Research Of Rate Control Strategy In H.264 Based On The Mechanism Of TFRC

For the purpose of making the development of multimedia transmissionsatisfy the people's requirement of diversity of the network's content, theincompatible problem between the TCP-unfriendly and the picture qualitiesin the video network transmission at present is studied in this paper. Bymaking improvement on the rate control strategy in the H.264 which baseson the TFRC mechanism, the picture quality of the H.264 TCP-friendlyvideo stream is improved effectively.The main works of this paper:Firstly, the deficiency of the traditional target bit estimation withoutconsidering the frame's complexity is analysed, and a new theoreticalexpression of the frame's complexity is put forward, which bases on themotion vector and the zero-block number of the frame. By using thetheoretical expression to the adjustment of the target bit estimation, thecoded picture quality is effectively improved.Secondly, as the inaccuracy of the MAD (Mean Absolute Difference)prediction in H.264, a new MAD prediction method is carried out, which bases on the grades of the macroblock's complexity.This method has betteruse of the space relativity and higher accuracy of prediction;Thirdly, to ease up the drop of the decoded picture quality caused bythe simplity of the frameskip method in H.264, a new frameskip strategy isdeveloped, which bases on the HOD(Histogram Of Difference) of twoframes.by using this new method, the picture quality is improved.Finally, a TFRC mechanism for the transmission of the H.264 isrealized on the ARM platform. Improvement for the TFRC is made to solvethe problems in video transmission control. The effect of the packet dropration to the R-D(Rate-Distorsion) model is especially analysed. At last, theTCP-friendliness of the H.264 transmission under the control of themechanism, and the improvement of the picture quality are proved by thetest results.