Rate Control Scheme for Video Coding Using Low-Memory-Cost Look-Up Table

This paper presents a new MPEG-4/H.263 rate control scheme. It is applicable to constant-bit-rate transmissions containing equal-interval I-frames. Conventional schemes usually allocate bits equally to each P-frame, resulting in large video quality variations. In this work, in order to smooth quality variations, we allocate bits unequally to each P-frame by its encoding complexity and buffer level. In macroblock (MB) layer, rate-distortion model is usually employed to determine MB QP, but it needs complex floating-point computations. So, instead, we design a simple and effective look-up table, which also relates MB QP, SAD and the texture bit counts. With certain improvements, our table size reduces to only 1/20 of that in reference work, while the scheme still performs well. Experimental results show that, compared with a modified TMN8 rate control scheme, our scheme achieves higher PSNR and smoother PSNR variations, retaining the bit rate proximity and buffer regulation.