Design and implementation of real‐time software‐based H.261 video codec

ITU-T H.261 is a video coding standard for videophone and video-conferencing applications on LAN and ISDN, which requires a great amount of computing power for DCT and motion estimation, traditionally provided by hardware. Since motion estimation is a major problem in developing real-time video codec, in this paper we propose a simple and fast motion estimation algorithm to reduce searching time. Mainly, a real-time software-based H.261 video codec is investigated and implemented, in which several fast methods such as programming technique and Intel MMX™ instruction are used to improve computing speed. The experimental results have demonstrated that our H.261 codec can compress video in CIF format over 30 fps and in QCIF at 105 fps, and can achieve a very high decoding rate. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 73–83, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10013