JP5692680B2 - Data transmission apparatus, program, and data transmission method - Google Patents

Description

  The present invention relates to a data transmission device, a program, and a data transmission method, and more particularly, to a data transmission device, a program, and a data transmission method in a communication system using a multiple TS (Transport Stream) transmission method.

  In a BS digital broadcast re-transmission service using a cable television network, a multiple TS transmission scheme is adopted as a scheme for efficiently transmitting a plurality of BS digital broadcast transport streams (for example, the following non-patent document). 1).

  In the multiple TS transmission scheme, a multiplexed frame (TSMF: Transport Streams Multiplexing Frame) having 53 slots is defined, and transmission of TS (transport stream) is performed by being mapped to the frame structure of the multiplexed frame. A multi-frame header in the form of a TS packet is stored in the first slot of the multi-frame. After the second slot, a predetermined slot is assigned to each business operator. MPEG2 TS packets broadcast by the service provider are stored in order in the assigned slots.

Japan CATV Technology Association Standard JCTEA STD-002-5.0 Digital Cable Television Broadcast Multiplexer, Japan CATV Technology Association, October 10, 2007

  When a transport stream is transmitted from a data transmission device (for example, a master station of a cable television communication system) to a data transmission device (for example, a slave station) via an IP (Internet Protocol) network, multiple frames are transmitted in units of a plurality of slots. By dividing, data transmission by RTP (Real-time Transport Protocol) or the like is performed as a plurality of IP packets that are arranged side by side in the slot order. One IP packet stores a plurality of (for example, seven) TS packets.

  The data transmission device performs synchronization processing of multiple frames based on the multiple frame headers received periodically. Here, since the number of slots of the multiplexed frame is a fixed value, the transmission interval of the multiplexed frame header is an equal interval. Therefore, when the data transmission apparatus receives an IP packet in which a multiple frame header is stored, the data transmission apparatus can predict an IP packet in which the next multiple frame header is stored, and multiplexes from the predicted IP packet. Extract the frame header.

  However, in data transmission via the IP network, there may occur a situation in which IP packets are lost in the IP network and some IP packets do not reach the data transmission apparatus from the data transmission apparatus. When one IP packet is lost, a plurality of TS packets stored therein are lost together. Therefore, the prediction of the IP packet in which the next multiplex frame header is stored is greatly deviated, and the multiplex frame header cannot be extracted from the predicted IP packet. Therefore, it is necessary to redo the multiplex frame synchronization processing in the data transmission apparatus. Until the synchronization is restored by detecting the next multi-frame header, all the TS packets received during that time must be discarded. The operation is significantly interrupted, and the influence is great.

  The present invention has been made in view of such circumstances, and even when an IP packet loss occurs in data transmission from a data transmission device to a data transmission device, the influence of the IP packet loss is minimized. It is an object of the present invention to obtain a data transmission device, a program, and a data transmission method that can be suppressed to the limit.

  A data transmission apparatus according to a first aspect of the present invention is a data transmission apparatus that transmits stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network, and is multiplexed. A receiving unit that receives an IP packet sequence including a plurality of consecutive IP packets, in which a predetermined multiplex frame including a plurality of stream data is divided and stored, from the data transmission device via the IP network; and the reception A data processing unit that processes the IP packet sequence received by the unit, wherein the data processing unit is received by the receiving unit among a plurality of IP packets included in the IP packet sequence transmitted from the data transmitting device. Determining means for determining the presence or absence of a missing packet that is an IP packet that has not been received, and when the determining means determines that there is a missing packet, Generating means for generating a complementary packet that is an IP packet for complementing the packet, and transmitting from the data transmitting device by inserting the complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit And a restoring means for restoring the IP packet sequence thus obtained.

  According to the data transmission apparatus according to the first aspect, the generation unit generates a complementary packet that is an IP packet for complementing the missing packet when the determination unit determines that there is a missing packet, and restores the packet. Restores the IP packet sequence transmitted from the data transmitting apparatus by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit. Therefore, even if a loss of an IP packet occurs, only the synchronization of multiple frames can be maintained by restoring the IP packet sequence transmitted from the data transmission device. There is no need to start over. As a result, it is possible to avoid a situation in which an appropriate reception operation is significantly interrupted until the synchronization is restored, so that it is possible to minimize the influence due to the loss of the IP packet.

  The data transmission apparatus according to the second aspect of the present invention is the data transmission apparatus according to the first aspect, and in particular, the IP packet sequence transmitted from the data transmission apparatus includes information on a plurality of stream data in a multiplex frame. Includes a reference packet that is an IP packet storing reference data that describes the reference data, and further includes holding means for holding reference data included in the reference packet received by the receiving unit in the past, and the missing packet is the reference packet In this case, the generation means generates a complementary packet using the reference data held by the holding means.

  Here, the “reference data” includes, for example, a multiple frame header in a multiple TS transmission scheme.

  According to the data transmission apparatus according to the second aspect, when the missing packet is a reference packet, the generation unit generates a complementary packet using the reference data held by the holding unit. Therefore, even if the reference packet is lost, it is possible to restore the IP packet sequence including the missing reference data by inserting the complementary packet generated using the reference data.

  The data transmission apparatus according to the third aspect of the present invention specifies the position where the reference data should be stored in the complementary packet when the missing packet is the reference packet, particularly in the data transmission apparatus according to the second aspect. And a generating means for generating a complementary packet by inserting the reference data held by the holding means at a position specified by the specifying means. .

  According to the data transmission apparatus of the third aspect, the specifying unit specifies the position where the reference data is to be stored in the complementary packet, and the generating unit specifies the reference data held by the holding unit. Is inserted at the specified position to generate a complementary packet. Therefore, even if the reference packet is lost, the reference data is stored at an appropriate position in the restored IP packet sequence, so that multiple frames can be reliably synchronized based on the reference data. .

  The data transmission apparatus according to the fourth aspect of the present invention is the data transmission apparatus according to any one of the first to third aspects, and in particular, the reference packet stores a multiple frame header in a multiple TS transmission scheme. The data processing unit further includes a determination unit that determines that the data transmission is based on a multi-TS transmission scheme by detecting a multiplex frame header in the IP packet sequence received by the reception unit. It is what.

  According to the data transmission apparatus according to the fourth aspect, the determination unit determines that the data transmission is based on the multiple TS transmission scheme by detecting the multiple frame header in the IP packet sequence received by the reception unit. Therefore, it is possible to automatically determine whether it is a multiple TS transmission system or a single TS transmission system depending on whether or not a multiple frame header is detected.

  The data transmission device according to a fifth aspect of the present invention is the data transmission device according to any one of the first to fourth aspects, in particular, wherein the generation means is a predetermined unit for the IP packet sequence received by the reception unit. A complementary packet is generated using data restored by error correction.

  Here, “predetermined error correction” includes, for example, use of a FEC (Forward Error Correction) packet.

  According to the data transmission apparatus of the fifth aspect, the generation unit generates the complementary packet using the data restored by the predetermined error correction for the IP packet sequence received by the receiving unit. Therefore, it is possible to correctly restore a missing IP packet as compared to a case where a complementary packet is generated by filling a null packet (a TS packet whose data content is filled with null data).

  The data transmission device according to a sixth aspect of the present invention is the data transmission device according to any one of the first to fifth aspects, and in particular, the determination means is configured to process the IP packet sequence received by the reception unit. The presence / absence of a missing packet is determined for an IP packet sequence after the rearrangement of IP packets for correcting the order of packet arrival order.

  According to the data transmission apparatus according to the sixth aspect, the determination unit is configured to perform rearrangement of the IP packets for correcting the order of the packet arrival order with respect to the IP packet sequence received by the receiving unit. The presence or absence of a missing packet is determined for the IP packet sequence. Therefore, when the packet arrival order is simply changed, it is not necessary to process the packet as a missing IP packet, and processing by the generating unit and the restoring unit is not necessary, thereby reducing the processing load on the data processing unit. It becomes possible.

  According to a seventh aspect of the present invention, there is provided a program for causing a computer installed in a data transmission apparatus that transmits stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network to function. The data transmission device is a program that transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored. From the plurality of IP packets included in the IP packet sequence transmitted from the data transmission device, and the computer receives the lost packet that is not received by the data transmission device. Determining means for determining the presence or absence of a packet, and when the determining means determines that there is a missing packet, Generating means for generating a complementary packet that is an IP packet for complementing the packet, and inserting the complementary packet at the position of the missing packet in the IP packet sequence received by the data transmission device, from the data transmission device It is characterized by functioning as a restoration means for restoring the transmitted IP packet sequence.

  According to the program according to the seventh aspect, when the determination unit determines that there is a missing packet, the generation unit generates a complementary packet that is an IP packet for complementing the lost packet, and the restoration unit includes: The IP packet sequence transmitted from the data transmitting apparatus is restored by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit. Therefore, even if a loss of an IP packet occurs, only the synchronization of multiple frames can be maintained by restoring the IP packet sequence transmitted from the data transmission device. There is no need to start over. As a result, it is possible to avoid a situation in which an appropriate reception operation is significantly interrupted until the synchronization is restored, so that it is possible to minimize the influence due to the loss of the IP packet.

  A data transmission method according to an eighth aspect of the present invention is a data transmission method in a data transmission apparatus for transmitting stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network, The data transmission apparatus transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored from the data transmission apparatus to the IP network. (A) determining whether or not there is a missing packet that is an IP packet not received by the data transmission device among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device. (B) If it is determined in step (A) that there is a missing packet, an IP packet for complementing the missing packet And (C) an IP packet transmitted from the data transmitting device by inserting the complementary packet at the position of the missing packet in the IP packet sequence received by the data transmitting device. And restoring the sequence.

  According to the data transmission method of the eighth aspect, in step (B), when it is determined in step (A) that there is a missing packet, a complementary packet that is an IP packet for complementing the missing packet is generated. In step (C), the complementary packet is inserted at the position of the missing packet in the IP packet sequence received by the data transmission device, so that the IP packet sequence transmitted from the data transmission device is restored. Therefore, even if a loss of an IP packet occurs, only the synchronization of multiple frames can be maintained by restoring the IP packet sequence transmitted from the data transmission device. There is no need to start over. As a result, it is possible to avoid a situation in which an appropriate reception operation is significantly interrupted until the synchronization is restored, so that it is possible to minimize the influence due to the loss of the IP packet.

  According to the present invention, in data transmission from a data transmission device to a data transmission device, even if an IP packet loss occurs, data that can minimize the influence of the IP packet loss A transmission device, a program, and a data transmission method can be obtained.

1 is a diagram showing an overall configuration of a communication system according to an embodiment of the present invention. It is a figure which shows the frame structure of a multi-frame. It is a figure which shows the stream data transmitted from a data transmitter. It is a figure which shows the example of one IP packet. It is a figure which shows the example of one IP packet. It is a block diagram which shows the structure of a data transmission apparatus. It is a block diagram which shows the function implement | achieved by a data processing part by running a program. It is a figure which shows the 1st example about a part of IP packet sequence which the receiving part received. It is a figure which shows the 2nd example about a part of IP packet sequence which the receiving part received. It is a figure which shows a complement packet. It is a figure which shows the decompress | restored IP packet sequence. It is a figure which shows the 3rd example about a part of IP packet sequence which the receiving part received. It is a figure which shows the 4th example about a part of IP packet sequence which the receiving part received. It is a figure which shows a complement packet. It is a figure which shows the complementary packet after replacement. It is a figure which shows the decompress | restored IP packet sequence.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the element which attached | subjected the same code | symbol in different drawing shall show the same or corresponding element.

  FIG. 1 is a diagram showing an overall configuration of a communication system 1 according to an embodiment of the present invention. The communication system 1 is a system for providing a BS digital broadcast retransmission service using a cable television network, for example. As shown in FIG. 1, the communication system 1 includes a data transmission device 2, an IP (Internet Protocol) network 3, a data transmission device 4, a modulation unit 5, a cable television network 6, and an STB (Set Top Box) 7. It is configured. The data transmission device 2 and the data transmission device 4 are connected to the IP network 3. The data transmission device 4 is connected to the modulation unit 5. The modulation unit 5 and the STB 7 are connected to the cable television network 6. The STB 7 is connected to the television 8.

  The data transmission device 2 is, for example, a master station of a cable television communication system, and the data transmission device 4 is, for example, a slave station of the system. The data transmission device 4 receives BS digital broadcast stream data received from the data transmission device 2 via the IP network 3 (a data transmission method for continuously transmitting moving images, voices, etc. (before all data has been received). Data transmitted by a reproducible system) is transmitted as a broadcast wave to the cable television network 6 via the modulation unit 5. The STB 7 receives a broadcast wave from the cable television network 6. Thereby, it is possible to view BS digital broadcasting on the television 8.

  In the communication system 1, a multiple TS transmission method is adopted as a method for efficiently transmitting a plurality of BS digital broadcast stream data. In the multiple TS transmission scheme, a multiplexed frame (TSMF: Transport Streams Multiplexing Frame) having 53 slots is defined, and transmission of stream data is performed while maintaining the frame structure of the multiplexed frame.

  FIG. 2 is a diagram illustrating a frame structure of a multiplexed frame. In the first slot (slot number “1”) of the multiplex frame, a multiplex frame header (hereinafter referred to as “TSMF header”) in the form of a TS packet is stored. After the second slot, TS packets (hereinafter referred to as “MPEG packets”) for storing stream data compressed and encoded by MPEG2 or the like are stored in a predetermined slot assigned for each business operator. The data size of each slot is 188 bytes equal to the data size of the MPEG packet. In the TSMF header, reference data that describes information related to a plurality of stream data in a multiplexed frame, such as the arrangement information of MPEG packets in each slot, is described.

  FIG. 3 is a diagram showing stream data transmitted from the data transmission device 2. As shown in FIG. 3, when stream data is transmitted from the data transmission apparatus 2 to the data transmission apparatus 4 via the IP network 3, the multiplexed frame is divided into a plurality of (in the following example, seven) slot units. As a result, data transmission by RTP (Real-time Transport Protocol) or the like is performed as a sequence of a plurality of IP packets that are arranged side by side in the slot order (hereinafter referred to as “IP packet sequence”).

  4 and 5 are diagrams showing examples of one IP packet. The IP packet shown in FIG. 4 stores data from the first slot to the seventh slot of the multiplexed frame. The IP header, the RTP header, the TSMF header corresponding to the first slot, and the second to seventh slots. Corresponding 6 MPEG packets are stored. Hereinafter, in this specification, an IP packet in which a TSMF header is stored is also referred to as a “reference packet” in order to distinguish it from other IP packets. In the IP packet shown in FIG. 5, seven MPEG packets are stored. Since the IP packet shown in FIG. 5 does not contain a TSMF header, the IP packet is not a reference packet. In the IP packets shown in FIGS. 4 and 5, the RTP header describes a sequence number of about 2 to 4 bytes, for example, continuous between a plurality of IP packets constituting the IP packet sequence.

  FIG. 6 is a block diagram showing a configuration of the data transmission device 4. As shown by the connection relationship in FIG. 6, the data transmission device 4 includes a reception unit 11, a data processing unit 12, a transmission unit 13, and a storage unit 14. The receiving unit 11 receives the IP packet sequence transmitted from the data transmitting device 2 via the IP network 3. The data processing unit 12 processes the IP packet sequence received by the receiving unit 11. The transmission unit 13 transmits the stream data processed by the data processing unit 12 to the cable television network 5. The storage unit 14 stores a program 15 for operating the data processing unit 12. The data processing unit 12 reads the program 15 from the storage unit 14 and executes it.

  FIG. 7 is a block diagram illustrating functions implemented in the data processing unit 12 by executing the program 15. As shown by the connection relationship in FIG. 7, the data processing unit 12 includes a replacement unit 20, a determination unit 21, a synchronization unit 22, a holding unit 23, a determination unit 24, a specification unit 25, a generation unit 26, FEC (Forward Error Correction). Unit 27, IP restoration unit 28, and TS restoration unit 29. In other words, the program 15 includes a data processing unit 12 as a computer mounted on the data transmission device 4, a replacement unit 20, a determination unit 21, a synchronization unit 22, a holding unit 23, a determination unit 24, a specification unit 25, This is a program for functioning as the unit 26, the FEC unit 27, the IP restoration unit 28, and the TS restoration unit 29. The determination unit 24 includes a register 30, and the specifying unit 25 includes a register 31.

  FIG. 8 is a diagram illustrating a first example of a part of the IP packet sequence received by the reception unit 11. FIG. 8 shows three consecutive IP packets X100, X101, and X102. In FIG. 8, the abbreviation “I” is attached to the IP header, the abbreviation “R” is attached to the RTP header, and the abbreviation “M” is attached to the MPEG packet (the same applies hereinafter). Since each of the IP packets X100 to X102 stores 7 MPEG packets and does not store a TSMF header, none of the IP packets X100 to X102 is a reference packet. In the example shown in FIG. 8, the sequence number described in the RTP header of the IP packet X100 is “100”, the sequence number described in the RTP header of the IP packet X101 is “101”, and the IP packet X102 The sequence number described in the RTP header is “102”.

  Referring to FIG. 7, a plurality of IP packets constituting the IP packet sequence are sequentially input from receiving unit 11 to replacing unit 20. The replacement unit 20 arranges the IP packets for correcting the order of arrival of the IP packets from the data transmission device 2 to the data transmission device 4 based on the sequence numbers of the IP packets sequentially input from the reception unit 11. Change. Referring to FIG. 8, for example, when IP packet X102 arrives earlier than IP packet X101, the sequence number of the IP packet input to replacement unit 20 is “100” → “102” → “101”. It becomes the order. In this case, the replacement unit 20 rearranges the order of the IP packet X102 having the sequence number “102” and the IP packet X101 having the sequence number “101”, thereby correctly arranging the IP packets X100 → X101 → X102. An IP packet sequence is output. In addition to the above-described process for correcting the order of arrival and departure of IP packets, when the same IP packet is received a plurality of times, a process for deleting the IP packet received at the second time or later may be performed.

  Referring to FIG. 7, the IP packet sequence output from replacement unit 20 is input to determination unit 21, determination unit 24, FEC unit 27, and IP restoration unit 28.

  The determination unit 21 detects the TSMF header in the IP packet sequence input from the replacement unit 20 to determine that the method of the IP packet sequence is a multiple TS transmission method, and determines the data transmission apparatus 4 as a plurality of TSs. Set the operation mode corresponding to the transmission method. On the other hand, the determination unit 21 determines that the method of the IP packet sequence is a single TS transmission method by not detecting the TSMF header in the IP packet sequence input from the replacement unit 20, and the data transmission device 4. Is set to the operation mode corresponding to the single TS transmission system. In this example, the multiple TS transmission method is adopted, and the determination unit 21 detects the TSMF header, so that the data transmission device 4 is set to the operation mode corresponding to the multiple TS transmission method.

  The synchronization unit 22 confirms that the TSMF headers are arranged at predetermined intervals (every 53 packets) in the IP packet sequence, and inputs the latest TSMF header to the holding unit 23. The holding unit 23 holds the latest TSMF header input from the synchronization unit 22.

  The determination unit 24 determines whether or not an IP packet is lost based on the sequence number of each IP packet input in order from the reception unit 11. That is, it is determined whether or not there is an IP packet (hereinafter referred to as “missing packet”) that has not been received by the receiving unit 11 among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device 2. . Specifically, the sequence number of the IP packet input from the receiving unit 11 is stored in the register 30, the sequence number of the IP packet input this time, and the sequence of the previously input IP packet stored in the register 30 Compare the number. If the difference is “2” or more, it is determined that the IP packet is lost.

  In the example shown in FIG. 8, the difference between the sequence number “101” of the IP packet X101 and the sequence number “100” of the IP packet X100 is “1”, and the sequence number “102” of the IP packet X102 and the IP packet X101 Since the difference from the sequence number “101” is also “1” and both are less than “2”, the determination unit 24 determines that no IP packet is lost.

  Referring to FIG. 7, the register 31 included in the specifying unit 25 stores the count value of the MPEG packet. This count value is reset to “1” every time a TSMF header is detected, and then the count value is incremented for each IP packet by a number equal to the number of MPEG packets included in each IP packet. That is, the count value of the register 31 is equal to the slot number of the MPEG packet stored at the end of each IP packet. In the example shown in FIG. 8, the count value of the register 31 is “30” corresponding to the IP packet X100, “37” corresponding to the IP packet X101, and “44” corresponding to the IP packet X102. Become.

  If the determination unit 24 determines that there is no IP packet loss, the processing in the generation unit 26, the FEC unit 27, and the IP restoration unit 28 is passed, and the TS restoration unit 29 converts the IP packet to the MPEG packet. Is restored, the restored MPEG packet is input to the transmission unit 13.

  FIG. 9 is a diagram illustrating a second example of a part of the IP packet sequence received by the reception unit 11. FIG. 9 shows an example when the IP packet X101 shown in FIG. 8 is lost.

  In the example shown in FIG. 9, the difference between the sequence number “102” of the IP packet X102 and the sequence number “100” of the IP packet X100 immediately before is “2”, and the difference is “2” or more. Therefore, the determination unit 24 determines that an IP packet is lost. In this example, the IP packet X101 is a missing packet.

  The count value of the register 31 included in the specifying unit 25 is “30” corresponding to the IP packet X100. The specifying unit 25 adds a value equal to the number of MPEG packets included in the IP packet X102 to the counter value “30” of the register 31 at that time, and uses the added value as the slot number of the multiplexed frame. Compare with the maximum value of “53”. In the example illustrated in FIG. 9, the number of MPEG packets included in the IP packet X102 is seven, and the addition value is “37”. Therefore, the addition value “37” is smaller than “53”. Information indicating that packet loss has occurred and the added value is less than “53” is input from the specifying unit 25 to the generating unit 26.

  In this case, the production | generation part 26 produces | generates the complement packet Y101 for complementing the missing packet X101 with a null packet. FIG. 10 is a diagram illustrating the complement packet Y101. The complement packet Y101 stores an IP header, an RTP header, and seven null packets. In FIG. 10, an abbreviation “N” is attached to a null packet (the same applies hereinafter). The data size of each null packet is 188 bytes equal to the data size of the MPEG packet. In the RTP header of the complement packet Y101, “101” equal to the sequence number of the missing packet X101 is described. If the MPEG packet data in the missing packet X101 can be restored by error correction by the FEC unit 27 (see FIG. 7), the data restored by the FEC unit 27 is input to the generation unit 26, and the generation unit 26 The complement packet Y101 is generated using the restored data instead of the null packet.

  The complement packet Y101 is input from the generation unit 26 to the IP restoration unit 28. Further, the count value of the register 31 included in the specifying unit 25 is incremented by a number equal to the number of null packets included in the complementary packet Y101. In this example, the value of the register 31 that was “30” corresponding to the IP packet X100 is incremented to “37” corresponding to the complement packet Y101.

  The IP restoration unit 28 inserts the complementary packet Y101 into the position of the missing packet X101 in the IP packet sequence input from the replacement unit 20 (that is, the IP packet sequence received by the reception unit 11), thereby the data transmission device 2 The IP packet sequence transmitted from is restored. FIG. 11 is a diagram showing a restored IP packet sequence. The complementary packet Y101 input from the generation unit 26 to the IP restoration unit 28 is inserted between the IP packet X100 and the IP packet X102 in the IP packet sequence (see FIG. 9) input from the replacement unit 20 to the IP restoration unit 28. Thus, the IP packet sequence in which the missing packet X101 is complemented by the complement packet Y101 is restored. The IP packet sequence restored by the IP restoration unit 28 is input to the TS restoration unit 29.

  The TS restoring unit 29 restores the IP packet sequence input from the IP restoring unit 28 from an IP packet to an MPEG packet, and inputs the restored MPEG packet to the transmitting unit 13.

  FIG. 12 is a diagram illustrating a third example of a part of the IP packet sequence received by the reception unit 11. FIG. 12 shows three consecutive IP packets X200, X201, and X202. In FIG. 12, the abbreviation “T” is added to the TSMF header (the same applies hereinafter). Since each of the IP packets X200 and X202 stores 7 MPEG packets and does not store a TSMF header, the IP packets X200 and X202 are not reference packets. The IP packet X201 stores a TSMF header and six MPEG packets. Since the TSMF header is stored, the IP packet X201 is a reference packet. In the example shown in FIG. 12, the sequence number described in the RTP header of the IP packet X200 is “200”, the sequence number described in the RTP header of the IP packet X201 is “201”, and the IP packet X202 The sequence number described in the RTP header is “202”.

  In the example shown in FIG. 12, the difference between the sequence number “201” of the IP packet X201 and the sequence number “200” of the IP packet X200 is “1”, and the sequence number “202” of the IP packet X202 and the IP packet X201 Since the difference from the sequence number “201” is also “1” and both are less than “2”, the determination unit 24 determines that no IP packet is lost.

  As described above, the count value of the register 31 included in the specifying unit 25 is reset to “1” every time the TSMF header is detected, and thereafter, the number of IP packets equal to the number of MPEG packets included in each IP packet. The count value is incremented every time. In the example shown in FIG. 12, the count value of the register 31 is “50” corresponding to the IP packet X200, “4” corresponding to the IP packet X201, and “11” corresponding to the IP packet X202. Become.

  If the determination unit 24 determines that there is no IP packet loss, the processing in the generation unit 26, the FEC unit 27, and the IP restoration unit 28 is passed, and the TS restoration unit 29 converts the IP packet to the MPEG packet. Is restored, the restored MPEG packet is input to the transmission unit 13.

  FIG. 13 is a diagram illustrating a fourth example of a part of the IP packet sequence received by the reception unit 11. FIG. 13 shows an example when the IP packet X201 shown in FIG. 12 is lost.

  In the example shown in FIG. 13, the difference between the sequence number “202” of the IP packet X202 and the sequence number “200” of the IP packet X200 immediately before is “2”, and the difference is “2” or more. Therefore, the determination unit 24 determines that an IP packet is lost. In this example, the IP packet X201, which is a reference packet, is a lost packet.

  The count value of the register 31 included in the specifying unit 25 is “50” corresponding to the IP packet X200. The specifying unit 25 adds the number of slots “7” corresponding to one IP packet to the counter value “50” of the register 31 at that time, and the value “57” is the maximum value of the slot number of the multiplexed frame. By exceeding “53”, it is detected that the missing packet X201 is a reference packet. Further, the specifying unit 25 specifies that the TSMF header is stored in the “4th” slot obtained by subtracting “53” from “57” among the seven slots corresponding to the lost packet X201. Information indicating that the reference packet is lost and the TSMF header is stored in the “4th” slot in this example is input from the specifying unit 25 to the generating unit 26.

  In this case, the generation unit 26 first generates a complement packet Y201 for complementing the missing packet X201 with a null packet. FIG. 14 is a diagram illustrating the complement packet Y201. The complement packet Y201 stores an IP header, an RTP header, and seven null packets. In the RTP header of the complement packet Y201, “201” equal to the sequence number of the missing packet X201 is described. If the MPEG packet data in the missing packet X201 can be restored by error correction by the FEC unit 27 (see FIG. 7), the data restored by the FEC unit 27 is input to the generation unit 26, and the generation unit 26 The complement packet Y201 is generated using the restored data instead of the null packet.

  Next, the generation unit 26 reads the latest TSMF header held by the holding unit 23, and reads the “4th” null packet in this example among the seven null packets included in the complementary packet Y 201. Replace with the latest TSMF header. FIG. 15 is a diagram illustrating the complement packet Y201 after replacement.

  The replaced complementary packet Y201 is input from the generation unit 26 to the IP restoration unit 28. Further, the count value of the register 31 included in the specifying unit 25 is incremented according to the complement packet Y201. In this example, after the value of the register 31 that was “50” corresponding to the IP packet X100 is reset to “1” by the TSMF header stored in the “4” th of the complementary packet Y201, By incrementing the number of null packets “3” after the TSMF header, the count value of the register 31 becomes “4”.

  The IP restoration unit 28 inserts the replaced complementary packet Y201 at the position of the missing packet X201 in the IP packet sequence input from the replacement unit 20 (that is, the IP packet sequence received by the reception unit 11). The IP packet sequence transmitted from the data transmission device 2 is restored. FIG. 16 is a diagram showing a restored IP packet sequence. The complementary packet Y201 input from the generation unit 26 to the IP recovery unit 28 is inserted between the IP packet X200 and the IP packet X202 of the IP packet sequence (see FIG. 13) input from the replacement unit 20 to the IP recovery unit 28. Thus, the IP packet sequence in which the missing packet X201 is complemented by the complement packet Y201 is restored. The IP packet sequence restored by the IP restoration unit 28 is input to the TS restoration unit 29.

  The TS restoring unit 29 restores the IP packet sequence input from the IP restoring unit 28 from an IP packet to an MPEG packet, and inputs the restored MPEG packet to the transmitting unit 13.

  As described above, according to the data transmission device 4 according to the present embodiment, the generation unit 26, when the determination unit 24 determines that there is a missing packet, is a complement packet that is an IP packet for complementing the missing packet. The IP restoring unit 28 restores the IP packet sequence transmitted from the data transmitting device 2 by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit 11. Therefore, even when the IP packet is lost, only the multiplexed frame can be synchronized by restoring the IP packet sequence transmitted from the data transmitting device 2, so that the data transmitting device 4 can maintain the multiplexed frame. There is no need to redo the synchronization process. As a result, it is possible to avoid a situation in which an appropriate reception operation is significantly interrupted until the synchronization is restored, so that it is possible to minimize the influence due to the loss of the IP packet.

  Further, according to the data transmission device 4 according to the present embodiment, when the missing packet is a reference packet, the generation unit 26 uses the reference data (the latest TSMF header in this example) held by the holding unit 23. To generate a complementary packet. Therefore, even if the reference packet is lost, it is possible to restore the IP packet sequence including the missing reference data by inserting the complementary packet generated using the reference data.

  Moreover, according to the data transmission device 4 according to the present embodiment, the specifying unit 25 specifies the position where the reference data is to be stored in the complementary packet, and the generating unit 26 is held by the holding unit 23. By inserting the reference data at the position specified by the specifying unit 25, a complementary packet is generated. Therefore, even if the reference packet is lost, the reference data is stored at an appropriate position in the restored IP packet sequence, so that multiple frames can be reliably synchronized based on the reference data. .

  Further, according to the data transmission device 4 according to the present embodiment, the determination unit 21 detects data in the multiple TS transmission scheme by detecting the TSMF header in the IP packet sequence received by the reception unit 11. Is determined. Therefore, it is possible to automatically determine whether it is a multiple TS transmission system or a single TS transmission system depending on whether or not a TSMF header is detected.

  Further, according to the data transmission device 4 according to the present embodiment, the generation unit 26 complements using data restored by predetermined error correction (in this example, FEC) for the IP packet sequence received by the reception unit 11. Generate a packet. Therefore, it is possible to correctly restore the missing IP packet as compared with the case where the complementary packet is generated by filling the null packet.

  In addition, according to the data transmission device 4 according to the present embodiment, the determination unit 24 rearranges the IP packets for correcting the order of the arrival of the packets with respect to the IP packet sequence received by the reception unit 11. The presence / absence of a missing packet is determined for the IP packet sequence that has been performed. Therefore, when the packet arrival order is simply changed, it is not necessary to process as a missing IP packet, and processing by the generation unit 26 and the IP restoration unit 28 is not necessary, so the processing load on the data processing unit 12 is reduced. It becomes possible to reduce.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

2 Data transmission device 3 IP network 4 Data transmission device 6 Cable television network 12 Data processing unit 15 Program 20 Replacement unit 21 Determination unit 22 Synchronization unit 23 Holding unit 24 Judgment unit 25 Identification unit 26 Generation unit 27 FEC unit 28 IP restoration unit 29 TS restoration part

Claims (11)

A data transmission device for transmitting stream data received from a data transmission device via an IP (Internet Protocol) network to another communication network,
A receiving unit that receives an IP packet sequence including a plurality of continuous IP packets, in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored, from the data transmission apparatus via the IP network When,
A data processing unit for processing the IP packet sequence received by the receiving unit;
With
The data processing unit
A determination unit that determines whether or not there is a missing packet that is an IP packet that is not received by the reception unit among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
Generating means for generating a complement packet that is an IP packet for complementing the missing packet when the judging means determines that there is a missing packet;
Restoring means for restoring the IP packet sequence transmitted from the data transmitting device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit;
I have a,
The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
The data transmission apparatus performs synchronization processing of multiple frames based on the reference data arranged at predetermined intervals in an IP packet sequence,
The data transmission device , wherein the generation unit generates a complementary packet having the same data amount as a missing packet . The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
Further comprising holding means for holding reference data included in reference packets received by the receiving unit in the past;
The data transmission apparatus according to claim 1, wherein when the missing packet is a reference packet, the generation unit generates a complementary packet using the reference data held by the holding unit. When the missing packet is a reference packet, further comprising a specifying means for specifying a position in which the reference data is stored in the complementary packet,
The data transmission apparatus according to claim 2, wherein the generation unit generates a complementary packet by inserting the reference data held by the holding unit at a position specified by the specifying unit. A data transmission device for transmitting stream data received from a data transmission device via an IP (Internet Protocol) network to another communication network,
A receiving unit that receives an IP packet sequence including a plurality of continuous IP packets, in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored, from the data transmission apparatus via the IP network When,
A data processing unit for processing the IP packet sequence received by the receiving unit;
With
The data processing unit
A determination unit that determines whether or not there is a missing packet that is an IP packet that is not received by the reception unit among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
Generating means for generating a complement packet that is an IP packet for complementing the missing packet when the judging means determines that there is a missing packet;
Restoring means for restoring the IP packet sequence transmitted from the data transmitting device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the receiving unit;
Have
The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
The data processing unit further includes holding means for holding reference data included in a reference packet received by the receiving unit in the past,
When the missing packet is a reference packet, the generation unit generates a complementary packet using the reference data held by the holding unit,
The data processing unit further includes a specifying unit that specifies a position where the reference data is to be stored in the complementary packet when the missing packet is the reference packet.
The data transmission apparatus, wherein the generation unit generates a complementary packet by inserting the reference data held by the holding unit at a position specified by the specifying unit. The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
In the reference packet, a multiple frame header in the multiple TS transmission method is stored,
Wherein the data processing unit, by detecting the multiplex frame header in the IP packet sequence received by the receiver, further comprising a determining means for determining that the data transmission by multiple TS transmission system, according to claim 1-4 The data transmission device according to any one of the above. Said generating means generates a complementary packet using the data recovered by the predetermined error correction for IP packet sequence received by the receiver, the data transmission apparatus according to any one of claims 1-5. The determination means determines whether or not there is a missing packet for the IP packet sequence after the IP packet rearrangement is performed to correct the order of the arrival of packets with respect to the IP packet sequence received by the receiving unit. determining, data transmission apparatus according to any one of claims 1-6. A program for causing a computer installed in a data transmission apparatus to transmit stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network,
The data transmission apparatus transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored from the data transmission apparatus to the IP network. Received through
The computer,
Judgment means for judging presence / absence of a missing packet that is an IP packet not received by the data transmission device among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
Generating means for generating a complement packet that is an IP packet for complementing the missing packet when the judging means determines that there is a missing packet;
A restoring means for restoring the IP packet sequence transmitted from the data transmitting device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the data transmission device;
Is a program to function as,
The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
The data transmission apparatus performs synchronization processing of multiple frames based on the reference data arranged at predetermined intervals in an IP packet sequence,
The generating means generates a complementary packet having the same data amount as a missing packet . A program for causing a computer installed in a data transmission apparatus to transmit stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network,
The data transmission apparatus transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored from the data transmission apparatus to the IP network. Received through
The computer,
Judgment means for judging presence / absence of a missing packet that is an IP packet not received by the data transmission device among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
Generating means for generating a complement packet that is an IP packet for complementing the missing packet when the judging means determines that there is a missing packet;
A restoring means for restoring the IP packet sequence transmitted from the data transmitting device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the data transmission device;
Holding means for holding reference data included in reference packets received by the data transmission device in the past;
As a program to function as
When the missing packet is a reference packet, the generation unit generates a complementary packet using the reference data held by the holding unit,
Said computer further
When the missing packet is a reference packet, it is a program for functioning as a specifying means for specifying a position where reference data should be stored in a complementary packet.
The generating unit generates a complementary packet by inserting the reference data held by the holding unit into a position specified by the specifying unit. A data transmission method in a data transmission apparatus for transmitting stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network,
The data transmission apparatus transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored from the data transmission apparatus to the IP network. Received through
(A) determining whether or not there is a missing packet that is an IP packet not received by the data transmission device among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
(B) when it is determined in step (A) that there is a missing packet, generating a complement packet that is an IP packet for complementing the missing packet;
(C) restoring the IP packet sequence transmitted from the data transmission device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the data transmission device;
Bei to give a,
The IP packet sequence transmitted from the data transmission device includes a reference packet that is an IP packet in which reference data describing information on a plurality of stream data in a multiplex frame is stored,
The data transmission apparatus performs synchronization processing of multiple frames based on the reference data arranged at predetermined intervals in an IP packet sequence,
In the step (B), a data transmission method for generating a complementary packet having the same data amount as that of a lost packet . A data transmission method in a data transmission apparatus for transmitting stream data received from a data transmission apparatus via an IP (Internet Protocol) network to another communication network,
The data transmission apparatus transmits an IP packet sequence including a plurality of continuous IP packets in which a predetermined multiplexed frame including a plurality of multiplexed stream data is divided and stored from the data transmission apparatus to the IP network. Received through
(A) determining whether or not there is a missing packet that is an IP packet not received by the data transmission device among a plurality of IP packets included in the IP packet sequence transmitted from the data transmission device;
(B) when it is determined in step (A) that there is a missing packet, generating a complement packet that is an IP packet for complementing the missing packet;
(C) restoring the IP packet sequence transmitted from the data transmission device by inserting a complementary packet at the position of the missing packet in the IP packet sequence received by the data transmission device;
(D) holding the reference data included in the reference packet received by the data transmission apparatus in the past;
With
In the step (B), if the missing packet is a reference packet, a complementary packet is generated using the reference data held in the step (D),
(E) when the missing packet is a reference packet, further comprising the step of specifying a position where the reference data is to be stored in the complementary packet;
In the step (B), the complementary data is generated by inserting the reference data held in the step (D) at the position specified in the step (E).

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