U.S. patent application number 09/412839 was filed with the patent office on 2002-05-09 for trigger having a time attribute.
Invention is credited to BLACKKETTER, DEAN J., PARK, TIMOTHY F., ZIGMOND, DANIEL J..
Application Number | 20020056129 09/412839 |
Document ID | / |
Family ID | 23634715 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020056129 |
Kind Code |
A1 |
BLACKKETTER, DEAN J. ; et
al. |
May 9, 2002 |
TRIGGER HAVING A TIME ATTRIBUTE
Abstract
An interactive television trigger has a time attribute value
that indicates a future time when the trigger is to be executed. In
situations where the trigger cannot be sent to the receiver unit at
the desired time of trigger execution (for example, due to limited
available bandwidth of a communication channel to the receiver
unit), the trigger is sent prior to the future time. The receiver
unit then executes the trigger on the receiver unit at the future
time as indicated by the time attribute. The trigger can be sent
well before the future time so that a receiver unit that receives
the trigger can prefetch an information resource identified by the
trigger prior to the future time such that the information resource
is already available on the receiver unit when the trigger is later
executed at the future time. Multiple triggers identifying the same
information resource can be sent so that a receiver unit that does
not receive a trigger sent well before the future time (a trigger
intended to cause prefetching of the information resource) will
receive another trigger to the same information resource at or near
the future time. In another embodiment, the time attribute value
indicates a life span when the trigger is valid. If the trigger is
executed in the context of a first channel of video, and the viewer
switches channels to a second channel of video and then switches
channels back to the first channel of video, the trigger is
automatically reexecuted if the current time is within the life
span of the trigger as indicated by the time attribute.
Inventors: |
BLACKKETTER, DEAN J.; (SAN
FRANCISCO, CA) ; ZIGMOND, DANIEL J.; (CARNATION,
WA) ; PARK, TIMOTHY F.; (MENLO PARK, CA) |
Correspondence
Address: |
WORKMAN NYDEGGER & SEELEY
1000 EAGLE GATE TOWER
60 EAST SOUTH TEMPLE
SALT LAKE CITY
UT
84111
US
|
Family ID: |
23634715 |
Appl. No.: |
09/412839 |
Filed: |
October 5, 1999 |
Current U.S.
Class: |
725/112 ;
348/E5.096; 348/E7.031; 348/E7.071; 375/E7.024; 725/110;
725/51 |
Current CPC
Class: |
H04N 21/435 20130101;
H04N 21/8586 20130101; H04N 5/44 20130101; H04N 7/088 20130101;
H04N 21/235 20130101; H04N 21/8547 20130101; H04N 21/4782 20130101;
H04N 21/4331 20130101; H04N 7/17318 20130101; H04N 21/2393
20130101; H04N 21/4622 20130101; H04N 21/2665 20130101 |
Class at
Publication: |
725/112 ; 725/51;
725/110 |
International
Class: |
G06F 003/00; H04N
005/445; G06F 013/00; H04N 007/173 |
Claims
What is claimed is:
1. A method, comprising: a. receiving on a receiver unit a trigger
having a time attribute value, the time attribute value being
indicative of a future time; and b. waiting until the future time
and then executing the trigger on the receiver unit.
2. A method, comprising: a. receiving on a receiver unit broadcast
video and a trigger, the trigger having a time attribute value, the
time attribute value being indicative of a frame of video; and b.
waiting until the frame of video is received on the receiver unit
and then executing the trigger on the receiver unit.
3. The method of claim 2, wherein the broadcast video comprises a
plurality of frames of video, each frame containing a code, the
code having a time portion and a frame number portion, the receiver
unit monitoring the codes of successively received frames of the
broadcast video to identify the frame of video indicated by the
time attribute value.
4. The method of claim 2, wherein the broadcast video comprises a
plurality of frames of video, the receiver unit identifying the
frame of video indicated by the time attribute value by
incrementing a frame count when each successive frame of the
broadcast video is received onto the receiver unit, the frame of
video indicated by the time attribute value corresponding to a
particular frame count.
5. The method of claim 2, further comprising: before step (b),
obtaining content identified by the trigger from a packet-switched
network.
6. The method of claim 1, further comprising: c. before step (b),
obtaining content identified by the trigger from a packet-switched
network.
7. The method of claim 1, wherein the receiver unit maintains a
current time, the receiver unit determining when to execute the
trigger in step (b) by comparing the time attribute value to the
current time.
8. A method, comprising: a. receiving on a receiver unit a trigger
having a time attribute value, the time attribute value indicating
a period of time; and b. waiting the period of time and then
executing the trigger on the receiver unit.
9. The method of claim 8, wherein the receiver unit receives a
plurality of video frames, said frames being numbered with
successively increasing numbers, wherein the period of time
indicated by the time attribute value in step (a) is represented by
a number of frames, the receiver unit waiting the period of time in
step (b) by waiting for the number of frames to be received on the
receiver unit.
10. The method of claim 8, wherein the period of time indicated by
the time attribute value in step (a) is an amount of time, the
receiver unit waiting the period of time in step (b) by waiting for
the amount of time to pass.
11. The method of claim 8, further comprising: c. before executing
the trigger in step (b), obtaining content identified by the
trigger from a packet-switched network.
12. The method of claim 9, further comprising: c. before executing
the trigger in step (b), obtaining content identified by the
trigger from a packet-switched network.
13. A method, comprising: a. broadcasting a first trigger
indicative of an information resource, the first trigger having a
time attribute value, the time attribute value being indicative of
a future time; b. receiving the first trigger on a first receiver
unit, the first receiver unit retrieving the information resource
from a packet-switched network prior to the future time; c. after
steps (a) and (b), broadcasting a second trigger indicative of the
same information resource; d. receiving the second trigger on a
second receiver unit but not receiving the first trigger on the
second receiver unit, the second receiver unit retrieving the
information resource from the packet-switched network; and e.
executing the first trigger on the first receiver unit at the
future time, and executing the second trigger on the second
receiver unit at the future time.
14. A method, comprising: a. receiving and displaying on a receiver
unit a first channel of video; b. receiving a trigger having a time
attribute value, the time attribute value indicating a life span
during which the trigger is valid; c. executing the trigger in the
context of the first channel of video so that an enhancement is
displayed on the receiver unit along with the first channel of
video; d. on the receiver unit, switching channels from receiving
and displaying video from the first channel of video to receiving
and displaying video from a second channel of video; e. after step
(d), switching channels back so the receiver unit is receiving and
displaying video from the first channel of video; and f. during the
life span, automatically reexecuting the trigger upon switching
channels back in step (e) so that the enhancement is displayed on
the receiver unit along with the first channel of video.
15. A method, comprising: a. broadcasting information and an
associated trigger to a receiver unit, the trigger having a time
attribute value indicating a life span, the information being
broadcast during the life span; and b. after expiration of the life
span, rebroadcasting the information and the trigger to the
receiver unit.
16. The method of claim 15, further comprising: c. after step (a)
and before step (b), receiving the broadcast information and the
associated trigger on the receiver unit and executing the trigger
on the receiver unit; and d. after step (b), receiving the
rebroadcast information and the associated trigger on the receiver
unit and ignoring the trigger on the receiver unit.
17. A computer-readable medium having computer-executable
instructions for performing the steps of: a. on a receiver unit,
receiving a trigger having a time attribute value, the time
attribute value being indicative of a future time; and b. waiting
until the future time and then executing the trigger on the
receiver unit.
18. The computer-readable medium of claim 17, wherein the
computer-readable medium is a semiconductor memory.
19. The computer-readable medium of claim 17, wherein the time
attribute value indicates the future time by indicating a
wall-clock time.
20. The computer-readable medium of claim 17, wherein the time
attribute value indicates the future time by indicating a media
time base time.
21. The computer-readable medium of claim 17, wherein the time
attribute value indicates the future time by indicating an absolute
time.
22. The computer-readable medium of claim 17, wherein the time
attribute value indicates the future time by indicating a relative
time.
23. The computer-readable medium of claim 17, wherein the time
attribute value indicates the future time by indicating a frame of
video.
24. A computer-readable medium having computer-executable
instructions for performing the steps of: a. receiving a trigger
having a time attribute value, the time attribute value being
indicative of a future time, the trigger having an identifier that
identifies an information resource; b. using the identifier to
retrieve the information resource from a remote information store;
and c. after step (b), waiting until the future time and then
executing the trigger.
25. The computer-readable medium of claim 24, wherein the
identifier is a Uniform Resource Identifier (URI), and wherein the
remote information store is a server on a packet-switched
network.
26. A computer-readable medium having computer-executable
instructions for performing the steps of: a. receiving and
displaying a first channel of video on a receiver unit; b.
receiving a trigger associated with the first channel of video, the
trigger having a time attribute value, the time attribute value
indicating a life span; c. switching channels so that a second
channel of video is received and displayed on the receiver unit;
and d. after step (c), switching channels back so that the first
channel of video is received and displayed on the receiver unit,
the trigger being automatically reexecuted upon switching back.
27. The computer-readable medium of claim 26, wherein execution of
the trigger in step (b) results in an enhancement being displayed
on the receiver unit along with video from the first channel of
video, and wherein the enhancement is not displayed when the second
channel of video is displayed in step (c), and wherein the
enhancement is displayed again when the trigger is automatically
reexecuted.
Description
BACKGROUND INFORMATION
[0001] FIG. 1 (Prior Art) is a simplified diagram of an interactive
television system 100. System 100 includes a receiver unit 101, a
receiving antenna 111, and a remote control unit 102. A viewer uses
the remote control unit 102 to control the receiver unit 101 and/or
to interact with interactive television content via the receiver
unit 101. A video link 103 couples receiver unit 101 to an ordinary
analog television set 104 so that the receiver unit can use the
screen of the television set as a display device. The receiver unit
101 receives broadcast television video 105 on receiving antenna
111 and displays it as television video 106 on the screen of the
television set 104.
[0002] In interactive television, information 107 from an
information resource 108 is displayed along with television video
106 in a synchronized fashion. When the information 107 is to be
displayed at a particular point in the television video, a
communication called a "trigger" 109 is broadcast along with the
television video 105 and is received on receiving antenna 111.
Trigger 109 includes a Uniform Resource Identifier (URI) that
identifies the information resource 108. Receiver unit 101 uses
this URI to retrieve the information resource 108 from the Internet
110. Receiver unit 101 then displays the information 107 from the
information resource 108 along with the television video 106 to
provide an enhanced television viewing experience.
[0003] Each frame of the television video 106 includes two fields
of 262.5 horizontal scan lines each in accordance with the National
Television Standards Committee (NTSC) broadcast television format
standard. The first twenty-one scan lines of each frame are
commonly referred to as the "vertical blanking interval" (VBI
lines). This interval is used to synchronize television receiver
electronics and to return the electron beam of the television to
the top of the screen among other things. The electron beam is
therefore disabled (i.e. "blanked") during the scan time of the
first twenty-one scan lines so that the electron beam does not
scribe a visible line from the bottom of the screen to the top of
the screen when it is being returned to the top of the screen. The
entire vertical blanking interval is, however, generally not
required for vertical synchronization and vertical beam retrace.
Only VBI lines 1-9 of a field are generally required. The other
twelve lines 10-21 of the field are therefore available for the
communication of other information.
[0004] VBI line 21, for example, provides a low speed communication
sub-channel. The Federal Communications Commission (FCC) mandates
that part of this sub-channel be reserved for closed captioning
services as specified by EIA-608. Text subtitles are encoded into
this VBI line 21 sub-channel such that a television receiver that
receives the signal can decode the information encoded into VBI
line 21 and display it as a text subtitle along with the television
video to assist the hearing impaired. Spare bandwidth available in
this VBI line 21 sub-channel after the encoding of the closed
captioning information may be used to transport the interactive
television triggers such as trigger 109 to the receiver unit 101 at
an appropriate time with respect to the broadcast television video
105.
[0005] FIG. 2 illustrates a problem associated with the use of the
VBI line 21 sub-channel for the transport of trigger 109. Trigger
109 is desired to be transmitted to receiver unit 101 at time 200
with respect to broadcast television video 105. There is in this
example, however, particularly heavy closed captioning use of the
VBI line 21 sub-channel during period 201. Accordingly, there is
not adequate bandwidth left for the communication of the trigger
109 at time 200.
[0006] A conventional method of solving this problem involves
sending the trigger 109 beforehand (out of synchronization) with
respect the point in the associated broadcast television video 105
where the trigger 109 is to be executed. In the example
illustrated, trigger 109 is sent via the VBI line 21 sub-channel at
time 202 before period 201. Receiver unit 101, rather than
executing trigger 109 immediately upon receipt, executes a script
on the information resource 108 to which the trigger 109 is
addressed. The script involves a delay loop that delays the
execution of trigger 109 until time 200.
[0007] The use of such a delay loop, however, introduces several
complexities. The magnitude of the delay of such a delay loop is
generally somewhat unrepeatable and difficult to control. The
magnitude of the delay may, for example, vary from receiver unit to
receiver unit due to hardware differences. The magnitude of the
delay may also be affected by the particular software processes
running on a receiver unit. Moreover, the coding required to
realize such a delay loop involves effort on the part of the author
of the interactive content and this is undesirable. Solutions to
one or more of these problems are desired.
[0008] Moreover, in a current interactive television
implementation, if trigger 109 executes in the context of a
channel, and the viewer then changes channels to a different
channel, and the viewer then changes channels back, the trigger is
not reexecuted automatically. If, for example, trigger 109
initially caused stock ticker tape information 107 to be displayed
along with video of a given channel, and if the viewer switched
channels and then switched back, the stock ticker tape information
107 would not reappear because its trigger 109 would not
automatically be reexecuted. A solution to this problem is also
desired.
SUMMARY
[0009] In a first aspect of the invention, a trigger includes a
time attribute indicative of a time in the future when the trigger
is to be executed. Providing a time in the future when the trigger
is to be executed allows the trigger to be sent in advance when
there is adequate transport bandwidth to transport the trigger to
the receiver unit. The receiver unit receives the trigger but knows
from the future time attribute that the trigger is not to be
executed yet, but rather is to be executed at the indicated future
time. The receiver unit therefore waits until the indicated future
time to execute the trigger. This future time attribute therefore
eliminates the need for the script and delay loop described
above.
[0010] In a second aspect of the invention, a trigger includes a
time attribute indicative of a particular frame when the trigger is
to be executed. In one embodiment, each frame of video is numbered
with a frame number that is embedded in the video in accordance
with a standard. The receiver unit monitors these frame numbers (or
otherwise keeps track of the number of the current frame) and waits
to execute the trigger until the frame identified by the time
attribute of the trigger has been received. This future time
attribute therefore eliminates the need for the script and delay
loop described above.
[0011] In a third aspect of the invention, a receiver unit receives
a trigger with an attribute indicating that the trigger is to be
executed at some time in the future or some frame in the future.
The receiver unit determines whether the receiver unit has enough
time to retrieve an information resource identified by the trigger
(this may involve establishing a connection to the Internet and
retrieving the information resource from the Internet). If the
receiver unit determines that there is enough time, then the
receiver unit prefetches the information resource so that it is
available at the future time or future frame when the trigger is to
be executed. Triggers are therefore sent well before they are to be
executed so that receiver units will prefetch associated
information resources. Such prefetching is used in some embodiments
to have receiver units access the Internet at off-peak (low cost)
times and retrieve information resources needed for subsequent
interactive television viewing [at peak (high cost) times].
[0012] In a fourth aspect of the invention, multiple triggers to
the same associated information resource on the Internet are all
sent indicating the same future time or future frame for execution
so that if a receiver unit for some reason does not receive the
earlier triggers (the earlier triggers are provided to cause the
receiver unit to prefetch the associated information resource),
then the receiver unit will at least receive the last trigger and
be able to execute it (this will generally require prompt retrieval
of the associated information resource from the Internet).
[0013] In a fifth aspect of the invention, a trigger has a time
attribute which provides a time up until which the trigger is valid
for presentation (i.e., a "life span" for the trigger). Providing
the life span time attribute allows a trigger to be executed in the
context of a channel, allows the viewer to change channels and then
change back, and allows the receiver unit automatically to
reexecute the trigger if it is still valid (has not expired).
[0014] Future times of trigger execution, life span starting times
and/or life span ending times can be expressed using multiple
different characters and codes. Such times can be designated as
absolute times and/or as relative times. Such times can be
designated in terms of wall-clock time and/or media time base time.
A receiver unit need not receive media encoded with time stamps in
order to support media time base time attribute values, rather the
receiver unit can keep track of the media time base by monitoring
the progress of the media (for example, by maintaining a count of
successive frames of video media as successive frames of the video
media are received).
[0015] Triggers with time attributes can synchronize events with
respect to information other than video. Triggers with time
attributes can, for example, synchronize events with respect to
audio. Such triggers can, for example, be transmitted via radio
transmission along with audio information so as to synchronize
events with respect to the audio as it is received by radio
receiver units and/or to cause retrieval of information or
prefetching of information by radio receiver units.
[0016] Other aspects of the invention and other embodiments are
described in the detailed description below. This summary does not
purport to define the invention. The invention is defined by the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 (Prior Art) is a simplified diagram of an interactive
television system 100.
[0018] FIG. 2 (Prior Art) illustrates a problem that may be
encountered when transmitting triggers to interactive television
system 100.
[0019] FIG. 3 is a flowchart of a method wherein a trigger has a
time attribute value.
[0020] FIGS. 4, 5 and 6 illustrate diagrams of examples of triggers
that have time attribute values and that are usable in the method
of FIG. 3.
[0021] FIG. 7 is a flowchart of a method wherein a time attribute
value indicates a future time by identifying a future frame of
video.
[0022] FIGS. 8 and 9 illustrate examples of triggers that have time
attribute values that identify future frames of video and are
usable in the method of FIG. 7.
[0023] FIG. 10 is a flowchart of a method wherein a trigger having
a time attribute value is transmitted well before it is to be
executed so that a receiver unit can prefetch an information
resource identified by the trigger before the trigger is
executed.
[0024] FIG. 11 is a diagram illustrating the method of FIG. 10.
[0025] FIG. 12 illustrates an embodiment of the invention wherein a
trigger has a time attribute value that indicates a life span for
the trigger.
[0026] FIG. 13 is a flowchart of a method in accordance with the
embodiment of FIG. 12.
[0027] FIG. 14 illustrates an example of a time attribute value
that indicates a life span of the trigger of FIG. 12.
[0028] FIG. 15 is a diagram of a time attribute value that
indicates a life span of a trigger where the life span starts when
the trigger is received.
[0029] FIG. 16 is a simplified diagram illustrating the life span
specified by the time attribute value of FIG. 15.
[0030] FIGS. 17, 18, 19 and 20 illustrate other examples of time
attribute values that indicate life spans.
DETAILED DESCRIPTION
[0031] FIG. 3 is a flowchart of a method in accordance with one
embodiment wherein a trigger (for example, trigger 400 in FIG. 4)
has a time attribute value. The time attribute value is indicative
of a future time. In a first step (step 300), the trigger having
the time attribute is received on a receiver unit. In one
embodiment, the receiver unit is a WebTV.RTM. set-top Internet
Terminal as described in the following documents: U.S. patent
application Ser. No. 09/099,118, entitled "Communicating Logic
Addresses Of Resources In A Data Service Channel Of A Video
Signal", filed Jun. 17, 1998, by Daniel J. Zigmond, et al.; U.S.
patent application Ser. No. 09/295,746, entitled "Enabling And/Or
Disabling Selected Types Of Broadcast Triggers", filed Apr. 20,
1999, by Park, et al.; and U.S. patent application Ser. No.
09/295,436, entitled "Receiving An Information Resource From The
Internet If It Is Not Received From A Broadcast Channel", filed
Apr. 20, 1999, by Zigmond, et al. (the content of these documents
is incorporated herein by reference). The receiver unit may involve
a television and Internet Terminal that are integrated together to
constitute a single device. The receiver unit may also involve
another type of receiver unit including a personal computer having
a television tuner card such as the "Windows.RTM. 98 Broadcast PC"
system. In some embodiments, the receiver unit includes a cable
modem that couples the receiver unit to a cable (for example, a
coaxial cable or a fiber optic cable).
[0032] The receiver unit determines the future time from the time
attribute and waits (step 301) until the indicated future time. At
the indicated future time, the receiver unit executes the trigger.
Because the receiver unit determines the future time from the time
attribute, the delay loops used to delay the execution of triggers
described above are not needed.
[0033] FIG. 4 is a diagram of an example of a trigger 400 usable in
the method of FIG. 3. Trigger 400 includes a Uniform Resource
Identifier (URI) 401, a script 402, a time attribute value 403
indicative of the future time, a version number 404 and a checksum
405. The general format of trigger 400 and methods of transporting
trigger 400 to the receiver unit are set forth in: 1) Electronic
Industries Association standard EIA-746A, and 2) Advanced
Television Enhancement Forum Specification (ATVEF) Draft Version
1.1, revision 26 (the subject matter of these two documents is
incorporated herein by reference).
[0034] The general format of dates in trigger 400 is set forth in
International Organization for Standardization standard ISO-8601
(the subject matter of which is incorporated herein by reference).
The YYYY digits of the time attribute value 403 indicate the year
of the future time; the MM digits indicate the month; and the DD
digits indicate the day. The "T" in the time attribute value 403
after the date indicates that the value 403 indicates a wall-clock
date and time (as opposed to a media time base time). The HH digits
in the time attribute value 403 indicate the hour of the future
time; the MM digits indicate the month; the SS digits indicate the
second; and the PP digits indicate the fraction of the second. The
precision of fractional seconds is arbitrary. In this example, each
second is broken into sixty parts. The values for PP in this
example therefore range from 00 to 59.
[0035] The receiver unit maintains an indication of the current
date and time (i.e., the current wall-clock time). The receiver
unit may, for example, involve a real-time clock in either software
or hardware that maintains the current date and time. In addition,
or in the alternative, the current date and time can be
periodically broadcasted to the receiver unit via a suitable
mechanism. There are, for example, mechanisms for broadcasting time
on XDS in analog television and there are other mechanisms for
broadcasting time in digital television. These mechanisms can be
used to communicate the current date and time to the receiver
unit.
[0036] When the current wall-clock date and time as maintained by
the receiver unit matches the future date and time indicated by the
time attribute value 403, then the receiver unit executes the
trigger 400. In the illustrated example, execution of the trigger
involves execution of script "BOOM( )". Version number 404
indicates an ATVEF trigger standard version number with which
trigger 400 comports.
[0037] FIG. 5 is a diagram of another example of a trigger 500
usable in the method of FIG. 3. Trigger 500 includes a URI 501, a
name attribute value 502, a time attribute value 503, a version
number 504 and a checksum 505. The "T" indicates that the time
attribute value 503 indicates a time in terms of wall-clock time as
opposed to a time in terms of a media time base such as a number of
frames. In the example of FIG. 5, there is no date before the "T"
so value 503 indicates the next occurrence of the time. The "+" in
the time attribute value 503 means that the value 503 indicates a
relative time (a relative time between the current wall-clock time
and the future time when the trigger is to execute). Trigger 500 is
therefore to be executed an "HH:MM:SS.PP" amount of time after the
time when the trigger was received (i.e., from the current
wall-clock time when the trigger was received). The receiver unit
determines the passage of "HH:MM:SS.PP" using wall-clock time
rather than using a media time base. At the future time, the name
attribute 502 causes the name "OSCAR" to be displayed to the
viewer.
[0038] FIG. 6 is a diagram of another example of a trigger 600
usable in the method of FIG. 2. Trigger 600 has a URI 601, a script
602, a time attribute 603, a version number 604, and a checksum
605. The time attribute does not, however, contain a date. Trigger
600 executes on the next occurrence of time "HH:MM:SS". The "T"
indicates that the time "HH:MM:SS" is a wall-clock time as opposed
to a media based time. In this example, time attribute value 603
does not contain a "PP" to designate a fraction of the second.
[0039] FIG. 7 is a flowchart of a method in accordance with another
embodiment wherein the future time indicated by the time attribute
value of the trigger is indicated in terms of a media time base. In
a first step (step 700), a trigger (for example, trigger 800 of
FIG. 8) having a time attribute value is received on a receiver
unit. The time attribute value indicates of a future frame of
video.
[0040] Rather than immediately executing the trigger, the receiver
unit waits (step 701) until the future frame indicated by the time
attribute value has been received. When the future frame is
received on the receiver unit, then the receiver unit executes the
trigger (step 702).
[0041] FIG. 8 is a diagram of one example of a trigger 800 usable
in the method of FIG. 7. Trigger 800 includes a URI 801, a name
attribute 802, a time attribute value 803, a version number 804 and
a checksum 805. Each frame of video in this example is encoded with
a frame number such that each successive individual frame of video
within a second has a frame number one integer larger than the
previous frame. There are about thirty frames of video each second
in an National Television Standards Committee (NTSC) video signal.
NTSC video frames are therefore numbered successively from 00 to 29
each second in accordance with the ______ (SMPTE) 12M standard. The
"C" in the time attribute 803 indicates that the value
"HH:MM:SS:FF" indicates a future time in terms of a media time base
(in this case, time attribute 803 identifies a particular frame)
rather than in terms of wall-clock time. The "HH" digits indicate
the hour of the frame; the "MM" digits indicate the minute of the
frame; the "SS" digits indicate the second of the frame; and the
"FF" digits indicate the number of the frame within the second. If
the character 806 is a colon as it is in this example, then the
time attribute value 803 is a drop frame code, whereas if character
806 is a semi-colon, then the time attribute value 803 is a
non-drop frame code.
[0042] The time attribute value 803 in the example of FIG. 8
indicates the future time by referencing the frame number of a
particular frame of video that will be received in the future.
Generally the frames of a segment of video are numbered starting at
"00:00:00:00". The receiver unit monitors the numbers of
successively received video frames. When the receiver unit receives
the frame indicated by the time attribute value 803, then the
receiver unit executes the trigger 800. In the illustrated example,
the name attribute 802 causes the name OSCAR to be displayed on the
receiver unit. Version number 804 indicates an ATVEF trigger
standard version number with which trigger 800 comports.
[0043] FIG. 9 is a diagram of another example of a trigger 900
usable in the method of FIG. 7. Trigger 900 is similar to trigger
800 of FIG. 8 in that the time attribute value identifies a future
time in terms of media time base time as opposed to wall-clock
time. Trigger 900 has a "+" indicating that the value of the time
attribute is a relative value. Accordingly, trigger 900 is to be
executed "HH:MM:SS:FF" frames from the current frame (the frame
when trigger 900 was received on the receiver unit).
[0044] FIG. 10 is a flowchart of a method in accordance with
another embodiment. FIG. 11 is a diagram illustrating the method of
FIG. 10. In this embodiment, a trigger 1100 that is to execute at a
future time 1101 is sent early so that the receiver unit prefetches
an information resource identified in the trigger. In a first step
(step 1000), the trigger 1100 having a time attribute value is
received on a receiver unit. The time attribute value indicates the
future time 1101 when the trigger 1100 is to be executed. The
trigger 1100 also identifies an information resource that should be
available on the receiver unit when the trigger is executed. An
example of such an information resources is web page content that
is to be displayed on the receiver unit along with television video
when the trigger is executed.
[0045] Next (step 1001), if there is enough time before future time
1101 for the receiver unit to retrieve the information resource
from a remote information store (for example, from a server on the
Internet), then the receiver unit retrieves (i.e. prefetches) the
information resource from the remote information store. This
prefetching occurs in FIG. 11 during time period 1102. Trigger 1100
in some embodiments has a URI that identifies the information
resource on the Internet.
[0046] Once the information resource has been retrieved from the
remote information store, then trigger 1100 is executed (step 1002)
at future time 1101 indicated by the time attribute value of
trigger 1100. In this way, receipt of trigger 1100 by the receiver
unit causes the receiver unit to prefetch the information resource
needed to execute the trigger so that the information resource is
present on the receiver unit at future time 1101 when trigger 1100
is executed. This prefetching avoids the need to retrieve the
information resource at the future time.
[0047] A time attribute value can be used to facilitate the
prefetching of information by a relay station (such as a satellite
uplink station) for subsequent insertion of the information into a
signal being relayed by the relay station to receiver units. In
some embodiments, only a selected type of information (for example,
disconnected content) is prefetched and inserted as set forth in
U.S. patent application Ser. No. 09/345,247, Attorney Docket Number
MS-137851.1, entitled "Interactive Television Triggers Having
Connected Content/Disconnected Content Attribute", filed Jun. 30,
1999, by Leak, et al. (the subject matter of which is incorporated
herein by reference). A trigger filter such as described in U.S.
patent application Ser. No. 09/295,746, Attorney Docket Number
MS-131721.1, entitled "Enabling And/Or Disabling Selected Types Of
Broadcast Triggers", filed Apr. 20, 1999, by Park, et al. can be
employed to distinguish the selected type of trigger from other
types of triggers (the subject matter of this application is
incorporated herein by reference).
[0048] FIG. 11 also illustrates another embodiment in accordance
with the present invention. Broadcasting trigger 1100 (hereinafter
referred to as the first trigger) well before the future time 1101
when it is to be executed allows the prefetching of the associated
information resource during time period 1102 as described above. If
only first trigger 1100 were broadcast, however, then a receiver
unit that was not receiving triggers during time period 1103 (for
example, a receiver unit that was turned off during time period
1103 and was turned on at time 1104) would not receive the first
trigger 1100. A viewer could be watching interactive television on
the receiver unit after time 1104, but the enhancement that should
have been provided by executing trigger 1100 would not be available
as it should because trigger 1100 would not have been received.
[0049] In accordance with one embodiment of the invention, a second
trigger 1105 for the same enhancement as first trigger 1100 is
broadcast slightly before or at future time 1101. Accordingly, if a
receiver unit does not receive first trigger 1100 because it was
not receiving triggers up until time 1104, the receiver unit would
nevertheless receive the second trigger 1105. Second trigger 1105
would then be executed despite the fact that first trigger 1100 was
not received. Executing the second trigger 1105 would not provide
for the prefetching of the information resource as would have been
the case were first trigger 1100 received, but the receiver unit
would still be able to retrieve the information resource at time
1101.
[0050] The receiver unit can distinguish first triggers from second
triggers in one of many suitable ways. In one embodiment, a trigger
is determined to be a second trigger if its URI is the same as the
URI of an earlier received trigger that will be executed at a
future time. If the receiver unit has already received a first
trigger and then receives such a second trigger that has the same
URI and identifies the same information resource, then the receiver
unit may ignore the second trigger.
[0051] FIG. 12 is a diagram that illustrates another embodiment in
accordance with the invention. This embodiment involves a trigger
that indicates a life span 1201 for the trigger.
[0052] FIG. 13 is a flowchart illustrating a method in accordance
with this embodiment. Initially (step 1300), video from a first
broadcast channel is received and displayed on a receiver unit.
Next (step 1301), a trigger 1200 having a time attribute value
indicating a life span 1201 is received by the receiver unit. In
FIG. 12, time progresses from left to right in the direction of the
horizontally extending arrow labeled TIME. The vertically pointing
arrow 1200 indicates the point in time on the arrow labeled TIME
when the trigger 1200 is received. In one embodiment, trigger 1200
is encoded into VBI line 21 of a first channel of an NTSC broadcast
signal. Trigger 1200 can, however, be communicated to the receiver
unit via other transport mechanisms.
[0053] FIG. 14 illustrates one possible time attribute value 1400
of trigger 1200. The "/" 1401 indicates that the time attribute
value indicates a life span. The time value 1402 preceding the "/"
indicates the starting time 1202 of the life span. The time value
1403 following the "/" indicates the ending time 1203 of the life
span. The "Ts" in these values 1402 and 1403 indicate that these
times are wall-clock times (as opposed to media time base times).
The receiver unit does not immediately execute trigger 1200 because
the current time is not within the life span 1201 indicated by time
attribute value of trigger 1200.
[0054] Next (step 1302), at time 1202, the receiver unit determines
that the current time is within the life span 1201 of trigger 1200.
The trigger can be executed within life span 1201. In one
embodiment, the receiver unit automatically executes trigger 1200
without further human input upon reaching time 1202. Execution of
trigger 1200 is illustrated in FIG. 12 by arrow 1204.
[0055] In one embodiment, execution of trigger 1200 causes an icon
to be displayed on the receiver unit. If a viewer selects the icon
using a remote control unit of the receiver unit, then an
enhancement is displayed on the receiver unit along with video from
the first broadcast channel. Execution of trigger 1200 may, for
example, entail retrieving an information resource identified by
trigger 1200 from the Internet and displaying that information
resource on the receiver unit.
[0056] Next (step 1303), the channel of video being displayed by
the receiver unit is switched from the first channel to a second
channel. When the channel of video is switched to the second
channel, the enhancement is no longer displayed because the trigger
1200 is not associated with the second channel. The switching of
channels from the first channel to the second channel is
illustrated in FIG. 12 as occurring at time 1205.
[0057] After a period of time, the channel of video is switched
back (step 1304) to first channel at time 1206 so that video from
the first channel is again displayed on the receiver unit. Such a
switching of channels from the first channel to the second channel
and back to the first channel may be due to a viewer's perusing
various channels.
[0058] If the time 1206 when the channel of video being displayed
is switched back to the first channel is within life span 1201 of
trigger 1200, then the trigger is valid for execution. In one
embodiment, trigger 1200 is automatically reexecuted (step 1305) by
the receiver unit so that the enhancement is displayed on the
receiver unit along with the first channel video. In this way, a
viewer can be viewing a first channel of video along with a
particular enhancement, switch channels to another channel, and
then return to the first channel of video such that the enhancement
previously being viewed will be automatically displayed if the
current time is still within the life span 1201 of the trigger.
[0059] There are many ways that a time attribute value can indicate
a life span. FIG. 15 illustrates a time attribute value 1500 that
indicates a life span that starts when the receiver unit receives
the trigger and ends at an absolute time (not a relative time).
FIG. 16 is a diagram illustrating the life span 1601 indicated by
the time attribute value 1500 of FIG. 15. In the example of FIG.
15, the absence of a value preceding the "/" character 1501 in the
time attribute value 1500 indicates that the life span 1601 starts
at the time 1602 when trigger 1600 is received. Life span 1601 ends
at time 1603 indicated by the value 1502 that follows the "/"
character 1501. Time value 1502 contains a "C" indicating that life
span ending time 1603 is expressed in terms of a media time base
(as opposed to wall-clock time). In one embodiment, each frame of
the broadcast video is labeled with a frame number and the receiver
unit monitors these frame numbers to determine when the frame
designated by the time attribute value is received. In another
embodiment, frames of the broadcast video are not labeled with
frame numbers. Rather, the receiver unit keeps track of the current
frame number by counting the passing of each successive frame as
frames are received.
[0060] Rather than life span ending time 1603 being expressed in
terms of a media time base as in the example of FIG. 15, life span
ending time 1603 can be expressed in terms of a wall-clock time. In
such a case, the "C" in the example of FIG. 15 is replaced with a
"T". Time attribute value 1500 would then indicate a life span that
starts when the receiver unit receives the trigger and that ends at
a given wall-clock time.
[0061] FIG. 17 illustrates another time attribute value 1700 that
indicates a life span. The absence of a time value preceding the
"/" character indicates that the life span starts when the trigger
is received. The "+P" characters of time value 1701 mean that time
value 1701 indicates a duration of time. The "C" in time value 1701
indicates that the duration is expressed in terms of a media time
base (as opposed to wall-clock time). Time attribute value 1700
therefore indicates a life span of one minute of video, wherein the
minute is measured in terms of the media time base, and wherein the
life span starts at the time the trigger is received.
[0062] FIG. 18 illustrates a time attribute value 1800 that is
similar to time attribute value 1700, except that the time value
that indicates the duration of the life span does so in terms of an
amount of wall-clock time (as opposed to an amount of time measured
in the media time base). Time attribute value 1800 therefore
indicates a life span of one minute of video, wherein the minute is
measured in terms of wall-clock time, and wherein the life span
starts at the time the trigger is received.
[0063] FIG. 19 illustrates a time attribute value 1900 that
indicates a life span wherein the starting and ending times are
expressed in terms of relative times. Both relative times are
measured from the time of the trigger is received. Time value 1901
indicates that the life span starts at a time one minute of media
from when the trigger is received. Time value 1902 indicates that
the life span ends at a time two minutes from the time when the
trigger is received. The one minute of media is measured in terms
of a media time base as indicated by the "C" in time value 1901.
The two minutes of media is measured in terms of a media time base
as indicated by the "C" in ending value 1902.
[0064] FIG. 20 illustrates a time attribute value 2000 that is
similar to time attribute value 1900 except that the ending time
value 2002 does not include the "+" character. The ending time
value 2002 is therefore not relative to the time the trigger is
received, but rather represents an amount of time relative to the
starting time value 2001. The life span therefore starts at a time
one minute of media from the time the trigger is received and
extends from that time for a period of three minutes of media. Both
the starting time and the three minutes of media are measured in
terms of a media time base (as opposed to wall-clock time).
[0065] In accordance with one embodiment, a television program is
tape-delayed or rebroadcast at a time when its triggers are no
longer valid (i.e., expired). To prevent these invalid triggers
from causing receiver unit failures or otherwise degrading the
viewing of the television show at the time of the tape-delay or
rebroadcast, the triggers of the television program include life
span time attributes. The ending times of the life span attributes
of these triggers are all before the time of the tape-delay or
rebroadcast. Because the life spans of these triggers have all
expired at the time of the tape-delay or rebroadcast, the receiver
unit ignores these triggers that are no longer valid.
[0066] Although the present invention is described in connection
with certain specific embodiments for instructional purposes, the
present invention is not limited thereto. Time attribute values can
employ characters and codes other than the specific characters and
codes in the specific time attribute described above. The specific
characters and codes used in the specific time attribute values
described above are but one possible set of characters and codes.
Other characters and codes may be employed. The various ones of the
characters and codes used in the specific time attributes described
above can be used together in various combinations to designate
future times of trigger execution, life span starting times, and/or
life span ending times. Such times can be designated in terms of
wall-clock time and/or media time base time. Such times can be
designated as absolute times and/or as relative times. Time zone
information and different precision of times may be expressed in
accordance with International Organization for Standardization
standard ISO-8601 (the subject matter of which is incorporated
herein by reference). Although the specific examples of time
attributes described above all involve an attribute of the form
[TIME:], the time attribute can have another forms in accordance
with the invention. The time attribute need not be an attribute in
accordance with EIA-746A. Application of triggers having time
attribute values are not limited to the video context, but rather
apply more broadly to triggers in general including the use of
triggers in radio (both analog radio and digital radio). The
triggers that do not synchronize events to either video or audio
may nonetheless employ a time attribute in accordance with the
present invention. A receiver unit need not receive media encoded
with time stamps in order to support media time base time attribute
values, rather a receiver unit can, for example, keep track of the
media time base by monitoring the progress of the media (for
example, by maintaining a count of successive frames of media as
successive frames are received). Triggers having time attribute
values can be communicated to receiver units by transports other
than the VBI line 21 sub-channel. Broadcast television formats
other than the NTSC format can be employed including: the Phase
Alternate Lines (PAL) format, the Sequential Couleur Avec Memoire
(SECAM) format, and the High Definition Television (HDTV) or
digital television format. Triggers having time attribute values
are not limited in application to solving bandwidth problems or to
solving problems associated with having to retrieve information
resources prior to trigger execution, but rather apply to the
timing of execution of triggers in general.
[0067] Triggers having time attributes are not limited in
application to situations where the triggers are received onto a
receiver unit via a broadcast transmission, but rather apply to any
situation where triggers are used including situations where video
stored on a storage medium (for example, on an optical disc) is
replayed and displayed on the receiver unit. In such a situation,
the receiver unit is considered to be "receiving" the triggers and
the video as the triggers and video are received onto the receiver
unit from the storage medium. A panel is used, rather than an icon,
to present possible interactivity to the user in some embodiments.
Software that carries out steps of methods in accordance with the
present invention can be stored on any computer-readable medium.
Examples of computer-readable mediums include magnetic and optical
storage media and semiconductor memory. Accordingly, various
modifications, adaptations, and combinations of various features of
the described embodiments can be practiced without departing from
the scope of the invention as set forth in the claims.
* * * * *