WO2012053047A1

WO2012053047A1 - Streaming playback device, streaming playback method, computer program and recording medium

Info

Publication number: WO2012053047A1
Application number: PCT/JP2010/068288
Authority: WO
Inventors: 秀人遠藤; 裕貴玉田; 恭一寺尾
Original assignee: パイオニア株式会社
Priority date: 2010-10-18
Filing date: 2010-10-18
Publication date: 2012-04-26

Abstract

The present invention quickly initiates the streaming playback of content. A streaming playback device (10) is provided with an identification means (100) for identifying a communication state via said network with each of a plurality of data providing nodes; a protocol generating means (100) for, on the basis of the identified communication state, generating a request protocol for requesting the transfer of a plurality of subdivision data which is prepared by subdividing playback initiation data as data required for initiating the streaming playback; a transmitting means (300) for transmitting the generated request protocol to each of the plurality of data providing nodes via said network; an acquiring means (400) for acquiring via said network, the subdivision data transferred from each of the plurality of data providing nodes in response to the transmitted request protocol; and a playback means (100) for sequentially reproducing the contents in accordance with the acquired subdivision data.

Description

Streaming playback apparatus, streaming playback method, computer program, and recording medium

The present invention relates to a technical field of a streaming playback device, a streaming playback method, a computer program, and a recording medium for performing streaming playback of various contents related to, for example, video and audio.

When downloading a single file, a method has been proposed in which a plurality of data (called “fragments” in the literature) obtained by dividing the single file are transmitted from a plurality of servers via a network. (For example, refer to Patent Document 1).

According to the method disclosed in Patent Document 1, a file transmission rate is obtained by allocating an amount of fragments according to the transmission rate to each of a plurality of servers selected in order of increasing transmission rate, and transmitting them from these servers. It is said that it is possible to improve.

According to Patent Document 1, the technical idea disclosed in Patent Document 1 is applicable not only to file download but also to streaming playback. In this case, the streaming reproduction means that the contents are sequentially reproduced based on the acquired data while acquiring data regarding various contents. In general streaming playback, acquisition of data related to content is continued at the start of playback of the content.

JP-T-2004-531824

Although the method disclosed in Patent Document 1 can reduce the time required for downloading a file compared to downloading a file from a single server, the method has been tried to be applied to streaming playback of various contents. In some cases, the following problems may arise.

In one streaming playback device, the time required to start streaming playback of content from the time when a transfer request for data necessary for streaming is issued (hereinafter referred to as “playback start time” as appropriate) Proportional to the time it takes to get the minimum data needed to start.

Here, in particular, when acquiring divided data of a single content from a plurality of nodes that can take various forms such as a server device and a personal computer, as described above, a predetermined amount is determined according to the transmission speed from the beginning of the file. When the above data is allocated as divided data, it is highly possible that the reproduction startable data is allocated to only one node. In this case, after all, the playback start time is no different from when a file is acquired from one node.

That is, in the method disclosed in Patent Document 1, there is a case where a special gain does not occur in using a plurality of nodes regarding the playback start time, and the time until the streaming playback is started is surely shortened. There is a technical problem that this is difficult.

The present invention has been made in view of the above-described problems, and provides a streaming playback apparatus and method capable of quickly starting streaming playback of content, and a computer program and a recording medium for realizing such a method. The purpose is to do.

In order to solve the above-described problem, a streaming playback device according to claim 1 is a streaming playback device capable of streaming playback of content, which is accommodated in a network together with a plurality of data providing nodes, and is connected via the network. Communication status specifying means for specifying a communication status with each of the plurality of data providing nodes, and for starting the streaming reproduction of the content data constituting the content based on the specified communication status Protocol generation means for generating a request protocol for requesting transfer of a plurality of pieces of fragmented data obtained by subdividing the reproduction start data as necessary data, and for each of the generation via the network Means for transmitting the requested request protocol, and the network An acquisition means for acquiring the fragmented data transferred from each of them according to the transmitted request protocol, and a reproduction means for sequentially reproducing the content according to the acquired fragmented data It is characterized by.

In order to solve the above-described problem, the streaming playback method according to claim 7 is a streaming playback method in a streaming playback device capable of streaming playback of content accommodated in a network together with a plurality of data providing nodes. A communication state specifying step for specifying a communication state with each of the plurality of data providing nodes via the network, and content data constituting the content based on the specified communication state A protocol generation step of generating a request protocol for requesting transfer of a plurality of segmented data obtained by segmenting the reproduction start data as data necessary for starting the streaming reproduction; The generated request protocol via the network A transmission step of transmitting, an acquisition step of acquiring the fragmented data transferred from each according to the transmitted request protocol via the network, and the contents sequentially according to the acquired fragmented data And a reproducing step for reproducing.

In order to solve the above-described problem, a computer program according to claim 8 causes a computer system to function as the streaming playback device according to any one of claims 1 to 6. Features.

In order to solve the above-described problem, a recording medium described in claim 9 records the computer program described in claim 8.
<Embodiment of Streaming Playback Device>

An embodiment of the streaming playback device according to the present invention is a streaming playback device capable of streaming playback of content accommodated in a network together with a plurality of data providing nodes, wherein the plurality of data providing nodes are connected via the network. Communication status specifying means for specifying the communication status with each other, and data necessary for starting the streaming reproduction among the content data for viewing the content based on the specified communication status Generating a request protocol for requesting transfer of a plurality of subdivided data obtained by subdividing the reproduction start data, and transmitting the generated request protocol to each of the above via the network Transmitting means for transmitting the data via the network Comprising an acquisition means for acquiring the subdivided data transferred from said each of the reproducing means for sequentially reproducing the contents according to the acquired subdivided data in response to the request protocol.

The “network” according to the embodiment is, for example, a WAN (Wide Area Network) network, a LAN (Local Area Network) network, a WAN line or a LAN network, a telephone line, an ADSL (Asymmetric Digital Subscriber Line), or an optical fiber. It is a concept encompassing various data communication networks such as the Internet network appropriately connected via a cable or the like.

The “data providing node” according to the embodiment means, for example, various server devices, personal computer devices, and the like. The server apparatus may be an open server apparatus that does not limit the number of connected persons, or may be a closed server apparatus that is limited in the number of connected persons. The data providing node may be a predetermined device, or may be a device that is appropriately selected or determined from appropriate candidates each time.

According to the streaming playback apparatus according to the embodiment, during the operation, the communication status with each of the plurality of data providing nodes is specified by the communication status specifying means.

Here, the “communication state” specified by the communication state specifying means means that, when requesting some data to the data providing node via the network, appropriate data transferred from the data providing node in response to the request. It means a qualitative or quantitative state that defines the amount of delay on the time axis when arriving at the streaming playback device. Therefore, a practical aspect related to the “communication state” may include a network dependent one and a data providing node dependent one, and is not uniquely limited. For example, the “communication state” may appropriately include a transmission band of the network, a data processing speed of the data providing node, a data transfer speed of the data providing node, an RTT (Round Trip Time), and the like.

Note that the specifying step related to the communication state specifying means may be executed periodically, for example, at a constant or indefinite period, or may be executed irregularly or limitedly when an appropriate condition is satisfied. There may be.

In addition, “specific” according to the embodiment means that a specific target is determined directly or indirectly as a reference value for control, and is detected, calculated, derived, estimated, identified, selected, or The practical aspects such as acquisition are not limited in any way.

On the other hand, when the communication state is specified, a request protocol is generated by the protocol generation unit, and transmitted to each of the data providing nodes via the network by the transmission unit. The transmission / reception mode of various data with the data providing node may be, for example, via an appropriate server device, or may be, for example, not via a server device such as P2P (Peer To Peer). Good.

The “request protocol” according to the embodiment is a concept that encompasses various protocols for requesting each data providing node to transfer fragmented data.

Here, “subdivision data” refers to the data size of reproduction start data (hereinafter referred to as “reproduction start data”), which is obtained by subdividing reproduction start data necessary for starting reproduction of content among content data corresponding to the entire content. This is fragment data having a data size less than the “reproduction start data amount” as appropriate.

Note that the reproduction start data is continuous data extending from the start position of the content data to an appropriate position, but the reproduction start data amount is determined based on the streaming reproduction such as the data processing speed of the streaming reproduction apparatus and the reproduction method related to the streaming reproduction. Depending on the situation on the apparatus side, it may be appropriately changed.

In the embodiment of the streaming playback apparatus, the segmented data transferred according to the request protocol is sequentially acquired by the acquisition unit from the plurality of data providing nodes via the network. As a result, when the data larger than the data size of the reproduction start data is accumulated, streaming reproduction of the content is started by the reproduction means. For example, the segmented data may be temporarily buffered in a volatile storage area, or may be permanently stored in a nonvolatile storage area.

As described above, in the embodiment of the streaming playback device of the present invention, even when data is transferred from a plurality of data providing nodes, the playback start data is transferred from one data providing node without being subdivided. For example, it has been found as a technical problem that the time until the start of streaming reproduction cannot be shortened. In response to such technical problems, at least the playback start data is subdivided, and the technical idea of collecting the subdivision data as fragments of the playback start data from a plurality of data providing nodes reduces the time required to acquire the playback start data. Thus, streaming playback can be started quickly.

By the way, in data transmission via a network, such fragmentation of reproduction start data does not necessarily lead to a reduction in the time required to acquire the reproduction start data. That is, the communication state described above greatly affects the transmission of various data between the streaming playback device and each of the plurality of data providing nodes. In particular, data having a relatively small size such as fragmented data has a relatively large influence from the communication state.

More specifically, even when the request protocols generated by the protocol generation means are transmitted to a plurality of data providing nodes all at once, the times when the request protocols arrive at each data providing node do not necessarily match each other. Similarly, the time required for analyzing the request protocol and preparing the appropriate data transfer in each data providing node is not uniform. Further, assuming that data transfer is started in each data providing node, the time until each packet (that is, transfer unit) constituting the requested fragmented data arrives at the streaming playback device is also determined by each node. Is not uniform.

For this reason, simply subdividing the reproduction start data may cause a situation such as the transfer of some of the subdivided data being greatly delayed. In some cases, the time required to acquire the reproduction start data may be shorter if the reproduction start data is not subdivided.

Therefore, the streaming playback device according to the embodiment is configured such that the protocol generation unit generates the request protocol based on the communication state specified by the communication state specifying unit. Such a practical aspect of the request protocol generated based on the communication state can be defined in any way. For example, the request protocol is determined by the data size of the fragmented data in the content data for each data providing node. May be a protocol that prescribes information related to information, information related to the transfer start position of segmented data, and the like.

Here, in particular, “based on the communication state” can be interpreted as a conceptual expression, but in view of the fact that such a technical idea does not exist in the past, its effect is denied due to unclearness. not. As described above, the “communication state” according to the embodiment is a qualitative or quantitative state that defines the amount of delay on the time axis when the segmented data arrives at the streaming playback device. The mere size of the transmission band of the network as seen in the technology is a state defined by a more practical operational aspect in which the tendency does not necessarily coincide. In other words, unless the communication state of this kind is taken into consideration, the position on the time axis where the transferred fragmented data actually arrives at the streaming playback device loses its controllability. Whether or not the time required for acquisition can be shortened can be left to the end.

In view of the point that the streaming reproduction waits until the completion of the acquisition of the reproduction start data, at least the segmented data related to the reproduction start data does not necessarily need to be acquired in the data reproduction order.

Note that the communication state specifying unit, the protocol generation unit, and the playback unit according to the embodiment of the streaming playback device are each or as a whole, for example, various arithmetic processing devices such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), It may be configured as various processors, controllers or various functional modules.

In one aspect of the embodiment of the streaming playback device of the present invention, the communication state specifying unit specifies at least a communication speed and a response delay amount as the communication state.

The communication speed via the network means a transmission bandwidth (usable bandwidth) of the network, a data transfer speed depending on the specifications or performance of the streaming playback device or the data providing node, etc. Changes for each data providing node. In addition, it is not uncommon for the transmission band of a network to irregularly decrease from the maximum value in specifications or standards. Therefore, it is appropriate as a practical aspect that the “communication state” according to the present invention can take.

The response delay amount is a time delay amount (for example, RTT) when exchanging a request or a command between the streaming playback device and the data providing node, or a processing delay amount (hardware-like) in the data providing node. It is influenced by the processing speed, the load state, etc.), and can be appropriately changed according to the network environment, the performance of the data providing node, and the like. Therefore, it is appropriate as a practical aspect that the “communication state” according to the present invention can take.

In another aspect of the embodiment of the streaming playback apparatus of the present invention, the apparatus further comprises storage means for storing the specified communication state.

According to this aspect, since the specified communication state is stored in the appropriate storage means in the form of the appropriate data, once the process related to specifying the communication state is performed, the process after the next time is simplified. Is possible. At this time, the specifying unit may newly execute a process related to specifying the communication state only when it can be determined that the communication state is clearly different or different from the previous time. Alternatively, as a simpler example, this type of specifying process may be performed when a designated time has elapsed.

In another aspect of the embodiment of the streaming playback apparatus of the present invention, the protocol generation means is configured to equalize the transfer time from the transmission time of the request protocol to the time when the transfer of the fragmented data ends in each of the above. The request protocol is generated as follows.

According to this aspect, the request protocol is generated so that the transfer time, which means the length of the data transfer period from the request protocol transmission time to the time when the fragmented data transfer is completed, is equal among the data providing nodes. The For this reason, the time required to acquire the reproduction start data can be ideally shortened most.

Note that “so as to be equal” means the control target as described above, and the actual data transfer end time does not necessarily have to be exactly the same in each data providing node. Furthermore, in this aspect, if the communication state specified with various aspects and the reproduction start data amount are known, the data amount or allocation amount of the subdivided data that can equalize the transfer period is mathematically determined. It means that it can lead to.

In another aspect of the embodiment of the streaming playback apparatus of the present invention, the protocol generation means generates fragmentation in the process in which the fragmented data is transferred from each of them via the network when generating the request protocol. The data size of the subdivided data is set so as not to occur.

According to this aspect, in the request protocol, the data size of the fragmented data is set so that fragmentation (that is, division) of the fragmented data in the process of transferring the fragmented data is avoided. Therefore, efficient data transfer is realized while ensuring controllability, and the time required to acquire the reproduction start data can be suitably shortened.

If the data size of the fragmented data is too small, the processing load in the data transfer process increases unnecessarily, and the data transmission efficiency in the network decreases. Therefore, it is desirable that the data size of the fragmented data is set within a range that does not cause a significant decrease in transmission efficiency while avoiding fragmentation.

For example, such a data size may be the smallest MTU among the MTU (Maximum Transfer Unit) of each data providing node. In addition, for example, the data size may be different for each node as the MTU for each node without intentionally making such a common.

In another aspect of the embodiment of the streaming playback apparatus according to the present invention, the protocol generation unit subdivides the continuation data necessary for continuing the streaming playback after obtaining the playback start data of the content data. And generating a request protocol for requesting transfer in accordance with the reproduction order of the continuation data that has been segmented and subdivided, and the transmission means, for each of the above, generates the generated protocol via the network The request data related to the continuation data is transmitted, and the acquisition unit transfers the fragmented continuation data transferred from the respective according to the request protocol related to the transmitted continuation data via the network. And the reproduction means obtains the content according to the obtained fragmented continuation data. In order to play.

According to this aspect, the continuation data necessary for continuing the streaming playback of the content after the completion of the acquisition of the playback start data by the request protocol generation means (that is, the data after the playback start data in the content data). ) Is further generated for requesting its subdivision and transfer.

The request protocol related to the continuation data is transmitted to each node in the same manner as the request protocol related to the reproduction start data by the transmission unit, and each node transfers according to the request protocol related to the continuation data concerned. The data is acquired by the acquisition unit in the same manner as the segmented data regarding the reproduction start data.

Note that the continuation data may be subdivided similarly to the subdivision data related to the reproduction start data, or may be subdivided differently. In any case, by acquiring fragment data of continuation data from a plurality of data providing nodes, the acquisition time of the entire content data can be shortened.

Here, according to this aspect, the request protocol for the continuation data is generated as a request for subdivision of the continuation data and a transfer in accordance with the reproduction order. That is, the segmented data for continuation is sequentially acquired along the reproduction order.

* Acquisition of data according to the playback order directly leads to stability or reliability of streaming playback. That is, according to this aspect, it is extremely useful in practice in that it is possible to realize uninterrupted streaming.

In addition, when data transfer is performed in accordance with the reproduction order in this way, content data fragments for streaming reproduction (that is, fragmented continuation data) are accumulated extremely efficiently. On the side, there is a margin in the amount of fragment data that can be stored, and it is possible to perform other processes using time delay. For example, in this case, it is possible to take measures such as requesting the transfer again in response to various unexpected situations such as a transfer error or fragment data loss. Therefore, it is possible to ensure the reliability of streaming playback as a whole.

An embodiment according to the streaming playback method of the present invention is a streaming playback method in a streaming playback device capable of streaming playback of content accommodated in a network together with a plurality of data providing nodes, wherein A communication state specifying step of specifying a communication state with each of the data providing nodes, and starting streaming playback of content data for viewing the content based on the specified communication state A protocol generation step for generating a request protocol for requesting transfer of a plurality of fragmented data obtained by subdividing the reproduction start data as necessary data; and Sending process to send the request protocol An acquisition step of acquiring the fragmented data transferred from each of them according to the transmitted request protocol via a network; and a reproduction step of sequentially reproducing the content according to the acquired fragmented data To do.

The embodiment according to the streaming playback method of the present invention achieves the same effect as the embodiment of the streaming playback device according to the present invention by each step corresponding to the operation of each means in the embodiment according to the streaming playback device of the present invention. obtain.

The embodiment according to the computer program of the present invention causes a computer system to function as the embodiment according to the streaming playback device of the present invention.

The computer program is read into the computer system from a solid-state storage device such as a ROM, CD-ROM, DVD-ROM, hard disk or other storage medium storing the computer program, or a USB (Universal Serial Bus) memory. If the computer program is executed, or if the computer program is executed after being downloaded to a computer system via, for example, communication means, the embodiment of the above-described streaming playback device of the present invention can be relatively easily performed. realizable.

Incidentally, in response to the various aspects in the embodiments of the streaming playback apparatus of the present invention described above, the embodiments of the computer program of the present invention can also adopt various aspects.

The embodiment according to the recording medium of the present invention records the embodiment according to the computer program of the present invention.

According to the embodiment of the recording medium of the present invention, the computer program of the present invention recorded by being attached to or connected to a computer system, or by being inserted into an appropriate reader provided in or connected to the computer system. The embodiment according to the present invention can be read and executed by a computer system, and the embodiment according to the streaming playback apparatus of the present invention described above can be realized relatively easily.

As described above, according to the embodiment of the streaming playback apparatus of the present invention, since the communication state specifying unit, the protocol generation unit, the transmission unit, the acquisition unit, and the playback unit are provided, the content streaming playback is started quickly. be able to.

As described above, according to the embodiment of the streaming playback method of the present invention, the communication state specifying step, the protocol generation step, the transmission step, the acquisition step, and the playback step are provided, so that the content streaming playback is started quickly. be able to.

As described above, according to the embodiment of the computer program of the present invention, the computer system can function as the embodiment of the streaming playback device of the present invention, so that the content streaming playback can be started quickly. Can do.

As described above, according to the embodiment of the recording medium of the present invention, the embodiment of the computer program of the present invention is recorded, so that streaming playback of content can be started quickly.

These effects and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic configuration diagram conceptually showing a configuration of a streaming system according to a first example of the present invention. FIG. 2 is a block diagram conceptually showing the structure of a playback device in the streaming system of FIG. 1. 3 is a flowchart of streaming playback control executed in the playback device of FIG. 2. FIG. 3 is a conceptual diagram of response delay and transmission speed referred to in the streaming playback control of FIG. 2. 3 is a timing chart conceptually illustrating a fastest transfer pattern in the execution process of the streaming reproduction control of FIG. It is a conceptual diagram of the data request protocol produced | generated in the streaming reproduction | regeneration control of FIG. It is a conceptual diagram of an IP packet when TCP is adopted as a transmission protocol. It is a conceptual diagram of an IP packet when UDP is adopted as a transmission protocol. It is a timing chart of the data transfer in the comparative example which concerns on the effect of an Example and does not consider response delay. It is a table | surface of the difference of the reproduction start time of an Example and a comparative example regarding the effect of an Example. It is a conceptual diagram of the bitmap which concerns on 2nd Example. It is a conceptual diagram of the encoded bitmap pattern according to the second embodiment.

Hereinafter, various preferred embodiments of the present invention will be described with reference to the drawings as appropriate.
<First embodiment>
<Configuration of Example>
First, the configuration of the streaming system 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the streaming system 1.

In FIG. 1, the streaming system 1 includes a playback device 10 and

data providing nodes

30A, 30B, 30C, and 30D (each of which is accommodated in a wide area network 20 (in this embodiment, an IP (Internet Protocol) network)). This is a system for realizing streaming playback of various contents related to video or audio on the playback device 10. More specifically, the playback device 10 distributes and requests content data to each data providing node, and performs streaming playback based on fragmented data of the content data appropriately transferred from each data providing node. It has a configuration.

Note that the configuration of the streaming system 1 illustrated in FIG. 1 is merely an example for performing streaming playback on the playback device 10. For example, in the streaming system 1, the playback device 10 and each data providing node are configured to perform P2P communication individually without going through a specific server device, but the playback device 10 and each data providing node are Communication may be performed via an appropriate server device accommodated in the network 20. In FIG. 1, four data providing nodes are shown, but there is basically no limit on the number of data providing nodes except for a practical limitation. When a streaming system is constructed by P2P communication, an unspecified number of nodes (for example, personal computers owned by individuals) accommodated in the network 20 can appropriately be data providing nodes. Can be one of the data providing nodes.

Next, the configuration of the playback device 10 will be described with reference to FIG. FIG. 2 is a block diagram conceptually showing the configuration of the playback apparatus 10. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

2, the playback device 10 is an example of a “streaming playback device” according to the present invention, which includes a control unit 100, a storage device 200, a transmission unit 300, a reception unit 400, and a buffer 500.

The control unit 100 is an electronic control device that includes an arithmetic processing device such as a CPU or MPU, and a storage device such as a ROM (Read Only Memory) and a RAM (Random Access Memory), according to a computer program stored in the ROM. It is configured to be able to execute streaming playback control described later. The computer program is an example of the “computer program” according to the present invention for realizing the “streaming reproduction method” according to the present invention.

This computer program can be recorded on various recording media such as HD, CD-ROM, and DVD-ROM (an example of the “recording medium” according to the present invention). It is also possible to cause the computer system to function as an example of the “streaming playback device” according to the present invention in a state of being installed, stored, or inserted in an appropriate recording / playback device built in or attached to various computer systems. .

The control unit 100 is configured to function as an example of each of the “communication state specifying unit”, the “protocol generating unit”, and the “reproducing unit” according to the present invention in the execution process of the streaming reproduction control.

The storage device 200 is a nonvolatile storage device such as an HDD or a flash memory, and is an example of the “storage means” according to the present invention. Delay data DLY is stored in the storage area of the storage device 200. The delay data DLY is control data describing a response delay td and a transmission speed x (that is, an example of a “communication state” according to the present invention) described later for each data providing node.

The transmission unit 300 is a transmission interface that is an example of a “transmission unit” according to the present invention, in which an output terminal (symbol omitted) is connected to the network 20, and various data specified by the control unit 100 via the network 20. Can be transmitted to each data providing node. Note that a data request protocol, which will be described later, generated in the process in which the control unit 100 executes the streaming playback control, is also transmitted from the transmission unit 300 as one of the data.

The receiving unit 400 is a receiving interface as an example of the “acquisition means” according to the present invention, in which an output terminal (not shown) is connected to the network 20. Various receiving units 400 are transferred from the data providing nodes via the network 20. It is configured to receive data. Note that a data fragment (that is, an example of “subdivided data” according to the present invention), which will be described later, transferred from each data providing node via the network 20 is also received by the receiving unit 400 as one of the data. It has become.

The buffer 500 is a volatile storage device that temporarily accumulates data fragments transferred from each data providing node by a data amount corresponding to a predetermined buffer capacity.
<Operation of Example>
Hereinafter, streaming playback control will be described as the operation of this embodiment.

<Overview of streaming playback control>
First, an overview of streaming playback control will be described.

Streaming playback control is control for realizing streaming playback of content in the playback device 10. Content data necessary for content reproduction is not stored in the reproduction apparatus 10 and is acquired from each data providing node via the network 20. At this time, the data acquired from each data providing node is acquired with a data fragment as an example of “subdivided data” according to the present invention, which is obtained by subdividing the content data according to a predetermined standard. In addition, selection of a data providing node that requests a data fragment and allocation of data fragments (data amount and fragment position) in each selected data providing node are defined by a data request protocol generated in the playback device 10.

Here, the playback device 10 can start streaming playback when playback start data, which is data corresponding to N (bit), is acquired from the top data of the content data. The streaming reproduction control is a control aimed at shortening the reproduction start time Tply as the length of the period from the transmission point of the data request protocol to the start point of streaming reproduction. Note that “shortening” is, of course, a concept that can be defined only when a comparison target exists. However, the shortening standard according to this embodiment is based on a comparative example described later that belongs to the category of the conventional technical idea. It is assumed that this is the playback start time.

<Details of streaming playback control>
Next, details of the streaming playback control will be described with reference to FIG. FIG. 3 is a flowchart of the streaming playback control.

In FIG. 3, the control unit 100 refers to the delay data DLY stored in the storage device 200, and the response delay td and the transmission rate x in the data transmission path established via the network 20 with each data providing node. Are acquired (step S101). The response delay td and the transmission rate x are examples of the “communication state” according to the present invention, and are measured by the control unit 100 prior to or in synchronization with the execution of step S101. The delay data DLY is data generated based on the measured response delay td and transmission rate x and stored in the storage device 200. The operation according to step S101 and the response delay td and transmission rate x measurement process preceding or synchronized with it are examples of the operation of the “communication state specifying means” according to the present invention. Here, referring to FIG. The delay td and transmission rate x will be described. FIG. 4 is a conceptual diagram of the response delay td and the transmission rate x.

In FIG. 4, the vertical axis is the time axis, and along the time axis, the playback device 10 and the data providing node as the operation subject are represented.

Suppose that the data request protocol is transmitted from the playback device 10 side at the illustrated operation point P1 (which corresponds to the time one-on-one) (see arrow S1). When the data request protocol arrives at the data providing node, appropriate internal processing is started at each data providing node from the illustrated operation point P2 corresponding to the arrival time (see arrow S2).

Internal processing includes analysis of received data request protocol, retrieval of data fragment specified by data request protocol and preparation for transfer thereof (for example, read processing in HDD, various optical disk devices, etc.), creation of response message, etc. Refers to various processes related to When the internal processing is completed, the data providing node sequentially transmits a plurality of data fragments ready for transfer to the playback device 10 via the network 20 (see the broken line frame S3 in the drawing).

Here, the time at which the data request protocol is transmitted from the playback device 10 (time corresponding to the operating point P1) and the time at which the data request protocol is received at the data providing node (time corresponding to the operating point P2) There is a shift on the time axis due to the transmission delay of the network 20. A delay time corresponding to the deviation on the time axis is set as a required time td1.

Also, it takes time to execute the internal processing in each data providing node. This time is set as a processing time td2.

Further, when the data fragment is transferred after the internal processing is completed, the time between the start of transmission of the first data fragment and the acquisition time of the data on the playback device 10 side is also the same as the previous request time td1. There is a shift on the time axis due to the transmission delay of the network 20. A delay time corresponding to the deviation on the time axis is defined as a response time td3. The response delay td is the sum of these request time td1, processing time td2, and response time td3 (ie, td = td1 + td2 + td3). The sum of the request time td1 and the response time td3 corresponds to the RTT of the network 20.

On the other hand, the processing time td2 is significantly affected by the hardware performance and load state on the data providing node side. Therefore, the control unit 100 separately measures the processing time td2 of each data providing node in synchronization with the measurement of the RTT. A specific method for measuring the processing time td2 is not particularly limited. For example, a request is made for data set in advance for measuring the processing time, and the time until the data is transferred in response to the request. The processing time td2 may be estimated based on the difference from the RTT. Alternatively, it is possible to request each data providing node for information regarding the processing speed and hardware configuration of each data providing node, and to estimate the processing time td2 based on the obtained information. Good.

In measuring (or estimating) the processing time td2, it is desirable to adopt the same measurement method for all the data providing nodes to be processed. As long as the same measurement method is used, even if the actual processing time differs from the measured or estimated processing time, the difference is uniformly canceled, and there is no practical impact on the progress and effect of streaming playback control. Does not occur.

By the way, when actually acquiring data fragments from the data providing node, the number of data fragments corresponding to the amount of data allocated to the data providing node is continuously acquired on the time axis after the completion of the acquisition of the first data fragment. Will be acquired. In FIG. 4, this state is shown in the time passage from the illustrated operating point P4 to the operating point P5 (see the illustrated arrow line S4). The time required to acquire data corresponding to the data amount allocated to the data providing node is the illustrated transmission time tx. The transmission time tx is uniquely defined if the transmission rate x defined for each data providing node and the amount of data allocated to the data providing node are determined. If the amount of data is Nf, tx = Nf / x. is there. The time value obtained by adding the transmission time tx and the response delay td is from the time when the data request protocol is transmitted to one data providing node until the time when acquisition of the data fragment corresponding to the requested data amount is completed. And is an example of the “transfer time” according to the present invention.

The transmission rate x is between the data providing node uniquely defined by the transmission bandwidth of the network 20 allowed between the playback apparatus 10 and each data providing node, the hardware configuration of the data providing node, and the like. This value is unique to the transmission path. Therefore, when the control unit 100 manages the state of the network 20, it can be determined for each data providing node.

The control unit 100 repeatedly measures the response delay td and the transmission rate tx at a constant or indefinite period during the streaming playback control execution period, and updates the delay data DLY as appropriate. Therefore, even if the delay data DLY is referred to or the response delay td and the transmission rate tx are measured in real time in step S101, highly accurate values can be referred to.

3, the control unit 100 acquires the reproduction start data amount N (bit), which is the data amount of the reproduction start data described above (step S102). The reproduction start data amount N is a value determined by the processing capability on the hardware of the reproduction apparatus 10, and is a value held by the control unit 100 as its own control data.

When the reproduction start data amount N is acquired, the control unit 100 calculates the above-described reproduction start time Tply based on the response delay td and transmission rate x for each data providing node and the acquired reproduction start data amount N (step S1). S103). Here, the reproduction start time Tply varies depending on a data providing node that is a data fragment request destination, a data allocation amount for each data providing node, a data size of the data fragment, and the like. Therefore, the control unit 100 assumes a plurality of patterns for the data providing node as an option, calculates and compares the reproduction start time Tply for the plurality of assumed patterns, and based on the comparison result, A pattern is determined (step S104).

In practice, such a calculation for all of an unspecified number of nodes that can be data providing nodes accommodated in the network 20 causes a time delay in itself, and quick start of streaming playback Disturb. Therefore, step S103 and step S104 may not always be executed. In the present embodiment, the description will be continued on the assumption that one pattern (hereinafter, referred to as “the fastest transfer pattern” as appropriate) in which the reproduction start time Tply can be the shortest in theory is selected.

In describing streaming playback according to the fastest transfer pattern, the fastest transfer pattern will be described first with reference to FIG. FIG. 5 is a timing chart conceptually illustrating the fastest transfer pattern. In the figure, parts that are the same as those in FIG.

In FIG. 5, in the vertical axis direction,

data providing nodes

30D, 30C, 30B and 30A are represented in order from the top, the vertical axis represents the transmission rate x described above, and the horizontal axis represents time in common. ing.

Further, in FIG. 5, when the transmission time of the data request protocol is used as the origin, the response delays td_d, td_c, td_b, and td_a corresponding to the

data providing nodes

30D, 30C, 30B, and 30A, respectively, The relationship td_b <td_d <td_a <td_c is established. Furthermore, the relationship x_a> x_c> x_b> x_d is established between the transmission rates x_d, x_c, x_b, and x_a corresponding to the

data providing nodes

30D, 30C, 30B, and 30A, respectively.

Here, when these are analyzed mathematically, it is possible to derive an allocation amount of data fragments that can equalize the transfer time in each data providing node except in special cases. FIG. 5 shows a state in which transfer of data fragments is completed at time T5 in all data providing nodes as a result of adopting such an allocation amount.

Note that “A”, “B”, “C”, and “D” shown in the figure represent the data allocation amount in each data providing node, respectively, and the sum (ie, A + B + C + D) is the reproduction start data amount N. . When such an allocation amount is employed, the reproduction start time Tply becomes equal to each transfer time and is minimized. That is, it becomes possible to start streaming playback of content at the fastest speed.

Hereinafter, such mathematical analysis will be described in the case where there are three data providing nodes, that is, node A, node B, and node C. As initial conditions, the playback start data amount is N (bits), the data fragment size is less than N, and the transmission rates and response delays for nodes A, B, and C are a and ta, b and tb, and c and tc, respectively. And Further, it is assumed that the data allocation amounts for the nodes A, B, and C are Na, Nb, and Nc, respectively.

First, the following equation (1) is established.

Further, the following equation (2) is established for the transfer time Ttf_a in the node A.

Similarly, the following equations (3) and (4) are established for the transfer time Ttf_b at the node B and the transfer time Ttf_c at the node C.

Here, Na, Nb, and Nc are respectively expressed by simultaneous equations consisting of a relational expression (1), a relational expression (2) = (3), and a relational expression (2) = (4). It is calculated | required like the following (5) Formula, (6) Formula, and (7) Formula.

Note that the above relational expressions may not hold. For example, when only the response delay exceeds the transfer time in another node, the data allocation amount of that node is set to zero. That is, such a node is excluded from the requested nodes.

Further, considering the nodes A, B,..., X in a more generalized manner, the transmission rates and response delays corresponding to the nodes A, B,..., X, respectively, Sa, Sb,. Then, the data amounts Na, Nb,..., Nx allocated to each can be expressed as the following equation (8). In the equation (8), z is an identifier, and z = a, b,.

3, the control unit 100 generates a data request protocol based on the determined pattern (step S104), and transmits the data request protocol to each data providing node via the transmission unit 300 (step S106). The operation according to step S104 is an example of the operation of the “protocol generation unit” according to the present invention, and the transmission operation of the transmission unit 300 under the control of the control unit 100 is performed by the “transmission unit” according to the present invention. It is an example of operation | movement.

The data request protocol is a protocol for requesting a data fragment to each data providing node, and its configuration is various, but in this embodiment, it is described with at least the following three elements. That is, the three elements are (a) transfer start position (data fragment position or byte position), (b) bitmap size, and (c) bitmap.

Here, the data request protocol will be described with reference to FIG. FIG. 6 is a conceptual diagram of the data request protocol. In the figure, the same reference numerals are assigned to the same parts as those in FIG. 5, and the description thereof is omitted as appropriate.

6, FIG. 6 (a) is a diagram showing a timing chart when a data fragment is transferred from each data providing node according to the data request protocol. FIG. 6B shows the reproduction start data represented by data fragments. FIG. 6C is a schematic diagram of a bitmap.

In FIG. 6A, the data size of the data fragment is common to all nodes. The size of the data fragment is smaller than the reproduction start data amount N as described above. In particular, in this embodiment, the size of the data fragment does not cause fragmentation of the data fragment (division processing due to excessive size). In addition, the MTU is set as a reference.

Here, the configuration of an IP packet corresponding to one data fragment will be described with reference to FIG. 7 and FIG. FIG. 7 is a conceptual diagram of an IP packet when TCP is used as a transmission protocol. FIG. 8 is a conceptual diagram of an IP packet when UDP is used as a transmission protocol. In these drawings, the same reference numerals are given to the overlapping portions, and the description thereof will be omitted as appropriate.

In FIG. 7, the data size of the entire IP packet is an MTU defined for each data providing node. Part of the IP packet is used to describe the fragment location of the IP header, TCP header and data fragment. The remaining data area is a data fragment area. Therefore, from the viewpoint of preventing data fragmentation, at least the data size of the data fragment is less than the MTU. In practical operation, when the data size of the data fragment transferred from each data providing node is equalized, since the MTU size does not always match between the nodes, the data size conforms to the minimum MTU. It is desirable to do.

In FIG. 8, as in FIG. 7, the entire data size of the IP packet is MTU, and the data fragment is stored in the remaining data area after the fragment position of the IP header, UDP header, and data fragment is described.

Returning to FIG. 6, as shown in FIG. 6A, the data providing node 30 </ b> A receives a total of seven data fragments A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A _7. Data fragments are transferred at a transfer interval defined by the transmission rate x_a. Actually, after the transfer of one data fragment is completed, the transfer of the next data fragment is started without any interval. Further, the sum of the data amounts of the data fragments A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ and A ₇ is the data allocation amount Na to the data providing node 30A.

Similarly, a total of five data fragments of data fragments B ₁ , B ₂ , B ₃ , B ₄ and B ₅ are transferred from the data providing node 30B at a transfer interval defined by the transmission rate x_b. Actually, after the transfer of one data fragment is completed, the transfer of the next data fragment is started without any interval. Further, the sum of the data amounts of the data fragments B ₁ , B ₂ , B ₃ , B ₄ and B ₅ is the data allocation amount Nb to the data providing node 30B.

Similarly, a total of four data fragments of data fragments C ₁ , C ₂ , C ₃ and C ₄ are transferred from the data providing node 30C at a transfer interval defined by the transmission rate x_c. Actually, after the transfer of one data fragment is completed, the transfer of the next data fragment is started without any interval. Further, the sum of the data amounts of the data fragments C ₁ , C ₂ , C ₃ and C ₄ is the data allocation amount Nc to the data providing node 30C.

Similarly, a total of three data fragments, data fragments D ₁ , D ₂ and D ₃ , are transferred from the data providing node 30D at a transfer interval defined by the transmission rate x_d. Actually, after the transfer of one data fragment is completed, the transfer of the next data fragment is started without any interval. Further, the sum of the data amounts of the data fragments D ₁ , D ₂ and D ₃ is the data allocation amount Nd to the data providing node 30D.

When the data fragments transferred at the timing shown in FIG. 6A are accumulated in the order of acquisition via the receiver 400, the data fragments transferred from each node are randomly arranged as shown in FIG. 6B. It becomes composition. Here, the data request protocol is generated so that the data illustrated in FIG. 6B becomes the reproduction start data as it is. That is, when the acquisition of the reproduction start data is completed, streaming reproduction is realized by reproducing the data fragments in the order of acquisition.

The designation of the fragment position of such a data fragment is defined by a bitmap as illustrated in FIG. In FIG. 6 (c), A to D mean each data providing node, and the reproduction start data is defined for each data fragment divided from left to right. That is, the data fragment adjacent to the right of the symbols A to D is the top data of the reproduction start data, and the rightmost data fragment means the last data of the reproduction start data. In addition, “1” hatched in the bitmap means that the corresponding node is in charge of transferring the data fragment, and “0” means that the data fragment is not transferred.

Here, when it is predicted that the data fragment is transferred at the timing shown in FIGS. 6A and 6B, the control unit 100 displays the bitmap as shown in FIG. Create and send to each node as data request protocol. Each node refers to the bitmap, selects continuous or discontinuous data fragments to be transferred from the content data based on the fragment positions, and sequentially transfers them as the IP packets described above. is there.

In each data providing node, the order of the data fragments acquired by the playback device 10 is not considered at all, and the data fragments specified by the protocol are sequentially transmitted at the timing specified by the response delay td and the transmission speed x. Will be transferred. Therefore, the control unit 100 calculates the arrival order of the data fragments based on the data allocation amount, the response delay td, and the transmission rate x, so that the reproduction start data is sequentially acquired from the head side. A request protocol is generated.

Returning to FIG. 3, when the data request protocol is transmitted, the control unit 100 sequentially acquires the data fragments transferred from each data providing node (step S107), and in the process of sequentially acquiring the data fragments, the reproduction start data It is determined whether or not the acquisition has been completed (step S108). If acquisition of the reproduction start data has not been completed (step S108: NO), the process returns to step S107, and acquisition of the data fragment is continued.

On the other hand, when the acquisition of the data fragment is completed (step S108: YES), the control unit 100 starts streaming playback (step S109). Step S109 is an example of the operation of the “reproducing means” according to the present invention. When streaming playback is started, an elapsed time from the start of playback is referred to, and it is determined whether or not a certain time has passed (step S110). If the predetermined time has not elapsed (step S110: NO), step S110 is repeated and the process is temporarily put into a standby state.

When the predetermined time has elapsed (step S110: YES), the control unit 100 determines whether or not the acquisition of content data has been completed (step S111), and if it has been completed (step S111: YES), streaming playback is performed. End control. However, the reproduction process related to the acquired content data is continued until the reproduction ends.

Here, when the acquisition of the reproduction start data has been completed but the acquisition of the content data has not yet been completed (step S111: NO), the control unit 100 executes a streaming continuation process (step S112).

The streaming continuation process proceeds basically in the same manner as the processes after step S101. That is, the control unit 100 sets the reproduction start data amount N to an appropriate data size (for example, the data size of the remaining content data excluding the reproduction start data (that is, an example of “continuation data” according to the present invention)). When set, the data request protocol is generated and transmitted so that the data fragment is transferred to the playback apparatus 10 at the fastest speed in the playback order.

Here, in particular, when collecting the reproduction start data, streaming reproduction is not started unless the reproduction start data is acquired. Therefore, the data fragment does not necessarily have to arrive at the reproduction apparatus 10 in the reproduction order. On the other hand, after the completion of the acquisition of the reproduction start data, it is desirable that acquisition of data fragments in accordance with the reproduction order is requested in order to prevent a reproduction error. That is, the generation of the data request protocol according to the present embodiment is also effective in the streaming continuation process.

In view of the fact that the data fragments are acquired in the reproduction order in this way, for example, when the transfer of the data fragments does not proceed as scheduled due to a change in the state of the network 20, the data fragment is caused by a packet error or the like. Even in the case of disappearance, etc., it is possible to acquire a grace period enough to deal with it. That is, the streaming continuation process is also effective from the viewpoint of stably operating streaming playback of content.
<Effect of Example>
Here, in order to explain the effect of the present embodiment, the above-described comparative example will be described. First, the concept of data transfer according to the comparative example will be described with reference to FIG. FIG. 9 is a timing chart when data transfer is performed without taking the response delay td into consideration. In the figure, the same reference numerals are assigned to the same parts as those in FIG. 5, and the description thereof is omitted as appropriate.

9, in the data fragment transmission mode according to the comparative example, the amount of data allocated to each node is determined so that the data transfer end times are equal without considering the response delay td. That is, the length of the allocated data in the time axis direction is the same for each node.

However, in reality, since there is a response delay td, the transfer start times at the nodes are different. Therefore, especially in the data providing node 30C having a large response delay td, the data transfer does not end even at time T5, and the reproduction start time Tply becomes longer than that in the above embodiment. That is, in the comparative example, the transfer time, which is the sum of the response delay td and the transmission time tx, varies between nodes, and the maximum value among them is the reproduction start time. Therefore, it is difficult to start content streaming playback quickly.

Next, in order to clarify the effect according to the above-described embodiment, a comparison using actual numerical values is performed with reference to FIG. FIG. 10 is a table showing the difference in the reproduction start time Tply between the example and the comparative example.

FIG. 10 shows FIG. 10 (a), FIG. 10 (b), and FIG. 10 (c) with different conditions. However, the transmission rate x is common.

Here, for the purpose of preventing the explanation from becoming complicated, the conditions are not explained one by one. However, the reproduction start time Tply is 32 ms under the condition of FIG. 10A, 28 ms under the condition of FIG. 10B, and FIG. Under the condition of c), 277 ms, each of the examples is shorter. This is an effect of calculating the data allocation amount in consideration of the response delay td. That is, in the embodiment, since the transfer times are the same for all nodes, transfer time = reproduction start time Tply. On the other hand, in the comparative example, since the response delay td is not taken into consideration, the transmission time tx defined by the allocated amount and the transmission rate becomes equal, and the transfer time obtained by adding the response delay td to each node varies. End up. As a result, the reproduction start time Tply is limited to these maximum values.

As described above, according to the present embodiment, the selection of the data providing node and the data allocation amount in consideration of the response delay td defined by the request time td1, the processing time td2, the response time td3, and the like, and the transmission rate x. By considering the above, it is possible to suitably shorten the reproduction start time Tply as the time from the transmission time point of the data request protocol to the time point when the reproduction start data acquisition is completed. Accordingly, it is possible to quickly start streaming playback of content.
<Second embodiment>
The configuration example of the bitmap defined in the data request protocol is not limited to that of the first embodiment. Here, a second embodiment based on such a purpose will be described with reference to FIG. FIG. 11 is a conceptual diagram of a bitmap according to the second embodiment. In the figure, the same reference numerals are given to the same parts as those in FIG. 6, and the description thereof will be omitted as appropriate.

In FIG. 11, as is apparent from the hatched display in the figure, the bitmap according to the second embodiment has regularity as represented as the illustrated unit UT. When the bit map has regularity in this way, the number of times of issuing the data request protocol can be reduced, and the transfer time can be shortened by reducing the response delay td. At this time, the least common multiple of the transmission rate x between the nodes is calculated and the unit UT is formed, so that the data fragment acquisition end time can be made equal at each node.

Further, when such a unit UT is adopted, the data request protocol can be configured to include the following elements, for example. That is, (a) transfer start position, (b) requested data size, requested unit number or requested packet number, (c) unit size, and (d) bitmap pattern.

In such a case, the bitmap pattern can be further coded. Here, the encoded bitmap pattern will be described with reference to FIG. FIG. 12 is a conceptual diagram of a coded bitmap pattern.

When the bitmap pattern is coded as shown in FIG. 12, the code contents are as follows for each node.

Node A: 1st, 3 fragment, 1 fragment skip, 2 blocks Node B: 4th, 1 fragment, 3 fragment skip, 2 blocks Node C: 9th, 1 fragment, x fragment skip, 1 block When employing a coded bitmap pattern, the data request protocol can be configured to include, for example, the following elements: That is, (a) transfer start position, (b) requested data size, requested unit number or requested packet number, (c) unit size, and (d) bitmap pattern code.

When the bitmap pattern is encoded in this way, the data amount of the entire data request protocol is reduced, and the processing time td2 required for analyzing the data request protocol can be shortened. As a result, the transfer time can be shortened.

The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. A streaming reproduction method, a computer program, and a recording medium are also included in the technical scope of the present invention.

The present invention can be applied to an apparatus that performs streaming playback of content.

DESCRIPTION OF SYMBOLS 1 ... Streaming system, 10 ... Playback apparatus, 20 ... Network, 30A, 30B, 30C, 30D ... Data provision node, 100 ... Control part, 200 ... Playback part, 300 ... Delay measurement part, 400 ... Transmission part, 500 ... Reception Part, 600 ... buffer, 700 ... storage device.

Claims

A streaming playback device capable of streaming playback of content accommodated in a network together with a plurality of data providing nodes,
A communication state specifying means for specifying a communication state with each of the plurality of data providing nodes via the network;
Based on the specified communication state, a request is made to transfer a plurality of pieces of fragmented data obtained by subdividing the reproduction start data as data necessary for starting the streaming reproduction among the content data constituting the content Protocol generation means for generating a request protocol for
Transmitting means for transmitting the generated request protocol to the respective devices via the network;
Obtaining means for obtaining the fragmented data transferred from each of the requests according to the transmitted request protocol via the network;
A streaming playback apparatus comprising: playback means for sequentially playing back the content according to the acquired segmented data.
The streaming playback device according to claim 1, wherein the communication state specifying unit specifies at least a communication speed and a response delay amount as the communication state.
The streaming playback apparatus according to claim 1, further comprising storage means for storing the specified communication state.
The protocol generation means generates the request protocol so that transfer times from the transmission time point of the request protocol to the time point at which the transfer of the fragmented data is completed are equal in each of the protocol generation means. The streaming playback device according to any one of claims 1 to 3,
The protocol generation means sets the data size of the fragmented data so that fragmentation does not occur in the process in which the fragmented data is transferred from each of them via the network when generating the request protocol. The streaming playback device according to any one of claims 1 to 4, wherein the streaming playback device is characterized in that:
The protocol generating means subdivides the continuation data necessary for continuing the streaming reproduction after obtaining the reproduction start data of the content data and follows the reproduction order of the continuation data subjected to the subdivision. Further generate a request protocol to request
The transmission means transmits a request protocol for the generated continuation data to the respective units via the network,
The acquisition means acquires the fragmented continuation data transferred from each according to a request protocol related to the transmitted continuation data via the network,
The streaming reproduction device according to any one of claims 1 to 5, wherein the reproduction unit sequentially reproduces the content in accordance with the acquired fragmented continuation data.
A streaming playback method in a streaming playback apparatus capable of streaming playback of content accommodated in a network together with a plurality of data providing nodes,
A communication state specifying step for specifying a communication state with each of the plurality of data providing nodes via the network;
Based on the specified communication state, a request is made to transfer a plurality of pieces of fragmented data obtained by subdividing the reproduction start data as data necessary for starting the streaming reproduction among the content data constituting the content A protocol generation step for generating a request protocol for
A transmitting step of transmitting the generated request protocol to the respective devices via the network;
Obtaining the fragmented data transferred from each according to the transmitted request protocol via the network;
And a playback step of sequentially playing back the content according to the acquired segmented data.
A computer program for causing a computer system to function as the streaming playback device according to any one of claims 1 to 6.
A recording medium for recording the computer program according to claim 8.