JP2010062690A - Receiver and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the switching time of programs in a television being a receiver is determined by the state of a relay device of a router, a switch or the like on a network, in an IP broadcast using IP multicast communication. <P>SOLUTION: An IP broadcast receiver for receiving and reproducing a video content program by IP multicast communication, in the case of switching a program viewed by a user to another program, performs program switching as shortly and smoothly as possible by a method suitable to a band state of a network used by the user by switching orders as to which processing to be performed first between processing for receiving the next program desired to be viewed and processing for stopping receiving the program viewed so far. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The technical field relates to a receiving apparatus and a receiving method for receiving content distributed by a content distribution server via a communication network such as the Internet in response to a request from a viewer.

  In recent years, networks such as video-on-demand (VOD), which allows you to enjoy the title you want to watch, and IP (Internet Protocol) broadcasts where broadcast stations distribute broadcast programs over the Internet instead of broadcast waves, are not networks. In response to this, service forms for distributing video content have been fully developed, and in response to this, receivers such as televisions and recorders have been developed that are equipped with a network function and are equipped with a function of receiving and playing back video content as data packets.

  With regard to the above IP broadcast, Patent Document 1 has a problem of “providing a technology capable of switching channels quickly” (see Patent Document 1 [0008]), and a solution to this problem is “a plurality of contents multiplexed from a network”. A home gateway device capable of receiving the stream, and transmitting channel information corresponding to the desired content from the receiving terminal such as a television receiver to the home gateway device. Describes that the content corresponding to the channel information from the receiving terminal is extracted from the multiplexed content included in the received stream and supplied to the receiving terminal ”.

JP 2008-022393 A

  Internet protocol communication methods include unicast in which network devices send and receive IP packets on a one-to-one basis, and multicast in which the same IP packet is sent simultaneously from one device to multiple devices. IP broadcasting using an IP network In the service, content distribution is performed using an IP multicast mechanism.

  In the multicast communication method, the server sends a single packet destined for the multicast address to the router that serves as the distribution base, and the router that is distributed to the network for routing then sends the packet as needed. By copying and repeating the transfer, data packets are delivered to a large number of receivers. In this way, in the case of multicast communication, the load on the server is small, but routing procedures such as communication path determination and packet transfer destination registration become complicated, increasing the burden on relay devices such as routers and switches. Become.

  In addition, the receiver does not directly request the destination server to transmit the content data as in the case of unicast communication, but the desired data packet is sent to the router group that relays the data packet on the network. You must request that the be copied and transferred. There are IGMP (Internet Group Management Protocol), MLD (Multicast Listener Discovery), etc. as protocols used for this receiver to make a multicast reception request to the router, and the mechanism is as follows.

  First, the receiver obtains an IP multicast address indicating program content to be viewed from program distribution information separately. Then, it notifies the router in the content distribution IP network connected to itself of the IP multicast address indicating the desired content, and declares to receive the data packet of the content addressed to the multicast address (Listener Report) ).

  Based on the declaration, each router corresponding to the multicast in the IP network constructs a delivery path so that the data packet addressed to the corresponding multicast address is forwarded to the receiver that has transmitted the Listener Report, and the distribution source server Since the data packet is transferred from the receiver to the receiver and arrives, the receiver can receive the program content.

  In other words, the multicast address in IP broadcast corresponds to the program channel in the case of TV broadcast, and obtaining the multicast address of the video content that you want to view means that the program you want to watch at what time is broadcast from the electronic program guide etc. This is equivalent to the act of examining whether or not.

  By the way, the switching time of IP broadcast program channels is different from that of broadcasting, and the switching time may be affected by the state of the network. As described above, the content that is a video program is received by all network relay devices such as routers and layer 3 switches between the distribution source server and the final distribution destination receiver. After receiving the Report request and finishing the process of transferring the corresponding packet, the content finally reaches the receiver, and the receiver can take in the data and reproduce it. Also, for example, if there is even one router in the path that has a slow transfer start / stop process, the transfer processing time of the slowest device is reflected in the user's waiting time, no matter how fast the other device processes. End up.

  In particular, when switching the program content that has been viewed so far to another program content, the procedure is to stop the data packet transfer processing of the multicast address that has been received so far, and further transfer the packet of another multicast address. The load increases. That is, in multicast IP broadcasting, program content may not be switched smoothly depending on the state of the network, which is inconvenient for the user.

  In contrast to the above-described program switching in IP broadcasting, in Patent Document 1, a receiver acquires information on a plurality of programs corresponding to a plurality of contents in advance and performs a multicast reception procedure to transfer the plurality of contents data in advance. Keep it. A method is disclosed in which when a program switching request is received from a user, a program switching is quickly performed by selecting and reproducing a content corresponding to the switching request from a plurality of already received contents.

  However, when performing a multicast reception procedure for a plurality of programs and receiving a plurality of contents, there is a problem of bandwidth limitation of the network. In general, in the distribution of content via a network, the number of content programs that can be simultaneously received by a viewer is limited by the performance of the communication line and receiver used. Video content is transmitted as data packets over the network by the distribution server, reaches the receiver via devices such as routers and switches, and is taken into the receiver. The data transfer capacity per second is called the bit rate. This value is unique to each content file.

  The larger this value, the higher the quality such as the resolution and smoothness of the moving image, but the use band necessary for receiving data for viewing increases. If the network environment used by the viewer and the available bandwidth of the receiver are larger than the total bit rate of the received content, all content can be received and played back without any problem. On the other hand, if the data is smaller, there is a risk that the video may be disturbed or unviewable because the data does not reach the receiver or the reproduction process inside the receiver is not in time. Therefore, as IP broadcasts become widespread in the future, it is practically impossible to receive in advance tens or hundreds of program channels and switch the content to be reproduced from them.

  One embodiment of the present invention changes the order of multicast reception start processing and reception stop processing when the user performs an operation of switching the IP broadcast program being viewed.

  According to the above means, it is possible to improve the usability of switching the channel of the IP broadcast program.

  FIG. 1 shows that a content distribution server that distributes program content by an IP multicast communication method and an IP television that is an IP broadcast receiving apparatus of the present invention transmit and receive multicast data packets via a network relay device such as a router or a switch. It is an example showing a state.

  The content distribution network 1 is an Internet protocol communication network implemented using various network physical layers (including optical, wired, or wireless networks, for example), and transmits data packets from a transmission source such as a router, a switch, or a hub. It is assumed that communication control devices 41 to 44 for accurately delivering to the transmission destination are also included.

  The content distribution server 2 is a server system for providing an IP broadcast service that distributes program content to a plurality of receivers in a multicast manner.

  The IP TV 3 is a video receiving terminal having a function of receiving multicast distribution content and playing a program for viewers. The IP television 3 is connected to the home network 5, and the home network 5 distributes content outside the home via the router 44. Connected to network 1. Note that the IP television 3 does not necessarily include a display device or a speaker, and may be a receiving terminal (for example, a set top box (STB)) connected to an external display device or a speaker.

  In FIG. 1, video contents A, B, and C are distributed from the content distribution server 2 via the content distribution network 1. The IP television 3 issues a request for receiving the video content A using the IP multicast protocol, and the content is distributed by the switch 42 and the routers 43 and 44 transferring the data packet A to the IP television 3 in response to the reception request. Shows how this is done.

  FIG. 2 is a hardware block configuration diagram of the IP television 3 of the present invention. 11 is a tuner that receives and selects a broadcast, 12 is a descrambler that restores a scrambled signal, 13 is a demultiplexer that separates the multiplexed signal, 14 is a decoder for encoded video data and audio data A video / audio decoder 15, a media control unit 15 for controlling input / output of content data to / from a recording medium, 16 a recording medium (including a removable recording medium) such as an HDD (Hard Disk Drive), DVD, Blu-ray Disc, 18 is a display device such as a liquid crystal display, 19 is a speaker, 20 is a CPU (Central Processing Unit) that performs information processing and device control in the IP television 3, and 21 is a remote control interface (remote control I / F) that receives signals from a remote control ), 22 is an I for transmitting and receiving IP (Internet Protocol) data packets. P communication port, 23 and 24 are ROM (Read-Only Memory) in which programs are recorded, 25 is a graphic / audio engine for controlling processing of displaying a Web page screen, still image, and the like, and 26 is a video display. A video display control unit to be controlled, 27 an audio output control unit for controlling audio output, 28 a memory card, and 30 a remote controller for operating the IP television 3.

  As described above, the display device 18 and the speaker 19 are not necessarily required, and an output unit that outputs data from the video display control unit 26 or the audio output control unit 27 to the outside (for example, an S terminal, a D terminal, The component video terminal or the like may be an optical digital terminal, a coaxial digital terminal, or the like for audio and the HDMI terminal or the like for video / audio. A plurality of recording media 16 may be provided. For example, a configuration in which both a recording medium such as an HDD and a drive of a removable recording medium such as a DVD are provided may be used.

  The IP television 3 includes an IP communication port 22 for transmitting and receiving IP data packets in addition to an antenna and a digital tuner for receiving broadcast radio waves, and includes TCP (Transmission Control Protocol), UDP (User Datagram Protocol), DHCP (Dynamic Host Configuration Protocol). ), DNS (domain name server), HTTP (HyperText Transfer Protocol), RTP (Real-time Transport Protocol), RTSP (Real Time Streaming Protocol), MLD (Multicast Listener Discovery), IGMP (Internet Group Management Protocol), etc. A communication protocol and an application such as a browser are installed, and the IP communication port 22 is connected to the content distribution network 1 outside the home via a router or the like, and various contents distributed and distributed by the content distribution server 2 are streamed and downloaded. You can use the service.

  The content data received at the IP communication port 22 is descrambled by a descrambler (not shown) and reproduced through the demultiplexer 13, the video / audio decoder 14, and the like.

  In the IP broadcast service of the present embodiment, the receiver receives the program guide data of the IP broadcast program sent from the content distribution server and displays it on the display screen, and the user designates the displayed program with a remote controller or the like and receives it. The machine obtains the destination multicast address of the program video content based on the input channel number based on the multicast address included in the program guide data and the channel number conversion table. Then, the program content distribution procedure is performed using the MLD or IGMP protocol, and the content data packet transferred by the communication control device is received and sent to the decoder 14 for reproduction.

Note that the method of selecting a program to be viewed, the method of acquiring a multicast address, and the IP protocol used in the service are not limited to those described above. FIG. 3 shows that the IP television program 3 is playing back an IP broadcast program distributed in multicast. FIG. 11 is a flowchart of a control program for IP broadcast program switching processing when a user gives an instruction to view another program. For example, the program is stored in the ROM 24 and executed by the CPU 20.

  First, as with a normal television, for example, when the IP television 3 is turned on, it starts program playback in the state and channel that it was watching just before the power was turned off, and waits for a user's remote control operation (steps 1000 to 1001).

  In general, a TV remote control has various functions for moving the TV, such as a broadcast channel selection button and a volume adjustment button, and various processes corresponding to the operation of the remote control button are performed (step 1001). Here, a case where an operation related to channel switching of an IP broadcast program which is a feature of the present invention is performed will be described. In the embodiment, the operation by the remote controller is described as an example, but an operation by another method (for example, an operation by a button or a switch of the receiving apparatus main body) may be used.

  First, it is assumed that the user designates display of a program guide in order to view an IP broadcast program with a remote controller (in the case of “viewing” in step 1004). In this case, the process proceeds to step 1005, where the program guide service screen is displayed so that the user can input and specify the channel of the IP broadcast program to be viewed. The program selection screen may be displayed, for example, in such a manner that the currently reproduced program screen is reduced to a slightly smaller size, and an IP broadcast program guide may be displayed in the gap, or the IP broadcast program may be displayed by other methods. The program guide may be displayed.

  When the user browses the displayed program guide and a program channel desired by the user is input from the remote control (step 1006), the input channel number is converted into a multicast address and a channel number conversion table included in the program guide data. To obtain the destination multicast address of the program video content. Then, a procedure for receiving program contents is performed.

  At this time, if the IP broadcast program is not currently received (eg, No in step 1007), such as watching a program provided by broadcast waves after turning on the power, the program content packet of IP multicast distribution is not received. The receiving process is started (step 1008). That is, in step 1008, a socket for taking in a new data packet from the IP communication port 22 is prepared, and a multicast address reception group participation notification (Listener Report) of the program is transmitted according to the IGMP protocol or the MLD protocol. Wait until the packet data of the multicast distribution content starts to arrive. Then, when the program content packet starts to reach the IP port 22, it is fetched and sent to the decoder. By this process, the user-specified IP program is reproduced and displayed.

  If the reception process of the IP multicast packet has already been performed (eg, Yes in step 1007), such as when another IP broadcast program is being viewed and the program channel is changed, the process of starting reception of the selected program content In addition to this, it is necessary to perform a procedure for stopping the program content that has been viewed.

  However, either reception start or stop processing is performed first. As described above, since the content distribution server 2 to the IP television 3 pass through routers and switches, a certain amount of time loss occurs at both start and stop (the magnitude of this loss time varies depending on the content distribution network 1). On the interface, it is better to first start receiving the next program so that the next program can be viewed as soon as possible.

  In this case, since the two program content data temporarily flows on the home network, the video of the switched program is disturbed if there is not enough room for the two content data to flow in the network band, and in some cases, the video is viewed. It can last a few seconds. Then, even if the loss time when switching programs is reduced by starting reception first, the video of the program after switching is disturbed. Therefore, if there is not enough bandwidth for the two content data to flow in the network bandwidth, stop receiving the program being played first, and wait for the content data to stop before starting the decoding of the next program The procedure to do is good.

  In the present invention, the IP television 3 is configured to use the two processing procedures depending on the allowable bandwidth of the connected network, and stores which procedure is suitable as a mode.

  That is, if the switching mode is set to high speed (high speed switching mode) (Yes in step 1009), the program content after switching is processed (step 1010) and then the program before switching. A content reception stop process (step 1011) is performed.

  The reception / reproduction process is the same as the process described in step 1008. The reception stop process is a process of sending an IP multicast communication packet reception group leaving notice (Leave Group or Listener Report) of a program whose reception should be stopped according to the IGMP protocol or MLD protocol, and deleting the reception socket. is there. In the high-speed switching mode, when viewed from the user, the program is switched in the first step 1010.

  If the mode is not the high-speed switching mode (if No in step 2009, hereinafter referred to as “normal switching mode”), the program content reception stop process before switching (step 1012) is performed, and then the next program is received. A start process (step 1013) is performed.

  And if there is a time limit value from the group leaving that has been agreed in operation in the data content distribution network until the actual content data transfer stop, etc. instead of playing the received data immediately, wait for that time to pass (Step 1014).

  Alternatively, it waits until the data of the content that has finished the stop procedure does not come, for example, by checking the sequence number of the packet so that the received data packet is stabilized without dropping (step 1014).

  Thereafter, the process proceeds to step 1015, where the acquired content of the next program is sent to the decoder to start reproduction. In this normal switching mode, when viewed from the user, the screen is momentarily blacked out after the processing of step 1012, and then the next program is displayed in the processing of step 1015.

  The high-speed switching mode and the normal switching mode may be set manually by the user or automatically according to the network bandwidth. Further, the user may be able to select whether the setting is manually performed by the user or automatically according to the bandwidth of the network. In this case, for example, the user can select whether the switching mode is set manually or automatically (steps 1004, 1020 to 1022).

  If manual setting is selected in step 1020, the switching mode may be selected in step 1021, for example, on a setting screen displayed on the screen.

  If automatic setting is selected in step 1020, in step 1022, for example, reception start processing of two IP broadcast programs is actually performed, and the network band is a band in which two content data can be received simultaneously. Determine if there is. In this determination, for example, the data received by the IP television may not be sent to the decoder, and the packet sequence number may be checked for several seconds to determine whether or not the band can be received simultaneously.

  For example, if both of the two content data packets can be received without packet loss (for example, the sequence number skips or is interrupted), the high-speed switching mode may be used, and if packet loss occurs, the normal switching mode may be selected.

Note that this simple measurement is, for example, because the bandwidth varies depending on the broadcast program, and it is important to try to receive three content data, or to receive two content data several times while changing the program. There can be various ways.
As described above, the user can receive and play back video content programs by IP multicast communication in which the switching time of a TV program as a receiver is determined depending on circumstances of a relay device such as a router or a switch on the network. When switching the program being watched to another program, by switching the order of receiving the next program you want to watch or the receiving stop process of the program that you have been watching first There is an effect that the program can be switched more smoothly by a method suitable for the state of the user's network.

It is a figure which shows an example of a content delivery system. It is a figure which shows an example of the hardware constitutions of a receiver. It is a flowchart which shows an example of the procedure of a program switching process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Network, 2 Content distribution server, 3 ... IP television, 5 ... Home network,
DESCRIPTION OF SYMBOLS 11 ... Antenna tuner, 12 ... Descrambler, 13 ... Demultiplexer, 14 ... Video / audio decoder, 15 ... Media recording control part, 16 ... Recording medium, 18 ... Display screen, 19 ... Speaker, 20 ... CPU, 21 ... Remote control interface unit 22 ... IP (Internet protocol) communication port 23 ... Random access memory 24 ... Read only memory 25 ... Graphic audio engine 26 ... Video display control unit 27 ... Audio output control unit 28 ... Memory card , 30 ... remote control, 31 ... remote control return button, 32 ... remote control advance button, 41 ... edge router, 42 ... layer 3 switch, 43 ... edge router, 44 ... home gateway router

Claims (6)

A receiving unit for receiving encoded content data through a communication network;
A decoding unit for decoding the encoded content data received by the receiving unit;
An output unit for outputting the content data decrypted by the decryption unit;
A control unit that controls the receiving unit, the decoding unit, and the output unit;
When the content data received by the receiving unit is switched from the first content data to the second content data, the control unit stops the reception of the first content data and the second content data A receiving apparatus that changes the order of the process for starting reception. The receiving device according to claim 1.
The control unit is a receiving device that switches a sequence of a process of stopping reception of the first content data and a process of starting reception of the second content data in accordance with an allowable communication band of the communication network. The receiving device according to claim 2,
The control unit first performs a process of starting reception of the second content data when the allowable communication band of the communication network can transmit the first content data and the second content data in parallel. A receiving apparatus that first performs a process of stopping the reception of the second content data when the allowable communication band of the communication network cannot transmit the first content data and the second content data in parallel. Receiving the encoded content data through the communication network,
Decoding the received encoded content data;
A receiving method for outputting the decrypted content data,
A reception method for switching the order of stopping the reception of the first content data and starting the reception of the second content data when switching the received content data from the first content data to the second content data. . The receiving method according to claim 4, wherein
A receiving method for switching the order of stopping the reception of the first content data and starting the reception of the second content data in accordance with an allowable communication band of the communication network. The receiving method according to claim 5, wherein
When the allowable communication band of the communication network can transmit the first content data and the second content data in parallel, the reception of the second content data is started first, and the allowable communication of the communication network is performed. A reception method in which the reception of the second content data is stopped first when the band cannot transmit the first content data and the second content data in parallel.

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