Intra/Internet Videophone Based on MPEG-4

We describe a new videophone system for use both in intranet and internet environment. Video coding method for the videophone is based on the emerging MPEG-4 standard. One of the new functionalities is coding of video objects rather than video frames. Due to the object-based coding, the resulting videophone provides better quality and error robustness through intra/interne compared with the existing H.263-based videophones which employ frame-based video coding. The system is implemented in pure software on general-purpose multimedia personal computers and makes video telephony possible only with minimal hardware additions such as a set of video camera and video acquisition board. For the rest of the system, we used G.723.1 for speech, MPEG-4, synchronization layer (SL) for audio-visual synchronization, and RTP and RTCP over UDP for stream packet delivery. Call setup is performed using TCP. In a LAN environment, it currently provides superb audio-visual quality at rate as high as 15 frames/sec, which is still under continuing improvement as the system optimization progresses.