1. Field of the Invention
The present invention relates to signal processing, and, in particular, to computer-implemented processes and apparatuses for encoding and decoding video signals.
2. Description of the Related Art
This invention relates to audio/video conferencing between two or more conference nodes, where each conference node is a personal computer (PC) system communicating with the other conference nodes over a selected transmission medium. Because transmission media typically have finite bandwidths, in order to provide audio/video conferencing of satisfactory quality, each PC system preferably compresses in real time the audio and video signals corresponding to the local participant and transmits the resulting compressed signals to the PC systems of the remote participants. Each PC system also preferably receives and decompresses compressed signals from the PC systems of the remote participants to play the decompressed audio and video signals locally.
Possible transmission media include Integrated Services Digital Network (ISDN) and Public Switched Telephone Network (PSTN) telephone connections. Although ISDN connections provide a higher bandwidth than PSTN connections, ISDN connections are less readily available and more expensive than PSTN connections.
Unfortunately, conventional methods for compressing video signals, such as the H.261 (P.times.64) and ISO/IEC 11172-2 (MPEG) standards, require bandwidths greater than that provided by PSTN connections. As a result, these conventional video compression methods cannot be used to support audio/video conferencing over PSTN connections.
What is needed is a video compression process that can be implemented in real time on PC systems to generate compressed video signals that can be transmitted under the bandwidth constraints of PSTN connections and then decompressed in real time by the PC systems to provide satisfactory audio/video conferencing.
It is accordingly an object of this invention to overcome the disadvantages and drawbacks of the known art and to provide computer-implemented processes, apparatuses, and systems for compressing and decompressing video signals to provide satisfactory audio/video conferencing between PC systems communicating via PSTN connections.
Further objects and advantages of this invention will become apparent from the detailed description of a preferred embodiment which follows.