Study Of Digital Video Technology Of Downhole Based On H.264

Down Hole Video is a logging instrument used to obtain downhole image in oil field,and becomes an important logging technology.It developed on aboard have made successful application,and gained great commercial benefits.While it is just beginning research in downhole video logging instrument field in our country.The major purpose of this dissertation is to study digital video technology of downhole based on H.264. The major content and outcome is listed as follows.1.Study of the downhole digital video compressed codinga)A fast H.264 Intra-prediction mode selection scheme is proposed in this paper. The proposed method uses spatial and transform domain features of the target lock jointly to filter out the majority of candidate modes.This is justified by examining the posterior error probability.For the final mode selection,only 2-3 candidate modes need cumulated.It is demonstrated by experimental results that the encoding rate of the proposed scheme is 10 times than referred in H.264b)This paper introduces a multi-stage motion estimation algorithm.The algorithm ensures getting good video quality while decreases the motion search time efficiently.It divides the search regions into many un-overlapped small-diamond regions and forces the motion search to go outward for larger motion vectors.This method is also designed to avoid mistaking local optimal motion vectors.Experimental results show that the proposed algorithm has a speed-up factor which is about 40 times faster than FS,and is about 4 times faster than UMHexagonS.2.Study of the downhole digital video transmissionThis paper introduces an efficient combination of turbo coding and hierarchical quadrature amplitude modulation(HQAM)to provide a high protection for the HP layer and at the same time maintaining the requisite channel coding redundancy.Simulation results show that,over a wide range of channel signal-to-noise ratio(SNR),the combined technique is superior to non-scalable transmission and outperforms UEP with turbo coding alone.