Interactive system for the ditribution of numeric audiovisual signals

摘要

The system uses two channels for bi-directional communication between server and users. The interactive system for distribution of digital audio-visual signals uses a descending channel and an ascending channel. The descending channel transmits signals in the form of digital packets from a server to users. A clock controls the multiplexing of messages from the users to the server. These messages are defined by markers whose position is periodically indicated by a pointer number incorporated in one of the descending channel packets. This pointer indicates the time remaining between the instant when the pointer appears and the moment when the marker appears. The system includes a system for generating a packet containing a pointer at an instant which is shifted w.r.t. the position where it is generated, and for reducing the value of the pointer by a quantity equal to a specific elapsed time.