KR20000076401A - Downloading a computer file from a transmitter via a receiver/decoder to a computer - Google Patents

Abstract

The file, or portion thereof, is divided into a series of R data groups, each group being subdivided into a series of C data blocks. A C extra block group is generated, with each extra block associated with each of the data blocks in the R group by a bitwise exclusive OR or NOR of these data blocks. Each group of data blocks and a group of extra blocks are repeatedly sent from the transmitter. At the receiver / decoder, at least some of the transmitted blocks are received and fed to a computer. The computer is used to determine whether at least one of the received spare blocks has received everything except the spare block and one of each data block, and if so reproduces the one data block. Lost data blocks can be played without having to wait for retransmission.

Description

DOWNLOADING A COMPUTER FILE FROM A TRANSMITTER VIA A RECEIVER / DECODER TO A COMPUTER}

Although not intended to be limiting, in particular in satellite television systems, the emergence of digital transmission systems that primarily intend to broadcast television signals has given the possibility of using the systems for other purposes. One of them is to enable downloading of computer files or software to end users.

Data errors in the transmission system do not occur very frequently. These may often be plausible using interpolation techniques in the case of errors in video or audio data, while a simple single bit of error in a computer file may render the file useless.

The present invention is:

Downloading computer files from a transmitter (such as a satellite television uplink transmitter) to a computer (such as a PC or workstation) via a receiver / decoder (such as a digital satellite television set top box);

A computer used to carry out a portion of the method;

A recording medium (such as a diskette or CD-ROM) having a computer program for programming the processing means of the computer;

MPEG transport system; And

A receiver / decoder is arranged to receive a table of MPEG video and / or audio data and computer file data.

1 shows an overall configuration of a digital television system.

2 illustrates the structure of an interactive system of the digital television system of FIG.

3 is a schematic diagram of a receiver / decoder interface that forms part of the FIGS. 1 and 2 system.

4 is a schematic diagram of a remote controller used in a digital television system.

5 shows an arrangement of blocks forming a file to be downloaded.

6 shows a row of blocks while the file is being downloaded.

7 is a functional block diagram of a receiver / decoder during a file download operation.

8 through 12 are flowcharts illustrating processes occurring in a receiver / decoder during a file download operation.

13 shows another arrangement of blocks forming a file to be downloaded.

14 details the first matrix of blocks shown in FIG.

FIG. 15 shows a generalized matrix of blocks shown in FIG. 13.

FIG. 16 is a flow chart illustrating the process taking place in an application and data server in a television system while preparing a file for download.

17 is a flowchart illustrating a process occurring in a computer during a file download operation.

A first aspect of the invention relates in particular to a method of downloading a computer file from a transmitter to a computer via a receiver / decoder, which comprises:

Dividing the file into data blocks;

Transmitting blocks from a transmitter;

Receiving blocks transmitted at a receiver / decoder; And

Supplying the received blocks from the receiver / decoder to the computer. Blocks typically contain a CRC code so that they can be tested for validity, and the transmission of the blocks is typically second or later if the block is not received correctly at the first transmission, or if it is not received at all. It will be repeated so that it can be received when sent to. The problem with this configuration is that if one or more blocks are not validly received, it takes time to receive the file. Extremely, if only the last block is validly received, the total download time for that file will almost double. The problem with this configuration is that if the blocks are not downloaded in the order in which they are sent, for example, the download rate from the receiver / decoder to the computer is below the download rate from the transmitter to the receiver / decoder. The waiting time may be relatively large. Extremely, the wait time for the last block will be as large as the time it takes to transmit the complete set of blocks, even though all blocks are validly received.

According to a first aspect of the invention, a method is provided for downloading a computer file from a transmitter to a computer via a receiver / decoder, the method comprising:

Dividing the file, or a portion thereof, into a series of R data groups, and dividing each group into a series of C data groups;

Generating a group of C spare blocks;

Transmitting extra blocks from each transmitter and groups of each data block;

Receiving at least some of the blocks transmitted at the receiver / decoder;

Supplying the received blocks from the receiver / decoder to the computer, and

Determine with the computer at least one of the received spare blocks whether all but one of the spare block and one of its respective data blocks has been received, and if so the bits for the spare block and each received data block Regenerating the one data block by performing a Wise Exclusive OR or NOR operation, wherein each redundant block is associated with each of the data blocks in the R group by bitwise exclusive OR or NOR these data blocks. do.

To avoid doubt, a bitwise OR operation on multiple data block means is that each bit of the first of the blocks is XORed with each bit of the second of the blocks, and the result is three of the blocks. Each bit of the first one is XORed, which continues until the last of the blocks. For simplicity, the first bit of the first block is XORed with the first bit of the second block, and the result is XORed with the first bit of the third block. The second bit, the third bit, and the rest are similar. Nevertheless, it is possible to use another predetermined permutation of blocks of bits for the XOR operation. The case where an exclusive NOR operation is used rather than XOR is similarly described.

The first aspect of the invention is that each extra block received, without having to wait for the remaining data blocks to be transmitted and validly received, even if the data block has not yet been received, especially with respect to the purpose of the file downloading operation. And reproducing the block from the respective data blocks. If there is a problem with the transmission and reception of a particular block, the problem with the transmission and reception of the next block in C blocks of the same column will also be of relatively high probability. However, by appropriately selecting the C value, the possibility that there may also be a problem relating to the transmission and reception of the corresponding block in the C blocks of the next column is relatively small. The addition of these extra blocks will increase the time required to transfer all blocks by 100 / R. However, by appropriately selecting the value of R, the benefits provided by this aspect of the invention make it possible to overcome these disadvantages. Typically, the values of C and R will be chosen to be 50 and 10, respectively.

The determining and playing step may be performed for only some of the extra blocks received, especially with respect to the purpose of the file downloading operation. However, the determining and reproducing step is preferably performed for each of the received spare blocks where all but one of the respective data blocks is received. In the latter case, the method may further comprise the step of determining when all data blocks in which the blocks remain are to be reproduced, and then stopping receiving the other block and the portion thereof of the file. have. Thus, the playback step can be done after all the necessary blocks have been received.

The numeric values of R and C are fixed for all file downloading operations. However, for flexibility, the method preferably further comprises transmitting data indicative of the numerical values of R and C from the transmitter, receiving R and C at the receiver, and feeding R and C to the computer. Includes; The computer uses the supplied R and C to determine which data blocks each extra block is associated with.

The blocks are preferably arranged such that the i th of the extra blocks in the group of C extra blocks (for i = 1 to C) are associated with the i th data block in each R group of C data blocks. However, other relationships are also possible.

According to a second aspect of the invention, there is provided a computer used to carry out part of the method of the first aspect of the invention, the computer comprising:

Means for receiving blocks from a receiver / decoder;

Means for processing the received blocks; And

Means for storing the received data blocks and all said reproduced data blocks,

The processing means determines for at least one of the received spare blocks whether all but one of the spare block and one of its respective data blocks has been received, and if so, to the spare block and each received data block. It is programmed to replay said one data block by performing a bitwise exclusive OR or NOR operation on it.

Preferably, the processing means is programmed such that the above determination and reproduction is performed on each received spare block in which all but one of the respective data blocks has been received. In this case, the processing means is preferably programmed to determine when all the data blocks in which the blocks remain are to be reproduced, and then stop receiving other blocks of the file and their portions thereof.

The receiving means is preferably operable to receive data indicative of the numerical values of R and C, and the processing means to use R and C to determine which data blocks each extra data block relates to. Is programmed.

Preferably, the processing means is programmed to be linked with the received data blocks and all the reproduced data blocks above to reconstruct the computer file or portion thereof, and the storage means is operative to store the reconstructed file or portion thereof. do.

According to a third aspect of the present invention, there is provided a recording medium having a computer program for programming the processing means of the computer according to the second aspect of the present invention to operate as described above.

According to a fourth aspect of the present invention,

Means for dividing the file or portion thereof to be downloaded to the receiver / decoder into a series of R data groups, and subdividing each group into one side C data blocks;

C means for generating a group of extra blocks; And

Means for transmitting each group of data blocks and a group of extra blocks, each extra block being associated with each of the data blocks in the R group by bitwise exclusive OR or NOR these data blocks. This is provided.

A fifth aspect of the invention is further particularly relevant to a method of downloading a computer file from a transmitter to a computer via a receiver / decoder, which:

Dividing the file into data blocks;

Repeatedly transmitting blocks from a transmitter;

Receiving blocks transmitted at a receiver / decoder; And

Supplying the blocks received from the receiver / decoder to the computer.

Data blocks are transmitted from the transmitter to the receiver / decoder at a fixed data rate. In order to allow the receiver / decoder to be used in computers with different capacities, and to utilize these capacities, the receiver / decoder has a typical data rate of 400kbits / s, for example IEEE 1284 ECP-mode with a typical data rate of 1 Mbit / s. IEEE 1284 parallel byte-mode with an IEEE 1284 parallel nibble-mode with a typical data rate of 150 to 200 kbits / s, and an RS with a maximum data rate of perhaps 115 kbit / s and typically substantially lower than this. It should be possible to download blocks to the computer in various modes with different data rates, such as -232 serial mode.

When the data rate into the receiver / decoder is faster than the data rate from the receiver / decoder, the step should be able to ensure that all data blocks are received and downloaded to the computer. This can be done by providing a buffer in the receiver / decoder that is large enough to store the complete computer file. However, this is expensive. In addition, the minimum data rate from the receiver / decoder to the computer, which is divided by the data rate expected by the receiver / decoder to provide a rounding integer X, can be measured, so that N / X blocks can be received on one phase. One in every X of the received blocks can be downloaded to the computer, after which the phase can be repeated X times to download all N blocks. However, for efficiency, this depends on the data rate to the computer being accurately measured, which is not possible because the data rate can vary. In addition, if a particular data block is lost, serious problems with this method will arise. A fifth aspect of the present invention relates to finding a solution to these problems.

According to a fifth aspect of the invention, a method is provided for downloading a computer file from a transmitter to a computer via a receiver / decoder, the method comprising:

Dividing the file into the number N of blocks;

Repeatedly transmitting blocks of a file from a transmitter with respective IDs of the blocks;

At the receiver / decoder, providing a plurality of N flags that were initially reset once for each block; And

Receiving the currently transmitted one of the blocks, determining if a flag has been set for the block, if not, feeding the block from the receiver to the computer, and setting the flag for that block until all flags have been set; Periodically performing the setting step.

Thus, it will be appreciated that it does not matter what order the blocks are received by the receiver / decoder. The receiver / decoder can determine if a block is needed and, if so, download the block to a computer. If the receiver / decoder can download the blocks to the computer as soon as the blocks are downloaded to the receiver / decoder, if not all, most blocks will be downloaded in sequence. However, if the receiver / decoder cannot download the blocks to the computer as soon as the blocks are downloaded to the receiver / decoder, for example at only half the speed, then speaking alternate blocks generally It will be downloaded during the phase, and then the remaining blocks will be downloaded during the later phase. If the ratio between the download speed to the receiver / decoder and the download speed from the receiver / decoder is different, the above described arrangement will automatically adjust the interleaving of the blocks.

Preferably, by each supply step, the computer is arranged to send a receive acknowledgment of the block supplied to the receiver / decoder, and the setting step of each block is performed in response to the receive acknowledgment for that block. Thus, if the block is not properly approved by the computer, the receiver / decoder downloads the block again at the next valid opportunity.

The method also includes repeating this method without resetting the flag. Thus, if there is an interruption in the reception of blocks, the downloading method may continue again without repeating the downloading of already received blocks.

According to a sixth aspect of the invention, there is provided a receiver / decoder arranged to receive a table of MPEG video and / or audio data and computer file data, the receiver / decoder comprising:

Means for storing a plurality of N flags that are initially reset once for each computer;

Means for temporarily storing a computer file block currently received;

Means for supplying a block stored in the block storage means to the computer; And

Determine whether a flag for the currently received block is set in the flag storage means, otherwise, cause the block supply means to supply the block from the block storage means to the computer, and set the flag for the block in the flag storage means. Control means arranged to cause the computer file to be received as a plurality of N blocks, each received periodically and each of which contains an ID of the block.

The receiver / decoder preferably further comprises means for receiving from the computer an acknowledgment that the block has been received from the block supply means, wherein the control means sets a flag for the block in response to receiving the acknowledgment for that block. To work.

Preferably, the control means can be operated to resume the reception of computer file blocks after a lost connection without resetting the flag.

The block supply means may include, for example, an ECP-mode IEEE parallel port; It may be one of a number of other types of block supply means, including at least two of a byte-mode IEEE parallel port, a nibble-mode IEEE parallel port, and an RS-232 serial port.

Note that the features of the fourth and fifth aspects of the invention can be used with a method of downloading a computer file from a transmitter to a computer via a receiver / decoder.

Preferred features of the invention will now be described by way of example only with reference to the accompanying drawings.

1 shows an overview of a digital television system 1000 according to the present invention. The present invention includes an almost common digital television system 2000 that uses a known MPEG-2 compression system for transmitting compressed digital signals. More specifically, the MPEG-2 compressor 2002 in the broadcast center receives a digital signal stream (typically a stream of video signals). Compressor 2002 is coupled to multiplexer and scrambler 2004 by linkage 2006. The multiplexer 2004 also receives a plurality of input signals, gathers one or more transport streams, transmits the compressed digital signals through the linkage 2010 to the transmitter 2008 of the broadcast center, and the linkage 2010 ) Can of course have a wide variety of forms, including telecom links. Transmitter 2008 transmits electromagnetic signals towards satellite transponder 2014 via uplink 2012, which are processed electronically in satellite transponder 2014 and then owned or leased by the end user. Typically broadcasted through the downlink to the terrestrial receiver 2018 in the form of a dish. The signals received by the receiver 2018 are transmitted to an integrated receiver / decoder 2020 that is owned or leased by the end user and coupled to the end user's television set 2022. Receiver / decoder 2020 decodes the compressed MPEG-2 signal into a television signal for television set 2022.

Conditional access system 3000 is coupled to multiplexer 2004 and receiver / decoder 2020, which is located partially in the broadcast center and decoder, respectively. This allows end users to access digital television broadcasts from one or more broadcasters. Smartcards may be inserted into the receiver / decoder 2020 capable of decrypting messages related to commercial applications (ie, one or several television programs sold by a broadcaster). Using the decoder 2020 and a smart card, the end user may purchase commercial applications in a reservation or pay per view mode.

The interactive system 4000, also coupled to the multiplexer 2004 and receiver / decoder 2020 and partially located in the broadcast center and decoder, respectively, allows the end user to interact with various applications via the modem back channel 4002. To do this.

2 shows the general structure of an interactive television system 4000 of a digital television system 1000 of the present invention.

For example, interactive system 4000 buys items from a catalog on the screen, requests local news and weather maps on demand, and enables games to be played through a television set.

The interactive system 4000 roughly has four main elements:

Authoring tool 4004 in a broadcast center (or elsewhere) for enabling broadcasters to create, develop, fix defects, and test applications;

MPEG-2 transport stream (typically its private section), coupled to authoring tool 4004, for broadcasters to prepare, verify, and format applications and data delivered to the multiplexer An application and data server 4006 in a broadcast center coupled to a scrambler 2004 for insertion into a;

Equipment within a receiver / decoder 2020 that is owned or leased by the end user so that the end user can receive, verify, decompress and load the application into the working memory 2024 of the receiver / decoder 2020 for execution. A virtual device including a time engine (RTE) 4008, which is executable executable code; And

Modem back channel 4002 between receiver / decoder 2020 and application and data server 4006 allowing server 4006 command signals to insert data and applications into the MPEG-2 transport stream upon end user's request. The engine 4008 also runs resident general purpose applications and is independent of hardware and operating systems.

Interactive television systems operate using an “application” that controls the receiver / decoder and the various devices contained therein. The applications are represented as “resource files” in engine 4008. A module is a set of resource files and data. You may need some modules to configure your application. The “memory capacity” of the receiver / decoder is the storage space for the module. The "interface" is used to download the module. The module may be downloaded from the MPEG-2 transport stream into the receiver / decoder.

The physical interface of the receiver / decoder 2020 is used to download data. Referring to FIG. 3, the decoder 2020 may include, for example, six downloading devices; MPEG flow tuner 4028, serial interface 4030, parallel interface 4032, modem 4034, and two card readers 4036.

For purposes of explanation, the application is preferably part of computer code for controlling the high level functions of the receiver / decoder 2020. For example, when the end user presses the OK key with the remote control's focus on the button object shown on the screen of the television set 2022, the sequence of commands associated with the button is activated.

Interactive applications present menus, execute commands on demand from the end user, and provide data related to the purpose of the application. The applications may be resident applications, i.e., applications stored in ROM (or FLASH or other nonvolatile memory) of receiver / decoder 2020, or applications broadcast or downloaded into RAM or FLASH memory of receiver / decoder 2020. have.

Examples of applications are as follows:

Initialization application. Receiver / decoder 2020 has a resident initialization application, which is a set of modifiable modules that can be made to operate receiver / decoder 2020 immediately in an MPEG-2 environment (this item is defined in more detail below). do. The application provides core characteristics that can be changed by the broadcaster if necessary. It also provides an interface between resident and downloaded applications.

Startup application. The startup application allows all downloaded or resident applications to run on receiver / decoder 2020. This application acts like a bootstrap that runs on arrival of a service to start the application. The startup application can be downloaded into RAM and thus easily updated. It can be configured so that interactive applications available on each channel can be selected and run immediately after being downloaded or preloaded. When preloaded, the application is loaded into memory 2024 and activated by the startup circuitry if necessary.

Program guide. The program guide is an interactive application that gives complete information about programming. For example, it may give information about a television program provided on each channel of a digital television boutique, such as a week. By pressing a key on the remote controller 2026, the end user accesses an accessory screen that overlays the event shown on the screen of the television set 2022. This subscreen is a browser that provides information about the current and next events of each channel of the digital TV's bucket. By pressing another key on the remote controller 2026, the end user accesses an application that outputs a list of information about events for more than a week. End users also search for events and classify them by sample and ordered criteria.

Paid viewing application. The pay-per-view application is an interactive service that can be used on each PPV channel of the digital TV bucket with the conditional access system 3000. End users can access the application using a TV guide or channel browser. In addition, the application is automatically started as soon as a PPV event is detected on the PPV channel. The end user can then buy the current event through his daughter smart card 3020 or by the communication server 3022 (using a modem, telephone and DTMF code, MINITEL, etc.). The application resides in ROM of the receiver / decoder 2020 or is downloadable in RAM of the decoder 2020.

PC download application. Upon request, the end user can download the computer software using a PC download application.

Magazine browser application. The magazine browser application includes periodic video broadcasting of images by end user navigation by on-screen buttons.

Quiz application. The quiz application is preferably motivated with the quiz program being broadcast. For example, multiple selection questions are displayed on the screen of the television 2022 and the user can select the answer using the remote controller 2026. The quiz application can inform the user whether the answer is correct or not, and can continue to count the user's score.

Teleshopping application. In one example of a teleshopping application, an application for a merchandise for sale is delivered to a receiver / decoder 2020 and displayed over a television 2022. Using the remote control, the user can select a particular item to buy. Applications and data over the modem back channel 4002 with an order to debit an invoice for a credit card inserted into one of the card readers 4036 of the receiver / decoder 2020 as far as possible. The server 4006 or telephone number is sent to a separate sales system that is downloaded to the receiver / decoder.

Telebanking Application. In one example of a telebanking application, a user inserts a bank card into one of the card readers 4036 of the receiver / decoder 2020. When the receiver / decoder 2020 dials up the user's bank using a bank card or a telephone number stored on the receiver / decoder, the application can be selected using the remote controller 2026, for example by a telephone line. It provides a number of conveniences, such as downloading bills, requesting checkbooks, and transferring funds between accounts.

Internet browser application. In one example of an internet browser, commands from a user, such as a request to view a web page with a particular URL, are input using remote controller 2026, which is accessed by the modem back channel 4002 by an application and data server. Is sent to 4006. This would include the appropriate web page within the transmission from the broadcast center received by the receiver / decoder 2020 via uplink 2012, transponder 2014 and downlink 2016, to television 2022. Is displayed.

The special features of the PC download application will now be described. A particular technical problem to be solved is that downloading the software will ultimately have a data input speed that is different from the speed at which the desired computer is broadcast. For example, the difference may be 9 kbits / s to 1000 kbits / s, and the software is transmitted over an MPEG-2 stream, for example at 500 bits / s.

In order to deal with this problem, as a general view within a broadcasting center, the software is divided into N blocks (see Fig. 5) and then repeatedly inserted into the MPEG private section (see Fig. 6). Receiver / decoder 2020 includes a bitmap that describes all the software blocks. When downloading starts, all bits in the bitmap are set to zero. The steps of the downloading procedure are as follows. Read the block number. If the bit is 0, the block is sent to the receiving computer, which checks the block and then acknowledges it as appropriate. The receiving computer needs its own software, usually provided on the profile disk, to combine the various blocks of transmitted software. Auto-interleaving provides a measure of flow control. Assuming that the broadcast data rate does not change, blocks of consecutive periods are automatically interleaved. In consecutive periods of all carousels, depending on the bit rate of the receiving computer, the third and fourth blocks are sent to the decoder 2020 until all the blocks have been received.

If a block is lost, problems arise. In general, the solution to this problem is to use the concept of redundancy using the XOR function. Additional extra blocks are added to the data stream where the value of the blocks to be lost can be obtained if necessary.

The PC downloading application will now be described in more detail. During PC download, data is typically downloaded from transponder 2014 to receiver / decoder 2020 via MPEG flow tuner 4028 at a data rate of 700kbits / s, parallel interface 4032 or serial interface 4030. Is downloaded from the receiver / decoder 2020 to the computer via. The receiver / decoder is typically an IEEE 1284 ECP-mode with a data rate of 1 Mbit / s, a byte-mode with a typical data rate of 400 kbits / s, and a nibble-mode with a typical data rate of 150 to 200 kbits / s. Support for downloading to a computer by means of a parallel interface 4032. The receiver / decoder also supports downloading to a computer by serial interface 4030 in RS-232 serial mode, which typically has a maximum data rate of 115 kbit / s and typically has a substantially lower data rate. The receiver / decoder 2020 provides the computer with all of these modes of downloading to provide flexibility, and the user will usually select the downloading mode that operates the fastest.

When the data rate into the receiver / decoder 2020 is faster than the data rate from the receiver / decoder 2020, a step is needed to ensure that all data blocks are received and downloaded to the computer. This is done by providing a receiver / decoder 2020 with a buffer large enough to record a complete computer file. In addition, the minimum data rate from the receiver / decoder to the computer, which is divided by the data rate expected by the receiver / decoder to provide a rounding integer X, can be measured, so that N / X blocks can be received on one phase. One in every X of the received blocks can be downloaded to the computer, after which the phase can be repeated X times to download all N blocks. However, for efficiency, this depends on the data rate to the computer being accurately measured, which is not possible because the data rate can vary. In addition, if a particular data block is lost, serious problems with this method will arise.

To address this problem, the receiver / decoder 2020 is functionally arranged during the PC download operation as shown in FIG. The bitstream flowing from the receiver 2018 passes through a block detect function 10 and then flows to the buffer 14A or the buffer 14B by the selector 12. The contents of the selected one of the buffers 14A and 14B are then supplied to the corresponding portion of the PC 14 by the selected one of the selector 16, the parallel port 4032 and the serial port 4030. The buffers 14A, 14B, like the bitmap 20, are provided by a portion of the RAM of the receiver / decoder 2020. The block detector 10, the selectors 12 and 16, the buffers 14A and 14B, the parallel and serial ports 4032 and 4030, and the bitmap 20 are controlled by a processor 22 that runs a PC download application. do.

The operation of the receiver / deco 2020 during the PC download operation will now be described with reference to the flowcharts of FIGS. 8-12. As shown in Fig. 8, during the initialization process, in step 24, a receiving block is detected by the block detector 10, and the number N of blocks includes the number i of the block and the total number N of blocks. Is determined from the header of each block. In step 26, bitmap 20 is set up with a number of bits equal to N, with each bit reset to zero. In step 28, both the buffer A flag and the buffer B flag are set to "empty". In the example being described, the possible states of these flags are "empty", "filling", "full" and "emptying". In step 32, the output mode to the PC is set. Then, in step 34, the initialization process is passed on to the six processes shown in Figures 9, 10A, 10B, 11A, 11B and performed substantially in parallel.

9 shows a routine for controlling the initiation of downloading to buffers 14A and 14B. In step 36, the process waits until a new block is detected by the block detector 10. Once a new block is detected, in step 38, the number i of the new block is detected by the block detector 10. In step 40, a check is made in the bitmap whether bit b (i) is set to 1, and if so, the block is ignored and the process returns to the beginning. Otherwise, in step 42, the buffer A flag is tested for “empty”, if so, in step 44, the buffer A flag is set to “filling” and then in step 46, selector 12 Downloading of blocks to buffer 14A is initiated, after which the process returns to the beginning. If at step 42, the buffer A flag is not set to "empty", then at step 48 it is tested against the buffer B flag "empty". If the buffer B flag is set to "empty", then step 50 the buffer B flag is set to "filling", and then downloading of the block to the buffer 14B through the selector 12 in step 52 The process then returns to the beginning. If at step 42, 48 the buffer flags are not both set to "empty", the process returns to the beginning.

10A illustrates a routine to perform at the end of downloading a block to buffer 14A. In step 54, the process waits until the end of the block is detected by the block detector 10. Then, in steps 56 and 58, the block is checked using the CRC included in the block. If the block is good, the buffer A flag is set to "full" in step 60, while if the block is bad, the buffer A flag is set to "empty" in step 62, and the resulting block is ignored. will be. As shown in Fig. 10B, a complementary routine is performed at the end of the downloading of the block to the buffer 14B.

11A shows a routine for controlling the downloading of blocks from buffer A to PC 18. In step 64, the process waits until buffer A is tested to "full". Then, in step 66, a check is made to see if the buffer B flag is set to "emptying", and if so, the process waits until buffer 10B has full emptying. Then, in step 68, buffer A is set to "emptying". Then, in step 70, the block i in the buffer 14A is initiated by the selector 16 to the PC 18 using the set output mode. In step 72, the process waits for the download to complete. Then, in step 74, a check is made for approval from the PC 18. If an acknowledgment is received, bit b (i) for block i in bitmap 20 is set to 1 in step 76 and the buffer B flag is then set to “empty” in step 78. Then the process goes back to the beginning. If, at step 74, the acceptor is not received, step 76 is omitted, thus downloading of the block will be ignored. As shown in FIG. 11B, a routine routine is performed to control block downloading from buffer 14B to PC 18. As shown in FIG.

12 shows a routine for checking whether the downloading of a computer file has been completed. In step 80, a check is made to see if all bits in the bitmap from b (i) to b (N) are set to 1, and if so, a file downloading operation as long as the receiver / decoder 2020 is involved. Ends.

From the above, it will be appreciated that the order in which blocks are received by the receiver / decoder 2020 is not a problem. The receiver / decoder 2020 can determine if a block is needed, and if so, locates the block in one of the buffers 14A and 14B and waits until the PC 18 is ready to receive the block. If the block fails the CRC check, or if the block is not properly authorized by the PC 18, the receiver / decoder 2020 downloads the block again at the next valid opportunity. Thus, if the receiver / decoder 2020 can download the blocks to the PC 18 as soon as the blocks are downloaded by the receiver / decoder 2020, most not all, but most of the blocks in sequence Will be downloaded. However, if the receiver / decoder 2020 is not downloaded to the PC 18 as soon as the blocks are downloaded by the receiver / decoder 2020, for example at half speed, then the speaking alternating blocks are generally It will be downloaded for one phase, and then the remaining blocks will be downloaded for later phases. If the download rate to receiver / decoder 2020 changes in the ratio between the download rate from receiver / decoder 2020, the arrangement described above will automatically adjust the interleaving of the blocks.

Apart from operating the software, the memory required for the above-described configuration is two buffers 14A and 14B and a bitmap 20. The size of a block is typically 2kbytes (although it may be included in a single MPEG-2 up to 4kbytes) and the maximum number of blocks in a file is 2 ¹⁶ blocks. Accordingly, the required memory is 2 ^16/8 = 8kbytes for 4kbytes and bitmap 20 for the buffers (14A, 14B), is the total 12kbytes, 2 enables the ¹⁶ × 2kbyte = 128Mbytes can be downloaded.

In the arrangement described above, the PC 18 is programmed such that once each block is received, the block is written to the hard disk of the PC 18 with a file name containing the number i of the block. Then, once all the blocks have been received, the data in the N file are concatenated to play the original computer file.

Now, in order to handle the case where the connection between the broadcasting center and the receiver / decoder 2020 is lost, the change to the above-described arrangement will be described with reference to FIGS. 5 to 12. In such a case, the broken connection is detected by the receiver / decoder 2020 and the user may be reminded if they wish to resume the download operation. If so, download the file in the manner described above, except that step 26 of FIG. 8 is omitted so that the bits from b (1) to b (N) of the current bitmap 20 are not reset to zero. Is required. Thus, the download operation will continue without requiring blocks that have already been downloaded to be downloaded again.

Now, the concept of redundancy using the XOR function will be explained in detail. In the arrangement described above with reference to FIGS. 5 and 6, the data blocks were only considered as a column of blocks from 1 to N. FIG. In the arrangement to be described now, the blocks can be considered to be arranged as a series of matrices, each matrix comprising (R + 1) row and C columns of the block as shown in FIGS. 13 to 15. In particular, as shown in FIG. 14, in the first matrix, the top row contains blocks numbered from i = 1 to C and the next row contains blocks numbered from i = C + 1 to 2C. This continues from i = RC + 1 to the bottom row, which includes (R + 1) C numbered locks. As shown in Figure 15, in the more general case of a numbered matrix, the top row is from i = (j-1) (R + 1) C + 1 to ((j-1) (R + 1). Contains blocks numbered from +1) C, and the row at the bottom contains blocks numbered from i = (j (R + 1) -1) C + 1 to j (R + 1) C . At the general position in row r and column c of matrix j, the number of blocks i = ((j-1) (R + 1) + (r-1)) C + c. In the matrix, all rows of blocks except the bottom row (r = 1 to R) are data blocks into which the computer file to be downloaded is divided. However, the blocks of the bottom row (r = R + 1) are extra blocks that are calculated by the application and data server 4006 and added into the MPEG bitstream. More specifically, as shown in Fig. 16, in step 100, the file to be downloaded is divided into data blocks of 2 kbytes each. In step 102, the values of R and C are set. In step 104, the matrix number counter is set to one. In step 106, the first RC data blocks, which are regarded as the matrix of the C column and R row of data blocks, are read. In step 108, for each column c = 1 through C, an extra block for that column is calculated. In more detail, the extra blocks are computed as bitwise XOR operations on the data blocks in each column. In step 110, the extra blocks will be an additional bottom row (r = R + 1) of the matrix. In step 112, a block number from i = (j-1) (R + 1) C + 1 to (j (R + 1) -1) C is added as a header to the data blocks, i = ( Block numbers j-1) (R + 1) C + 1 to (j (R + 1) -1) C are added as extra headers as headers, and the blocks are stored. In step 114 a test is made to see if the end of the file has been reached, and if not, the matrix counter j is incremented in step 116. Then, in steps 102 to 108, the next RC data blocks are repeated. This continues until the end of the computer file is reached. An entry for the file is then added to the directory or index MPEG-2 table containing the name, size, and date stamp for the file and the values of R and C. The processed data blocks and spare blocks then prepare for transmission.

When the user wants to download the file, the receiver / decoder 2020 is used to select a description for the file from a directory or index, and then the receiver / decoder 2020 includes values of R and C. The file information is supplied to the PC 18. Then, during PC download of the file, the receiver / decoder 2020 does not require any functionality other than the method described above with reference to FIGS. However, the PC 18 may be a program loaded into the PC 18 from the diskette or CD-ROM or downloaded from the receiver / decoder 2020 to the PC 18 to process the extra blocks in the manner described below. Is programmed by). In general, each time the PC 18 detects that an extra block has been downloaded, it checks whether all but one of the data blocks of the same column of the same matrix are received as the received extra block. If so, the PC 18 reproduces the lost data block by performing a bitwise XOR operation on the received data blocks and the received spare block, and the received data blocks received from the receiver / decoder 2020. Save as

Referring to FIG. 17 in more detail, in the initial step 120, the PC 18 receives the values of R and C, and then in step 122 receives the block. In step 124, PC 18 extracts its block number from the header of the received block. In step 126, the PC 18 SMS stores the block as block i. In step 128, an acknowledgment is sent to the receiver / decoder 2020. In step 130, the PC 18 checks whether all but at least one of the blocks (R-1) has been received in each C column. This may be done by checking the directory of the hard disk of the PC 18 where the blocks are stored, or preferably by using a bitmap in the PC 18 memory where each block is distinguished as being stored. If at least everything except one of the blocks is stored for each column, enough blocks are received and the process proceeds to step 132. If not, however, the process returns to step 122 to receive the next block. Step 132 controls the FOR-NEXT loop. In step 134, PC 18 determines for each column whether all data blocks for that column (ie, R-1 data blocks) have been received. If so, the FOR-NEXT loop goes to the next column. If not, however, in step 136 the PC 18 reproduces the lost data block by performing a bitwise XOR operation on the received data blocks and the spare block. Then, at step 138, PC 18 stores the regenerated data block and goes to the next column in the FOR-NEXT loop. At the end of the FOR-NEXT loop, the process goes to step 14 where a computer file is played from the received data blocks, and in step 142 the computer file is stored on the hard disk of the PC 18. In step 134, the determination as to whether the block is a data block or an extra block is determined by 0 < i-, where the matrix number j is determined from j = int ((i-1) / (R + 1) C) +1. It can also be done by checking the authenticity of the jRC≤C relationship, where int () represents the government part of (). If true, the block is an extra block; if false, it is a data block.

The arrangement described above addresses two major problems. The first problem concerns a simple interruption in the bitstream from the transponder 2014 to the terrestrial receiver 2018. If a particular block i was affected by the interruption above, it can be seen that the next block i + 1 of the same row is also relatively likely to be affected. The value of C is chosen so that the next block i + C in the same column is also less likely to be affected. If R of (R + 1) blocks in each column are properly received, the remaining blocks can be reproduced, using the properties of the extra blocks and bitwise XOR operations. The remaining problem relates to the effective rate at which blocks are received for the purpose of the file download operation. If only one block is waiting, you will see that the remaining period may be as large as the time it takes to transfer almost all blocks in the file. With the arrangement described above, if only a few data blocks are waiting, they are likely to be reproduced from the extra blocks and already received data blocks. Of course, the transfer of additional extra blocks increases the total time to transfer the computer file, and thus the advantage of dealing with communication interruptions and reducing the time spent waiting for the last few blocks is by appropriately choosing the values of C and R. There is a need to balance the shortcomings of increasing total transmission time. The choice of C and R values can be a topic of statistical study or trial and error. Typically, however, the values would be C = 50, R = 10. Preferably, C and R are greater than five.

In the example described above, the values of C and R are determined when the file is ready to be transferred into the blocks, and the values of C and R are included in the directory or index table for the downloadable file. Also, the values of C and R may be predetermined without values contained in the directory or index table, and the PC 18 may be preprogrammed with the values of C and R.

In the example described above, blocks are downloaded until enough blocks are downloaded so that the file can be played. Then, the missing blocks are played and the file is played. In a variant, if an extra block for a particular column is downloaded, and if everything except one of the data blocks in that column is downloaded, then it is missing without waiting for enough blocks to be downloaded so that the entire file can be played. The data block is reproduced and marked as received in that step.

In the apparatus described above, the receiver / decoder 2020 is shown as separate from the PC 18. However, receiver / decoder 2020 may be formed in the form of a portion of PC 18, for example an add-on card.

The invention has been described above by way of example only, and it is obvious that changes in details may be made within the scope of the invention.

Each feature, (appropriate) claim and drawing described in the detailed description may be provided independently or in any suitable combination.

In the preferred embodiment described above, certain aspects of the invention have been implemented using computer software. However, it will be apparent to one skilled in the art that all these features can be implemented by hardware. In addition, it will be readily understood that hardware, computer software, and the functions performed by these may be performed on or with electricity and such signals.

Signal generation and broadcasting (agent reference number PC / ASB / 19707), smart cards for use with receivers of encrypted broadcast signals (agent reference number PC / ASB / 19708), broadcast and reception systems, and conditional access systems therefor (Attorney Ref. No. PC / ASB / 19710), Downloading computer files from the transmitter to the computer using a receiver / decoder (Attorney Ref. No. PC / ASB / 19711), Transmitting and receiving television programs and other data (Attorney Reference) PC / ASB / 19712), downloading data (agent reference number PC / ASB / 19713), computer memory configuration (agent reference number PC / ASB / 19714), television or radio control system development (agent reference number PC / ASB / 19715), extraction of data sections from the transmitted data stream (agent reference number PC / ASB / 19716), access control system (agent reference number PC / ASB / 19717), data processing system (agent reference number) PC / ASB / 19718), and our concurrently pending applications entitled Broadcasting and Receiving Systems, Receivers / Decoders and Remote Controllers for them (agent PC / ASB / 19720), all having the same filing date. The literature crosses. The contents of these documents are incorporated herein by reference. The list of applications includes the present invention.

Claims (26)

A method of downloading a computer file from a transmitter to a computer via a receiver / decoder, Dividing the file, or a portion thereof, into a series of R data groups, and dividing each group into a series of C data groups; Generating a group of C spare blocks; Transmitting groups of each data block and redundant blocks from the transmitter; Receiving at least some of the blocks transmitted at the receiver / decoder; Supplying the received blocks from the receiver / decoder to the computer, and Determine by the computer for at least one of the received spare blocks whether all but the one of the spare block and one of its respective data blocks has been received, and if so the spare block and each received data block Regenerating the one data block by performing a bitwise exclusive OR or NOR operation on Wherein each spare block is associated with each of the data blocks in the R group by bitwise exclusive ORing or NORing these data blocks. 2. The method of claim 1, wherein said determining and playing step is performed for each of said received redundant blocks except that one of each data block is received. 3. The method of claim 2 including determining when enough blocks are received so that all remaining data blocks can be reproduced, and stopping receiving other blocks for the file or other portions thereof. How to download computer files. The method of claim 1 further comprising: transmitting data representing numeric values of R and C from the transmitter, receiving the R and C data at the receiver, and supplying the R and C data to the computer. To; And the computer is operative to use the supplied R and C to determine which of the data blocks are associated with each spare block. The method of claim 1, wherein the blocks are associated with the i th data block in each of the R groups of the C data blocks, where the i th one of the extra blocks in the group of C surplus blocks (for i = 1 to C). A method of downloading a computer file, characterized in that arranged as possible. A method of downloading a computer file from a transmitter to a computer via a receiver / decoder, Dividing the file into the number N of blocks; Repeatedly transmitting blocks of a file from a transmitter with respective IDs of the blocks; And At the receiver / decoder, providing a plurality of N flags that were initially reset once for each block; And Receiving the currently transmitted one of the blocks, and determining if a flag has been set for the block, if not, feeding the block from the receiver to the computer, and flag for that block until all flags are set And periodically performing the step of setting the computer file. 7. The method of claim 6, wherein by each supply step, the computer is arranged to send a receipt acknowledgment of a block supplied to the receiver / decoder, wherein the setting step of each block is performed in response to the receipt acknowledgment for that block. How to download a computer file, characterized in that. 8. A method according to claim 6 or 7, comprising repeating the method of claim 6 or 7 without resetting the flag. Method claimed by any one of claims 1 to 5 and by any of claims 6 to 8. A method of downloading a computer file from a transmitter to a computer via a receiver / decoder substantially described with reference to the drawings. Claims 1 to 5, 9 and 10 of the computer used for aquatic part of any one of the methods, Means for receiving blocks from the receiver / decoder; Means for processing the received blocks; And Means for storing said received data blocks and all said reproduced data blocks, The processing means determines for at least one of the received spare blocks whether all but one of the spare block and one of its respective data blocks has been received, and if so, to the spare block and each received data block. And program to regenerate the one block of data by performing a bitwise exclusive OR or NOR operation on the data block. 12. The computer according to claim 11, wherein said processing means is programmed so that said determination and reproduction are performed on each received spare blocks in which all but one of the respective data blocks is received. 13. The method of claim 12, wherein the processing means is programmed to determine when all data blocks in which blocks remain are to be reproduced and then stop receiving other blocks of the file and their portions thereof. computer. 14. A method according to claims 11 to 13, wherein said receiving means is operable to receive data representing numerical values of R and C, said processing means determining which data blocks each extra data block is associated with. And programmed to use R and C to do so. 15. The apparatus according to any one of claims 11 to 14, wherein said processing means is programmed to be linked with received data blocks and all said reproduced data blocks to reconstruct a computer file or part thereof, Means for operating to store the reconstructed file or portion thereof. A computer used for downloading a computer file from a transmitter to a computer via a receiver / decoder substantially described with reference to the drawings. 17. A recording medium having a computer program for programming a processing means of a computer as claimed in any one of claims 11 to 16, to operate as described in the claims. A recording medium having a computer program, substantially described with reference to the drawings. Means for dividing the file or portion thereof to be downloaded to the receiver / decoder into a series of R data groups, and subdividing each group into one side C data blocks; C means for generating a group of extra blocks; And Means for transmitting each group of data blocks and a group of extra blocks, each extra block being associated with each of the data blocks in the R group by bitwise exclusive ORing or NORing these data blocks. MPEG transmission system. MPEG transmission system substantially described with reference to the drawings. A receiver / decoder arranged to receive a table of MPEG video and / or audio data and computer file data, Means for storing a plurality of N flags that are initially reset once for each computer; Means for temporarily storing a computer file block currently received; Means for supplying a block stored in the block storage means to the computer; And Determine whether a flag for the currently received block is set in the flag storage means, otherwise, cause the block supply means to supply the block from the block storage means to the computer, and set the flag for the block in the flag storage means. Control means arranged to cause the computer file to be received as a plurality of N blocks, each received periodically and each including an ID of the block. 22. The apparatus of claim 21, wherein the receiver / decoder further comprises means for receiving an acknowledgment from the computer that the block has been received from a block supply means, the control means in response to receiving the acknowledgment for the block. A receiver / decoder operable to set a flag for that block. 23. A receiver / decoder according to claim 21 or 22, wherein said control means is operable to resume reception of computer file blocks after lost connection without resetting a flag. 24. A receiver / decoder according to any one of claims 21 to 23, wherein said block supply means is one of a plurality of block supply means of different types. 25. The apparatus of claim 24, wherein the plurality of block supply means comprises: an ECP-mode IEEE parallel port; And at least two of a byte-mode IEEE parallel port, a nibble-mode IEEE parallel port, and an RS-232 serial port. Receiver / decoder substantially described with reference to the drawings.