Frame Skipping/Interpolation Algorithms Of Rate Control In H.264 At Low Bit Rate

With the rapid development of the multimedia communication technology, efficient and high quality compression digital video transmission technology has become one hot topic of the research and development nowadays. As a new generation of video coding standard, H.264 has high coding efficiency and wide application prospects by using a series of new technologies. In order to get higher reconstruction video quality in the variable channel bandwith, the rate control technology is used to control the bitrate.Based on the thorough research of rate control principle and algorithm in H.264, the frame skipping algorithm of the rate control in the low bit rate is researched and improved. Contrasting the original passive frame skipping algorithm, a new active frame skipping algorithm is propsed in this paper. By fully considering the complexity of image motion, the encoded frame quality and the occupancy of the encoding buffer, the proposed algorithm can adaptively decide whether to skip the next frame, which makes bit allocation of the video sequence more rationally.Corresponding to the encoder, the interpolation algorithm used at the decoder is also improved in this paper. The improved algorithm uses the bilateral motion vector estimation for the motion-compensated frame interpolation and smooths the motion vector twice in the motion vector estimation. Using the adjusted motion vector in the motion-compensated frame interpolation and considering the situation in which the pixels pointed by the motion vector are over the image boundary, the subjective quality and PSNR of the decoded frames are improved.The simulation experiments of the algorithm are on MATLAB and JM10.2. The experiments results show that the visual quality and PSNR with the proposed algorithm are improved comparing with the original frame interpolation algorithm by using the more accurate motion vector estimation; the visual quality and PSNR with the proposed active frame skipping algorithm are improved comparing with the orginal rate control algorithm which only modifies the quantitative parameters.