Advanced Video Technologies’ Patent:
U.S. Patent No. 5,781,788, “Full Duplex Single Chip Video Codec,” has a priority date of May 8, 1995 and was published July 14, 1998. The patent covers a single-chip video compression/decompression (video codec) chip is connected to receive a video input from a NTSC-compatible or PAL-compatible camera and a transmit channel. Video information from the camera or other video input source is compressed by the video codec and transmitted out in compressed form on a transmit channel. Concurrently, compressed video information is input to the video codec from a receive channel, decompressed and output to the monitor or other video output device, e.g., a television set. Only a separate single module of dynamic random access memory (DRAM) is needed to provide storage for incoming and outgoing video data, compressed bit streams and reconstructed pictures for both compression and decompression procedures. The compression of video information is by spatial decorrelation of the intraframe information, and temporal decorrelation of the interframe information. The communication channel bit rate is further reduced by quantization and variable length coding. Intraframe coding uses the redundancy of information within a single frame. The processing is done on blocks of eight-by-eight pixels. Both the luminance and chrominance pixel blocks are transform coded by a discrete cosine transform that changes the pixels from spatial domain to frequency domain. View a .pdf of the Patent.
Note: At Google Patents, the title of the Patent appears as “…Single Clip Video…”. This was an error when the patent was initially issued that has since been corrected, but Google shows the patent as it was originally published.