Abstract: The technical field of the invention generally concerns systems for receiving and transmitting compressed video and audio data. In particular, a subscriber system (10) includes a communication subsystem (12) to receive compressed data from and transmit compressed data to a ISDN primary access line (14) utilizing the "bandwidth on demand" feature of that communication channel. The communication subsystem (12) separates received compressed data into compressed video data and compressed audio data. Within the subscriber system (10), the compressed video data is transmitted to a programmable video data format conversion subsystem (28) for decompression and production of a visible image on a CRT (82). Similarly, compressed audio data is transmitted to a programmable audio data format conversion subsystem (192) for decompression and production of an audible sound on a speaker (262). Compressed data of visible images and audible sounds may also be obtained with and transmitted from the subscriber system (10).

Abstract: If motion occurs in an area viewed by a lens (14) of a video camera (12), a video security monitoring system (10) establishes a communication link with a video monitoring facility and begins transmitting compressed video images of the area. The system (10) is fabricated from CMOS integrated circuits, and operates at a reduced clock frequency while motion is not detected. Reducing the clock frequency lowers the required power thus permitting operation of the system (10) on energy supplied by an ISDN basic access communication channel. If motion occurs, a digital video image compression subsystem (16) begins producing low quality compressed video data for transmission to the monitoring facility. If motion occurs in the central region of the area viewed by the lens (14), then the subsystem (16) produces a single high quality compressed video image. Commands transmitted from the monitoring facility to the video security monitoring system (10) may control its entire operation.