JP6401546B2 - Content distribution server and content distribution program - Google Patents

Description

  The present invention relates to a content distribution server, a receiving device, and a content distribution program, and in particular, a content distribution server and a receiving device for suppressing variation in arrival time of content distributed to each receiving device connected to the content distribution server. And a content distribution program.

  Conventionally, there are services that distribute various contents to receiving apparatuses. In such a distribution service, a push-type information distribution technique is known in which information is directly delivered from a content distribution server to a user receiving device. For example, as distribution information such as IP (Internet Protocol) content, for example, information related to TV broadcast programs, the latest information on weather according to individual user needs, the latest information on traffic, applications, or various information requested by users Data.

  In a large-scale IP content push-type information distribution service, a large number of receiving devices establish communication sessions on one content distribution server and distribute IP content. With respect to IP content distributed in real time, distribution is performed simultaneously from the content distribution server to the receiving device. However, even if each receiving device that has established a session with the content distribution server is connected to the same distribution server, the communication distance with each receiving device is different. For example, when a content distribution server is arranged in Tokyo, the communication distance is different if the receiving device is in Tokyo, Osaka, Okinawa, or the like. Therefore, the time required for communication with the content distribution server (for example, RTT (Round Trip Time)) differs for each receiving device, and the timing at which IP content arrives also differs for each receiving device. In addition, since the time required for distributing data to each receiving apparatus varies every time depending on the state of the communication path, it is not actually constant.

  For this reason, there is a variation in the arrival time of IP contents distributed simultaneously from the content distribution server in each receiving device, and it is difficult to simultaneously distribute the distributed content to all receiving devices without variation. .

  Therefore, conventionally, by adjusting the distribution time of IP content at the distribution server so that the reception time of data is the same for a large number of reception devices connected to the distribution server, A technique for reducing variation in reception time is disclosed (for example, see Non-Patent Document 1).

  In addition, in a system in which a receiving apparatus receives IP content from a content distribution server, a technique for constructing a distribution network so as to reduce the distribution delay by considering the installation location of the receiving apparatus and the connection environment is disclosed ( For example, see Patent Document 1).

JP 2006-332825 A

Takeshi Tanaka et al. “Study of delivery control method in push delivery server considering client RTT”, Annual Conference of Video Information Media Society of Japan 18-12

  By the way, in the push-type information distribution service described above, a service that repeatedly distributes data at a constant cycle is assumed. For example, in the technology as described in Non-Patent Document 1 described above, the target delivery time is set and the delivery time of each receiving device is delayed to reduce the variation in the reception time of the IP content. If the RTT is large and the distribution time does not fit within the target distribution time, or depending on the size of the distribution required time that fluctuates for each distribution cycle, the distribution time is delayed so that distribution to other receiving devices is distributed. There has been a problem that a receiving device that cannot be distributed may occur due to a situation that does not fit within a cycle.

  In addition, the technique disclosed in Patent Document 1 does not consider the distribution delay difference between the content distribution server and the receiving device connected to the distribution server, and the reception is performed even though the connected distribution server is the same receiving device. There is a problem in that the delivery content arrival time differs between devices.

  In one aspect, an object of the present invention is to provide a content distribution server, a reception device, and a content distribution program for suppressing variation in arrival time of distribution content between reception devices connected to the distribution server. .

  In order to solve the above problems, the present invention employs means for solving the problems having the following features.

In one embodiment, the present invention is, for each receiving device connected via a communications network, the content delivery server for delivering content to be displayed to the each receiving device at a predetermined delivery period, wherein from each reception apparatus receiving the connection request, the session control means for establishing a session between said each of the receiving device, before delivering the content to the receiving device to establish a session by the session control unit, the each reception apparatus perform delay confirmation request for the delay verify the delay amount measuring means for measuring a reception delay amounts of the respective receiving device based on the response information to the request, the delay amount measuring means and the respective receiving devices obtained by using the reception delay amount, the other receiving apparatus in accordance with the time during which the content reaches the highest reception apparatus receives delay The distribution time for each receiving device is set so that the content arrives, and the set distribution time is before the start time of the predetermined distribution cycle or after the end time of the predetermined distribution cycle A distribution time setting unit that updates the distribution time within the predetermined distribution period, and a content transmission unit that transmits the content to each receiving device based on the distribution time obtained by the distribution time setting unit. Have.

  Moreover, as one aspect, the present invention is a content distribution program for causing a computer to function as each unit included in the above-described content distribution server.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersion | variation in the arrival time of the content delivered to each receiver connected to the content delivery server can be suppressed.

It is a figure which shows the schematic structural example of a content delivery system. It is a figure which shows the function structural example of a content delivery server. It is a figure which shows the function structural example of a receiver. It is FIG. (1) for demonstrating the outline | summary of a content delivery process. It is FIG. (2) for demonstrating the outline | summary of a content delivery process. It is a figure which shows the example of updated content delivery. It is a figure which shows the example of data in this embodiment. It is a flowchart which shows 1st Example of a content delivery process. It is a flowchart which shows 2nd Example of a content delivery process.

<About this embodiment>
In the present embodiment, for example, when content is distributed from a content distribution server to a plurality of receiving devices, the distribution content arrival times in all the receiving devices are matched, and the content is synchronously distributed to all the receiving devices. For example, when the content delivery server push-distributes the content to the receiving device, the RTT in each receiving device is fed back to the content delivery server, and the reception delay amount with each receiving device is managed in the content delivery server. Also, based on this reception delay amount, the distribution content arrival time or any distribution target time of the receiving device with the latest delivery content arrival time, for example, the receiving device with the largest RTT, is calculated, and the other Time distribution when distributing content to the receiving device.

  In addition, in the present embodiment, when there is a receiving device that has a delivery time earlier than the target delivery time or a receiving device that does not fit in the delivery cycle due to the adjustment of the delivery time, the delivery time is reset by that time. Adjust and distribute to all receiving devices. Thereby, the dispersion | distribution of the arrival time of the delivery content in each receiving device is suppressed, and the push delivery of the synchronized content to more each receiving devices is attained. Hereinafter, a preferred embodiment of a content distribution server, a receiving device, and a content distribution program will be described in detail with reference to the drawings.

<Example of schematic configuration of content distribution system>
FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system. A content distribution system 10 illustrated in FIG. 1 includes a content distribution server 11 and one or a plurality of receiving devices 12-1 to 12-n (hereinafter, collectively referred to as “receiving device 12” as necessary). Yes. The content distribution server 11 and the receiving device 12 are connected in a state where data can be transmitted and received through a communication network 13 typified by the Internet or a LAN (Local Area Network).

  The content distribution server 11 distributes the same content to each receiving device 12 via the communication network 13. In addition, the content distribution server 11 multiplexes and transmits the content to be distributed (for example, an IP packet transmitted via an IP network which is an example of the communication network 13) in time series.

  The content distribution server 11 in this embodiment may be a general-purpose server or a PC (Personal Computer), for example. Further, the content distribution server 11 is not limited to one, and a plurality of content distribution servers 11 may be provided at different points. The content distribution server 11 may be a cloud server configured by cloud computing having one or more information processing devices, for example.

  For example, the receiving device 12 receives content (distribution information) received from the content distribution server 11 via the communication network 13 together with a broadcast program received in real time in a transmission form (for example, broadcast wave) different from the communication network 13, for example. Display on the screen. For example, in a sports broadcast program, the receiving device 12 can display information (contents) related to players such as player names and results in synchronization with baseball players and soccer players displayed on the screen by broadcast waves, Synchronize quiz questions and answers, information on stores and product information displayed on the screen in information programs, information such as one scene of a drama or information (subtitles) spoken by the characters with broadcast waves Or stock trade information etc. are displayed in synchronism between the other receiving devices 12, but the present invention is not limited to this.

  It is desirable to distribute the information as described above, for example, by linking (synchronizing) as much as possible to the screen of a TV broadcast program. For example, before the screen is displayed, related distribution information is displayed in advance or already displayed. If the distribution information remains as it is even though the screen (scene) related to the distribution information is finished, it is very uncomfortable for the viewer.

In addition, since the receiving device 12 has different communication positions (installation locations) for receiving content, the receiving delay amount (for example, round trip delay time (RTT)) between the content distribution server 11 and each receiving device 12 is 1 /. value) is that the 2, ₁ second RTT of each receiver 12, as shown in FIG. 1 _{T, T 2} seconds, ..., when _{T N seconds, T} 1/2 _{seconds, T} 2/2 seconds, ..., Each will be different, such as T _N / 2 seconds. Therefore, the arrival time of the content distributed from the content distribution server 11 to each receiving device 12 varies in each receiving device 12. Therefore, in the present embodiment, for example, distribution information (IP content) is displayed in synchronization with a screen of a television broadcast program, and control is performed so that no variation occurs between the receiving apparatuses 12.

  The receiving device 12 in the present embodiment is, for example, a PC, a notebook PC, a mobile phone, a smartphone, a tablet terminal, a television, a game device, or the like. As an example, the receiving device 12 is connected to the communication network 13 and a function for receiving and displaying broadcast waves. And a function for transmitting and receiving information.

<Example of Functional Configuration of Content Distribution Server 11>
Next, a functional configuration example of the content distribution server 11 in the present embodiment will be described with reference to the drawings. FIG. 2 is a diagram illustrating a functional configuration example of the content distribution server. In the example of FIG. 2, the content distribution server 11 includes a control unit 20, a communication unit 30, and a storage unit 40. The control unit 20 includes a session control unit 21, a delay amount measurement unit 22, a content generation unit 23, a distribution time setting unit 24, and a content transmission unit 25. In addition, the storage unit 40 includes session management information 41 and distribution time information 42.

  The session control unit 21 controls session establishment and disconnection between the content distribution server 11 and the reception device 12 in response to a connection request or disconnection request from the reception device 12. For example, the session control unit 21 stores a session ID assigned to each session in the session management information 41 of the storage unit 40 when a session is established. In addition, when the session is disconnected, the session control unit 21 deletes the session ID to be disconnected stored in the session management information 41, various information associated with the session ID, the record of the distribution time information 42, and the like. .

  The delay amount measuring unit 22 measures the reception delay amount of the receiving device 12 and stores the measurement result in the session management information 41 of the storage unit 40 in association with the session ID. For example, the delay amount measuring unit 22 measures the reception delay amount by executing a ping command from each receiving device 12 as an example of the delay amount confirmation request and measuring the RTT from the response information. Further, the delay amount measuring means 22 is a request message (delay amount confirmation) from the content distribution server 11 when, for example, transmission / reception between the content distribution server 11 and the receiving device 12 is performed by TCP (Transmission Control Protocol). ACK message (response information) is received from the receiving device 12 for an example of a request), and RTT is obtained by measuring the reception delay amount by the difference between the time when the request message is transmitted and the time when the ACK message is received. May be. The reception delay amount in each receiving device 12 can be obtained by setting RTT indicating the round trip time to ½, but is not limited to this. For example, when the communication speed is different between upstream and downstream Alternatively, the value may be adjusted based on the ratio.

  In addition, the delay amount measuring unit 22 may measure the reception delay amount for each distribution cycle when, for example, an IP packet is transmitted in a time-sharing manner with a predetermined distribution cycle, and immediately after establishing a session with the receiving device 12, The reception delay amount may be measured at a timing at which the IP packet is first transmitted, a predetermined timing such as a predetermined time interval, or the like. Further, the delay amount measuring means 22 may calculate an average value from the statistics of the past several reception delay amounts, and store the calculated average value in the session management information 41. By using the average value, it is possible to reduce the influence due to a temporary line state malfunction or the like.

  The content generation unit 23 generates content to be distributed to the receiving device 12 and outputs the generated content to the content transmission unit 25. The content is, for example, information associated with a broadcast wave transmitted to the receiving device 12 in another transmission form (for example, program related information, information about a displayed person, shop, clothes, etc.). However, the present invention is not limited to this.

  The distribution time setting unit 24 sets the distribution order and distribution time for each session ID in a predetermined distribution cycle. For example, the delivery time setting unit 24 refers to the session management information 41 in the storage unit 40 and sets the delivery order for each session ID (each receiving device 12) based on the reception delay amount included in the session management information 41. . The distribution order is set in, for example, the order of descending reception delay amount (descending order), but is not limited to this. For example, when the processing performance of each receiving device 12 is acquired, the performance is reduced. Accordingly, the distribution order may be adjusted so that the IP packet of the receiving apparatus that is slow in processing is transmitted early.

  Further, the distribution time setting unit 24 calculates a distribution time for each session ID based on the set distribution order, and stores the distribution time in the distribution time information 42. For example, the delivery time setting unit 24 transmits an IP packet (content) to the receiving device 12 having the largest reception delay amount, and the time until the content arrives (the receiving device 12 to output a program at a target time). The time at which the IP packet must be reached) is set as the distribution target time, and the distribution time is set so that the IP packet reaches the other receiving apparatus 12 in accordance with the distribution target time. Further, the distribution time setting means 24 sets the distribution time within one distribution cycle with the distribution interval necessary for displaying the continuous content on the screen of each receiving device 12 in real time without interruption. However, the setting method is not limited to these.

  In the present embodiment, for example, when the content to be distributed is associated with a program provided from the outside (for example, a broadcasting station) to the receiving device 12 by a broadcast wave or the like, it is matched with the broadcast time timing of the program. The delivery time is set so that the content can be displayed (in synchronization).

  The delivery time setting unit 24 performs readjustment of the delivery time when there is a session ID (receiving device 12) that causes the delivery time to protrude from the delivery cycle, and sets all session IDs based on the readjustment result. On the other hand, the distribution time is updated so that the IP packet is distributed within the distribution cycle. The updated delivery time is stored in the delivery time information 42. A specific update example will be described later.

  The content transmission unit 25 acquires the receiving device 12 with which the session is established from the session management information 41, and is calculated by the distribution time setting unit 24 for each acquired receiving device 12 (session ID). The communication unit 30 transmits the IP packet of the content generated by the content generation unit 23 based on the distribution time stored in the communication unit 30. The content transmitting unit 25 may be configured to be separated from the content distribution server 11 and input IP content data from the outside.

  The communication means 30 is a communication interface that performs transmission / reception of data with the receiving device 12 or the like. For example, the communication unit 30 receives a connection request or a content distribution request from the receiving device 12 based on predetermined address information or a session ID for the receiving device 12, measures the RTT of the receiving device 12, The contents generated by the generating means 23 are transmitted.

  The storage unit 40 stores the session management information 41 and the distribution time information 42 described above. The information stored in the storage unit 40 is not limited to this, and various settings such as content contents, content distribution result (log information) and error information, identification information and distribution address of the receiving device 12, etc. Information or the like may be stored.

<Functional Configuration Example of Receiving Device 12>
Next, a functional configuration example of the receiving device 12 in this embodiment will be described with reference to the drawings. FIG. 3 is a diagram illustrating a functional configuration example of the receiving apparatus. The receiving device 12 illustrated in FIG. 3 includes a control unit 50 and a communication unit 60. The control unit 50 includes a session control unit 51, a program acquisition unit 52, a content acquisition unit 53, and a display unit 54.

  The session control means 51 makes a session request to the content distribution server 11 to establish a session. The session control means 51 responds in response to the execution of the ping command from the content distribution server 11 or returns an ACK message to the request message from the content distribution server 11. The session control means 51 controls disconnection of a session established by an instruction from the user.

  The program acquisition unit 52 is a first information acquisition unit that acquires a program or the like by broadcast waves as an example of the first information displayed on the display unit 54. The broadcast wave may be push-distributed from the providing side (for example, a broadcasting station or the like), or may be received by requesting the providing side from the program acquisition unit 52.

  Examples of programs include sports, news, variety, drama, etc., but are not limited to these. The broadcast wave of the program as described above may be distributed from another device in a broadcasting station, for example, or may be distributed from the content distribution server 11.

  As an example of the second information displayed on the display unit 54, the content acquisition unit 53 is distributed from the content distribution server 11 via a transmission mode (for example, the communication network 13) different from the transmission mode from which the first information is acquired. It is the 2nd information acquisition means which acquires the content matched with the program of a broadcast wave. The content may be push-distributed from the providing side (for example, the content distribution server 11), or may be received by requesting the providing side from the program acquisition means 52.

  An example of the content is various information related to the above-described program (program content, information about a displayed person, shop, clothes, etc.), but is not limited thereto.

  The display unit 54 displays the program acquired by the program acquisition unit 52 and the content acquired by the content acquisition unit 53. The display unit 54 is, for example, a display, a monitor, a touch panel, or the like, but is not limited thereto.

  The communication means 60 is a communication interface that performs transmission / reception of data with the content distribution server 11 and the like. For example, the communication unit 60 can make a session establishment request or a disconnection request to the content distribution server 11, receive a broadcast wave, or receive content.

  In the present embodiment, the program to be displayed and the content are distributed at a timing at which they can be displayed synchronously, and are also distributed synchronously between the receiving devices 12 connected to the same content distribution server 11. Therefore, it is possible to view the program and the content in synchronism without performing special adjustment processing on the receiving device 12 side.

  According to the present embodiment, it is possible to suppress the variation in the arrival time of the distribution content between the reception devices 12 connected to the content distribution server 11 and to perform push distribution that does not generate the reception device 12 that cannot be distributed.

<Example of content distribution processing overview>
Next, an outline example of content distribution processing in the present embodiment will be described with reference to the drawings. 4 and 5 are diagrams (No. 1 and No. 2) for explaining the outline of the content distribution processing. 4 and 5 show two examples (Example 1 and Example 2) that cannot be distributed by a conventional method (for example, the method shown in Non-Patent Document 1), and a distribution example according to this embodiment.

4 and FIG. 5 represents one distribution data (one IP packet) corresponding to the identification information (number) of each receiving device 12, and the size (diameter) is the content distribution server. Reference numeral 11 denotes a time required to issue an IP packet to each receiving device 12. Also, in the delivery order, in the example of FIGS. 4 and 5, the delivery time difference (empty interval) of the same IP packet in each receiving device 12 in the same delivery cycle is represented by d ₁ , d ₂ ... Dn _{+ 1} , respectively. ing.

The part in contact with the circle (o) indicates that there is no empty space, and d = 0. D ₁ is an interval (time) from the start time of the distribution cycle to the start of distribution to the first receiving device 12 (identification number 1), and d _{n + 1} is the last receiving device 12 (identification number n). ) Is the interval (time) from the end of distribution to the end time of the distribution cycle.

For example, as shown in FIG. 4 and FIG. 5, the content is distributed to the 1st to n-th receiving devices 12 having a session with the content distribution server 11 and the content distribution data (IP packet) is transmitted at a predetermined distribution cycle. Time-division distribution is performed in a predetermined distribution order. In this case, the reception delay amount in each receiving device 12 is measured, and based on the measurement result, the delivery time of each IP packet is adjusted so that the data arrival time of each receiving device 12 matches the target time. At this time, depending on the distribution cycle, there may be an IP packet that must be output earlier than the distribution cycle as shown in FIG. 4 due to the measured reception delay amount. In this case, all cannot be distributed in one distribution cycle (example 1 in which distribution is not possible). Specifically, as shown in FIG. 4, the timing for delivering the IP packet protrudes by the time s _f before the delivery cycle start time.

Depending on the delivery cycle, there may be an IP packet that does not fall within the delivery cycle as shown in FIG. 5 due to the measured reception delay amount. In this case, all packets are delivered in one delivery cycle. Cannot be performed (example 2 in which distribution is not possible). Specifically, as shown in FIG. 5, the timing for distributing the IP packet protrudes by the time s _b after the end time of the distribution cycle.

Therefore, in this embodiment, for example, as shown in FIG. 4, it is slid behind the overall delivery timing by s _f, to be delivered to all IP packets 1 delivery period. Also, as shown in FIG. 5, all IP packets can be delivered in one delivery cycle by sliding forward by s _b at the overall delivery timing. In the present embodiment, readjustment is performed using the delivery time difference (empty interval) d so that no other IP packet protrudes due to the slide described above.

For example, the distribution time setting unit 24 obtains the total sum of the above-mentioned empty intervals by the expression (1), compares the total sum with s _f , s _b, etc., and “d ₁ + d ₂ +... + D _{n + 1} > s _If “ _f ”, “d ₁ + d ₂ +... + dn _{+ 1} > s _b ”, etc., the delivery time is readjusted and the delivery time is set. And the content transmission means 25 becomes possible to deliver to all the receiving apparatuses 12 within a delivery period by delivering an IP packet at the delivery time updated by readjustment.

なお、空き間隔の総和の計算において、配信周期からはみ出している部分（図４の例ではｄ_１，ｄ_２、図５の例では、ｄ_ｎ−１，ｄ_ｎ，ｄ_ｎ＋１）については、総和の計算に含めなくてもよい。つまり、一例としては、配信周期内における空き間隔の総和（配信周期内においてＩＰパケットを配信していない時間）を計算する。また、本実施形態においては、上述したｓ_ｆ及びｓ_ｂの両方を含む場合もある。

Incidentally, in the calculation of the sum of the free period, a portion which protrudes from the distribution period _(d 1 in the example of FIG. 4, _{d 2,} in the example of FIG. _{5, d n-1, d} n, d n + 1) for the sum It does not have to be included in the calculation. That is, as an example, the sum of empty intervals within the distribution cycle (time during which no IP packet is distributed within the distribution cycle) is calculated. In the present embodiment, or it may include both of s _f and s _b described above.

Next, an update example by readjustment of the delivery time will be described. In the following description, an arbitrary distribution target time is t _def , and a distribution order of receiving apparatuses that distribute in one distribution cycle is 1 to n (for example, an order set in descending order based on an RTT value), and each distribution time T ₁ to t _n , L is the time required to issue an IP packet to each receiving device 12, t _{c is} the delivery period, and m _f and m _b are the numbers of receiving devices corresponding to s _f and s _b described above, respectively. To do. Further, when there is no empty interval at the time of packet delivery to the receiving device corresponding to s _f and s _b (d = 0), s _f and s _b are “s _f = m _f × L” and “s _b = m, respectively. _b × L ”or the like.

<Delivery time update example 1>
In update example 1, the distribution time is slid as a whole. For example, when the relationship between the above-described expression (1) and s _f and s _b is “(1) expression ≧ s _f + s _b ”, the updated t 'Calculate _n .

In the above-described formula (2), when s _f > 0, t ₁ = t _def , and when s _b > 0, t _n = t _c −L. That is, in the case of “(1) expression ≧ s _f + s _b ”, for example, _dn is reduced by a value obtained by the following expression (3), and the delivery time is shortened as a whole.

また、「（１）式＜ｓ_ｆ＋ｓ_ｂ」となる場合には、配信周期に全ての配信データを配信しきれない状態となる。そのため、上述の条件を満たす場合には、例えば配信周期に収まらない配信データの一部又は全部を破棄する。例えば、ｔ_１＝ｔ_ｄｅｆとし、その他の配信時刻は配信順序１番目から昇順にｔ_ｃに収まる配信データ分だけｔ_ｎ＝ｔ_ｎ−１＋Ｌで更新する。また、別の例としては、例えばｔ_ｎ＝ｔ_ｄｅｆ＋ｔ_ｃ−Ｌとし、その他の配信時刻は配信順序ｎ番目から降順にｔ_ｃに収まる配信データ分だけｔ_ｎ＝ｔ_ｎ−１＋Ｌに更新する。つまり、何れの場合にも配信周期に収まらない前方又は後方の配信データの一部又は全部を破棄する。

Further, when “(1) expression <s _f + s _b ” is satisfied, it becomes a state in which all distribution data cannot be distributed in the distribution cycle. Therefore, when the above-described conditions are satisfied, for example, part or all of the distribution data that does not fit in the distribution cycle is discarded. For example, t ₁ = t _def and other distribution times are updated with t _n = t _n−1 + L for the distribution data that falls within t _c in ascending order from the first distribution order. As another example, for example, t _n = t _def + t _c −L, and other distribution times are updated to t _n = t _n−1 + L by the amount of distribution data that falls within t _c in the descending order from the distribution order n. To do. That is, in any case, a part or all of the front or rear distribution data that does not fit in the distribution cycle is discarded.

<Delivery time update example 2>
Next, update time 2 of the delivery time will be described. In update example 2, the distribution time is partially slid. For example, in the case of “(1) expression ≧ s _f ”, _f satisfying “s _f ≧ d ₁ + d ₂ +... D _f ” is calculated (the time at that time is defined as t _f ), and t ₁ = T _def and the distribution times of t ₂ to t _f are updated with t _n = t _n−1 + L. In addition, in the case of “(1) expression ≧ s _b ”, _{b that} satisfies “s _b ≧ d _n + d _n−1 +... D _b ” is calculated (the time at that time is set to t _b ). , and _{t n = t def + t c} -L, updates the delivery time of the time _t b _{~t n-1} at _{t n = t n-1 +} L.

In the case of “(1) expression ≧ s _fb ” and “(1) expression ≧ s _b ”, t ₁ = t _def, and after updating from t ₂ to t _f , the expression (1) is obtained again, in the case of "(1) ≧ _{s b" is} set to _{t n = t def + t c} -L, calculates b becomes _{"s b ≧ d n + d n} -1 + ··· d b " (the time is referred to as _{t b} of the _time), the delivery time of _t b _{~t n-1} is updated with _{t n = t n-1 +} L.

Also, the update example _2, after updating the _t b _{~t n-1,} may be updated in the order of t 2 ~t _f. Further, when “(1) expression <s _f + s _b ” is satisfied, it becomes a state in which all distribution data cannot be distributed in the distribution cycle. Therefore, when the above conditions are satisfied, a part or all of the distribution data that does not fit in the distribution cycle is discarded. For example, t ₁ = t _def and other distribution times are updated to t _n = t _n−1 + L for the distribution data that falls within t _c in ascending order from the first distribution order. As another example, for example, t _n = t _def + t _c −L, and other distribution times are updated to t _n = t _n−1 + L by the amount of distribution data that falls within t _c in the descending order from the distribution order n. To do. That is, in any case, a part or all of the front or rear distribution data that does not fit in the distribution cycle is discarded.

In addition, since the arbitrary delivery target time t _def described above is a time at which each IP packet should reach the receiving device (for example, a time at which a program starts), strictly speaking, the time changes for each delivery cycle. . For example, if the delivery target time for the first cycle (first packet) is t _def , the delivery target time for the second week (second packet) is t _def + t _c (t _c is the delivery cycle). In addition, the distribution target time for the third period is t _def + t _c × 2, and changes similarly thereafter. Therefore, it is assumed that the distribution target time t _def used in the description of the present embodiment changes in accordance with the number of distribution cycles as described above.

  FIG. 6 is a diagram illustrating an example of updated content distribution. First, in the conventional distribution example, since a plurality of packets corresponding to each receiving device 12 are distributed in a time division set in advance in the content distribution server 11, distribution is performed before and after the distribution cycle as shown in FIG. In some cases, data that cannot be generated occurs (distributed data for the receiving devices 1 and 2 before the cycle, and distributed data for the receiving devices n-1 and n after the cycle). Therefore, a control function for adjusting the distribution time is provided by each of the update examples 1 and 2 described above.

  In the update example 1 described above, as shown in FIG. 6B, the distribution time of distribution data for all the receiving apparatuses 12 (1 to n) is adjusted. As a result, the individual distribution data (IP packet) is slightly shifted, but the size thereof is very small, so that it can be synchronized between terminals without a sense of incongruity.

  In the update example 2 described above, the delivery time of a part of the delivery data is adjusted as shown in FIG. In the example of FIG. 6C, the delivery time for the receiving devices 1, 2, n-1, and n is adjusted. As a result, it is not necessary to adjust the distribution data that does not require adjustment of the distribution time, so that the readjustment processing time can be shortened, and it is possible to properly synchronize other than the receiving device close to the start and end of the distribution cycle. .

<Data example>
Here, data examples (for example, session management information and distribution time information) in the present embodiment will be described with reference to the drawings. FIG. 7 is a diagram illustrating an example of data in the present embodiment. FIG. 7A shows an example of the session management information 41. FIGS. 7B to 7D show an example of the delivery time information 42. FIGS. 7C and 7D show the delivery shown in FIG. 7B based on each update example described above. The time is re-adjusted and updated.

  The items of the session management information 41 shown in FIG. 7A include, for example, “session ID”, “session information”, “reception delay amount (ms)” corresponding to the session, etc., but are not limited thereto. It is not a thing.

  The session ID is information for identifying the receiving device 12 being accessed. The session information is information on the behavior and operation of the receiving device to which the session ID is assigned, and management of access conditions (session management). The reception delay amount stores the delay amount measured by the delay amount measuring means 22.

  Examples of the items of the distribution time information 42 shown in FIGS. 7B to 7D include “distribution order”, “session ID”, “session information”, “distribution time”, and the like, but are not limited thereto. It is not a thing. As the session ID and session information, information stored in the session management information 41 is stored. The distribution order is a content distribution order set based on the session management information 41. For example, the distribution order is set in descending order of reception delay amount, but is not limited thereto. The distribution time is a distribution time when the start time of the distribution cycle is 0.0 ms.

Below, the specific example of the update examples 1 and 2 mentioned above is demonstrated using the data example of FIG. 7B to 7D, as an example, the time required for the content distribution server 11 to issue an IP packet to each receiving device 12 is L = 1 ms, and the distribution cycle t _{c is} 33 ms. Also, as an example, the total sum of empty intervals in the distribution cycle (corresponding to equation (1)) = 20 ms, and s _f + s _b = 2 ms.

  In addition, based on the reception delay amount of the session management information 41 described above, the IP packet is distributed in the order of “ID5” → “ID2” → “ID3” → “ID1” → “ID4” → “ID0”. Shall.

FIG. 7B shows an example of setting the delivery time according to the conventional method. For reference, the transmission interval (empty interval d (ms)) of the IP packet with respect to each receiving device 12 is also shown. First, from FIG. 7A, an ideal delivery time for each session is calculated. Specifically, for example, a difference in reception delay amount in each session may be calculated with respect to the distribution target time t _def = 50 ms. Therefore, for example, in session 0, t ₀ = t _def −6 = 44 ms. The delivery time can be similarly determined for other sessions.

Here, assuming that the distribution target time t _def = 50 ms after the start time (for example, 9:00:00) of the distribution cycle, the session ID 5 is distributed as the above-mentioned s _f due to the reception delay amount in FIG. 7A. Distribution is not possible within the period (FIG. 7B). Further, since the distribution cycle t _c = 33 ms, the session ID 0 becomes the s _b target described above and cannot be distributed within the distribution cycle due to the reception delay amount in FIG. 7A (FIG. 7B). As a result, only the session IDs 1 to 4 can be distributed. When the session IDs 1 to 4 are in descending order, the session IDs are ID2, ID3, ID1, and ID4. Since the session ID 2 with the first distribution order has a reception delay amount of 48.0 ms, the empty interval d ₁ can be obtained as t _def −48.0 ms = 2 ms.

Next, the second session ID 3 in the distribution order has a reception delay amount of 44.0 ms and the distribution end time of the session ID 2 is t ₁ + L = 3 ms, so the empty interval d ₂ is t ₂ -3 ms = 3 ms. Can be sought. The other d can be similarly obtained.

The example of FIG. 7C shows the distribution time information 42 updated by the update example 1 described above. In the example of FIG. 7B, since session ID 5 and session ID 0 cannot be distributed, the number of receiving devices corresponding to s _f m _f = 1, the number of receiving devices corresponding to s _b m _b = 1, and s _f + s _b = 2 ms.

  Therefore, in the update example 1, all the distribution times of the session IDs 0 to ID5 are readjusted by applying the above-described formula (2), and updated to the distribution times shown in FIG. As a result, the IP packet can be distributed to all the receiving devices 12 within the distribution cycle.

The example of FIG. 7D shows the distribution time information 42 updated by the update example 2 described above. As described above, in the example of FIG. 7B, since session ID 5 and session ID 0 cannot be distributed, m _f = 1, m _b = 1, and s _f + s _b = 2 ms.

  Therefore, the update time of only the session ID 5 and the session ID 0 is adjusted by applying the update example 2 described above, and updated to the distribution time shown in FIG. As a result, the IP packet can be distributed to all the receiving devices 12 within the distribution cycle. Note that whether to use update example 1 or update example 2 described above may be set in advance by the user, for example, depending on the content to be distributed and the priority between the receiving devices 12. Good.

<Execution program>
Here, the content distribution server 11 and the receiving device 12 described above include, for example, a volatile storage device such as a CPU (Central Processing Unit) and a RAM (Random Access Memory), and a nonvolatile storage device such as a ROM (Read Only Memory). Further, it can be configured by a computer including an input device such as a mouse, a keyboard, and a pointing device, a display device for displaying images and data, and an interface device for communicating with the outside.

  Therefore, the above-described functions of the content distribution server 11 and the receiving device 12 can be realized by causing the CPU to execute a program describing these functions. These programs can also be stored and distributed in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory.

  That is, the content distribution process can be realized by generating an execution program (content distribution program) for causing the computer to execute the processes in the above-described configurations and installing the program in, for example, a general-purpose PC or server. it can.

<Content distribution processing (first embodiment: update example 1)>
FIG. 8 is a flowchart showing a first embodiment of content distribution processing. In the first embodiment, processing corresponding to the update example 1 described above is shown. In the example of FIG. 8, the content distribution server 11 receives a connection request from one or a plurality of receiving devices 12 (S01), and establishes a session with the receiving device 12 (S02).

  Next, the content distribution server 11 assigns a session ID to each established session and stores it in the session management information of the storage unit 40 (S03). Next, the content distribution server 11 transmits a delay amount confirmation request to the reception device 12 (S04), measures the RTT from the reception result, obtains the reception delay amount with the reception device 12 from the measurement result, and obtains the session. Stored in the management information 41 (S05).

Next, the content distribution server 11 refers to the session management information 41, calculates the distribution order based on the reception delay amount, and the distribution time based on the distribution order, and stores them in the distribution time information 42 (S06). Here, the content distribution server 11 determines that “s _f + s _b > 0 from the relationship between the time s _f that protrudes before the start time of the distribution cycle and the time s _b that protrudes after the end time of the distribution cycle. Is determined (S07), and if “s _f + s _b > 0” (YES in S07), the sum of the empty intervals within the distribution cycle as shown in the above equation (1) ( In this case, it is determined whether or not the condition “Σd ≧ s _f + s _b ” is satisfied (S08).

When the condition of “Σd ≧ s _f + s _b ” is not satisfied (NO in S08), the content distribution server 11 sets t _n of the distribution time information 42 as the first distribution time t ₁ = t _def , The delivery time is updated to t _n = t _n-1 + L for the delivery data that falls within t _c in ascending order from the first delivery order. Alternatively, t _n = t _def + t _c −L, and other distribution times are updated to t _n = t _n−1 + L by the amount of distribution data that falls within t _c in descending order from the distribution order n (S09). In the process of S09, the update is performed only for the distribution data that fits the front or rear distribution data that does not fit in the distribution cycle. Note that “t ₁ = t _def ” described above means that t ₁ is set based on t _def . Therefore, for example, as shown in FIG. 7C and the like, the delivery time t ₁ of the receiving device 12 corresponding to the first session ID is set based on t _def with reference to the delivery start time.

In addition, when the condition of “Σd ≧ s _f + s _b ” is satisfied (YES in S08), the content distribution server 11 determines whether the condition of “s _f > 0” is satisfied (S10). When the condition of “s _f > 0” is satisfied (YES in S10), the content distribution server 11 sets the first distribution time t ₁ to t ₁ = t _def (S11), and the distribution time to other receiving devices 12 t _n is updated using the above-described equation (2) (S12). Further, when the condition of “s _f > 0” is not satisfied (NO in S10), the content distribution server 11 updates all to t _n = t _def + t _c −L (S13).

If the condition of “s _f + s _b > 0” is not satisfied in the process of S07 (NO in S07), the content distribution server 11 refers to the distribution time information 42 after the process of S09, S12, or S13, Content (IP packet corresponding to the distribution cycle) is distributed in the set distribution order and distribution time (S14).

  Next, the content distribution server 11 determines whether or not to end the distribution (S15). When the distribution is not ended (NO in S15), the process returns to S04. Note that the process of S04 is always performed immediately after the start of connection, and does not necessarily have to be performed every time in the subsequent loop process. For example, it may be performed at an arbitrary timing or periodically.

  Further, when the content distribution server 11 ends the distribution (YES in S15), for example, the content distribution server 11 receives a disconnection request from the receiving device 12 and ends the distribution (S16). Further, the content distribution server 11 deletes the record of the session management information 41 and the distribution time information 42 of the session that has received the disconnection request (S17), and ends the process.

  In the above-described processing of S15 to S17, for example, when a session is established with a plurality of receiving devices 12, and there is a disconnection request from one of the receiving devices 12, all the receiving devices 12 are set. However, in this case, as shown in the process of S17, the record in the session management information 41 and the distribution time information 42 of the session that has received the disconnection request is deleted. The

<Content distribution processing (second embodiment: update example 2)>
FIG. 9 is a flowchart showing a second embodiment of the content distribution process. In the second embodiment, processing corresponding to the update example 2 described above is shown. In the example of FIG. 9, the content distribution server 11 receives a connection request from one or a plurality of receiving devices 12 (S21), and establishes a session with the receiving device 12 (S22). Next, the content distribution server 11 assigns a session ID to each established session and stores it in the session management information 41 of the storage means 40 (S23).

  Next, the content distribution server 11 transmits a delay amount confirmation request to the reception device 12 (S24), measures the RTT from the reception result, obtains the reception delay amount with the reception device 12 from the measurement result, and obtains the session. Stored in the management information 41 (S25).

Next, the content distribution server 11 refers to the session management information 41, calculates the distribution order based on the reception delay amount and the distribution time based on the distribution order, and stores them in the distribution time information 42 (S26). Here, the content distribution server 11 determines whether or not the condition of “s _f > 0” is satisfied (S27). If the condition of “s _f > 0” is satisfied (YES in S27), then the above-mentioned Whether or not the condition of “Σd ≧ s _f ” is satisfied is determined from the relationship with the sum of the empty intervals in the distribution cycle as shown in the expression (1) (here, expressed as “Σd”) (S28). ).

When the content distribution server 11 does not satisfy the condition of “Σd ≧ s _f ” (NO in S28), t _n of the distribution time information 42 is set to the first distribution time t ₁ = t _def and other distribution times Is updated to t _n = t _n-1 + L by the amount of distribution data that falls within t _c in ascending order from the first distribution order (S29). In other words, the subsequent packets that cannot be delivered are discarded. When the condition of “Σd ≧ s _f ” is satisfied (YES in S28), the content distribution server 11 sets t _n of the distribution time information 42 to t ₁ = t _def and sets t ₂ to t _f to t _n. = T _n-1 + L is updated (S30).

Here, in the process of S27, when the condition of “s _f > 0” is not satisfied (NO in S27), the content distribution server 11 satisfies the condition of “s _b > 0” after the process of S29 or S30. Whether or not (S31). When the condition of “s _b > 0” is satisfied (YES in S31), it is next determined whether or not the condition of “Σd ≧ s _b ” is satisfied (S32). When the condition of “Σd ≧ s _b ” is not satisfied (NO in S32), t _n of the distribution time information 42 is set to the last distribution time t _n = t _def + t _c −L, and other distribution times are distribution. only distribution data content fits into _{t c} of order n-th in descending order is updated to _{t n = t n-1 +} L (S33). That is, the previous packet that cannot be delivered is discarded. Further, when the condition of “Σd ≧ s _b ” is satisfied (YES in S32), the content distribution server 11 updates t _b to t _{n −1} of the distribution time information 42 with t _n = t _n−1 + L. (S34).

  Next, the content distribution server 11 refers to the distribution time information 42 and distributes the content (IP packet corresponding to the distribution cycle) in the set distribution order and distribution time (S35).

  Next, the content distribution server 11 determines whether or not to end the distribution (S36). If the distribution is not ended (NO in S36), the process returns to S24. Note that the process of S24 is always performed immediately after the start of connection, and does not necessarily have to be performed every time in the subsequent loop process. For example, it may be performed at an arbitrary timing or periodically.

  In addition, when the content distribution server 11 ends the distribution (YES in S36), for example, the content distribution server 11 receives a disconnection request from the receiving device 12 and ends the distribution (S37). Further, the content distribution server 11 deletes the record of the session management information 41 and the distribution time information 42 of the session that has received the disconnection request (S38), and ends the process.

  As described above, according to the present embodiment, it is possible to suppress variations in the arrival time of content distributed to each receiving device 12 connected to the content distribution server 11. Further, it is possible to perform push distribution without generating the receiving device 12 that cannot be distributed.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be changed.

DESCRIPTION OF SYMBOLS 10 Content distribution system 11 Content distribution server 12 Receiving device 13 Communication network 20, 50 Control means 21, 51 Session control means 22 Delay amount measurement means 23 Content generation means 24 Distribution time setting means 25 Content transmission means 30, 60 Communication means 40 Storage Means 41 Session management information 42 Distribution time information 52 Program acquisition means (first information acquisition means)
53 Content acquisition means (second information acquisition means)
54 Display means

Claims (4)

For each receiving apparatus connected via a communication network, the content delivery server for delivering content to be displayed to the each receiving device at a predetermined delivery period,
Session control means for receiving a connection request from each receiving device and establishing a session with each receiving device;
Before delivering the content to the receiving device to establish a session by the session control unit, the performs delay confirmation request to each reception device, wherein the receiving device based on the response information in response to said delay amount confirmation request A delay amount measuring means for measuring the reception delay amount,
Using the reception delay amount of each receiving device obtained by the delay amount measuring means, the content reaches another receiving device in accordance with the time when the content reaches the receiving device having the largest receiving delay amount. If the distribution time for each of the receiving devices is set, and the set distribution time is before the start time of the predetermined distribution cycle or after the end time of the predetermined distribution cycle, the distribution is performed. Distribution time setting means for updating the time within the predetermined distribution cycle ;
A content distribution server comprising: content transmission means for transmitting the content to each receiving device based on the distribution time obtained by the distribution time setting means. The delivery time setting means includes:
Delivery time obtained using the reception delay amount, before the start time of the predetermined delivery period, or, if later than the end time of the predetermined delivery period, all of the receiving apparatuses to be distributed The content distribution server according to claim 1, wherein the distribution time is updated. The delivery time setting means includes:
Delivery time obtained using the reception delay amount, before the start time of the predetermined delivery period, or, if later than the end time of the predetermined delivery period, updating only the distribution time The content distribution server according to claim 1, wherein: The content delivery program for functioning a computer as each means which the content delivery server of any one of Claims 1 thru | or 3 has.

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