Transmission System

Abstract

To provide a communication device, a transmission system, and a program that can achieve IP transmission of signals at low cost while ensuring redundancy that allows transmission errors to be coped with.SOLUTION: A communication device (transmission device) includes: a redundant data string generation unit that generates a redundant data string based on all data strings from a first data string to an Nth data string (N≥2) as an (N+1)th data string; and a transmission unit that transmits each data string from the first data string to the (N+1)th data string. The redundant data string allows, when an ith data string (arbitrary i; 1≤i≤N) among the first data string to the Nth data string is missing, the ith data string to be restored based on other data strings excluding the ith data string among the first data string to the Nth data string and the redundant data string. A communication device (reception device) receives data from the transmission device, and restores it when an error occurs.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a communication device, a transmission system, and a program. [Background technology]

[0002] Signal transmission using IP (Internet Protocol) has also come into practical use in broadcast program production and other such purposes. When transmitting high-quality, low-latency video signals over IP lines in program production and other such purposes, SMPTE ST2022-6, ST2110-20, or ST2110-22 are often used as the transmission format. All of these transmission formats are in the form of RTP / UDP / IP. RTP is an abbreviation for "Realtime Transport Protocol." UDP is also an abbreviation for "User Datagram Protocol."

[0003] In transmission using RTP / UDP / IP, there is no delivery confirmation as in TCP (Transmission Control Protocol). To deal with errors during transmission, two-way transmission according to SMPTE ST2022-7 is generally used. In other words, the sender sends two lines of the same RTP packets. The receiver receives these two lines of RTP packets and uses the packet that can be received correctly. If the receiver can receive both lines, it uses one of the packets.

[0004] When transmitting video signals using SMPTE ST2022-7, even if an RTP packet is lost in one of the two systems due to a transmission error, the RTP packet is received in the other system, so the video is not distorted on the receiving side.

[0005] Non-Patent Document 1 describes an IP transport method for video and audio signals. Non-Patent Document 1 also refers to duplication by SMPTE ST2022-7. Non-Patent Document 2 also describes SMPTE ST2022. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Junichiro Kawamoto, IP Transport Method for Video and Audio Signals, Lecture: IP Shift in the Broadcasting Industry, IP Program Production and Related Technologies, 3rd Lecture, Journal of the Institute of Image Information and Television Engineers, VOL. 73, No. 4, pp. 680-686, 2019. [Non-Patent Document 2] Junichiro Kawamoto, SMPTE ST 2022, Keywords to Know No. 121, Journal of the Institute of Image Information and Television Engineers, VOL. 72, No. 2, pp. 247-250, 2018. Summary of the Invention [Problem to be solved by the invention]

[0007] However, when transmitting high-quality, low-latency video signals over duplicated IP lines in broadcast program production, etc., the cost can be an issue, especially when transmitting video signals to remote locations over a wide area network (WAN).

[0008] As an example, the amount of data required to transmit uncompressed 2K video (1920 pixels horizontal x 1080 pixels vertical, YCbCr 4:2:2, 60 frames per second, progressive) is approximately 1.3 gigabits per second (Gbps). Here, Y represents the luminance signal, and Cb and Cr represent the color difference signals of the blue and red systems, respectively. In other words, a 1Gbps communication line is insufficient to transmit one system of this video signal, and a 10Gbps communication line is required. To transmit two systems using the SMPTE ST2022-7 mechanism, two 10Gbps communication lines are required, which can be cost-problematic. Ethernet is standardized at 1Gbps, 10Gbps, 25Gbps, 40Gbps, 100Gbps, etc., and there are cases where a significant increase in cost is required to secure a higher speed.

[0009] As another example, when 2K video (1920 pixels horizontal x 1080 pixels vertical, YCbCr 4:2:2, 60 frames per second, progressive) is lightly compressed to about 1 / 6, the amount of data per video is about 0.22 gigabits per second. In other words, it is possible to transmit four such compressed videos over one 1 Gbps communication line. To transmit two streams of four compressed videos, it is possible to transmit them over two 1 Gbps communication lines. However, to transmit six such compressed videos, a 10 Gbps communication line is required. To transmit two streams of six compressed videos, two 10 Gbps communication lines or four 1 Gbps communication lines are required.

[0010] As another example, when transmitting video signals between studios, the cost would be high if 40 Gigabit Ethernet were required, but costs could be reduced if 25 Gigabit Ethernet were sufficient.

[0011] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a communication device, a transmission system, and a program that can realize IP transmission of signals at low cost while ensuring redundancy that can deal with transmission errors. [Means for solving the problem]

[0012] [1] In order to solve the above problem, a communication device according to one embodiment of the present invention includes a redundant data string generation unit that generates a redundant data string based on all data strings from a first data string to an Nth data string (N≧2) as the (N+1)th data string, and a transmission unit that transmits each of the data strings from the first data string to the (N+1)th data string, wherein the redundant data string enables the restoration of the i-th data string based on the other data strings from the first data string to the Nth data string excluding the i-th data string (any i; 1≦i≦N) when the i-th data string from the first data string to the Nth data string is lost.

[0013] [2] Also, in one aspect of the present invention, in the above-mentioned communication device, the redundant data string generation unit generates the redundant data string by calculating an exclusive OR of each bit or the negation of each bit from the first data string to the Nth data string.

[0014] [3] Furthermore, in one aspect of the present invention, in the above-mentioned communication device, the transmission unit transmits each of the first data sequence through the (N+1)th data sequence via a separate communication line.

[0015] [4] Furthermore, a communication device according to one embodiment of the present invention includes a receiving unit that receives each of the first data sequence through the (N+1)th data sequence (N≧2), and a restoration unit that (a) outputs the first data sequence through the Nth data sequence when all of the first data sequence through the Nth data sequence can be received normally, and (b) when the ith data sequence (any i; 1≦i≦N) among the first data sequence through the Nth data sequence cannot be received, restores the ith data sequence based on the other data sequences from the first data sequence through the Nth data sequence excluding the ith data sequence and the (N+1)th data sequence, which is a redundant data sequence, and then outputs the first data sequence through the Nth data sequence.

[0016] [5] In another aspect of the present invention, in the above-mentioned communication device, the restoration unit restores the i-th data string by calculating an exclusive OR of each bit or the negation of each bit of the (N-1) data strings from the first data string to the Nth data string excluding the i-th data string and the redundant data string.

[0017] [6] Moreover, in one aspect of the present invention, in the above-mentioned communication device, the receiving unit receives each of the first data sequence through the (N+1)th data sequence via a separate communication line.

[0018] [7] A transmission system according to one aspect of the present invention includes a source device which outputs an identical data string from a first output terminal and a second output terminal, a first transmission device which receives the data string output from the first output terminal of the source device, divides the data string into a first data string through an N-th data string (N≧2), generates a redundant data string, an (N+1)-th data string, based on the first data string through the N-th data string, and transmits each of the first data string through the (N+1)-th data string. a second transmitting device which receives a data string, divides it into a first data string through an N-th data string, generates a redundant data string, an (N+1)-th data string, based on the first data string through the N-th data string, and transmits each of the first data string through the (N+1)-th data string; (N+1) i-th aggregating devices which select either the i-th data string (1≦i≦N+1) transmitted by the first transmitting device or the i-th data string transmitted by the second transmitting device and transmit the selected data; and a first receiving device that receives the i-th data string (1≦i≦N+1) output from the first output terminal of the i-th switch and outputs an output data string formed by integrating the first data string to the N-th data string based on the received first data string to the (N+1)-th data string; and a second receiving device that receives the i-th data string (1≦i≦N+1) output from the second output terminal of the i-th switch and outputs an output data string formed by integrating the first data string to the N-th data string based on the received first data string to the (N+1)-th data string. a second receiving device that outputs an output data sequence consisting of a first data sequence to an Nth data sequence based on the above-mentioned data sequence, and a destination device that acquires the output data sequence output by the first receiving device from a first input terminal and acquires the output data sequence output by the second receiving device from a second input terminal, wherein each of the first transmitting device and the second transmitting device is a communication device described in any one of [1] to [3] above, and each of the first receiving device and the second receiving device is a communication device described in any one of [4] to [6] above.

[0019] [8] Another aspect of the present invention is a program for causing a computer to function as the communication device described in any one of [1] to [6] above. Effect of the Invention

[0020] According to the present invention, a communication device can reduce the amount of transmission while ensuring redundancy capable of withstanding a failure or the like of a single communication line. [Brief description of the drawings]

[0021] [Figure 1] 1 is a block diagram showing a schematic functional configuration of a transmitting device and a receiving device in a transmission system according to a first embodiment of the present invention. [Diagram 2] 4 is a schematic diagram showing the processing of a distributor in the transmitting device according to the first embodiment. FIG. [Diagram 3] FIG. 4 is a schematic diagram showing the processing of an integration unit in the receiving device according to the first embodiment. [Figure 4] FIG. 11 is a block diagram showing a schematic functional configuration of a transmission system according to a second embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing an example of packet transmission between devices in the second embodiment. [Figure 6] FIG. 11 is a block diagram showing a schematic functional configuration of a transmission system according to a third embodiment. [Figure 7] FIG. 13 is a schematic diagram (1 / 3) showing an example of packet transmission between devices in the third embodiment. [Figure 8] FIG. 13 is a schematic diagram (2 / 3) showing an example of packet transmission between devices in the third embodiment. [Figure 9] FIG. 13 is a schematic diagram (3 / 3) illustrating an example of packet transmission between devices in the third embodiment. [Figure 10] FIG. 13 is a block diagram showing a schematic functional configuration of a transmission system according to a fourth embodiment. [Figure 11] FIG. 13 is a schematic diagram (1 / 3) showing an example of packet transmission between devices in the fourth embodiment. [Figure 12] FIG. 13 is a schematic diagram (2 / 3) showing an example of packet transmission between devices in the fourth embodiment. [Figure 13] FIG. 13 is a schematic diagram (3 / 3) illustrating an example of packet transmission between devices in the fourth embodiment. [Figure 14] FIG. 13 is a block diagram showing a schematic functional configuration of a transmission system according to a fifth embodiment. [Figure 15] FIG. 13 is a schematic diagram showing an example of packet transmission between devices in the fifth embodiment. [Figure 16] FIG. 2 is a block diagram showing an example of the internal configuration of each device (transmitting device 1, receiving device 2) used in each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, a number of embodiments of the present invention will be described with reference to the drawings.

[0023] [First embodiment] In an embodiment, a transmitting device transmits a signal to a receiving device using the Internet Protocol (IP). Here, the signal is a video signal, an audio signal, or the like. The transmitted signal may be only a video signal, only an audio signal, or may include a video signal and an audio signal. The signal may further include information other than video and audio.

[0024] The transmitting device temporarily terminates one IP flow, divides the flow into N packets, and transmits the IP flows as multiple IP flows. Here, N is an integer equal to or greater than 2. (N+1) is the number of communication lines (transmission paths) for transmitting signals from the transmitting device to the receiving device. The transmitting device makes the payload parts of the N packets the same length by padding if necessary, and then generates a new redundant packet (redundant signal) using a redundant signal generation function. An example of the redundant signal generation function is a function that performs an XOR operation (exclusive OR operation) on corresponding bits between packets. The transmitting device transmits the redundant packet as the (N+1)th flow in addition to the original N IP flows. As a result, the signal sent from the transmitting device has redundancy. Such a configuration of the transmitting device may be built into a camera, a gateway device (IP-GW), etc.

[0025] The receiving device receives the (N+1) flows. If necessary, the receiving device removes the padding, and then rearranges the packets to restore one IP flow. Even if the receiving device is unable to receive one of the (N+1) flows correctly, the receiving device can restore the flow that was not received by utilizing the signal redundancy. That is, the receiving device can restore the flow that was not received by using an appropriate inverse function (called a redundant signal generation inverse function) of the redundant signal generation function. Such a receiving device configuration may be built into a video monitor, a gateway device (IP-GW), etc.

[0026] 1 is a block diagram showing a schematic functional configuration of a transmission system according to the present embodiment. As shown in the figure, the transmission system 1000 includes a transmitting device 1 (also called a communication device) and a receiving device 2 (also called a communication device).

[0027] The transmitting device 1 divides one IP flow into N IP flows in a predetermined unit (for example, packet unit). The transmitting device 1 generates an (N+1)th IP flow based on the N IP flows. The transmitting device 1 transmits each of these (N+1) IP flows via a communication line. By having appropriate redundancy, even if one of the (N+1) IP flows is lost, the original N IP flows after division can be restored.

[0028] The receiving device 2 receives the (N+1) IP flows transmitted from the transmitting device 1. Even if the receiving device 2 fails to receive one of these (N+1) IP flows, it can restore the original N IP flows by utilizing the redundancy of the entire signal. The receiving device 2 arranges the N IP flows to reconstruct one IP flow.

[0029] As shown in the figure, the transmitting device 1 includes an input unit 10, a distribution unit 20 (also called a redundant data string generating unit), and a transmitting unit 30. The receiving device 2 includes a receiving unit 40, an integration unit 50 (also called a restoration unit), and an output unit 60. The functions of each unit of the transmitting device 1 and the receiving device 2 are realized, for example, by using electronic circuits. Furthermore, each functional unit may include internal storage means such as a semiconductor memory or a magnetic hard disk drive, as necessary. Furthermore, at least some of the functions may be realized by a computer and a program. The functions of each unit of the transmitting device 1 and the receiving device 2 are as follows.

[0030] The input unit 10 acquires a signal such as a video to be transmitted from the outside. The input unit 10 may acquire the signal such as a video as an IP flow, or may acquire the signal such as a video in another form. In either case, the input unit 10 passes the signal such as a video to the distribution unit 20 as one IP flow.

[0031] The distribution unit 20 divides the IP flow passed from the input unit 10 into N (N≧2) packets, and generates redundant packets based on the data of these N IP flows. More specifically, the distribution unit 20 divides N RTP packets P 1 ,P 2 ,···,P N Based on this, redundant packets P R1 Generate a redundant packet P R1 When generating the RTP packets P 1 ,P 2 ,···,P N That is, the distribution unit 20 pads bits to make N RTP packets P 1 ,P 2 ,···,P N The length of the packet is adjusted to the length of the longest packet among these N packets. Then, a redundant packet P is generated using the redundant signal generation function. R1 Generate.

[0032] That is, the distribution unit 20 generates a redundant data string based on all data strings from the first data string (packet) to the Nth data string (N≧2) as the (N+1)th data string. When the i-th data string (any i; 1≦i≦N) from the first data string to the Nth data string is lost, the redundant data string is capable of restoring the i-th data string based on the other data strings from the first data string to the Nth data string excluding the i-th data string and the redundant data string. The distribution unit 20 generates the redundant data string, for example, as follows. That is, the distribution unit 20 generates the redundant data string by calculating the exclusive OR of each bit or the negation of each bit from the first data string to the Nth data string. However, the method of generating the redundant data string is not limited to this.

[0033] Packet P 1 ,P 2 ,···,P N and redundant packet P R1 The corresponding bits of 1 ,S2 ,···,S N , and R 1 Let us assume that R 1 is calculated using the redundant signal generating function F as follows:

[0034] R 1 =F(S 1 ,S 2 ,···,S N )

[0035] An example of the redundant signal generating function F is as follows: Note that XOR here is a logical operation that calculates an exclusive OR. F(S 1 ,S 2 ,···,S N )=(S 1 )XOR(S 2 )XOR···XOR(S N )

[0036] In other words, R calculated by the function F shown above 1 is S 1 From S N The redundant signal generation function F is the exclusive OR of all bits up to S 1 From S N As long as the function preserves all bits of information up to the end of the first bit, it is not limited to the above examples. For example, the redundant signal generation function F can be 1 From S N Alternatively, a negation operator may be applied to a predetermined bit or bits among the bits up to and including , and then the exclusive OR of all of these bits may be calculated.

[0037] The distributor 20 distributes the first packet to the N-th packet, which are the division results, to the transmitters 30-1 to 30-N, respectively. The distributor 20 also distributes the generated (N+1)-th packet (redundant packet) to the transmitter 30-(N+1).

[0038] The transmitting unit 30 is a general term for the transmitting units 30-1 to 30-(N+1). The transmitting unit 30 transmits the packets distributed by the distributing unit 20 to the corresponding receiving unit 40 by IP. That is, the transmitting unit 30-i (i=1, 2, . . . , N, N+1) transmits packets to the receiving unit 40-i. That is, the transmitting unit 30 transmits each data string from the first data string to the (N+1)th data string. The transmitting unit 30 may transmit each of the first data string to the (N+1)th data string through a separate communication line. In this case, even if any communication line becomes incommunicable, it is possible to restore the data to be transmitted through the communication line that has become incommunicable based on the data transmitted through the other communication lines.

[0039] Receiving unit 40 is a general term for receiving units 40-1 to 40-(N+1). Receiving unit 40 receives packets from corresponding transmitting unit 30 via IP. Each of receiving units 40-1 to 40-(N+1) passes the received packets to integrating unit 50. If receiving unit 40 detects an event in which it cannot receive a packet due to a communication line being disconnected or the like, that receiving unit 40 notifies integrating unit 50 of the event. As a result, integrating unit 50 knows that it was unable to receive a packet on a specific communication line.

[0040] That is, the receiving unit 40 receives each of the first data string through the (N+1)th data string (N≧2). The receiving unit 40 may receive each of the first data string through the (N+1)th data string through a separate communication line, for example. In this case, when a failure occurs in a single communication line, only one of the first data string through the (N+1)th data string is lost.

[0041] The integrating unit 50 receives packets received from each receiving unit 40 and integrates these packets. The integrating unit 50 arranges N packets from the first packet to the Nth packet to restore the original IP flow. If any of these N packets cannot be received due to a communication line disconnection or the like, the integrating unit 50 uses the (N+1)th packet (redundant packet) to restore the data of the packet that could not be received. Specifically, the integrating unit 50 uses the following redundant signal generation inverse function to restore the data of the packet that could not be received.

[0042] The redundant signal generation inverse function is G 1 ,G 2 ,···,G N There are N kinds of functions G 1 is the function for recovering the first packet, and function G 2 is a function for recovering the second packet, and G 3 ,G 4 , ... N is a function for recovering the Nth packet. i (1≦i≦N) is S 1 ,S 2 ,···,S N Of S i Each bit other than and the redundant packet bit R 1 With and as arguments, S i It prints the value of , that is: S 1 =G 1 (S 2 ,S 3 ,···,S N ,R 1 ) S 2 =G 2 (S 1 ,S 3 ,···,S N ,R 1 ) The same continues below. S N-1 =G N-1 (S 1 ,S 2 ,···,S N-2,S N ,R 1 ) S N =G N (S 1 ,S 2 ,···,S N-2 ,S N-1 ,R 1 ) Once the redundant signal generating function F without loss of information is determined, the inverse redundant signal generating function G 1 ,G 2 ,···,G N Each of these is uniquely determined.

[0043] As an example, F(S 1 ,S 2 ,···,S N )=(S 1 )XOR(S 2 )XOR···XOR(S N ) In the case of , the redundant signal generation inverse function G 1 ,G 2 ,···,G N is as follows: G 1 (S 2 ,S 3 ,···,S N ,R 1 )=(S 2 )XOR(S 3 )XOR···XOR(S N )XOR(R 1 ) G 2 (S 1 ,S 3 ,···,S N ,R 1 )=(S 1 )XOR(S 3 )XOR···XOR(S N )XOR(R 1 ) The same continues below. G N-1 (S 1 ,S 2 ,···,S N-2 ,S N ,R 1 )=(S1 )XOR(S 2 )XOR···XOR(S N-2 )XOR(S N )XOR(R 1 ) G N (S 1 ,S 2 ,···,S N-2 ,S N-1 ,R 1 )=(S 1 )XOR(S 2 )XOR···XOR(S N-2 )XOR(S N-1 )XOR(R 1 )

[0044] That is, the integrating unit 50 outputs the first data string through the Nth data string by restoring the data string as follows when necessary. That is, (a) when the integrating unit 50 can normally receive all of the data strings from the first data string through the Nth data string, the integrating unit 50 outputs the first data string through the Nth data string. Also, (b) when the integrating unit 50 cannot receive the ith data string (any i; 1≦i≦N) among the data strings from the first data string through the Nth data string, the integrating unit 50 restores the ith data string based on the other data strings from the first data string through the Nth data string excluding the ith data string and the (N+1)th data string, which is a redundant data string, and then outputs the first data string through the Nth data string.

[0045] As in the above example, the integration unit 50 restores the i-th data string by calculating the exclusive OR of each bit or the negation of each bit of the (N-1) data strings excluding the i-th data string among the first data string to the N-th data string and the redundant data string. However, the method by which the integration unit 50 restores the missing data using redundancy is not limited to this.

[0046] The output unit 60 outputs the single IP flow restored by the integrator to the outside.

[0047] FIG. 2 is a schematic diagram showing the processing of the distribution unit 20 in the transmission device 1. As shown in the figure, the distribution unit 20 sequentially receives packet 1, packet 2, ..., packet N from the input unit 10. Each packet is an RTP packet. If the lengths of these N packets are different, the distribution unit 20 uses a predetermined padding to make the packet lengths uniform to a predetermined length (for example, the length of the longest packet among the N packets). In addition, the distribution unit 20 generates packet (N+1) based on packets 1 to N using the above-mentioned redundant signal generation function. This packet (N+1) is a redundant packet. The distribution unit 20 distributes these (N+1) packets to each transmission unit 30. In other words, the distribution unit 20 distributes these (N+1) packets to (N+1) communication lines.

[0048] FIG. 3 is a schematic diagram showing the processing of the integrating unit 50 in the receiving device 2. As shown in the figure, the integrating unit 50 receives packet 1, packet 2, . . . , packet N, and packet (N+1) from each receiving unit 40. If the integrating unit 50 fails to receive any of packet 1, packet 2, . . . , packet N, that is, if one of N packets is not received due to a communication line disconnection or the like, the integrating unit 50 uses the above-mentioned redundant signal generation inverse function to restore data of the packet that was not received based on the packet that was received. After completing the necessary restoration, the integrating unit 50 aligns packet 1, packet 2, . . . , packet N to reconstruct one IP flow. The integrating unit 50 passes this one IP flow to the output unit 60.

[0049] The transmitting device 1 and the receiving device 2 can repeat the same process by treating the N packets and one redundant packet shown in FIG. 2 and FIG. 3 as a group.

[0050] [Second embodiment] Next, a second embodiment will be described. Note that the matters already described in the previous embodiment may be omitted below. Here, the matters specific to this embodiment will be mainly described. Note that the transmitting device in this embodiment may be the transmitting device described in the first embodiment. Also, the receiving device in this embodiment may be the receiving device described in the first embodiment.

[0051] 4 is a block diagram showing a schematic functional configuration of a transmission system according to this embodiment. As shown in the figure, the transmission system 1001 includes a camera 101, a transmitting device 1, a receiving device 2, and a video monitor 102. In this configuration, communication is performed between the transmitting device 1 and the receiving device 2 using multiple ((N+1)) communication lines. The value of N is, for example, 2. However, the value of N may be any integer equal to or greater than 2 and is not limited to 2.

[0052] The camera 101 captures an image and outputs (supplies) a video signal.

[0053] The transmitting device 1 transmits video signals using a plurality of communication lines. As described in the first embodiment, the transmitting device 1 also generates redundant packets and transmits the redundant packets.

[0054] The receiving device 2 receives video signals using a plurality of communication lines. As described in the first embodiment, the receiving device 2 can restore video signals that could not be received by utilizing redundant packets.

[0055] The video monitor 102 is a destination of the video signal output by the receiving device 2. The video monitor 102 decodes video based on the video signal received from the receiving device 2 and displays it on a screen or the like.

[0056] The transmission system 1001 of this embodiment transmits uncompressed 2K video (1920 pixels horizontal × 1080 pixels vertical, YCbCr 4:2:2, 60 frames per second, progressive) output by the camera 101 with N=2. The data rate of this uncompressed 2K video is about 1.3 gigabits per second (Gbps). To ensure redundancy in the transmission section using conventional technology, two 10 Gigabit Ethernet (10 GbE) lines are required. In this embodiment, since N=2, the data rate per communication line is about 0.65 Gbps. In other words, in this embodiment, even if redundancy is ensured, uncompressed 2K video can be transmitted using three 1 Gigabit Ethernet (1 GbE) lines. Even if communication on any one of these three communication lines is cut off, the original data can be restored on the receiving device 2 side because the packets are made redundant. When the cost of one 10 Gigabit Ethernet cable exceeds 1.5 times the cost of one 1 Gigabit Ethernet cable, the use of this embodiment can achieve cost reduction.

[0057] In this embodiment, communication is performed between the transmitting device 1 and the receiving device 2 by IP. In the configuration shown in FIG. 4, the input from the camera 101 to the transmitting device 1 is IP data. However, an IP-GW (IP gateway device) that inputs video according to the HD-SDI (High Definition-Serial Digital Interface) standard may instead have the function of the transmitting device 1. Also, the camera 101 may have the function of the transmitting device 1 built in. Also, in the configuration of this embodiment, the output from the receiving device 2 to the video monitor 102 is IP data. However, the HD-SDI may instead have the function of the receiving device 2. Also, the video monitor 102 may have the function of the receiving device 2 built in.

[0058] In the example shown in this embodiment, an uncompressed 2K video (approximately 1.3 Gbps) is divided into two (N=2). However, the type of video and the value of the division number (N) do not have to be as shown in this example. For example, if the data rate of one stream exceeds a certain communication interface (e.g., 1 Gbps), but the data rate of each stream can be reduced to 1 / N by dividing the stream into N streams, and the data rate after division fits within the communication interface, it is still possible to transmit data with a configuration similar to that of this embodiment.

[0059] SMPTE ST2110-20, an IP transmission technology that handles uncompressed video, and ST2110-22, which handles lightly compressed video, use IP packets with an RTP / UDP / IP configuration for transmission. In this case, when splitting one IP flow into N IP flows, the flow splitting and recomposition can be controlled in units of RTP packets using the RTP sequence number.

[0060] The IP flow of a packet (redundant packet) newly generated by the operation of the redundant signal generation function (for example, XOR operation) can be associated with the original video packet, for example, by the mechanism of the FEC header of RFC 2733. In other words, the redundant packet generated by the redundant signal generation function indicates which original video packet the redundant packet corresponds to.

[0061] 5 is a schematic diagram showing an example of packet transmission between devices in the second embodiment. (A) in the figure shows packet transmission from camera 101 to transmitting device 1. (B) in the figure shows packet transmission from transmitting device 1 to receiving device 2. (C) in the figure shows packet transmission from receiving device 2 to video monitor 102.

[0062] 5(A), packets P1, P2, P3, P4, P5, and P6 are sequentially passed from the camera 101 to the transmission device 1. Each of these packets is an RTP packet.

[0063] As shown in FIG. 5B, packets are transmitted from the transmitting device 1 to the receiving device 2 via three communication lines 701, 702, and 703. The distribution unit 20 of the transmitting device 1 distributes packets P1, P3, and P5 for transmission on the communication line 701. The distribution unit 20 of the transmitting device 1 distributes packets P2, P4, and P6 for transmission on the communication line 702. The distribution unit 20 of the transmitting device 1 generates packets P-R1, P-R2, and P-R3, and distributes them for transmission on the communication line 703. The packet P-R1 is a redundant packet generated by the distribution unit 20 based on packets P1 and P2 using a redundant signal generation function. Similarly, the packet P-R2 is a packet generated by the distribution unit 20 based on packets P3 and P4. Similarly, the packet P-R3 is a packet generated by the distribution unit 20 based on packets P5 and P6. In the illustrated example, due to a line disconnection of the communication line 702, packets P2, P4, and P6 do not reach the receiving device 2. The other communication lines are normal. That is, the receiving device 2 receives packets P1, P3, and P5, and packets P-R1, P-R2, and P-R3. The receiving device 2 can restore the data of packets P2, P4, and P6 using these packets that it was able to receive. That is, using the redundant signal generation inverse function, the integrating unit 50 of the receiving device 2 restores the data of packet P2 from packets P1 and P-R1. The integrating unit 50 also restores the data of packet P4 from packets P3 and P-R2. The integrating unit 50 also restores the data of packet P6 from packets P5 and P-R3.

[0064] 5(C), packets P1, P2, P3, P4, P5, and P6 are sequentially passed from the receiving device 2 to the video monitor 102. Of these packets, packets P2, P4, and P6 are packets of data restored by the receiving device 2. The video monitor 102 can display on its screen an image based on the received packets.

[0065] [Third embodiment] Next, a third embodiment will be described. Note that the matters already described in the previous embodiments may be omitted below. Here, the matters specific to this embodiment will be mainly described. Note that the transmitting device in this embodiment may be the transmitting device described in the first embodiment. Also, the receiving device in this embodiment may be the receiving device described in the first embodiment.

[0066] 6 is a block diagram showing a schematic functional configuration of a transmission system according to this embodiment. As shown in the figure, the transmission system 1002 includes cameras 201, 202, 203,...,208, a switch 221, a transmitting device 1, a receiving device 2, a switch 222, and video monitors 211, 212, 213,...,218. The transmission system 1002 of this embodiment transmits video signals output by the eight cameras to the eight video monitors.

[0067] Cameras 201, 202, 203, . . . , 208 are cameras that capture independent images and output the image signals.

[0068] The switch 221 is a network switch that outputs an input IP packet to a predetermined network path according to the destination of the IP packet. In this configuration, the switch 221 outputs IP packets from each of the cameras 201, 202, 203, ..., 208 to a predetermined network path so that the packets reach the transmitting device 1. The communication line between the switch 221 and the transmitting device 1 will be described later.

[0069] The transmitting device 1 transmits video signals using a plurality of communication lines. As described in the first embodiment, the transmitting device 1 also generates redundant packets and transmits the redundant packets.

[0070] The receiving device 2 receives video signals using a plurality of communication lines. As described in the first embodiment, the receiving device 2 can restore video signals that could not be received by utilizing redundant packets.

[0071] The switch 222 is a network switch having the same function as the switch 221. In this configuration, the switch 222 outputs an IP packet from the receiving device 2 to a predetermined network path so that the packet reaches one of the video monitors 211, 212, 213, ..., 218 according to the destination of the packet. The communication line between the receiving device 2 and the switch 222 will be described later.

[0072] The video monitors 211, 212, 213,..., 218 are devices that receive video signals and display images. In the configuration of this embodiment, each of the video monitors 211, 212, 213,..., 218 receives a packet from the receiving device 2 via the switch 222 and displays the image.

[0073] In this embodiment, IP communication is performed at least between the transmitting device 1 and the receiving device 2. In the configuration shown in FIG. 6, each of the cameras 201 to 208 outputs a lightly compressed 2K video signal. In the case of 1 / 6 compression of 2K video, the data rate per stream is about 0.22 Gbps. For communication from each of the cameras 201 to 208 to the switch 221, for example, 1 Gigabit Ethernet can be used for each camera. That is, a total of eight 1 Gigabit Ethernets are used. The total data rate from the switch 222 to the transmitting device 1 is about 1.76 Gbps (8 x 0.22 Gbps). That is, for communication from the switch 221 to the transmitting device 1, two 1 Gigabit Ethernets or one 10 Gigabit Ethernet can be used. For communication from the transmitting device 1 to the receiving device 2, for example, three Gigabit Ethernets are used. In this configuration, N=2. For communication between the receiving device 2 and the switch 222, two 1 Gigabit Ethernets or one 10 Gigabit Ethernet can be used. For communication between the switch 222 and each of the video monitors 211 to 218, for example, a 1 Gigabit Ethernet can be used for each video monitor. In other words, a total of eight 1 Gigabit Ethernets are used.

[0074] As described above, in this embodiment as well, data transmission from transmitting device 1 to receiving device 2 is performed with N=2. That is, transmission from transmitting device 1 to receiving device 2 is performed using three communication lines. In the configuration of this embodiment, SMPTE ST2110 multicast is used. In this case, transmitting device 1 requests video signals from each of cameras 201 to 208. Also, receiving device 2 requests a signal from transmitting device 1. Also, each of video monitors 211 to 218 requests a video signal from receiving device 2.

[0075] 7, 8, and 9 are schematic diagrams showing examples of packet transmission between devices in the third embodiment. Fig. 7(A) shows packet transmission from each of cameras 201, 202, ..., 208 to switch 221. Fig. 7(B) shows packet transmission from switch 221 to transmitter 1. Fig. 8(C) shows packet transmission from transmitter 1 to receiver 2. Fig. 9(D) shows packet transmission from receiver 2 to switch 222. Fig. 9(E) shows packet transmission from switch 222 to each of video monitors 211, 212, ..., 218.

[0076] As shown in FIG. 7(A), packets P1-1, P1-2, P1-3, and P1-4 are sequentially passed from camera 201 to switch 221. Also, packets P2-1, P2-2, P2-3, and P2-4 are sequentially passed from camera 202 to switch 221. Similarly, each of cameras 203, 204, 205, 206, 207, and 208 also passes four packets to switch 221. In this figure, each of eight cameras passes four packets to switch 221. These packets are RTP packets representing video. That is, within the range shown in this figure, switch 221 receives a total of 32 packets.

[0077] 7B, the switch 221 sequentially transfers packets received from the camera to the transmitting device 1. In this figure, the illustration of individual packets is omitted. The transmitting device 1 rearranges the packets and generates redundant packets.

[0078] As shown in Fig. 8(C), transmission is performed from the transmitting device 1 to the receiving device 2 using three communication lines 701, 702, and 703. The distributor 20 of the transmitting device 1 distributes the packets received in Fig. 7(B) to the communication lines 701 and 702. One of the transmitting units 30 of the transmitting device 1 transmits packets P1-1, P2-1,...,P8-1, P1-3, P2-3,...,P8-3 in this order using the communication line 701. Another of the transmitting units 30 of the transmitting device 1 transmits packets P1-2, P2-2,...,P8-2, P1-4, P2-4,...,P8-4 in this order using the communication line 702.

[0079] Also, the distribution unit 20 of the transmitting device 1 generates a redundant packet. Specifically, the distribution unit 20 generates a redundant packet P-R1 based on the packets P1-1 and P1-2. Also, the distribution unit 20 generates a redundant packet P-R2 based on the packets P2-1 and P2-2. Similarly, the distribution unit 20 generates redundant packets (P-R3, P-R4, P-R5, P-R6, P-R7, P-R8) up to the output video from the camera 208. Furthermore, the distribution unit 20 generates a redundant packet P-R9 based on the packets P1-3 and P1-4. Also, the distribution unit 20 generates a redundant packet P-R10 based on the packets P2-3 and P2-4. Similarly, the distribution unit generates redundant packets (P-R11, P-R12, P-R13, P-R14, P-R15, P-R16) up to the output video from the camera 208. The distribution unit 20 generates these redundant packets using the redundant signal generation function described above. All of these redundant packets are transmitted using the communication line 703.

[0080] In the illustrated example, due to an event such as line disconnection in the communication line 701, the transmission of packets in the communication line fails. That is, within the illustrated range, the packets received by the receiving device 2 are only packets P1-2, P2-2, . . ., P8-2, P1-4, P2-4, . . ., P8-4 in the communication line 702 and packets P-R1, P-R2, . . ., P-R8, P-R9, P-R10, . . ., P-R16 in the communication line 703. The integrating unit 50 in the receiving device 2 generates data of packets that could not be received based on packets that could be received using a redundant signal generation inverse function. That is, the integrating unit 50 restores data of packets P1-1, P2-1, . . ., P8-1, P1-3, P2-3, . . ., P8-3 using packets that could be received.

[0081] As shown in Fig. 9(D), the receiving device 2 passes video packets from the eight cameras to the switch 222. These packets include packets restored by the integration unit 50 of the receiving device 2 based on redundant packets. Each packet transmitted from the receiving device 2 is addressed to the address of one of the eight video monitors 211, 212,..., 218. In this figure, the packets are omitted.

[0082] 9(E), switch 222 transfers packets transmitted from receiving device 2 to the respective destination video monitors. Specifically, switch 222 sequentially transmits packets P1-1, P1-2, P1-3, and P1-4 to video monitor 211. Switch 222 also sequentially transmits packets P2-1, P2-2, P2-3, and P2-4 to video monitor 212. Similarly, switch 222 transmits packets to each of the eight video monitors up to video monitor 218. That is, four packets reach each video monitor within the illustrated range.

[0083] 7, 8, and 9, the process in which each of the cameras 201 to 208 transmits four packets and each of the video monitors 211 to 218 receives the four packets has been described. The transmission system 1002 can repeatedly execute this process. This allows a video signal of any length to be transmitted from the camera side to the video monitor side via transmission between the transmitting device 1 and the receiving device 2.

[0084] In this third embodiment, eight streams could be transmitted using three 1-gigabit Ethernets. Moreover, because redundant packets were generated and transmitted, even if one of the three communication lines was disconnected, the data of the lost packets could be restored. When redundancy was achieved using conventional technology, four 1-gigabit Ethernets or two 10-gigabit Ethernets were required for transmission. In other words, redundancy can be ensured at a lower cost than when conventional technology is used.

[0085] In addition, not only in the case of transmitting eight streams as exemplified in this embodiment, but also in the case of transmitting five or more and seven or less streams, for example, by using this embodiment, it is possible to realize signal transmission at a lower cost. Specifically, it is as follows. The data rate of one lightly compressed 2K video is 0.22 Gbps. In any case of five, six, or seven streams, the streams can be divided and transmitted to the first and second communication lines. In addition, the third communication line can transmit redundant packets. That is, in any of these cases, a redundant signal can be transmitted using three 1 Gigabit Ethernets. On the other hand, in the case of using the conventional technology, in order to transmit five, six, or seven streams, a total of four 1 Gigabit Ethernets are required, including two 1 Gigabit Ethernets and two 1 Gigabit Ethernets for redundant packets. Alternatively, in the case of using the conventional technology, two 10 Gigabit Ethernets are required instead of the four 1 Gigabit Ethernets. That is, in any of these cases, by using this embodiment, it is possible to reduce the cost of the communication lines.

[0086] Furthermore, the application of this embodiment is not limited to the case of lightly compressed 2K video where N=2. This embodiment can be applied when the total data rate of multiple streams exceeds the interface speed of a certain communication line, but can be made within the interface speed of the communication line by dividing them into N. This also makes it possible to reduce the cost of the communication line.

[0087] [Fourth embodiment] Next, a fourth embodiment will be described. Note that the matters already described in the previous embodiments may be omitted below. Here, the matters specific to this embodiment will be mainly described. Note that the transmitting device in this embodiment may be the transmitting device described in the first embodiment. Also, the receiving device in this embodiment may be the receiving device described in the first embodiment.

[0088] The transmission system of the fourth embodiment has a configuration for the case where a video transmitting device (such as a camera) and a video receiving device (such as a video monitor) are originally compatible with the redundancy of SMPTE ST2022-7. In this embodiment, two systems of transmitting devices and receiving devices are prepared, and then an aggregating device transmits data in a form in which the data flow is aggregated. The aggregating device has a receiving function of SMPTE ST2022-7, aggregates the two systems, and then retransmits the received packets as IP.

[0089] 10 is a block diagram showing a schematic functional configuration of a transmission system according to the present embodiment. As shown in the figure, the transmission system 1003 includes a camera 103, transmitting devices 1-1 and 1-2, receiving devices 2-1 and 2-2, switches 231, 232, 233, 234, 235, 236, and 237, aggregation devices 261, 262, and 263, and a video monitor 104.

[0090] Camera 103 captures video and outputs a signal of the captured video. Camera 103 is compatible with SMPTE ST2022-7 and outputs the captured uncompressed 2K video (approximately 1.3 Gbps) through two systems. In other words, camera 103 is a product that is originally designed to transmit the same video through two systems. In the configuration shown in the figure, camera 103 outputs a video signal to transmitting device 1-1 via switch 231 as a first system. Camera 103 also outputs a video signal to transmitting device 1-2 via switch 232 as a second system.

[0091] Each of the transmitting devices 1-1 and 1-2 has a function of rearranging an input video signal in packet units and transmitting the signal through N communication lines (from the first communication line to the Nth communication line). Each of the transmitting devices 1-1 and 1-2 also generates a redundant packet based on the input video signal. Each of the transmitting devices 1-1 and 1-2 transmits the generated redundant packet through the (N+1)th communication line. Each of the transmitting devices 1-1 and 1-2 may be the transmitting device 1 in the first embodiment.

[0092] Each of the receiving devices 2-1 and 2-2 has a function of arranging packets (RTP packets) received on N communication lines (from the first communication line to the Nth communication line) and outputting them as one IP flow (video signal). Each of the receiving devices 2-1 and 2-2 also receives a redundant packet on the (N+1)th communication line. When each of the receiving devices 2-1 and 2-2 cannot receive a signal on any of the first communication line to the Nth communication line, it can use the redundant packet received on the (N+1)th communication line to restore data of the packet on the communication line that could not be received. Each of the receiving devices 2-1 and 2-2 may be the receiving device 2 in the first embodiment.

[0093] Each of the switches 231, 232, 233, 234, 235, 236, and 237 is a network switch. Each switch outputs an input IP packet to a predetermined network path according to the destination.

[0094] Specifically, the switch 231 transfers packets from the output of the first system of the camera 103 to the transmitting device 1-1. The switch 231 also transfers packets to be transmitted on each of the three communication lines output from the transmitting device 1-1 to the aggregation devices 261, 262, and 263. The switch 232 transfers packets from the output of the second system of the camera 103 to the transmitting device 1-2. The switch 232 also transfers packets to be transmitted on each of the three communication lines output from the transmitting device 1-1 to the aggregation devices 261, 262, and 263. The switch 233 transfers packets received from the aggregation device 261 through the first communication line to both the receiving device 2-1 side (the switch 236 side) and the receiving device 2-2 side (the switch 237 side). The switch 234 transfers packets received from the aggregation device 261 through the second communication line to both the receiving device 2-1 side (switch 236 side) and the receiving device 2-2 side (switch 237 side). The switch 235 transfers packets received from the aggregation device 261 through the third communication line to both the receiving device 2-1 side (switch 236 side) and the receiving device 2-2 side (switch 237 side). The switch 236 transfers packets (first system side) from each of the switches 233, 234, and 235 to the receiving device 2-1. The switch 237 transfers packets (second system side) from each of the switches 233, 234, and 235 to the receiving device 2-2.

[0095] The aggregation devices 261, 262, and 263 each select either the data string from the transmitting device 1-1 or the data string from the transmitting device 1-2, and transmit the selected data to the switches 233, 234, and 235, respectively. The aggregation devices 261, 262, and 263 each receive different data from the transmitting device side. It is assumed that the data received by each of the aggregation devices 261, 262, and 263 from the transmitting devices 1-1 and 1-2 is the same data unless there is an error or the like. In other words, the aggregation devices 261, 262, and 263 aggregate the system on the transmitting device 1-1 side and the system on the transmitting device 1-2 side. The aggregation devices 261, 262, and 263 each transmit packets to the switches 233, 234, and 235 through the communication lines of the WAN.

[0096] The switches 233, 234, and 235 pass the data they receive to both the receiving devices 2-1 and 2-2.

[0097] The video monitor 104 receives the video signal and displays the received video on the screen. The video monitor 104 is compatible with SMPTE ST2022-7 and inputs video signals through two systems. The video monitor 104 decodes one of the video signals received from both systems and displays it on the screen. Selection of one of the two systems may be based on settings or on the results of comparing the states of the received signals. When the video monitor 104 can only receive video signals from one of the two systems, it decodes the video signal from the system that it can receive and displays it on the screen.

[0098] In the configuration shown in Fig. 10, 10 Gigabit Ethernet can be used as the transmission path from camera 103 to transmitter 1-1 via switch 231, and as the transmission path from camera 103 to transmitter 1-2 via switch 232. Also, 10 Gigabit Ethernet can be used as the transmission path from receiver 2-1 to video monitor 104 via switch 236, and as the transmission path from receiver 2-2 to video monitor 104 via switch 237. For the other transmission paths in Fig. 10, including the WAN portion, 1 Gbps communication lines can be used.

[0099] In the configuration shown in FIG. 10, each of the transmitting devices 1-1 and 1-2 transmits packets of the video signal passed from the camera 103, with N=2, through the first and second communication lines. Also, each of the transmitting devices 1-1 and 1-2 generates a redundant packet and transmits it through the third communication line. However, each of the aggregation devices 261, 262, and 263 aggregates packets from the system of the transmitting device 1-1 side and the system of the transmitting device 1-2, and transmits one of the packets to the receiving device side (the switches 233, 234, and 235, respectively). Then, on the receiving device side, the switches 233, 234, and 235 distribute the packets received from the aggregation devices 261, 262, and 263 to both the receiving device 2-1 side and the receiving device 2-2 side, respectively. Incidentally, the packets to the receiving device 2-1 go through the switch 236. The packets to the receiving device 2-2 go through the switch 237. Each of the receiving devices 2-1 and 2-2 passes the received video packets to the video monitor 104. The packets from the receiving device 2-1 are passed to the first of the two input systems of the video monitor 104. The packets from the receiving device 2-2 are passed to the second input system of the video monitor 104.

[0100] That is, in the configuration shown in FIG. 10, in the area of ​​the transmitting side and the area of ​​the receiving side, two-way transmission is performed in accordance with the ST2022-7 method. The area of ​​the transmitting side is the part of the transmission from the camera 103 to the aggregation devices 261, 262, and 263. The area of ​​the receiving side is the part of the transmission from the switches 233, 234, and 235 to the video monitor 104. In addition, in the transmission part by the WAN, a signal having redundancy is transmitted. This redundancy is obtained by the redundant packets generated by the transmitting devices 1-1 and 1-2. Each of the aggregation devices 261, 262, and 263 selects one of the RTP packets in the two ways (the transmitting device 1-1 side and the transmitting device 1-2 side) and transmits it to the switches 233, 234, and 235.

[0101] 11, 12, and 13 are schematic diagrams showing an example of packet transmission between devices in the fourth embodiment. FIG. 11(A) shows packet transmission from the camera 103 to each of the transmitting devices 1-1 and 1-2. The switches 231 and 232 through which the transmission passes are omitted here. FIG. 11(B) shows packet transmission from each of the transmitting devices 1-1 and 1-2 to each of the aggregation devices 261, 262, and 263. The switches 231 and 232 through which the transmission passes are omitted here. FIG. 12(C) shows packet transmission from the aggregation device 261 to the switch 233, from the aggregation device 262 to the switch 234, and from the aggregation device 263 to the switch 235. FIG. 13(D) shows packet transmission from each of the aggregation devices 261, 262, and 263 to each of the receiving devices 2-1 and 2-2. Note that the switches 236 and 237 through which this transmission goes are not shown here. Fig. 13(E) shows the transmission of packets from each of the receiving devices 2-1 and 2-2 to the video monitor 104. Note that the switches 236 and 237 through which this transmission goes are not shown here.

[0102] 11A, packets P1, P2, P3, and P4 are sequentially delivered in the system from the camera 103 to the transmitting devices 1-1 and 1-2. The transmitting devices 1-1 and 1-2 generate redundant packets P-R1 and P-R2, respectively.

[0103] 11B, the transmitting device 1-1 sequentially passes packets P1 and P3 to the aggregation device 261, packets P2 and P4 to the aggregation device 262, and packets P-R1 and P-R2 to the aggregation device 263. The transmitting device 1-2 also sequentially passes packets P1 and P3 to the aggregation device 261, packets P2 and P4 to the aggregation device 262, and packets P-R1 and P-R2 to the aggregation device 263. Each of the aggregation devices 261, 262, and 263 selects packets of one of the systems from the packets received from both systems to transmit to the receiving side switches 233, 234, and 235.

[0104] 12C, the aggregation device 261 sequentially transmits packets P1 and P3 to the switch 233 via the WAN line. The aggregation device 262 sequentially transmits packets P2 and P4 to the switch 234 via the WAN line. The aggregation device 263 sequentially transmits packets P-R1 and P-R2 to the switch 235 via the WAN line.

[0105] As shown in FIG. 13(D), the switch 233 passes packets P1 and P3 received from the transmitting device to both the receiving device 2-1 and the receiving device 2-2. The switch 234 passes packets P2 and P4 received from the transmitting device to both the receiving device 2-1 and the receiving device 2-2. The switch 235 passes packets P-R1 and P-R2 received from the transmitting device to both the receiving device 2-1 and the receiving device 2-2. Each of the receiving devices 2-1 and 2-2 reconstructs the flow by arranging the received packets. Each of the receiving devices 2-1 and 2-2 reconstructs the flow by using redundant packets to restore the data of the lost packets if any packets are lost during transmission.

[0106] 13(E), both receiving devices 2-1 and 2-2 sequentially transmit packets P1, P2, P3, and P4 to the video monitor 104. The video monitor 104 receives the packet trains of both systems, decodes video based on the packets of either system, and displays it on the screen.

[0107] That is, the transmission system 1003 of the fourth embodiment has the following configuration. With such a configuration, it is possible to reduce the required communication line capacity in signal transmission between a source device having a redundant output terminal and a destination device having a redundant input terminal. Here, the source device and the destination device are products that comply with the SMPTE ST2022-7 standard, for example.

[0108] A source device (e.g., camera 103) outputs the same data string from a first output terminal and a second output terminal (in FIG. 10, addressed to transmitting device 1-1 and transmitting device 1-2). A first transmitting device (transmitting device 1-1) inputs the data string output from the first output terminal of the source device, divides the data string into a first data string through an N-th data string (N≧2), generates an (N+1)-th data string that is a redundant data string based on the first data string through the N-th data string, and transmits each of the first data string through the (N+1)-th data string (in FIG. 10, addressed to aggregation devices 261, 262, and 263, respectively). A second transmitting device (transmitting device 1-2) inputs the data sequence output from the second output terminal of the source device, divides it into a first data sequence through an Nth data sequence, generates an (N+1)th data sequence, which is a redundant data sequence, based on the first data sequence through the Nth data sequence, and transmits each of the first data sequence through the (N+1)th data sequence (in FIG. 10, addressed to each of aggregation devices 261, 262, and 263).

[0109] The i-th aggregation device (respectively, aggregation devices 261, 262, and 263 in FIG. 10) selects and transmits either the i-th data sequence (1≦i≦N+1) transmitted by the first transmission device or the i-th data sequence transmitted by the second transmission device. The i-th aggregation device is (N+1) aggregation devices from the first aggregation device to the (N+1)-th aggregation device. The i-th switch (respectively, switches 233, 234, and 235 in FIG. 10) receives the i-th data sequence transmitted by the i-th aggregation device (1≦i≦N+1) and outputs the i-th data sequence from each of the first output terminal and the second output terminal. The i-th switch is (N+1) switches from the first switch to the (N+1)-th switch.

[0110] The first receiving device (receiving device 2-1) receives the ith data sequence (1≦i≦N+1) output from the first output terminal of the ith switch, and outputs an output data sequence consisting of the first data sequence through the Nth data sequence integrated based on the received first data sequence through the (N+1)th data sequence. The second receiving device (receiving device 2-2) receives the ith data sequence (1≦i≦N+1) output from the second output terminal of the ith switch, and outputs an output data sequence consisting of the first data sequence through the Nth data sequence integrated based on the received first data sequence through the (N+1)th data sequence. The destination device (e.g., video monitor 104) obtains the output data sequence output by the first receiving device from a first input terminal, and obtains the output data sequence output by the second receiving device from a second input terminal.

[0111] In the configuration of this embodiment, redundancy is ensured so that video transmission is not interrupted even if any one of the transmitting devices 1-1 and 1-2, the aggregation devices 261, 262, and 263, the receiving devices 2-1 and 2-2, and the switches 231 to 237 breaks down. Also, redundancy is ensured so that video transmission is not interrupted even if any one of the illustrated communication lines 701, 702, and 703 is disconnected. Also, in this embodiment, it is possible to transmit redundant signals using three 1 Gigabit Ethernet lines. That is, this embodiment is advantageous compared to the conventional technology which requires two 10 Gigabit Ethernet communication lines (when the cost of two 10 Gigabit Ethernet lines exceeds the cost of three 1 Gigabit Ethernet lines).

[0112] In this embodiment, a case where uncompressed 2K video is transmitted with N=2 has been described, but the present invention is not limited to this example. This embodiment can be applied to cases where a single stream exceeds the interface speed of a certain communication line, but can be kept within the speed by reducing the speed to 1 / N.

[0113] [Fifth embodiment] Next, a fifth embodiment will be described. Note that the matters already explained in the previous embodiments may be omitted below. Here, the matters specific to this embodiment will be mainly explained. A feature of the transmission system of the fifth embodiment is that the bit rates of the multiple communication lines for communication between the transmitting device 1 and the receiving device 2 are at least partially different. Note that the transmitting device in this embodiment may be the transmitting device explained in the first embodiment. Also, the receiving device in this embodiment may be the receiving device explained in the first embodiment.

[0114] 14 is a block diagram showing a schematic functional configuration of a transmission system according to this embodiment. As shown in the figure, a transmission system 1004 includes a transmitting device 1 and a receiving device 2. Communication lines 701, 702, and 703 are provided between the transmitting device 1 and the receiving device 2. In the example shown in the figure, the capacity of the communication line 701 is 1 Gbps. Furthermore, the capacities of the communication lines 702 and 703 are each 2 Gbps. In this way, the capacities of the communication lines used between the transmitting device 1 and the receiving device 2 may be different.

[0115] FIG. 15 is a schematic diagram showing an example of packet transmission from a transmitting device 1 to a receiving device 2 in the fifth embodiment. In this embodiment, the transmitting device 1 transmits three video signals, conveniently called A, B, and C, to the receiving device 2. FIG. 15 shows the configuration of packets transmitted in a predetermined unit period. In the figure, packets P-A1 and P-A2 are RTP packets of video A. Also, packets P-B1 and P-B2 are RTP packets of video B. Also, packets P-C1 and P-C2 are RTP packets of video C. The video signals of videos A, B, and C are each transmitted at a rate of 0.6 Gbps, for example.

[0116] Packets P-R1, P-R2, P-R3, and P-R4 are redundant packets generated by the distribution unit 20 of the transmitting device 1. Here, packet P-R1 is a packet generated by the distribution unit 20 based on packets P-A1 and P-B1 using a redundant signal generation function. Similarly, packet P-R2 is a packet generated by the distribution unit 20 based on packets P-A1 and P-C1. Moreover, packet P-R3 is a packet generated by the distribution unit 20 based on packets P-A2 and P-B2 using a redundant signal generation function. Moreover, packet P-R4 is a packet generated by the distribution unit 20 based on packets P-A2 and P-C2.

[0117] As an example, packet P-R1 is generated by taking the exclusive OR of corresponding bits of packets P-A1 and P-B1.

[0118] As described above, when the video signal rate of each of the videos A, B, and C is 0.6 Gbps, if the transmission method of this embodiment is used, it is possible to transmit the videos A, B, and C using one 1 Gbps communication line and two 2 Gbps communication lines while ensuring redundancy. On the other hand, if the conventional technology is used, one 1 Gbps communication line and two 2 Gbps communication lines are insufficient to transmit the videos A, B, and C while ensuring redundancy. If the conventional technology is used, for example, three 2 Gbps communication lines or six 1 Gbps communication lines are required.

[0119] By using any one of the first to fifth embodiments described above, it is possible to ensure redundancy, that is, the ability to continue signal transmission even if one of multiple lines is cut, while enabling transmission over a slower (lower cost) communication line. In other words, it is possible to reduce the total transmission volume while ensuring redundancy.

[0120] FIG. 16 is a block diagram showing an example of the internal configuration of each device (transmitting device 1, receiving device 2, etc.) used in the first to fifth embodiments. Each device can be realized using a computer. As shown in the figure, the computer is configured to include a central processing unit 1901, a RAM 1902, an input / output port 1903, input / output devices 1904 and 1905, etc., and a bus 1906. The computer itself can be realized using existing technology. The central processing unit 1901 executes instructions included in a program read from the RAM 1902, etc. The central processing unit 1901 writes data to the RAM 1902, reads data from the RAM 1902, and performs arithmetic and logical operations according to each instruction. The RAM 1902 stores data and programs. Each element included in the RAM 1902 has an address and can be accessed using the address. Note that RAM is an abbreviation for "random access memory." The input / output port 1903 is a port through which the central processing unit 1901 exchanges data with external input / output devices, etc. The input / output devices 1904 and 1905 are input / output devices. The input / output devices 1904 and 1905 exchange data with the central processing unit 1901 via the input / output port 1903. The bus 1906 is a common communication path used within the computer. For example, the central processing unit 1901 reads and writes data in the RAM 1902 via the bus 1906. Also, for example, the central processing unit 1901 accesses the input / output ports via the bus 1906.

[0121] At least some of the functions of the transmitting device and the receiving device in the above-mentioned embodiment can be realized by a computer. In that case, a program for realizing the functions may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the functions. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to a portable medium such as a flexible disk, an optical magnetic disk, a ROM, a CD-ROM, a DVD-ROM, a USB memory, and a storage device such as a hard disk built into a computer system. In other words, the term "computer-readable recording medium" may be a non-transitory computer-readable recording medium. The term "computer-readable recording medium" may also include a medium that temporarily and dynamically holds a program, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-mentioned program may be a program for realizing some of the above-mentioned functions, and may further be a program that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0122] Although a number of embodiments have been described above, the present invention can also be embodied in the following modified examples. In the above-described embodiment, the redundant signal generation function and the redundant signal generation inverse function are realized mainly using an exclusive OR operation (a negation operation may be appropriately combined). However, the redundant signal generation function is not limited to such a function. Other forms of functions may be used as long as they satisfy the requirements as a function for generating an appropriate redundant data string. The requirements that the redundant signal generation function should satisfy are as follows. That is, when an i-th data string (any i; 1≦i≦N) among the first data string to the N-th data string is lost, the redundant data string can be restored based on the other data strings from the first data string to the N-th data string excluding the i-th data string and the redundant data string. The redundant signal generation inverse function is an inverse function thereof.

[0123] In the above embodiment, an example in which the transmitting device and the receiving device are connected by three communication lines has been described, but the number of communication lines between the transmitting device and the receiving device may be (N+1), where N is an integer equal to or greater than 2. N is the number of transmission paths for packets excluding redundant packets.

[0124] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Industrial Applicability]

[0125] The present invention can be used, for example, for transmitting signals. As an example, the present invention can be used for transmitting video content and audio content. However, the scope of use of the present invention is not limited to the examples given here. [Explanation of symbols]

[0126] 1,1-1,1-2 Transmitting device (communication device) 2, 2-1, 2-2 Receiving device (communication device) 10 Input section 20 Distribution unit (redundant data string generation unit) 30 Transmitter 40 Receiving section 50 Integration Section (Restoration Section) 60 Output section 101 Camera 103 Camera (supplier device) 102 Video monitor 104 Video monitor (destination device) 201, 202, 203, . . ., 208 Camera 211, 212, 213, 218 Video monitor 221,222,231,232,233,234,235,236,237 Switches 261,262,263 Aggregation Device 1000,1001,1002,1003,1004 Transmission Systems 1901 Central Processing Unit 1902 RAM 1903 Input / Output Ports 1904,1905 Input / Output Devices 1906 Bus

Claims

1. a source device that outputs the same data string from a first output terminal and a second output terminal; a first transmitting device which receives the data sequence output from the first output terminal of the source device, divides the data sequence into a first data sequence through an N-th data sequence (N≧2), generates an (N+1)-th data sequence that is a redundant data sequence based on the first data sequence through the N-th data sequence, and transmits each of the first data sequence through the (N+1)-th data sequence; a second transmission device that receives the data sequence output from the second output terminal of the source device, divides the data sequence into a first data sequence through an N-th data sequence, generates an (N+1)-th data sequence that is a redundant data sequence based on the first data sequence through the N-th data sequence, and transmits each of the first data sequence through the (N+1)-th data sequence; (N+1) i-th aggregation devices that select and transmit either the i-th data sequence (1≦i≦N+1) transmitted by the first transmission device or the i-th data sequence transmitted by the second transmission device; (N+1) i-th switches each receiving an i-th data sequence transmitted by the i-th aggregation device (1≦i≦N+1) and outputting the i-th data sequence from a first output terminal and a second output terminal; a first receiving device that receives the ith data string (1≦i≦N+1) output from a first output terminal of the ith switch, and outputs an output data string that is formed by integrating the first data string to the Nth data string based on the received first data string to the (N+1)th data string; a second receiving device that receives the ith data string (1≦i≦N+1) output from the second output terminal of the ith switch, and outputs an output data string that is formed by integrating the first data string to the Nth data string based on the received first data string to the (N+1)th data string; a destination device that receives the output data sequence output by the first receiving device from a first input terminal and receives the output data sequence output by the second receiving device from a second input terminal; Including, Each of the first transmitting device and the second transmitting device a redundant data sequence generator that generates a redundant data sequence based on all data sequences from a first data sequence to an Nth data sequence (N≧2) as an (N+1)th data sequence; a transmitting unit that transmits each of the first data string to the (N+1) data string; Equipped with the redundant data string enables, when an ith data string (any i; 1≦i≦N) among the first data string to the Nth data string is lost, to restore the ith data string based on the other data strings among the first data string to the Nth data string excluding the ith data string and the redundant data string; Each of the first receiving device and the second receiving device a receiving unit for receiving each of the first data string to the (N+1)th data string (N≧2); (a) when all of the first data string through the Nth data string can be normally received, outputting the first data string through the Nth data string; (b) when an ith data string (any i; 1≦i≦N) among the first to Nth data strings cannot be received, restoring the ith data string based on the other data strings from the first to Nth data string excluding the ith data string and the (N+1)th data string which is a redundant data string, and outputting the first to Nth data strings; A restoration unit; Transmission system.

2. The redundant data string generation unit included in each of the first transmission device and the second transmission device generates the redundant data string by calculating an exclusive OR of each bit or negation of each bit from the first data string to the Nth data string, The restoration unit included in each of the first receiving device and the second receiving device restores the i-th data string by calculating an exclusive OR of each bit or a negation of each bit of the (N-1) data strings excluding the i-th data string among the first data string to the N-th data string and the redundant data string. The transmission system according to claim 1 .

3. The transmission unit included in each of the first transmission device and the second transmission device transmits each of the first data sequence to the (N+1)th data sequence via a separate communication line; The receiving unit included in each of the first receiving device and the second receiving device receives the first data sequence to the (N+1)th data sequence via a separate communication line.

3. A transmission system according to claim 1 or 2.

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