KR20110070644A - Channel switching system and method using sub multicast stream - Google Patents

Abstract

Provided are a channel switching system and method using a sub multicast stream, and more particularly, a system for improving a channel switching speed by separately transmitting a sub multicast stream including only a specific frame used for decoding broadcast data to a user terminal. And a method are provided.

The channel switching system using the sub multicast stream generates a main multicast stream corresponding to a broadcast channel and generates a sub multicast stream using I frames included in the video data of the main multicast stream. It may include a sub stream providing server for transmitting the generated sub multicast stream to the user terminal.

Sub Multicast Stream, I Frame, Channel Switching

Description

Channel switching system and method using sub-multicast stream {SYSTEM AND METHOD FOR CHANGING CHANNEL USING SUB MULTICAST STREAM}

The present invention relates to a channel switching system and method using a sub multicast stream. More particularly, the present invention relates to a channel switching speed by transmitting a sub multicast stream including only a specific frame used for decoding broadcast data to a user terminal. A system and method for improving.

Since the successful introduction of IPTV, efforts have been made in various fields to ensure and improve service quality. In particular, the improvement of IPTV channel switching speed in the field of guarantee and improvement of IPTV service quality has a significant effect on the user's customer satisfaction.

Typical digital cable channel switching speeds are known as 1 to 2.5 seconds, digital satellites are known to be 2 to 4 seconds, and typical IPTV channel switching speeds are recommended within 2 seconds. Developing technology by setting goals.

Furthermore, considering that the experiment suggests that 0.43 seconds is appropriate as a standard for the user's channel switching speed, reducing the IPTV channel switching speed is very important in providing IPTV services.

When switching to an IPTV channel, in order to switch to a new channel and display an image on the screen, an I frame serving as a RAP (random access point) that starts decoding of a multicast stream must be recognized.

Therefore, a delay occurs when switching to a new channel because it has to wait until an I frame is recognized. Typically, when transmitting a multicast stream corresponding to a GOP length of 15 frames at 30 fps, most of the frames depend on other frames transmitted earlier as differential code, i.e., P or B frames, and only I frames Contains all the information needed to decrypt.

According to the prior art, the tune-in server receives all the multicast streams, buffers tens of RAP cycles (GOPs) of each stream, and the tune-in server connects to the client with an access link when tuning according to channel switching. It uses the maximum bandwidth available in between to stream data from the last buffered RAP to the client, i.e., the set-top box, over a unicast connection.

In addition, in parallel, the client connects to the multicast stream, and if the multicast stream and the unicast stream are aligned or the data received in the unicast and multicast overlap, the client switches to the multicast stream and unicast. By breaking the connection, the client can use unicast content from the server only during the tuning period.

In addition, when a stream reflection server is placed in the access network such as a tune-in server, the tune-in server receives all multicast streams and buffers only the current RAP period of each stream.

When tuning according to channel switching, the tune-in server starts streaming from the last buffered RAP. Unlike the aforementioned method, the client never directly connects to multicast, but always forwards the packet to the client through the unicast connection through the reflection server.

This conventional technology uses a mixed or dedicated unicast connection based on a server that receives all multicasts, and operates in a form in which a large amount of traffic to the client side exists, thereby causing a burden of a small amount of fixed traffic. have.

In addition, in the case of channel switching according to the prior art, since most frames are occupied by B frames or P frames in a multicast stream, and I frames serving as RAPs are relatively small, a predetermined time is required to recognize I frames. There is a problem in that it takes more time to switch channels due to this.

According to an embodiment of the present invention, a multicast stream transmitted to a user terminal is divided into a multicast stream including all frames and a multicast stream including only an I frame, and the user terminal transmits two multicast streams more quickly. In order to improve the channel switching speed in the user terminal by searching for an I frame serving as a random access point (RAP) and decoding a multicast stream.

As a technical means for achieving the above-described technical problem, the first aspect of the present invention is to generate a main multicast stream corresponding to a broadcast channel and using the I frame included in the image data of the main multicast stream sub-multicast It is possible to provide a channel switching system using a sub multicast stream including a stream processing server for generating a stream and a sub stream providing server for transmitting the generated sub multicast stream to a user terminal.

In addition, the second aspect of the present invention is to generate a main multicast stream and a sub multicast stream corresponding to a broadcast channel, maintaining only the sub multicast stream generated within a predetermined time from the generated sub multicast stream, Receiving a request for switching to a specific channel from a user terminal, transmitting the sub-multicast stream and the main multicast stream generated within the predetermined time in response to the specific channel switching request to the user terminal; The main multicast stream includes I frames, P frames, and B frames for broadcast data transmitted through the broadcast channel, and the sub multicast stream includes I frames for the broadcast data. Is included in the sub multicast stream It is possible to provide a method for improving a channel switching speed by using a sub multicast stream for acquiring initial image data using the I frame.

According to the aforementioned problem solving means of the present invention, a user terminal receives a main multicast stream including all I frames, P frames and B frames, and a sub multicast stream including only I frames, and the I of the sub multicast stream. By decoding using a frame, an initial image is obtained, and then switched to a main multicast stream to obtain broadcast data, thereby providing a user with a broadcast of the switched channel more quickly.

In addition, according to the aforementioned problem solving means of the present invention, since the period of the I frame of the sub-multicast stream is shorter than the period of the I frame of the main multicast stream, the user terminal acquires broadcast data using only the main multicast stream. Since the broadcast data is acquired more quickly than in the case, the channel switching speed can be improved.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

1 is a diagram illustrating a configuration of a channel switching system using a sub multicast stream according to an embodiment of the present invention.

The channel switching system according to an embodiment of the present invention includes a broadcast transmission server 100, a stream processing server 200, a sub stream providing server 300, and a settop box (STB) 400.

The broadcast transmission server 100 transmits broadcast content, that is, broadcast data, for all channels currently being broadcast to the stream processing server 200.

The stream processing server 200 encodes broadcast data received from the broadcast transmission server 100 to generate a main multicast stream and a sub multicast stream. The stream processing server 200 encodes the main multicast stream to include all I, P, and B frames included in the broadcast data, and performs encoding so that only the I frames are included in the sub multicast stream.

The stream processing server 200 transmits the generated sub multicast stream to the sub stream providing server 300 and transmits the main multicast stream to the set top box 400 in response to a channel switching request of the set top box 400. .

The sub stream providing server 300 extracts and stores only the most recent sub multicast stream, that is, a sub multicast stream within a preset period, among the sub multicast streams received from the stream processing server 200.

The sub stream providing server 300 provides the set top box 400 with the latest sub multicast stream stored in response to the channel switching request of the set top box 400. That is, the sub-stream providing server 300 is within a predetermined time from the time when the first I frame included in the video data of the main multicast stream is transmitted to the set-top box 400 or received from the set-top box 400. The sub-multicast stream including the first I frame may be transmitted to the set-top box 400, and at this time, when the main multicast stream is received by the set-top box 400, the set-top box 400 provides the sub-stream providing server 300. ) May be determined by sending received information or adding a predetermined time from the time of transmission.

The sub-stream providing server 300 may provide a sub-multicast stream to a set-top box divided by region so as to be in charge of a regional user terminal, that is, set-top box.

The set top box 400 receives a channel switch request from the user, and transmits a channel switch request to the stream processing server 200 and the sub stream providing server 300. The set top box 400 receives the main multicast stream from the stream processing server 200 and the sub multicast stream from the sub stream providing server 300.

The set-top box 400 performs broadcast decoding using I frames included in the sub multicast stream to obtain broadcast data, and then converts the decoding target into the main multicast stream to obtain broadcast data.

2 is a diagram illustrating a configuration of a stream processing server in a channel switching system according to an embodiment of the present invention.

The stream processing server 200 according to an embodiment of the present invention includes a video data receiver 210, a main multicast stream processor 220, and a sub multicast stream processor 230.

The video data receiver 210 receives video data including broadcast content from a broadcast transmission server (not shown), and transmits the received video data to the main multicast stream processor 220 and the sub multicast stream processor 230. do.

The main multicast stream processor 220 encodes the received video data to generate a main multicast stream including all I frames, B frames, and P frames. The main multicast stream processor 220 transmits the main multicast stream generated in response to the channel switching request received from the set top box (not shown) to the set top box.

The sub multicast stream processor 230 encodes the received video data to generate a sub multicast stream including only I frames. The period of the I frame included in the sub multicast stream is shorter than the period of the I frame included in the main multicast stream.

The sub multicast stream processing unit 230 transmits the generated sub multicast stream to a sub stream providing server (not shown).

In one embodiment of the present invention, since the RAP (random access point) of the multicast stream in which video data is encoded is an I frame, the set-top box (not shown) is included in the multicast stream to decode the multicast stream back into video data. The I frame is searched, and decoding of the multicast stream is performed using the retrieved I frame.

Therefore, when the set-top box decodes using the sub multicast stream, decoding can be performed more quickly than when decoding using only the main multicast stream.

3 is a diagram illustrating a configuration of a sub stream providing server in a channel switching system according to an embodiment of the present invention.

The sub stream providing server 300 according to an exemplary embodiment of the present invention includes a sub multicast stream receiving unit 310, a sub multicast stream buffering unit 320, a sub multicast stream providing unit 330, and a sub multicast stream database. 340.

The sub multicast stream receiving unit 310 receives a sub multicast stream for all channels transmitted from a stream processing server (not shown), and stores the received sub multicast stream in the sub multicast stream database 340.

The sub multicast stream buffering unit 320 obtains the latest, that is, the recently received sub multicast stream among the sub multicast streams stored in the sub multicast stream database 340.

That is, the server multicast stream buffering unit 320 obtains only the sub multicast streams received within a predetermined period of the sub multicast streams stored in the sub multicast stream database 340, and obtains the sub multicast streams within the obtained predetermined period. It is stored separately in the sub multicast stream database 340 to maintain the latest sub multicast stream.

The sub multicast stream providing unit 330 receives a channel switch request, that is, a channel join request, from the user terminal, that is, the set-top box 400, and transmits to the sub multicast stream database 340 in response to the received request. The latest stored sub multicast stream is transmitted to the set top box 400.

The latest sub multicast stream transmitted by the sub multicast stream provider 330 to the set-top box 400 includes only an I frame which becomes a random access point (RAP) as described above, and the I of the sub multicast stream. The period of the frame is shorter than the period of the I frame of the main multicast stream.

The channel switching request of the sub multicast stream providing unit 330 may be transmitted from the set top box 400 to the sub stream providing server 300 through an IGMP (Internet Group Management Protocol) join message.

4 is a diagram illustrating a configuration of a set-top box in a channel switching system according to an embodiment of the present invention.

The set top box 400 according to the exemplary embodiment of the present invention includes a multicast stream receiver 410, a stream switcher 420, a decoder 430, and an outputter 440.

The multicast stream receiving unit 410 receives the main multicast stream from a stream processing server (not shown), and receives the latest sub multicast stream from the substream providing server (not shown).

The multicast stream receiver 410 simultaneously buffers and receives the main multicast stream and the sub multicast stream. The main multicast stream and the sub multicast stream are transmitted by the stream processing server and the sub stream providing server, respectively, in response to the channel switch request transmitted from the set-top box 400.

As described above, the main multicast stream includes not only I frames, but also B frames and P frames, and the sub multicast stream includes only I frames serving as a random access point (RAP). In addition, the period of the I frame included in the sub multicast stream is shorter than that of the I frame included in the main multicast stream.

The stream switching unit 420 provides a sub-multicast stream to the decoding unit 430 as a primary of two multicast streams received by the multicast stream receiving unit 410 according to channel switching.

When the decoding unit 430 decodes the broadcast data of the multicast stream using the I frame included in the sub-multicast stream provided as the primary, the stream switching unit 420 switches the stream to secondary the main multicast stream. The decoding unit 430 is provided.

The stream switching unit 420 provides the main multicast stream to the decoding unit 430, notifies the multicast stream receiving unit 410 of the stream switching, and the multicast stream receiving unit 410 stops receiving the sub multicast stream. Do it.

The decoding unit 430 first obtains I frames from the sub-multicast stream provided by the stream switching unit 420, decodes the multicast stream using the obtained I frames, and broadcasts data of the channel to be switched, In particular, the first image data of the channel to be switched is obtained.

As described above, the period of the I frame of the sub multicast stream is shorter than the period of the I frame of the main multicast stream, and the I frame corresponds to a random access point (RAP). If used, the RAP cycle is shortened. Accordingly, the decoding unit 430 may decode the multicast stream more quickly by using the sub multicast stream.

The decoder 430 acquires broadcast data using the sub multicast stream, receives the main multicast stream secondarily by the stream switching unit 420, decodes the received main multicast stream, and then broadcasts the broadcast data. Acquire it.

The output unit 440 receives broadcast data from the decoder 430, and transmits the received broadcast data to a display device such as a television to output a broadcast image.

5 is a signal flow diagram illustrating a flow of a channel switching method using a sub multicast stream according to an embodiment of the present invention.

In step S105, the broadcast transmission server 100 transmits broadcast data for all channels currently being broadcast to the stream processing server 200 in a streaming manner.

In step S110, the stream processing server 200 encodes the received broadcast data into a main multicast stream and a sub multicast stream. The main multicast stream generated by the stream processing server 200 includes all I frames, P frames, and B frames, while the sub multicast stream contains only I frames. In addition, the I frame of the sub multicast stream has a shorter period than the I frame of the main multicast stream.

In step S115, the stream processing server 200 transmits the sub multicast stream generated in step S110 to the sub stream providing server 300. The stream processing server 200 transmits all sub multicast streams generated for all channels to the sub stream providing server 300.

In step S120, the sub-stream providing server 300 buffers the sub-multicast stream received within a preset period of the sub-multicast streams received in step S115, that is, the recently received sub-multicast stream. It is stored in the database provided in the stream providing server 300.

In step S125, the set-top box 400 receives a switch request signal for a specific channel from the user, and requests the multicast stream of the specific channel to the stream processing server 200 and the sub-stream providing server 300. The set top box 400 may transmit an IGMP join message to the stream processing server 200 and the sub stream providing server 300 to request channel switching.

In step S130, the stream processing server 200 transmits the main multicast stream of the channel that the set-top box 400 requests to switch to the set-top box 400 in response to the channel switch request received in step S125. .

In step S135, the sub-stream providing server 300 responds to the channel switch request received in step S125, which is the latest sub-multicast stream of the channel requested by the set-top box 400 to switch, that is, step S120. The sub multicast stream received within a preset period stored in the transmission to the set-top box 400.

The sub-stream providing server 300 includes a sub-multicast stream including a specific I frame within a preset time from when a specific I frame included in the image data of the main multicast stream is transmitted to or received from the set-top box 400. It can be transmitted to the set-top box 400.

In step S140, the set-top box 400 performs decoding using the sub-multicast stream received in step S135 to obtain an initial image of a channel requested for switching. As described above, since the I frame is a RAP (random access point) in the multicast stream, the set-top box 400 includes only the I frame and uses a sub-multicast stream whose I frame period is shorter than the main multicast stream. The first image of the channel can be acquired within a short time.

After acquiring the first image, the set-top box 400 switches the multicast stream used for decoding from the sub multicast stream to the main multicast stream. The set top box 400 may obtain broadcast data of a channel for which switching is requested by decoding the switched main multicast stream. After switching, the set-top box 400 may continue to use the main multicast stream to obtain broadcast data and stop receiving the sub-multicast stream.

In step S145, the set-top box 400 outputs the first image and subsequent broadcast data acquired in step S140 to a display device such as a television to provide broadcast contents to the user.

One embodiment of the present invention can also be implemented in the form of a recording medium containing instructions executable by a computer, such as a program module executed by the computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, computer readable media may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transmission mechanism, and includes any information delivery media.

Although the methods and systems of the present invention have been described in connection with specific embodiments, some or all of their components or operations may be implemented using a computer system having a general hardware architecture.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

1 is a diagram illustrating a configuration of a system for improving channel switching speed by using a sub multicast stream according to an embodiment of the present invention;

2 is a diagram illustrating a configuration of a stream processing server in a system for improving channel switching speed according to an embodiment of the present invention;

3 is a diagram illustrating a configuration of a sub-stream providing server in a channel switching speed improving system according to an embodiment of the present invention;

4 is a view showing the configuration of a set-top box in the channel switching speed improvement system according to an embodiment of the present invention,

5 is a signal flow diagram illustrating a flow of a method for improving channel switching speed using a sub multicast stream according to an embodiment of the present invention.

Claims (8)

In a channel switching system using a sub multicast stream, A stream processing server generating a main multicast stream corresponding to a broadcast channel and generating a sub multicast stream using I frames included in video data of the main multicast stream; Sub stream providing server for transmitting the generated sub multicast stream to the user terminal Channel switching system comprising a. The method of claim 1, The substream providing server may include a subframe including the first I frame within a preset time from when the first I frame included in the image data of the main multicast stream is transmitted to the user terminal or when the user terminal is received at the user terminal. A channel switching speed improvement system for transmitting a multicast stream to a user terminal. The method of claim 1, The stream processing server A main multicast stream processor for generating a main multicast stream corresponding to the broadcast channel and providing a main multicast stream corresponding to the specific channel to the user terminal in response to a request for switching to a specific channel of the user terminal; A sub multicast stream processing unit generating the sub multicast stream and providing the sub multicast stream to the sub stream providing server; Including, And wherein the main multicast stream includes I frames, P frames, and B frames. The method of claim 3, wherein The sub stream providing server, A sub multicast stream buffering unit for obtaining a sub multicast stream within a preset period from among the sub multicast streams received from the stream processing server; A sub-multicast stream providing unit for providing a sub-multicast stream corresponding to the specific channel to the user terminal among the obtained sub-multicast streams in response to the request for switching to the specific channel by the user terminal; Channel switching speed improvement system comprising a. The method of claim 4, wherein The user terminal A multicast stream receiver for receiving a main multicast stream and a sub multicast stream corresponding to the specific channel; A decoding unit for acquiring the first image data using the I frame retrieved from the sub multicast stream; A stream switching unit for providing the main multicast stream to the decoding unit after the initial image data is obtained; Including, And the decoding unit obtains broadcast data after the initial image data using the main multicast stream provided by the stream switching unit. In the method of improving the channel switching speed using a sub multicast stream, Generating a main multicast stream and a sub multicast stream corresponding to the broadcast channel; Maintaining only the sub multicast stream generated within a predetermined time in the generated sub multicast stream; Receiving a request for switching to a specific channel from a user terminal, Transmitting the sub multicast stream and the main multicast stream generated within the predetermined time in response to the specific channel switching request to the user terminal; Including, The main multicast stream includes I frames, P frames, and B frames for broadcast data transmitted through the broadcast channel, the sub multicast stream includes I frames for the broadcast data, and the user terminal And acquiring initial video data using the I frame included in the sub multicast stream. The method of claim 6, And a period of I frames included in the sub multicast stream is shorter than a period of I frames included in the main sub multicast stream. The method of claim 6, And the user terminal acquires broadcast data after the initial video data using the main multicast stream.

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