JP2007274244A - Content data distribution system, content data distribution method, terminal device, and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly deal with channel switching by a user of a terminal device in a content distribution system for performing streaming distribution for a plurality of channels. <P>SOLUTION: The content distribution system has one or more content distribution devices, with each distributing content data in streaming by using a plurality of channels; the plurality of terminal devices for receiving and reproducing the content data; and a connection management device for managing connection so that the plurality of terminal devices are connected logically in multiple layers of a hierarchial structure, while the content distribution device is used as a top for each channel. The terminal devices in the content distribution system each set a ring buffer region for receiving the content data of each of the channels into a storage, and the buffer capacity of the ring buffer region is allocated, on the basis of the reproduction status of the channels, thereby improving the utilization efficiency of the ring buffer region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to content data distribution technology. Specifically, a plurality of terminal devices are logically connected in a multilayered manner with a content distribution device at the top for each channel, and content data streamed from the content distribution device is sequentially layered for each channel by the relay function of the terminal device The present invention relates to a content data distribution system, a content data distribution method, a terminal device, and a program thereof, which are relayed downstream from each other and allow content data to be reproduced by a plurality of terminal devices.

  In recent years, content distribution services for streaming distribution of content data (hereinafter referred to as “content data”) such as music, movies, and talk programs have started to be started via networks such as the Internet. Here, the streaming distribution is a distribution method for distributing content data in a streaming format that can be stream-received by a client terminal device (hereinafter simply referred to as “terminal device”). You can play while receiving. Further, as a streaming distribution form, there are a broadcast format in which a distribution time of content data is determined and an on-demand format in which streaming distribution is performed to individual terminal devices in response to a request from the terminal device.

  Conventionally, a content distribution service in a broadcast format has been mainly used to directly distribute content from a single content distribution device to a plurality of terminal devices.

  However, with the enhancement of content distribution services and the increase in the number of terminal devices connected to the network, the number of terminal devices that request content data distribution from the content distribution devices increases, and the load on the distribution devices increases. The concentration of traffic in the network has become a serious influence.

  In order to avoid such an increase in load and traffic on the content distribution device, a technology for distributing the load by placing a plurality of servers such as mirror servers and caches in the network in addition to the original distribution server has been put into practical use. However, a plurality of servers for distributing contents are required, and the cost of facilities increases.

  Therefore, a content data distribution method has been proposed that can reduce load and traffic concentration without increasing the number of content distribution devices by relaying content data between terminal devices, that is, using a P2P communication mode. In this content data distribution method, a plurality of terminal devices are logically connected in multiple layers in a tree structure with the content distribution device as a vertex, and content data is sequentially distributed from the content distribution device to downstream terminal devices. That is, the content data distributed from the content distribution device is distributed to the terminal device located in the highest layer (first layer), and the terminal device located in the highest layer receives the content data distributed from the content distribution device. The relay is performed until the terminal device located in the second hierarchy is relayed and the content data is relayed to the terminal device located in the lowest layer (see, for example, Patent Documents 1 and 2).

  In such a content data distribution system, a connection management device for logically connecting a plurality of terminal devices in a tree structure is arranged on the network. The connection management device has a function of managing the connection state of the terminal devices in the hierarchical structure of the content distribution system, and forms a hierarchical structure when receiving a participation request from a terminal device not participating in the hierarchical structure. Of the plurality of terminal devices, the terminal device that made the participation request is notified of which terminal device should be connected. The terminal device that has received this notification can participate in the content distribution system by making a connection request to the connection destination candidate that has been introduced by the connection management device. It is possible to reproduce while receiving from the upstream terminal device that is logically connected.

  By the way, in the content data distribution system in the broadcast format, when content data is streamed and distributed by a plurality of channels, a tree-type hierarchical structure having the content distribution device as a vertex is configured for each channel.

Therefore, when the user of the terminal device performs an operation to view a channel different from the channel being viewed, the terminal device participates in a tree-type hierarchical structure different from the tree-type hierarchical structure corresponding to the channel being viewed. It will be.
JP 2004-341576 A JP 2004-246790 A

  In the terminal device of the content distribution system as described above, a ring buffer area for temporarily storing content data is provided so that a supplementary process for packet loss and trick play for received content data can be performed. Is set.

  The larger this ring buffer area is, the more the accuracy of complementary processing for packet loss and the trick play operability can be improved.

  However, since the viewing situation by the user of the terminal device varies depending on each channel, setting the buffer capacity of the ring buffer area to be constant is not necessarily required in the complementary processing or trick play for packet loss related to the channel to be viewed. The buffer capacity may be reached, and the storage area of the terminal device cannot be used effectively.

  In particular, in devices such as set-top boxes and digital home appliances with a small storage area, it is desirable to secure as much storage capacity as possible for other processing. When such a device is used as a terminal device, the buffer capacity of the ring buffer area is reduced. It is desirable to set appropriately.

  Accordingly, in order to solve such a problem, the invention according to claim 1 is characterized in that one or more content distribution apparatuses that perform streaming distribution of content data respectively on a plurality of channels and a plurality of terminal apparatuses that receive and reproduce the content data. And a connection management device that manages a plurality of terminal devices so as to be logically connected in a hierarchical structure with the content distribution device at the top for each channel, and the content distributed by streaming from the content distribution device In the content data distribution system in which data is sequentially relayed downstream of the hierarchical structure by the relay function of the terminal device for each channel, and the content data can be reproduced by the plurality of terminal devices, the content distribution device includes: Equipped with delivery means to deliver content data The connection management device receives connection state information storage means for storing connection state information of the terminal device constituting the hierarchical structure for each channel, and when the connection destination introduction request is received from the terminal device, the connection state The connection destination candidate selection means for selecting a connection destination candidate from the connection state information stored in the information storage means, and the connection destination candidate selected by the connection destination candidate selection means, the terminal that has transmitted the connection destination introduction request Notification means for notifying a device, wherein the terminal device is a storage means, a channel selection means for selecting the channel, and the connection destination introduction request relating to the channel selected by the channel selection means. A connection means for transmitting to the management device and then connecting to the connection destination candidate notified from the connection management device; and the channel Ring buffer setting means for setting a ring buffer area in which content data of a channel selected by the selection means is received from the candidate connection destination and temporarily stored in the storage means for each channel selected by the channel selection means And a reproducing means for retrieving the content data of the latest channel selected by the channel selecting means from the ring buffer area corresponding to the channel and reproducing the content data for each channel by the reproducing means. Content data reproduction status detecting means, relay request receiving means for receiving the content data relay request from the other terminal device, and transfer for transferring the content data stored in the ring buffer area to the other terminal device Means, and The ring buffer setting means of the terminal device sets the ring buffer area having a buffer capacity corresponding to the reproduction status of the content data of the channel selected by the channel selection means in the storage means.

  Further, the invention according to claim 2 is the connection according to claim 1, wherein the connection means of the terminal device includes a buffer capacity of a ring buffer area corresponding to the channel selected by the channel selection means. A connection introduction request is transmitted as the connection destination introduction request, and the connection management device includes a buffer capacity reception unit that receives a buffer capacity of a ring buffer area of the terminal device and stores the buffer capacity in the connection state information storage unit, When the connection destination candidate selection means of the connection management device receives a connection destination introduction request including the buffer capacity of the ring buffer area from the terminal device, in the hierarchical structure of the channel corresponding to the connection destination introduction request, the hierarchical structure The buffer capacity of the ring buffer area of the terminal device constituting the terminal device is from upstream to downstream of the hierarchical structure. As smaller, the connection destination candidate for the connection destination introduction request, and selects from the connection state information stored in the connection state information storage means.

  The invention according to claim 3 is characterized in that one or more content distribution apparatuses for streaming distribution of content data through a plurality of channels, a plurality of terminal apparatuses for receiving and reproducing the content data, and the content for each channel A connection management device that manages a plurality of terminal devices so as to be logically connected in multiple layers with a distribution device at the top, and the content data streamed from the content distribution device is the terminal for each channel In a content data distribution method of a content data distribution system that is sequentially relayed downstream of the hierarchical structure by a relay function of the device and is capable of reproducing the content data by the plurality of terminal devices, the content distribution device transmits the content data Having a step of delivering, The connection management device stores the connection status information of the terminal device constituting the hierarchical structure for each channel, and receives the connection destination introduction request from the terminal device, from the stored connection status information. Selecting a connection destination candidate; and notifying the selected connection destination candidate to the terminal device that has transmitted the connection destination introduction request, wherein the terminal device selects the channel. A step of detecting, a step of transmitting the connection destination introduction request relating to the selected channel to the connection management device, a step of connecting to the connection destination candidate notified from the connection management device, and the channel selection means A ring buffer area for temporarily storing the content data of the selected channel received from the connection destination candidate, Setting in the storage means for each channel selected by the channel selection means, retrieving the content data of the selected latest channel from the ring buffer area corresponding to the channel, and reproducing the channel data; Detecting a reproduction status of each content data; receiving a relay request for the content data from another terminal device; and transferring the content data stored in the ring buffer area to the other terminal device And a step of setting, in the storage means, the ring buffer area having a buffer capacity corresponding to the content data reproduction status of the selected channel.

  According to a fourth aspect of the present invention, there is provided one or more content distribution apparatuses for streaming distribution of content data through a plurality of channels, a plurality of terminal apparatuses for receiving and reproducing the content data, and the content for each channel. A connection management device that manages a plurality of terminal devices so as to be logically connected in multiple layers with a distribution device at the top, and the content data streamed from the content distribution device is the terminal for each channel In the terminal device in the content data distribution system that is sequentially relayed downstream of the hierarchical structure by the relay function of the device, and the content data can be reproduced by the plurality of terminal devices, for selecting the storage means and the channel Channel selection means and the channel A connection means for transmitting the connection destination introduction request regarding the channel selected by the selection means to the connection management apparatus, and then connecting to the connection destination candidate notified from the connection management apparatus; and the channel selection means A ring buffer setting means for setting a ring buffer area for receiving and temporarily storing content data of a channel from the connection destination candidate in the storage means for each channel selected by the channel selection means; and the channel selection A reproduction means for retrieving the content data of the latest channel selected by the means from the ring buffer area corresponding to the channel, and a content data reproduction status for detecting the reproduction status of the content data for each channel by the reproduction means Detection means; Relay request receiving means for receiving the relay request for the content data from the terminal device, and transfer means for transferring the content data stored in the ring buffer area to the other terminal device, and the ring buffer setting The means sets the ring buffer area having a buffer capacity corresponding to the reproduction status of the content data of the channel selected by the channel selection means in the storage means.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the condition relating to the reproduction state of the content data is the number of reproductions of the content data in each channel.

  According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the condition relating to the reproduction state of the content data is a reproduction time of the content data in each channel.

  The invention according to claim 7 is the invention according to any one of claims 4 to 6, wherein the ring buffer setting means responds to the reproduction status of the content data for each channel every predetermined period. The ring buffer area is updated so that the buffer capacity becomes the same.

  The invention according to claim 8 is the invention according to any one of claims 4 to 7, wherein the ring buffer setting means is connected to the connection destination candidate of the channel selected by the channel selection means. When it is determined that the ring buffer area corresponding to the selected channel does not exist in the storage means and the number of the ring buffer areas set in the storage means has reached a predetermined number when connected by the means, One of the plurality of ring buffer areas is deleted from the storage means, and a ring buffer area corresponding to the selected channel is set in the storage means.

  The invention according to claim 9 is the invention according to claim 8, wherein the ring buffer setting means has a period of time that is not reproduced by the reproduction means in the ring buffer area set in the storage means. The longest ring buffer area is deleted from the storage means, and a ring buffer area corresponding to the selected channel is set in the storage means.

  Further, the invention according to claim 10 is the buffer capacity notifying means for notifying the connection management apparatus of the buffer capacity of the ring buffer area every predetermined period in the invention according to any one of claims 4 to 9. It is provided with.

  The invention according to claim 11 is the invention according to any one of claims 4 to 9, wherein the ring buffer area is set by the ring buffer setting means, or the ring buffer setting means When the buffer capacity of the ring buffer area is changed, buffer capacity notifying means is provided for notifying the connection management apparatus of the buffer capacity of the ring buffer area.

  The invention according to claim 12 is the invention according to any one of claims 4 to 11, wherein when the power supply of the terminal device is detected to be cut off, the plurality of sets set in the storage means The buffer capacity of the ring buffer area is stored in the nonvolatile storage device, and when the power of the terminal device is supplied again, the plurality of ring buffer areas are stored on the basis of the buffer capacity stored in the nonvolatile storage device. A backup processing means for resetting the storage means is provided.

  The invention according to claim 13 is the buffer capacity of the ring buffer area of the terminal device upstream of the terminal device in the hierarchical structure according to any one of claims 4 to 12. Upstream buffer capacity acquisition means for acquiring the buffer capacity of the ring buffer area possessed by the terminal apparatus, the comparison means for comparing the buffer capacity of the ring buffer area possessed by the upstream terminal apparatus, and the comparison means If the buffer capacity of the ring buffer area of the terminal device is larger than the buffer capacity of the ring buffer area of the upstream terminal device as a result of the comparison by the above, the hierarchical structure is higher than that of the upstream terminal device. And reconnection means for reconnection upstream.

  Further, in the invention described in claim 14, in the invention described in claim 13, the upstream buffer capacity acquisition means determines the buffer capacity of the ring buffer area of the upstream terminal device for each predetermined trigger. A buffer capacity of the ring buffer area of the upstream terminal device is acquired by inquiring of the device.

  Further, in the invention described in claim 15, in the invention described in claim 13, the upstream buffer capacity acquisition means obtains the buffer capacity of the ring buffer area of the upstream terminal device at the predetermined upstream timing. A buffer capacity of the ring buffer area of the upstream terminal device is acquired by making an inquiry to the terminal device.

  The invention according to claim 16 is the invention according to any one of claims 4 to 15, wherein the buffer capacity of the ring buffer area of the terminal device downstream of the terminal device in the hierarchical structure is increased. By the downstream buffer capacity acquisition means to be acquired, the comparison means for comparing the buffer capacity of the ring buffer area of the terminal apparatus with the buffer capacity of the ring buffer area of the downstream terminal apparatus, and the comparison means As a result of comparison, when the buffer capacity of the ring buffer area included in the terminal apparatus is smaller than the buffer capacity of the ring buffer area included in the downstream terminal apparatus, it is less than the downstream terminal apparatus or the downstream terminal apparatus. Reconnecting means for reconnecting downstream in the hierarchical structure.

  The invention according to claim 17 is the invention according to claim 16, wherein the downstream buffer capacity acquisition means connects the buffer capacity of the ring buffer area of the downstream terminal device at a predetermined timing. The buffer capacity of the downstream terminal device is acquired by making an inquiry to the management device.

  Further, in the invention described in claim 18, in the invention described in claim 16, the downstream buffer capacity acquisition means sets the buffer capacity of the ring buffer area of the downstream terminal device to the downstream at a predetermined timing. The buffer capacity of the ring buffer area possessed by the downstream terminal device is obtained by making an inquiry to the terminal device.

  The invention according to claim 19 is the connection according to any one of claims 4 to 10, wherein the connection means includes a buffer capacity of the ring buffer area for a channel related to the connection destination introduction request. A destination introduction request is transmitted as the connection destination introduction request.

  An invention according to claim 20 is a program for causing a computer to function as each unit of the terminal device according to any one of claims 4 to 19.

  According to the present invention, the ring buffer area for temporarily storing the content data is dynamically set in accordance with the viewing situation of the user. Even when a device with a small storage area such as a box or a digital home appliance is used as a terminal device, the ring buffer area can be set appropriately. For example, while maintaining a function (connection pooling function) for quickly responding to a channel switching request by a viewing user, a complementary function for packet loss that occurs when relaying content data from upstream to downstream, It is possible to appropriately set the execution degree of the trick play function for the content data in accordance with the viewing frequency. In other words, the packet loss compensation function is more reliably applied to channels with high viewing frequency, and the trick play function is performed over a wide range, and the packet loss loss compensation function is moderately applied to channels with low viewing frequency. The buffer capacity of the ring buffer area can be adjusted to perform the function in a narrow range.

  According to the second aspect of the present invention, the buffer capacity of the ring buffer area of the terminal device constituting the hierarchical structure decreases from upstream to downstream of the hierarchical structure in accordance with the buffer capacity of the ring buffer area in the terminal device. Thus, the distribution path can be formed as described above, so that each terminal apparatus can reliably perform the process of complementing the lost packet generated in the stream relay process.

  According to the fifth aspect of the present invention, since the ring buffer area having a buffer capacity corresponding to the number of times content data is reproduced is set, the ring buffer area of a channel having a small number of reproduction times can be reduced, and the ring buffer area The buffer capacity of the area can be efficiently allocated.

  According to the sixth aspect of the present invention, since the ring buffer area having a buffer capacity corresponding to the reproduction time of the content data is set, the ring buffer area of the channel having a short reproduction time can be reduced, and the ring buffer area can be reduced. The buffer capacity of the area can be efficiently allocated.

  According to the seventh aspect of the present invention, the ring buffer area is updated so as to have a buffer capacity corresponding to the reproduction status of the content data for each channel every predetermined period. A ring buffer area having a buffer capacity corresponding to the storage capacity can be set in the storage means.

  According to the invention described in claim 8, since the ring buffer area exceeding the predetermined number is not set in the storage means, it is possible to prevent the ring buffer area from being set in the storage means indefinitely. it can.

  According to the ninth aspect of the present invention, the ring buffer area having the longest non-reproduced period is deleted from the ring buffer areas set in the storage means, and the ring corresponding to the newly selected channel is deleted. Since the buffer area is set, it is possible to delete the ring buffer area that has little influence on the content reproduction by the user of the terminal device, and to perform appropriate replacement according to the usage status of the terminal device.

  According to the tenth aspect of the invention, since the buffer capacity of the ring buffer area is notified to the connection management apparatus every predetermined period, the connection management apparatus collects information on the buffer capacity of each terminal apparatus. This makes it possible to perform connection destination introduction processing more accurately based on the size of the buffer capacity of the ring buffer area.

  According to the eleventh aspect of the present invention, when the ring buffer area is set by the ring buffer setting means, or when the buffer capacity of the ring buffer area is changed by the ring buffer setting means, the buffer capacity of the ring buffer area is reduced. Since the connection management device is notified, the connection management device can collect information on the buffer capacity of each terminal device, and the connection destination introduction process based on the size of the buffer capacity of the ring buffer area can be more accurately performed. You can do it.

  According to the twelfth aspect of the present invention, since the ring buffer area can be set using the nonvolatile storage device, the ring buffer area is supplied with power even when the power is temporarily down. It becomes possible to return to the state before going down, and appropriate power failure (instantaneous interruption) measures can be taken.

  According to the invention described in claim 13, when the buffer capacity of the ring buffer area in the terminal device is larger than that of the upstream device, reconnection is further performed upstream, so that the terminal device having a large buffer capacity. As a result, it is possible to arrange in a higher layer in the hierarchical structure, and it is possible to configure a hierarchical structure that can accurately perform the lost packet complementing process.

  In addition, according to the inventions of claims 14 and 15, since the buffer capacity of the ring buffer area of the upstream terminal device is acquired at every predetermined opportunity, the position of the hierarchical structure is periodically changed. Even when terminal devices whose buffer capacity is frequently changed are arranged in a hierarchical structure, a hierarchical structure capable of accurately performing the process of compensating for lost packets is appropriately configured. Is possible.

  According to the invention described in claim 16, when the buffer capacity of the ring buffer area in the terminal device is smaller than that of the downstream device, reconnection is further performed downstream, so that the terminal device having a small buffer capacity. As a result, it is possible to arrange in a lower layer in the hierarchical structure, and it is possible to configure a hierarchical structure capable of accurately performing the process of compensating for lost packets.

  Further, according to the inventions of claims 17 and 18, since the buffer capacity of the ring buffer area of the downstream terminal device is acquired at every predetermined opportunity, the position of the hierarchical structure is periodically changed. Even when terminal devices whose buffer capacity is frequently changed are arranged in a hierarchical structure, a hierarchical structure capable of accurately performing the process of compensating for lost packets is appropriately configured. Is possible.

  According to the nineteenth aspect of the present invention, the buffer capacity of the ring buffer area is notified to the connection management device when participating in the hierarchical structure, so that the position corresponding to the notified buffer capacity is set. It becomes possible to select a connection destination candidate.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described based on the drawings. The embodiment described below is a content distribution system with a tree structure using P2P, in which content data distributed from a content distribution apparatus in a broadcast format is P2P by a terminal device that configures a tree-like hierarchical structure. This is an embodiment in which the present invention is applied to a broadcast-type content distribution system that is used and received.

(First embodiment)
[1. Content distribution system configuration]
First, with reference to FIG. 1, a schematic configuration and the like of the content distribution system S in the first embodiment will be described.

  FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system S according to the first embodiment. As shown in FIG. 1, the content distribution system S according to the first embodiment is a broadcast-type content distribution system, and a plurality of distribution channels (hereinafter simply referred to as “ Called “channel”). For example, in the channel ch1, a plurality of terminal devices 2a1, 2a2, 2b1-2b4, 2c1-2c8 are logically connected in a tree-like hierarchical structure with the content distribution device 1 as a vertex, and content data is received from the content distribution device 1. The tree structure is configured to be streamed from the upper layer to the lower layer. The other channels have the same configuration.

  In addition, the content distribution system S is provided with a connection management device 3, and this connection management device 3 manages the tree-like hierarchical structure of each channel.

  An IP address is assigned to each of the content distribution device 1, the terminal devices 2a1, 2a2, 2b1 to 2b4, 2c1 to 2c8, and the connection management device 3, and these devices are connected to the Internet 4 as an example of a network, a router 10 and the like. Connected through. In other words, communication connection is possible by transmitting a packet including a header with the destination IP address of the target terminal device as the destination IP address and the IP address of the own device as the source IP address.

  The connection management device 3 may be included in the content distribution device 1. In this case, the connection management apparatus 3 may not be assigned an IP address, and may be shared with the IP address of the content distribution apparatus 1. In addition, the content distribution apparatus 1 may distribute content data of all channels of a plurality of channels (here, channel ch1 to channel chn) constituting the content distribution system S, for each channel. The content distribution device 1 may be provided. In the first embodiment, a description will be given on the assumption that one content distribution apparatus 1 performs streaming distribution of content data of all channels ch1 to chn.

  Further, in the case of showing any one of the terminal devices 2a1, 2a2, 2b1-2b4, 2c1-2c8 or all the terminal devices, it may be called the terminal device 2 for convenience. Also, the first layer terminal devices 2a1 and 2a2 are referred to as the terminal device 2a for convenience, the second layer terminal devices 2b1 to 2b4 are referred to as the terminal device 2b, and the second layer terminal devices 2c1 to 2c8 are referred to as the terminal device 2c for convenience. There is.

  In the content distribution system S, the connection management device 3 uses the content distribution device 1 as a vertex (here, the 0th layer for convenience) so that a plurality of terminal devices 2 are logically connected in multiple layers in a tree-like hierarchical structure. Managed. In the first embodiment, a tree-like hierarchical structure is described. However, the present invention is not limited to this, and a plurality of terminal devices 2 may be logically connected in multiple layers in a chain-like hierarchical structure.

  When the connection management device 3 receives a connection destination introduction request from the terminal device 2 that does not participate in the content distribution system S, in other words, from the terminal device 2 that does not constitute a tree-like hierarchical structure, the connection management device 3 Based on the state of the structure and the like, a connection destination candidate (content distribution apparatus 1 or terminal apparatus 2) to be connected as an upstream apparatus for receiving the streaming distribution of the terminal apparatus 2 is selected. Then, the connection management device 3 notifies the terminal device 2 of the location information (such as the IP address and port number of the connection destination candidate) and the communication protocol of the connection destination candidate thus selected.

  In the content distribution system S, when the communication protocol and the port number are already fixed, the port number and the communication protocol to the terminal device 2 need not be notified. Here, MMS (Microsoft Media Server) protocol, RTSP (Real Time Streaming Protocol), etc. are used as communication protocols. As the format of the content data, ASF (Advanced Streaming Format), WMA (Windows (registered trademark) Media Audio), WMV (Windows (registered trademark) Media Video), or the like is used.

  Upon receiving the location information of the connection destination candidate from the connection management device 3, the terminal device 2 requests the connection destination candidate to participate (connect) to the content distribution system S with the location information as a destination, and thereby the terminal device 2 is incorporated into the hierarchical structure in the content distribution system S. That is, the terminal device 2 can receive the content data distributed from the content distribution device 1. Participation in the content distribution system S is performed for each channel of the content distribution apparatus 1, and the terminal device 2 participates for each channel and receives the content data of the channel in which the participation has been performed. become. Here, participation in a channel means participation in a hierarchical structure having the content distribution apparatus 1 corresponding to the channel as a vertex, and content data of the channel that has participated by participating in the channel in this way. Can be received from a device upstream of the hierarchical structure. Further, the “upstream device” means an upstream device (terminal device 2 or content distribution device 1) connected to the terminal device 2 in a hierarchical structure. For example, the upstream terminal device in the terminal device 2b2 in FIG. 1 refers to the terminal device 2a1.

  In the content distribution system S, when the terminal devices 2 participate in each channel one after another in this manner, a plurality of terminal devices 2 are logically connected in multiple layers in a tree-like hierarchical structure with the content distribution device 1 as a vertex for each channel. The Then, the content data distributed from the content distribution apparatus 1 for each channel is sequentially relayed to the lower terminal apparatus 2 by the relay function of the terminal apparatus 2 and streamed to the plurality of terminal apparatuses 2.

  That is, as shown in FIG. 1, in channel ch1, content data is transmitted from the content distribution device 1 to the terminal devices 2a1, 2a2 (first layer terminal devices), and the terminal devices 2a1, 2a2 receive the content data. The received content data is sequentially relayed to the lower-layer terminal devices 2b1 to 2b4 (second-layer terminal devices). When receiving the content data, the terminal devices 2b1 to 2b4 sequentially relay the received content data to the lower-layer terminal devices 2c1 to 2c8 (third-layer terminal devices).

  The terminal device 2 stores the location information of the terminal device 2 or the content distribution device 1 upstream of the position of the incorporated hierarchical structure, and the location information of the terminal device 2 downstream of the location, which will be described later. The content data is relayed based on the stored location information. Further, the content data to be distributed is divided into a plurality of packets and sequentially distributed, and the data thus divided and distributed is called a content packet.

  Thus, the content data distributed to the terminal device 2 is distributed to all the terminal devices 2 participating in the content distribution system S for each channel. The distributed content data includes playback time information (hereinafter referred to as “playback time data”) in addition to content data such as music and movies. Then, the plurality of terminal devices 2 that have received the content data perform the reproduction of the content data that is sequentially transmitted based on the reproduction time data. In this way, the content distribution system S can stream-distribute content data transmitted from the content distribution device 1 for each channel to the plurality of terminal devices 2 and reproduce the content at the same time on the plurality of terminal devices 2. it can. That is, the content distribution system S realizes streaming distribution in a broadcast format to a plurality of terminal devices 2 using P2P.

  As described above, the content distribution system S according to the first embodiment has a plurality of channels for streaming distribution of a plurality of content data. When the user selects a desired channel, the terminal device 2 acquires the connection destination device (hereinafter, referred to as “connection destination candidate”) of the terminal device 2 in the selected channel from the connection management device 3. Then, the terminal device 2 participates in a hierarchical structure of a desired channel by connecting to the connection destination candidate, and receives and reproduces content data from a device upstream of the own terminal device 2 in this hierarchical structure.

  Next, a case will be described in which the terminal device 2 switches the channel that the user of the terminal device 2 views (reproduces) after joining the hierarchical structure of a certain channel in this way. When the user makes a selection to switch channels, in the conventional content distribution system S, the terminal device 2 leaves the hierarchical structure of the participating channel, and participates in the hierarchical structure of the channel for which switching has been selected. It was done in the procedure.

  In this case, when joining from a hierarchical structure of a participating channel to another channel hierarchical structure, a process for receiving information on connection destination candidates from the connection management device 3 and connection to the connection destination candidates It is necessary to perform a series of connection processing such as the above processing. For this reason, in the conventional content distribution system S, the state in which the content data is not reproduced occurs for the time until the content data of the switching destination channel is received and reproduced, and the operability of the user of the terminal device 2 is lowered. It was.

  Therefore, in the terminal device 2 in the first embodiment, content data is not reproduced even when the channel is switched in the terminal device 2 by continuously participating in the hierarchical structure of a plurality of channels. The period is not generated. That is, the terminal device 2 establishes a connection (session) with another terminal device 2 participating in each of the plurality of channels, and continues the connection.

  A ring that temporarily stores content data of each channel so that the terminal device 2 can receive content data of a plurality of channels distributed by streaming and can reproduce or relay to the downstream terminal device 2 The buffer area is set in a storage device such as a RAM. Here, the “downstream terminal device” means a downstream terminal device connected to the own terminal device 2 in the hierarchical structure. For example, the downstream terminal devices in the terminal device 2b2 in FIG. 1 indicate the terminal devices 2c3 and 2c4.

  By the way, when the number of channels that are connected simultaneously, that is, the number of channels that participate at the same time increases, the number of ring buffer areas to be prepared increases accordingly, and the necessary storage area increases. In a terminal device with a small storage area such as a set-top box or a digital home appliance, setting a plurality of ring buffer areas in this way is heavy and has a limit.

  Therefore, in the terminal device 2 in the first embodiment, the buffer capacity of the ring buffer area other than the ring buffer area corresponding to the channel selected for reproduction (hereinafter, sometimes referred to as “ring buffer capacity”). Is made smaller. That is, the buffer capacity of the ring buffer area corresponding to the channel not in the reproduction state among the plurality of ring buffer areas is made smaller than the buffer capacity of the ring buffer area corresponding to the channel in the reproduction state.

  Here, the ring buffer area in the terminal device 2 will be described. FIG. 2 is a diagram conceptually illustrating a configuration in which content data is received using the ring buffer area in the terminal device 2 of the first embodiment and is played back or relayed to the downstream terminal device 2.

  When the terminal device 2 participates in the hierarchical structure of the desired channel, the content data included in the received content packet is sequentially received by the stream receiver from the upstream device in the hierarchical structure and transmitted by streaming. Are temporarily stored in the ring buffer area. The content data temporarily stored in the ring buffer area is taken out of the ring buffer area and played by the player as the playback means of the terminal device 2 at the playback time.

  Here, as shown in FIG. 2, new content data is sequentially stored in the ring buffer area in the clockwise direction, and the oldest content data is rewritten to new content data. That is, if the point written in the ring buffer area by the stream receiver is A, the point A moves clockwise.

  Note that the ring buffer area in FIG. 2 is conceptually shown, and is not actually ring-shaped, but the control unit of the terminal device 2 stores the oldest content stored in a predetermined address area in the storage area. This is realized by sequentially rewriting data with new content data.

  Further, the playback time information is stored in the content data as described above, and the player has content data having playback time data that matches the current time among the content data accumulated in the ring buffer area (here, FIG. 2). The content data of the middle B point) is taken out from the ring buffer area and sequentially reproduced.

  With such a ring buffer area, content data before the playback time is accumulated, and content packet loss that occurs intermittently depending on the state of the Internet 4 by the playback time is dealt with. In other words, the content distribution apparatus 1 distributes content data while ensuring a margin sufficient to perform packet loss compensation processing.

  Here, when two other terminal apparatuses 2 are connected downstream of the hierarchical structure, as shown in FIG. 2, the terminal apparatus 2 is provided with two stream transmitters. This stream transmitter stores the content data stored in the ring buffer area in the data area of the content packet every predetermined amount, generates a content packet, and transmits this content to the other terminal devices 2 connected downstream. Send packets sequentially.

  In the terminal device 2 in the first embodiment, the content data included in the content packet transmitted from the upstream device is extracted and stored in the ring buffer area, but the content packet is stored in the ring buffer area as it is. You may make it do. In any case, the stream transmitter transmits to the downstream terminal device 2 a content packet in which the information on the transmission destination and transmission source of the content packet received by the stream receiver is replaced.

  By the way, when the user of the terminal device 2 is viewing the content data streamed from the content distribution device 1, the user may want to reproduce the content data whose reproduction time has passed from an arbitrary position. This is so-called trick play. In the example of the ring buffer area shown in FIG. 2, trick play is possible for the buffer area X from point B to point C counterclockwise.

  As described above, the terminal device 2 provides a ring buffer area for temporarily storing content data, thereby supplementing the packet loss while prebuffering the content packet, and is generated on the Internet 4 route. The effect of packet loss is avoided.

  Further, by making the buffer capacity of the ring buffer area larger than the buffer capacity for the pre-buffering, it is possible to perform trick play on the content data whose playback time has passed by the user operation of the terminal device 2. Become.

  The terminal device 2 in the first embodiment is configured such that a plurality of ring buffer areas for temporarily storing content data of a plurality of channels can be set as storage areas, and these ring buffers are further configured. The buffer capacity of the area is set as the buffer capacity corresponding to the reproduction status.

  FIG. 3 is a diagram for explaining the distribution of the buffer capacity of the ring buffer area, and shows an example in which the content data of the three channels ch1 to ch3 are received by the first to third ring buffer areas, respectively. It is what. In this example, since the reproduction frequency (viewing frequency) of the channel ch1 is high and the reproduction frequency (viewing frequency) of the channels ch2 and 3 is low, the buffer capacity of the second and third ring buffer areas is set to the buffer of the first ring buffer area. A state in which it is smaller than the capacity is shown.

  Here, as a condition for setting the buffer capacity according to the reproduction status, there is a reproduction frequency as described above. The reproduction frequency includes the number of reproductions of content data per unit time in each channel, the reproduction time, and the like.

  By reducing the buffer capacity of the ring buffer area as the number of playbacks is reduced or the playback time is shorter, the buffer capacity of the ring buffer area of a channel that is not used much (ie, the number of playbacks and playback time is less) is reduced. Can do.

  In addition, the buffer status of the ring buffer area is updated by detecting the playback status periodically or at a predetermined timing, and the buffer capacity of the ring buffer area can be distributed according to the latest playback status. .

  As described above, in the terminal device 2 in the first embodiment, the storage capacity necessary for setting the ring buffer area is made as much as possible by setting the buffer capacity of the ring buffer area to a buffer capacity corresponding to the reproduction status. This makes it possible to efficiently use the storage area in the terminal device having a small storage area capacity for setting the ring buffer area.

  That is, by setting a plurality of ring buffer areas as storage areas and maintaining connection with a plurality of channels, the connection process at the time of channel switching by the user is unnecessary, eliminating the blank period of content data reproduction, and the storage area by the ring buffer area Therefore, the occupancy ratio can be suppressed overall.

  As described above, when the number of channels connected simultaneously increases, the number of ring buffer areas to be prepared increases accordingly, and the required storage area increases.

  Therefore, in the terminal device 2 in the first embodiment, in addition to changing the buffer capacity of the ring buffer area between the reproduction state and the non-reproduction state as described above, the number of ring buffer areas set in the storage area is limited. I am doing so. For example, 10 channels that can be connected simultaneously are determined.

  By limiting the number of channels connected at the same time as described above, it is possible to prevent the ring buffer area from increasing without limitation.

  In the terminal device 2 configured in this way, when a state to be connected to a new channel occurs while being connected to the upper limit number of channels, the channel is in a non-reproducing state and satisfies a predetermined condition And disconnect the ring buffer area from the storage area. The terminal device 2 sets the ring buffer area of the new channel as a storage area and connects to the channel. For example, when a new channel is selected, the terminal device 2 deletes the ring buffer area corresponding to the channel having the longest non-reproduction state and secures the ring buffer area corresponding to the newly selected channel. It is.

  In the terminal device 2 of the first embodiment, the channel to be connected is the channel selected by the user. That is, when the user of the terminal device 2 operates the remote controller 205 or the like as a channel selection unit to be described later, the terminal device 2 sequentially connects to the selected channel, and stores a ring buffer area for each connected channel in the storage unit. I try to set it.

  In FIG. 4, in the terminal device 2c1 connected to the channel ch1, switching from the channel ch1 to the channel ch2 is instructed by a user's operation of the remote controller or the like, and the terminal device 2 continues to connect the channel ch1 while A state of connection to ch2 is shown. Note that the connection to the channel ch2 is made for the connection destination candidate notified from the connection management device 3. In the example illustrated in FIG. 4, the terminal device 2 d 1 is notified from the connection management device 3 as a connection destination candidate.

  Here, the state of the ring buffer area of the terminal device 2c1 before and after the terminal device 2c1 is connected to the terminal device 2d1 as the terminal device 2e1 is shown in FIGS. As shown in this figure, in the terminal device 2, in addition to the ring buffer area of channel ch1, the ring buffer area of channel ch2 is set as a storage area. The buffer capacity of each ring buffer area depends on the reproduction status of the channel. Set accordingly.

  Further, it is also possible to simultaneously connect to a channel set when the terminal device 2 is powered on by a user's prior selection. Hereinafter, the operation of connecting to a plurality of channels selected in advance in the terminal device 2 will be described.

  First, the user of the terminal device 2 selects a channel to be connected when the power is turned on by operating a remote controller 205 described later. Information on the channel thus selected (for example, a channel number) is stored in the storage unit of the terminal device 2. When the terminal device 2 is powered on, the terminal device 2 retrieves the channel information stored in the storage means by the execution of the program of the terminal device 2, and connects to these channels.

  Thus, since the connection to the channel selected in advance by the user is made when the power is turned on, there is no period during which the content data is not reproduced, and the user of the terminal device 2 can comfortably view the content data. .

  Further, instead of the user's pre-setting or in addition to the user's pre-setting, the terminal device 2 can be configured to select a channel to be connected when the power is turned on.

  For example, the control means of the terminal device 2 detects the playback history such as the playback time and playback frequency of the channel selected by the user, and stores this playback history in the storage area of the terminal device 2 itself. Then, when the terminal device 2 is powered on, the control unit selects a channel that is likely to be viewed by the user based on the reproduction history, and the terminal device 2 is connected to the channel thus selected. is there.

  As described above, by selecting a channel to be connected when the power is turned on based on the reproduction history, it is possible to reduce the setting work by the user in advance. In other words, the channel selection means is a program stored in advance in the terminal device 2 instead of the remote controller 205. In other words, the channel to be connected when the power is turned on can be said to be a channel predetermined in the initial setting.

  By the way, the amount of content data that the terminal device 2 has to pre-buffer varies depending on where the terminal device 2 is connected in the hierarchical structure.

  In other words, in order to ensure that the terminal device 2 can compensate for the loss of the content packet that occurs in the distribution route for the relay process of the content packet, that is, the distribution route of the content packet in the hierarchical structure on the Internet 4, The amount of pre-buffering has to be increased as the terminal device 2 in the upper layer.

  For example, as shown in FIG. 1, when the hierarchical structure is configured by a four-layer structure (the content distribution device 1 is assumed to be the 0th layer), the first from the content distribution device 1 to the terminal device 2a in the first layer. Loss of content packet in the route, the second route from the terminal device 2a in the first layer to the terminal device 2b in the second layer, and the third route from the terminal device 2b in the second layer to the terminal device 2c in the third layer However, at this time, since the upstream terminal device 2 needs to hold the lost packet supplemented by the downstream terminal device 2, the upstream terminal device 2 has a pre-buffering amount. The distribution route is formed so that there are many.

  Here, with reference to FIG. 6, the pre-buffering of the device in each layer will be described.

  As shown in FIG. 6, in the ring buffer area of terminal device 2, a margin (hereinafter referred to as “reproduction margin”) is necessary between a transmission / reception point and a reproduction point in consideration of transmission delay due to retransmission processing. It is. That is, the content distribution system S must distribute content data with a reproduction margin that takes into account the retransmission time that may occur in stream relay processing per track. In other words, this reproduction margin is a recovery processing time for a content packet loss that may be consumed from the start of distribution of one track of content by the content distribution apparatus 1 to the end of distribution.

  FIG. 6A shows the state of the ring buffer area of the terminal device 2 when retransmission processing does not occur in the hierarchical structure of a certain channel. In the first embodiment, the reproduction margin of the terminal device 2 per layer is set to 3 packets. In the example of this figure, since retransmission processing has not yet occurred, a reproduction margin of 9 packets exists at the reproduction point and the reception point in the lowermost terminal device 2c.

  On the other hand, as shown in FIG. 6B, when retransmission processing for two packets occurs in the terminal device 2a in the first layer, and retransmission control for three packets occurs in the terminal device 2b in the second layer, In the lower terminal apparatus 2c, the reproduction margin is reduced to 4 packets. That is, the reproduction margin for the accumulated retransmission time performed on the route from the content distribution apparatus 1 to the lowermost terminal apparatus 2c is lost to the lowermost terminal apparatus 2c.

  Therefore, in order to cause all the terminal devices 2 to reproduce the content data at the same time based on the time information stored in the content packet, the content data is routed from the content distribution device 1 to the lowermost terminal device 2c. A reproduction margin having a retransmission time that may occur in the stream relay processing of one track is required, and a ring buffer area for having this reproduction margin is required. And it is necessary to increase the amount of pre-buffering as the terminal device 2 is higher.

  Therefore, the connection management device 3 in the first embodiment stores, for each channel, information on the buffer capacity of the ring buffer area of the terminal device 2 constituting the hierarchical structure of the channel in the connection state information storage means, The hierarchical structure of each channel is managed so that the buffer capacity of the ring buffer area of the terminal device 2 constituting the hierarchical structure decreases from upstream to downstream of the hierarchical structure.

  Here, an operation of joining the predetermined channel (here, channel ch1) in the terminal device 2 will be described with reference to FIG. As shown in FIG. 7, each terminal device 2 connected to the channel ch1 periodically notifies the connection management device 3 of the buffer capacity of the ring buffer area corresponding to the channel ch1.

  Then, in order for the terminal device 2x to participate in the channel ch1, the connection management device 3 is requested to notify the connection destination candidate. At this time, the terminal device 2x also notifies the connection management device 3 of the buffer capacity of the ring buffer area corresponding to the channel ch1 (here, 20 MB).

  When receiving the connection destination candidate notification request and the buffer capacity from the terminal device 2x, the connection management device 3 is larger than the buffer capacity of the terminal device 2x among the terminal devices 2 constituting the hierarchical structure of the channel ch1 that is the participation request target. The terminal device 2b4 having the buffer capacity of the ring buffer area (here, 30 MB) is selected as a connection destination candidate and notified to the terminal device 2x that has made the participation request. Although the buffer capacity of the ring buffer area of the terminal device 2a2 is as large as 40 MB, the connection destination candidate selected by the connection management device 3 is a terminal device having a buffer capacity closest to the buffer capacity of the ring buffer area of the terminal device 2x. That is, the terminal device 2b4 is selected.

  The terminal device 2 that has received the notification of the connection destination candidate from the connection management device 3 connects to the terminal device 2b4 that is the notified connection destination candidate, receives the content data of the channel ch1 from the terminal device 2b4, and reproduces it. To do.

  On the other hand, the terminal device 2 constituting the hierarchical structure of the channel acquires the buffer capacity of the ring buffer area of the terminal device 2 upstream or downstream of the own terminal device 2 in the connected channel hierarchical structure. Compared with the buffer capacity of the ring buffer area of the terminal device 2, reconnection is performed at an appropriate position in the hierarchical structure.

  Here, the reconnection operation in the terminal device 2 will be described with reference to FIG. As shown in FIG. 8, it is assumed that the buffer capacities of the ring buffer areas in the terminal apparatuses 2a2, 2b4, 2c8 connected to the hierarchical structure of the channel ch1 are 40 MB, 10 MB, and 20 MB.

  The terminal device 2b4 connected to the hierarchical structure of the channel ch1 has the buffer capacity of the ring buffer area of these terminal devices 2a2 and 2c8 with respect to the upstream terminal device 2a2 and downstream terminal device 2c8 of the terminal device 2 itself. Request to be notified.

  In response to this request, the terminal device 2a2 notifies the terminal device 2b4 that the buffer capacity of the ring buffer area of the terminal device 2a2 is 40 MB. Similarly, the terminal device 2c8 notifies the terminal device 2b4 that the buffer capacity of the ring buffer area of the terminal device 2c8 is 20 MB.

  Since the terminal device 2b4 has a buffer capacity of its own ring buffer area lower than that of the downstream terminal device 2c8, the terminal device 2b4 requests the connection management device 3 to notify the connection destination candidate. As described above, the connection management device 3 is a connection destination candidate (here, the terminal device 2c5) at a position where the buffer capacity of the ring buffer area of the terminal device constituting the hierarchical structure decreases from upstream to downstream of the hierarchical structure. ) Is selected and notified to the terminal device 2b4. The terminal device 2b4 connects to the connection destination candidate notified from the connection management device 3.

  In this way, the terminal device 2 acquires the buffer capacity of the ring buffer area of the terminal device 2 upstream or downstream of the terminal device 2, compares it with the buffer capacity of the ring buffer area of the terminal device 2, By reconnecting to an appropriate position in the hierarchical structure, it is possible to reliably compensate for the loss of content packets.

  Hereinafter, specific configurations and operations of the content distribution device 1, the terminal device 2, and the connection management device 3 constituting the content distribution system S will be described with reference to the drawings.

[2. Description of Content Distribution Device 1 Configuration]
Next, the configuration and operation of the content distribution apparatus 1 will be described with reference to FIG.

  FIG. 9 is a diagram illustrating a schematic configuration example of the content distribution apparatus 1 according to the first embodiment. The content distribution apparatus 1 is applicable to a general server computer, and as shown in FIG. 9, a CPU (Central Processing Unit) 101 and a second rewritable main storage apparatus that stores (stores) various programs and the like. Communication is performed between the terminal device 2 and the connection management device 3 via the Internet 4 and the second storage unit 103 configured by one storage unit 102, an HDD (Hard Disc Drive) or the like that stores various data and the like. The network interface 104, a peripheral device control chip 107 that controls input means such as a keyboard 105 and a mouse 106 capable of inputting predetermined information, and image data from the CPU 101 are received and written to an internal video memory (not shown). Video chip 1 for displaying data written in the video memory on a display 109 described later 8, a display 109 that performs display according to a signal transmitted from the video chip 108, a sound source chip 110 having a sound source such as an FM sound source (Frequency Modulation) or a Wave Table sound source, and an audio signal output from the sound source chip 110 And a built-in speaker 111 that converts sound waves into sound waves, and these various components are connected to each other via a system bus 112.

  The network interface 104 is connected to the Internet 4 via the router 10a.

  In the first embodiment, the CPU 101 and the first storage unit 102 constitute a control unit 113. In addition, a display (liquid crystal display or the like) 109 or the like is connected to the content distribution apparatus 1 as described above. For example, a broadcast operator who operates the content distribution system S looks at the display 109. However, it is possible to input predetermined information from the input means.

(About the first storage unit 102)
Further, the first storage unit 102 extracts an OS (Operating System) program 120 for providing basic functions as a computer of the content distribution apparatus 1 and content data stored in the second storage unit 103. A stream control program 121 for streaming delivery to the terminal device 2, a topology management program 122 for managing the location information (IP address, port number, etc.) of the first layer terminal device 2a for each channel, and a display A screen control program 123 for controlling 109 and a player program 124 for decoding the encoded content data and for decoding the content data in the broadcast content database 114 are stored. Read, and functions according to the program by the CPU101 is executed.

  The first storage unit 102 is provided with a ring buffer settable area 125. In this ring buffer settable area 125, a ring buffer area for each channel can be set. Here, ring buffer areas respectively corresponding to the channels ch1 to chn are set as ring buffer areas 125a to 125n (not shown), and a ring buffer area corresponding to a channel to be distributed is set in the ring buffer settable area 125. The

  Here, the OS program 120 is read and executed by the CPU 101, whereby functions relating to input / output of the keyboard 105 and mouse 106, and content distribution devices such as memory management of the first storage unit 102 and the second storage unit 103 The basic function of the computer 1 can be executed. Then, with the OS program 120 being executed by the CPU 101, the above-described stream control program 121, topology management program 122, screen control program 123, and player program 124 are read from the first storage unit 102. Executed.

  The OS program 120, the stream control program 121, the topology management program 122, the screen control program 123, the player program 124, etc. are downloaded to the first storage unit 102 from, for example, a server connected to the Internet 4. Alternatively, after being recorded on a recording medium such as a CD-ROM, it may be read into the first storage unit 102 via a drive of the recording medium.

(Regarding the controller 113)
The control unit 113 includes the CPU 101 and the first storage unit 102 as described above, and the CPU 101 reads out and executes the various programs 120 to 124 stored in the first storage unit 102, whereby the entire content distribution apparatus 1 is executed. And functions as distribution means, topology management means, display control means, reproduction means and the like which will be described later. The CPU 101 executes the stream control program 121 to serve as a distribution unit, the CPU 101 executes the topology management program 122, the topology management unit, and the CPU 101 executes the screen control program 123. When the CPU 101 executes the player program 124 as a display control unit or the like, it functions as a reproduction unit.

(About distribution means)
The distribution means takes out the content data designated for each channel from the broadcast content database 114 by the input means such as the keyboard 105, and distributes the data via the network interface 104 to the terminal device 2a on the first layer of each channel. To do.

  Streaming distribution to the terminal device 2a and the like by this distribution means is executed according to the following procedure.

  The distribution unit retrieves content data corresponding to the content selected for each channel or the preset content from the broadcast content database 114.

  Next, the distribution means encodes the content data extracted from the broadcast content database 114 into a data format for streaming distribution, for example, a data format such as ASF, WMA, WMV.

  Thereafter, the distribution means stores the corresponding content data in the content packet while dividing the content data for each predetermined capacity with respect to the first layer terminal device 2a and the like of each channel, and the content packet is transmitted via the network interface 104. Send to.

(Topology management means)
The content distribution apparatus 1 has a plurality of channels for streaming distribution of different contents at the same time (a plurality of content distribution apparatuses 1 may exist and one channel may be allocated to each content distribution apparatus 1). The topology management means manages the location information (IP address, port number, etc.) of the terminal devices 2 participating in the first layer of the tree-like hierarchical structure configured for each channel. The topology management means manages the distribution IP addresses corresponding to the plurality of channels, respectively. The above distribution means distributes content data to the terminal apparatus 2 using the IP address of the terminal device 2 managed by the topology management means as the destination address and the distribution IP address as the transmission source.

  In the first embodiment, the IP addresses of the plurality of channels are made different. However, the plurality of channels may be configured by making the port numbers different using the same IP address. In this case, a tree-like distribution structure is configured for each port number.

(Display control means)
The display control means has a function of controlling the video chip 108 and the display 109 to display content data and various information. That is, the display control means can control how the content video and various information are displayed on the display 109.

(About playback means)
The reproduction means has a function of displaying content data stored in the broadcast content database 114 on the display 109 or outputting from the speaker 111.

[3. Description of Configuration of Terminal Device 2]
Next, the configuration and operation of the terminal device 2 will be described with reference to FIG.

  FIG. 10 is a diagram illustrating a schematic configuration example of the terminal device 2 in the first embodiment. As the terminal device 2, a general personal computer or a dedicated terminal can be applied. As shown in FIG. 10, as a rewritable main storage device that stores (stores) a CPU (Central Processing Unit) 201 and various programs. Between the first storage unit 202, the second storage unit 203 composed of an HDD (Hard Disc Drive) or the like for storing various data, and the content distribution apparatus 1 or the connection management apparatus 3 via the Internet 4. A network interface 204 for performing communication, a remote controller 205 for transmitting and receiving a predetermined infrared signal for a user to remotely operate the terminal device 2, an infrared port 206 for performing infrared communication with the remote control 205, and an infrared port The peripheral device control chip 207 that controls 206 and the image data from the CPU 201 are received. And a video chip 208 for writing data to the internal video memory (not shown) and displaying the data written to the video memory on a built-in display 209 to be described later, and a built-in display for displaying a signal corresponding to a signal transmitted from the video chip 208 The display 209 includes a sound source chip 210 having a sound source such as an FM sound source (Frequency Modulation) or a Wave Table sound source, and a built-in speaker 211 that converts an audio signal output from the sound source chip 210 into a sound wave. Various components are connected to each other via a system bus 212.

  In the first embodiment, the CPU 201 and the first storage unit 202 constitute a control unit 213. The network interface 204 is connected to the Internet 4 via the router 10b.

  Here, the remote controller 205 has a channel selection button (not shown) as a selection means for selecting a channel of the content distribution system S, and the user of the terminal device 2 can select a desired channel using the channel selection button. Can be connected.

(Regarding the first storage unit 202)
The first storage unit 202 also distributes the OS program 220 for providing basic functions of the terminal device 2 as a computer, and streaming distribution from the content distribution device 1 directly or to another terminal device 2. Stream control program 221 for receiving and streaming the content data to be streamed to the downstream terminal device 2, location information (IP address and port number) and tree of the connected upstream device (or content distribution device 1) Topology control program 222 for managing location information of the connected downstream terminal device 2, screen control program 223 for controlling the display 209, and content data received by streaming from the upstream device Player (playback) program 224, Stores a connection pool program 225 or the like that manages the connection with the number of channels, they are retrieved by the CPU 201, and functions according to the program by the CPU 201 is executed.

  Further, the first storage unit 202 is provided with a ring buffer settable area 226 in which a ring buffer area for temporarily storing content data distributed for each channel can be set. In this ring buffer settable area 226, a ring buffer area for each channel can be set. Here, the ring buffer areas corresponding to the channels ch1 to chn are the ring buffer areas 226a to 226n, respectively, and the ring buffer area corresponding to the channel to be connected is set in the ring buffer settable area 226. Here, the first storage unit 202 is composed of a nonvolatile storage device and a volatile storage device, and the ring buffer settable area 226 is a nonvolatile storage device, while the areas in which various programs 220 to 225 are stored are It is a volatile storage device.

  Here, the OS program 220 is read and executed by the CPU 201, so that the terminal device 2 such as a function related to input / output of the remote controller 205 or memory management such as the first storage unit 202 and the second storage unit 203. It enables the basic functions of a computer to be executed. Then, with the OS program being executed by the CPU 201, the above-described stream control program 221, topology control program 222, screen control program 223, player program 224, connection pool program 225, etc. are read from the first storage unit 202. Executed.

  The OS program 220, the stream control program 221, the topology control program 222, the screen control program 223, the player program 224, the connection pool program 225, etc. are downloaded to the first storage unit 202 from a server connected to the Internet 4, for example. Alternatively, it may be recorded on a storage medium such as a CD-ROM and then read into the first storage unit 202 via a drive of the storage medium.

(About the control unit 213)
The control unit 213 includes the CPU 201 and the first storage unit 202 as described above, and the CPU 201 reads and executes the various programs 220 to 225 stored in the first storage unit 202, whereby the entire terminal device 2 is configured. Centralized control and connection means, topology management means, streaming reception means, reproduction means, display control means, content data reproduction status detection means, ring buffer setting means, relay request reception means, transfer means, buffer capacity notification means, which will be described later , Function as backup processing means, buffer capacity acquisition means, comparison means, reconnection means, and the like.

  As the CPU 201 executes the stream control program 221, as the streaming control means, the transfer means, etc., and as the CPU 201 executes the topology management program 122, as the connection means, the topology management means, the relay request receiving means, etc. Further, the CPU 201 executes the screen control program 223 as a display control unit, the CPU 201 executes the player program 224 as a playback unit, and the CPU 201 executes the connection pool program 225 to reproduce content data. Functions as status detection means, ring buffer setting means, buffer capacity notification means, backup processing means, buffer capacity acquisition means, comparison means, reconnection means, etc. That.

(About connection means)
The connection means transmits a connection destination introduction request for the channel selected by the user's operation of the channel selection button of the remote controller 205 as the channel selection means to cause the terminal device 2 to participate in the content distribution system S. Thereafter, the connection destination candidate notified from the connection management device 3 is connected.

  More specifically, the connection means transmits a registration request to the connection management device 3 to register it in the connection management device 3 and transmits a connection destination introduction request in order to cause the terminal device 2 to participate in the content distribution system S. Thus, the connection management apparatus 3 is requested to request connection destination candidates. The registration request and the connection destination introduction request include information specifying a channel selected by the user of the terminal device 2 operating a channel selection button or the like of the remote controller 205, location information of the terminal device 2, and the like.

  Further, when the connection means transmits a registration request or a connection destination introduction request to the connection management device 3, the connection means transmits the buffer capacity of the ring buffer area for the channel related to the connection destination introduction request. For example, when making a connection destination introduction request for channel ch1, the buffer capacity of the ring buffer area 226a is used. The buffer capacity of the ring buffer area may be included in the registration request or the connection destination introduction request, or may be transmitted separately.

  Furthermore, when the user of the terminal device 2 performs a channel switching operation by operating the remote controller 205 or the like in a state where the terminal device 2 is connected to a certain channel, the connection means newly starts the switching operation. A channel to be connected is determined, and a connection destination introduction request including a channel switching request is transmitted to the connection management device 3.

  As a result, the terminal device 2 can switch the connection from one channel to a new channel. Instead of providing the channel switching button of the remote controller 205, a display control unit (to be described later) may be operated to display a channel selection screen on the display 209 and selected by operating the remote controller 205.

  Further, the connection means responds to the connection destination introduction request transmitted to the connection management device 3, and information on the connection destination candidate notified from the connection management device 3, that is, the IP address that is the location information of the terminal device of the connection destination candidate, It has a function of receiving information such as a port number (hereinafter, may be abbreviated as “connection destination candidate” including connection destination candidate information).

  Further, the connection unit has a function of connecting to the connection destination candidate based on the received information about the connection destination candidate. In other words, the connection means makes a connection request with the destination IP address and port number as the destination based on the information about the destination candidate, and makes a logical connection with the destination candidate. By connecting with the connection destination candidates in this way, it becomes possible to participate in the channel, that is, to incorporate the own terminal device 2 into a part of the tree-like hierarchical structure.

(About topology management means)
The topology management means stores the location information of the upstream device of the tree-like hierarchical structure connected by the connection means in each first connected channel in the first storage unit 202 and manages the transfer described in detail later. The location data of the downstream terminal device 2 in the tree-like hierarchical structure is stored in the first storage unit 202 and managed by the means.

(Streaming reception means)
The streaming receiving unit receives a content packet that is streamed from the upstream terminal device 2 or the content distribution device 1 in the hierarchical structure, and stores the content data included in the content packet in a ring buffer area corresponding to the channel of the content data. Accumulate temporarily.

(About playback means)
The reproduction means has a function of sequentially reproducing the content data stream-received by the streaming reception means, that is, the content data stored in the ring buffer area.

  This reproduction means realizes its function by operating the sound source chip 210 and the video chip 208, and sequentially extracts the content data stored in the ring buffer area and converts it into a predetermined content data format (for example, Wave format). Then, the sound is input to the sound source chip 210 and the video chip 208 to reproduce the content.

  When the content data includes audio information, the content data converted into a predetermined content data format by the reproduction unit is output from the built-in speaker 211 after the audio information is converted into an audio signal by the sound source chip 210. The

  Further, when the video data is included in the content data converted into the predetermined content data format by the reproducing means, the video information is displayed on the display 209 by the control of the display control means described later.

  Further, the reproduction means determines the timing for reproducing the content data based on the reproduction time information included in the content data stored in the ring buffer area. That is, the playback means is configured to output the content data stored in the ring buffer area to the built-in speaker 211 and the display 209 at the playback time.

  The reproduction by this reproduction means is performed by taking out the content data from the ring buffer area corresponding to the latest channel last selected by the channel selection button or the like and outputting it to the video chip 208 or the sound source chip 210.

(Display control means)
The display control means has a function of controlling the video chip 208 and the display 209 to display content data and various information. That is, the display control means can control how the content video and various types of information are displayed on the display 209.

(Content data playback status detection means)
The content data playback status detection means has a function of detecting the playback status of content data for each channel by the playback means.

  As described above, the content data reproduction state includes the number of reproductions and the reproduction time per unit time. Here, the description will be made assuming that the number of reproductions of content data for each channel is detected. Note that the number of times content data is reproduced is, in other words, the number of channel selections.

  By the way, depending on the user of the terminal device 2, the channel may be switched very frequently. In such a case, it is often not appropriate to detect the number of reproductions of content data as it is. Therefore, the content data reproduction status detection means does not include the channel that has been switched immediately in the number of reproductions. In other words, only those viewed for a predetermined period or longer are included in the count of the number of reproductions.

  When the content data playback status detection unit detects the playback status of the content data for each channel by the playback unit, the content data playback status detection unit registers and updates the playback status in the playback status history table provided in the first storage unit 202.

  Here, an example of the reproduction status history table is shown in FIG. In the example of this figure, the number of reproductions per day for each channel from channel ch1 to ch5 is stored from the current day to 30 days ago. In this example, the unit time is one day and is 30 minutes (30 days) before, but the unit time may be one hour or one week. Alternatively, a reproduction status history table for each day of the week may be used. In this case, the number of reproductions of each channel is stored in this table for each of Monday through Sunday.

(About ring buffer setting means)
The ring buffer setting unit has a function of setting a ring buffer area for each channel selected by the channel selection unit such as a channel selection button in the ring buffer settable area 226 of the first storage unit 202. Then, the ring buffer area information set in this way is registered as connection pool information in the connection pool information area (hereinafter referred to as “connection pool”) of the first storage unit 202.

  The buffer capacity of the ring buffer area is determined by the ring buffer setting means, and is set to a buffer capacity according to the reproduction status of the content data of the channel corresponding to the ring buffer area. That is, the ring buffer setting means calculates the buffer capacity corresponding to the channel reproduction status detected by the content data reproduction status detection means using a predetermined arithmetic expression or table, and allocates it to the ring buffer area of that channel.

  Here, the content data reproduction status refers to the number of times content data is reproduced per unit time and the reproduction time in each channel as described above. Here, description will be made assuming that the ring buffer area setting means allocates the buffer capacity calculated by the calculation method for weighting the number of reproductions of each channel to the ring buffer area.

  Hereinafter, a calculation method in the case where the number of entries in the connection pool is three and the evaluation section is three will be described as an example. Here, the “number of entries in the connection pool” means the number of ring buffer areas that can be set simultaneously in the ring buffer settable area 226.

  Here, the memory capacity of the ring buffer area that can be set in the first storage unit 202 is Sf, and SI and Sr are defined by the following equation (1).

  When SI and Sr are defined in this way, the buffer capacity of the ring buffer area of channel i is calculated as the buffer capacity according to the reproduction status by the following equation (2). Here, the selection probabilities Pch (i) _t1 to t3 in the respective evaluation sections 1 to 3 shown in FIG. 12 are derived from the reproduction status history table of FIG. The weights Wt1 to Wt3 are parameters adjusted so as to reduce the weights in the past evaluation sections.

  Each parameter is defined by the following formulas (3) and (4).

  In this way, the ring buffer setting means calculates the buffer capacity of the ring buffer area allocated to each channel by a calculation method in which the weight is increased as new playback is performed, and the buffer capacity of the ring buffer area is determined according to the channel playback status. Can be allocated efficiently.

  Further, when the ring buffer setting means connects to the connection destination candidate of the channel selected by the channel selection means by the connection means, the ring buffer area corresponding to the selected channel is first stored in the first storage unit 202. If it is determined that the number of ring buffer areas not existing in the section 202 and set in the ring buffer settable area 226 of the first storage section 202 has reached a predetermined number (upper limit), the plurality of ring buffer areas Among them, one ring buffer area is deleted from the first storage unit 202 and a ring buffer area corresponding to the selected channel is set in the first storage unit 202.

  For example, the ring buffer setting unit deletes the ring buffer area set in the first storage unit 202 from the first storage unit 202 and selects the ring buffer region having the longest period that has not been reproduced by the reproduction unit. A ring buffer area corresponding to the channel is set in the first storage unit 202.

(Relay request receiving means)
The relay request receiving unit receives a content data relay request from the terminal device 2 connected downstream. This content data relay request is made simultaneously or separately with a connection request from the terminal device 2 downstream of the terminal device 2 itself. That is, the connection request from the terminal device 2 downstream of the own terminal device 2 may also serve as a relay request for content data, and the content data relay request is received after establishing a connection (session) with the own terminal device 2 You may make it take the structure to do. Here, it is assumed that the connection request also serves as a relay request for the content data. The content data relay request includes channel designation information of content data to be relayed, and the relay request receiving means determines a channel to be relayed based on the channel designation information.

(Transfer means)
The transfer means takes out the content data temporarily stored in the ring buffer area and distributes the content data to the downstream terminal device 2 by streaming. In other words, the transfer means transfers the content data received by the streaming receiving means in a streaming format to the downstream terminal device that has made the relay request.

  Here, the transfer means determines the ring buffer area corresponding to the channel to be transferred based on the channel designation information received by the relay request receiving means. Then, the transfer means sequentially extracts the content data from the ring buffer area determined as described above and transfers it to the downstream terminal device 2.

(Buffer capacity notification means)
The buffer capacity notification means notifies the connection management apparatus 3 of the buffer capacity of each ring buffer area set in the ring buffer settable area 226 of the terminal device 2 at predetermined intervals. Here, the predetermined period may be one hour or one day, for example. Note that the predetermined period can be changed by the user's operation of the remote controller 205 or the like.

  In addition, when the buffer capacity notifying unit receives an inquiry about the buffer capacity of the ring buffer area in the own terminal apparatus 2 from another terminal apparatus 2, the buffer capacity notifying means determines the buffer capacity of the ring buffer area of the channel corresponding to this inquiry. The terminal device 2 is notified.

  Further, the buffer capacity notifying means is configured to provide a buffer for the ring buffer area when the ring buffer area is set by the ring buffer setting means or when the buffer capacity of the ring buffer area is updated and changed by the ring buffer setting means. The capacity is notified to the connection management device 3.

(Backup processing means)
When the backup processing unit detects that the power of the terminal device 2 is turned off, the backup processing unit sets the buffer capacity of the ring buffer area set in the ring buffer settable area 226 of the first storage unit 202 to the nonvolatile storage device. 2 When storing in the storage unit 203 and detecting that the power of the terminal device 2 is supplied again, the ring buffer area is stored in the first storage based on the buffer capacity of the ring buffer area set in the second storage unit 203. Set again in the section 202.

  Here, the detection of the power-off and the detection of the re-supply of power by the backup processing means are performed by monitoring the output voltage of the power circuit (not shown) of the terminal device 2 itself. That is, when the output voltage becomes smaller than a predetermined value, the power-off is detected, and when the output voltage becomes equal to or higher than the predetermined value, the power re-supply is detected.

(Buffer capacity acquisition means)
The buffer capacity acquisition means functions as upstream buffer capacity acquisition means for acquiring information on the buffer capacity of the ring buffer area of the terminal device 2 upstream of the terminal device 2 in each channel hierarchical structure connected by the connection means. . In other words, the buffer capacity acquisition means requests the buffer capacity information of the ring buffer area from the connection management apparatus 3 or the terminal apparatus 2 upstream of the terminal apparatus 2 as upstream buffer capacity acquisition means, and in response to the request, the buffer capacity acquisition means The buffer capacity of the ring buffer area transmitted from the terminal device 2 is acquired.

  The buffer capacity acquisition means acquires downstream buffer capacity acquisition means for acquiring information on the buffer capacity of the ring buffer area of the terminal device 2 downstream of the terminal device 2 in the hierarchical structure of each channel connected by the connection means. Function as. That is, the buffer capacity acquisition means requests the buffer capacity information of the ring buffer area from the connection management apparatus 3 or the terminal apparatus 2 downstream of the own terminal apparatus 2 as the downstream buffer capacity acquisition means, and downstream in response to the request. The buffer capacity of the ring buffer area transmitted from the terminal device 2 is acquired.

(Comparison means)
The comparison means compares the buffer capacity of the ring buffer area of the terminal device 2 with the buffer capacity of the ring buffer area of the upstream terminal apparatus acquired by the buffer capacity acquisition means for each channel. Further, the comparison means compares the buffer capacity of the ring buffer area of the terminal device 2 with the buffer capacity of the ring buffer area of the downstream terminal apparatus acquired by the buffer capacity acquisition means for each channel.

  In addition, when there are a plurality of terminal devices downstream, the comparison means compares the buffer capacity with respect to each downstream terminal device 2.

(Reconnection method)
As a result of the comparison by the comparison means, the reconnection means determines that the buffer capacity of the ring buffer area possessed by the terminal apparatus 2 is larger than the buffer capacity of the ring buffer area possessed by the terminal apparatus located upstream. Reconnection processing is performed so as to reconnect to the upstream terminal device 2 on the hierarchical structure.

  Further, the reconnection means determines that the downstream terminal apparatus when the buffer capacity of the ring buffer area of the terminal apparatus 2 is smaller than the buffer capacity of the ring buffer area of the downstream terminal apparatus as a result of the comparison by the comparison means. 2 or the downstream terminal device 2 is reconnected so as to reconnect to the downstream terminal device 2 in the hierarchical structure.

  As a result of the comparison by the comparison means, the reconnection means has a large buffer capacity of the ring buffer area of the terminal apparatus 2 upstream of the ring buffer area of the own terminal apparatus 2 and the own terminal apparatus 2 When the buffer capacity of the ring buffer area possessed by the terminal apparatus 2 downstream is small, the reconnection to the upstream terminal apparatus 2 is prioritized over the upstream terminal apparatus 2.

[4. Description of Configuration of Connection Management Device 3]
Next, the configuration and operation of the connection management device 3 will be described with reference to FIG.

  FIG. 13 is a diagram illustrating a schematic configuration example of the connection management device 3 according to the first embodiment. As the connection management device 3, a general server computer can be applied. As shown in FIG. 13, a CPU (Central Processing Unit) 301 and a rewritable main storage device that stores (stores) various programs and the like. Communication is performed between the content storage device 1 and the terminal device 2 via the Internet 4 and the second storage unit 303 configured by a 1 storage unit 302, an HDD (Hard Disc Drive) that stores various data, and the like. The network interface 304, a peripheral device control chip 307 that controls input means such as a keyboard 305 and a mouse 306 capable of inputting predetermined information, and image data from the CPU 301 are received and written to an internal video memory (not shown). A video chip for displaying data written in the video memory on a display 309 to be described later Is constituted by a 08, these various components are mutually connected via a system bus 310.

  In the first embodiment, the CPU 301 and the first storage unit 302 constitute the control unit 315. The network interface 304 is connected to the Internet 4 via the router 10c.

(Regarding the first storage unit 302)
The first storage unit 302 also includes an OS program 320 for providing basic functions of the connection management device 3 as a computer, and location information (IP addresses and ports) of a plurality of terminal devices 2 connected to the channel. Corresponding to a connection destination introduction request transmitted from the terminal device 2 and a terminal management program 321 for managing a tree-like hierarchical structure of each channel, a topology management program 322 for managing and managing a tree-like hierarchical structure of each channel, and the like. A channel connection destination candidate is selected, and a connection destination introduction program 323 for transmitting connection destination candidate information to the terminal device 2 and an operation management program 324 for managing the operation of the content distribution system S are stored. These are read by the CPU 301 and the CPU 301 follows these programs. Function is executed.

  Here, the OS program 320 is read and executed by the CPU 301, thereby connecting functions such as functions relating to input / output of the keyboard 305 and the mouse 306 and memory management such as the first storage unit 302 and the second storage unit 303. The basic function of the computer which is the management apparatus 3 is made executable. Then, in a state where the OS program 320 is executed by the CPU 301, the above-described terminal management program 321, topology management program 322, connection destination introduction program 323, operation management program 324, and the like are executed.

  The OS program 320, the terminal management program 321, the topology management program 322, the connection destination introduction program 323, the operation management program 324, etc. are downloaded to the first storage unit 302 from, for example, a server connected to the Internet 4. Alternatively, it may be recorded on a storage medium such as a CD-ROM and then read into the first storage unit 302 via a drive of the storage medium.

(About the control unit 315)
The control unit 315 includes the CPU 301 and the first storage unit 302 as described above, and the CPU 301 reads out and executes the various programs 320 to 324 stored in the first storage unit 302, whereby the connection management apparatus 3 as a whole. Are controlled as a connection destination candidate selection unit, a notification unit, a topology management unit, a terminal management unit, etc., and the first storage unit 302 is used as a connection state information storage unit.

  It should be noted that the CPU 301 executes the terminal management program 321 as a terminal management unit or the like, and the CPU 301 executes the topology management program 322 as a topology management unit or the like, and further the CPU 301 executes the connection destination introduction program 323. Respectively function as buffer capacity reception means, connection destination candidate selection means, notification means, and the like.

(About terminal management means)
When receiving the registration request from the terminal device 2, the terminal management means registers the IP address, which is the location information of the terminal device 2, in the terminal management database 314 for each channel. In addition, when a registration request is received from the content distribution apparatus 1, the location information of the content distribution apparatus 1 is registered in the terminal management database 314 for each channel. The location information of the terminal device 2 is included in the registration request from the terminal device 2, and the location information is acquired from the registration request.

(About topology management means)
The topology management means includes a new topology generation means for generating a tree-like hierarchical structure of a new channel based on a new channel generation request transmitted from the content distribution apparatus 1, and a connection destination introduction request or connection disconnection of the terminal device 2. It has a function as topology change means for changing connection information of the terminal device 2 in the channel by topology change notification such as notification. Further, the topology management means stores the connection status information of the terminal device 2 constituting the hierarchical structure for each channel in the topology database 313 as the connection status information storage means.

  When receiving a new channel generation request from the content distribution apparatus 1, the new topology generation means generates a new channel topology table and registers it in the topology database 313. Here, the topology table is a table for storing connection state information and the like of the terminal device 2 constituting a hierarchical structure for each channel, and is generated for each channel and registered in the topology database 313.

  The topology changing means executes a function of adding or deleting information of the terminal device 2 to / from a plurality of topology tables stored in the topology database 313. Based on the connection destination introduction request topology participation report from the terminal device 2 Addition or change to the topology table.

  Here, the topology table in the topology database 313 will be specifically described with reference to FIG.

  As shown in FIG. 14, the topology table has the terminal number of each terminal device 2 (for example, the MAC address of the terminal device 2) as a main item, the terminal device in the upstream node for each terminal device 2, the downstream Is a table in which terminal devices in each node, location information, and buffer capacity of the ring buffer area are associated with each other, and this topology table is provided for each channel.

  Here, the terminal number, location information, and buffer capacity of the ring buffer area of the terminal device 2 are registered in the topology table based on information included in the connection destination introduction request.

  That is, the topology changing means receives the buffer capacity, terminal number, and location information of the ring buffer area for each channel transmitted from each terminal apparatus 2 and registers them in the terminal management database 314.

(About buffer capacity receiving means)
The buffer capacity receiving means receives a connection destination introduction request including the buffer capacity of the ring buffer area from the terminal device 2 that is about to newly join the channel. In addition, the buffer capacity of the ring buffer area is periodically received from the terminal devices 2 participating in the channel.

(About connection destination candidate selection means)
When the connection destination candidate selection means receives a connection destination introduction request including the buffer capacity of the ring buffer area from a terminal device that is newly joining or reconnecting to the channel, the hierarchical structure of the channel corresponding to the connection destination introduction request Connection state information stored in the topology database 313 for connection destination candidates for connection destination introduction requests so that the buffer capacity of the ring buffer area of the terminal device constituting the hierarchical structure decreases from upstream to downstream of the hierarchical structure. Select from.

  That is, the connection destination candidate selection means is a terminal downstream of a terminal device having a ring buffer area having a buffer capacity larger than the buffer capacity of the ring buffer area of the terminal apparatus 2 that has made a connection destination introduction request, and that has made a connection destination introduction request. The terminal device 2 upstream of the terminal device having a ring buffer area with a buffer capacity smaller than the buffer capacity of the ring buffer area of the apparatus 2 is selected as a connection destination candidate.

(Notification means)
The notifying unit has a function of notifying the connection destination candidate selected by the connection destination candidate selecting unit to the terminal device 2 that has transmitted the connection destination introduction request. The notification of the connection destination candidate includes information on the connection destination candidate, that is, information such as the communication protocol, IP address, and port number of the connection destination candidate terminal device 2.

[5. Operation of content distribution system S]
Hereinafter, detailed operations of the terminal device 2 and the connection management device 3 will be described more specifically with reference to flowcharts.

(Description of processing flow of terminal device 2)
First, a more specific operation of the terminal device 2 will be described with reference to FIGS. 15 is a flowchart showing the entire processing in the terminal device 2, FIG. 16 is a flowchart showing channel switching processing in the terminal device 2, and FIG. 17 is a flowchart showing connection change processing in the terminal device 2.

  First, with reference to FIG. 15, an overview of the entire processing in the terminal device 2 will be described.

  First, when the terminal device 2 is powered on, the programs 220 to 225 are initialized in the terminal device 2, the programs 220 to 225 are executed by the CPU 201, and the function as the control unit 213 is operated. . When the control unit 213 is in the operating state in this way, a connection introduction request is made to the connection management device 3 together with a registration request for the own terminal device 2 (step S100). That is, the control unit 213 includes location information (IP address, port number, etc.) of the terminal device 2, a channel predetermined in the initial setting (hereinafter referred to as “initial setting channel”), and a ring buffer area of this channel. Information such as the buffer capacity is transmitted to the connection management device 3.

  When receiving the registration request and the connection destination introduction request from the terminal device 2, the connection management device 3 registers the information received from the terminal device 2 that has made the registration request and the connection destination introduction request in the topology database 313 and the terminal management database 314. . Thereafter, the connection management device 3 selects connection destination candidates in the initial setting channel based on the information in the topology database 313, and notifies the selected connection destination candidates to the terminal device 2 that has made the connection destination introduction request.

  After transmitting the registration request and the connection destination introduction request to the connection management device 3, the control unit 213 of the terminal device 2 receives the connection destination candidate notified from the connection management device 3. A connection with the content distribution device 1) is established. The control unit 213 of the terminal device 2 sets the ring buffer area for the initial setting channel in the first storage unit 202 in order to receive the content data of the initial setting channel from the connection destination candidate that has established the connection in this way. .

  When the content packet of the initial setting channel is streamed from the connection destination candidate, the control unit 213 of the terminal device 2 extracts the content data from the content packet and sequentially stores it in the ring buffer area for the initial setting channel. .

  The control unit 213 of the terminal device 2 checks the reproduction time information included in the content data stored in the ring buffer area for the initial setting channel, takes out the content data at the reproduction time from the ring buffer area, and Playback is started using 209 or the built-in speaker 211. Note that the process of receiving and reproducing the content packet of the initial setting channel may be performed in steps S150 and S151 described below.

  Thereafter, the control unit 213 of the terminal device 2 determines whether or not a channel switching request has been made (step S101). That is, it is determined whether or not a channel different from the currently reproduced channel has been selected by the operation of the channel selection button provided on the remote controller 205 by the user.

  If it is determined in step S101 that a channel switching request has been made (step S101: YES), the control unit 213 performs channel switching processing in step S110. The channel switching process in step S110 will be described in detail later.

  If it is determined in step S101 that a channel switching request has not been made (step S101: NO), the control unit 213 determines whether or not the ring buffer area is being updated (step S102).

  The update trigger of the ring buffer area is set in the update trigger storage area of the first storage unit 202 so as to be an update trigger at regular intervals (for example, every 30 minutes). You may make it the structure which can change the information of the update opportunity set in this update opportunity storage area. The control unit 213 refers to the update opportunity storage area and determines whether it is an update opportunity of the ring buffer area.

  As described above, when the calculation of the buffer capacity according to the reproduction status is performed based on the number of reproductions by date, it means that the number of reproductions as a calculation source is changed by changing the date. In the example shown in FIG. 11, when the date changes, the data 30 days before is rewritten to the data 29 days ago. For this reason, when the reproduction status based on the number of reproductions in date units is detected in this way, the time when the date changes is used as an update trigger for the ring buffer area.

  If it is determined in step S102 that the ring buffer area is being updated (step S102: YES), the control unit 213 recalculates the buffer capacity allocated to the ring buffer area being pooled according to the playback status, The buffer capacity of the ring buffer area is set so that the buffer capacity according to the result is obtained (step S120).

  Here, the ring buffer area being pooled is a ring buffer area (hereinafter referred to as “standby channel”) of a non-reproducing channel (hereinafter referred to as “standby channel”) among the channels that have established connections (pool connections). "Ring buffer (3)").

  Thereafter, the control unit 213 reports the buffer capacity of the ring buffer (3) to the connection management apparatus 3 by transmitting the buffer capacity of the ring buffer (3) to the connection management apparatus 3 (step S121).

  If it is determined in step S102 that the ring buffer area is not updated (step S102: NO), the control unit 213 determines whether or not it is an inquiry about the buffer capacity of the ring buffer area being pooled. Is determined (step S103).

  The buffer capacity inquiry trigger of the ring buffer (3) is set in the inquiry trigger storage area of the first storage unit 202 in advance so as to be an inquiry trigger at regular intervals (for example, every 30 minutes). A configuration may be adopted in which information on the inquiry trigger set in the inquiry trigger storage area can be changed by operating the remote controller 205. The control unit 213 refers to the inquiry trigger storage area and determines whether it is an inquiry trigger for the buffer capacity of the ring buffer area.

  If it is determined in step S103 that the buffer capacity of the ring buffer (3) being pooled is inquired (step S103: YES), the control unit 213 performs a connection change process in S130. The connection change process in step S130 will be described in detail later.

  If it is determined in step S103 that the buffer capacity of the ring buffer (3) being pooled is not triggered (step S103: NO), the control unit 213 determines the buffer capacity of the ring buffer area of the terminal device 2 itself. It is determined whether or not the inquiry is from another terminal device 2 (step S104).

  If it is determined in step S104 that there is an inquiry about the buffer capacity of the ring buffer area (step S104: YES), the control unit 213 inquires about the buffer capacity of the ring buffer area of the terminal device 2 related to the channel related to the inquiry request. Is notified to the other terminal device 2 that has performed (step S140).

  If it is determined in step S104 that there is no inquiry about the buffer capacity of the ring buffer area (step S104: NO), the control unit 213 has received a content packet from an upstream device in the hierarchical structure of the connected channel. Is determined (step S105).

  As described above, the content packet is received by sequentially accumulating in the ring buffer area prepared for the channel corresponding to the received content packet. That is, the content packet corresponding to each of the ring buffer areas set for each channel to which the terminal device 2 is connected is stored. Note that content data included in the content packet is stored in the ring buffer area, and is information obtained by removing the header portion of the content packet.

  If it is determined in step S105 that the content packet has been received from the upstream device (step S105: YES), the control unit 213 transfers the received content packet to the downstream terminal device 2 (step S150). If there is no downstream terminal device 2 that transfers the received content packet, the process of S150 is not performed.

  The transfer to the downstream apparatus is performed for each channel, and is performed by extracting the content data from the corresponding ring buffer area and transmitting it as a content packet.

  In addition, the control unit 213 acquires content data that has reached the playback time from the ring buffer area from the ring buffer area and plays it. The content data to be played back is the content data of the channel selected to be played back by the remote controller 205 or the like when a plurality of ring buffer areas are set in the ring buffer settable area 226 of the first storage unit 202. Then, data is sequentially extracted from the ring buffer area of the channel selected for reproduction from the plurality of ring buffer areas and reproduced (step S151).

  When the processes of steps S110, S121, S130, S140, and S151 are completed, or when it is determined in step S105 that a content packet has not been received from an upstream device (step S105: NO), the control unit 213 automatically It is determined whether or not the terminal device 2 is turned off (step S160). If it is determined that the power of the terminal device 2 is not turned off (S160: NO), the processing from step S101 is repeated, and if it is determined that the power of the terminal device 2 is turned off (S160: YES), the processing is terminated. To do.

  Next, the channel switching process in S110 will be specifically described with reference to FIG.

  First, the control unit 213 changes the state of the buffer capacity of the ring buffer area of the channel being played back (here, this ring buffer area is referred to as “ring buffer (1)”) to the non-playback state, that is, the standby state. (Step S200).

  Next, the control unit 213 determines whether information regarding the requested switching destination channel (hereinafter referred to as “request channel”) exists in the connection pool. That is, it is determined whether there is information regarding the requested channel in the connection pool information area of the first storage unit 202. In other words, the control unit 213 determines whether or not the ring buffer area corresponding to the requested request channel exists in the ring buffer settable area 226 of the first storage unit 202 (step S201).

  If it is determined in step S201 that information related to the requested channel exists in the connection pool (step S201: YES), the control unit 213 determines a ring buffer area for the requested channel (hereinafter referred to as “ring buffer (2)”). The buffer capacity is calculated according to the reproduction status, and the buffer capacity of the ring buffer (2) set in the first storage unit 202 is updated based on the result (step S202).

  Next, the control unit 213 updates the selection time of the ring buffer (2) related to the requested channel. That is, the selection time of the ring buffer (2) is registered in the above-described reproduction status history table, and the reproduction status history table is updated (step S203).

  If it is determined in step S201 that information related to the requested channel does not exist in the connection pool (step S201: NO), the control unit 213 calculates the buffer capacity of the ring buffer (2) for the requested channel according to the reproduction status ( Step S204). That is, the ring buffer (2) related to the requested channel is set in the first storage unit 202 so that the buffer capacity becomes the buffer capacity calculated according to the reproduction status (step S205). Thereafter, the control unit 213 registers the ring buffer (2) in the connection pool (step S205).

  Next, the control unit 213 determines whether or not the number of registered connection pools, that is, the number of ring buffer areas set in the first storage unit 202 has reached a predetermined upper limit value (step S206).

  If it is determined in step S206 that the number of registered connection pools has reached the upper limit (step S206: YES), the control unit 213 deletes the oldest registration information in the connection pool (step S207). Here, the “oldest registration information in the connection pool” includes the oldest registration information in the connection pool and the period of the registration information in the connection pool that has not been reproduced. There are long registration information and registration information that has been reproduced the oldest among the registration information in the connection pool. Hereinafter, “the oldest registration information in the connection pool” will be described as the oldest registration information among the registration information in the connection pool. When already connected to the requested channel, since the ring buffer area corresponding to the requested channel is set in the first storage unit 202, the processing of step S208 is not performed without performing the processing of steps S206 and S207. Transition. That is, when there is no ring buffer area corresponding to the requested channel, the processes in steps S206 and S207 are performed.

  Here, the deletion of the registration information in step S207 means withdrawal from the channel hierarchical structure corresponding to the registration information to be deleted and deletion of the corresponding ring buffer area from the first storage unit 202. That is, the control unit 213 stops receiving the content data regarding the channel corresponding to the registration information to be deleted, withdraws from the hierarchical structure of this channel, and further sets the ring buffer area corresponding to the channel to leave in the first manner. It is deleted from the storage unit 202.

  When it is determined in step S206 that the number of registered connection pools has not reached the upper limit (step S206: NO), or when the process of step S207 is completed, the control unit 213 requests the requested channel for which a switching request has been made. In order to connect to the connection management device 3, the connection management device 3 is requested to notify the connection destination candidate.

  Further, the control unit 213 notifies the connection management apparatus of the buffer capacity of the ring buffer area set for the requested channel, in addition to the connection destination introduction request including the requested channel information. Thereafter, the control unit 213 receives a connection destination candidate notified from the connection management device 3 (step S208).

  Next, the control unit 213 requests connection to an upstream device that is a connection destination candidate received from the connection management device 3 in step S208. Thereafter, the connection with the connection destination candidate is established. This participates in the hierarchical structure (topology) of the requested channel (step S209).

  When the connection with the connection destination candidate is established in this way, the control unit 213 notifies the connection management device 3 of participation in the hierarchical structure of the requested channel, that is, a topology participation report (step S210). This topology participation report includes the buffer capacity of the ring buffer (2) set for the request channel in addition to the location information of the terminal device 2 itself.

  Thereafter, the control unit 213 sets the ring buffer (2) for the requested channel to be reproducible (step S211). If the ring buffer (2) is already set in the first storage unit 202 when already connected to the requested channel, the processing in steps S208 to S211 is not performed.

  Thereafter, the control unit 213 receives the content data from the connected connection destination candidates and sequentially accumulates them in the ring buffer (2), and sequentially reproduces the content data according to the reproduction time of the accumulated content data.

  Next, the control unit 213 increments the channel selection count for the ring buffer (2) of the reproduction status history table by 1, and updates the reproduction status history table (step S212). When the process of step S212 is finished, the channel switching process of S110 is finished.

  As described above, in the channel switching process, when the switching destination channel is a channel that is not managed in the connection pool (that is, a channel that is not connected and does not have a corresponding ring buffer area), the channel that is managed in the connection pool Since the oldest registration information in the connection pool is deleted by the control unit 213 when the number of registrations is the upper limit of the predetermined number, the ring buffer settable area 226 does not expand without limit, In addition, the ring buffer area can be used efficiently because the connection of the channels that are less likely to be used is disconnected.

  Next, the connection change process in S130 will be specifically described with reference to FIG.

  First, the control unit 213 acquires information on the buffer capacity of the ring buffer area of the terminal device 2 upstream of the own terminal device 2 for each standby channel (step S300). The acquisition of the buffer capacity takes a form in which the control unit 213 receives a notification from the upstream terminal device 2 by making an inquiry to the upstream terminal device 2.

  Next, the control unit 213 determines whether or not the buffer capacity of the ring buffer (3) of the standby channel is larger than the buffer capacity of the ring buffer area of the upstream terminal device 2 (step S301).

  If it is determined in step S301 that the buffer capacity of the ring buffer (3) of the standby channel is larger than the buffer capacity of the ring buffer area of the upstream terminal device 2 (step S301: YES), the control unit 213 determines the standby channel. Is sent to the connection management device 3. At this time, the control unit 213 also transmits the buffer capacity of the ring buffer (3) to the connection management device 3 (step S302).

  Thereafter, the control unit 213 requests connection to an upstream device that is a connection destination candidate received from the connection management device 3. Thereafter, the connection with the connection destination candidate is established. This rejoins the channel hierarchy (topology) (step S303).

  When the connection with the connection destination candidate is established in this way, the control unit 213 notifies the connection management device 3 of the participation in the hierarchical structure of the requested channel, that is, the topology participation report (step S304). This topology participation report includes the buffer capacity of the ring buffer (3) in addition to the location information of the terminal device 2 itself.

  After the process of step S304 is completed, or when it is determined in step S301 that the buffer capacity of the ring buffer (3) of the standby channel is not larger than the buffer capacity of the ring buffer area of the upstream terminal device 2 (step S301: NO), the process of the next step S305 is performed.

  That is, the control unit 213 acquires information on the buffer capacity of the ring buffer area of the terminal device 2 downstream of the terminal device 2 for each connected channel (step S305). The acquisition of the buffer capacity takes a form in which the control unit 213 receives a notification from the downstream terminal device 2 by making an inquiry to the downstream terminal device 2.

  Next, the control unit 213 determines whether or not the buffer capacity of the ring buffer (3) of the standby channel is smaller than the buffer capacity of the ring buffer area of the terminal device 2 downstream of the terminal device 2 in the standby channel. Determination is made (step S306).

  When it is determined that the buffer capacity of the ring buffer (3) is smaller than the buffer capacity of the ring buffer area of the downstream terminal device 2 (step S306: YES), the control unit 213 introduces the connection destination for this standby channel. The request is transmitted to the connection management device 3. At this time, the control unit 213 also transmits the buffer capacity of the ring buffer (3) to the connection management device 3 (step S307).

  Thereafter, when the connection destination candidate notified from the connection management device 3 is received, the control unit 213 requests connection to the upstream device that is the connection destination candidate received from the connection management device 3 in step S307. Thereafter, the connection with the connection destination candidate is established. This rejoins the hierarchical structure (topology) (step S308).

  When the connection with the connection destination candidate is established in this way, the control unit 213 notifies the connection management device 3 of participation in the hierarchical structure of the requested channel, that is, a topology participation report (step S309). This topology participation report includes the buffer capacity of the ring buffer (3) in addition to the location information of the terminal device 2 itself.

  After the process of step S309 is completed, or when it is determined in step S306 that the buffer capacity of the ring buffer (3) of the standby channel is not smaller than the buffer capacity of the ring buffer area of the downstream terminal device 2 (step S306). : NO), this connection change process is terminated.

  As described above, in the connection change process, when the buffer capacity of the ring buffer (3) of the standby channel is larger than the buffer capacity of the ring buffer area of the upstream terminal apparatus 2 in the standby channel, the local terminal apparatus 2 is Further, reconnection to the upstream terminal device 2 is performed. That is, the hierarchical structure is dynamically changed from the upstream to the downstream of the hierarchical structure so that the buffer capacity of the ring buffer area of the terminal device 2 constituting the hierarchical structure becomes smaller.

  Similarly, when the buffer capacity of the ring buffer (3) of the standby channel is smaller than the buffer capacity of the ring buffer area of the downstream terminal device 2 in the standby channel, the own terminal device 2 is reassigned to the downstream terminal device 2 again. Connecting. That is, the hierarchical structure is dynamically changed from the upstream to the downstream of the hierarchical structure so that the buffer capacity of the ring buffer area of the terminal device 2 constituting the hierarchical structure becomes smaller.

  As described above, in the first embodiment, the hierarchical structure is dynamically changed so that the buffer capacity of the ring buffer area of the terminal device 2 configuring the hierarchical structure decreases from the upstream to the downstream of the hierarchical structure. The loss packet complementing process can be appropriately performed while improving the use efficiency of the ring buffer area set in each device.

  In the terminal device 2, the ring buffer area update trigger and the ring buffer capacity query trigger have been described as one trigger, but the present invention is not limited to this. For example, a ring buffer area update opportunity or a ring buffer capacity inquiry opportunity may be provided for each channel, and in this way, the ring buffer area can be updated more appropriately for the use environment.

(Description of processing flow of connection management device 3)
Next, a more specific operation of the connection management device 3 will be described with reference to FIG. FIG. 18 is a flowchart showing the entire processing in the connection management device 3.

  When the power of the connection management device 3 is turned on, the connection management device 3 initializes the programs 320 to 324, puts the programs 320 to 324 into an execution state by the CPU 301, and operates the function as the control unit 315 ( Step S400).

  First, the control unit 315 determines whether or not a request to join a channel has been received from the terminal device 2 (step S401).

  If it is determined in step S401 that a request for participation in the channel has been received from the terminal device 2 (step S401: YES), the control unit 315 transmits the location information of the terminal device 2 included in the received participation request to the terminal management database 314. Registration is performed (step S405).

  On the other hand, if it is determined in step S401 that a request to join a channel has not been received from the terminal device 2 (step S401: NO), the control unit 315 determines whether or not a registration request from the content distribution device 1 has been received. Determination is made (step S402).

  If it is determined in step S402 that a registration request from the content distribution apparatus 1 has been received (step S402: YES), the control unit 315 sends the location information of the content distribution apparatus 1 included in the received registration request to the terminal management database 314. Register (step S406).

  Next, the control unit 315 registers new channel information in the topology database 313. That is, a topology table for a new channel is generated in the topology database 313 (step S407).

  If it is determined in step S402 that the registration request from the content distribution device 1 has not been received (step S402: NO), the control unit 315 determines whether or not a connection destination introduction request has been received from the terminal device 2 (step S402: NO). Step S403).

  If it is determined in step S403 that a connection destination introduction request has been received from the terminal device 2 (step S403: YES), the control unit 315 selects a terminal device 2 that is a connection destination candidate from the topology database 313 (step S408).

  Here, selection of connection destination candidates is performed as follows. That is, the control unit 315 includes information on the connection destination channel included in the connection destination introduction request transmitted from the terminal device 2 and the buffer capacity of the ring buffer area allocated for the connection destination channel by the terminal device 2 (hereinafter, “ "Notification buffer capacity")). Then, the topology table of this connection destination channel is extracted from the topology database 313, and based on the notification buffer capacity, among the terminal devices 2 registered in this topology table, from the upstream to the downstream of the hierarchical structure in the connection destination channel, A terminal device 2 suitable for a hierarchical structure in which the buffer capacity of the ring buffer area of the terminal device 2 constituting the hierarchical structure is gradually reduced is selected as a connection destination candidate.

  The control unit 315 of the connection management device 3 sends back and notifies the selected connection destination candidate to the terminal device 2 that has made the connection destination introduction request (step S409).

  Further, the control unit 315 registers the notification buffer capacity in the topology database 313 together with the location information of the terminal device 2 that has notified the connection destination candidate in step S409 (step S410).

  If it is determined in step S403 that a connection destination introduction request has not been received from the terminal device 2 (step S403: NO), the control unit 315 determines whether a topology participation report has been received from the terminal device 2 (step S404). .

  If it is determined in step S404 that there has been a topology participation report from the terminal device 2 (step S404: YES), the control unit 315 extracts the location information and notification buffer capacity of the terminal device included in this topology participation report, and the topology database. Update processing of 313 is performed (step S411). That is, the control unit 315 registers the topology change in the topology database 313.

  When it is determined in step S404 that there is no topology participation report from the terminal device 2 (step S404: NO), the control unit 315 determines whether there is a report of the buffer capacity of the ring buffer area from the terminal device 2 (step S405). ).

  If it is determined in step S405 that the terminal device 2 has reported the buffer capacity of the ring buffer area (step S405: YES), the control unit 315 provides information corresponding to the terminal apparatus 2 that has reported the buffer capacity of the ring buffer area. Then, it is registered in the topology database 313 (step S412). That is, the topology table of the topology database 313 is updated according to the ring buffer capacity notification from the terminal device 2.

  When the processes of steps S405, S407, S410, S411, and S412 are completed, or when it is determined in step S405 that there is no report of the buffer capacity of the ring buffer area from the terminal device 2 (step S405: NO), the control unit 315 Then, it is determined whether or not an operation for terminating the service of the connection management apparatus 3 has been performed (step S413). If it is determined that the service termination operation has not been performed (S413: NO), the processing from step S401 is repeated, and if it is determined that the service termination operation of the connection management device 3 has been performed (S413: YES), the processing is terminated. To do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment, the reconnection operation in the terminal device 2 is performed without depending on the connection management device 3. In the second embodiment, only portions different from the first embodiment will be described, and description of other similar portions will be omitted.

  The terminal device 2 of the second embodiment performs the reconnection operation without depending on the connection management device 3, and only the connection change processing operation in the first embodiment is different. A description will be given with reference to FIG.

  As illustrated in FIG. 19, the terminal device 2 stores information of other neighboring terminal devices 2 within a predetermined number of hops in the neighboring terminal information storage area in the first storage unit 202, and based on this information The reconnection process is performed.

  Here, the predetermined number of hops is 2 hops or 3 hops, for example. The number of hops means the number of routers that pass until a packet transmitted by the terminal device 2 is received.

  Further, the location information is included in the information of the other terminal device 2, and the reconnection process is performed without depending on the connection management device 3 based on the information.

  Hereinafter, the connection change process in the second embodiment will be described in detail with reference to the flowchart of FIG.

  First, the control unit 213 acquires information on the buffer capacity of the ring buffer area of the terminal device 2 upstream of the own terminal device 2 for each standby channel (step S500). The acquisition of the buffer capacity takes a form in which the control unit 213 receives a notification from the upstream terminal device 2 by making an inquiry to the upstream terminal device 2.

  First, the control unit 213 determines whether or not the buffer capacity of the ring buffer (3) of the standby channel is larger than the buffer capacity of the ring buffer area of the upstream terminal device 2 (step S501).

  If it is determined in step S501 that the buffer capacity of the ring buffer (3) of the standby channel is larger than the buffer capacity of the ring buffer area of the upstream terminal device 2 (step S501: YES), the control unit 213 determines neighboring terminal information. Based on the information of the neighboring terminal device 2 stored in the storage area, the upstream device (upstream node) of the terminal device that is currently the upstream device of the own terminal device 2 is selected. That is, a terminal device that can raise the connection position of the terminal device 2 in the hierarchical structure to the upper level is selected. Then, the terminal device 2 selected in this way is requested to establish a connection with the terminal device 2. Thereby, the participation position of the hierarchical structure (topology) of the channel being reproduced is autonomously changed (step S502).

  When the connection with the connection destination candidate is established in this way, the control unit 213 notifies the connection management device 3 that it has participated in the hierarchical structure of the requested channel, that is, a topology participation report (step S503). This topology participation report includes the buffer capacity of the ring buffer (3) in addition to the location information of the terminal device 2 itself.

  After the processing of step S503 is completed or when it is determined in step S501 that the buffer capacity of the ring buffer (3) of the standby channel is not larger than the buffer capacity of the ring buffer of the upstream terminal device 2 (step S501: NO) ), The next step S504 is performed.

  That is, the control unit 213 acquires information on the buffer capacity of the ring buffer area of the terminal device 2 downstream of the terminal device 2 for each connected channel (step S504). The acquisition of the buffer capacity takes a form in which the control unit 213 receives a notification from the downstream terminal device 2 by making an inquiry to the downstream terminal device 2.

  Next, in step S505, the control unit 213 has a buffer capacity of the ring buffer (3) of the standby channel smaller than the buffer capacity of the ring buffer area of the terminal device 2 downstream of the own terminal device 2 in this standby channel. It is determined whether or not.

  If it is determined that the buffer capacity of the ring buffer (3) is smaller than the buffer capacity of the ring buffer area of the downstream terminal device 2 (step S505: YES), the control unit 213 stores the neighborhood stored in the neighboring terminal information storage area The terminal device that is currently the downstream device of the terminal device 2 is selected based on the information of the terminal device 2. That is, a terminal device that can lower the connection position of the terminal device 2 in the hierarchical structure to a lower level is selected. Then, the terminal device 2 selected in this way is requested to establish a connection with the terminal device 2. Thereby, the participation position of the hierarchical structure (topology) of the channel being reproduced is autonomously changed (step S506).

  When the connection with the connection destination candidate is established in this way, the control unit 213 notifies the connection management device 3 of a topology participation report (step S507). This topology participation report includes the buffer capacity of the ring buffer (3) in addition to the location information of the terminal device 2 itself.

  After the processing of step S507 is completed, or when it is determined in step S505 that the buffer capacity of the ring buffer (3) of the standby channel is not smaller than the buffer capacity of the ring buffer of the downstream terminal device 2 (step S505: NO), this connection change process is terminated.

  As described above, the terminal device 2 autonomously constructs a hierarchical structure for each channel so that the buffer capacity of the ring buffer of the terminal device 2 constituting the hierarchical structure is reduced from the upstream to the downstream of the hierarchical structure. I am doing so.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the knowledge of those skilled in the art including the aspects described in the above [Disclosure of the Invention] section. It is possible to implement the present invention in other forms in which various modifications and improvements are made based on the above.

It is a figure showing the example of outline composition of content distribution system S concerning a 1st embodiment. It is the figure which represented notionally the function of the ring buffer area | region in the terminal device of FIG. It is a figure for demonstrating the distribution method of the buffer capacity | capacitance of a ring buffer area | region. It is a figure for demonstrating the distribution method of the buffer capacity | capacitance of a ring buffer area | region. It is a figure for demonstrating the distribution method of the buffer capacity | capacitance of a ring buffer area | region. It is explanatory drawing about the pre-buffering of the apparatus in a hierarchy. It is a figure which shows the participating operation to the predetermined channel in a terminal device. It is a figure which shows the reconnection operation | movement in a terminal device. It is a figure which shows the example of schematic structure of the content delivery apparatus of FIG. It is a figure which shows the schematic structural example of the terminal device of FIG. It is a figure which shows the example of the reproduction | regeneration status log | history table of the terminal device of FIG. It is explanatory drawing of the detection operation of the reproduction | regeneration condition of the terminal device of FIG. It is a figure which shows the example of schematic structure of the connection management apparatus of FIG. It is a figure which shows the content of the topology database of FIG. It is a flowchart which shows the whole process in a terminal device. It is a flowchart which shows the channel switching process in a terminal device. It is a flowchart which shows the connection change process in a terminal device. It is a flowchart which shows the whole process in a connection management apparatus. It is a figure which shows the reconnection process operation | movement in 2nd Embodiment. It is a flowchart which shows the connection change process in the terminal device of 2nd Embodiment.

Explanation of symbols

S Content Distribution System 1 Content Distribution Device 2 Terminal Device 3 Connection Management Device 213 Terminal Device Control Unit 226 Terminal Device Ring Buffer Settable Area 313 Connection Management Device Topology Database 315 Connection Management Device Control Unit

Claims (20)

One or more content distribution devices that stream-distribute content data on a plurality of channels, a plurality of terminal devices that receive and reproduce the content data, and a plurality of terminal devices that have the content distribution device as a vertex for each channel A connection management device that manages the logical connection in multiple layers in a structure, and the content data streamed from the content distribution device is sequentially downstream of the hierarchical structure by the relay function of the terminal device for each channel In the content data distribution system that is relayed to and can reproduce the content data by the plurality of terminal devices,
The content distribution device includes:
A distribution means for distributing the content data;
The connection management device includes:
Connection state information storage means for storing connection state information of the terminal device constituting the hierarchical structure for each channel;
When a connection destination introduction request is received from the terminal device, the connection destination candidate selection unit that selects a connection destination candidate from the connection state information stored in the connection state information storage unit and the connection destination candidate selection unit are selected. Notification means for notifying the connection destination candidate to the terminal device that has transmitted the connection destination introduction request,
The terminal device
Storage means;
Channel selection means for selecting the channel;
A connection means for transmitting the connection destination introduction request for the channel selected by the channel selection means to the connection management device, and then connecting to the connection destination candidate notified from the connection management device;
A ring buffer that sets a ring buffer area for receiving and temporarily storing content data of a channel selected by the channel selection means from the connection destination candidate in the storage means for each channel selected by the channel selection means Setting means;
Reproduction means for taking out and reproducing the content data of the latest channel selected by the channel selection means from the ring buffer area corresponding to the channel;
Content data reproduction status detection means for detecting the reproduction status of the content data for each channel by the reproduction means;
Relay request receiving means for receiving a relay request for the content data from the other terminal device;
Transfer means for transferring the content data stored in the ring buffer area to the other terminal device,
The ring buffer setting means of the terminal device includes:
The content data distribution system, wherein the ring buffer area having a buffer capacity corresponding to a reproduction status of content data of a channel selected by the channel selection means is set in the storage means. The connection means of the terminal device is:
A connection destination introduction request including a buffer capacity of a ring buffer area corresponding to the channel selected by the channel selection means is transmitted as the connection destination introduction request;
The connection management device includes:
Buffer capacity receiving means for receiving the buffer capacity of the ring buffer area of the terminal device and storing it in the connection state information storage means;
The connection destination candidate selection means of the connection management device includes:
When receiving a connection destination introduction request including the buffer capacity of the ring buffer area from the terminal device, in the hierarchical structure of the channel corresponding to the connection destination introduction request, the ring buffer area of the terminal device constituting the hierarchical structure The connection destination candidate for the connection destination introduction request is selected from the connection state information stored in the connection state information storage means so that the buffer capacity of the connection destination becomes smaller from upstream to downstream of the hierarchical structure. The content data distribution system according to claim 1. One or more content distribution devices that stream-distribute content data on a plurality of channels, a plurality of terminal devices that receive and reproduce the content data, and a plurality of terminal devices that have the content distribution device as a vertex for each channel A connection management device that manages the logical connection in a multi-layer structure, and the content data streamed from the content distribution device is sequentially downstream of the hierarchical structure by the relay function of the terminal device for each channel. In the content data distribution method of the content data distribution system that is relayed to and the content data can be reproduced by the plurality of terminal devices,
The content distribution device includes:
Delivering the content data;
The connection management device includes:
Storing connection state information of the terminal device constituting the hierarchical structure for each channel;
When receiving a connection destination introduction request from the terminal device, selecting connection destination candidates from the stored connection state information;
Notifying the selected connection destination candidate to the terminal device that has transmitted the connection destination introduction request,
The terminal device
Detecting the selection of the channel;
Transmitting the connection destination introduction request for the selected channel to the connection management device;
Connecting to the connection destination candidate notified from the connection management device;
Setting a ring buffer area in which content data of a channel selected by the channel selection unit is received from the connection destination candidate and temporarily stored in the storage unit for each channel selected by the channel selection unit; ,
Retrieving the content data of the selected latest channel from the ring buffer area corresponding to the channel and reproducing the content data;
Detecting the reproduction status of the content data for each channel;
Receiving a relay request for the content data from another terminal device;
Transferring the content data stored in the ring buffer area to the other terminal device;
A content data distribution method comprising: setting, in the storage unit, the ring buffer area having a buffer capacity corresponding to the content data reproduction status of the selected channel. One or more content distribution apparatuses for streaming distribution of content data on a plurality of channels, a plurality of terminal apparatuses for receiving and reproducing the content data, and a plurality of terminal apparatuses for each channel with the content distribution apparatus at the top A connection management device that manages the logical connection in a multi-layer structure, and the content data streamed from the content distribution device is sequentially downstream of the hierarchical structure by the relay function of the terminal device for each channel. In the terminal device in the content data distribution system that is relayed to the content data and can be reproduced by the plurality of terminal devices,
Storage means;
Channel selection means for selecting the channel;
A connection means for transmitting the connection destination introduction request for the channel selected by the channel selection means to the connection management device, and then connecting to the connection destination candidate notified from the connection management device;
A ring buffer that sets a ring buffer area for receiving and temporarily storing content data of a channel selected by the channel selection means from the connection destination candidate in the storage means for each channel selected by the channel selection means Setting means;
Reproduction means for taking out and reproducing the content data of the latest channel selected by the channel selection means from the ring buffer area corresponding to the channel;
Content data reproduction status detection means for detecting the reproduction status of the content data for each channel by the reproduction means;
Relay request receiving means for receiving a relay request for the content data from the other terminal device;
Transfer means for transferring the content data stored in the ring buffer area to the other terminal device,
The ring buffer setting means includes:
The terminal device characterized in that the ring buffer area having a buffer capacity corresponding to the reproduction status of the content data of the channel selected by the channel selection means is set in the storage means. The terminal device according to claim 4, wherein the condition relating to the reproduction state of the content data is the number of reproductions of the content data in each channel. The terminal device according to claim 4, wherein the condition regarding the reproduction state of the content data is a reproduction time of the content data in each channel. The ring buffer setting means includes:
The terminal device according to any one of claims 4 to 6, wherein the ring buffer area is updated so as to have a buffer capacity corresponding to a reproduction status of the content data for each channel for each predetermined period. . The ring buffer setting means includes:
When the connection means is connected to the connection destination candidate of the channel selected by the channel selection means, there is no ring buffer area corresponding to the selected channel in the storage means, and the storage means set in the storage means When it is determined that the number of ring buffer areas has reached a predetermined number, one ring buffer area is deleted from the storage means among the plurality of ring buffer areas, and the ring corresponding to the selected channel is stored in the storage means. The terminal area according to claim 4, wherein a buffer area is set. The ring buffer setting means includes:
Among the ring buffer areas set in the storage means, the ring buffer area that has the longest period not being played back by the playback means is deleted from the storage means, and the ring buffer area corresponding to the selected channel is stored in the storage means The terminal device according to claim 8, wherein: is set. The terminal device according to any one of claims 4 to 9, further comprising a buffer capacity notification unit that notifies the connection management apparatus of a buffer capacity of the ring buffer area at predetermined intervals. A buffer that notifies the connection management device of the buffer capacity of the ring buffer area when the ring buffer area is set by the ring buffer setting means or when the buffer capacity of the ring buffer area is changed by the ring buffer setting means It has a capacity | capacitance notification means. The terminal device of any one of Claims 4-9 characterized by the above-mentioned. When it is detected that the power supply of the own terminal device is cut off, the buffer capacities of the plurality of ring buffer areas set in the storage means are stored in a nonvolatile storage device, and the power supply of the own terminal device is supplied again The backup processing means for resetting the plurality of ring buffer areas in the storage means based on the buffer capacity stored in the non-volatile storage device is provided. The terminal device described in 1. Upstream buffer capacity acquisition means for acquiring the buffer capacity of the ring buffer area of a terminal apparatus upstream of the terminal apparatus in the hierarchical structure;
Comparing means for comparing the buffer capacity of the ring buffer area of the terminal apparatus with the buffer capacity of the ring buffer area of the upstream terminal apparatus;
As a result of the comparison by the comparison means, when the buffer capacity of the ring buffer area of the terminal apparatus is larger than the buffer capacity of the ring buffer area of the upstream terminal apparatus, the upstream terminal apparatus The terminal device according to any one of claims 4 to 12, further comprising reconnection means for reconnecting upstream in a hierarchical structure. The upstream buffer capacity acquisition means includes
The buffer capacity of the ring buffer area of the upstream terminal apparatus is obtained by inquiring of the connection management apparatus at every predetermined time the buffer capacity of the ring buffer area of the upstream terminal apparatus. The terminal device according to claim 13. The upstream buffer capacity acquisition means includes
Obtaining the buffer capacity of the ring buffer area possessed by the upstream terminal device by inquiring of the upstream terminal device the buffer capacity of the ring buffer area possessed by the upstream terminal device at predetermined intervals. The terminal device according to claim 13. Downstream buffer capacity acquisition means for acquiring the buffer capacity of the ring buffer area of the terminal device downstream of the terminal device in the hierarchical structure;
Comparison means for comparing the buffer capacity of the ring buffer area of the terminal apparatus with the buffer capacity of the ring buffer area of the downstream terminal apparatus;
As a result of comparison by the comparison means, when the buffer capacity of the ring buffer area of the terminal apparatus is smaller than the buffer capacity of the ring buffer area of the downstream terminal apparatus, the downstream terminal apparatus or the downstream terminal apparatus The terminal device according to any one of claims 4 to 15, further comprising reconnection means for reconnecting downstream in the hierarchical structure with respect to the terminal device. The downstream buffer capacity acquisition means includes
The buffer capacity of the downstream terminal device is acquired by inquiring the connection management device at every predetermined time about the buffer capacity of the ring buffer area of the downstream terminal device. The terminal device described. The downstream buffer capacity acquisition means includes
Obtaining the buffer capacity of the ring buffer area of the downstream terminal device by inquiring of the buffer capacity of the ring buffer area of the downstream terminal device to the downstream terminal apparatus at predetermined intervals. The terminal device according to claim 16, characterized in that: The connecting means includes
The terminal device according to any one of claims 4 to 18, wherein a connection destination introduction request including a buffer capacity of the ring buffer area for a channel related to the connection destination introduction request is transmitted as the connection destination introduction request. .   The program for making a computer function as each means of the terminal device of any one of Claims 4-19.

Images