A directional field based fast intra mode decision algorithm for H.264 video coding

The H.264 video coding standard can achieve considerably higher coding efficiency than previous standards. In order to achieve this, a robust rate-distortion optimization (RDO) technique is employed to select the best coding mode for each macroblock. As a result. the encoder complexity is increased considerably. This paper presents a directional field based fast intra mode decision algorithm to improve the encoder´s efficiency. Prior to intra prediction, the directional field is calculated for all the block size to decide the dominant edge direction in the blocks. Based on the edge direction information, only a small number of prediction modes are chosen for RDO calculation. Experimental results show that the fast intra mode decision algorithm increases the speed of intra coding significantly with negligible loss of PSNR