JP4702397B2 - Content server, information processing apparatus, network device, content distribution method, information processing method, and content distribution system - Google Patents

Description

  The present invention relates to a content server, an information processing apparatus, a network device, a content distribution method, an information processing method, and a content distribution system.

  IPTV (Internet Protocol Television), which is a video distribution system using an IP network, is based on MPEG2 and H.264. By distributing a video compressed using a high-efficiency video encoding technology such as H.264 / AVC to a plurality of terminals by IP multicast, a service equivalent to a conventional TV system using radio waves can be realized.

  However, the IPTV system requires about 1 to 3 seconds for channel switching due to the characteristics of the system, and there is a problem that the time required for channel switching is slow compared to ordinary digital television broadcasting. It was.

  This problem is caused by two problems as described below. The first problem is that it takes time to control switching of data to be distributed to the access network. This is because the IPTV system is a network with a limited access network to the service subscriber's home (for example, about 10 Mbps in the case of ADSL2), and the access network includes only the data of the channel received by the terminal. This is a problem that occurs because the transmission method is adopted.

  The second problem is that in order to distribute channel data in an access network with a limited data band, the length of compressed video, for example, MPEG2 GOP (Group Of Picture) length, must be longer than that of digital broadcasting. Therefore, there is a problem that the process waits until receiving the first I picture (IDR picture in the case of AVC) of the MPEG2 stream GOP of the switched channel.

  To solve these problems, the following two methods have been proposed as means for speeding up channel switching in IPTV. The first method is a method in which compressed data obtained by encoding a video signal of a channel at a low resolution to a low bit rate is simultaneously delivered to a terminal as a channel switching stream (for example, Patent Document 1 and Patent Document 2). reference.). In this method, compressed data with a low bit rate is displayed at the time of channel switching, and then the display is switched to display with a compressed data method with a bit rate of the original resolution. In the second method, a server that caches and buffers an I picture (IDR picture) is arranged near the access network, and at the time of channel switching, the I picture is temporarily transmitted from the server to the terminal at high speed and displayed. (See, for example, Patent Document 3).

International Publication No. 04/114667 Pamphlet International Publication No. 04/114668 Pamphlet US Patent Application Publication No. 2005/0081244

  However, the methods described in Patent Document 1 and Patent Document 2 have a problem in that the quality of the channel switching video is poor because of the low resolution. Further, in the method described in Patent Document 3, it is necessary to arrange a special server in the vicinity of the access network, and the equipment cost increases in proportion to the size of the entire system, and the operation cost increases because the system is complicated. There is a problem.

  Further, both methods have a problem that the protocol for switching channels and the mechanism for switching data streams are complicated, and it is difficult to implement a playback system for the terminal.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to perform high-speed channel switching in an IPTV system by a simple method without significantly changing the playback system of existing network devices and terminals. It is an object of the present invention to provide a new and improved content server, information processing apparatus, network device, content distribution method, information processing method, and content distribution system that can be realized.

  In order to solve the above-described problem, according to one aspect of the present invention, in time-series data generated by compression of a video signal, decoding of a subsequent video signal can be started without depending on previous data. A plurality of video / audio contents encoded so that the video frames corresponding to the reference compressed video data as data and the delivery times of the reference compressed data are different from each other, and a plurality of compressed data streams are generated from the one video / audio content A network address different from each other is assigned to the encoding unit, and the compressed data stream generated by the one encoding unit is acquired from one different encoding unit and distributed. A content server is provided.

  Here, the reference compressed video data is data that can start decoding of the subsequent video signal without depending on the previous data in the time-series data generated by the compression of the video signal. A plurality of reference compressed video data can exist in the time series data.

  According to such a configuration, the plurality of encoding units encode the video and audio content so that the video frame corresponding to the reference compressed video data and the delivery time of the reference compressed data are different from each other, and A plurality of compressed data streams are generated, and a plurality of distribution units are assigned different network addresses, and acquire one compressed data stream generated by the one encoding unit from one different encoding unit. And deliver.

  Each of the plurality of encoding units may encode the video and audio content so that compression and encoding conditions are the same.

  Preferably, each of the plurality of distribution units outputs reference compressed video data distribution scheduled time information related to a distribution scheduled time at which the generated reference compressed video data is distributed.

  The clock in the content server is synchronized with a reference clock provided from a reference clock server located outside the content server, and the plurality of encoding units are configured to perform the reference based on the synchronized clock. The compressed video data distribution scheduled time may be measured.

  In the content server, a plurality of devices including one encoding unit and one distribution unit may be connected in parallel. Further, the plurality of encoding units and the plurality of distribution units may be provided in the same device.

  In order to solve the above problem, according to another aspect of the present invention, in time-series data generated by compression of a video signal, decoding of subsequent video signals is started without depending on previous data. The video / audio content is encoded so that the video frame corresponding to the standard compressed video data that can be generated and the delivery time of the standard compressed data are different from each other, and a plurality of compressed data streams are generated from the video / audio content. A plurality of encoding units and network addresses different from each other are allocated, and the one compressed data stream generated by the one encoding unit is acquired from one different encoding unit and distributed. The compression unit to obtain from the plurality of compressed data streams distributed by the content server An information processing apparatus is provided comprising: an acquisition stream selection unit that selects a data stream; and a content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit. The

  The acquisition stream selection unit acquires reference compressed video data distribution scheduled time information output from the content server and related to a distribution scheduled time at which the generated reference compressed video data is distributed, and the acquired reference compressed video data distribution The compressed data stream to be acquired may be selected based on the scheduled time information.

  The acquisition stream selection unit is a switch that completes switching of the acquired compressed data stream by using a switching time required for switching the display to the acquired compressed data stream and a time at which selection processing of the acquired stream is started. An estimated completion time may be calculated, and the compressed data stream having the latest reference compressed video data distribution scheduled time after the calculated expected switching completion time may be selected.

  The acquisition stream selection unit does not have to select any data stream when the reference compressed video data distribution scheduled times corresponding to the respective compressed data streams are all before the expected switching completion time.

  The acquisition stream selection unit displays the selection result of the compressed data stream when the time interval between the scheduled delivery time and the expected switching completion time of the selected compressed data stream is equal to or less than a predetermined threshold. You may make it notify to a content acquisition part.

  The content acquisition unit may perform switching control of the compressed data stream selected by the acquisition stream selection unit by IGMP.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. Video audio content is encoded so that the video frame corresponding to the reference compressed video data that can be started and the delivery time of the reference compressed data are different from each other, and a plurality of compressed data streams are generated from the one video audio content A plurality of encoding units and different network addresses are assigned to each other, and the one compressed data stream generated by the one encoding unit is acquired from one different encoding unit and distributed. A plurality of compressed data streams distributed by a content server including a plurality of distribution units; An acquisition stream selection unit that selects a compressed data stream, a content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit, and the acquired compressed data stream There is provided a network device including a distribution control unit that distributes to an information processing device connected via a network.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. A video frame corresponding to the reference compressed video data, which can be started, and a single video / audio content input so that the delivery times of the reference compressed data are different from each other are encoded. There is provided a content distribution method including an encoding step of generating a compressed data stream and a step of simultaneously distributing each of the generated plurality of compressed data streams.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. Reference compressed video data that can be started is distributed with respect to a plurality of compressed data streams in which one video and audio content is encoded such that the corresponding video frame and the distribution time of the reference compressed data are different from each other. An information processing method is provided that includes an acquisition stream selection step of selecting the compressed data stream to be acquired from the plurality of compressed data streams, and a content acquisition step of acquiring the selected compressed data stream.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. Reference compressed video data that can be started is distributed with respect to a plurality of compressed data streams in which one video and audio content is encoded such that the corresponding video frame and the distribution time of the reference compressed data are different from each other. An acquisition stream selection step of selecting the compressed data stream to be acquired from the plurality of compressed data streams, a content acquisition step of acquiring the selected compressed data stream, and the acquired compressed data stream via a network A distribution control step of distributing to the information processing apparatus connected by Including, content delivery method is provided.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. Video audio content is encoded so that the video frame corresponding to the reference compressed video data that can be started and the delivery time of the reference compressed data are different from each other, and a plurality of compressed data streams are generated from one video audio signal. A plurality of encoding units that are assigned different network addresses, and obtain and distribute one compressed data stream generated by the one encoding unit from one different encoding unit. A content server comprising: a plurality of compressed data streams distributed by the content server; An acquisition stream selection unit that selects the compressed data stream to be acquired, and a content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit. And a content distribution system including a processing device.

  In order to solve the above-described problem, according to still another aspect of the present invention, time-series data generated by compression of a video signal can be used to decode subsequent video signals without depending on previous data. Video audio content is encoded so that the video frame corresponding to the reference compressed video data that can be started and the delivery time of the reference compressed data are different from each other, and a plurality of compressed data streams are generated from the one video audio content A plurality of encoding units and different network addresses are assigned to each other, and the one compressed data stream generated by the one encoding unit is acquired from one different encoding unit and distributed. A content server comprising: a plurality of distribution units; and the plurality of compressed data streams distributed by the content server An information processing apparatus that notifies the compressed data stream desired to be reproduced and reproduces the acquired compressed data stream, and the plurality of contents distributed by the content server based on the notification received from the information processing apparatus Content that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit and an acquisition stream selection unit that selects the compressed data stream to be acquired There is provided a content distribution system including an acquisition unit and a network device including a distribution control unit that distributes the acquired compressed data stream to the information processing apparatus via a network.

  According to the present invention, it is possible to realize high-speed channel switching in an IPTV system by a simple method without significantly changing existing network device or terminal playback systems.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<Explanation about basic technology>
First, prior to detailed description of a preferred embodiment according to the present invention, technical matters that form the basis for realizing the present embodiment will be described. In addition, this embodiment is comprised so that a more remarkable effect can be acquired by adding improvement on the fundamental technique described below. Therefore, the technology related to the improvement is the only part that characterizes this embodiment. In other words, the present embodiment follows the basic concept of the technical matters described here, but the essence is rather concentrated in the improved portion, the configuration is clearly different, and the effect is in line with the basic technology. Please note that

  FIG. 19 is a network configuration diagram regarding multicast video distribution in a general IPTV system 900. As shown in FIG. 19, a general IPTV system 900 includes, for example, a plurality of content servers 901 corresponding to respective channels, edge switches 903 and 909, routers 905 and 907, and a plurality of viewers. Terminal 911.

  The content server 901 includes an encoder that encodes a video / audio signal (video / audio content) and a distribution server. The video signal of each TV channel (for example, total 300 channels) is, for example, H.264. H.264 / AVC is used for encoding in real time, and audio signals of each TV channel are encoded in real time using a high-efficiency audio encoding technique such as HE-AAC (High-Efficiency Advanced Audio Coding). After that, the encoder multiplexes each encoded signal in the MPEG2-TS (MPEG2-Transport Stream) format, and transmits the multiplexed signal to the distribution server as stream data. The distribution server converts the plurality of MPEG2-TS packets into a RTP (Real-time Transport Protocol) packet format, puts the MPEG2-TS packets, and further multicasts to the IP network using a UDP (User Datagram Protocol) transmission protocol. To deliver.

  The IP packet of the stream of each channel is designated with an individual multicast address, and is distributed to the terminal 911 via the core network and the access network. As the core network, a broadband network capable of transmitting data of several gigabits to several tens of gigabits per second using a technique such as WDM (Wavelength Division Multiplexing) using an optical fiber is used. On the other hand, the access network from the IPTV service subscriber's home (that is, the edge switch 909 to the terminal 911) uses, for example, a technology such as ADSL (Asymmetric Digital Subscriber Line) using copper wiring of an existing analog telephone line. The There are various standards for ADSL, and the data bandwidth depends on the length of the line. For example, if the standard ADSL2 is used, a bandwidth of 10 megabits or more per second can be realized if the distance is 4 kilometers or less from the base station. It is possible to distribute a single video signal having a resolution of a high-definition television.

  In this way, the core network has sufficient bandwidth and can distribute all the channel streams provided by the IPTV service, whereas the data bandwidth of the access network is limited. You only need to distribute data for the channels you ’re using. In general, IGMP (Internet Group Management Protocol) is used for distribution control of multicast data.

  When the terminal 911 transmits an IGMP message to the network in order to join the multicast group of the data of the channel to be received, the edge router 907 distributes the multicast data only to the requested network. However, when a plurality of terminals are connected to the edge router 907, the edge router 907 distributes the data to the access network to which the terminal 911 that has not received the corresponding multicast data is connected. End up. Therefore, it is necessary to prevent distribution to the access work to which the terminal 911 not requesting to join the multicast group by IGMP is connected. Therefore, the DSLAM (Digital Subscriber Line Access Multiplexer), which is the edge switch 909, is implemented with IGMP SNOOPING. The DSLAM performs filtering control so as to steal the IGMP packet transmitted from the terminal 911 and distribute multicast group data only to the access network to which the terminal 911 that has received the request is connected.

  The IPTV system according to each embodiment of the present invention is made after following the IPTV system having the general architecture as described above. The embodiments of the present invention will be described in detail below.

(First embodiment)
<About content distribution system>
First, the content distribution system according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is an explanatory diagram for explaining a content distribution system according to the present embodiment. In the following description, an IPTV system will be described as an example of a content distribution system, and will be described in detail.

  As shown in FIG. 1, for example, the content distribution system 1 according to the present embodiment includes a plurality of content servers 10A, 10B, 10C, switches 12, 18, routers 14, 16, corresponding to each channel, and viewing. A plurality of information processing devices 20A, 20B, 20C, and 20D used by a person, a distribution scheduled time information transmission server 30, and a reference clock server 40 are mainly provided.

  The content server 10 corresponds to the broadcasting station of each channel in the IPTV system, encodes video / audio content (video / audio signal) by a predetermined method into a compressed data stream, and uses an IP network using a predetermined transmission protocol. To multicast. In FIG. 1, only three content servers 10 are illustrated, but there are as many content servers 10 as, for example, the number of channels on the IPTV system, and when the total number of channels is 300, the content distribution system 1, 300 content servers 10 exist.

  The switch 12 is a communication device having a switching function (switching function) of packets flowing on the core network, and the switch 18 is a communication device having a switching function of packets flowing on the access network, and is located around the core network. Therefore, it is called an edge switch. These switches 12 and 18 are set so as to determine the destination of the packet and relay the communication only to a specific partner.

  The routers 14 and 16 are devices that relay data such as packets flowing on the network. These routers analyze data of a part of the network layer and transport layer in the so-called OSI reference model and transfer data. In addition, it has a route selection function for analyzing an address written in the network layer and determining which route should transfer data.

  The information processing apparatus 20 is a terminal used by a viewer of the content distribution system 1, acquires content to be viewed from a plurality of video / audio contents distributed by each content server 10, and acquires the acquired content. Reproduce.

  The content server 10 and the information processing apparatus 20 described above will be described again in detail below.

The distribution scheduled time information transmission server 30 receives the reference compressed video data distribution scheduled time information output from each content server 10 and distributes the reference compressed video data of all the content servers 10 existing on the content distribution system 1. Organize scheduled time information. Also, the distribution scheduled time information transmission server 30 sends the collected reference compressed video data distribution scheduled time information to the information processing apparatus 20 connected to the system at a predetermined time interval (for example, 10 milliseconds to 20 milliseconds). (Second cycle). The reference compressed video data distribution scheduled time information described above will be described in detail below.

  The reference clock server 40 is a server having a time information source with an accuracy of 1 / 10,000 second, for example, and uses, for example, the content server 10 connected to the content distribution system 1 or information processing using NTP (Network Time Protocol). The internal clock of the computer such as the device 20 is synchronized with the time information source of the reference clock server 40.

  The content distribution system 1 according to the present embodiment has been described above. Next, the content server 10 and the information processing apparatus 20 according to the present embodiment will be described in detail with reference to FIGS. 2 and 3.

<Content server configuration>
Next, the configuration of the content server 10 according to the present embodiment will be described in detail with reference to FIG. FIG. 2 is a block diagram for explaining the configuration of the content server 10 according to the present embodiment.

  In the content server 10 according to the present embodiment, the clock in the content server 10 is synchronized with the reference clock server 40 existing on the content distribution system 1. The content server 10 synchronizes the internal clock with the time of the reference clock server 40 using, for example, NTP at an arbitrary timing such as when the server is started or when the administrator of the content server 10 inputs an internal clock update command. It is possible to make it.

  Each processing unit of the content server 10 according to the present embodiment performs a predetermined process while referring to the current time of the internal clock synchronized with the reference clock server 40.

  The content server 10 according to the present embodiment includes a first processing unit 11A and a second processing unit 11B, for example, as illustrated in FIG. The audio / video signals of the same channel are input to the first processing unit 11A and the second processing unit 11B, respectively.

  As illustrated in FIG. 2, the first processing unit 11A mainly includes, for example, a first encoding unit 101, a first distribution unit 105, and a storage unit 109. In addition, as illustrated in FIG. 2, the second processing unit 11B mainly includes, for example, a second encoding unit 103, a second distribution unit 107, and a storage unit 111.

  As shown in FIG. 2, the first processing unit 11A and the second processing unit 11B are processing units each including at least one set including one encoding unit and one distribution unit. The distribution units function independently of each other.

  The first encoding unit 101 and the second encoding unit 103 are configured by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The first encoding unit 101 and the second encoding unit 103 convert the video signal out of the input video / audio signal, for example, H.264. In addition to encoding in real time using H.264 / AVC (hereinafter also referred to as encoding), the audio signal is encoded in real time using a high-efficiency audio encoding technology such as HE-AAC. Subsequently, the first encoding unit 101 and the second encoding unit 103 multiplex the encoded signals into the MPEG2-TS format, and then send them to the first distribution unit 105 and the second distribution unit 107 as compressed data streams. To transmit.

  Here, the first encoding unit 101 and the second encoding unit 103 each have a position of a video frame (usually 30 frames per second) or a field (60 fields per second) of the original video signal corresponding to the reference compressed data. The video signals of the video / audio signals are encoded so as to be different from each other. Here, the standard compressed video data means compressed video data that can be decoded without referring to the compressed video data temporally prior to the compressed video data. The first encoding unit 101 and the second encoding unit 103 perform encoding so that the reference compressed video data appears periodically so that encoding can be performed from the middle of the compressed data stream. Examples of such reference compressed video data include, for example, H.264. IDR (Instantaneous Decoder Refresh: Instantaneous refresh of decoder decoding operation) picture in H.264 / AVC, and I picture (Intra picture: intra-picture coded picture) in MPEG2 video can be mentioned.

  For example, a high-definition video is converted to H.264. Consider the case of encoding with H.264 / AVC. At this time, the first encoding unit 101 and the second encoding unit 103 are composed of 30 MPEG pictures per second, and encode the video signal so that the IDR picture appears once per second. By performing such an encoding process, even if the video bit rate is 7 megabits per second at the maximum, it is possible to achieve a higher quality of the reproduced video than encoding the IDR picture so that it appears twice a second. can do. Note that, in accordance with the notation of GOP (Group Of Picture) of MPEG2 video, in this specification, a group of a plurality of pictures including an IDR picture at the head is indicated as GOP.

  Each of the first encoding unit 101 and the second encoding unit 103 encodes the video / audio signal so that conditions other than the timing at which the reference compressed video data appears are the same. For example, the first encoding unit 101 and the second encoding unit 103 encode the same video signal with the same number of MPEG pictures and the same resolution. Also, the MPEG streams output from the encoding units 101 and 103 are output so as to be a maximum of 8 megabits per second when multiplexed into MPEG2-TS. In this case, two MPEG2-TS IDR pictures appear every second (that is, GOP length 30 frames), but the IDR picture is generated by being shifted by 0.5 seconds (that is, 15 pictures). As described above, the first encoding unit 101 and the second encoding unit 103 are respectively set.

  The first encoding unit 101 and the second encoding unit 103 can refer to various databases and the like recorded in the storage unit 109 and the storage unit 111, which will be described later, when encoding the video / audio signal, respectively. It is. Further, the first encoding unit 101 and the second encoding unit 103 may record the generated compressed data streams in the storage unit 109 and the storage unit 111, respectively.

  The 1st delivery part 105 and the 2nd delivery part 107 are comprised from CPU, ROM, RAM, a communication apparatus etc., for example, and have a function of what is called a RTP (Real-Time Transport Protocol) server. The first distribution unit 105 and the second distribution unit 107 store the MPEG2-TS packets generated by the first encoding unit 101 and the second encoding unit 103 in the RTP packet and the UDP packet, respectively, and then perform IP multicasting. Store in packet and send. These IP packets are distributed by the IP network via the switch 12 or the like, for example.

  Also, the first distribution unit 105 and the second distribution unit 107 calculate a distribution scheduled time at which the reference compressed video data generated by the first encoding unit 101 and the second encoding unit 103 is distributed, and this distribution schedule Reference compressed video data distribution scheduled time information (hereinafter abbreviated as distribution scheduled time information) in which the time is described is periodically generated. A method for calculating the scheduled delivery time will be described in detail later.

  The first distribution unit 105 and the second distribution unit 107 periodically output the distribution schedule time information generated by each to the distribution schedule time information transmission server 30. The first distribution unit 105 and the second distribution unit 107 may record the generated distribution scheduled time information in the storage unit 109 and the storage unit 111, respectively.

  The storage unit 109 appropriately records various parameters, processing progresses, and various databases that need to be saved when the first processing unit 11A according to the present embodiment performs some processing. The The storage unit 109 can be freely read and written by the first encoding unit 101, the first distribution unit 105, and the like.

  Similarly, in the storage unit 111, the second processing unit 11B according to the present embodiment stores various parameters, processing progresses, and various databases that need to be saved when performing some processing. Are recorded as appropriate. The storage unit 111 can be freely read and written by the second encoding unit 103, the second distribution unit 107, and the like.

  In the example illustrated in FIG. 2, the case where the content server 10 according to the present embodiment is configured by two processing units, the first processing unit 11A and the second processing unit 11B, has been described. You may be comprised from three or more process parts. As the number of processing units allocated to one channel (in other words, one video / audio signal) increases, it becomes possible to realize high-speed channel switching.

  In addition, the first processing unit 11A and the second processing unit 11B may be provided in the housing of one content server. Further, a processing unit including one encoding unit and one distribution unit is independent as one device, and a plurality of such devices may be connected in parallel.

  Heretofore, an example of the function of the content server 10 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

<Configuration of information processing device>
Next, the configuration of the information processing apparatus 20 according to the present embodiment will be described in detail with reference to FIG. FIG. 3 is a block diagram for explaining the configuration of the information processing apparatus 20 according to the present embodiment.

  In the information processing apparatus 20 according to the present embodiment, the clock in the information processing apparatus 20 is synchronized with the reference clock server 40 existing on the content distribution system 1. The information processing device 20 uses, for example, NTP to set the internal clock to the time of the reference clock server 40 at an arbitrary timing such as when the device starts up or when the user of the information processing device 20 inputs an internal clock update command. It is possible to synchronize with.

  For example, as illustrated in FIG. 3, the information processing apparatus 20 according to the present embodiment includes a channel selection unit 201, a content acquisition unit 203, an acquisition stream selection unit 205, a content reproduction unit 207, a storage unit 209, Is mainly provided.

  The channel selection unit 201 includes, for example, a CPU, a ROM, a RAM, and the like. When a user selects a specific channel from a plurality of distributed channels by operating an operation unit such as a channel selection switch or a channel selection button provided in the information processing apparatus 20 or a remote controller. The channel selection unit 201 converts an input from a channel selection switch, a channel selection button, or the like into a predetermined signal. In addition, the channel selection unit 201 outputs a predetermined signal obtained by converting the user input to the content acquisition unit 203 described later.

  The content acquisition unit 203 includes, for example, a CPU, a ROM, a RAM, a communication device, and the like, and a channel corresponding to the signal transmitted from the channel selection unit 201 is distributed from a plurality of distributed channels. Get content. In the content distribution system according to the present embodiment, since a plurality of compressed data streams are distributed for content belonging to one channel, the content acquisition unit 203 selects the notification notified from the acquisition stream selection unit 205 described later. Content is acquired based on the result.

  When acquiring content, the content acquisition unit 203 can execute content acquisition processing while referring to various databases and the like recorded in the storage unit 209 described later.

  The acquisition stream selection unit 205 includes, for example, a CPU, a ROM, a RAM, a communication device, and the like, and performs processing as described below with reference to the current time of the internal clock synchronized with the reference clock server 40. To implement.

  The acquisition stream selection unit 205 periodically receives the scheduled delivery time information output from each content server 10 and collected by the scheduled delivery time information transmission server 30 from the scheduled delivery time information transmission server 30. The acquisition stream selection unit 205 selects the compressed data stream to be acquired from the plurality of compressed data streams distributed by the channel notified from the content acquisition unit 203 with reference to the received scheduled delivery time information. .

  More specifically, the acquisition stream selection unit 205 has started a process for selecting a compressed data stream to be acquired and a switching time required for acquiring and displaying the compressed data stream of the channel notified from the content acquisition unit 203. Using the time, a predicted switching completion time for completing the display of the acquired compressed data stream is calculated. Here, the above switching time means the time required for displaying the content distributed on a new channel when the channel is switched from the currently displayed channel to a different channel. is there. The acquisition stream selection unit 205 compares the calculated estimated switching completion time with the estimated distribution time information acquired from the estimated distribution time information transmission server 30, and has compressed data having the latest estimated distribution time after the estimated switching completion time. Select a stream.

  In addition, when the scheduled distribution times corresponding to the plurality of compressed data streams distributed by the channel notified from the content acquisition unit 203 are all before the expected switching completion time, the acquisition stream selection unit 205 No compressed data stream is selected. Instead, based on the scheduled delivery time information newly notified from the scheduled delivery time information transmission server 30, the compressed data stream selection process is executed again.

  Since the scheduled delivery time information is transmitted from the scheduled delivery time information transmission server 30 at a very short cycle such as a period of several tens of milliseconds, the acquisition stream selection unit 205 performs “selection” as described above. Even if it is determined that “there is no”, it is selected at the next appropriate timing.

  When the selection of the compressed data stream to be acquired ends, the acquisition stream selection unit 205 notifies the content acquisition unit 203 of the selection result.

  Note that when performing these selection processes, the acquisition stream selection unit 205 can perform processes while referring to various databases and the like recorded in the storage unit 209 described later.

  In addition, the acquisition stream selection unit 205, when there is a time interval exceeding a predetermined threshold between the scheduled delivery time and the expected switching completion time of the selected compressed data stream, It is not necessary to notify the content acquisition unit 203 of the selection result. Instead, based on the scheduled delivery time information newly notified from the scheduled delivery time information transmission server 30, the compressed data stream selection process is executed again. In other words, the acquisition stream selection unit 205 selects the compressed data stream to be acquired when the time interval between the scheduled delivery time and the predicted completion time of switching of the selected compressed data stream is equal to or less than a predetermined threshold. The result is notified to the content acquisition unit 203.

  If there is a time interval equal to or greater than a predetermined threshold between the expected switching completion time and the scheduled delivery time, the display screen will be displayed even if display switching is performed based on the selection result of the acquisition stream selection unit 205. The screen will remain in a blackout state, such as displaying a black color on the screen. Therefore, while waiting for the scheduled delivery time information newly notified from the scheduled delivery time information transmission server 30, the stream of the channel before switching is continuously acquired, so that the video can be continuously displayed on the screen. The compressed data stream selection process can be executed again without impairing the viewer's feeling of use.

  The acquisition stream selection method as described above will be described in detail later.

  The content playback unit 207 includes, for example, a CPU, a ROM, a RAM, and the like. The content playback unit 207 plays back the content acquired by the content acquisition unit 203 and displays it on a display unit (not shown) included in the information processing apparatus 20. . Here, the reproduction of content refers to decoding the compressed data stream transmitted from the content acquisition unit 203, reproducing the decoded content, and decoding the compressed data stream while decoding the content. Including playing. The content playback unit 207 can refer to a database or the like recorded in the storage unit 209, which will be described later, when performing content decoding or content playback.

  The storage unit 209 appropriately records various parameters, intermediate progress of processing, or various databases that need to be saved when the information processing apparatus 20 according to the present embodiment performs some processing. . The storage unit 209 can be freely read and written by the channel selection unit 201, the content acquisition unit 203, the acquisition stream selection unit 205, the content reproduction unit 207, and the like.

  Heretofore, an example of the function of the information processing apparatus 20 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

<About content distribution method>
Next, the content distribution method executed by the content server 10 according to the present embodiment will be described in detail with reference to FIGS.

[Position relationship of standard compressed video data]
FIG. 4 is an explanatory diagram for explaining the positional relationship of IDR pictures in the MPEG2-TS stream output from the content server 10 according to the present embodiment. FIG. 4 shows an example in which encoding is performed such that IDR pictures as reference compressed video data appear at a rate of once per second. However, an encoding method that dynamically changes the generation timing of IDR pictures is shown. It may be adopted. In this case, the encoding units are set so as to operate so that the appearance timing of the IDR picture is shifted in cooperation with each other.

  In FIG. 4, encoding is executed so that an IDR picture that is reference compressed video data appears once a second as described above. The GOP is composed of 30 frames, and besides the IDR picture, a P picture (Predictive picture) and a B picture (Bi-predictive picture) exist in the GOP. When the stream output from the first encoding unit 101 and the stream output from the second encoding unit 103 are compared, as is apparent from FIG. 4, the appearance timing of the IDR picture is 15 frames (about 0. 5 seconds).

  In addition to encoding in this way, when the information processing apparatus 20 that is a terminal receives the optimal MPEG2-TS stream at the time of channel switching, the waiting time until the IDR picture is received after switching Can be minimized, and the video of the switched channel can be displayed quickly.

  For example, when switching to this channel occurs in the information processing apparatus 20 that is a terminal at the time “time A” illustrated in FIG. 4, the information processing apparatus 20 outputs the stream ( In other words, by receiving the stream output from the first processing unit 11A), it is possible to shorten the waiting time until the video display of the selected channel after channel switching. Similarly, when the information processing device 20 switches to this channel at the time “time B”, the information processing device 20 reads the stream output from the second encoding unit 103 (in other words, By receiving the stream output from the second processing unit 11B, it is possible to shorten the waiting time until video display of the selected channel after channel switching.

  The MPEG streams output from the encoding units 101 and 103 are generated from the same video signal, and are merely shifted in the temporal position of the IDR picture that can start video display by channel switching or the like. The resolution and the maximum bit rate are encoded under the same conditions. Therefore, from the viewpoint of the viewer, there is almost no awareness of which encoding unit is playing back the stream sent from.

  In addition, each of the encoding units 101 and 103 is H.264. H.264. It is not necessary that the AVC encoder and the MPEG2 multiplexing system clock are synchronized with each other. Each encoding unit 101, 103 can be realized without performing communication between the processing units 11A, 11B if information necessary for shifting the relative positional relationship of IDR pictures is determined in advance. Here, examples of information necessary for shifting the relative positional relationship of the IDR picture include, for example, information on the size of the fixed GOP length and which frame of the video frame of the original video signal is encoded into the IDR picture. Can give information. If a variable GOP length is employed, the processing units 11A and 11B communicate with each other, and the appearance position can be relatively shifted so that the appearance frame of the IDR picture is optimal for channel switching. is there.

[UDP packet format]
FIG. 5 is an explanatory diagram for explaining the format of the UDP packet transmitted by the distribution units 105 and 107 according to the present embodiment. The MPEG2-TS packet generated by each of the encoding units 101 and 103 provided in the content server 10 is output to a distribution unit provided in a processing unit to which the respective encoding unit belongs, and is transmitted as an IP packet. This IP packet has a format as shown in FIG. 5, for example.

  As shown in FIG. 5, an IP multicast UDP packet is composed of an IP header, a UDP header, an RTP header, and an RTP payload. MPEG2-TS packets generated by the encoding units 101 and 103 of the content server 10 are stored in the RTP payload. Normally, seven MPEG2-TS packets are stored in the RTP payload as shown in FIG.

  Each distribution unit 105, 107 of the content server 10 generates a UDP packet as shown in FIG.

[Calculation of scheduled delivery time]
Next, with reference to FIG. 6, a method for calculating a scheduled delivery time performed by each delivery unit included in the content server 10 according to the present embodiment will be described in detail. FIG. 6 is an explanatory diagram for describing a method of calculating a scheduled delivery time performed by the content server according to the present embodiment.

  The distribution units 105 and 107 included in the content server 10 according to the present embodiment calculate the scheduled distribution time of the IDR picture. This calculation process is performed using the following equation.

IDR picture delivery scheduled time at calculation time C: Time F = Time C + Time D + Time E
... (Formula 1)

  Here, in the above Equation 1, the time D can be calculated using time D = (time B−time A) as shown in FIG. This time D can be considered as a delay time from when an MPEG2-TS packet including data of an IDR picture generated from each encoding unit is generated until it is transmitted as an IP multipacket.

  Time B in FIG. 6 is the generation time of the first MPEG2-TS packet including IDR picture data, and time A is the time at which the MPEG2-TS packet is transmitted from each distribution unit. Since this delay time D is generally almost constant, a value obtained by one measurement may be used, a fixed value may be used, or calculated every time an IDR picture is transmitted. Also good.

  A time E in FIG. 6 is a time taken to generate an MPEG2-TS packet including the first data of the next IDR picture at the time C. Since the time E is updated as time C elapses, it is necessary to inquire the respective encoding units each time the IDR picture delivery scheduled time is measured. Normally, in real-time encoding, the IDR picture delivery scheduled time is the time predicted by the encoding unit in order to reduce the delay due to encoding. For example, when each encoding unit is set to generate an IDR picture at a fixed interval every second per second, the time E can be easily obtained. Even when this is not the case, the time E can be sufficiently predicted based on the encoder buffer management information generated by the encoding unit and recorded in the storage unit or the like. If there is an IDR packet that has not been sent yet at time C, the time E takes a negative value.

  Each distribution unit included in the content server according to the present embodiment calculates the reference compressed video data distribution scheduled time using the method as described above. The distribution unit associates the estimated distribution time calculated in this way with location information (for example, an IP address number) assigned to the distribution unit itself, to the distribution scheduled time information transmission server 40 as distribution scheduled time information. Output.

[Example of scheduled delivery time information]
Next, a specific description example of the scheduled delivery time information calculated by the above method will be described in detail with reference to FIG. FIG. 7 is an explanatory diagram for describing a specific example of reference compressed video data distribution scheduled time information according to the present embodiment.

  IDR picture scheduled delivery time information, which is an example of reference compressed video data delivery scheduled time information, includes, for example, an IP header, a UDP header, an RTP header, and an RTP payload, as shown in FIG. . As shown in FIG. 7, IDR picture delivery scheduled time information is stored in the RTP payload of the UDP packet, and M IDR picture delivery scheduled time records are described together with a 12-byte header.

  In the header of IDR picture delivery scheduled time information, an identifier indicating that this UDP packet is in the packet format of IDR picture delivery scheduled time information, a version number, and the like are specified. IDR picture delivery scheduled time information of one MPEG stream is represented by 8 bytes consisting of an IP multicast address (4 bytes) and a scheduled delivery time (4 bytes), and one UDP packet has about M = 150. The scheduled delivery time for the MPEG stream can be described.

  The IP multicast address of one record corresponds to the IPMulticastAddress of each channel of the broadcast discovery record as described below, and the IP packet including the IDR picture of the corresponding IP multicast stream is delivered next. The scheduled time is recorded.

  For the scheduled delivery time, for example, an accuracy of about 1/100 second is sufficient, but an accuracy of 1/1000 second, that is, 1 millisecond is preferable. It is sufficient that this scheduled distribution time is measured with the same clock among the processing units 11 that transmit at least the IP multicast stream of the same channel. Measurement may be performed.

  Next, with reference to FIG. 7, a description will be given of a mechanism for totalizing IDR picture delivery time information measured by each content server 10 of the content delivery system 1 and transmitting the aggregated information to the information processing apparatus 20 that is a terminal.

As described above, the clocks of all the content servers 10 and the information processing devices 20 are set to synchronize with the clocks of the reference clock server 40 connected to the network by NTP (Network Time Protocol). 10 synchronizes its own clock with NTP to this reference clock, and calculates a scheduled time at which the next IDR picture will be distributed with the synchronized clock. The distribution unit provided in the processing unit 11 of the content server 10 transmits the calculated time to the IDR picture distribution scheduled time information transmission server 30 as described above.

In this case, the distribution unit of each processing unit 11 transmits the UDP packet shown in FIG. 7 by IP unicast. In this UDP packet, only the scheduled delivery time record for the IP packet stream sent out by the processing unit 11 is recorded. In other words, the UDP packet in FIG. 7 is M = 1. The IDR picture scheduled delivery time information transmission server 30 aggregates the scheduled IDR picture delivery times transmitted from each content server 10 (more specifically, each processing unit 11), and generates a UDP packet as shown in FIG. Generate.

  As shown in FIG. 1 and FIG. 2, when there are 300 channels (that is, 300 content servers 10) on the content distribution system 1, and there are two processing units 11 for each channel, they are shown in FIG. The UDP packet becomes information of 600 IP multicast streams. Therefore, in each UDP packet, M = 150, and it is divided into four UDP packets and transmitted. In a network environment where there is a risk of losing a UDP packet, the same packet is transmitted redundantly.

The IP multicast address of the UDP packet transmitted from the distribution scheduled time information transmission server 30 is an IP multicast address designated in ChannelChangeInfo of a broadcast discovery record as described later. In order to receive the IDR picture delivery scheduled time information, each information processing device 20 designates this IP multicast address and joins the multicast group by IGMP. Delivery of IDR picture delivery time information is performed, for example, at a frequency of about 100 times per second, that is, at a cycle of 10 milliseconds, and the information processing apparatus 20 updates the latest scheduled IDR picture delivery time information every 10 milliseconds. Can be received.

[Transmission of IP packet]
Next, a mechanism for transmitting the IP packet according to the present embodiment to the information processing apparatus will be described in detail with reference to FIGS. 8 and 9. In the following, a detailed description will be given based on DVB-IP (ETSI TS102 034) which is a standard of the IPTV system.

  The information processing apparatus 20, which is a terminal, needs to know the IP multicast address to which the channel data is distributed in order to receive the MPEG stream for each channel. In DVB-IP, channel information is described in an SD & S broadcast discovery record. This broadcast discovery record is transmitted from an IPTV application server (not shown) such as an EPG server to the information processing apparatus 20 by multicast using DVB SD & S Transport Protocol (DVB STP) defined by DVB-IP. This broadcast discovery record is transferred by an IP multicast address different from the MPEG2-TS stream.

  For this reason, the content server 10 existing in the content distribution system 1 according to the present embodiment preliminarily stores the IP multicast address assigned to each processing unit 11 of the content server 10 and various channel information in accordance with the IPTV application server. Need to be notified.

  FIG. 8 is an explanatory diagram for explaining a data format of a DVB-IP broadcast discovery record. In the broadcast discovery record, information on all channels provided by the IPTV service is described. For example, in the case of an IPTV service that broadcasts 300 channels, the information processing apparatus 20 as a terminal receives a broadcast discovery record in which information on 300 channels is described.

  As the channel information, for example, as shown in FIG. 8, the channel name is described as a character string in TextualIdentifier @ ServiceName, and is used to display the channel name. IPMulticastAddress @ Address and IPMulticastAddress @ Port describe the IP multicast address and port number to which the IP multicast packet of this channel is distributed.

  The information processing apparatus 20, which is a terminal, can receive an IP multicast packet by starting distribution of an IP multicast packet of a desired channel by joining an IP multicast address group described in a broadcast discovery record using IGMP. It becomes.

  Normally, one IP multicast distribution is assigned to each channel, but in the content distribution system according to the present embodiment, a plurality of IP multicast distributions are provided for each channel. For this purpose, a plurality of IPMulticastAddresses are described in the broadcast discovery record.

  FIG. 9 is an explanatory diagram for explaining an example when the broadcast discovery record is expressed in XML. In this broadcast discovery record example, service information for 300 channels is described, and each XML element of “<SingleService>” corresponds to information for one channel.

  For example, the first channel information includes “Channel 1” that is a channel name (ServiceName), two multicast addresses (address 224.0.1.1, port number 1600, and address 224.0.1. 1 and port number 1600). These two addresses correspond to the multicast address of the IP packet distributed from the first processing unit 11A shown in FIG. 2 and the multicast address of the IP packet distributed from the second processing unit 11B. In the channel information listed next, “Channel 2” that is a channel name and two multicast addresses are described. Hereinafter, description of channel information is omitted, but information for a total of 300 channels is listed and described. With the broadcast discovery record described above, the information processing apparatus 20 can know the two channel addresses of each channel.

  Next, a method for acquiring IDR picture distribution schedule information in an MPEG2-TS stream distributed at each multicast address will be described. In the present embodiment, the DVB-IP standard broadcast discovery record is extended, and an XML element “<ChannelChangeInfo>” is described. In the XML element of “<ChannelChangeInfo>”, data indicating the maximum number of MPEG streams distributed per channel is specified in “@NumberOfStreamsPerChannel”. In addition, the multicast address of the scheduled distribution time information transmission server 30 that can acquire IDR picture distribution scheduled time information of all MPEG streams distributed from the IPTV service is designated as “<IPMulticastAddress>”. The example shown in FIG. 9 shows that a maximum of two MPEG streams are distributed per channel, and IDR picture distribution scheduled time information can be acquired from the port number 1500 at the address 224.0.1.0.

  As described above, in the content distribution method according to the present embodiment, a plurality of compressed data streams having different appearance timings of reference compressed video data are distributed to one channel. These compressed data streams differ only in the appearance timing of the reference compressed video data, and the encoding conditions other than the appearance timing are the same. Therefore, the information processing apparatus 20 that is a terminal can minimize the waiting time until the reference compressed video data is received by selecting a suitable stream from a plurality of compressed data streams. Images can be displayed quickly.

<About information processing method>
Subsequently, an information processing method executed by the information processing apparatus 20 according to the present embodiment will be described in detail with reference to FIGS. FIG. 10 is a flowchart for explaining an information processing method performed by the information processing apparatus 20 according to the present embodiment.

  When the power of the information processing apparatus 20 according to the present embodiment is turned on by a viewer (user) or when a TV service is selected from the IPTV service menu or the like, the information processing apparatus 20 according to the present embodiment. Starts the TV viewing process.

  First, the information processing apparatus 20 acquires a broadcast discovery record from an IPTV application server (not shown) such as an EPG server by using a CPU, a ROM, a RAM, a communication apparatus, and the like provided in the apparatus (step). S101). This broadcast discovery record is described based on the protocol defined by DVB-IP as shown in FIG. 9, and the information processing apparatus 20 can acquire channel information corresponding to each channel. If the channel information does not change frequently, the channel information already acquired from the IPTV service may be used.

  Next, the information processing device 20 uses the CPU, ROM, RAM, communication device, and the like provided in the device to issue an IGMP message for requesting the start of distribution of IDR picture distribution scheduled time information, and this distribution Reception of a multicast packet related to the scheduled time information is started (step S103).

  11A and 11B are IGMP message formats for performing multicast data delivery control from the information processing apparatus 20 in IGMP version 3 defined by RFC3376. 12A and 12B are explanatory diagrams for explaining an example of the IGMP message according to the present embodiment.

  When the information processing apparatus 20 joins or leaves the multicast group, the report format IGMP message shown in FIG. 11A is used. In addition, there is an IGMP message in a query format for confirming that the multicast router has joined the multicast group, but a detailed description of the specifications of the IGMP will be omitted.

  As shown in FIG. 11A, in the IGMP message in the report format, the number of records included in the report is specified in the column “Number of Group Records”, and then the number of specified records is displayed. “Group Record” is described for each minute. FIG. 11B shows the format of each group record. As shown in FIG. 11B, the format of the group record includes a “Record Type” field. By entering a predetermined value in this field, it is possible to specify joining or leaving a multicast group. It is.

  In order to instruct the information processing apparatus 20 to start distribution of a multicast group that distributes IDR picture distribution scheduled time information, an IGMP message as shown in FIG. 12A is issued. The value “1” specified in the “Record Type” field indicates MODE_IS_INCLUDE, and the multicast address (224.0.1.0 in the example) acquired in step S101 described above is assigned to the multicast group. Indicates participation. By participating in the multicast group by IGMP, the scheduled distribution time information transmission server 30 distributes the IDR picture distribution scheduled time information to the information processing apparatus 20 periodically (for example, every 10 milliseconds). The information processing apparatus 20 receives the IDR picture delivery scheduled time information, and always keeps the latest information in the storage unit 209.

  Subsequently, the channel selection unit 201 of the information processing apparatus 20 performs initial setting of channel selection information (step S105). The channel selection information to be initially set includes four parameters “CurrentChan”, “CurrentAddress”, “SelectChan”, and “SelectAddr”.

  The parameter “CurrentChan” is a parameter indicating the position of the channel currently selected by the information processing apparatus 20, and the parameter “CurrentAddress” is a parameter indicating the multicast address to which the currently selected channel is distributed. . In the initial setting, both these two parameters are set to -1. This is a value indicating that channel selection is not currently performed. The parameter “SelectChan” is a parameter indicating the channel position of the channel to be selected from now on, and the parameter “SelectAddr” is a parameter indicating the multicast address to which the MPEG2-TS stream of the selected channel is distributed. In the initial setting, 1 is set to “SelectChan”. If the terminal holds the previously selected channel information, the channel position is designated. “SelectAddress” is set to −1 to perform initialization.

Subsequently, the channel selection section 201 notifies the channel indicated in the parameter "Sel e ctChan" to the content acquisition section 203, the content acquisition section 203 performs selection processing of the channel (step S107). The channel selection process will be described in detail later. By this processing, the video of the channel is displayed on the screen of the display unit (not shown) of the information processing apparatus 20, and the sound is reproduced from the speaker.

  When the channel selection process is completed, the channel selection unit 201 updates the channel information related to the currently selected channel (step S109). That is, the value of the parameter “SelectChan” is set to the parameter “CurrentChan”, and the value of the parameter “SelectAddr” is set to the parameter “CurrentAddr”.

  Subsequently, the channel selection unit 201 of the information processing apparatus 20 waits for an input of a user operation (step S111).

  Here, when the user inputs an end operation such as pressing a power-off button on the remote controller (step S113), the channel selection unit 201 generates a signal corresponding to the input operation, and step S123. The process proceeds to the channel reception end process. If the user inputs an operation to switch channels (step S115), the process proceeds to step S117 described later. If not, the process returns to step S111 to wait for a user operation. Actually, in addition to these controls, there are other user operation processes such as volume control, but the description in FIG. 10 is omitted.

  When the channel switching operation, for example, the channel up button of the remote controller is operated by the user, the channel selection unit 201 adds 1 to the parameter “SelectChan”, and when the channel down button is operated, the channel selection unit 201 The selection unit 201 subtracts 1 from the parameter “SelectChan” (step S117). Here, the channel selection unit 201 performs control so that the value of the parameter “SelectChan” does not exceed a negative value or a total channel value. When the remote controller or the like has a button or the like that can directly select a channel number or the like, the channel selection unit 201 sets a channel position corresponding to the selected channel number in the parameter “SelectChan”. Thereafter, the channel selection unit 201 notifies the content acquisition unit 203 of information regarding the newly set parameters.

  The content acquisition unit 201 selects a channel designated by this parameter based on the value of the parameter “SelectChan” notified from the channel selection unit 201 (step S119). As a result, the newly selected channel is reproduced from the screen of the information processing apparatus 20 and the speaker. As described in step S107, details of the channel selection process will be described later.

  After that, the channel selection unit 201 updates the channel information regarding the currently selected channel (step S121), similarly to step S109.

  Subsequently, the channel selection unit 201 of the information processing apparatus 20 waits for an input of a user operation and TV viewing continues.

  On the other hand, when the user operation is an end operation, the content acquisition unit 203 performs a channel reception end process (step S123). The channel reception end process will be described in detail later.

Thereafter, the information processing device 20 uses the CPU, ROM, RAM, communication device, and the like provided in the device to stop the distribution of the IDR picture distribution scheduled time information started in step S103, and the distribution scheduled time information The multicast packet reception is also terminated (step S125). The information processing apparatus 20 can stop the distribution by transmitting an IGMP message as shown in FIG. 12B. Here, “RecordType = 2” in FIG. 12B indicates that it is MODE_IS_EX CL UDE, which means leaving from the multicast group of 224.0.1.0.

  Subsequently, the information processing apparatus 20 ends the TV viewing and returns to another IPTV service menu or shifts to another function of the terminal.

[Channel selection processing]
Next, the channel selection process performed by the information processing apparatus 20 according to the present embodiment will be described in detail with reference to FIG. FIG. 13 is a flowchart for explaining channel tuning processing in the information processing method according to the present embodiment.

  The acquisition stream selection unit 205 that has received a request from the content acquisition unit 203 acquires channel information corresponding to the parameter “SelectChan” from the latest scheduled IDR picture distribution time information recorded in the storage unit 209 or the like (step S201). ).

  More specifically, the acquisition stream selection unit 205 first acquires the multicast address of the channel from the broadcast discovery record. In the example illustrated in FIG. 9, when the parameter “SelectChan” is set to 1, “<SingleService>” at the head position is the corresponding channel information. In this channel information “<ServiceLocation>”, as shown in FIG. 9, two multicast addresses are described. In the example of FIG. 9, 224.0.1.1 is set to the parameter “Address1”, and 224.0.1.2 is set to the parameter “Address2”.

  Next, the acquisition stream selection unit 205 searches for the scheduled delivery time information record of each multicast address from the latest scheduled IDR picture delivery time information, and sets the scheduled IDR picture delivery times to “NextTime1” and “NextTime2”, respectively. . However, the delivery time of the IDR picture is a time sent from each delivery unit of the content server 10, and there is a delay until the leading MPEG2-TS packet including the IDR picture reaches the information processing apparatus 20. For this reason, if the delay time is not significantly negligible, it is necessary to appropriately add the delay time to “NextTime1” and “NextTime2” in accordance with the network conditions from the content server 10 to the information processing apparatus 20.

  Next, the acquisition stream selection unit 205 calculates a multicast distribution switching completion prediction time (step S203). The expected switching completion time is an expected time until the first packet of a newly joined multicast group arrives when an IGMP message is immediately issued to start or switch distribution. The expected switching completion time “SwitchTime” can be obtained by adding the required switching time to the current time. Here, the required switching time is the sum of the following times.

(1) Time required for the information processing apparatus 20 to issue an IGMP message (2) Time required for the IGMP message to reach the edge switch (for example, DSLAM) performing the IGMP proxy (3) The edge switch The time required to stop the distribution of the multicast group packet currently distributed to the access network to which the terminal is connected and start the distribution of the newly joined multicast group packet (4) The edge switch distributes Time required for the first packet that starts the packet to reach the information processing device 20 (5) Time required for the information processing device 20 to receive and store the first packet

  The values of (1) to (5) depend on the IPTV service network and the performance of the information processing apparatus 20, and the maximum value of the required switching time corresponding to the conditions of the information processing apparatus 20 and the network is determined in advance. It is assumed that 20 is set. For example, the maximum switching time can be set to about 20 milliseconds.

  In (3) above, when a plurality of information processing devices 20 are connected to the subscriber's home, it is determined whether other information processing devices 20 have joined the same multicast group when stopping packet distribution. The time required for confirmation is also included. This confirmation is usually done by periodic IGMP query messages as specified in RFC-3376. In addition, when a plurality of information processing apparatuses 20 join individual multicast groups, that is, when different channels are viewed on the plurality of information processing apparatuses 20, multicast for a plurality of channels is sent to the access network. A sufficient data bandwidth is required. For this purpose, for example, QoS (Quality of Service) control such as IMS (IP Multimedia Subsystem) can be used to guarantee the bandwidth of the network.

  Hereinafter, in steps S <b> 205 to S <b> 221, it is determined which of the multicast addresses of the channel to be selected is selected, and the determination of the timing at which IGMP is to be issued for the start or switching of distribution. We are carrying out. The acquisition stream selection unit 205 according to the present embodiment determines address selection and timing determination based on the following four conditions.

(A) If the reception of the IP packet including the IDR picture is not in time at the switching completion prediction time SwitchTime, the multicast address is not selected.
(B) A multicast address that can receive an IP packet including an IDR picture earliest is selected. Under this condition, high-speed channel switching can be realized.
(C) When the selection of the results of (A) and (B) is not performed, the process is performed from step S201 after waiting for the reception of the next IDR picture distribution scheduled time information packet.
(D) Although the selection of the results of (A) and (B) is performed, if the difference between the IP packet arrival time including the IDR picture and the switching completion scheduled time SwitchTime is large, the distribution is not started or switched, The process from step S201 is performed after waiting for the next IDR picture delivery scheduled time information packet.

  The condition (D) is set for the following reason. That is, even if the display is started or switched immediately, the content reproduction unit 207 of the information processing device 20 cannot expand the video until the IDR picture arrives after the reception of the packet is started. Therefore, a period during which screen display is not generated (hereinafter referred to as a blackout period) occurs. According to the condition (D), the blackout period can be shortened. In order to start or switch seamlessly, it is desirable to make the blackout period as short as possible, but it is necessary to make it longer than the packet transmission cycle at the scheduled delivery time of the IDR picture. Therefore, the maximum value of the blackout period (hereinafter referred to as blackout allowable time) is preferably set to 40 milliseconds, for example.

  Hereinafter, the conditions (A) to (D) will be described with reference to specific examples. FIG. 14A and FIG. 14B are explanatory diagrams for explaining case classification for selection of multicast addresses, and FIG. 15 is an explanatory diagram for explaining case classification for start or switching timing.

  First, with reference to FIGS. 14A and 14B, how the conditions (A) to (C) are applied to the six specific cases shown in these drawings will be described.

  From the condition (A), in the case (case 2) shown in FIG. 14A, “Address 1” is selected, and in the case (4), “Address 2” is selected. In addition, according to the condition (A), multicast addresses are not switched in (Case 5) and (Case 6) shown in FIG. 14B. Therefore, based on the condition (C), the process from step S201 is performed after waiting for reception of the next IDR picture delivery scheduled time information packet.

  Further, according to the condition (B), “Address 1” is selected in (Case 1) shown in FIG. 14A, and “Address 2” is selected in (Case 3).

  The determination based on the conditions (A) to (C) as described above corresponds to steps S205 to S217 in FIG.

  Here, when “Address 1” is selected according to the conditions (A) and (B), the following values are set as the channel selection information. That is, “Address1” is set to the parameter “SelectAddr” indicating the selected multicast address, and “NextTime1” is set to the parameter “NextTime” indicating the scheduled delivery time of the IDR picture (step S211).

  Similarly, when “Address 2” is selected according to the conditions (A) and (B), the following values are set as the channel selection information. That is, “Address2” is set to the parameter “SelectAddr” indicating the selected multicast address, and “NextTime2” is set to the parameter “NextTime” indicating the scheduled delivery time of the IDR picture (step S215).

  Next, the condition (D) will be described with reference to FIG. 15 with a specific example. This condition determination corresponds to step S219 shown in FIG.

  According to the conditions (A) and (B), since neither multicast address is selected in (Case 1) shown in FIG. 15, the multicast address is not switched according to the condition (C). In the case 2 shown in FIG. 15, the blackout time after switching is greater than an allowable value (for example, 40 milliseconds), and multicast address switching is performed according to the condition (D). Absent. In the case of (Case 3) shown in FIG. 15, since the condition (D) is not satisfied, the selected multicast address is switched.

  When the acquisition stream selection unit 205 selects the multicast address of the selected channel and determines the timing based on the condition determination as described above, the channel selection result is transferred from the acquisition stream selection unit 205 to the content acquisition unit 203. Is transmitted. The content acquisition unit 203 issues an IGMP message based on the channel selection result, and switches distribution of multicast packets distributed to the access network to which the information processing apparatus 20 is connected (step S221). This IGMP message is issued in the IGMP version 3 report format defined in RFC-3376 shown in FIGS. 11A and 11B.

Examples of IGMP packets are shown in FIGS. 16A to 16C. FIG. 16A shows the case where the parameter “CurrentChan” is −1, that is, there is no multicast that has already been distributed. In Figure 16A, to the multicast group of parameter "SelectChan" multicast address (1 in the example) "SelectAddress" (224.0.1.1 in the example), and specify the Reco rd Type = 1 (MODE_IS_INCLUDE) This means joining a multicast address to start multicast data distribution. FIG. 16B shows a case where the parameter “CurrentChan” is other than −1, that is, there is a multicast address that has already been distributed. For example, in the multicast group of “CurrentAddress” (example 224.0.1.0) of “CurrentChannel” (example 1), RecordType = 2 (MODE_IS_EXCLUDE) is designated to stop distribution, and “SelectChannel” ( In the example, the start of distribution is instructed by specifying RecordType = 1 (MODE_IS_INCLUDE) for the multicast group of the multicast address “SelectAddress” of 2) (224.0.1.4 in the example).

  In IMGP version 3, as shown in FIG. 16B, since instructions can be collectively performed by using one IGMP packet, there is an advantage that it is possible to implement such that a multicast address is not distributed redundantly to the access network at the time of switching. .

  As a result, the content acquisition unit 203 starts to receive the multicast packet of “SelectAddress” (step S223).

  Since it is necessary to wait for the maximum switching time until the switching of distribution is completed, when the multicast packet is not received, the process waits (step S225). If there is a risk of loss of IGMP packets in the network, send multiple packets in step S221, or provide a timeout in step S225 to perform IGMP packet retransmission processing. Also good.

  As a result of the standby in step S225, since the multicast distribution switching has been completed after the standby, when there is a channel that has been previously selected, the content acquisition unit 203 sets the multicast packet of the corresponding “CurrentAddress”. Reception ends (step S227).

  Thereafter, the content acquisition unit 203 transmits the received multicast packet to the content reproduction unit 207, and the content reproduction unit 207 starts reproduction of the MPEG2-TS stored in the multicast packet of the channel that has newly started reception. (Step S229). Actually, after receiving the MPEG2-TS packet including the IDR picture, the video is displayed on the display unit (not shown) of the information processing apparatus 20. In this way, the channel selection process ends, and IPTV television viewing continues as it is.

[About channel reception end processing]
Next, the channel reception end process performed by the information processing apparatus 20 will be described in detail with reference to FIG.

First, the content acquisition unit 203 stops the multicast packet currently being received. Receive a multicast packet can be stopped by sending an IGMP report message shown in FIG. 16C (step S301). As illustrated in FIG. 16C, the content acquisition unit 203 transmits an IGMP message by specifying RecordType = 2 (MODE_IS_EXCLUDE) for the multicast group of the parameter “CurrentAddress” (224.0.1.4 in the example). By doing so, multicast packet delivery can be stopped.

  Next, the content acquisition unit 203 ends multicast reception (step S303). Thereafter, the content reproduction unit 207 ends the reproduction of the MPEG2-TS stream (step S305). By performing such processing, the channel reception end processing is completed.

  Heretofore, the high-speed channel switching of the IPTV system according to the present embodiment has been described. In addition to the above-described embodiment, according to the present invention, it is easy to devise another embodiment. For example, another embodiment as follows can be considered.

  In the embodiment according to the present invention, the channel selection process shown in FIG. 13 is interrupted halfway in order to cancel the channel switching or change the channel to be selected by interruption by a user operation during the channel switching process. It is easy to implement the processing.

  In the embodiment according to the present invention, H.264 Although the case of H.264 / AVC has been described, the present invention can be easily applied to an IPTV system using MPEG2 video compression by considering an IDR picture as an I picture even when MPEG2 video compression is used. Is possible.

  Further, in the embodiment according to the present invention, the compressed video data and the audio data are multiplexed and transmitted by MPEG2-TS. However, the present invention can be applied even when the compressed video and audio data are individually distributed by IP packet. By applying this, it is possible to easily realize an IPTV system that realizes high-speed channel switching by switching IP packet distribution.

  Further, in the embodiment according to the present invention, only one video / audio signal is multiplexed as compressed video data and audio data in MPEG2-TS and stored in an IP packet, and then the distribution is switched. However, compressed video data and audio data of a plurality of video / audio signals are multiplexed and distributed in MPEG2-TS, and compressed video / audio packets corresponding to the selected video / audio signal are transmitted through the network path to the information processing apparatus 20. By only filtering and transmitting, it is possible to easily realize an IPTV system that realizes high-speed channel switching similar to the present embodiment.

  Further, in the embodiment according to the present invention, the scheduled delivery time information of the IDR picture is transmitted to the information processing apparatus 20 which is a terminal only for one IDR picture to be transmitted next. Here, if the scheduled delivery time for a plurality of IDR pictures is specified and transmitted in the scheduled delivery time record of the IDR picture, the information processing apparatus 20 more strictly selects the multicast address at the time of channel selection. It is obvious that we can do it.

  Further, in the embodiment according to the present invention, by using the IGMP version 3 function and performing multicast group distribution switching with one IGMP packet, the packets are not duplicated and distributed to the access network during the switching. The data bandwidth used by the IPTV system in the access network is limited. However, even when IGMP version 2 is used, the data band used in the IPTV system is similarly limited by processing to join the multicast group to be switched after leaving the multicast group and stopping distribution. It is possible to do.

  In the embodiment according to the present invention, the content server 10 encodes a plurality of MPEG2-TS streams of each channel and distributes them via the core network. Here, in an environment where the bandwidth of the core network is limited, the following can be performed. That is, the content server 10 distributes one encoded packet for each channel in the core network, and arranges another content server such as an edge server or an edge router in the middle of the distribution network such as an access network. These other content servers generate and distribute MPEG2-TS streams having different IDR picture distribution timings based on the video and audio signals for the received MPEG2-TS streams. By doing so, it is possible to realize a high-speed channel switch similar to the ITPV system described in the present embodiment while limiting the bandwidth of the core network.

  In the embodiment according to the present invention, the IDR picture distribution scheduled time information is transmitted to the information processing apparatus 20 that is a terminal, and the information processing apparatus 20 selects the multicast address of the channel and transmits the multicast packet to be transmitted to the access network. Judgment of switching timing was made. Here, the scheduled distribution time of the IDR picture is distributed to an edge switch or edge router that performs IGMP snooping that actually performs distribution switching, and the information processing apparatus 20 immediately starts the channel tuning process. Instruct multicast delivery switching. The edge switch and the edge router that have received the instruction use the IDR picture distribution schedule information to control the selection of the multicast address and the distribution switching timing in the same judgment as the channel selection process of the information processing apparatus shown in FIG. May be.

  In this case, the network devices such as edge switches and edge routers are processing units (for example, a content acquisition unit and an acquisition stream selection unit) having the same functions as the processing units included in the information processing apparatus 20 illustrated in FIG. And a distribution control unit that distributes the acquired compressed data stream to the information processing apparatus 20 via a predetermined network. A network device having such a processing unit can function as an edge server.

<About hardware configuration>
Next, the hardware configuration of the content server 10 and the information processing apparatus 20 according to each embodiment of the present invention will be described in detail with reference to FIG. FIG. 18 is a block diagram for explaining a hardware configuration of the content server 10 and the information processing apparatus 20 according to the present embodiment.

  The content server 10 and the information processing apparatus 20 mainly include a CPU 701, a ROM 703, a RAM 705, a host bus 707, a bridge 709, an external bus 711, an interface 713, an input device 715, an output device 717, A storage device 719, a drive 721, a connection port 723, and a communication device 725 are provided.

  The CPU 701 functions as an arithmetic processing unit and a control unit, and in accordance with various programs recorded in the ROM 703, the RAM 705, the storage device 719, or the removable recording medium 727, the entire operation in the content server 10 and the information processing device 20 or a part thereof. To control. The ROM 703 stores programs used by the CPU 701, calculation parameters, and the like. The RAM 705 primarily stores programs used in the execution of the CPU 701, parameters that change as appropriate during the execution, and the like. These are connected to each other by a host bus 707 constituted by an internal bus such as a CPU bus.

  The host bus 707 is connected to an external bus 711 such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge 709.

  The input device 715 is an operation unit operated by the user, such as a mouse, a keyboard, a touch panel, a button, a switch, and a lever. The input device 715 may be, for example, remote control means (so-called remote control) using infrared rays or other radio waves, or a mobile phone, a PDA, or the like corresponding to the operation of the content server 10 and the information processing device 20. The external connection device 729 may be used. Furthermore, the input device 715 is configured by, for example, an input control circuit that generates an input signal based on information input by the user using the above-described operation means and outputs the input signal to the CPU 701. The user of the content server 10 or the information processing device 20 can input various data or instruct processing operations to the content server 10 or the information processing device 20 by operating the input device 715. .

  The output device 717 acquires, for example, a display device such as a CRT display device, a liquid crystal display device, a plasma display device, an EL display device, and a lamp, a sound output device such as a speaker and a headphone, a printer device, a mobile phone, and a facsimile. It is comprised with the apparatus which can notify the information which carried out visually or audibly to a user. The output device 717 outputs, for example, results obtained by various processes performed by the content server 10 and the information processing device 20. Specifically, the display device displays the results obtained by various processes performed by the content server 10 and the information processing device 20 as text or images. On the other hand, the audio output device converts an audio signal composed of reproduced audio data, acoustic data, and the like into an analog signal and outputs the analog signal.

  The storage device 719 is a data storage device configured as an example of a storage unit of the content server 10 and the information processing device 20, and includes, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical It is comprised by a storage device or a magneto-optical storage device. The storage device 719 stores programs executed by the CPU 701 and various data, and acoustic signal data and image signal data acquired from the outside.

  The drive 721 is a recording medium reader / writer, and is built in or externally attached to the content server 10 and the information processing apparatus 20. The drive 721 reads information recorded on a removable recording medium 727 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 705. The drive 721 can also write a record to a removable recording medium 727 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory. The removable recording medium 727 is, for example, a DVD medium, an HD-DVD medium, a Blu-ray medium, a compact flash (registered trademark) (CompactFlash: CF), a memory stick, or an SD memory card (Secure Digital memory card). Further, the removable recording medium 727 may be, for example, an IC card (Integrated Circuit card) on which a non-contact type IC chip is mounted, an electronic device, or the like.

  The connection port 723 is, for example, a USB (Universal Serial Bus) port, i. Directly connect devices such as an IEEE 1394 port such as Link, a small computer system interface (SCSI) port, an RS-232C port, an optical audio terminal, and a high-definition multimedia interface (HDMI) port to the content server 10 and the information processing apparatus 20. It is a port for. By connecting the external connection device 729 to the connection port 723, the content server 10 and the information processing apparatus 20 directly acquire the audio signal data and the image signal data from the external connection device 729, or send the audio signal to the external connection device 729. Provide data and image signal data.

  The communication device 725 is a communication interface configured with, for example, a communication device for connecting to the communication network 731. The communication device 725 is, for example, a wired or wireless LAN (Local Area Network), Bluetooth, or WUSB (Wireless USB) communication card, a router for optical communication, an ADSL (Asymmetric Digital Subscriber Line) router, or various types. It is a modem for communication. The communication device 725 can transmit and receive signals and the like according to a predetermined protocol such as TCP / IP, for example, with the Internet or other communication devices. Further, the communication network 731 connected to the communication device 725 is configured by a wired or wirelessly connected network, and may be, for example, the Internet, a home LAN, infrared communication, radio wave communication, satellite communication, or the like. .

  Heretofore, an example of the hardware configuration capable of realizing the functions of the content server 10 and the information processing apparatus 20 according to each embodiment of the present invention has been shown. Each component described above may be configured using a general-purpose member, or may be configured by hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration to be used as appropriate according to the technical level at the time of carrying out this embodiment.

  The content server 10 according to each embodiment of the present invention can be provided as a program having the following functions. This program corresponds to a computer with reference compressed video data that is data that can start decoding of subsequent video signals without depending on previous data in time-series data generated by compression of video signals. An encoding step for encoding a single input video / audio content and generating a plurality of compressed data streams from the single video / audio content so that the delivery times of the video frame and the reference compressed data are different from each other; And a step of simultaneously delivering each of the plurality of compressed data streams.

  The computer program is stored in a storage unit included in the computer, and is read and executed by a CPU included in the computer, thereby causing the computer to function as the content server 10 described above. A computer-readable recording medium in which a computer program is recorded can also be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

  Further, the information processing apparatus 20 according to each embodiment of the present invention can be provided as a program having the following functions. This program corresponds to a computer with reference compressed video data that is data that can start decoding of subsequent video signals without depending on previous data in time-series data generated by compression of video signals. Compression acquired from a plurality of compressed data streams that are distributed for a plurality of compressed data streams in which one video and audio content is encoded so that the distribution times of the video frame and the reference compressed data are different from each other This is a program for executing an acquisition stream selection step of selecting a data stream and a content acquisition step of acquiring a selected compressed data stream.

  The computer program is stored in a storage unit included in the computer, and is read and executed by a CPU included in the computer, thereby causing the computer to function as the information processing apparatus 20 described above. A computer-readable recording medium in which a computer program is recorded can also be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

  As described above, according to each embodiment of the present invention, a high-speed channel switch can be provided to a user with high-quality video even in an environment where the data bandwidth of an access network to an IPTV subscriber house is limited. The IPTV system can be realized without installing expensive network devices and special content servers in the vicinity of the access network.

  Further, according to each embodiment of the present invention, it is possible to minimize the blackout period in which no video is displayed at the time of channel switching, or the time to display the video of the channel before switching in a stopped state, Viewers can be provided with seamless channel switching.

  Also, according to each embodiment of the present invention, since any channel can be viewed regardless of which multicast stream assigned to each channel is received, the IPTV coexisting with a terminal (existing terminal) that does not select a multicast address. A system can be constructed.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is explanatory drawing for demonstrating the content delivery system which concerns on the 1st Embodiment of this invention. It is a block diagram for demonstrating the structure of the content server which concerns on the same embodiment. It is a block diagram for demonstrating the structure of the information processing apparatus which concerns on the embodiment. 4 is an explanatory diagram for explaining a positional relationship of IDR pictures in an MPEG2-TS stream output from a content server according to the embodiment. FIG. It is explanatory drawing for demonstrating the format of the UDP packet which the content server concerning the embodiment sends out. It is explanatory drawing for demonstrating the calculation method of the delivery scheduled time which the content server which concerns on the embodiment implements. It is explanatory drawing for demonstrating the specific example of the reference | standard compressed video data delivery scheduled time information which concerns on the same embodiment. It is explanatory drawing for demonstrating the data format of the broadcast discovery record of DVB-IP. It is explanatory drawing for demonstrating the example at the time of expressing a broadcast discovery record in XML. It is a flowchart for demonstrating the information processing method which concerns on the embodiment. It is explanatory drawing for demonstrating the format of an IGMP message. It is explanatory drawing for demonstrating the format of an IGMP message. It is explanatory drawing for demonstrating an example of the IGMP message which concerns on the embodiment. It is explanatory drawing for demonstrating an example of the IGMP message which concerns on the embodiment. It is a flowchart for demonstrating the channel selection process in the information processing method which concerns on the embodiment. It is explanatory drawing for demonstrating case classification about the selection of the multicast address in the information processing method which concerns on the embodiment. It is explanatory drawing for demonstrating case classification about the selection of the multicast address in the information processing method which concerns on the embodiment. It is explanatory drawing for demonstrating case division of the start or switching timing in the information processing method which concerns on the embodiment. It is explanatory drawing for demonstrating an example of the IGMP message which concerns on the embodiment. It is explanatory drawing for demonstrating an example of the IGMP message which concerns on the embodiment. It is explanatory drawing for demonstrating an example of the IGMP message which concerns on the embodiment. It is a flowchart for demonstrating the channel reception end process in the information processing method which concerns on the embodiment. It is a block diagram for demonstrating the hardware constitutions of the content server and information processing apparatus which concern on the embodiment. It is explanatory drawing for demonstrating a general IPTV system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Content delivery system 10 Content server 11A 1st process part 11B 2nd process part 20 Information processing apparatus 30 Scheduled delivery time information transmission server 40 Reference clock server 101 1st encoding part 103 2nd encoding part 105 1st delivery part 107 Second distribution unit 109, 111 Storage unit 201 Channel selection unit 203 Content acquisition unit 205 Acquisition stream selection unit 207 Content playback unit 209 Storage unit

Claims (15)

In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video A plurality of encoding units that encode video and audio content so that the data distribution times are different from each other, and generate a plurality of compressed data streams from the one video and audio content;
A plurality of distribution units that acquire and distribute one compressed data stream generated by the one encoding unit from one different encoding unit;
Bei to give a,
Each of the plurality of encoding units encodes the video and audio content so that compression and encoding conditions are the same,
Each of the plurality of distribution units outputs reference compressed video data distribution scheduled time information related to a distribution planned time at which the generated reference compressed video data is distributed,
The reference compressed video data distribution scheduled time information is a content used when a device capable of acquiring the plurality of distributed compressed data streams selects a compressed data stream acquired from the plurality of compressed data streams. server. The clock in the content server is synchronized with a reference clock provided from a reference clock server located outside the content server,
The content server according to claim 1, wherein the plurality of encoding units measure the reference compressed video data distribution scheduled time based on the synchronized clocks.   The content server according to claim 1, wherein a plurality of devices including one of the encoding units and one of the distribution units are connected in parallel.   The content server according to claim 1, wherein the plurality of encoding units and the plurality of distribution units are provided in the same device. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video From the plurality of encoding units that encode the video and audio content so that the data delivery times are different from each other and generate a plurality of compressed data streams from the one video and audio content, and the one encoding unit different from each other, It delivers acquire one of the compressed data stream encoding unit of the one-generated e Bei a plurality of delivery unit, the respective plurality of encoding unit, compression and encoding conditions the same As described above, the video / audio contents are encoded, and each of the plurality of distribution units is scheduled to be distributed in which the generated reference compressed video data is distributed. From among the multiple compressed data streams by the content server to output the reference compressed video data scheduled distribution time point information about the time to deliver, an acquisition stream selection section for selecting the compressed data stream to be acquired,
A content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit;
Bei to give a,
The acquisition stream selection unit acquires the reference compressed video data distribution scheduled time information output from the content server, and selects the compressed data stream to be acquired based on the acquired reference compressed video data distribution scheduled time information , the information processing apparatus. The acquisition stream selection unit is a switch that completes switching of the acquired compressed data stream by using a switching time required for switching the display to the acquired compressed data stream and a time at which selection processing of the acquired stream is started. 6. The information processing apparatus according to claim 5 , wherein a predicted completion time is calculated, and the compressed data stream having the latest reference compressed video data distribution scheduled time after the calculated switching completion predicted time is selected. The acquisition stream selection section, when the reference compressed video data scheduled distribution time point corresponding to each compressed data stream is before the all the switching completion expected time, you do not select any of the data streams, in claim 6 The information processing apparatus described. The acquisition stream selection unit displays the selection result of the compressed data stream when the time interval between the scheduled delivery time and the expected switching completion time of the selected compressed data stream is equal to or less than a predetermined threshold. The information processing apparatus according to claim 6 , which notifies the content acquisition unit. The information processing apparatus according to claim 5 , wherein the content acquisition unit performs switching control of the compressed data stream selected by the acquisition stream selection unit by IGMP. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video From the plurality of encoding units that encode the video and audio content so that the data delivery times are different from each other and generate a plurality of compressed data streams from the one video and audio content, and the one encoding unit different from each other, It delivers acquire one of the compressed data stream encoding unit of the one-generated e Bei a plurality of delivery unit, the respective plurality of encoding unit, compression and encoding conditions the same As described above, the video / audio contents are encoded, and each of the plurality of distribution units is scheduled to be distributed in which the generated reference compressed video data is distributed. From among the multiple compressed data streams by the content server to output the reference compressed video data scheduled distribution time point information about the time to deliver, an acquisition stream selection section for selecting the compressed data stream to be acquired,
A content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit;
A distribution control unit that distributes the acquired compressed data stream to an information processing apparatus connected via a network;
Bei to give a,
The acquisition stream selection unit acquires the reference compressed video data distribution scheduled time information output from the content server, and selects the compressed data stream to be acquired based on the acquired reference compressed video data distribution scheduled time information , Network equipment. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video An encoding step of encoding one video / audio content input so that data distribution times are different from each other, and generating a plurality of compressed data streams from the one video / audio content;
Each generated the plurality of compressed data streams and distribution step of distributing simultaneously,
Only including,
In the encoding step, the video and audio content is encoded so that the compression and encoding conditions are the same,
In the distribution step, reference compressed video data distribution scheduled time information related to a distribution scheduled time at which the generated reference compressed video data is distributed is output,
The reference compressed video data distribution scheduled time information is a content used when a device capable of acquiring the plurality of distributed compressed data streams selects a compressed data stream acquired from the plurality of compressed data streams. Delivery method. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video The compressed data stream to be acquired is selected from the plurality of compressed data streams that are distributed with respect to the plurality of compressed data streams in which one video / audio content is encoded so that the data distribution times are different from each other. An acquisition stream selection step,
A content acquisition step of acquiring the selected compressed data stream;
Only including,
The compressed data stream is encoded with the video and audio content so that the compression and encoding conditions are the same, and the reference compressed video data relating to the scheduled distribution time at which the generated reference compressed video data is distributed. Distribution scheduled time information is distributed together with the compressed data stream,
In the acquisition stream selection step, the reference compressed video data distribution scheduled time information distributed is acquired, and the compressed data stream to be acquired is selected based on the acquired reference compressed video data distribution scheduled time information. Processing method. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video The compressed data stream to be acquired is selected from the plurality of compressed data streams that are distributed with respect to the plurality of compressed data streams in which one video / audio content is encoded so that the data distribution times are different from each other. An acquisition stream selection step,
A content acquisition step of acquiring the selected compressed data stream;
A distribution control step of distributing the acquired compressed data stream to an information processing apparatus connected via a network;
Only including,
The compressed data stream is encoded with the video and audio content so that the compression and encoding conditions are the same, and the reference compressed video data relating to the scheduled distribution time at which the generated reference compressed video data is distributed. Distribution scheduled time information is distributed together with the compressed data stream,
In the acquisition stream selection step, the reference compressed video data distribution scheduled time information being distributed is acquired, and the compressed data stream to be acquired is selected based on the acquired reference compressed video data distribution scheduled time information Delivery method. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video A plurality of encoding units that encode video and audio content so that the data distribution times are different from each other, and generate a plurality of compressed data streams from the one video and audio content;
A plurality of distribution units that acquire and distribute one compressed data stream generated by the one encoding unit from one different encoding unit;
Bei to give a,
Each of the plurality of encoding units encodes the video and audio content so that compression and encoding conditions are the same,
Each of the plurality of distribution units outputs reference compressed video data distribution scheduled time information related to a distribution planned time at which the generated reference compressed video data is distributed,
The reference compressed video data distribution scheduled time information is a content used when a device capable of acquiring the plurality of distributed compressed data streams selects a compressed data stream acquired from the plurality of compressed data streams. Server,
An acquisition stream selection unit that selects the compressed data stream to be acquired from the plurality of compressed data streams distributed by the content server;
A content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit;
Bei to give a,
The acquisition stream selection unit acquires the reference compressed video data distribution scheduled time information output from the content server, and selects the compressed data stream to be acquired based on the acquired reference compressed video data distribution scheduled time information An information processing device;
Including content distribution system. In the time-series data generated by the compression of the video signal, the video frame corresponding to the reference compressed video data, which is data that can start decoding of the subsequent video signal without depending on the previous data, and the reference compressed video A plurality of encoding units that encode video and audio content so that the data distribution times are different from each other, and generate a plurality of compressed data streams from the one video and audio content;
A plurality of distribution units that acquire and distribute one compressed data stream generated by the one encoding unit from one different encoding unit;
Bei to give a,
Each of the plurality of encoding units encodes the video and audio content so that compression and encoding conditions are the same,
Each of the plurality of distribution units outputs reference compressed video data distribution scheduled time information related to a distribution planned time at which the generated reference compressed video data is distributed,
The reference compressed video data distribution scheduled time information is a content used when a device capable of acquiring the plurality of distributed compressed data streams selects a compressed data stream acquired from the plurality of compressed data streams. Server,
An information processing apparatus that notifies the compressed data stream desired to be reproduced from among a plurality of compressed data streams distributed by the content server, and reproduces the acquired compressed data stream;
An acquisition stream selection unit that selects the compressed data stream to be acquired from the plurality of compressed data streams distributed by the content server based on the notification received from the information processing apparatus;
A content acquisition unit that acquires the compressed data stream distributed from the content server based on a selection result by the acquisition stream selection unit;
A distribution control unit that distributes the acquired compressed data stream to the information processing apparatus via a network;
Bei to give a,
The acquisition stream selection unit acquires the reference compressed video data distribution scheduled time information output from the content server, and selects the compressed data stream to be acquired based on the acquired reference compressed video data distribution scheduled time information , and network equipment,
Including content distribution system.

Images