Abstract: An efficient mode decision algorithm for H.264 intra-coding is proposed. For luma component, the algorithm sets the condition according to the features of the macroblock smoothness. One of the four intra_16×16 prediction modes is chosen when it meets the condition, otherwise it will choose the intra_4×4 prediction modes, and at this time, some of the intra_4x4 prediction modes that are not usually used are eliminated. For chroma component, the numbers of prediction modes are reduced by an impersonal fact that human don’t be sensitive to chroma component, in order to decrease the encoding time. Experimental results show that the proposed algorithm can save more than 30% of encoding time, while keeping the similar visual quality.

Key words: H.264/AVC, intra prediction, mode selection, fast algorithm

摘要： 针对H.264帧内模式决策，提出一种快速算法。对于亮度分量，该算法根据待编码宏块平滑度的特点来设定条件，满足平滑条件则直接判断出采用intra_16×16四种预测模式中的哪种模式，对于不符合条件的采用intra_4×4预测模式，此时可以剔除部分不常用的预测模式；对于色度分量，可以根据人眼对色度不敏感这个客观事实来减少候选模式的数量，从而进一步降低编码时间。实验结果表明，该算法可以节省30%以上的编码时间，同时保持相似的视频质量。

关键词: H.264/AVC, 帧内预测, 模式选择, 快速算法