JP2013141138A - Distribution device, distribution method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which when moving image data is intermittently transmitted to a terminal in consideration of the bit rate of the moving image data, a buffer amount in the terminal cannot be appropriately controlled.SOLUTION: A distribution device comprises: estimation means that estimates a buffer amount in a terminal which receives distributed data; and adjustment means that adjusts a transmission time of the data and a transmission amount of the data on the basis of the estimated buffer amount.

Description

  The present invention relates to a distribution apparatus, a distribution method, and a program for distributing data via a network.

  In recent years, with the speeding up of networks, moving image distribution services have begun to spread in earnest. In addition to moving image distribution via wired networks at home and offices, the proportion of viewing via moving image distribution via wireless networks is also rapidly increasing due to the emergence of small and highly functional terminals such as smartphones. . As a result, the traffic due to the voice communication and the data communication exceeds the traffic, and the traffic due to the moving image viewing is a major factor causing the congestion of the network.

  Normally, RTSP (Real Time Streaming Protocol) is used to distribute moving images via the Internet, but RTSP traffic is allowed to pass through a server that exists at a relay point such as a proxy or firewall. Often not.

  Therefore, as described in Non-Patent Document 1, a technique for distributing moving images is widely used by HTTP (Hyper Text Transfer Protocol) widely used for browsing home pages and the like.

  In moving image distribution by HTTP, data is transmitted at a speed determined by TCP (Transport Control Protocol), which is a lower layer transmission protocol. If all the moving image data is distributed at once without considering the bit rate of the moving image data, the moving image data is distributed at a speed higher than the speed at which the moving image is reproduced on the receiving side in a network with high throughput. Problems arise. Non-Patent Document 1 discloses a technique for intermittently distributing moving images in consideration of the bit rate of moving image data in moving image distribution using HTTP.

  Furthermore, Patent Literature 1 and Patent Literature 2 can be cited as technologies related to data distribution via a network.

  Patent Document 1 discloses that a packet transmission interval is adjusted based on data characteristics and data communication characteristics for the purpose of reducing distribution data transmission errors.

  Also, in Patent Document 2, a tuner (transmission side) capable of wireless communication with a display (reception side) estimates the remaining time of the video buffer of the display, and distributes based on the estimated remaining time and the wireless band. Controlling the content bit rate of data is disclosed.

JP 2009-049529 A JP 2011-0099904 A

Kevin J. et al. Ma, et al, “Mobile Video Delivery with HTTP”, IEEE Communications Magazine, pp. 166-175, April 2011

  As described above, transmitting a large amount of data in a short time without considering the bit rate of moving image data causes network congestion. Furthermore, since the receiving terminal receives a large amount of data in advance, if the user stops viewing halfway, the moving image data after the stop is wasted. Therefore, it cannot be said that the network is used efficiently.

  On the other hand, in Non-Patent Document 1, moving image distribution is performed in consideration of the bit rate of moving image data. In Non-Patent Document 1, when a temporary decrease in throughput occurs due to network congestion, network transmission path error, or the like, when the distribution of moving image data is not in time for the terminal playback time, , Playback of moving images stops on the terminal side.

  As a method for preventing the reproduction stop due to the reduction in throughput, it is common to buffer moving image data on the terminal side. However, if the video data is excessively buffered on the terminal side, a delay in starting reproduction on the terminal side and a decrease in network utilization efficiency are caused. Also, it is necessary to consider the amount of buffered moving image data determined by the hardware restrictions of the terminal.

  Therefore, in consideration of the bit rate of moving image data, when the moving image data is intermittently transmitted to the terminal, the buffer amount in the terminal cannot be appropriately controlled.

  An object of the present invention is to provide a communication device, a communication system, a communication method, and a communication program that can solve the above-described problems.

  The distribution apparatus according to the present invention includes an estimation unit that estimates a buffer amount of a terminal that receives data to be distributed, and an adjustment unit that adjusts the transmission time of the data and the transmission amount of the data based on the estimated buffer amount. And.

  A distribution method according to the present invention is a distribution method for distributing data via a network, estimating a buffer amount of a terminal that receives data to be distributed, and based on the estimated buffer amount, The transmission amount of the data is adjusted.

  A program according to the present invention is a program that distributes data via a network, a process for estimating a buffer amount of a terminal that receives data to be distributed, and a transmission time of the data based on the estimated buffer amount. And a process of adjusting a transmission amount of the data.

  According to the present invention, it is possible to appropriately control the buffer amount of the data distribution destination.

It is a figure which shows the structural example of the communication system by 1st Embodiment. It is a figure which shows the structural example of the origin server 130 by 1st Embodiment. It is a flowchart which shows the flow of operation | movement by 1st Embodiment. It is a figure which shows the relationship between terminal buffer amount and time in 1st Embodiment. It is a figure which shows the change of the target buffer amount in 1st Embodiment. It is a figure which shows the structural example of the origin server 130 by 2nd Embodiment. It is a figure which shows the relationship between the amount of terminal buffers, and time in 2nd Embodiment. It is a figure which shows the structural example of the delivery apparatus 1000 by 4th Embodiment. It is a flowchart which shows the flow of operation | movement by 4th Embodiment.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration example of a communication system according to a first embodiment of the present invention. The communication system in FIG. 1 includes two networks, a core network 110 and a mobile network 120.

  The communication system of FIG. 1 shows an example in which data such as moving images stored in the origin server 130 is distributed to a personal computer 131, a personal computer 132, a mobile terminal 141, a mobile terminal 142, and the like. The data to be distributed is not limited to moving images, but may be only images, only sounds, or other various data. Below, the origin server 130 demonstrates as what delivers moving image data. Hereinafter, the personal computer 131, the personal computer 132, the mobile terminal 141, and the mobile terminal 142, which are data distribution destinations, are collectively referred to as “terminals”.

  The core network 110 includes a core router 111, an edge router 112, an edge router 113, an edge router 114, and an edge router 115. The core network 110 includes a cache server 116.

  The mobile network 120 includes an edge router 114, a cache server 121, a base station 122, and a base station 123.

  FIG. 2 shows an example of the configuration of the origin server 130. In the communication system of FIG. 1, it may be considered that the cache server 116 and the cache server 121 cache and distribute the data stored in the origin server 130. In this case, the cache server 116 and the cache server 121 may have the same configuration as the origin server 130 shown in FIG.

  According to FIG. 2, the origin server 130 includes an estimation unit 131, an adjustment unit 132, a monitoring unit 133, a determination unit 134, and a transmission unit 135. Hereinafter, the operation of each unit of the origin server 130 will be described with reference to the flowchart shown in FIG.

  First, the adjustment unit 132 sets a data transmission cycle T (seconds) and a target terminal buffer amount Bt (seconds) as initial settings (S201). Specifically, for example, values of T = 2 seconds and Bt = 20 seconds are set. The data transmission cycle T is a cycle for transmitting data in a normal state. The adjustment unit 132 divides the moving image data to be distributed every T seconds and transmits it every T seconds.

  Here, it is assumed that the moving image data distributed by the origin server 130 is a file stored in a format in which video and audio are multiplexed. Also, it is assumed that the data position corresponding to the reproduction time on the medium can be known in byte units. Normally, the data size for T seconds of moving image data is not constant for each section.

  Furthermore, considering the data transmission time required for the data transmitted from the server to arrive at the terminal, the transmission start time can be advanced by that time. The data transmission time can be calculated by dividing the data size by the network throughput. For example, when the data size is 100 Kbytes and the throughput is 1 Mbps (bit per second), the data transmission time is 100 × 8 ÷ 1000 = 0.8 seconds.

  The target terminal buffer amount Bt is a target value of a time obtained by subtracting the time that the terminal has already reproduced from the total time length of the moving image data that has been received by the terminal, that is, the time of the unreproduced portion of the data received on the terminal side is there.

  The buffer provided in the terminal is used to prevent the reproduction from being stopped when the network throughput decreases. The larger the buffer amount, the more it can withstand a reduction in transmission throughput for a long time, but there is also a drawback that it takes time to start reproduction. Further, the maximum value of the buffer amount is restricted by hardware factors such as the amount of memory installed in the terminal.

  Next, the transmission unit 135 transmits data to be distributed (S202). First, the transmission unit 135 transmits data corresponding to the target terminal buffer amount Bt (seconds) in the initial data transmission period. Thereafter, the transmission unit 135 transmits T (second) data from the top of the moving image file every T seconds. FIG. 4 shows the relationship between the amount of moving image data buffer in the terminal and time. Here, TCP (Transmission Control Protocol) is used as the data transmission protocol. In addition, the size of the transmitted data is set as a transmission data amount D (bytes).

  Subsequently, the transmission unit 135 calculates a data transmission rate (S203). Specifically, the transmission unit 135 calculates the data transmission rate R (bytes / second) by dividing the transmission data amount D (bytes) by the time required for data transfer.

  The time required for data transfer may be limited by the measurement method due to implementation restrictions, but in the case of TCP transfer, the time from the start of transmission until the end of transmission, or from the terminal The time until the reception of an ACK packet, which is a notification of completion of reception.

  Next, the estimation unit 131 performs calculation for estimating the buffer amount of the terminal (S204). The estimated terminal buffer amount Be (second), which is an estimated value of the buffer amount accumulated in the terminal, is reproduced on the terminal side from the transmitted moving image time Ts (second) that is the time length of the transmitted moving image data. It is calculated by subtracting the terminal-side moving image reproduction time Tr (seconds) that is the time of the moving image.

  The terminal-side moving image playback time Tr is calculated by adding the elapsed time with the time when the origin server 130 transmits the first data or the time when the terminal returns the ACK for the data transmitted first as the playback start time. To do.

  Finally, the adjustment unit 132 performs data transmission control (S205).

  When the network state is good, the adjusting unit 132 controls to transmit moving image data for T seconds in a T second cycle, thereby preventing excessive use of the network. In this case, data for T seconds to be transmitted next is read from the moving image file, the data size D is acquired, and control is performed so that data is transmitted T seconds after the time when the previous data was transmitted.

  The adjustment unit 132 controls to transmit the next data immediately after the previous data transmission is completed if the previous data transmission has not been completed after T seconds.

  Thus, in a state where data cannot be transmitted at the scheduled time, the data transmission rate R is a value smaller than the bit rate of the moving image data. In addition, when the estimated terminal buffer amount Be calculated by the estimated terminal buffer amount calculation decreases and the estimated terminal buffer amount Be becomes 0, reproduction at the terminal stops. In addition, the adjustment unit 132 performs adjustment so that the time corresponding to the stoppage is not added to the terminal-side moving image reproduction time Tr.

  Furthermore, the adjustment unit 132 sets the target terminal buffer amount Bt to an appropriate value as shown in FIG. 5 according to the type of network between the terminal and the server, the state of the network, the type of terminal, the bit rate of moving images, and the like. To determine the data transmission time and the data transmission amount. FIG. 5 shows a change in the buffer amount of the terminal with time. The solid line indicates the buffer amount of the terminal, and the dotted line indicates the target value of the buffer amount of the terminal.

  Here, the network information such as the type of network and the network state is acquired by the monitoring unit 133 monitoring the network. The type of terminal is determined by the determination unit 134.

  A section A in FIG. 5 is a section in which the network throughput is lower than the moving image bit rate. For this reason, the buffer amount of the terminal decreases with time. In the case of section A, the adjustment unit 132 performs control so as to increase the target value of the buffer amount in order to avoid buffer depletion of the terminal. After that, the adjustment unit 132 performs control to lower the target value when the throughput becomes stable for a certain period as in the section B.

  Also, when determining the data transmission time, the transmission time can be subtracted from the transmission time in consideration of the transmission time from when the data is transmitted until it arrives at the terminal. The transmission time is calculated by dividing the data transmission amount by the network throughput. The network throughput can also be the previous measured value, a value predicted from past measured values, or the worst predicted value. Also, the transmission time can be set to a predetermined fixed value.

  For example, if the terminal and the server are connected by a wired network, and the throughput necessary for distributing moving image data can always be secured, the target terminal buffer amount Bt is a minimum value (within about 10 seconds). To.

  On the other hand, if the wireless network exists between the terminal and the server and the throughput necessary for distributing moving image data cannot be temporarily secured, the target terminal buffer amount Bt is set to an appropriate value. Adjust by increasing to.

  It is also possible to make adjustments by determining an appropriate Bt value with respect to the past average values and dispersion values. Even if the average throughput for 30 seconds is half the bit rate of the moving image, the target buffer amount needs to be 15 seconds or more in order to prevent the reproduction from stopping.

  When the dispersion of the throughput is large, it is effective to predict that the network is unstable and the throughput is likely to decrease, and control to increase the target buffer amount is effective. Conversely, when the average value of throughput is high or the variance is small, it is effective to control so as to reduce the target buffer amount.

  Alternatively, as one of the network states, a future lower limit value or worst-case throughput may be predicted based on past throughput. By predicting the lower limit or worst value of throughput, it is also effective to set the minimum required value as the target buffer amount so that the terminal buffer will not be depleted even if the throughput actually falls to the lower limit. is there.

  Also, when increasing or decreasing the target buffer amount, rather than controlling the transmission time and transmission data amount so that it is reflected instantaneously, it takes time to approach the target value in order to suppress rapid fluctuations in the transmission rate. It is also effective to control this.

  Further, for each terminal, the maximum value of the target terminal buffer amount Bt that can be secured can be determined from the buffer amount that can be secured and the bit rate of the moving image, and control can be performed so as not to exceed that value. For example, if the buffer amount that can be secured is 1 Mbytes and the bit rate of the moving image is 250 Kbps, the maximum value of Bt is (1M × 8) / 250K = 32 seconds.

  As described above, according to the first embodiment, the buffer amount of the terminal is estimated, and the transmission time and the transmission data amount are controlled based on the buffer amount and the network state. Therefore, according to the first embodiment, it is possible to appropriately control the buffer amount of the data distribution destination. Furthermore, by performing transmission control according to the state of the network, the data delivery speed can be made as constant as possible.

  In addition, according to the first embodiment, since the buffer amount of the data distribution destination can be controlled, the distribution of moving image data is unnecessarily adversely affecting the network such as causing congestion. It is possible to prevent a large amount of moving image data from being transmitted in a short time.

  Further, according to the first embodiment, it is possible to prevent as much as possible the stop of moving image reproduction on the terminal side caused by a decrease in transmission throughput caused by network congestion or radio wave interference in a wireless network. That is, according to the first embodiment, efficient network use can be realized while improving the quality of moving images experienced by the user.

[Second Embodiment]
Next, a second embodiment will be described. Hereinafter, differences between the second embodiment and the first embodiment will be described. Each variable is the same as that defined in the first embodiment, and some variables are not used.

  FIG. 6 shows the configuration of the origin server 130 according to the second embodiment. The difference from the first embodiment is that the origin server 130 includes a buffer amount determination unit 136. Note that, similarly to the first embodiment, the cache server 116 and the cache server 121 may have the same configuration as the origin server 130 of FIG.

  The operation of the second embodiment will be described below with reference to the flowchart of FIG. First, the adjustment unit 132 sets a minimum terminal buffer amount B1 (second) and a maximum terminal buffer amount Bh (second) in addition to those described in the first embodiment as initial settings (S201). Specifically, for example, values of B1 = 40 seconds and Bh = 60 seconds are set.

  Here, the maximum terminal buffer amount Bh is the maximum value of the buffer amount restricted by hardware in the terminal. Even if a clear value is unknown, a certain assumed value is set. The minimum terminal buffer amount B1 is set to a value smaller than Bh.

  In S202, the transmission unit 135 transmits data of the maximum terminal buffer amount Bh. In S203, the data transmission rate R (bytes / second) is calculated as in the first embodiment.

  Next, in S204, an estimated terminal buffer amount Be (seconds) that is an estimated value of the buffer amount accumulated in the terminal is calculated in the same manner as in the first embodiment.

  In S205, the adjustment unit 132 obtains moving image data corresponding to the time length of Bh−Bl (seconds) at a time when Be becomes Bl so that the estimated terminal buffer amount Be does not exceed Bh and does not fall below Bl. Control to transmit intermittently. FIG. 7 shows the relationship between the estimated terminal buffer amount and time in the second embodiment.

  As described above, according to the second embodiment, the communication time and the transmission data amount are controlled based on the maximum value and the minimum value of the buffer amount of the terminal. Therefore, according to the second embodiment, it is possible to appropriately control the buffer amount of the data distribution destination.

  In addition, according to the second embodiment, since the buffer amount of the data distribution destination can be controlled, in the distribution of moving image data, it is unnecessary to adversely affect the network such as causing congestion. It is possible to prevent a large amount of moving image data from being transmitted in a short time.

  Further, according to the second embodiment, it is possible to prevent as much as possible the stop of moving image reproduction on the terminal side caused by a decrease in transmission throughput caused by network congestion or radio wave interference in a wireless network. That is, according to the second embodiment, efficient network use can be realized while improving the quality of moving images experienced by the user.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment is characterized in that the operations of the first embodiment and the second embodiment are switched according to the state of the network.

  First, as initial setting (S201) in the flowchart of FIG. 3, a target terminal buffer amount Bt (second), a minimum terminal buffer amount B1 (second), and a maximum terminal buffer amount Bh (second) are set. Specifically, for example, values of Bt = 30 seconds, B1 = 40 seconds, and Bh = 60 seconds are set.

  For example, in a state where the network is stable, the adjustment unit 132 controls the terminal buffer amount by the method of the first embodiment, and also adaptively changes the target terminal buffer amount Bt. On the other hand, when the network becomes unstable, the method is switched to the method of the second embodiment.

  In order to determine that the network state is unstable, for example, a method of determining that the network state is unstable when the average value in a certain section of the throughput measured by the server is equal to or less than a predetermined threshold value can be considered.

  According to the third embodiment, similarly to the first embodiment and the second embodiment, the buffer amount of the terminal is estimated, and based on the buffer amount and the network state, the transmission time and the transmission data amount are estimated. Is controlling. Therefore, according to the third embodiment, it is possible to appropriately control the buffer amount of the data distribution destination.

  In addition, according to the third embodiment, since the buffer amount of the data distribution destination can be controlled, in the distribution of moving image data, it is unnecessary to adversely affect the network such as causing congestion. It is possible to prevent a large amount of moving image data from being transmitted in a short time.

  Further, according to the third embodiment, it is possible to prevent as much as possible the stop of moving image reproduction on the terminal side caused by a decrease in transmission throughput caused by network congestion or radio wave interference in a wireless network. That is, according to the second embodiment, efficient network use can be realized while improving the quality of moving images experienced by the user.

  Furthermore, by adaptively switching between the method of the first embodiment that places importance on making the distribution speed as constant as possible and the method of the second embodiment that places importance on avoiding stoppage of moving image playback, the network It is possible to efficiently reduce the load and the degradation of moving image quality.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 8 is a diagram illustrating a configuration of a distribution apparatus 1000 according to the fourth embodiment. The distribution apparatus 1000 in FIG. 8 distributes data to terminals not shown.

  According to FIG. 8, the distribution apparatus 1000 includes an estimation unit 1001 and an adjustment unit 1002.

  FIG. 9 is a flowchart showing an example of the operation according to the fourth embodiment. First, the estimation means 1001 estimates the buffer amount of the terminal that receives data (S1001). Next, the adjusting unit adjusts the data transmission time and the data transmission amount based on the estimated buffer amount (S1002).

  As described above, according to the fourth embodiment, the buffer amount of the terminal is estimated, and the transmission time and the transmission data amount are controlled based on the estimated buffer amount. Therefore, according to the fourth embodiment, it is possible to appropriately control the buffer amount of the data distribution destination.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  Further, a part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
An estimation means for estimating a buffer amount of a terminal that receives data to be distributed;
Adjusting means for adjusting the transmission time of the data and the transmission amount of the data based on the estimated buffer amount;
A distribution apparatus comprising:

(Appendix 2)
The distribution device further includes:
Monitoring means for monitoring the state of the network;
Discrimination means for discriminating the type of the terminal;
With
The adjusting means further includes:
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The distribution apparatus according to attachment 1, wherein the distribution apparatus is characterized in that

(Appendix 3)
The distribution device further includes:
A buffer amount determining means for determining a maximum buffer amount and a minimum buffer amount for accumulating the data in the buffer of the terminal using at least one of the network state, the terminal type, and the bit rate of the data; ,
If the estimated buffer amount is less than the minimum buffer amount, transmitting means for transmitting data corresponding to an amount obtained by subtracting the minimum buffer amount from the maximum buffer amount;
The distribution device according to attachment 2, further comprising:

(Appendix 4)
The transmitting means further includes
The distribution according to claim 3, wherein the data is intermittently transmitted so that a data amount stored in the buffer of the terminal does not exceed the maximum buffer amount and does not fall below the minimum buffer amount. apparatus.

(Appendix 5)
A distribution method for distributing data over a network,
Estimate the buffer capacity of the terminal that receives the data to be distributed,
The distribution method, wherein the transmission time of the data and the transmission amount of the data are adjusted based on the estimated buffer amount.

(Appendix 6)
The delivery method further includes:
Monitor the status of the network;
Determine the type of terminal,
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The distribution method according to supplementary note 5, wherein:

(Appendix 7)
The delivery method further includes:
Using at least one of the state of the network, the type of the terminal, and the bit rate of the data, the maximum buffer amount and the minimum buffer amount for storing the data in the buffer of the terminal are determined,
The distribution method according to appendix 6, wherein if the estimated buffer amount is less than the minimum buffer amount, data corresponding to an amount obtained by subtracting the minimum buffer amount from the maximum buffer amount is transmitted.

(Appendix 8)
The delivery method further includes:
The distribution according to appendix 7, wherein the data is intermittently transmitted so that the data amount stored in the buffer of the terminal does not exceed the maximum buffer amount and does not fall below the minimum buffer amount. Method.

(Appendix 9)
A program for distributing data over a network,
A process for estimating the buffer capacity of the terminal receiving the data to be distributed;
A process of adjusting the transmission time of the data and the transmission amount of the data based on the estimated buffer amount;
A program that causes a computer to execute.

(Appendix 10)
The program further includes:
Processing for monitoring the state of the network;
Processing to determine the type of the terminal;
Including
The adjusting process further includes:
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The program according to appendix 9, characterized by:

(Appendix 11)
The program further includes:
A process of determining a maximum buffer amount and a minimum buffer amount for storing the data in the buffer of the terminal using at least one of the network state, the terminal type, and the bit rate of the data;
If the estimated buffer amount is less than the minimum buffer amount, a process of transmitting data corresponding to an amount obtained by subtracting the minimum buffer amount from the maximum buffer amount;
The program according to appendix 10, characterized by including:

(Appendix 12)
The program further includes:
A process of intermittently transmitting the data so that the amount of data stored in the buffer of the terminal does not exceed the maximum buffer amount and does not fall below the minimum buffer amount;
The program according to appendix 11, characterized by including:

DESCRIPTION OF SYMBOLS 110 Core network 111 Core router 112, 113, 114, 115 Edge router 116, 121 Cache server 120 Mobile network 122, 123 Base station 131, 132 Personal computer 141, 142 Mobile terminal 1000 Distribution apparatus 1001 Estimation means 1002 Adjustment means

Claims (10)

An estimation means for estimating a buffer amount of a terminal that receives data to be distributed;
Adjusting means for adjusting the transmission time of the data and the transmission amount of the data based on the estimated buffer amount;
A distribution apparatus comprising: The distribution device further includes:
Monitoring means for monitoring the state of the network;
Discrimination means for discriminating the type of the terminal;
With
The adjusting means further includes:
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The distribution apparatus according to claim 1. The distribution device further includes:
A buffer amount determining means for determining a maximum buffer amount and a minimum buffer amount for accumulating the data in the buffer of the terminal using at least one of the network state, the terminal type, and the bit rate of the data; ,
If the estimated buffer amount is less than the minimum buffer amount, transmitting means for transmitting data corresponding to an amount obtained by subtracting the minimum buffer amount from the maximum buffer amount;
The distribution apparatus according to claim 2, further comprising: The transmitting means further includes
The data is intermittently transmitted so that the amount of data stored in the buffer of the terminal does not exceed the maximum buffer amount and does not fall below the minimum buffer amount. Distribution device. A distribution method for distributing data over a network,
Estimate the buffer capacity of the terminal that receives the data to be distributed,
The distribution method, wherein the transmission time of the data and the transmission amount of the data are adjusted based on the estimated buffer amount. The delivery method further includes:
Monitor the status of the network;
Determine the type of terminal,
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The distribution method according to claim 5. The delivery method further includes:
Using at least one of the state of the network, the type of the terminal, and the bit rate of the data, the maximum buffer amount and the minimum buffer amount for storing the data in the buffer of the terminal are determined,
The distribution method according to claim 6, wherein if the estimated buffer amount is less than the minimum buffer amount, data corresponding to an amount obtained by subtracting the minimum buffer amount from the maximum buffer amount is transmitted. The delivery method further includes:
The data is intermittently transmitted so that the amount of data stored in the buffer of the terminal does not exceed the maximum buffer amount and does not fall below the minimum buffer amount. Delivery method. A program for distributing data over a network,
A process for estimating the buffer capacity of the terminal receiving the data to be distributed;
A process of adjusting the transmission time of the data and the transmission amount of the data based on the estimated buffer amount;
A program that causes a computer to execute. The program further includes:
Processing for monitoring the state of the network;
Processing to determine the type of the terminal;
Including
The adjusting process further includes:
In addition to the estimated buffer amount, the data transmission time and the data transmission amount are adjusted based on at least one of the network state, the terminal type, and the data bit rate. The program according to claim 9.

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