A real-time implementation of the H.263 video codec

It is known that software-based video telephony can provide a low cost solution and great flexibility of implementation. However, today's video telephony usually has the defect of discontinuous video and audio. This leads to an inadequate video frame rate at only 2 to 10 frames per second (fps). The situation is common for a video codec to run under Pentium 200MHz personal computer (PC) processing a quarter common intermediate format (QCIF) video sequence. However, an ideal frame rate is 30 fps. These are due to the big software loops that form the real-time bottleneck. Therefore, methods were sought to improve the speed performance of the International Telecommunication Union (ITU) H.263 low-bit-rate video codec. Techniques have been developed in this thesis to improve coding speed. These include implementing a new very fast discrete cosine transform (DCT) algorithm, utilizing and adopting the Intel's multimedia extension (MMX) technology to the very fast DCT algorithm, the sum of absolute difference (SAD) algorithm and the frame filtering algorithm, and enabling the optional PB-frames mode of H.263. The results are increases in the execution speed, improvement in image quality and the compression ratio. The combination of these techniques can lead to an increase in frame rate up to 15 fps on a 200MHz Pentium computer