中文摘要：

H.264是最新的国际视频编码标准，它能够提供更高的编码效率，但其编码实现也非常复杂，三叉树结构的多编码模式和多帧参考技术是复杂度增加的两个重要因素．针对这两个因素提出一种用于帧间编码的快速模式判决算法FIMDA，它利用编码过程中获得的模式、码率开销等编码信息来减少那些对编码性能影响不大的参考帧和模式的搜索过程，从而降低编码复杂度．实验结果表明，对常用的5帧参考，与全搜索相比，FIMDA可将编码复杂度降低平均85％以上，而PSNR下降仅在0．07dB左右．

英文摘要：

The new video coding standard, H.264 gives a better encoding performance than previous video standards at the cost of expensive computation since it allows motion estimation performing on tri-ree structured macroblock partitioning and multiple reference frames. In this paper, a fast algorithm FIMDA is proposed to accelerate mode decision of inter macroblock. FIMDA makes full use of valuable cues provided by the previous searching reference frames, such as mode, rate distortion cost etc., to eliminate unnecessary modes and reference frames in the following searching. FIMDA can effectively reduce encoding complexity and the quality degradation compared with full search can be ignored. Simulation results show that average complexity reduction exceeds 85 % and average quality degradation is only about 0.07dB.