KR100827825B1 - Method of video on demand streaming and storage medium storing program therefor - Google Patents

Abstract

A VOD(Video On Demand) service providing method and a recording medium for recording a program thereof are provided to manage a bandwidth of a content server efficiently in consideration of the number of terminals which request or receive a VOD service. A VOD service providing method comprises the following steps of: providing VOD streaming data responding to a VOD service request from one or more terminals(100)(S540,S550); computing an optimum transmission mode by using preset correlation; and converting a current transmission mode into the optimum transmission mode if the current transmission mode between a content server(130) and the terminal is different from the optimum transmission mode(S520). The correlation uses one or more terminals connected to the content server, a bandwidth assigned to the content server, and a payment policy.

Description

HDD service providing method and a recording medium having recorded thereon the program. {Method of video on demand streaming and Storage medium storing program therefor}

1 is an overall configuration diagram of a VOD service providing apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a flow in a case where a mode switch does not occur in a VOD service providing method according to an exemplary embodiment of the present invention.

3 is a diagram illustrating a configuration request message and a response message in the VOD service providing method according to an embodiment of the present invention.

4 is a diagram illustrating a transmission request message and a response message in a VOD service providing method according to an embodiment of the present invention.

5 is a diagram illustrating a flow when a mode switch occurs in the content server 130 in the method of providing a VOD service according to an embodiment of the present invention.

6 is a graph illustrating a case of switching from the RVOD mode to the NVOD mode according to an embodiment of the present invention.

FIG. 7 is a graph illustrating a case where a mode is switched from an NVOD mode to an RVOD mode according to an embodiment of the present invention. FIG.

8 is a diagram illustrating a mode switch request message and a response message according to an embodiment of the present invention.

The present invention relates to a VOD service providing method and a recording medium on which the program is recorded. More particularly, the present invention relates to a VOD service providing method and a recording medium on which the program is managed according to a client's demand. It is about.

Recently, the network environment is being developed by building a high-speed transmission environment, such as hybrid fiber coaxial cable (HFC), x digital subscriber line (xDSL), fiber to the home (FTTH). In addition, if BcN (Broadband convergence Network) is being promoted, the development of data communication technology and excellent bi-directional characteristics will lead to VOD (Video On Demand) / EOD (Education On Demand). ), It is possible to provide various advanced services such as multi-channel broadcasting service.

In general, VODs are classified into a Real Video On Demand (RVOD) mode and a Near Video On Demand (NVOD) mode according to a method of transmitting data.

RVOD mode is a 1: 1 service between the server and the client that allows users to select and watch video at the desired time. It's an interactive service that allows you to watch the video the same way you watch a video by providing features such as fast forward, reverse, and pause. However, even if the network becomes wider, there is a problem in that bandwidth is limited to serve tens of thousands and hundreds of thousands of users simultaneously in RVOD mode.

NVOD mode is a 1: n service that uses a broadcasting or multicasting method that can be accessed by multiple users on a single channel.The same program is repeatedly broadcasted over a plurality of channels at regular time intervals for each channel. Then, the client can see the desired program at the designated time, which is a way to reduce the cost of the server. However, the conventional NVOD mode does not support the interactive service, and there is a problem in that the user must take some access latency before watching the video.

Even if the content server uses the same bandwidth, NVOD mode can serve more users than RVOD mode. However, the fact that NVOD mode requires fewer channels than RVOD mode is a case of demanding video. NVOD mode has a problem that it is not effective for low demand video because it must always occupy the bandwidth of a fixed number of channels.

In order to solve the above-mentioned problems, the present invention proposes a VOD service providing method capable of managing bandwidth of a content server according to a client's demand, and a recording medium on which the program is recorded.

In addition, the present invention proposes a VOD service providing method for switching to the NVOD mode for streaming data with a large number of client requests in the content server, and RVOD mode for streaming data with a small number of client requests, and a recording medium on which the program is recorded. will be.

In addition, the present invention proposes a VOD service providing method and a recording medium on which the program is recorded so that the content server can control both the RVOD mode and the NVOD mode, and can switch between the two modes so as to respond to changes in user demand. .

Still other objects of the present invention will be readily understood through the following description of the embodiments.

In order to achieve the above object, according to an aspect of the present invention, in a method for providing a video on demand (VOD) service in a content server, (a) VOD streaming data in response to a VOD service request from one or more terminals; Providing a; (b) an optimal transmission mode using a predetermined correlation that takes one or more of a number of terminals connected to the content server, a bandwidth allocated to the content server, a communication environment between the terminal and the content server, and a charging policy; Calculating; And (c) if the current transmission mode between the content server and the terminal is different from the optimal transmission mode, switching the current transmission mode to the optimal transmission mode.

Step (c) may include: (c1) transmitting a mode switch request message to the terminal; And (c2) when receiving a response message corresponding to the mode change request message from the terminal, switching the current transmission mode to the optimal transmission mode.

The step (c2) may further include receiving, from the terminal, a time offset value of the VOD streaming data to be received by the terminal after switching to the optimal transmission mode.

In step (c2), if the response message is not received from the terminal, the VOD streaming data is transmitted using the current transmission mode, and monitoring whether connection is maintained between the terminal and the content server is performed. Can be.

As a result of the monitoring, when the connection between the terminal and the content server is not maintained, the VOD service using the current transmission mode may be stopped.

The mode switch request message may include one or more of a command sequence number CSeq, a target switching mode, a filename of VOD streaming data, a ContentID, and a port for message communication.

The current transmission mode or the optimal transmission mode may be one of Real Video On Demand (RVOD) and Near Video On Demand (NVOD).

(A) step (a1) receiving a configuration request message from the terminal; (a2) transmitting a first response message to the terminal in response to the configuration request message; (a3) receiving a transmission request message from the terminal; And (a4) transmitting a second response message to the terminal in response to the transmission request message.

The configuration request message includes one or more of a command sequence number, a file name of the VOD streaming data, and a content ID, wherein the file name and the content ID of the VOD streaming data are the content server. It may be provided to the terminal in a web server interlocked with.

When the current transmission mode is Near Video On Demand (NVOD), the first response message includes a command sequence number, a service type, a service state, and the VOD streaming data. One or more of TotalTime, MultiCasting IP, Start Port Number, StartPort, Number of Ports (ActivePort), and WaitTime (WaitTime) may be included.

When the current transmission mode is Real Video On Demand (RVOD), the first response message includes a command sequence number, a service type, a service state, and a VOD streaming data. It may include one or more of TotalTime.

The transmission request message may include one or more of a command sequence number, a file name of the VOD streaming data, a playback start point, and a playback end point.

According to another aspect of the present invention, there is tangibly implemented a program of instructions that can be executed by a content server to provide a video on demand (VOD) service, and a recording medium recording a program that can be read by the content server. A method comprising: (a) providing VOD streaming data in response to a VOD service request from one or more terminals; (b) an optimal transmission mode using a predetermined correlation that takes one or more of a number of terminals connected to the content server, a bandwidth allocated to the content server, a communication environment between the terminal and the content server, and a charging policy; Calculating; And (c) when the current transmission mode between the content server and the terminal is different from the optimal transmission mode, a recording medium recording a program for executing the step of switching the current transmission mode to the optimal transmission mode.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the same reference numerals will be used for the same means regardless of the reference numerals in order to facilitate the overall understanding.

1 is an overall configuration diagram of a VOD service providing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a VOD service providing apparatus according to an embodiment of the present invention may include one or more terminals 101, 102, and 103, a web server 120, and one or more content servers 131, 132, and 133. Can be.

Although not shown in FIG. 1, the mobile communication terminal 101 may be connected to the network 110 through a mobile communication network.

For example, when the mobile communication network is wideband code division multiple access (WCDMA), the mobile communication terminal 101 is connected to a network through a radio network controller (RNC), a serving GPRS support node (SGSN), and a gateway GPRS support node (GGSN). 110 can be connected.

Since the method of connecting the mobile communication terminal 101 to the network 110 through a mobile communication network is a well-known technique, detailed descriptions thereof will be omitted in order to clarify the gist of the present invention.

In addition, in order to facilitate the understanding and explanation of the present invention, one or more of the terminals 101, 102, and 103 are referred to as the terminal 100, and a video of various VOD streaming data will be described as an example. It is apparent to those skilled in the art that the present invention is not limited thereto.

The web server 120 may provide the terminal 100 with information about a content server corresponding to the VOD service request from the terminal 100.

The content server 130 may provide a VOD service to the terminal 100. In addition, the number of terminals receiving the VOD service may be monitored and the VOD service mode may be switched in consideration of the bandwidth allocated to the content server.

The VOD service providing method according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 8.

2 is a diagram illustrating a flow in a case where a mode switch does not occur in a VOD service providing method according to an exemplary embodiment of the present invention. 3 is a diagram illustrating a configuration request message and a response message in the VOD service providing method according to an embodiment of the present invention, Figure 4 is a transmission request in the VOD service providing method according to an embodiment of the present invention A diagram illustrating a message and a response message.

In order to facilitate the understanding and explanation of the present invention, in the present specification, the flow of an embodiment of the present invention will be described with reference to FIG. 2, but will be described in detail with reference to FIGS. 3 and 4 where necessary.

Referring to FIG. 2, in step S201, the terminal 100 requests a connection to the web server 120, and in step S202, the web server 120 may provide session information to the terminal 100. In addition, the web server 120 may provide the terminal 100 with video details held by the one or more content servers 130.

Here, although not shown in Figure 2, it is apparent to those skilled in the art that there may be an authentication process for the terminal and / user in the web server 120.

Subsequently, in step S211, the terminal 100 requests the web server 120 for one or more videos selected by the user, and the web server 120 provides information on the content server 130 including the requested video. 100).

In this case, the information on the content server 130 may include an IP address of the content server, information on a communication port of the content server, and a content ID.

The content ID is a unique identification number assigned by the content server 130 to the service for the video file, and is stored in the web server 120 in advance.

For example, when there is a video file called 'monster' in the content server 130, the same video file is served in the NVOD mode as the first service, and the RVOD service is performed in the second service. The content ID is given differently so that it can be identified for each service.

Subsequently, when there is an authentication process for the terminal and / or the user in the web server 120 (not shown in FIG. 2), the terminal 100 and / or the user information is transferred from the web server 120 to the content server (step S213). 130).

Subsequently, the content server 130 may receive a configuration request message from the terminal 100 in step S221, and the content server 130 may transmit a response message to the terminal 100 in step S222. .

3A is a diagram illustrating an example of an environment setting message according to an embodiment of the present invention. Referring to FIG. 3A, the configuration message may include one or more of a command sequence number (hereinafter, referred to as 'CSeq'), a corresponding video file name, and a content ID.

Here, the configuration message serves to inform the content server 130 to prepare to transmit the video file and to request a description of the corresponding service as a response message.

FIG. 3B is a diagram illustrating a response message to an environment setting message when a content server services in an NVOD mode according to an embodiment of the present invention. More specifically, it is a diagram illustrating an example of a response message in the case of straggered broadcasting in the NVOD mode.

Referring to (b) of FIG. 3, the response message includes a command sequence number (CSeq), a service type (Service Type), a service operation state, a total length of video data (TotalTime), a multicast group IP ( It may include one or more of MultiCasting IP), a starting port number (StartPort), the number of ports (ActivePort), and a wait time (WaitTime).

3 (c) is a diagram illustrating a response message to an environment setting message when a content server services in an RVOD mode according to an embodiment of the present invention.

Referring to (c) of FIG. 3, the response message may include one or more of a command sequence number (CSeq), a service type, a service operation state, and a total length of video data. have.

Since the components included in the response message (refer to (b) and (c) of FIG. 3) are well-known elements, detailed descriptions thereof will be omitted herein for clarity.

Referring back to FIG. 2, in step S231, the content server 130 may receive a transmission request message from the terminal 100 and transmit a response message to the terminal 100 in step S232.

Here, the transmission request message plays a role similar to that of Real Time Streaming Protocol (RTSP) in the RVOD mode. More specifically, the transmission request message according to an embodiment of the present invention may inform the content server 130 of the start of playback and the end of playback when the content server 130 is in the RVOD mode.

In the case where the content server 130 is in the NVOD mode, since the video stream is unilaterally transmitted to the terminal through the multicast IP, it is unnecessary to use the above-described transmission request message. However, according to an embodiment of the present invention, the above-described transmission request message may be used even when the content server 130 is in the NVOD mode in order to monitor the number of terminals receiving the VOD service.

Referring to FIG. 4A, a transmission request message according to an embodiment of the present invention may include one or more of a command sequence number (CSeq), a video data name (File), a playback start point (StartOffset), and a playback end point. It may include.

4A illustrates an example of a transmission request message that the content server 130 receives from the terminal 100. FIG. 4B illustrates a response message that the content server 130 transmits to the terminal 100. Referring to FIG. It is an example.

In the transmission request message of FIG. 4A according to an embodiment of the present invention, a command sequence number (CSeq), a video data name (File), and a playback start point (StartOffset) are illustrated, but a playback end point may be included. It will be apparent to those skilled in the art.

4B may include a command sequence CSeq as a response message to the above-described transmission request message.

Referring back to FIG. 2, in operation S240, an audio file and an image file of video data requested by the terminal 100 may be transmitted from the content server 130 to the terminal 100 by using a Realtime Transport Protocol Control Protocol (RTCP). have.

Herein, in order to facilitate understanding and explanation of the present invention, video data (that is, Realtime Transport Rpotocol Control Protocol) and RTP (real-time transport protocol) are used between the content server 130 and the terminal 100. The audio files and video files of the video are transmitted. However, it is apparent to those skilled in the art that the present invention is not limited thereto and that various protocols may be used to transmit the multimedia stream.

Subsequently, when transmission of the video data requested by the terminal 100 is terminated, the content server may receive a session or service termination message from the terminal 100 in step S251, and transmit a response message to the terminal 100 in step S252.

Herein, the above-described session or service termination message and response message may be transmitted to one of the terminal 100 and the content server 130 to another one, and the contents thereof may be, for example, a command sequence number CSeq. It is obvious to those skilled in the art.

Up to now, the flow in the case where the mode switching does not occur in the content server 130 in the VOD service providing method according to an embodiment of the present invention. Hereinafter, a flow in a case where a mode switch occurs in the content server 130 will be described with reference to FIGS. 5 and 6.

5 is a diagram illustrating a flow when a mode switch occurs in the content server 130 in the method of providing a VOD service according to an embodiment of the present invention, and FIG. 6 is a diagram illustrating an RVOD mode in accordance with an embodiment of the present invention. FIG. 7 is a graph illustrating a case of mode switching to the NVOD mode, FIG. 7 is a graph illustrating a case of mode switching to the RVOD mode from the NVOD mode according to an embodiment of the present invention, and FIG. 8 is a diagram of an embodiment of the present invention. FIG. 9 illustrates a mode change request message and a response message.

In the following, descriptions duplicated with the contents described with reference to FIGS. 2 to 4 will be omitted to clarify the gist of the invention.

According to an embodiment of the present invention, when the number of the terminal 100 requests the VOD service to the content server 130 or receives the VOD service from the content server 130, the number of the terminal 100 is small in the NVOD mode. In this case, the bandwidth can be efficiently managed by the content server 130 by switching to the RVOD mode.

More specifically, there are some differences for each NVOD mode, but in general, increasing the latency can reduce the channel. And as the channel shrinks, so does the bandwidth. In the RVOD mode, since it is a 1: 1 service between the terminal 100 and the content server 130, when a service request comes in to the content server 130, the bandwidth is allocated as much as the video bandwidth for each request, but in the NVOD mode, the service request is performed. Regardless, the channel is allocated as much as the preset channel and occupies the bandwidth corresponding thereto.

Therefore, according to the number of the terminal 100 requesting the VOD service or the VOD service to the content server 130, the content server 130 needs to switch to the NVOD mode or the RVOD mode for efficient bandwidth management. The transition between NVOD mode and RVOD mode is called 'mode switch'.

Hereinafter, the bandwidth of the content server 130 in the case of switching the mode from the RVOD mode to the NVOD mode will be described with reference to FIG. 6. The graph of FIG. 6 illustrates a case where it is assumed that a VOD service request increases from the terminal 100 to the content server 130 by one every 10 seconds, the bandwidth of the content server 130 is 100 Mbps, and one video is VOD service. It's a graph. When the number of terminals requesting the VOD service increases and the limit bandwidth of the content server 130 is reached (for example, 14 minutes and 40 seconds in the graph of FIG. 6), the content server 130 switches from the RVOD mode to the NVOD mode. can do. In this case, as the plurality of terminals 100 are switched to NVOD, the overall bandwidth (ie, 'band total' in FIG. 6) of the content server 130 may be reduced.

Hereinafter, referring to FIG. 7, when the mode is switched from the NVOD mode to the RVOD mode, the bandwidth of the content server 130 will be described. In the graph of FIG. 7, when the bandwidth of the content server 130 is 100 Mbps and one video is VOD service, the terminal connected to the content server 130 is terminated once every 10 minutes, and the new terminal every 30 minutes. This is the case with the VOD service request. More specifically, the number of terminals decreases by one every 10 minutes until the number of terminals connected to the content server 130 is two.

For example, in NVOD mode, a predetermined bandwidth of 9Mbps can be allocated. Even when the number of terminals connected to the content server 130 is extremely small, allocating a predetermined bandwidth of 9Mbps is inefficient in bandwidth management of the content server 130. Accordingly, according to an embodiment of the present invention, the content server may provide a VOD service by switching from the NVOD mode to the RVOD mode. According to an embodiment of the present invention, when switching to RVOD, only 4 Mbps of bandwidth is used, and thus bandwidth management can be more efficient than NVOD mode using 9 Mbps.

As described above, the number of the terminal 100 requesting the VOD service and the limit bandwidth of the content server 130 have a close correlation. Furthermore, the communication environment and various charging policies may be additionally considered. Accordingly, one or more factors including the number of terminals 100 connected to the content server 130, the bandwidth allocated to the content server 130, the communication environment between the terminal 100 and the content server 130, and a charging policy may be used as factors. It will be apparent to those skilled in the art that the preset correlation may be stored in the content server 130.

For convenience of explanation, hereinafter, the current VOD service mode is referred to as a 'current transmission mode' between the terminal 100 and the content server 130, and the number of the terminal 100 and the number of the content server 130 in the content server 130 are described. The VOD service mode calculated using the limit bandwidth and the pre-stored table is called 'optimal mode'.

Referring back to FIG. 5, when the VOD service mode is switched with reference to a pre-stored table, the content server 130 transmits a mode switch request message to the terminal 100 and receives a response message from the terminal 100 accordingly. can do.

Referring to (a) of FIG. 8, the mode switching request message according to an embodiment of the present invention may include a command sequence number CSeq, a target switching mode, a filename of VOD streaming data, a content ID, and a ContentID. It may include one or more of a port (ListenerPort) for message communication.

Herein, the conversion target mode (Target) is a mode in which the content server 130 wants to switch the VOD service mode, and FIG. 8A illustrates an example of switching from the NVOD mode to the RVOD mode.

A port for message communication (ListenerPort) is a port for message (for example, configuration request message, transmission request message, service termination message) communication between the content server 130 and the terminal 100. In step S202 of FIG. The web server 120 may be information on a communication port of the content server 130 transmitted to the terminal 100. In addition, the content server 130 is a port for the message communication between the terminal 100 even after switching from the current transmission mode to the optimal transmission mode.

It is apparent to those skilled in the art that (b) of FIG. 8 may be a command sequence number CSeq as an example of a response message of the terminal 100 to the mode change request message described above.

Referring back to FIG. 5, in operation S510, the terminal 100 may transmit a response message to the content server in response to the mode switch request message, and then calculate a time offset value of video data to be received in the switched mode.

Subsequently, in step S520, the content server 130 may switch the VOD service mode with respect to the terminal 100 that has transmitted the response message in response to the mode switch request message.

Hereinafter, in step S530, the descriptions overlapping with the descriptions provided with reference to FIG. 2 will be omitted.

In this case, the transmission request message in step S540 may include a playback start time and / or a playback end time (see S231 of FIG. 2). In more detail, the transmission request message may include a playback start time and / or playback end time calculated using the time offset value of the video data calculated in step S510.

Therefore, the content server 130 may transmit the corresponding video data in step S550 using the above-described playback start time and / or playback end time after the mode conversion.

According to an embodiment of the present invention, in step S520, the content server 130 switches the VOD service mode for the terminal 100 that transmitted the response message corresponding to the mode switch request message.

For example, in the process of providing the VOD service in the NVOD mode in the content server 130, it will be described below on the assumption that there are two terminals 100 requesting the VOD service (that is, the first terminal and the second terminal). do. That is, the case where the current transmission mode is the NVOD mode and the optimum transmission mode is the RVOD mode will be described with an example.

When two terminals request the VOD service, the RVOD scheme of allocating bandwidth of each video channel to the terminals is more efficient for bandwidth management of the content server 130 than the NVOD mode of allocating a predetermined amount of channels.

Accordingly, the content server 130 may transmit a mode change request message to the first and second terminals to switch to the RVOD mode, which is an optimal transmission mode.

In the following description, it is assumed that the content server 130 receives a response message from the first terminal and does not receive a response message from the second terminal.

The content server 130 may switch to the RVOD mode, which is an optimal transmission mode, for the first terminal that transmits the response message, and transmit video data in the NVOD mode, which is the current transmission mode, for the second terminal that does not transmit the response message. .

Here, according to an embodiment of the present invention, the content server 130 may monitor whether the second terminal is connected to the content server at a predetermined time unit.

If the second terminal is not connected to the content server 130 as a result of the monitoring, the content server 130 may stop the VOD service in the NVOD mode, which is the current transmission mode, regardless of whether a response message is received from the second terminal. .

Therefore, according to the embodiment of the present invention, the bandwidth of the content server 130 may be efficiently managed in consideration of the number of the terminal 100 requesting the VOD service or receiving the VOD service.

The above-described embodiments of the present invention are disclosed for the purpose of illustration, and those skilled in the art may make various modifications, changes, and additions within the spirit and scope of the present invention. Should be considered to be within the scope of the following claims.

As described above, the VOD service providing method and a recording medium on which the program is recorded according to the present invention have an advantage of managing bandwidth of a content server according to a demand of a client.

In addition, the present invention has the advantage that the content server can switch to NVOD mode for streaming data with a large number of client requests, and to RVOD mode for streaming data with fewer client requests.

In addition, the present invention has the advantage that can be switched between the two modes to control both the RVOD mode and NVOD mode in the content server, and to respond to changes in user demand.

Claims (13)

In the method for providing a video on demand (VOD) service in the content server, (a) providing VOD streaming data in response to a VOD service request from one or more terminals; (b) calculating an optimal transmission mode using a predetermined correlation which takes one or more of a number of terminals connected to the content server, a bandwidth allocated to the content server, and a charging policy; And (c) if the current transmission mode between the content server and the terminal is different from the optimal transmission mode, switching the current transmission mode to the optimal transmission mode, Step (a) includes the step (a1) of transmitting a first response message to the terminal in response to the configuration request message received from the terminal, The configuration request message includes one or more of a command sequence number (CSeq), a conversion target mode (Target), a file name of VOD streaming data, a ContentID, and a port for message communication (ListenerPort). How to provide VOD service. The method of claim 1, Step (c) is (c1) transmitting a mode change request message to the terminal; And (c2) if a response message corresponding to the mode switch request message is received from the terminal, switching the current transmission mode to the optimal transmission mode; The method of claim 2, Step (c2) is And receiving a time offset value of the VOD streaming data to be received by the terminal from the terminal after switching to the optimal transmission mode. The method of claim 2, Step (c2) is If the response message is not received from the terminal, the VOD streaming data is transmitted using the current transmission mode, And monitoring whether a connection is maintained between the terminal and the content server. The method of claim 4, wherein If the connection between the terminal and the content server is not maintained as a result of the monitoring, stopping the VOD service using the current transmission mode. The method of claim 2, The mode switch request message is A method of providing a VOD service comprising at least one of a command sequence number (CSeq), a conversion target mode (Target), a file name of VOD streaming data, a ContentID, and a port for message communication. The method of claim 1, The current transmission mode or the optimal transmission mode Method of providing a VOD service, characterized in that one of RVOD (Real Video On Demand) and NVOD (Near Video On Demand). delete delete The method of claim 1, The first response message When the current transmission mode is NVOD (Near Video On Demand), the command sequence number (Service Sequence Number), service type (Service Type), service operation state (state), the total length of the VOD streaming data (TotalTime), A method of providing a VOD service comprising at least one of a multicast group IP, a starting port number, a starting port number, a number of ports, an active port, and a waiting time. The method of claim 1, The first response message If the current transmission mode is RVOD (Real Video On Demand), the command sequence number (Service Sequence Number), service type (Service Type), service operation state (state) and the total length of the VOD streaming data (TotalTime) A VOD service providing method comprising at least one. The method of claim 1, The step (a) further comprises the step (a2) after the step (a2) further comprising the step of transmitting a second response message to the terminal corresponding to the transmission request message received from the terminal, And the transmission request message includes one or more of a command sequence number, a file name of the VOD streaming data, a playback start point, and a playback end point. In order to provide a video on demand (VOD) service, a program of instructions that can be executed by a content server is tangibly implemented, and in a recording medium recording a program that can be read by the content server, (a) providing VOD streaming data in response to a VOD service request from one or more terminals; (b) calculating an optimal transmission mode using a predetermined correlation which takes one or more of a number of terminals connected to the content server, a bandwidth allocated to the content server, and a charging policy; And (c) if the current transmission mode between the content server and the terminal is different from the optimal transmission mode, changing the current transmission mode to the optimal transmission mode; Step (a) includes the step (a1) of transmitting a first response message to the terminal in response to the configuration request message received from the terminal, The configuration request message includes one or more of a command sequence number (CSeq), a conversion target mode (Target), a file name of VOD streaming data, a ContentID, and a port for message communication (ListenerPort). Record carrier recording the program.

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