under some real-world constraints, such as bandwidth, delay, buffer sizes etc. This study presents an adaptive and efficient rate control framework for low-delay H.264/AVC video communication. At the basic unit level, to realise quantisation decision improvement, a novel rate-qantisation (R-Q) model is proposed for P frame. This P frame R-Q model is established through the ρ domain rate control theory to compute quantisation according to target bit assignment. In addition, an I frame R-Q model is presented to measure frame level coding activity for quantisation decision without performing computationally intensive intra-prediction, which helps alleviating the frame skipping problem. When compared with Joint Video Team (JVT)-G012, a rate control scheme adopted by JVT H.264/AVC reference software JM12.3, the proposed rate control framework shows good performance in terms of improved average luminance peak signal noise ratio (PSNR), reduced number of skipped frames and smaller mismatch between target and actual bit rates.