In this paper, optimization of a H.264 encoder and video capture driver using TMS320DM642 are presented, and some speciality are considered according to the analysis of the video capture driver structure and the architecture of DM642. The problem of dealing with high definition video, such as video frame of 1024×768 resolution, is finally resolved based on DM642. The testing results demonstrate that encoder has sped up remarkably after optimization, which can meet the real-time encoding requirement for the video resolution of 1024×768.