KR20080022816A - Appratus and method for instant channel change in ip-tv broadcasting system - Google Patents

Abstract

An apparatus and a method for real-time channel switching in an IP(Internet Protocol) TV broadcasting system are provided to stream PSI(Program Specific Information) and an I-frame read from broadcasting data to a set-top box which request channel switching, thereby reducing channel zapping delay to less than 0.5 second during the channel switching. A plurality of buffers(710-1~710-n) is provided to correspond to each channel received from an Internet subscriber connection device for providing broadcasting data in a multicasting method and has capacity in which broadcasting data corresponding to each channel is stored at a predetermined amount. A PSI management unit(720) manages PSI including a PAT(Program Association Table) and a PMT(Program Map Table) which a provider supplying the broadcasting data sets up. A first connection management unit(730) performs communication by the Internet subscriber connection device and an IGMP(Internet Group Management Protocol) and receives broadcasting data on plural channels selected out of channels which the Internet subscriber connection device supplies. A packet generation unit(750) generates a RTP(Real time Transport Protocol) or UDP(User Datagram Protocol) packet including the PSI and a RTP or UDP packet including TSs(Transport Streams). A second connection management unit(740) sets a RTSP(Real-Time Streaming Protocol) session for channel switching and streams the RTP or UDP packets corresponding to a switched channel to a set-top box which requests the channel switching in a unicast method.

Description

Apparatus and method for instant channel change in IP-TV broadcasting system

1 is a view showing the configuration of a conventional IP broadcasting network,

2 is a view showing a channel change process in the existing IP broadcasting system,

3 and 4 are diagrams illustrating the main factors causing the zapping delay when changing channels in the existing IP broadcasting system and the delay times due to the respective factors;

5 is a diagram illustrating the configuration of an entire broadcasting network to which a real-time channel change device is applied in an IP broadcasting system according to the present invention;

6A and 6B illustrate the structure of an MPEG2-TS PSI and the structure of an MPEG2-TS stream, respectively;

7 is a diagram showing the detailed configuration of a preferred embodiment of the apparatus for changing a real-time channel in the IP broadcasting system according to the present invention;

FIG. 8 is a diagram illustrating a broadcast data streaming procedure between a buffer included in an apparatus for real-time channel change and a set-top box requesting a channel change in an IP broadcasting system according to the present invention.

FIG. 9 is a diagram illustrating main factors that cause zapping delays when changing channels by a real-time channel changing apparatus in an IP broadcasting system according to the present invention, and delay times due to respective factors.

The present invention relates to an apparatus and method for real-time channel change in an IP broadcasting system, and more particularly, to an apparatus and method for real-time channel changing that can minimize a zapping delay when changing a channel in an IP broadcasting system.

In recent years, with the rapid spread of high-speed Internet and the development of information and communication technology, IP-TV service that provides interactive TV service using the Internet is different from the conventional method in which communication and broadcasting have been provided in different ways. It is being activated. IPTV is connected to a set-top box that processes IP video signals and converts them into standard TV signals. Using a switched video service (SVS) system, IPTV can be used for services such as broadband network channels, subscriber services, and movie watching. Can be connected selectively. However, IP-TV has many advantages in terms of providing high-definition video and providing various additional services, compared to analog broadcasting such as terrestrial broadcasting. However, when a user watching IP-TV wants to change the channel, There is a disadvantage that it takes more time to change the channel than the broadcast. As such, a phenomenon in which a large amount of time is required when changing a channel of the IP-TV (hereinafter, referred to as a "zapping delay") is due to the transmission and reception method of the IP-TV.

FIG. 1 is a diagram illustrating a configuration of an existing IP broadcasting network, and FIG. 2 is a diagram illustrating a channel changing process in an existing IP broadcasting system.

1 and 2, upon receiving a channel change request signal from a user, the set-top box 110-1 mutes the screen output and terminates the existing channel and starts the change channel with the Internet subscriber access device 120. An Internet Group Management Protocol (IGMP) message indicating the transmission is transmitted (S200). IGMP is an Internet protocol that provides a means for an Internet terminal device to inform a connected node that a multicast group is connected. After analyzing the received IGMP message, the Internet subscriber access device 120 stops the streaming of the broadcast data of the existing channel through the port corresponding to the set-top box (110-1) transmitting the IGMP message (S210). Next, the Internet subscriber access apparatus 120 copies the broadcast data of the changed channel requested by the corresponding set-top box 110-1 from the broadcast data of all channels provided from the broadcast data providing server 130 existing in the public network. Streaming to the set-top box (110-1) (S220). At this time, the Internet subscriber access device 120 provides the broadcast data of the channel requested by each set-top box (110-1 to 110-n) connected to the lower by a multicasting method. The set top box 110-1 decodes the broadcast data when the program specific information (PSI) and the first I-frame are detected from the broadcast data of the changed channel received from the Internet subscriber access device 120. It outputs to the connected device, such as a TV, a monitor (S230).

The channel changing method of the conventional IP broadcasting system as described above has a problem that a zapping delay occurs due to various factors such as processing time of an IGMP message and time required to start decoding the broadcast data of the changed channel in the set-top box. . 3 and 4 illustrate the main factors causing the zapping delay when changing channels in the existing IP broadcasting system, and the delay times due to the respective factors. Referring to FIGS. 3 and 4, a zapping delay of at least 0.7 seconds occurs when a channel is changed in an existing IP broadcasting system, and a zapping delay of about 2 seconds is generally generated considering all the influences of the remaining factors. do.

An object of the present invention is to provide a channel change apparatus and method capable of minimizing a zapping delay occurring when a channel is changed in an IP broadcasting system.

Another object of the present invention is to provide a computer-readable recording medium having recorded thereon a program for executing a channel changing method for minimizing a zapping delay occurring when a channel is changed in an IP broadcasting system. have.

The apparatus for changing a real-time channel in the IP broadcasting system according to the present invention is provided in correspondence with each channel received from an Internet subscriber access apparatus for providing broadcast data in a multicasting manner, and broadcast data corresponding to each channel is provided. A plurality of buffers having a capacity that can be stored for a predetermined amount of time; A PSI manager configured to manage program specific information including a program association table and a program map table set by a provider for supplying the broadcast data; A first access management unit communicating with the digital subscriber line access multiplexing device through an Internet Group Management Protocol to receive broadcast data for a plurality of channels selected from channels provided by the Internet subscriber access device; A transport stream corresponding to an I-frame from an RTP or UDP packet including the program specific information provided from the PSI management unit and a buffer corresponding to a change channel requested from a set-top box requesting a channel change among the plurality of buffers. A packet generation unit for generating an RTP or UDP packet including the transport streams sequentially read; And establishing an RTSP session for the change channel with the set-top box requesting the channel change, and setting the RTP or UDP packets corresponding to the change channel through the set RTSP session to the set-top box requesting the channel change in a unicast manner. And a second connection manager for streaming.

As a result, it is possible to minimize the zapping delay occurring when the channel is changed in the IP broadcasting system.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the apparatus and method for real-time channel change in the IP broadcasting system according to the present invention.

5 is a diagram showing the configuration of the entire IP broadcast network to which the real-time channel change apparatus according to the present invention is applied.

Referring to FIG. 5, the entire broadcasting network includes a set top box 510-1 through 510-n, a real time channel change device 520, an internet subscriber access device 530, and a data providing server 540.

Set-top boxes 510-1 to 510-n process user input commands such as service request commands and channel change commands input from the user, and generate a web packet corresponding to the user input command to connect to the public network. The server transmits to a server such as a mail server or generates a Real Time Streaming Protocol (RTSP) message and transmits it to the real time channel change device 520. Here, the public network means a public telephone network, a wired / wireless internet network, a wireless communication network, and the like. In addition, the set-top boxes 510-1 to 510-n decode broadcast data received from the real-time channel changer 520 to output through a connected output device, or output devices connected to web data received from a public network. Output through The set-top boxes 510-1 to 510-n and the real-time channel change device 520 transmit and receive data in a real time transport protocol (RTP) or user datagram protocol (UDP) packet.

In particular, in connection with the channel change, the set-top boxes 510-1 to 510-n establish a new RTSP session with the real-time channel change device 520 when a channel change command is input from the user, and change the channel through the set RTSP session. It transmits the information about the real-time channel change device 520. Next, the set-top boxes 510-1 through 510-n decode broadcast data streamed from the real-time channel change device 520 and output the decoded broadcast data through an output device. The broadcast data received from the real-time channel change device 520 by the set-top boxes 510-1 through 510-n requesting the channel change are discontinuous information (DI), PSI, and MPEG streams. In this case, DI is information for determining whether the set-top boxes 510-1 to 510-n are broadcast data corresponding to an existing channel or a change channel, which are received from the real-time channel change device 520. If DI is '1', the set-top boxes 510-1 to 510-n interpret the received RTP or UDP packets as broadcast data corresponding to the changed channel, and if '0', broadcast data corresponding to the existing channel. Interpret with The DI is recorded in a TS located before the TS corresponding to the PSI in the RTP or UDP packet including the PSI or transmitted before the RTP or UDP packet corresponding to the PSI in an RTP or UDP packet separate from the PSI. In order to decode broadcast data received by the set-top boxes 510-1 through 510-n, a transport stream (TS) packet corresponding to a PSI and an I-frame must be received. 6A and 6B show the structure of the MPEG2-TS PSI and the structure of the MPEG2-TS stream, respectively.

The real-time channel change device 520 provides broadcast data corresponding to a channel requested from the set-top box located below as an RTP or UDP packet by a unicast method. The real-time channel change device 520 is provided in the Internet subscriber access device 530, or is provided as an independent device corresponding to the Internet subscriber access device 530. Detailed configuration and operation of the real-time channel change device 520 will be described later.

The internet subscriber access device 530 is located between the set-top boxes 510-1 to 510-n, which are subscriber terminal devices, and the public network, and operates as an access node. Hereinafter, a case where the Internet subscriber access device 530 is a digital subscriber line access multiplexer (DSLAM) will be described as an example. The DSLAM 530 streams broadcast data to the real-time channel changer 520 located below in a multicast manner. At this time, the DSLAM 530 and the real-time channel change device 520 communicates by IGMP.

The data providing server 540 is located in the public network and provides the broadcasting data received from the data streamer of the broadcasting data provider to the DSLAM 530 located below the multicasting method. 5, one data providing server 540 is shown for convenience, but a plurality of such data providing servers 540 are located on the public network. In addition, although only one DSLAM 530 is shown below the data providing server 540, a plurality of DSLAMs may be connected to the lower part of the data providing server 540, and further, an L2 switch and an optical communication line terminal (Optical Line). Terminal: OLT) etc. can be connected.

7 is a diagram showing a detailed configuration of a preferred embodiment of a real-time channel change device 520 according to the present invention.

Referring to FIG. 7, the apparatus 520 for real-time channel change according to the present invention includes a plurality of buffers 710-1 to 710-n corresponding to each channel, a PSI manager 720, and a first connection manager 730. And a second connection manager 740, a packet generator 750, and a controller 760.

In each of the buffers 710-1 to 710-n, broadcast data corresponding to each channel received from the DSLAM 530 is stored. Each of the buffers 710-1 to 710-n is a circular buffer in which newly received data is written to the place where the first received data is stored when the buffer capacity is full, and at least 5 seconds of broadcast data can be stored. Has storage capacity. Each buffer 710-1 to 710-n stores TSs constituting broadcast data (ie, MPEG streams) received from the DSLAM 530.

The PSI management unit 720 manages the PSI set by the broadcast data provider. The PSI includes a program association table (PAT), a program map table (PMT), a conditional access table (CAT), a network information table (NIT), a transport stream description table (TSDT), and the like. PAT is information table for PID of PMT or NIT corresponding to each channel, PMT is information table for PID list of data included in a specific channel, CAT is information table for stream management information, scrambling key, etc. to be. In addition, NIT and TSDT are information tables for networks and channels, respectively. The PSI management unit 720 holds the PSI set by the broadcast data provider in its own storage means, and provides the PSI held by the packet generation unit 750 in response to the PSI provision command input from the control unit 760. do. In this case, the PSI management unit 720 may provide only the PAT and PMT necessary for decoding the MPEG stream to the packet generation unit 750 among the PSI. Meanwhile, the PSI management unit 720 may extract the PSI from the broadcast data corresponding to each channel received from the DSLAM 530 and store the PSI in a storage unit provided therein. In this case, the PSI management unit 720 may be provided by the broadcast data provider. In order to prepare for the change of the PSI, it is preferable to update the PSI stored in the storage means with the PSI extracted from the most recently received broadcast data. The PSI management unit 720 may be integrated into the packet generation unit 750 to be described later.

The first access manager 730 communicates with the DSLAM 530 by IGMP to receive broadcast data for all channels from the DSLAM 530. To this end, the first access manager 730 transmits an IGMP message requesting transmission of broadcast data for all channels provided by the DSLAM 530 to the DSLAM 530. Except that the message exchange between the first access management unit 730 and the DSLAM 530 and the streaming of the broadcast data is performed for all channels, between the conventional set-top box and the DSLAM as described with reference to FIG. Same as the message exchange and streaming of broadcast data.

The second connection management unit 740 provides a connection means between the real-time channel change device 520 and the set-top box (510-1 to 510-n). To this end, the second connection management unit 740 is provided with an RTSP module. In connection with the channel change, the second access manager 740 broadcasts data corresponding to the changed channel generated by the packet generator 750 through the set-top box 510-1 requesting the channel change and the RTSP session set up for the changed channel. Streaming the RTP or UDP packet containing the unicast method to the set-top box 510-1 requesting a channel change.

The packet generator 750 reads and streams a TS from the buffers 710-1 to 710-n corresponding to the changed channel to the set-top box 510-1 requesting a channel change in response to a control command of the controller 760. Create an RTP or UDP packet to be used. For example, when a channel change request of channel 2 is received from the set-top box 510-1 receiving stream data corresponding to channel 1, the packet generator 750 first transmits a subsequent RTP or UDP packet. It generates an RTP or UDP packet including DI for indicating whether the broadcast data corresponding to the channel or the broadcast data corresponding to the changed channel. Next, the packet generator 750 generates an RTP or UDP packet including the PSI provided from the PSI manager 720. In this case, the packet generator 750 may generate DI and PSI as one packet. Subsequently, the packet generator 750 sequentially reads the TSs from the TSs corresponding to the I-frames from the buffer 710-2 corresponding to the channel 2 to generate an RTP or UDP packet. In this case, each of the buffers 710-1 to 710-n has a buffer capacity (eg, a capacity capable of storing 5 seconds of TS) longer than the transmission interval (eg, 0.5 seconds) of the I-frame. As such, a plurality of I-frames may be stored in the buffer 710-2 corresponding to channel 2. Accordingly, the packet generator 750 may generate one I-frame (eg, second received I) among a plurality of I-frames stored in the buffer 710-2 corresponding to channel 2 according to the setting state of the device. Frame) to sequentially read the TSs from the corresponding TSs to generate an RTP or UDP packet. The RTP or UDP packet generated in this manner is streamed to the set-top box 510-1 by which the channel change request is sequentially performed by the second access manager 740. FIG. 8 illustrates a broadcast data streaming procedure between a buffer provided in the real-time channel change device 520 and a set-top box requesting a channel change.

The controller 760 controls the operation of each module constituting the real-time channel change device 520. In particular, the control unit 760 analyzes the RTSP packet received from the set-top box 510-1 requesting the channel change in relation to the channel change, the IP address of the set-top box 510-1 requesting the channel change, and the corresponding set-top box ( The channel of the broadcast data provided to 510-1 and the change channel requested by the corresponding set-top box 510-1 are identified. In addition, the control unit 760 instructs the PSI management unit 720 to provide the PSI to the packet generation unit 750, and provides the packet generation unit 750 with information on the identified change channel to request the channel change. Instructs generation of an RTP or UDP packet to stream to box 510-1. In addition, the control unit 760 outputs a control command to the second connection management unit 740 to stream the RTP or UDP packet generated by the packet generation unit 750 to the set-top box 510-1 requesting the channel change. .

FIG. 9 is a diagram illustrating a main factor that causes a zapping delay when changing a channel by the real-time channel changing apparatus 520 according to the present invention, and a delay time by each factor.

Referring to FIG. 9, the apparatus for changing a real-time channel in the IP broadcasting system according to the present invention changes the channel of an I-frame read from PSI held in its own and broadcast data stored in a buffer corresponding to each channel. Is streaming to the set-top box that requested it immediately. Therefore, compared with the conventional channel change method, the time required to process the channel change request by IGMP message and the time required for the set-top box to receive both the PSI and the first I-frame which are essential for decoding the broadcast data from the DSLAM. This becomes unnecessary and the zapping delay at the time of channel change is reduced to 0.5 seconds or less.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the apparatus and method for real-time channel change in the IP broadcasting system according to the present invention, a channel change request is made for an I-frame read from a PSI held in advance and broadcast data stored in a buffer corresponding to each channel. Because it is streaming to set-top box immediately, it takes time to process channel change request by IGMP message, and it takes until PSI and first I-frame which are necessary for set-top box to decode broadcast data from DSLAM. This eliminates the need for time-consuming, reducing the zapping delay during channel change to less than 0.5 seconds. In addition, since broadcast data for a predetermined amount of time is stored in a buffer corresponding to each channel included in the real-time channel change device, additional services such as retransmission of broadcast data are possible. Furthermore, the real-time channel change device and the set-top box transmit and receive data in a unicast manner, thereby providing a personalized service that cannot be provided in a conventional IP broadcasting system that uses a multicast data transmission scheme.

Claims (1)

A plurality of buffers provided corresponding to respective channels received from an Internet subscriber access apparatus for providing broadcast data in a multicasting manner, the plurality of buffers having a capacity for storing a predetermined amount of broadcast data corresponding to each channel; A PSI manager configured to manage program specific information including a program association table and a program map table set by a provider for supplying the broadcast data; A first access management unit communicating with the Internet subscriber access device through an Internet Group Management Protocol to receive broadcast data for a plurality of channels selected from channels provided by the Internet subscriber access device; A transport stream corresponding to an I-frame from an RTP or UDP packet including the program specific information provided from the PSI management unit and a buffer corresponding to a change channel requested from a set-top box requesting a channel change among the plurality of buffers. A packet generation unit for generating an RTP or UDP packet including the transport streams sequentially read; And Set up an RTSP session for the change channel with the set-top box that requests the channel change, and stream the RTP or UDP packets corresponding to the change channel to the set-top box that requests the channel change in a unicast manner through the set RTSP session. Real-time channel change device in the IP broadcast system comprising a.

Images