Improved ρ-domain rate control with accurate header size estimation

p-domain rate control has been shown to be a simple yet effective rate control approach for DCT-based hybrid video codecs. When it is applied to H.264/AVC, improvements need to be made because of the large amount of header information and the QP-dependent Rate Distortion Optimization (RDO). In this paper, we propose a novel rate model to estimate the size of header information accurately. We present a two-stage rate control algorithm which combines the proposed header rate model and the p-domain source model. In comparison to the original p-domain rate control algorithm without header size estimation, our scheme not only improves the PSNR of the decoded video, but also achieves the target bit rates more accurately.