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Claims  |
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What is claimed is:
1. An interactive multiuser system for composing at least two multimedia
signals from a set of source signals, the system comprising:
a plurality of composing unit means for communicating with a plurality of
users, each of said plurality of composing unit means composing a
plurality of user requested multimedia signals from said set of source
signals in response to a user request from any one of the plurality users,
each of said sets of source signals comprising a visual signal, an audio
signal, and a third set of signals, the third set of signals representing
at least one additional video or audio signal;
means for assigning:
(i) a first composing unit means of the plurality of composing unit means
in response to a first user requested multimedia signal of the plurality
of user requested multimedia signals from a first user of the plurality of
users, and
(ii) a second composing unit means of the plurality of composing unit means
in response to a second user requested multimedia signal of the plurality
of user requested multimedia signals from a second user of the plurality
of users,;
means for configuring:
(i) the first composing unit means to compose said first user requested
multimedia signal, and
(ii) the second composing unit means to compose said second user requested
multimedia signal;
means for applying:
(i) a first source signal of the set of source signals to said first
composing unit means in response to said first user requested multimedia
signal, and
(ii) a second source signal of the set of source signals to said second
composing unit means in response to said second user requested multimedia
signal; and
means for transmitting said first and second user requested multimedia
signals to the first user and the second user, respectively.
2. The system of claim 1, wherein each of said sets of source signals
include video signals and each of said plurality of composing unit means
comprises at least one means for modifying a video signal in accordance
with at least one video parameter, said means for configuring comprising
means for applying said at least one video parameter to the at least one
means for modifying a video signal, each of said plurality of composing
unit means further comprising means for combining outputs of said at least
one means for modifying a video signal into a composite video signal
representing an overall image.
3. The system of claim 2, wherein said at least one video parameter affects
the size in said overall image of an image resulting from said video
signal.
4. The system of claim 2, wherein said at least one video parameter affects
the position in said overall image of an image resulting from said video
signal.
5. The system of claim 2, wherein at least one of said video signals is a
still frame video signal.
6. The system of claim 2, wherein at least one of said video signals is a
full-motion video signal.
7. The system of claim 1, wherein said set of source signals include audio
signals and each of said plurality of composing unit means comprises:
at least one audio modifying means for modifying the audio signals in
accordance with at least one audio parameter, said means for configuring
comprising means for applying said at least one audio parameter to the at
least one audio modifying means, said composing unit means further
comprising means for combining outputs of said audio modifying means into
a composite audio signal.
8. The system of claim 1, wherein said set of source signals include video
signals and each of said plurality of composing unit means comprises:
at least one video modifying means for modifying the video signals in
accordance with at least one video parameter, said means for configuring
comprising means for applying said at least one video parameter to the at
least one video modifying means, each of said plurality of composing unit
means further comprising means for combining outputs of said video
modifying means into a composite video signal.
9. The system of claim 1, wherein said set of source signals is compressed
and each of said plurality of composing unit means further comprises:
at least one means for decompressing at least one of the first and second
source signals.
10. The system of claim 1, wherein said at least two multimedia signals are
compressed by the plurality of composing unit means and each of the
plurality of composing unit means, further comprises:
means for compressing one of the at least two multimedia signals.
11. An interactive multiuser system for composing and transmitting a first
video signal and a second video signal, the system comprising:
(a) means for receiving a first request from a first user for the first
video signal and a second request from a second user for the second video
signal;
(b) a plurality of assignable means for composing, one of the plurality of
assignable means composing the first video signal and another one of the
plurality of assignable means composing the second video signal in
response to the first and second requests, respectively;
(c) means for determining a first assignable means as the one of the
plurality of assignable means and a second assignable means as the another
one of the plurality of assignable means;
(d) means for independently configuring the first and second assignable
means;
(e) means for receiving a first video signal set of at least two video
signals at the first assignable means and a second video signal set of at
least two video signals at the second assignable means;
(f) means for combining the first video signal set in the first assignable
means into the first video signal and the second video signal set
assignable means into the second video signal; and
(g) means for transmitting the first video signal to the first user and the
second video signal to the second user.
12. The apparatus of claim 11, wherein the first and second video signal
sets are in a compressed format and the first and second video signals are
in the compressed format.
13. The apparatus of claim 11, wherein at least one video signal in the
first and second video signal sets is a still frame video signal.
14. The apparatus of claim 11, wherein each of the assignable means for
composing, further comprises;
means for modifying a signal in accordance with a video parameter.
15. A method for composing and transmitting a first video signal to a first
user and a second video signal to a second user of an interactive
multiuser system, the method comprising:
(a) receiving a first request for the first video signal from the first
user and a second request for the second video signal from the second
user;
(b) assigning a first assignable means from a plurality of assignable means
for composing and a second assignable means from the plurality of
assignable means for composing, the first assignable means composing the
first video signal and the second assignable means for composing the
second video signal in response to the first and second requests from the
first and second users, respectively;
(c) independently configuring the first and second assignable means;
(d) receiving a first video signal set of at least two video signals and a
second video signal set of at least two video signals;
(e) combining the first video signal set in the first assignable means into
the first video signal and the second video signal set in the second
assignable means into the second video signal; and
(f) transmitting with a transmitting means the first video signal to the
first user and the second video signal to the second user.
16. The method of claim 15, wherein the first and second video signal sets
are in a compressed format and the first and second video signals are in
the compressed format.
17. The method of claim 15 wherein at least one video signal in the first
and second video signal sets is a still frame video signal.
18. The method of claim 15, wherein each of the plurality of assignable
means for composing, further comprises:
means for modifying a signal in accordance with a video parameter. |
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Claims |
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Description |
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TECHNICAL FIELD
This invention relates to interactive television (ITV) systems, and more
particularly to systems for generating multimedia signals from various
video and audio sources for transmission to users in connection with
furnishing interactive television services.
BACKGROUND OF THE INVENTION
Cable television systems have made possible the transmission of many
channels of television programs to the homes of subscribers. Instead of
being limited to the number of VHF and UHF channels that can be
transmitted and received in a given area, the number of channels in cable
systems is limited only by the transmission characteristics of the cable
itself and the ability to compress the information in television programs
into narrower-bandwidth channels. The advent of fiber-optic transmission
systems for use in cable television networks has also vastly increased the
number of channels available.
Such increase in channels has also given rise to proposals for interactive
television systems wherein a subscriber can transmit information or
requests back into the system, which information or requests may
subsequently affect programs or information directed to such subscriber.
There are a wide variety of applications for interactive television
systems, such as video games, video catalog shopping, teaching systems,
movies on demand and audio programs. Each application can be tailored for
an individual subscriber, for example, a subscriber may be able to select
the language of the soundtrack in a movie. However, such systems typically
require the ability (i) to control specific programs or information sent
to each subscriber and (ii) to receive input messages or requests from the
subscriber.
A headend-to-subscriber channel does not need the full bandwidth of the
usual television cable channel if compression can be used. For example, if
a television signal is digitized and compressed in accordance with the
MPEG standard, it is possible to transmit sixteen television programs
digitally over a single conventional 6 Mhz cable channel. Other program
information, such as high-fidelity audio, still video pictures or text can
also be sent in compressed form. By using a large number of conventional
channels for ITV purposes, such as is now possible with optical fiber
distribution systems, together with compression, it is conceivable that
hundreds of virtual channels could be made available.
Systems are also becoming available for transmitting compressed and encoded
television signals over telephone circuits. In one such system, 1.5
megabits/second of data, sufficient for one compressed and encoded
television channel, can be transmitted from a telephone central office
over a twisted-pair loop to a subscriber's premises, and 16 kilobits of
data can be transmitted back to the central office, together with regular
telephone service. Such a loop is known as an asymmetric digital
subscriber loop.
With the wide deployment of digital communication systems, standardized
digital transmission systems have become available in which data is
transmitted in packet form over networks. One such network is an
asynchronous transmission mode (ATM) network in which packets of varying
length can be sent. Such packet networks can be used for carrying
digitized television signals.
Clearly the means now exist by which tailored television signals can be
delivered to individual users, such as by cable television systems,
telephone networks, packet networks and satellites. Also, a large number
of sources are available from which programs and interactive television
applications can be provided. However, problems arise in the efficient
generation of television signals composed of signals from multiple video
and/or audio sources for use in providing interactive television services.
SUMMARY OF THE INVENTION
The system of the invention composes multimedia signals from various source
signals, such as still-frame video signals, full motion video signals and
audio signals. The system includes a plurality of composing units each of
which is capable of composing a multimedia signal from selected source
signals. One of such composing units is assigned for each multimedia
signal to be composed. Each composing unit accepts parameters specifying
various properties for each element of the multimedia signal, such as
size, position and precedence for each video element and gain for each
audio element.
Each composing unit can include decompressors for decompressing source
signals furnished in compressed form and a compressor to compress the
multimedia signal to be transmitted to the user.
The source signals can be received from a packet network and the resulting
multimedia signals transmitted to the respective users via the same packet
network.
These and other aspects of the invention will become apparent from the
drawings and the detailed description.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an overall block diagram of an integrated television services
system using the multimedia frame of the invention.
FIG. 2 is a block diagram showing the overall flow of control and data
packets in the system of FIG. 1.
FIG. 3 is an overall block diagram of the multimedia frame of the
invention.
FIG. 4 is a block diagram of a composing unit used in the multimedia frame
of the invention.
FIG. 5 is a diagram of a multimedia menu screen that can be composed with
the system of the invention.
DETAILED DESCRIPTION
FIG. 1 is an overall block diagram of a basic integrated television
services system in which the multimedia frame of the invention can be
used. The elements of the system communicate through packet network 10,
which includes one or more packet switches 120. Such elements include
control processor 100, application processor 102, application resources
such as data cache 104, multimedia frame 106, broadcast source 108 and
game frame 110 and one or more distribution interfaces 112 and 114, all of
which are connected by links 140 to packet switch 120. Program library 105
is a high-capacity, long-term source of stored program material for data
cache 104. Broadcast source 108 furnishes digitized and compressed program
material from television broadcasts, cable systems, satellites or other
means. In an exemplary embodiment, packet network 10 is an asynchronous
transfer mode (ATM) network, links 140 are SONET OC-3 links, and packet
switch 120 is an ATM switch such as the AT&T GCNS- 2000 ATM switch.
In general, control processor 100 serves to interact with users selecting
any of the various interactive services that may be provided by the system
of the invention, and application processor 102 controls the services
themselves. Control processor 101 also assigns the resources necessary to
provide a service to a user. Application processor 102 and application
resources such as data cache 104, multimedia frame 106, broadcast source
108 and game frame 110 can be duplicated as necessary to meet the capacity
requirements of the system, but control processor 100 is preferably not
duplicated because such processor maintains assignment records for the
various resources in the system and making such records available to more
than one processor, while achievable, is cumbersome. However, these task
assignments to control processor 101 and application processor 102 are not
inviolate; for example, in some cases it may be desirable to combine the
functions of both processors in a single processor, or to use control
processor 100 for certain applications.
Data cache 104 is a large random access memory for storing audio and video
material in compressed and packetized form, such as the program server
described in our copending patent application Ser. No. 07/997,985 filed
Dec. 29, 1992 and having the same assignee as this invention. Data cache
104 can have one or more links 140 into packet network 10 depending on
capacity requirements. Program library 105 can be a large-capacity system
of any convenient type for storing program material, such as movies,
musical selections, video clips, still frames and audio clips, in
digitized and compressed form on devices such as magnetic tapes or optical
discs and the like. Link 142 between program library 105 and data cache
104 can also be made via a separate ATM packet network, such as a SONET
OC-3 network, or via packet network 10, depending on capacity and
geographic limitations. Program library 105 is typically equipped to
transmit a large quantity of data, such as digitized and compressed video
and audio signals for complete movies, to data cache 104 in a relatively
short time, as described in more detail in our above mentioned
application.
It is contemplated that the various elements shown in FIG. 1 can be
situated at different geographic locations. For example, packet switch
120, control processor 100, application processor 102, multimedia frame
106, broadcast source 108 and game frame 110 can be at a first location,
data cache 104 can be at a second location and program library 105 can be
at a third location. Other packet switches 120 and distribution interfaces
such as 112 and 114 can be at still other locations. Connections between
locations can be SONET OC-3 links. It will be clear to those skilled in
the art that numerous possible combinations of and locations for such
elements are possible without departing from the spirit and scope of the
invention.
Many interactive television services may be offered that incorporate
broadcast television programs. Therefore, one of the application resources
provided in the system of the invention can be a source of such programs,
such as broadcast source 108, which receives one or more broadcast
television signals from regular broadcasts, satellite transmissions, cable
television systems or any other appropriate means, all symbolized by
antenna 109. Broadcast TV source 108 includes facilities for digitizing
and compressing each received television signal and transmitting such
signals in packetized form via packet network 10.
Multimedia frame 106 contains a number of units for composing compressed
and packetized multimedia signals from a number of different sources, such
as data cache 104, broadcast source 108 and internal text generators. Each
such source typically provides a signal in digitized and compressed form.
When a multimedia signal composed from multiple video and/or audio sources
is to be transmitted to a user, control processor 100 assigns one of such
composing units and the necessary virtual channels to create the
multimedia signal. Note that the input signals to multimedia frame 106, as
well as output signals to users, are all transmitted in packetized form
through packet network 10. Multimedia frame 106 will be described in more
detail below.
Game frame 110 contains a number of units for generating compressed and
packetized audio and video signals for use in computer games that may be
offered as part of an interactive television service. One such unit is
assigned to each user of a computer game.
Application processor 102 and applications resources 104, 106, 108 and 110
can be combined in various ways to form what can be thought of as
application servers for providing different ITV services. For example, a
video-on-demand/enhanced-pay-per-view server could include application
processor 102 and data cache 104; a multimedia ITV server could include
application processor 102, data cache 104, multimedia frame 106 and
broadcast source 108; and a game server could include application
processor 102, multimedia frame 106 and game frame 110. Each application
processor 102 can be a part of more than one such server, up to the limit
of its capacity.
Interfaces such as cable distribution interface 112 are typically located
at cable television system headends and connected to signal converters 130
situated on cable customers' premises by distribution cable 116, whereby
the signal converter 130 for each cable customer receives the same overall
"downstream" signals broadcast to all cable customers served by the same
cable distribution interface 112. However, signal converters 130 can be
enabled by control packets transmitted over cable 116 to receive only
certain specified "virtual" channels from cable 116.
Interfaces such as telephone distribution interface 114 are typically
located at telephone central offices and connected to signal converters
150 situated on telephone subscribers' premises by subscriber loops 118,
whereby each telephone subscriber receives a different downstream signal.
Signal converters 130 and 150 convert the downstream signals into
conventional television signals for display on television receivers 134.
Users can send "upstream" signals to control processor 100 and
applications processors 102 from input means such as remote control 132
that transmit control messages to signal converters 130 or 150, as the
case may be. Other devices, such as processors, printers, video cameras,
telephones and other input and output devices can be connected to signal
converters 130 and 150 as required for the provision of ITV services.
The various data and control packets transmitted through the packet network
each contain a header and a body. The header defines a "virtual channel"
in which the packet is deemed to be transmitted. In data packets, the body
contains data, such as part of a digitized and compressed audio or video
signal. In control packets, the body contains information such as the
address of the unit for which the packet is intended and an action to be
performed. In the exemplary embodiment, each packet contains five bytes in
the header and 48 bytes in the body. The header can include information
such as polling addresses and virtual channel identifies. Control packets
are typically sent in one or more specifically assigned virtual channels,
for example, channel "0."
For each link 140 connected to packet switch 120, packet switch control 121
stores information specifying how to route packets arriving over such
link. Such information is based on header contents; for example, certain
virtual channels and/or certain polling addresses can be identified for
transmission over a link. A packet arriving at packet switch 120 over any
link is then routed to one or more links 140 depending on its header
contents. Packet switch control 121 can itself receive packets from packet
network 10, and, in the system of the invention, control processor 100
sends control packets as needed to packet switch control 121 containing
such identifying information for each link 140.
In the exemplary embodiment, a television signal is made up of three
separate data signals, one video and two audio (for stereophonic sound).
Each signal is separately digitized and compressed and sent through packet
network 120 as a packet stream in a separate virtual channel. Accordingly,
three virtual channels are used for transmission of a single television
signal. However, other embodiments are possible in which multiple audio
channels are encoded and compressed together, such as the Dolby (r) AC-2
system.
FIG. 2 shows typical flows of data and control packets through packet
network 10 and in other parts of the system. During the furnishing of ITV
services, data packets containing audio and/or video information flow from
application resources such as data cache 104, multimedia frame 106 and
game frame 110 to signal converters 130 and 150. Such data packets can
also flow between application resources, such as from data cache 104 to
multimedia frame 106 and game frame 110 and from broadcast source 108 to
multimedia frame 106. During interactions with users, control packets flow
between signal converters 130 and 150 and control processor 100 and/or
between signal converters 130 and 150 and application processor 102.
Control processor 100 interacts with application processor 102 and with
packet switch control 121 by means of control packets, and application
processor 102 interacts with application resources 104, 105, 106, 108 and
110 by means of control packets. Data packets from program library 105 to
data cache 104 can be sent via a direct link or via a packet network; even
via packet network 10, if convenient. The link between application
processor 102 and program library 105 carries only control packets and can
be of lower capacity than the links 140, for example, such link can be
part of an Ethernet (r) network. However, such link can also be a
low-bandwidth virtual channel in packet network 10, if desired.
The flexibility of packet network 10 makes possible flows of data and
control packets between any pair of terminals and from one terminal to
groups of terminals. Possibly useful paths for control packets that are
not shown are between signal converters 130 and 150 on the one hand to
multimedia frame 106 and game frame 110 on the other. These paths may be
desirable for use in time-dependent interactive applications using
multimedia frame 106 and game frame 110 in which an extremely fast
response to an action by a user is desired. As will be described,
multimedia frame 106 contains processors that can generate and respond to
such control packets, and game frame 110 typically will also contain such
processors.
In general, control processor 100 interacts with users to control requested
services and to assign the various resources needed to furnish the
services, including the necessary virtual channels in packet network 10
and the various other links in the system. During the delivery of a
service by application resources 104, 106 and 110, under control of
application processor 102, control processor 100 maintains supervision by
responding to certain control packets from signal converters 130 and 150;
application processor 102 responds to control packets from signal
converters 130 and 150 specifically relating to an ITV service being
delivered. However, as described above, application resources may be
equipped to respond directly to control packets from signal converters 130
and 150.
FIG. 3 is an overall block diagram of multimedia frame 106, which includes
a control and demultiplexer (DEMUX) unit 310, a number of composing units
314 and a multiplexer unit 316. Control and demultiplexer 310 routes
packets from packet network 10 for the various components to be included
in multimedia signals via links 312 to the various composing units 314.
Multiplexer 316 accepts packets for the various multimedia signals via
links 318 from composing units 314 and transmits such packets over packet
network 10.
FIG. 4 is an overall block diagram of composing unit 314. Data dispatcher
410 receives packets from control and demultiplexer 310 via link 312 and
routes such packets via bus 412 to various elements such as text generator
414, cursor generator 416, still-frame video decompressors 418,
full-motion video decompressors 420, audio decompressors 422 and control
424. In general, text generator 414, cursor generator 416 and control 424
receive control packets and still-frame video decompressors 418,
full-motion video decompressors 420 and audio decompressors 422 receive
data packets.
The output of each video decompressor 418 and 420 is connected to the input
of a corresponding video scaler and positioner 430 and respectively, the
outputs of which are connected to video combiner 440. The output of each
audio decompressor 422 is connected to the input of a corresponding audio
scaler 434, the outputs of which are connected to audio mixer 442. Video
combiner 440 composes full-motion video frames in digital form from the
various outputs from scalers and positioners 430 and 432 and video
compressor 444 compresses such frames into data packets for transmission
via multiplexer 450, link 318 and multiplexer 316 (FIG. 3) to packet
network 10. Audio mixer 442 combines audio signals from audio scalers 434
and audio compressor 446 compresses such frames into data packets for
transmission, again via multiplexer 450, link 318 and multiplexer 316 to
packet network 10. Multiplexers 450 and 316 can be combined, if
convenient.
Text generator 414 generates text for display on a user's television screen
in response to control packets received from data dispatcher 410. Text
generator 414 can include facilities for producing different type styles
and other displays such as icons and graphic symbols, and can be arranged
to place text and other display material at any location on the screen, as
is well known in the art. Control packets for text generator 414 typically
originate in control processor 100 or application processor 102; however,
for complex text messages that are used often, it may be desirable to
store such packets in data cache 104.
Cursor generator 416 generates a cursor for display on a user's television
screen when required by a particular ITV service. The cursor symbol to be
used and its position on the screen are specified by control packets
received via data dispatcher 410. The position of a cursor is typically
determined by interaction with a user operating an input device such as a
mouse, a trackball or the like connected to signal converter 130 or 150.
The cursor position can be associated with locations of letters or symbols
in text, or with the position of other elements on the screen, as desired.
As mentioned above, control packets from a user during an application are
typically routed to application processor 102. However, because of the
highly time- dependent nature of cursor movement, this is an example of a
situation in which it may be desirable for control packets from a user to
bypass application processor 102 and be routed directly from packet
network 10 to multimedia frame 106. Such packets then proceed through
control and demultiplexer 310 to data dispatcher 410 and cursor generator
416 in the composing unit 314 assigned to the user.
An alternative location for text generator 414 and/or cursor generator 416
is in signal converter 130 or 150 at the user's location. In such a
configuration, control packets specifying text can be transmitted to the
signal converter and control packets specifying cursor position can be
transmitted by the signal converter. The choice is a tradeoff based on the
cost of providing such units for each user in comparison to the cost of
fewer, shared units in composing unit 314 and on differences in
control-packet transmissions required.
Still-frame video decompressors 418 receive data packets containing
compressed still-frame video information in a format such as the
well-known JPEG-standard format. Each decompressor 418 typically includes
decompression logic and a frame buffer capable of storing the resulting
uncompressed data for all pixels in a full video frame, for example, the
C-Cubed CL550 circuit. If desired, such decompressors can also be provided
with smaller frame buffers for partial frames. The origin of such data
packets will typically be data cache 104.
Similarly, full-motion video decompressors 420 receive data packets
containing compressed full-motion video information in a format such as
the well-known MPEG-standard format. Each decompressor 420 typically
includes decompression logic and one or more frame buffers each capable of
storing the uncompressed data for all pixels in a full video frame, for
example the C-Cubed CL450 circuit. Again, if desired, such decompressors
can also be provided with smaller frame buffers for partial frames. The
origin of such data packets will typically be data cache 104 or broadcast
source 108.
Audio decompressors 434 receive data packets containing compressed audio
information in a format such as the Dolby AC-2 format. The output of audio
decompressor 422 is typically one or more audio signals in digital form.
If the particular audio compression format used does not provide for
multiple channels, then a decompressor 422 can be used for each audio
channel desired. Again, the origin of such data packets will typically be
data cache 104 or broadcast source 108.
Video scalers and positioners 430 and 432 each have the ability to accept
full video frames in digitized form from decompressors 418 and 420,
respectively, reduce the scale of such frames and reposition reduced
frames at specified locations in a full-size frame. The amount of the
scale reduction and the position are specified by control packets received
by control 424, which forwards the necessary control information to
scalers and positioners 430 a | | |
