CN100547994C - The caching method that is used for the files in stream media of mobile flow medium acting server - Google Patents

Abstract

A kind of caching method that is used for the media file of mobile flow medium acting server, step is as follows: (1) sets the institutional framework of files in stream media main part; (2) computational methods of the popularity of the section of setting files in stream media main part; (3) when each user asks to arrive, according to the buffer memory acceptance method to relevant files in stream media whether buffer memory judge and handle; (4) carrying out buffer memory replaces: in acting on behalf of server the duration of certain files in stream media of buffer memory less than the accessed average duration of this files in stream media, or certain media object M is when for the first time accessed, discharge spatial cache by acting server according to buffer replacing method, be used for section that this files in stream media next one is not buffered as yet or for the first time accessed media object M carry out buffer memory and replace.This method can improve the user terminal response speed of streaming media service, saves the network bandwidth, and the variation of proxy server caches size is had well adaptability in real time.

Description

The caching method that is used for the files in stream media of mobile flow medium acting server

Technical field

The present invention relates to a kind of new technology of mobile flow medium, exactly, relate to a kind of caching method that is used for the files in stream media of mobile flow medium acting server, belong to the mobile communication value-added service technical field.

Background technology

Streaming media service is a kind of multimedia application that grows up from Internet: adopt stream (Streaming) mode at multimedia files such as transmission over networks audio frequency, video and/or animations.The main feature of streaming media transmission technique is the form transmitting multimedia data with stream, continuous image and acoustic information after handling, are put on the webserver in overcompression, client does not need to download entire media file before broadcast, but when the information that has received in buffer area plays, the multimedia file of remainder will download to client from server continuously, promptly realize " download on the limit, and play on the limit ".So just avoided the user when watching or listening to Media Stream, must spend the process that a period of time intactly downloads to file client earlier, not only saved service time, more can bring the professional sensory experience of " playing in real time " to the user.These characteristics make stream media technology to provide the high-efficiency information service for the consumer to greatest extent in limited spatial and temporal scope.

The application of stream media technology on mobile radio communication and terminal produced mobile flow medium service, and it mainly is the mobile radio communication that utilizes present 2.5G or 3G, and the streaming media service of audio frequency, video is provided for mobile phone terminal.The content of mobile flow medium service comprises various ways such as news information, video display, MTV, physical culture, education, industry and special application.

The technical characterstic of Streaming Media has determined its broad prospect of application in the mobile network.At first, stream media technology effectively reduces the requirement to transmission bandwidth and shake, makes to realize that at the wireless transmission environment real-time media play service becomes possibility.Size of mobile terminals is little, the requirement of low energy consumption has determined finite storage space, and media file need not preserved in terminal, has avoided the requirement to memory space.Secondly, effectively copyright protection can be guaranteed the commercial pattern that mobile flow medium is used.Therefore,, the mobile flow medium technology is introduced mobile value-added service, become one of focus of mobile service research in the present global range, just causing more and more technical staff's attention and exploitation along with the progressively maturation of 3G (Third Generation) Moblie technology.Standardization bodies such as 3GPP, 3GPP2 have carried out the application study work of mobile flow medium for a long time at present, and have formulated corresponding standard.

Referring to Fig. 1, mobile flow medium server and mobile flow medium acting server provide two crucial platforms of mobile flow medium service, also are the nucleus equipments in the mobile flow medium network system.Wherein the mobile flow medium server is in the IP kernel heart net usually, is used to deposit files in stream media, and the response user asks and sends stream medium data to portable terminal.The mobile flow medium acting server then is positioned at mobile network's edge, near the user.In Wireless Application Environment, wireless channel is very unstable, and the storage resources of 3G client is limited, and the effect of mobile flow medium acting server seems and be even more important, the focus during wherein the acting server method of how media data being carried out buffer memory is studied especially.

Summary of the invention

In view of this, the purpose of this invention is to provide a kind of caching method that is used for the media file of mobile flow medium acting server,, save the network bandwidth so that can improve the user terminal response speed of streaming media service.

In order to achieve the above object, the invention provides a kind of caching method that is used for the files in stream media of mobile flow medium acting server, it is characterized in that: described method comprises following operating procedure:

(1) institutional framework of setting files in stream media main part;

(2) computing formula of the popularity of the section of setting files in stream media main part is;

In the formula, the distance function of the numbering s of D (s) section of being, the numerical value of this distance function D (s) is nonnegative real number, and s is big more, the absolute value of D (s) is big more, gets log (s);

(3) when each user asks to arrive, relevant files in stream media is carried out the whether judgement and the processing of buffer memory according to buffer memory admission processing method;

(4) carrying out buffer memory replace to handle: in acting on behalf of server the duration of certain files in stream media of buffer memory less than the accessed average access duration L of this files in stream media _Avg, or certain files in stream media discharges spatial cache by acting server according to the buffer memory replacing processing method when for the first time accessed, be used for to the section that is not buffered as yet of this files in stream media or for the first time accessed files in stream media carry out buffer memory and replace; Promptly when certain files in stream media M is for the first time accessed, enough spatial caches are arranged, the then direct initial data cached buffer memory that carries out to this files in stream media M as if acting server; Otherwise, the popularity value of the back segment that acting server must calculate earlier that each files in stream media is buffered, and in current files in stream media of not asked, select the files in stream media Q of popularity value minimum, and the occupied spatial cache of back segment that discharges that this files in stream media Q is buffered by the user; If the capacity of spatial cache not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and, discharge the occupied spatial cache of this section in the current media object section of selecting popularity value minimum in not by the files in stream media of client requests; Carry out according to the aforesaid operations circulation, up to there being enough spatial caches to be released;

When the once accessed in the past mistake of accessed files in stream media M,, then directly first section that is not buffered of this files in stream media M is carried out buffer memory if acting server has enough spatial caches; Otherwise, the popularity of the back segment that the popularity of first section that is not buffered that acting server calculates this files in stream media M and other each files in stream media are buffered, and at the files in stream media Q of the popularity value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of files in stream media Q is not more than the popularity numerical value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that files in stream media Q is buffered; If at this moment the capacity of spatial cache is enough big, then acting server carries out buffer memory to first section that is not buffered of files in stream media M; If the capacity of spatial cache is not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and at the files in stream media P of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity value of the back segment that is buffered of files in stream media P is not more than the popularity value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that files in stream media P is buffered; Carry out according to aforesaid operations circulation, up to there being enough spatial caches to be released, first section that is not buffered of the accessed files in stream media M of proxy server caches then; If there are not enough spatial caches to be released, then acting server is abandoned first section that is not buffered of the accessed files in stream media M of buffer memory; Upgrade the access log of this files in stream media M, finish whole operations of this flow process.

Be used for to the section that is not buffered as yet of files in stream media M or for the first time accessed files in stream media M carry out buffer memory and replace.。

Described method further comprises following operating procedure: the prefix with all files in stream media in the media server is cached in the acting server in advance, the prefix size that is buffered depends on the network condition between media server and each acting server, so that when client requests, acting server can send the prefix of files in stream media immediately to the client, reduce the playout-delay of files in stream media; Be that described method is not carried out caching process to the prefix of files in stream media.

Described step (1) further comprises following content of operation:

(11) with removing the media data of the main part of prefix in the files in stream media, from head part, be divided into the data block of identical size according to the time span of setting, a last remaining data block can make an exception;

(12) use natural number and each data block is numbered one by one according to the time order and function order;

(13) based on data block, the media data of main part is begun to be divided into the section that size increases progressively one by one from the head, and with natural number sequentially for each segment number: the 1st section comprises 1 data block, the 2nd section comprises two data blocks, the 3rd section comprises 3 data blocks, and the like, the n section comprises n data block, and n is a natural number; But except remaining last section.

The computing formula of the popularity of certain files in stream media of calculating in the computing formula of the popularity of the section of described files in stream media main part is:

In the formula, T _FirstBe for the first time accessed duration of this files in stream media, T _LastBe the last accessed duration of this files in stream media, T _SumBe the accessed total duration of this files in stream media, N is the accessed number of times of this files in stream media, T _cThe expression current time, H is the data volume that this files in stream media is buffered in the current acting server.

Buffer memory admission processing method in the described step (3) is to want acting server to carry out following content of operation:

(31) if certain accessed files in stream media M does not have access log, promptly it is for the first time accessed, and acting server is known the time span T of this files in stream media M, then jumps to step (41), adopts the buffer memory replacing processing method that it is carried out caching process;

(32) if this accessed files in stream media M has access log, i.e. once accessed mistake before its, and access log indicate this files in stream media M by total caching in acting server, at this moment as long as upgrade the access log of this files in stream media M; Finishing this flow process all operates;

(33) if accessed files in stream media M has access log, i.e. once accessed mistake before its, but access log indicates this files in stream media M not by total caching; Then add up the average access duration L of this files in stream media M earlier _AvgIf, this average access duration L _AvgThe time span that in acting server, has been buffered greater than this files in stream media, illustrate then in the acting server that the data duration of this files in stream media M of buffer memory can not satisfy the most of access request of user to this files in stream media M, therefore the section that this files in stream media M next one is not buffered is as yet admitted in the acting server decision, and operation is handled in the replacement of the buffer memory of redirect execution subsequent step (42).

The average access duration L that described certain files in stream media is accessed _AvgBe the accessed total duration T of this files in stream media _SumDivided by the merchant of the accessed times N of this files in stream media, i.e. L _Avg=T _Sum/ N.

Each caching process of carrying out in acting server is that unit carries out with the section.

Buffer memory replacing processing method in the described step (4) is to want acting server to carry out following content of operation:

(41) when certain files in stream media M is for the first time accessed, if enough spatial caches are arranged in the acting server, then directly to the initial data cached buffer memory that carries out of this files in stream media M, initial data cached size is

Data, L wherein _sBe the duration that is numbered the section of s, x is satisfied $\underset{s=1}{\overset{x}{\mathrm{\Σ}}}{L}_s\≥W$ Minimum value, W represents the buffer window size, the initial value of W is T/I, T is total duration of this files in stream media M, ordinal number I is a natural number, elects 2 usually as; Otherwise, the popularity value of the back segment that acting server must calculate earlier that each files in stream media is buffered, and at the current files in stream media Q that selects popularity value minimum in not by the files in stream media of client requests, and discharge the occupied spatial cache of back segment that this files in stream media Q is buffered, if at this moment the free buffer space of acting server enough is used for the initially data cached of cache flow media file M, then acting server is to the initial data cached buffer memory that carries out of files in stream media M; If the capacity of spatial cache not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and, discharge the occupied spatial cache of this section in the current media object section of selecting popularity value minimum in not by the files in stream media of client requests; So repeat, up to there being enough spatial caches to be released, be used for the initially data cached of this files in stream media of buffer memory M, and set up the access log of this files in stream media M simultaneously, the accessed history of this files in stream media of opening entry M, and according to accessed situation real-time update is carried out in this daily record afterwards; If there are not enough spatial caches to be released, then acting server is abandoned the initially data cached of this files in stream media of buffer memory M; Finish whole operations of this flow process;

(42),, then directly first section that is not buffered of this files in stream media M is carried out buffer memory if enough spatial caches are arranged in the acting server when the once accessed in the past mistake of accessed files in stream media M; Otherwise, the popularity of the back segment that acting server calculates that the popularity of first section that is not buffered of files in stream media M and other each files in stream media are buffered, and at the files in stream media Q of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of files in stream media Q is not more than the popularity numerical value of first section that is not buffered of files in stream media M, then discharge the shared spatial cache of back segment that this files in stream media Q is buffered, if at this moment the capacity of spatial cache is enough big, then acting server carries out buffer memory to first section that is not buffered of files in stream media M; If the capacity of spatial cache is not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and at the files in stream media P of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of this files in stream media P is not more than the popularity numerical value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that this files in stream media P is buffered; So repeat, up to there being enough spatial caches to be released, first section that is not buffered of the accessed files in stream media M of proxy server caches then; If there are not enough spatial caches to be released, then acting server is abandoned first section that is not buffered of the accessed files in stream media M of buffer memory; Upgrade the access log of this files in stream media M, finish whole operations of this flow process.

Described step (41) further comprises following content of operation: acting server upgrades the size of the buffer window W of files in stream media: if behind the certain interval of time, have the user to ask this files in stream media M again, then acting server is added up the accessed average duration L of this files in stream media M _AvgIf, L at this moment _Avg＜T/2 then makes W=2 * L _AvgIf L _Avg＞T/2 then makes W=L _Avg

Described step (42) further comprises the content of operation of following selective execution: after acting server completes successfully the buffer memory of the section that first of this files in stream media M is not buffered, if the length that this files in stream media M has been buffered is still less than the buffer window W of this files in stream media M of this moment, then acting server continues the section that the next one to this files in stream media M is not buffered and carries out caching process; So repeat, be not less than up to the length that this files in stream media M has been buffered till the buffer window W of this files in stream media M at this moment, perhaps till not having spatial cache to be released.

The mobile flow medium technology is the product that network audio-video technology and mobile communication technology develop into certain phase, it is to merge the new technology that is produced after a lot of network technologies, relate to collection, compression, the storage of stream medium data, wireless communication, and multinomial technology such as portable terminal.The present invention then is a kind of caching method of files in stream media of the Streaming Media acting server that is used for mobile radio communication, the major advantage and the effect of this method are: the variation for the proxy server caches size has well conformability in real time, can access the bigger average that is buffered the Streaming Media object, has higher rate and byte hit, the less initial request rate that is delayed, lower startup time-delay.

Description of drawings

Fig. 1 is that mobile flow medium service distributing network system architecture is formed schematic diagram.

Fig. 2 is the caching method flow chart of the present invention's media file of being used for the mobile flow medium acting server.

Fig. 3 is a Streaming Media obj ect file main part institutional framework among the present invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing.

The present invention is a kind of caching method that is used for the files in stream media of mobile flow medium acting server, files in stream media is divided into prefix and main body two parts, the present invention does not carry out caching process to the prefix of files in stream media, promptly the prefix of all files in stream media in the media server need be cached in the acting server in advance, the prefix size that is buffered depends on the network condition between media server and each acting server, so that when client requests, acting server can send the prefix of media file immediately to the client, reduce the playout-delay of media file.

Referring to Fig. 2, introduce each operating procedure of the inventive method:

(1) institutional framework of setting files in stream media main part: will remove the main part media data of prefix in the files in stream media, start anew, be divided into the data block (except last data block of main part) of equal size according to the time span of setting, and be that each data block is numbered according to the time order and function order since 1; Based on data block, main part is started anew the section of being divided into simultaneously, and be numbered for section in proper order since 1: section 1 comprises 1 data block, and section 2 comprises two data blocks, and section 3 comprises 3 data blocks, ..., and the like, but except last section of main part.

(2) computational methods of the popularity of the section of setting files in stream media main part: the computing formula of the popularity of the section of files in stream media main part is;

In the formula, the numbering of the variable s section of being, D (s) is the distance function of s, and the numerical value of this distance function D (s) is nonnegative real number, and s is big more, and the absolute value of D (s) is big more, so common desirable log (s); The computing formula of the popularity of certain files in stream media can be selected following formula for use in the above-mentioned formula:

In the formula, T _FirstBe for the first time accessed duration of this files in stream media, T _LastBe the last accessed duration of this files in stream media, T _SumBe the accessed total duration of this files in stream media, N is the accessed number of times of this files in stream media, T _cThe expression current time, H is the data volume that this files in stream media is buffered in the current acting server; The calculating of files in stream media popularity numerical value also can select for use known other of industry circle to calculate the computing formula of the popularity of certain files in stream media.

(3) when each user asks to arrive, relevant files in stream media is carried out the whether judgement and the processing of buffer memory according to buffer memory admission processing method; The buffer memory admission processing method of acting server will be carried out following operation:

(31) if certain accessed media object M does not have access log, promptly it is for the first time accessed, and acting server is known the time span T of this media object M, then jumps to step (41), adopts the buffer memory replacing processing method that it is carried out caching process; And set up the access log of this media object M simultaneously, the accessed history of this media object of opening entry M, and according to accessed situation real-time update is constantly carried out in this daily record afterwards.

(32) if this accessed media object M has access log, it is once accessed mistake before it, and access log indicate this media object M by total caching in acting server, at this moment need not carry out the buffer memory admission judgment, as long as upgrade the access log of this media object M; Finishing this flow process all operates.

(33) if accessed media object M has access log, i.e. once accessed mistake before its, but access log indicates this media object M not by total caching; Then add up the average access duration L of this media object M earlier _AvgIf, this average access duration L _AvgThe time span that in acting server, has been buffered greater than this media object, illustrate then in the acting server that the data duration of this media object M of buffer memory can not satisfy the most of access request of user to this media object M, therefore media object M hereto, acting server need be considered the section of admitting this media object M next one also not to be buffered, can the buffer memory that be redirect execution subsequent step (42) be replaced the processing operation, finally be carried out buffer memory replacement processing by acting server to judge this new section.

(4) carrying out buffer memory replace to handle: the cost of using acting server be need be on acting server copy data, and in the acting server in case when not having enough available spatial cache, will discharge spatial cache by the application cache replacing processing method, so select suitable buffer replacing method just quite important.The treatment principle of buffer replacing method of the present invention is: in acting on behalf of server the duration of certain files in stream media of buffer memory less than the accessed average duration L of this files in stream media _Avg, or certain media object M is when for the first time accessed, acting server will discharge spatial cache according to buffer replacing method, be used for section that this files in stream media next one is not buffered as yet or for the first time accessed media object M carry out buffer memory and replace.The concrete operations content is:

(41) when certain files in stream media M is for the first time accessed, if enough spatial caches are arranged in the acting server, then directly to the initial data cached buffer memory that carries out of this files in stream media M, initial data cached size is

Data, L wherein _sBe the duration that is numbered the section of s, x is satisfied $\underset{s=1}{\overset{x}{\mathrm{\Σ}}}{L}_s\≥W$ Minimum value, W represents the buffer window size, the initial value of W is T/I, T is total duration of this files in stream media M, ordinal number I is a natural number, elects 2 usually as; Otherwise, the popularity value of the back segment that acting server must calculate earlier that each files in stream media is buffered, and at the current files in stream media Q that selects popularity value minimum in not by the files in stream media of client requests, and discharge the occupied spatial cache of back segment that this files in stream media Q is buffered, if at this moment the free buffer space of acting server enough is used for the initially data cached of cache flow media file M, then acting server is to the initial data cached buffer memory that carries out of files in stream media M; If the capacity of spatial cache not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and, discharge the occupied spatial cache of this section in the current media object section of selecting popularity value minimum in not by the files in stream media of client requests; So repeat, up to there being enough spatial caches to be released, be used for the initially data cached of this files in stream media of buffer memory M, and set up the access log of this files in stream media M simultaneously, the accessed history of this files in stream media of opening entry M, and according to accessed situation real-time update is carried out in this daily record afterwards; If there are not enough spatial caches to be released, then acting server is abandoned the initially data cached of this files in stream media of buffer memory M; Finishing this flow process all operates.

This step (41) also comprises following content of operation: acting server upgrades the size of the buffer window W of files in stream media: if behind the certain interval of time, have the user to ask this files in stream media M again, then acting server is added up the accessed average duration L of this files in stream media M _AvgIf, L at this moment _Avg＜T/2 then makes W=2 * L _AvgIf L _Avg＞T/2 then makes W=L _Avg

(42),, then directly first section that is not buffered of this files in stream media M is carried out buffer memory if enough spatial caches are arranged in the acting server when the once accessed in the past mistake of accessed files in stream media M; Otherwise, the popularity value of the back segment that acting server calculates that the popularity value of first section that is not buffered of files in stream media M and other each files in stream media are buffered, and at the files in stream media Q of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of files in stream media Q is not more than the popularity numerical value of first section that is not buffered of files in stream media M, then discharge the shared spatial cache of back segment that this media object Q is buffered, if at this moment the capacity of spatial cache is enough big, then acting server carries out buffer memory to first section that is not buffered of media object M; If the capacity of spatial cache not enough after discharging, then acting server recomputates the popularity value of the new back segment that is buffered of media object Q, and at the current files in stream media P that selects popularity value minimum in not by the media object of client requests, if the popularity numerical value of the back segment that is buffered of this files in stream media P is not more than the popularity numerical value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that this files in stream media P is buffered; So repeat, up to there being enough spatial caches to be released, first section that is not buffered of the accessed files in stream media M of proxy server caches; If there are not enough spatial caches to be released, then acting server is abandoned first section that is not buffered of the accessed files in stream media M of buffer memory; Upgrade the access log of this files in stream media M, finish whole operations of this flow process.

This step (42) also comprises following available content of operation: after acting server completes successfully the buffer memory of the section that first of this files in stream media M is not buffered, if the length that this files in stream media M has been buffered is still less than the buffer window W of this files in stream media M of this moment, then acting server continues the section that the next one to this files in stream media M is not buffered and carries out caching process; So repeat, be not less than up to the length that this files in stream media M has been buffered till the buffer window W of this files in stream media M at this moment, perhaps till not having spatial cache to be released.

Claims (10)

1, a kind of caching method that is used for the files in stream media of mobile flow medium acting server, it is characterized in that: described method comprises following operating procedure:

(1) institutional framework of setting files in stream media main part;

(2) computing formula of the popularity of the section of setting files in stream media main part is:

In the formula, the distance function of the numbering s of D (s) section of being, the numerical value of this distance function D (s) is nonnegative real number, and s is big more, the absolute value of D (s) is big more, gets log (s);

(3) when each user asks to arrive, relevant files in stream media is carried out the whether judgement and the processing of buffer memory according to buffer memory admission processing method;

(4) carrying out buffer memory replace to handle: in acting on behalf of server the duration of certain files in stream media of buffer memory less than the accessed average access duration L of this files in stream media _Avg, or certain files in stream media discharges spatial cache by acting server according to the buffer memory replacing processing method when for the first time accessed, be used for to the section that is not buffered as yet of this files in stream media or for the first time accessed files in stream media carry out buffer memory and replace; Promptly when certain files in stream media M is for the first time accessed, enough spatial caches are arranged, the then direct initial data cached buffer memory that carries out to this files in stream media M as if acting server; Otherwise, the popularity value of the back segment that acting server must calculate earlier that each files in stream media is buffered, and in current files in stream media of not asked, select the files in stream media Q of popularity value minimum, and the occupied spatial cache of back segment that discharges that this files in stream media Q is buffered by the user; If the capacity of spatial cache not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and, discharge the occupied spatial cache of this section in the current media object section of selecting popularity value minimum in not by the files in stream media of client requests; Carry out according to the aforesaid operations circulation, up to there being enough spatial caches to be released;

When the once accessed in the past mistake of accessed files in stream media M,, then directly first section that is not buffered of this files in stream media M is carried out buffer memory if acting server has enough spatial caches; Otherwise, the popularity of the back segment that the popularity of first section that is not buffered that acting server calculates this files in stream media M and other each files in stream media are buffered, and at the files in stream media Q of the popularity value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of files in stream media Q is not more than the popularity numerical value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that files in stream media Q is buffered; If at this moment the capacity of spatial cache is enough big, then acting server carries out buffer memory to first section that is not buffered of files in stream media M; If the capacity of spatial cache is not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and at the files in stream media P of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity value of the back segment that is buffered of files in stream media P is not more than the popularity value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that files in stream media P is buffered; Carry out according to aforesaid operations circulation, up to there being enough spatial caches to be released, first section that is not buffered of the accessed files in stream media M of proxy server caches then; If there are not enough spatial caches to be released, then acting server is abandoned first section that is not buffered of the accessed files in stream media M of buffer memory; Upgrade the access log of this files in stream media M, finish whole operations of this flow process.

2, the caching method of files in stream media according to claim 1, it is characterized in that: described method further comprises following operating procedure: the prefix with all files in stream media in the media server is cached in the acting server in advance, the prefix size that is buffered depends on the network condition between media server and each acting server, so that when client requests, acting server can send the prefix of files in stream media immediately to the client, reduce the playout-delay of files in stream media; Be that described method is not carried out caching process to the prefix of files in stream media.

3, the caching method of files in stream media according to claim 1 is characterized in that: described step (1) further comprises following content of operation:

(11) with removing the media data of the main part of prefix in the files in stream media, from head part, be divided into the data block of identical size according to the time span of setting, a last remaining data block can make an exception;

(12) use natural number and each data block is numbered one by one according to the time order and function order;

(13) based on data block, the media data of main part is begun to be divided into the section that size increases progressively one by one from the head, and with natural number sequentially for each segment number: the 1st section comprises 1 data block, the 2nd section comprises two data blocks, the 3rd section comprises 3 data blocks, and the like, the n section comprises n data block, and n is a natural number; But except remaining last section.

4, the caching method of files in stream media according to claim 1 is characterized in that: the computing formula of the popularity of certain files in stream media of calculating in the computing formula of the popularity of the section of described files in stream media main part is:

In the formula, T _FirstBe for the first time accessed duration of this files in stream media, T _LastBe the last accessed duration of this files in stream media, T _SumBe the accessed total duration of this files in stream media, N is the accessed number of times of this files in stream media, T _cThe expression current time, H is the data volume that this files in stream media is buffered in the current acting server.

5, the caching method of files in stream media according to claim 1 is characterized in that: the buffer memory admission processing method in the described step (3) is to want acting server to carry out following content of operation:

(31) if certain accessed files in stream media M does not have access log, be that it is for the first time accessed, acting server is known the time span T of this files in stream media M, and then subsequent step (4) is carried out in redirect, adopts the buffer memory replacing processing method that it is carried out caching process;

(32) if this accessed files in stream media M has access log, i.e. once accessed mistake before its, and access log indicate this files in stream media M by total caching in acting server, at this moment as long as upgrade the access log of this files in stream media M; Finishing this flow process all operates;

(33) if accessed files in stream media M has access log, i.e. once accessed mistake before its, but access log indicates this files in stream media M not by total caching; Then add up the average access duration L of this files in stream media M earlier _AvgIf, this average access duration L _AvgThe time span that in acting server, has been buffered greater than this files in stream media, illustrate then in the acting server that the data duration of this files in stream media M of buffer memory can not satisfy the most of access request of user to this files in stream media M, therefore the section that this files in stream media M next one is not buffered is as yet admitted in the acting server decision, and operation is handled in the replacement of the buffer memory of redirect execution subsequent step (4).

6, the caching method of files in stream media according to claim 1 or 5 is characterized in that: the average access duration L that described certain files in stream media is accessed _AvgBe the accessed total duration T of this files in stream media _SumDivided by the merchant of the accessed times N of this files in stream media, i.e. L _Avg=T _Sum/ N.

7, the caching method of files in stream media according to claim 1 is characterized in that: each caching process of carrying out in acting server is that unit carries out with the section.

8, the caching method of files in stream media according to claim 1 is characterized in that: the buffer memory replacing processing method in the described step (4) is to want acting server to carry out following content of operation:

(41) when certain files in stream media M is for the first time accessed, if enough spatial caches are arranged in the acting server, then directly to the initial data cached buffer memory that carries out of this files in stream media M, initial data cached size is

Data, L wherein _sBe the duration that is numbered the section of s, x is satisfied $\underset{s=1}{\overset{x}{\mathrm{\Σ}}}{L}_s\≥W$ Minimum value, W represents the buffer window size, the initial value of W is T/I, T is total duration of this files in stream media M, ordinal number I is a natural number; Otherwise, the popularity value of the back segment that acting server must calculate earlier that each files in stream media is buffered, and at the current files in stream media Q that selects popularity value minimum in not by the files in stream media of client requests, and discharge the occupied spatial cache of back segment that this files in stream media Q is buffered, if at this moment the free buffer space of acting server enough is used for the initially data cached of cache flow media file M, then acting server is to the initial data cached buffer memory that carries out of files in stream media M; If the capacity of spatial cache not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and, discharge the occupied spatial cache of this section in the current media object section of selecting popularity value minimum in not by the files in stream media of client requests; So repeat, up to there being enough spatial caches to be released, be used for the initially data cached of this files in stream media of buffer memory M, and set up the access log of this files in stream media M simultaneously, the accessed history of this files in stream media of opening entry M, and according to accessed situation real-time update is carried out in this daily record afterwards; If there are not enough spatial caches to be released, then acting server is abandoned the initially data cached of this files in stream media of buffer memory M; Finish whole operations of this flow process;

(42),, then directly first section that is not buffered of this files in stream media M is carried out buffer memory if enough spatial caches are arranged in the acting server when the once accessed in the past mistake of accessed files in stream media M; Otherwise, the popularity of the back segment that acting server calculates that the popularity of first section that is not buffered of files in stream media M and other each files in stream media are buffered, and at the files in stream media Q of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of files in stream media Q is not more than the popularity numerical value of first section that is not buffered of files in stream media M, then discharge the shared spatial cache of back segment that this files in stream media Q is buffered, if at this moment the capacity of spatial cache is enough big, then acting server carries out buffer memory to first section that is not buffered of files in stream media M; If the capacity of spatial cache is not enough, then acting server recomputates the popularity value of the new back segment that is buffered of files in stream media Q, and at the files in stream media P of the popularity numerical value minimum of the current back segment of selecting in not by the files in stream media of client requests to be buffered, if the popularity numerical value of the back segment that is buffered of this files in stream media P is not more than the popularity numerical value of first section that is not buffered of files in stream media M, the shared spatial cache of back segment that discharges then that this files in stream media P is buffered; So repeat, up to there being enough spatial caches to be released, first section that is not buffered of the accessed files in stream media M of proxy server caches then; If there are not enough spatial caches to be released, then acting server is abandoned first section that is not buffered of the accessed files in stream media M of buffer memory; Upgrade the access log of this files in stream media M, finish whole operations of this flow process.

9, the caching method of files in stream media according to claim 8, it is characterized in that: described step (41) further comprises following content of operation: acting server upgrades the size of the buffer window W of files in stream media: if behind the certain interval of time, have the user to ask this files in stream media M again, then acting server is added up the accessed average duration L of this files in stream media M _AvgIf, L at this moment _Avg＜T/2 then makes W=2 * L _AvgIf L _Avg＞T/2 then makes W=L _Avg

10, the caching method of files in stream media according to claim 8, it is characterized in that: described step (42) further comprises the content of operation of following selective execution: after acting server completes successfully the buffer memory of the section that first of this files in stream media M is not buffered, if the length that this files in stream media M has been buffered is still less than the buffer window W of this files in stream media M of this moment, then acting server continues the section that the next one to this files in stream media M is not buffered and carries out caching process; So repeat, be not less than up to the length that this files in stream media M has been buffered till the buffer window W of this files in stream media M at this moment, perhaps till not having spatial cache to be released.