WO2012093718A1

WO2012093718A1 - Content acquisition device, reproduction device, content acquisition method, distribution system, content acquisition program, and recording medium

Info

Publication number: WO2012093718A1
Application number: PCT/JP2012/050164
Authority: WO
Inventors: 高橋　真毅
Original assignee: シャープ株式会社
Priority date: 2011-01-07
Filing date: 2012-01-06
Publication date: 2012-07-12

Abstract

A reproduction device (100) is provided with a communication control unit (110) which reads out a bit rate value indicated by bandwidth attributes from among MPD data recorded in a storage unit (130). The control unit (110) causes a network interface (140) to acquire, from a distribution server, media segments (MS) in which all video content is time divided. Specifically, the control unit (110) causes the interface (140) to concurrently acquire a plurality of media segments (MS) by way of N logical channels. The control unit (110) sets the value of N such that the value of N increases as the bit rate value increases.

Description

Content acquisition device, playback device, content acquisition method, distribution system, content acquisition program, and recording medium

The present invention relates to a content acquisition device, a playback device, and a content acquisition method for acquiring content data from a distribution server. The present invention also relates to a distribution system including such a distribution server and a content acquisition device. Furthermore, the present invention relates to a content acquisition program that causes a computer to operate as such a content acquisition device, and a recording medium that stores such a content acquisition program.

In recent years, with the rapid increase in demand for the Internet, not only WEB pages composed of static content such as texts and still images but also users who watch video content are increasing.

Since the moving image content has a huge amount of data compared to text data and still image data, it is inevitably necessary to secure a sufficient transmission speed for communication from the moving image content distribution server to the playback device.

Problems that make it difficult to secure the transmission rate of communication are roughly classified into the following two.
Problem 1) Link speed (line speed) is insufficient. For example, when the playback device uses a wireless communication network such as a 3G network network or a wireless LAN network (Wi-Fi), the link speed of the wireless network depends on the distance from the playback device to the base station and the presence or absence of a shield. There are cases in which the transmission speed required to play streaming video content without interruption cannot be ensured due to large fluctuations.
Problem 2) Insufficient communication throughput (effective speed). For example, it is necessary to play back streaming video content without interruption due to a decrease in throughput due to communication protocol restrictions and insufficient processing capabilities of NW devices such as distribution servers that distribute and relay video content. There are cases where the transmission speed cannot be secured.

チャンネル Channel bonding technology is a technology that can prevent the transmission of video content from being affected when the transmission speed is reduced due to Problem 1.

Channel bonding is a technology that bundles multiple physical channels into one logical channel. For example, in the wireless LAN IEEE 802.11n standard, a channel bonding technique is employed, and communication is possible with a bandwidth of 40 MHz obtained by bundling two 20 MHz physical channels.

Therefore, when the number of physical channels bundled by channel bonding is N, even if the link speed is reduced due to the problem 1, the link speed can be secured about N times higher than the conventional speed in the same situation. The probability that the required transmission rate can still be secured will increase.

Patent Document 1 discloses a technique for solving Problem 1 in a communication apparatus including a plurality of communication means (for example, PHS communication, 3G communication, and WiMAX communication (“PHS” and “WiMAX” are registered trademarks)). Are listed. The communication device of Patent Literature 1 monitors a network in use (for example, a 3G network), and when the communication quality of the network does not satisfy the required quality, the network to be used is changed to another network that satisfies the required quality (for example, (WiMAX network).

Japanese Patent Publication “Japanese Unexamined Patent Publication No. 2009-124367 (published on June 4, 2009)”

However, the channel bonding technique cannot solve the shortage of transmission speed due to the above problem 2. Insufficient transmission speed due to the communication throughput of Problem 2 occurs, for example, when HTTP is used as a communication protocol (data transfer protocol). Since HTTP uses TCP with a flow control function as a transport protocol, the communication throughput decreases when the round trip time becomes long due to the length of the network path and the delay in each node on the network path. Therefore, even if the bandwidth on the playback device side is increased by channel bonding and a sufficient link speed is secured, the shortage of transmission speed cannot be solved. Further, even when the communication throughput decreases due to insufficient processing capability of network devices such as a distribution server that distributes / relays moving image content, it is clear that the technology cannot solve the insufficient transmission speed.

Also, it is clear that the shortage of the transmission speed due to the above problem 2 cannot be solved for the same reason even using the technique of the above-mentioned Patent Document 1.

The present invention has been made in view of the above problems, and its main purpose is to realize a content acquisition device that can stably acquire content without causing a shortage of transmission speed even when the communication throughput is low. There is to do.

In order to solve the above problems, the content acquisition device according to the present invention is a content acquisition device that acquires content data from a distribution server. In the content acquisition device, the content data indicating the data amount of the content data per unit time Reading means for reading out the metadata about the content, setting means for setting the value of N indicating the number of logical channels used for acquiring the content data based on the data amount information, and the content data are time-divided Acquisition control means for controlling the acquisition section so that the acquisition section acquires each of the plurality of divided data from the distribution server, and the acquisition control means is connected to the acquisition section through N logical channels. Configured to be able to obtain a plurality of the divided data from the distribution server in parallel. And, the setting means, the more the amount of data indicated by the data amount information is large, is characterized by setting a large value of the N.

According to the above configuration, the content acquisition apparatus according to the present invention acquires a plurality of divided data obtained by time-dividing content data from the distribution server in parallel through N logical channels. That is, the content acquisition apparatus according to the present invention can acquire more divided data within the certain period than the number of divided data that can be received within a certain period through one logical channel.

In addition, the content acquisition device according to the present invention sets the value of N to be larger as the amount of content data per unit time is larger, so that the content data is reproduced even when the amount of data is large. It is possible to acquire a sufficient number of pieces of divided data within the predetermined period so that the playback buffer of the playback device does not become empty.

Therefore, the content acquisition apparatus according to the present invention has an effect that content can be stably acquired without causing a shortage of transmission speed even when the throughput of communication with the distribution server is low.

In order to solve the above problems, a content acquisition method according to the present invention is a content acquisition device that acquires content data from a distribution server, and the content acquisition device includes an acquisition control unit, a reading unit, and a setting unit. In the method, the reading unit reads out data amount information indicating the data amount of the content data per unit time from the metadata related to the content data, and the setting unit acquires the content data. A setting step for setting the number N of logical channels to be used based on the data amount information read in the reading step; and the acquisition control means includes a plurality of divided data in which the content data is time-divided The acquisition unit so that the acquisition unit acquires each from the distribution server An acquisition control step for controlling, wherein the acquisition control means causes the acquisition unit to acquire a plurality of the divided data from the distribution server in parallel through the N logical channels in the acquisition control step. The setting means sets the value of N larger as the data amount indicated by the data amount information is larger in the setting step.

According to the above configuration, the content acquisition method according to the present invention has the same effects as the content acquisition device according to the present invention.

In order to solve the above-described problem, the content acquisition device according to the present invention acquires, from a distribution server, content data composed of N different types of components from a distribution server. The detecting means for detecting that the number of the formats is N by referring to the content data, and the content data is divided for each format so that the acquisition unit acquires each of the divided data from the distribution server. An acquisition control means for controlling the acquisition unit, wherein the acquisition control means is configured to allow the acquisition unit to acquire a plurality of the divided data from the distribution server in parallel through N logical channels. It is characterized by being.

According to the above configuration, the content acquisition apparatus according to the present invention acquires content data from a distribution server by acquiring data of components in different formats through different logical channels. That is, the content acquisition apparatus according to the present invention can acquire more data of each component within a certain period of time than acquiring all N components through one logical channel.

As described above, the content acquisition device of the present invention has an effect that content can be acquired stably without causing a shortage of transmission speed even when the throughput of communication with the distribution server is low.

It is the figure which showed the structure of the reproducing | regenerating apparatus which concerns on embodiment of this invention. It is the figure which showed the whole structure of the delivery system which concerns on embodiment of this invention. FIG. 2 is a diagram illustrating an example of MPD (Media Presentation Description) data referred to by the playback apparatus of FIG. 1. (A) is a flowchart showing the operation of the playback apparatus of FIG. 1, and (b) is a flowchart showing an example of a specific operation of the step of determining the media segment reception schedule in the flowchart of (a). It is. It is the figure which showed the structure of the reproducing | regenerating apparatus which concerns on another embodiment of this invention. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. FIG. 6 is a diagram illustrating another example of MPD (Media Presentation Description) data referred to by the playback apparatus in FIG. 5. FIG. 5 is a flowchart showing another example of the specific operation of the step of determining the media segment reception schedule in the flowchart of FIG. FIG. 6 is a diagram schematically illustrating an example of a time schedule for the playback apparatus of FIG. 5 to receive a plurality of media segments for each logical channel. FIG. 6 is a diagram schematically illustrating an example of a time schedule for the playback apparatus of FIG. 5 to receive a plurality of media segments for each logical channel. It is the figure which showed the structure of the reproducing | regenerating apparatus which concerns on another embodiment of this invention. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. 12 is a flowchart illustrating an example of an operation in which the playback device of FIG. 11 determines a media segment reception schedule. It is a flowchart which shows an example of the specific operation | movement of the physical channel allocation process step in the flowchart of FIG. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. It is the figure which showed an example of MPD (Media Presentation Description) data which the reproducing | regenerating apparatus of FIG. 11 refers. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. It is the figure which showed the structure of the reproducing | regenerating apparatus which concerns on another embodiment of this invention. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. It is the figure which showed the structure of the reproducing | regenerating apparatus which concerns on another embodiment of this invention. It is the figure which showed the whole structure of the delivery system which concerns on another embodiment of this invention. It is the figure which showed the whole structure of the conventional delivery system.

[Embodiment 1]
A distribution system according to an embodiment of the present invention will be described with reference to FIGS. In the distribution system of the present embodiment, the following description will be made assuming that 3GPP AHS (Adaptive HTTP Streaming) is used as a distribution method.

FIG. 1 is a diagram illustrating an overall configuration of a playback apparatus according to the present embodiment, and FIG. 2 is a diagram illustrating an overall configuration of a distribution system 1 according to the present embodiment.

As shown in FIG. 2, the distribution system 1 is a system including a playback device 100, a distribution server 300, and a network storage server (NAS) 400. Further, the playback device 100 and the distribution server 300 are connected to the Internet NW, and the distribution server 300 and the NAS 400 are communicably connected.

Hereinafter, the playback device 100, the distribution server 300, and the NAS 400 will be described.
(Reproducing apparatus 100)
The playback device 100 plays back video content received from the distribution server 300. As illustrated in FIG. 1, the playback device 100 includes a communication control unit 110, a playback unit 120, a storage unit 130, and a network I / F 140. Specific examples of the playback apparatus 100 include mobile devices such as smartphones.
(Communication control unit 110)
The communication control unit 110 is a unit obtained by dividing a media segment (encoded data of video content every predetermined time (10 seconds in the present embodiment) through one or more HTTP connections (logical channels), hereinafter referred to as “MS”. The network I / F 140 is controlled so as to receive the encoded data of the video content from the distribution server 300 in units, and the received media segment is buffered in the storage unit 130.

The communication control unit 110 determines the number of HTTP connections used to receive the encoded data of the video content, the bit rate (data amount information) of the video content, and the effective average speed of the latest communication with the distribution server 300. And is determined based on the above.

The communication control unit 110 recognizes the effective average speed of the latest communication as follows. That is, the communication control unit 110 repeats the calculation of the average reception effective speed while receiving the video content from the distribution server 300. More specifically, the communication control unit 110 performs one calculation of the average effective speed as follows. That is, the communication control unit 110 periodically measures the effective speed, and calculates the average value of the measured effective speed as the effective speed average.

Then, the communication control unit 110 updates the effective speed information (the initial value is the bit rate of the video content) recorded in the storage unit 130 by the effective speed average calculated most recently. The communication control unit 110 recognizes the average effective speed of the latest communication by referring to the effective speed information recorded in the storage unit 130.
(Playback unit 120)
The playback unit 120 displays the video content on the display unit 150 by reading out the media segments buffered in the storage unit 130 in order of the time to be played back, and performing decoding and playback.
(Storage unit 130)
The storage unit 130 is a recording medium that stores various data such as MPD data (metadata) related to each media segment constituting the video content and the video content.
(Network I / F140)
The network I / F 140 transmits / receives data to / from the server 300.
(Display unit 150)
The display unit 150 is a display that displays video content.
(Distribution server 300)
The distribution server 300 distributes the video content recorded in the NAS 400 to the playback device 100 in units of media segments through one or more HTTP connections.
(NAS400)
The NAS 400 is a network storage that holds MPD data related to each media segment and video content constituting the video content.
(Details of MPD data)
Next, details of the MPD data described above will be described below with reference to FIG. FIG. 3 is a diagram showing a specific example of MPD data held by the NAS 400 and referred to by the playback apparatus 100 to determine the number of HTTP connections.

As shown in FIG. 3, MPD data is markup language format data having “MPD” as a root element. The value of the attribute “minBufferTime” of the MPD start tag indicates the initial buffer amount, and the value of the attribute “baseUrl” indicates the base URL of the video content.

In addition, “Period” which is a sub-element of “MPD” is played back in a period (period) starting from the time indicated by the attribute “start” (in the example of FIG. 3, 0 seconds, 1800 seconds, and 3600 seconds from the start of playback). This indicates that the information regarding the video to be written is described in the range surrounded by the corresponding Period start tag and end tag.

Specifically, in the range surrounded by the Period start tag and the end tag, one or more sub-elements “Representation” are described, and the range surrounded by the Representation start tag and the end tag includes the corresponding period. Information about media segments that are candidates for playback by the playback apparatus 100 is described. In addition, the value of the attribute “mimeType” of the representation start tag indicates the type of media segment that is a candidate for playback, and the value of attribute “bandwidth” is for receiving media segments that are candidates for playback sequentially and streaming playback. Indicates the required bit rate.

In the example of the MPD data 5a in FIG. 3, only one sub-element “Representation” is described in the range surrounded by <Period start = “PT0S”> and </ Period>, and the attribute “bandwidth” Is “1024000”, and if the playback device 100 has a network bandwidth of 1 Mbps, the media segments in the section are sequentially played back without interruption for 1800 seconds from the playback start time. become.

Specifically, at most one sub-element “SegmentInfo” is described in the range surrounded by the representation start tag and the end tag. The value of the attribute “duration” of the SegmentInfo start tag indicates the playback time of each media segment that is sequentially played back during the above period, and indicates 10 seconds in the MPD data 5a.

The range enclosed by the SegmentInfo start tag and end tag includes at most one sub-element “InitialisationSegmentURL” and the number of media segments to be played back during the above period in the playback device 100 (180 in the MPD data 5a). The sub-element “Url” is described. The value of the attribute “sourceURL” of the element “Url” indicates the file name of the media segment to be reproduced. Further, the value of the attribute “sourceURL” of the element “InitialisationSegmentURL” indicates the file name of the initialization segment.
(Operation of the playback apparatus 100)
Next, an operation in which the playback apparatus 100 receives video content will be described below with reference to FIG. FIG. 4A is a flowchart showing the above operation, and FIG. 4B is a flowchart showing a specific operation of the playback device 100 in step S2 during the above operation. In the following description, video content to be received will be referred to as target video content.

As shown in FIG. 4A, the playback device 100 receives MPD data related to the target video content from the server 300 (step S1).

Specifically, the communication control unit 110 of the playback apparatus 100 transmits a request for MPD data regarding the target video content to the server 300 via the network I / F 140. The server 300 reads MPD data corresponding to the received request from the NAS 400 and transmits it to the playback device 100.

After the process of step S1, the communication control unit 110 analyzes the received MPD data, and for each media segment of the i-th (i: initial value 1) period (target period) constituting the target video content, A reception schedule is determined (step S2).

Specifically, the communication control unit 110 converts the number of HTTP connections (number of logical channels) N used to receive the media segment of the target period into the bit rate and effective speed information of the media segment of the target period. Determine based on (step S11)
More specifically, the communication control unit 110 confirms the bit rate of the media segment of the target period from the value of the attribute “bandwidth” of the sub-element “Representation” of the i-th element “Period” from the top in the MPD data. To do. Then, the communication control unit 110 calculates the number of logical channels N from the equation N = ROUNDUP (“bit rate” ÷ “value indicated by effective speed information (bit rate that is an initial value or average value of the latest effective speeds)”. To decide.

In the above formula, ROUNDUP (x) is a function that rounds up the decimal point of the argument x. As can be seen from the above equation, the larger the bit rate, the greater the number of logical channels.

After step S11, the communication control unit 110 causes the playback apparatus 100 to receive a multiple of 7 + jth media segment from the top through the jth (j: each integer value from 1 to N) logical channel. A logical channel for transmitting a transmission request for the media segment is determined (step S12). The transmission order of a plurality of transmission requests transmitted through the jth (j: each integer value from 1 to N) logical transmission order is such that the transmission request of the media segment closer to the head is preferentially transmitted. Become.

In step S12, the communication control unit 110 calculates the number of media segments for which a logical channel is to be determined with reference to the MPD data. Specifically, the communication control unit 110 represents the time represented by the attribute “start” of the element “Period” corresponding to the target period and the attribute “start” of the element “Period” corresponding to the period immediately after the target period. The difference (period) between the time and the second is calculated. Then, the communication control unit 110 calculates a value obtained by dividing the period by the value of the attribute “duration” of the element “SegmentInfo” corresponding to the target period as the number of media segments for which the logical channel is to be determined.

As an example of a case where 180 media segments in the first period of FIG. 3 are received through two logical channels, the communication control unit 110 transmits Seg-1.3gp, Seg-3.3gp, It is determined that the transmission request of the media segment is transmitted to the distribution server 300 in the order of Seg5-3.gp. In addition, the communication control unit 110 determines to transmit the transmission request for the media segment to the distribution server 300 in the order of Seg-2.3gp, Seg-4.3gp, Seg6-3.gp,... Through the second logical channel. To do.

After determining the reception schedule of the media segment of the target period in step S2, the communication control unit 110 receives the media segment from the distribution server 300 through each logical channel in the order according to the reception schedule (step S3). Note that the communication control unit 110 periodically measures the effective reception speed during the period of step S3, and updates the effective speed information in the storage unit 130 to the average value of the effective speeds measured during the period of step S3.

The communication control unit 110 supplies the received media segment to the playback unit 120 in order of the time to be played back (step S4).

After step S4, it is determined whether or not the processing of steps S2 to S4 has been performed for all periods described in the MPD data. If it is determined that there is still a period for which the processes of S2 to S4 have not been performed (NO in S5), the process returns to step S2, and the processes of S2 to S4 are executed for the next target period (i + 1th period). On the other hand, when it is determined that the processes of steps S2 to S4 have been performed for all periods (YES in S5), the reception process is terminated.

Note that the playback unit 120 starts playback of the target video content immediately after the communication control unit 110 starts the process of S4 for the first period.

(Advantages of the playback device 100)
As described above, in the playback device 100, the communication control unit 110 reads the bit rate value indicated by the attribute “bandwidth” from the MPD data buffered in the storage unit 130. In addition, the communication control unit 110 acquires each media segment obtained by dividing the entire video content from the distribution server 300. Specifically, the communication control unit 110 acquires a plurality of media segments in parallel in N parallel through N logical channels that can acquire media segments from the distribution server 300 independently in each logical channel. The communication control unit 110 sets the value of N larger as the bit rate value is larger.

In general, even if a sufficient link speed is ensured, with HTTP using TCP as the transport protocol, if the round trip time is large, the amount of data (communication) that can be received within a certain period per logical channel There is a large limit on throughput.

Therefore, when the round trip time is large, when acquiring a plurality of media segments in parallel with a maximum of N parallel through N logical channels, the plurality of media segments are sequentially acquired through one logical channel. More media segments can be acquired within a certain period of time than when doing so.

In addition, the communication control unit 110 sets the value N to be larger as the bit rate value is larger, so as long as the bandwidth is sufficient, the larger the bit rate value is, the more media segments are acquired within a certain period. To do.

From the above, the playback device 100 can stably acquire content without causing a shortage of transmission speed even when the round trip time is long and the throughput of communication with the distribution server is low.

[Embodiment 2]
Next, a distribution system according to another embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a diagram illustrating the overall configuration of the playback apparatus according to the present embodiment, and FIG. 6 is a diagram illustrating the overall configuration of the distribution system 1A according to the present embodiment.

As shown in FIG. 5, the distribution system 1A is a system including a playback device 100A, two distribution servers 300-1 and 300-2, and a network storage server (NAS) 400. In addition, the playback apparatus 100 and the two distribution servers 300-1 and 300-2 are connected to the Internet NW, and the two distribution servers 300-1 and 300-2 are connected to the NAS 400 so as to communicate with each other. .

Since the two distribution servers 300-1 and 300-2 and the NAS 400 are the same as the distribution server 300 described in the first embodiment, the configuration of the playback device 100A will be described here.
(Reproducing apparatus 100A)
The playback device 100A plays back the video content received from the two distribution servers 300-1 and 300-2. As illustrated in FIG. 1, the playback device 100A includes a communication control unit 110a, a playback unit 120, a storage unit 130, a network I / F 140, and a display unit 150.

Since the reproduction unit 120, the storage unit 130, the network I / F 140, and the display unit 150 have been described in the first embodiment, the communication control unit 110a will be described here.
(Communication control unit 110a)
The communication control unit 110a receives encoded data of video content from the distribution server in units of media segments through one or more HTTP connections (logical channels). The communication control unit 110a receives the media segment from either the distribution server 300-1 or the distribution server 300-2 for each media segment obtained by dividing the video content based on a reception schedule described later.

The communication control unit 110a determines the number of HTTP connections used for receiving encoded data of the video content, the bit rate of the video content, and the latest communication between the two distribution servers 300-1 and 300-2. Is determined based on the average effective speed.

Note that the communication control unit 110a repeats the calculation of the average effective communication speed in the same manner as the communication control unit 110 of the first embodiment. However, in the present embodiment, since the distribution system 1 includes two distribution servers 300-1 and 300-2, the communication control unit 110a includes each of the two distribution servers 300-1 and 300-2. The average effective speed of communication is calculated.

Then, the communication control unit 110a calculates the effective speed of communication with the distribution server 300-1 that has recently calculated the two effective speed information (the initial value is the bit rate of the video content) recorded in the storage unit 130, respectively. The update is performed based on the average and the average effective speed of communication with the distribution server 300-2 calculated most recently.

(About MPD data)
Next, MPD data referred to by the playback apparatus 100A for determining the number of HTTP connections in the present embodiment will be described below with reference to FIG. FIG. 7 is a diagram showing a specific example of MPD data referred to by the playback device 100A.

As shown in FIG. 7, the data structure of MPD data is substantially the same as the data structure of MPD data referred to by the playback apparatus 100 according to the first embodiment, but differs in the following points.

That is, the attribute “BaseURL” is not described in the MPD start tag of the MPD data. Instead, the element “BaseURL” is described for the number of distribution servers included in the distribution system 1 at the beginning of the range surrounded by the MPD start tag and the end tag of the MPD data. The base URL of the distribution server is described in the range surrounded by the BaseURL start tag and end tag.

In the example of MPD data 5b in FIG. 7, since the number of distribution servers included in the distribution system 1 is two distribution servers 300-1 and 300-2, two elements “BaseURL” are described. The base URL of the distribution server 300-1 and the base URL of the distribution server 300-2 are described in the ranges surrounded by the BaseURL start tag and the end tag, respectively.

The base URL surrounded by the BaseURL tag is used for recognizing the location of the distribution server that distributes the video content to be reproduced by the reproduction apparatus 100A.

(Operation of playback apparatus 100A)
Next, the operation in which the playback apparatus 100A receives video content will be described below with reference to FIG. 4 and FIGS. FIG. 8 is a flowchart showing a specific operation of the playback device 100A in step S2 of the flowchart of FIG.

FIG. 9 and FIG. 10 are diagrams illustrating the relationship graph between the time for receiving the media segment of the period through each logical channel and the most recent effective speed average for each of the three consecutive periods. In each figure, squares with 1 to 9 schematically indicate media segments. In each figure, a media segment with a shorter time to be played within the same period is given a smaller number.

Note that the operations in steps S1, S4, and S5 in FIG. 4A performed by the playback device 100A are the same as the operations performed by the playback device 100 according to the first embodiment. Only the operation of S3 will be described.

As shown in FIG. 8, the step S2 is specifically subdivided into sub-steps S21 to S23.

First, the communication control unit 110a sets the number of elements <BaseURL> included in the MPD data received in S1 as the default number of HTTP connection connections (number of logical channels) N used to receive video content. (S21). That is, when the MPD data 5b is received in S1, the communication control unit 110a sets the default number of logical channels to 2.

In S21, the communication control unit 110a sets the URLs of the N distribution servers corresponding to the N logical channels on a one-to-one basis in the range surrounded by the BaseURL start tag and the end tag. Recognize by referring to the URL. That is, when MPD data 5b is received, the communication control unit 110a sets the URLs of the two distribution servers (distribution servers 300-1 and 300-2) corresponding to the two logical channels to “http: //www1.exsample. com / "and" http://www2.exsample.com/ ".

After the process of step S21, the communication control unit 110a corrects the number of logical channels based on the most recent effective speed average for each distribution server and the bit rate of the video content (step S22).

The communication control unit 110a adds a logical channel when the total value of the most recent effective speed average of each logical channel is lower than the bit rate of the video content, for example, as in the relation graphs in the middle stage of FIG. 9 and FIG. More specifically, the communication control unit 110a communicates with the distribution server having the smaller number of HTTP connections with the playback device 100 out of the two distribution servers (distribution servers 300-1 and 300-2). To establish a new HTTP connection (logical channel). Then, the communication control unit 110a determines whether or not the total value of the assumed effective speeds is equal to or higher than the video content bit rate. Here, the communication control unit 110a sets the most recent effective speed average as the value of the assumed effective speed of the default logical channel, and sets a predetermined value as the value of the assumed effective speed of the added logical channel. The predetermined value may be a difference value obtained by subtracting the total value of the effective speed averages from the bit rate of the video content. Further, the predetermined value may be an average of the latest effective speeds in communication with a distribution server in which an HTTP connection is newly established.

When the communication control unit 110a determines that the total value of the assumed effective speeds is less than the bit rate of the video content, the communication control unit 110a further creates a new one with the distribution server having the smaller number of HTTP connections with the playback device 100. Establish an HTTP connection. A new HTTP connection is established until the total value of the assumed effective speeds exceeds the bit rate of the video content.

On the other hand, the communication control unit 110a decreases the logical channel by one when the total value of the latest average effective speed exceeds the bit rate of the video content greatly (that is, more than a predetermined threshold). For example, the communication control unit 110a disconnects one HTTP connection with the distribution server with the smallest average effective speed among the plurality of distribution servers included in the distribution system 1A.

After step S22, the communication control unit 110a determines, for each of the N logical channels corrected in step S22, which media segment is received through the logical channel based on the most recent effective speed average of each logical channel. (Step S23). Hereinafter, a specific algorithm in step S23 will be described.

The communication control unit 110a calculates, for each of the _N logical channels CH ₁ to CH _N , an estimated reception time T _k per media segment through the logical channel CH _k . Specifically, T _k is calculated by dividing the amount of data per media segment by the assumed effective speed ES _k . More specifically, since the data amount per media segment is equal to the product of the value B of the attribute “bandwidth” and the value D of the attribute “duration”, T _k = B × D ÷ ES _k .

The communication control unit 110a performs the following processing for each m from 1 to M (M: the number of media segments of the target period).

That is, the communication control unit 110a determines that the minimum value among the function values of the following N MAX functions (MAX function 1 to MAX function N) is MAX function L: MAX (SUM ₁ (m−1), SUM ₂ , SUM _L (m−1) + T _k ,..., SUM _N (m−1)), it is determined to receive the m th media segment through the logical channel CH _L. .
MAX function 1: MAX (SUM ₁ (m−1) + T ₁ , SUM ₂ (m−1),..., SUM _N (m−1))
MAX function 2: MAX (SUM ₁ (m−1), SUM ₂ (m−1) + T ₂ ,... SUM _N (m−1))
...
MAX function N: MAX (SUM ₁ (m−1), SUM ₂ (m−1),... SUM _N (m−1) + T _N ))
When there are a plurality of MAX functions having a minimum function value, there are a plurality of logical channel candidates used for receiving the m-th media segment. In this case, the communication control unit 110a determines to receive the m-th media segment through the logical channel CH _L having the largest average effective speed among the plurality of logical channel candidates.

In addition, the communication control unit 110a stores the value of SUM _L (m−1) + _{TL in} the variable SUM _L (m), and variables SUM ₁ (m) to SUM _L-1 (m), SUM _{L + 1.} ( _M ) to SUM _N (m) are the values of SUM ₁ (m-1) to SUM _L-1 (m-1) and SUM _{L + 1} (m-1) to SUM _N (m-1), respectively. Is stored. The communication control unit 110a sets the values of SUM ₁ (0) to SUM _N (0) to 0 in advance. Further, the above-described MAX function is a function having the maximum value among the N arguments as a function value. The operation of the algorithm will be described below with reference to FIGS. 9 and 10 with two specific examples.
(Specific example 1)
9 is a graph showing which media segment is received through which logical channel of the two logical channels when the number of logical channels (logical CH) is increased to 2 by the process of step S22. is there. This graph is a graph when the most recent effective speed average (ES ₁ , ES ₂ ) of logical CH ₁ and logical CH ₂ is 600 kbps and 300 kbps, respectively, and the content bit rate (BR) is 900 kbps. In the following description, it is assumed that the playback time (D) of each media segment is 10 seconds.

In this case, the communication control unit 110a calculates an assumed reception time T ₁ = 15 and an assumed reception time T ₂ = 30. Then, the communication control unit 110a determines that MAX (SUM ₁ (0) + T ₁ , SUM ₂ (0)) is smaller than MAX (SUM ₁ (0), SUM ₂ (0) + T ₂ ). through CH ₁ decides to receive media segments 1 th. Then, the communication control unit 110a sets the value of SUM ₁ (1) to 15 and sets the value of SUM ₂ (1) to 0.

Next, the communication control unit 110a determines that MAX (SUM ₁ (1) + T ₁ , SUM ₂ (1)) and MAX (SUM ₁ (1), SUM ₂ (1) + T ₂ ) are the same value. , Decide to receive the second media segment through logical CH ₁ with the highest average effective speed average. Then, the communication control unit 110a sets the value of SUM ₁ (2) to 30 and sets the value of SUM ₂ (2) to 0.

Further, the communication control unit 110a determines that MAX (SUM ₁ (2), SUM ₂ (2) + T ₂ ) is smaller than MAX (SUM ₁ (2) + T ₁ , SUM ₂ (2)), and the logic It decides to receive media segments 3 th through CH _2. Then, the communication control unit 110a sets the value of SUM ₁ (3) to 30 and sets the value of SUM ₂ (3) to 30. Similarly, the communication control unit 110a determines which logical channel to receive the media segment for all M media segments of the target period.

With the algorithm described above, the communication control unit 110a receives media segments from each logical channel in the receiving order as shown in the lower relation graph of FIG.
(Specific example 2)
10 is a graph showing which media segment is received through which logical channel of the three logical channels when the number of logical channels (logical CH) is increased to 3 by the process of step S22. is there. In this graph, the most recent effective speed average (ES ₁ to ES ₃ ) of logical CH ₁ to logical CH ₃ is 1 Mbps, 300 kbps, and 200 kbps, respectively, and the content bit rate (BR) is 1.5 Mbps. It is a graph in a case. In the following description, as in the first specific example, it is assumed that the playback time (D) of each media segment is 10 seconds.

In this case, the communication control unit 110a calculates an assumed reception time T ₁ = 15, an assumed reception time T ₂ = 50, and an assumed reception time T ₃ = 75. Then, the communication control unit 110a is configured to execute MAX (SUM ₁ (0), SUM ₂ (0) + T ₂ , SUM ₃ (0)) and MAX (SUM ₁ (0), SUM ₂ (0), SUM ₃ (0). + T ₃ ) is determined to be smaller than MAX (SUM ₁ (0) + T ₁ , SUM ₂ (0), SUM ₃ (0)) and decided to receive the first media segment through logical CH ₁ To do. Then, the communication control unit 110a sets the value of SUM ₁ (1) to 15, and sets the values of SUM ₂ (1) and SUM ₃ (1) to 0. Similarly, the communication control unit 110a determines to receive media segments two and third th through logic CH _1.

When the logical channel used to receive the third media segment is determined to be logical CH ₁ , the value of SUM ₁ (3) is set to 45, and SUM ₂ (3) and SUM ₃ (3) The value is set to 0. The communication control unit 110a includes MAX (SUM ₁ (3) + T ₁ , SUM ₂ (3), SUM ₃ (3)) and MAX (SUM ₁ (3), SUM ₂ (3), SUM ₃ (3) + T _3. ) (MAX ₁ (SUM ₁ (3), SUM ₂ (3) + T ₂ , SUM ₃ (3))) is determined to be smaller, and it is determined to receive the fourth media segment through the logical CH ₂ . Then, the communication control unit 110a sets the value of SUM ₁ (4) to 45, sets the value of SUM ₂ (4) to 50, and sets the value of SUM ₃ (4) to 0. Similarly, the communication control unit 110a determines to receive media segments 5 th and 6 th through logic CH _1.

When the logical channel used to receive the sixth media segment is determined to be logical CH ₁ , the value of SUM ₁ (6) is set to 75 and the value of SUM ₂ (6) is set to 50. , SUM ₃ (6) is set to 0. The communication control unit 110a includes MAX (SUM ₁ (6) + T ₁ , SUM ₂ (6), SUM ₃ (6)) and MAX (SUM ₁ (6), SUM ₂ (6) + T ₂ , SUM ₃ (6). ) Is smaller than MAX (SUM ₁ (6), SUM ₂ (6), SUM ₃ (6) + T ₃ ), and it is determined to receive the seventh media segment through the logical CH ₃ . Similarly, the communication control unit 110a determines which logical channel to receive the media segment for all M media segments of the target period.

With the algorithm described above, the communication control unit 110a receives media segments from each logical channel in the receiving order as shown in the lower graph of FIG.

As can be seen from the above description of the algorithm and FIG. 10, the value of SUM _k (m) (k: 1 to N) is determined from the start of reception through m logical channels according to the above algorithm. The total reception time of the logical CH _k up to the time of receiving the number is shown. The above algorithm is such that the total reception time on the logical channel with the longest total reception time among N logical channels is as short as possible (in other words, the time required to complete reception of all media segments is as short as possible). And so on) to determine the logical channel used to receive the media segment.

After determining the reception schedule of the media segment of the target period in step S2, the communication control unit 110a sends the media segment from the distribution server 300-1 or 300-2 through each logical channel in the order according to the reception schedule. Receive (step S3). Note that the communication control unit 110a periodically measures the effective speed of receiving the media segment from the distribution server 300-1 during the period of step S3, and calculates the effective speed average. Similarly, the communication control unit 110a periodically measures the effective speed at which the media segment is received from the distribution server 300-2 during the synchronization, and calculates the effective speed average. Then, the two effective speed information stored in the storage unit 130 is updated to the two effective speed averages calculated in the period of step S3.

(Advantages of the playback device 100A)
As described above, in the playback device 100A, the communication control unit 110a uses each of the URLs surrounded by the baseURL start tag and the end tag to identify the distribution server that can distribute the video content from the MPD data related to the video content. read out.

The communication control unit 110a determines which of the distribution server 300-1 and the distribution server 300-2 receives the media segment when the two URLs of the distribution server 300-1 and the distribution server 300-2 are read. It can be selected.

Specifically, for each media segment, the communication control unit 110a receives the media segment from the distribution server 300-1, or receives the media segment from the distribution server 300-2 for communication with the distribution server 300-1. It is determined based on the assumed effective speed and the assumed effective speed of communication with the distribution server 300-2.

That is, the communication control unit 110a determines the reception schedule of each media segment so as to receive more media segments from the distribution server having the larger assumed effective speed.

Accordingly, the playback device 100A has an effective speed when the effective speed of communication between the distribution server and the playback device 100A decreases due to an overload of any of the distribution servers 300-1 and 300-2. A large amount of divided data is acquired from the other distribution server having a relatively high value. As a result, the playback device 100A can stably acquire video content without causing a shortage of transmission speed even when one of the distribution servers is overloaded.

[Embodiment 3]
Next, a distribution system according to another embodiment of the present invention will be described with reference to FIGS.

FIG. 11 is a diagram illustrating the overall configuration of the playback apparatus according to the present embodiment, and FIG. 12 is a diagram illustrating the overall configuration of the distribution system 1B according to the present embodiment.

As shown in FIG. 12, the distribution system 1B is a system that includes the playback device 100B, the proxy server 200 of the playback device 100B, the distribution server 300, and the NAS 400. In addition, the playback device 100B is connected to two different networks NW1 and NW2. The proxy server 200 is connected to the network NW2. The distribution server 300 is connected to the network NW3 and is communicably connected to the NAS 400. A router 250-1 is installed between NW1 and NW3, and a router 250-2 is installed between NW2 and NW3.

That is, as can be seen from FIG. 12, in the distribution system 1B, there are two communication paths between the playback device 100B and the distribution server 300: a communication path via NW1 and a communication path via NW2.

Since the distribution server 300 and the NAS 400 are the same as the distribution server 300 described in the first embodiment, the configuration of the playback device 100B and the proxy server 200 will be described here.
(Reproducing apparatus 100B)
The playback device 100B plays back the video content received from the distribution server 300. As shown in FIG. 11, the playback device 100B includes a communication control unit 110b, a playback unit 120, a storage unit 130, two network I /

Fs

140a and 140b, and a display unit 150.

The reproduction unit 120, the storage unit 130, and the display unit 150 are described in the first embodiment. Since the two network I /

Fs

140a and 140b are the same as the network I / F 140, the communication control unit 110 is used here. Will be described.
(Communication control unit 110b)
The communication control unit 110b controls the two network I /

Fs

140a and 140b so as to receive the encoded data of the video content from the distribution server 300 in units of media segments through one or more HTTP connections (logical channels).

Specifically, the communication control unit 110b receives each media segment from the distribution server 300 via the proxy server 200 via the network I / F 140b, or via the network I / F 140a. Whether to directly receive the media segment from the distribution server 300 is controlled based on a reception schedule to be described later.

The communication control unit 110b determines the number of HTTP connections used for receiving the encoded data of the video content, the bit rate of the video content, and the effective when the communication with the distribution server 300 via the NW1 is performed most recently. It is configured to be determined based on the average speed, the bit rate of the video content, and the average effective speed when communication with the distribution server 300 via the NW 2 is performed most recently. Note that the communication control unit 110b repeats the calculation of the average effective communication speed in the same manner as the communication control unit 110b of the first embodiment.

The communication control unit 110b then communicates the two effective speed information recorded in the storage unit 130 (the initial value is the bit rate of the video content) with the distribution server 300 via the NW 1 most recently. And the effective speed average when the most recent communication with the distribution server 300 via NW2 is performed.
(Proxy server 200)
The proxy server 200 transmits a media segment transmission request to the distribution server 300 and receives the media segment from the distribution server 300 on behalf of the playback device 100B. The proxy server 200 transfers the received media segment to the playback device 100B.
(Communication path between playback device 100B and distribution server)
When playback device 100B directly receives a media segment from distribution server 300, the transmission request for the media segment and the communication path through which the media segment passes are communication paths via NW1. This is because the routing table of the playback device 100B is set so that the communication gateway from the playback device 100B to the distribution server 300 is the router 250-1, and the communication gateway from the distribution server 300 to the playback device 100B is the router. This is because the routing table of the distribution server 300 is set to be 250-1.

On the other hand, when the playback device 100B receives a media segment from the distribution server 300 via the proxy server 200, the transmission request for the media segment and the communication path through which the media segment passes are communication paths via the NW2. This is because the playback device 100B and the proxy server 200 are connected to the same network NW2, and the routing table of the playback device 100B is set so that the gateway for communication from the proxy server 200 to the distribution server 300 is the router 250-2. This is because the routing table of the distribution server 300 is set so that the gateway for communication from the distribution server 300 to the proxy server 200 is the router 250-2.
(About MPD data)
The MPD data referred to by the playback device 100B for determining the number of HTTP connections is the same data as the MPD data 5b. However, since only one distribution server 300 is included in the distribution system 1B, only one element “BaseURL” is described in the MPD data.
(Operation of the playback device 100B)
Hereinafter, the operation of the playback apparatus 100B according to the present embodiment will be described with reference to FIGS. 3, 4, 13, and 14. FIG. FIG. 13 is a flowchart showing a specific operation of the playback device 100B in step S2 of the flowchart of FIG. FIG. 14 is a flowchart showing a specific operation of the playback device 100B in step S43 of the flowchart of FIG. In the following description and drawings, a communication path to an adjacent node starting from the network I / F 140a as a starting point or an end point is a physical CH1, and a communication path to an adjacent node starting from the network I / F 140b is a physical CH2. I will call it.

Similar to the playback device 100A of the second embodiment, the operations in steps S1, S4, and S5 in FIG. 4A performed by the playback device 100B are the same as the operations performed by the playback device 100 according to the first embodiment. Since they are the same, only the operations in steps S2 and S3 will be described here.

As shown in FIG. 13, the process of step S2 is specifically subdivided into sub-processes of steps S41 to S42.

As in step S21 of the second embodiment, the communication control unit 110b uses the number of elements <BaseURL> included in the MPD data received in S1 as the number of default HTTP connections used for receiving video content (logical The number of channels is set as N (S41). That is, when MPD data is received in S1, the communication control unit 110b sets the default number of logical channels to 1.

After the process of step S41, the communication control unit 110b determines the number of logical channels based on the most recent effective speed average with the distribution server 300 and the bit rate of the video content, as in step S22 of the second embodiment. Correction is performed (step S42).

After the process of step S42, the communication control unit 110b assigns each of the N logical channels after the correction in step S42 to one of the physical channels of the playback device 100B (step S43). That is, in the distribution system 1, since there are two physical channels, physical CH1 and physical CH2, each logical channel is assigned to one of the two physical channels. Here, “assigning a logical channel to a physical channel” is equivalent to determining an IP address of an HTTP connection communication source from among different IP addresses assigned to a plurality of network I / Fs. It is.

As shown in FIG. 14, the process of step S43 is specifically subdivided into sub-processes of steps S61 to S72.

The communication control unit 110b selects one logical channel for which a physical channel to be allocated is to be determined (S61). Next, the communication control unit 110b selects one physical channel that is a candidate for assignment to the logical channel selected in S61 (S62). Various methods are conceivable as methods for determining the selection order of candidate physical channels. For example, physical channels may be selected in the order of link speeds. By preferentially selecting a physical channel with a high link speed, for example, when the content bit rate is low, the number of physical channels for communication can be reduced. In this case, since the communication control unit 110b can cut off the power supply to the unused physical channel (network I / F), the playback device 100B can also reduce power consumption.

After step S62, the communication control unit 110b determines whether the physical channel selected in S62 can be assigned to the logical channel selected in S61 (S63). Specifically, the communication control unit 110b can finally communicate directly with the distribution server by communication using the physical channel as a communication path (that is, the physical channel is the playback device 100B). To determine whether it is on the routing route from the distribution server 300 to the distribution server 300).

If it is determined in step S63 that assignment is not possible (no in S63), the process proceeds to step S66, and if it is determined that assignment is possible (yes in S63), the process proceeds to step S64.

In step S64, the communication control unit 110b determines whether the physical channel band selected in step S62 has enough free space to allocate the logical channel selected in step S61. Specifically, the communication control unit 110b, which performs the determination as follows, in the following, the effective rate the number of assigned logical channels to physical channels selected in step S62 as N _d, in the storage unit 130 The average effective speed when the most recent communication via the physical channel recorded as information is performed is denoted as BR _avg .

The communication control unit 110b confirms the link speed of the physical channel selected in step S62. Then, the communication control unit 110b determines whether the value of (N _d +1) × BR _avg is greater than the link speed. If it is determined that the value of (N _d +1) × BR _avg is greater than the link speed, the communication control unit 110b determines that there is not enough space to allocate the logical channel selected in step S61. On the other hand, when the communication control unit 110b determines that the value of (N _d +1) × BR _avg is equal to or less than the link speed, the communication control unit 110b determines that there is enough space to allocate the logical channel selected in step S61.

If it is determined in step S64 that there is no space (no in S64), the process proceeds to step S66, and if it is determined that there is a space (yes in S64), the process proceeds to step S65.

In step S65, the communication control unit 110b assigns the physical channel selected in step S62 to the logical channel selected in step S61, and proceeds to step S67.

On the other hand, in step S66, the communication control unit 110b determines whether there is a physical channel that is not selected in step S62 as a candidate for assignment to the logical channel selected in step S61. If it is determined that there is an unselected physical channel (yes in step S66), the process returns to step S62. On the other hand, when it is determined that there is no unselected physical channel (no in step S66), the process proceeds to step S67.

In step S67, the communication control unit 110b determines whether there is a logical channel that has not been selected in step S61 among the N logical channels. If it is determined that there is an unselected logical channel (yes in step S67), the process returns to step S61. On the other hand, when it is determined that there is no unselected logical channel (no in step S67), the process proceeds to step S68.

In step S68, the communication control unit 110b determines whether there is a logical channel that is not allocated in step S65 among the N logical channels. If it is determined that there is an unallocated logical channel (no in step S68), the process proceeds to step S69.

In step S69, the communication control unit 110b selects one logical channel from which unassigned logical channels should be assigned. Next, the communication control unit 110b selects one physical channel that is a candidate for assignment to the logical channel selected in S69 (S70).

After step S70, the communication control unit 110b determines whether or not there is enough space to allocate the logical channel selected in step S68 in the bandwidth of the physical channel selected in step S69. It is determined by processing (S71).

After step S71, the communication control unit 110b refers to the address information of the proxy server stored in the storage unit 130, so that the address of the proxy server installed in the network to which the physical channel selected in step S70 belongs. Is confirmed (S72). For example, when physical CH2 is selected in step S70, the communication control unit 110b refers to the IP address of the proxy server 200 stored in the storage unit 130.

Then, the communication control unit 110b assigns the physical channel selected in S70 to the logical channel selected in S69, and sets the communication destination of the logical channel in the proxy server whose address is confirmed in S72. That is, the media segment transmission request through the logical channel selected in S69 is transmitted to the distribution server 300 via the proxy server 200, and the media segment transmitted from the distribution server 300 is transmitted via the proxy server 200. Is transmitted to the playback device 100B.

After step S72, the process returns to step S68. If it is determined in step S68 that there is no unallocated logical channel (no in step S68), the process in step S43 is terminated.

After the process of step S43 is completed, the process of step S44 is performed. Since the process of step S44 is the same as the process of step S23 described in the second embodiment, the description thereof is omitted here.

After determining the reception schedule of the media segment of the target period in step S2, the communication control unit 110b receives the media segment from the distribution server 300 through each logical channel in the order according to the reception schedule (step S3). Note that the communication control unit 110b periodically measures the effective speed at which the media segment is received from the distribution server 300 via the network I / F 140a during the period of step S3, and calculates the effective speed average. Similarly, the communication control unit 110b periodically measures the effective speed at which the media segment is received from the distribution server 300 via the network I / F 140b during the synchronization, and calculates the effective speed average. Then, the two effective speed information stored in the storage unit 130 is updated to the two effective speed averages calculated in the period of step S3.

As described above, the operation of receiving the video content by the playback apparatus 100B has been described. As can be seen from the above description, the playback apparatus 100B has a margin in the bandwidth of the physical CH1 on the routing path to the distribution server 300. In some cases, all media segments are received from distribution server 300 using physical CH1 as a communication path. On the other hand, when there is no room in the physical CH1 bandwidth that can directly communicate with the distribution server 300, the playback device 100B receives some media segments from the distribution server 300 using the physical CH1 as a communication path, The remaining part of the media segment is received from the distribution server 300 using CH2 as a communication path.
(Additional notes)
Note that, after it is determined in step S66 that there is no unselected physical channel, the following process may be performed before the process proceeds to step S67.

In other words, if there are a plurality (P) of physical channels that are determined to be assignable in step S63 and that are determined not to be free in step S64, the communication control unit 110b determines in S61. Instead of the logical channel selected in this way, it is determined to receive the media segment using new P logical channels (hereinafter referred to as additional logical channels). At this time, the communication control unit 110b calculates, for each of the P physical channels, a difference value (<BR _avg ) obtained by subtracting N _d × BR _avg from the link speed of the physical channel. Then, the communication control unit 110b assigns the P physical channels to the P additional logical channels on a one-to-one basis.

In this case, in step S44, the communication control unit 110b calculates the reciprocal of the assumed effective speed of the logical channel for each of the plurality of logical channels to which the physical channel is allocated in S65, in the same manner as in step S23. . However, the communication control unit 110b sets the value of the assumed effective speed of the additional logical channel to the difference value calculated for the physical channel assigned to the additional logical channel.

For example, when the physical CH1 link speed is 1 Mbps and a logical channel with an assumed effective speed of 600 kbps has been assigned to the physical CH1, the communication control unit 110b calculates a difference value of 400 kbps for the physical CH1. Then, the communication control unit 110b sets the assumed effective speed of the additional logical channel assigned to the physical CH1 to 400 kbps.

That is, when the same physical channel is assigned to the additional logical channel and a logical channel other than the additional logical channel (normal logical channel), the communication control unit 110b determines the estimated effective speed of the additional logical channel and the normal logical channel. The total of the assumed effective speed is set to match the link speed of the physical channel. Therefore, the playback device 100B can receive the media segment at an effective speed that is substantially close to the link speed of the physical channel (that is, by sufficiently effectively using the bandwidth of the physical channel).
(Advantages of playback device 100B)
As described above, the playback device 100B includes the two network I /

Fs

140a and 140b. In addition, since the playback device 100B becomes a node on the routing path to the distribution server 300, the playback device 100B can receive the media segment directly from the distribution server 300 by HTTP communication, and the distribution server 300 A network I / F 140b that cannot directly receive a media segment from the distribution server 300 by IP communication because it is not a node on the routing path.

The communication control unit 110b receives a media segment directly from the distribution server 300 via the network I / F 140a or relays the proxy server 200 in the same network NW2 as the network I / F 140b via the network I / F 140b. It is possible to select whether to indirectly receive the media segment from the distribution server 300.

Therefore, the communication control unit 110b passes through a network in which no failure occurs even when a failure such as congestion occurs in the network NW1 or the network NW2 and the effective speed of communication via the failed network is reduced. Many media segments can be received.

A conventional client can receive video content only from one communication path even if there are a plurality of communication paths with the server that distributes the video content. This will be described in detail with reference to FIG.

FIG. 22 is a diagram showing an overall configuration of a distribution system including a conventional client and server.

Similar to the playback device 100B, the conventional client refers to the routing table stored in the client when communicating with the server, and the network I / O recorded in the routing table in association with the IP address of the server. Refer to the address of F. On the other hand, unlike the playback apparatus 100B, the conventional client always transmits a video content transmission request directly to the server via the network I / F that refers to the address, and sends the video content to the server via the network I / F. Receive directly from.

In the example of FIG. 22, the IP address of the server is “10.0.3.30”. However, since “10.0.3.30” corresponds to “default” in the client routing table, the network associated with “10.0.3.30”. The address of the I / F is “10.0.1.10”. Normally, the routing table does not change unless there is a change in the network configuration. Therefore, when the client receives video content from the server, the client always passes through the network I / F to which the IP address “10.0.1.10” is assigned. Receive from distribution server via Wi-Fi network. In other words, conventional clients cannot receive video content using both 3G network and Wi-Fi network together, and if the Wi-Fi network fails, It cannot be received stably.

Therefore, the reproducing apparatus 100B has an advantageous effect that cannot be obtained by the conventional client that the video content can be stably received from the distribution server 300 even when a failure occurs in any of the networks.

The distribution system 1B of the third embodiment is a system in which the playback device 100B includes two communication interfaces and includes one proxy server and one distribution server, but the distribution system of the present invention. Is not limited to this.

That is, in the distribution system, for example, the playback device includes three or more communication interfaces, and includes two or more proxy servers and two or more distribution servers. It may be possible to communicate directly via any communication interface, or indirectly via any proxy server.

When the playback device performs communication simultaneously with L (L <M) distribution servers using M communication interfaces, two of the L distribution servers each include two distribution servers. The above communication may be performed using the above communication interface. Specifically, the communication control unit of the playback device communicates directly with the distribution server using a certain communication interface, and indirectly through the proxy server using one or more other communication interfaces. You may communicate with.

[Embodiment 4]
A distribution system according to still another embodiment of the present invention will be described with reference to FIGS. 2, 15 and 16.

FIG. 15 is a diagram showing an overall configuration of the distribution system 1C according to the present embodiment.

As shown in FIG. 15, the distribution system 1C includes a reproduction apparatus 100B, a proxy server 200 of the reproduction apparatus 100B, two distribution servers 300-1, 300-2, a distribution management server 350, and three NAS 400a to 400c. It is a system including

The playback device 100B is connected to two different networks NW1 and NW2. The proxy server 200 and the distribution server 300-2 are connected to the network NW2, and the distribution server 300-2 is connected to be communicable with the NAS 400a.

Similarly, the distribution server 300-1 is connected to the network NW1, and the distribution server 300-1 is connected to be communicable with the NAS 400b.

Furthermore, the distribution management server 350 is connected to the network NW3 and is communicably connected to the NAS 400c. A router 250-1 is installed between NW1 and NW3, and a router 250-2 is installed between NW2 and NW3.

Since the playback device 100B, proxy server 200, and distribution servers 300-1 and 300-2 have already been described in the second or third embodiment, the distribution management server 350 and NAS 400a to 400c will be described here.

(NAS 400a-400c)
The same video content is stored in the NAS 400a and the NAS 400b. On the other hand, the NAS 400c stores two MPD data relating to the same video content.

One MPD data (MPD data for NW1) stored in the NAS 400c includes the value of the attribute “baseURL” of the element “MPD” as the value of the distribution server 300-1 as in the MPD data 5a shown in FIG. Base URL is described. Further, in the other MPD data (MPD data for NW2), the base URL of the distribution server 300-2 is described as the value of the attribute “baseURL” of the element “MPD” as in the MPD data 5c shown in FIG. Has been. The two MPD data are the same except for the value of the attribute “baseURL”.

(Distribution Management Server 350)
Upon receiving the MPD data transmission request for the video content, the distribution management server 350 determines whether the IP address of the device that transmitted the transmission request is an IP address belonging to NW1 or an IP address belonging to NW2, and sends a transmission request. The MPD data for NW to which the IP address of the device that transmitted the message belongs is returned to the device.

(Operation of the playback device 100B)
The operation of the playback device 100B according to the present embodiment is the same as the operation of the playback device 100B according to the third embodiment except for step S1 in FIG.

That is, the communication control unit 110b of the playback device 100B receives the MPD data for NW1 from the distribution management server 350 via NW1, and receives the MPD data for NW2 from the distribution management server 350 via NW2 by relaying by the proxy server 200. Receive.

Then, the communication control unit 110b analyzes the received two MPD data and determines the media segment reception schedule.

(Additional notes)
In this embodiment, the MPD data for NW1 and the MPD data for NW2 are stored in the NAS 400c. However, one MPD data such as the MPD data 5b in FIG. 7 may be stored in the NAS 400c. . That is, as shown in MPD data 5b of FIG. 7, the base URL of the NW1 distribution server 300-1 and the base URL of the NW2 distribution server 300-2 are described in a range surrounded by the baseURL start tag and end tag. The MPD data may be stored in the NAS 400c.

In this case, the playback device 100B performs exactly the same operation as the playback device 100B of the distribution system 1B according to the third embodiment.

(Advantages of distribution system 1C)
In the distribution system 1C, distribution servers (300-1, 300-2) are installed in each of a plurality of different networks (NW1, NW2). Each distribution server can read out the same video content media segment as the other distribution servers from the NAS (400a, 400b) on the same network and distribute it to the playback device 100B.

On the other hand, in the distribution system 1A, a plurality of distribution servers 300-1 and 30-2 are installed in the same network. Each distribution server shares one NAS 400 on the same network, reads a media segment of video content from one NAS 400, and distributes it to the playback device 100B.

Therefore, in the distribution system 1A, when the storage server is overloaded, the distribution of video content becomes unstable because the storage server becomes a bottleneck and the effective speed is lowered when receiving a media segment from any distribution server. . On the other hand, in the distribution system 1C, even if a storage server installed in a certain network is overloaded, the playback device can receive distribution of video content from a distribution server in another network. The video content distribution does not immediately become unstable due to overloading.

From the above, the distribution system 1C can distribute video content from the distribution server to the playback device more stably.

As mentioned above, although each embodiment of this invention has been described, this invention is not limited to each embodiment mentioned above.

That is, in Embodiments 1 to 4, the video content distributed by the distribution system is exemplified as video content configured by a single representation (Representation) having a bit rate of 1 Mbps. The present invention can also be applied to distribution of video content composed of

For example, video content in which each of a plurality of different types of media components such as audio data, video data, and text data (components) is represented, and each of the base layer and the enhancement layer (components) is represented as a representation. The present invention can also be applied to distribution of video content.

A distribution system 1d configured as shown in FIG. 17 that multicasts video content including audio data and video data as representations is also included in the scope of the present invention.

The playback device 100B included in the distribution system 1D receives the MPD data of the video content from the distribution server, and confirms from the contents of the MPD data that the video content is a video content in which each of the audio data and the video data is represented. To do.

Then, the playback device 100B requests multicast distribution of audio data (divided data) from the multicast-compatible router 250'-1 and requests multicast distribution of video data from the multicast-compatible router 250'-2. Specifically, the playback device 100B transmits a request to join a multicast group used for multicast distribution of audio data to the multicast router 250'-1, and the playback device 100B is used for multicast distribution of video data. A request to join the multicast group is transmitted to the router 250′-2.

Thereby, the distribution server 300A transmits the audio data of the video content to the router 250'-1, and the router 250-1 transfers the audio data to the playback device 100. Further, the distribution server 300A transmits the video data of the video content to the router 250'-2, and the router 250'-2 transfers the audio data to the playback device 100.

Therefore, since the playback device 100B receives video content using a plurality of physical channels in combination, the playback device 100B can receive video content more stably.

In the distribution system 1, the distribution server 300A may be a distribution server that distributes video content in which each of the base layer and the enhancement layer is represented. In this case, the playback device 100B may request, for example, the base layer multicast distribution to the router 250'-1 and the expansion layer multicast distribution to the multicast compatible router 250'-2.

Further, the video content may be distributed using a distribution system 1E as shown in FIG. 19 instead of the distribution system 1D.

In the distribution system 1E, the distribution server includes two types of servers, a distribution server 300-1 that is a broadcast content server and a distribution server 300-2 that is a communication content server. The layer is transmitted on the broadcast wave, and the distribution server 300-2 transmits the extension layer to the playback device by communication via the NW.

The playback device 100C shown in FIG. 18 included in the distribution system 1E receives the MPD data of the video content from the distribution server 300-1 through the tuner (reception interface) 160, and the video content includes each of the base layer and the extension layer. It is confirmed from the contents of the MPD data that the video content is a representation. Further, the playback device 100C confirms the base URL of the distribution server 300-2 that distributes the enhancement layer from the contents of the MPD data.

Therefore, since the playback device 100C receives video content by using the two physical channels of the broadcast network and the IP network in combination, the playback device 100C can receive the video content more stably.

(Other)
In each embodiment, the most recent effective speed average is recorded as the execution speed information and is assumed to be the assumed effective speed. However, the past effective speed average that is not the most recent may be used as the assumed effective speed of the leading period. . Further, the bit rate of the video content may be used as the assumed effective speed of the leading period.

Also, the present invention can be realized by a distribution system 1F in which the distribution system 1 of the first embodiment is partially changed as shown in FIG. That is, the present invention is realized as a distribution system 1F in which a playback device 100D in which the communication control unit 110 is replaced with the communication control unit 110b is installed instead of the playback device 100, and a proxy server 200 (public proxy) is installed on the Internet NW. can do.

That is, the communication control unit 110b may be configured to be able to select whether to receive a media segment from the distribution server 300 via the public proxy 200 or to receive a media segment directly from the distribution server 300.

In this case, as in the third embodiment, the communication path from the distribution server 300 to the playback device 100D via the public proxy 200 is different from the routing path from the distribution server 300 to the playback device 100D. Accordingly, the playback device 100D can receive video content from the other path when the effective speed of communication that passes through either path decreases, so that the video content can be received more stably. it can.

In the first to fourth embodiments, the playback device uses HTTP communication in order to receive video content from the distribution server. However, in each of the above embodiments, the playback device transmits another communication protocol such as an FTP protocol from the distribution server. May be used to receive video content. In this case, for example, the value of the attribute “baseURL” in the MPD data 5a may be the base URL of the distribution server starting from “ftp: //”.

The present invention can be realized not only as a video playback device for playing back video content, but also as a sound playback device for playing back audio content (content including information on the playback time required to play back the entire data). it can.

(Program, storage medium)
Each block of the playback apparatus 100 (100A, 100B) may be realized by hardware by a logic circuit formed on an integrated circuit (IC chip), or by software using a CPU (Central Processing Unit). It may be realized.

In the latter case, the playback device 100 (100A, 100B) includes a CPU that executes program instructions for realizing each function, a ROM (Read Only Memory) that stores the program, and a RAM (Random Access Memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. The object of the present invention is to record the program code (execution format program, intermediate code program, source program) of the control program of the playback apparatus 100 (100A, 100B), which is software that realizes the above-described functions, in a computer-readable manner. This can also be achieved by supplying the recorded medium to the playback apparatus 100 (100A, 100B) and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. IC cards (including memory cards) / optical cards, semiconductor memories such as mask ROM / EPROM / EEPROM (registered trademark) / flash ROM, or PLD (Programmable logic device) and FPGA (Field Programmable Gate Logic circuits such as (Array) can be used.

Further, the program code may be supplied to the playback device 100 (100A, 100B) via a communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network (Virtual Private Network), telephone line network, mobile communication network, satellite communication network, etc. can be used. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even in the case of wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR ( It can also be used by wireless such as High Data Rate, NFC (Near Field Communication), DLNA (Digital Living Network Alliance), mobile phone network, satellite line, and terrestrial digital network.

In addition, it should be thought that embodiment disclosed here is an illustration and restrictive at no points. The scope of the present invention is shown not only by the above description but also by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

As described above, the content acquisition device according to the present invention is a content acquisition device that acquires content data from a distribution server, and includes data amount information indicating the data amount of the content data per unit time as metadata about the content data. Reading means for reading out the content data; setting means for setting a value of N indicating the number of logical channels used for acquiring the content data based on the data amount information; Acquisition control means for controlling the acquisition section so that the acquisition section acquires each of the divided data from the distribution server, and the acquisition control means is connected in parallel to the acquisition section through N logical channels. A plurality of the divided data can be acquired from the distribution server. The setting means is configured to set the value of N to be larger as the data amount indicated by the data amount information is larger. For example, the acquisition unit includes M reception interfaces. The acquisition control means is configured to control the M reception interfaces so that each of the M reception interfaces acquires the divided data, and the setting means is controlled by the acquisition control means. Regardless of the value of M, which is the number of reception interfaces to be controlled, it can be realized as a content acquisition apparatus that sets the value of N.

In the content acquisition device according to the present invention, the acquisition unit is a communication unit capable of communicating with the distribution server, and the acquisition control unit is configured such that the communication unit routes the logical channel. The communication unit is configured to control the communication unit so as to acquire the divided data by IP communication, and the acquisition control unit supplies the divided data to each of the plurality of divided data. Setting the communication destination in the proxy server of the content acquisition device causes the communication unit to acquire from the distribution server via the proxy server, or setting the communication destination in the distribution server to the communication unit It is desirable to be able to select whether to obtain directly from the distribution server.

Here, when the content acquisition apparatus causes the communication unit to acquire the divided data from the distribution server via the proxy server, and the divided data distribution path when the communication unit directly acquires the divided data from the distribution server. It is clear that the delivery route is generally different.

Therefore, the content acquisition apparatus allocates the other distribution path to N logical channels and acquires divided data from the other distribution path when a delay or failure occurs in one of the two distribution paths. Can do.

As a result, the content acquisition apparatus has the further effect that it can acquire the content more stably without causing a shortage of transmission speed.

In order to achieve the above-described effect, in the content acquisition device according to the present invention, the communication unit includes a plurality of communication interfaces, and the acquisition control unit transmits the divided data from the distribution server by IP communication. The first communication interface that can be directly acquired allows the first communication interface to acquire the divided data, or the communication interface that cannot directly acquire the divided data from the distribution server through IP communication. The second communication interface in which the proxy server exists in the same network as the interface may be configured to select whether the divided data is acquired from the distribution server via the proxy server.

In the content acquisition device according to the present invention, the acquisition control unit is configured to transmit the communication interface and the distribution for each of the communication interfaces corresponding to the first communication interface or the second communication interface among the plurality of communication interfaces. It is configured to measure the effective speed of communication with the server, and the acquisition control means is configured to cause the communication interface having a relatively large effective speed to acquire a relatively large amount of divided data. It is desirable that

According to the above configuration, the content acquisition device according to the present invention efficiently uses a plurality of communication paths from each communication interface to the distribution server, and acquires more divided data from the distribution server per fixed period. be able to.

In the content acquisition apparatus according to the present invention, the acquisition unit is a communication unit capable of communicating with the distribution server, and can distribute the content data from metadata regarding the content data. Second reading means for reading distribution server specifying information for specifying a distribution server is provided, wherein the acquisition control means is configured to perform the division by the communication unit when a plurality of the distribution servers are specified from the distribution server specifying information. A distribution server as a data acquisition destination can be selected, and the acquisition control unit distributes the divided data to the communication unit for each of the plurality of divided data. The acquisition control means is configured to determine whether to acquire from a server based on an effective speed of communication with each distribution server. , From the distribution server the effective speed is relatively large, it is desirable that a relatively large amount of the divided data is configured to acquire to the communication unit.

According to the above configuration, in the content acquisition device according to the present invention, the effective speed of communication between the distribution server and the content acquisition device decreases due to any one of the plurality of distribution servers being overloaded. In this case, a large amount of divided data is acquired from another distribution server having a relatively high effective speed.

Therefore, even if the throughput of communication with some of the distribution servers is reduced due to the overload of some of the plurality of distribution servers, the transmission speed is insufficient. There is an additional effect that the content can be acquired stably without causing it.

The present invention is a distribution system including the content acquisition apparatus, which is a content acquisition apparatus including a communication unit including a plurality of communication interfaces, one or more distribution servers, and one or more proxy servers. And at least a part of each of the distribution servers in the case where the content acquisition device communicates simultaneously with the number of distribution servers using the number of communication interfaces exceeding the number of the distribution servers with which the content acquisition device should communicate. The communication between the communication server and the distribution server is a communication via two or more communication interfaces using both a direct communication with the distribution server and an indirect communication with the distribution server via the proxy server. It can also be realized as a distribution system.

The present invention can also be realized as a playback device including each unit of the content acquisition device and a playback unit that sequentially plays back the plurality of divided data acquired by the acquisition unit in time series. .

Furthermore, a program for operating a computer as a content acquisition apparatus according to the present invention, characterized in that the computer functions as each of the above-described means, and a computer-readable program recording such a program Recording media are also included in the scope of the present invention.

The content acquisition device according to the present invention can be widely applied to playback devices and the like.

5a to

5c MPD data

100, 100A, 100B Playback device (content acquisition device)
110, 110a Communication control unit (reading means, acquisition control means, setting means)
120 playback unit 130

storage unit

140, 140a, 140b network I / F (acquisition unit, communication interface, reception interface)
150 Display unit 200 Proxy server 250-1, 250-2 Router 300, 300-1, 300-2 Distribution server 350

Distribution management server

400, 400a to 400c Network storage server (NAS)

Claims

In a content acquisition device that acquires content data from a distribution server,
Reading means for reading data amount information indicating the data amount of the content data per unit time from the metadata relating to the content data;
Setting means for setting a value of N indicating the number of logical channels used for acquiring the content data based on the data amount information;
Acquisition control means for controlling the acquisition unit so that the acquisition unit acquires each of a plurality of pieces of divided data obtained by time-dividing the content data from the distribution server,
The acquisition control means is configured to allow the acquisition unit to acquire a plurality of the divided data from the distribution server in parallel through N logical channels.
The content acquisition apparatus according to claim 1, wherein the setting means sets the value of N larger as the data amount indicated by the data amount information is larger.
The content acquisition device according to claim 1,
The acquisition unit is composed of M reception interfaces,
The acquisition control means is configured to control the M reception interfaces so that each of the M reception interfaces acquires the divided data.
The content acquisition apparatus according to claim 1, wherein the setting unit sets the N value regardless of a value of M that is the number of the reception interfaces to be controlled by the acquisition control unit.
The content acquisition device according to claim 1 or 2,
The acquisition unit is a communication unit capable of communicating with the distribution server,
The acquisition control means is configured to control the communication unit so that the communication unit acquires the divided data by IP communication using the logical channel as a route.
For each of the plurality of pieces of divided data, the acquisition control unit sets the communication destination of the IP communication to the proxy server of the content acquisition apparatus, and then sends the divided data to the communication unit via the proxy server. A content acquisition apparatus configured to be able to select whether to acquire from a distribution server or to cause the communication unit to directly acquire from the distribution server by setting the communication destination in the distribution server .
The content acquisition device according to claim 3,
The communication unit is composed of a plurality of communication interfaces,
The acquisition control unit causes the first communication interface capable of directly acquiring the divided data from the distribution server by IP communication to acquire the divided data, or receives the divided data from the distribution server by IP communication. The divided data is acquired from the distribution server via the proxy server to the second communication interface that cannot be directly acquired by the second communication interface in which the proxy server exists in the same network as the communication interface. A content acquisition apparatus characterized by being configured to be selectable.
The content acquisition device according to claim 4,
The acquisition control unit measures an effective speed of communication between the communication interface and the distribution server for each of the communication interfaces corresponding to the first communication interface or the second communication interface among the plurality of communication interfaces. Is configured to
The content acquisition apparatus, wherein the acquisition control unit is configured to cause the communication interface having a relatively large effective speed to acquire a relatively large amount of divided data.
The content acquisition device according to claim 1 or 2,
The acquisition unit is a communication unit capable of communicating with the distribution server,
A second reading means for reading distribution server specifying information for specifying a distribution server capable of distributing the content data from the metadata relating to the content data;
The acquisition control unit is configured to be able to select a distribution server that is an acquisition destination of the divided data by the communication unit when a plurality of the distribution servers are specified from the distribution server specifying information.
The acquisition control means determines, for each of the plurality of divided data, whether the divided data is acquired from the plurality of distribution servers by the communication unit based on an effective speed of communication with each distribution server. Is configured to make decisions based on
The content acquisition apparatus, wherein the acquisition control unit is configured to cause the communication unit to acquire a relatively large amount of divided data from the distribution server having a relatively large effective speed.
In a content acquisition device that acquires content data composed of N different types of components from a distribution server,
Detecting means for detecting that the number of the formats is N by referring to metadata about the content data;
Acquisition control means for controlling the acquisition unit so that the acquisition unit acquires each of the N pieces of divided data obtained by dividing the content data for each format from the distribution server,
The content acquisition apparatus, wherein the acquisition control unit is configured to allow the acquisition unit to acquire a plurality of the divided data from the distribution server in parallel through N logical channels.
The content acquisition device according to claim 4 or 5,
One or more distribution servers,
A distribution system including one or more proxy servers,
When at the same time communicating with the number of distribution servers using the number of the communication interfaces that exceeds the number of the distribution servers with which the content acquisition device should communicate, at least a part of the distribution servers The communication between the two is a communication via two or more communication interfaces using both a direct communication with the distribution server and an indirect communication with the distribution server via the proxy server. Distribution system.
Each means with which the content acquisition apparatus of any one of Claim 1 to 7 is equipped,
And a reproducing unit that sequentially reproduces the plurality of divided data acquired by the acquisition unit in time series.
In a content acquisition method for acquiring content data from a distribution server, wherein the content acquisition method includes an acquisition control unit, a reading unit, and a setting unit.
A reading step in which the reading means reads data amount information indicating a data amount of the content data per unit time from metadata regarding the content data;
A setting step in which the setting means sets the number N of logical channels used for acquiring the content data based on the data amount information read in the reading step;
The acquisition control means includes an acquisition control step of controlling the acquisition unit so that the acquisition unit acquires each of a plurality of divided data obtained by time-dividing the content data from the distribution server,
The acquisition control means is configured to allow the acquisition unit to acquire a plurality of the divided data from the distribution server in parallel through the N logical channels in the acquisition control step.
The content acquisition method, wherein the setting means sets the value of N larger as the data amount indicated by the data amount information is larger in the setting step.
A program for operating a computer as the content acquisition device according to any one of claims 1 to 7, wherein the content acquisition program causes the computer to function as each of the above means.
A computer-readable recording medium on which the content acquisition program according to claim 11 is recorded.