Fast adaptive inter mode decision method in H.264 based on spatial correlation

The computation complexity of H.264 is so large that make it difficult to be used in practical applications especially in real time environment. In this paper, a fast adaptive inter modes decision method is proposed to reduce the complexity of H.264 encoder. Firstly the candidate inter modes can be limited in a small mode group (MG) by using the characteristics of the motion compensated residual image. Then the most probable mode (MPM) of the MB is predicted on the basis of the modes of the neighboring macroblocks. The overlapped mode groups and dynamic adjusted thresholds adopted in the proposed method can make the best mode lies within the chosen MG with great possibility which leads to extensively computation reduction with acceptable loss in quality. The experimental results show that the proposed method can save the encoding time up to 64% on average with -0.45dB performance degradation.