Patent Publication Number: US-11051082-B2

Title: Extensions to trigger parameters table for interactive television

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 13/915,664, filed Jun. 12, 2013, which is related and claims priority to U.S. provisional patent application No. 61/661,738, filed Jun. 19, 2012, which is incorporated herein by reference in its entirety. This application is also related to U.S. patent application Ser. No. 13/490,216, filed Jun. 6, 2012; U.S. provisional patent application No. 61/509,679, filed Jul. 20, 2011; U.S. provisional patent application No. 61/531,360, filed Sep. 6, 2011; U.S. provisional patent application No. 61/613,869, filed Mar. 21, 2012; U.S. provisional patent application No. 61/613,880, filed Mar. 21, 2012; and U.S. provisional patent application No. 61/636,488, filed Apr. 20, 2012, which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     Embodiments described herein relate generally to a method, computer program, reception apparatus, and information providing apparatus for trigger compaction. 
     Background 
     Modern televisions and set top boxes are capable of performing numerous functions in addition to receiving and presenting television broadcasts. Some functions include the display of an electronic programming guide (EPG), widgets that allow a television viewer to pull up web pages and tools right alongside programs being watched on a television, and the like. Many of these functions require that the television or set top box receive additional data. For example, in the case of the EPG, the television or set top box would need to receive program information. 
     In some cases the additional data is provided along with the television broadcast. When the additional data is provided in this manner the amount of data that can be provided is often limited. As a result, it may be necessary to reduce the amount of additional data provided along with the television broadcast or obtain the additional data from another source. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present disclosure address at least the problem discussed above by providing trigger compaction using a trigger parameters table (TPT). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  illustrates an exemplary broadcast system including a content source, reception apparatus, trigger parameters table (TPT) server, triggered declarative object (TDO) server, and an automatic content recognition (ACR) system; 
         FIG. 2  is a block diagram of an exemplary reception apparatus; 
         FIG. 3  is a processor-centric block diagram of an exemplary reception apparatus; 
         FIG. 4A  illustrates a flow diagram of an exemplary method for processing a trigger; 
         FIG. 4B  illustrates a flow diagram of an exemplary method for processing a trigger when a full transport stream (TS) is available; 
         FIG. 4C  illustrates a flow diagram of an exemplary method for processing a trigger when Internet access is available; 
         FIG. 4D  illustrates a flow diagram of another exemplary method for processing a trigger; 
         FIG. 5  illustrates a more detailed flow diagram of an exemplary method of a Declarative Object (DO) Engine for processing the trigger; 
         FIG. 6A  illustrates exemplary trigger timings for pre-produced content; 
         FIG. 6B  illustrates exemplary trigger timings for live content; 
         FIGS. 6C and 6D  illustrate exemplary triggers and associated TPTs; 
         FIG. 7  is a block diagram of an exemplary information providing apparatus; 
         FIG. 8  is an exemplary computer; 
         FIG. 9A  is an exemplary method for processing non-closed caption text data; 
         FIG. 9B  is an exemplary format of a trigger command delivered in non-closed caption text data; 
         FIG. 9C  illustrates an exemplary trigger syntax; 
         FIG. 10A  is an exemplary normative syntax for a trigger; and 
         FIG. 10B  is another exemplary normative syntax for a trigger. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment of the present disclosure, there is provided a method of a reception apparatus for processing triggers. The method includes receiving content from a content source, and displaying the received content on a display. A first trigger is extracted from closed caption data associated with the received content. The reception apparatus retrieves a trigger parameters table (TPT) based on the extracted first trigger. The TPT includes at least one event associated with one or a combination of a trigger identifier and a first media time of the received content, and is stored in a memory of the reception apparatus. Further, the reception apparatus processes the event based on one or a combination of a second trigger including the trigger identifier and the first media time equaling a current media time of the received content. 
     According to another embodiment of the method, the step of receiving content includes receiving the content via at least one of a satellite broadcast, a cable television transmission, a terrestrial television broadcast, and the Internet. 
     According to another embodiment of the method, the step of retrieving the TPT includes processing a Program Map Table (PMT) of a broadcast virtual channel associated with the received content. processing a Service Signaling Channel (SSC) to retrieve a Service Map Table (SMT), discovering coordinates of a File Delivery over Unidirectional Transport (FLUTE) session, acquiring a FLUTE File Delivery Table (FDT), comparing a locator-part of the first trigger against Content-Location values in the FLUTE FDT until a match is found, and retrieving the TPT based on the matched Content-Location value. 
     According to another embodiment of the method, the step of retrieving the TPT includes performing an Internet http GET using a locator-part of the first trigger. 
     According to another embodiment of the method, the step of extracting the first trigger includes extracting the first trigger from non-closed caption text data within a service block having a service number in the range of 1-6. 
     According to another embodiment of the method, the step of extracting the first trigger includes extracting the first trigger from non-closed caption text data within a service block having a service number of 6. 
     According to another embodiment of the method, the method further includes extracting the second trigger, including a second media time, from the closed caption data associated with the received content, and determining the current media time based on the second media time. 
     According to another embodiment of the method, the method further includes extracting the second trigger indicating that the event is to be retimed to a second media time from the closed caption data associated with the received content, and associating the event included in the TPT stored in the memory with the second media time. 
     According to another embodiment of the method, the method further includes extracting the second trigger from the closed caption data associated with the received content. The second trigger indicates immediate execution of the event associated with the trigger id. Further, the step of processing includes immediately processing the event associated with the trigger id. 
     Further, according to an embodiment of the present disclosure, there is provided a computer-readable storage medium having instructions embedded therein, which, when executed by a computer, cause the computer to perform the method of the reception apparatus, as discussed above. 
     According to an embodiment of the present disclosure, there is provided a reception apparatus. The reception apparatus includes a receiver, a display interface, an extraction unit, and a processor. The receiver is configured to receive content from a content source. The display interface is configured to display the received content. The extraction unit is configured to extract a first trigger from closed caption data associated with the received content. The processor is configured to retrieve a TPT based on the extracted first trigger. The TPT includes at least one event associated with one or a combination of a trigger identifier and a first media time of the received content. Further, the processor is configured to store the TPT in a memory of the reception apparatus, and process the event based on one or a combination of a second trigger including the trigger identifier and the first media time equaling a current media time of the received content. 
     According to another embodiment of the reception apparatus, the receiver is configured to receive the content via at least one of a satellite broadcast, a cable television transmission, a terrestrial television broadcast, and the Internet. 
     According to another embodiment of the reception apparatus, the processor is configured to process a PMT of a broadcast virtual channel associated with the received content, process an SSC to retrieve an SMT, discover coordinates of a FLUTE session, acquire an FDT, compare a locator-part of the first trigger against Content-Location values in the FLUTE FDT until a match is found, and retrieve the TPT based on the matched Content-Location value. 
     According to another embodiment of the reception apparatus, the processor is configured to perform an Internet http GET using a locator-part of the first trigger to retrieve the TPT. 
     According to another embodiment of the reception apparatus, the extraction unit is configured to extract the first trigger from non-closed caption text data within a service block having a service number in the range of 1-6. 
     According to another embodiment of the reception apparatus, the extraction unit is configured to extract the first trigger from non-closed caption text data within a service block having a service number of 6. 
     According to another embodiment of the reception apparatus, the extraction unit is configured to extract the second trigger including a second media time from the closed caption data associated with the received content. The processor is configured to determine the current media time based on the second media time. 
     According to another embodiment of the reception apparatus, the extraction unit is configured to extract the second trigger indicating that the event is to be retimed to a second media time from the closed caption data associated with the received content. The processor is configured to associate the event included in the TPT stored in the memory with the second media time in response to the second trigger. 
     According to another embodiment of the reception apparatus, the extraction unit is configured to extract the second trigger from the closed caption data associated with the received content. The second trigger indicates immediate execution of the event associated with the trigger id. The processor is configured to immediately process the event associated with the trigger id in response to the second trigger. 
     According to an embodiment of the present disclosure, there is provided an information providing apparatus, which includes a memory and a communication unit. The memory is configured to store a TPT. The TPT includes at least one event associated with one or a combination of a trigger identifier and a media time of content to be provided to a reception apparatus. The communication unit is configured to provide the TPT to the reception apparatus. The TPT is provided at a location identified in a trigger included within closed caption data associated with the content provided to the reception apparatus. 
     According to an embodiment of the present disclosure, there is provided a method of a reception apparatus for processing triggers. The method includes receiving content from a content source, and displaying the received content on a display. The reception apparatus  20  receives a first trigger associated with the received content. The reception apparatus retrieves a TPT based on the first trigger. The TPT includes at least one event associated with one or a combination of a trigger identifier and a first media time of the received content, and is stored in a memory of the reception apparatus. Further, the reception apparatus determines whether to process the at least one event included in the TPT based on one or a combination of a protocol version and one or more capabilities defined in the TPT. 
     According to another embodiment of the method, the step of receiving content includes receiving the content via at least one of a satellite broadcast, a cable television transmission, a terrestrial television broadcast, and the Internet. 
     According to another embodiment of the method, the step of retrieving the TPT includes processing a PMT of a broadcast virtual channel associated with the received content, processing an SSC to retrieve an SMT, discovering coordinates of a FLUTE session, acquiring an FDT, comparing a locator-part of the first trigger against Content-Location values in the FLUTE FDT until a match is found, and retrieving the TPT based on the matched Content-Location value. 
     According to another embodiment of the method, the step of retrieving the TPT includes performing an Internet http GET using a locator-part of the first trigger. 
     According to another embodiment of the method, the method further includes computing a random time period based on a diffusion attribute included in the TPT, and retrieving supplemental content referenced in the TPT after the computed random time period. 
     According to another embodiment of the method, the method further includes retrieving a second trigger indicating that the event is to be retimed to a second media time from a server identified in the TPT, and associating the event included in the TPT stored in the memory with the second media time. 
     Further, according to an embodiment of the present disclosure, there is provided a computer-readable storage medium having instructions embedded therein, which, when executed by a computer, cause the computer to perform the method of the reception apparatus, as discussed above. 
     According to an embodiment of the present disclosure, there is provided a reception apparatus. The reception apparatus includes a receiver, a display interface, and a processor. The receiver is configured to receive content from a content source. The display interface is configured to display the received content. The processor is configured to receive a first trigger associated with the received content. The processor is configured to retrieve a TPT based on the first trigger. The TPT includes at least one event associated with one or a combination of a trigger identifier and a first media time of the received content. Further, the processor is configured to store the TPT in a memory of the reception apparatus, and determine whether to process the at least one event included in the TPT based on one or a combination of a protocol version and one or more capabilities defined in the TPT. 
     According to another embodiment of the present disclosure, the receiver is configured to receive the content via at least one of a satellite broadcast, a cable television transmission, a terrestrial television broadcast, and the Internet. 
     According to another embodiment of the present disclosure, the processor is configured to process a PMT of a broadcast virtual channel associated with the received content, process an SSC to retrieve an SMT, discover coordinates of a FLUTE session, acquire an FDT, compare a locator-part of the first trigger against Content-Location values in the FLUTE FDT until a match is found, and retrieve the TPT based on the matched Content-Location value. 
     According to another embodiment of the present disclosure, the processor is configured to perform an Internet http GET using a locator-part of the first trigger to retrieve the TPT. 
     According to another embodiment of the present disclosure, the processor is configured to compute a random time period based on a diffusion attribute included in the TPT, and retrieve supplemental content referenced in the TPT after the computed random time period. 
     According to another embodiment of the present disclosure, the processor is configured to retrieve a second trigger indicating that the event is to be retimed to a second media time from a server identified in the TPT, and associate the event included in the TPT stored in the memory with the second media time. 
     According to an embodiment of the present disclosure, there is provided an information providing apparatus, which includes a memory and a communication unit. The memory is configured to store a TPT. The TPT includes at least one event associated with one or a combination of a trigger identifier and a media time of content to be provided to a reception apparatus. The communication unit is configured to provide the TPT to the reception apparatus, which determines whether to process the at least one event included in the TPT based on one or a combination of a protocol version and one or more capabilities defined in the TPT. 
     While the disclosure is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure of such embodiments is to be considered as an example of the principles and not intended to limit the disclosure to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings. 
     In interactive television applications, viewers are offered extra (i.e., supplemental) content, in addition to the program audio and video, that allows them to interact with the programming in some way. The extra content could be as simple as an Internet uniform resource locator (URL) that points to a website that can provide further information about the program, item, or service being shown. Or, an interactive element could provide text and/or graphics that augment the program video. An example of the latter is an element that displays a particular player&#39;s updated statistics during the course of a sporting event. 
     Often, the behavior or appearance/disappearance of these interactive elements is dependent on the timing of events within the program. Television receivers which are rendering these objects must be able to receive the appropriate signaling to know how and when to make the adjustments to the display of the interactive elements. The objects which perform this signaling function may be called “triggers” because they act to trigger a certain operation at the designated time. The varieties of operations that may be triggered are endless. Simple examples include such things as “execute” (start the operation of the interactive function), “hide” (remove all visible elements from the display), perform some designated action such as display or update some text or graphic, and “terminate” (end all operations and release memory resources). 
     The trigger itself must be transported from the point in the distribution chain at which the interactive element is sourced and operated all the way to the consumer&#39;s receiver. A variety of transport methods are possible for the trigger object. The trigger can be included in the digital transport multiplex in a variety of different locations, or it can be provided by an Internet-based server and accessed by receivers that are Internet-connected. Possible locations in the digital transport include in video or audio “user data,” within the closed captioning transport (as described below in further detail), within a descriptor carried in a program specific information (PSI) table, within adaptation fields of the MPEG-2 Transport Stream packet, embedded in audio, and modulated within the video itself in luminance or chrominance. 
     In each case, smaller triggers are preferable. E.g. a trigger that can be represented in as few as 30 bytes (or characters of text) offers greater flexibility in transport and greater efficiency compared to one whose size might be 100 or more bytes. In embodiments of the present disclosure, a method for providing interactivity is described in which the trigger function is accomplished using a small or “compact” trigger. 
     Referring now to the drawings,  FIG. 1  is a block diagram that shows an exemplary broadcast system  2 , including a content source  10 , a reception apparatus  20  (e.g., a digital television receiver device), a trigger parameters table (TPT) server  40 , a triggered declarative object (TDO) server  50 , and an optional automatic content recognition (ACR) system  60 . The reception apparatus  20  accesses the TPT server  40 , TDO server  60 , and/or ACR system  60  via one or more communication networks such as the Internet  30 . In other embodiments, TPTs stored in the TPT server  40  and/or the TDOs stored in the TDO server  60  are provided to the reception apparatus  20  by the content source  10  or the ACR system  60 . 
     The broadcast system  2  provides an interactive digital television feature whereby a viewer is presented with supplemental content that is associated with, and synchronized in time to events within, content provided by the content source  10 . The supplemental content includes one or a combination of media types such as audio, video, text, or an image, and/or one or more interactive elements. In one embodiment, the behavior and appearance of the supplemental content is associated with, and synchronized in time to the events within, the content. 
     In one embodiment, the content source  10  provides content to the reception apparatus  20  via a terrestrial broadcast. In other embodiments, the content source  10  provides the content via at least one of a satellite broadcast, a cable television transmission, a terrestrial television broadcast, cellular network, and data communication network such as a local area network (LAN), wide area network (WAN), or the Internet  30 . The content provided by the content source  10  includes one or more television programs, without regard to whether the content is a movie, sporting event, segment of a multi-part series, news broadcast, etc. Further, the content provided by the content source  10  may also include advertisements, infomercials, and other program-like content which may not be reported as a program in an EPG. 
     The reception apparatus  20  receives the content provided by the content source  10  and displays the content on a display  350 , illustrated in  FIG. 3 . In one embodiment, the display  350  is an integral part of the reception apparatus  20  such as a television set. Alternatively, the display  350  may be external to the reception apparatus  20  such as a television set connected to a set top box. 
     According to one embodiment, the reception apparatus  20  includes a Declarative Object (DO) Engine that accepts declarative objects (DOs) and renders them along with the content (e.g., audio/video content of a program) received from the content source  10 . The DO Engine renders a DO in response to a specific request from a user or in response to a trigger event. A DO that is rendered in response to a trigger event is referred to as a triggered declarative object (TDO). 
     The TDO is a downloadable software object created by a content provider, content creator, or service provider, which includes declarative content (e.g., text, graphics, descriptive markup, scripts, and/or audio) whose function is tied in some way to the content it accompanies. An embodiment of the TDO is described in U.S. application Ser. No. 12/959,529 filed Dec. 3, 2010 entitled “Announcement of Triggered Declarative Objects” to Blanchard et al. which is hereby incorporated by reference in its entirety. However, the TDO is not limited to the structure described in Blanchard et al. since many attributes defined therein as being a part of a TDO could be situated in a trigger or vice versa or not present at all depending upon the function and triggering of a particular TDO. 
     The TDO is generally considered as “declarative” content to distinguish it from “executable” content such as a Java applet or an application that runs on an operating system platform. Although the TDO is usually considered to be a declarative object, a TDO player (e.g., the DO Engine) supports a scripting language that is an object-oriented programming language. The TDOs, in examples shown herein, are received from a content or service provider in advance of the time they are executed so that the TDO is available when needed. Moreover, an explicit trigger signal may not be necessary and a TDO may be self-triggering or triggered by some action other than receipt of a trigger signal. Various standards bodies may define associated behaviors, appearances, trigger actions, and transport methods for content and metadata for a TDO. Additionally, requirements regarding timing accuracy of TDO behaviors relative to audio/video may be defined by standards bodies. 
     The trigger is a data object, which is optionally bound to a particular item of content (e.g., a television program) that references a specific TDO instance or a TPT, by the use of a file name or identifier for an object that is to be downloaded (e.g., when instructing download of the TDO or TPT) or has already been downloaded (e.g., when instructing execution, suspension, termination, etc. of the TDO or based on the TPT). Certain TDOs will only make sense in conjunction with certain content. An example is a TDO that collects viewer response data, such as voting on a game show or contest. 
     In one embodiment, the DO Engine receives triggers tied to coincide with various points (e.g., trigger events) in the content such as a scene change or the beginning or ending of an ad segment. The triggers are divided into two types: (1) those that are processed by the DO Engine, and (2) those that are passed by the DO Engine to the TDO for processing. The triggers associated with a type 1 command are associated with, for example, commands to be executed by the DO Engine. The triggers associated with a type 2 command are associated, for example, with parameters (e.g., commands, data, etc.) to be processed within the DO itself to effect changes in appearance, behavior, or state of associated supplemental content. 
     A trigger may be transported within a broadcast emission stream as described, for example, in U.S. patent application Ser. No. 13/216,375, which is incorporated herein by reference in its entirety. For example, a trigger may be transported in a Packetized Elementary Stream (PES) in an MPEG-2 Transport Stream (TS), or within the DTV closed caption stream, as described in U.S. provisional application No. 61/613,869, filed Mar. 21, 2012. In other embodiments, the trigger is embedded in the content itself. For example, the trigger may be embedded in an audio or a video portion of the content and recovered by processing of the decoded audio or the video in the reception apparatus  20 . 
     For some methods of transporting the trigger, smaller sized objects are preferred. In such a case, the trigger should be able to be represented within a small number of bits or bytes. Further, some transport methods may limit the maximum size of the trigger to a fixed number of bytes such as in the case of using the DTV Closed Caption Channel. 
     In one embodiment, when a trigger is transported within the broadcast emission stream, the trigger is delivered in the DTV Closed Caption Channel, in Standard caption service #6, in a command called “URL String”, as a URI_type=0 URL (Interactive TV Trigger). Based on the size of the trigger, the trigger may be segmented into a plurality of segments. In one embodiment, when the trigger is separated into a plurality of segments, each segment is associated with a type that indicates whether the respective segment is (1) the first of two or more; (2) neither the first nor the last; (3) the last; and (4) the one-and-only. Any predefined values may be used to identify the type of a particular segment. Further, in one embodiment, the type information defines the sequential order of the segments. In other embodiments, the type information may be used to convey any information about the segments to allow the reception apparatus  20  to reconstruct the trigger. 
     For example, if the trigger is less than or equal to 26 characters in length, it is sent non-segmented (e.g., Type=11). If the trigger is 27 to 52 characters in length, it is sent in two segments (the first segment in a Type=00 segment and the second segment in a Type=10 segment). However, in other embodiments, any other criteria can be used to determine how the trigger should be segmented. Further, other service numbers may be used in addition, or as an alternative, to using service number  6 . The trigger type is included in the trigger syntax illustrated in  FIG. 9C . 
       FIG. 9A  illustrates an exemplary process performed by the reception apparatus  20  when the trigger is delivered via the DTV Closed Caption channel. The reception apparatus  20  has access to such a trigger when, for example, it has access to the MPEG-2 Transport Stream, a portion of the full broadcast multiplex, or the content in compressed form. The process begins at S 902  where closed caption data including closed caption text is received within a first Standard service block having a pre-determined service number in the range of 1-6. At S 904 , non-closed caption text data are received within a Standard service block having a service number equal to the pre-determined number. In general, the Standard service used for the non-closed caption text data could be any one or a combination of service numbers n between 1 and 6, but since it is relatively rare for more than the first few of the service numbers to be used for caption text data, service number  6  is used in one embodiment. 
     At step S 906 , the reception apparatus  20  parses (e.g., in a parsing computer process module) the non-closed caption text data from the closed caption data appearing in service number  6  (or n). The non-closed caption text data are then processed at step S 908  (e.g., in another processor operation) to extract the trigger and perform a function based on the trigger. In one embodiment, the above-referenced non-closed caption text data are carried in a CEA-708 compliant variable length command. However, in other embodiments, the non-closed caption text data are carried in a CEA-708 fixed length command or a combination of variable and fixed length commands. 
     It should be noted that the DTV Closed Caption channel may also carry other types of data as an alternative or in addition to the trigger (e.g., a data stream including one or more parameters suitable for ingestion and processing by one or more TDOs, disparity data used in rendering a graphical object such as a caption window and its associated text for 3D content, etc.). These other types of data may be provided via one or more Standard service blocks having pre-determined number(s) different from the Standard service block carrying the trigger (e.g., Service #5, 4, or 3) or utilize different predetermined command code sequences in the same Standard service block as the trigger. 
     In one embodiment, the triggers are delivered using one of the unused code points, e.g., 0x98 in the CEA-708 C3 code space to deliver a variable-length short trigger. See  FIG. 9B  for an example specification in the format of a CEA standard (e.g. as an extension to CEA-708). The trigger is a variable-length command delivered in, for example, the C3 code set as defined in CEA-708. 
     The trigger command illustrated in  FIG. 9B  provides for the transport of interactive TV trigger data. As described above, in one embodiment, the trigger command is transported in standard caption Service #6. In the command coding above, the Length (L) is an unsigned integer that indicates the number of bytes following the header, in the range 11 to 27. 
     As specified in CEA-708-D Section 7.1.11.2, variable-length commands are indicated by the EXT1 character followed by a number in the range 0x90 to 0x9F, where the “0x” notation denotes a number represented in hexadecimal format. In the command format depicted in  FIG. 9B , the EXT1 character (0x10) is followed by 0x98. In this context, 0x98 is the command identifier for the trigger command. However, any other unused command identifier can be associated with the trigger command. In accordance with the syntax defined in CEA-708-D Section 7.1.11.2, the next byte contains a two-bit Type field, a zero bit, followed by a 5-bit length field. 
     In one embodiment, the trigger( ) data structure follows the byte containing the length field. The syntax of one example of the trigger data is depicted in  FIG. 9C  in pseudo code. In the exemplary trigger syntax of  FIG. 9C , trigger_type is a 4-bit unsigned integer that indicates the type of trigger to follow. In one embodiment, only type 0 triggers are defined. Accordingly, the value of trigger_type is set to 0. The reception apparatus  20  is expected to disregard instances of the trigger command indicating triggers of any other (unrecognized) type. In another embodiment, trigger_type is set to one value to indicate an Interactive TV trigger and another value to indicate that the URL is the Internet server location used for service usage reporting. 
     Further, in one embodiment, trigger_character is an 8-bit ASCII character whose value is restricted to those allowed for Uniform Resource Identifiers (URIs) by RFC 2396. The character string formed by trigger( ) is a valid URI per RFC 2396, which is incorporated by reference in its entirety. 
     Use of a variable-length DTV closed caption command in Service #6 to transport the trigger provides: (1) robust (explicit) signaling of the presence of the trigger; (2) signaling of the type of trigger (for future expansion); (3) a transport format that is a natural extension to the existing CEA-708 DTV CC protocol; and (4) a transport method that is transparent to legacy receivers. 
     A trigger may also be transported via other paths such as the Internet. In one embodiment, when the trigger is not available via the broadcast emission stream, the reception apparatus  20  acquires the trigger via the ACR system  60  by, for example, sending A/V samples of the content being received by the reception apparatus  20  to the ACR system  60 . 
     When the reception apparatus  20  has no access to either the broadcast TS or broadcast triggers, in one embodiment, the reception apparatus  20  identifies the content being watched and the Media Time by means of the ACR system  60 . In this case, the TPT and associated files are retrieved from the Internet server (e.g., TPT server  40 ) identified by the trigger as usual. However, in one embodiment, the ACR system  60  will not be responsible for offering updated triggers, to for example establish the timing for live events. Instead, updated triggers will be distributed from the TPT server  40  identified by a locator_part of the trigger, as described below. In other embodiments, the updated triggers may be provided by the ACR system  60 , for example, when the ACR system  60  and TPT server  40  are combined into a single system. 
     In the ACR case, the reception apparatus  20  is expected to perform an access to the TPT server  40  to open a channel over which updated triggers may be received. For example, the protocols for trigger refresh may conform to the Long Polling methods defined in RFC 6202, which is incorporated herein by reference in its entirety. 
     Embodiments of the present disclosure provide some approaches to a system design in which the trigger itself can be represented within a small number of bytes, in order to facilitate convenient and robust transport. The representation of the trigger in a small number of bytes addresses issues such as a need for small, compact, and robust triggers for transport methods with limited data carrying capacity; and a need to accommodate variable-sized payloads, which are often awkward to transport. Some embodiments of the present disclosure also address the desire to offer a flexible system in which the TDO can be “table-driven” (e.g., its actions and behavior are specified by data in an associated table, rather than being coded into the TDO itself). This allows a single TDO script to be usable in a variety of situations. 
     A motivation behind the concept of triggers is that the files that make up a TDO and the data files to be used by the TDO to take some action take some amount of time to transmit to the reception apparatus  20 , given their size. While the user experience of the interactive elements can be authored prior to the broadcast of the content, certain behaviors must be carefully timed to coincide with events in the program itself, for example the occurrence of a commercial advertising segment. The broadcast system  2  separates the delivery of declarative objects and associated data, scripts, text and graphics from the signaling of the specific timing of the playout of interactive events (i.e., the trigger). 
     The triggers perform various timing-related signaling functions in support of interactive services. Triggers are multi-functional; depending on their structure, exemplary trigger instances can perform one or more of the following functions:
         Signal the location of a file directory (accessible via a File Delivery over Unidirectional Transport (FLUTE) session in the emission stream, via an Internet server, or both) containing interactive elements, for example TPTs, TDOs, graphics, and data files;   Indicate that interactive content for an upcoming program segment is available to be pre-loaded;   Indicate the current Media Time of associated audio/video or audio-only content;   Reference a particular interactive event in a TPT and signal that the event is to be executed now or at a specified future Media Time;   Indicate that accesses to an Internet server are to be spread out randomly over a specified time interval in order to avoid a peak in demand.       

     An exemplary normative syntax for the trigger is illustrated in  FIG. 10A . This Trigger syntax is based on the absolute URI per RFC 3986, which is incorporated herein by reference in its entirety, excluding the &lt;scheme&gt; and “://” portion, with additional restrictions as specified below.  FIG. 10B  illustrates another exemplary normative syntax for the trigger. 
     The syntactic definition illustrated in  FIG. 10A  is described using the Augmented Backus-Naur Form (ABNF) grammar defined in RFC 5234, which is incorporated herein by reference in its entirety, except that the vertical bar symbol “|” is used to designate alternatives. Rules are separated from definitions by an equal “=”, indentation is used to continue a rule definition over more than one line, literals are quoted with “ ”, parentheses “(“and”)” are used to group elements, optional elements are enclosed in “[” and “]” brackets, and elements may be preceded with &lt;n&gt;* to designate n or more repetitions of the following element; n defaults to 0. 
     In one embodiment, additional constraints include: (1) the maximum length of the trigger does not exceed 52 bytes; and (2) the host name portion of the Trigger is a registered Internet domain name. The maximum length of 52 bytes is set in the embodiment in which the trigger is transmitted via the DTV Closed Caption Channel in Service Channel #6, as described above. However, different maximum lengths can be set if the trigger is transmitted via other portions of the DTV Closed Caption Channel or other transport methods. 
     In some embodiments, the trigger is considered to consist of three parts, two being required and the third being optional: &lt;domain name part&gt;/&lt;directory path&gt;[?&lt;parameters&gt;]. 
     The &lt;domain name part&gt; references a registered Internet domain name. The &lt;directory path&gt; is an arbitrary character string identifying a directory path under the control and management of the entity who owns rights to the identified domain name. The combination of &lt;domain name part&gt; and &lt;directory path&gt; uniquely identify a set of files that can be processed by the reception apparatus  20  to add interactivity to the associated content. 
     The &lt;parameters&gt; portion of the Trigger is optional. When present, it can convey one or more parameters associated with the trigger. In one embodiment, the trigger carries parameters within a query string (e.g., the portion of the trigger to the right of the “?”). Defined formats for the query string include, for example, (1) &lt;event time&gt;, optionally followed by &lt;spread&gt;; (2)&lt;media time&gt;, optionally followed by &lt;spread&gt;; (3)&lt;other&gt;, optionally followed by &lt;spread&gt;; and (4) &lt;spread&gt;. 
     In one embodiment, the parameters are formatted according to the following rules: 
     &lt;event time&gt;—two parameters, a trigger event ID designated by “e=” followed by a decimal number referencing the event ID in the associated TPT, and a timing value designated by “&amp;t=” followed by a string 1 to 7 characters in length representing a hexadecimal number indicating a new media timing for the designated trigger event. 
     &lt;media time&gt;—a term designated by “m=” followed by a character string of 1 to 7 characters in length representing hexadecimal number indicating the current Media Time in units of milliseconds. 
     &lt;spread&gt;—a term designated by “s=” when it is the only term, or “&amp;s=” when appended to other terms, with a character string of 1 to 3 characters in length representing a decimal number indicating the number of seconds of time over which all receivers, including the reception apparatus  20 , should attempt to access the Internet server identified in the trigger. Each individual reception apparatus  20  is expected to derive a random time within the designated interval and delay the access request by that amount, thereby spreading in time the peak in demand that might otherwise occur at the first appearance of a trigger at the reception apparatus  20 . 
     &lt;other&gt;—a term designated by a character other than “e”, “E”, “m”, “M”, “s”, “S”, “t”, or “T”, followed by the equals-sign and an alphanumeric string. A second &lt;other&gt; term may appear after the first; if present, the beginning of the second term is delimited with the “&amp;” character. Each reception apparatus  20  is expected to disregard unrecognized terms. 
     Examples of valid Triggers and their functions are given in Table 1 below: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Example Triggers and Functions 
               
            
           
           
               
               
            
               
                 Example Trigger 
                 Function 
               
               
                   
               
               
                 xbc.tv/e12 
                 Pre-load interactive content (or TPT) from identified 
               
               
                   
                 directory/location (online at http://xbc.tv/e12 or within 
               
               
                   
                 associated FLUTE session). 
               
               
                 xbc.tv/e12?s=10 
                 Pre-load interactive content (or TPT) from identified 
               
               
                   
                 directory/location (online at http://xbc.tv/e12 or within 
               
               
                   
                 associated FLUTE session), with smoothing parameter 
               
               
                   
                 value 10 seconds. 
               
               
                 xbc.tv/e12?m=5a33 
                 Identify the location of interactive content (or TPT) 
               
               
                   
                 and establish the current Media Time of the associated 
               
               
                   
                 content. 
               
               
                 xbc.tv/e12?e=7 
                 Identify the location of interactive content (or TPT) 
               
               
                   
                 and signal the immediate execution of the TPT 
               
               
                   
                 interactive event associated with trigger_ID (or 
               
               
                   
                 eventID) value 7. 
               
               
                 xbc.tv/e12?e=8&amp;t=77ee 
                 Identify the location of interactive content (or TPT) 
               
               
                   
                 and signal the execution of the TPT interactive event 
               
               
                   
                 associated with trigger_ID (eventID) value 8 at Media 
               
               
                   
                 Time 77ee. 
               
               
                 xbc.tv/e12?m=5a33&amp;s=12 
                 Identify the location of interactive content (or TPT) 
               
               
                   
                 and establish the current Media Time of the associated 
               
               
                   
                 content, with smoothing parameter value 12 seconds. 
               
               
                   
               
            
           
         
       
     
     Query terms other than those defined above (“e”, “m”, “s”, and “t”) may appear in a trigger to define one or more other predetermined functions. Accordingly, in one embodiment, the following triggers are legal and each reception apparatus  20  is expected to process them accordingly: 
     a.xbc.tv/77?a=6EE43f. Reception apparatus  20  can use as a pre-load, but disregard the “a” term if it is not recognized. 
     a.xbc.tv/133-Ar4?w=3&amp;s=10. Reception apparatus  20  can use as a pre-load with spreading parameter  10 , and disregard the “w” term if it is not recognized. 
     x.tv/E7?B=OK&amp;C=OK&amp;S=10. Reception apparatus  20  can use as a pre-load with spreading parameter  10 , and disregard the “B” and “C” commands if they are not recognized. Note that depending on the embodiment, the query term identifier may or may not be case-insensitive. 
     When the TPT is specified as an XML Schema, an exemplary namespace for this schema is http://www.atsc.org/XMLSchemas/tpt/2012/1 indicating that it is major version 1 of the schema. In one embodiment, the “schema” element of the XML schema includes a “version” attribute set to the value 1.0, indicating that the minor version number of the schema is 0. 
     In order to provide flexibility for future changes in the schema, decoders (e.g., reception apparatus  20 ) of TPT instance documents with the namespace defined above should follow the “must ignore” rule. That is, they should ignore any elements or attributes they do not recognize, rather than treating them as errors. 
     An embodiment of the TPT structure is illustrated in the Table 2 below. Items preceded by “@” are attributes; others are elements. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 TPT Structure 
               
            
           
           
               
               
               
            
               
                   
                 No. 
                   
               
               
                 Element/Attribute (with @) 
                 permitted 
                 Description &amp; Value 
               
               
                   
               
               
                 tpt 
                   
                   
               
               
                 @id 
                 1 
                 domain_name/Program_id = segment id 
               
               
                 @tptType 
                 1 
                 “static”|“dynamic” 
               
               
                 @majorVersion 
                 1 
                 Interactive protocol major version number 
               
               
                 @minorVersion 
                 0 . . . 1 
                 Interactive protocol minor version number 
               
               
                 @tptVersion 
                 1 
                 Version of this TPT instance 
               
               
                 @updatingTime 
                 0 . . . 1 
                 Recommended TPT polling interval (only for type = 
               
               
                   
                   
                 “dynamic”) 
               
               
                 @beginMt 
                 0 . . . 1 
                 The beginning time of the TPT scope 
               
               
                 @endMt 
                 0 . . . 1 
                 The end time of the TPT scope 
               
               
                 @expireDate 
                 0 . . . 1 
                 Expire date for caching TPT document. (only for 
               
               
                   
                   
                 type = “static”) 
               
               
                 liveTrigger 
                 0 . . . 1 
                 optional specification of server providing live 
               
               
                   
                   
                 Triggers 
               
               
                   @liveTriggerURL 
                 1 
                 URL of server providing updated live Triggers 
               
               
                   @longPoll 
                 0 . . . 1 
                 true means use “long poll” protocol; false means 
               
               
                   
                   
                 reg. poll 
               
               
                   @pollPeriod 
                 0 . . . 1 
                 polling period in seconds when regular polling is 
               
               
                   
                   
                 used 
               
               
                 event 
                 1 . . . N 
               
               
                   @eventID 
                 1 
                 event_id 
               
               
                   @startTime 
                 0 . . . 1 
                 The start time of the command valid period 
               
               
                   @endTime 
                 0 . . . 1 
                 The end time of the command valid period 
               
               
                   @destination 
                 0 . . . 1 
                 Device type—“receiver”: receiver itself; 
               
               
                   
                   
                 “external_1” external device type1 
               
               
                   
                   
                 “external_2” external device type2 
               
               
                   @action 
                 1 
                 “register”|“suspend-execute”|“terminate- 
               
               
                   
                   
                 execute”|“suspend-resume”|“terminate-resume”| 
               
               
                   
                   
                 “terminate”|“event” 
               
               
                   @diffusion 
                 0 . . . 1 
                 Period for applying command diffusion 
               
               
                   application 
                 1 
                 Description for target TDO 
               
               
                     @appID 
                 1 
                 TDO ID 
               
               
                     @type 
                 1 
                 TDO type 
               
               
                     @url 
                 1 
                 TDO URL 
               
               
                     @priority 
                 0 . . . 1 
                 Priority to persist 1: High 0: Normal 
               
               
                     @expireDate 
                 0 . . . 1 
                 Expire date for caching the application 
               
               
                     capability 
                 0 . . . N 
                 Receiver required capability for this application 
               
               
                   streamEvent 
                 0 . . . 1 
                 Description for event 
               
               
                     @streamEventID 
                 1 
                 Event ID 
               
               
                     data 
                 0 . . . 1 
                 Embedded data 
               
               
                   
               
            
           
         
       
     
     The TPT structure of Table 2 includes major and minor protocol version attributes at the TPT level (top level). In one embodiment, these attributes function similarly to the way namespaces can be used to specify different types of TPT data structures for extensibility. The major and minor protocol version attributes allow the reception apparatus  20  to conveniently identify whether a particular TPT instance corresponds to a first release or to some future release of a standard where the structure of the schema may be different. 
     The TPT structure of Table 2 also includes a simplified XML specification of a diffusion mechanism. As opposed to a diffusion mechanism of a complex type called Diffusion Type with a single attribute, the diffusion mechanism is simplified to just an attribute of the Event Type. 
     The complex Diffusion Type relates to diffusion occurring during repeated deliveries of the TPT. The first issuance might indicate that 1 in 4 receivers should try to access the server. The second might indicate that 1 in 3 should access, etc. The last one would indicate that all the remaining ones should access. In the more realistic use case, the TPT is retrieved once, and nearly all receivers may want to begin retrieving the referenced assets at that moment. A one-parameter method is suitable for this application. 
     The prior 3-parameter method involved these items: 
     rate: An attribute of diffusion element. It indicates the number of timing divided for the randomized diffusion of command execution timing in integer. 
     range: An attribute of diffusion element. It indicates the scope of the randomized diffusion of command execution timing in seconds. 
     period: An attribute of diffusion element. It indicates the period to apply the randomized diffusion of command execution timing in seconds since the start time of the command. In other words, the receiver works considering the diffusion only during this period. 
     The TPT structure of Table 2 also includes a liveTrigger element added at the TPT (top) level, corresponding to a complex type called liveTrigger Type. In one embodiment, the liveTrigger Type consists of one required and two optional attributes. The required attribute specifies the URL of a server or other location within the TS that can provide updated triggers for live events. The optional parameters specify how polling is to be done (e.g., periodic, or “long” poll), and if periodic, the duration of the polling period. However, the liveTrigger Type may consist of different combinations of required and optional attributes in other embodiments. 
     The TPT structure of Table 2 further includes a capability element, in the Application Type. This feature allows a given Application to be associated with zero or more “capability codes.” Each code identifies a data type for which support in the reception apparatus  20  for that data type is essential for meaningful presentation of the application. A given code can be any predetermined symbol or value such as an integer value which references predetermined definitions, or it can be an Internet Media Type string (formerly known as mime-type string). Resource definitions can be, for example, a certain audio or video codec along with the required level of the reception apparatus  20  decoding capability (for codecs, known as profiles and levels). 
     The capability codes, when present, allow the reception apparatus  20  to ascertain up front, before downloading necessary resources (e.g., TDOs and other assets associated with an application), whether or not it has the capability to decode that content. For example, if support for a certain codec is needed, or a certain protocol level, the reception apparatus  20  should be able to decide whether or not it supports it. 
     Exemplary semantics of the fields in the TPT structure are as follows: 
     tpt: The root element of the TPT. One tpt element describes all or a portion (in time) of one programming segment. 
     id: An attribute of the tpt element such as a string that uniquely identifies the programming segment to which this tpt element targets. In one embodiment, the id string is the locator_part of the corresponding trigger, as described above. 
     tptType: An attribute of the tpt element. In one embodiment, this attribute is a string that indicates the updatability of this tpt element. The value is “static” or “dynamic”. In case of “static,” all the timing references in the tpt instance are valid Media Time values. In case of “dynamic”, the tpt element may not include valid Media Time values. Therefore, in this case the reception apparatus  20  is expected to acquire and process triggers including &lt;event time&gt; parameters in order to know the proper Media Times for different events. The reception apparatus  20  may also acquire updated timing by receiving an updated (newer version) of the TPT. 
     majorVersion: A required attribute of the tpt element that is an integer value in the range 1 to 99 that indicates the major protocol version of this TPT instance. The value of majorVersion for this version of the protocol is set to 1, in one embodiment. Each reception apparatus  20  is expected to discard instances of the TPT indicating values of majorVersion it is not equipped to support. 
     Note that in some embodiments, one TPT instance can describe interactive events for multiple versions of the protocol. For example, a single TPT instance could be usable by receivers that only understand protocol version 1.0 as well as by receivers that also support protocol version 2.0. The latter type of receiver could disregard all or part of the portion of the TPT including the 1.0-level elements, and process the portion of the TPT including the 2.0-level elements. 
     minorVersion: An optional attribute of the tpt element that is an integer value in the range 0 to 99 that indicates the minor protocol version of this TPT instance. The value of minorVersion is set to 0 in one embodiment. Each reception apparatus  20  is expected to not discard instances of the TPT indicating unrecognized values of minorVersion. The minor protocol version is used to represent changes to the TPT protocol that are not significant enough to cause compatibility issues with older receivers built to an earlier minor protocol version. For receivers that do recognize a certain value of minor protocol version, they can look for and process certain data elements that the older receivers would ignore. 
     tptVersion: An attribute of the tpt element that is a positive integer value that indicates the version number of the tpt element identified by the id attribute. The tptVersion is incremented whenever any change is made to the TPT. 
     updatingTime: An optional attribute of the tpt element. When present, this positive integer value indicates the time period in seconds the reception apparatus  20  should use when acquiring an updated TPT by polling. The updatingTime parameter is only valid when the tpt type is “dynamic”. Note that one method for delivery of updated event timing is to issue a trigger including &lt;event time&gt; parameters. 
     beginMt: an optional attribute of tpt element. When present, it indicates the beginning Media Time of the segment or portion of the segment described by this TPT instance. 
     endMt: An optional attribute of tpt element. When present, it indicates the ending Media Time of the segment or portion of the segment described by this TPT instance. 
     expireDate: An optional attribute of tpt element. When present, it indicates the date and time of the expiration of the information included in this tpt instance. If the reception apparatus  20  caches the tpt, it can be re-used until the expireDate. The expireDate is formatted as an xs:dateTime string. 
     liveTrigger: This optional complex type specifies information that is used for the case of the dynamic tpt. 
     liveTriggerURL: A required attribute of the liveTrigger element. This string indicates the URL of a server that will provide updated triggers for the live broadcast case. 
     longPoll: An optional attribute of the liveTrigger element. This Boolean element indicates when true that the reception apparatus  20  should use the “long polling” protocol to receive updated triggers. When false, it indicates the reception apparatus  20  should do regular polling at the interval indicated in the pollPeriod attribute. 
     pollPeriod: An optional attribute of the liveTrigger element. This parameter, when present, indicates the time period in seconds the reception apparatus  20  should use when polling the live Trigger server. A value of 30, for example, indicates the reception apparatus  20  should ask for an updated trigger every 30 seconds. 
     event: A child element of tpt element. It represents each event affecting TDO operation and life-cycle. One or more events may appear in a TPT instance. 
     eventID: An attribute of event element. It indicates the unique identifier of command in the form of an unsigned integer. The scope of the uniqueness of eventID is, in one embodiment, the full duration of the programming segment. The eventID is referenced by a trigger containing &lt;event time&gt; parameters. 
     startTime: An optional attribute of the event element. When present it indicates the start of the valid time period for the event relative to Media Time. The reception apparatus  20  is expected to execute the command when Media Time reaches the value in startTime. 
     endTime: An optional attribute of the event element. When present it indicates the end of the valid time period for the event relative to Media Time. The reception apparatus  20  is expected to not execute the command when Media Time is past the value in endTime. 
     destination: An optional attribute of the event element. When present it indicates the device targeted for this event. If the targeted device is the reception apparatus  20  itself, the value is “receiver” or any other predetermined value. If the target device is not the reception apparatus  20 , it indicates the other device type or application type. 
     action: An attribute of event element. It indicates the event action type to control application (TDO) operation and life-cycle. In one embodiment, the value is either of the following: 
     “register”: if possible, acquire and pre-cache resources of the application. 
     “suspend-execute”: suspend any other currently executing application and launch the application. In case of not pre-caching application yet, before launching application, the reception apparatus  20  needs to acquire the resources of the application. If the targeted application is suspended, the reception apparatus  20  resumes it with the former state. 
     “terminate-execute”: terminate any other currently executing application and launch the application. In case of not pre-caching application yet, before launching application, the reception apparatus  20  needs to acquire the resources of the application. If the targeted application is suspended, the reception apparatus  20  resumes it with the former state. 
     “suspend-resume”: suspend any other currently executing application and resume the application. 
     “terminate-resume”: terminate any other currently executing application and resume the application. 
     “terminate”: terminate the application. 
     “suspend”: suspend the application executing. UI and application engine state is required to be preserved until launching again. 
     “event”: Fire the stream event depending on the application script. 
     diffusion: An optional attribute of the event element. When present, this integer value represents a period of time in seconds, N. The purpose of the diffusion parameter is to smooth peaks in server loading. The reception apparatus  20  is expected to compute a random time period in the range 0-N and delay this amount before accessing an Internet server to retrieve content referenced by URLs in the TPT. 
     application: A child element of command. It represents the application (e.g., TDO) to which the command targets. 
     appID: A required attribute of the application element. It indicates the unique identifier of the application (TDO). In one embodiment, the format is a predetermined globally unique format. 
     appType: A required attribute of application element. It indicates the application format type. In one embodiment, the value only can be “html5.” 
     url: A required attribute of the application element. It indicates the URL where the reception apparatus  20  can acquire the application. 
     priority: An optional Boolean attribute of the application element. If the reception apparatus  20  caches the application resources after using them once, it may need to manage multiple application resources. The priority indicates the caching priority among applications competing for cache memory space. The value is either normal (value false or 0) or high (value true or 1). If this attribute is not present, in one embodiment, the cache priority is regarded as normal. Alternatively, the cache priority may be regarded as high when the attribute is not present in another embodiment. 
     expireDate: An optional attribute of the application element. The expireDate parameter is used to help the reception apparatus  20  manage memory resources. It indicates a date and time after which the reception apparatus  20  can safely delete the application resources. The expireDate is expressed in xs:dateTime format. 
     capability: An element of the application element that is a sequence of zero or more capability code strings. Each capability code string is either an integer or a media type string. When the capability code string is an integer, the integer value corresponds to a predetermined capability code corresponding to capabilities such as a supported video codec, supported audio codec, supported “browser” profile, supported DO engine profile, supported memory size (to signal whether the memory resources in the receiver are sufficient to handle the resources associated with the service), etc. The reception apparatus  20  is expected to process each capability element to determine if it supports the indicated capability. If one or more capability codes are not supported, the reception apparatus  20  is expected to disregard the application instance. In another embodiment, the reception apparatus  20  may determine whether the application instance based on a predetermined or user defined priority of each of the unsupported capability codes. 
     streamEvent: A child element of the event element. It represents the stream event which enables the application to work synchronously with the broadcast signal in case that action attribute of command element is “event”. 
     streamEventID: A required attribute of the event element. It indicates the unique identifier of the stream event. Referencing between stream event and application can be realized by this identifier. 
     data: A child element of event element. It describes the embedded data related to the stream event if it exists. The target application will read this data and use it. 
     An embodiment of the XML schema of a TPT is defined in Table 3 below: 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 TPT XML Schema 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 &lt;?xml version=″1.0″ encoding=″UTF-8″?&gt; 
               
               
                 &lt;xs:schema xmlns:tpt=″urn:atsc2.0″ 
               
               
                 xmlns:xs=″http://www.w3.org/2001/XMLSchema″ targetNamespace=″urn:atsc2.0″ 
               
               
                 elementFormDefault=″qualified″ attributeFormDefault=″unqualified″&gt; 
               
               
                   &lt;xs:element name=″TPT″&gt; 
               
               
                    &lt;xs:complexType&gt; 
               
               
                     &lt;xs:sequence&gt; 
               
               
                      &lt;xs:element name=″liveTrigger″ type=″tpt:LiveTriggerType″ 
               
               
                 minOccurs=″0″/&gt; 
               
               
                      &lt;xs:element name=″event″ type=″tpt: EventType″ 
               
               
                 maxOccurs=″unbounded″/&gt; 
               
               
                     &lt;/xs:sequence&gt; 
               
               
                     &lt;xs:attribute name=″majorVersion″ type=″xs:string″ use=″required″/&gt; 
               
               
                     &lt;xs:attribute name=″minorVersion″ type=″xs:string″ use=″optional″/&gt; 
               
               
                     &lt;xs:attribute name=″id″ type=″xs:ID″/&gt; 
               
               
                     &lt;xs:attribute name=″tptType″ type=″xs:string″ default=″static″/&gt; 
               
               
                     &lt;xs:attribute name=″tptVersion″ type=″xs:string″ use=″optional″/&gt; 
               
               
                     &lt;xs:attribute name=″updatingTime″ type=″xs:string″ use=″optional″/&gt; 
               
               
                     &lt;xs:attribute name=″beginMt″ type=″xs:time″ use=″optional″ 
               
               
                     &lt;xs:attribute name=″endMt″ type=″xs:time″ use=″optional″/&gt; 
               
               
                     &lt;xs:attribute name=″expireDate″ type=″xs:dateTime″ use=″optional″/&gt; 
               
               
                    &lt;/xs:complexType&gt; 
               
               
                   &lt;/xs:element&gt; 
               
               
                   &lt;xs:complexType name=″LiveTriggerType″&gt; 
               
               
                    &lt;xs:attribute name=″liveTriggerURL″ type=″xs:anyURI″ use=”required”/&gt; 
               
               
                    &lt;xs:attribute name=″longPoll″ type=″xs:boolean″ use=″optional″ 
               
               
                 default=″true″/&gt; 
               
               
                    &lt;xs:attribute name=″pollPeriod″ type=″xs:duration″ use=″optional″/&gt; 
               
               
                   &lt;/xs:complexType&gt; 
               
               
                   &lt;xs:complexType name=″EventType″&gt; 
               
               
                    &lt;xs:sequence&gt; 
               
               
                     &lt;xs:element name=″application″ type=″tpt:ApplicationType″/&gt; 
               
               
                     &lt;xs:element name=″streamEvent″ type=″tpt:StreamEventType″ 
               
               
                 minOccurs=″0″/&gt; 
               
               
                    &lt;/xs:sequence&gt; 
               
               
                    &lt;xs:attribute name=″eventID″ type=″xs:ID″ use=”required”/&gt; 
               
               
                    &lt;xs:attribute name=″startTime″ type=″xs:time″ use=″optional″/&gt; 
               
               
                    &lt;xs:attribute name=″endTime″ type=″xs:time″ use=″optional″/&gt; 
               
               
                    &lt;xs:attribute name=″destination″ type=″xs:string″ use=″optional″ 
               
               
                 default=″receiver″/&gt; 
               
               
                    &lt;xs:attribute name=″action″ type=″xs:string″ use=”required”/&gt; 
               
               
                    &lt;xs:attribute name=″diffusion″ type=″xs:duration″ use=″optional″/&gt; 
               
               
                   &lt;/xs:complexType&gt; 
               
               
                   &lt;xs:complexType name=″ApplicationType″&gt; 
               
               
                    &lt;xs:sequence&gt; 
               
               
                     &lt;xs:element name=″capability″ type=″xs:string″ minOccurs=″0″ 
               
               
                 maxOccurs=″unbounded″/&gt; 
               
               
                    &lt;/xs:sequence&gt; 
               
               
                    &lt;xs:attribute name=″appID″ type=″xs:ID″ use=”required”/&gt; 
               
               
                    &lt;xs:attribute name=″type″ type=″xs:string″ use=”required”/&gt; 
               
               
                    &lt;xs:attribute name=″url″ type=″xs:anyURI″ use=″optional″/&gt; 
               
               
                    &lt;xs:attribute name=″priority″ type=″xs:boolean″ use=″optional″ default=″0″/&gt; 
               
               
                    &lt;xs:attribute name=″expireDate″ type=″xs:dateTime″ use=″optional″/&gt; 
               
               
                   &lt;/xs:complexType&gt; 
               
               
                   &lt;xs:complexType name=″StreamEventType″&gt; 
               
               
                    &lt;xs:sequence&gt; 
               
               
                     &lt;xs:element name=″data″ type=″xs:string″ minOccurs=″0″/&gt; 
               
               
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                    &lt;xs:attribute name=″streamEventID″ type=″xs:ID″/&gt; 
               
               
                   &lt;/xs:complexType&gt; 
               
               
                 &lt;/xs:schema&gt; 
               
               
                   
               
            
           
         
       
     
     In one embodiment, the reception apparatus  20  is configured to receive updated versions of a TPT when available. The capability to receive an updated version of the TPT provides increased flexibility in providing trigger events when it is difficult to determine the exact timing of trigger events ahead of time, such as in the case of live programming. During the live programming, the TPT can be updated to include timing information once it has been determined. For example, updated versions of the TPT may include modified or new timing information associated with a trigger for displaying supplemental content during the live programming. In another example, the TPT can be updated to refer to different content based on the outcome of the live event. 
     In another embodiment, the TPT remains unchanged as the program progresses. The timing of execution of specific interactive events is determined by the appearance of a trigger referencing a specific event. When the receiving apparatus  20  receives a trigger, the event referenced in the TPT is executed. 
     While some forms of the trigger can indicate that the time is right for the TDO to perform a certain action, a series of timed actions can be played out without a trigger. The TPT optionally provides timing information for various interactive events relative to “media time.” Each item of interactive content has a timeline for its playout; an instant of time on this timeline is called media time. In other words, the media time is a parameter referencing a point in the playout of an audio/video or audio content item. For example, a 30-minute program may have an interactive event at media time ten minutes and 41 seconds from the beginning of the program, or media time 10:41. The TPT can include an entry indicating the details of the event that is to occur at time 10:41. Once the receiving apparatus  20  determines the current timing relative to the start of the program, it can use the TPT to play out all subsequent events. 
     The reception apparatus  20  may determine the availability of an updated TPT by referring to a non-real-time (NRT) file in a FLUTE, such as a file version number indicated in a Transport Object Identifier (TOI). FLUTE is defined in RFC 3926, which is incorporated herein by reference in its entirety. In another embodiment, the reception apparatus  20  receives the updated TPT by posting a GET request to the TPT server  40  which remains pending until a new TPT is available. In another embodiment, the reception apparatus  20  periodically accesses a source of the TPT to determine whether a new TPT is available. Alternatively, the reception apparatus  20  accesses a source identified by the liveTrigger element described above. 
     Likewise, compact triggers may be available via an Internet-based server. As with TPT updates, the receiving apparatus may post a GET request to the TPT server  40  which remains pending until a new triggers is available. 
       FIG. 2  illustrates an embodiment of the reception apparatus  20 . The reception apparatus  20  is a digital television receiver device that may be incorporated into a television set or a set top box. The reception apparatus  20  includes a tuner/demodulator  202 , which receives content from one or more content sources such as a terrestrial broadcast or a cable television transmission. The reception apparatus  20  may also, or alternatively, receive content from a satellite broadcast. The tuner/demodulator  202  receives a transport stream (TS), which is demultiplexed by the demultiplexer  206  into audio and video (A/V) streams. The audio is decoded by an audio decoder  210  and the video is decoded by a video decoder  214 . Further, uncompressed A/V data may be received via an uncompressed A/V interface (e.g., a HDMI interface) that can be selectively utilized. 
     In one embodiment, the TS includes ancillary information such as one or more of caption data, TDOs, triggers, TPTs, etc. However, in other embodiments, the A/V content and/or a subset or all of the ancillary information may be received via the Internet  30  and a network interface  226 . 
     A storage unit  230  is provided to store NRT or Internet-delivered content such as Internet Protocol Television (IPTV). The stored content can be played by demultiplexing the content stored in the storage unit  230  by the demultiplexer  206  in a manner similar to that of other sources of content. The storage unit  230  may also store one or more TDOs, triggers, and TPTs acquired by the reception apparatus  20 . 
     The reception apparatus  20  generally operates under control of at least one processor, such as CPU  238 , which is coupled to a working memory  240 , program memory  242 , and a graphics subsystem  244  via one or more buses (e.g., bus  250 ). The CPU  238  receives closed caption data from the demultiplexer  206  as well as any other information such as TDO announcements and EPGs used for rendering graphics, and passes the information to the graphics subsystem  244 . The graphics outputted by the graphics subsystem  244  are combined with video images by the compositor and video interface (compositor)  260  to produce an output suitable for display on a video display. Further, the CPU  238  receives non-closed caption text data, as described above. 
     Further, the CPU  238  operates to carry out functions of the reception apparatus  20  including the processing of related triggers (e.g., included in the closed caption data), TDOs, TPTs, and browser operations. The browser operations include accessing a service specified by a URL given by the TDO or trigger. The CPU  238  further operates to execute script objects (control objects) contained in the TDO, its trigger(s), etc., using for example the DO Engine 
     Although not illustrated in  FIG. 2 , the CPU  238  may be coupled to any one or a combination of the reception apparatus  20  resources to centralize control of one or more functions. In one embodiment, the CPU  238  also operates to oversee control of the reception apparatus  20  including the tuner/demodulator  202  and other television resources. 
     A more processor-centric view of the reception apparatus  20  is illustrated in  FIG. 3 . Memory and storage  230 ,  240 , and  242  are depicted collectively as memory  310 . Further, a processor  300  includes one or more processing units such as CPU  238 . Similarly, the various demodulators, decoders, etc., that initially process digital television signals are collectively depicted as television receiver/tuner  320 . The reception apparatus  20  further includes a remote controller  360  which communicates with a remote controller receiver interface  340 . Additionally, the display  350  is connected to a display interface  330 , which includes for example the uncompressed A/V interface and/or compositor  260 , and is either a display integral to the reception apparatus  20  as in a television set or a connected display device as in the case where the reception apparatus  20  is integrated into a set-top box. 
     Memory  310  contains various functional program modules and data. The memory  310  stores the data used by the reception apparatus  20 . The memory  310  within the reception apparatus  20  can be implemented using disc storage form as well as other forms of storage such as non-transitory storage devices including for example network memory devices, magnetic storage elements, magneto-optical storage elements, flash memory, core memory and/or other non-volatile storage technologies. It should be noted that the use of the term “non-transitory” in the present disclosure is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). When a TDO  316  is received, the TDO  316  is stored in the memory  310 . The TDO execution is carried out by a DO Engine  312 . The TDO, when executed by the DO Engine  312  presents supplemental content based on one or more triggers associated with the TDO and/or timing information stored in an associated TPT  318 . The memory  310  also stores the TPT  318 , which in one embodiment, defines one or more parameters for each trigger associated with the TDO. 
       FIG. 4A  provides an overview of an exemplary method for processing triggers by, for example, the reception apparatus  20 . In step S 402 , the reception apparatus  20  receives content (e.g., a television program) from a content source, such as the content source  10 . The received content is presented to the user of the reception apparatus  20 , in step S 404 . In step S 406 , the reception apparatus  20  extracts a compact trigger from closed caption data associated with the received content. The reception apparatus  20  processes the compact trigger, in step S 408 , to determine a location of a TPT. 
     In step S 410 , the reception apparatus  20  retrieves the TPT from the determined location and stores the TPT in a first memory of the reception apparatus  20 . Further, in step S 412 , the reception apparatus  20  processes the retrieved and stored TPT to identify necessary resources, including triggered declarative objects (TDOs), associated with the TPT. In another embodiment, the location of one or more necessary resources are identified by one or more separate compact triggers. The determined necessary resources are subsequently retrieved and stored in a second memory of the reception apparatus  20  in step S 414 . In step S 416 , the reception apparatus  20  determines a media time or waits for a compact trigger identifying an event. When a media time is reached and/or a compact trigger identifies an event, in step S 418 , the reception apparatus processes an event such as performing an operation on a declarative object (e.g., a TDO) or having the declarative object perform a function based on the data in the TPT. It should be noted that the event processed in step S 418  could correspond to either a type 1 command which the reception apparatus  20  (e.g., the DO Engine  312 ) knows how to execute or a type 2 command which the reception apparatus  20  passes to the TDO for execution. The first and second memories may correspond to the same memory such as different portions of the storage  230  or working memory  240 , or discrete memories. 
     While triggers must be tightly time-synchronized to the audio/video content (e.g., to coincide with an ad boundary or scene change), the TPT can be delivered far in advance of the events it describes. Because the reception apparatus  20  can collect or download the TPT prior to its use over a period time such as seconds or minutes beforehand, use of the Internet for transport of the TPT becomes feasible. 
     In one embodiment, the TDO is downloaded from the TDO server  50  and the TPT is downloaded from the TPT server  40  in response to receiving one or more triggers associated with currently received content. For example, the reception apparatus  20  receives a first compact trigger that identifies the location of the TPT. The reception apparatus  20  downloads the TPT from the TPT server  40  in response to receiving the first compact trigger. Subsequently, the reception apparatus  20  processes the TPT and determines that a TDO is a necessary resource. In one embodiment, the reception apparatus  20  determines that the TDO is a necessary resource based on the inclusion of the TDO location in the TPT. In response, the reception apparatus  20  retrieves the TDO from the TDO server  50 . In another embodiment, the reception apparatus  20  receives a second compact trigger that identifies the location of the TDO. It should be noted that in the case of receiving the second compact trigger, the order in which the triggers identify the locations of the TPT and TDO can be reversed. 
     In yet another embodiment, the reception apparatus  20  receives a compact trigger that identifies the location of the TDO. The reception apparatus  20  retrieves the TDO from the location identified by the compact trigger. Subsequently, after the TDO is executed, the TDO itself causes the download of an associated TPT. 
     As noted above, in one embodiment, once the Internet address (URL) of the TPT server is identified by the trigger, the reception apparatus  20  uses it to acquire the TPT. Upon reception of the TPT, various other referenced assets (e.g., TDOs, files, multimedia assets, etc.), are retrieved by the reception apparatus  20  and stored in memory for possible later use. Once the media time is known, the reception apparatus  20  begins processing the TPT to see if there are any “type 1” or “type 2” commands that are ready for execution. 
     In step S 418 , when the reception apparatus  20  receives a trigger associated with a type 1 command (e.g., to execute the TDO), the DO Engine  312 , running on the processor  300 , executes the TDO. When the reception apparatus  20  receives a trigger associated with a type 2 command in step S 418 , while the TDO is being executed, the reception apparatus  20  passes the trigger data to the TDO, which retrieves the at least one parameter associated with the trigger event stored in the TPT based on information (e.g., a tag value, media time, etc.) included in the trigger associated with the type 2 command. In another embodiment, the DO Engine  312  retrieves the at least one parameter and passes the retrieved at least one parameter to the TDO. The TDO performs a function based on the at least one parameter retrieved. 
       FIGS. 4B and 4C  provide more detailed illustrations of the retrieval of the TPT and other necessary resources, according to one embodiment. Upon reception of a trigger either via the broadcast emission or via an interaction with the ACR system  60 , the reception apparatus  20  is expected to access the files referenced by the URL in the locator_part of the Trigger (the portion to the left of the “?”). As described above, two file delivery paths are possible, depending on whether or not the reception apparatus  20  has access to the full broadcast Transport Stream. 
       FIG. 4B  illustrates a case where the full TS is available to the reception apparatus  20 , which has no, or poor, Internet access. The trigger processing begins at step S 430 , at which time the reception apparatus  20  processes a broadcast virtual channel&#39;s Program Map Table (PMT) to discover the coordinates of an associated IP subnet. In step S 432 , the reception apparatus  20  processes a Service Signaling Channel (SSC) of the associated IP subnet to retrieve a Service Map Table (SMT). In step S 434 , the reception apparatus  20  discovers the coordinates of a FLUTE session based on the retrieved SMT. The reception apparatus  20  acquires a FLUTE File Delivery Table (FDT) for the FLUTE session, in step S 436 , which yields a list of content items each with a Content-Location value. In step S 438 , the reception apparatus  20  compares the locator_part of the Trigger against the Content-Location values until a match is found. In step S 440 , the reception apparatus  20  retrieves the file(s) associated with the matched Content-Location value to find the TPT. In step S 442 , the reception apparatus  20  retrieves any other files referenced by the TPT from the FLUTE session. 
       FIG. 4C  illustrates a case where good Internet access is available. The trigger processing begins at step S 450 , at which time the reception apparatus  20  performs an Internet http GET using the locator_part of the trigger. In one embodiment, the Internet http GET is performed using a spread algorithm. In step S 452 , the reception apparatus  20  processes the returned TPT to discover and retrieve other content items that may be needed. 
     In one embodiment, when the reception apparatus  20  has access to both the full TS and good Internet access, the reception apparatus  20  defaults to retrieving the TPT via the full TS to reduce load on the Internet server. In other embodiments, the reception apparatus  20  defaults to retrieving the TPT via the Internet or selects between the full TS and Internet server based on predetermined criteria (e.g., based on the time required to retrieve the TPT via the full TS and the Internet, whether the Internet connection is being used by another process of the reception apparatus  20  such as a software update, etc.). 
       FIG. 4D  provides an overview of another exemplary method for processing triggers by, for example, the reception apparatus  20 . In step S 460 , the reception apparatus  20  receives content (e.g., a television program) from a content source, such as the content source  10 . The received content is presented to the user of the reception apparatus  20 , in step S 462 . In step S 464 , the reception apparatus  20  receives a compact trigger associated with the received content. The reception apparatus  20  processes the compact trigger, in step S 466 , to determine a location of a TPT. In step S 468 , the TPT is retrieved from the determined location and stored in a first memory. In step S 470 , the reception apparatus  20  determines whether to process the at least one event included in the TPT based on one or a combination of a protocol version and one or more capabilities defined in the TPT. 
     In a further embodiment, the reception apparatus  20  may be further configured to perform one or more of the steps described above with respect to  FIG. 4A . One or a combination of the steps discussed above with respect to  FIG. 4A  may be performed before or after the determination in step S 470 . For example, the reception apparatus  20  may be configured to process the TPT to identify necessary resources, including TDOs, associated with the TPT. In another embodiment, the location of one or more necessary resources are identified by one or more separate compact triggers. The determined necessary resources are subsequently retrieved and stored in a second memory of the reception apparatus  20  as discussed with respect to step S 414  above. 
     Further, similar to  FIG. 4A , the reception apparatus  20  may further determine a media time or wait for a compact trigger identifying an event. When a media time is reached and/or a compact trigger identifies an event, the reception apparatus processes an event such as performing an operation on a declarative object (e.g., a TDO) or having the declarative object perform a function based on the data in the TPT. As discussed above, the event processed could correspond to either a type 1 command which the reception apparatus  20  (e.g., the DO Engine  312 ) knows how to execute or a type 2 command which the reception apparatus  20  passes to the TDO for execution. Further, the first and second memories may correspond to the same memory such as different portions of the storage  230  or working memory  240 , or discrete memories. 
       FIG. 5  is a more detailed illustration of an exemplary method for processing a trigger associated with a type 2 command (e.g., a “lifecycle” or “DO engine” command) using the DO Engine. In step S 502 , the DO Engine  312  determines whether a trigger of associated with the type 2 command (e.g., a “DO event” command) has been received. In one embodiment, the DO Engine  312  determines the type of the trigger based on whether the trigger specifies a command to be executed by the DO Engine  312 . For example, if the trigger includes a tag value that has been assigned to a command to be executed by the DO Engine  312 . In other embodiments, the DO Engine  312  determines whether a trigger is associated with a type 1 or type 2 command based on information included in the TPT entry. For example, the TPT entry itself can including information specifying that it corresponds to a type 1 or type 2 command. In another example, the DO Engine  312  determines whether the TPT entry includes a DO Engine command. 
     When the trigger associated with a type 2 command is determined to be received in step S 502 , the DO Engine extracts information included in the trigger in step S 504 . In one embodiment, the trigger information includes one or a combination of a TDO identifier (e.g., a TDO URL) and a reference to a TPT and/or one or more table entries containing parameters and data associated with this trigger event. The TDO identifier can be any unique identifier such as a reference number, URL, symbol, or other representation. The reference can be tag value such as an index number (small integer) or a media time. In some embodiments, the trigger only includes the reference information. 
     In step S 506 , the DO Engine determines whether the trigger is associated with a currently executing TDO based on the extracted TDO identifier. When, the trigger is determined to be associated with the currently executing TDO, in step S 508 , a reference (e.g., a tag value) extracted from the trigger is provided to the TDO, via a trigger application program interface (API) function. The tag value may be extracted with the TDO identifier or at any time prior to the tag value being provided to the TDO. 
     When the trigger is determined not to be associated with the currently executing TDO, in one embodiment, the trigger is discarded and the DO Engine  312  returns to step S 502  and waits for receipt of the next trigger associated with the type 2 command. Alternatively, the DO Engine  312  may temporarily suspend, or terminate, the currently executed TDO and execute a TDO associated with the trigger before proceeding the step S 508 . For example, in one embodiment, when the trigger is determined not to be associated with the currently executing TDO, the currently executing TDO is terminated or suspended and the TDO associated with the trigger is executed. When the currently executing TDO is suspended, execution of the suspended TDO is resumed when a trigger associated with the suspended TDO is later received. 
       FIG. 6A  illustrates an example of triggers delivered in association with two programming segments. In this example, both segments are “pre-produced,” meaning that the content is not from a live broadcast; interactive elements have been added in post-production. 
     As shown, a short time prior to the occurrence of programming segment  1 , a “pre-load” trigger is delivered to allow the reception apparatus  20  an opportunity to acquire the TPT and interactive content associated with programming segment  1 . Delivery of a pre-load trigger is optional; if not transmitted, each reception apparatus  20  is expected to use the first trigger it sees within the segment to acquire the content. 
     Triggers are sent throughout segment  1 , as shown, to indicate the current Media Time relative to the segment. Note that there is no requirement that the first frame of the segment be associated with Media Time zero, although such a practice may be common and helpful. Periodic delivery of Media Time Triggers is necessary to allow any reception apparatuses  20  which are just encountering the channel to synchronize and acquire the interactive content. 
     Just prior to the beginning of segment  2 , a pre-load Trigger for that upcoming segment is sent. 
     Note that in the case of pre-produced content (i.e., non-live), in one embodiment, the TPT that the reception apparatus  20  acquires after processing the first Trigger defines the timing of all elements of the interactive experience for that segment. All that is needed for the reception apparatus  20  and TDO to play out the interactive elements is the knowledge of the media timing; the TPT describes interactive events relative to Media Time. 
     For the case of live content, the TPT still contains data and information pertinent to different interactive events, however the timing of playout of those events cannot be known until the action in the program unfolds during the broadcast. For the live case, the “event-timing” function of the Trigger is utilized. In this mode, the Trigger signals that a specified interactive event in the TPT is to be re-timed to a specified new value of Media Time. Alternatively, the Trigger can indicate that a certain event is to be executed immediately.  FIG. 6B  illustrates the live-event case. 
     The example in  FIG. 6B  shows a program segment called “segment  3 ” with nine Triggers. The function of each of the numbered triggers is as follows: 
     Trigger  601  is a pre-load Trigger referencing the directory where the files for segment  3  may be acquired. Trigger  602  is a Media Time Trigger used to establish the playout timing for segment  3 . Trigger  603  is an event re-timing Trigger indicating that the event with event_id=2 in the TPT is to be re-timed to occur at Media Time  240 . The hatched area indicates the time interval prior to  240  over which Trigger  403  may be delivered to the reception apparatus  20 . Trigger  604  is another Media Time Trigger. Trigger  605  is an event re-timing Trigger indicating that the event with event_id=5 in the TPT is to be re-timed to occur at Media Time  444 . Triggers  606  and  607  are additional Media Time Triggers. Trigger  608  is an event Trigger indicating that the event with event_id=12 in the TPT is to be executed immediately. Further, Trigger  609  is an event re-timing Trigger indicating that the event with event_id=89 in the TPT is to be re-timed to occur at Media Time  900 . 
     As illustrated in  FIGS. 6C and 6D , in one embodiment, the TPT includes a primary key (e.g., a tag element, media time, etc.) that associates each element (row) in the table with an associated trigger event. Each trigger, in turn, will refer to a particular event in the TPT by means of this key. 
       FIG. 6C  illustrates a TPT  616  which, according to one embodiment, only contains parameters for a particular TDO (e.g., TDO  159 ). In one embodiment, prior to executing the TDO whose ID is 159, the reception apparatus  20  downloads the TDO itself along with associated files, one of which is the TPT. The TDO has script-level access to the TPT. As noted above, depending on the embodiment, the TPT is downloaded prior to or after the TDO, the TDO is downloaded from a location identified by the TPT, the TPT is downloaded from a location identified by the TDO, etc. 
     A TS  612  carrying content is associated with a plurality of events identified by triggers  614 A- 614 F. The triggers  614 A- 614 C and  614 F are associated with type 1 commands; and triggers  614 D and  614 E are associated with type 2 commands. The triggers associated with type 1 commands are processed by the DO Engine  312 , while the triggers associated with type 2 commands are processed by a TDO. 
     In  FIG. 6C , the reception apparatus  20  receives the triggers  614 A and  614 B, which identify the locations of the TPT  616  and TDO  159 , respectively. The reception apparatus  20  retrieves and stores the TPT  616  and TDO  159  based on the identified locations. It should be noted that the TPT  616  and TDO  159  can be received in any order. Further, in other embodiments, the TPT  616  identifies the location of the TDO  159  or the TDO  159  identifies the location of the TPT  616 . 
     Each of triggers  614 D and  614 E is associated with a row (or element) in the TPT, such as TPT  616 , and includes a reference to a specific entry in the TPT using, for example, a tag value. The DO Engine  312  extracts a tag value from each of the triggers  614 D and  614 E, which are associated with type 2 commands, and provides the extracted tag value to a currently executed TDO. The TDO uses the tag value to determine at least one parameter that is associated with the trigger. Then, as noted above, the TDO performs a function based on the retrieved at least one parameter. It should be noted that the reference to the TPT entry is not limited to a tag value and can be any symbol or representation that can be used to reference an entry in the TPT. 
     Further, in one embodiment, predetermined tag values (e.g., tag values below 16) are associated with predetermined commands to be executed by the DO Engine  312 . Accordingly, certain triggers such as a subset or all triggers associated with type 1 commands need not be associated with a row (or element) in the TPT. For example, when the reception apparatus  20  receives the trigger  614 C with a tag value of 5, the reception apparatus  20  executes a TDO  159  that is stored in the reception apparatus  20 . In another example, when the reception apparatus  20  receives a trigger  614 F with a tag value of 7, the DO Engine  312  terminates, or suspends, the TDO  159 . Accordingly, in these examples, the tag value 5 is specified as an “Execute” command and the tag value 7 is specified as a “Terminate” or “Suspend” command. 
     In one embodiment, the predetermined tag values are specified in a standard as commands to be executed by the DO Engine  312 . The specified basic trigger types to be executed by the DO Engine  312  itself include “Register,” “Execute,” “Suspend,” “Resume,” and “Terminate.” Any other tag values, symbols, or representations may be reserved for DO Engine commands. Further, in other embodiments, the triggers associated with type 1 commands refer to entries in the TPT  616  or a separate TPT to provide any parameters required to execute a command. For example, when the trigger is associated with a type 1 command that is “load TDO,” the trigger includes the location (e.g., a URL), or a reference to the location (e.g., entry in a TPT) of the TDO so that it can be acquired by the reception apparatus  20 . That is, in other embodiments, a trigger associated with a type 1 command may include a reference to an entry in a TPT that identifies the location of a TDO to be retrieved and executed, as illustrated for example in  FIG. 6D . 
     Further, as illustrated in  FIG. 6C , the TPT  616  includes TPT entries (e.g., tag values 19 or 21) that are utilized by the TDO  159  when the specified media times have arrived. The arrival of a specified media time may be determined based on the receipt of a trigger including the specified media time or by the reception apparatus  20 . For example, the TDO  159  monitors the current media time of the received content and processes parameters when the media time equals 15000 and 18500, respectively, Alternatively, the DO Engine  312  monitors the current media time and passes the tag value to the TDO  159  at the appropriate time. 
     In one embodiment, the media time represents the number of milliseconds that have elapsed in the received content. However, any other unit of time could be used to represent the media time. Further, any one or a plurality of the triggers  614 A- 614 F can include additional parameters such as media time information for use by the reception apparatus  20 , DO Engine  312 , and/or TDO  159 , as a reference point for determining the current media time in the received content. 
       FIG. 6D  illustrates an exemplary TPT that contains parameters for triggers associated with type 1 and type 2 commands. It should be noted that separate TPTs for the type 1 and type 2 commands could alternatively be provided. Triggers  654 A,  654 B,  654 D, and  654 E are associated with type 1 commands; and trigger  654 C is associated with a type 2 command. As described above, in one embodiment, the reception apparatus  20  retrieves the TPT  656  based on the trigger  654 A, which identifies the location of the TPT  656 . Further, the reception apparatus  20  processes the TPT  656  and determines that necessary resources for the TPT include TDO 1  and TDO 2 . Subsequently, the reception apparatus  20  retrieves the TDO 1  and TDO 2  based on the locations identified in the TPT  656 . 
     When the reception apparatus receives trigger  654 B, in one embodiment, the DO Engine  312  determines that the trigger is associated with a type 1 command based on the tag value falling within a predetermine range of tag values (e.g., tag value less than 16), as described above. In another embodiment, the DO Engine  312  determines that the trigger is associated with the type 1 command based on the presence of a command such as “Execute” or other identifying information in the corresponding TPT entry. The reception apparatus  20  executes the TDO 1  in response to receiving the trigger  654 B. 
     When the reception apparatus  20  receives the trigger  654 C, the DO Engine  312  extracts the tag value from the trigger  654 C and determines that the trigger is associated with a type 2 command. In one embodiment, the DO Engine  312  determines that the trigger  654 C is associated with a type 2 command based on the tag value falling outside of a predetermined range (e.g., tag value is 16 or greater). In other embodiments, the DO Engine  312  makes the determination based on information included in the TPT  656 . The DO Engine  312  provides the extracted tag value to the TDO 1 . The TDO 1  uses the tag value to determine at least one parameter that is associated with the trigger. Further, the TDO 1  performs a function based on the at least one parameter. 
     As illustrated in  FIG. 6D , the reception apparatus  20  receives triggers  654 D and  654 E. These triggers provide the reception apparatus  20 , DO Engine  312 , and/or a TDO a reference point for determining the current media time in the received content. The DO Engine  312  and/or an executing TDO monitors the current media time to determine whether any entries in the TPT  656  should be processed. For example, when the DO Engine  312  determines that the current media time is 20000, the DO Engine executes TDO 2  in accordance with the TPT entry with the tag value 21. In another example, when the DO Engine  312  or TDO 1  determines that the current media time is 15000, the TDO 1  is caused to process, or processes, the parameters included in the TPT entry with the tag value 19. In another embodiment, the media time information included in the trigger itself is used to identify a TPT entry. 
     The TPT  606  illustrated in  FIGS. 6C and 6D  contains references to image files. As illustrated in  FIG. 6C , one graphic is associated with each tag value or media time. However, the TPTs  606  and  656  are not so limited and can refer to one or a combination of different media types such as audio, video, an image, and/or one or more interactive elements. As noted above, predetermined tag values (e.g., below 16) may be specified in a standard as commands to be executed by the DO Engine. Therefore, in one embodiment, the TPT only contains entries for tag values 16 and above. In another embodiment, TPT entries are provided for all tag values. 
     For example, when the reception apparatus  20  receives a trigger  614 D with a tag value of 16, the DO Engine  312  passes the tag value 16 to the TDO  159 , which is currently executing. The DO Engine  312  passes the tag value by calling a Trigger API function, which is supported by the DO Engine  312 , and delivers the tag value to the TDO  159 . The Trigger API function may be included in the DO Engine  312  or a separate programming component of the reception apparatus  20 . The TDO  159  accesses the TPT  616  and determines the parameters associated with the trigger are “product1.jpg” and the numbers  104  and  226 . In one embodiment, the function performed by the TDO  159  based on the determined parameters includes rendering the image file “product1.jpg” at location X, Y ( 104 ,  226 ) on the display  350 . 
     The TPT, however, is not limited to including information on image files and position, and can include other parameters such as (as mentioned) a media time that designates the timing of any given interactive elements, validity information for defining an expiration date of the trigger, capability codes that allow the reception apparatus  20  to determine whether it is capable of providing the supplemental content associated with the TPT or a specific TPT entry, etc. The TPT could include a URL the TPT could use to fetch an updated parameter set from an Internet server, where the data set represents a weather report, sports scores, player statistics, or any other time-sensitive data. As another example, the TPT may include one or more capability codes that indicate the TPT can only be processed by a reception apparatus supporting “ATSC 2.7+,” a minimum requirement code such as support for certain media formats and decoders, essential and non-essential capabilities, etc. 
     Note that, in one embodiment, the DO Engine  312  itself does not try to interpret anything carried in a given row of the TPT instance, such as the row identified with Tag Value 21 in TPT  616 . The information contained in the TPT instance is known and interpretable only to the TDO it is designed to work with. Therefore, the number and types of parameters included in a TPT may be customizable based on the requirements of an associated TDO. In other words, the TPT is not limited to including a predetermined set of parameters and may contain any parameter that is required by a particular TDO. 
       FIG. 7  illustrates an information providing apparatus  700 , which may be included in the content source  10 , TPT server  40 , TDO server  50 , ACR system  60 , or a stand-alone device. As illustrated in  FIG. 7 , the information providing apparatus  700  includes a memory  710  and a communication unit  720 . The memory  710  can be implemented using disc storage form as well as other forms of storage such as non-transitory storage devices including for example network memory devices, magnetic storage elements, magneto-optical storage elements, flash memory, core memory and/or other non-volatile storage technologies. Further, the communication unit  720  can be implemented using any one or a combination of a terrestrial broadcast transmitter, a cable broadcast transmitter, a satellite uplink transmitter, a network interface (e.g., WLAN card, Ethernet card, etc.), or the like. 
     The memory  710  is configured to store a TPT, which includes at least one event associated with one or a combination of a trigger identifier and a media time of content to be provided to a reception apparatus. The communication unit  720  provides the TPT stored in the memory  710  to the reception apparatus  20 . For example, the communication unit  720  provides the TPT to the reception apparatus  20  via the TS or the Internet. The TPT is provided at a location identified in a trigger included within closed caption data associated with the content provided to the reception apparatus. 
       FIG. 8  is a block diagram showing an example of a hardware configuration of a computer  800  configured to function as any one or a combination of the content source  10 , reception apparatus  20 , TPT server  40 , TDO server  50 , ACR system  60 , and information providing apparatus  700 . 
     As illustrated in  FIG. 8 , the computer  800  includes a central processing unit (CPU)  802 , read only memory (ROM)  804 , and a random access memory (RAM)  806  interconnected to each other via one or more buses  808 . The one or more buses  808  is further connected with an input-output interface  810 . The input-output interface  810  is connected with an input portion  812  formed by a keyboard, a mouse, a microphone, remote controller, etc. The input-output interface  810  is also connected to a output portion  814  formed by an audio interface, video interface, display, speaker, etc.; a recording portion  816  formed by a hard disk, a non-volatile memory, etc.; a communication portion  818  formed by a network interface, modem, USB interface, fire wire interface, etc.; and a drive  820  for driving removable media  822  such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc. 
     According to one embodiment, the CPU  802  loads a program stored in the recording portion  816  into the RAM  806  via the input-output interface  810  and the bus  808 , and then executes a program configured to provide the functionality of the one or combination of the content source  10 , reception apparatus  20 , TPT server  40 , TDO server  50 , ACR system  60 , and information providing apparatus  700   
     The various processes discussed above need not be processed chronologically in the sequence depicted as flowcharts; the steps may also include those processed parallelly or individually (e.g., in paralleled or object-oriented fashion). 
     Also, the programs may be processed by a single computer or by a plurality of computers on a distributed basis. The programs may also be transferred to a remote computer or computers for execution. 
     Furthermore, in this specification, the term “system” means an aggregate of a plurality of component elements (apparatuses, modules (parts), etc.). All component elements may or may not be housed in a single enclosure. Therefore, a plurality of apparatuses each housed in a separate enclosure and connected via a network are considered a network, and a single apparatus formed by a plurality of modules housed in a single enclosure are also regarded as a system. 
     Also, it should be understood that this technology when embodied is not limited to the above-described embodiments and that various modifications, variations and alternatives may be made of this technology so far as they are within the spirit and scope thereof. 
     For example, this technology may be structured for cloud computing whereby a single function is shared and processed in collaboration among a plurality of apparatuses via a network. 
     Also, each of the steps explained in reference to the above-described flowcharts may be executed not only by a single apparatus but also by a plurality of apparatuses in a shared manner. 
     Furthermore, if one step includes a plurality of processes, these processes included in the step may be performed not only by a single apparatus but also by a plurality of apparatuses in a shared manner. 
     Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced otherwise than as specifically described herein.