The Study On Efficient Method Of Streaming Media Proxy Caching Based On Patching Algorithm

Since the concept of streaming media has been introduced in recentyears,it has experienced a dramatic growth. Streaming media has turn froma novel technology into one of the mainstream manners in which peopleexperience the Internet service such as VOD, network TV, distanceeducation ,vedio conference and network amusement. Users can play backsome parts of a streaming media, which is being downloaded. However,due to the high bandwidth requirements and the long-live nature of video,server and network bandwidths are proved to be major limiting resource inthe widespread usage of steaming media over the internet. The conflictsbetween limited internet's resources and wide application of streaming mediaare more serious, So it become a popular question in the streaming mediaarea that how to improve the delivery quality.In order to solve the problem, The researchers have put forward lots oftechniques to improve the delivery quality of the streaming media. Such asthe prefix catching, dynamic catching in the proxy caching, the Patching andBatch Patching in the delivery are the most efficient techniques.This paper introduce the streaming media proxy caching and thepatching algorithm firstly, then we propose an efficient method of streamingmedia proxy caching based on patching algorithm. Lastly ,we design andimplement this method.The.proxy caching of streaming media is brought forward because thebottleneck resource is in short supply,The bottleneck often exit on the remoteserver and the backbone network. For example, the most providers, thejam-up because of the lacking of backbone network's bandwidth.Thestreaming media proxy server can resolve the above questions partially. Theproxy cache can decrease the network bandwidth, depress the network flux,reduce the network delay and alleviate the pressure of the server. At the sametime, it can promised the quality of server.Batching scheduling technology divide the time that the proxy serve toclient into lots of interval .In order to use the multicast priority and save thenetwork bindwidth,the proxy will give multicast delivery to the clients whoreach the proxy at the interval and will have only one regular channel at eachinternal .In the real system designing process, we want to fulfill maximumservice capability using the limited resourse. But the batching scheduling hasthe defect that it will have sometime start-up delay for some clients becauseit have lots of clients sharing a multicast streaming . So someone proposethe patching algorithm base on the batching schduling. The client will join inthe regular channel if he miss some media data, then he can get the data fromthe patching channel. The method will remove the start-up delay .We can find that the streaming media proxy caching and patchingalgorithm are two main methods to improve the delivery quality by theanalysis and research. So we apply the patching method in the streamingmedia server to streaming meidia proxy caching, and propose an efficientmethod of streaming media proxy caching based on patching algorithm. Ourmethod is as fellows:we can give a regular streaming start-up period ,theproxy server can get streaming media data from the original server by unicastin this period,the time of the proxy serving to the client can divide into lots ofinterval, the client can join into the regular channel at the batching interval,when the proxy transmit the data for the one interval clients, it will also cachethe dada for the latter client. When the latter client miss some data, the proxycan compensate the missing data using the caching data. In a regularstreaming period ,we can only start-up one regular channel ,we can meet lotsof batching clients. The method combines the proxy caching with patchingalgorithm, and we needn't start the patching channel between the orginalserver and the proxy server. From the analysis, we can find the method canreduce significantly the consumption of aggregate bandwidth on backbonenetwork bindwidth.At last, based on the above method we design and implement astreaming media proxy caching program,divide the trasmitting media into thesame size block and cache them in the proxy .In this program ,we create thecaching mapping node to manage the data in the disk.When a new client askfor the data,the proxy caching judges the client's state.Then the proxy cachingtransmits the regular data and the patching data by multicast at the batchinginterval.We make use of RTSP protocol as the stream service protocol. RTSPis an application-level protocol for control over the delivery of data withreal-time properties. It provides VRC functions, such as play, pause, playbacketc. we can setup RTSP proxy of the client's player to carry out the datadelivery. The transition of stream data is not confined on network protocol, itcan use either RTP (UDP)/RTCP (UDP);lastly ,the data can transmit to theclient from the remote server by the proxy cachingWe believe that the method proposed in this paper have some referencemerit.