Interactive video distribution systems – User-requested video program system – Video-on-demand
Reexamination Certificate
1997-12-03
2001-06-26
Grant, Chris (Department: 2611)
Interactive video distribution systems
User-requested video program system
Video-on-demand
C725S095000
Reexamination Certificate
active
06253375
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for delivering interactive information services, such as video, audio, library, interactive games, and the like to one or more subscribers. More particularly, the invention relates to a system for establishing a multi-channel communicative connection between a subscriber's set top terminal and a service provider and then managing the communications necessary to deliver interactive information services to the subscriber(s).
2. Description of the Background Art
Recent advances in digital signal processing techniques and, in particular, advancements in digital compression techniques, have led to a plethora of proposals for providing new digital services to a subscriber's home via existing telephone and coaxial cable networks. For example, it has been proposed to provide hundreds of cable television channels to subscribers by compressing digital video, transmitting the compressed digital video over conventional coaxial cable television cables, and then decompressing the video at the subscriber's set top terminal. Another proposed application of this technology is a movie-on-demand video system in which a subscriber communicates directly with a video service provider via telephone lines to request a particular video program from a video library and the requested video program is routed to the subscriber's home via telephone lines or via the coaxial television cables for immediate viewing.
However, these present movie-on-demand video systems are not truly interactive systems wherein a subscriber can selectively access a large audio, video or data library and control the presentation of the selected information on a real-time basis, as when a video program is played using a video cassette recorder (VCR). Most of the presently available systems have a simple control interface that permits subscribers to merely order information without any further control of the presentation of the information. Other, more sophisticated systems, have a control interface that contains more complex commands such as start, stop, pause, fast-forward and rewind to permit rudimentary control of the presentation of the information. However, these systems use conventional signaling and information routing networks that are relatively slow to react to the commands, e.g., the latency between the instant an interactive function is requested and when that function takes effect is extremely long. Furthermore, the set top terminals used by these systems contain complex and costly electronics to facilitate processing of the complex commands. Additionally, these systems use a conventional cable television network architecture, where a central data server transmits data to a plurality of head end subsystems which in turn propagate various subsets of the data to an individual or a multiplicity of set top terminals. The servers in such systems perform much of the control functions and, as such, the latency arising from sending control commands through the head end to the server is substantial.
Therefore, there is a need in the art for a cost effective, interactive information distribution system that provides real-time interaction (with relatively short latency) between the subscriber and the service provider at any time during the presentation of requested information.
SUMMARY OF THE INVENTION
The disadvantages heretofore associated with the prior art are overcome by the present invention. The present invention is a system for interactively distributing information services. The system contains an information server, a video session manager, a bi-directional cable transport network, and subscriber equipment (e.g., a set top terminal, an input device, and a display device).
The system uses three independent communications channels to facilitate distribution and interactive control of the information distribution process. Specifically, an information channel propagates program information and a command channel propagates control information from the service provide to the subscriber equipment, and a back channel propagates command and control information from the subscriber equipment to the service provider. The information channel may also be utilized to transport control information to the subscriber equipment. Consequently, the service provider sends through the command and/or information channels selection menus to the subscriber equipment such that a subscriber can select a particular program. The program selection request is propagated through the back channel to the service provider. The service provider then sends the program through the information channel for display on the subscriber equipment. The subscriber can manipulate (e.g., fast-forward, pause, rewind, perform context based branching and the like) the presentation via commands sent from the subscriber equipment to the service provider.
More specifically, the server provides a video session manager with a plurality of program streams that generally comply with the MPEG-2 transport protocol. The program streams are generated using a common, high accuracy clock signal (synchronization clock) such that the data in the plurality of streams is synchronous. The video session manager interacts with the server to request particular information program streams in response to subscriber demands. Once a subscriber requests use of the service provider navigator to facilitate selection of viewable programming, the video session manager opens a “session” for a given subscriber and sends requested program streams through the cable transport network to the subscriber's set top terminal via the information channel.
To provide real-time interactive control of the information presentation to the subscriber, the subscriber, through their input device (remote control), may order, start, stop, fast-forward, rewind, pause and branch from or to any information stream that is resident on the server subsystem. As such, the system of the present invention provides the customer with all of the interactive commands that are generally available on a conventional video cassette recorder. Additionally, the user can open multiple sessions such that multiple information streams may be started and stopped and interactively controlled at any time. Such interaction is facilitated by the system because the system is synchronized from end-to-end. That is, the server provides the synchronization clock to which all subsystems of the invention are synchronized. The system synchronization extends to the cable transport network and the subscriber's set top terminal.
In particular, the synchronization clock is used by the video session manager to modulate all of the data streams such that each transmitted stream is synchronized with other streams. Furthermore, the set top terminals recover timing from the synchronized data bits within the received stream; thus, the set top terminals are also synchronized to the synchronization clock. As such, when a subscriber changes from one program to another, there is no resynchronization delay before the different program is available for display. Consequently, the latency between when a command is entered and when it is implemented is relatively short. Thus, a subscriber can have multiple sessions open and switch from one to another without substantial delay after each session change.
To reduce the cost associated with transmission and presentation of each program stream, the system of the present invention avoids encrypting all of the information that is sent to the set top terminals. System security, without encryption, is provided by randomly assigned and altered program identification numbers (PID). Specifically, when a session is started by a subscriber request, the set top terminal is assigned a unique session number. Additionally, the set top terminal has an assigned identification number (TID). This TID is compared to a TID stored in the system such that the user identification is confirmed. Periodically, the TID numbers are a
Chin Danny
Goode Christopher
Gordon Donald
Knight Stanley
Star Jack Van der
DIVA Systems Corporation
Grant Chris
Thomason Moser & Patterson LLP
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