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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to computer systems and receiving broadcast
information. More particularly, this invention relates to caching video
and audio information and providing the cached information to end users in
an indexed manner.
2. Background
Video and audio broadcasts currently have a wide and varied audience. Such
broadcasts encompass a wide spectrum of information, including news
broadcasts, weather reports, soap operas, etc. This broadcast information
is typically made available to individual end users at a particular time,
and users simply choose whether they will watch the broadcast at that
time. Alternatively, an individual user may have a video cassette recorder
(VCR) which enables the user to record the broadcast in an analog format
and play it back at a later time.
One disadvantage to current video and audio broadcasts is that the end
users are limited to either watching the information as it is received, or
viewing it as recorded on a VCR. These methods force the end users to
consume the information sequentially in the order it is received. For
example, during a news broadcast, important headlines may be broadcast
first and a weather report may be broadcast sometime later. Therefore, in
order to watch the weather report, it is necessary for the end user to sit
through the intervening news. Thus, it would be beneficial to provide a
system which allows individual users to watch only those portions of the
broadcast which are of interest to them without requiring them to watch
the entire broadcast. The present invention provides such a system.
In addition, the advancement of computer technology has resulted in
computer systems being found on the desktops of a large number of
individuals in the work force. These individuals are often interested in
staying knowledgeable of current events, whether it be for personal or
business reasons. These individuals, however, are particularly
time-sensitive during the work day; that is, an individual at work
typically cannot take a few half-hour breaks during the day to watch live
news reports. Thus, it would be advantageous to provide a system which
allows an end user to view up-to-date news reports of interest to him or
her when it is convenient for him or her. The present invention provides
such a system.
Additionally, storing audio and video information requires a substantial
amount of storage space in a computer system. Therefore, it is difficult
to store multiple news reports in a computer system until such a time as
the user is able to search through them for the desired information.
Furthermore, locating a desired portion of audio and/or video information
may be very difficult, such as requiring sequentially scanning hours worth
of a VCR videotape or other storage medium. Thus, it would be beneficial
to provide a system which stores broadcast information in an efficient
manner, keeping only that portion of the information which is most
current. In addition, it would be beneficial to provide a system which
allows an individual to quickly and easily access the stored information.
The present invention provides for these and other advantageous results.
SUMMARY OF THE INVENTION
A method and apparatus for providing broadcast information with indexing is
described herein. A stream of broadcast information including multiple
video and audio information segments is generated and transferred to a
receiving device. Once receive, the segments are stored in a cache and
indexing information associated with the segments is made available to end
users of the apparatus. The end users are then able to select which
segment(s) they would like to receive, and the selected segment(s) is
transmitted to the requesting user(s).
In one embodiment, when a new segment is received, a determination is made
as to whether it is a more recent version of another segment already
stored by the apparatus. If it is a more recent version, then the older
version is overwritten by the newer version.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by way of example and not limitation
in the figures of the accompanying drawings, in which like references
indicate similar elements and in which:
FIG. 1 shows an overview of a broadcast information transmitting, receiving
and distribution system according to one embodiment of the present
invention;
FIG. 2 shows an example user-interface of the present invention;
FIG. 3 is a flowchart showing the steps followed in maintaining current
story segments in one embodiment of the present invention;
FIG. 4 is a flowchart showing the steps followed in providing broadcast
information to individual users in one embodiment of the present
invention; and
FIG. 5 shows an overview of an example multiple-processor computer system
which can be utilized in the present invention.
DETAILED DESCRIPTION
In the following detailed description numerous specific details are set
forth in order to provide a thorough understanding of the present
invention. However, it will be understood by those skilled in the art that
the present invention may be practiced without these specific details. In
other instances well known methods, procedures, components, and circuits
have not been described in detail so as not to obscure the present
invention.
Some portions of the detailed descriptions which follow are presented in
terms of algorithms and symbolic representations of operations on data
bits within a computer memory. These algorithmic descriptions and
representations are the means used by those skilled in the data processing
arts to most effectively convey the substance of their work to others
skilled in the art. An algorithm is here, and generally, conceived to be a
self-consistent sequence of steps leading to a desired result. The steps
are those requiring physical manipulations of physical quantities.
Usually, though not necessarily, these quantities take the form of
electrical or magnetic signals capable of being stored, transferred,
combined, compared, and otherwise manipulated. It has proven convenient at
times, principally for reasons of common usage, to refer to these signals
as bits, values, elements, symbols, characters, terms, numbers, or the
like. It should be borne in mind, however, that all of these and similar
terms are to be associated with the appropriate physical quantities and
are merely convenient labels applied to these quantities. Unless
specifically stated otherwise as apparent from the following discussions,
it is appreciated that throughout the present invention, discussions
utilizing terms such as "processing" or "computing" or "calculating" or
"determining" or the like, refer to the action and processes of a computer
system, or similar electronic computing device, that manipulates and
transforms data represented as physical (electronic) quantities within the
computer system's registers and memories into other data similarly
represented as physical quantities within the computer system memories or
registers or other such information storage, transmission or display
devices.
The present invention provides a system for individual users to access the
most recent version of multiple versions of broadcast information in an
indexed manner. Broadcast information refers to any type of audio data
and/or video image data which can be transmitted from a source unit to a
destination unit via any of a wide variety of communication media, such as
a television program broadcast. The descriptions below discuss this
broadcast information as news information, however it will be appreciated
that the present invention is not limited to a specific type of
information. Any type of broadcast information can be utilized by the
present invention.
FIG. 1 shows an overview of a broadcast information transmitting, receiving
and distribution system 100 according to one embodiment of the present
invention. Broadcast information originates at broadcast source 105.
Broadcast source 105 may be any of a wide variety of conventional signal
broadcasting devices, such as a satellite dish, a radio or television
transmitter, etc. Broadcast source 105 transmits the broadcast information
over a transmission medium 107 to broadcast receiver 110. Transmission
medium 107 represents any of a wide variety of conventional signal
transmission media. For example, transmission medium 107 may be a cable, a
fiber-optic cable, or may represent a nonphysical medium transmitting
electromagnetic signals in the electromagnetic spectrum. Transmission
medium 107 may also include any number of conventional routing or
repeating devices, such as satellites or electromagnetic signal repeaters.
The broadcast information from broadcast source 105 includes both the video
image and/or audio data being presented to the end users and various
control, indexing and text information. The generation and transmission of
video and audio information is well-known in the art and thus will not be
discussed further.
Broadcast receiver 110 receives the broadcast information transmitted by
broadcast source 105 and transfers it to capture device 115 and index data
capture device 112. Broadcast receiver 110 may be any of a wide variety of
conventional transmission receiving devices. Receiver 110 may be included
as part of a video cassette recorder (VCR), a television set, a computer
system, etc. The receipt of electromagnetic signals via a transmission
medium is well-known to those skilled in the art and thus will not be
discussed further.
When the broadcast information is a news broadcast, the video image and/or
audio data can be divided into several subject areas referred to as
program segments. Each of these programming segments then includes
multiple story segments. In one embodiment of the present invention, the
control information transmitted by broadcast source 105 includes indexing
information for each of these multiple program and story segments. In one
implementation, this indexing information includes, for each of the
program segments, a subject matter heading and a set of subject matter
keywords which describe key aspects of the program segment. For each of
the story segments, the indexing information includes: a title, the
program segment the story is associated with, and a set of subject matter
keywords which describe key aspects of the story segment.
In one embodiment, this indexing information is transmitted by broadcast
source 105 concurrently with the video and/or audio news broadcast. The
indexing information for the story segments can be generated in a wide
variety of manners. In one implementation, the control information is
generated by an individual at the broadcast source 105. The indexing
information is generated prior to transmission of the broadcast, such as
by entering text into a computer system. The indexing information is then
inserted into the broadcast stream when the individual indicates to do so,
such as by entering the proper command to the computer system.
Alternatively, the indexing information may be generated and input into the
broadcast stream automatically by the broadcast source 105. For example,
news broadcasts typically use a TelePrompTer which displays the text to be
read by the newscaster. This TelePrompTer can be a computer system with
the text to be read by the newscaster being input to the computer system
prior to broadcasting the news report. This text input into the
TelePrompTer computer system includes subject matter information which can
serve as the indexing information. When this subject matter information is
input into the TelePrompTer, an indication is made that this text is
indexing information which should be transmitted along with the video and
audio broadcast. Thus, whenever subject matter information is displayed on
the TelePrompTer for the newscaster to read, the indexing information is
also broadcast over the transmission medium 107.
Additional methods may also be utilized to obtain the indexing information.
For example, the indexing information may be generated by scanning closed
caption information. Alternatively, the indexing information may be
generated on the receiving end by scanning the received audio data
utilizing a speech recognition process, or by scanning the received video
data utilizing an image recognition process.
Broadcast receiver 110 transfers the received broadcast information to
index data capture device 112. Index data capture device 112 obtains the
indexing information from the broadcast information and discards the
remaining broadcast information. Index data capture device 112 includes
the necessary hardware and software to obtain-the indexing information
from the broadcast information, based on the method used by broadcast
source 105 to transmit the indexing information. The indexing information
is then transferred to cache manager 125, along with the remainder of the
broadcast information from capture device 115.
In one embodiment of the present invention, the control information,
including the indexing information, is transmitted by broadcast source 105
during a vertical blanking interval (VBI). The VBI refers to the time
required by the electron gun in a conventional television set (or similar
video display) to reset itself to the top of the television screen from
the bottom of the screen. That is, conventional video displays generate
their display by using an electron gun(s) to illuminate each line on the
television screen. The electron gun illuminates a single line at a time
and typically starts at the top of the screen, illuminates every other
line as it travels down the screen, then resets itself to the top of the
screen once it reaches the bottom. During this reset from the bottom of
the screen to the top of the screen, no lines of the screen are being
illuminated. This period of reset is referred to as the VBI.
Typically, the VBI is equivalent to twenty-one "lines" of the display. That
is, the time it takes for the electron gun to reset itself to the top of
the screen from the bottom of the screen is equivalent to the amount of
time it would take the electron gun to illuminate twenty-one lines on the
screen. During the VBI, no video data is transmitted by a broadcasting
device because the electron gun is not illuminating lines at that time.
Thus, control information can be transmitted during the VBI rather than
video and/or audio data without disrupting the video and/or audio
transmission. The VBI is twenty-one lines under National Television
Standards Committee (NTSC) and twenty-five lines under Phase Alternate
Line (PAL) broadcast standards currently utilized in most North American
and European countries, respectively.
Of the twenty-one lines of the VBI under NTSC, the first ten are typically
used by television broadcasters for control information necessary for
displaying the audio and video data. This control information includes,
for example, video synchronization, luminance, and chrominance signals. In
addition, some broadcasters utilize VBI line twenty-one for broadcasting
the text for closed captioning for the hearing impaired. Thus, up to
eleven lines of the VBI are available for transmitting the control
information of the present invention. Each one of these eleven lines is
capable of transferring 17,280 bits per second (bps) without error
correction, or 9600 bps with forward error correction, using current VBI
encoding techniques.
In one implementation of the present invention, the indexing information
associated with the broadcast information is transferred over line
fourteen of the VBI. It will be appreciated, however, that the indexing
information can be transferred over any one or several of the available
VBI lines. For example, expansion boards and devices for computer systems
are commercially available which can be coupled to a conventional computer
system and tuned to a particular one or several of the VBI lines, thereby
allowing the computer system to receive information from the VBI.
Thus, the present invention makes use of available bandwidth (that is, the
available VBI lines) in an already-existing network (that is,
electromagnetic spectrum and cable transmitters and receivers). Therefore,
transmitting the indexing information for the present invention does not
require additional physical networks (such as cables) or additional
bandwidth on already existing networks.
In an alternate embodiment of the present invention, indexing information
is generated at the receiving end based on the time rather than being
inserted at the transmission end. In this embodiment, index data capture
device 112 and cache manager 125, discussed in more detail below, "know"
the topic of a particular segment being broadcast based on the time it is
broadcast. For example, a repeating news transmission may transmit
sporting news for five minutes every half-hour starting at ten minutes
past the half-hour. Thus, index data capture device 112 and cache manager
125 "know" that all video and audio data received during that five-minute
span is sports related. Thus, a subject-matter index can be generated and
provided to the individual end users without transmitting any additional
indexing information.
In one implementation of this alternate embodiment, further indexing is
available via the closed caption information received. That is, specific
story subject headings within the subject matter heading can be generated
by scanning the closed caption information. For example, the closed
caption information could be scanned for all names of professional sports
teams, with each of these team names being presented to the end users as a
story subject heading.
Index data capture device 112 receives the broadcast information from
broadcast receiver 110 and obtains the indexing information from the
broadcast information. It will be appreciated that although index data
capture device 112 and capture device 115 are shown as separate units in
FIG. 1, both units may be part of the same physical device. The method
utilized by index data capture device 112 to obtain the indexing
information is dependent on the method utilized by broadcast source 105 to
transmit the indexing information. For example, index data capture device
112 may receive the indexing information from one of the VBI lines, or
alternatively, may utilize a video or speech recognition process or other
communications link to examine the broadcast information and obtain the
indexing information. Thus, for certain video and speech recognition
processes, index data capture device 112 converts the broadcast
information to digital form prior to performing the recognition. Upon
obtaining the indexing information, index data capture device 112
transfers the indexing information to cache manager 125 and deletes the
remainder of the received broadcast information.
Capture device 115 receives the broadcast information from broadcast
receiver 110. It will be appreciated that although capture device 115 and
broadcast receiver 110 are shown as separate units in FIG. 1, both units
may be part of the same physical device. Capture device 115 operates in a
conventional manner to convert video and audio data received in analog
form into a digital form which can be displayed on a display device of a
computer system. Broadcasts received in digital form require no such
conversion. In one embodiment, capture device 115 also compresses the
digital form of the video and audio data for storage. In one
implementation, capture device 115 utilizes Indeo.TM. IRV (ISDN Rate
Video) compression, available from Intel.RTM. Corporation of Santa Clara,
Calif., the corporate assignee of the present invention. Utilizing
Indeo.TM. IRV allows video and audio data to be stored in approximately
40-60 MB (megabytes) of storage space per thirty minutes of information.
In addition, Indeo.TM. IRV provides a fifteen frames per second playback
rate with a transfer rate of 300 kbps. However, any of a wide variety of
compression techniques may be utilized, such as Indeo.TM. HQV, MPEG, JPEG,
etc. It will be appreciated that the higher the bandwidth of network 135,
the higher the image resolution and/or frame rate which can be made
available to the end users. In one embodiment, broadcast receiver 110 and
capture device 115 operate to continuously receive and capture broadcast
information.
After compressing the video and audio data, capture device 115 transfers
the compressed digital information to cache manager 125 via network 120.
In one implementation, network 120 is a conventional 10 Mbps Ethernet
network used solely by capture device 115 to transfer the compressed
digital information to cache manager 125. In the embodiment shown, a
single cache manager 125 is coupled to network 120. Alternatively,
additional cache managers 125 may also be coupled to network 120, each of
which receives the compressed data transmitted by capture device 115.
Providing multiple cache managers 125 allows the capture device 115 to
transfer the compressed data to cache managers 125 serving multiple local
area networks (LANs).
In one implementation of the present invention, capture device 115 operates
in a pipelined manner to continuously process the received broadcast
information. That is, as soon as a block of data is received it is
converted to digital form (if necessary), compressed, and transferred to
cache manager 125. This block of data could be, for example, a single
frame of a sequence of frames or a display line. The end of a story
segment can be determined by receiving an end-of-segment signal from the
broadcast source 105, by the receipt of new segment indexing information,
by video and/or audio indications such as sudden volume changes, pauses,
or by scene changes. Alternatively, capture device 115 may operate on a
segment-by-segment basis to compress and transfer information. That is,
information received as part of a segment from broadcast receiver 110 is
stored temporarily in capture device 115 until the entire segment is
received. Once the entire segment is received, the segment is converted
(if necessary), compressed, and transferred to cache manager 125.
Cache manager 125 stores the compressed information received from capture
device 115 in cache 130. In one implementation, cache 130 is a
conventional high-speed magnetic disk drive having one gigabyte of storage
space and being capable of storing at least two hours of compressed video
and audio data. However, it will be appreciated that any of a wide variety
of conventional mass storage devices can be utilized as cache 130.
Alternatively, cache 130 may be an analog storage medium, such as a
videocassette, rather than a digital storage medium. If cache 130 is an
analog storage medium, then capture device 115 does not convert received
analog signals to a digital form (however received digital signals may be
converted to an analog form by capture device 115).
Cache manager 125 is also coupled to cache index 128 where cache manager
125 stores the indexing information, such as titles and keywords, for each
program and story segment of the video and audio data stored in cache 130.
Cache index 128 may be a volatile memory device, such as a random access
memory, or may be a nonvolatile storage device such as a magnetic disk
drive. It will be appreciated that although cache manager 125, cache index
128, and cache 130 are shown as separate units in FIG. 1, each of these
units may be part of a single physical device, such as a computer system
file server. In one implementation, index data capture device 112, capture
device 115, cache manager 125, cache index 128, and cache 130 are part of
the same computer system file server.
In one embodiment of the present invention, when a block of video and audio
data is received, such as a single frame of a sequence of frames, the time
of receipt is associated with the block by capture device 115. Similarly,
index data capture device 112 associates the time it receives the indexing
information with the indexing information itself. Thus, when the indexing
information and the block of video and audio data is transferred to cache
manager 125, cache manager 125 is able to correlate the indexing
information with the blocks of video and audio data via the time stamps of
each. Cache manager 125 continues to associate the received indexing
information with subsequent blocks of video and audio data until new
indexing information is received. Once a new segment of indexing
information is received, an indicator of each block of video and audio
data stored in cache 130 is stored with the indexing information in cache
index 128, and subsequent blocks of video and audio data are associated
with the new indexing information.
In addition, cache manager 125 keeps an indicator of which of the versions
of a particular program or story segment is the most recent, the next most
recent, etc. This indicator may be stored in cache index 128, or
alternatively, in a separate local storage device of cache manager 125
(such as a random access memory). In one implementation, this indicator is
updated as soon as a new version of the segment is received and stored in
cache 130. Thus, when an individual end user requests a particular segment
stored in cache 130, such as by the title or keywords, cache manager 125
is able to quickly retrieve the most recent version of the requested
information and return it to the user.
In one embodiment of the present invention, cache manager 125 updates the
indicator of a new version each time a new program segment and associated
story segments are retrieved. Alternatively, cache manager 125 may update
the indicator of a new version each time a new story segment is retrieved.
In one embodiment of the present invention, cache manager 125 also
maintains a list of which program segments in cache 130 are currently
being viewed (and/or listened to) by individual end users and a user
identifier of the client system 140 which the program segment is being
transferred to. Thus, cache manager 125 knows which versions of program
segments are being accessed at any given time. When a user requests a
particular program segment or a story segment within a particular program
segment, discussed in more detail below, the cache manager 125 stores a
user identifier, a program segment identifier for that particular segment,
and the starting time of the access.
In one embodiment, the broadcast information transmitted by broadcast
source 105 is a repeating news broadcast. For example, the broadcast
information may be Turner Broadcasting's CNN Headline news, which repeats
four program segments every thirty minutes (e.g., Headlines, Dollars and
Sense, Lifestyles, and Sports). Due to the repeating nature of such news
broadcasts, it is not necessary for cache 130 to store the entire day's
broadcasts. Thus, cache manager 125 removes the video and audio data
stored in cache 130 for broadcasts earlier in the day.
Cache manager 125 determines which earlier broadcasts should be removed by
establishing a predetermined number of broadcasts which will be kept in
cache 130. In one implementation, this predetermined number of broadcasts
is three (for example, the most recent ninety minutes of CNN Headline
news). By storing multiple broadcasts, cache manager 125 is able to update
cache 130 with the newest version of a program segment while end users are
viewing older versions of the segment. For example, end user A may start
watching a story segment. Before end user A completes viewing the segment,
the most recent version of that segment is received by cache manager 125
from capture device 115. Thus, cache manager 125 allows end user A to
finish watching the older version of the segment while storing the newer
version in cache 130. Once storage of the most recent version in cache 130
is complete, subsequent end users B, C, etc. requesting that segment will
be given the newer version. In one implementation, cache manager 125
overwrites one version of a program segment currently stored in cache 130
with the most recent version of that segment.
Note that previous program segments can be deleted in a wide variety of
manners. In one implementation, cache manager 125 removes an indicator of
the program segment from a list of indicators of segment versions
associated with a particular title. Alternatively, the new version may
actually overwrite the locations in the cache 130 where the older segment
was stored. It should be noted that although the above description
describes replacing segments in cache 130 on a program segment basis,
cache manager 125 may, alternatively, replace segments in cache 130 on a
story segment basis. That is, cache manager 125 operates as described
above, except that cache manager 125 replaces new versions of story
segments as they are received rather than waiting for the receipt of an
entire program segment.
In one embodiment of the present invention, once cache manager 125 receives
a request for a story or program segment from a user of client system 140,
the most recent version of that segment is "reserved" for that user. That
is, the most recent version of that segment at the time cache manager 125
receives the request is recorded in cache manager 125 as being viewed by
this user. Thus, if the user requests five different segments, each of
those five segments is reserved at the time the request is received.
Alternatively, cache manager 125 may temporarily store the request for
five segments, and reserve the most recent version of a requested segment
only when transfer of that segment to the client system 140 actually
begins.
It should be noted that certain situations could arise where all of the
prior newscasts are being viewed by individuals when a new version is
ready to be stored in cache 130. In one embodiment, cache manager 125
resolves this situation by automatically terminating delivery of the
oldest version to any individuals viewing the oldest version. The oldest
version is then overwritten by the new version, and cache manager 125
restarts transmission of the new version to the previously terminated
users. Alternatively, cache manager 125 may drop the newly received
segment and not store it in cache 130. Or, cache manager 125 may store the
most recent version in cache 130; then, once no end users are viewing one
of the older versions, that version not being viewed is deleted from cache
130.
In one embodiment, cache manager 125 continuously monitors the activity of
individuals requesting information. If an individual user remains inactive
for a predetermined period of time (in one implementation, ten minutes),
then cache manager 125 terminates transmission of that version of the
segment to that user. Cache manager 125 then provides the newest version
of that segment to that user. A user may be inactive, for example, by
starting to view a story segment, then pausing receipt of the story. Thus,
all versions of a story segment will generally not be in use (that is,
viewed) by users at any given time.
Cache manager 125 is coupled to multiple client computer systems 140 via
network 135. In one embodiment, network 135 is a LAN. In one
implementation, network 135 is a conventional 10 Mbps Ethernet network.
When an individual user of a client system 140 desires to view the news
stored in cache 130, the client system 140 transmits a request to cache
manager 125. Cache manager 125 returns a listing of the story segments
from cache index 128 about stories available from cache 130. Based on this
listing of segments, the individual user selects those that he or she
wishes to view. This may be done on a segment-by-segment basis, or may be
all the story segments within a particular subject area. Client system 140
then transmits this selection to cache manager 125, which retrieves the
selected segments from cache 130 and transfers the selected segments to
the client system 140 via network 135. Client system 140 then decompresses
the selected segments and displays them to the individual user.
In one embodiment, cache manager 125 supports periodic transmissions from
cache index 128 to the client systems 140. That is, each user of a client
system 140 can choose certain subject areas to be received periodically.
For example, users may request that news headline titles be received every
two hours. In this situation, cache manager 125 transmits the most recent
headline titles contained in cache index 128 over network 135 every two
hours, targeting those client systems 140 which requested the information.
It should be noted that although FIG. 1 is described in terms of multiple
computer systems coupled together via one or more networks, the present
invention is not limited to such a system. For example, the broadcast
receiver 110, index data capture device 112, capture device 115, cache
manager 125, cache index 128, and cache 130 may be included within a
single physical unit. This single unit could be, for example, a set-top
box coupled to a single television set in an individual user's home. The
television is analogous to a client system 140, and could include a
graphical user interface (GUI) or alphanumeric input device for inputting
requests for story segments. Thus, broadcast information would be
continuously received by the set-top box, and the most recent information
would be made available to the individual user at his or her request.
The user of a client system 140 may also search for particular news titles.
For example, the user may enter subject matter search terms, such as a
professional sports team name, to client system 140. In one embodiment,
the client system 140 transfers a request to cache manager 125 for titles
of all story segments which match the search criteria. The cache manager
125 searches in a conventional manner through the title information in
cache index 128, or alternatively through the keyword information,
associated with the most recent story segment versions stored in cache
130. The segments for any matches are then transferred to client system
140. In an alternate embodiment, cache manager 125 transfers all of the
titles and the keyword descriptions to client system 140 and client system
140 attempts to match the search criteria to the titles and/or keywords.
If any matches are found, then client system 140 sends a request to cache
manager 125 for the matched titles.
In one embodiment, cache manager 125 makes the titles of only the most
recent story segments available to the users of client systems 140. Thus,
once a new program segment is received by cache manager 125 and stored in
cache 130, only story segments of the new program segment are available
for subsequent requests for those titles within the new program (requests
for a title which are received by cache manager 125 prior to receipt of
the new program segment are given the most recent segment at the time the
request is received). Note that in this embodiment, a story segment could
be an hour old even if the broadcast repeats itself every thirty minutes.
This situation occurs, for example, when broadcast source 105 stops
broadcasting a particular story segment. In one implementation, cache
manager 125 keeps the story segment available to the client systems 140
for so long as the remaining segments which were broadcast in the same
thirty-minute span as that story segment are available. For example, if
three versions of the thirty-minute broadcast are kept in cache 130, then
once the title has been available for ninety minutes, cache manager 125
deletes it (assuming no user is currently viewing the segment).
In an alternate embodiment, cache manager 125 provides the titles of all
the story segments stored in cache index 128 and cache 130 to the users of
the client systems 140. Thus, in this alternate embodiment an individual
user is able to view the most recent available version of a segment, the
next most recent version of the segment, or the oldest version of the
segment, depending on how many versions are stored in cache index 128 and
cache 130.
FIG. 2 shows an example user-interface of the present invention. Interface
200 is displayed to the individual user by client system 140 of FIG. 1.
Interface 200 may be, for example, a display device coupled to the client
system 140, or a television set coupled to a set-top box.
Interface 200 includes an information display area 205, an index display
210, a storage interface 230, and a personalized newscast | | |
