KR20080057925A - Channel switching method and apparatus for performing the method - Google Patents

Abstract

A channel change method and an apparatus for performing the method are provided to change channel quickly by previously storing frames composing broadcasting contents in respective buffers according to channels. A packet receiving module(210) receives a broadcasting signal including a plurality of packets. A frame extracting module(250) extracts a frame by using packet identification information about the packets. A frame storing module(260) stores the extracted frame according to channels. A display module(280) outputs a frame corresponding to a channel requested from a user among the stored frames.

Description

Channel switching method and apparatus for performing the method {Method for channel switching and Apparatus for performing the method}

1 is a diagram illustrating a basic concept of channel switching according to the present invention.

2 is a block diagram illustrating a structure of an apparatus for performing channel switching according to an embodiment of the present invention.

3 is a flowchart illustrating operation in a first mode according to an embodiment of the present invention.

4 is a flowchart illustrating operation in a second mode according to an embodiment of the present invention.

5A to 5C are diagrams illustrating a connection relationship between a decoder for storing a frame and a decoder according to the present invention.

6A to 6E are diagrams for describing a method of storing broadcast content for each channel by input of numeric keys according to an embodiment of the present invention.

(Symbol description of main part of drawing)

210: packet receiving module

220: program information extraction module

230: user input module

240: channel switching control module

250: frame extraction module

260: frame storage module

270: decoding module

280: display module

The present invention relates to channel switching, and more particularly, to provide a method for quickly displaying an image of a requested channel on a screen according to a user's channel switching request in an IPTV environment, and an apparatus for performing the method.

With the development of communication and image processing technology, digital TVs are widely used, and accordingly, conventional analog TVs are gradually replaced by digital TVs.

Such digital TVs are favored by many users by providing clearer images and various additional information. However, when a user switches channels (for example, when switching channels to KBS while watching MBC), Since the switching speed is slower than that of analog TV, the user has to wait for the waiting time according to the channel switching. This requires a time to tune from the frequency band for the current channel to the frequency band for the requested channel when the tuner mounted on the digital TV receives a channel switching request, and even if the tuner is tuned, for example, the GOP of the transmitted image is I frame, In the case of B frame and P frame, decoding is possible as soon as GOP (Group Of Picture) order starts with I frame, but if channel switching is performed in the middle of GOP, The image of the switched channel is not displayed. In other words, it takes time before the start of a new GOP is reached.

In order to solve this inconvenience, a digital TV having a plurality of tuners instead of one tuner has emerged. A broadcast signal transmitted through a plurality of channels is input through a plurality of tuners, and a user's request for channel switching is performed. If there is, a tuner corresponding to the requested channel is selected to reduce the conventional tuning time.

However, even in the case of such a digital TV, when the image consisting of I frame, B frame and P frame is received like the MPEG-2 method, the solution takes no time to reach the I frame. In order to have a plurality of tuners, the structure of the digital TV becomes complicated, and there is a problem in that a price increase is also required.

Recently, an IPTV (Internet Protocol Television) service that provides information service, video content, and broadcasting to a television receiver has been introduced using high-speed Internet.

IPTV is not different from general terrestrial broadcasting, cable broadcasting or satellite broadcasting in that it provides broadcasting contents including video. However, IPTV is added and interactive broadcasting contents are provided through internet lines.

However, in the case of IPTV, channel switching by a user may occur as frequently as in digital TV. Therefore, when a channel switching request is requested by a user, it is necessary to quickly switch to a requested channel to display an image of the converted channel on a screen. Was born.

SUMMARY OF THE INVENTION An object of the present invention is to provide a channel switching method and apparatus for performing the method, the method including the plurality of buffers, and the channel switching is performed quickly by pre-stored frames constituting the broadcast content in each buffer for each channel. .

In order to achieve the above object, the channel switching method according to the present invention comprises the steps of (a) receiving a broadcast signal consisting of a plurality of packets, extracting a frame using the packet identification information for the packet, and the extracted frame (B) storing the data for each channel and outputting a frame corresponding to the channel requested from the user among the stored frames.

In addition, in order to achieve the above object, the channel switching method according to the present invention comprises the steps of (a) receiving a channel switch request from a user, (b) outputting a frame already stored for the requested channel, (C) extracting packet identification information of a program for a lower or upper channel of the requested channel, (d) extracting a frame for broadcast content corresponding to the extracted packet identification information, and the extracted (E) storing the frame.

In addition, in order to achieve the above object, an apparatus for performing a channel switching method according to the present invention is a packet receiving module for receiving a broadcast signal consisting of a plurality of packets and extracting a frame using the packet identification information for the packet A frame extraction module, a frame storage module for storing the extracted frame for each channel, and a display module for outputting a frame corresponding to the channel requested by the user from the stored frame.

In addition, to achieve the above object, an apparatus for performing a channel switching method according to the present invention is a user input module for receiving a channel switching request from a user, and a display module for outputting a frame already stored for the requested channel And a program information extraction module for extracting packet identification information of a program for a lower or upper channel of the requested channel, a frame extraction module for extracting a frame for broadcast content corresponding to the extracted packet identification information, and the extraction. And a frame storage module for storing the frame.

In addition, in order to achieve the above object, the apparatus for performing the channel switching method according to the present invention outputs the broadcast content in the current channel while storing the frame constituting the broadcast content in the lower channel and the upper channel for the current channel A channel switching control for controlling an operation of a second mode of storing a frame constituting broadcast content in a lower or upper channel of the requested channel while outputting a pre-stored frame regarding a channel requested by the user and a first mode Module and a user input module for receiving a request from the user.

In addition, in order to achieve the above object, the apparatus for performing a channel switching method according to the present invention is frame extraction means for extracting a frame representing broadcast content for each channel from the broadcast signal consisting of a plurality of packets, and the extracted A plurality of buffers for storing frames for each channel, decoding means for decoding a frame stored in any buffer of the plurality of buffers, and a display screen for outputting the decoded frame.

In addition, in order to achieve the above object, the channel switching method according to the present invention comprises the steps of (a) receiving the numeric key information for channel switching from the user, the frame for a plurality of channels corresponding to the received numeric key information (B) storing each channel for each channel, determining (c) the channel number to be converted based on the received at least one numeric key information, and decoding and outputting the stored frame at the determined channel number. (D) step.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.

Hereinafter, the present invention will be described with reference to a block diagram or a flowchart illustrating a channel switching method and an apparatus for performing the method according to embodiments of the present invention. At this point, it will be understood that each block of the flowchart illustrations and combinations of flowchart illustrations may be performed by computer program instructions. Since these computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, those instructions executed through the processor of the computer or other programmable data processing equipment may be described in flow chart block (s). It will create means to perform the functions. These computer program instructions may be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular manner, and thus the computer usable or computer readable memory. It is also possible for the instructions stored in to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block (s). Computer program instructions It is also possible to mount on a computer or other programmable data processing equipment, so that a series of operating steps are performed on the computer or other programmable data processing equipment to create a computer-implemented process to perform the computer or other programmable data processing equipment. It is also possible for the instructions to provide steps for performing the functions described in the flowchart block (s).

In addition, each block may represent a portion of a module, segment, or code that includes one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of order. For example, the two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the corresponding function.

1 is a diagram illustrating a basic concept of channel switching according to the present invention.

When the broadcast signal 100 consisting of a plurality of packets is received, the frame extracting unit 110 extracts program information for each broadcast program based on the received packets. Then, the frames constituting the program are stored in the plurality of buffers 120 for each program or each channel provided with the program by using the extracted program information. At this time, when the broadcast signal 100 is transmitted by the MPEG-2 scheme, the frame stored in the plurality of buffers 120 is preferably an I-frame or a P-frame, and one of the buffers is the current user. All frames (I, B, P-frames) for the program being watched are stored, transferred to the decoding means 140 and output through the display screen 160.

At this time, when the user wants to watch another program, that is, when the user wants to switch from the channel currently being viewed to another channel, the decoding means 140 corresponds to the channel selected by the user in response to the channel switching command received from the user. The frames stored in the associated buffer are immediately decoded and provided to the user through the display screen 160.

Therefore, it is possible for the user to perform channel switching more quickly by storing broadcast frames not only for the channel currently being watched but also for other channels.

In this case, as many buffers as the number of broadcast channels may be provided. In order to facilitate the description of the present invention, the plurality of buffers 120 may be referred to as a channel currently viewed by a user (hereinafter, referred to as a 'current channel'). A buffer for the first channel (hereinafter referred to as a 'first buffer'), and a buffer for the previous channel of the current channel (hereinafter referred to as a 'subchannel'). And a buffer for a subsequent channel of the current channel (hereinafter, referred to as 'high channel') (hereinafter, referred to as 'third buffer').

For example, if the broadcast channel is 6, 7, 9 and 11, if the user is currently watching 9, the current channel is 9, the lower channel is 7 and the upper channel is 11. .

2 is a block diagram illustrating a structure of an apparatus for performing channel switching according to an embodiment of the present invention.

Referring to FIG. 2, the apparatus 200 for performing channel switching includes a packet receiving module 210, a program information extracting module 220, a user input module 230, a channel switching control module 240, and a frame extracting module 250. ), A frame storage module 260, a decoding module 270, and a display module 280.

The packet receiving module 210 receives a broadcast signal composed of a plurality of packets. At this time, the received broadcast signal is assumed to be a broadcast signal made of the MPEG-2 method.

The program information extraction module 220 extracts program information of the current channel, the lower channel, and the upper channel based on the channel selection of the user and the packet identification information for identifying each packet.

The user input module 230 receives a channel selection from a user.

The channel switching control module 240 controls the program information extraction module 220, the decoding module 270, and the frame extraction module 250 according to the channel selection by the user so as to perform faster channel switching.

The frame extraction module 250 extracts a frame constituting broadcast content corresponding to the extracted program information. In this case, in the case of the lower channel and the upper channel, the frame extraction module 250 may include an I-frame and a P-frame (hereinafter referred to as an 'IP frame') or two P-frames (hereinafter, referred to as a 'PP frame'). Will be referred to as respectively).

The frame storage module 260 includes a first buffer, a second buffer, and a third buffer, and stores the frames extracted by the frame extraction module 250 in a corresponding buffer.

The decoding module 270 decodes the frames stored in the frame storage module 260, and the display module 280 outputs the decoded frames.

Meanwhile, the apparatus 200 for performing channel switching may distinguish an operation mode as a first mode indicating an operation before channel switching and a second mode indicating an operation when channel switching occurs. When the apparatus 200 for performing channel switching receives a channel switching command from the user while operating in the first mode, the apparatus 200 switches to the second mode, returns to the first mode after performing the operation according to the second mode. do.

Hereinafter, operations between the respective modules constituting the apparatus 200 for performing channel switching shown in FIG. 2 will be described in detail with reference to flowcharts shown in FIGS. 3 and 4.

3 is a flowchart illustrating operation in a first mode according to an embodiment of the present invention.

First, the packet receiving module 210 receives a broadcast signal composed of a plurality of packets (S310). At this time, each packet includes packet identification information to distinguish itself from other packets. In the case of a broadcast stream transmitted in MPEG-2 format, the packet identification information corresponds to a PID.

The program information extraction module 220 extracts packet identification information of a program for a current channel, a lower channel, and an upper channel (S320), and the frame extraction module 250 uses the extracted packet identification information for the current channel and lower channel. A frame for broadcast content in the channel and the upper channel is extracted (S330). In this case, packet identification information for each broadcast content may be obtained through a program allocation table (PAT) and a program map table (PMT) defined in the MPEG-2 standard.

For example, if the packet identification information of the packet received by the packet receiving module 210-that is, the PID value is 0, the received packet indicates a packet having PAT information. You can get the PID of the program currently being broadcast in the current channel, lower channel and upper channel by using PMT PID information in.

When the PID information of the received packet is a program PID for the current channel, the lower channel, and the upper channel, the PID information of the elementary stream (ES) required for each program can be obtained through the PMT PID information. . At this time, the elementary stream has video information or audio information.

The frame extraction module 250 extracts only an I-P frame or a P-P frame among programs constituting broadcast content, that is, broadcast content, in a lower channel and a higher channel. This is because decoding can be performed using only I-P frames or P-P frames.

Frames extracted by the frame extraction module 250 are stored in the frame storage module 260 (S340). The frame for the current channel is stored in the first buffer, the frame for the lower channel is stored in the second buffer, and the upper channel. The frame for the is stored in the third buffer.

The frame for the current channel among the stored frames as described above is decoded by the decoding module 270 and output through the display module 280. In addition, the I-P frame or P-P frame extracted by the frame extraction module 250 is updated and stored in the second buffer and the third buffer. In this case, the frames stored in the second buffer and the third buffer may be decoded and stored in advance by the decoding module 270.

4 is a flowchart illustrating operation in a second mode according to an embodiment of the present invention.

First, the user input module 230 receives a channel switching command from the user (S410). If the user requests to switch to the upper channel or the lower channel by using a channel switching input means (for example, two buttons for channel switching) provided in the infrared remote controller, the user input module 230 An infrared receiver module corresponding to the infrared remote controller is provided to receive an infrared signal, and transmits information on a corresponding command to the channel switching control module 240.

Then, the channel switching control module 240 causes the decoding module 270 to decode the frame previously stored in the frame storage module 260 for the channel requested by the user, thereby causing the display module 280 to decode. The outputted frame is output (S420).

For example, when the user requests to switch to the lower channel, since the IP frame or PP frame constituting the broadcast content in the lower channel is already stored in the second buffer in the frame storage module 260, the decoding module In operation 270, the frames stored in the second buffer are immediately decoded in response to the channel change command from the user and output through the display module 280.

If the frames stored in the second buffer and the third buffer have already been decoded, the decoding process by the decoding module 270 is omitted and the decoded frames stored in the second buffer are left as they are. Since it is output through, it is possible to provide the user with the image of the switched channel more quickly.

The program information extracting module 220 extracts packet identification information of a program for a lower or upper channel of the channel converted by the channel switching information received from the channel switching control module 240 (S430).

For example, if the broadcast channel is 6, 7, 9, 11, the user is switching to channel 7, which is a sub-channel of channel 9 while watching the current 9, the switched 7 Extracts the packet identification information of the program for channel 6, which is the lower channel of channel 1. In the case of channel 9, which is the upper channel of the switched channel 7, the packet identification information is already extracted by the program information extraction module 220 before the channel is switched, and in the case of channel 11, before the channel is switched Packet identification information was extracted, but after channel switching, packet identification information for channel 11 is no longer extracted.

Even when the user switches the channel from the current channel to the upper channel, the packet identification information on the upper channel of the switched channel may be extracted by the program information extraction module 220 according to the above method.

The frame extraction module 250 extracts a frame for the corresponding broadcast content using the extracted packet identification information (S440), and the extracted frames are stored in a corresponding buffer (S450).

At this time, the buffer in which the frames for the switched channel are stored becomes the first buffer, the buffer in which the frames for the lower channel of the switched channel are stored becomes the second buffer, and the frames for the upper channel of the switched channel are The buffer to be stored becomes the third buffer.

As mentioned above, all the frames constituting the broadcast content are stored in the first buffer, the frames stored in the first buffer are decoded by the decoding module 270, and then the decoded frames are output through the display module 280. do.

The I-P frame or P-P frame extracted by the frame extraction module 250 is updated and stored in the second buffer and the third buffer. In this case, the frames stored in the second buffer and the third buffer may be decoded and stored in advance by the decoding module 270.

Meanwhile, the decoding module 270 illustrated in FIG. 2 may include a plurality of decoders, and the display module 280 may connect the plurality of decoders to a plurality of buffers stored in the frame storage module 260. In addition to the current channel, the provided screen may also play broadcast contents in other channels. In this case, the user can simultaneously enjoy the content being broadcast on the various channels. 5A to 5C show a connection relationship between a buffer and a decoder.

Meanwhile, as described in the above embodiment, the user may directly switch to a desired channel by inputting a numeric key attached to a remote controller as well as an up / down button for channel switching, an example of which is illustrated in FIGS. 6A to 6E. .

In FIGS. 6A to 6E, in addition to a buffer for storing a frame of broadcast content for a channel currently output from the display module 280, 11 buffers are separately provided to display broadcast content for each channel in response to a user's numeric key input. The process of storing a frame is illustrated in detail. 6A to 6E illustrate that the user switches from the current channel to channel 251, and assumes that the channel exists from channel 0 to channel 999.

First, referring to FIG. 6A, broadcast content frames for channels 0 to 10 are stored in 11 buffers in an initial stage, before the user inputs a numeric key for channel switching. At this time, the frame of the corresponding channel is updated and stored as a new frame until the user inputs the numeric key. Each buffer includes not only physically separated but also logically separated, and the frame stored in each buffer is preferably an I-frame or a P-frame.

If the user selects the numeric key '2', the user input module 230 transmits the selected numeric key information to the channel switch control module 240, and the channel switch control module 240 uses the program information extraction module ( 220 extracts program information of channel 2 and channel 20 (channels 21 to 29). Then, the frame extraction module 250 extracts a frame in a corresponding channel based on the extracted program information, and the frame storage module 260 stores the extracted frame in a buffer for each channel. In FIG. 6A, frames of channel 2 have already been stored, and thus frames in channels 20 to 29 are newly stored. This is illustrated in Figure 6b.

Then, when the user selects the numeric key '5' again, the frames of channel 25 are already stored according to the above method, and the frames of channels 250 to 259 are divided into the remaining 10 buffers and newly stored. . This is illustrated in Figure 6c.

Then, when the user selects the numeric key '1' again, the frames of channel 251 have already been stored according to the same method, and since there are 999 channels, the frames of channels 0 to 9 are again stored. It is divided into two buffers and newly stored. This is illustrated in Figure 6d.

Finally, if the user selects 'OK', the decoding module 270 accesses the buffer storing the frame of channel 251, decodes the stored frame, and outputs the same through the display module 280. Then, the frame of channel 10 is stored in the buffer which previously stored the frame of the channel watched by the user. This is illustrated in FIG. 6E.

On the other hand, the channel number to be switched may be determined by the user's input of the 'OK' button.However, after a predetermined time has passed since the user inputs the last numeric key, the channel number may be determined as the channel number to be converted. have.

6A to 6E illustrate a process of pre-storing frames in other channels using 11 buffers, but the present invention is not limited thereto, and channels of a predetermined range are based on numeric key information input by a user. Alternatively, it may be understood that the method of pre-storing frames on specific channels is included in the scope of the present invention. Information about the channels corresponding to the input numeric key information may be preset in the apparatus for performing channel switching.

Meanwhile, the term 'module' used in the present embodiment refers to software or a hardware component such as an FPGA or an ASIC, and the module plays a role. However, modules are not meant to be limited to software or hardware. The module may be configured to be in an addressable storage medium and may be configured to play one or more processors. Thus, as an example, a module may include components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, subroutines. , Segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and modules may be combined into a smaller number of components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented to play one or more CPUs in a device or secure multimedia card.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited to drawing.

According to the present invention, when the user wants to change the channel, the channel is changed more quickly, thereby providing an image in the switched channel.

Claims (36)

(A) receiving a broadcast signal consisting of a plurality of packets; (B) extracting a frame by using packet identification information of the packet and storing the extracted frame for each channel; And (C) outputting a frame corresponding to a channel requested from a user among the stored frames. The method of claim 1, And the extracted frame is a frame for a current channel, a lower channel, and a higher channel. The method of claim 2, And the frames for the lower channel and the upper channel are I-frames or P-frames. The method of claim 2, And frames for the lower channel and the upper channel are decoded and stored. The method of claim 2, If the requested channel is the lower channel, extracting and storing a frame for the lower channel of the requested channel. The method of claim 2, (E) extracting and storing a frame for the upper channel of the requested channel when the requested channel is the upper channel. The method of claim 1, The broadcast signal is transmitted by the MPEG-2 scheme, and the packet identification information is a PID prescribed by the MPEG-2 standard. (A) receiving a channel switch request from a user; (B) outputting a frame already stored for the requested channel; (C) extracting packet identification information of a program for a lower or upper channel of the requested channel; (D) extracting a frame for broadcast content corresponding to the extracted packet identification information; And And (e) storing the extracted frame. The method of claim 8, And the frame for the lower channel or the upper channel is an I-frame or a P-frame. The method of claim 8, The step (e) may include decoding the extracted frame; And Storing the decoded frame. The method of claim 8, The program is a channel switching method is carried on a broadcast signal consisting of a plurality of packets. The method of claim 11, The broadcast signal is transmitted by the MPEG-2 scheme, and the packet identification information is a PID prescribed by the MPEG-2 standard. The method of claim 8, And the channel switch request is either a switch to an upper channel or a switch to a lower channel. A packet receiving module for receiving a broadcast signal consisting of a plurality of packets; A frame extraction module for extracting a frame using packet identification information of the packet; A frame storage module for storing the extracted frame for each channel; And And a display module configured to output a frame corresponding to a channel requested from a user among the stored frames. The method of claim 14, And the extracted frame is a frame for a current channel, a lower channel, and an upper channel. The method of claim 15, And the frame for the lower channel and the upper channel is an I-frame or a P-frame. The method of claim 15, And the frames for the lower channel and the upper channel are decoded and stored. The method of claim 15, If the requested channel is the sub-channel, And the frame extraction module extracts a frame for a lower channel of the requested channel and is stored by the frame storage module. The method of claim 15, If the requested channel is the upper channel, And the frame extraction module extracts a frame for a higher channel of the requested channel and is stored by the frame storage module. The method of claim 14, And the broadcast signal is transmitted by the MPEG-2 scheme, and the packet identification information is a PID defined by the MPEG-2 standard. A user input module to receive a channel switch request from a user; A display module for outputting a frame already stored for the requested channel; A program information extraction module for extracting packet identification information of a program for a lower or upper channel of the requested channel; A frame extraction module for extracting a frame for broadcast content corresponding to the extracted packet identification information; And And a frame storage module for storing the extracted frame. The method of claim 21, And the frame for the lower channel or the upper channel is an I-frame or a P-frame. The method of claim 21, And the frame storage module decodes and stores the extracted frame. The method of claim 21, The program performs a channel switching carried on a broadcast signal consisting of a plurality of packets. The method of claim 24, And the broadcast signal is transmitted by the MPEG-2 scheme, and the packet identification information is a PID defined by the MPEG-2 standard. The method of claim 21, And the channel switch request is either a switch to an upper channel or a switch to a lower channel. The first mode for storing the frames constituting the broadcast content in the lower channel and the upper channel for the current channel while outputting the broadcast content on the current channel, and outputting the pre-stored frame about the channel requested from the user, A channel switching control module configured to control an operation of a second mode of storing a frame constituting broadcast content in a lower channel or a higher channel of the channel; And And a user input module to receive a request from the user. The method of claim 27, And the frame for the lower channel or the upper channel is an I-frame or a P-frame. The method of claim 27, And the stored frame is decoded and stored. The method of claim 27, And broadcast information is transmitted on a broadcast signal including a plurality of packets distinguished by packet identification information. The method of claim 30, And the broadcast signal is transmitted by the MPEG-2 scheme, and the packet identification information is a PID defined by the MPEG-2 standard. Frame extraction means for extracting a frame representing broadcast content for each channel from a broadcast signal composed of a plurality of packets; A plurality of buffers for storing the extracted frames for each channel; Decoding means for decoding a frame stored in an arbitrary buffer among the plurality of buffers; And And a display screen for outputting the decoded frame. (A) receiving numeric key information for channel switching from a user; (B) storing frames for a plurality of channels corresponding to the received numeric key information for each channel; (C) determining a channel number to be converted based on the received at least one numeric key information; And And (d) decoding and storing the stored frame at the determined channel number. The method of claim 33, wherein The stored frame is an I-frame or a P-frame. The method of claim 33, wherein And the frame is a frame representing broadcast content for each channel in a broadcast signal composed of a plurality of packets. The method of claim 33, wherein And a plurality of channels corresponding to the numeric key information are channels within a preset channel range.

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