Rate control for low-delay video using a dynamic rate table

The conventional rate control schemes employ rate-distortion (R-D) models which need complex floating-point computation. In this work, we present a simple and effective rate-control algorithm that involves only fixed-point operation. Instead of using mathematical R-D model, we design a dynamic rate table that relates the coding bit count, encoding complexity, and quantization parameter for each macroblock (MB). The table contains the R-D information implicitly and is updated dynamically on an MB-by-MB basis to reflect the variation of video contents. We implement our technique in H.263 and compare its performance to TMN8 rate control. The experimental results indicate the new technique performs better than TMN8 in terms of PSNR, frame skipping, bit-rate proximity, and buffer steadiness. More importantly, our technique needs only integer operations, which offers significant advantage in hardware implementation.