JP2005244929A - Transmission apparatus and method, reception apparatus and method, communication system, recording medium, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high-speed and stable communication. <P>SOLUTION: A Multi Flow RTP 83 divides data of one RTP session so as to be transmitted to UDP ports 87-89 and supplies the data to the UDP ports 87-89. An RTCP 64 controls the UDP ports 87-89 to transmit the data and controls a TCP port 86 to transmit control information for reconstructing the divided data. The UDP ports 67-69 receive the divided data and supply them to the Multi Flow RTP 63. The RTCP 64 also acquires control information from the TCP port 66 and supplies the information to the Multi Flow RTP 63. The Multi Flow RTP 63 reconstructs the divided data based on the control information and supplies the data to a player 61, and the player 61 reproduces the reconstructed data. The present invention can be applied to a stream data distribution system. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transmission apparatus and method, a reception apparatus and method, a communication system, a recording medium, and a program, and in particular, a transmission apparatus and method capable of realizing stable communication by suppressing data delay in data communication. , A receiving apparatus and method, a communication system, a recording medium, and a program.

  A technique for distributing data while guaranteeing the reproduction time of large-capacity streaming data or the like is becoming popular.

  In a router on the Internet, a flow of data to be forwarded (transferred) is monitored, and flow control such as lowering the forward priority of a flow in which a large amount of data is transmitted may be performed. In a general router, a data flow is identified by a source and destination IP address, a transport protocol, and a source and destination port number.

  As an example of the above communication, there is an RTP (Real Time Protocol) method. In the case of the RTP method, when streaming data is communicated between a distribution server and a client PC (Personal Computer), streaming control is performed by RTSP (Real Time Streaming Protocol). Further, RTCP (RTP Control Protocol) is used for data transmission control, and moving image transfer is performed by RTP. In the case of a conventional video transfer technology using RTP, video transfer is realized by using one port for one RTP session.

  In addition, it has been proposed to divide a bit stream and transmit / receive it at different ports (see, for example, Patent Document 1).

Furthermore, what implement | achieves the optimal packet communication process according to the capability of a terminal is proposed (for example, refer patent document 2).
JP 2002-017637 A JP 2003-152544 A

  By the way, when performing video transfer by the conventional RTP method, the router on the Internet monitors the flow of data to be forwarded, and communication is performed by flow control such as lowering the forward priority of the flow transmitting a large amount of data. Control is performed so as not to occupy excessive bandwidth.

  Also, for example, the router controls to discard the received packet when the buffer becomes overloaded and the buffer becomes full.

  To cope with this, in TCP (Transmission Control Protocol), when congestion occurs due to the packet being discarded on the router, the speed is temporarily reduced and the window size that is a multiple of the packet length (communication is possible) Search for the optimum communication speed while gradually increasing the amount of data (slow start).

  Here, the congestion will be described. For example, in TCP and the like, when data is lost on the communication path, a retransmission request is transmitted from the transmission destination to the transmission source. However, when data is continuously lost, the retransmission request is also continuously received. As a result, the communication path becomes more crowded and the data loss on the communication path is further deteriorated, and the data cannot be stably transferred. Such a state in which data cannot be transferred stably is called congestion. For example, as shown in FIG. 1, the congestion occurs somewhat after the communication is started. In FIG. 1, the horizontal axis represents time, and the vertical axis represents the amount (byte) of data received at the transmission destination per unit time.

  That is, as shown in FIG. 1, at the beginning of communication, since there is no flow control based on the amount of data transferred, the communication speed is maintained to some extent, but data is discarded by routers existing in various places on the communication path. When a certain amount of time has elapsed since the start of communication, the retransmission request is frequently sent from the transmission destination, so that the data to be retransmitted and the retransmission request further congest the communication path and eventually Results in congestion as indicated by A in FIG.

  For this reason, when congestion occurs in a double or triple manner, it may take a very long time to find the optimum communication speed, resulting in communication with a low transmission speed. For example, if buffering of streaming data is insufficient, playback of streaming data is interrupted, and smooth streaming data may not be played back.

  In order to avoid such a situation, for example, UDP may be used instead of TCP. However, UDP (User Datagram Protocol) does not perform flow control or congestion control like TCP. Therefore, although it is possible to communicate at high speed, there is a problem in that the arrival of data is not guaranteed because it is not confirmed whether the transmission data is reliably transmitted.

  The present invention has been made in view of such a situation, and in particular, by transmitting communication data of one session in the session layer using a plurality of transport layer ports, it is possible to achieve high speed and stability. This makes it possible to realize communication of streaming data.

  The transmission apparatus of the present invention reproduces data including a plurality of first transmission means for transmitting data according to the first protocol of the transport layer, the port number of the first transmission means, and the number of ports used. Generating means for generating control information for the data, a second transmitting means for transmitting the control information generated by the generating means by the second protocol of the transport layer, and a plurality of data to be transmitted by the protocol of the session layer And a control unit that controls to allocate and transmit according to each operation state of one transmission unit.

  The control means may be controlled to allocate and transmit data to be transmitted according to a session layer protocol in a round-robin manner according to the operating states of the plurality of first transmission means. .

  The control unit may be configured to control so that data to be transmitted according to a session layer protocol is allocated and transmitted according to the operating state of each of the plurality of first transmission units. it can.

  A dividing unit that divides the data to be transmitted by the session layer protocol into a plurality of data can be further provided, and the control unit converts the plurality of data divided by the dividing unit into a plurality of first data The transmission means may be controlled to transmit using the first protocol of the transport layer.

  When the data is divided by the dividing unit, the generating unit generates control information including the port number of the first transmitting unit and the number of ports used for combining and reproducing the divided data. Can be.

  The control means may be controlled so that the same data to be transmitted by the session layer protocol is transmitted by the plurality of first transmission means by the first protocol of the transport layer.

  The generating means identifies the data to be transmitted by the protocol of the session layer, including the port number of the first transmitting means and the number of used ports, and generates control information for reproducing the data. be able to.

  The second protocol may be TCP.

  The session layer protocol may be RTP.

  The first protocol of the transport layer may be a protocol that does not confirm the arrival of transmitted data.

  The first protocol in the transport layer that does not check the arrival of the transmitted data may be UDP.

  The first protocol of the transport layer may be TCP.

  The transmission method of the present invention includes a plurality of first transmission steps for transmitting data according to a first protocol of the transport layer, a port number in the processing of the first transmission step, and a number of used ports. Step of generating control information for reproducing the data, a second transmission step of transmitting the control information generated by the processing of the generation step by the second protocol of the transport layer, and a protocol of the session layer And a control step for performing control so that data is allocated and transmitted according to each operation state of the processing of the plurality of first transmission steps.

  The program of the first recording medium of the present invention includes a plurality of first transmission control steps for controlling transmission of data by a first protocol of the transport layer, a port number in the processing of the first transmission step, and A generation control step for controlling the generation of control information for reproducing data, including the number of used ports, and control information generated in the process of the generation control step for transmission in the second protocol of the transport layer A second transmission control step, and an operation control step for controlling the data to be transmitted according to the session layer protocol so that the data is allocated and transmitted in accordance with the operation states of the processes of the plurality of first transmission control steps. It is characterized by including.

  A first program of the present invention includes a plurality of first transmission control steps for controlling transmission of data by a first protocol of a transport layer, a port number in the processing of the first transmission step, and a use port A generation control step for controlling generation of control information for reproducing data, including a number, and a second for controlling transmission of the control information generated by the processing of the generation control step in the second protocol of the transport layer The computer executes the transmission control step and the operation control step for controlling the transmission of the data to be transmitted according to the session layer protocol in accordance with the operation states of the processes of the plurality of first transmission control steps. It is characterized by making it.

  The receiving apparatus of the present invention reproduces data including a plurality of first receiving means for receiving data according to the first protocol of the transport layer, the port number of the first receiving means, and the number of used ports. And a second receiving means for receiving control information for the transport layer second protocol, and a reproducing means for reproducing data based on the control information as received data according to the session layer protocol. To do.

  The data may be a plurality of divided data, the plurality of first receiving means may be caused to receive the divided data, and the reproducing means Data received by the session layer protocol based on the control information including the information for combining and reproducing the divided data in addition to the port number and the number of used ports received by the receiving means of 2 As described above, a plurality of data can be combined and reproduced.

  The data can be a plurality of the same data, the plurality of first receiving means can each receive the same data, and the reproduction means can receive the second data Data received by the protocol of the session layer among the plurality of first receiving means based on the control information including information identifying the data in addition to the port number and the number of used ports received by the receiving means As a result, the data received first can be reproduced.

  The second protocol may be TCP.

  The session layer protocol may be RTP.

  The first protocol of the transport layer may be a protocol that does not confirm the arrival of transmitted data.

  The first protocol in the transport layer that does not check the arrival of the transmitted data may be UDP.

  The first protocol of the transport layer may be TCP.

  The reception method of the present invention includes a plurality of first reception steps for receiving data according to a first protocol in the transport layer, a port number in the processing of the first reception step, and a number of ports used Including a second reception step for receiving control information for reproducing data using the transport layer second protocol, and a reproduction step for reproducing data based on the control information as received data using the session layer protocol. It is characterized by.

  The program of the second recording medium of the present invention includes a plurality of first reception control steps for controlling reception of data by the first protocol of the transport layer, a port number in the processing of the first reception control step, And a second reception control step for controlling reception of control information for reproducing data including the number of used ports in the second protocol of the transport layer, and as data received by the protocol of the session layer, A reproduction control step for controlling reproduction based on the control information.

  A second program of the present invention includes a plurality of first reception control steps for controlling reception of data by a first protocol of the transport layer, a port number in the processing of the first reception control step, and use A second reception control step for controlling the reception of control information for reproducing data, including the number of ports, in the second protocol of the transport layer; A reproduction control step for controlling reproduction based on the computer is executed.

  In the communication system according to the present invention, a transmission apparatus reproduces data including a plurality of transmission units that transmit data using a transport layer protocol, the port number of the first transmission unit, and the number of ports used. Generating means for generating control information; second transmitting means for transmitting control information generated by the generating means using a second protocol of the transport layer; and a plurality of first data to be transmitted using a protocol of the session layer Control means for controlling the transmission means to allocate and transmit according to the respective operating states of the transmission means, and the receiving device receives the data by the transport layer protocol, and the port of the first receiving means 2nd reception which receives the control information for reproducing | regenerating data containing a number and the number of use ports by the 2nd protocol of a transport layer And stage, as the reception data by the session layer protocol, characterized in that it comprises a reproducing means for reproducing data based on the control information.

  In the transmission apparatus and method and the program of the present invention, data is transmitted through a plurality of communication paths by the first protocol of the transport layer, and control for reproducing the data including the port number and the number of used ports is performed. Information is generated, the generated control information is transmitted by the second protocol of the transport layer, and the data to be transmitted by the protocol of the session layer is allocated and transmitted according to the operation states of the plurality of communication paths. To be controlled.

  In the receiving apparatus, method, and program of the present invention, data is received through a plurality of communication paths by the first protocol in the transport layer, and control for reproducing the data including the port number and the number of ports used is performed. Information is received by the second protocol of the transport layer, and the data is reproduced based on the control information as received data by the protocol of the session layer.

  In the communication system of the present invention, data is transmitted by a transmission device using a transport layer protocol through a plurality of communication paths, and control information for reproducing data including a port number and the number of ports used is generated. The generated control information is transmitted by the second protocol of the transport layer, and the data to be transmitted by the protocol of the session layer is controlled so as to be allocated and transmitted according to the respective operation states of the plurality of communication paths. The data is received by the receiving device according to the protocol of the transport layer, and the control information for reproducing the data including the port number and the number of used ports is received by the second protocol of the transport layer, and the session layer The data is reproduced based on the control information as received data according to the protocol.

  The transmission apparatus, the reception apparatus, or the communication system of the present invention may be an independent apparatus or a block that performs transmission processing or reception processing.

  According to the present invention, high-speed and stable communication can be realized.

  Embodiments of the present invention will be described below. The correspondence relationship between the invention described in this specification and the embodiments of the invention is exemplified as follows. This description is intended to confirm that the embodiments supporting the invention described in this specification are described in this specification. Therefore, although there is an embodiment which is described in the embodiment of the invention but is not described here as corresponding to the invention, it means that the embodiment is not It does not mean that it does not correspond to the invention. Conversely, even if an embodiment is described herein as corresponding to an invention, that means that the embodiment does not correspond to an invention other than the invention. Absent.

  Further, this description does not mean all the inventions described in this specification. In other words, this description is for the invention described in the present specification, which is not claimed in this application, that is, for the invention that will be applied for in the future or that will appear and be added by amendment. It does not deny existence.

  That is, the transmission apparatus of the present invention includes a plurality of first transmission means (for example, UDP ports 87 to 89 in FIG. 4) for transmitting data according to the first protocol of the transport layer, and a port of the first transmission means. Generating means (for example, Multi Flow RTP 83 in FIG. 4) for generating control information for reproducing data, including the number and the number of ports used, and the control information generated by the generating means in the second transport layer The second transmission means (for example, TCP port 86 in FIG. 4) that transmits by the protocol of the above and the data to be transmitted by the protocol of the session layer are allocated and transmitted according to the respective operating states of the plurality of first transmission means. And control means (for example, RTCP 84 in FIG. 4) for controlling to do so.

  Dividing means (for example, Multi Flow RTP 83 in FIG. 4) that divides data to be transmitted by the session layer protocol may be further provided, and the control means may include a plurality of data divided by the dividing means. Can be controlled to be transmitted according to the first protocol of the transport layer by allocating the data according to the respective operating states of the plurality of first transmission means.

  The transmission method according to the present invention includes a plurality of first transmission steps (for example, the processing in step S16 in the flowchart of FIG. 7) for transmitting data according to the first protocol in the transport layer, and the processing in the first transmission step. The generation step (for example, the process of step S14 in the flowchart of FIG. 7) for generating control information for reproducing data, including the port number and the number of ports used, and the control information generated by the process of the generation step A second transmission step (for example, the process of step S15 in the flowchart of FIG. 7), and a plurality of first transmission steps of data to be transmitted using the session layer protocol. A control step (for example, the flowchart of FIG. 7) that controls to allocate and transmit according to each operation state of Characterized in that it comprises a chromatography process in step S16 in g).

  The receiving apparatus of the present invention includes a plurality of first receiving means (for example, UDP ports 67 to 69 in FIG. 4) for receiving data according to the first protocol of the transport layer, the port number of the first receiving means, And second receiving means (for example, TCP port 66 in FIG. 4) for receiving control information for reproducing data, including the number of ports used, in the transport layer second protocol, and the session layer protocol. The reception data is provided with reproduction means for reproducing the data based on the control information (for example, Multi Flow RTP 63 in FIG. 4).

  The reception method of the present invention includes a plurality of first reception steps (for example, the process of step S6 in the flowchart of FIG. 7) for receiving data using the first protocol of the transport layer, and the processes of the first reception step. A second reception step of receiving control information for reproducing data, including the port number of the first port and the number of used ports, using the second protocol of the transport layer (for example, the process of step S4 in the flowchart of FIG. 7) And a reproduction step (for example, the process of step S7 in the flowchart of FIG. 7) for reproducing the data based on the control information as the received data according to the protocol of the session layer.

  Note that the correspondence relationship between the recording medium, the program, and the communication system is the same as that of the transmission apparatus and method and the reception apparatus and method described above, and thus the description thereof is omitted.

  FIG. 2 is a diagram showing a configuration of an embodiment of a distribution system to which the present invention is applied.

  The distribution system of the present invention shown in FIG. 2 is a system that distributes stream data requested from the distribution server 7 to the client PC 1 when there is a stream data distribution request from the client PC 1.

  The client PC 1 specifies an address by a URL (Universal Resource Locator) or the like to the nearest Internet service provider server 3 via the home router 2 and requests the distribution server 7 to distribute the stream data. . Further, when the stream data is distributed, the client PC 1 acquires the stream data transmitted from the Internet service provider server 3 via the home router 2 and reproduces it.

  The home router 2 (hereinafter also simply referred to as router 2) interconnects different networks. More specifically, the router 2 relays the communication path to the destination network according to the routing table in which the communication path is described. Since the router 2 operates in a network layer or higher of an OSI (Open Systems Interconnection) reference model (also referred to as an OSI hierarchical model), the operation depends on the network protocol. The router 2 has various formats such as TCP / IP (Transmission Control Protocol / Internet Protocol), IPX / SPX (Internetwork Packet Exchange / Sequenced Packet Exchange), AppleTalk (trademark), and SNA (Systems Network Architecture). There are types corresponding to various protocols, and these are generally called “multi-protocol routers”. Further, as described above, the router 2 performs flow control and congestion control.

  The Internet service provider server 3 is a server that is managed and operated by a telecommunications carrier that provides an Internet connection service. Internet service providers can use the Internet via a LAN if they belong to an educational institution, organization, or company that owns the server, but a public server that can be used by companies and individuals who do not have a server. Is a telecommunications carrier that provides

  Based on the request from the client PC 1, the Internet service provider server 3 requests stream data from the distribution server 7 specified by the URL via the network 5 represented by the Internet. In response to this request, the internet service provider server 3 acquires the stream data distributed from the distribution server 7 via the network 5 via the router 4 and supplies it to the client PC 1.

  The routers 4 and 6 are the same as the router 2. The router 4 mainly connects the Internet service provider server 3 and the network 5, and the router 6 connects the distribution server 7 and the network 5. , Forming a communication path.

  The network 5 includes a plurality of routers 11a to 11f, and the routers 11a to 11f configure a communication path with each other. The routers 11a to 11f are basically the same as the router 2. In FIG. 2, routers 11a and 11b, routers 11a and 11c, routers 11a and 11d, routers 11b and 11c, routers 11b and 11f, routers 11c and 11d, routers 11c and 11f, routers 11d and 11e, and routers Although 11e and 11f are connected to each other to form a communication path, the routers 11a to 11f may be connected in other combinations to form a communication path. In addition, the network 5 may be formed by a number of routers other than these numbers. Furthermore, when it is not necessary to particularly distinguish the routers 11a to 11f, the routers 11a to 11f are simply referred to as routers 11, and the same applies to other configurations.

  The distribution server 7 distributes the stream data requested from the client PC 1 via the Internet service provider server 3 and the network 5 to the requested client PC 1.

  Next, the configuration of the client PC 1 will be described with reference to FIG.

  A CPU (Central Processing Unit) 21 executes various processes according to a program stored in a ROM (Read Only Memory) 22 or a storage unit 28. A RAM (Random Access Memory) 23 appropriately stores programs executed by the CPU 21 and data. These CPU 21, ROM 22, and RAM 23 are connected to each other by a bus 24.

  An input / output interface 25 is connected to the CPU 21 via the bus 24. The input / output interface 25 is connected to an input unit 26 including a keyboard, a mouse, and a microphone, and an output unit 67 including a display and a speaker. The CPU 21 executes various processes in response to commands input from the input unit 26.

  The storage unit 28 connected to the input / output interface 25 is configured by, for example, a hard disk and stores programs executed by the CPU 21 and various data. The communication unit 29 is, for example, a modem, and exchanges various data with a device having a communication function via a network (not shown).

  The drive 30 connected to the input / output interface 25, when a magnetic disk 41, an optical disk 42, a magneto-optical disk 43, or a semiconductor memory 44 is mounted, drives them, and programs and data recorded there. Get etc. The acquired program and data are transferred to and stored in the storage unit 28 as necessary.

  Note that the configurations of the Internet service provider server 3 and the distribution server 7 are basically the same as those of the client PC 1, and thus the description thereof is omitted, but the ROM 22, the storage unit 28, and the drive 30 are omitted. The program stored in the magnetic disk 41, the optical disk 42, the magneto-optical disk 43, or the semiconductor memory 44 mounted on the Internet service provider server 3 and the distribution server 7 in order to realize the functions described later, Different data from the client PC 1 may be stored, or the processing speed of the CPU 21 and the capacities of the RAM 23 and the storage unit 28 may be changed according to the processing.

  Next, functions realized by the client PC 1 described with reference to FIG. 3 and the distribution server 7 having the same configuration will be described. In FIG. 4, the routers 2, 4, 6, 11, the Internet service provider server 3, and the network 5 are not shown, but all are on the communication path.

  The player 61 is a program for controlling the reproduction of stream data. The player 61 is operated when an instruction to reproduce predetermined stream data is given by a GUI (Graphical User Interface) or when reproduction of stream data is stopped. A command such as playback or stop according to the contents is supplied to an RTSP (Real Time Streaming Protocol) 62 and transmitted to the distribution server 7 via a TCP (Transmission Control Protocol) port 65, and in response to the above-described command. The stream data received from the Multi Flow RTP 63 is temporarily stored and played back as necessary (the data received by the cache function is temporarily stored as needed and is suitable for playback. Read and play at bit rate).

  The RTSP controls the distribution of the real-time stream data, and supplies a stream data control command such as playback or stop supplied from the player 61 to the distribution server 7 via the TCP port 65.

  The RTSP 62 also includes a Transport header field (a field used for data transmission protocol negotiation in the SETUP method) in the SETUP method (procedure for performing negotiation necessary for stream data transmission between the distribution server 7 and the client PC 1). ) Negotiate the stream data transmission protocol. At this time, the RTSP 62 designates RTP / UDP as the transmission protocol. At this time, the range of the UDP ports (UDP ports 67 to 69 in FIG. 4) used for the Multi Flow RTP 63 and the RTCP 64 are used for the client_port parameter and the server_port parameter. Is specified.

  Multi flow RTP 63 is a protocol for transmitting stream data by a plurality of flows. Here, a flow is a data transmission unit defined by a combination of a transmission source, a transmission destination IP address, a transport protocol, and a port. A flow is a unit when a general router controls forward priority.

  The Multi flow RTP 63 controls the UDP ports 67 to 69 specified by the RTSP 62, and acquires the stream data transmitted by being divided into the UDP ports 67 to 69. In addition, the Multi flow RTP 63 assembles (combines) the divided data such as the transmission order and arrangement of the divided stream data supplied from the distribution server 7 via the TCP port 66 from the RTCP 64 and re-assembles the data. Get control information for construction. Further, the multi flow RTP 63 combines the stream data received in the divided state based on the control information acquired from the RTCP 64, reconstructs the original stream data, and supplies the reconstructed stream data to the player 61.

  When the distribution program 81 of the distribution server 7 receives an instruction to reproduce or stop the stream data designated from the client PC 1 via the TCP port 85, the distribution program 81 supplies an instruction corresponding to the instruction to the RTSP 82.

  The RTSP 82 basically corresponds to the RTSP 62 of the client PC 1, but in the distribution server 7, based on the reproduction of the stream data instructed from the distribution program 81 or the stop instruction, Alternatively, the address of the stream data instructed to be stopped is designated and supplied to the Multi Flow RTP 83. In addition, RTSP 82 designates RTP / UDP as a transmission protocol. At that time, the client_port parameter and the server_port parameter indicate the range of UDP ports (in FIG. 4, UDP ports 67 to 69) used by Multi Flow RTP 83 and RTCP 84. specify.

  The Multi Flow RTP 83 basically corresponds to the Multi Flow RTP 63 of the client PC 1. However, the Multi Flow RTP 83 can read out the stream data whose address is specified by the RTSP 82 and transmit it through the specified UDP ports 87 to 89. And is supplied to each of the UDP ports 87 to 89. At that time, information for reconstructing the divided stream data, a port number for identifying a port used for communication among the UDP ports 87 to 89, and Control information including information on the number of used ports is generated and supplied to the RTCP 84.

  More specifically, when stream data to be transmitted in one RTP session is divided so as to correspond to the UDP ports 87 to 89, the control information is a sequence number (Sequence) attached to each divided data. Based on the (Number), information indicating in what order the data of each sequence number was divided, that is, in what order, and UDP ports 87 to 89 used for communication Information including the port number for identifying the UDP port used for the communication and the number of used ports.

  The Multi Flow RTP 83 monitors the operation state (write state to the socket) of each UDP port when actually transmitting data using the plurality of UDP ports 87 to 89, and is divided according to the operation state. Allocate the data and send it to each. The allocation method includes a round robin method and an immediate method. The round robin method is a method in which divided data is allocated to a plurality of UDP ports and transmitted in a predetermined order. The immediate method is a method for allocating and transmitting data to be transmitted immediately to a plurality of UDP ports if writing is possible regardless of the order. The allocation method may be either a round robin method or an immediate method. For example, the allocation method may be switched and used, or other allocation methods may be used.

  The RTCP 84 is basically the same as the RTCP 64 of the client PC 1 but supplies stream data to the client PC 1 by controlling the UDP ports 87 to 89 based on the control information supplied from the Multi Flow RTP 63. In addition, the supplied control information is transmitted to the client PC 1 by controlling the TCP port 86.

  The player 61, RTSP 62, Multi Flow RTP 63, RTCP 64, TCP 65, 66, and UDP 67 to 69, and the distribution program 81, RTSP 82, Multi Flow RTP 83, RTCP 84, TCP 85, 86, and UDP 87 to 89 shown in FIG. These are all protocols, but as shown in FIG. 5, each is classified as follows according to the OSI reference model.

  That is, the player 61 and the distribution program 81 are application layers and define an application that can be seen by a user who operates the client PC 1 or the distribution server 7. At this time, when the stream data is, for example, moving image data, the moving image format that grows in the moving image data becomes the presentation layer, and defines the format and code in communication.

  RTSPs 62 and 82, Multi Flow RTPs 63 and 83, and RTCPs 64 and 84 are session layers and are protocols that define communication procedures. TCP ports 65, 66, 85, and 86 and UDP ports 67 to 69 and 87 to 89 are transport layers and define logical communication paths.

  Based on the above, IP (Internet Protocol), which is a protocol in TCP / IP, becomes a network layer that defines the communication path through the network, and the MAC address (Media Access Control Address) that is the physical address of each device is A data layer that defines a logical signal procedure (for example, a packetization procedure, etc.) between physically adjacent devices, and a physical layer that is a definition of a physical electrical connection such as a LAN.

  FIG. 6 shows the functions of FIG. 4 arranged for each layer based on the OSI reference model described with reference to FIG. In FIG. 6, the overlapping or contacting portions of each block indicate that the upper block in the figure controls the lower block, and each arrow indicates the data transmission direction. ing.

  That is, RTSPs 62 and 82 control Multi Flow RTPs 63 and 83 in the same session layer, respectively, and control TCP ports 65 and 85 in the transport layer, respectively. Multi Flow RTPs 63 and 83 control RTCPs 64 and 84 in the same session layer, respectively. The session layer RTCPs 64 and 84 control the transport layer UDPs 67 to 69 and 87 to 89, and the transport layer TCPs 66 and 86, respectively. At this time, the UDP port of the distribution server 7 and the UDP port of the client PC 1 are paired on a one-on-one basis to exchange data. That is, in FIG. 6, UDP 67 and 87, UDP 68 and 88, and UDP 69 and 89 form a pair, and data is exchanged for each pair.

  With the above function, transmission of stream data transmitted by one session is performed at a plurality of ports. Here, the maximum unit of streaming transmission by Multi-Flow RTPs 63 and 83 is defined as “RTP session”, and a pair of destination / source UDP ports belonging to a certain RTP session (for example, UDP in FIG. 6). The unit of data exchanged by the ports 67 and 87, the UDP ports 68 and 88, or the UDP ports 69 and 89) is defined as “RTP data flow”.

  In this case, each RTP data flow in the Multi Flow RTPs 63 and 83 conforms to the RTP data transmission specification of RFC1889, but the RTCP 64 and 84 do not perform control in units of RTP data flows exchanged with each pair of UDP ports. 67 to 69 and UDP ports 87 to 89 are regarded as one, and the entire RTP session is controlled.

  At this time, the Multi Flow RTPs 63 and 83 assign the sequence numbers of the RTP data packets not in units of RTP data flows but in units of RTP sessions, and even if the data packets are transmitted by different RTP data flows, Uniquely managed by number.

  In normal RTP, the stream data source is identified by SSRC (Synchronization Source: a 32-bit field for identifying the source of a stream data packet in RTP), but Multi-Flow RTP 83 uses SSRC as the RTP session. Match one-on-one. This makes it easy for the Multi-Flow RTP 63 to combine a plurality of RTP data flows as one RTP session, and properly sorts even when data belonging to a plurality of RTP sessions is received at the same UDP port. be able to.

  In addition, although each UDP port of the RTP data flow is assigned in a continuous port range in principle, only an even number of ports in the continuous port range may be assigned in accordance with the provisions of RFC1889.

  Next, stream data distribution processing by the client PC 1 and distribution server 7 of FIG. 4 will be described with reference to the flowchart of FIG.

  In step S1, the player 61 determines whether or not an operation for requesting delivery of predetermined stream data has been performed by operating the input unit 26, and until an operation for requesting delivery of predetermined stream data is performed. Repeat the process. If the user operates the input unit 26 and determines that data distribution is requested, the process proceeds to step S2.

  In step S <b> 2, the player 61 supplies an operation instruction for requesting distribution of stream data to the RTSP 62 and transmits it to the distribution server 7 via the TCP port 65. At this time, naturally, as shown in FIG. 1, information requesting distribution of stream data via a route via the router 2, the Internet service provider server 3, the router 4, the network 5, and the router 6. Is transmitted to the distribution server 7. In the following, since it is assumed that the data of the client PC 1 and the distribution server 7 are exchanged through the same route, the router 2, the Internet service provider server 3, the router 4, the network 5, and A description of data exchange in the router 6 will be omitted as appropriate.

  In step S11, the distribution program 81 determines whether or not the distribution of stream data is requested from the client PC 1 via the TCP port 85 from the RTSP 82, and until it is determined that the distribution of stream data is requested from the client PC 1. Repeat the process. In step S11, for example, when it is determined by the processing in step S2 that distribution of stream data has been requested by the client PC 1, the distribution program 81 controls the RTSP 82 to store the stream data to be transmitted. Is supplied to the Multi Flow RTP 83.

  In step S13, the Multi Flow RTP 83 reads the stream data to be transmitted based on the address information supplied from the RTSP 82, divides the data into numbers corresponding to the UDP ports 87 to 89, and supplies them to the UDP ports 87 to 89. At the same time, control information necessary to reconstruct the stream data divided at this time is generated and supplied to the RTCP 84.

  In step S14, the Multi Flow RTP 83 generates control information including information necessary for reconstructing the divided stream data, and information on the port number of the UDP port used for communication and the number of used ports.

  In step S <b> 15, the RTCP 84 controls the TCP port 86 to transmit control information to the client PC 1.

  In step S16, a plurality of UDP port transmission processes are executed, the UDP ports 87 to 89 are controlled by the RTCP 84, and the stream data individually supplied in a state of being divided by the Multi Flow RTP 83 is transmitted to the client PC 1. The multiple UDP port transmission process will be described later with reference to FIGS.

  In step S3, the Multi Flow RTP 63 controls the RTCP 64, inquires about the TCP port 66, and information necessary for reconstructing the stream data that is divided and received by the UDP ports 67 to 69 (for example, data The control information including the information on the order for reconstructing the data), the port number for identifying the UDP ports 67 to 69 used for communication, and the information on the number of used ports is transmitted. The process is repeated until it is received. For example, when it is determined in step S3 that data has been transmitted by the process of step S15, the process proceeds to step S4.

  In step S4, the RTCP 64 controls the TCP port 66 to receive the control information, and further supplies it to the Multi Flow RTP 63.

  In step S5, the RTCP 64 inquires the UDP ports 67 to 69 based on the port number used for communication of control information and the number of ports to be used, and data is transmitted from the corresponding UDP ports 87 to 89, respectively. The process is repeated until data is transmitted. In step S5, for example, when it is determined that data has been transmitted by the process of step S16, the process proceeds to step S6.

  In step S6, a plurality of UDP port reception processes are executed, and based on the RTCP 64, based on the port number identifying the UDP ports 67 to 69 used for communication included in the control information and the number of used ports, The UDP ports 67 to 69 are controlled, and the transmitted divided stream data is received and supplied to the Multi Flow RTP 63. The multiple UDP port reception process will be described later with reference to FIGS.

  In step S7, the Multi Flow RTP 63 reassembles the divided stream data received from each UDP port based on information necessary for reconstructing the stream data included in the control information. Build and supply to player 61.

  In step S8, the player 61 buffers the assembled and reconstructed original stream data supplied from the Multi Flow RTP 63 for a predetermined time, and reproduces it.

  As a result of the above processing, stream data is transmitted through a plurality of UDP ports in a divided state. For example, as shown in FIG. 8, the stream data is divided by a plurality of communication paths and distributed. Therefore, as shown in FIG. 8, it is possible to transmit all data at a timing before congestion has occurred so far.

  In FIG. 8, for example, the RTP data flow by the UDP ports 67 and 87, the UDP ports 68 and 88, or the UDP ports 69 and 89, which are the UDP port pairs in FIG. It is indicated by a bold line and a bold line with a one-dot chain line. That is, for example, the RTP data flow of the UDP ports 67 and 87 is via the routers 6, 11 f, 11 e, 11 d, 4, the Internet service provider server 3 and the router 2, and the RTP data flow of the UDP ports 68 and 88 Is routed through the routers 6, 11f, 11b, 11c, 11d, 4, the Internet service provider server 3, and the router 2. Further, the RTP data flow of the UDP ports 69 and 89 is the router 6, 11f, 11c, 11d, 4, the Internet service provider server 3, and the router 2, each of which uses a different communication path, so that a wide band can be used and data can be transmitted at high speed. As shown in FIG. 9, transmission is completed until time t <b> 1 where congestion has occurred so far. So that it is, it is possible to realize high-speed communication by suppressing such delay. In FIG. 9, the dotted line indicates the communication so far, and the solid line indicates the data transfer status by the distribution system in FIG. 4. In the communication so far, the time t1 in FIG. Congestion is occurring in the vicinity.

  In the above, an example has been described in which the data to be distributed by one RTP session in the stream data is divided and transmitted by a plurality of RTP data flows. However, in the above communication, communication is performed using a UDP port. If any of the routers on the route discards the packet by flow control or the like, there is a possibility that the Multi Flow RTP 101 cannot reconstruct the stream data without confirming whether or not the transmitted data has arrived. is there. Therefore, when a packet is discarded on the communication path, a retransmission of the lost packet may be requested.

  FIG. 10 is a diagram for explaining functions realized by the client PC 1 and the distribution server 7 that can request retransmission of a lost packet. Note that the same functions as those realized by the client PC 1 and the distribution server 7 shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  10 differs from the client PC 1 and the distribution server 7 in FIG. 4 in that, instead of the Multi Flow RTPs 63 and 83, Multi Flow RTPs 101 and 111 with a retransmission processing function are provided. The Multi Flow RTP 101 with a retransmission processing function basically has the same function as the Multi Flow RTP 63, but is further based on information necessary for reconstructing stream data included in the control information. In the divided stream data supplied from the UDP ports 67 to 69, the presence of missing data is confirmed. When the missing data is detected, the RTCP 64 is controlled and the data of the missing data is transmitted from the TCP port 66. Request resend. In addition, when the Multi Flow RTP 111 with a retransmission processing function controls the RTCP 84 and receives a retransmission request from the Multi Flow RTP 101 with a retransmission processing function from the TCP port 86, the data (packet) for which the retransmission request has been made is transmitted to a plurality of UDP ports. 87 to 89 are controlled and transmitted.

  Next, with reference to the flowchart of FIG. 11, the distribution process by the distribution system by the client PC 1 and the distribution server 7 of FIG. 10 will be described. Note that the processing of steps S31 to S36, S38, and S39 and the processing of steps S51 to S56 in the flowchart of FIG. 11 are the same as the processing of steps S1 to S8 and S11 to S16 in the flowchart of FIG. Description is omitted.

  In step S37, the Multi Flow RTP 101 with a retransmission processing function determines whether or not all the data supplied from the UDP ports 67 to 69 has been received based on the control information supplied from the RTCP 64. For example, as shown in FIG. 12, when the data to be transmitted by the pair of UDP ports 68 and 88 is discarded by the router 11c, the data is lost and not all the data is received. The process proceeds to step S40.

  In Step S40, the Multi Flow RTP 101 with the retransmission processing function determines whether or not it is within the allowable delay time. If it is determined that it is within the allowable delay time, the process returns to Step S37. That is, even when it is determined that all data has not been received, the processes of steps S37 and S40 are repeated within the allowable delay time. If it is determined that it is not within the allowable delay time, the Multi Flow RTP 101 with a retransmission processing function controls the RTCP 64 in step S 41 to send a retransmission request for data missing from the TCP port 66 to the distribution server 7. The process returns to step S33, and the subsequent processes are repeated. More specifically, the sequence number of the missing RTP data packet is specified and retransmission is requested.

  In step S57, the Multi Flow RTP 111 with a retransmission processing function controls the RTCP 84 to determine whether or not a retransmission request has been transmitted to the TCP port 86. For example, it is determined that there has been a retransmission request by the processing in step S41. If so, the process proceeds to step S58.

  In step S58, the Multi Flow RTP 111 with a retransmission processing function designates the address of the data requested to be retransmitted (data address corresponding to the sequence number of the data requested to be retransmitted), and the process proceeds to step S53. Return, and the subsequent processing is repeated.

  If it is determined in step S37 that all data has been received, the process proceeds to step S38. If it is determined in step S57 that there is no retransmission request, the process ends.

  That is, as shown in FIG. 13, the RTP data flow 121 has a plurality of UDP port pairs (for example, UDP ports 67 and 87, UDP ports 68 and 88, which are UDP port pairs in FIG. 6, or UDP ports). 69 and 89), when transmitted from the distribution server 7, the player 61 reproduces the data 131 by the process of step S38 in the flowchart of FIG. Similarly, in the client PC 1, the RTP data flow 122 is similarly transmitted by a plurality of UDP port pairs, so that the data 132 is reproduced.

  However, as shown in FIG. 13, when the RTP data flow 123 is discarded by, for example, the router 11c on the dotted communication path shown in FIG. 12, the corresponding data is lost. become. Therefore, in this case, the corresponding data is not supplied to the player 61. In FIG. 13, the RTP data flow 124 transmitted thereafter is received and the corresponding data 135 is buffered. During this time, if the allowable delay time elapses after the data 123 is lost, the RTCP 64 controls the TCP port 66 to request retransmission by the processing in step S41 described above.

  Then, based on this retransmission request, the RTP data flow 126 is transmitted from the distribution server 7 and the corresponding missing data 134 is buffered, and then the stream data is reproduced. FIG. 13 shows how the RTP data flows 127 and 128 are subsequently transmitted from the distribution server 7 and the corresponding data 136 and 137 are buffered and reproduced. The allowable delay time needs to be shorter than the time obtained by subtracting the retransmission response time predicted from the buffering time (the estimated time until data is transmitted based on the retransmission request).

  Through the above processing, stream data is transmitted in a state of being divided by a plurality of UDP ports, so that all data can be transmitted at the timing before congestion occurs so far, and the communication path Even when data loss occurs above, it is possible to suppress data loss by a retransmission request and realize stable reproduction of stream data.

  In the above description, an example in which one RTP session is transmitted and received using a plurality of RTP data flows (a plurality of UDP ports) has been described. For example, as shown in FIG. A session division program 141 that divides the RTP session itself and a session combination program 142 that combines the divided sessions may be provided in higher layers.

  Furthermore, in the above, an example in which data consisting of one RTP session is divided into a plurality of RTP data flows (a plurality of UDP ports) and transmitted / received simultaneously has been described. For example, as shown in FIG. Instead of the ports 67 to 69 and 87 to 89, TCP ports 151 to 153 and 161 to 163 may be provided. In this case, there is a possibility that the communication speed will be lower than in the case of the UDP port, but because TCP has a function to confirm the arrival of data, it is possible to realize more stable delivery of stream data .

  14 and 15, the Multi Flow RTPs 63 and 83 may be replaced with the Multi Flow RTPs 101 and 111 shown in FIG. 10 to have a retransmission processing function. In addition, although the UDP ports 67 to 69 and 87 to 89 have been described with respect to an example in which all three ports are configured, the present invention is not limited to this, and other UDP ports or TCP ports are used. It may be configured.

  In the above description, an example in which data consisting of one RTP session is divided and transmitted has been described. However, data consisting of one RTP session may be transmitted simultaneously from a plurality of UDP ports.

  FIG. 16 is a diagram for explaining functions realized by the client PC 1 and the distribution server 7 configured to simultaneously transmit data consisting of one RTP session from a plurality of UDP ports. Note that the same functions as those realized by the client PC 1 and the distribution server 7 shown in FIG.

  In the client PC 1 and the distribution server 7 of FIG. 16, functions different from the client PC 1 and the distribution server 7 of FIG. 4 are parallel Multi Flow RTPs 171, 181 and RTCP 172 instead of the Multi Flow RTPs 63, 83 and RTCP 64, 84. , 182 are provided. The parallel Multi Flow RTP 171 basically has the same function as the Multi Flow RTP 63, but supplies information to the UDP ports 87 to 89 without dividing the data to be transmitted, and identifies the data to be transmitted. Is supplied to the RTCP 172. The RTCP 172 is basically the same as the RTCP 84, but since the stream data is not divided, the control is not control information for reconstructing the divided data but information for identifying data to be transmitted. A signal is transmitted to the client PC 1 by controlling the TCP port 86, and the UDP ports 87 to 89 are controlled to transmit data from each to the client PC 1.

  In addition, the parallel Multi Flow RTP 181 controls the RTCP 182 to receive control information that is information for identifying data transmitted from the distribution server 7 via the TCP port 66, and is connected to any of the UDP ports 67 to 69. When data (packet) identified based on the control information is received, the data received at the other UDP ports 67 to 69 are discarded and the first received data is supplied to the player 61 for reproduction. .

  Next, distribution processing by the distribution system including the client PC 1 and the distribution server 7 in FIG. 16 will be described with reference to the flowchart in FIG. Note that the processing in steps S71 and S72 and the processing in steps S91 and S92 in the flowchart in FIG. 17 are the same as the processing in steps S1, S2 and S91 and S92 in the flowchart in FIG. .

  In step S93, the parallel Multi Flow RTP 171 reads out the stream data to be transmitted based on the address information supplied from the RTSP 82, and uses the information for identifying the stream data and communication among the UDP ports 87 to 89. Control information including information on the port number to be used and the number of used ports is generated.

  In step S94, the parallel Multi Flow RTP 171 controls the RTCP 84 to identify the generated stream data to be transmitted from the TCP port 86, and the port number used for communication among the UDP ports 87 to 89. Control information including information on the number of ports used is sent to the client PC 1.

  In step S95, multiple UDP port transmission processing is executed, and stream data to be transmitted is supplied to the UDP ports 87 to 89 by the parallel Multi Flow RTP 171 and transmitted to the client PC 1. That is, by this process, the same stream data to be transmitted is simultaneously transmitted to the client PC 1 from the plurality of UDP ports 87 to 89. In the process of step S95, unlike the processes of steps S16 and S56, the transmitted data is not divided, but the multiple UDP port transmission process itself using the multiple UDP ports 87 to 89 is the same. It is.

  In step S73, the RTCP 182 controls the TCP port 66, determines whether or not control information is transmitted from the distribution server 7, and repeats the processing until it is transmitted. For example, when control information is transmitted by the process of step S93, the process proceeds to step S74.

  In step S 74, multiple UDP port reception processing is executed, the TCP port 66 is controlled by the RTCP 182 to receive control information, and the received control information is supplied to the parallel Multi Flow RTP 181. In the process of step S74, unlike the processes of steps S6 and S36, the received data is not divided, but the multiple UDP port reception process using the multiple UDP ports 67 to 69 is the same. It is.

  In step S75, the parallel Multi Flow RTP 171 determines whether or not the transmitted stream data is received at any of the UDP ports 67 to 69 based on the control information, and performs the process until it is received. repeat. For example, when a plurality of UDP port reception processes are executed in step S76 by the process in step S94 and stream data transmitted from any of the UDP ports 87 to 89 is received, the process proceeds to step S77. .

  In step S77, the parallel Multi Flow RTP 171 compares the stream data received by any of the UDP ports 67 to 69 with the received control information, and determines whether or not the stream data has already been received. . More specifically, the parallel Multi Flow RTP 171 compares the information for identifying the received stream data with the information for identifying the stream data to be transmitted included in the control information. It is determined whether or not the stream data is to be transmitted, and it is determined whether or not the stream data is to be transmitted and is already received. For example, when it is determined in step S76 that the received stream data is the first stream data that has not yet been received, the process proceeds to step S77.

  In step S78, the parallel Multi Flow RTP 171 supplies the received stream data to the player 61 for playback.

  If it is determined in step S77 that the stream data has already been received, that is, the stream data is simultaneously transmitted in parallel through a plurality of UDP ports by the processing in step S94, any one of them is selected. When a plurality of stream data are received at a plurality of UDP ports without being discarded on the path of the parallel multi flow RTP 171, the parallel multi-flow RTP 171 receives the second and subsequent received stream data packets in step S 79. Discard.

  For this reason, in conventional data transfer using UDP packets, when the packet is discarded by any router on the communication path, for example, when the stream data is a moving image, the playback proceeds without reaching the data, thereby degrading the image quality. As a result, the same stream data can be transferred in parallel through multiple ports, and as a result, it is transmitted in parallel. If even one of the stream data is delivered, it is possible to avoid a situation in which the stream data does not reach, so that it is possible to improve the reliability of communication. In addition, when one correct packet arrives, other packets are discarded, and there is no confirmation response. Therefore, while taking advantage of the characteristics of the UDP communication that is faster than the TCP communication, It is possible to realize highly reliable data transfer, which was a weak point in UDP communication.

  In addition, with a single TCP connection or UDP packet, there is a limit on the data capacity that can be transmitted within a single connection or in a single packet. Although there was a problem that it was difficult to use the available bandwidth to the full, the bandwidth was close to the limit by performing the transfer using multiple ports by the TCP method or UDP method by the above processing. And the transfer capacity can be increased.

  That is, by dividing the stream data to be transmitted and simultaneously transmitting / receiving it as a continuous data through a plurality of ports, the data can be transferred at a higher speed. In addition, when the same data is transmitted using a plurality of ports, it is possible to improve the communication reliability by receiving the same data at a plurality of ports in consideration of the situation where the packet is discarded. Transfer at the same speed as transmission / reception on a single port is possible.

  In addition, by using multiple ports as described above, by providing a cache function on the client PC side, necessary data can be transferred at high speed, and the network usage rate can be transferred by multiple transfers. By increasing the communication speed due to the priority control of the router, which is caused by the phenomenon that the communication speed decreases due to flow control, which occurs when general communication uses a single port, or the long-term usage and the communication frequency decreases. It is possible to avoid a phenomenon such as lowering.

  Next, a plurality of UDP port transmission processing and a plurality of UDP port reception processing using the round robin method will be described with reference to the flowchart of FIG. In the flowchart of FIG. 18, the multiple UDP port transmission process and the multiple UDP port reception process will be described as detailed processes of steps S6 and S16 in the flowchart of FIG. 7, but steps S36 and S56 in the flowchart of FIG. The processing in steps S76 and S95 in the flowchart of FIG.

  In step S111, the Multi Flow RTP 83 initializes a counter p for identifying the UDP ports 87 to 89 to 1. In the following description, it is assumed that counter p = 1 corresponds to UDP port 87, counter p = 2 corresponds to UDP port 88, counter p = 3 corresponds to UDP port 89, and UDP port 3 Since the number is P, the upper limit P of the counter p is assumed to be 3, but of course, other numbers may be used.

  In step S112, the Multi Flow RTP 83 executes a UDP port inspection process corresponding to the counter p. That is, for the UDP port corresponding to the counter p, for example, in the first process, the UDP port corresponding to the counter p = 1 is executed.

  Here, the UDP port inspection process will be described with reference to the flowchart of FIG.

  In step S151, the Multi Flow RTP 83 specifies a UDP port to be inspected. More specifically, for example, when UNIX (registered trademark) SystemV (trademark) is used as the OS, Multi Flow RTP83 performs inspection by executing FD-SET (standard macro of OS (= SystemV)). A descriptor for specifying the UDP port corresponding to the target counter p is designated.

  In step S152, the Multi Flow RTP 83 inspects whether or not the UDP port to be inspected can communicate. That is, in more detail, the Multi Flow RTP 83 checks the operation state of the descriptor specified by FD-SET by executing, for example, a select () function (standard function of OS (= SystemV etc.)) (more Specifically, whether the socket of the UDP port to be inspected is writable is inspected).

  In step S153, the Multi Flow RTP 83 confirms the inspection result as to whether or not the UDP port to be inspected can communicate. That is, in more detail, the Multi Flow RTP 83 confirms the result of the select () function, for example, by executing FD-ISSET (standard function of OS (= SystemV)).

  As described above, whether or not one UDP port to be inspected specified by the counter p can be transmitted is inspected by the processing of steps S151 to S153.

  Here, it returns to the flowchart of FIG.

  In step S113, the Multi Flow RTP 83 determines whether or not the UDP port corresponding to the counter p that is the inspection target can be transmitted. For example, if transmission is not possible, that is, for example, in a state where another data is being transmitted or the like cannot be transmitted, the processing returns to step S112. That is, the processes in steps S112 and S113 are repeated until it is determined that transmission is possible.

  If it is determined in step S113 that transmission is possible, the process proceeds to step S114.

  In step S114, the RTCP 84 controls the UDP port corresponding to the counter p, and transmits the stream data divided by the Multi Flow RTP 83 to the client PC 1.

  In step S131, the RTCP 64 controls the UDP ports 67 to 69 based on the port number for identifying the UDP ports 67 to 69 used for communication included in the control information and the information on the number of used ports. Then, the transmitted divided stream data is received and supplied to the Multi Flow RTP 63. That is, the stream data divided by any of the UDP ports 87 to 89 corresponding to the above-described counter p among the UDP ports 67 to 69 is received.

  On the other hand, in step S115, the Multi Flow RTP 83 determines whether there is stream data to be transmitted, that is, whether there is any divided stream data that remains without being transmitted. If there is no data, the process ends.

  If it is determined in step S115 that there is divided stream data to be transmitted, in step S116, the Multi Flow RTP 83 increments the counter p by 1.

  In step S117, the Multi Flow RTP 83 determines whether or not the counter p is larger than the upper limit P. For example, when it is determined that the counter p is not larger, the process returns to step S112.

  If it is determined in step S117 that the counter p is larger than the upper limit P, the process returns to step S111.

  That is, by the above processing, it is determined whether or not each UDP port can be transmitted in the order of the UDP ports 87, 88, 89. When the inspection of the UDP port 89 is completed, the UDP port 87 can be transmitted again. It is determined whether there is any, and the process is repeated. Furthermore, if transmission is not possible, wait until transmission is possible, and when transmission is possible, after sending stream data from that UDP port, the next UDP port is being checked, so it was divided The stream data is always allocated in the order of the UDP ports 87, 88, 89, 87, 88, 89,... (Allocated by the round robin method). Therefore, the client PC 1 receives the UDP ports 67, 68, 69, 67, 68, 69.

  As a result, stream data divided by a plurality of UDP ports is efficiently transmitted. In FIG. 17, it is assumed that the same stream data is transmitted in parallel from a plurality of UDP ports 87, 88, 89, but it is not a simultaneous timing as described above.

  Next, the multiple UDP port transmission processing and the multiple UDP port reception processing by the immediate method will be described with reference to the flowchart of FIG. Note that the processes in steps S171 to S177 and S191 in the flowchart of FIG. 19 are the same as the processes in steps S111 to S117 and S131 in the flowchart of FIG.

  That is, each process of the flowchart of FIG. 19 and each process of the flowchart of FIG. 17 are completely the same. However, in FIG. 17, if it is determined in step S174 that transmission is not possible, the process of step S174 is skipped, and the process proceeds to step S175.

  Therefore, there is no waiting state until it is determined that the UDP port determined to be unable to transmit can be transmitted. For this reason, the transmission order of the plurality of UDP ports 87 to 89 is not constant, but when it is determined that the UDP port cannot be transmitted, another UDP port is immediately inspected and a UDP port that can be transmitted is determined. On the other hand, transmission of stream data that is preferentially divided is allocated.

  As a result, the multiple UDP port transmission processing and the multiple UDP port reception processing by the immediate method can transmit stream data at a higher speed than the multiple UDP port transmission processing and the multiple UDP port reception processing by the round robin method.

  In the above description, an example of using a plurality of UDP ports as an example of using a plurality of ports has been described. However, since the above-described processing is a protocol-independent processing, It is not always necessary to use a UDP port. For example, the same effect can be obtained by using a plurality of TCP ports instead of a plurality of UDP ports.

  FIGS. 21 and 22 show the relationship between the number of TCP ports and the throughput in transmission processing using a plurality of TCP ports and reception processing using a plurality of TCP ports, respectively, in the round robin method and the immediate method. In FIGS. 21 and 22, the solid lines indicate communication paths in usable bands up to 50 Mbps, the dotted lines up to 30 Mbps, and the one-dot chain lines up to 10 Mbps. The vertical axis indicates the throughput (Mbps), and the horizontal axis indicates the number of TCP ports.

  As shown in FIG. 21, when the round robin method is adopted, when the maximum bandwidth is 50 Mbps, the number of ports is two, when the maximum bandwidth is 30 Mbps, when the number of ports is three, and the maximum bandwidth is 10 Mbps. It is shown that the number of ports is 6 and the throughput decreases rapidly.

  On the other hand, as shown in FIG. 22, when the immediate method is adopted, the bandwidth is maximum regardless of the number of TCP ports regardless of the number of TCP ports when the bandwidth is maximum 50 Mbps, when the bandwidth is maximum 30 Mbps, or when the bandwidth is maximum 10 Mbps. It has been shown that can be used fully.

  As a result, as can be seen from FIG. 21 and FIG. 22, in the case of communication using a plurality of TCP ports in the immediate method rather than the round robin method, the bandwidth can be sufficiently used, and at a high speed, It is shown that data can be sent and received. Of course, it goes without saying that the same effect as described with reference to FIGS. 21 and 22 can be obtained even when a plurality of UDP ports are used.

  According to the above, high-speed communication and stable communication can be realized by transmitting communication data of one session in the session layer using a plurality of transport layer ports.

  The series of processes described above can be executed by hardware, but can also be executed by software. When a series of processes is executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a recording medium in a general-purpose personal computer or the like.

  As shown in FIG. 3, the recording medium on which the program is recorded is distributed to provide the program to the user separately from the computer. The magnetic disk 21 (including the flexible disk) on which the program is recorded is distributed. By a package medium composed of an optical disk 22 (including compact disc-read only memory (CD-ROM), DVD (digital versatile disk)), a magneto-optical disk 23 (including MD (mini-disc)), or a semiconductor memory 24 In addition to being configured, it is configured by a ROM 22 on which a program is recorded and a hard disk included in the storage unit 28 provided to the user in a state of being incorporated in advance in a computer.

  In this specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in time series in the order described, but of course, it is not necessarily performed in time series. Or the process performed separately is included.

  Further, in this specification, the system represents the entire apparatus constituted by a plurality of apparatuses.

It is a figure explaining congestion. It is a figure which shows the structure of one Embodiment of the delivery system to which this invention is applied. It is a figure which shows the structure of the client PC of FIG. It is a figure which shows the function implement | achieved by the client PC and distribution server 7 of FIG. It is a figure explaining an OSI reference model. FIG. 5 is a diagram in which functions realized by the client PC and the distribution server 7 shown in FIG. 4 are associated with an OSI reference model. It is a flowchart explaining the delivery process by the function of FIG. It is a figure explaining a delivery process. It is a figure explaining the transfer rate of data. It is a figure which shows the other function implement | achieved by the client PC and distribution server 7 of FIG. It is a flowchart explaining the delivery process by the function of FIG. It is a figure explaining the delivery process by the function of FIG. It is a figure explaining the delivery process by the function of FIG. It is a figure which shows the further another function implement | achieved by the client PC and distribution server 7 of FIG. It is a figure which shows the further another function implement | achieved by the client PC and distribution server 7 of FIG. It is a figure which shows the further another function implement | achieved by the client PC and distribution server 7 of FIG. It is a flowchart explaining the delivery process by the function of FIG. It is a flowchart explaining the multiple UDP port transmission process and multiple UDP port reception process by a round robin system. It is a flowchart explaining a UDP port inspection process. It is a flowchart explaining the multiple UDP port transmission process and multiple UDP port reception process by an immediate system. It is a figure explaining the relationship between the throughput and the number of UDP ports in the multiple UDP port transmission process and the multiple UDP port reception process by the round robin method. It is a figure explaining the relationship between the throughput and the number of UDP ports in the multiple UDP port transmission process and the multiple UDP port reception process by the immediate method.

Explanation of symbols

1 Client PC, 2 Router, 3 Internet Service Provider Server, 4 Router, 5 Network, 6 Router, 7 Distribution Server, 11, 11a to 11f Router, 61 Player, 62 RTSP, 63 Multi Flow RTP, 64 RTCP, 65, 66 TCP, 67 to 69 UDP, 81 player, 82 RTSP, 83 Multi Flow RTP, 84 RTCP, 85, 86 TCP, 87 to 89 UDP, 101, 111 Multi Flow RTP with retransmission processing function, 171 Multi Flow RTP with retransmission processing function , 172 RTSP, 181 Parallel Multi Flow RTP, 182 RTSP

Claims (27)

A plurality of first transmission means for transmitting data according to a first protocol of the transport layer;
Generating means for generating control information for reproducing the data, including the port number of the first transmitting means and the number of ports used;
Second transmission means for transmitting the control information generated by the generation means using a second protocol of a transport layer;
And a control unit configured to control so that data to be transmitted according to a session layer protocol is allocated and transmitted according to an operation state of each of the plurality of first transmission units. The control means performs control so that data to be transmitted by a protocol of a session layer is allocated and transmitted by a round robin method according to each operation state of the plurality of first transmission means. Item 2. The transmission device according to Item 1. The control means performs control so that data to be transmitted by a protocol of a session layer is assigned to a transmittable data according to the operation state of each of the plurality of first transmission means. The transmission device according to claim 1. Dividing means for dividing data to be transmitted by the session layer protocol into a plurality of data;
The control means controls the plurality of data divided by the dividing means to be allocated according to the respective operating states of the plurality of first transmission means and transmitted using the first protocol of the transport layer. The transmission device according to claim 1, wherein: The generating means includes control information for combining and reproducing the divided data when the data is divided by the dividing means, including the port number of the first transmitting means and the number of used ports. The transmitter according to claim 1, wherein the transmitter is generated. The control unit controls the same data to be transmitted by the session layer protocol to be transmitted by a plurality of first transmission units by the first protocol of the transport layer, respectively. The transmitting device according to 1. The generation means identifies the data to be transmitted by the protocol of the session layer, including the port number of the first transmission means and the number of used ports, and generates control information for reproducing the data. The transmission apparatus according to claim 6. The transmission apparatus according to claim 1, wherein the second protocol is TCP. The transmission apparatus according to claim 1, wherein the session layer protocol is RTP. The transmission device according to claim 1, wherein the first protocol of the transport layer is a protocol that does not check arrival of transmitted data. The transmission apparatus according to claim 10, wherein the first protocol of the transport layer that does not check arrival of the transmitted data is UDP. The transmission device according to claim 1, wherein the first protocol of the transport layer is TCP. A plurality of first transmission steps for transmitting data according to a transport layer first protocol;
A generation step of generating control information for reproducing the data, including the port number in the process of the first transmission step and the number of ports used;
A second transmission step of transmitting the control information generated in the processing of the generation step by a second protocol of a transport layer;
And a control step of controlling to transmit data to be transmitted according to a protocol of a session layer in accordance with an operating state of each of the plurality of first transmission units. A plurality of first transmission control steps for controlling transmission of data according to a first protocol of the transport layer;
A generation control step for controlling generation of control information for reproducing the data, including the port number and the number of ports used in the processing of the first transmission step;
A second transmission control step for controlling transmission of the control information generated in the processing of the generation control step in a second protocol of a transport layer;
An operation control step for controlling the transmission of data to be transmitted according to the protocol of the session layer in accordance with each operation state of the processing of the plurality of first transmission control steps. A recording medium on which the program is recorded. A plurality of first transmission control steps for controlling transmission of data according to a first protocol of the transport layer;
A generation control step for controlling generation of control information for reproducing the data, including the port number and the number of ports used in the processing of the first transmission step;
A second transmission control step for controlling transmission of the control information generated in the processing of the generation control step in a second protocol of a transport layer;
A program that causes a computer to execute an operation control step of controlling to transmit data to be transmitted according to a protocol of a session layer in accordance with each operation state of the processing of the plurality of first transmission control steps. A plurality of first receiving means for receiving data in accordance with a transport layer first protocol;
Second receiving means for receiving control information for reproducing the data, including the port number of the first receiving means and the number of used ports, using a second protocol of the transport layer;
Receiving apparatus comprising: reproducing means for reproducing the data based on the control information as received data according to a session layer protocol. The data is a plurality of divided data,
The plurality of first receiving means receive the divided data, respectively.
The reproducing means is based on the control information including information for combining and reproducing the divided data in addition to the port number and the number of used ports received by the second receiving means. The reception apparatus according to claim 16, wherein the plurality of data are combined and reproduced as reception data according to a session layer protocol. The data is a plurality of identical data,
The plurality of first receiving means respectively receive the same data,
The reproducing means includes a plurality of first information based on the control information including information identifying the data in addition to the port number and the number of ports used, received by the second receiving means. The receiving apparatus according to claim 16, wherein, among receiving means, data received first is reproduced as received data according to a session layer protocol. The receiving apparatus according to claim 16, wherein the second protocol is TCP. The receiving apparatus according to claim 16, wherein the session layer protocol is RTP. The receiving apparatus according to claim 16, wherein the first protocol of the transport layer is a protocol that does not check arrival of transmitted data. The receiving apparatus according to claim 21, wherein the first protocol of the transport layer that does not check the arrival of the transmitted data is UDP. The receiving apparatus according to claim 16, wherein the first protocol of the transport layer is TCP. A plurality of first receiving steps for receiving data according to a transport layer first protocol;
A second reception step of receiving control information for reproducing the data, including the port number in the processing of the first reception step and the number of used ports, by a second protocol of the transport layer;
And a reproduction step of reproducing the data based on the control information as received data according to a session layer protocol. A plurality of first reception control steps for controlling reception of data by a first protocol of the transport layer;
Second reception for controlling reception of the control information for reproducing the data in the second protocol of the transport layer, including the port number in the processing of the first reception control step and the number of used ports. Control steps;
A recording medium on which a computer-readable program is recorded, comprising: a reproduction control step for controlling reproduction based on the control information of the data as received data by a session layer protocol. A plurality of first reception control steps for controlling reception of data by a first protocol of the transport layer;
Second reception for controlling reception of the control information for reproducing the data in the second protocol of the transport layer, including the port number in the processing of the first reception control step and the number of used ports. Control steps;
A program that causes a computer to execute a reproduction control step of controlling reproduction based on the control information of the data as received data according to a protocol of a session layer. In a communication system consisting of a transmission device and a reception device,
The transmitter is
A plurality of transmission means for transmitting data according to a transport layer protocol;
Generating means for generating control information for reproducing the data, including the port number of the first transmitting means and the number of ports used;
Second transmission means for transmitting the control information generated by the generation means using a second protocol of a transport layer;
Control means for controlling the data to be transmitted according to the protocol of the session layer so as to allocate and transmit the data according to the operating state of each of the plurality of first transmission means,
The receiving device is:
Receiving means for receiving data according to the transport layer protocol;
Second receiving means for receiving control information for reproducing the data, including the port number of the first receiving means and the number of used ports, using a second protocol of the transport layer;
A communication system comprising: reproduction means for reproducing the data based on the control information as received data according to a session layer protocol.

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