Demultiplexer

[Technical field to which the invention belongs] The present invention is a demultiplexer.<u style="single">apparatus</u>And the demultiplexing method. The present invention specifically decodes digital signals transmitted over cables and / or satellite networks.<u style="single">So-called</u>Demultiplexer used for set top box (STB)<u style="single">apparatus</u>Regarding.

[0002] [Conventional technique]<u style="single">recent years</u>, Standards for digital broadcasting of video information have been established. These standards include MPEG-2 transport streams (hereinafter referred to as MPEG-2 TS) using technology for compressing audio and video signals, and data packet formats such as ISO-IEC 13818-1,2,3. I am using. Early forms of digital broadcasting over networks were to transmit the same program, the same signal, to all viewers in the network. However, it was hoped that "narrowcast" transmission would be introduced, in which the signal would be transmitted over the network to only one viewer. This technology is especially<u style="single">So-called</u>Applies to Video on Demand. Therefore, it is necessary to provide a set top box capable of receiving both a broadcast signal and, for example, an asynchronous transfer mode, that is, a narrow cast signal such as an ATM signal.

[0003] Broadcast signals, such as MPEG-TS signals and narrow cast signals, are encoded in different formats, and in order to convert a block of transmitted signals into a basic MPEG video signal, each of them is used. A decoder is needed. If each decoder is provided in the set-top box, there is a problem that the manufacturing cost becomes high and the set-top box becomes complicated. Since set-top boxes are mass-produced, it is desirable that adding the ability to receive narrowcast services does not increase costs.

[0004] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to demultiplex both a broadcast signal and a narrow cast signal. Can multiplexer<u style="single">Equipment and</u>To provide a demultiplexing method.

[Means for Solving the Problems] A Demultiplexer According to the Present Invention.<u style="single">The device receives the MPEG transport stream or the ATM signal generated by processing the MPEG transport stream, and selectively demultiplexes the MPEG transport stream and the ATM signal. In the demultiplexer device, the MPEG transport is performed. It is possible to demultiplex the stream</u><u style="single">MPEG demultiplexer, memory shared for MPEG transport stream processing and ATM signal processing, and ATM signal data are stored in the above memory, and the MPEG transformer in the ATM signal data stored in the memory. Read from memory based on the data identified by the ATM means, the ATM means to identify the data needed to process the port stream, the path to feed the MPEG transport stream directly to the MPEG demultiplexer, and the data identified by the ATM means. It is provided with a switching means for switching the path for supplying data to the MPEG demultiplexer. Then, the ATM means supplies the MPEG demultiplexer with an address for reading the data to be demultiplexed from the memory based on the identified result, and the MPEG demultiplexer is demultiplexed using the address. Read the data from the memory</u>。

[0006] The demultiplexing method according to the present invention is<u style="single">MPEG demultiplexer capable of demultiplexing MPEG transport stream, memory shared for MPEG transport stream processing and ATM signal processing, ATM means for storing ATM signal data in memory, and MPEG An MPEG transport stream or this MPEG is used by using a demultiplexer device provided with a switching means for switching between a path for supplying the transport stream as it is to the MPEG demultiplexer and a path for supplying the data read from the memory to the MPEG demultiplexer. In the demultiplexing method of receiving the ATM signal generated by processing the transport stream and selectively demultiplexing the MPEG transport stream and the ATM signal, the MPEG transport stream was received by the switching means. When the MPEG transport stream is supplied to the MPEG demultiplexer, and when the ATM signal is received, the step of supplying the ATM signal to the ATM means and the MPEG transport stream supplied by the switching means are transferred to the MPEG demultiplexer. The ATM signal data supplied by the switching means is stored in the memory by the ATM means, and the MPEG transport stream in the ATM signal data stored in the memory is processed. The step of identifying the data required for the data and the address for reading the data to be demultiplexed from the memory based on the identified result by the ATM means are supplied to the MPEG demultiplexer, and the address is provided by the MPEG demultiplexer. Has a step of reading demultiplexed data from the memory using</u>。

[0007] As described above, in the present invention, the demultiplexing process can be performed very efficiently by using one memory. In the present invention, it is only necessary to send and receive the address of the memory, and it is not necessary to write and read the data for the memo many times. Further, when demultiplexing an ATM signal, the MPEG demultiplexer performs processing according to the address from the ATM means, so that the ATM means and the MPEG demultiplexer do not need to perform processing at the same time, and the capacity of the entire memory is increased. It can be made smaller.

[Embodiment of the Invention] Hereinafter, a demultiplexer according to the present invention.<u style="single">apparatus</u>And the demultiplexing method will be described in detail with reference to the drawings.

[0009] In broadcasting, a plurality of programs, that is, a plurality of video signals are simultaneously transmitted, and a viewer selects one signal from these video signals for viewing. In this method, the user cannot control the type of transmitted signal and its time. Therefore, when receiving such a plurality of video signals at the home terminal, the home terminal must separate the video signal selected by the user from the plurality of video signals including unnecessary video signals.

[0010] On the other hand, in narrow cast transmission, the user can control the transmitted data to some extent. For example<u style="single">So-called</u>With video on demand, users can request programs that are transmitted over the network. The requested program data is transmitted over one digital channel along with data for other users. Therefore, the home terminal must selectively extract packets of data related to the program requested by the user.

[0011] In a device that receives a narrow cast signal and a broadcast signal, a plurality of signals for a plurality of users are multiplexed and transmitted via the same channel, so that a process of further separating the narrow cast signal and the broadcast signal. Is required.

[0012] Therefore, narrow cast<u style="single">Data of</u>And broadcast data can be encoded in the same format. As a coding format that conforms to the above-mentioned ISO standard and can be used, there is an MPEG-2 transport stream (hereinafter referred to as MPEG-2 TS).

[0013] In a broadcasting system, coding of a video signal is performed by converting the video signal into a stream of digital MPEG video data. Specifically, as shown in FIG. 1, the stream of data 1 is divided into blocks 2, a header 3 is added to each block 2, and a transmission block 4 in MPEG-2 TS is generated. And these<u style="single">transmission</u>block<u style="single">4</u>Is transmitted via the network and received by the user's home terminal (set-top box).

[0014] In narrowcast transmission systems, coding video signals is somewhat more complex than in broadcast systems, as shown in FIG. The video signal is converted into MPEG video data as shown in FIG. 2A and then divided into the MPEG-2 TS transmission block 4 as shown in FIG. 2B. As shown in Fig. 2C, one or more transmission blocks 4 of MPEG-2 TS are attached with a trailer 6 and some dummy data as needed, and a protocol data unit in ATM is added. Hereinafter referred to as PDU)<u style="single">5</u>Is formed. And these PDUs<u style="single">5</u>Is divided into one or more small blocks, as shown in FIG. 2D, and then each block is appended with a header containing destination address information, as shown in FIG. 2E. The destination address information relates to the addresses of one or more recipients of the data. Header added<u style="single">block</u>Is known as an ATM cell, which performs narrowcast transmission of data. In order to transmit the ATM cell over the network without using very complicated hardware, the ATM cell is further coded in the same format as MPEG-2 TS, as shown in Fig. 2F.<u style="single">pseudo</u>MPEG transport stream (hereafter,<u style="single">pseudo</u>It is called an MPEG transport stream. ) Is formed. this<u style="single">pseudo</u>The MPEG transport stream is transmitted over the network together with the MPEG-2 TS for broadcasting.

[0015] Here, the narrow cast data (<u style="single">pseudo</u>A set-top box that decodes both MPEG transport stream) and broadcast data (MPEG-2 TS) will be described.

[0016] The MPEG-2 TS signal transmitted via the network, or shown in Fig. 2F.<u style="single">pseudo</u>The MPEG transport stream signal (shown in FIG. 2F) is received by the set-top box and fed to the ATM termination and data extractor 11 and selector switch 12. By the way, since the signal received via one channel is either signal, the type of signal, that is, whether it is a broadcast signal or a narrow cast signal, is based on the channel selected by the user. Can be decided. Therefore, the changeover switch 12 is controlled by the channel selected by the user, and for example, when receiving broadcast data, the received MPEG-2 TS signal is directly supplied to the MPEG-2 TS demultiplexer 13. On the other hand, when receiving the narrow cast data, the changeover switch 12 supplies the MPEG-2 TS from the ATM termination and the data extractor 11, which will be described later, to the MPEG-2 TS demultiplexer 13. A narrow cast / broadcast detector (not shown) that identifies narrow cast data and broadcast data may be provided at the input of the set-top box to control the changeover switch 12.

The ATM termination and data extractor 11 are shown in FIG. 2F.<u style="single">pseudo</u>The MPEG transport stream is decomposed into the ATM cells shown in FIG. 2E, and the ATM cell addressed to the user who requested the program is extracted based on the destination address added to the header of the ATM cell. Then, the ATM termination and the data extractor 11 form the PDU shown in FIG. 2C after removing the destination address related to the current virtual connection attached to the ATM cell, as shown in FIG. 2D. The ATM termination and data extractor 11 then removes the trailer and dummy bits from these PDUs to form the MPEG-2 TS shown in FIG. 2B, and as described above, switches this MPEG-2 TS to the selector switch 12 It is supplied to the MPEG-2 TS demultiplexer 13 via. The ATM termination and data extractor 11 received these processes using, for example, a memory 15 composed of DRAM.<u style="single">pseudo</u>The MPEG transport stream, the extracted ATM cell, the formed PDU, etc. are written to the memory 15 and read out.

[0018] The MPEG-2 TS demultiplexer 13 separates the MPEG-2 TS of the program selected by the user from all the broadcast programs to be multiplexed and received by using the memory 16, and also separates the MPEG-2 TS from the MPEG-2 TS. The header is removed, the MPEG video data shown in FIG. 1A or FIG. 2A is reproduced, and supplied to a subsequent MPEG decoder (not shown). The MPEG decoder includes, for example, a variable length decoder, an inverse DCT converter, an adder, a memory, and the like, and reproduces an analog video signal from MPEG video data and supplies it to, for example, a television receiver. In this way, the user can watch the program sent as a broadcast and also can watch the program sent as a narrow cast such as video on demand. For example, it is determined whether or not the MPEG-2 TS received by broadcasting has the right to watch a paid program.<u style="single">Limited reception</u>It may be supplied to the MPEG-2 TS demultiplexer 13 via an optional conditional access sub-system 14.

By the way, the set-top box shown in FIG. 1 can receive both narrow cast data and broadcast data as described above, but there is a problem related thereto. Specifically, when receiving a narrow cast signal in the set-top box, the ATM termination and data extractor 11 processes a large amount of data using the memory 15 as described above, and the broadcast signal is broadcast in the set-top box. Is bypassed, so no data processing is performed. In contrast, the MPEG-2 TS demultiplexer 13 provides the video signal and audio requested by the user from the ATM termination and data extractor 11 when the signal received by the set-top box is a narrow cast signal. MPEG-2 consisting of data related only to signals, etc.<u style="single">TS</u>Is supplied. Therefore, the MPEG-2 TS demultiplexer 13 merely outputs the supplied data. On the other hand, when the set-top box receives the broadcast signal, the MPEG-2 TS demultiplexer 13 extracts the signal of the program requested by the user from the signal to be multiplexed and received. That is, the ATM termination and data extractor 11 and the MPEG-2 TS demultiplexer 13 are substantially idle while one is processing a large amount of data.

In other words, in the above-mentioned set-top box, the memory 1 for the ATM termination and the data extractor 11 and the MPEG-2 TS demultiplexer 13 to independently perform data processing.<u style="single">5</u>、1<u style="single">6</u>There is an inefficiency aspect of having. The set-top box also performs two-step signal processing, despite processing video signals supplied at very high data rates. Specifically, the input data is stored in the memory 15 and the first data processing is performed, the processed data is stored in the memory 16 and the second data processing is performed, and finally the processed data. Note again to output to the subsequent MPEG decoder<u style="single">Ri</u>I remember in 16. The number of writes and reads of memory at high data rates is very important and it is inefficient to write and read twice. Therefore, this set-top box has a problem that the data throughput is limited or a large amount of high-speed memory is required and the cost is high.

[0021] Here, a specific configuration of the set-top box that solves the above-mentioned problems will be described with reference to FIG.

[0022] This set-top box comprises a single demultiplexer 20, as shown in FIG. This demultiplexer 20 is with MPEG-2 TS<u style="single">pseudo</u>It is possible to demultiplex both with the transport stream. In addition, this figure<u style="single">4</u>Shows the flow of processing rather than the physical configuration.

As shown in FIG. 4, the demultiplexer 20 uses an ATM regenerator 21 that generates an address for identifying an ATM cell and an ALLPDUSAR device 22 that generates an address for forming an MPEG-2 TS. MPEG-2 TS Demultiplexer 23, which extracts the MPEG-2 TS of the program selected by the user,<u style="single">pseudo</u>It includes a memory 25 for storing MPEG transport stream data and a changeover switch 26. The ATM regenerator 21 uses the memory 25 and is shown in FIG. 2F.<u style="single">pseudo</u>From the MPEG transport stream the ATM cell shown in Figure 2E<u style="single">Regeneration</u>To do. It should be noted that the video signal is as described above via the network.<u style="single">pseudo</u>Instead of being transmitted as an MPEG transport stream, it may be transmitted as an ATM packet. In this case, the ATM regenerator 21 is unnecessary. Or it is bypassed.

[0024] The ALLPDUSAR device 22 is stored in the memory 25.<u style="single">In a pseudo MPEG transport stream</u>From the ATM cell, the PDU shown in Figure 2C<u style="single">Regeneration</u>To do. It should be noted that the above-mentioned<u style="single">Shown in Figure 3</u>Unlike set-top boxes, ATM cell data is not transferred directly from ATM regenerator 21 to ALL PDUSAR device 22. Further, as will be described later, the MPEG-2 TS is not transferred from the ALL PDUSAR device 22 to the MPEG-2 TS demultiplexer 23.

Specifically, the ATM player 21 is shown in FIG. 4F received via the network.<u style="single">pseudo</u>When forming an ATM cell from an MPEG transport stream<u style="single">pseudo</u>The data of the MPEG transport stream is transferred to the memory 25 via the bus 24 and stored. Therefore, as described above<u style="single">Shown in Figure 3</u>The set-top box is shown on the 4th floor of the figure.<u style="single">pseudo</u>Whereas the MPEG transport stream data is stored in memory 15 and the data is selectively read from memory 15 to form an ATM cell, in this set-top box, it is stored in memory 25.<u style="single">pseudo</u>The ATM regenerator 21 analyzes the data stored in the memory 25, only identifying the appropriate data part corresponding to the ATM cell in the data of the MPEG transport stream and not actually reading it. An address indicating which area of the memory 25 the ATM cell data is stored in is supplied to the ALL PDUSAR device 22.

The ALLPDUSAR device 22 is<u style="single">ATM regenerator 21</u>Based on the address from, the process of simply identifying the data part required for MPEG-2 TS among the data stored in the memory 25 is performed. Further, the ALL PDUSAR device 22 performs header processing including destination address information and error correction processing on the data stored in the memory 25 at the time of this data processing. Then, the ALL PDUSAR device 22 supplies the MPEG-2 TS demultiplexer 23 with an address indicating an area in which the MPEG-2 TS data is stored and an appropriate control signal. The MPEG-2 TS demultiplexer 23 accesses necessary data from the memory 25 based on this address or the like. Thus, in this set-top box, the ALLPDUSAR device 22 memorizes the ATM cell shown in Figure 2E.<u style="single">25</u>Write to memory<u style="single">25</u>Read data from to form the ATM packets shown in Figure 2D and re-memory these ATM packets.<u style="single">25</u>Write to, read the appropriate data to form the ATMPDU shown in Figure 2C, and store the ATMPDU in memory.<u style="single">25</u>It does not require the process of rewriting to form the MPEG transport stream shown in Figure 4B.

[0027] On the other hand, the broadcast signal received as the MPEG-2 TS shown in FIG. 1B is directly supplied to the MPEG-2 TS demultiplexer 23 via the changeover switch 26, similarly to the set-top box shown in FIG.<u style="single">Also</u>, Narrow cast signal is shown in Figure 2F<u style="single">pseudo</u>When received as a transport stream, this<u style="single">pseudo</u>The data of the MPEG transport stream is temporarily stored in the memory 25, and as described above, the data stored in the memory 25 is subjected to a process of forming an MPEG-2 TS using an appropriate pointer or address. .. Thus, in this set-top box, memory<u style="single">25</u>It is not necessary to repeat writing and reading of data to, and it is not necessary to transfer data between each circuit. In other words, it can reduce the data processing in each circuit.<u style="single">Ki</u>To. In particular, when receiving a narrow cast signal, the ATM regenerator 21 and ALLPDUSAR device 22 operate, and the MPEG-2 TS demultiplexer 23 is based on the address supplied from the ALLPDUSAR device 22 in memory.<u style="single">25</u>Since it is only necessary to search for and read appropriate data from the MPEG-2 TS demultiplexer 23, the data processing by the MPEG-2 TS demultiplexer 23 can be reduced.

[0028] Further, in the demultiplexer 20, the received data is stored in the memory before the appropriate address for obtaining the MPEG-TS data is determined.<u style="single">25</u>It is stored in, and is read out in a timely manner, that is, in real time, and output, and other data is MPEG data.<u style="single">Coda</u>Is supplied to or removed from.

[0029] This set-top box was also connected to the demultiplexer 20.<u style="single">Limited reception</u>A sub-device 27 is provided, which is an additional one and may be a general device set to limit access to a signal to a particular user.

[0030] The demultiplexer 20 may be formed by, for example, a single integrated circuit. That is, one ATM processing and one MPEG-2 TS processing<u style="single">of</u>This set-top box, which uses memory 25, has great advantages. For example, the manufacturing cost can be reduced, and the number of input / output pins of the integrated circuit can be reduced.

[0031] As described above, the present invention is suitable, but not limited to, for transmission of signals over satellite or cable networks, for terrestrial broadcasting or other networks such as MMDS. Can be applied in the same way.

[Effect of the Invention] As is clear from the above description, in the present invention,<u style="single">The data of the ATM signal is stored in memory, and the data required to process the MPEG transport stream in the data of the ATM signal stored in the memory is identified. Then, based on the identification result, an address for reading the data to be demultiplexed from the memory is supplied to the MPEG demultiplexer, and the MPEG demultiplexer uses this address to obtain the demultiplexed data. Read from memory. On the other hand, the received MPEG transport stream is supplied to the MPEG demultiplexer, and the MPEG demultiplexer is used to demalize it.</u><u style="single">To</u>.. As a result, the amount of memory required for demultiplexing processing can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a diagram showing a data format in broadcasting.

FIG. 2 is a diagram showing a data format in narrow cast transmission.

FIG. 3 is a block diagram showing a specific configuration of a set-top box.

FIG. 4 is a block diagram showing a specific configuration of another set-top box.

[Code description] 21 ATM regenerator, 22 ALLPDUSAR device, 23 MPEG-2 TS demultiplexer, 24 buses