Canadian Patents Database / Patent 2001263 Summary
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|(12) Patent Application:||(11) CA 2001263|
|(54) English Title:||DIGITAL AUDIO-VIDEO PRESENTATION DISPLAY SYSTEM|
|(54) French Title:||SYSTEME DE REPRODUCTION AUDIO-VISUELLE|
- Bibliographic Data
- Representative Drawing
- Admin Status
- Owners on Record
|(52) Canadian Patent Classification (CPC):||
|(51) International Patent Classification (IPC):||
|(72) Inventors :||
|(73) Owners :||
|(71) Applicants :||
|(74) Agent:||OSLER, HOSKIN & HARCOURT LLP|
|(74) Associate agent:||OSLER, HOSKIN & HARCOURT LLP|
|(22) Filed Date:||1989-10-23|
|(41) Open to Public Inspection:||1990-04-25|
|(30) Availability of licence:||N/A|
|(30) Language of filing:||English|
|(30) Application Priority Data:|
A digital audio-video presentation display
system is disclosed for use in an interactive communica-
tions system wherein a subscriber may select for viewing on
a television a plurality of audio-video presentations
consisting of particular sequences of selected video frames
and accompanying audio. The digital audio-video
presentation display system is responsive to commands from
a host computer which designates and prepares the
presentation for playback to the television of the
subscriber who has requested it. The digital audio-video
presentation display system includes a digital mass storage
subsystem which provides for digital storage of compressed
video and audio data, and a plurality of digital
audio-video display subsystems which include means for
retrieving the selected data from the storage subsystem,
means for expanding and reformatting the data into a format
suitable for television transmission, and means for
controlling the transmission of the information to the
subscriber who has requested it.
What is claimed is:
1. In an interactive communications system wherein a
subscriber may select for viewing on a television a plurality of
audio-video presentations consisting of particular sequences of
selected video frames and possibly accompanying audio, a digital
audio-video presentation display system responsive to commands
from a host computer which designates and prepares the
presentation for playback to the television of the subscriber
requesting the presentation comprising:
(a) a digital mass storage subsystem for storing
compressed video and audio data objects in digital format; and
(b) at least one digital audio-video display subsystem
(i) means for retrieving data objects corresponding
to each of the selected video frames and
accompanying audio information of the requested
sequence in digital format from the digital mass
storage subsystem upon command from the host
(ii) means for expanding and reformatting the digital
compressed video data into full frames of analog
video compatible with television transmission and
(iii)means for transforming the digital audio data
into analog baseband audio and for modulating the
baseband audio onto audio carrier frequencies
compatible with television transmission and
(iv) means for controlling the transmission of
the video frames and accompanying audio
information in analog format to the
headend of a cable network so that the
subscriber requesting the information
receives the information in the particular
sequence designated by the host computer.
2. The digital audio-video presentation display
system of Claim 1 wherein the digital audio-video display
subsystem further comprises means for encoding identifying
information in the vertical blanking interval of the
selected video frames.
3. The digital audio-video presentation display
system of Claim 2 wherein the digital mass storage
subsystem for storing and retrieving data objects of
compressed video and audio data in digital format further
(a) a plurality of disc storage volumes, each disc
storage volume including a disc drive, a disc drive
controller, and a single board computer which serves as a
disc storage volume manager that provides supervisory
control of the disc storage volume;
(b) a plurality of chassis, each chassis housing at
least one disc storage volume manager, at least one gateway
module for importing and exporting data to and from the
digital mass storage subsystem, at least one display system
command module for connecting the digital mass storage
subsystem to each of the display system controllers which
comprise the digital audio-video display subsystem, at
least one object locator module for determining which disc
storage volume is associated with a particular data object,
and at least one interchassis communications module for
interconnecting and transferring data to and from each of
the plurality of chassis.
4. The digital audio-video presentation system of
Claim 3 wherein the plurality of chassis include a central
services module in each chassis for providing maintenance
5. The digital mass storage subsystem of Claim 3
wherein the disc storage volume managers, the gateway
modules, the object locator modules, the display system
command modules, and the interchassis communications
modules each comprise a single board computer.
6. The digital mass storage subsystem of Claim 3
wherein the interchassis communications modules which
reside on one chassis are each connected in parallel to
corresponding interchassis communications modules on the
other chassis of the digital mass storage subsystem.
7. The digital mass storage subsystem of Claim 3
wherein a display system command module is individually
connected to a display system controller which comprises
the digital audio-video display subsystem.
8. The digital mass storage subsystem of Claim 3
wherein a display system command module is interfaced in a
redundant fashion to each of two display system controllers
which comprise the digital audio-video display subsystem,
and wherein each display system controller is interfaced to
two display system command modules, each of which is on a
separate chassis of the digital mass subsystem.
9. A method for storing and rapidly accessing and
retrieving data objects in the digital mass storage
subsystem, in which each data object to be stored is
identified by a name having a very large domain of
possibilities, comprising the steps of:
(a) storing the data by the steps of,
(i) mapping the large domain of possible data
object names into a smaller range of data
groups in such a manner that any portion
of the large domain maps randomly and
uniformly into the smaller range of data
(ii) associating an object name that has been
so mapped into a particular data group
with a particular disc storage volume;
(iii) storing the data object into a location at
that particular disc storage volume; and
(iv) storing the object name associated with
the data object in a lookup table
associated with that particular disc
storage volume; and
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(b) accessing and retrieving the data so stored by
the steps of;
(i) performing the same mapping as in step (a)
to the object name in order to determine
the data group and thereby the disc
storage volume wherein the data object has
(ii) accessing the lookup table associated with
that disc storage volume to determine the
location of the data object having the
particular name; and
(iii) accessing and retrieving the data object
from the particular disc storage volume
wherein it has been stored for further
10. The digital audio-video presentation display
system of Claim 1 wherein each digital audio-video display
subsystem further comprises:
(a) at least one digital video distribution unit
which includes means for transforming compressed video data
in digital format into full frames of video in RGB format;
(b) at least one digital audio distribution unit
which includes means for which transforming digital audio
data into baseband audio;
(c) at least one display system controller which
includes means for coordinating the orderly transfer of
data from the digital mass storage subsystem to the digital
video distribution units and the digital audio distribution
(d) a plurality of audio transmitters which include
means for receiving baseband audio signals from the digital
audio distribution unit and for modulating these audio
signals onto an audio subcarrier having a frequency
appropriate for television transmission; and
(e) a scheduler control unit including means for
accepting the RGB outputs from the digital video
distribution units, and for converting the frame into a
format compatible with television transmission and playback.
11. The digital audio-video display subsystem of
Claim 10 wherein the scheduler control unit further
comprises means for inserting identifying information into
the vertical blanking interval of each frame.
12. The digital audio-video display subsystem of
Claim 10 wherein the display system controller further
comprises a single board computer for receiving
presentation requests from the host computer and performing
the scheduling of these requests, a plurality of interfaces
for connection to the digital mass storage subsystem, a
second plurality of interfaces for connection to the
digital audio distribution audio unit, a third plurality of
interfaces for connection to the digital video distribution
unit, a plurality of single board computers for supervisory
control for monitoring the loading of the display systems
13. The digital audio-video display subsystem of
Claim 10 wherein the digital video distribution unit
further comprises a single board computer, an interface
card, a floppy disc drive, a floppy disc drive controller
and two digital video expander units for reading the
compressed video data and producing expanded video frames
in RGB format.
14. The digital audio-video display subsystem of
Claim 10, wherein the digital audio distribution system
further comprises a single board computer, a parallel
interface card, a small computer system (SCSI) interface
card, a floppy disc drive, a floppy disc drive controller,
and a plurality of audio playback boards, each of which
contains a digital signal processor, for converting the
digital audio data into baseband audio.
15. The digital audio-video display subsystem of
Claim 10 wherein the scheduler control unit further
comprises an RGB switch, an encoder for converting RGB
signals to a standard television transmission and playback
format, and an address inserter for placing identifying
information onto the vertical blanking interval of the
16. The address inserter of Claim 15, wherein the
identifying information comprises the address of the frame
store unit to which the video frame will be sent and the
audio receiver tuning code.
A DIGIT~L AUDIO-VIDEO PRESENTATION DISPLAY SYSTEM
- FIELD OF THE INVENTION
The present invention relates to an interactive home
shopping system which can deliver to a subscriber particular
television video frames depicting shopping items of interest
which the subscriber has requested, along with an accompanying
audio message. The system permits a shopper, in the comfort of
his home, to browse through an ~electronic mall" of different
shops, obtain detailed information on particular items, and make
purchases. More particularly, this invention relates to and
describes a digital audio-video presentation display system for
use in an interactive home shopping system, in which all the
necessary video and audio information is stored in digital form,
and wherein the information is further manipulated in digital
form to provide the proper timing which ensures that the
shopping presentation is transmitted to a particular subscriber
in the appropriate time sequence.
BACKGROUND OF THE INVENTION
Home shopping by use of the television has been
growing in popularity in recent years. Generally, home shopping
channels are transmitted on a community antenna television
(CATV) facility. The CATV facility, which has the capacity for
transmitting a multiplicity of commercial and public television
signals, is usually connected to a large number of homes via
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coaxial cable. In most of the home shopping systems being
offered to date, subscribers passively view the home shopping
channel, watch tems and pricing being presented by television
sales people, and if interested in any particular item, can
place an order over the telephone with a sales person. These
systems are non-interactive, in the sense that a viewer can only
passively watch items as they are presented on the television
screen, but cannot control the course of the shopping
A more advanced interactive home shopping system has
been designed and implemented, in which viewers are able to
request particular items to be presented for display and can
control the shopping presentation as they proceed. A system of
this sort is described in U.S. Patent No. 4,734,764, entitled
"Cable Television System Selectively Distributing Pre-recorded
Video and Audio Messages~. This prior art invention describes a
system which conveys still-frame television-quality video with
overlaid graphics information and an appropriate audio message
(when desired), to a multiplicity of CATV subscribers who tune
to a particular cable channel. The subscriber, by use of a
Touch-Tone telephone, transmits particular codes in response to
message prompts which are displayed in menu form on the TV
screen, and requests video displays and information on specific
products, as well as make purchases. The user of this system
requires no additional equipment other than a Touch-Tone
telephone and a television.
In order to interactively operate this type of home
shopping system, a subscriber tunes to the CATV channel ~hich is
being used for transmission, and dials a telephone number ~o
access the system. Each subscriber is given a particular
identification number upon subscribing to the service. When
this identifying number is entered via the telephone Touch-Tone
keypad, the system recognizes the subscriber and his location.
Based upon succeeding codes which are displayed on the
television screen, and which the subscriber enters on the
Touch-Tone keypad, his television screen begins to display
still-frame video, having overlaid graphics where appropriate,
and possibly accompanied by a sound track to present information
which he has requested on an item. Graphic overlays depicting
menus and directories of the ~electronic stores" which are on
the system are also displayed, and by responding to these menus
with a sequence o~ Touch-Tone commands, the subscriber may
browse through a particular store of his choice (e.g. a
particular aisle in a supermarket), select a particular product
of interest, make purchases or request additional information or
help in response to prompts on the television screen.
This interactive home shopping system uses a CATV
cable network to transmit the video presentations and
accompanying audio messages as requested by subscribers. In
conventional video transmission, video frames are transmitted at
the rate of 30 frames per second (the North American or Japanese
standard), or 25 frames per second (the European standard).
video frame is an interleaved composition of two video fields,
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with each video field bein~ ~urther composed of a plurality of
scan lines referred tO as the vertical blanking interval, a~d a
larger plurality of scan llnes which contains the video image
information. The interactive home shopping system described in
U.S. Patent No. 4,734,764 makes use of the vertical blanking
interval (which consist of the ~irst 21 lines of the video
field) to store information which identifies the particular
subscriber to whom the requested video and audio data will be
sent and his location. The control center of the CATV system
(the CATV headend) transmits the video and audio data with-this
addressing information in the vertical blanking interval down
the main "trunk~ coaxial cables of the system. In order to
compensate for signal losses which naturally occur down the
transmission line, most CATV cable systems incorporate
amplifiers at strategic locations called "nodes", which are
downstream from the control center. At each node an amplifier
amplifies the signals from the control center, and transmits the
amplified signals down a plurality of secondary distribution
cables. Each of the secondary distribution cables is generally
provided with a plurality of tertiary distribution cables known
as "taps", and finally each of these taps is further split into
a plurality of "drop~ cables which terminate at the subscriber's
In order to accommodate a large number of concurrent
subscribers, the interactive shopping system described in U.S.
Patent No. 4,734,764 utilizes a device known as a frame store
unit typically located at each node of the distribution sys~em.
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Each frame store unit services a small number o cable drops,
and functions to capture the video ~rame that is destined for a
subscriber whose particular ID code, encoded in the vertical
blanking interval, is associated with the unit. Thus, a frame
store unit captures video frames having a particular address
encoded in the vertical blanking interval of the frame and
stores the video information of that frame into its memory. The
video frame store then replays the stored video information 30
times per second (according to the U.S. National Television
Standards Committee (NTSC) requirement), and transmits the video
along with any accompanying audio message to the particular
subscriber that it is servicing.
In the prior art system of U.S. Patent No. 4,734,764,
which has been brièfly described above, the video and audio data
which comprise a particular presentation offering by a merchant,
must first be processed and encoded onto conventional laser
video discs. A plurality of conventional video disc players at
the central system site transmit the appropriate video and audio
information in analog form, under control of a central
processing unit. T~.is information is then time multiplexed in
the proper sequence, and appropriately modulated and frequency
converted for transmission down the CATV cable channel.
Numerous problems and limitations are associated with
this type of ~'analog~ video display system. First, a large
number of video disc players are required, making the cost and
physical size of the electronics for the interactive home
shopping system exorbitant. Second, the response time between a
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subscriber keying in a particular code on the telephone keypad
and the appearance of a display in response to that code is too
slow to provide Cor a comfortable interactive session. The
response time in the analog system is limited by the time it
ta~es for the video disc player to access a particular frame
which can be on the order of three seconds. The slow response
time is compounded by the graphics overlay process, in which a
graphics decoder receives the graphics information that is
associated with a particular video frame from the central
processing unit, generates the appropriate graphics display data
and routes this data to a video combiner, which receives the
video frame from the video player and overlays the graphics
information onto the video frame.
Further, in the prior art analog system, the audio
information is stored on the video disc in the electronic forma~
of the video frame. This imposes a maximum limit of ten seconds
for the duration of the audio portion associated with a
particular frame. In many cases, this time limitation is too
restrictive for practical use,
An additional limitation arises from the use of a
laser disc as the storage medium for the video and audio data.
A merchant who desires to put a particular presentation for his
business onto the interactive home shopping system of the prior
art must undertake a lengthy premastering procedure, required to
convert his original material (possibly in the format of catalog
photographs, video tape information, etc.) into a format whicn
is encoded onto a video disc master. Multiple copies of .he
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master disc must then be made so that each video disc player in
the system can have access to the information when it is called
upon to deliver a particular frame to a requesting subscriber.
This premas~ering and duplication process is a time-consuming,
linear and batch-oriented procedure which provides no mechanism
for making minor modifications at a later date. Thus, no
reusable archiving is possible. If changes are required, a new
video disc must be mastered and reproduced.
Finally, the prior art system has general problems
which are fundamentally related to storing and copying data in
analog form. Analog signals are more prone to degradation by
noise sources that arise in any electronic system. Further, the
maximum signal to noise of the video signals which are
attainable at the output of a video disc player is several
orders of magnitude below the noise figure for studio quality
video broadcast. Degradation of analog signals as they are
transmitted down the long lenqths of coaxial line which
comprises the CATV system is inevitable. This further degrades
the video image seen by the subscriber.
SUMMARY OF THE INVENTION
It is the objective of the present invention to
provide for a digital audio-video presentation display system as
part of a new and improved interactive communications system for
merchandislng products and services to subscribers.
It is a further object of the present invention to
overcome the deficiencies of the analog display system used in
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the prior art system described above, by providing a digital
audio-video display system which utilizes a different conceptual
approach, but which is embodied in a system of ~ardware and
software that is nevertheless downward compatible with tne
overall home shopping system, as practiced by the prior art U.S.
Patent No. 4,734,764.
It is another object of the digital audio-video
presentation display system of the present invention, to
maintain and process the video and audio signals in a digital
format, thereby providing for more accurate reproduction o~ the
It is yet another object of this invention to provide
for a digital audio-video presentation display system which is
considerably more cost effective and of physically smaller size
than the prior art analog video display system,
It is still another object of the invention to provide
for a digital audio-video presentation display system having
markedly de~reased response time to a subscriber's input, when
compared to the prior art analog system, and which does not
impose severe constraints on the length of audio information
which can be transmitted along with the video data.
Another object of this invention is to provide for a
digital audio-video presentation display system which obviates
the need for a cumbersome premastering procedure, as is required
in the prior art analog system to prepare masters of video discs
which carry the appropriate commercial presentations designed by
merchants, and which does not require the making of a plurality
of copies of these master discs.
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It is another cbject of this invention to provide for
a digital audio-video presentation display system which has an
innovative digital mass storage subsystem for storage and
retrieval of video and audio data, which can be shared easily
among a plurality of digital audio-video display subsystems as
described further herein, and which provides for a reusable
It is an additional object of this invention tO
provide a novel encoding technique for storing large amounts of
data in the digital mass storage subsystem which permits rapid
retrieval of a particular set of data from the large database of
information stored on the digital mass storage subsystem.
The present invention is directed to a digital
audio-video presentation display system which can be used iA
conjunction with other elements o an interactive shopping
system which allows a subscriber to choose a shopping
presentation comprising particular items for display and
purchase by keying in codes on a standard Touch-Tone telephone
keypad as prompted by menus, graphics, and audio which are
presented on the television screen. The digital audio-video
presentation display system of the present invention comprises a
digital mass storage subsystem for storing compressed audio and
video data, and one or more digital audio-video display
subsystems. Each of these digital audio-video display
subsystems includes means for retrieving compressed data which
corresponds to the selected audio and video presentation from
the digital mass storage subsystem, means for expanding and
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re:Eormatting the video data into a format compatible for
television transmission, means for transforming and modulating
the audio data onto appropriate television carr'er frequencies,
and means for performing the transmission of the audio and ~ideo
data in proper sequence to a requesting subscriber.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and objects
of the invention, reference should be made to the following
detailed description, as illustrated in the accompanying
FIG. 1 is block diagram of the overall home shopping
system which illustrates the major functional components of the
FIG. 2 shows the configuration and functions of the
digital mass storage subsystem chassis.
FIG. 3 illustrates the disc storage volume, which is
the building block of the digital mass storage subsystem.
FIG. 4 represents a scheme for connecting the
interchassis communications modules.
FIG. 5 shows a non-redundant method of connecting the
digital audio-video display subsystems to the DMSS chassis.
FIG. 6 illustrates a f~ult-tolerant redundant method
of connecting the digital audio-video display subsystems to the
FIG. 7 is block diagram of the major functional
components of a digital audio-video display subsystem (DAVDS).
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FIG. 8 illustrates the hardware interconnection
for the display system controller (DSC).
FIG. 9 is a sof~ware process diagram representing the
miajor soft tasks implemented in the display system controller
FIG. l0 is a block diagram illustrating the hardware
configuration of the digital video distribution unit (DVDU).
FIG. 11 is a process flow diagram illustrating the
major software tasks implemented by the digital video
distribution unit (DVDU).
FIG. 12 is a bloc~ diagram which illustrates the
hardware configuration of the digital audio distribution unit
DETAILED DESC~IPTION OF THE INVENTION
With reference to FIG. 1, the digital audio-video
presentation display system is shown in its relationship to the
other major elements of the overall interactive home shopping
system. At least one telephone management subsystem 10 (TMS) ia
present in the overall system to receive telephone requests from
the subscribers (in the form of Touch-Tone signals) and to relay
those requests to the central processing unit of the host
computer 20, which in a preferred embodiment is a Tandem VLX
mainframe system. The digital audio-video presentation display
system 30 comprises a digital mass storage subsystem 40 (DMSS)
which holds the database of digitized and compressed video and
audio presentations, and at least one digital audio-video
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d:isplay subsystem so (DAVDS). A preferred embodiment of the
diqital audio-video display system 30 uses seven active digital
alldio-video display subsystems each one of which is capable of
servicing approximately 200 concurrent subscribers. The overall
system is protected by a single independent DAVDS. This DAVDS,
when requested by the host computer, can replace any one of the
seven active DAVDS which may suffer a failure or a reduced
performance condition. The overall interactive shopping system
incorporates the use of both on-line and off-line measurement
techniques to ensure that failures which may cause the system
degradation or reduced performance, are rapidly detected.
The output of the digital audio-video display system
30 is transmitted to the CATV headend 80, and then down the CATV
cable lines where it is intercepted by the particular frame
store unit 60 (FSU) which services the particular subscriber.
The frame store unit 60 replays the video frame at an
appropriate rate to provide a still-video image, along with any
accompanying audio, of selected items in the presentation. .
production system 70 is interfaced to DMSS 40. The production
system 70 is used by merchants to prepare their commercial
presentations, which are then stored in DMSS 40.
It is helpful at this point to define some of the
terminoloqy that is used in this disclosure, and which relates
particularly to the presently preferred embodiment of ~he
digital audio-video presentation display system.
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1. Seqment: This is a series of audio frames (usually
0-4) followed by a series of video frames (usually
2. Presentation: A presentation consists of a series of
segments, as initially set up and defined by the
3. Script: A script is a data structure generally of
several hundred to several thousand bytes in length,
which contains information that defines the time
sequence for the display of audio and video images
within a presentation. The script also contains
information as to what kind of data (e.g. video or
audio) is contained within the frame, as well as
overlay graphics information.
4. Data Object: A data object is a generic term for any
string of data. The object string generally includes
structural information about itself.
THE DIGITAL MASS STORAGE SUBSYSTEM
The Digital Mass Storage Subsystem (DMSS) comprises
the database of digitized/compressed video and audio presenta-
As such, it is a repository for a plurality of large
data objects, each of which contains a compressed video image or
a portion of digitized audio. The objects range in size from
about 200 bytes up to about 100,000 bytes. The average size is
about 40,000 bytes. The DMSS, in a preferred embodiment, can
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accommodate 1,000,000 such objects (each individually named),
can accept "retrieve" commands for individual objects by name
and deliver the named object within 80 milliseconds.
~dditionally, it can accommodate seven active digi~al
audio-video display subsystems (DAVDS) and one spare DAVDS, and
provide a bandwidth for delivering objects to any one DAVDS of 4
megabytes/second, r~hen an object is requested by a DAVDS which
is not present in the DMSS, it can be fetched automatically
through a gateway device to an archival versian of the digital
mass storage subsystem which contains a backup copy of ali data
objects. The DMSS can accept commands through the gateway to
either delete or store data objects. Further, when traffic
demands can not be satisfied instantaneously, the DMSS provides
for queuing of commands to be serviced on a priority basis.
rn order to meet these requirements, a set of up to
eight standard, Multibus II chassis are provided in a preferred
embodiment. Multibus II is an "open system" bus architecture
which is commonly used by many people in the computer industry.
The actual number of chassis required by the system depends upon
the number of data objects which need to be contained. Each
chassis is populated with 19 identical, single board computers
(SBCs) of the Intel 386/100 class, each SBC having two industry
standard Small Computer System Interface (SCSI) ports and
built-in diagnostics. The functions of the SBCs, as described
more fully below, provide for disc volume management, object
location, gateway connection, inter-chassis communication, and
communication with each DAVDS. Test and future expansion slots
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are also available. The hardware layout of a preferred
embodiment of the DMSS is depicted in FIG. 2, which shows the
configuration and functions of a standard chassis.
The basic building block of the DMSS is called a "disc
st:orage volume". Data objects are stored on the disc storaqe
volumes. A disc storage volume 300, as illustrated in FIG. 3,
comprises a disc drive unit 310 such as the Maxtor 760 megabyte
unit, a controller 320 for the disc drive unit connected tO the
drive via an industry standard Enhanced Small Disc Interface
(ESDI) interface, and a single board computer (SBC) which acts
as the disc storage volume manager 330, and which is connected
to the controller via a SCSI interface.
With reference to FIG. 2, the single board computers
(SBCs) on board each chassis provide different software
functions to the system. The disc storage volume managers 330,
of which there may be up to ten on a chassis, have the function
of storing, retrieving, and deleting data objscts. Each disc
storage volume manager 330 also stores a record of the object
name index of its associated disc storage volume for recovery
purposes. A volume manager 330 also sends messages to each of
the object locator modules 350 (OLMs), reporting its own slot
and chassis number, and describing the data groups which it
contains. The interchassis communication modules 360 (ICCMs)
route messages which are received from the Multibus II backplane
to other chassis of the DMSS over the SCSI ribbon cables and
correspondingly route messages which are received over the
ribbon cables to the appropriate slots on their chassis. The
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display system command modules 310 (DSCMs) are connected to tne
display system controllers of the DAVDS, which are described
more fully below, ~ia SCSI interface links. The software
function performed by the DSCM 370 is to receive requests for
data objects from the display system controllers, and deliver
corresponding data objects to the display system controllers for
further processing. As shown, the preferred embodiment has tWO
DSCMs 370 per chassis. The display system controllers deliver
their re~uests for a desired data object to the DSCM 370. This
message is routed to the onboard object locator module 350 ~ia
the Multibus II backplane, or to object locator modules on
different chassis via the interchassis communication module 360
(ICCM). The object locator module 350 (OLM) performs a mapping
function described with more particularity below, which
determines the data storage volume where the data object
resides, and transmits a retrieval message to that volume
requesting that the particular data object be sent to the
digital audio-video display subsystem (DAVDS). The gateway
module 380 imports and exports data objects and messages upon
command from other digital mass storage devices, or from object
locator modules 350. Additionally, each chassis contains a
central services module 390 (CSM) which performs housekeeping
functions for the chassis and which is a required component in a
Multibus II application system. Test equipment and additional
expansion slots 395 are also available on each chassis for
development, testing and future expansion.
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FIG. ~ shows with more particularity the parallel
connection pathways for connecting the interchassis
communication modules 360 which reside on different chassis tO
each other. As shown, each of the single board computers which
provide the ICCM functionality have dual SCSI interface ports.
As illustrated, data and command flow between the chassis is
provided by up to four of these SCSI connections per chassis,
with each pair of ports from a particular ICCM 360 being
connected in parallel fashion to all the other chassis of the
system. The parallel pathways and the built-in redundancy
ensure that communications between chassis occurs rapidly, even
under high system load conditions. The number of such
connections which are actually necessary depends upon the number
of digital audio-video display systems (DAVDS) that are
connected to the DMSS.
The display system controllers of each of the digital
audio-video display subsystems, which are described more fully
below, may be connected with the chassis which comprise the DMSS
in the manner shown in FIGS. 5 and 6. The connection arrange-
ment is flexible and may be determined for each installation
according to the number of data objects that will be stored and
the number of digital audio-video display subsystems which will
be needed to service traffic at the operating site. For
example, in FIG. 5, a non-redundant connection, in which each of
the digital display system controllers 315 is connected via a
SCSI interface link o a display system control module 3~0.
FIG. 6 shows an alternative embodiment wherein each display
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system controller 315 is connected to two display system control
module5 3~0, each of which is on a different chassis. In turn,
each display system control module is seen to service two
di.splay system controllers 315 over its dual oort SCSI
interface. The redundant connection shown in FIG. 6 may be
desirable for fault tolerance purposes and to ensure overall
Each data object stored in the DMSS must be given an
identifying name. In order to provide the system with
suf f ic ient flexibility for name allocation purposes, each object
name is stored in a data field which is 20 bytes long. An
exceedingly large number of possibilities of names (2562) is
thereby provided for.
A novel encoding methodology has been implemented in
the DMSS which permits rapid search and access of this
potentially large set o data objects. The methodology utilizes
the notion that the domain which comprises the large set of
distinct data object names may be mapped, by any number of
straight-forward algorithms, into a range comprising a much
smaller set of numbers. Each member of this smaller set, which
is designated as a ~'data group" is then associated with a
particular volume. Since the mapping is not one-to-one, each
data group represents a plurality of distinct data object
names. However, since each data group is associated with a
particular volume, the volume containing the desired data object
may be rapidly accessed. A second stage search within the data
volume, which has a lookup table of manageable size containing
all the distinct data object names that are stored in the data
volume, permits rapid location of the desired named data
object. Association of a particular data group with a
particular data volume is performed by the object locator module
350 (OLM) in each DMSS standard chassis, which at all times
knows how many active data volumes are on the system, and which
data volumes provide storage for any data group. In order to
distribute objects uniformly throughout the different data
volumes, the mapping must be performed in such a way that a
small region of the large domain of distinct data object names
is mapped uniformly over the complete range comprising the data
group set. This is required to ensure that data object names
are sufficiently randomized during the mapping process so that
they are uniformly distributed over the different active data
~olumes of the system.
The following example serves to illustrate how such a
mapping may be performed to map 20 bytes into 2 bytes (or 16
bits), thereby providing for a total of 65,536 possible data
group elements. This example illustrates only one of many ways
in which a domain of 20 bytes which represents the totality of
possible data object names can be mapped uniformly into a 2 byte
range. Data object name formats may differ depending upon the
particular type of object being named. In this illustrative
example we assume that there are three different kinds of data
object names. For example, a name for a presentation data object
may have the following format:
P~ESE~TATION OBJECT NAME: TTTTCCCCCPPPPPFFFFFF
byte 1................ 20
.~,. . ~ - . '
rn ehis naming scheme, the type of data object is allocated a 4
~yte field denoted by "T'`s. the client name is allocated a 5
byte field denoted by ~'C"s, the presentation number is a 5 byte
field denoted by "~"s. Similarly, the particular frame number
is denoted by the F field and the frame type (audio or video) is
denoted by the f field. A name for a subscriber identification
data object may have the following format:
SUBSCRI~ER ID OBJECT NAME: TTTTLLLLLLNN?D~n~NN
byte 1.................. 20
in which the ~T~ field again designates the type of object, the
"L" field designates the operating center and the N field
designates the subscriber's telephone number. The name for an
order data object may be likewise designated as
ORDER OBJECT NAME: TTTTTLLLLLNN~nnnn~NiN
byte 1.................. 20
in which the object type field is again designated by "T"s, the
local operating center that has taken the order is designated by
the "L" field and the order number is designated by the "~"
By appropriately selecting bytes from these different
types of data object names which display the most variability,
and by performing a series of operations on these bytes which
lead to further randomization, one may obtain a two byte range
which maps the entire 20 byte domain in a highly uniform
manner. For example, it may be determined by analysis of the
data object names that the most variable byte in the
presentation object name is byte 14 (the lowest order digit of
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the presentation number), and that similarly the most variable
bytes of the data object name which denotes subscriber
identification information are the two last dig.ts of the
subscriberls telephone number (bytes 19 and 20). Likewise, it
may further be determined that bytes 15 and 16 of the object
names as number of which designate orders are the mos~
variable, After selecting the most variable bytes (e.g. byte 14
from the presentation object name, bytes 19 and 20 from the
subscriber identification object name, and bytes lS and 16 from
the order object name), one can perform a highly randomized
mapping of the original 20 bytes into 2 bytes by following a set
of rules such as:
1. Concatenate bytes lg, 19, 20, 15 and 16. Bytes 14,
19, 20 may be designated by A and lS and 16 as ~.
14, 19, 20 15, 16
2. Add B to A, dropping any carry. This leaves a 3 byte
3. Add the first 8 bits of the sum (byte 14) to the low
order 16 bits, again dropping any carry.
In this manner, a 16 bit (2 byte) number is obtained
which by virtue of its construction, is designed tO map any
section of the domain of the large 20 byte set uniformly over
the full range of the much smaller 2 byte set.
In operation, as a particular data object is presented
for storage in the DMSS, a mapping function of this type i a
performed by the object locator module 350 (OLM) which converts
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the name of the data object into a particular data group of the
small range. The OLM 350 allocates a particular data volume for
that data group. As o~her data objects names come into the
system, the mapping again forces the same data groups to be
stored in the same volume. The full object name is stored in a
lookup table at the disc storage volume manager 330 that is
associated with each disc drive. Since each disc drive holds at
most 20,000 objects, the lookup table of object names in each
volume manager 330 is of manageable size.
In order to retrieve a particular data object, the
same mapping is performed, which immediately tells the object
locator module 350 (OLM) which data volume contains that
particular object. Once the volume is accessed, a second stage
of the search, which searches the object name in the particular
volume's lookup table is then performed to find and retrieve the
data object. This two-step data allocation and retrieval
approach permits a very large data base structure to be searched
rapidly. Rapid retrieval of data objects is essential in order
to provide acceptable response times for the interactive video
THE DIGITAL AUDIO-VIDEO DISPLAY SUBSYSTEM
Each digital audio-video display subsystem 50 of FIG.
1 SDAv~s) is comprised of five major units as shown in FIG. 7,
which, with reference to that figure, include:
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1. A DisPlav Svstem Controller
The display system controller lQ0 (DSC) coordinates
and orders the transfer of data from the DMSS 40 to other
components of the DAVDS, such as to the digital audio-video
distribution units 110 (DVDU) and the digital audio
distribution units 120 (DADU) which are described below.
It also maintains the time synchronization of the DVDUs 110
and DADUs 120 to provide minimum response times to the
subscriber and to maintain high presentation data transfer
rates. The transfer of audio and video data, as werl as
control and status information to and from the DADUs and
DVDUs is done via standard Small Computer System Interface
2. A Diqital Video Distribution Unit (DVDU)
It is the function of the digital audio-video
distribution unit 110 (DVDU) to transform compressed video
data into full frames of video in standard RGB format. In
a preferred embodiment each DAVDS contains two or three
DVDUs. Each DVDU in turn contains two Digital Video
Expanders (DVEs). The two DVDUs, working in combination
will provide frames at a rate of about 24 per second. This
will serve 200 concurrent users at expected consump~ion
rates. Three DVDUs are needed to provide thirty frames per
second, the maximum permitted in the NTSC video format.
3. A Diqital Audio Distribution Unit (DADU)
The function of the diqital audio distribution unit
120 is to transform audio data which comprises the audio
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proqram, and which may be in compressed Corm, into
baseband audio, which is then sent to the audio
transmitters 130 for modulation onto an audio subcarrier.
In a preferred embodiment, there are twenty channels of
audio per DADU and ten DADUs per DAVDS. Thus each DAVDS
has two hundred independent audio channels for concurrently
serving 200 active subscribers.
4. Audio Transmitters
Each of the audio transmitters 130 receive audio
signals from the DADU 120 and in a preferred embodiment,
modulate these audio signals onto one of five hundred and
seventy two discrete frequencies in the 41-46 megahertz
band. This frequency range corresponds to the standard
intermediate frequency (IF) of a CATV upconverter which
further converts the audio for transmission to any standard
CATV channel. The typical audio system may thus occupy any
four-megahertz channel in ~he CATV distribution network or
alternatively, or two groups of audio channels may be
combined into a single six-megahertz channel.
5. A Scheduler Control Unit (SCU~
The scheduler control unit 140 (SCU) accepts the RGB
outputs from the DVDUs 110 and converts them into the
standard NTSC video format (with all required addresses and
audio tuning codes included in the vertical blanking
interval) for presentation to the CATV headend control
center which injects the signals into the CATV transmission
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A more detailed description of each of Shese five
functional elements o~ the DAVDS now follows.
1. The Displav System Controller (DSC)
In a preferred embodiment, the hardware of the DSC lO0 is
configured in an open system bus structure such as the Multibus
II chassis (which includes a twenty slot Multibus II backplane,
a central services module, and a power supply). With reference
to FIG. 8, a processor board, which in the preferred embodiment
is an Intel 186/530 processor functions as the DSC 100 scheduler
210 and receives presentation segment requests from the~ host
computer via its internal local area network interface 220. The
processor schedules the presentation requests, and responds to
the host computer with status information when the requests are
The function of the DSC 100 is to generate the timing for
properly interspersing and collating the video frames for all
concurrent subscribers who have shopping sessions in progress
(up to approximately 200 per DAVDS). The information which
describes the playback of the presentation to the subscriber s
contained in "a script", which as defined above, is a data
structure of several hundred to several thousand bytes wh,ich
contains the time sequence information for properly displaying
audio and video images within a presentation. Upon capturing
the script from the host, the DSC lO0 ascertains that the script
is played out properly to the particular subscriber who has
requested it. Moreover, the DSC loO properly intersperses he
scripts to different subscribers in such a way that timing
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delays caused by syst~m load conditions are minimized so that
the video and audio ~re presented as closely as possible to what
was intended. The script information resides in the presenta-
tion database of the host c~mputer. DSC 100 is connected to the
DMSS 40 by a plurality of SCSI boards 230. These boards carry
the fetch requests to, and return compressed audio and video
data from the DMSS 40. Two additional SCSI boards 250 connect
DSC 100 to the digital audio distribution units. Control
information and audio data, are transmitted from the DSC lOo to
the DADUs 120 along this interface, which also functions tO
return the response information from DADUs 120. Two more SCSI
boards 240 connect the DSC 100 to the DVDUs 110. These boards
permit the transmission of control information for the text and
video data to the digital video display units, and return
response information from the video display units back to DSC
100. An additional four Intel 186/100 processor boards, known
as DSC image controllers 260 perform supervisory control over
the SCSI interfaces which connect DMSS 40, DVDUs llo and DADUs
120. An additional Intel 186/100 board known as the DSC 100
queuer 270 is provided to allocate requests to, and monitor the
loading of the four DSC 100 image controllers 260.
Software Functions Of The DSC
In addition to a number of system processes and
support processes, application processes are provided in the DSC
100 s~stem which are responsible for processing the segment
messages from the host computer. A process flow diagram for the
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DSC loo is shown in FIG. 9. with reference tO that figure, he
major software tasks which are provided i~ the preferred
embodiment of the DSC 100 are briefly described as follows:
As individual steps contained in the script received
from the host computer become due, the scheduler 400 sends
request messages to the queuer task 410 to initiate the
presentation of the image to the appropriate subscriber.
The queuer task 410 partitions the requests ~
receives from the scheduler, and spreads them across the
available image controllers 420 in order to achieve and
maintain a proper system load balance. The queuer 410 also
selects which DVDU will be used to process the request.
C, Imaqe Controller:
This process provides the appropriate command
sequences for s-~nchronizing the audio and video generation
and the delivery of the data to a subscriber's frame store
unit. It monitors the DVDU and the DADU throughput and
attempts to initiate the audio part of the presentation as
closely as possible to the delivery of the irst video
2. The Diqital Video Distribution Unit (DVDU):
The function of the digital video distribution unit (DVDU)
is to transform compressed frames of video into full frames of
video in standard RGB video format so that when requested, these
frames can be presented to the scheduler control unit (SCU) 280
for transmission to the cable system.
.: - - , :. . .- . , :
In the preferred embodiment, the hardware configuration of
the DVDU, as shown in FIG. 10, is contained in a chassis wnich
has a passive IBM PC-AT backplane, an 80386 AT-compatible CPU
card with four megabytes of memory 500, a SCSI interface card
having an integral floppy disc controller 510, a floppy disc
drive 520 and two digital video expander (DVE) units s30. The
SCSI interface provides the pathway for receipt of compressed
video data and control information and for transmission of
status information to the display system controller (DSC lO0).
The two digital video expander (DVE) boards 530~~ each
comprise a pair of video processors. Compressed video data is
read by the first processor, which produces a block of data in
expanded format. The expanded data is then processed by the
second processor to produce the video frame in RGB format for
subsequent presentation to the scheduler control unit. An
additional function of the DVDU which is provided by the second
video processor is to produce graphics image overlays of a
variety of fonts, having different colors (background and
foreground), sizes and other artistic attributes such as drop
shadows, and kerning. The graphics data for these image
overlays is produced either during the initial set up of the
presentation by the merchant, or interactively by the host
computer in response to particular requests made by the
subscriber during the shopping session. The appropriate scripts
for the overlay graphics are stored in the host computer.
The compression of video data is performed at the time of
initial presentation encoding by the merchant. The result of
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this compression is data which represents the original video
image and which also contains a set of algorithms which are
ne!eded to reconstruct the original image.
Software Functions Of The DVDU:
The basic function of the DVDUs 110 is to expand
compressed video data, combine it with any associated
text/graphics data and deliver RGB formatted video to the video
switch of the SCU.
The software structure for the DVDU is illustrated in
FIG. ll. The three basic tasks required to perform the above
functions are briefly described as follows:
The scheduler task 600 provides a communication
capability to the DVDU and the DSC 100 via a SCSI interface
625 and also provides for synchronization of the operations
within the DVDU.
B. OverlaY Manaqer:
The overlay manager task 610 controls the translation
of text~graphics commands into the proper microcode
instructions which are acceptable by the second digital
video expander 612.
C. Display Manaqement:
The display manager task 620 controls the expansion of
the video by digital video expander 614, and its display in
response to commands from the DSC 100.
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3. The Diqital Audio Distribution Unit (DADU):
The digital audio distribution unit transforms the audio
data, which may be in compressed format, into original baseband
audio form. This is then presented to the transmitters for
modulation onto a channel of the CATV cable system.
With reference to FIG. 12, the hardware configuration of
the DADU in a preferred embodiment is contained in a chassis
which has an IBM PC-AT backplane, and 80386 AT-compatible CPU
card 700 with four megabytes of memory, a parallel interface
card 710 which serves as a communications port to the
transmitter, a SCSI interface card having an integral floppy
disc controller 720, a floppy disc drive 730 and 10 dual-channel
audio playback boards 74~.
The audio portion of the shopping presentations may be
encoded and compressed using an Adaptive-Differential-Pulse-
Code-Modulation ~ADPCM) during the initial presentation
processing. The ADPCM group of algorithms is widely used and
exhibits well characterized behavior. The compressed audio data
as well as appropriate control information is transmitted from
the DSC 100 along the SCSI interface to the DADU. The parallel
interface provides tuning control of the transmitters and
monitors their status. The CPU manages the data flow into and
out of system memory and ensures that the audio data is routed
to the appropriate audio playback circuits. Each of the audio
boards contains a digital signal processor with enough buffer
memory to provide continuous audio playback while the CPU
performs other tasks.
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The Software ~unctions Of The DADU
The DADU software, upon receipt of audio playback
requests from the DSC loo, manaqes the audio data associated
with these requests and controls the loading of this data into
the audio playback circuits. The DADU softwa~e also provides
proper interfacing to the audio transmitters~ The software
includes both utility tasks as well as supervisory tasks. Among
the utility tasks, there is a SCSI driver which provides a data
path for receiving audio data from the DSC 100 and for properly
routing it to a buffer memory from which it is transferred back
to the audio boards, a tuner driver which communicates over the
parallel port to the DADU to pass signals to the transmitter
tuner hardware, and an audio driver which provides the proper
protocol for transferring data to and from the audio boards.
The most important of the supervisory tasks is
performed by the schedùle control program which acts to receive
new audio loads from the DSC 100, sets up appropriate audio
channels, and tunes the transmitters.
4. The Audio Transmitter
The audio transmitter in the preferred embodiment, consists
of 10 dual transmitter cards, an interface card and a power
supply mounted in a chassis. It functions to amplitude-modulate
up to twenty baseband audio channels which are received from the
DADU and then mixes and places them onto a carrier frequency
associated with a specified audio IF channel. In particular, in
the preferred embodiment, each transmitter card consists of ~wo
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single transmitters having combined outputs. The audio signal
is double-side band amplitude modulated onto a 10.738635 MHz
carrier, and this amplitude ~odulated IF signal is then
up~converted to the desired CATV channel output frequency by
standard mixing techniques.
5. The Scheduler Control Unit
. _ _
The scheduler control unit 140 (SCU), as shown in FIG. 7,
comprises, in a preferred embodiment, an RGB video switch 142,
an RGB to NTSC encoder 144 and an address inserter 146. The RGB
video switch 142 accepts the multiple RGB outputs from the DVDUs
110 110, and switches these outputs into a signal path which
forms the RGB signal stream. The NTSC encoder 144 operates on
this signal stream and produces NTSC formatted video output
which is passed to the address inserter 146. In countries which
do not utilize the NTSC transmission standard, a similar encoder
would be utilized to perform the function of producing formatted
video output compatible with that country's transmission
standard. In particular, sys~ems designed for use in most
Western European countries (as well as some South American
countries), which utilize the PAL transmission standard would
convert the RGB output to the PAL format. Similarly, the RGB
signals would be converted to SECAM format in systems designed
for use in France and the USSR. In the address inserter, the
address of the particular frame store unit and the audio
receiver tuning code are inserted into the vertical blanking
interval of the frame.
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In a preferred embodiment, the SCU hardware is
configured within the DSC 100 and communicates, via a number of
parallel input/output lines with the address inserter and the
To summarize, a digital audio-video presentation
display system (DAVDS) has been disclosed which overcomes the
deficiencies present in analog video display systems used in the
prior art. The digital audio-video presentation display system
disclosed herein comprises a digital mass storage subsystem and
a digital audio-video display subsystem. A novel method of
encoding a large set of object names required by the interactive
home shopping system has been presented which permits rapid
retrieval of a particular data object from the DMSS 40.
Further, both the hardware and software functionalities of the
major components of the DAVDS have been described.
Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative examples of the
different aspects of the invention. Thus, it will be apparent
to one skilled in the art that numerous modifications may be
made to the illustrative embodiments and other arrangements may
be devised to implement the invention which do not depart from
the spirit and scope of the invention. Such modifications and
arrangements are therefore intended to be embraced by the claims
. : . . . .
, , : . .
For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee and Payment History should be consulted.
|Forecasted Issue Date||Unavailable|
|(41) Open to Public Inspection||1990-04-25|
There is no abandonment history.
|Current Owners on Record|
|Past Owners on Record|
|FISCHER, JAMES L.|
|LODBERG, ALLAN E.|
|MCCALLEY, KARL W.|
|WILSON, STEVEN D.|