CN101626400B - Compensation method of P2P music on-demand system - Google Patents
Compensation method of P2P music on-demand system Download PDFInfo
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- CN101626400B CN101626400B CN2009100635780A CN200910063578A CN101626400B CN 101626400 B CN101626400 B CN 101626400B CN 2009100635780 A CN2009100635780 A CN 2009100635780A CN 200910063578 A CN200910063578 A CN 200910063578A CN 101626400 B CN101626400 B CN 101626400B
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Abstract
The invention belongs to the technical field of P2P network streaming media, in particular relating to a compensation method of a P2P music on-demand system. The music on-demand compensation mechanism provided in the invention comprises the following steps: compensation is started, and compensation is performed aiming at the condition that music data file playing can not be immediately started; compensation is performed during the playing, and the compensation is performed aiming at the condition that the music playing is started. By adopting the technical scheme in the invention, the playing starting time delay of the music can be reduced, the music playing continuity can be ensured, and the expansibility of the system can be improved, therefore, the waiting time of the user can be shortened, and the user experience can be improved.
Description
Technical field
The present invention relates to P2P (Peer-to-Peer, equity) network flow-medium technical field, more specifically, relate to a kind of compensation method of P2P music demand system.
Background technology
It is more and more universal that Music on Demand is used, but high quality of music has relatively high expectations to bandwidth resources, and traditional C/S pattern can not satisfy application demand, and server is easy to become system bottleneck; The IP multicast alleviates server and offered load through the mode of the distributed concurrent transmission of audio stream of intermediate node (peer), but owing to disposing reason, is difficult in Internet and goes up extensively enforcement; CDN adopts the mode of proxy caching node will serve with content and pushes network " edge " to, but disposes costliness and existence and the similar bottleneck of C/S model; The P2P Streaming Media provides service through the resource of utilizing ordinary node for other node, under the prerequisite that does not change the existing network configuration, has good cost performance, is a kind of audio distribution method with wide application prospect.
In the music demand system based on the P2P network, the music source server is a requisite part, and it provides the distribution of music source data.Each node not only can obtain data (major part comes from this) from other node, also can obtain data from the music source server in a certain way, to guarantee small-startup time delay and to play continuity.Be called " compensation " to the mode of obtaining data from the music source server.
In the existing P2P music demand system; Mainly take some simple modes to obtain voice data from the music source server; As after playing startup; The data of one section set time length (like 10s) after when playing a music data piece, checking current play position are not downloaded as accomplishing as yet, then directly obtain data from the music source server.Such strategy is of value to a certain extent plays successional raising, but has some serious deficiencies, mainly is:
1) there is not consideration to reduce to start the compensation policy of time delay.Because system takes the P2P pattern, might download to the music data of reproduction time after earlier, and the music data of front delays to obtain to download, thereby increased the startup time delay;
2) do not confirm that which data really needs compensation.Might cause overabundance of data or very few compensation, too much compensation can increase server stress, makes the music source server become system bottleneck, influences the system expandability; Very few compensation causes plays continuous decreased performance, often occurs stagnating, and influences user experience.
To above deficiency, be necessary to propose a kind of compensation mechanism of P2P music demand system, play continuity to reduce starting time delay and music source server stress and assurance.
Summary of the invention
In order to solve startup delay problem, broadcast continuity problem and the system expandability problem that exists in the P2P music demand system, realize better music online service quality, the present invention proposes a kind of new compensation method.
Technical scheme provided by the invention is the compensation method of a kind of P2P music demand system of the compensation method of P2P music demand system; Include music source server and node in the said P2P music demand system; In the P2P music demand system, LIST SERVER is set, music source server, LIST SERVER and node realize that based on centralized destructuring topology network is connected; Said LIST SERVER is used to control the whole network nodal information and the resource node location is provided,
The data block of slabs such as the music data file that transmits in the P2P music demand system and play is divided into is also successively from 1 numbering, and each piecemeal is called 1 chunk;
Node in the P2P music demand system is selected chunk and is downloaded to other node requests that have this chunk; Each node is provided with a compensation space, is designated as C
A, be used to deposit the chunk numbering that this node maybe the needs compensation;
According to the situation of node startup playing back music data file, the startup compensation process is provided and has play compensation process,
Said startup compensation process is used for to play starting and the user VCR operation situation of buffer memory desired data piece not as yet afterwards, through predefined Probability p
cFrom the forward chunk of music source server requests reproduction time, start time delay to reduce; May further comprise the steps,
Step 1.1 needs the continuous chunk number of buffer memory based on starting the playing back music data file, need to confirm the chunk numbering of compensation;
Step 1.2, the chunk that needs are compensated numbers the compensation space C that puts into this node
A
Step 1.3 is not if the numbering of the chunk that downloads from other node requests belongs to compensation space C
A, and compensation space C
ABe not empty, then with Probability p
cSelect compensation space C
AIn the minimum chunk of numbering to the music source server requests, and with this chunk numbering from compensation space C
AIn remove;
Step 1.4 needs the continuous chunk of buffer memory all to accomplish download if play startup, plays to start, and starts the compensation flow process and finishes;
Said broadcast compensation process is used for situation about having started to playing, to the chunk that has little time to download from other node from the music source server requests, to guarantee to play continuity; May further comprise the steps,
Step 2.1 is downloaded the required time of chunk according to history, estimates from other nodes and downloads the time that chunk is required;
Step 2.2, the time of estimating according to step 2.1 is judged the chunk of needs compensation after the current play position;
Step 2.3 is put into compensation space C with the chunk numbering of needs compensation
A
Step 2.4 is with compensation space C
AIn the chunk of all reference numerals to the music source server requests, empty compensation space C then
A
Step 2.5 after current play position content play is accomplished, is returned step 2.2 and is compensated to new current play position, finishes playing up to whole music data file.
And; Node in the said P2P music demand system is selected chunk and is downloaded to other node requests that have this chunk; Implementation is that node periodically utilizes the chunk selection algorithm to select chunk and to the node request that has this chunk; Said chunk selection algorithm is based on preferential and the rare preference strategy of order, and gives preferentially higher-priority of order.
And the state of said chunk is divided into " not request ", " from node is downloaded ", " from server is downloaded " and " downloading " four kinds, and is overtime when certain chunk download, resets this chunk state and is " not request ".
And the chunk download time in the said broadcast compensation process is estimated, and implementation method is asked for centrifugal pump for the time difference from asking to receive of every chunk having downloaded according to node; Estimated time T
Ra ETrigger its dynamically adjustment between centrifugal pump according to the download situation, and centrifugal pump is upgraded by periodicity or trigger-type.
Music on Demand compensation mechanism provided by the invention includes: start compensation, the situation that has just added system or carried out the VCR operation to the user compensates; Compensate during broadcast, the situation that has started to music compensates.Through scheme provided by the invention, can reduce startup time delay, the assurance music continuity of music, and can improve the system expandability, thereby shorten period of reservation of number, improve user experience.
Description of drawings
Fig. 1 is a P2P music demand system general frame of the present invention;
Fig. 2 is a nodal cache structure of the present invention;
Fig. 3 is the T of the embodiment of the invention
Ra E(request of chunk arrives the estimated time) state transition diagram.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is carried out detailed description.
As shown in Figure 1; P2P music demand system of the present invention mainly is made up of music source server, LIST SERVER and the ordinary node (like peer1, peer2, peer3, peer4, peer5, peer6) that connect based on centralized destructuring topology realization network, can realize the network interconnection by Internet.Wherein the music source server is responsible for the storage and the distribution of original music data file; LIST SERVER is responsible for management and control, and all participate in nodal information; The situation such as joining day, play position, load that comprises each node; And help node to carry out the location of resource node; Ordinary node begins promptly periodically alternately with LIST SERVER from adding music demand system, makes the LIST SERVER user profile that can upgrade in time.Ordinary node generally is common Music Appreciation user's an individual main frame; Be responsible for resource request and also download service be provided for other users; Friendly user interface is provided simultaneously; Can realize getting into the P2P music demand system easily through inserting Internet, line node can realize that node is mutual in the net.The present invention adopts the centralized management scheme; LIST SERVER promptly is set safeguards the information of all participation nodes; Carry out the resource node location according to this whole network nodal information, promptly return to the optimum partner node tabulation that the music data resource is provided of user, its advantage is to respond the location fast; Can be optimized processing to the whole network music transmission, make whole P2P music demand system have the controllability of height.And the distributed schemes that prior art adopts has also increased response wait time simultaneously because the dispersion that nodal information is safeguarded is not suitable for concentrating management and control and network-wide optimization.The present invention adopts unstructured mode to carry out the distribution of audio content; It is the partner list that node returns according to LIST SERVER; Organize themselves into application layer overlay network for no fixed topology; Each node can provide music data for a plurality of other nodes, also can download required data from a plurality of partner nodes simultaneously, has reduced the influence that the node dynamic produces.And for the transfer of data under the structured mode, owing to need to safeguard the chain type or the tree of an application layer, its maintenance costs is big and can't solve the high dynamic problem of node.
The present invention is an isometric piece and since 1 serial number with the cutting of music data source file, divides each deblocking that obtains and is designated as 1 chunk, is transmission and the data unit play.Node adopts sliding window mechanism to come buffer memory and playing back music chunk.As shown in Figure 2; In order to reduce the discrete influence that causes of voice data; Node not only can buffer memory near the music data of current play position; Also can download the music data of remaining time of buffer memory in advance,, reduce the influence of scarce resource and discrete resource music demand system so that for other node provides service near play position.Among the embodiment, the node request msg is used same buffer memory with broadcast, is divided into two parts, and high-priority buffer and low-priority buffer are respectively with symbol B
H, B
LExpression.B
HBuffer memory is near the music data of play position, B
LThe inferior part music data that buffer memory is remaining near play position.B
HLength be l
H, B
LLength be l
L, whole buffer storage length is l
B, l then
H+ l
L=l
BB
HAnd B
LBe the fixed length buffer memory, l
HWith l
LRatio range suggestion get 1/6～1/2.If B (n) is n piece memory block in the nodal cache, from 1 open numbering, then B
HThe spatial cache scope be B (1), B (2) ..., B (l
H), B
LThe spatial cache scope be B (l
H+ 1), B (l
H+ 2) ..., B (l
B).If certain current play position of the moment is the m chunk of music data file, this moment, the corresponding relation of buffer memory and each chunk of audio data file was as shown in Figure 2, B
HB (1) in the spatial cache, B (2) ..., B (l
H) deposit successively m, m+1 ..., m+l
H-No. 1 chunk, B
LB (l in the spatial cache
H+ 1), B (l
H+ 2) ..., B (l
B) deposit m+l successively
H, m+l
H+ 1 ..., m+l
B-No. 1 chunk.The chunk that spatial cache is corresponding selects window W
HAnd W
LAlong with music is slided to the right.Chuck after the broadcast leaves in the local disk of node main frame, so that the music transmission service is provided for other node.
For the ease of indicating that the chunk in the node downloads situation, the state of chunk is divided into " Unrequested (request) ", " DownloadingFromPeer (from node is downloaded) ", " DownloadingFromServer (from server is downloaded) " and " Downloaded (downloading) " four kinds." Unrequested (not request) " expression is not downloaded from other nodes or music source server requests as yet; If download is overtime, the state that then can reset automatically is " Unrequested "." DownloadingFromPeer (from node is downloaded) " expression is in the downloading process to other node requests that has this chuck." DownloadingFromServer (from server is downloaded) " expression is in the downloading process to the music source server requests." Downloaded (downloading) " expression has been downloaded this chuck from other nodes or music source server, and perhaps node this locality has this chuck in advance and need not to ask download.
Node is selected chunk and is downloaded node to other node requests that have this chunk, and multiple implementation can be arranged.It is that node periodically utilizes the chunk selection algorithm to select chunk and to the node request that has this chunk that the present invention proposes implementation, and said chunk selection algorithm is based on preferential and the rare preference strategy of order, and gives preferentially higher-priority of order.For the ease of the chuck resource that has of explanation node, node uses bitmap (BitMap) information to characterize the state that oneself has the music data file piecemeal, " 1 " represent certain chunk deposit 4, " 0 " representes that certain chunk does not exist.Because node, dynamically adds the P2P music demand system often according to user's needs, after the node adding system,, periodically utilize the chunk selection algorithm to select chunk to download then to the resource node request at first to LIST SERVER request resource node; For the chunk of needs compensation, compensate simultaneously through server.Concrete mode does; Node is periodically asked message bit pattern to it according to the resource node tabulation that LIST SERVER returns; Select suitable chunk to download according to this message bit pattern, the chunk selection algorithm is: according to the BitMap information of resource node, with predefined Probability p
CsAt W
HIn select as yet not the chunk of request and return numbering with the order priority algorithm, with probability 1-p
CsAt W
LIn select as yet not the chunk of request and return numbering with rare priority algorithm; When not choosing the chunk that can download, the chunk that returns is numbered 0.Concrete order priority algorithm is at W
HThe interior numbering according to chunk selects the less not request chunk of numbering to ask successively, and rare priority algorithm is at W
LThe interior not request chunk that has minimum number in all resource nodes that selects asks.Those skilled in the art can adopt software mode realization order priority algorithm and rare priority algorithm according to concrete needs, and the present invention will not give unnecessary details.Probability p
CsThe suggestion span is 0.6～0.9, makes the preferential selection algorithm of order that higher priority arranged.
After node has just added the P2P music demand system or has carried out VCR operation (drag operation that the user carries out), often need be at buffer memory after the current play position behind one section continuous music data, start and play, play while download then.To accomplishing the whole process of playing, need low time-delay, high broadcast continuity and the low server stress of starting of using compensation mechanism guarantee from the beginning program request, and improve the extensibility of P2P music demand system.In order to compensate timely and effectively, each node is provided with a compensation space, is designated as C
A, be used to deposit the chunk numbering that this node maybe the needs compensation.When realizing compensation, can use certain compensation policy to select set C
AIn chunk download to the music source server requests.The compensation policy that the present invention adopts is according to the situation of node startup playing back music data file, the startup compensation process to be provided respectively and to have play compensation process.
Starting compensation is that purpose is to reduce to start time delay to the situation (generally being that node has just added system or carried out the VCR operation) that can not start the playing back music data file immediately, shortens period of reservation of number.Implementation strategy is through predefined probability P
cFrom the forward chunk of music source server requests reproduction time.Note play to start after the current play position of required buffer memory continuously that the number of chunk is N, then node play the condition that starts be spatial cache B (1), B (2) ..., B (N) is for full.If the chunk that B (1) (also being current play position) is corresponding is numbered m, concrete implementation procedure step is following:
Step 1.1 needs the continuous chunk number of buffer memory based on starting the playing back music data file, need to confirm the chunk numbering of compensation;
Embodiment is numbered m with chunk, m+1 ..., m+N-1 and the numbering that is in state " Unrequested (request) " are added compensation space C to
AIn.If it is overtime that certain moment chunk is numbered the chunk download of a ∈ [m, m+N-1], add C again to
AIn.
Step 1.2, the chunk that needs are compensated numbers the compensation space C that puts into this node
A
Step 1.3 is not if the numbering of the chunk that downloads from other node requests belongs to compensation space C
A, and compensation space C
ABe not empty, then with Probability p
cSelect compensation space C
AIn the minimum chunk of numbering to the music source server requests, and with this chunk numbering from compensation space C
AIn remove;
Among the embodiment, download for fear of same chunk from resource node and clash from the server compensation, remember that current chunk number of selecting according to the chunk selection algorithm is d, when not choosing the chunk that can download, it is 0 that the chunk that returns numbers d.If d is not 0, download this chunk to the resource node request.If d ∈ C
A, then because from selecting node to download, with this chunk from C
AIn shift out.Otherwise, if d does not belong to compensation space C
A, and compensation space C
ABe not empty, then can Probability p
cSelect C
AThe minimum chunk of interior numbering downloads to the music source server requests, and with this chunk numbering compensation space C
AIn remove.The present invention's suggestion, when d is 0, p
c=1; D is not 0 o'clock, suggestion p
cSpan be 0.5～0.7.Step 1.4 needs the continuous chunk of buffer memory all to accomplish download if play startup, plays to start, and starts the compensation flow process and finishes; If all accomplishing as yet, do not download the continuous chunk that playing startup needs buffer memory,
Among the embodiment, buffer memory after the current play position behind continuous N the chunk, play and start, start the compensation flow process and finish.
Said broadcast compensation process is used for situation about having started to playing, to the chunk that has little time to download from other node from the music source server requests, to guarantee to play continuity.In order to obtain the continuous performance of good broadcast, need relevant chunk before playing deadline, to accomplish and download, stagnate when avoiding playing; Simultaneously, can not too much download, be unlikely to excessive, improve system expandability ability to keep server stress from the music source server.The present invention provides concrete implementation procedure step following:
Step 2.1 is downloaded the required time of chunk according to history, estimates from other nodes and downloads the time that chunk is required;
Step 2.2, the time of estimating according to step 2.1 is judged the chunk of needs compensation after the current play position;
Step 2.3 is put into compensation space C with the chunk numbering of needs compensation
A
Step 2.4 is with compensation space C
AIn the chunk of all reference numerals to the music source server requests, empty compensation space C then
A
Step 2.5 after current play position content play is accomplished, is returned step 2.2 and is compensated to new current play position, finishes playing up to whole music data file.
Among the embodiment, establish the historical z chunk that downloads, its request is tr (z) constantly, receives ta (z) constantly, and then the request difference time of advent of z chunk is T
Ra(z)=t
a(z)-t
r(z).Estimate from other nodes and download the time that chunk is required, establish structure for estimating chunk request difference time of advent T
Ra E, establishing current play position is m chunk, if m+k (k=1,2,3 ...) number chunk request as yet, then be played to the condition that m+k chunk can occur stagnating and be:
T
Ra E＞k*b/r (formula 1)
Wherein, b is the data block size of chunk, and r is for playing code check, and b and r are definite value.Estimate the chunk request difference time of advent and during deadline, possibly before broadcast, can not receive this chunk from resource node greater than broadcast.Therefore, node is downloaded these chunk from the music source server requests, to reduce or to avoid stagnating.If the corresponding chunk of current play position is numbered m, compensation policy is following:
The chunk numbering that 1) will satisfy condition (formula 1) and be in state " Unrequested (request) " or " DownloadingFromPeer (from node is downloaded) " is added compensation space C to
AIn;
2) compensation space C
AInterior all chunk download to the music source server requests, empty compensation space C then
ASpecial is, from music source server downloading process, if compensation space C
AIn certain chunk accomplish to download from resource node, then notify the download of this chunk of music source server cancellation;
3) after current play position content play is accomplished, return 1) continue compensation, finish playing up to whole music data file.
Carry out above compensation policy, need be to the T in (formula 1)
Ra EValue is confirmed.Because can't be to T
Ra EEstimate accurately, so the mode that embodiment takes to carry out centrifugal pump estimation and dynamic adjustment in playing process the time of advent according to the request of downloading chunk is confirmed.Concrete definite mode is following:
The chunk number that note has been downloaded is D, T
Ra(z) z in gets 1～D, then T
Ra EDesirable centrifugal pump is: average:
Minimum value: T
Min=min{T
Ra(1), T
Ra(2) ..., T
Ra(D) }
Maximum: T
Max=max{T
Ra(1), T
Ra(2) ..., T
Ra(D) }
Definition set L={T
m(z) | T
Ra(z)＜T
M, set H={T
m(z) | T
Ra(z)>=T
M; If the size of set L is l, the size of set H is h, l+h=D, then
The average of set L:
The average of set H:
Above gained T
Min, T
L, T
M, T
HAnd T
MaxBe exactly T
Ra E5 desirable centrifugal pumps, and this 5 centrifugal pumps and T
Ra EValue all can when playing, dynamically adjust.If T
Ra EAdjustment cycle is T
u, T
uInterior broadcast is stagnated and is add up to C, note T
uThe interior chunk that before music source server requests and request, is in state " DownloadingFromPeer (from node is downloaded) " adds up to X, and these chunk can in time accomplish the x that adds up to that downloads from other node, with the triggering T that gives a definition
Ra EThe incident of dynamically adjusting:
1. T
uTime arrives, C＞C
o
2. T
uTime arrives, C＜=C
oAnd x/X＞ρ;
3. T
uTime arrives, C＜=C
oAnd x/X＜=ρ.
Wherein, T
uSuggestion value 30b/r～50b/r, C
oSuggestion value 3～5, ρ advises value 0.7～0.8.1. incident is represented if in a period of time, occur repeatedly playing stagnation behavior, T to be described owing to compensate in advance
Ra EValue is too small, needs the chunk of compensation not satisfy condition (formula 1), fails to add to C
AIn, thereby can not in time compensate, should increase T this moment
Ra E2. incident is represented if in a period of time, before music source server requests and request, be in the large percentage that the chunk of state " DownloadingFromPeer (from node is downloaded) " can in time obtain from other node; And do not have and stagnate or to stagnate number of times less, T is described
Ra EValue is excessive, overcompensate, and should reduce T this moment
Ra E3. incident is represented when stagnating number of times and timely acquisition ratio all hour, T
Ra ERemain unchanged.
In order to make the T that estimates
Ra EMore accurate, can upgrade centrifugal pump, promptly recomputate T
Min, T
L, T
M, T
HAnd T
MaxCentrifugal pump is upgraded can adopt to periodically update with trigger-type and is upgraded dual mode:
A) (4T is got in suggestion to preestablish update cycle Tc
u～6T
u), whenever the Tc time then, recomputate centrifugal pump, promptly periodically update.
B) as shown in Figure 3, when one of meeting the following conditions, recomputate centrifugal pump immediately, promptly trigger-type upgrades:
1) T
Ra E=T
Max1. and said incident takes place;
2) T
Ra E=T
Min2. and said incident takes place;
Can find out from condition, work as T
Ra EFor current maximum centrifugal pump and still need increase or T
Ra EFor current smallest discrete value and still need reduce the time, cause that the centrifugal pump trigger-type upgrades.
Because ask for gained t
Min, T
L, T
M, T
HAnd T
MaxBe ascending, sum up above-mentioned adjustment scheme, the T of embodiment
Ra EDynamically the state transitions of adjustment is as shown in Figure 3: work as T
Ra E=T
MaxThe time, 1. the generation incident then triggers the renewal of five centrifugal pumps, and the generation incident is T then 2.
Ra E=T
HWork as T
Ra E=T
HThe time, the generation incident is T then 1.
Ra E=T
Max, the generation incident is T then 2.
Ra E=T
MWork as T
Ra E=T
MThe time, the generation incident is T then 1.
Ra E=T
H, the generation incident is T then 2.
Ra E=T
LWork as T
Ra E=T
LThe time, the generation incident is T then 1.
Ra E=T
M, the generation incident is T then 2.
Ra E=T
MinWork as T
Ra E=T
MinThe time, the generation incident is T then 1.
Ra E=T
L, 2. the generation incident then triggers the renewal of five centrifugal pumps.T
Ra EDuring for arbitrary value, if 3. T of generation incident
Ra EThen continue to have.
When the broadcast compensation process has just started or after the centrifugal pump renewal, T need be set
Ra EInitial value, confirm needing the chunk of compensation according to (formula 1), and get into dynamically adjustment flow process, setting means respectively as follows:
After node has just added system or VCR operation, buffer memory the voice data of certain-length, music starts, and plays compensation process this moment and starts, and is to guarantee continuity initialization T
Ra E=T
Max
After centrifugal pump is upgraded, set T
Ra ENew centrifugal pump for ad eundem.For example: if T before upgrading
Ra E=T
Max, it is T that the note centrifugal pump is upgraded the new maximum in back
Max(new), after then centrifugal pump is upgraded, initialization T
Ra E=T
Max(new).
Claims (4)
1. the compensation method of a P2P music demand system; Include music source server and node in the said P2P music demand system; It is characterized in that: in the P2P music demand system, LIST SERVER is set, music source server, LIST SERVER and node realize that based on centralized destructuring topology network is connected; Said LIST SERVER is used to control the whole network nodal information and the resource node location is provided,
Transmission and the music data file play the data block of slab such as are divided into and since 1 number consecutively, each piecemeal is called 1 chunk in the P2P music demand system;
Node in the P2P music demand system is selected chunk and is downloaded to other node requests that have this chunk; Each node is provided with a compensation space, is designated as C
A, be used to deposit the chunk numbering that this node maybe the needs compensation;
According to the situation of node startup playing back music data file, the startup compensation process is provided and has play compensation process,
Said startup compensation process is used for to play starting and the user VCR operation situation of buffer memory desired data piece not as yet afterwards, through predefined Probability p
cFrom the forward chunk of music source server requests reproduction time, start time delay to reduce; May further comprise the steps,
Step 1.1 needs the continuous chunk number of buffer memory based on starting the playing back music data file, need to confirm the chunk numbering of compensation;
Step 1.2, the chunk that needs are compensated numbers the compensation space C that puts into this node
A
Step 1.3 is not if the numbering of the chunk that downloads from other node requests belongs to compensation space C
A, and compensation space C
ABe not empty, then with Probability p
cSelect compensation space C
AIn the minimum chunk of numbering to the music source server requests, and with this chunk numbering from compensation space C
AIn remove;
Step 1.4 needs the continuous chunk of buffer memory all to accomplish download if play startup, plays to start, and starts the compensation flow process and finishes;
Said broadcast compensation process is used for situation about having started to playing, to the chunk that has little time to download from other node from the music source server requests, to guarantee to play continuity; May further comprise the steps,
Step 2.1 is downloaded the required time of chunk according to history, estimates from other nodes and downloads the time that chunk is required;
Step 2.2, the time of estimating according to step 2.1 is judged the chunk of needs compensation after the current play position;
Step 2.3 is put into compensation space C with the chunk numbering of needs compensation
A
Step 2.4 is with compensation space C
AIn the chunk of all reference numerals to the music source server requests, empty compensation space C then
A
Step 2.5 after current play position content play is accomplished, is returned step 2.2 and is compensated to new current play position, finishes playing up to whole music data file.
2. the compensation method of P2P music demand system as claimed in claim 1; It is characterized in that: the node in the said P2P music demand system is selected chunk and is downloaded to other node requests that have this chunk; Implementation is that node periodically utilizes the chunk selection algorithm to select chunk and to the node request that has this chunk; Said chunk selection algorithm is based on preferential and the rare preference strategy of order, and gives preferentially higher-priority of order.
3. according to claim 1 or claim 2 the compensation method of P2P music demand system; It is characterized in that: the state of said chunk is divided into " not request ", " from node is downloaded ", " from server is downloaded " and " downloading " four kinds; Overtime when certain chunk download, reset this chunk state and be " request ".
4. according to claim 1 or claim 2 the compensation method of P2P music demand system; It is characterized in that: the chunk download time in the said broadcast compensation process is estimated; Implementation method is asked for centrifugal pump for the time difference from asking to receive of each chunk of having downloaded according to node; Trigger estimated time T according to the download situation
Ra EDynamic adjustment between centrifugal pump, and centrifugal pump is upgraded by periodicity or trigger-type.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100635780A CN101626400B (en) | 2009-08-11 | 2009-08-11 | Compensation method of P2P music on-demand system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100635780A CN101626400B (en) | 2009-08-11 | 2009-08-11 | Compensation method of P2P music on-demand system |
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| Publication Number | Publication Date |
|---|---|
| CN101626400A CN101626400A (en) | 2010-01-13 |
| CN101626400B true CN101626400B (en) | 2012-03-28 |
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| CN104661108A (en) * | 2013-11-25 | 2015-05-27 | 乐视网信息技术（北京）股份有限公司 | Media stream downloading method for terminal, terminal and communication system |
| CN104506929A (en) * | 2014-12-26 | 2015-04-08 | 电子科技大学 | Hybrid data scheduling method for P2P (peer to peer) systems |
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| CN101345768A (en) * | 2008-08-15 | 2009-01-14 | 南京邮电大学 | Peer-to-peer network transmission method of music demand system |
| CN101388909A (en) * | 2008-10-14 | 2009-03-18 | 中兴通讯股份有限公司 | P2P play-on-demand system and service method |
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| CN101345768A (en) * | 2008-08-15 | 2009-01-14 | 南京邮电大学 | Peer-to-peer network transmission method of music demand system |
| CN101388909A (en) * | 2008-10-14 | 2009-03-18 | 中兴通讯股份有限公司 | P2P play-on-demand system and service method |
Non-Patent Citations (1)
| Title |
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| 彭昭等.P2P异步传输点播系统设计与仿真.《计算机科学》.2009,第36卷(第2期), * |
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