US20020091816A1 - Broadcast data access system for multimedia clients in a broadcast network architecture - Google Patents
Broadcast data access system for multimedia clients in a broadcast network architecture Download PDFInfo
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- US20020091816A1 US20020091816A1 US09/219,714 US21971498A US2002091816A1 US 20020091816 A1 US20020091816 A1 US 20020091816A1 US 21971498 A US21971498 A US 21971498A US 2002091816 A1 US2002091816 A1 US 2002091816A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/435—Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/16—Arrangements for broadcast or for distribution of identical information repeatedly
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
- H04H60/61—Arrangements for services using the result of monitoring, identification or recognition covered by groups H04H60/29-H04H60/54
- H04H60/65—Arrangements for services using the result of monitoring, identification or recognition covered by groups H04H60/29-H04H60/54 for using the result on users' side
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/235—Processing of additional data, e.g. scrambling of additional data or processing content descriptors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/434—Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream
- H04N21/4348—Demultiplexing of additional data and video streams
- H04N21/4349—Demultiplexing of additional data and video streams by extracting from data carousels, e.g. extraction of software modules from a DVB carousel
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/435—Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
- H04N21/4351—Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream involving reassembling additional data, e.g. rebuilding an executable program from recovered modules
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
- H04N21/4508—Management of client data or end-user data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/45—Management operations performed by the client for facilitating the reception of or the interaction with the content or administrating data related to the end-user or to the client device itself, e.g. learning user preferences for recommending movies, resolving scheduling conflicts
- H04N21/454—Content or additional data filtering, e.g. blocking advertisements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/80—Generation or processing of content or additional data by content creator independently of the distribution process; Content per se
- H04N21/81—Monomedia components thereof
- H04N21/8166—Monomedia components thereof involving executable data, e.g. software
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
- H04H60/35—Arrangements for identifying or recognising characteristics with a direct linkage to broadcast information or to broadcast space-time, e.g. for identifying broadcast stations or for identifying users
- H04H60/46—Arrangements for identifying or recognising characteristics with a direct linkage to broadcast information or to broadcast space-time, e.g. for identifying broadcast stations or for identifying users for recognising users' preferences
Definitions
- the present invention relates generally to a broadcast data access system, and more particularly to an architecture for supporting applications that receive broadcast data from a data carousel over a broadcast network.
- multimedia clients do not have enough resources to store all of the data that is being broadcast over the network. Even if the client could store all of the data, there is no guarantee that the client will receive an error-free copy of the data in a single transmission of the data. Moreover, the client has no way of requesting that a server resend missing or defective data. Since the data is being sent to many clients, it might also be prohibitive to resend missing or defective data to each of the clients which request it.
- a broadcast data carousel is commonly used for transporting data in a broadcast environment.
- This underlying mechanism for transporting data is defined in the MPEG-2 DSM-CC specification (i.e., ISC/IEC 13818-6).
- the server uses this mechanism to send data over a period of time so that a client which is interested in the data may receive it only when it is required. If a client misses some of the data or receives defective data, it waits for the next broadcast of the data to receive any data that it may need.
- a Broadcast File System provides a layer on top of the broadcast data carousel that hides the details of the underlying transport mechanism from the server and clients.
- BFS creates a mapping between the carousel/file number and a module name.
- the server and clients view the broadcast data as a standard hierarchical file system similar to files found on a disk operating system.
- a broadcast data access system for receiving broadcast data from a data carousel in a simple, efficient, and flexible manner. It should support multiple data sources between the broadcast network and the multimedia client, such that each source can receive a different form of encoded broadcast data.
- the broadcast data access system should be able to efficiently process data packets received in a non-sequential order, as well as simultaneously fulfill multiple requests for the same data packets by different applications. To lessen processing overhead, filters are dynamically installed on the client.
- the present invention should provide a method for downloading and synchronizing a directory module with the content of the data carousel being broadcast to the client.
- a broadcast data access system for receiving broadcast data by applications residing on a multimedia client, where the broadcast data is a set of modules on a data carousel that are being broadcast over a broadcast network.
- the broadcast data access system includes an interest manager configured to store a plurality of interests, such that each interest identifies an available module on the data carousel being requested by an application.
- the system further includes at least one application having registered an interest for a first module with the interest manager, and a dispatcher distributing the first module to the requesting application by accessing the interest manager.
- FIG. 1 is a diagram depicting the basic components in a typical broadcast file system in accordance with the present invention
- FIG. 2 is a data flow diagram illustrating a preferred embodiment of the broadcast data access system of the present invention
- FIG. 3 is a block diagram showing the software architecture for the broadcast data access system of the present invention which resides on each multimedia client;
- FIG. 4 is a diagram showing dynamic filter installation in accordance with the present invention.
- FIGS. 5A and 5B are a detailed flowchart illustrating a preferred embodiment of the data block processor of the present invention.
- FIG. 6 is a detailed flowchart illustrating a preferred embodiment of a portion of the data block processor that handles downloading and synchronizing the BFS directory onto the client.
- a Broadcast File System 10 provides an architecture for delivering various types of data from a BFS server 12 (or group of servers) to a plurality of multimedia clients 14 over a broadcast network 16 . It is also envisioned that a two-way communication network could be used in conjunction with the broadcast file system 10 of the present invention.
- the underlying mechanism for transporting data across the network 16 relies on a broadcast data carousel which is defined in the MPEG-2 DSM-CC specification (i.e., ISC/IEC 13818-6).
- broadcast data is grouped into files that are subdivided into fixed-size data blocks and then broadcast in a non-sequential order using the data carousel mechanism.
- BFS 10 of the present invention provides a layer on top of the broadcast data carousel that hides the details of this underlying transport mechanism from the server 12 and clients 14 .
- individual data files are called modules. Since modules are identified by numbers (not names), BFS 10 creates a mapping between file numbers and module names. In this way, the server 12 and clients 14 of BFS 10 view these modules in a standard hierarchical file system similar to files found on a disk operating system.
- BFS server 12 is the component responsible for storing, assembling and delivering modules across the network 16 . While the following discussion is provided with reference to one data carousel, it is readily understood that the explanation is applicable to more than one data carousel.
- a top level data carousel contains at least one module known as the BFS directory which includes the module names for all of the other modules on this or any other data carousel.
- BFS server 12 creates a module name (i.e., identifier) for each new module and then updates the BFS directory structure. Similarly, when modules are updated and/or deleted from the data carousel, the BFS directory structure is updated by BFS server 12 .
- the network 16 may employ any underlying transport protocol (e.g., MPEG transport and/or UDP/IP) which has the ability to deliver data packets across the network to the client.
- MPEG transport and/or UDP/IP transport protocol
- a broadcast data access system 30 of the present invention serves as the interface between the set of modules contained on the data carousel 32 and the various applications residing 34 on multimedia client 14 .
- the broadcast data access system 30 on each multimedia client 14 includes an interest manager 36 that is configured to store a plurality of interests.
- an application 34 registers an interest with the interest manager 36 (e.g., a first application registers a first interest requesting a first module from the data carousel).
- the term Aapplication@ signifies any software module, including the operating system, that may reside on the multimedia client 14 .
- a dispatcher 38 accesses the interest manager 36 to determine if any application residing on that client 14 has requested that module, and if so distributes that module to the appropriate application 34 .
- data access system 30 supports at least two data sources: a QAM modulated in-band source and a QPSK modulated out-of-band source. In the case of a set-top box, these multiple data sources may be received via an HFC connection. Since the data access system 30 is designed to support different types of data sources, it provides a data source processor 42 for each of these data sources. As data blocks arrive at the client, data source processor 42 performs source specific processing on each data block, including but not limited to, removing header information, verifying checksum and decompression.
- Data access system 30 currently incorporates three specific processors: a download information indication (DII) processor 44 which receives DSM-CC download information indication (DII) messages, cancel processor 46 which receives DSM-CC messages that indicate when a module has been removed from the data carousel, and data block processor 48 which receives all other types of data blocks.
- DII download information indication
- cancel processor 46 which receives DSM-CC messages that indicate when a module has been removed from the data carousel
- data block processor 48 which receives all other types of data blocks.
- TV manager 52 which provides the functionality to select and manipulate in-band data source.
- an application When an application requests to “open” (or retrieve) a module on the data carousel, it registers this request with the interest manager 36 .
- the interest manager 36 maintains a list of modules which the data access system 30 is currently interested in receiving from the data carousel. Thus, an interest exists for every application request.
- An identifier e.g., source id, carousel id, module id, version id, ect.
- An identifier that uniquely identifies the requested module as well as an identifier for the requesting application are stored in a data structure 37 associated with the interest manager 36 .
- an open file component 36 A of the interest manager 36 will interface with the BFS directory 50 to ensure that the requested module exists on the data carousel.
- DII messages contain a directory of all of the modules on the carousel and are periodically received (e.g., multiple times per second) by the DII processor 44 .
- the open file component 36 A also verifies that the module exists in accordance to the most recently received DII message. Next, it checks that the version number for the module retrieved from the BFS directory matches the version for that module included in the DII message.
- the interst manager 36 ensures that the applications request to open a module is synchronized with the module contained on the data carousel. Because modules are delivered on multiple sources at different rates, it is important to implement this synchonization process; otherwise an application may read data from either an older version of the module or possibly even a newer version of the module. It is also envisioned that a filter may be dynamically installed by the open file component 36 A that allows DII messages for this carsousel to pass through to the dispatcher 38 . Once the synchronization process is complete, the filter is removed so that DII messages will not unnecessarily pass through to the dispatcher 38 .
- interest manager 36 To more efficiently process incoming data blocks, interest manager 36 also dynamically installs filters for each requested interest. Referring to FIG. 4, when an application 34 registers an interest, the interest manager 36 installs a filter in the corresponding data source processor 42 . A module identifier encapsulated in each data block is compared to each registered interest. Data blocks not associated with any registered interest are discarded before any unnecessary processing occurs on the client. In this way, only data blocks associated with a registered interest undergo pre-processing in the data source processor 42 and are allowed to pass through to the dispatcher 30 . Once all of the data blocks for a particular interest have been received by the client, interest manager 36 removes the filter for that interest.
- a data carousel broadcasts all of the data on the carousel before it re-broadcasts any of the data. Therefore, when an application makes a new data request, the response time depends on the data's location relative to where the carousel is in the broadcast cycle. For example, a carousel having ten data blocks may be currently broadcasting the fifth data block. An application that requests data contained in the seventh block will receive that data faster than an application that requests data contained in the ninth block. If it is the eighth block that is currently being broadcast, the reverse is true: an application that requests data contained in the ninth block will receive that data faster than an application that requests data contained in the seventh block.
- data block processor 48 reads the data from a data carousel as it is broadcast; it does not wait for the beginning of the data to begin reading. For instance, an application may be interested in a module contained in blocks 2 to 6 . If it starts reading as block 4 is broadcast, data block processor 48 copies the data in block 4 to the application's buffer and then reads the data in each successive block that is broadcast. Subsequent data blocks associated with the requested module (i.e., blocks 5 , 6 , 2 , and 3 ) are copied to the application's buffer, whereas data that is not part of the module (i.e., blocks 7 , 8 , 9 , 10 and 1 ) are discarded.
- FIGS. 5A and 5B are a flowchart showing a more detailed implementation of the data block processor 48 .
- Start block 100 begins the processing for each incoming data block.
- data block processor 48 interfaces with the interest manager 36 to retrieve a registered interest.
- Decision block 104 determines if the incoming data block matches this interest, and if so continues processing in block 106 . If the incoming data block does not match the registered interest, data block processor 48 retrieves the next interest. Because all of the interests are evaluated for each data block, multiple interests can be served by the same incoming data block.
- Decision block 106 compares the version number for each incoming data block to the expected version number contained in the BFS directory. This is important because a module can be changed on the carousel as individual data blocks for that module are being read by data access system 30 . If the version numbers match, then processing proceeds to decision block 110 . On the other hand, if the version number does not match, processing branches to an error subroutine 108 .
- decision block 110 determines if a data block falls within the desired range of data blocks. For each data blocks within the desired range, Block 112 sets a Read Block indicator. Data blocks outside the desired range are discarded in block 114 .
- Read Block indicator is an array data structure used to monitor which data blocks have been read from the data carousel. Each bit in the array represents a data block in the requested module, such that if the bit is on (i.e., set to 1), then the block has been read, but if the bit is off (i.e., set to 0), then the block has not been read. Using this indicator allows data block processor 48 to receive data blocks in any order from the data carousel, and thus eliminates any unnecessary memory copies.
- decision block 116 determines if an incoming data block has been previously received by the client. For previously unread data blocks, block 120 sets the appropriate bit in Read Block indicator and then copies the data block to the corresponding application buffer space (or alternatively placed in cache memory) in block 122 . On the other hand, previously read data blocks are discarded in block 118 . Decision block 124 evaluates whether all of the data blocks for a requested module have been read (i.e., all bits set to 1). Once all of the data block have been read, data block processor 48 interfaces with interest manager 36 to remove the interest and filter for that requested module in block 126 , but in either case processing continues by reading the next interest in block 102 . Once all of the interests have been evaluated with respect to an incoming data block, processing is completed for that data block.
- the BFS directory may not always be in synch with the content of the data carousel being broadcast to the client.
- a module including the BFS directory module
- the data block processor 48 also provides a method for downloading and synchronizing the BFS directory on the client.
- FIG. 6 is a flowchart showing a portion of the data block processor 48 that handles the downloading of the BFS directory.
- a DSM-CC user-to-network configuration message is received at the client which contains the source ID, carousel ID and module ID for the BFS directory.
- Block 140 installs a filter that allows (any version of) BFS directory data blocks to pass through the dispatcher 38 .
- the current version of the BFS directory is retrieved from the data carousel.
- BFS directory structure is only delivered over the out-of-band source (which by definition is guaranteed to be available to data access system 30 ), and thus this filter only need be applied to that data source.
- Decision block 144 determines when a BFS directory data block arrives, and if so block 146 reads and parses each incoming data block to construct the BFS directory structure. In the event an error occurs during the downloading process, decision block 148 returns processing to block 142 for re-installation of the initial BFS directory filter. This ensures that the current BFS directory is always downloaded from the data carousel.
- block 150 checks any registered interests against the newly downloaded BFS directory. At boot up, there will be no registered interests. However, for subsequently downloaded BFS directories, DII processor 44 interfaces with the interest manager 36 to verify registered interests. If a registered interest no longer exists or has been updated on the data carousel (as indicated by the newly downloaded BFS directory), then the interest is marked for deletion. Block 152 then installs (e.g., cached in memory) the newly downloaded BFS directory onto the client for use by data access system 30 .
- block 154 installs a different filter which only passes data blocks whose version number does not match the version number of the downloaded BFS directory.
- the version number will be modified, thereby allowing BFS directory data blocks to again pass through the dispatcher 38 .
- a new BFS directory can then be downloaded. In this way, data block processor 48 does not process redundant BFS directory information.
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Abstract
Description
- The present invention relates generally to a broadcast data access system, and more particularly to an architecture for supporting applications that receive broadcast data from a data carousel over a broadcast network.
- In a broadcast network architecture, various types of data can be delivered from a server to a group of multimedia clients. Typically, multimedia clients do not have enough resources to store all of the data that is being broadcast over the network. Even if the client could store all of the data, there is no guarantee that the client will receive an error-free copy of the data in a single transmission of the data. Moreover, the client has no way of requesting that a server resend missing or defective data. Since the data is being sent to many clients, it might also be prohibitive to resend missing or defective data to each of the clients which request it.
- A broadcast data carousel is commonly used for transporting data in a broadcast environment. This underlying mechanism for transporting data is defined in the MPEG-2 DSM-CC specification (i.e., ISC/IEC 13818-6). Using this mechanism, the server repeatedly sends data over a period of time so that a client which is interested in the data may receive it only when it is required. If a client misses some of the data or receives defective data, it waits for the next broadcast of the data to receive any data that it may need.
- A Broadcast File System (BFS) provides a layer on top of the broadcast data carousel that hides the details of the underlying transport mechanism from the server and clients. In particular, BFS creates a mapping between the carousel/file number and a module name. As a result, the server and clients view the broadcast data as a standard hierarchical file system similar to files found on a disk operating system.
- Therefore, it would be desirable to provide a broadcast data access system for receiving broadcast data from a data carousel in a simple, efficient, and flexible manner. It should support multiple data sources between the broadcast network and the multimedia client, such that each source can receive a different form of encoded broadcast data. In addition, the broadcast data access system should be able to efficiently process data packets received in a non-sequential order, as well as simultaneously fulfill multiple requests for the same data packets by different applications. To lessen processing overhead, filters are dynamically installed on the client. Lastly, the present invention should provide a method for downloading and synchronizing a directory module with the content of the data carousel being broadcast to the client.
- In accordance with the teachings of the present invention, a broadcast data access system is provided for receiving broadcast data by applications residing on a multimedia client, where the broadcast data is a set of modules on a data carousel that are being broadcast over a broadcast network. The broadcast data access system includes an interest manager configured to store a plurality of interests, such that each interest identifies an available module on the data carousel being requested by an application. The system further includes at least one application having registered an interest for a first module with the interest manager, and a dispatcher distributing the first module to the requesting application by accessing the interest manager.
- FIG. 1 is a diagram depicting the basic components in a typical broadcast file system in accordance with the present invention;
- FIG. 2 is a data flow diagram illustrating a preferred embodiment of the broadcast data access system of the present invention;
- FIG. 3 is a block diagram showing the software architecture for the broadcast data access system of the present invention which resides on each multimedia client;
- FIG. 4 is a diagram showing dynamic filter installation in accordance with the present invention;
- FIGS. 5A and 5B are a detailed flowchart illustrating a preferred embodiment of the data block processor of the present invention; and
- FIG. 6 is a detailed flowchart illustrating a preferred embodiment of a portion of the data block processor that handles downloading and synchronizing the BFS directory onto the client.
- The following description of the present invention is merely exemplary in nature and is in no way intended to limit the invention or its uses. Moreover, the following description, while depicting a broadcast data access system that is designed to reside on a conventional set top box, is intended to adequately teach one skilled in the art to make and use a similar architecture for a variety of consumer multimedia clients including, but not limited to, intelligent televisions, Internet terminals and advanced DVD players.
- A Broadcast File System10 (BFS), as depicted in FIG. 1, provides an architecture for delivering various types of data from a BFS server 12 (or group of servers) to a plurality of
multimedia clients 14 over a broadcast network 16. It is also envisioned that a two-way communication network could be used in conjunction with thebroadcast file system 10 of the present invention. The underlying mechanism for transporting data across the network 16 relies on a broadcast data carousel which is defined in the MPEG-2 DSM-CC specification (i.e., ISC/IEC 13818-6). Typically, broadcast data is grouped into files that are subdivided into fixed-size data blocks and then broadcast in a non-sequential order using the data carousel mechanism. However,BFS 10 of the present invention provides a layer on top of the broadcast data carousel that hides the details of this underlying transport mechanism from the server 12 andclients 14. Within a data carousel, individual data files are called modules. Since modules are identified by numbers (not names), BFS 10 creates a mapping between file numbers and module names. In this way, the server 12 andclients 14 of BFS 10 view these modules in a standard hierarchical file system similar to files found on a disk operating system. - BFS server12 is the component responsible for storing, assembling and delivering modules across the network 16. While the following discussion is provided with reference to one data carousel, it is readily understood that the explanation is applicable to more than one data carousel. A top level data carousel contains at least one module known as the BFS directory which includes the module names for all of the other modules on this or any other data carousel. As modules are added to the data carousel, BFS server 12 creates a module name (i.e., identifier) for each new module and then updates the BFS directory structure. Similarly, when modules are updated and/or deleted from the data carousel, the BFS directory structure is updated by BFS server 12. Applications residing on a
multimedia client 14 in turn utilize the BFS directory to access modules contained on the broadcast data carousel. The network 16 may employ any underlying transport protocol (e.g., MPEG transport and/or UDP/IP) which has the ability to deliver data packets across the network to the client. - A broadcast
data access system 30 of the present invention serves as the interface between the set of modules contained on thedata carousel 32 and the various applications residing 34 onmultimedia client 14. Referring to FIG. 2, the broadcastdata access system 30 on eachmultimedia client 14 includes aninterest manager 36 that is configured to store a plurality of interests. To receive broadcast data from thedata carousel 32, anapplication 34 registers an interest with the interest manager 36 (e.g., a first application registers a first interest requesting a first module from the data carousel). For purpose of this discussion, the term Aapplication@ signifies any software module, including the operating system, that may reside on themultimedia client 14. For each module received by themultimedia client 14, adispatcher 38 accesses theinterest manager 36 to determine if any application residing on thatclient 14 has requested that module, and if so distributes that module to theappropriate application 34. - A more detailed implementation of the broadcast
data access system 30 is shown in FIG. 3. Preferably,data access system 30 supports at least two data sources: a QAM modulated in-band source and a QPSK modulated out-of-band source. In the case of a set-top box, these multiple data sources may be received via an HFC connection. Since thedata access system 30 is designed to support different types of data sources, it provides adata source processor 42 for each of these data sources. As data blocks arrive at the client,data source processor 42 performs source specific processing on each data block, including but not limited to, removing header information, verifying checksum and decompression. - Once pre-processed by a
data source processor 42, data blocks are passed along (in DSM-CC format) to adispatcher 38.Dispatcher 38 may perform some additional data block verification (e.g., check payload length). However, based on the particular type of DSM-CC message, thedispatcher 38 is primarily responsible for directing each incoming data block to an appropriate processor.Data access system 30 currently incorporates three specific processors: a download information indication (DII)processor 44 which receives DSM-CC download information indication (DII) messages, cancelprocessor 46 which receives DSM-CC messages that indicate when a module has been removed from the data carousel, anddata block processor 48 which receives all other types of data blocks. For the in-band QAM channel,data access system 30 also interacts with aTV manager 52 which provides the functionality to select and manipulate in-band data source. - When an application requests to “open” (or retrieve) a module on the data carousel, it registers this request with the
interest manager 36. Theinterest manager 36 maintains a list of modules which thedata access system 30 is currently interested in receiving from the data carousel. Thus, an interest exists for every application request. An identifier (e.g., source id, carousel id, module id, version id, ect.) that uniquely identifies the requested module as well as an identifier for the requesting application are stored in adata structure 37 associated with theinterest manager 36. Once an interest has been registered by the anapplication 34, all data blocks that match that interest are processed by thedata block processor 48. - In addition to registering each application request, an open file component36A of the
interest manager 36 will interface with theBFS directory 50 to ensure that the requested module exists on the data carousel. Generally, DII messages contain a directory of all of the modules on the carousel and are periodically received (e.g., multiple times per second) by theDII processor 44. As part of this synchonization process, the open file component 36A also verifies that the module exists in accordance to the most recently received DII message. Next, it checks that the version number for the module retrieved from the BFS directory matches the version for that module included in the DII message. In this way, theinterst manager 36 ensures that the applications request to open a module is synchronized with the module contained on the data carousel. Because modules are delivered on multiple sources at different rates, it is important to implement this synchonization process; otherwise an application may read data from either an older version of the module or possibly even a newer version of the module. It is also envisioned that a filter may be dynamically installed by the open file component 36A that allows DII messages for this carsousel to pass through to thedispatcher 38. Once the synchronization process is complete, the filter is removed so that DII messages will not unnecessarily pass through to thedispatcher 38. - To more efficiently process incoming data blocks,
interest manager 36 also dynamically installs filters for each requested interest. Referring to FIG. 4, when anapplication 34 registers an interest, theinterest manager 36 installs a filter in the correspondingdata source processor 42. A module identifier encapsulated in each data block is compared to each registered interest. Data blocks not associated with any registered interest are discarded before any unnecessary processing occurs on the client. In this way, only data blocks associated with a registered interest undergo pre-processing in thedata source processor 42 and are allowed to pass through to thedispatcher 30. Once all of the data blocks for a particular interest have been received by the client,interest manager 36 removes the filter for that interest. - Typically, a data carousel broadcasts all of the data on the carousel before it re-broadcasts any of the data. Therefore, when an application makes a new data request, the response time depends on the data's location relative to where the carousel is in the broadcast cycle. For example, a carousel having ten data blocks may be currently broadcasting the fifth data block. An application that requests data contained in the seventh block will receive that data faster than an application that requests data contained in the ninth block. If it is the eighth block that is currently being broadcast, the reverse is true: an application that requests data contained in the ninth block will receive that data faster than an application that requests data contained in the seventh block.
- Therefore,
data block processor 48 reads the data from a data carousel as it is broadcast; it does not wait for the beginning of the data to begin reading. For instance, an application may be interested in a module contained inblocks 2 to 6. If it starts reading as block 4 is broadcast, data blockprocessor 48 copies the data in block 4 to the application's buffer and then reads the data in each successive block that is broadcast. Subsequent data blocks associated with the requested module (i.e., blocks 5, 6, 2, and 3) are copied to the application's buffer, whereas data that is not part of the module (i.e., blocks 7, 8, 9, 10 and 1) are discarded. - FIGS. 5A and 5B are a flowchart showing a more detailed implementation of the
data block processor 48.Start block 100 begins the processing for each incoming data block. Inblock 102, data blockprocessor 48 interfaces with theinterest manager 36 to retrieve a registered interest.Decision block 104 determines if the incoming data block matches this interest, and if so continues processing inblock 106. If the incoming data block does not match the registered interest,data block processor 48 retrieves the next interest. Because all of the interests are evaluated for each data block, multiple interests can be served by the same incoming data block. -
Decision block 106 compares the version number for each incoming data block to the expected version number contained in the BFS directory. This is important because a module can be changed on the carousel as individual data blocks for that module are being read bydata access system 30. If the version numbers match, then processing proceeds todecision block 110. On the other hand, if the version number does not match, processing branches to an error subroutine 108. - Next,
decision block 110 determines if a data block falls within the desired range of data blocks. For each data blocks within the desired range,Block 112 sets a Read Block indicator. Data blocks outside the desired range are discarded inblock 114. Read Block indicator is an array data structure used to monitor which data blocks have been read from the data carousel. Each bit in the array represents a data block in the requested module, such that if the bit is on (i.e., set to 1), then the block has been read, but if the bit is off (i.e., set to 0), then the block has not been read. Using this indicator allowsdata block processor 48 to receive data blocks in any order from the data carousel, and thus eliminates any unnecessary memory copies. - By evaluating the Read Block Indicator,
decision block 116 determines if an incoming data block has been previously received by the client. For previously unread data blocks, block 120 sets the appropriate bit in Read Block indicator and then copies the data block to the corresponding application buffer space (or alternatively placed in cache memory) in block 122. On the other hand, previously read data blocks are discarded in block 118. Decision block 124 evaluates whether all of the data blocks for a requested module have been read (i.e., all bits set to 1). Once all of the data block have been read,data block processor 48 interfaces withinterest manager 36 to remove the interest and filter for that requested module in block 126, but in either case processing continues by reading the next interest inblock 102. Once all of the interests have been evaluated with respect to an incoming data block, processing is completed for that data block. - Since the
data access system 30 receives data from multiple data sources, each of which may have different content as well as different data rates, the BFS directory may not always be in synch with the content of the data carousel being broadcast to the client. For example, a module (including the BFS directory module) can be changed on the carousel as individual data blocks for that module are being read bydata access system 30. Therefore, thedata block processor 48 also provides a method for downloading and synchronizing the BFS directory on the client. - FIG. 6 is a flowchart showing a portion of the
data block processor 48 that handles the downloading of the BFS directory. Initially, when a set-top box on an (RF) broadcast network boots, a DSM-CC user-to-network configuration message is received at the client which contains the source ID, carousel ID and module ID for the BFS directory. Based on this information,Block 140 installs a filter that allows (any version of) BFS directory data blocks to pass through thedispatcher 38. As a result, the current version of the BFS directory is retrieved from the data carousel. In a preferred embodiment, BFS directory structure is only delivered over the out-of-band source (which by definition is guaranteed to be available to data access system 30), and thus this filter only need be applied to that data source. -
Decision block 144 determines when a BFS directory data block arrives, and if so block 146 reads and parses each incoming data block to construct the BFS directory structure. In the event an error occurs during the downloading process,decision block 148 returns processing to block 142 for re-installation of the initial BFS directory filter. This ensures that the current BFS directory is always downloaded from the data carousel. - Without an error, block150 checks any registered interests against the newly downloaded BFS directory. At boot up, there will be no registered interests. However, for subsequently downloaded BFS directories,
DII processor 44 interfaces with theinterest manager 36 to verify registered interests. If a registered interest no longer exists or has been updated on the data carousel (as indicated by the newly downloaded BFS directory), then the interest is marked for deletion.Block 152 then installs (e.g., cached in memory) the newly downloaded BFS directory onto the client for use bydata access system 30. - Once a BFS directory has been successfully downloaded, block154 installs a different filter which only passes data blocks whose version number does not match the version number of the downloaded BFS directory. When the BFS directory is changed on the server, the version number will be modified, thereby allowing BFS directory data blocks to again pass through the
dispatcher 38. Beginning inblock 144, a new BFS directory can then be downloaded. In this way,data block processor 48 does not process redundant BFS directory information. - The foregoing discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present invention.
Claims (19)
Priority Applications (5)
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US09/219,714 US20020091816A1 (en) | 1998-12-23 | 1998-12-23 | Broadcast data access system for multimedia clients in a broadcast network architecture |
KR1020017008033A KR20010086149A (en) | 1998-12-23 | 1999-12-17 | A broadcast data access system for multimedia clients in a broadcast network architecture |
PCT/US1999/030249 WO2000039947A2 (en) | 1998-12-23 | 1999-12-17 | A broadcast data access system for multimedia clients in a broadcast network architecture |
EP99965315A EP1142173A2 (en) | 1998-12-23 | 1999-12-17 | A broadcast data access system for multimedia clients in a broadcast network architecture |
US10/392,103 US7069572B2 (en) | 1998-12-23 | 2003-03-18 | Broadcast data access system for multimedia clients in a broadcast network architecture |
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US09/219,714 US20020091816A1 (en) | 1998-12-23 | 1998-12-23 | Broadcast data access system for multimedia clients in a broadcast network architecture |
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US20030070165A1 (en) * | 2001-09-19 | 2003-04-10 | Koninklijke Philips Electronics N.V. | Control of an interactive application |
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US20040162908A1 (en) * | 2003-02-10 | 2004-08-19 | Pawel Wrobel | Method of servicing reception of software broadcasted in a carousel of objects |
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Also Published As
Publication number | Publication date |
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KR20010086149A (en) | 2001-09-08 |
EP1142173A2 (en) | 2001-10-10 |
WO2000039947A3 (en) | 2000-11-23 |
US20030177230A1 (en) | 2003-09-18 |
WO2000039947A2 (en) | 2000-07-06 |
US7069572B2 (en) | 2006-06-27 |
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