Broadcast signal conversion device and its program

Abstract

To provide a broadcast signal conversion device capable of preventing the MTU size from being exceeded and suppressing reduction in transmission efficiency.SOLUTION: A broadcast signal conversion device 1 includes: a video encoding unit 10 that encodes a video signal; an audio encoding unit 20 that encodes an audio signal; a control information generating unit 30 that fragments the leading fragment of control information to become a payload not exceeding a full header target fragment size, and fragments the remaining control information to become a payload not exceeding a basic fragment size; a multiplexing processing unit 40 that generates a multiplexed signal of IP packets storing the fragmented control information and the payloads of the video signal and the audio signal; and a TLV conversion unit 50 that converts the multiplexed signal of IP packets into TLV packets.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a broadcast signal conversion device and a program therefor. [Background technology]

[0002] In IP (Internet Protocol)-based broadcasting, TLV (Type Length Value) is used as an interface between IP packets and modulation frames in the physical layer. For example, in broadcasting services using MMT (MPEG Media Transport), a sequence of MMTP (MMT Protocol) / UDP (User Datagram Protocol) / IPv6 / TLV packets is stored in a modulation frame and modulated onto a broadcast wave (Non-Patent Documents 1 to 4).

[0003] When a sequence of IP packets belonging to the same IP data flow as one broadcasting service is included, the source address and port number and destination address and port number contained in the UDP / IP header remain constant and do not change. For this reason, IP header compression may be applied to the IP packet sequence to improve transmission efficiency during TLV conversion.

[0004] Figure 9(a) shows an IP packet 100 before IP header compression. This IP packet 100 includes a payload 200, an MMTP header 210, and a UDP / IPv6 header 220. Figure 9(b) shows a TLV packet 110 after IP header compression. This TLV packet 110 includes the payload 200, the MMTP header 210, either a full header 230 or a partial header 240, and a TLV header 250. In this way, the UDP / IPv6 header 220 has been converted into either the full header 230 or the partial header 240 by IP header compression.

[0005] The majority of TLV packets 110S include partial headers 240 that are largely compressed versions of the UDP / IPv6 header 220, resulting in a smaller packet size. On the other hand, some TLV packets 110L include full headers 230 that are inserted periodically regardless of the type of payload 200, resulting in a packet size that does not change significantly from before IP header compression. For example, a 48-byte UDP / IPv6 header 220 is compressed to a 3-byte partial header 240, while the full header 230 is 45 bytes. The full header 230 and partial header 240 are specified in Non-Patent Document 5, and the partial header 240 is sometimes called a compressed header. An example of how IP header compression is used in broadcasting services is specified in Non-Patent Document 3.

[0006] In addition to the MMT method, the DASH / ROUTE (Dynamic adaptive streaming over HTTP / Real-Time Object Delivery over Unidirectional Transport) method is also known as a multiplexing method for transmitting a multiplexed signal in which coded signals such as video and their control information are multiplexed using IP packets (Non-Patent Document 4). In MMT, a payload with an MMTP payload header is attached to coded video and audio signals, and then an MMTP / UDP / IP header is attached and transmitted. In contrast, in DASH / ROUTE, coded video and audio signals are transmitted as segment files in LCT (Layer Coding Transport) / ALC (Asynchronous Layered Coding) / UDP / IP packets. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] ISO / IEC 23008-1, “High efficiency coding and media delivery in heterogeneous environments: MPEG media transport” [Non-patent document 2] ARIB STD-B60, "Media Transport Method Using MMT in Digital Broadcasting" [Non-patent document 3] ARIB TR-B39, "Advanced Wideband Satellite Digital Broadcasting Operational Standards (Volume 3)" [Non-patent document 4] ATSC Standard:A / 331,“Signaling, Delivery, Synchronization, and Error Protection” [Non-Patent Document 5] ARIB STD-B32, "Video coding, audio coding and multiplexing methods for digital broadcasting" Summary of the Invention [Problem to be solved by the invention]

[0008] As shown in Figure 9(c), a TLV packet 110 may be stored in a UDP / IPv4 packet 120 as an IP transmission format between transmission / reception facilities inside and outside a broadcasting station or in an IP network. However, the UDP / IPv4 packet 120L includes a 28-byte UDP / IPv4 header 260 and a full header 230 stored in the TLV packet 110L. As a result, the size of the UDP / IPv4 packet 120L may exceed the MTU (Maximum Transmission Unit) size (e.g., 1500 bytes) of typical IP lines and facilities, preventing normal transmission. In Figure 9, if the IP packet 100 is configured to be, for example, 1491 bytes, the UDP / IPv4 packet 120L will be 1520 bytes, exceeding the MTU size, while the UDP / IPv4 packet 120S will be 1478 bytes, which is less than the MTU size, and will not exceed the MTU size. Although the TLV packet 110 may be stored in a UDP / IPv6 packet and transmitted, the data size of the UDP / IPv6 header is larger than that of the UDP / IPv4 header 260, so there is a high possibility that the MTU size will be exceeded.

[0009] To address this issue, broadcasting stations must install costly equipment capable of handling jumbo packets exceeding 1,500 bytes in their transmission and delivery facilities. Furthermore, broadcast retransmission requires the use of a fragmented TLV method, which entails a large overhead, to enable the transmission of jumbo packets over existing lines and facilities. The fragmented TLV method is a method of transmitting TLV packets by fragmenting them into MPEG-2 Transport Stream (TS) packets, storing them in IP packets, and transmitting them over IP lines using TS Over IP.

[0010] Another possible approach is to reduce the fragment size of the IP packet payload stored in all TLV packets so that TLV / UDP / IP packets including full headers do not exceed the MTU size. However, this approach increases the overhead ratio of IP packets, reducing the transmission efficiency of broadcast signals. The overhead ratio of IP packets can be defined in various ways. For example, if the data size up to the MMTP / UDP / IP header is A and the data size (fragment size) of the payload above MMTP is B, then A / (A+B) can be defined as the overhead ratio. The closer this overhead ratio is to '0', the higher the transmission efficiency, and the closer it is to '1', the lower the transmission efficiency.

[0011] Therefore, an object of the present invention is to provide a broadcast signal conversion device and a program therefor that can prevent the MTU size from being exceeded and suppress a decrease in transmission efficiency. [Means for solving the problem]

[0012] In order to solve the above problem, the broadcast signal conversion device of the present invention is a broadcast signal conversion device that converts IP packets of a broadcast signal into TLV packets so that they are equal to or smaller than a predetermined target size during IP transmission, and is configured to include a fragmentation unit, a multiplexing processing unit, and a TLV conversion unit.

[0013] According to this configuration, the broadcast signal conversion device inputs a first fragment size to the fragmentation unit, the first fragment size being set so that the size of the TLV packet storing the full header during IP transmission is equal to or smaller than the target size. This target size is a value determined depending on the operation, with one requirement being that it does not exceed the MTU size. The fragmentation unit then fragments the control information so that it becomes a payload equal to or smaller than the input first fragment size. Note that if the payload containing the entire control information does not reach the first fragment size, the fragmentation unit does not fragment the control information and instead uses the payload containing the entire control information.

[0014] In addition, the broadcast signal conversion device receives the payloads of the encoded and fragmented video and audio signals as input by the multiplexing processing unit, and generates a multiplexed signal of an IP packet that stores the fragmented control information and the payloads of the video and audio signals by the fragmentation unit. Furthermore, the broadcast signal conversion device converts, by the TLV conversion unit, the IP packet storing the payload of the control information fragmented so that the payload is equal to or smaller than the first fragment size, into a TLV packet including a full header.

[0015] In this way, the broadcast signal conversion device makes the first fragment or the entire control information a payload that is equal to or smaller than the first fragment size, taking into account the insertion of a full header, and then converts it into a TLV / UDP / IP packet that stores the full header, thereby preventing the MTU size from being exceeded on general IP lines and equipment and enabling IP transmission of TLV packets. Furthermore, because the broadcast signal conversion device does not need to reduce the fragment size of the payload stored in all IP packets, the increase in the overhead ratio of IP packets is small, and a decrease in transmission efficiency can be suppressed.

[0016] The present invention can also be realized by a program for causing a computer to function as the above-mentioned broadcast signal conversion device. [Effects of the Invention]

[0017] According to the present invention, it is possible to prevent the MTU size from being exceeded and to suppress a decrease in transmission efficiency. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing the configuration of a broadcast signal conversion device according to an embodiment; [Figure 2] In the embodiment, (a) is a diagram illustrating a multiplexed signal of IP packets before IP header compression, (b) is a diagram illustrating a TLV packet after IP header compression, and (c) is a diagram illustrating a TLV packet during IP transmission. [Figure 3] In the embodiment, (a) and (b) are explanatory diagrams of a payload. [Figure 4] FIG. 2 is an explanatory diagram illustrating a fragment of a control signal in the embodiment. [Figure 5] 5 is a flowchart illustrating an operation of a control signal generating unit in the embodiment. [Figure 6] 10 is a flowchart illustrating an operation of a TLV conversion unit in the embodiment. [Figure 7] 10 is a flowchart showing the operation of a control signal generating unit in a modified example. [Figure 8] 10 is a flowchart showing the operation of a TLV conversion unit in a modified example. [Figure 9] In the prior art, (a) is an explanatory diagram of an IP packet before IP header compression, (b) is a TLV packet after IP header compression, and (c) is a diagram illustrating a TLV packet during IP transmission. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, each embodiment described below is intended to embody the technical concept of the present invention, and unless otherwise specified, the present invention is not limited to the following. Furthermore, the same means will be given the same reference numerals, and their description may be omitted.

[0020] [Configuration of broadcast signal conversion device] The configuration of a broadcast signal conversion device 1 according to an embodiment will be described with reference to FIG. The broadcast signal conversion device 1 converts IP packets of a broadcast signal into TLV / UDP / IP packets (TLV packets) so that the size of the TLV packets is equal to or smaller than a predetermined target size when the TLV packets are transmitted over IP. As shown in Fig. 1, the broadcast signal conversion device 1 includes a video encoding unit 10, an audio encoding unit 20, a control information generation unit (fragmentation unit) 30, a multiplexing processing unit 40, a TLV conversion unit 50, and a fragment size calculation unit 60.

[0021] Video encoding unit 10 receives a video signal and encodes the input video signal. For example, video encoding unit 10 encodes the video signal using a common video encoding method such as H.265 / HEVC (High Efficiency Video Coding). At this time, video encoding unit 10 may fragment the video signal so that the payload is equal to or smaller than a basic fragment size (second fragment size) input from fragment size calculation unit 60 (described later). Then, video encoding unit 10 outputs the payload of the encoded and fragmented video signal to multiplexing processing unit 40.

[0022] Note that fragmentation refers to dividing desired data such as video signals, audio signals, and control information into pieces of a predetermined size or less so that they can be stored as the payload of an IP packet. The full-header target fragment size (first fragment size) is set so that the size of the TLV / UDP / IP packet that stores the first fragment or the entire control information during IP transmission of the TLV packet is equal to or smaller than the target size even after a full header is inserted by IP header compression. Here, the target size can be set arbitrarily, for example, MTU size = 1500 bytes. In addition, the basic fragment size (second fragment size) is set so that the size of TLV / UDP / IP packets other than those mentioned above will be equal to or smaller than the target size even after partial headers are inserted due to IP header compression, and is a value larger than the full-header target fragment size.

[0023] The audio encoder 20 receives an audio signal and encodes the input audio signal. For example, the audio encoder 20 encodes the audio signal using a common audio encoding method such as AAC (Advanced Audio Coding). At this time, the audio encoder 20 may fragment the audio signal so that the payload is equal to or smaller than the basic fragment size input from the fragment size calculator 60. The audio encoder 20 then outputs the encoded and fragmented payload of the audio signal to the multiplexing processor 40.

[0024] The payload of the video signal output by the video encoding unit 10 and the payload of the audio signal output by the audio encoding unit 20 do not have to be coded data as they are. For example, if the multiplexing method is MMT, the payload may be in the MMTP payload format with an MMTP payload header added, and if the multiplexing method is DASH / ROUTE, the payload may be in the ISOBMFF (ISO Base Media File Format) segment file format and fragmented according to the basic fragment size.

[0025] The control information generator 30 receives the full-header target fragment size from the fragment size calculator 60 and fragments the control information so that the payload is equal to or smaller than the input full-header target fragment size. However, if the payload including the entire control information does not reach the full-header target fragment size, the control information generator 30 does not fragment the control information and generates a payload including the entire control information. In this embodiment, the control information generator 30 generates a PA (Package Access) message including an MPT (MMT Package Table), which is control information defined in Non-Patent Document 2.

[0026] The control information generator 30 also receives the basic fragment size from the fragment size calculator 60, and fragments the remaining unfragmented control information using the full-header target fragment size so that the payload is equal to or smaller than the input basic fragment size. The control information generator 30 then outputs the fragmented control signal to the multiplexing processor 40.

[0027] Here, the transmission period of the full header may be longer than the transmission period of the control information that serves as the entry point. In this case, it is not necessary to insert a full header into all IP packets containing the first fragment of the control information that serves as the entry point. Therefore, the control information generator 30 fragments the first fragment of the control information or the entire control information by the full-header target fragment size at a preset full-header transmission interval. This full-header transmission interval represents the interval at which full headers are transmitted, i.e., the interval at which full headers are inserted into IP packets. For example, if the transmission period of the control information at the entry point is 100 milliseconds or less and the transmission period of the full header is 500 milliseconds or less, a full header needs to be inserted only once out of every five transmissions of control information (full-header transmission interval = 5).

[0028] The multiplexing processing unit 40 receives the payloads of the encoded and fragmented video and audio signals and generates a multiplexed signal of IP packets storing the payloads of the control information, video signal, and audio signal fragmented by the control information generating unit 30. That is, the multiplexing processing unit 40 multiplexes the payload of the video signal input from the video encoding unit 10, the payload of the audio signal input from the audio encoding unit 20, and the payload of the control signal input from the control information generating unit 30 into IP packets of the same IP data flow. For example, the multiplexing processing unit 40 performs multiplexing using a general multiplexing method such as MMT or DASH / ROUTE. The multiplexing processing unit 40 then outputs the multiplexed signal of IP packets storing the payloads of the video signal, audio signal, and control signal to the TLV conversion unit 50.

[0029] The TLV conversion unit 50 converts an IP packet storing the payload of control information fragmented so as to be a payload equal to or smaller than the full-header target fragment size into a TLV / UDP / IP packet including a full header. Further, the TLV conversion unit 50 converts an IP packet having a payload including control information fragmented at the basic fragment size into a TLV / UDP / IP packet including a partial header. At this time, the TLV conversion unit 50 performs IP header compression on the multiplexed signal of the IP packet input from the multiplexing processing unit 40. Then, the TLV conversion unit 50 performs IP transmission on the TLV / UDP / IP packet subjected to IP header compression.

[0030] In the present embodiment, the TLV conversion unit 50 converts, for each full-header transmission interval, an IP packet having a payload including control information fragmented at the full-header target fragment size into a TLV packet including a full header. Further, in the present embodiment, the TLV conversion unit 50 stores the converted TLV packet in a UDP / IPv4 packet.

[0031] The fragment size calculation unit 60 calculates the full-header target fragment size and the basic fragment size from a preset target packet size. This target packet size represents the target size of a TLV packet (TLV / UDP / IP packet) at the time of IP transmission, and is set to be not larger than the MTU size. Then, the fragment size calculation unit 60 outputs the calculated full-header target fragment size and basic fragment size to the control information generation unit 30. Further, the fragment size calculation unit 60 outputs the calculated basic fragment size to the video encoding unit 10 and the audio encoding unit 20.

[0032] <Conversion of TLV Packet> Referring to FIGS. 2 and 3, the conversion of the TLV packet will be described in detail. Figure 2(a) shows a multiplexed signal of IP packets 100 before the TLV conversion unit 50 compresses the IP header. As shown in Figure 2(a), the multiplexed signal of IP packets 100 (100A, 100B) includes payloads 200 (200A, 200B), an MMTP header 210, and a UDP / IPv6 header 220. Here, the multiplexing processing unit 40 adds the MMTP header 210 and the UDP / IPv6 header 220.

[0033] 3, payload 200 stores either a video signal 300 coded by video coding unit 10, an audio signal 310 coded by audio coding unit 20, or a control signal 320 (320A, 320B) fragmented by control information generation unit 30. Here, control signal 320A is fragmented to a payload that is equal to or smaller than the full-header target fragment size, while control signal 320B is fragmented to a payload that is equal to or smaller than the basic fragment size. For this reason, the size of payload 200A that stores control signal 320A is smaller than that of payload 200B that stores control signal 320B.

[0034] Figure 2(b) shows the TLV packet 110 after the TLV converter 50 has compressed the IP header. As shown in Figure 2(b), the TLV packet 110 (110A, 110B) includes a payload 200 (200A, 200B), an MMTP header 210, either a full header 230 or a partial header 240, and a TLV header 250. Here, the TLV converter 50 compresses the UDP / IPv6 header 220 into either the full header 230 or the partial header 240, and adds the TLV header 250.

[0035] Fig. 2(c) shows a TLV packet (UDP / IPv4 packet 120) during IP transmission. As shown in Fig. 2(c), the UDP / IPv4 packet 120 includes a TLV packet 110 (110A, 110B) and a UDP / IPv4 header 260. Here, the TLV conversion unit 50 adds the UDP / IPv4 header 260.

[0036] As mentioned above, the size of the full header 230 is 45 bytes, which is larger than the 3-byte partial header 240, so the UDP / IPv4 packet 120L exceeds the MTU size (see FIG. 9). In anticipation of this, as shown in FIG. 4, the control information generator 30 fragments the first fragment of the control signal 320 (control signal 320A) as payload 200A of the full-header target fragment size. On the other hand, the control information generator 30 fragments the remaining fragment of the control signal 320 (control signal 320B) that was not fragmented to the full-header target fragment size as payload 200B of the basic fragment size.

[0037] As a result, as shown in Figure 2(b), TLV packet 110A, which includes payload 200A fragmented at the full-header target fragment size and full header 230, is the same size as TLV packet 110B, which includes payload 200B of the basic fragment size and partial header 240. Therefore, as shown in Figure 2(c), during IP transmission, even if UDP / IPv4 header 260 is added to TLV packet 110A, UDP / IPv4 packet 120A remains below the MTU size. In the example of Figure 2(c), both UDP / IPv4 packets 120A and 120B are 1500 bytes or less.

[0038] <Calculation of full-header target fragment size and basic fragment size> The calculation of the full-header target fragment size and the basic fragment size will be described in detail below. The fragment size calculation unit 60 calculates the full-header target fragment size by subtracting the size of the UDP / IPv4 header to be added to the TLV packet, the header size of the TLV packet including the full header, and the header size of the multiplexing method from the target packet size. By using this full-header target fragment size to construct the payload, the size of the TLV packet that stores the first fragment or all of the control information during IP transmission becomes equal to or smaller than the MTU size.

[0039] In addition, the fragment size calculation unit 60 calculates the basic fragment size by subtracting the size of the UDP / IPv4 header, the header size of the TLV packet including the partial header, and the header size of the multiplexing method from the target packet size.

[0040] Here, for example, let's assume that MMT is used as the multiplexing method, and the MMTP header is operated with packet_counter_flag=0 and extension_flag=0. Also, let's assume that the MMTP / UDP / IPv6 packet is stored in a TLV packet and transmitted via IP using a TLV / UDP / IPv4 packet. In other words, the fragment size is calculated using a data structure based on the MMTP payload, including the MMTP payload header.

[0041] In this example, the target packet sizes etc. are as follows: Target packet size: 1478 bytes UDP / IPv4 header: 28 bytes (8 bytes for UDP + 20 bytes for IPv4) Header size of TLV packet including full header: 49 bytes (TLV sync 1 byte + type 1 byte + length 2 bytes + full header 45 bytes) Header size of TLV packet including partial header: 7 bytes (TLV sync 1 byte + type 1 byte + length 2 bytes + partial header 3 bytes) MMTP header size: 12 bytes

[0042] In this example, the full-header target fragment size is 1478-28-49-12=1389 bytes, and the basic fragment size is 1478-28-7-12=1431 bytes.

[0043] Note that even if the MMTP header (packet_counter_flag, extension_flag) is used differently, the header size increase is determined according to the method of use, so the basic fragment size can be calculated. Furthermore, if the use differs depending on the payload type, such as video signal, audio signal, or control information, the basic fragment size may be calculated for each. In other words, the basic fragment size for video signal and audio signal may be different from the basic fragment size for control information.

[0044] [Operation of the control information generator] The operation of the control information generator 30 will be described with reference to FIG. As shown in FIG. 5, in step S1, the control information generator 30 resets a counter to zero. In step S2, the control information generator 30 determines whether a timer interrupt has occurred, which commands the transmission of control information. For example, a timer interrupt may be a fixed-cycle timer that counts up or down a variable from an initial value at a fixed clock rate and generates an interrupt when the variable reaches a set value. This allows the control information to be generated and transmitted at fixed cycles, such as every 100 milliseconds.

[0045] If a timer interrupt occurs (Yes in step S2), the control information generator 30 proceeds to the process of step S3. If a timer interrupt does not occur (No in step S2), the control information generator 30 returns to the process of step S2. That is, the control information generator 30 idles until a timer interrupt occurs.

[0046] In step S3, the control information generator 30 generates control information. In step S4, the control information generator 30 determines whether the counter is 0 or not. If the counter is 0 (Yes in step S4), the control information generator 30 proceeds to the process in step S5. If the counter is not 0 (No in step S4), the control information generator 30 proceeds to the process of step S6.

[0047] In step S5, the control information generator 30 fragments the first fragment of the control information with the full-header target fragment size. In step S6, the control information generator 30 fragments the beginning of the control information with the basic fragment size. In step S7, the control information generator 30 outputs the fragmented control information to the multiplexing processor 40.

[0048] In step S8, the control information generator 30 determines whether or not the output of all the control information has been completed. If the output of all the control information has been completed (Yes in step S8), the control information generator 30 proceeds to the process of step S9. If the output of all the control information has not been completed (No in step S8), the control information generator 30 proceeds to the process of step S11.

[0049] In step S9, the control information generator 30 adds 1 to the counter. In step S10, the control information generator 30 determines whether the counter is equal to the full-header transmission interval. If the counter is equal to the full-header transmission interval (Yes in step S10), the control information generator 30 returns to the processing in step S1. If the counter is not equal to the full-header transmission interval (No in step S10), the control information generator 30 returns to the process in step S2.

[0050] In step S11, the control information generator 30 fragments the remaining control information with the basic fragment size, and then the control information generator 30 returns to the processing of step S7.

[0051] [TLV conversion unit operation] The operation of the TLV conversion unit 50 will be described with reference to FIG. As shown in FIG. 6, in step S20, the TLV conversion unit 50 resets the counter to zero. In step S21, the TLV conversion unit 50 receives the IP packets of the multiplexed signal.

[0052] In step S22, the TLV conversion unit 50 determines whether or not the IP packet input in step S21 is an IP packet that includes the first fragment or the entire control information of the entry point.

[0053] When MMT is used as the multiplexing method, an IP packet with packet_ID '0' and fragmentation_indicator '0' or '1' corresponds to an IP packet containing the first fragment or the entire entry point control information. In this case, the target for full header insertion is an IP packet containing the first fragment of a PA message transmitted by MMTP / UDP / IPv4 with Packet_ID=0, or an IP packet containing the entire PA message. An IP packet containing the first fragment has fragmentation_indicator=1, and an IP packet containing the entire PA message has fragmentation_indicator=0.

[0054] Furthermore, when DASH / ROUTE is used as the multiplexing method, an LCT / ALC / UDP / IP packet with a TSI (Transport Session Identifier) ​​of '0' and a TOI (Transport Object Identifier) ​​of '0' that satisfies the following condition corresponds to an IP packet containing the first fragment or the entire control information of the entry point. The above condition is limited to IP packets with TSI=0 and TOI=0, and the close_object_flag of the previous IP packet is '1'. In this case, the target for inserting a full header is a packet containing the first fragment of a file object transmitted by an LCT / ALC / UDP / IP packet with TSI=0 and TOI=0, or an IP packet containing the entire file object. In ROUTE, there is no flag that has the same function as the fragmentation_indicator in MMT, but the close_object_flag='1' indicates that the packet contains the end of a file object. Furthermore, a packet that does not divide a file object and sends the entire file object in a single packet can also be indicated by the close_object_flag='1'. Therefore, among IP packets with TSI='0' and TOI='0', the next IP packet after the IP packet with close_object_flag='1' is the first packet of a fragment of a file object or an IP packet containing the entire file object, and is the target packet for full header insertion.

[0055] If it corresponds to the IP packet (Yes in step S22), the TLV conversion unit 50 proceeds to the process of step S23. If the IP packet does not correspond to the packet (No in step S22), the TLV conversion unit 50 proceeds to the process of step S26.

[0056] In step S23, the TLV conversion unit 50 determines whether the size of the TLV / UDP / IP packet including the full header during IP transmission will not exceed the target packet size. That is, the TLV conversion unit 50 calculates backward the size of the UDP / IPv4 packet 120A in FIG. 2(c) and determines whether the calculated size will not exceed the target packet size. At the start of processing, a threshold value for the IP packet size may be calculated in advance so that the target packet size is not exceeded after full header insertion. In this case, in step S23, the size of the input IP packet may be compared with the threshold value.

[0057] If the target packet size is not exceeded (Yes in step S23), the TLV conversion unit 50 proceeds to the process of step S24. If the target packet size is exceeded (No in step S23), the TLV conversion unit 50 proceeds to the process of step S26.

[0058] In step S24, the TLV conversion unit 50 determines whether the counter is 0 or not. If the counter is 0 (Yes in step S24), the TLV conversion unit 50 proceeds to the process of step S25. If the counter is not 0 (No in step S24), the TLV conversion unit 50 proceeds to the process of step S26.

[0059] In step S25, the TLV conversion unit 50 converts the IP packet input in step S21 into a TLV packet including a full header. That is, the TLV conversion unit 50 performs IP header compression on the IP packet 100A in Fig. 2(a) and adds a UDP / IPv4 header 260 to generate the UDP / IPv4 packet 120A in Fig. 2(c).

[0060] In step S26, the TLV conversion unit 50 converts the IP packet input in step S21 into a TLV packet including a partial header. That is, the TLV conversion unit 50 performs IP header compression on the IP packet 100B in Fig. 2(a) and adds a UDP / IPv4 header 260 to generate the UDP / IPv4 packet 120B in Fig. 2(c). Thereafter, the TLV conversion unit 50 proceeds to the processing of step S30.

[0061] In step S27, the TLV conversion unit 50 adds 1 to the counter. In step S28, the TLV conversion unit 50 determines whether the counter is equal to the full-header transmission interval. If the counter is equal to the full-header transmission interval (Yes in step S28), the TLV conversion unit 50 proceeds to the process of step S29. If the counter is not equal to the full-header transmission interval (No in step S28), the TLV conversion unit 50 proceeds to the process of step S30.

[0062] In step S29, the TLV conversion unit 50 resets the counter to zero. In step S30, the TLV conversion unit 50 transmits the TLV packets converted in steps S25 and S26 to the IP transmission path. After that, the TLV conversion unit 50 returns to the processing of step S21.

[0063] [Actions and Effects] In this way, the broadcast signal conversion device 1 reduces the size of the first fragment or the entire payload of the control information compared to other payloads, taking into account the insertion of a full header, and then converts it into a TLV / UDP / IP packet that stores the full header, thereby preventing the MTU size from being exceeded in general IP lines and equipment and enabling IP transmission of TLV packets. Furthermore, since the broadcast signal conversion device 1 does not need to reduce the fragment size of the payload stored in all IP packets, the increase in the overhead ratio of IP packets is small, and a decrease in transmission efficiency can be suppressed.

[0064] Although the embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and includes design modifications and the like within the scope of the present invention.

[0065] (Variation 1) In the above embodiment, fragmentation is performed at a full-header target fragment size based on the frequency of control information transmission, which is further thinned out by the full-header transmission interval, but this is not limited to this. If the insertion period of the control information and full header at the entry point is the same, the full-header transmission interval may be set to 1, or the full-header transmission interval itself may not be taken into account. Below, as Modification 1, the operation of the control information generation unit 30 and the TLV conversion unit 50 when the full-header transmission interval is not taken into account will be described.

[0066] [Operation of the control information generator] The operation of the control information generator 30 will be described with reference to FIG. As shown in FIG. 7, in step S30, the control information generator 30 determines whether or not a timer interrupt has occurred to instruct transmission of control information.

[0067] If a timer interrupt occurs (Yes in step S30), the control information generator 30 proceeds to the process of step S31. If a timer interrupt does not occur (No in step S30), the control information generator 30 returns to the process of step S30. That is, the control information generator 30 idles until a timer interrupt occurs.

[0068] In step S31, the control information generator 30 generates control information. In step S32, the control information generator 30 fragments the first fragment of the control information by the full-header target fragment size. In step S33, the control information generator 30 outputs the fragmented control information to the multiplexing processor 40.

[0069] In step S34, the control information generator 30 determines whether or not the output of all the control information has been completed. If the output of all the control information has been completed (Yes in step S34), the control information generator 30 returns to the process of step S30. If the output of all the control information has not been completed (No in step S34), the control information generator 30 proceeds to the process of step S35. In step S35, the control information generator 30 fragments the remaining control information using the basic fragment size, and then returns to the process of step S33.

[0070] [TLV conversion unit operation] The operation of the TLV conversion unit 50 will be described with reference to FIG. As shown in FIG. 8, in step S40, the IP packets of the multiplexed signal are input to the TLV conversion unit 50.

[0071] In step S41, the TLV conversion unit 50 determines whether or not the IP packet input in step S40 is an IP packet that includes the first fragment or the entire control information of the entry point.

[0072] If it corresponds to the IP packet (Yes in step S41), the TLV conversion unit 50 proceeds to the process of step S42. If the IP packet does not correspond to the packet (No in step S41), the TLV conversion unit 50 proceeds to the process of step S44.

[0073] In step S42, the TLV conversion unit 50 determines whether the size of the TLV packet including the full header does not exceed the target packet size. If the target packet size is not exceeded (Yes in step S42), the TLV conversion unit 50 proceeds to the process of step S43. If the target packet size is exceeded (No in step S42), the TLV conversion unit 50 proceeds to the process of step S44.

[0074] In step S43, the TLV conversion unit 50 converts the IP packet input in step S40 into a TLV packet including a full header. In step S44, the TLV conversion unit 50 converts the IP packet input in step S40 into a TLV packet including a partial header. In step S45, the TLV conversion unit 50 transmits the TLV packets converted in steps S43 and S44 via IP. After that, the TLV conversion unit 50 returns to the processing of step S40.

[0075] (Variations of this) In the above embodiment, the control information generating unit generates the control information, but the control information may be input to the control information generating unit from outside.

[0076] In the above embodiment, the control information generator 30 has been described as generating a PA message including an MPT, which is control information defined in Non-Patent Document 2. However, it may also generate a PA message including a PLT (Package List Table), which is control information defined in Non-Patent Document 2. When a PLT is transmitted as a service entry point in a PA message with Packet_ID=0, the MPT referenced by the PLT can also be transmitted in a PA message with Packet_ID other than 0. In this case, since a PA message with Packet_ID other than 0 is not control information for a service entry point, it may be fragmented to have a payload equal to or smaller than the basic fragment size.

[0077] Payloads other than video and audio signals may be input to the multiplexing processor 40 from an encoding device (not shown) or the like. For example, in the case of a broadcasting service, the multiplexing processor 40 may multiplex payloads of data broadcasting and subtitle data in addition to video and audio signals. In this case, the data broadcasting and subtitle data may be fragmented so that the payload is equal to or smaller than the basic fragment size.

[0078] The payload 200 and the MMTP header 210 may be input to the TLV converter 50 without adding a UDP / IP header in the multiplexing processor 40, and the TLV converter 50 may directly add either the full header 230 or the partial header 240. In other words, the process can be simplified by omitting the step in Fig. 2(a).

[0079] In the above-described embodiment, in step S22 or step S41, when the TLV conversion unit 50 determines whether the input IP packet is an IP packet including the first fragment or the entire control information of the entry point, it analyzes the MMT or DASH / ROUTE header to make the determination, but this method is not limited to this. For example, the control information generator 30 may add a label indicating that a full header can be inserted to a packet containing the first fragment of control information fragmented at the full-header target fragment size or the entire payload. The TLV converter 50 may then determine whether the IP packet is a full-header target based on this label and convert the IP packet with this label added into a TLV packet containing a full header. This eliminates the need to analyze the MMT or DASH / ROUTE header. In this case, the IP packet with the label added is considered to have been fragmented at the full-header target fragment size. Therefore, the process of step S23 or step S42, which determines whether the size of the TLV / UDP / IP packet does not exceed the target packet size even if the full header is included, may be omitted.

[0080] In the above-described embodiment, the broadcast signal conversion device is described as an independent piece of hardware, but the present invention is not limited to this. For example, the present invention can also be realized by a program that causes hardware resources such as a CPU, memory, and hard disk of a computer to function as the above-described broadcast signal conversion device. This program may be distributed via a communication line or written to a recording medium such as a CD-ROM or flash memory. [Explanation of symbols]

[0081] 1 Broadcast signal conversion device 10 Video Encoding Unit 20 Audio coding unit 30 Control information generation unit (fragment unit) 40 Multiplexing processing unit 50 TLV conversion unit 60 Fragment size calculation unit

Claims

1. A broadcast signal conversion device that converts IP packets of a broadcast signal into TLV packets so that the size of the packets is equal to or smaller than a predetermined target size during IP transmission, a fragmentation unit that receives a first fragment size set so that the size of a TLV packet storing a full header during IP transmission is equal to or smaller than the target size, and fragments control information so that the payload is equal to or smaller than the input first fragment size; a multiplexing processing unit to which the payloads of the encoded and fragmented video and audio signals are input, and which generates a multiplexed signal of IP packets storing the control information fragmented by the fragmenting unit and the payloads of the video and audio signals; a TLV conversion unit that converts an IP packet storing a payload of the control information fragmented to have a payload equal to or smaller than the first fragment size into a TLV packet including the full header; A broadcast signal conversion device comprising:

2. the fragmentation unit fragments the control information at every preset full-header transmission interval so that the payload is equal to or smaller than the first fragment size; The broadcast signal conversion device of claim 1, characterized in that the TLV conversion unit converts an IP packet of a payload including control information fragmented to have a payload less than the first fragment size at each full header transmission interval into a TLV packet including the full header.

3. the fragmentation unit further receives a second fragment size set larger than the first fragment size, fragments a leading portion of the control information so as to have a payload equal to or smaller than the input first fragment size, and fragments the remainder of the control information that has not been fragmented with the first fragment size so as to have a payload equal to or smaller than the input second fragment size; The broadcast signal conversion device described in claim 1 or claim 2, characterized in that the TLV conversion unit converts an IP packet of a payload including control information fragmented to have a payload less than the second fragment size into a TLV packet including a partial header.

4. Calculate the first fragment size by subtracting the size of a UDP / IP header to be added to the TLV packet, the header size of the TLV packet including the full header, and the header size of a multiplexing method from a preset target packet size; The broadcast signal conversion device of claim 3, further comprising a fragment size calculation unit that calculates the second fragment size by subtracting the size of the UDP / IP header, the header size of the TLV packet including the partial header, and the header size of the multiplexing method from the target packet size.

5. The broadcast signal conversion device of claim 4, characterized in that the TLV conversion unit converts an IP packet of a multiplexed signal including control information fragmented at the first fragment size into a TLV packet including the full header when the size of the TLV packet including the full header does not exceed the target packet size.

6. The broadcast signal conversion device according to any one of claims 1 to 5, characterized in that, when MMT is used as the multiplexing method, the TLV conversion unit converts an IP packet having a packet_ID of '0' and a fragmentation_indicator of '0' or '1' into a TLV packet including the full header.

7. A broadcast signal conversion device as described in any one of claims 1 to 5, characterized in that when DASH / ROUTE is used as the multiplexing method, the TLV conversion unit converts an IP packet in which the close_object_flag of the previous IP packet is '1' into a TLV packet including the full header, limited to IP packets in which TSI is '0' and TOI is '0'.

8. the fragmentation unit adds a label indicating that the full header can be inserted to a packet including control information fragmented to have a payload equal to or smaller than the first fragment size; 8. The broadcast signal conversion device according to claim 1, wherein the TLV conversion unit converts the IP packet to which the label is added into a TLV packet including the full header.

9. a video encoding unit that encodes the video signal; an audio encoding unit that encodes the audio signal; 9. The broadcast signal conversion device according to claim 1, further comprising:

10. A program for causing a computer to function as the broadcast signal conversion device according to any one of claims 1 to 9.

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