KR100850358B1 - Method and IP settop box for reducing delay of zapping time - Google Patents

Abstract

The present invention relates to a method and an IP set-top box for reducing a channel change delay (zapping time), the first step of receiving a broadcast stream for the requested channel and the upper and lower channels of the channel according to the channel change request; A second step of separating the received broadcast stream for each channel; Generating a broadcast signal by decoding each of the separated broadcast streams; And a fourth step of transmitting a broadcast signal of a requested channel among the generated broadcast signals to a display device, thereby reducing a channel change delay when a channel currently being viewed is changed to an adjacent channel. have.

Change channel, set-top box, broadcast stream, IPTV, zapping, zapping

Description

Method and IP settop box for reducing delay of zapping time

1 is a block diagram showing a general IPTV system,

2 is a flowchart illustrating a method for reducing a channel change delay;

3 is a flowchart illustrating a method for reducing a channel change delay according to an embodiment of the present invention;

4A and 4B are flowcharts illustrating a method for reducing a channel change delay according to an embodiment of the present invention;

5 is a diagram illustrating usage of network bandwidth according to an embodiment of the present invention; and

6 is a block diagram illustrating an IP set-top box for reducing a channel change delay according to an embodiment of the present invention.

The present invention relates to a method and an IP set-top box for reducing a channel change delay, and a method and an IP set-top for reducing a channel change delay especially when there is a change request for a channel adjacent to a receiving channel. It's about the box.

1 is a diagram illustrating a schematic configuration of a general internet protocol television (IPTV) system. IPTV is a method in which a program provider delivers a broadcast stream desired by a user using a network, and watches the desired channel by using a device such as an IP settop box.

Referring to FIG. 1, a general IPTV system includes a broadcast server 101, a network 102, and a plurality of IP set-top boxes 103. In the system, a broadcast stream is generated in the form of an IP (internet protocol) frame in the broadcast server 101. The generated frames are transferred to the plurality of IP set-top boxes 103 through the network 102. At this time, the network is composed of L (layer) 3 devices such as routers and L2 devices such as switches, and a multicast routing protocol operates between routers to deliver a multicast frame to a desired destination.

If the IP set-top box 103, which was receiving the broadcast stream of a specific channel, requests a channel change to change to another channel, the channel change request is performed through the L2 switch in the form of an internet group management protocol (IGMP) join message. Is passed on. If the frame of the channel is being transmitted to this router, the frame of this channel can be delivered to the requesting L2 switch. However, if the frame of the channel is not delivered to the router, the router requests a broadcast stream of the channel using the multicast routing protocol. Thereafter, when the broadcast stream is delivered to the router, the broadcast stream is delivered to the L2 switch requesting the frame of this channel.

The problem with the above scheme is that the time from the user requesting the channel change to watching the requested channel, that is, the delay of the channel change is too large. CATV, on the other hand, has very little channel change delay.

2 is a diagram schematically illustrating a flow of a method for reducing a conventional channel change delay. This method is proposed as a solution for solving the channel change delay problem mentioned above. In order to solve the problem caused by the routing protocol, the L2 switch 201 delivers the streams of all channels. The L2 switch 201 delivers only the channel requested by the user using IGMP snooping. A more detailed description of the operation method is as follows.

When the user requests a channel change using a remote control or a button on the TV, the IP settop box 202 detects this and transmits an IGMP join message for the corresponding channel to the L2 switch 201. The L2 switch 202 receiving the IGMP join message delivers the stream of the channel to the IP set-top box 202. The stream of the corresponding channel is transmitted to the display device 203. After that, if the user wants to change the channel, the above process is repeated. Therefore, the channel change delay during channel change is constant as shown in FIG. 2, and the channel change delay mentioned in FIG. 1 is also significantly reduced. However, this method also does not solve the inconvenience caused by delay in changing the channel to a satisfactory level.

An object of the present invention for solving the above problems is to provide a method and an IP set-top box that can reduce the channel change delay when the channel is continuously changed up or down.

In order to achieve the object of the present invention as described above, a method for reducing the channel change delay of the present invention, the first step of receiving a broadcast stream for the requested channel and the upper and lower channels of the channel according to the channel change request; A second step of separating the received broadcast stream for each channel; Generating a broadcast signal by decoding each of the separated broadcast streams; And transmitting a broadcast signal of a requested channel among the generated broadcast signals to a display device.

In order to achieve the object of the present invention as described above, the IP set-top box for reducing the channel change delay of the present invention, the interface unit for receiving an IGMP (Internet group management protocol) message and broadcast stream in response to the channel change request; A stream separator for separating the broadcast stream received through the interface for each channel; A decoder to decode each broadcast stream separated by the stream separator to generate a broadcast signal; A stream selector which transmits a broadcast signal of a channel requested among the generated broadcast signals to a display device; And a control unit controlling an operation of the stream selector to transmit at least one IGMP message through the interface and to transmit a broadcast signal of the received requested channel to a display device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

3 is a diagram schematically illustrating a flow of a method for reducing a channel change delay according to an embodiment of the present invention. Referring to FIG. 3, first, it is assumed that a user of a broadcast program is watching a specific channel. For example, the first time you turn on the TV, you are watching the channel you were watching when you first turned it off, or you are still watching an existing channel because there has been no channel change request for a preset amount of time. to be. In this case, it is assumed that only the broadcast stream of a specific channel is received in the IP set-top box or the like (S301).

Then, if there is a change request to the upper or lower adjacent channel of the currently viewed channel (S302), the broadcast stream of the requested channel and the upper and lower adjacent channels of the requested channel is received (S303). For example, when a user selects a number of a specific channel through a set-top box remote controller or the like, the user receives a broadcast stream for the channel, at least one upper channel adjacent to the channel, and at least one lower channel adjacent to the channel.

Then, each of the received broadcast streams is separated (S304), and each of the separated broadcast streams is decoded into a broadcast signal (S305). In operation S306, only the broadcast signal requested by the user, etc., among the broadcast signals generated as a result of the decoding is transmitted to the display apparatus for viewing.

Thereafter, if there is a channel change request to the upper or lower adjacent channel of the channel being transmitted to the display device within a predetermined time (S307), the broadcast stream is received only for the requested channel and the upper and lower adjacent channels, and the broadcast stream of the other channel. The reception is stopped (S308). That is, if there is a change request to the upper channel adjacent to the channel currently viewed by the user, the steps S304 to S306 are repeated to transmit only the requested channel to the display apparatus. For example, if the requested channel in step S307 is an upper channel adjacent to the previous channel, since the broadcast stream for the requested channel is already received, the broadcast stream for the upper channel adjacent to the requested channel is further added. Receives and stops receiving a broadcast stream for a subchannel adjacent to the previous channel (or a subchannel that is no longer needed among the subchannels adjacent to the previous channel). Similarly, if the requested channel in the step S307 is a subchannel adjacent to the previous channel, since the broadcast stream for the requested channel is already received, further receiving a broadcast stream for the lower channel adjacent to the requested channel, Stop receiving the broadcast stream for the upper channel adjacent to the previous channel (or the higher channel that is no longer needed among the upper channel adjacent to the previous channel).

If there is no channel change request within a predetermined time after step S306 (S307), only the broadcast stream currently delivered to the display device is received (S309). Usually, a certain amount of time elapses after a change request to an upper or lower neighbor channel means that the user has decided to watch a specific channel, and thus receives only a broadcast stream for the channel currently being watched in order to reduce bandwidth usage. .

In the whole process, the broadcast stream for the channel requested by the user and the adjacent channel should be at least one of the upper and lower channels, and the broadcast streams for the channel as many as the environment permits, such as bandwidth, may be set to be received. In this case, the step S309 for reducing bandwidth usage may be omitted. In this way, the channel change delay can be significantly reduced. Each step is described in more detail below.

4A and 4B are flowcharts showing in detail a method for reducing a channel change delay according to an embodiment of the present invention. At this time, it is assumed that all the broadcast streams are delivered up to the L2 switch 301 while the user of the IPTV broadcast program is watching the broadcast of the specific channel. Referring to FIG. 4A, the L2 switch 301 transmits a stream of a channel requested by a user to the set top box 302, and the set top box 302 transmits a broadcast signal of the requested channel to the display device 303. do. This is a process that is performed when the user first watches a broadcast by performing an operation of turning on an IPTV, for example.

Subsequently, when the user requests a channel change (for example, when a channel change request is made by using an up or down button such as a set-top box remote controller), the IP set-top box 302 that detects the channel is requested. The IGMP join message requesting the stream for the upper and lower neighbor channels of the established channel is transmitted to the L2 switch 301. The L2 switch 301 detects this and delivers the requested channel and the streams of the upper and lower adjacent channels around the channel to the IP set-top box 302.

The IP set-top box 302 displays only the channel requested by the user on the display device 303. If the channel is changed to an upper (or lower) channel, the stream of the channel is being transmitted to the IP set-top box 302 so that it can be immediately displayed on the display device. Therefore, the channel change delay measured at this time represents a very short time compared with the previous one. The IP set-top box 302 simultaneously transmits the IGMP join message for the upper neighbor channel of the requested channel and the IGMP leave message for the lower neighbor channel of the previous channel to the L2 switch 301. Thereafter, the L2 switch 301 transfers the streams of the requested channel and the upper and lower adjacent channels to the IP set-top box 302.

Thereafter, when the user does not change the channel for a predetermined time, the IP set-top box 302 transmits an IGMP leave message for the up-and-down adjacent channel to the L2 switch 301 and detects the L2 switch 301 up and down. The stream of adjacent channels may no longer be delivered. This is to reduce network bandwidth usage from the point in time when no more channel changes are expected to be requested.

FIG. 4B is a diagram illustrating an example of a method for reducing channel change delay described with reference to FIG. 4A. Suppose a user is currently watching channel 1 and attempts to change a channel using a button for selecting a higher channel such as a set-top box remote controller.

When the user presses the button for selecting the upper channel once, channel 2 is displayed on the display device after a predetermined time. At this time, if the user does not like the changed channel 2, the user will press the button again. Thereafter, the channel 3 shows a delay that is much shorter than the change delay of the previous channel and is displayed on the display device. At this time, if the user wants to watch the broadcast program of channel 3, the user no longer presses the button for selecting the upper channel. If the user keeps pressing the channel 3 unfavorably, the display device displays a very short delay time and displays the changed channel.

During this process, the following processes are performed between the IP set-top box 302 and the L2 switch 301. As soon as the user changes to channel 2, the IP set-top box 302 delivers IGMP join messages for channels 2 and 3 to the L2 switch 301. The L2 switch 301 transmits the broadcast streams for channels 1, 2, and 3 to the IP set-top box 302, and the IP set-top box 302 displays the broadcast signal of the channel 2 on the display device. When a channel change request from the user to channel 3 is requested again, the IP set-top box 302 immediately displays channel 3 on the display device, and simultaneously displays the IGMP join message for channel 4 and the IGMP leave message for channel 1 at the L2 switch. Forward to 301. The L2 switch 301 that detects this transmits the broadcast streams of channels 2, 3, and 4 to the IP set-top box 302.

Thereafter, if there is no channel change request of the user for a predetermined time, the IGMP leave message for channels 2 and 4 is transmitted to the L2 switch, and the L2 switch only delivers the stream of channel 2 to the IP set-top box 302.

5 is a diagram illustrating network bandwidth usage when a method for reducing channel change delay is used according to an embodiment of the present invention.

Referring to FIG. 5, the x axis represents time and the y axis represents bandwidth usage. If the user of the IPTV requests a channel change at time a, it triples from the bandwidth usage X to 3X. After that, if the channel is fixed while the channel is fixed until the time point b, the bandwidth usage is reduced to the amount of using the broadcast stream of one channel at the time point c. In other words, if the channel is changed continuously, twice as much bandwidth is wasted as in the case of transmitting a single broadcast stream, but the channel change delay represents a very short time.

For users, it is common to prefer short channel change delay even if bandwidth is wasted. In addition, the waste of the channel is a temporary phenomenon since it is made only during the continuous channel change attempt.

6 is a diagram schematically illustrating a configuration of an IP set-top box 302 for reducing a channel change delay according to an embodiment of the present invention. Referring to FIG. 6, the IP set-top box 302 of the present invention includes an interface unit 601, a stream separation unit 602, a decoder unit 603, a stream selection unit 604, and a control unit 605. It is composed.

When the user requests a change to a specific channel through an input device such as a set-top box remote controller, the controller 605 broadcasts the requested channel and the upper and lower adjacent channels of the corresponding channel through the interface unit 601. Control the transmission of a request message (for example, IGMP join message, etc.) or a message (for example, IGMP leave message, etc.) about the transmission stop of the broadcast stream for a channel that is no longer needed when changing the channel. The message about the broadcast stream request or suspension may be a plurality of messages. In addition, the operation of the stream selector 604 is controlled to transmit only a broadcast signal for a channel requested by the user to a display device.

The interface unit 601 includes an interface for receiving a broadcast stream and transmitting an IGMP message to the IP set-top box 302. The stream separator 602 separates the broadcast stream received through the interface unit 601 and transmits the stream to the decoder 603.

The decoder 603 decodes each broadcast stream separated by the stream separator 602 and delivers the stream to the stream selector 604. Existing IP set-top box has only one decoder, but since the IP set-top box 302 of the present invention receives a plurality of broadcast streams, there must be a plurality of decoders for decoding them. Although the decoder unit 603 of the figure includes three decoders, a larger number of decoders may be included depending on the setting of the number of broadcast streams or as long as the network bandwidth allows.

In addition, the decoder unit 603 according to the present embodiment may be implemented by each chip decoding each broadcast stream, or may be implemented to decode a plurality of broadcast streams simultaneously in one chip. It goes without saying that a plurality of broadcast streams can be decoded by software, not by hardware configuration.

The stream selector 604 receives information about a channel requested by the user from the controller 605, detects only a broadcast signal for a channel requested by the user among the broadcast signals decoded by each decoder, and delivers the broadcast signal to a display device. do.

That is, in addition to the configuration of the existing IP set-top box, a component portion for separating a plurality of broadcast streams and a component portion for selecting and delivering only a broadcast stream requested by a user from among the plurality of broadcast streams to a display device are requested. In addition, a component serving as a conventional decoding function should be able to decode a plurality of broadcast streams as in the decoder unit 603 of the present invention. In addition, although not shown in FIG. 6, the IP set-top box 302 of the present invention may include a plurality of IGMP messages (for example, a plurality of IGMP join messages or IGMP leave messages, etc.) as described with reference to FIGS. 4A and 4B. You should be able to transfer.

So far I looked at the center of the preferred embodiment of the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

The method and the IP set-top box for reducing the channel change delay of the present invention as described above, when receiving a channel change request by receiving a broadcast stream for the channel and the adjacent upper and lower channels, if there is a change request to the channel adjacent to the current channel The zapping time can be reduced.

Claims (15)

Receiving a broadcast stream for the requested channel and the upper and lower channels of the corresponding channel according to a channel change request; A second step of separating the received broadcast stream for each channel; Generating a broadcast signal by decoding each of the separated broadcast streams; And And transmitting a broadcast signal of a requested channel among the generated broadcast signals to a display device. The broadcast stream of claim 1, wherein the broadcast streams received in the first step are received. And a broadcast stream for at least one higher channel adjacent to the requested channel and a broadcast stream for a lower channel. The method of claim 1, wherein the first step If the channel change request is a channel change request to an upper neighbor channel of a channel currently delivered to the display device, And further receiving a broadcast stream for at least one upper neighbor channel adjacent to the requested channel, and no longer receiving a broadcast stream for a lower neighbor channel of the channel currently being transmitted to the display device. How to reduce it. The method of claim 1, wherein the first step If the channel change request is a channel change request to a lower adjacent channel of the channel currently being transmitted to the display device, And further receiving a broadcast stream for at least one lower adjacent channel adjacent to the requested channel, and no longer receiving a broadcast stream for a higher adjacent channel of the channel currently being transmitted to the display device. How to reduce it. The method of claim 1, If there is no channel change request for a preset time after the fourth step, receiving only the broadcast stream of the channel currently being transmitted to the display device. An interface unit for transmitting an internet group management protocol (IGMP) message and receiving a broadcast stream according to a channel change request; A stream separator for separating the broadcast stream received through the interface for each channel; A decoder to decode each broadcast stream separated by the stream separator to generate a broadcast signal; A stream selector which transmits a broadcast signal of a channel requested among the generated broadcast signals to a display device; And An IP protocol set-top box for reducing a channel change delay including a control unit for controlling the operation of the stream selector to transmit one or more IGMP messages through the interface and to transmit a broadcast signal of the received requested channel to a display device. . The method of claim 6, wherein the interface unit IP set-top box for reducing the channel change delay, characterized in that for receiving a broadcast stream for the requested channel and the upper and lower channels of the channel according to the channel change request. The method of claim 7, wherein the broadcast stream for the upper and lower channels are And a broadcast stream for at least one higher channel adjacent to the requested channel and a broadcast stream for lower channel. The method of claim 7, wherein the interface unit If the channel change request is a channel change request to an upper neighbor channel of a channel currently delivered to the display device, And further receiving a broadcast stream for at least one upper neighbor channel adjacent to the requested channel, and no longer receiving a broadcast stream for a lower neighbor channel of the channel currently being transmitted to the display device. IP set-top box to reduce power. The method of claim 7, wherein the interface unit If the channel change request is a channel change request to a lower adjacent channel of the channel currently being transmitted to the display device, And further receiving a broadcast stream for at least one lower adjacent channel adjacent to the requested channel, and no longer receiving a broadcast stream for a higher adjacent channel of the channel currently being transmitted to the display device. IP set-top box to reduce power. The method of claim 7, wherein the interface unit If there is no other channel change request for a preset time after the channel change request, IP set-top box for receiving a channel change delay, characterized in that for receiving only the broadcast stream of the channel currently delivered to the display device. The method of claim 7, wherein the decoder unit IP set-top box for reducing the channel change delay, characterized in that it comprises a decoder of the total number of the requested channel and the upper and lower channels of the channel. 13. The apparatus of claim 12, wherein each of the decoders is IP set-top box for reducing the channel change delay, characterized in that implemented in a separate chip (decode) to decode each broadcast stream. The method of claim 12, wherein the decoder unit IP set-top box for reducing the channel change delay, characterized in that it is implemented to decode each broadcast stream simultaneously in one chip. delete

Images