JP4931093B2 - Delivery speed control device, delivery speed control method, and delivery speed control program - Google Patents

Description

  The present invention relates to a technical field such as a distribution system including a distribution source device that distributes distribution information such as content data by, for example, a streaming method and a distribution destination device that receives the distribution information.

  In this type of distribution system, when content data is distributed from a distribution server that is a distribution source device to a client that is a distribution destination device, for example, by a streaming method, a certain amount of data is accumulated (stored) in the buffer memory in the client. At this time, the reproduction of the content data is started, and constant data is always accumulated in the buffer memory (see, for example, Patent Document 1). This is to absorb the influence of fluctuations in the transmission speed of the communication line connecting the distribution source device and the distribution destination device.

JP 2003-169089 A

  However, in the conventional distribution system, when the communication line is congested, it takes time to store data in the buffer memory, and it takes time until the reproduction of the content data is started, which is preferable for the user. Absent. In particular, when there are many streaming channels, it is assumed that the user will first watch various channels and then settle down to one channel. In such a case, a sufficient amount of data is stored in the buffer memory each time. (Buffering) is not convenient for the user.

  On the other hand, if the amount of data stored in the buffer memory is reduced, the time until reproduction is shortened, but the problem is that reproduction is likely to be affected by fluctuations in transmission speed and reproduction is stopped.

  The present invention has been made in view of the above problems and the like, and is a distribution speed that can shorten the time until reproduction of distributed distribution information without being affected by fluctuations in the transmission speed of a communication line. It is an object to provide a control device, a distribution system, a distribution speed control method, and a distribution speed control program.

In order to solve the above-mentioned problem, the invention of the delivery speed control device according to claim 1 is a delivery source device that delivers delivery information to be delivered, and a delivery destination device that receives delivery of the delivery information. A distribution destination device that includes storage means for temporarily storing distributed distribution information, and that controls a distribution speed of the distribution information from the distribution source device to the distribution destination device. In the speed control device, at a timing of changing the delivery speed based on the accumulated amount of the delivery information in the storage means, in a range equal to or higher than the reproduction output speed of the delivery information delivered to the delivery destination device. , a speed control means for changing the delivery speed, when the storage amount in the storage means becomes a first storage amount, playback to start playback output of the distribution information Comprising a control means, wherein the speed control means, said case storage amount is smaller than the first accumulation amount, the delivery speed is controlled to be faster first delivery rate than the reproduction output speed, the storage If the amount is greater than or equal to the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed and the reproduction output A second delivery speed that is faster than the second delivery speed , and a second delivery speed that cancels fluctuations in transmission speed in a communication line connecting the delivery source device and the delivery destination device. When the amount is equal to or greater than the second accumulation amount, the distribution speed is controlled to be a third distribution speed that follows the reproduction output speed.

According to the present invention, the distribution destination apparatus to delivered the destination range of more reproduction output speed in the device of distribution information, have rows speed control to change the delivery speed based on the accumulated amount of the distribution information, storage means Since the reproduction output of the distribution information is started when the storage amount in the first storage amount becomes the first storage amount, the distribution information can be reproduced without being affected by the fluctuation in the transmission speed of the communication line. Can be shortened. Further, when the storage amount of the storage means is smaller than the first storage amount, the distribution speed is controlled to be a first distribution speed faster than the reproduction output speed, the storage amount is equal to or higher than the first storage amount, and When less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is a second delivery speed that is slower than the first delivery speed and faster than the reproduction output speed, and the delivery source device and the Control is made so that the second delivery speed cancels the fluctuation in the transmission speed on the communication line connecting the delivery destination device . Further, when the accumulation amount is equal to or greater than the second accumulation amount, the delivery speed follows the reproduction output speed. Since the third delivery speed is controlled to be controlled, the time for delivering the delivery information at the first delivery speed can be shortened, and the burden on the delivery source apparatus can be reduced.
Further, according to the present invention, it is possible to shorten the time for distributing the distribution information at the first distribution speed, and therefore it is possible to reduce the burden on the distribution source device. Also, a distribution source device having a higher distribution speed than other distribution source devices can be efficiently used in many distribution destination devices. Furthermore, a distribution source device group having a higher distribution speed than other distribution source device groups can be efficiently used in many distribution destination devices, and one distribution source device in the distribution source device group stops functioning. Even when (down), the distribution information can be reproduced and output without being affected by the influence.

According to a second aspect of the present invention, there is provided a delivery speed control method comprising: a delivery source device that delivers delivery information to be delivered; and a delivery destination device that receives delivery of the delivery information. A distribution speed control device for controlling a distribution speed of the distribution information from the distribution source device to the distribution destination device. In the method, the timing of changing the delivery speed based on the storage amount of the delivery information in the storage means in a range equal to or higher than the reproduction output speed of the delivery information delivered to the delivery destination device in the delivery destination device. A speed control step for changing the delivery speed, and a playback control process for starting playback output of the delivery information when the storage amount in the storage means reaches the first storage amount. In the speed control step, when the accumulated amount is smaller than the first accumulated amount, the delivery speed is controlled to be a first delivery speed faster than the reproduction output speed, and the accumulated amount Is equal to or greater than the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed, and the reproduction output speed Control is performed so that the second delivery speed is higher than the second delivery speed, and the second delivery speed cancels out the fluctuation of the transmission speed in the communication line connecting the delivery source device and the delivery destination device. When the amount is greater than or equal to the second accumulation amount, the distribution speed is controlled to be a third distribution speed that follows the reproduction output speed .

Further, the invention of the distribution speed control program according to claim 3 is a distribution source device that distributes distribution information to be distributed, and a distribution destination device that receives distribution of the distribution information. Included in a distribution system including a storage unit that temporarily stores data, and included in a distribution speed control device that controls a distribution speed of the distribution information from the distribution source device to the distribution destination device. In the range above the reproduction output speed of the distribution destination device of the distribution information distributed to the distribution destination device at a timing of changing the distribution speed based on the amount of distribution information stored in the storage means to the computer, A speed control step for changing the delivery speed, and when the accumulation amount in the accumulation means becomes the first accumulation amount, the reproduction output of the distribution information is started. A raw control step, and in the speed control step, when the accumulation amount is smaller than the first accumulation amount, the delivery speed is controlled to be a first delivery speed faster than the reproduction output speed. When the accumulation amount is equal to or greater than the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed, and The second delivery speed is higher than the reproduction output speed, and is controlled to be a second delivery speed that cancels a change in transmission speed in a communication line connecting the delivery source apparatus and the delivery destination apparatus, and When the accumulation amount is equal to or greater than the second accumulation amount, the distribution speed is controlled to be a third distribution speed that follows the reproduction output speed .

  According to the present invention, the speed control is performed to change the distribution speed based on the accumulated amount of the distribution information in a range equal to or higher than the reproduction output speed in the distribution destination apparatus of the distribution information distributed to the distribution destination apparatus. Therefore, it is possible to reduce the time until reproduction of the distributed distribution information without being affected by fluctuations in the transmission speed of the communication line.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. In addition, each embodiment described below is an embodiment when the present invention is applied to a content distribution system.

(I) First Embodiment First, a content distribution system according to a first embodiment of the present invention will be described.

  First, the configuration and function of the content distribution system in the first embodiment will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system according to the first embodiment, FIG. 2 is a block diagram illustrating a schematic configuration example of a distribution server, and FIG. 3 is a schematic configuration example of a terminal device. FIG.

  As shown in FIG. 1, a content distribution system as a distribution system includes a distribution server 1 as a distribution source device that distributes content (for example, content such as movies and music pieces) data as distribution information to be distributed, and the content And a terminal device (client) 2 serving as a distribution destination device that receives data distribution, and an IP (Internet Protocol) address is assigned to each of the distribution server 1 and the terminal device 2. Are connected to each other via a network 3 such as the Internet.

  As shown in FIG. 2, the distribution server 1 includes a storage unit 11 including an HDD (Hard Disc Drive) that stores (stores) various data and programs, content data, and the like, and is included in the content data. An encoder unit 12 for encoding (data compression, encryption, etc.) video information (video data) and audio information (audio data), and a communication unit 13 for controlling communication with the terminal device 2 through the network 3; , A CPU (Central Processing Unit), a working RAM (Random-Access Memory), a ROM (Read-Only Memory) that stores various data and programs, and the like. Each component is connected to each other via a bus 15.

  The control unit 14 reads and executes a program stored in the storage unit 11 and the like so that the control of the entire distribution server 1 is performed, and distribution control of content data is performed in response to a request from the terminal device 2. . Specifically, the control unit 14 generates a plurality of continuous data packets by dividing the content data encoded by the encoder unit 12 into a predetermined amount of data, and requests the terminal device 2 as a data stream. Distribution (streaming distribution) is performed to the terminal device 2 through the communication unit 13 or the like at the distribution speed (hereinafter referred to as “transfer speed”). Each data packet is given a packet number that continues from the beginning of the content.

  As shown in FIG. 3, the terminal device 2 is a storage unit 21 configured by an HDD or the like that stores various data and programs, and an accumulation unit that temporarily accumulates (stores) content data from the distribution server 1. A buffer memory 22, a decoder unit 23 that decodes (decompresses and decodes) video information and audio information included in the content data from the buffer memory 22, and reproduces the reproduced video information A video processing unit 24 that performs predetermined rendering processing and outputs the video signal, a display unit 25 such as a CRT or a liquid crystal display that displays video based on the video signal output from the video processing unit 24, and the reproduced audio An audio processing unit 26 that converts D (Digital) / A (Analog) information into an analog audio signal and then amplifies the information by an amplifier, and the audio A speaker 27 that outputs a sound signal output from the processing unit 26 as a sound wave, a communication unit 28 for controlling communication with the distribution server 1 through the network 3, a CPU having a calculation function, a working RAM, various types A control unit 29 composed of a ROM and the like for storing data and programs, and instructions (for example, reproduction output instructions, setting instructions, etc.) from a user (viewer) are input and the instruction signal is given to the control unit 29 An input unit (for example, a mouse, a keyboard, an operation panel, or a remote controller) 30 is configured, and the storage unit 21, the buffer memory 22, the decoder unit 23, the communication unit 28, the control unit 29, and the input unit 30 are a bus 31. Are connected to each other. As the terminal device 2, for example, an STB (Set Top Box) or a personal computer is applicable.

  The buffer memory 22 is composed of, for example, a FIFO (First In First Out) format ring buffer memory under the control of the control unit 29, and temporarily stores the content data received through the communication unit 28 in the storage area indicated by the reception pointer. The content data stored in the storage area indicated by the playback pointer is output to the decoder unit 23 via the bus 31.

  In the control unit 29, the CPU reads and executes a program (including the distribution speed control program of the present invention) stored in the storage unit 21 or the like, thereby controlling the entire terminal device 2 and reproducing control means. And function as speed control means. Note that the distribution speed control program may be downloaded from a predetermined server on the network 3, for example, or recorded on a recording medium such as a CD-ROM via a drive of the recording medium. It may be read.

  The control unit 29 as a playback control means controls the playback output of content data in the buffer memory 22 (that is, playback output by the decoder unit 23, the video processing unit 24, the audio processing unit 26, etc.) The reproducible buffer amount (the first buffer in the present invention) is the minimum buffer amount at which the content data storage amount (hereinafter referred to as “buffer amount”) in the buffer memory 22 can start the reproduction output of the content data. (For example, in the case of audio information, the amount of data for one audio frame, for example, in the case of video information, for example, the amount of data for one frame (picture), in other words, the decoder unit 23 is required.) When the data amount reaches the minimum data amount, reproduction and output of the content data is started.

  The control unit 29 as speed control means cooperates with the distribution server 1 to set the transfer rate of the content data from the distribution server 1 to the terminal device 2 based on the content data buffer amount in the buffer memory 22. Control is performed to change the transfer speed within a range equal to or higher than the reproduction output speed of the content data at the timing of changing the transfer speed based on the buffer amount of the content data.

  Here, with reference to FIG. 4, the transfer rate control of the content data in the control unit 29 will be described in detail.

  FIG. 4 is a conceptual diagram showing how the content data transfer rate is changed (in this example, two-stage change). In the example of FIG. 4, the vertical axis indicates the data amount (kbyte), the horizontal axis indicates time (t), and the slope of the line 51 indicates the transfer rate (first to third transfer rates). , The slope of the line 52 indicates the reproduction output speed. Further, the amount of data between the line 51 and the line 52 at an arbitrary time t indicates the buffer amount (that is, the amount of content data accumulated in the buffer memory 22).

  In the example of FIG. 4, when the buffer amount of the content data is smaller than the reproducible buffer amount 53, the control unit 29 causes the transfer speed to be the first transfer speed (the fastest speed (full speed)) faster than the playback output speed. (A period of “A” in FIG. 4), the buffer amount is greater than or equal to the reproducible buffer amount 53 and is larger than the reproducible buffer amount, and is set in advance as a set buffer amount (second accumulation in the present invention). If the transfer rate is less than 54, the transfer rate is controlled to be a second transfer rate that is slower than the first transfer rate and faster than the reproduction output rate (period “B” in FIG. 4). When the buffer amount is equal to or greater than the set buffer amount 54, the transfer rate becomes the third transfer rate (in other words, the data consumption rate of the decoder unit 23) that follows the reproduction output rate (in the period “C” in FIG. 4). And it is controlled. That is, according to the buffer amount in the buffer memory 22, the control unit 29 sets the delivery speed to a first delivery speed that is faster than the reproduction output speed of the content data, a first delivery speed that is slower than the first delivery speed, and faster than the reproduction output speed. Control is performed so as to switch between the second distribution speed and the third distribution speed that follows the reproduction output speed.

  Here, since the transfer rate is determined by three elements of the processing capability on the distribution server 1 side, the processing capability on the terminal device 2 side, and the bandwidth of the network 3 path (bandwidth), the first transfer rate ( The fastest speed (full speed) is as fast as possible after taking these three factors into account (that is, within the range where the bottleneck speed of these three factors does not reach its peak) Controllable).

  Further, the set buffer amount 54 is, for example, jitter of the network 3 (that is, fluctuation in transfer rate (transmission rate) in a communication line connecting the distribution server 1 and the terminal device 2, in other words, a deviation in arrival time of data packets ( Displacement)) is set in consideration, and the reproduction output of the content data is a buffer amount that is not affected by the jitter (that is, the reproduction output is not interrupted by the fluctuation). In the period “C” in FIG. 4, the set buffer amount 54 is maintained by following the reproduction output speed with the transfer speed being the third transfer speed. Further, in the period “B” in FIG. 4 until the buffer amount in the buffer memory 22 reaches the set buffer amount 54, the transfer speed is the second delivery speed higher than the reproduction output speed. The transfer speed is set so as to cancel out the jitter (transfer speed fluctuation) of the network, and the reproduction output speed (in other words, the data consumption speed) + the adjustment speed “a” (this value is (Determined according to jitter).

  Next, the operation of the content distribution system in the first embodiment will be described with reference to FIGS.

  5 to 8 are flowcharts showing processing of the control unit 29 of the terminal device 2 at the time of content data distribution according to the first embodiment.

  The process shown in FIG. 5 is started when, for example, a user requests a desired content via the input unit 30. First, the control unit 29 makes a connection request to the distribution server 1 (that is, the distribution server). 1 is transmitted) (step S1). In response to the connection request, the distribution server 1 executes a predetermined authentication process, and if it is satisfactory, returns information indicating connection acceptance to the terminal device 2.

  When the connection is accepted, the control unit 29 performs a connection establishment process with the distribution server 1 (step S2), and then makes a content data distribution request (step S3). In response to the distribution request, the distribution server 1 prepares distribution of the requested content data.

  Next, the control unit 29 confirms the current buffer amount in the buffer memory 22 (step S4), and if it is less than the reproducible buffer amount 53 (step S4: L), at the first transfer rate shown in step S5. If the reproducible buffer amount is 53 or more and less than the set buffer amount 54 (step S4: M), the request processing at the second transfer rate shown in step S6 (FIG. 7). If the set buffer amount is 54 or more (step S4: H), the process proceeds to the request process (FIG. 8) at the third transfer rate shown in step S7. In the initial stage where data is not yet stored in the buffer memory 22, such as when the user issues a content request instruction for the first time, the process proceeds to request processing at the first transfer rate.

  In the request process at the first transfer rate, as shown in FIG. 6, the control unit 29 first requests the distribution server 1 at a first transfer rate (for example, about 400 kbps (bit per second)) ( That is, information indicating a request for distributing data packets related to the content data at the first transfer rate is transmitted to the distribution server 1 (step S11). In response to the request, the distribution server 1 sets the transfer rate to the first transfer rate, and distributes the data packet to the terminal device 2 at the first transfer rate (note that the distribution server 1 performs the following from the terminal device 2). The data packets are successively sent at the first transfer rate until the request is received, and the data packets are received through the communication unit 28 of the terminal device 2 and accumulated in the buffer memory 22. .

  Next, the control unit 29 determines whether or not the last data packet has been received from the distribution server 1 (step S12), and if received (step S12: Y), disconnects the connection with the distribution server 1. (Step S19), it is determined whether or not unreproduced content data is stored in the buffer memory 22 (Step S20). If it is stored (Step S20: Y), the remaining content in the buffer memory 22 is determined. The data is reproduced and output (step S21), and the process ends.

  On the other hand, when the last data packet has not been received (step S12: N), the control unit 29 measures the jitter of the network 8 based on the received data packet (step S13).

  Next, the control unit 29 determines whether or not the buffer amount in the buffer memory 22 has reached the reproducible buffer amount 53 (in other words, has reached) or not (step S14), and has reached the reproducible buffer amount 53 or more. If not (step S14: N), the process returns to step S12 and the same processing as described above is performed.

  Thus, the jitter of the network 8 is obtained by, for example, the average value or the standard deviation of the arrival time differences of the respective data packets in a predetermined time until reaching the reproducible buffer amount 53.

  When the buffer amount in the buffer memory 22 becomes equal to or greater than the reproducible buffer amount 53 (step S14: Y), the control unit 29 gives a reproduction start command to the decoder unit 23 and the like (step S15). Thereby, reproduction output of the content data stored in the buffer memory 22 is started.

  Next, the control unit 29 determines whether or not the jitter obtained by the measurement in step S13 is larger than a predetermined value (for example, the maximum value of normally allowable jitter) (step S16). If not large (step S16: N), the set buffer amount 54 is set to the specified buffer amount, the adjustment speed “a” is set to the specified speed (step S18), and the process of step S4 shown in FIG. Return to. On the other hand, when the jitter is larger than the predetermined value (step S16: Y), the control unit 29 sets the setting buffer amount 54 to a buffer amount larger than the specified buffer amount (for example, a value proportional to the magnitude of the jitter). In addition, the adjustment speed “a” is set to a speed higher than the specified speed (for example, a value proportional to the magnitude of the jitter, that is, the buffer amount is increased if the jitter is large) (step S17), as shown in FIG. The process returns to step S4.

  Next, in the request processing at the second transfer speed, as shown in FIG. 7, the control unit 29 sends the second transfer speed (reproduction output speed + the set adjustment speed “a” to the distribution server 1. For example, a request (timing to change the transfer rate) is made at about 150 kbps when the jitter is not larger than the predetermined value, and about 200 kbps when the jitter is larger than the predetermined value (step S23). In response to the request, the distribution server 1 changes and sets the transfer rate to the second transfer rate, and distributes the data packet related to the content data to the terminal device 2 at the second transfer rate.

  Next, the control unit 29 determines whether or not the last data packet has been received from the distribution server 1 (step S24), and if it has been received (step S24: Y), disconnects the connection with the distribution server 1. (Step S26) When unreproduced content data is accumulated in the buffer memory 22 (Step S27: Y), the remaining content data in the buffer memory 22 is reproduced and output (Step S28), and the process is terminated. To do.

  On the other hand, if the last data packet has not been received (step S24: N), the control unit 29 has the buffer amount in the buffer memory 22 less than the reproducible buffer amount 53 or more than the set buffer amount 54 (that is, reproducible). It is determined whether or not the buffer amount is 53 or more and out of the set buffer amount 54 or less (step S25). If it is less than the reproducible buffer amount 53 or not less than the set buffer amount 54 (step S25). S25: N), returning to step S24, the same processing as described above is performed.

  On the other hand, when it becomes less than the reproducible buffer amount 53 or the set buffer amount 54 or more (step S25: Y), the processing returns to the step S4 shown in FIG.

  If the data packet is normally distributed and accumulated in the buffer memory 22, the buffer amount reaches the set buffer amount 54. For example, the distribution server 1 side or some network path 3 If delivery of data packets is delayed due to the cause, there may be a case where the reproducible buffer amount 53 becomes less. Even in such a case, the processing can be appropriately handled.

  Next, in the request processing at the third transfer rate, as shown in FIG. 8, the control unit 29 sends the third transfer rate (speed following the reproduction output rate to the distribution server 1; for example, about 100 kbps. ) (Timing for changing the transfer rate) is made (step S31). In response to the request, the distribution server 1 changes the transfer rate to the third transfer rate and distributes the data packet related to the content data to the terminal device 2 at the third transfer rate.

  Next, the control unit 29 determines whether or not the last data packet has been received from the distribution server 1 (step S32), and if received (step S32: Y), disconnects the connection with the distribution server 1. (Step S34) When unreproduced content data is stored in the buffer memory 22 (Step S35: Y), the remaining content data in the buffer memory 22 is reproduced and output (Step S36), and the process is terminated. To do.

  On the other hand, when the last data packet has not been received (step S32: N), the control unit 29 determines whether or not the buffer amount in the buffer memory 22 is less than the set buffer amount 54 (step S33). If the set buffer amount is not less than 54 (step S33: N), the process returns to step S32 and the same processing as described above is performed.

  On the other hand, when it becomes less than the set buffer amount 54 (step S33: Y), the process returns to the process of step S4 shown in FIG.

  As described above, according to the first embodiment, the content data is distributed at the first transfer speed (full speed) until the buffer amount stored in the buffer memory 22 reaches the reproducible buffer amount (see “ After that, the content data is distributed at the second transfer rate (reproduction output rate + adjustment rate “a”) until the buffer amount reaches the set buffer amount considering the jitter of the network 3 (FIG. 4). Content data is distributed at a third transfer speed (speed following the playback output speed) (period "C" in FIG. 4), and then the content data playback output speed In the above range, since the transfer rate is changed stepwise according to the buffer amount, the distributed content is not affected by the jitter of the network 3. It is possible to shorten the time until the reproduction of over data. In addition, since the distribution server 1 can transfer (distribute) data packets at full speed during the period “A” in FIG. 4, the burden on the distribution server 1 can be reduced.

  In particular, when there are many streaming channels, it is assumed that the user will first watch various channels and then settle down to one channel. In such a case, the buffering is performed to a sufficient buffer amount each time. Since waste can be eliminated and playback can be started quickly, convenience for the user can be improved.

  In the above embodiment, the example in which the transfer speed is changed (decelerated) in two stages within the range of the content data reproduction output speed or more is shown, but the present invention is not limited to this, and there are more stages than two stages. You may comprise so that it may change automatically. For example, the second delivery speed may be changed in a plurality of stages or in a quadratic curve during the period “B” in FIG.

(II) Second Embodiment Next, a content distribution system in the second embodiment will be described.

  In the said 1st Embodiment, although the 1st-3rd transfer rate demonstrated the server initiative type | formula set by the delivery server 1 according to the request | requirement from the terminal device 2, in 2nd Embodiment, A client-driven form in which the first to third transfer rates are determined by the request timing of the terminal device 2 will be described with reference to FIGS. In addition, since the structure and function of the delivery server 1 and the terminal device 2 in 2nd Embodiment are the same as that of 1st Embodiment, the overlapping description is abbreviate | omitted.

  9 to 12 are flowcharts showing processing of the control unit 29 of the terminal device 2 at the time of content data distribution according to the second embodiment. FIG. 13 shows a data block request from the terminal device 2 to the distribution server 1. It is a figure which shows an example of a timing.

  The process shown in FIG. 9 is started when a request for requesting desired content is received from the user via the input unit 30, for example, as in the first embodiment. Note that the processing from step S41 to step S43 shown in FIG. 9 is the same as the processing from step S1 to step S3 shown in FIG.

  Next, in step S44 of FIG. 9, the control unit 29 sets “0” as the initial value of the number i of the data block constituting the content data (i = 0).

  Here, the data block is content data that is divided into block units (arbitrary data amount (for example, several kbytes to several Mbytes)) on the distribution server 1 side, and is continuous with respect to each data block, for example. A unique number is assigned. The terminal device 2 makes a distribution request to the distribution server 1 by designating the data block number. This data block is further divided into a plurality of data packets and distributed.

  Next, as in the first embodiment, the control unit 29 checks the current buffer amount in the buffer memory 22 (step S45), and if it is less than the reproducible buffer amount 53 (step S45: L), step S46. The process proceeds to the request processing with the first waiting time shown in FIG. 10 (FIG. 10), and when the reproducible buffer amount 53 is less than the set buffer amount 54 (step S45: M), the second waiting time shown in step S47 is reached. If the setting buffer amount is 54 or more (step S45: H), the process proceeds to the request process with the third waiting time shown in step S48 (FIG. 12).

  In the request processing in the first waiting time, as shown in FIG. 10, the control unit 29 first requests the i-th data block from the distribution server 1 (that is, the i-th data block from the distribution server 1). Information indicating a request to distribute the data block is transmitted) (step S51). In response to the request, the distribution server 1 distributes the data packet related to the data block to the terminal device 2 at a predetermined transfer rate, and the data packet is received through the communication unit 28 of the terminal device 2 and is buffered. It is stored in the memory 22.

  Next, the control unit 29 increments the data block number i by “1” (step S52), and then determines whether or not the last data packet has been received from the distribution server 1 (step S53). When the last data packet has not been received (step S53: N), the control unit 29 measures the jitter of the network 8 based on the received data packet as in the first embodiment (step S54). Then, it is determined whether or not the buffer amount in the buffer memory 22 is greater than or equal to the reproducible buffer amount 53 (step S55).

  If the reproducible buffer amount 53 is not exceeded (step S55: N), the control unit 29 returns to step S51 after the first waiting time has elapsed (step S56), and the next data block ( The i-th data block incremented in step S52 is requested to the distribution server 1.

  Here, the “waiting time” defines an elapsed time from the timing at which the previous data block was requested, and in step S56, the control unit 29 monitors the clock and becomes the time of the next request timing. I will wait for you. Thereby, the request timing of the data block of the terminal device 2 is determined, and the transfer rate is determined by the time interval of the plurality of request timings.

  In the second embodiment, when the buffer amount of the content data is smaller than the reproducible buffer amount 53, this waiting time is referred to as “first waiting time” (for example, the terminal device 2 distributes the data block at the full speed). When it is pulled out, it is “0” (zero) time, that is, the maximum transfer rate (depending on the operation speed of the CPU) that the terminal device 2 can issue is controlled to be the first transfer rate, and the buffer amount Is greater than or equal to the reproducible buffer amount 53 and less than a preset buffer amount 54 that is greater than the reproducible buffer amount and is set as the “second wait time” (longer than the first wait time). When the second transfer rate is controlled and the buffer amount is equal to or greater than the set buffer amount 54, the waiting time is “third waiting time” (longer than the second waiting time). And controls so that the third transfer rate as.

  For example, the example of FIG. 13 shows the request timing to the distribution server. In the period “A”, a data block request is made to the distribution server at the time interval “T1” determined by the first waiting time. In the period “B”, a data block is requested to the distribution server at a time interval “T2” determined by the second waiting time. In the “C” period, the time interval determined by the third waiting time is requested. A data block request is made to the distribution server at “T3”. In this way, the speed accumulated in the buffer memory 22 can be adjusted by changing the time interval of the request timing.

  Note that the processing from step S57 to step S63 shown in FIG. 10 is the same as the processing from step S15 to step S21 shown in FIG.

  Next, in the request processing in the second waiting time, as shown in FIG. 11, the control unit 29 first requests the i-th data block from the distribution server 1 (step S65). The data block number i is incremented by “1” (step S66), and then it is determined whether or not the last data packet has been received from the distribution server 1 (step S67). When the last data packet has not been received (step S67: N), the control unit 29 has the buffer amount in the buffer memory 22 less than the reproducible buffer amount 53 or the set buffer amount 54 or more, as in the first embodiment. (Step S68), and when the reproducible buffer amount is less than 53 or not larger than the set buffer amount 54 (step S68: N), after the above-described second waiting time has passed ( In step S69), the process returns to step S65, and the next data block is requested to the distribution server 1.

  Note that the processing from step S70 to step S72 shown in FIG. 11 is the same as the processing from step S26 to step S28 shown in FIG.

  Next, in the request processing in the third waiting time, as shown in FIG. 12, the control unit 29 first requests the i-th data block from the distribution server 1 (step S75). The data block number i is incremented by “1” (step S76), and then it is determined whether or not the last data packet has been received from the distribution server 1 (step S77). When the last data packet has not been received (step S77: N), the control unit 29 determines whether or not the buffer amount in the buffer memory 22 is less than the set buffer amount 54, as in the first embodiment. If the set buffer amount is not less than 54 (step S78: N), after the above-described third waiting time has elapsed (step S79), the process returns to step S75, and the next data block is stored. Requests to the distribution server 1.

  Note that the processing from step S80 to step S82 shown in FIG. 12 is the same as the processing from step S34 to step S36 shown in FIG.

  As described above, according to the second embodiment, in addition to having the same effect as that of the first embodiment, for example, when the performance of the distribution server and the terminal device are greatly different, the request from the terminal device is Since the data is transferred after reaching the distribution server, there is an effect that data is not missed on the terminal device side (that is, data transfer that matches the performance of the terminal device is possible).

  In the second embodiment, the size (data amount) of the data block is fixed and the time interval of the request timing is variable, but as another example, the time interval of the request timing is fixed and the data block The size (data amount) may be controlled to be variable.

(III) Third Embodiment Next, a content distribution system according to a third embodiment will be described.

  FIG. 14 is a diagram illustrating a schematic configuration example of a content distribution system according to the third embodiment, and fourth and fifth embodiments to be described later.

  In the first and second embodiments, the form in which the content data is distributed from one distribution server 1 to the terminal device 2 has been described. However, in the third embodiment, as shown in FIG. A mode in which a data block obtained by dividing one content data from each of the three distribution servers 1A, 1B, and 1C is distributed to the terminal device 2 (distributed streaming distribution) will be described. The configurations and functions of the distribution servers 1A, 1B, 1C and the terminal device 2 in the third embodiment are basically the same as those of the distribution server 1 and the terminal device 2 in the first embodiment. Omitted.

  The distribution servers 1A, 1B, and 1C have different transfer rates of content data (data packets), and among these three distribution servers, the distribution server 1A has the fastest transfer rate. Although 1B is slower than the distribution server 1A, it is faster than the distribution server 1C, and the distribution server 1C is the latest one. Further, these distribution servers 1A, 1B, and 1C have the same content data.

  On the other hand, the control unit 29 as speed control means in the terminal device 2 changes the number of distribution servers 1A, 1B, 1C to change the number of distribution servers to be connected at the timing of changing the transfer rate based on the content data buffer amount. Control connection with. That is, the number of connections of the distribution servers 1A to 1C can be changed so as to achieve a transfer rate to be controlled.

  This transfer rate control will be described with reference to FIG. 4. For example, in the period “A”, the fastest transfer rate from each of the three distribution servers 1 A, 1 B and 1 C (for example, the overall transfer rate viewed from the terminal device 2). Are distributed at the first transfer rate), and during the period “B”, two distributions are performed so that the transfer rate of the content data is the second transfer rate as viewed from the terminal device 2. Each of the servers 1B and 1C is controlled so that the data packet is distributed. During the period “C”, the data packet is distributed from one distribution server 1C so that the transfer rate of the content data becomes the third transfer rate. It is controlled so that

  Next, the operation of the content distribution system in the third embodiment will be described with reference to FIGS.

  FIGS. 15 to 19 are flowcharts showing processing of the control unit 29 of the terminal device 2 at the time of content data distribution according to the third embodiment. FIG. 20 is a data block from the terminal device 2 to the distribution servers 1A to 1C. It is a figure which shows an example of the request | requirement timing.

  The process shown in FIG. 15 is started when a request for a desired content is received from the user via the input unit 30, for example, as in the first embodiment. First, the control unit 29 includes a plurality of distribution servers, for example, A connection request is made to each of the three distribution servers 1A, 1B, and 1C (step S101). In response to the connection request, each of the distribution servers 1A, 1B, and 1C executes a predetermined authentication process, and if it is satisfactory, returns information indicating connection acceptance to the terminal device 2.

  When the connection is accepted, the control unit 29 performs connection establishment processing with the distribution servers 1A, 1B, and 1C (step S102), and then requests distribution of content data to the respective distribution servers ( Step S103). In response to the distribution request, the distribution servers 1A, 1B, and 1C prepare for distribution of the requested content data.

  Next, the control unit 29 sets “0” (sets i = 0) as the initial value of the number i of the data block constituting the content data (step S104).

  Next, as in the second embodiment, the control unit 29 confirms the current buffer amount in the buffer memory 22 (step S105), and if it is less than the reproducible buffer amount 53 (step S105: L), step S106. The process proceeds to the request processing with the first waiting time shown in FIG. 16 (FIG. 16), and when the reproducible buffer amount 53 is less than the set buffer amount 54 (step S105: M), the second waiting time shown in step S107 is reached. If the set buffer amount is 54 or more (step S105: H), the process proceeds to the request process with the third waiting time shown in step S108 (FIG. 18).

  In the request process during the first waiting time, as shown in FIG. 16, the control unit 29 performs a connection process for the distribution server 1A (step S111). In the connection process of the distribution server 1A, as shown in FIG. 19A, the control unit 29 determines whether or not the distribution server 1A is already connected (step S155), and is connected (for example, If the connection is completed immediately after the start of the process shown in FIG. 15 (step S155: Y), the process returns to the process of FIG. On the other hand, if not connected (step S155: N), the control unit 29 issues a connection request to the plurality of distribution servers 1A (step S156), and subsequently establishes connection with the distribution server 1A. (Step S157), then, a distribution data distribution request is made to the distribution server 1A (Step S158), and the process returns to the process of FIG.

  Next, in step S112 illustrated in FIG. 16, the control unit 29 performs connection processing (FIG. 19B) for the distribution server 1B. Since the connection process of the distribution server 1B is the same as the connection process of the distribution server 1A, description thereof is omitted.

  Next, the control unit 29 requests the i-th data block from the idle distribution server (that is, the distribution server for which the data block distribution preparation is completed among the distribution servers 1A to 1C) (step S113). Subsequently, the data block number i is incremented by "1" (step S114). When there are a plurality of idle distribution servers, a method of issuing a request to a distribution server having a long idle time or a method of issuing a request for the i-th data block to a distribution server having a high transfer rate can be considered. Further, when there is no idle distribution server, it waits until one of the connected distribution servers becomes idle.

  Next, the control unit 29 determines whether or not the last data packet has been received from any of the distribution servers (step S115). If the last data packet has not been received (step S115: N), Similar to the second embodiment, the jitter of the network 8 is measured based on the received data packet (step S116).

  Next, the control unit 29 determines whether or not the buffer amount in the buffer memory 22 is greater than or equal to the reproducible buffer amount 53 (step S117), and when it is not greater than or equal to the reproducible buffer amount 53 (step S117: N) As in the second embodiment, after the first waiting time has elapsed (step S118), the process returns to step S113 to request the next data block from the idle distribution server.

  In this way, the data block request processing is repeated until the reproducible buffer amount becomes 53 or more. At this time, for example, as shown in FIG. 20, the control unit 29 performs processing in descending order of processing capability (that is, the distribution server 1C). The distribution server 1B and the distribution server 1A increase in order, so that the data block request interval is shortened (the numbers in the inverted triangles in FIG. 20 indicate the order of the data block requests). )

  In the example of FIG. 20, the first waiting time is set to zero in the transfer time with the first waiting time, and there is a delay by the time from the step S113 until returning from the loop. That is, a request for the next data block is immediately made to the distribution server that has finished distributing (transferring) the data block. When it exceeds the reproducible buffer amount, the process proceeds to the second waiting time process, and a request is made to the distribution server at the second waiting time interval. The same applies to the third waiting time.

  Note that the processing from step S119 to step S122 shown in FIG. 16 is the same as the processing from step S15 to step S21 shown in FIG.

  Next, after the process of step S121, the control unit 29 disconnects from the distribution server 1A (step S123), and returns to the process of FIG.

  When the control unit 29 receives the last data packet (step S115: Y), the control unit 29 disconnects all connected distribution servers (step S124), and performs steps S125 and the like. Then, the process ends.

  In the request process in the second waiting time, as shown in FIG. 17, the control unit 29 performs the connection process of the distribution server 1B as in step S112 (step S131).

  Next, the control unit 29 requests the i-th data block from the idle distribution server (that is, the distribution server that is ready to distribute data blocks among the distribution servers 1A and 1B) (step S132). Subsequently, the data block number i is incremented by “1” (step S133).

  Next, the control unit 29 determines whether or not the last data packet has been received (step S134). If the last data packet has not been received (step S134: N), the buffer amount in the buffer memory 22 is determined. Is less than the reproducible buffer amount 53 or the set buffer amount 54 or more (step S135), and if it is less than the reproducible buffer amount 53 or the set buffer amount 54 or more (step S135: N) As in the second embodiment, after the second waiting time has elapsed (step S136), the process returns to step S132 to request the next data block from the idle distribution server.

  When the control unit 29 receives the last data packet (step S134: Y), the control unit 29 disconnects all connected distribution servers (step S138), and performs step S125 and the like. Then, the process ends.

  The request process with the third waiting time shown in FIG. 18 is the same as the request process with the third waiting time shown in FIG.

  As described above, according to the third embodiment, in addition to having the same effect as that of the second embodiment, for example, a distribution server having a higher transfer speed than other distribution servers can be efficiently used in many terminal devices. can do. Further, as in the third embodiment, the method of gradually reducing the number of distribution server connections is effective when there are few distribution servers having the same content data.

  In the third embodiment, a plurality of distribution servers having different transfer speeds have been described as examples. However, the present invention is not limited to this. For example, the content distribution system has the same transfer speed. A distribution server group including a plurality of distribution servers, including a plurality of distribution server groups having different transfer rates, and one piece of content data is divided from each of the plurality of distribution server groups and distributed to the terminal device 2. In this manner, the control unit 29 of the terminal device 2 may control connection with each distribution server group so as to change the number of distribution server groups to be connected at the timing of changing the transfer speed.

  FIG. 21 is a diagram illustrating a schematic configuration example of a content distribution system including three distribution server groups having different transfer rates. In the example of FIG. 21, a distribution server group 1D having the fastest transfer speed, a distribution server group 1E having a normal transfer speed, and a distribution server group 1F having the slowest transfer speed are shown. 1D to 1F are provided with three distribution servers having the same transfer rate. In such a configuration, the number of connections of the distribution server groups 1D to 1F is changed by, for example, the processing in FIGS. 15 to 19 so that the transfer speed to be controlled is obtained (for example, in the processing in FIGS. 15 to 19). The distribution server 1A corresponds to the distribution server group 1D, the distribution server 1B corresponds to the distribution server group 1E, and the distribution server 1C corresponds to the distribution server group 1F). With this configuration, even when one distribution server in the distribution server group stops functioning (down), the content data can be reproduced and output without being affected by the influence.

(IV) Fourth Embodiment Next, a content distribution system according to a fourth embodiment will be described.

  In the fourth embodiment, a description will be given of a mode in which connections to a plurality of (here, three) distribution servers 1A, 1B, and 1C shown in FIG.

  The configurations and functions of the distribution servers 1A, 1B, 1C and the terminal device 2 in the fourth embodiment are basically the same as those of the distribution server 1 and the terminal device 2 in the first embodiment. Omitted.

  Also in the fourth embodiment, similarly to the third embodiment, the distribution servers 1A, 1B, and 1C have different content data (data packet) transfer speeds, and among these three distribution servers. Thus, the transfer server 1A has the fastest transfer speed, the distribution server 1B is slower than the distribution server 1A, but faster than the distribution server 1C, and the distribution server 1C is the slowest. These distribution servers 1A, 1B, and 1C have the same content data.

  On the other hand, the control unit 29 as speed control means in the terminal device 2 performs control so as to switch the connection of the distribution server at the timing of changing the transfer speed based on the content data buffer amount.

  This transfer speed control will be described with reference to FIG. 4. For example, during the period “A”, data is transmitted from the delivery server 1A having the fastest transfer speed to the first transfer speed (fastest speed (full speed) in the delivery server 1A). The packet is controlled to be distributed, and is switched from the distribution server 1A to the distribution server 1B at the boundary between the “A” period and the “B” period. In the “B” period, the transfer rate is a normal distribution server. The data packet is controlled to be distributed from 1B at the second transfer rate, and is switched from the distribution server 1B to the distribution server 1C at the boundary between the “B” period and the “C” period. The data packet is controlled to be delivered at the third transfer rate from the delivery server 1C having the slowest transfer rate.

  Next, the operation of the content distribution system in the fourth embodiment will be described with reference to FIGS. 22 to 26 and the like.

  22 to 26 are flowcharts showing processing of the control unit 29 of the terminal device 2 at the time of content data distribution according to the fourth embodiment.

  Similar to the first embodiment, the processing shown in FIG. 22 is started, for example, when a request for a desired content is received from the user via the input unit 30. First, the control unit 29 performs the current processing in the buffer memory 22. The buffer amount is confirmed (step S171), and if it is less than the reproducible buffer amount 53 (step S171: L), the process proceeds to the request processing (FIG. 23) at the first transfer speed shown in step S172 and replay is possible. If the buffer amount is 53 or more and less than the set buffer amount 54 (step S171: M), the process proceeds to the request processing (FIG. 24) at the second transfer rate shown in step S173, and the set buffer amount is 54 or more. (Step S171: H), the process proceeds to the request process (FIG. 25) at the third transfer rate shown in Step S174.

  In the request process at the first transfer rate, as shown in FIG. 23, the control unit 29 performs the connection process of the distribution server 1A (step S181). In the connection process of the distribution server 1A, as shown in FIG. 26A, the control unit 29 makes a connection request to the distribution server 1A having the fastest transfer speed (step S215), and then continues to the distribution server. A connection establishment process with 1A is performed (step S216), and then a content data distribution request is made to distribution server 1A (step S217).

  Next, the control unit 29 determines whether there is a connected distribution server other than the distribution server 1A (step S218). If there is a connection server (step S218: Y), the control unit 29 determines whether there is a distribution server other than the distribution server 1A. Is disconnected (step S219), and the process returns to the process of FIG.

  Note that the processing from step S182 to step S192 shown in FIG. 23 is the same as the processing from step S11 to step S21 shown in FIG.

  Next, in the request process at the second transfer rate, as shown in FIG. 24, the control unit 29 performs the connection process of the distribution server 1B (step S195). In the connection process of the distribution server 1B, as shown in FIG. 26B, the control unit 29 makes a connection request to the distribution server 1B having the fastest transfer speed in order to switch the distribution server (step S221). Subsequently, a connection establishment process with the distribution server 1B is performed (step S222), then a distribution request for content data is made to the distribution server 1B (step S223), and a distribution server other than the distribution server 1B is connected. Is disconnected (step S224), and the process returns to the process of FIG.

  Note that the processing from step S196 to step S201 shown in FIG. 24 is the same as the processing from step S23 to step S28 shown in FIG.

  Next, in the request process at the third transfer rate, as shown in FIG. 25, the control unit 29 performs a connection process for the distribution server 1C (step S205). In the connection process of the distribution server 1C, as shown in FIG. 26C, the control unit 29 makes a connection request to the distribution server 1C having the fastest transfer speed in order to switch the distribution server (step S226). Subsequently, a connection establishment process with the distribution server 1C is performed (step S227), and then a content data distribution request is made to the distribution server 1C (step S228). Is disconnected (step S22), and the process returns to the process of FIG.

  Note that the processing from step S206 to step S211 shown in FIG. 25 is the same as the processing from step S31 to step S36 shown in FIG.

  As described above, according to the fourth embodiment, in addition to having the same effects as those of the first embodiment, for example, a distribution server having a higher transfer speed than other distribution servers can be efficiently used in many terminal devices. can do.

  In the fourth embodiment, a plurality of distribution servers having different transfer rates have been described as examples. However, the present invention is not limited to this. For example, as in the third embodiment, the content distribution system is And a plurality of distribution server groups (for example, as shown in FIG. 21) having different transfer speeds, each including a plurality of distribution server groups having the same transfer speed. At the timing when the control unit 29 changes the transfer rate, the connection is switched to a distribution server group having a different transfer rate (for example, in the processing of FIGS. 22 to 26, the distribution server group 1D → the distribution server group 1E → the distribution server). It is switched in the order of group 1F). With this configuration, even when one distribution server in the distribution server group stops functioning (down), the content data can be reproduced and output without being affected by the influence.

(V) Fifth Embodiment Next, a content distribution system in the fifth embodiment will be described.

  In the fifth embodiment, similarly to the fourth embodiment, the connection with a plurality of (here, three) distribution servers 1A, 1B, 1C shown in FIG. 14 is sequentially switched, and the content data is distributed to the terminal device 2. However, in the fifth embodiment, FIG. 26 to FIG. 30 are used for the client-driven type (similar to the second embodiment) in which the first to third transfer rates are determined by the request timing of the terminal device 2. The description will be given with reference. The configurations and functions of the distribution servers 1A, 1B, 1C and the terminal device 2 in the fifth embodiment are basically the same as those of the distribution server 1 and the terminal device 2 in the first embodiment. Omitted.

  27 to 30 are flowcharts showing processing of the control unit 29 of the terminal device 2 at the time of content data distribution according to the fifth embodiment.

  The process shown in FIG. 27 is started when a request for a desired content is received from the user via the input unit 30, for example, as in the first embodiment. First, the control unit 29 sets the data constituting the content data. “0” is set as the initial value of the block number i (i = 0) (step S231).

  Next, as in the second embodiment, the control unit 29 checks the current buffer amount in the buffer memory 22 (step S232), and if it is less than the reproducible buffer amount 53 (step S232: L), step S233. The process proceeds to the request processing with the first waiting time shown in FIG. 28 (FIG. 28), and when the reproducible buffer amount 53 is less than the set buffer amount 54 (step S232: M), the second waiting time shown in step S234 is reached. When the setting buffer amount is 54 or more (step S232: H), the process proceeds to the request process with the third waiting time shown in step S235 (FIG. 30).

  In the request process in the first waiting time, as shown in FIG. 28, the control unit 29 performs the connection process of the distribution server 1A (the process of FIG. 26A as in the fourth embodiment) (step S241). ).

  Note that the processing from step S242 to step S254 shown in FIG. 28 is the same as the processing from step S51 to step S63 shown in FIG.

  Next, in the request process at the second transfer rate, as shown in FIG. 29, the control unit 29 performs the connection process of the distribution server 1B (the process of FIG. 26B as in the fourth embodiment). (Step S256).

  Note that the processing from step S257 to step S264 shown in FIG. 29 is similar to the processing from step S65 to step S72 shown in FIG.

  Next, in the request process at the third transfer rate, as shown in FIG. 30, the control unit 29 performs the connection process of the distribution server 1C (the process of FIG. 26C as in the fourth embodiment). (Step S271).

  Note that the processing from step S272 to step S279 shown in FIG. 30 is the same as the processing from step S75 to step S82 shown in FIG.

  As described above, the fifth embodiment can provide the same effects as those of the fourth embodiment.

  In the first to fifth embodiments, the present invention is applied to the server-client type content distribution system. However, the present invention is not limited to this, and Peer to Peer (P2P). The present invention may be applied to a type of content distribution system. In the peer-to-peer type content distribution system, each peer (node) has a function as the above-described distribution server and terminal device. In such a peer-to-peer type content distribution system, there is a difference in capability such as distribution speed (transfer speed) of each node, so that the present invention is applied and control is performed so as to change the transfer speed in stages as described above. It is especially effective to do.

  Also, the distribution server has a tree structure network in which a plurality of nodes form a plurality of hierarchies and are connected in a tree shape via communication lines, and the content data distributed by the distribution server is a higher hierarchy node. The present invention can also be applied to a tree-type content distribution system in which data is sequentially transferred from a node to a lower hierarchy node. In this case, not only when the distribution of the content data is started, but also because the latest upper layer node that transfers the content data to the own node has left the tree structure network (for example, due to a power failure). The present invention is also applied when the local node reconnects to another upper layer node to receive the content data transfer, and the transfer is performed according to the buffer amount within the range higher than the content data reproduction output speed. It is effective if the speed is changed (decelerated) stepwise.

  In the above embodiment, the first transfer rate is set when the reproducible buffer amount is less than 53, the second transfer rate is set when the reproducible buffer amount is 53 or more and less than the set buffer amount 54, and the third transfer rate is set when the set buffer amount is 54 or more. However, when the reproducible buffer amount is 53 or less, the first transfer rate is set. When the reproducible buffer amount is 53 and less than the set buffer amount 54, the second transfer rate is set. When the set buffer amount is larger than 54, the third transfer rate is set. Also good. Alternatively, the first transfer rate may be set when the reproducible buffer amount is less than 53, the second transfer rate may be set when the reproducible buffer amount is 53 or more and the set buffer amount is less than 54, and the third transfer rate may be set when the set buffer amount is greater than 54. Alternatively, the first transfer rate may be set when the reproducible buffer amount is 53 or less, the second transfer rate may be set when the reproducible buffer amount is 53 and less than the set buffer amount 54, and the third transfer rate may be set when the set buffer amount is 54 or more. . Note that the speed control means in the present invention has a content data transfer speed (delivery speed) that is higher than the reproduction output speed, lower than the first transfer speed, and lower than the first transfer speed, according to the buffer amount in the buffer memory, and Control is made so as to switch between a second transfer speed that is faster than the reproduction output speed and a third transfer speed that follows the reproduction output speed, and it is particularly limited to which buffer amount the transfer speed is switched to Is not to be done.

It is a figure showing an example of outline composition of a contents distribution system in a 1st embodiment. It is a block diagram which shows the example of a schematic structure of a delivery server. It is a block diagram which shows the example of a schematic structure of a terminal device. It is a conceptual diagram which shows a mode that the transfer rate of content data is changed. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 1st Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 1st Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 1st Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 1st Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 2nd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 2nd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 2nd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 2nd Embodiment. It is a figure which shows an example of the request timing of the data block from the terminal device 2 to the delivery server 1. FIG. It is a figure which shows the example of a schematic structure of the content delivery system in 3rd Embodiment and 4th and 5th embodiment mentioned later. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 3rd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 3rd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 3rd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 3rd Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 3rd Embodiment. It is a figure which shows an example of the request timing of the data block from the terminal device 2 to distribution server 1A thru | or 1C. It is a figure which shows the example of an outline structure of a content delivery system provided with three delivery server groups from which a transfer rate differs mutually. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 4th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 4th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 4th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 4th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 4th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 5th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 5th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 5th Embodiment. It is a flowchart which shows the process of the control part 29 of the terminal device 2 in the case of the content data delivery of 5th Embodiment.

1, 1A, 1B, 1C Distribution server 2 Terminal device 3 Network 11 Storage unit 12 Encoder unit 13 Communication unit 14 Control unit 15 Bus 21 Storage unit 22 Buffer memory 23 Decoder unit 24 Video processing unit 25 Display unit 26 Audio processing unit 27 Speaker 28 Communication unit 29 Control unit 30 Input unit
31 bus

Claims (3)

A distribution source device that distributes distribution information to be distributed; and a distribution destination device that is a distribution destination device that receives distribution of the distribution information and includes storage means for temporarily storing the distributed distribution information. In the distribution speed control device that is included in the distribution system and controls the distribution speed of the distribution information from the distribution source device to the distribution destination device,
The distribution speed is set within a range equal to or higher than the reproduction output speed of the distribution information distributed to the distribution destination device at the timing of changing the distribution speed based on the storage amount of the distribution information in the storage means. Changing speed control means ;
Reproduction control means for starting reproduction output of the distribution information when the accumulation amount in the accumulation means becomes the first accumulation amount;
With
The speed control means is
When the accumulated amount is smaller than the first accumulated amount, the delivery speed is controlled to be a first delivery speed faster than the reproduction output speed,
When the accumulation amount is not less than the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed, and the Control to be a second distribution speed that is faster than a reproduction output speed and that offsets fluctuations in transmission speed in a communication line connecting the distribution source apparatus and the distribution destination apparatus ;
Furthermore, when the accumulation amount is equal to or greater than the second accumulation amount, the distribution speed control device controls the distribution speed to be a third distribution speed that follows the reproduction output speed. A distribution source device that distributes distribution information to be distributed; and a distribution destination device that is a distribution destination device that receives distribution of the distribution information and includes storage means for temporarily storing the distributed distribution information. In a delivery speed control method of a delivery speed control device included in the delivery system for controlling the delivery speed of the delivery information from the delivery source device to the delivery destination device,
The distribution speed is set within a range equal to or higher than the reproduction output speed of the distribution information distributed to the distribution destination device at the timing of changing the distribution speed based on the storage amount of the distribution information in the storage means. A speed control process to be changed;
A reproduction control step of starting reproduction output of the distribution information when the accumulation amount in the accumulation means becomes a first accumulation amount;
Including
In the speed control step,
When the accumulated amount is smaller than the first accumulated amount, the delivery speed is controlled to be a first delivery speed faster than the reproduction output speed,
When the accumulation amount is not less than the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed, and the Control to be a second distribution speed that is faster than a reproduction output speed and that offsets fluctuations in transmission speed in a communication line connecting the distribution source apparatus and the distribution destination apparatus;
Furthermore, when the accumulation amount is equal to or greater than the second accumulation amount , the distribution speed control method is controlled so that the distribution speed becomes a third distribution speed that follows the reproduction output speed . A distribution source device that distributes distribution information to be distributed; and a distribution destination device that is a distribution destination device that receives distribution of the distribution information and includes storage means for temporarily storing the distributed distribution information. A computer included in a distribution speed control device that is included in a distribution system and controls a distribution speed of the distribution information from the distribution source device to the distribution destination device.
The distribution speed is set within a range equal to or higher than the reproduction output speed of the distribution information distributed to the distribution destination device at the timing of changing the distribution speed based on the storage amount of the distribution information in the storage means. A speed control step to change;
A reproduction control step of starting reproduction output of the distribution information when the accumulation amount in the accumulation means becomes the first accumulation amount;
And execute
In the speed control step,
When the accumulation amount is smaller than the first accumulation amount, the delivery speed is controlled to be a first delivery speed that is faster than the reproduction output speed,
When the accumulation amount is not less than the first accumulation amount and less than a preset second accumulation amount that is greater than the first accumulation amount, the delivery speed is slower than the first delivery speed, and the A second delivery speed that is faster than the reproduction output speed, and is controlled to be a second delivery speed that cancels a change in transmission speed in a communication line connecting the delivery source device and the delivery destination device;
Furthermore, when the accumulation amount is equal to or greater than the second accumulation amount , the distribution speed control program is controlled so that the distribution speed becomes a third distribution speed that follows the reproduction output speed .

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