Fast Mode Decision for H.264 Video Encoder Based on MB Motion Characteristic

Seven variable block sizes are adopted for inter-frame MB (macroblock) coding in H.264. This new feature achieves significant coding gain. However, the computation complexity of the mode decision is extremely high when RD (rate distortion) algorithm is used. In this paper, we propose a fast mode decision algorithm with fast coding block size selection based on MB motion characteristic for inter frames. In this algorithm, the residual_MB is first gotten through motion estimation for the MB. Then, the motion characteristic of the MB is extracted through careful analysis of the texture in the residual_MB. At last, the optimization mode for the MB is decided according to the motion characteristic. Experimental results show that the mode decision can save significantly computational complexity at cost of a little degradation of RD performance.