KR101104729B1 - System and Method for Multimedia Streaming of Distributed Contents Using Optimal Way of Acquiring Segments - Google Patents

Abstract

The present invention relates to a content distributed storage multimedia streaming system and method using an optimal cache fragment acquisition method. The present invention distributes and stores the fragmented cache fragments in a cache server of several nodes, and the node receiving the client's streaming request checks the cache fragment storage information and the node state information of each node to determine an optimal cache fragment acquisition method. And obtain cache fragments of other nodes accordingly. That is, the present invention optimizes the performance of the entire network by distributing the load of the streaming node to other nodes by transmitting the cache fragments of other nodes via the node closest to the streaming node while the streaming node is receiving the specific cache fragments. And improve the quality of service.

Streaming, CDN, multimedia content, node, cache server, cache fragment

Description

System and Method for Multimedia Streaming of Distributed Contents Using Optimal Way of Acquiring Segments}

The present invention relates to a multimedia streaming service. More specifically, the multimedia content to provide a streaming service is divided into multiple cache pieces, distributed and stored in a cache server of multiple nodes, and a streaming node receiving a streaming request from a client is a node of another node. The present invention relates to a streaming system and method for determining an optimal cache fragment acquisition method by checking cache fragment storage information and node state information, acquiring cache fragments, and performing streaming.

With the development of internet technology, a streaming service that receives multimedia content such as video or animation through the internet in real time is being activated. Streaming refers to a technique of playing in real time while buffering a certain amount of the entire file, unlike a download method of playing after receiving all multimedia content files. Since the rest is continuously transmitted while playing back the buffered part, it is called 'streaming' because the transmitted data is treated as if it were a continuous, continuous stream of water. Such streaming services include real time broadcast services or video on demand services.

Meanwhile, with the explosive increase in video content including user created contents (UCC), Internet traffic has been increasing rapidly in recent years. The growth rate of Internet bandwidth (supply) is not able to keep pace with the growth rate of Internet traffic (demand). In 2007 alone, global Internet traffic grew 75 percent, but Internet bandwidth grew only 44 percent.

As a way to solve the shortage of Internet bandwidth, CDN (content delivery network) technology is attracting attention. CDN technology is a technology that can utilize the internet network more efficiently by using active traffic distribution to increase average network utilization and lower peak traffic. According to the CDN technology, the content provider replicates the content to be provided to the client to a plurality of locally distributed servers, and when requested by the client, the content provider can receive the content from the optimal server.

In addition, one of the technologies widely used to increase the data transmission speed of the subscriber end in a data service such as streaming is a cache technology. In a typical cache implementation, an object to be cached is composed of data units of various sizes, and based on this, the cache server generates various statistics for managing data.

However, this method does not cover various types of resources of the cache server (RAM size, storage space, total content capacity of the original content provider server, etc.), instability of the internet transmission speed, and various behavioral characteristics of the user's use of the content (during downloading or streaming). , Etc.), and various sizes of data to be cached, the following problems occur when the object unit handled by the cache server depends on the content size.

1. Inefficiencies due to inconsistent utilization of computing resources when dealing with large and small files

2. Inconsistent quality of service (QoS) for users who requested files of different sizes

3. Splitting that occurs when a user's request for a file is not terminated normally (that is, if the user's request saves the entire file to a cache server or memory but is interrupted in the middle), the overall efficiency is reduced.

As a solution to this problem, a technique for dividing a large amount of multimedia contents of various sizes into a plurality of fixed sized cache segments and distributing them in a cache server of several nodes is already known. This allows you to load balance the entire system through distributed data storage, and to make the physical performance (RAM, CPU, network bandwidth, etc.) of a single server hardware behave as if it is more than one cache server, for example a hardware barrier of a single server (e.g., Maximum memory size).

However, the conventional content distributed streaming technology focuses on distributed storage of data, and researches how it is most efficient to collect and stream cache fragments of adjacent nodes when a client requests streaming. There is not enough.

Accordingly, the present invention is to solve the conventional problem, and when the streaming request from the client in the content distributed storage multimedia streaming service to collect the cache fragments and perform streaming in the most efficient manner in terms of overall performance and service quality of the network. It is to provide a multimedia streaming system and method.

In order to achieve the above object, the present invention provides a content distributed storage multimedia streaming system and method using an optimal cache fragment acquisition method.

Contents distributed storage multimedia streaming system according to the present invention, a content providing server for providing multimedia content; A plurality of nodes distributed geographically between the content providing server and a plurality of clients; And a cache server provided in each of the nodes, the cache server storing cache fragments in which the multimedia contents are divided, and the cache server of the streaming node that has received a streaming request from the client among the nodes, the cache fragment of the node. A cache fragment obtaining method determining unit configured to determine an optimal cache fragment obtaining method based on stored information and node state information, an inter-node communication unit obtaining the cache fragments from another node according to the cache fragment obtaining method, and the inter-node communication unit The streaming control unit for transmitting the cache pieces obtained through the streaming method to the client.

The content distributed storage multimedia streaming system is provided in each node, and stores the cache piece storage information and the node state information, and an index for providing the cache piece storage information and the node state information to the cache server. The server may further include.

The cache fragment storage information may include a file name, a reproduction priority, a size, and a storage time of the cache fragment stored in each node. The node state information may include a distance between nodes, a remaining memory capacity of each node, and a node between nodes. It may include a transmission delay time.

In addition, the cache fragment obtaining method may be a method in which the cache fragment transmission is performed to the streaming node via the node closest to the streaming node when the reproduction priority is not the fastest cache fragment.

On the other hand, according to the present invention, the content distributed storage multimedia streaming method is distributed locally and distributed between a content providing server providing a multimedia content and a plurality of clients, and each cache fragment in which the multimedia content is divided is stored in a cache server. Receiving a streaming request of the client from the specific node when the client accesses a specific node of the plurality of nodes to request streaming; Determining, by the cache server of the specific node, an optimal cache fragment acquisition method based on cache fragment storage information and node state information of the node; And obtaining, by the cache server of the specific node, the cache fragments from another node according to the cache fragment acquisition method, and streaming the cache fragments to the client.

The content distributed storage multimedia streaming method may further include, by the cache server of the specific node, querying the index server for the cache fragment storage information and the node state information and receiving a response.

The cache fragment storage information may include a file name, a reproduction priority, a size, and a storage time of the cache fragment stored in each node. The node state information may include a distance between nodes, a remaining memory capacity of each node, and a node between nodes. It may include a transmission delay time.

In addition, the cache fragment obtaining method may be a method in which the cache fragment transmission is performed to the streaming node via the node closest to the streaming node when the reproduction priority is not the fastest cache fragment.

As described above, the present invention distributes and stores the divided pieces of cache in a cache server of several nodes, and the node receiving the streaming request of the client checks the cache pieces storing information and the node state information of each node to obtain an optimal cache piece based on this. Determine the scheme and obtain cache fragments of other nodes accordingly. That is, the present invention optimizes the performance of the entire network by distributing the load of the streaming node to other nodes by transmitting the cache fragments of other nodes via the node closest to the streaming node while the streaming node is receiving the specific cache fragments. And the quality of service can be improved.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention. In describing the embodiments, descriptions of technical contents that are well known in the art to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly communicate without obscure the core of the present invention by omitting unnecessary description. In addition, like reference numerals designate like or corresponding elements throughout the accompanying drawings.

1 is a view schematically showing the configuration of a multimedia streaming system according to the present invention, Figure 2 is a view showing the configuration of the multimedia streaming system and the content distribution storage method according to an embodiment of the present invention.

Referring to FIG. 1, the multimedia streaming system of the present invention includes a plurality of nodes distributed locally distributed between a content providing server CP and a plurality of clients C1, C2, C3, C4, C5,. node; N1, N2, N3, ..., Nn).

Content providing server (CP) is a server that stores the original of the multimedia content to provide a streaming service, also called an origin server (origin server), multimedia server, content server. The content providing server CP distributes and stores a copy of the multimedia content in each node N1, N2, N3, ..., Nn according to a predetermined content distribution storage policy. Multimedia content includes UCC and other video content, online education, mass media content such as movies, broadcasts, music, recording and live broadcast content.

As illustrated in FIG. 2, each node N1, N2, N3, N4, N5 has a cache server CS. The cache server (CS) supports the real-time streaming protocol (RTSP) of the international standard IETF RFC2326 and the real-time transport protocol (RTP) / RTP control protocol (RTCP) of the IETF RFC3550 to perform streaming.

The multimedia content MC is divided into several cache segments S1 to S5 and distributed and stored in the cache servers CS of the nodes N1 to N5. At this time, all cache fragments of the multimedia content are distributed and stored in at least two nodes, and at least one cache fragment is stored in the cache server of the node in charge of storage. In the example of FIG. 2, the multimedia content MC is divided into five cache pieces S1 to S5 and distributed and stored in five nodes N1 to N5.

The cache fragmentation of the multimedia content MC is performed according to a predetermined predetermined rule, and the content fragmentation rule may be determined in various ways such as a frame unit, a time unit, and a capacity unit. In addition, the content division rule may be determined differently for each content type or may be determined collectively regardless of the content type. In addition, the content partitioning rule may be determined in proportion to the storage capacity of each node or may be determined regardless of the node storage capacity.

Each node N1-N5 also has an index server IS. The index server IS stores cache fragment storage information on how many cache fragments S1 to S5 of the multimedia content MC are stored in which nodes N1 to N5. That is, the cache fragment storage information of the index server IS includes a file name, reproduction priority, size, storage time, etc. of the cache fragments stored in each node. The index server IS also stores node state information such as distance between nodes, remaining memory capacity of each node, and transmission delay time between nodes.

Meanwhile, the client C1 includes one or more buffers B for receiving and temporarily storing streaming data. The client C1 encompasses various electronic devices capable of receiving, decoding and playing streaming data. For example, the client C1 may be a computer, a set top box, a personal digital assistant (PDA), a mobile phone, a game machine, an MP3 player, or the like.

The cache server will be described in more detail with reference to FIG. 3 showing a detailed configuration of the cache server CS.

Each cache server CS may include a streaming controller 11, a content cache fragment storage unit 12, a cache fragment acquisition method determiner 13, and an inter-node communication unit 14.

The streaming control unit 11 receives the streaming request from the client C1 and transmits the requested content to the client C1 in a streaming manner.

The content cache fragment storage unit 12 stores the cache fragments allocated to its own node among the cache fragments in which the content is divided, and transmits the cache fragments to the client C1 through the streaming control unit 11.

When the streaming control unit 11 receives the streaming request from the client C1, the cache fragment obtaining method determination unit 13 accesses the index server IS and inquires and confirms the cache fragment storage information and the node state information of each node. Based on this information, the optimal cache fragment acquisition method is determined.

The inter-node communication unit 14 obtains cache fragments from other nodes if its node is a streaming node, and transmits the cache fragments to the client C1 through the streaming control unit 11, and if not, the node 14 transmits the cache fragments to the content cache fragment storage unit 12. The stored cache fragment is transmitted to the cache server of the streaming node.

Next, a multimedia streaming system and method according to an embodiment of the present invention will be described in more detail with reference to FIGS. 2 to 4. 4 is a flowchart illustrating a multimedia streaming method according to an embodiment of the present invention.

In the example of FIGS. 2 to 4, it is assumed that the cache fragments S1 to S5 divided into five are distributed and stored in five nodes N1 to N5, respectively, and have a reproduction priority in numerical order. That is, the cache fragment S1 stored in the cache server of node N1 has the fastest reproduction priority, and the cache fragment S5 stored in the cache server of node N5 has the lowest reproduction priority. In addition, in FIG. 4, it is assumed that adjacent nodes have the same distance between nodes. That is, the distance between node N1 and node N2 and the distance between node N2 and node N3 are equal, the distance between node N2 and node N4 is twice the distance between node N1 and node N2, and the distance between node N2 and node N3 is 3 times the distance between node N1 and node N2. However, these assumptions are merely illustrative and are not intended to limit the scope of the present invention. The distance between each node may not be the same, and in this case, the present invention may be equally applied.

When the client C1 connects to the specific node N2 and makes a streaming request, the cache server CS of the node N2 receives the streaming request of the client C1 (step S11). Hereinafter, the specific node N2 receiving the streaming request of the client C1 will be referred to as a 'streaming node' to distinguish it from other nodes.

The cache server CS of the streaming node N2 inquires the cache fragment storage information and the state information of each node that has received the streaming request (step S12). That is, the cache server CS queries the index server IS for cache fragment storage information and node state information and receives a response. The cache piece storage information includes the file name, reproduction priority, size, storage time, etc. of the cache pieces stored in each node. The node state information includes distances between nodes, remaining memory capacity of each node, transmission delay time between nodes, and the like.

The cache server CS of the streaming node N2 having received the cache fragment storage information and the node state information from the index server IS stores the location, reproduction priority, size, distance between each node, and remaining of each node. The optimal cache fragment acquisition method is determined in consideration of the memory capacity and the like comprehensively (step S13).

In detail, an optimal cache fragment acquisition method is described first. First, a node (hereinafter, referred to as a 'first node') in which a cache fragment having a first play rank (hereinafter referred to as 'first cache fragment') is stored is identified. do.

Subsequently, a node (hereinafter referred to as a 'second cache fragment') in which the cache fragment having a second play rank is referred to (hereinafter referred to as a 'second node') is identified, and the second cache fragment is obtained in some way. Determine if this is the most efficient. That is, it is determined whether it is better to receive the second cache fragment directly from the second node to the streaming node or to receive the second cache fragment via another node. If the first node is closer to the streaming node than the second node and there is room in the memory capacity of the first node, the second node goes to the first node while the first node is sending the first cache fragment to the streaming node. Sending the second cache fragment may be more efficient than sending the second cache fragment directly to the streaming node. In this case, after completing the transmission of the first cache fragment to the streaming node, the first node transmits the second cache fragment received from the second node to the streaming node.

In this way, the node storing each cache fragment determines whether the transmission scheme is more efficient between transmitting the cache fragment directly to the streaming node and transmitting the cache fragment via another node. The basic concept of this method is that when a streaming node is receiving a specific cache fragment, the other node's cache fragment is transmitted to the node closest to the streaming node and then transmitted to the streaming node. This allows you to distribute the load of streaming nodes to other nodes to optimize the performance of the entire network. On the other hand, the node selected as a waypoint before transmitting the cache fragment to the streaming node may be the node that is physically closest to the streaming node, or may be determined by comprehensively considering the transmission delay time and the remaining memory capacity.

The example of FIG. 4 is a case where the first node N2 is a streaming node. After the streaming node N2 determines the optimal cache piece acquisition method, the streaming node N2 requests a cache piece transmission to each of the nodes N1, N3 to N5 (steps S14, S15, S16, and S17). These cache fragment transfer requests may be performed simultaneously, sequentially, or sequentially at intervals of time.

The first node N1 receiving the cache fragment transmission request transmits the first cache fragment to the streaming node N2 (step S18), and the streaming node N2 receiving the first cache fragment receives the client requesting the streaming ( The first cache piece is streamed to C1) (step S19).

In addition, the third node N3 receiving the cache fragment transmission request transmits the third cache fragment to the streaming node N2 (step S20), and the streaming node N2 receiving the third cache fragment stores itself. The second cache fragment being streamed is streamed to the client C1 and then the third cache fragment is streamed.

Meanwhile, the fourth node N4 and the fifth node N5 that receive the cache fragment transmission request transmit the fourth cache fragment and the fifth cache fragment to the third node N3 adjacent to the streaming node N2, respectively. (Steps S21, S23). Upon receiving the fourth cache fragment and the fifth cache fragment, the third node N3 sequentially transmits the fourth cache fragment and the fifth cache fragment to the streaming node N2 when the transmission of the third cache fragment stored in the third node N3 is completed. (Step S22, S24).

The streaming node N2 receives the fourth cache fragment from the third node N3 and transmits it to the client C1, and receives the fifth cache fragment and transmits the fifth cache fragment to the client C1 (step S25).

The client C1, which has started to receive the streaming data from the streaming node N2, decodes the streaming data in the buffer B and plays the content by decoding it.

As described above, the present specification and drawings have been described with respect to preferred embodiments of the present invention, although specific terms are used, it is only used in a general sense to easily explain the technical contents of the present invention and to help the understanding of the present invention. It is not intended to limit the scope of the present invention. It is to be understood by those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

The present invention can be usefully used for a variety of multimedia streaming services that appear in a variety of forms, such as video content, online education, mass media content such as movies, broadcasts, music, recording and live broadcast, IPTV, including UCC.

1 is a view schematically showing the configuration of a multimedia streaming system according to the present invention.

2 is a diagram illustrating a configuration of a multimedia streaming system and a distributed content storage method according to an embodiment of the present invention.

3 is a diagram illustrating a detailed configuration of the cache server of FIG. 2.

4 is a flowchart illustrating a multimedia streaming method according to an embodiment of the present invention.

<Description of main parts of drawing>

CP: Content Delivery Server

N1, N2, N3, N4,... , Nn: node

C1, C2, C3, C4, C5,... , Cn: Client

MC: Multimedia Content

S1, S2, S3, S4, S5: Content Cache Piece

CS: Cache Server

IS: Index Server

B: buffer

11: streaming control

12: content cache fragment storage unit

13: cache fragment acquisition method determination unit

14: inter-node communication unit

Claims (8)

A content providing server providing multimedia content; A plurality of nodes distributed geographically between the content providing server and a plurality of clients; A cache server provided in each of the nodes, the cache server configured to store a cache fragment into which the multimedia content is divided; Including; The cache server of the streaming node that has received a streaming request from the client of the node, A cache fragment acquisition method determining unit configured to determine an optimal cache fragment acquisition method based on cache fragment storage information and node state information of the node; An inter-node communication unit for obtaining the cache pieces from another node according to the cache piece obtaining method; And a streaming control unit for transmitting the cache fragments obtained through the inter-node communication unit to the client in a streaming manner. The method according to claim 1, An index server provided in each of the nodes, storing the cache piece storage information and the node state information, and providing the cache piece storage information and the node state information to the cache server; Contents distributed storage multimedia streaming system further comprises. The method according to claim 1, The cache fragment storage information includes a file name, a reproduction priority, a size, and a storage time of the cache fragment stored in each node. The node state information includes a distance between nodes, a remaining memory capacity of each node, and a transmission delay time between nodes. Content distributed storage multimedia streaming system comprising a. The method according to claim 1, The cache fragment acquisition method is a content distribution storage multimedia streaming system characterized in that the cache fragment transmission to the streaming node via the node closest to the streaming node when the reproduction priority is not the fastest cache fragment. The client is connected to a specific node among a plurality of nodes which are distributed and distributed locally among a plurality of clients and a content providing server that provides multimedia contents, and each cache fragment in which the multimedia contents are divided is stored in a cache server. Receiving a streaming request from the client at the specific node, if requested; Determining, by the cache server of the specific node, an optimal cache fragment acquisition method based on cache fragment storage information and node state information of the node; Obtaining, by the cache server of the specific node, the cache fragments from another node according to the cache fragment obtaining scheme, and streaming the cache fragments to the client; Content distributed storage multimedia streaming method comprising a. The method according to claim 5, Querying, by the cache server of the particular node, an index server with the cache fragment storage information and the node state information; Contents distributed storage multimedia streaming method further comprising. The method according to claim 5, The cache fragment storage information includes a file name, a reproduction priority, a size, and a storage time of the cache fragment stored in each node. The node state information includes a distance between nodes, a remaining memory capacity of each node, and a transmission delay time between nodes. Content distributed storage multimedia streaming method comprising the. The method according to claim 5, The cache fragment acquisition method is a content distribution storage multimedia streaming method characterized in that the cache fragment transmission to the streaming node via the node closest to the streaming node when the reproduction priority is not the fastest cache fragment.

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