Interactive video distribution systems – User-requested video program system – Video-on-demand
Reexamination Certificate
1997-11-20
2003-04-01
Faile, Andrew (Department: 2611)
Interactive video distribution systems
User-requested video program system
Video-on-demand
C725S087000, C725S045000, C725S097000, C725S098000, C709S217000, C709S219000
Reexamination Certificate
active
06543053
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to information transmission, retrieval, reception, and distribution over a network, and more specifically, to a system and protocol for interactive multimedia services in a broadband network.
BACKGROUND OF THE INVENTION
A Video-on-Demand (“VOD”) system combines a video display system such as a user's TV set or personal computer with information retrieval technology. This technology usually provides a specific electronic video service based on user's requests over a network. Applications of VOD include entertainment services such as movie-on-demand service, news-on-demand service, and remote learning.
In true VOD, a user is allowed to select any program from remote content archives at any time. Those archives can include audio and video materials, and multimedia titles. In addition, the user is allowed to interact at any time with the programs using operations including random access to any point in a program, fast-forward, rewind, pause/resume, slow-motion play, and other VCR-like controls.
A VOD system that does not meet all these requirements is called a near VOD system. Near-VOD is often used in order to conserve or more efficiently use system resources. True VOD service is more desirable in order to compete with existing video rental services.
FIG. 1A
shows a generic VOD system
100
. Multiple users
120
are served by networked servers
102
and
107
over a network
103
. The solid lines represent the data flow for video and other data. The dashed lines represent the communication signal flow for controls and requests. Arrows indicate the flow direction.
The information sources of the system
100
are the networked remote server
102
connected to a backbone network
104
and the local server
107
in an access node
106
. Servers
102
and
107
can include one or multiple servers that have massive storage devices and media controllers for storing a large number of databases including videos, multimedia titles, interactive games and others. Servers
102
and
107
are capable of serving a considerable number of simultaneous user requests to the same or to different programs on demand.
One or more electronic controllers
130
are deployed in the network
103
to control and monitor the operations of the VOD system
100
. A controller may be a computer that controls the networked servers to operate under an operation protocol. The basic functions supported by the controller include request handling, support of user interactions, admission control and quality-of-service guarantees.
Storage media for servers
102
and
107
usually include magnetic disks, optical disks, and magnetic tapes. Such media are usually organized hierarchically to increase cost-effectiveness. For example, the more popular programs are stored on random access media, such as magnetic disks, for fast access and expedited distribution. The less-popular programs are stored in devices with longer access latencies such as a tape drive, and retrieved as necessary to a disk drive for processing.
The backbone network
104
may include high-speed switches and transport protocols which connect remote servers at geographically dispersed locations. One trend is towards a synchronous optical network (“SONET”) backbone with asynchronous transfer mode (“ATM”) switching because of their low error rate, high data transfer rate, capability of bandwidth-on-demand, and seamless services.
An access node
106
serves as a bridge between the backbone network
104
and access network
110
. A plurality of such access nodes are deployed to link multiple access networks to the backbone network. Depending on the system implementation, the access node
106
may be a head-end in CATV networks, a central office in a telephone network, or a base station in mobile systems. The access node
106
may be equipped with satellite dishes to receive analog broadcast TV programs. Examples of access networks include a hybrid fiber coax (“HFC”) system, asymmetric digital subscriber loop (“ADSL”) system, fiber to the curb (“FTTC”) system, wireless cable system, and direct broadcast satellite (“DBS”) system.
A subscriber terminal unit or “set-top box”
120
in
FIG. 1A
forms an interface between the user and the VOD network. It receives, demodulates, and decodes the information. The user can interact with the VOD system by sending out control commands and service requests, typically through a remote control. The set-top box has interfaces to video/audio output devices (e.g., a computer, a TV or a telephone) and can be integrated as a part of the video/audio output device. A user can be connected to servers
102
and
107
with various user interfaces such as on-screen images and cursor-like devices.
Various VOD systems have been proposed and/or developed. Some have been tested in small-scale trials. A number of existing field trials of VOD systems are reviewed by T. S. Perry in “The Trials and Travails of Interactive TV,” IEEE Spectrum, pp. 22-28, April, 1996.
One solution to provide true VOD services uses a dedicated video stream for each customer, i.e., the system resources associated with video delivery, namely, disk head usage and network bandwidth, are not shared. This is also referred to as a non-batching approach. Such systems usually are expensive since each stream requires high-speed video retrieval and transport, and can be inefficient because multiple identical video streams are sent to multiple customers accessing the same video. Existing VOD field trials typically deliver MPEG-1 or MPEG-2 compressed video, requiring 1.5 Mbps and 3 Mbps, respectively. Therefore, in the non-batching approach, the number of users which can be simultaneously served in a true VOD mode is limited by the system resources.
A batching approach can be used to increase the capacity or the number of simultaneous users of a given system. Batching divides users into groups. All users in the same group are served by the same video stream. One may group users according to their video request time.
FIGS. 1B and 1C
show non-batching and batching approaches, respectively. In a non-batching approach as in
FIG. 1B
, each user has a designated video stream generated by a designated video disk head, and transmitted to the user using dedicated network resources. A video disk head is typically multiplexed among multiple video streams. Therefore, the designated disk head may only correspond to a fraction of a physical video disk head. True VOD can be implemented this way for a limited number of users at a high cost.
In a batching approach as illustrated in
FIG. 1C
, the same video stream
140
is multicasted to, and shared by, multiple users
120
accessing the same video. Sharing is implemented both at the disk head and in the network. Thus, usage of the system resource per user is reduced and thereby the system capacity is increased. Many video delivering systems have implemented such batching mechanisms with limited user interactivity.
U.S. Pat. No. 5,357,276 to Banker et al., discloses a staggered VOD. This system broadcasts multiple staggered-in-time copies (streams) of the same video program. Specifically, a copy of the same video program is broadcasted to a group of users in a batch in a fixed batching interval. A user is always being served by one of the streams. User interactions are simulated, where practical, by switching to different streams. However, not all user interactions can be simulated in this fashion. Fast forward, i.e., displaying the video at a rate higher than the normal playback rate, is one example of a user interaction which cannot be simulated since none of the broadcast streams is in a fast forward mode.
Several interactive functions can be simulated with this system including pause, jump forward/jump back operations. However, the interactive effects are limited by the staggering structure, specifically by the staggering interval thereof. For example, if the staggering interval is 5 minutes, a user may jump forward or backwards by intervals of 5 minutes, 10 minutes, 15 minutes
Li Victor O. K.
Liao Wanjiun
Faile Andrew
Fish & Richardson P.C.
University of Hong Kong
Vu Ngoc
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