JP2012080417A - Streaming reproduction device, streaming reproduction method, computer program and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform streaming reproduction of a content with high quality regardless of processing capacity of a reproduction device.SOLUTION: A streaming reproduction device 100 is comprised of a first storage device 170 and a second storage device 160 with lower writing speed and larger storage capacitance compared with the first storage device. The streaming reproduction device 100 includes: means for acquiring a fragment Na including reproduction start data of a content and a fragment Nb in sequence with the fragment Na, respectively; means for storing the acquired fragments Na and Nb in each of the first and the second storage devices; means for starting reproduction of the content by sequentially reading out the fragments from the fragment Na to Nb; and means for determining the fragment Na and Nb, and their transfer rates so as to finish storing the fragment Nb before or at the same time finishing reading out the fragment Na.

Description

  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.

  As a content streaming reproduction method, a method using a real-time streaming method using a method 1 for conveying a content stream at a rate larger than the reproduction rate and a method 2 for conveying the content stream at a reproduction rate has been proposed (for example, Patent Document 1). According to the content distribution system disclosed in Patent Document 1, a cache is accumulated in the buffer by selecting the method 1 at the start of reproduction, and after the cache is accumulated in the buffer, the method 2 is selected. Even when the network is interrupted, playback can be continued using the cache in the buffer.

JP 2008-244548 A

  By the way, when writing to the buffer at the content playback speed, the time required for writing is equal to the content playback time. Therefore, in this type of real-time streaming, the time required to connect to the network tends to be long as a whole. Of course, if the capacity of the buffer used for this type of real-time streaming can be made sufficiently large with respect to the data amount of the content, writing synchronized with the playback speed is not necessarily required. When considering a relatively large amount of content, the buffer capacity is generally sufficiently small with respect to the content data amount.

  On the other hand, the state of the network is often not stable over time, and it is not unlikely that some kind of failure will occur, such as unexpectedly interrupting the connection to the network. Therefore, in this type of real-time streaming in which the connection time to the network must be relatively long, the reproduction quality of the content depends on the state of the network.

  Here, in particular, according to the apparatus disclosed in Patent Document 1, even if a failure occurs in the network, the content can be continuously played back for a certain time by the cache stored in the buffer. Since the capacity is not large with respect to the data amount of the content, the effect is limited, and it must be said that it is practically insufficient for the purpose of stable reproduction of the content.

  Incidentally, apart from this type of real-time streaming method, a progressive download method is also known in which a fixed unit of content is downloaded to a large-capacity storage device such as an HDD (Hard Disk Drive) and played sequentially. With this method, it is easy to make the capacity of the HDD as a buffer larger than the content data amount, and it is possible to shorten the time for connecting to the network.

  However, in this case, it is necessary to simultaneously execute content writing to the HDD and content reading from the HDD. In order to perform reading and writing at the same time, a large amount of processing power is required on the control device side. Therefore, the benefits of the progressive download method can be enjoyed from some high-performance, high-performance processing equipment. Only a playback device (that is, expensive). In other words, in a device environment where the device performance is inevitably limited, such as a portable terminal device or a relatively inexpensive network-compatible household electrical appliance, either content writing or reading is smoothly performed. The possibility of not being performed increases, and as a result, smooth streaming of content becomes difficult.

  That is, the conventional playback device has a technical problem that it is difficult to perform high-quality streaming playback of content without being affected by the processing capability of the playback device.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a streaming playback device that can realize smooth and high-quality streaming playback of content regardless of the processing capability of the playback device. .

  In order to solve the above-described problem, the streaming playback apparatus according to claim 1 holds content data related to content and accommodates the fragment of the content data requested to be transferred in a network together with at least one data providing node capable of transferring the content data. A first storage device having a volatile storage area, and a second storage device having a nonvolatile storage area and having a slower writing speed and a larger storage capacity than the first storage device, A streaming playback device capable of streaming playback of content, wherein the fragment Na including playback start data capable of starting streaming playback of the content as the fragment to the data providing node is continuous with at least the fragment Na With fragment Nb containing data part Request means for requesting transmission, acquisition means for acquiring the fragments Na and Nb transferred from the data providing node via the network, and the acquired fragment Na is stored in the volatile storage area. First storage control means for controlling the first storage device, and second storage control means for controlling the second storage device so that the acquired fragment Nb is accumulated in the nonvolatile storage area, At the time when the reproduction start data is accumulated, the accumulated fragment Na is sequentially read to start streaming reproduction of the content, and at the time when streaming reproduction of the content corresponding to the accumulated fragment Na is completed, The accumulated fragment Nb is continued to the accumulated fragment Na And a first specifying unit that specifies a communication state between the data providing node via the network, a reproducing unit that sequentially reads out the content and continues the streaming reproduction of the content, and states of the first and second storage devices Based on the specified communication status, the status of the first and second storage devices, and the status of the content, the second specifying means for specifying the content, the third specifying means for specifying the status of the content, Determining means for determining the fragments Na and Nb and the transfer rate thereof so that the accumulation of the fragment Nb ends before or at the same time as the reading ends, and the request means includes the data providing node Requesting transfer of the determined fragments Na and Nb at the determined transfer rate. Features.

  In order to solve the above-described problem, the streaming playback method according to claim 14 holds content data related to content and accommodates the fragment of the content data requested to be transferred in a network together with at least one data providing node capable of transferring the content data. A first storage device having a volatile storage area, and a second storage device having a nonvolatile storage area and having a slower writing speed and a larger storage capacity than the first storage device, A streaming playback method in a streaming playback apparatus capable of streaming playback of content, the fragment Na including playback start data capable of starting streaming playback of the content as the fragment to the data providing node, and at least the fragment Na and consecutive days A request step for requesting transfer with a fragment Nb including a portion, an acquisition step for acquiring the fragment Na and Nb transferred from the data providing node via the network, and the acquired fragment Na being the volatile A first storage control step of controlling the first storage device so as to be accumulated in the sexual storage area; and controlling the second storage device so that the acquired fragment Nb is accumulated in the nonvolatile storage area A second storage control step, and when the playback start data is stored, the stored fragment Na is sequentially read to start streaming playback of the content, and the content streaming corresponding to the stored fragment Na When reproduction is completed, the accumulated fragment Nb is accumulated. A playback step of sequentially reading out the content Na from the continuous portion of the fragment Na and continuing the streaming playback of the content; a first specifying step of specifying a communication state between the data providing nodes via the network; A second specifying step for specifying the states of the first and second storage devices, a third specifying step for specifying the state of the content, the specified communication state, the states of the first and second storage devices, and the state of the content And determining the fragment Na and Nb and the transfer rate thereof so that the accumulation of the fragment Nb ends before or at the same time as the reading of the fragment Na ends, The requesting step is for the data providing node to determine the determined fragment N according to the determined transfer rate. It is characterized by requesting transfer of a and Nb.

  In order to solve the above-described problems, a computer program according to a fifteenth aspect causes a computer system to function as the content reproduction device according to any one of the first to thirteenth aspects.

In order to solve the above-mentioned problem, a recording medium according to a sixteenth aspect records the computer program according to the fifteenth aspect.
<Embodiment of Streaming Playback Device>

  The embodiment of the streaming playback apparatus of the present invention holds content data related to content and is accommodated in a network together with at least one data providing node capable of transferring a fragment of the content data requested to be transferred. Streaming playback of the content, comprising: a first storage device having an area; and a second storage device having a nonvolatile storage area and a writing speed slower than that of the first storage device and a large storage capacity. A possible streaming playback apparatus, wherein the data providing node includes, as the fragment, a fragment Na including playback start data capable of starting streaming playback of the content, and a fragment including at least a data portion continuous with the fragment Na Necessary to request transfer with Nb Means, acquisition means for acquiring the fragments Na and Nb transferred from the data providing node via the network, respectively, and the first fragment so that the acquired fragment Na is accumulated in the volatile storage area. First storage control means for controlling a storage device, second storage control means for controlling the second storage device so that the acquired fragment Nb is accumulated in the nonvolatile storage area, and the reproduction start data The accumulated fragments Na are sequentially read out at the time of accumulation to start streaming reproduction of the content, and the accumulated fragments at the time when streaming reproduction of the content corresponding to the accumulated fragment Na is completed. Read Nb sequentially from the portion that continues to the accumulated fragment Na Then, the reproduction means for continuing the streaming reproduction of the content, the first identification means for identifying the communication state between the data providing node via the network, and the states of the first and second storage devices are identified. And reading out the fragment Na based on the specified communication status, the status of the first and second storage devices, and the status of the content. Determining means for determining the fragments Na and Nb and their transfer rate so that the accumulation of the fragment Nb ends before or at the same time as the termination, and the request means , Request transfer of the determined fragments Na and Nb at the determined transfer rate.

  The first storage device having a volatile storage area according to the embodiment is, for example, various memory devices such as a RAM (Random Access Memory), and the second storage device having a nonvolatile storage area is, for example, an HDD. Etc. However, these practical aspects are not limited in any way as long as the relative relationship between the writing speed and the storage capacity is satisfied.

  The “network” according to the embodiment is, for example, a WAN (Wide Area Network) network, a LAN (Local Area Network) network, or a WAN, an ADSL (Asymmetric Digital Subscriber Line), or an optical fiber via the WAN network or the LAN network. 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, at the time of operation, the request unit requests transfer of the fragment Na and the fragment Nb to one or a plurality of data providing nodes.

  The fragments Na and Nb that are required to be transferred are fragments as fragment data obtained by dividing content data, and are preferably a set of a plurality of transfer unit data. The fragment Na is data including reproduction start data (data corresponding to a data amount specific to the streaming reproduction device) necessary for starting streaming reproduction of the content. Fragment Nb is data including a data portion continuous with fragment Na.

  Note that supplementing the fragment Nb, the fragment Nb is preferably a fragment that includes a data portion that is continuous with the final data portion of the fragment Na to a data portion that defines the final position of the content data. However, as long as the continuous portion with the fragment Na is included, a part thereof may overlap with the fragment Na. Further, it is not always necessary to include a data portion that defines the final position.

  In one or a plurality of data providing nodes, the fragments designated by the transfer request are sequentially transferred to the embodiment of the streaming playback device via the network. At this time, as far as at least the fragment Na is concerned, it is preferably transferred sequentially from the data corresponding to the head of the content data. Fragments transferred from each data providing node are sequentially acquired for each by the acquisition means. In addition, the transmission / reception mode of various data including the transfer request with the data providing node may be, for example, via an appropriate server device, or not via a server device such as P2P (Peer To Peer), for example. It may be.

  On the other hand, according to the embodiment, among the transferred fragments, the fragment Na is stored in the volatile storage area in the first storage device, and the fragment Nb is stored in the nonvolatile storage area in the second storage device. It should be noted that which fragment is transferred from one or a plurality of data providing nodes is determined by information such as a fragment position described in a protocol or the like transmitted when each data providing node transfers the fragment. .

  On the other hand, in the process in which the acquired fragments are accumulated in the appropriate storage areas (storage devices), the playback means starts streaming the content at the appropriate start timing. More specifically, the playback means sequentially reads the fragment Na from the volatile storage area after the playback start data is accumulated in the volatile storage area of the first storage device, and starts streaming playback of the content.

  When streaming playback is started, the fragment amount (that is, the cache amount) accumulated in the volatile storage area of the first storage device is determined by the transfer speed of the fragment Na and the content playback speed (preferably the content encoding). Increase / decrease at an increase / decrease speed determined by the relative relationship with the bit rate.

  For example, the fragment Na is acquired in a wider band than the playback speed of the content until the cache amount reaches the storage capacity of the volatile storage area (capacity on the hardware or the capacity permitted according to the load status at that time). Thereafter, when taking measures such as matching the reproduction speed and the transfer rate of the fragment Na, if the reproduced cache data is sequentially discarded from the volatile storage area, the cache amount is the first storage device. The storage capacity is maintained for a while after reaching the storage capacity allowed for. Further, the cache amount gradually decreases after the writing of the fragment Na is completed.

  When the cache amount becomes zero with the decrease in the cache amount of the first storage device, the storage device as a so-called playback buffer is switched from the first storage device to the second storage device, and the non-volatile storage of the second storage device The fragment Nb stored in the area is sequentially read from the portion that is continuous with the last read fragment Na, and the streaming reproduction is continued.

  Here, by storing the fragment Na and the fragment Nb in the appropriate storage area in parallel with each other at least in part, for example, the content data is stored only in the first storage device having a relatively small storage capacity. Compared to storing the content data or storing the content data only in the second storage device having a relatively low writing speed, the time required to acquire the content data can be shortened. As a result, it is possible to perform high-quality streaming reproduction that is not easily affected by a network failure or the like.

  By the way, the processing related to the writing and reading of fragments to and from the nonvolatile storage area is a process that is more expensive than that to the volatile storage area. Capability is often required. Therefore, in various portable terminals where data processing capability is not always given the highest priority, relatively inexpensive network-compatible household electric appliances, etc., the fragment writing speed is reduced or fragment reading is not performed smoothly. A new problem occurs, and after all, it is difficult to solve the problem that the reproduction quality of the content is likely to deteriorate.

  Therefore, in the streaming playback device in the present embodiment, the state of communication with the data providing node via the network, the state of the first and second storage devices, and the content by the action of the first, second, and third specifying means. The determination means determines a fragment Na and a fragment Nb to be requested from the data providing node based on the specified elements together with the transfer rate.

  The network communication state specified by the first specifying means includes, for example, the transmission band of the data providing node, the reception band of the streaming playback device, the transmission speed of the network, RTT (Round Trip Time), TTL (Time To Live), and Means hardware performance. Further, the state of each storage device specified by the second specifying means means, for example, a usable storage capacity or a load state in each storage device. Furthermore, the content state specified by the third specifying means means the data size of the content, the playback speed (encoded bit rate), and the like. Each of these various specified elements is a time axis between the read end timing of the fragment Na in the first storage device and the write end timing of the fragment Nb in the second storage device, either alone or by combining a plurality of elements. This information can be used to estimate the above relationship.

  Here, the determining means, based on the information specified by each of these specifying means, before the end of reading of the fragment Na or at the same time as the completion of the fragment Nb, Determine the transfer rate. The requesting unit requests the data providing node to transfer the determined fragments Na and Nb at the determined transfer rate.

  The overlap between the fragment writing process and the reading process in the second storage device described above occurs when the reading of the fragment Na ends before the end of the writing of the fragment Nb. Therefore, if such a situation is avoided, that is, if the writing of the fragment Nb is completed before or at the same time as the reading of the fragment Na, the fragment writing process and the reading process in the second storage device are mutually Will be performed at different times. If these are not executed in duplicate on the time axis, the fragment writing process and the reading process will not interfere with each other, and the content will be smooth and high regardless of the processing capability of the playback device. Quality streaming playback is realized.

  Fragments Na and Nb that can realize such a relationship on the time axis can be obtained by defining the transfer rates of both fragments at the time of the transfer request by the requesting means. Conversely, if the fragments Na and Nb are defined in advance, the transfer rates of both fragments that can realize such a relationship on the time axis can be obtained. However, since there are various restrictions on the data transfer speed between the streaming playback device and the data providing node, it is needless to say that the former is more realistic than the latter. That is, as a preferred embodiment, the fragment is set as a result of various calculation processes based on the transfer speed of both fragments which are set in advance or appropriately set each time (in any case, which is a category of “determination”). Na and Nb are determined.

  Note that the determining means can relatively freely divide the content data into each fragment as long as the reading of the fragment Na is not completed during the writing of the fragment Nb.

  At this time, the end timing of the writing process with respect to the non-volatile storage area of the second storage device and the end timing of the reading process with respect to the volatile storage area of the first storage device (ie, uniquely, the non-volatile storage of the second storage device). Is smaller from the viewpoint of reducing the overall transfer time of content data.

  On the other hand, the communication state via the network, the load state of each storage device, etc. are not necessarily constant. Therefore, if there is no redundancy in the time interval, for example, the write processing in the second storage device is temporarily performed for some reason. In the case of delay or the like, the writing process and the reading process for the non-volatile storage area of the second storage device coexist for a transitional period including the switching of the buffer from the first storage device to the second storage device. Smooth streaming of content may be hindered. From this point of view, an appropriate standard for the time interval is established so that both the transfer time and reproduction quality can satisfy the required values experimentally, empirically, theoretically or based on simulation. It may be done.

  Note that the specifying process according to the specifying means may be executed periodically, for example, at a constant or indefinite period, or may be executed on demand when an appropriate condition is satisfied. 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 process such as acquisition is not limited in any way.

  Note that each means according to the embodiment of the streaming playback device is, for example, various arithmetic processing devices such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit), various processors, controllers, various functional modules, etc. It may be configured as.

  In one aspect of the embodiment of the streaming playback device, a plurality of the data providing nodes are accommodated in the network, and based on the specified communication state, the state of the first and second storage devices, and the state of the content, A plurality of data providing nodes that should request the transfer of the determined fragment Na are selected from among the plurality of data providing nodes, and each of the plurality of data providing nodes that should request the transfer of the selected fragment Na On the basis of the first allocation means for allocating a part of the determined fragment Na to be transferred respectively, the specified communication state, the state of the first and second storage devices, and the state of the content A plurality of data to be requested to transfer the determined fragment Nb from the plurality of data providing nodes A second allocation for selecting a serving node and allocating a part of the determined fragment Nb to be transferred to each of a plurality of data providing nodes to be requested to transfer the selected fragment Nb. Means for requesting each of a plurality of data providing nodes that should request transfer of the selected fragment Na to each of a part of the allocated fragment Na, and A part of the allocated fragment Nb is requested to each of the plurality of data providing nodes that should request the transfer of the selected fragment Nb.

  When a plurality of data providing nodes are accommodated in the network, a node that requests fragments Na and Nb can be relatively freely selected from the plurality of data providing nodes. In particular, when selecting a data providing node based on the specified communication state, the state of the first and second storage devices, and the state of the content, the most suitable data providing node for requesting the transfer of the fragment is Alternatively, it is possible to reliably select a plurality of data providing nodes that are relatively suitable for requesting transfer of fragments.

  Therefore, for example, when the reception bandwidth of the streaming playback device is larger than the transmission bandwidth of each data providing node, the fragment Na or Nb is appropriately divided, and the divided fragments are divided from a plurality of data providing nodes. By taking measures such as acquisition, the reception band can be used more efficiently.

  The practical aspect regarding the selection of the data providing node and the assignment of the fragments according to the first assigning means and the second assigning means is as long as the fragments Na and Nb determined by the determining means and their transfer rates are guaranteed. Is not limited. This is because, as long as the data sizes of the fragments Na and Nb and their transfer rates are secured, the writing and reading of the fragments will not occur simultaneously in the second storage device.

  In this aspect, the first assigning unit, when a network failure occurs with at least one data providing node among the plurality of data providing nodes that should request the transfer of the selected fragment Na, Reselecting at least one data providing node to be replaced with at least one data providing node corresponding to the occurred network failure from among the plurality of data providing nodes, and including the reselected data providing node Reassigning a part of the determined fragment Na that has not yet been transferred to each of a plurality of data providing nodes that should newly request transfer of the fragment Na. , The second allocating means should request a plurality of transfer of the selected fragment Nb When a network failure occurs with at least one data providing node among the data providing nodes, the plurality of data providing nodes are replaced with at least one data providing node corresponding to the generated network failure Reselecting at least one data providing node to be transferred, and each of the plurality of data providing nodes including the reselected data providing node to newly request transfer of the fragment Nb, A part of the determined fragment Nb that has not been transferred may be reassigned.

  In the configuration in which fragments can be obtained from a plurality of data providing nodes, as described above, the reception band of the streaming playback device can be effectively used. On the other hand, various temporary or long-term networks can be obtained. The possibility of being affected by a failure is also increased.

  For example, when a network failure occurs with a part of the data providing nodes selected to request the fragment Nb, the completion of acquisition of the fragment Nb is delayed, and reading and writing of the fragment Nb are temporarily or simultaneously performed. It can happen. Alternatively, when a network failure occurs with a part of the data providing nodes selected to request the fragment Na, the completion of the acquisition of the fragment Na is delayed and the reproduction of the content may be interrupted.

  According to this aspect, since the first and second allocating units are provided with the data selection node reselection and the fragment reassignment function with respect to the reselected data provision node, it is possible to quickly perform even when an instantaneous network failure occurs. In addition, it is possible to cope flexibly, and it is possible to stably continue streaming playback of content. It should be noted that the detection of a network failure can always be detected without delay based on information such as whether or not data (part of a fragment) requested to be transferred has been transferred.

  In another aspect of the embodiment of the streaming playback device of the present invention, the fragment is included in at least one of the fragment Na and the fragment Nb.

  According to this aspect, the content data is formed by the fragment Na that consists only of fragment data that are mutually continuous and the fragment Nb that is also composed of only fragment data that is mutually continuous. Therefore, the processing load in requesting each fragment from the data providing node can be reduced. At this time, ideally, it is desirable that there is no overlapping portion between the fragment Na and the fragment Nb.

  In another aspect of the embodiment of the streaming playback device of the present invention, the transfer rate of the fragment Na is the playback rate of the content, and the transfer rate of the fragment Nb is the bandwidth of the reception bandwidth of the streaming playback device. This is the transfer rate corresponding to the remaining reception band excluding the band corresponding to the playback speed.

  According to this aspect, the fragment Na is transferred at a transfer speed corresponding to the content playback speed, and the fragment Nb corresponds to the remaining reception band excluding the band used for the transfer of the fragment Na among the usable reception bands. It is transferred at the transfer speed to be.

  The volatile storage area of the first storage device is usually larger than the reproduction start data and smaller than the content data size. For this reason, if the acquired fragment Na reaches the storage capacity allowed for the first storage device, the transfer speed of the fragment Na is limited to the playback speed of the content, assuming that the reproduced cache is sequentially discarded. . On the contrary, if the fragment Na is acquired at the content playback speed, the content cache stored in the first storage device does not decrease until the completion of the fragment Na acquisition, so that the content playback is stable. Will continue.

  According to this aspect, the fragment Nb is acquired using the remaining band excluding the band corresponding to the playback speed, out of the reception band of the streaming playback device. Therefore, on the other hand, it is possible to efficiently accumulate the fragment Nb in the second storage device while stably reproducing the content, and to shorten the overall download time of the content data.

  In another aspect of the embodiment of the streaming playback apparatus of the present invention, the fragment Na is composed of a fragment N0 including the playback start data and a fragment N1 excluding the fragment N0, and the request means includes the fragment N0. Until the fragment Nb is requested.

  According to this aspect, the fragment Na is divided into the fragment N0 including the reproduction start data and the other fragment N1, and when requesting the fragment to the data providing node, first, the transfer of only the fragment N0 is requested. That is, until acquisition of the fragment N0 is completed, acquisition of the fragment Na has priority over acquisition of the fragment Nb. Therefore, the reception band of the streaming playback device can be preferentially used for acquiring the fragment N0, and the time required for completing the acquisition of the fragment N0 can be shortened as much as possible.

  In particular, since the fragment N0 is a fragment including the reproduction start data in the fragment Na, the acquisition is prioritized in this way, and the acquisition timing is advanced, thereby making the content reproduction start timing as possible as possible. It becomes possible to speed up.

  Note that the playback means starts streaming playback of content triggered by the completion of acquisition (accumulation) of playback start data. Accordingly, after the completion of the acquisition of the reproduction start data in the fragment N0, the acquisition of the fragment N0 proceeds at a speed corresponding to the difference between the transfer speed of the fragment N0 and the content reproduction speed. Here, when the storage capacity of the volatile storage area in the first storage device is not sufficiently large with respect to the reproduction start data (of course, at least larger than the reproduction start data), there is no interval from the start of content reproduction. The volatile storage area is filled with the fragment N0. After that, it is impossible to accumulate fragments above the playback speed. In view of this point, the data size of the fragment N0 is preferably set so that the total amount of fragments acquired at the time when the storage capacity of the first storage device is filled with the fragment N0 (rather than the storage capacity, It is desirable that

  When this aspect is applied in a mode in which the above-described fragment Na is transferred at a transfer speed corresponding to the content reproduction speed and the fragment Nb is transferred at a transfer speed corresponding to the remaining band of the reception band, the fragment N1 is applied. It is preferable to transfer the fragment Nb at the transfer rate corresponding to the remaining bandwidth after the completion of the acquisition of the fragment N0.

  In this way, by sequentially discarding the regenerated cache from the first storage device, the amount of fragments accumulated in the first storage device remains unchanged in time until the completion of acquisition of the fragment N1. Therefore, the remaining reception band of the streaming playback apparatus or the remaining transmission band of the data providing node is efficiently used for acquiring or transferring the fragment Nb without considering the buffer overflow or buffer underflow in the first storage device. be able to. Further, since the fragment Nb is transferred at the maximum transfer speed at that time, the fragment Nb can be acquired as quickly as possible, and the download time of the content data can be shortened.

  At this time, as described above, if the storage capacity of the first storage device is used to the maximum when the acquisition of the fragment N0 is completed, the first storage device stores the storage until the completion of the acquisition of the fragment N1. The state where the capacity is used to the maximum is maintained, which is more preferable.

  In this aspect, the transfer rate of the fragment N0 may be a maximum transfer rate defined between the data providing nodes.

  The transfer at the maximum transfer rate is equivalent to that the use efficiency of the reception band of the streaming playback device is theoretically or substantially maximum within a certain limitation range. Therefore, in this case, the fragment N0 can be acquired in the shortest time under allowable conditions, and the time delay from when the content playback request is made until the streaming playback is started is maximized. Can be

  The use efficiency of the reception band is maximized at 100% when the entire reception band is used for obtaining the fragment N0 (the transfer speed in this case is the theoretical maximum transfer speed). For example, when there is one data providing node and the transmission bandwidth exceeds the reception bandwidth of the streaming playback device, the transfer rate of the fragment N0 can be made equal to the reception bandwidth, and the usage efficiency of the reception bandwidth is 100. %. On the other hand, if there is one data providing node and its transmission band is smaller than the reception band of the streaming playback device, the entire reception band cannot be used, and the utilization efficiency is less than 100%. If there is only one providing node, if substantially all of the transmission band is used for the transfer of the fragment N0, the fragment N0 is eventually transferred at the maximum transfer rate.

  On the other hand, for example, when there are a plurality of data providing nodes as in the above-described aspect, the number of data providing nodes can be increased until the sum of the transmission bands of the data providing nodes exceeds the reception band. In this case, the entire reception band can be used for obtaining the fragment N0 regardless of the transmission band of each data providing node, which is effective.

  When requesting a fragment N0 to a plurality of data providing nodes, the data positions of the fragments constituting the fragment N0 are basically different among the nodes. However, packet errors may frequently occur when transferring fragments depending on the data transmission protocol. In such a case, frequently requesting retransmission of fragments may not necessarily lead to efficient data transfer. From such a point of view, when requesting transfer at the maximum transfer rate, a fragment N0 that partially or entirely overlaps a plurality of nodes may be requested in advance.

  In another aspect of the embodiment of the streaming playback device of the present invention, the requesting unit requests the fragment Na so that the fragment Na is sequentially acquired from the head of the content data, and the fragment Nb is the last. The fragment Nb is requested to be sequentially acquired from the tail fragment, and the acquisition means acquires the fragment Na and the fragment Nb so that the fragment Na and the fragment Nb do not overlap.

  According to this aspect, the fragment Na (including the case where the fragment is divided into the fragments N0 and N1 described above) is acquired from the start position of the content data, and the fragment Nb is acquired from the end position of the content data. Therefore, the fragment Na and the fragment Nb finally meet at one data position of the content data in the process of parallel acquisition.

  That is, the fragment Na in this aspect is not a fragment with a preset data amount, but the beginning of the fragment Nb from the beginning position of the content data (the beginning as the content playback order, and the acquisition order is the end. It is a fragment having a data amount up to (some) data. Similarly, the fragment Nb in this aspect is not a fragment having a preset data amount but a fragment having a data amount from the last position of the content data to the last data of the fragment Na.

  Here, as described above, the transmission state of the network, the load state of the first and second storage devices, etc. are never invariant in time, and may vary within the range of the content data download time. Not uncommon. In such a case, if the data amounts of the fragments Na and Nb are determined in advance, there is a possibility that the reading of the fragment Na is completed before the writing of the fragment Nb is completed.

  In this respect, if the transfer request is constructed so that the fragment Na is transferred from the head and the fragment Nb is transferred from the tail, it is realistic to reflect the transmission state of the network and the load state of each storage device. In the data transfer process, it is possible to reliably prevent a situation where reading of the fragment Na ends before the writing of the fragment Nb ends.

  That is, if the writing of the fragment Nb to the non-volatile storage area of the second storage device is delayed for some reason, the fragment Na becomes larger correspondingly, and the fragment Na to the volatile storage area of the first storage device for some reason. If the writing is delayed, the fragment Nb increases accordingly.

  In another aspect of the embodiment of the streaming playback apparatus of the present invention, the first specifying unit specifies a reception band of the streaming playback apparatus and a transmission band of the data providing node.

  According to this aspect, the first specifying unit specifies the reception band of the streaming playback device and the transmission band of the data providing node as the communication state. These are important information for estimating the read end timing of the fragment Na and the write start timing of the fragment Nb, and are suitable examples of the “communication state” according to the embodiment.

  In another aspect of the embodiment of the streaming playback device of the present invention, the second specifying means specifies the remaining capacity and the load state of the first and second storage devices.

  According to this aspect, the remaining capacity and the qualitative or quantitative load state are specified as the state of each storage device by the second specifying unit. These are important information for estimating the read end timing of the fragment Na and the write start timing of the fragment Nb, and are suitable examples of the “states of the first and second storage devices” according to the embodiment.

  In another aspect of the embodiment of the streaming playback apparatus of the present invention, the third specifying means specifies the data size and playback speed of the content.

  According to this aspect, the data size and playback speed of the content are specified as the content state by the third specifying means. These are important information for estimating the read end timing of the fragment Na and the write start timing of the fragment Nb, and are suitable examples of the “content state” according to the embodiment.

  In another aspect of the embodiment of the streaming playback device of the present invention, the second storage control means sets the second storage device so that the sequentially read fragment Na is accumulated in the second storage device. Control.

  The storage area of the first storage device is a volatile storage area, and only holds the fragment Na temporarily, and the read data fragment of the fragment Na basically disappears. As a result, of the content data, the data remaining in the streaming playback device after playback is only the fragment Nb. Therefore, the next time the same content is to be reproduced, it becomes necessary to acquire the fragment Na again, which is not efficient.

  According to this aspect, for example, every time a data fragment of the fragment Na is read from the volatile storage area of the first storage device, the data fragment is duplicated, and the second storage control means operates to store the second storage device. It is written in the non-volatile storage area.

  Therefore, after the streaming playback of the content is completed, the entire content data is stored in the nonvolatile storage area of the second storage device, and when it is desired to play back the content again, redundant data transfer becomes unnecessary. Smooth and efficient reproduction is possible.

  Even if the fragment Na after reading is written to the second storage device in this way, the writing processing and the reading processing for the nonvolatile storage area of the second storage device are not executed in parallel, and smooth. And the effect of embodiment which enables high quality streaming reproduction | regeneration is ensured reliably.

  In another aspect of the embodiment of the streaming playback apparatus of the present invention, the second control means erases the fragments stored in the nonvolatile storage area in response to a predetermined erase request.

  According to this aspect, it is automatically generated through various controllers or the like, triggered by an artificial operation through various input means such as a keyboard, various pointing devices, or various switches, or when some erasing condition is satisfied. In response to the erasure request, the fragment stored in the non-volatile storage area of the second storage device, for example, the fragment Nb or the fragment Na (that is, the content data itself in this case) is erased. Therefore, the non-volatile storage area of the second storage device can be used efficiently.

  An embodiment according to the streaming playback method of the present invention holds content data related to content and is accommodated in a network together with at least one data providing node capable of transferring a fragment of the content data requested to be transferred. Streaming playback of the content, comprising: a first storage device having an area; and a second storage device having a nonvolatile storage area and a writing speed slower than that of the first storage device and a large storage capacity. A streaming playback method in a possible streaming playback device, the fragment Na including playback start data capable of starting streaming playback of the content as the fragment to the data providing node, and data continuous with at least the fragment Na Flag with part A requesting step for requesting transfer to and from the client Nb, an acquiring step for acquiring the fragment Na and Nb transferred from the data providing node via the network, and the acquired fragment Na in the volatile storage area. A first storage control step for controlling the first storage device so as to be stored in the second storage device, and a second storage for controlling the second storage device so that the acquired fragment Nb is stored in the nonvolatile storage area The control step, and when the reproduction start data is accumulated, the accumulated fragment Na is sequentially read to start streaming reproduction of the content, and the streaming reproduction of the content corresponding to the accumulated fragment Na ends. When the accumulated fragment Nb is replaced with the accumulated fragment a playback step of sequentially reading out the content continuously from the portion that continues to a, a first specifying step of specifying a communication state between the data providing nodes via the network, the first and first 2 based on the second specifying step for specifying the state of the storage device, the third specifying step for specifying the state of the content, the specified communication state, the state of the first and second storage devices, and the state of the content. Determining the fragment Na and Nb and their transfer rate so that the accumulation of the fragment Nb ends before or at the same time as the reading of the fragment Na ends, and the requesting step comprises: , Transferring the determined fragments Na and Nb to the data providing node at the determined transfer rate. Request.

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.
<Embodiment of Computer Program>

  The embodiment according to the computer program of the present invention causes a computer system to function as any one of the above streaming playback devices.

  The computer program is loaded 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 of 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.
<Embodiment of Recording Medium>

  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, the request unit, the acquisition unit, the first storage control unit, the second storage control unit, the playback unit, the first specifying unit, and the second specifying unit. Since the third specifying means and the determining means are provided, smooth and high-quality streaming reproduction of content can be realized regardless of the processing capability of the reproducing apparatus.

  As described above, according to the embodiment of the streaming playback method of the present invention, the request process, the acquisition process, the first storage control process, the second storage control process, the playback process, the first specifying process, and the second specifying process. Since the third specifying step and the determination step are provided, smooth and high-quality streaming reproduction of content can be realized regardless of the processing capability on the reproducing apparatus side.

  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 apparatus of the present invention.

  As described above, according to the embodiment of the recording medium of the present invention, by recording the embodiment of the computer program of the present invention, the computer system functions as the embodiment of the streaming playback apparatus of the present invention. be able to.

  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 a configuration of a content reproduction device in the streaming system of FIG. 1. It is a flowchart of the streaming reproduction control performed in the content reproduction apparatus of FIG. 3 is a flowchart of a preparation process which is a subroutine of the streaming reproduction control of FIG. FIG. 3 is a flowchart of initial fragment processing which is a subroutine of streaming reproduction control of FIG. 2. FIG. It is a flowchart of the parallel fragment process which is a subroutine of the streaming reproduction control of FIG. 3 is a flowchart of a post-reception process that is a subroutine of the streaming reproduction control of FIG. 2. It is a conceptual diagram of the flow of each fragment in the streaming reproduction control of FIG. It is a figure which illustrates 1 time transition of each data amount in the streaming reproduction | regeneration control of FIG. It is a flowchart of the streaming reproduction | regeneration control which concerns on 2nd Example of this invention. It is a flowchart of the initial fragment process which is a subroutine of the streaming reproduction | regeneration control of FIG. It is a flowchart of the parallel fragment process which is a subroutine of the streaming reproduction control of FIG. It is a flowchart of the post-reception process which is a subroutine of the streaming reproduction control of FIG. It is a conceptual diagram of the flow of each fragment in the streaming reproduction control of FIG. It is a schematic block diagram which represents notionally the structure of the streaming system based on 3rd Example of this invention. It is a flowchart of the streaming reproduction control performed in the content reproduction apparatus of FIG. FIG. 17 is a flowchart of a preparation process that is a subroutine of the streaming playback control of FIG. 16. FIG. FIG. 17 is a flowchart of initial fragment processing, which is a subroutine for streaming playback control in FIG. 16. FIG. It is a flowchart of the parallel fragment process which is a subroutine of the streaming reproduction | regeneration control of FIG. It is a conceptual diagram of the flow of each fragment in the streaming reproduction control of FIG.

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 content reproduction device 100 and a data providing node 300 (that is, according to the present invention) each accommodated in a wide area network 200 (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 content playback apparatus 100. More specifically, the content playback apparatus 100 is configured to request content data from the data providing node 300 and perform streaming playback based on fragmented data of the content data transferred from the data providing node 300. ing.

  Note that the configuration of the streaming system 1 illustrated in FIG. 1 is merely an example for performing streaming playback on the content playback apparatus 100. For example, in the streaming system 1, the content playback device 100 and the data providing node 300 are configured to perform P2P communication individually without going through a specific server device. May communicate via an appropriate server device accommodated in the network 200. In FIG. 1, one data providing node 300 is shown. However, the number of data providing nodes is basically not limited except for realistic restrictions, and a plurality of data providing nodes may be provided. 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 200 can appropriately be data providing nodes. At the same time, the content reproduction apparatus 100 can be transferred to other nodes. On the other hand, it can be one of the data providing nodes. The case where there are a plurality of data providing nodes will be described in the third embodiment.

  Next, the configuration of the content reproduction apparatus 100 will be described with reference to FIG. FIG. 2 is a block diagram conceptually showing the configuration of the content reproduction apparatus 100. 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 content reproduction apparatus 100 includes a control unit 110, a protocol generation unit 120, a transmission unit 130, a reception unit 140, a reception data processing unit 150, an HDD 160, a high-speed memory 170, and a reproduction unit 180 according to the present invention. It is an example of a “streaming playback device”.

  The control unit 110 is an electronic control device that controls the overall operation of the content playback device 10, which 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). In accordance with a computer program stored in the ROM, it is configured to be able to execute streaming playback control to be 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 a hard disk, 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 110 functions as an example of each of the “determination unit”, “first identification unit”, “second identification unit”, and “third identification unit” according to the present invention in the execution process of the streaming playback control. It is the composition to do.

  The protocol generation unit 120 is a processing unit that generates a data request protocol for requesting the data providing node 300 for various fragments that are fragment data of content data, and is an example of the “request unit” according to the present invention. Note that the protocol generator 120 is configured such that its operation is controlled by the controller 110 at a higher level.

  The transmission unit 130 is a transmission interface having an output terminal (not shown) connected to the network 200, and is configured to be able to transmit various data designated by the control unit 110 to the data providing node 300 via the network 200. Yes. Note that the data request protocol generated by the protocol generation unit 120 in the process in which the control unit 110 executes streaming playback control is also transmitted from the transmission unit 130 as one of the data. That is, the transmission unit 130 is configured to function as an example of the “request unit” according to the present invention, together with the protocol generation unit 120.

  The receiving unit 140 is a receiving interface that is an example of an “acquiring unit” according to the present invention, whose output terminal (not shown) is connected to the network 200, and various types of data transferred from the data providing node 300 via the network 200. It is configured to receive data. Various fragments transferred from the data providing node 300 via the network 200 are also received by the receiving unit 140 as one of the data.

  The reception data processing unit 150 is a processing unit that analyzes the content of reception data received via the reception unit 140. The reception data processing unit 150 is configured such that its operation is controlled by the control unit 110 at a higher level. For example, the reception data processing unit 150 can identify the fragment position and data size of the transferred fragment by analyzing a transmission protocol that the data providing node 300 transfers together with the fragment.

  The HDD 160 includes a hard disk having a relatively large capacity (for example, several tens to several hundreds GB or several TB) of a non-volatile storage area, an optical pickup device that performs information recording / reproduction processing on the hard disk, and a control system thereof. Is a storage device that is an example of a “second storage device” according to the present invention.

  The high-speed memory 170 includes a volatile storage area having a storage capacity M (byte) of a small capacity (for example, several hundred MB to several GB) compared to the HDD 160 (strictly speaking, compared to a hard disk provided in the HDD 160). It is a memory element and is an example of the “first storage device” according to the present invention. The high-speed memory 170 can write information in the volatile storage area at a speed sufficiently faster (for example, several times to several tens of times) than the writing speed of the HDD 160. On the other hand, the high-speed memory 170 is configured to erase the read data from the volatile storage area.

The playback unit 180 is a content playback unit including a decoder unit that can decode and output content data or fragment data thereof at a playback speed P (byte / sec) equal to the encoding bit rate. It is an example of “reproducing means”. Note that the playback unit 180 is configured such that its operation is controlled by the control unit 110 at a higher level.
<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.

  The streaming playback control is control for realizing streaming playback of content in the content playback apparatus 100. Content data necessary for content reproduction is not stored in the content reproduction device 100 and is acquired from the data providing node 300 via the network 200. At this time, the data acquired from the data providing node 300 is acquired as a unit of fragment data obtained by subdividing the content data according to a predetermined standard. This fragment data constructs a data unit called a fragment.

  The fragment is composed of a fragment N0, a fragment N1, and a fragment N2, and the sum of these is equal to the content data. Data allocation (data amount and data position) between fragments is defined by a data request protocol generated in the protocol generation unit 120.

  The content playback device 100, when the playback start data corresponding to the data amount of M0 (bit) (hereinafter referred to as “playback start data amount M0” as appropriate) is acquired from the top data among the acquired content data Thus, the reproduction of the content can be started. The streaming playback control is a control aimed at realizing smooth and high-quality streaming playback regardless of the processing capability of the control unit 110 while suppressing the time from the transmission point of the data request protocol to the completion of downloading of the content data. .

<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 this embodiment, it is assumed that the data providing node 300 holds all the content data related to the content to be reproduced.

  In FIG. 3, the control unit 110 sequentially executes each subroutine in the order of preparation processing (step S100), initial fragment processing (step S200), parallel fragment processing (step S300), and post-reception processing (step S400). When the post-reception process ends, the streaming playback control ends.

<Details of preparation process>
Next, the details of the preparation process will be described with reference to FIG. FIG. 4 is a flowchart of the preparation process.

  In FIG. 4, the control unit 110 acquires node information (step S101).

  Here, the node information means the IP address of the data providing node 300, information on fragments to be held, information on various hardware performances (CPU processing speed and memory information), and the like. The node information is held by the data providing node 300 itself, and the control unit 110 can request the data providing node to provide such information. When these pieces of information are provided in response to the request, the control unit 110 sequentially analyzes them through the reception data analysis unit 150 and stores them in the RAM as node information.

  Next, the control unit 110 acquires content information (step S102). In this embodiment, the content information is a content playback speed P (byte / sec) and a content size N (byte). Step S102 is an example of the operation of the “third specifying means” according to the present invention to specify the state of the content. At this time, the control unit 110 transmits a request for urging transmission of content information via the transmission unit 130, and transmits content information transmitted from the data transfer node 300 in response to the request via the reception unit 140. At the same time, the received data analysis unit 150 analyzes the content, thereby acquiring the content information and storing it in the RAM.

  Next, the control part 110 acquires a buffer state (step S103). In this embodiment, the buffer state is assumed to be the free capacity and load state (busy state) of the HDD 160 and the high-speed memory 170. Step S103 is an example of the operation of the “second specifying means” according to the present invention to specify the states of the first and second storage devices. Since both the HDD 160 and the high-speed memory 170 are constituent elements of the content reproduction apparatus 100, the control unit 110 can always acquire these pieces of information in the process of controlling the operation state of the content reproduction apparatus 100. It is assumed that the storage capacity M (byte) of the high-speed memory 170 described above is a free capacity determined to be available for content reproduction at this stage.

  Next, the control part 110 acquires a network state (step S104). In the present embodiment, the network state means a communication state between the content reproduction apparatus 100 and the data providing node 300 via the network 200, and more specifically, the reception bandwidth B (byte / byte) of the content reproduction apparatus 100. sec), transmission bandwidth C (byte / sec) of the data providing node 300, RTT (Round Trip Time) and TTL (Time To Live) as transmission delay of the network 200. Step S104 is an example of the operation of the “first specifying unit” according to the present invention to specify the communication state with the data providing node via the network.

  The reception bandwidth B and the transmission bandwidth C are set values in the content reproduction device 100 and the data providing node 300. Further, RTT is measured by using SR (Sender Report) or RR (Receiver Report) of RTCP (Real-time Transport Control Protocol). Each communication bandwidth may be appropriately estimated based on an actual transmission state of data when data is transmitted / received randomly via the network 200.

  When the necessary information is acquired in steps S101 to S104, the control unit 110 determines the fragment size of the content data (step S105). Here, a method for determining the fragment size in the present embodiment will be described. First, the control unit 110 divides the content data into three types of fragments: a fragment N0, a fragment N1, and a fragment N2. That is, the following equation (1) is established. In the following formula (1), N0, N1, and N2 represent the data amount (bit) of each fragment. The fragment N0 and the fragment N1 constitute the “fragment Na” according to the present invention, and the fragment N2 constitutes the fragment Nb according to the present invention.

N = N0 + N1 + N2 (1)
Next, the control unit 110 determines the fragment N0 according to the following equation (2).

N0 = min (M + (M−M0) / (B−P) × P, N) (2)
Here, if the data amount of the comparison term on the left side of the right side of equation (2) is larger than the content size N, N0 = N, and the fragment N0 is the content data itself, but usually the content size N is Since it is sufficiently larger than the storage capacity M of the high-speed memory 170, N0 is a comparison term on the left side of the right side of equation (2).

  In this embodiment, it is assumed that the transmission bandwidth C of the data providing node 300 is sufficiently larger than the reception bandwidth B of the content reproduction device 100, and the maximum transfer speed between them is equal to the reception bandwidth B. Shall. The transfer speed of the fragment N0 is a speed corresponding to the reception bandwidth B which is the maximum transfer speed, the transfer speed of the fragment N1 is the playback speed P of the content, and the transfer speed of the fragment N2 is the playback speed from the reception bandwidth B. The speed corresponding to the remaining bandwidth excluding the bandwidth corresponding to P (that is, BP) is determined in advance.

  In the case where the data providing node 300 is a single node, if the transmission bandwidth C is less than the reception bandwidth B of the content reproduction node 100, the data transmission speed between them is naturally the transmission bandwidth C. To be ruled.

  Next, the control unit 110 determines the fragments N1 and N2 according to the following equations (3) and (4).

N1 = (N−N0) / B × P (3)
N2 = (N−N0) / B × (BP) (4)
In the above equations (3) and (4), the remaining fragments excluding the fragment N0 are allocated to the fragments N1 and N2 at the ratio of the reception bandwidth (that is, the transfer rate) allocated to the fragments N1 and N2. Means. In other words, in this embodiment, the acquisition completion timing of the fragment N1 and the acquisition completion timing of the fragment N2 ideally match.

  When the fragment size is determined, the control unit 110 secures appropriate buffer areas in the HDD 160 and the high-speed memory 170 (step S106) and ends the preparation process.

<Details of initial fragment processing>
Next, details of the initial fragment processing will be described with reference to FIG. FIG. 5 is a flowchart of the initial fragment processing.

  First, the control unit 110 requests the fragment N0 from the data providing node 300 (step S201). At this time, the control unit 110 generates a protocol for transmitting the previously determined fragment size to the data providing node 300 through the protocol generating unit 120 and transmits the protocol to the data providing node 300 through the transmitting unit 130. In this protocol, the data size N0 of the fragment N0, the fragment position of the fragment N0 in the content data, and the fragment position of each piece of fragment data constituting the fragment N0 are described.

  When the transfer of the fragment N0 is requested, the control unit 110 waits for the data providing node 300 to start the transfer of the fragment N0 according to the request, and receives the reception unit 140 for each fragment data size that fits in one packet as a data transfer unit. Fragment N0 arriving at is received (step S202). The received fragment N0 is sequentially stored in the high speed memory 170 (step S203). The processing relating to the reception of the fragment N0 and the storage in the high-speed memory 170 continues until the transfer of the fragment N0 from the data providing node 300 is completed.

  Note that since the fragment requested to the data providing node 300 at this stage is only the fragment N0, the fragment N0 is acquired using the maximum transfer rate, that is, in this case, the entire reception bandwidth B of the content reproduction device 100. Is done.

  On the other hand, in parallel with the accumulation of the fragment N0 in the high-speed memory 170, the control unit 110 determines whether or not the memory cache amount that is the fragment amount accumulated in the high-speed memory 170 is larger than the reproduction start data amount M0. (Step S204). If the memory cache amount is less than or equal to M0 (step S204: NO), the process returns to step S202.

  When the memory cache amount is larger than the reproduction start data amount M0 (step S204: YES), the control unit 110 sequentially reads and reproduces the memory cache as the fragment N0 stored in the high-speed memory 170 from the top data (step S205). . That is, at this stage, streaming playback of content is started.

  When streaming playback of content is started, the control unit 110 determines whether or not the received data amount is equal to or greater than the data amount N0 of the fragment N0 (step S206). If the received data amount is less than N0 (step S206: NO), the process returns to step S202. If the received data amount is N0 or more (step S206: YES), that is, the storage capacity M of the high-speed memory 170 is reached. When the corresponding fragment is accumulated, the initial fragment processing ends.

<Details of parallel fragment processing>
Next, the details of the parallel fragment processing will be described with reference to FIG. FIG. 6 is a flowchart of parallel fragment processing.

  First, the control unit 110 requests the fragments N1 and N2 from the data providing node 300 (step S301). At this time, the control unit 110 generates a protocol for transmitting the previously determined fragment size to the data providing node 300 through the protocol generating unit 120 and transmits the protocol to the data providing node 300 through the transmitting unit 130. This protocol describes the data sizes N1 and N2 of fragments N1 and N2, the fragment positions of fragments N1 and N2 in content data, and the fragment positions of fragment data in each fragment. In addition to this, the control unit 110 sets the transfer speed of the fragment N1 as the content playback speed P, and sets the transfer speed of the fragment N2 as the remaining bandwidth excluding the playback speed P from the reception bandwidth B. An instruction is given to the data providing node 300.

  When reception of a fragment is started (step S302), the control unit 110 determines whether the received fragment is the fragment N1 or the fragment N2 via the reception data analysis unit 150 (step S303).

  When the received fragment is the fragment N1 (step S303: YES), the control unit 110 accumulates the fragment in the high speed memory 170 (step S304) and reads the cache from the high speed memory 170 to reproduce the memory cache. Playback is performed with P (step S306). That is, the fragment is read at the reproduction speed P while the fragment is written at the reproduction speed P in the high-speed memory 170. Therefore, the fragment amount stored in the high-speed memory 170 is basically maintained at the storage capacity M.

  On the other hand, when the received fragment is the fragment N2 (step S303: YES), the control unit 110 accumulates the received fragment in the HDD 160 (step S305).

  When step S305 or step S307 is executed, the control unit 110 determines whether or not the received data amount, which is the amount of data received after the start of streaming playback control, is equal to or greater than the content size N (step S307). ). In view of the relationship of the above expression (1), the determination processing according to step S307 means whether or not the acquisition of the fragments N1 and N2 has been completed.

  If the amount of received data is less than N (step S307: NO), control unit 110 returns the process to step S302 and repeats a series of processes. On the other hand, when the amount of received data is N or more (step S307: YES), the parallel fragment processing ends.

<Details of post-reception processing>
Next, details of post-reception processing will be described with reference to FIG. FIG. 7 is a flowchart of post-reception processing.

  In FIG. 7, the control unit 110 disconnects the communication line with the data providing node 300 via the network 200 (step S401). Subsequently, the memory cache that is the fragment accumulated from the high-speed memory 170 is read and reproduced (step S402). Note that step S402 is processing continued from step S306. Here, unlike the process according to step S306, the reproduction process at step S402 does not involve writing a new fragment. Accordingly, in the execution process of step S402, the fragment accumulation amount of the high-speed memory 170 gradually decreases from the accumulation capacity M at the reproduction speed P.

  The control unit 110 determines whether or not the memory cache amount has become zero as a result of the gradual decrease of the memory cache (step S403). If the amount of memory cache is not zero (step S403: NO), that is, if a fragment whose reproduction order is earlier than that of fragment N2 still remains in high-speed memory 170, control unit 110 continues to reproduce the memory cache. .

  On the other hand, when the memory cache amount becomes zero (step S403: YES), the control unit 110 sequentially reads and reproduces the fragment N2, that is, the HDD cache, stored in the HDD 160 (step S404). When reproduction of the HDD cache is started, the control unit 110 determines whether or not reproduction of the HDD cache has been completed (step S405). If reproduction has not been completed (step S405: NO), the process proceeds to step S405. Returning to S404, the reproduction of the fragment N2 is continued, and when the reproduction is completed (step S405: YES), the post-reception process is terminated.

<Effect of streaming playback control>
Next, the effect of streaming playback control will be described with reference to FIG. FIG. 8 is a conceptual diagram of the flow of each fragment in streaming playback control. In FIG. 8, the same reference numerals are given to the portions overlapping with the above-described drawings, and the description thereof will be omitted as appropriate.

  In FIG. 8, the flows of the fragments N0, N1, and N2 are shown together with the step numbers related to the corresponding steps in the streaming playback control. The hundreds of the step number is an identification number of the subroutine, and the smaller the step number, the faster the time series is executed.

  As is clear from this, the process of writing the fragment N0 transferred from the data providing node 300 to the high-speed memory 170 (step S203) and the process of reading the fragment N0 from the high-speed memory 170 (step S205) precede the other fragments. (Strictly speaking, since there is no distinction between N0 and N1 in the cache stored in the high-speed memory 170, a part of N0 is also read in step S306).

  On the other hand, the fragment N1 is written in the high speed memory 170 in step S304, and is read from the high speed memory 170 in step S306. That is, the fragment writing process and the reading process for the volatile storage area of the high-speed memory 170 are executed in parallel with each other. The fragment writing speed and the reading speed in the high-speed memory 170 are sufficiently high, and even if they are executed in duplicate on the time axis, there is no practical problem.

  On the other hand, the fragment writing process and the reading process for the nonvolatile storage area, which are performed through the driving of the control system and the optical pickup, require a larger load on the control unit 110 than the high-speed memory 170. Therefore, if these are executed in duplicate on the time axis, the reading of the fragments is delayed and smooth playback of the content is hindered, or the period in which the writing of the fragments is delayed and these overlap on the time axis is further increased. It becomes a factor that the reproduction quality of content deteriorates, such as becoming longer. In particular, the tendency becomes strong in portable terminals and relatively inexpensive network-compatible household electric appliances in which the processing capability of the control unit 110 is regulated within a range of various practical restrictions.

  In this regard, according to the present embodiment, the process of writing the fragment N2 to the nonvolatile storage area of the HDD 160 is executed in step S305, and the process of reading the fragment N2 from the nonvolatile storage area of the HDD 160 is executed in step S403. The That is, the latter is surely slower in time series than the former. Therefore, according to the present embodiment, the writing process and the reading process with respect to the nonvolatile storage area of the HDD 160 do not overlap, and there is no concern that the reproduction quality of the content is lowered according to the processing capability of the control unit 110. That is, the reproduction quality of the content is suitably ensured.

  Next, with reference to FIG. 9, the time transition of the data amount in the streaming reproduction control will be described. FIG. 9 is a diagram exemplifying a one-hour transition of each data amount in the streaming reproduction control. In the figure, the same reference numerals are given to the same portions as those in the above-described drawings, and the description thereof will be omitted as appropriate.

  In FIG. 9, the vertical axis represents the data amount (byte), and the horizontal axis represents time.

  Assume that the initial fragment processing is started at time T0. At time T1, the received data amount reaches the reproduction start data amount M0, and content reproduction is started. Even after the start of content reproduction, the acquisition of the fragment N0 using the entire reception band B is continued. When the memory cache amount (see the hatched area in the figure) reaches the storage capacity M at time T2, the acquisition of the fragment N0 is also completed. (Formula (2) is defined so that such a relationship is satisfied).

  At the time T3 when the total amount of acquired fragments reaches the content size N, when the writing process of the fragment N1 into the volatile storage area of the high-speed memory 170 and the writing process of the fragment N2 into the nonvolatile storage area of the HDD 160 are completed, the time T4 The memory cache amount of the high-speed memory 170 gradually decreases at the playback speed P. At time T4 when the memory cache amount becomes zero, the reproduction buffer is switched to the HDD 160, and thereafter, content reproduction by the HDD cache is continued until the reproduction data amount reaches the content size N at time T5.

  Since the capacity of the HDD 160 is sufficiently large with respect to the content size N, it is not necessary to erase the read (reproduced) HDD cache even if the HDD cache is read. Will not decrease. In addition, since it is not necessary to erase the HDD cache that has been reproduced in this way, a situation in which read processing and write processing to the HDD 160 occur simultaneously during reproduction of content based on the HDD cache is avoided.

As is clear from FIG. 9, there is a time delay corresponding to T5-T4 between time T4 when the writing process of the fragment N2 is completed in the HDD 160 and time T5 when the reading process of the HDD cache is started. Both are never executed in duplicate.
<Second embodiment>
Next, streaming playback control according to the second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a flowchart of the streaming playback control. In the figure, the same reference numerals are given to the same portions as those in FIG. 3, and the description thereof will be omitted as appropriate. Note that the hardware configuration according to the second embodiment is equivalent to that of the first embodiment.

  In FIG. 10, after executing the preparation process, the control unit 110 executes an initial fragment process (step S210), executes a parallel fragment process (step S310), and executes a post-reception process (step S410).

  Subsequently, the initial fragment processing according to the second embodiment will be described with reference to FIG. FIG. 11 is a flowchart of the initial fragment processing. In the figure, the same parts as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  In FIG. 11, when the reproduction of the memory cache is executed (step S205), the control unit 110 determines whether or not there is a content storage request (step S211). The content saving request may correspond to, for example, a command given by the user of the content reproduction device 100 via an appropriate input device, or is automatically generated by the control unit 110 according to a preset condition or the like. It may be a thing.

  When there is no content storage request (step S211: NO), the control unit 100 shifts the processing to step S206 as in the first embodiment. On the other hand, when there is a content storage request (step S211: YES), the control unit 110 duplicates and writes the reproduced memory cache in the nonvolatile storage area of the HDD 160 (step S212).

  Next, parallel fragment processing according to the second embodiment will be described with reference to FIG. FIG. 12 is a flowchart of parallel fragment processing. In the figure, the same reference numerals are given to the same portions as those in FIG. 6, and the description thereof is omitted as appropriate.

  In FIG. 12, when the reproduction of the memory cache is executed (step S306), the control unit 110 determines whether or not there is a content storage request (step S311). The content saving request may correspond to, for example, a command given by the user of the content reproduction device 100 via an appropriate input device, or is automatically generated by the control unit 110 according to a preset condition or the like. It may be a thing.

  If there is no content storage request (step S311: NO), the control unit 100 shifts the processing to step S307 as in the first embodiment. On the other hand, when there is a content storage request (step S311: YES), the control unit 110 duplicates and writes the reproduced memory cache in the nonvolatile storage area of the HDD 160 (step S312).

  Next, post-reception processing according to the second embodiment will be described with reference to FIG. FIG. 13 is a flowchart of post-reception processing. In the figure, the same reference numerals are given to the same portions as those in FIG. 7, and the description thereof will be omitted as appropriate.

  In FIG. 13, when the reproduction of the HDD cache is completed (step S405: YES), the control unit 110 determines whether or not there is a content erasure request (step S411). The content erasure request may correspond to, for example, a command given by the user of the content reproduction device 100 via an appropriate input device, or is automatically generated by the control unit 110 according to a preset condition or the like. It may be a thing.

  When there is a content deletion request (step S411: YES), the control unit 110 deletes the HDD cache (in this case, the content data itself including the fragments N0, N1, and N2) from the HDD 160 (step S412). When there is no content erasure request (step S411: NO), the control unit 100 ends the post-reception process.

  Next, the effect of streaming playback control according to the second embodiment will be described with reference to FIG. FIG. 14 is a conceptual diagram of the flow of each fragment in the streaming playback control according to the second embodiment. In FIG. 14, parts that are the same as those in FIG. 8 are given the same reference numerals, and descriptions thereof are omitted as appropriate.

As apparent from FIG. 14, according to the streaming playback control according to the second embodiment, the fragments N0 and N1 (only the high-speed memory 170 in FIG. 14 are stored in the high-speed memory 170 in the first embodiment). Are depicted as if all the fragments N0 and N1 are stored, but the actual amount of data stored is only the data corresponding to the storage capacity M). Therefore, once downloaded, the contents need not be downloaded again, which is efficient.
<Third embodiment>
Next, a third embodiment of the present invention will be described.

<Configuration of Example>
First, the configuration of the streaming system 2 according to the third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a schematic configuration diagram conceptually showing the configuration of the streaming system 2. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  In FIG. 15, unlike the first embodiment, the streaming system 2 includes a plurality of data providing nodes 300A, 300B, 300C, and 300D, and content data can be downloaded from the plurality of data providing nodes. .

<Operation of Example>
Next, streaming playback control according to the second embodiment of the present invention will be described with reference to FIG. FIG. 16 is a flowchart of streaming playback control. In the figure, the same reference numerals are given to the same parts as those in FIG. 10, and the description thereof will be omitted as appropriate.

  In FIG. 16, the control unit 110 executes a preparation process (step S120), executes an initial fragment process (step S220), and executes a parallel fragment process (step S320). Thereafter, post-reception processing is executed as in the second embodiment (step S410).

  Next, details of the preparation process according to the third embodiment will be described with reference to FIG. FIG. 17 is a flowchart of the preparation process. In the figure, the same reference numerals are given to the same portions as those in FIG. 4, and the description thereof will be omitted as appropriate.

  In FIG. 17, steps S101, S102 and S104 are executed for each data providing node.

  When the fragment size is determined in step S105, the control unit 110 assigns data providing nodes to the determined fragments N0, N1, and N2, respectively (step S121). At this time, the control unit 110 assigns an appropriate data providing node to each fragment according to the following rules (A), (B), and (C).

(A) Determination of a node that provides a fragment N0 A node that provides a fragment N0 is determined in the following manners (a) to (d).

(A) Among the data providing nodes that hold the content, priorities are assigned in descending order of the transmission bandwidth C. (a) From the data providing node with the high priority set in (a), the transmission bandwidth C Select nodes until the sum total exceeds the reception bandwidth B of the content playback apparatus 100. (c) For each content providing node selected in (a), the transmission bandwidth C, RTT, and hardware performance Assign priorities Allocate fragment data from the head of fragment N0 in the order of the transmission bandwidth C in order from the node with the highest priority assigned in (d) and (c). When this rule is followed, the transmission bandwidth C If there is a data providing node whose size is larger than the reception bandwidth B of the content reproduction device 100, the fragment N0 is obtained from the single data providing node as in the first embodiment. Is done. On the other hand, when the transmission bandwidth C is less than the reception bandwidth B, a plurality of data providing nodes are selected so that the utilization efficiency of the reception bandwidth B is maximized (100%). If the data providing node is single as in the first embodiment, the utilization efficiency of the reception bandwidth B does not reach the theoretical maximum value in this case (however, the entire transmission bandwidth is used). In this embodiment, the fragment N0 including the reproduction start data is obtained by acquiring the fragment N0 from the plurality of nodes. Can be acquired as quickly as possible, and the time required to start playback of the content can be shortened.

(B) Determination of a node that provides a fragment N1 A node that provides a fragment N1 is determined in the following manners (a) to (d).

(A) A node having a transmission bandwidth equal to or higher than the content reproduction speed P is selected from the data providing nodes holding the content, and a node having the smallest RTT is further selected from the nodes. If there is no data providing node having a transmission band equal to or higher than the reproduction speed P, priority is given in the order of the transmission bandwidth C and RTT. Select the data providing node until the sum of the bandwidths C is equal to or higher than the reproduction speed P. (d) For the data providing node selected in (c), send fragment data from the beginning of the fragment N1 at the ratio of the transmission bandwidth C. The fragment N1 to be allocated is a fragment that is written to the volatile storage area of the high-speed memory 170 at a writing speed synchronized with the reproduction speed P. If the data providing node is a node having a transmission bandwidth equal to or higher than the reproduction speed P, there is no problem. However, if there are a plurality of data providing nodes, even if there is no data providing node having a transmission bandwidth equal to or higher than the reproduction speed P, data is provided until a transmission bandwidth equal to or higher than the reproduction speed P is ensured in this way. Since the number of nodes can be increased, it is not necessary to reduce the reproduction quality of the content. For example, if the data providing node is a single node having a transmission bandwidth less than the playback speed P, the memory cache of the high-speed memory 170 decreases with the playback of the content, so the playback is stopped at an arbitrary timing. And there is nothing but to increase the amount of memory cache.

(C) Determination of node providing fragment N2 The node providing fragment N2 is determined as follows (a) to (c).

(A) Giving priority to a plurality of content providing nodes in the order of transmission bandwidth C, hardware performance, and RTT (a) Sending in order from the data providing node with the highest priority given in (a) Select a data providing node until the sum of the bandwidth C exceeds the remaining bandwidth of the receiving bandwidth B. (c) For the data providing node selected in (a), the ratio of the fragment N2 in the ratio of the transmission bandwidth When allocating the fragment data from the beginning, when the node allocation is completed, the control unit 110 secures appropriate buffer areas in the HDD 160 and the high-speed memory 170 (step S106), and ends the preparation process.

  Subsequently, the initial fragment processing according to the third embodiment will be described with reference to FIG. FIG. 18 is a flowchart of the initial fragment processing. In the figure, the same parts as those in FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  In FIG. 18, when a fragment N0 request is made to one or a plurality of data providing nodes allocated by the preparation process (step S201), the control unit 110 causes a failure (communication line disconnection or stability It is determined whether or not a decrease or a decrease in bandwidth occurs (step S221). If no network failure has occurred (step S221: NO), the process proceeds to step S202.

  On the other hand, when a network failure has occurred (step S221: YES), the control unit 110 reassigns a data providing node that requests the fragment N0 (step S222). After reassigning the data providing node, the control unit 110 requests the fragment N0 from the reassigned data providing node (step S223). The subsequent processing is the same as in the second embodiment.

  Here, the reassignment of the data providing node in step S222 is performed by executing the process (A) again. That is, an appropriate data providing node is selected from the data providing nodes excluding the data providing node in which the network failure has occurred, and transfer is requested from fragment data after the fragment data already stored as a cache in the high-speed memory 170. The At this time, the reproduction of the memory cache stored in the high-speed memory 170 at that time may be started.

  Next, parallel fragment processing according to the third embodiment will be described with reference to FIG. FIG. 19 is a flowchart of parallel fragment processing. In the figure, the same reference numerals are given to the same portions as those in FIG. 12, and the description thereof is omitted as appropriate.

  In FIG. 19, when a request for fragments N1 and N2 is made to one or a plurality of data providing nodes allocated by the preparation process (step S301), the control unit 110 causes a failure (communication line disconnection or stabilization) in the network 200. It is determined whether or not there has been a decrease in performance or a decrease in bandwidth (step S321). If no network failure has occurred (step S321: NO), the process proceeds to step S302.

  On the other hand, if a network failure has occurred (step S321: YES), the control unit 110 reassigns data providing nodes that request fragments N1 and N2 (step S322). After reassigning the data providing nodes, the control unit 110 requests fragments N1 and N2 from the reassigned data providing nodes (step S323). The subsequent processing is the same as in the third embodiment.

  Here, the reassignment of the data providing node in step S322 differs between the fragment N1 and the fragment N2.

  When a network failure occurs in the node that provides the fragment N1, the control unit 110 continues the reproduction of the memory cache in order to maintain the smooth reproduction of the content. On the other hand, the data providing node having the largest transmission band is selected from the data providing nodes, and the fragment data after the last fragment data stored in the high-speed memory 170 is requested from the fragment N1. At this time, the acquisition of the fragment N2 is suspended until the memory cache amount of the high-speed memory 170 is restored to the storage capacity M. In other words, using all the reception bandwidth B, the memory cache of the high-speed memory 170 can be restored at the fastest speed.

  When the memory cache amount of the high-speed memory 170 is restored to the storage capacity M, the control unit 110 selects one or a plurality of data providing nodes according to the process (B) and resumes acquisition of the fragment N1 synchronized with the playback speed P. To do. At the same time, the acquisition of the fragment N2 is resumed.

  On the other hand, when a network failure occurs in the node that provides the fragment N2, the control unit 110 selects one or more nodes having a lower priority in accordance with the process (C), and the node in which the network failure has occurred. Among the pieces of fragment data assigned to, the data after the data already stored in the HDD 160 as the HDD cache is requested.

  Next, the effect of the streaming playback control according to the third embodiment will be described with reference to FIG. FIG. 20 is a conceptual diagram of the flow of each fragment in the streaming playback control according to the third embodiment. In FIG. 20, the same parts as those in FIG. 14 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  As is apparent from FIG. 20, according to the streaming playback control according to the third embodiment, fragments N0, N1, and N2 are transferred from a plurality of data providing nodes (300A and 300B in the figure). Therefore, as described above, even when the transmission bandwidth of each data transfer node is less than the reception bandwidth B of the content reproduction device 100, it is possible to maintain the utilization efficiency of the reception bandwidth B to the maximum. The download time for the entire content data can be shortened.

  In addition, even when communication with one or a plurality of content providing nodes is disconnected, other data providing nodes are used as alternative nodes, unlike when data is transferred with a single data providing node. Can be used. Therefore, interruption of content reproduction is prevented, and more robust content reproduction is ensured. Further, for example, even when the transmission bandwidth of each data providing node accommodated in the network 200 is lower than the content playback speed, such as high-quality video content, the content playback apparatus 100 side exceeds the playback speed. The content data can be acquired at a speed of 5 to reduce the restrictions on the content reproduction.

In any case, there is no duplication of the writing process and the reading process with respect to the nonvolatile storage area of the HDD 160, and it is needless to say that a practical advantage peculiar to the present invention is guaranteed.
<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described.

  When the protocol that defines the transmission mode of the fragment is a protocol such as UDP (User Datagram Protocol) that is unlikely to generate packet loss, it is desirable to take measures against such packet loss in advance.

  Therefore, in the fourth embodiment, in the third embodiment, fragments N0, N1, and N2 are obtained from a plurality of data providing nodes, respectively. In this case, since it is equivalent to doubling the fragment size, the time required to start playing content and the time required to download content data are longer than in the third embodiment, but the packet loss is reduced. Therefore, the frequency of packet retransmission requests can be reduced, which is effective for smooth playback of content.

Further, as an application, acquisition from a plurality of nodes may be performed only when a packet loss leads to a large error such as an MPEG1 picture or a GOP header.
<Fifth embodiment>
In the various embodiments described above, the data amounts of the fragment N1 and the fragment N2 are determined in advance at the stage of execution of the preparation process based on the state of the network at that time. However, since the network environment can change over time, there is no guarantee that the fragments N1 and N2 will maintain optimal values during the content data download period. Therefore, in the fifth embodiment, a description will be given of streaming playback control that is robust to such changes in the network environment.

  In the fifth embodiment, when determining the fragment size, only the fragment N0 is first determined.

  When the acquisition of the fragment N0 is completed, the control unit 110 sequentially acquires data fragments sequentially from the position that continues from the fragment N0 at a speed synchronized with the playback speed P, and on the other hand, using the remaining reception bandwidth. Fragment data is acquired retroactively from the last position of the content data. As described above, when fragment data is acquired from both ends of the remaining content data excluding the fragment N0, one piece of fragment data of the remaining content data is acquired in duplicate (detection of this before duplication). You may).

  The fragment data from the fragment data corresponding to this overlapping data position to the end is fragment N2, and the data on the head side of the fragment data corresponding to this overlapping position is fragment N1. In this way, if the fragments N1 and N2 are set as variable values, the data amounts of the fragments N1 and N2 automatically change according to changes in the network state (for example, changes in bandwidth). Rather than prescribing these data amounts in advance, it is more robust against changes in the network status.

  Also in this case, the memory cache is played back at the playback speed P, and the timing at which the fragment data at the duplicate data position is read out is greater than the timing at which the fragment data to be acquired overlaps at the playback speed. After the time multiplied by P. That is, also in this case, there is no overlap between the writing process and the reading process in the HDD 160, and smooth content reproduction is promised.

  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 is applicable to an apparatus that performs streaming playback of content.

  DESCRIPTION OF SYMBOLS 1 ... Streaming system, 2 ... Streaming system, 100 ... Playback apparatus, 200 ... Network, 300, 300A, 300B, 300C, 300D ... Data provision node, 110 ... Control part, 120 ... Protocol generation part, 130 ... Transmission part, 140 ... Receiving unit 150 ... Received data analyzing unit 160 ... HDD 170 ... High speed memory.

Claims (16)

A first storage device having a volatile storage area, which is stored in a network together with at least one data providing node capable of transferring a fragment of the content data requested to be transferred, the content data relating to the content being transferred, and a nonvolatile storage A streaming playback device capable of streaming playback of the content, comprising a second storage device having a region, a writing speed slower than that of the first storage device, and a large storage capacity;
Request means for requesting the data providing node to transfer, as the fragment, a fragment Na including reproduction start data capable of starting streaming reproduction of the content and a fragment Nb including at least a data portion continuous with the fragment Na. When,
Obtaining means for respectively obtaining the fragments Na and Nb transferred from the data providing node via the network;
First storage control means for controlling the first storage device so that the acquired fragment Na is accumulated in the volatile storage area;
Second storage control means for controlling the second storage device so that the acquired fragment Nb is accumulated in the nonvolatile storage area;
At the time when the reproduction start data is accumulated, the accumulated fragment Na is sequentially read to start streaming reproduction of the content, and at the time when streaming reproduction of the content corresponding to the accumulated fragment Na is completed, Reproduction means for sequentially reading out the accumulated fragment Nb from a portion continuous with the accumulated fragment Na and continuing streaming reproduction of the content;
First specifying means for specifying a communication state with the data providing node via the network;
Second specifying means for specifying the states of the first and second storage devices;
Third specifying means for specifying the state of the content;
Based on the specified communication state, the state of the first and second storage devices, and the state of the content, the storage of the fragment Nb ends before or at the same time as the end of reading of the fragment Na. And determining means for determining the fragments Na and Nb and their transfer rates,
The streaming reproduction apparatus, wherein the request unit requests the data providing node to transfer the determined fragments Na and Nb at the determined transfer rate. A plurality of the data providing nodes are accommodated in the network,
Providing a plurality of data to be requested to transfer the determined fragment Na from among the plurality of data providing nodes based on the specified communication state, the state of the first and second storage devices, and the state of the content First assigning means for selecting a node and allocating a part of the determined fragment Na to be transferred to each of a plurality of data providing nodes to be requested to transfer the selected fragment Na. When,
Providing a plurality of data to be requested to transfer the determined fragment Nb from among the plurality of data providing nodes based on the specified communication state, the state of the first and second storage devices, and the state of the content Second assigning means for selecting a node and allocating a part of the determined fragment Nb to be transferred to each of a plurality of data providing nodes to be requested to transfer the selected fragment Nb. And further comprising
The request means requests a part of the allocated fragment Na to each of a plurality of data providing nodes that should request the transfer of the selected fragment Na, and transfers the selected fragment Nb. The streaming playback device according to claim 1, wherein a part of the allocated fragment Nb is requested to each of a plurality of data providing nodes that are to request the data. The first assigning means is configured to provide the plurality of data providing nodes when a network failure occurs with at least one data providing node among the plurality of data providing nodes that should request transfer of the selected fragment Na. And reselecting at least one data providing node to be replaced with at least one data providing node corresponding to the network failure that has occurred, and newly including the reselected data providing node. Reassigning, to each of a plurality of data providing nodes that should request the transfer of a part of the determined fragment Na, which is to be transferred, a part of the determined fragment Na that has not been transferred,
The second assigning unit is configured to provide the plurality of data providing nodes when a network failure occurs with at least one data providing node among the plurality of data providing nodes that should request transfer of the selected fragment Nb. And reselecting at least one data providing node to be replaced with at least one data providing node corresponding to the network failure that has occurred, and newly including the reselected data providing node. A part of the determined fragment Nb that has not yet been transferred is reassigned to each of a plurality of data providing nodes that should request the transfer of Item 3. The streaming playback device according to Item 2. The streaming reproduction apparatus according to any one of claims 1 to 3, wherein the fragment is included in at least one of the fragment Na and the fragment Nb. The transfer speed of the fragment Na is the playback speed of the content, and the transfer speed of the fragment Nb is a transfer corresponding to the remaining reception band excluding the band corresponding to the playback speed among the reception bands of the streaming playback device. The streaming playback device according to claim 1, wherein the streaming playback device is a speed. The fragment Na is composed of a fragment N0 including the reproduction start data and a fragment N1 excluding the fragment N0.
The streaming playback device according to any one of claims 1 to 5, wherein the request unit waits for a request for the fragment Nb until the acquisition of the fragment N0 is completed. The streaming playback device according to claim 6, wherein a transfer rate of the fragment N0 is a maximum transfer rate defined between the data providing nodes. The requesting unit requests the fragment Na so that the fragment Na is sequentially acquired from the beginning of the content data, and requests the fragment Nb so that the fragment Nb is sequentially acquired from the last fragment. And
The streaming playback device according to any one of claims 1 to 7, wherein the acquisition unit acquires the fragment Na and the fragment Nb so that the fragment Na and the fragment Nb do not overlap. The streaming playback device according to any one of claims 1 to 8, wherein the first specifying unit specifies a reception bandwidth of the streaming playback device and a transmission bandwidth of the data providing node. The streaming playback device according to any one of claims 1 to 9, wherein the second specifying unit specifies a remaining capacity and a load state of the first and second storage devices. The streaming playback apparatus according to any one of claims 1 to 10, wherein the third specifying unit specifies a data size and a playback speed of the content. The said 2nd memory | storage control means controls the said 2nd memory | storage device so that the said sequentially read fragment | piece Na may be accumulate | stored in a said 2nd memory | storage device. The streaming playback device according to item. The streaming playback device according to any one of claims 1 to 12, wherein the second control unit erases fragments stored in the nonvolatile storage area in response to a predetermined erasure request. A first storage device having a volatile storage area, which is stored in a network together with at least one data providing node capable of transferring a fragment of the content data requested to be transferred, the content data relating to the content being transferred, and a nonvolatile storage A streaming playback method in a streaming playback device capable of streaming playback of the content, comprising: a second storage device having a region, a writing speed slower than the first storage device, and a large storage capacity ,
A requesting step for requesting the data providing node to transfer, as the fragment, a fragment Na including reproduction start data capable of starting streaming reproduction of the content and a fragment Nb including at least a data portion continuous with the fragment Na. When,
Obtaining each of the fragments Na and Nb transferred from the data providing node via the network;
A first storage control step of controlling the first storage device so that the acquired fragment Na is accumulated in the volatile storage area;
A second storage control step of controlling the second storage device so that the acquired fragment Nb is accumulated in the nonvolatile storage area;
At the time when the reproduction start data is accumulated, the accumulated fragment Na is sequentially read to start streaming reproduction of the content, and at the time when streaming reproduction of the content corresponding to the accumulated fragment Na is completed, A reproduction step of sequentially reading out the accumulated fragment Nb from a portion continuous with the accumulated fragment Na and continuing streaming reproduction of the content;
A first specifying step of specifying a communication state with the data providing node via the network;
A second specifying step of specifying states of the first and second storage devices;
A third identification step for identifying the state of the content;
Based on the specified communication state, the state of the first and second storage devices, and the state of the content, the storage of the fragment Nb ends before or at the same time as the end of reading of the fragment Na. Determining the fragments Na and Nb and their transfer rates; and
The requesting step requests the data providing node to transfer the determined fragments Na and Nb at the determined transfer rate.   A computer program for causing a computer system to function as the streaming playback device according to any one of claims 1 to 13.   A recording medium recording the computer program according to claim 15.

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