Information Processing Apparatus, Information Processing Method, and Program

Abstract

To provide a mechanism capable of maintaining continuity of packets when a communication method is switched.SOLUTION: An information processing device includes a control unit that controls output timing of a first packet transmitted using a first communication method and received by a first receiving unit, and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. The control unit outputs the first packet or the second packet at timing corresponding to a difference in received time between the first packet and the second packet having the same contents.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an information processing apparatus, an information processing method, and a program.

Background Art

[0002] In recent years, technologies for transmitting information while switching communication methods have been developed. As an example, Patent Document 1 below discloses a mechanism for switching from multicast to unicast according to a predetermined evaluation criterion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technology described in Patent Document 1 above, no consideration has been given to the continuity of packets when switching from multicast to unicast. Therefore, when switching from multicast to unicast, packets may become discontinuous, which may cause various inconveniences. For example, in a video distribution system where it is important to transmit packets continuously without interruption, the video may be interrupted or distorted during the switching.

[0005] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a mechanism capable of maintaining the continuity of packets when switching communication methods.

Means for Solving the Problems

[0006] In order to solve the above problems, according to an aspect of the present invention, there is provided a control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit, wherein the control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times of the first packet and the second packet having the same content. Of the first packet and the second packet having the same content, one is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets. An information processing apparatus is provided. Further, in order to solve the above problems, according to another aspect of the present invention, there is provided a control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. The control unit outputs the first packet or the second packet at a timing according to the difference in reception times of the first packet and the second packet having the same content. One of the first communication method and the second communication method is unicast, and the other is multicast. An information processing apparatus is provided.

[0007] When starting continuous transmission and reception of packets, the control unit may measure the difference in reception times of the first packet and the second packet having the same content received at that time, and output the first packet or the second packet at a timing corresponding to the measured difference in reception times.

[0008] When starting continuous transmission and reception of packets, the control unit may delay and output the packet received earlier among the first packet and the second packet having the same content received at that time by a delay time corresponding to the difference in reception times.

[0009] The delay time may be the same as the difference in reception times.

[0010] The delay time may be a value obtained by adding a margin value to the difference in reception times.

[0011] The margin value may be set based on the characteristics of the network that transmits the first packet and the second packet.

[0012] When the first packet and the second packet having the same content are received, the control unit may output the packet received earlier among the first packet and the second packet having the same content, and discard the packet received later.

[0015] The control unit may determine whether the first packet and the second packet have the same content based on the packet numbers assigned to the packets.

[0017] Also, in order to solve the above problems, according to another aspect of the present invention, controlling the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit, including outputting the first packet or the second packet at a timing according to the difference in reception times of the first packet and the second packet having the same content. Of the first packet and the second packet having the same content, one is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets. An information processing method executed by a processor is provided. Further, in order to solve the above problems, according to another aspect of the present invention, there is provided an information processing method executed by a processor, including controlling the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. Controlling the output timing includes outputting the first packet or the second packet at a timing according to the difference in reception times of the first packet and the second packet having the same content. One of the first communication method and the second communication method is unicast, and the other is multicast.

[0019] Also, in order to solve the above problems, according to another aspect of the present invention, causing a computer to function as a control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit, and the control unit outputs the first packet or the second packet at a timing according to the difference in reception times of the first packet and the second packet having the same content. Of the first packet and the second packet having the same content, one is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets. A program is provided. Also, in order to solve the above problems, according to another aspect of the present invention, a computer is caused to function as a control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. The control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times of the first packet and the second packet having the same content. One of the first communication method and the second communication method is unicast, and the other is multicast. A program is provided.

Advantages of the Invention

[0021] As described above, according to the present invention, a mechanism capable of maintaining the continuity of packets when switching communication methods is provided.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0024] <1. First Embodiment> <1.1. Configuration Example> FIG. 1 is a block diagram showing an example of the logical configuration of a system 1 according to a first embodiment. As shown in FIG. 1, the system 1 includes a transmission device 10 and a reception device 20. The transmission device 10 and the reception device 20 are communicably connected by a network 30. The network 30 may be any wired or wireless network capable of transmitting data, such as a communication network managed by a telecommunications carrier including a mobile telecommunications carrier, or a home network managed by an individual. Although one reception device 20 is shown in FIG. 1, the system 1 may include a plurality of reception devices 20.

[0025] The system 1 is a system for transmitting data. The system 1 decomposes data into a plurality of packets and transmits them. A packet is obtained by adding control information (also referred to as a header), such as a destination, to each decomposed data body (also referred to as a payload).

[0026] The system 1 does not particularly limit communication methods such as the type of data to be transmitted, communication protocols, transmission methods, and distribution methods. As an example, in the system 1, any type of data such as video and audio may be transmitted and received. As another example, in the system 1, any communication protocol such as RTP (Real-time Transport Protocol), UDP (User Datagram Protocol), and IP (Internet Protocol) may be adopted. As another example, in the system 1, any transmission method such as unicast and multicast may be adopted. As another example, in the system 1, any distribution method such as streaming and downloading may be adopted.

[0027] In this specification, it is assumed that the system 1 transmits data that is continuous along the time axis as any one of RTP packets, UDP packets, and IP packets. Note that these communication protocols are merely examples, and packets conforming to any other arbitrary communication protocol may be transmitted and received.

[0028] In system 1, the packets transmitted and received only need to be those that can correctly recognize the order of the packets on the receiving side, that is, those that can reproduce the order of the packets on the transmitting side. For example, the packets may be assigned a serial number (hereinafter also referred to as a packet number) indicating the order of the packets. The size of the packet may be fixed-length or variable-length.

[0029] Hereinafter, the configurations of RTP packets, UDP packets, and IP packets transmitted and received in system 1 will be described with reference to FIG. 2.

[0030] FIG. 2 is a diagram showing an example of the configuration of packets transmitted and received in system 1 according to the present embodiment. As shown in FIG. 2, an RTP packet has an RTP header and a disassembled data body included in the RTP payload. As shown in FIG. 2, a UDP packet has a UDP header and an RTP packet included in the UDP payload. Also, an IP packet has an IP header and a UDP packet included in the IP payload. That is, an IP packet is obtained by adding an IP header to a UDP packet, and a UDP packet is obtained by adding a UDP header to an RTP packet. Control information such as a packet number and information indicating the transmission time of the packet (hereinafter also referred to as a "timestamp") is stored in these packets. The control information is typically stored in at least one of the RTP header, UDP header, or IP header. Note that the packet configurations described here are merely examples, and the packet configurations are not limited to those described here.

[0031] System 1 shall transmit and receive the packets described above either by multicast or unicast. Multicast is a transmission method in which the same data (packets) are simultaneously transmitted to a specific plurality of recipients on the network. On the other hand, unicast is a transmission method in which data is transmitted to a specific single recipient. For example, if the transmission destination of the data is one receiving device 20, the transmission device 10 selects unicast, and if the transmission destination of the data is a plurality of receiving devices 20, the transmission device 10 selects multicast.

[0032] Hereinafter, a configuration example of the transmission device 10 and the receiving device 20 will be described.

[0033] (1) Transmission device 10 The transmission device 10 is a device that transmits packets to the receiving device 20. The transmission device 10 may generate and transmit packets by itself, or may receive packets generated by other devices and relay (i.e., transfer) them. In the former case, the transmission device 10 is, for example, a content distribution server such as a video or an encoder. In the latter case, the transmission device 10 is, for example, a relay server, a router, or a wireless communication access point. In this specification, it is assumed that the transmission device 10 generates and transmits packets by itself.

[0034] As shown in FIG. 1, the transmission device 10 includes a packet generation unit 11, a packet duplication unit 12, a packet transmission adjustment unit 13, a packet transmission control unit 14, a unicast packet transmission unit 15, and a multicast packet transmission unit 16. Hereinafter, the configuration of each component will be described.

[0035] The packet generation unit 11 has a function of generating packets. The packet generation unit 11 decomposes the information input from the upper layer such as the previous device or application and generates packets. The packet generation unit 11 assigns a packet number to the generated packets. The packet numbers may be assigned, for example, in ascending order. The packet generation unit 11 outputs the generated packets to the packet duplication unit 12.

[0036] The packet duplication unit 12 has a function of duplicating the packets generated by the packet generation unit 11. The packet duplication unit 12 duplicates the entire packet including the packet header. The same packet number is assigned to the duplicated packets. The packet duplication unit 12 switches whether to duplicate a packet based on the control by the packet transmission control unit 14. When duplicating a packet, the packet duplication unit 12 outputs the duplicated packet to each of the unicast packet transmission unit 15 and the multicast packet transmission unit 16. When not duplicating a packet, the packet duplication unit 12 outputs the packet to one of the unicast packet transmission unit 15 or the multicast packet transmission unit 16 designated by the packet transmission control unit 14.

[0037] The packet transmission adjustment unit 13 has a function of performing various adjustments related to the transmission and reception of packets with the receiving device 20. For example, the packet transmission adjustment unit 13 shares various control information with the receiving device 20. The control information includes, as an example, whether to transmit and receive packets by unicast or multicast, as well as the address and port number of the transmission destination, etc. Then, the packet transmission adjustment unit 13 outputs the shared control information to the packet transmission control unit 14.

[0038] The packet transmission control unit 14 controls the overall packet transmission process by the transmission device 10 based on the adjustment result by the packet transmission adjustment unit 13. Specifically, the packet transmission control unit 14 controls whether to duplicate a packet by the packet duplication unit 12, as well as the packet transmission by the unicast packet transmission unit 15 and the multicast packet transmission unit 16. For example, the packet transmission control unit 14 outputs information indicating whether to duplicate a packet and information indicating the output destination of the packet to the packet duplication unit 12. Also, the packet transmission control unit 14 outputs information indicating the address and port number of the packet transmission destination to at least one of the unicast packet transmission unit 15 and the multicast packet transmission unit 16.

[0039] The unicast packet transmission unit 15 has a function of unicast transmitting packets. Based on the control by the packet transmission control unit 14, the unicast packet transmission unit 15 writes the address and port number into the packet header and then transmits the packet.

[0040] The multicast packet transmission unit 16 has a function of multicast transmitting packets. Based on the control by the packet transmission control unit 14, the multicast packet transmission unit 16 writes the address and port number into the packet header and then transmits the packet.

[0041] (2) Receiver 20 The receiver 20 is a device that receives packets from the transmitter 10. The receiver 20 may process the data contained in the packet (e.g., play a video) by itself, or relay (i.e., transfer) the received packet to another device. In the former case, the receiver 20 is, for example, a set-top box (STB), or a television receiver, etc. In the latter case, the receiver 20 is, for example, a relay server, a router, or a wireless communication access point, etc. In this specification, it is assumed that the receiver 20 processes the data contained in the packet by itself.

[0042] As shown in FIG. 1, the receiver 20 includes a packet shaping unit 22, a packet reception adjustment unit 23, a packet reception control unit 24, a unicast packet reception unit 25, and a multicast packet reception unit 26. Hereinafter, the configurations of the respective components will be described.

[0043] The packet reception adjustment unit 23 has a function of performing various adjustments related to the transmission and reception of packets with the transmitter 10. For example, the packet reception adjustment unit 23 shares various control information with the transmitter 10. Then, the packet reception adjustment unit 23 outputs the shared control information to the packet reception control unit 24.

[0044] Based on the adjustment result by the packet reception adjustment unit 23, the packet reception control unit 24 controls the overall packet reception process by the receiving device 20. Specifically, the packet reception control unit 24 controls the reception of packets by the unicast packet reception unit 25 and the multicast packet reception unit 26. For example, the packet reception control unit 24 outputs information indicating the destination address and port number of the packet to at least one of the unicast packet reception unit 25 and the multicast packet reception unit 26.

[0045] The unicast packet reception unit 25 has a function of receiving packets unicast from the transmitting device 10. The unicast packet reception unit 25 outputs the received packets to the packet shaping unit 22.

[0046] The multicast packet reception unit 26 has a function of receiving packets multicast from the transmitting device 10. The multicast packet reception unit 26 outputs the received packets to the packet shaping unit 22.

[0047] The packet shaping unit 22 has a function of controlling the packets output from the unicast packet reception unit 25 and the multicast packet reception unit 26, and has a function of controlling the timing at which the packets are output from the packet shaping unit 22. Specifically, the packet shaping unit 22 shapes and outputs the packets received by the unicast packet reception unit 25 and the multicast packet reception unit 26. For example, the packet shaping unit 22 discards duplicate packets among the packets received by the unicast packet reception unit 25 and the multicast packet reception unit 26, and rearranges and outputs the packets in order based on the packet numbers. The packets output from the packet shaping unit 22 are restored to the data before decomposition by the upper layer such as the subsequent device or application, and video playback or the like is performed using the restored data.

[0048] (3) Supplementary Unicast is an example of a first communication method. A packet transmitted by unicast (hereinafter also referred to as a unicast packet) is an example of a first packet. The unicast packet transmission unit 15 is an example of a first transmission unit that transmits a first packet using the first communication method. On the other hand, the unicast packet reception unit 25 is an example of a first reception unit that receives a first packet transmitted using the first communication method.

[0049] Multicast is an example of a second communication method. A packet transmitted by multicast (hereinafter also referred to as a multicast packet) is an example of a second packet. The multicast packet transmission unit 16 is an example of a second transmission unit that transmits a second packet using the second communication method. On the other hand, the multicast packet reception unit 26 is an example of a second reception unit that receives a second packet transmitted using the second communication method.

[0050] The packet transmission control unit 14 is an example of a control unit that controls the operations of the first transmission unit and the second transmission unit. On the other hand, the packet shaping unit 22 is an example of a control unit that controls the output timing of the first packet received by the first reception unit and the second packet received by the second reception unit.

[0051] <1.2. Technical Features> When the transmission device 10 receives a data transmission start request for requesting the start of data transmission from the reception device 20, it starts transmitting packets obtained by decomposing the requested data. Here, it is assumed that the data for which the transmission start is requested is video data, and the transmission device 10 starts transmitting packets of the video data. That is, the data transmission start request is a video viewing start request.

[0052] The packet reception adjustment unit 23 transmits a viewing start request to the transmission device 10. When the packet transmission adjustment unit 13 receives the viewing start request, it outputs the received viewing start request to the packet transmission control unit 14. The viewing start request includes, for example, the address of the reception device 20 and information for specifying the video for which viewing is requested.

[0053] When the packet transmission control unit 14 receives a data transmission start request, it selects whether to transmit the packets obtained by decomposing the requested data (i.e., video) by unicast or by multicast. For example, if the number of viewers including the viewer (i.e., the receiving device 20) that has sent a viewing start request is 1, the packet transmission control unit 14 selects unicast. On the other hand, if the number of viewers including the viewer that has sent a viewing start request is plural, the packet transmission control unit 14 selects multicast. Note that selecting multicast includes determining to switch from unicast to multicast when the number of viewers of the video increases from 1 to 2 due to the receiving device 20 newly sending a viewing start request. Also, selecting multicast includes determining to add the receiving device 20 that has sent a viewing start request to the targets of multicast transmission when the video for which a viewing start request has been made is already being transmitted by multicast.

[0054] The packet transmission control unit 14 controls the processes for preparing to start transmitting packets. For example, the packet transmission control unit 14 outputs control information regarding the transmission and reception of packets to the unicast packet transmission unit 15 or the multicast packet transmission unit 16, or notifies the packet reception adjustment unit 23 via the packet transmission adjustment unit 13. The control information regarding the transmission and reception of packets includes, for example, information indicating whether to use unicast or multicast for the transmission and reception of packets, the address and port number of the destination, etc. The packet reception adjustment unit 23 outputs the notified control information to the packet reception control unit 24. The packet reception control unit 24 controls the reception preparation in the unicast packet reception unit 25 or the multicast packet reception unit 26 based on such control information. As a result, the preparation for packet transmission in the transmission device 10 is completed, and the preparation for packet reception in the receiving device 20 is completed.

[0055] Thereafter, the packet transmission control unit 14 starts continuous transmission of packets by one of the selected unicast or multicast transmission methods. For example, the packet transmission control unit 14 continues to transmit packets to the receiving device 20 until a data transmission stop request (i.e., a viewing stop request for requesting to stop viewing a video) that requests to stop data transmission is received from the receiving device 20. However, depending on the increase or decrease of viewers, the packet transmission method may be switched from unicast to multicast, or from multicast to unicast.

[0056] When starting continuous transmission of packets to the receiving device 20, the packet transmission control unit 14 controls the unicast packet transmission unit 15 and the multicast packet transmission unit 16 to transmit packets of the same content as unicast packets and multicast packets. More specifically, the packet transmission control unit 14 starts continuous transmission of packets by one of the selected unicast or multicast transmission methods, and temporarily transmits the replicated packets by the other transmission method. That is, one of the unicast packet and the multicast packet of the same content transmitted when starting continuous transmission of packets to the receiving device 20 is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission of packets. Temporarily transmitting a packet means transmitting one or more predetermined number of packets. Note that the unicast packet and the multicast packet of the same content are typically transmitted simultaneously, but the transmission timings may be different, such as being transmitted continuously on the time axis. By temporarily transmitting packets of the same content, as will be described later, it becomes possible to measure the difference in transmission time between the unicast packet and the multicast packet on the receiving device 20 side.

[0057] Note that the packet transmission control unit 14 may output control information regarding temporary packet transmission and reception to the unicast packet transmission unit 15 or the multicast packet transmission unit 16, or may notify the packet reception adjustment unit 23 via the packet transmission adjustment unit 13. The control information regarding temporary packet transmission and reception includes, for example, the number and transmission time of packets to be temporarily transmitted (i.e., timeout time), as well as the address and port number of the transmission destination. The packet reception adjustment unit 23 outputs the notified control information to the packet reception control unit 24. The packet reception control unit 24 controls the reception preparation in the unicast packet reception unit 25 or the multicast packet reception unit 26 based on such control information. As a result, the temporary packet transmission preparation in the transmission device 10 is completed, and the temporary packet reception preparation in the reception device 20 is completed.

[0058] Hereinafter, an example regarding temporary packet transmission and reception will be described.

[0059] As a first example, a case where unicast is selected as the transmission method of the video for which the viewing start is requested is considered. In that case, the packet transmission control unit 14 controls the unicast packet transmission unit 15 to start unicast transmission. At the same time, the packet transmission control unit 14 instructs the packet replication unit 12 to replicate one or more predetermined packets, and controls the multicast packet transmission unit 16 to multicast the replicated packets.

[0060] As a second example, a case where multicast is selected as the transmission method of the video for which the viewing start is requested and the video has not been multicast transmitted until then is considered. In that case, the packet transmission control unit 14 controls the multicast packet transmission unit 16 to start multicast transmission. At the same time, the packet transmission control unit 14 instructs the packet replication unit 12 to replicate one or more predetermined packets, and controls the unicast packet transmission unit 15 to unicast the replicated packets.

[0061] As a third example, consider a case where multicast is selected as the method for transmitting a video for which a viewing start has been requested, and the video has already been multicast transmitted up to that point. In that case, the packet transmission control unit 14 controls the multicast packet transmission unit 16 to continue the multicast transmission. At the same time, the packet transmission control unit 14 instructs the packet duplication unit 12 to duplicate one or more predetermined packets, and controls the unicast packet transmission unit 15 to unicast transmit the duplicated packets.

[0062] By the processing described above, the duplicated packets, that is, the unicast packets and multicast packets with the same content including the packet numbers, are transmitted to the receiving device 20. However, if the transmission paths are different between the unicast packets and the multicast packets, and if the timing of the packet relay processing is different due to priority control, a difference in transmission time may occur. Therefore, as described below, the receiving device 20 measures such a difference in transmission time and performs processing based on the measured difference in transmission time.

[0063] First, the packet shaping unit 22 buffers the received packets. Then, the packet shaping unit 22 identifies the duplicated unicast packets and multicast packets with the same content from among the plurality of buffered packets. At that time, the packet shaping unit 22 determines whether the unicast packet and the multicast packet have the same content based on the packet numbers assigned to the packets. For example, the packet shaping unit 22 determines that a unicast packet and a multicast packet to which the same packet number is assigned have the same content. On the other hand, the packet shaping unit 22 determines that a unicast packet and a multicast packet to which different packet numbers are assigned do not have the same content. With such a configuration, the packet shaping unit 22 can easily identify the duplicated packets.

[0064] The packet shaping unit 22 measures the difference in reception times between a unicast packet and a multicast packet having the same content. When a plurality of combinations of a unicast packet and a multicast packet having the same content are received, as the difference in reception times, for example, the maximum value in each combination may be measured. Here, the difference in reception times between a unicast packet and a multicast packet having the same content corresponds to the difference in transmission times between the unicast packet and the multicast packet.

[0065] Then, the packet shaping unit 22 outputs a unicast packet or a multicast packet at a timing according to the measured difference in reception times. Specifically, the packet shaping unit 22 outputs a unicast packet or a multicast packet at a timing adjusted to the packet with the later reception time (that is, the packet with the longer transmission time) among the unicast packet and the multicast packet. According to such a configuration, it becomes possible to absorb in advance the difference in transmission times between the unicast packet and the multicast packet at the start of viewing. Therefore, even when the packet transmission method is switched between unicast / multicast thereafter, it becomes possible to maintain the continuity of the packets before and after the switching. Note that maintaining the continuity of the packets means preventing the packets from being interrupted and lost. This makes it possible to prevent the occurrence of breaks and disturbances in the video so that the unicast / multicast switching does not affect the video playback.

[0066] Here, unicast packets and multicast packets with the same content are received when the continuous transmission and reception of packets are started. Therefore, the packet shaping unit 22 measures the difference in reception times between the unicast packet and the multicast packet with the same content received when the continuous transmission and reception of packets are started. Then, the packet shaping unit 22 outputs the unicast packet or the multicast packet at a timing corresponding to the measured reception time difference. More simply, the packet shaping unit 22 controls the output timing of the packets continuously received thereafter based on the reception time difference measured when the continuous transmission and reception of packets are started. According to such a configuration, after controlling the output timing based on the reception time difference measured once when the continuous transmission and reception of packets are started, it is not necessary to measure the reception time difference again. Therefore, the processing load can be reduced.

[0067] The packet shaping unit 22 arranges and outputs the received unicast packets or multicast packets in order along the packet numbers. However, when the unicast packet and the multicast packet with the same content are received, the packet shaping unit 22 outputs the packet received earlier among the unicast packet and the multicast packet with the same content and discards the packet received later. According to such a configuration, even when the unicast packet and the multicast packet with the same content are temporarily received, it is possible to output the packets in order along the packet numbers without duplication. Note that the packet transmission control unit 14 may switch between unicast and multicast during the continuous transmission and reception of packets. At the time of such a switch, the packet transmission control unit 14 may control to transmit the packets with the same content as unicast packets and multicast packets. This is to prevent the packets from becoming discontinuous. Even in this case, the packet shaping unit 22 can output the packets without duplication before and after the switch by outputting the packet received earlier and discarding the packet received later.

[0068] When starting continuous packet transmission and reception, the packet shaping unit 22 delays and outputs, by a delay time corresponding to the difference in reception times, the packet that was received earlier among the unicast packets or multicast packets with the same content. The difference in reception times corresponds to the difference in transmission times. In the present embodiment, the delay time is the same as the difference in reception times. That is, the packet shaping unit 22 delays and outputs, by a delay time equal to the difference in reception times, the packet that was received earlier among the unicast packets or multicast packets with the same content received at the start of continuous packet transmission and reception. Thereafter, the packet shaping unit 22 outputs the packets in order along the packet numbers while eliminating duplicates from the received packets. Since the packets are delayed and output at the start of packet reception, subsequent packets will also be delayed and output.

[0069] In this way, the packet shaping unit 22 delays in advance the output timing of the received packets to match the longer transmission time of either unicast or multicast, and then starts outputting the packets. Thereby, the difference in transmission times between unicast packets and multicast packets can be absorbed in advance at the start of continuous packet transmission and reception. Therefore, even when switching between unicast and multicast during continuous packet transmission and reception, it is possible to maintain the continuity of the packets.

[0070] <1.3. Specific Example> Hereinafter, a specific example regarding the control of the output timing of packets will be described with reference to FIGS. 3 to 6.

[0071] - First Specific Example This specific example is an example in which multicast is selected as the method for continuous packet transmission in response to a data transmission start request, and the transmission time of multicast packets is shorter than that of unicast packets.

[0072] FIG. 3 is a diagram for explaining a first specific example of control of packet output timing by the packet shaping unit 22 according to the present embodiment. The rectangles with numbers in this figure represent packets. The numbers inside the rectangles are packet numbers. The difference in hatching attached to the rectangles means the difference between unicast packets / multicast packets.

[0073] As shown in FIG. 3, the multicast packet receiving unit 26 has a multicast packet buffer 261 which is a buffer for buffering received multicast packets. Then, the multicast packet receiving unit 26 outputs the multicast packets buffered in the multicast packet buffer 261 to the packet shaping unit 22 in the order of reception.

[0074] As shown in FIG. 3, the unicast packet receiving unit 25 has a unicast buffer 251 which is a buffer for buffering received unicast packets. Then, the unicast packet receiving unit 25 outputs the unicast packets buffered in the unicast buffer 251 to the packet shaping unit 22 in the order of reception.

[0075] As shown in FIG. 3, the packet shaping unit 22 has an input buffer 221 and an output buffer 222. The input buffer 221 is a buffer for buffering the packets input from the unicast packet receiving unit 25 and the multicast packet receiving unit 26. The output buffer 222 is a buffer for buffering and outputting the packets to be output among the packets buffered in the input buffer 221 in order.

[0076] In each buffer shown in FIG. 3, it is assumed that packets are input from the left and output from the right. Also, the horizontal axis direction of the buffer means the input / output timing. That is, the packets described on the right side of the buffer are the packets input / output earlier, and the packets described on the left side of the buffer are the packets input / output later.

[0077] In this specific example, packets with packet numbers 1 to 4 are duplicated. The unicast packet receiver 25 has received packets with packet numbers 1 to 4. Then, the unicast packet receiver 25 has already output the packets with packet numbers 1 to 2 to the packet shaping unit 22, and buffered the packets with packet numbers 3 to 4 in the unicast buffer 251. The multicast packet receiver 26 has received packets with packet numbers 1 to 8. Then, the multicast packet receiver 26 has already output the packets with packet numbers 1 to 5 to the packet shaping unit 22, and buffered the packets with packet numbers 6 to 8 in the multicast packet buffer 261.

[0078] As shown in FIG. 3, when comparing the unicast packet and the multicast packet with packet number 1, the multicast packet is received earlier, and the difference in reception time is T D That is. Therefore, the packet shaping unit 22 delays the multicast packet with packet number 1 by the difference in reception time T D and adds it to the output buffer 222. After that, while discarding the unicast packet received later among the packets with duplicate packet numbers, the packet shaping unit 22 arranges the packets with packet numbers 2 and later in order and adds them to the output buffer 222. The packets stored in the output buffer 222 are output sequentially. Here, in the example shown in FIG. 3, the packets output from the input buffer 221 to the output buffer 222 are the multicast packets received earlier (packet numbers 1 to 5), but even if the multicast packets received earlier are discarded and the unicast packets received later are output without delay, the same packets can be added to the output buffer 222.

[0079] In this way, the packet shaping unit 22 delays in advance the output timing of the multicast packet with packet number 1 to match the reception time of the unicast packet with packet number 1, and then starts continuous output of the packets. Therefore, even when unicast and multicast are switched in the future, it is possible to maintain the continuity of the packets.

[0080] - Second specific example This specific example is an example in which multicast is selected as a method for continuously transmitting packets in response to a data transmission start request, and is an example in the case where the transmission time of unicast packets is shorter than that of multicast packets.

[0081] FIG. 4 is a diagram for explaining a second specific example regarding the control of the output timing of packets by the packet shaping unit 22 according to the present embodiment. The meaning of the rectangles with numbers in this figure, as well as the unicast buffer 251, the multicast packet buffer 261, the input buffer 221, and the output buffer 222, are as described above in the first specific example.

[0082] In this specific example, packets with packet numbers 1 to 4 are duplicated. The unicast packet receiver 25 has received packets with packet numbers 1 to 4. Then, the unicast packet receiver 25 has output the packets with packet numbers 1 to 4 to the packet shaping unit 22, and the unicast buffer 251 is empty. The multicast packet receiver 26 has received packets with packet numbers 1 to 8. Then, the multicast packet receiver 26 has output the packets with packet numbers 1 to 5 to the packet shaping unit 22, and has buffered the packets with packet numbers 6 to 8 in the multicast packet buffer 261.

[0083] As shown in FIG. 4, when comparing the unicast packet and the multicast packet with packet number 1, the unicast packet is received earlier, and the difference in reception time is T Dis. Therefore, the packet shaping unit 22 delays a unicast packet with a packet number of 1 by the difference T in reception time D and adds it to the output buffer 222. After that, the packet shaping unit 22 discards the multicast packets received late among the packets with duplicate packet numbers, and adds the packets with packet numbers 2 and later to the output buffer 222 while arranging them in order. The packets stored in the output buffer 222 are sequentially output. Here, in the example shown in FIG. 4, the packets output from the input buffer 221 to the output buffer 222 are the unicast packets received early (packet numbers 1 to 4) and the multicast packet (packet number 5). However, even if the unicast packets received early (packet numbers 1 to 4) are discarded and the multicast packets received late (packet numbers 1 to 4) are output without delay, the same packets can be added to the output buffer 222.

[0084] In this way, the packet shaping unit 22 delays the output timing of the unicast packet with a packet number of 1 in advance according to the reception time of the multicast packet with a packet number of 1, and then starts continuous output of the packets. Therefore, even when unicast and multicast are switched in the future, it is possible to maintain the continuity of the packets. Actually, as shown in FIG. 4, the multicast packet with a packet number of 5 is output after the unicast packet with a packet number of 4 while maintaining continuity. Even when switched from multicast to unicast in the future, unicast packets will be output while maintaining continuity after the multicast packet.

[0085] -The third specific example This specific example is an example in which unicast is selected as a method for continuously transmitting packets in response to a data transmission start request, and is an example in which the transmission time of unicast packets is shorter than that of multicast packets.

[0086] FIG. 5 is a diagram for explaining a third specific example of the control of the output timing of packets by the packet shaping unit 22 according to the present embodiment. The meaning of the rectangles with numbers in this figure, as well as the unicast buffer 251, the multicast packet buffer 261, the input buffer 221, and the output buffer 222, are as described above in the first specific example.

[0087] In this specific example, packets with packet numbers 1 to 4 are duplicated. The unicast packet receiver 25 has received packets with packet numbers 1 to 8. Then, the unicast packet receiver 25 has already output packets with packet numbers 1 to 5 to the packet shaping unit 22, and has buffered packets with packet numbers 6 to 8 in the unicast buffer 251. The multicast packet receiver 26 has received packets with packet numbers 1 to 4. Then, the multicast packet receiver 26 has already output packets with packet numbers 1 to 2 to the packet shaping unit 22, and has buffered packets with packet numbers 3 to 4 in the multicast packet buffer 261.

[0088] As shown in FIG. 5, when comparing the unicast packet and the multicast packet with packet number 1, the unicast packet is received earlier, and the difference in reception time is T D which is. Therefore, the packet shaping unit 22 delays the unicast packet with packet number 1 by the difference in reception time T DDelay it only and add it to the output buffer 222. Then, the packet shaping unit 22 discards the multicast packets received late among the packets with duplicate packet numbers, and while arranging the packets with packet numbers 2 and later in order, adds them to the output buffer 222. The packets stored in the output buffer 222 are output sequentially. Here, in the example shown in FIG. 5, the packets output from the input buffer 221 to the output buffer 222 are unicast packets received early (packet numbers are 1 to 5), but even if the unicast packets received early are discarded and the multicast packets received late are output without delay, the same packets can be added to the output buffer 222.

[0089] In this way, the packet shaping unit 22 delays in advance the output timing of the unicast packet with packet number 1 to match the reception time of the multicast packet with packet number 1, and then starts continuous output of the packets. Therefore, even when unicast and multicast are switched in the future, it is possible to maintain the continuity of the packets.

[0090] - The fourth specific example This specific example is an example in which unicast is selected as a method for continuously transmitting packets in response to a data transmission start request, and is an example in which the transmission time of multicast packets is shorter than that of unicast packets.

[0091] FIG. 6 is a diagram for explaining a fourth specific example regarding the control of the output timing of packets by the packet shaping unit 22 according to the present embodiment. The meaning of the rectangles with numbers in this figure, and the unicast buffer 251, multicast packet buffer 261, input buffer 221, and output buffer 222 are as described above in the first specific example.

[0092] In this specific example, packets with packet numbers 1 to 4 are replicated. The unicast packet receiver 25 has received packets with packet numbers 1 to 8. Then, the unicast packet receiver 25 has already output packets with packet numbers 1 to 5 to the packet shaping unit 22, and buffered packets with packet numbers 6 to 8 in the unicast buffer 251. The multicast packet receiver 26 has received packets with packet numbers 1 to 4. Then, the multicast packet receiver 26 has already output packets with packet numbers 1 to 4 to the packet shaping unit 22, and the multicast packet buffer 261 is empty.

[0093] As shown in FIG. 6, when comparing the unicast packet and the multicast packet with packet number 1, the multicast packet is received earlier, and the difference in reception times is T D Therefore, the packet shaping unit 22 delays the multicast packet with packet number 1 by the difference in reception times T D and adds it to the output buffer 222. After that, while discarding the unicast packet received later among the packets with duplicate packet numbers, the packet shaping unit 22 arranges the packets with packet numbers 2 and later in order and adds them to the output buffer 222. The packets stored in the output buffer 222 are output sequentially. Here, as shown in FIG. 6, the packets output from the input buffer 221 to the output buffer 222 are the multicast packets (packet numbers 1 to 4) and the unicast packet (packet number 5) received earlier. However, even if the multicast packets (packet numbers 1 to 4) received earlier are discarded and the unicast packets (packet numbers 1 to 4) received later are output without delay, the same packets can be added to the output buffer 222.

[0094] In this way, the packet shaping unit 22 delays in advance the output timing of the multicast packet with packet number 1 to match the reception time of the unicast packet with packet number 1, and then starts continuous output of the packets. Therefore, even if unicast and multicast are switched in the future, it is possible to maintain the continuity of the packets. Actually, as shown in FIG. 6, the unicast packet with packet number 5 is output after the multicast packet with packet number 4 while maintaining continuity. Even if it is switched from unicast to multicast in the future, the multicast packet will be output after the unicast packet while maintaining continuity.

[0095] <1.4. Flow of processing> - Flow of processing in the entire system FIG. 7 is a sequence diagram showing an example of the flow of processing executed in the system 1 according to the present embodiment. This sequence involves the transmission device 10 and the reception device 20.

[0096] As shown in FIG. 7, first, the reception device 20 transmits a viewing start request to the transmission device 10 (step S102). The viewing start request includes, for example, the address of the reception device 20 and information for specifying the video for which viewing is requested.

[0097] When the transmission device 10 receives the viewing start request, it selects either unicast or multicast as the method for continuously transmitting packets to the reception device 20 (step S104). For example, if the transmission device 10 has not yet transmitted the video that is the target of the viewing start request, it selects unicast. If the number of viewers including the received viewing start request is equal to or greater than a preset threshold, or if it is determined that multicast transmission is better, such as when there is a margin in the network bandwidth for multicast transmission, it selects multicast.

[0098] Next, the transmission device 10 transmits control information regarding packet transmission and reception to the reception device 20 (step S106). At this time, the transmission device 10 may also transmit control information regarding temporary packet transmission and reception to the reception device 20.

[0099] Next, the transmission device 10 duplicates one or more predetermined packets and transmits them as unicast packets and multicast packets with the same content (step S108). The reception device 20 buffers the received packets. Specifically, the unicast buffer 251 buffers the received unicast packets and sequentially outputs them to the packet shaping unit 22. On the other hand, the multicast packet buffer 261 buffers the received multicast packets and sequentially outputs them to the packet shaping unit 22. The packet shaping unit 22 buffers the packets input from the unicast packet reception unit 25 and the multicast packet reception unit 26 in the input buffer 221.

[0100] When the reception device 20 receives unicast packets and multicast packets with the same content, it determines the delay time based on the difference in reception times of the unicast packets and multicast packets with the same content (step S110). Specifically, the packet shaping unit 22 identifies the unicast packet and the multicast packet to which the same packet number is assigned from the packets buffered in the input buffer 221. Then, the packet shaping unit 22 determines the difference in reception times between the unicast packet and the multicast packet to which the same packet number is assigned as the delay time. Note that the packet shaping unit 22 may determine the delay time after receiving all of the one or more predetermined duplicated unicast packets and multicast packets, or may determine the delay time at an intermediate stage.

[0101] Next, the receiving device 20 starts outputting the packet based on the determined delay time (step S112). Specifically, the packet shaping unit 22 delays the first packet buffered in the input buffer 221 by the delay time determined in step S110 and adds it to the output buffer 222. Then, the packet shaping unit 22 discards the packet received later among the packets with duplicate packet numbers from the packets buffered in the input buffer 221, and adds them to the output buffer 222 in order along the packet numbers. The packets buffered in the output buffer 222 are output sequentially.

[0102] When the transmission of the replication and transmission of one or more predetermined packets by the transmitting device 10 is completed, the transmitting device 10 continuously transmits the packet by the transmission method selected in step S104 (step S114). That is, the transmitting device 10 continuously transmits either a unicast packet or a multicast packet to the receiving device 20. The receiving device 20 buffers the received packet.

[0103] When the receiving device 20 receives a packet, it sequentially outputs the received packet (step S116). Specifically, the packet shaping unit 22 adds the packets buffered in the input buffer 221 to the output buffer 222 in order along the packet numbers. The packets buffered in the output buffer 222 are output sequentially.

[0104] <1.5. Effect> As described above, according to the first embodiment, even in a network environment where there is a difference in transmission time between unicast and multicast, it is possible to prevent packet interruption and loss when switching between unicast and multicast. Therefore, the packets received by the receiving device 20 can be processed while maintaining continuity, so that it is possible not to affect the reproduction of the video.

[0105] <2. Second Embodiment> The configuration example of this embodiment is the same as that of the first embodiment.

[0106] In the first embodiment, an example was described in which the delay time when outputting a packet received earlier among unicast packets or multicast packets having the same content, which was received when starting continuous transmission and reception of packets, was the same as the difference in reception times. In contrast, in the present embodiment, the delay time is different from the difference in reception times.

[0107] Specifically, the delay time in the present embodiment is a value obtained by adding a margin value to the difference in reception times. The transmission time of a packet may vary due to factors such as fluctuations occurring in the network 30. In this regard, according to such a configuration, by providing a margin in the delay time, it is possible to maintain the continuity of packets when switching between unicast and multicast even when the transmission time of a packet varies.

[0108] The margin value may be set based on the characteristics of the network 30. Since the variation range of the packet transmission time varies depending on the situation of the network 30, it is difficult to accurately detect it in advance. In this regard, it is appropriate to set the margin value based on past measured values or empirical knowledge as in such a configuration.

[0109] A specific example of the present embodiment will be described with reference to FIG. 8.

[0110] FIG. 8 is a diagram for explaining a specific example regarding the control of the output timing of packets by the packet shaping unit 22 according to the present embodiment. The meaning of the rectangles with numbers in this figure, as well as the unicast buffer 251, multicast packet buffer 261, input buffer 221, and output buffer 222, are as described above with reference to FIGS. 3 to 6.

[0111] This specific example is an example in which multicast is selected as a method for continuously transmitting packets in response to a data transmission start request, and is an example in which the transmission time of unicast packets is shorter than that of multicast packets.

[0112] In this specific example, packets with packet numbers from 1 to 4 are duplicated. The unicast packet receiver 25 has received packets with packet numbers from 1 to 4. Then, the unicast packet receiver 25 has already output the packets with packet numbers from 1 to 4 to the packet shaping unit 22, and the unicast buffer 251 is empty. The multicast packet receiver 26 has received packets with packet numbers from 1 to 8. Then, the multicast packet receiver 26 has already output the packets with packet numbers from 1 to 5 to the packet shaping unit 22, and buffers the packets with packet numbers from 6 to 8 in the multicast packet buffer 261.

[0113] As shown in FIG. 8, when comparing the unicast packet and the multicast packet with packet number 1, the unicast packet is received earlier, and the difference in reception times is T D which is. Therefore, the packet shaping unit 22 delays the unicast packet with packet number 1 by adding a margin value α to the difference in reception times T D and adds it to the output buffer 222 after delaying it by T D + α. After that, while discarding the multicast packet received later among the packets with duplicate packet numbers, the packet shaping unit 22 arranges the packets with packet numbers 2 and later in order and adds them to the output buffer 222. Note that the multicast packets with packet numbers 5 and later are added to the output buffer 222 after being delayed by up to the margin value α according to the fluctuation of the network 30. The packets stored in the output buffer 222 are output sequentially. Here, in the example shown in FIG. 8, the packets output from the input buffer 221 to the output buffer 222 are the unicast packets (packet numbers 1 to 4) and the multicast packet (packet number 5) received earlier. However, even if the unicast packets (packet numbers 1 to 4) received earlier are discarded and the multicast packets (packet numbers 1 to 4) received later are output after being delayed by the margin value α, the same packets can be added to the output buffer 222.

[0114] In this way, the packet shaping unit 22 delays the output timing of the unicast packet with packet number 1 by a margin value α in advance from the reception time of the multicast packet with packet number 1, and then starts continuous output of the packets. Therefore, even when unicast and multicast are switched in the future, and even when fluctuations occur in the network 30, it is possible to maintain the continuity of the packets. Actually, as shown in FIG. 8, the multicast packet with packet number 5 is output after the unicast packet with packet number 4 while maintaining continuity. Even when switched from multicast to unicast in the future, unicast packets will be output while maintaining continuity after the multicast packets.

[0115] The processing executed in the system 1 according to the present embodiment is the same as that described above with reference to FIG. 7. However, in step S110, the packet shaping unit 22 determines, as the delay time, a value obtained by adding a margin value to the difference in reception times between the unicast packet and the multicast packet to which the same packet number is assigned.

[0116] As described above, according to the second embodiment, even when there are fluctuations in the packet transmission time, the fluctuations can be absorbed by setting a delay time that takes into account the fluctuations in advance. Therefore, even when fluctuations actually occur, it is possible to maintain the continuity of the packets and prevent them from affecting video playback.

[0117] <3. Hardware Configuration> Next, with reference to FIG. 9, the hardware configuration of the information processing apparatus according to each of the above embodiments will be described. FIG. 9 is a block diagram showing an example of the hardware configuration of the information processing apparatus according to each of the above embodiments. Note that the information processing apparatus 900 shown in FIG. 9 can realize, for example, the transmission apparatus 10 or the reception apparatus 20 shown in FIG. 1. The information processing by the transmission apparatus 10 or the reception apparatus 20 according to each of the above embodiments is realized by the cooperation of software and the hardware described below.

[0118] As shown in FIG. 9, the information processing apparatus 900 includes a CPU (Central Processing Unit) 901, a ROM (Read Only Memory) 902, a RAM (Random Access Memory) 903, a host bus 904, a bridge 905, an external bus 906, an interface 907, an input device 908, an output device 909, a storage device 910, and a communication device 911.

[0119] The CPU 901 functions as an arithmetic processing unit and a control unit, and controls the overall operation within the information processing apparatus 900 according to various programs. The CPU 901 may be a microprocessor. The ROM 902 stores programs used by the CPU 901, arithmetic parameters, and the like. The RAM 903 temporarily stores programs used in the execution of the CPU 901 and parameters that change as appropriate during the execution. These are interconnected by a host bus 904 composed of a CPU bus or the like. The CPU 901 can form, for example, the packet generation unit 11, the packet duplication unit 12, the packet transmission adjustment unit 13, and 14 shown in FIG. 1. Also, the CPU 901 can form, for example, the packet shaping unit 22, the packet reception adjustment unit 23, and the packet reception control unit 24 shown in FIG. 1.

[0120] The host bus 904 is connected to an external bus 906 such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge 905. Note that it is not always necessary to separately configure the host bus 904, the bridge 905, and the external bus 906, and these functions may be implemented on a single bus.

[0121] The input device 908 includes input means such as a mouse, a keyboard, a touch panel, buttons, a microphone, switches, and levers for a user to input information, and an input control circuit that generates an input signal based on the input by the user and outputs it to the CPU 901. A user who operates the information processing device 900 can input various data to the information processing device 900 and instruct processing operations by operating this input device 908.

[0122] The output device 909 includes, for example, a display device such as a CRT (Cathode Ray Tube) display device, a liquid crystal display (LCD) device, an OLED (Organic Light Emitting Diode) device, a lamp, and an audio output device such as a speaker. The output device 909 can display, for example, a video restored from the packet output from the packet shaping unit 22 shown in FIG. 1.

[0123] The storage device 910 is a device for storing data. The storage device 910 may include a storage medium, a recording device that records data on the storage medium, a reading device that reads data from the storage medium, a deleting device that deletes data recorded on the storage medium, and the like. The storage device 910 is composed of, for example, an HDD (Hard Disk Drive). This storage device 910 drives a hard disk and stores programs executed by the CPU 901 and various data.

[0124] The communication device 911 is, for example, a communication interface composed of a communication device or the like for connecting to a network. Also, the communication device 911 may support either wireless communication or wired communication. The communication device 911 may form, for example, the unicast packet transmission unit 15 and the multicast packet transmission unit 16 shown in FIG. 1. Further, the communication device 911 may form, for example, the unicast packet reception unit 25 and the multicast packet reception unit 26 shown in FIG. 1.

[0125] As described above, an example of the hardware configuration capable of realizing the functions of the information processing apparatus 900 according to the present embodiment has been shown. Each of the above-described components may be realized using general-purpose members, or may be realized by hardware specialized for the functions of each component. Therefore, it is possible to appropriately change the hardware configuration to be used according to the technical level at the time of implementing the present embodiment.

[0126] <4. Supplementary Note> As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and these are naturally understood to belong to the technical scope of the present invention.

[0127] - First Supplementary Note For example, in the above embodiment, an example in which the transmission device 10 starts packet transmission triggered by receiving a data transmission start request from the reception device 20 has been described, but the present invention is not limited to such an example. The transmission device 10 may receive a data transmission start request for requesting the start of data transmission to the reception device 20 from a source other than the reception device 20, or the transmission device 10 may spontaneously start packet transmission.

[0128] - Second Supplementary Note For example, in the above embodiment, an example where the first communication method is unicast and the second communication method is multicast has been described. However, the present invention is not limited to such an example. The first communication method may be multicast and the second communication method may be unicast. Also, as another example, there are the following two examples. In the first example, both the first communication method and the second communication method are unicast. In the second example, both the first communication method and the second communication method may be multicast.

[0129] - Supplementary Note 3 For example, in the above embodiment, an example where the two types of communication methods used for packet transmission differ between unicast / multicast has been described. However, the present invention is not limited to such an example. As an example, the two types of communication methods used for packet transmission may differ in communication protocols such as IP and UDP. As another example, the two types of communication methods used for packet transmission may differ in network protocols such as Wi-Fi and cellular communication networks.

[0130] - Supplementary Note 4 In the first communication method and the second communication method in the above embodiment, as another example, it is a case where the first layer (layer 1 (physical layer)) of the OSI (Open Systems Interconnection) 7-layer model is different, the first communication method may be a wired LAN, and the second communication method may be a wireless LAN.

[0131] Also, the first communication method and the second communication method in the above embodiment may further be combined with the method described in the second supplementary note. An example is as follows. In this example, the first communication method is a wired LAN, the second communication method is a wireless LAN, and further, the first communication method and the second communication method may be unicast and unicast (or, multicast and multicast, unicast and multicast, multicast and unicast).

[0132] Here, different IP addresses are assigned to the wired LAN and the wireless LAN in the above-described embodiment for the receiving device 20. Also, in the above-described embodiment, the transmitting device 10 outputs packets to the wired LAN and the wireless LAN to which different IP addresses are assigned.

[0133] - Fifth Supplementary Note In the first communication method and the second communication method in the above-described embodiment, as another example, it is a case where the third layer (layer 3 (network layer)) of the OSI (Open Systems Interconnection) 7-layer model is different. The first communication method may be IPv6, and the second communication method may be IPv4. Also, the first communication method and the second communication method may be IPv4 and IPv6 (or, IPv6 and IPv6, IPv4 and IPv4).

[0134] Also, the first communication method and the second communication method in the above-described embodiment may further combine the methods described in the second supplementary note. As an example, there are the following four examples.

[0135] The first example is that the first communication method is IPv6, the second communication method is IPv4, and further, the first communication method and the second communication method may be unicast and unicast (or, multicast and multicast, unicast and multicast, multicast and unicast).

[0136] The second example is that the first communication method is IPv4, the second communication method is IPv6, and further, the first communication method and the second communication method may be unicast and unicast (or, multicast and multicast, unicast and multicast, multicast and unicast).

[0137] The third example is that the first communication method is IPv6, the second communication method is IPv6, and further, the first communication method and the second communication method may be unicast and unicast (or, multicast and multicast, unicast and multicast, multicast and unicast).

[0138] In the fourth example, the first communication method is IPv4, the second communication method is IPv4, and further, the first communication method and the second communication method may be unicast to unicast (or multicast to multicast, unicast to multicast, multicast to unicast).

[0139] - Supplementary Note 6 Note that the series of processes performed by each device described in this specification may be realized using any of software, hardware, and a combination of software and hardware. The program constituting the software is pre-stored, for example, in a recording medium (specifically, a non-transitory computer-readable storage medium) provided inside or outside each device. Then, each program is read into the RAM when executed by a computer that controls each device described in this specification, and is executed by a processor such as a CPU. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, etc. Also, the above computer program may be distributed via a network, for example, without using a recording medium.

[0140] - Supplementary Note 7 Also, the processes described using flowcharts and sequence diagrams in this specification do not necessarily have to be executed in the order shown in the figures. Some processing steps may be executed in parallel. Also, additional processing steps may be adopted, and some processing steps may be omitted.

Explanation of Reference Numerals

[0141] 1 System 10 Transmitting Device 11 Packet Generation Unit 12 Packet Duplication Unit 13 Packet Transmission Adjustment Unit 14 Packet Transmission Control Unit 15 Unicast Packet Transmission Unit 16 Multicast Packet Transmission Unit 20 Receiving Device 22 Packet Shaping Unit 221 Input Buffer 222 Output Buffer 23 Packet Reception Adjustment Unit 24 Packet Reception Control Unit 25 Unicast Packet Reception Unit 251 Unicast Buffer 26 Multicast Packet Reception Unit 261 Multicast Packet Buffer 30 Network

Claims

1. A control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit, comprising: The control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times between the first packet and the second packet having the same content; One of the first packet and the second packet having the same content is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets, An information processing apparatus.

2. A control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit, comprising: The control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times between the first packet and the second packet having the same content; One of the first communication method and the second communication method is unicast, and the other is multicast, An information processing apparatus.

3. The control unit measures the difference in reception times between the first packet and the second packet having the same content received when starting continuous transmission and reception of packets, and outputs the first packet or the second packet at a timing corresponding to the measured difference in reception times. The information processing apparatus according to claim 1 or 2.

4. The control unit delays and outputs the packet received earlier among the first packet and the second packet having the same content received when starting continuous transmission and reception of packets by a delay time corresponding to the difference in reception times. The information processing apparatus according to claim 3.

5. The delay time is the same as the difference in reception times. The information processing apparatus according to claim 4.

6. The delay time is a value obtained by adding a margin value to the difference in reception times. The information processing apparatus according to claim 4.

7. The margin value is set based on the characteristics of the network that transmits the first packet and the second packet. The information processing apparatus according to claim 6.

8. When the control unit receives the first packet and the second packet having the same content, among the first packet and the second packet having the same content, the packet received earlier is output, and the packet received later is discarded. The information processing apparatus according to any one of claims 1 to 7.

9. The control unit determines whether the first packet and the second packet have the same content based on the packet numbers assigned to the packets. The information processing apparatus according to any one of claims 1 to 8.

10. Controlling the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. including Controlling the output timing includes outputting the first packet or the second packet at a timing corresponding to the difference in reception times of the first packet and the second packet having the same content. One of the first packet and the second packet having the same content is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets. An information processing method executed by a processor.

11. Controlling the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. including Controlling the output timing includes outputting the first packet or the second packet at a timing corresponding to the difference in reception times of the first packet and the second packet having the same content. One of the first communication method and the second communication method is unicast, and the other is multicast. An information processing method executed by a processor.

12. A computer A control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit. function as The control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times of the first packet and the second packet having the same content. One of the first packet and the second packet having the same content is a packet that is continuously transmitted and received, and the other is a packet that is temporarily transmitted and received when starting continuous transmission and reception of packets. Program. [

13. ] A computer, A control unit that controls the output timing of a first packet transmitted using a first communication method and received by a first receiving unit and a second packet transmitted using a second communication method different from the first communication method and received by a second receiving unit; Function as, The control unit outputs the first packet or the second packet at a timing corresponding to the difference in reception times between the first packet and the second packet having the same content. One of the first communication method and the second communication method is unicast, and the other is multicast. Program.

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