After the optimization of H.264-based FGSS,we propose an approach named modified FGSS(MFGSS).The H.264-encoded video has the characteristics of fine-granular scalability at each resolution such as CIF or QCIF.According to the relationship between the motion vectors for low spatial resolution and that for high spatial resolution,the bits to code motion vectors can be reduced because when the motion vectors with high resolution are lost,those with low resolution can be used to compensate them.Experiments show our approach has better performances on coding efficiency in comparison with MPEG-4 FGSS.Next,we describe the approaches to realize real-time coding on PC platform.After the simplified RDO optimization and multi-media instruction-set optimization,two schemes are proposed to enhance the structure of coder to realize real-time coding.The experiments show that in the case of the first scheme,the coding speed increases 72.76% than before and the bit rate also increases 23.3% and the coding PSNR reduces only 0.23 dB.However,in the case of the second scheme,the coding speed increases 10.95% and the bit rate also increases 2.7% and the PSNR reduces few.So the second scheme is preferable.