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Description  |
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FIELD OF THE INVENTION
The present invention relates to television and other video information,
and in particular to a novel method and apparatus for selectively viewing
television or other video signals.
BACKGROUND OF THE INVENTION
Television has become the world's predominant communications medium. The
variety of programming available on television has mushroomed in recent
years with the growth of cable networks. In many areas, a viewer can
select programming from among dozens of channels, broadcasting news, talk
shows, movies soap operas serials etc., from Geraldo Rivera to William F.
Buckley, from the banal to the sublime (or the reverse, depending on one's
point of view).
Although a large amount of information is broadcast via television, the
capability to selectively view television is primitive. Published
television listings typically contain a minimal amount of information
about the program to be shown, are often difficult to understand, and are
subject to frequent errors and changes. Furthermore, a certain amount of
television programming, such as a news broadcast, by its nature can not be
described in advance.
Most viewers would like greater control over what is being viewed. They
may, for example, wish to view specific portions of a news program or a
talk show dealing with a topic of interest. They may wish to monitor
multiple channels simultaneously. They may wish to screen out programming
they regard as offensive.
In theory, a viewer could record one or more television signals on one or
more recording devices, such as commonly available video cassette
recorders (VCRs), and review all recorded signals, editing such portions
as desired. In reality, this would be an extremely tedious and time
consuming task.
There has been some recognition of a need to provide a viewer width greater
control over what is being watched. For example, it is known in the art to
place a small window in one corner of the television display, in which is
shown the video signal of another broadcast channel, enabling the viewer
to screen one channel while simultaneously watching another. As helpful as
this feature is to the viewer, it is obviously limited in its
capabilities. Screening multiple channels would require a separate window
for each one. The screening must be done at the time the signal broadcast.
If something of interest is detected, the channel must be switched,
possibly foregoing programming of interest on the channel first being
viewed.
Television viewers have accepted this lack of ability to screen, preview or
extract portions of television programming only because no alternative has
been presented. However, a need exists for advanced capability on the part
of the viewer to selectively control what is viewed.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide am enhanced
method and apparatus for viewing video information.
Another object of this invention is to increase the ability of a user of
video information to control the content of the video presentation.
Another object of this invention is to provide an enhanced method and
apparatus for using televised information.
Another object of this invention is to increase the ability of a user of
video information to find and view desired information.
Another object of this invention is to increase the ability of a viewer of
televised information to locate information of interest from among a
plurality of channels and/or programs.
Another object of this invention is to increase the ability of a user of
video information to screen out material which the user considers
offensive or undesirable.
Another object of this invention is to provide and enhanced method and
apparatus for using information in a vertical blanking interval of a video
signal to find video matter of interest.
In accordance with the preferred embodiment of the present invention, the
information carried in the closed captioning portion of a television
signal is extracted and searched to find programming of interest to a
viewer. The viewer can then view an entire program segment or edit
segments.
A conventional television signal comprises video and audio components. The
video component of the signal is capable of carrying additional
information during a "vertical blanking interval". In particular, the
vertical blanking interval is used to carry closed captioning information,
which is a text stream. Typically, this closed captioning information is a
simplified version of the spoken words being transmitted by the audio
portion of the signal. While not a perfect representation of what is being
depicted by the television presentation, the closed captioning text will
generally contain words descriptive of a plot, news, or other information
being carried by the television signal.
A video presentation system in accordance with the preferred embodiment of
the present invention comprises a suitably programmed general purpose
digital computer, a television signal receiver/tuner, a closed captioned
text decoder, and a mass storage for storing television signals, which
could be s conventional video cassette recorder, a large direct access
storage device, or other data storage.
A television viewer inputs to the presentation system one or more key words
to be used as search parameters. These may be input simply as an unordered
set of words, or logical relations such as "AND", "OR", etc. may be
specified as known in the art of computer database searching. The computer
stores these key words and their required logical relationships. The
viewer also directs the presentation system to monitor specified channels
at specified times.
The television receiver/tuner receives television signals for the specified
channel or channels. The closed captioning portion of the television
signal is extracted by the closed captioning text decoder and converted to
a digital stream of textual data. The computer then scans the closed
captioning textual data stream extracted from the video signal for
occurrences of words matching its search parameters.
In a scan mode of operation, scanning is done while the television signal
is being received. When a match is found, the corresponding segment of the
television signal (video and audio portions) is saved in the mass storage
for later viewing. In other modes of operation, the system scans the
closed captioning stream of a pre-recorded signal for a match of the
search parameters.
What is done with a segment of interest once it has been located will
depend upon the desires of the viewer. The viewer may, for example,
specify the size of a segment, which could be a relatively short interval
(e.g., 15 seconds) before and after the occurrence of the search term, as
might be useful for a news broadcast, or could be a much longer interval
such as an entire 1/2 hour television program. The viewer may wish to
watch any segments which were found, or may wish to edit and save segments
for later viewing. The viewer may wish to edit out small segments of a
larger presentation, e.g., where the viewer finds such segments offensive.
The system may display to the user all or part of the extracted textual
data from the segments, and permit the user to select those segments to be
viewed and/or edited.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the major components of a video presentation
system according to the preferred embodiment of this invention;
FIG. 2 shows in greater detail the major components of the computer portion
of the video presentation system according to the preferred embodiment;
FIG. 3 shows in greater detail the structure of the video segment buffer
according to the preferred embodiment;
FIGS. 4A, 4B, 4C, 4D, and 4E show the format of scan profile data
structures according to the preferred and alternative embodiments;
FIG. 5 is an example of how a complete set of profile data structures would
be used to specify a typical scan for data of interest according to the
preferred and alternative embodiments;
FIG. 6 shows the high level flow of control of the control program
according to the preferred embodiment;
FIG. 7 shows the steps performed by control program 220 as part of the edit
profile function according to the preferred embodiment;
FIGS. 8A and 8B show the steps required to scan a received signal for items
of interest according to the preferred embodiment;
FIG. 9 shows the steps required to determine whether a sequence of words in
a log of closed captioning text matches the search parameters specified by
the profile data structures according to the preferred embodiment;
FIG. 10 shows the steps required to search and edit a signal according to
the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a block diagram of the major components of a video
presentation system according to the preferred embodiment of the present
invention. Video presentation system 100 comprises digitally controlled
receiver/tuner 101, signal splitter 102, closed captioning text decoder
103, general purpose digital computer system 104, mass storage 105, video
display 106 and audio speaker 107. Receiver/tuner 101 receives an analog
television signal from an external source, such as an antenna for
receiving atmospheric television transmissions, a coaxial transmission
cable from a cable television network, or a video cassette recorder.
Receiver/tuner 101 receives commands to tune in one or more channels from
computer 104 via control line 111. Receiver/tuner 101 demodulates the
signal received on a specified channel and outputs the demodulated signal
on line 112 to splitter 102. The signal is fed simultaneously from
splitter 102 into computer 104 and closed captioning text decoder 103 via
lines 113, 114. Closed captioning decoder 103 extracts a stream of textual
data from the video signal. This extracted stream is forwarded to computer
104 in digital format on serial digital line 115. Optional speech
recognition unit 130 may also be used to provide additional textual data
as explained with reference to an alternative embodiment.
Closed captioning decoder 103 is preferably a decoder constructed to
convert information contained in line 21 of the vertical blanking interval
of a television signal to a text stream. Normally, this information is a
modified representation of spoken text being carried in the audio portion
of the television signal, and is intended for use by hearing impaired
persons. Standards for such devices are specified in 47 C.F.R. 15.119,
herein incorporated by reference. Additional information relating to
closed captioning decoders is contained in Lentz et al., "Television
Captioning for the Deaf Signal and Display Specifications" (Public
Broadcasting Service, 1980), incorporated herein by reference as
additional background information.
In the preferred embodiment, receiver/tuner 101 is an IBM PS/2 TV. Computer
104 is an IBM PS/2 personal computer. It should be understood that other
hardware performing similar function could be used in place of that
specified here, in particular any of various commercially available video
function cards which plug into available slots of a personal computer.
FIG. 2 shows in greater detail the major components of completer portion
104 of video presentation system 100. Computer 104 comprises central
processing unit (CPU) 202, random access memory 203, mouse port controller
204, keyboard port controller 205, serial communications controller 206,
digital video capture 207, graphic display card 208, audio driver 209 and
storage controller 210, all coupled to bidirectional system communications
bus 201. Bus 201 facilitates communications, i.e. transfer of data, among
the various components of computer 104.
CPU 202 is a general purpose programmable processor such an an Intel 80486
processor commonly used in personal computers. Memory 203 is a random
access memory sufficiently large to hold the necessary programming and
buffer data. While memory 203 is shown as a single entity, it should be
understood that memory 203 may in fact comprise a plurality of modules,
and that memory may exist at multiple levels, from high-speed registers
and caches to lower speed but larger DRAM chips. As shown in FIG. 2,
memory 203 contains control program 220, data structures 221, and buffer
222. Control program comprises a plurality of machine instructions which
execute on processor 202 to perform video selection, scanning and editing
functions as described more fully herein. Data structures 221 comprise
data which direct and customize the operation of control program 220, such
as user time and channel selections, search parameters, locations of video
segments of interest, etc. Buffer 222 is used for temporary storage of
video signals or closed captioning data during scanning and editing by
control program 220.
Mouse port controller 204 and keyboard port controller 205 facilitate input
of data by the viewer from either a mouse or keyboard. In the preferred
embodiment, keyboard 120 attaches to PS/2 TV 101, and keyboard signals
pass through it. However, it is also possible to couple a keyboard
directly to keyboard port 205. Controllers 204 and 205 are illustrative of
the type of input controller commonly used for personal computers, it
being understood that it would be possible to use other forms of input
devices, such as joysticks, trackballs, infra-red hand-held remote control
units, or even speech recognition devices.
Serial communications controller 206 comprises a conventional universal
asynchronous receiver/transmitter (UART), for handling serial
communications with closed captioning decoder 103 over serial digital line
115. While controller 206 is capable of bidirectional communications, in
general it only receives digital data from decoder 103. However, it may be
used to transmit commands to decoder 103, e.g., to re-try a communication.
Digital video capture unit 207 is a circuit card and components which
receive analog video and audio signals over line 114 and convert theme
signals to a digital format suitable for storage and manipulation by
digital computer 104. In the preferred embodiment, digital video capture
unit 207 is an IBM ActionMedia II Display Adapter with ActionMedia II
capture option.
Graphic display card 208 transmits outgoing video signals to receiver/tuner
101 over line 116, and ultimately to video display screen 106. Display
card 208 receives digital signals on bus 201 and converts these to an RGB
analog format or composite video analog format, suitable for receiving by
display screen 106. Audio driver 209 simultaneously transmits the audio
component of the television signal to speaker 107.
Storage controller 210 communicates with mass storage device 105. In the
preferred embodiment, mass storage device 105 is an IBM PS/2 External Disk
Array Subsystem. Such a device comprises a plurality of rotating magnetic
disk drive storage devices, which are controlled by a single controller to
act as a single large storage entity. Mass storage device 105 functions
primarily as a buffer for storage of video and audio signals which have
been digitized by capture unit 207. Due to the large volume of storage
such digitized signals consume, a large external storage device is
preferably employed. While only one such unit is shown, it should be
understood that there may in fact be multiple mass storage devices, which
may be internal or external to computer 104. Typically, computer 104 will
include an internal disk drive of smaller capacity than the external disk
drive array subsystem 105, on which may be stored, e.g., programs required
for operation of computer 104 in accordance with the present invention or
other data. It should also be understood that other forms of mass storage
for video signals may be employed. In particular, it would be possible to
store analog video signals on one or more conventional video cassette
recorders.
FIG. 3 shows in greater detail the structure of buffer 222. Buffer 222 is
part of a larger general purpose RAM 203. A portion of RAM 203 is
allocated to buffer 222 upon initializing a certain functions as described
more fully herein. Buffer 222 is allocated in a plurality of segments
301-312, which may or may not be contiguous in RAM 203. Each buffer
segment is capable of holding a television signal segment from a short
time period in its respective data field 323. Each buffer segment 301-312
also contains a respective pointer field 321, containing a pointer to the
beginning of the next segment, and a respective save field 322, containing
a flag indicating whether the segment should be saved to storage. Segment
pointer 325 in data 221 points to current segment 305. Buffer 222 is
preferably arranged as a circular buffer. Segment pointer 325 is
"incremented" periodically as required to point to the next segment. After
the last segment is reached, the pointer is "incremented" to point to the
first segment again. As used herein, "incremented" refers to the fact that
the pointer is set to the next segment in the circular buffer; the actual
numerical address in the segment pointer may be increased or decreased.
While FIG. 3 shows a buffer having 12 segments, it should be understood
that the number and size of the segments may vary, and in particular that
control program 220 may dynamically vary the number and size of the
segments. The design and operation of such circular buffers is now in the
art of computer programming.
FIGS. 4A, 4B, 4C, 4D and 4E show the format of the scan profile data
structure which is used to record what type of television information the
viewer wishes to identify, and to govern the operation of control program
220. Each profile record includes one profile control block 401 as shown
in FIG. 4A. Profile control block 401 is the main profile record, and
contains pointers which point to subsidiary records. Profile control block
401 comprises title field 402, which contains a short title of the profile
for use in viewer identification. Description field 403 contains a longer
textual description of the subject of the profile. Interval field 404
determines the size of an interval to be saved and recorded. It specifies
the number of seconds of television signal to be saved and recorded before
and after encountering a match of the search parameters. Next profile
pointer field 405 and last profile pointer field 406 contain pointers to
the next and previous profile control blocks, respectively. It is expected
that the video presentation system of the present invention may store
multiple profiles, and that these would be stored as one or more circular
linked lists of variable length, as are known in the art of computer
programming. Time pointer field 407 contains a pointer to the first time
control block 410 to which the profile applies. Time control blocks 410
are maintained as a linked list of variable length, allowing a single
profile to specify multiple time periods during which channels should be
scanned for television of interest. Keyword pointer 408 contains a pointer
to the first OR-ed key word control block 430. Keywords are also
maintained as a variable length linked list, permitting multiple keywords
and combinations of AND-OR logic, as illustrated below in respect to FIG.
5.
The format of time block 410 is shown in FIG. 4B. Each time block 410
specifies a time period during which applicable channels should be scanned
for items of interest. Date or day field 411 specifies a date or day of
the week for the start of the scanning period. This may be specified
either as a single date, in which case the scan will be performed only
once, or as a day of the week, in which case the scan will be performed
every week at the same time. Date or day field 411 may also contain a
special code designating "Monday through Friday" or other common
combination of days, indicating that the scan is to be performed on all
such days. Start time field 412 specifies the time of day at which the
scan is to begin. Time end field 413 specifies the time at which the scan
ends. Next time pointer 414 contains a pointer to the next time control
block 410 in the list of time control blocks for the applicable profile. A
null value indicates that the end of the list has been reached. Channel
pointer 415 contains a pointer to the list of channels to be scanned.
The format of channel block 420 is shown in FIG. 4C. Channel block 420 is
used only if multiple channel scanning is supported. Where the system is
capable of scanning only one channel at a time, there is no need for a
pointer to a list of channels, and field 415 of time block 410 may instead
contain simply the single channel to be scanned. Where multiple channels
may be scanned, provision is made for a variable length list of channels.
Channel block 420 contains channel field 421, which identifies a channel
to be scanned, and next channel pointer field 422, which contains a
pointer to the next channel control block on the list. The final channel
block on the list contains a null pointer in field 422.
The formats of OR-ed keyword block 430 and AND-ed keyword block 440 are
shown in FIGS. 4D and 4E respectively. These blocks effectively specify
the search parameters to be used when scanning for television data of
interest. In accordance with the preferred embodiment, a user may specify
one or more disjunctions of conjunctions of keywords. I.e., a user may
specify a search of the form (WORD1 and WORD2) or (WORD3 and WORD4 and
WORD5) or (WORD6) or . . . The number of disjunctions is variable, as is
the number of conjunctions which make up each disjunction. OR-ed keyword
block 430 comprises next OR-ed pointer field 431, which points to the next
OR-ed keyword block of the disjunctive string; keyword 432 which contains
a keyword to be matched; and next AND-ed pointer field 433, which contains
a pointer to an AND-ed keyword block 440 which is part of the conjunctive
string. ANDed keyword block 440 comprises number words within field 441,
which specifies a maximum distance in terms of number of words between
words in a conjunctive string. I.e., the words of a conjunctive string
must be within a specified proximity of each other to create a true match.
ANDed keyword block 440 further comprises keyword field 442, which
specifies a keyword, and next ANDed pointer 443, which points to the next
ANDed keyword block 440 of the string. Nulls in pointer fields 431, 433,
443 indicate the last word of the string.
FIG. 5 is an example of how a complete set of profile data structures 401,
410, 420, 430, 440 would be used to specify a typical scan for data of
interest. In this example, the profile is established to scan for news
about the Minnesota Twins baseball team. It is desired to scan local
channels 3 and 10 during the periods of normal local newscasts on
weeknights, and to scan major network channels 4, 5 and 6 all weekend for
items about the Minnesota Twins.
In the example of FIG. 5, reference number 501 represents a profile control
block having the same structure as profile control block 401 shown in FIG.
4A. Reference numbers 510, 513 and 516 each represent a time block having
the same structure as time block 410 shown in FIG. 4B. Reference numbers
511, 512, 514, 515, 517, 518 and 519 each represent a channel block having
the same structure as channel block 420 shown in FIG. 4C. Reference
numbers 520 and 522 each represent an OR-ed keyword block having the same
structure as OR-ed keyword block 430 shown in FIG. 4D. Reference numbers
521 and 523 each represent an AND-ed keyword block having the same
structure as AND-ed keyword block 440 shown in FIG. 4E.
As noted earlier, the complete set of profile data for this scan contains
one profile control block 501. Title field 402 of block 501 contains the
title "Twins", and description field contains the string "MN Twins
Baseball News". These fields are useful in identifying the nature of the
profile. Next and Last profile pointer fields 405, 406 point to additional
profile control blocks (not shown) having the same structure as profile
control block 401, which are used to find unrelated items of interest.
Time block pointer field 407 points to the first time block 510 of a string
of time blocks. In this example, the first time block 510 is used to
specify the time period from 5:00 pm to 6:30 pm on weekdays. This time
period corresponds to the time for typical local newscasts. Channel
pointer field 415 of block 510 points to channel block 511. Channel field
421 of channel block 511 contains a channel (channel 10) to be scanned
during the time period specified by time block 510. Next channel pointer
field 422 points to channel block 512. This channel block contains a
different channel (channel 3) to be scanned during the same time period.
Next channel pointer field 422 of block 512 contains a null pointer,
indicating the end of the list of channels to be scanned at this time.
Thus, blocks 510, 511 and 512 together specify that channels 10 and 3
should be scanned every weekday from 5:00 pm to 6:30 pm.
Next time pointer field 414 of time block 513 specifies another time period
to be scanned. As in the case of time block 510 described above, time
block 513 points to channel block 514, which in turn points to block 515.
These collectively specify that channels 10 and 3 are to be scanned every
weekday from 10:00 pm to 10:30 pm. Although the strings of blocks starting
at 511 and 514 are shown separately in FIG. 5 for clarity, it should be
understood that they may in fact be a single string of channel blocks,
which is pointed to by both time blocks 510 and 513.
Next time pointer field 414 of time block 513 points to time block 516,
which specifies still another time period to be scanned. Block 516
specifies a scan on Saturday and Sunday, from 8:00 am to 11:00 pm. Next
time pointer field 414 of block 516 is null, indicating the end of the
string of time blocks 510, 513, and 516. Channel pointer field 415 of
block 516 points to channel block 517, which specifies channel 4. Channel
block 517 points to channel block 518, which in turn points to channel
block 519, specifying a list of three channels, channels 4, 5 and 6, to be
scanned during the time period specified by time block 516.
Keyword pointer field 408 of profile control block 501 points to the first
OR-ed keyword block 520. OR-ed keyword block 520 contains the keyword
"Minnesota" in keyword field 432, and contains a pointer to AND-ed keyword
block 521 in next AND-ed ptr field 433. AND-ed keyword block 521 contains
the keyword "Twins" in keyword field 442, and contains the number 2 in
field 441, specifying the maximum distance of the keywords. Next ANDed
pointer field 443 of block 521 is null, indicating the end of the string
of ANDed keywords. Blocks 520 and 521 together specify a search for the
keywords "Minnesota" and "Twins", and specify that these words must be
within two words of each other in a text string. Thus, the text "Siamese
twins were born at Lake Wobegone, Minnesota" would not satisfy the search
parameters specified by blocks 520 and 521 because the words "twins" and
"Minnesota" are more than two words apart in the string, whereas "The
Minnesota Twins lost to Kansas City last night" would satisfy the search
parameters.
Typically, closed captioning text is in all capital letters; the sample
text above is shown in mixed case for ease of understanding. However, even
if text is presented in mixed case, the search parameters are preferably
not case sensitive, i.e., search words match regardless of whether the
letters are upper or lower case.
Next OR-ed pointer field 431 of block 520 points to block 522, which
specifies another string of keywords. Block 522 contains the keyword
"Twins" in keyword field 432, and a pointer to AND-ed keyword block 523 in
field 433. AND-ed keyword block 523 contains the keyword "Baseball" in
field 442, and the keyword distance 30 in field 441. A null pointer in
field 443 of block 523 indicates the end of the conjunctive string. Blocks
522 and 523 collectively specify a search for the keywords "Twins" and
"Baseball", which must be located within 30 words of each other in a text
string. Next OR-ed pointer field 431 of block 522 is null, indicating the
end of the string of OR-ed keyword blocks (disjunctive string). In this
example, two separate and independent (disjunctive) conditions are
specified, the first by blocks 520-1, the second by blocks 522-3. If a
decoded closed captioned text string satisfies either condition, the
search parameters are said to be satisfied and appropriate action will be
taken to save or otherwise deal with the video interval in which the
string satisfying the search parameters was found, as more fully described
below.
The operation of the present invention in the preferred embodiment will now
be described. Control program 220 is the heart of the operation, and
controls computer 104 and other hardware shown in FIG. 1. Control program
220 comprises four basic functions, a set profile function, a capture
function, a scan function, and a review/edit function.
In order to perform certain functions, control program 220 requires
interactive input of the viewer. Video presentation system 100 preferably
displays prompts, lists of choices, and other required information on
display 106. Information in text form required for viewer selections may
be overlayed on any video picture being displayed on display 106,
permitting the viewer to interactively input information while a
television program is simultaneously being displayed on display 106.
Apparatus for overlaying such textual information is known in the art.
Alternatively, it would be possible to display such textual information on
display 106 by itself, without any other video picture, or in a window of
display 106 while a television program is being shown on the remainder of
the display, or on a separate special purpose display, such as a small
light emitting diode (LED) display.
FIG. 6 shows the high level flow of control of control program 220. Upon
power first being applied to video presentation system 100, control
program 220 enters idle mode at block 601. Control program 220 waits in
idle mode until the user demands attention, as for example, by pressing an
appropriate function key on keyboard 120, or a button on mouse 121 (block
602). Control program responds by displaying a menu of available choices
on display 106 or a special purpose display, as explained above, at block
603. The available choices are to edit a profile (block 610), to scan
incoming television signals in accordance with a profile (block 611), to
search and edit a stored video signal (block 612), and to capture and save
incoming television signals for later viewing and/or editing (blocks
620-23). The user may also choose to return to idle mode (block 613). The
user selects one of the available choices, and upon completion of the
selection, control program 220 either returns to idle mode or to the menu
of choices, as illustrated. The steps required to perform the edit
profile, scan, and search/edit video functions (blocks 610-612) are
explained in greater detail below with reference to FIGS. 7-10.
To perform the capture and save function, the video presentation system
must be instructed as to the time interval and channel(s) to be captured
and saved. When this option is selected, control program presents the
viewer with a list of available profiles to select at block 620. These
profiles specify channel(s) and time(s) for capture of the signal. The
viewer may optionally specify a channel and start and stop times, without
creating a profile. Upon receiving the viewer's selection, control program
220 waits at block 621 until the specified start time for video capture.
At the start time, control program 220 captures the video and text. I.e.,
it commands digital tuner 101 to tune the appropriate channel, and
instructs video capture unit 207 to receive and digitize the analog signal
from tuner 101 and send it directly to storage controller 210 via bus 201
to be stored in storage 105 (block 622). At the same time, decoder 103
decodes closed captioning data, which is received by serial UART 206 and
also stored directly in storage 105 (block 623). At the end of the
specified capture period, control program 220 returns to idle mode The
television signal thus digitized and stored can be later edited using the
search/edit function, or simply played back.
FIG. 7 shows the steps performed by control program 220 as part of the Edit
Profile function. The Edit Profile function allows a viewer to create or
alter a profile data structure. The profile data structure specifies such
things as channels and times to be monitored, size of capture windows, key
words used and search parameters and logical relationships between these
key words, etc., as explained above. When a viewer selects the set profile
function, e.g. by keyboard 120 or mouse input device 121, monitor program
220 displays a menu of available choices, which include to create a new
profile from scratch, to edit an existing profile, or to copy an existing
profile as a template for creating a new profile. If the user elects to
create a new profile from scratch, control program 220 prompts the user to
enter the new profile name at block 701. It then creates the new profile
data structures explained above and depicted in FIGS. 4A-4E, and enters
default values in the appropriate fields, at block 702. If the user elects
to edit an existing profile, control program 220 displays a list of
existing profiles and receives the user's selection at step 703. If the
user elects to copy an existing profile as a template, control program 220
displays the list of existing profiles and receives the user's selection
at step 704. It then creates new profile data structures as depicted in
FIGS. 4A-4E, and copies the values from the selected profile into the new
profile data structures, at step 705. Program 220 then prompts the user to
enter the name of the new profile, in order to distinguish it from the
profile from which it was copied, at step 706.
Upon completing the initial creation, selection or copying of a profile as
explained above, control program 220 displays the profile values at step
710. The user may then select any of various editing options. The user may
add an element (block 711), as for example adding a time period to be
scanned or adding a search word. The user may delete such an element
(block 712). The user may change such an element (block 713). Each time
the user adds, deletes or changes an element, control program returns to
block 710 to display the altered profile. The user may also delete an
entire profile, which would delete all associated data structures depicted
in FIGS. 4A-4E (block 714). When done editing, the user chooses to end the
editing function (block 715).
In accordance with the preferred embodiment, the video presentation system
can operate in automatic scan mode to automatically find and record
television signals of interest without a human operator's attendance
during signal reception. FIGS. 8A and 8B illustrate the operation of the
presentation system while in automatic scan mode. More particularly, FIGS.
8A and 8B illustrate the steps performed by control program 220 executing
on CPU 202 of computer 104.
Upon entering automatic scan mode, control program 220 performs necessary
initialization of data 221 and buffer 222 at step 801. Because buffer 222
is part of a larger general purpose RAM 203, initialization requires
allocation of a portion of RAM 203 to buffer 222. Buffer 222 will be
allocated in a plurality of segments 301-312, each buffer segment holding
a television signal segment from a short time period. This time period is
"short" in relation to human perceptions and viewing time. In relation to
the operation of a digital computer it must be sufficiently long to permit
computer 104 to perform the steps shown in FIGS. 8A and 8B. This time
period may, for example, be in the vicinity of 2 seconds. Segment pointer
325 is initialized to a first of such segments.
For monitoring and storing television signals in real time in accordance
with the preferred embodiment, the number and size of segments in buffer
222 must be sufficiently large that an interval of the specified size can
be captured. For example, if it is desired to capture an interval of
television signal beginning 15 seconds before closed captioning data
matching a set of search parameters is encountered, then buffer 222 must
be sufficiently large to hold 15 seconds of digitized television signal.
If each segment holds 2 seconds of televised signal, then buffer 222
should hold a minimum of 9 segments. One extra segment is needed to
account for the fact that control program 220 is analyzing a segment
previous to the one being currently recorded. Control program 220
allocates a buffer of appropriate size based on scanning parameters.
Alternatively, in certain applications it may be desirable to record much
larger intervals. For example, a viewer may wish to save an entire
half-hour program if a set of search parameters is satisfied anywhere
within the program. The set of search parameters may even require a count
of frequency of occurrence of some condition, so that the program should
be saved only if the condition is met a specified number of times. In this
case, computer 104 may be unable to determine that the television program
should be saved until the transmission is nearly finished. Because this
may require buffers of extremely large size, computer 104 could
alternatively save the entire television program in storage 105 while it
is being transmitted, analyze the closed captioning data as described
herein, and delete the program from storage 105 after transmission of the
program is complete if the specified conditions are not met.
After the buffer and data initialization functions have been performed,
control program 220 waits in a loop for the start time at step 802. The
start time, i.e., the time to begin receiving and monitoring a television
signal, is specified in a profile data structure Multiple profile data
structures may exist, each specifying a certain start time. While waiting
at step 802, the control program repeatedly compares the various start
times in the profile data structures with an internal clock. When the
internal clock reaches the first start time, the control program exits the
wait loop. If multiple profile data structures exist, control program 220
will periodically check whether the respective start time of each has
arrived and respond appropriately; for brevity of illustration, this is
not shown in FIG. 8A.
To start monitoring and capture of video signals, control program 220 sends
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