CN107786560A - Multicast mobile device video conferencing system based on network code - Google Patents
Multicast mobile device video conferencing system based on network code Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/14—Systems for two-way working
- H04N7/15—Conference systems
- H04N7/152—Multipoint control units therefor
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/61—Network streaming of media packets for supporting one-way streaming services, e.g. Internet radio
- H04L65/611—Network streaming of media packets for supporting one-way streaming services, e.g. Internet radio for multicast or broadcast
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/70—Media network packetisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
- H04L65/60—Network streaming of media packets
- H04L65/75—Media network packet handling
- H04L65/765—Media network packet handling intermediate
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/50—Network services
- H04L67/56—Provisioning of proxy services
- H04L67/565—Conversion or adaptation of application format or content
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/50—Network services
- H04L67/56—Provisioning of proxy services
- H04L67/568—Storing data temporarily at an intermediate stage, e.g. caching
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- Computer Networks & Wireless Communication (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
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Abstract
The present invention provides a kind of multicast mobile device video conferencing system based on network code, system includes some user terminals and at least one encoder server, encoder server is used for the initial data for receiving and recompiling user terminal, and the data after recompiling are returned into user terminal；Data processing between encoder server and user terminal includes：Determine treatment conditions, data encoding and data management.The present invention have data transfer is stable, Media Stream adaptive ability by force, the advantages of alloing the heterogeneous device of different size and diverse location to add the meeting with different resolution.
Description
Technical field
The invention belongs to network technique field, and in particular to a kind of multicast mobile device video conference based on network code
System.
Background technology
Video conferencing system is the typical case of video transmission technologies on the internet.The development of mobile device so that this
The application of sample has vast potential for future development.For mobile device high-quality video conference system will the coming years increasingly
Popularization.Limited network bandwidth and extreme link-quality are that we face in the implementation process of some multi-user's transmission of video
Challenge.Under such application scenarios, each user is required for establishing and keeps contacting with other all users, often drops
The unicast joint efficiency of low network.With unicast connection, multicast connection can also be used by internet.When multicasting technology is adopted
With the user with identical data demand can share a common link.Therefore, multicasting technology can the company of substantially reducing
The number connect, thus increases network throughput.
However, the multicast packet of the conventional method in the wireless networks of IEEE 802.11 is actually the mode in open loop
(not feeding back), do not support to use in the transmission of video of QoS (service quality).Correlative study in the past decade shows,
Network code is to implement the technology in two cable networks and the QoS of wireless network, and it has a variety of video compression standards,
Such as H.264/AVC and H.265.According to some previous studies, network code can make together with some video compression standards
With such as H.264/AVC.
Network code is the systems approach using the video compression system after data transfer.T.T.Thai et al. proposes reality
When transmission of video network coding-redundancy adaptive algorithm, and they show that their scheme is based on better than tradition
The FEC code of block.It is proposed to be based on network coding scheme for application, A.Le et al. in real time, in their scheme, cover again
Packet is the maximum quantity for being advantageous to user immediately.This method has the advantages of network code, such as high handling capacity and reliably
Property, and during this period, the side effect of network code, as playout-delay is lowered.S.Nazir et al. proposes use and existed
H.264/SVC data division stochastic linear code (RLC), their empirical result show, RLC is having very much for multimedia broadcasting application
The method of future.After the theoretical research in more than ten years, some scholars are had begun to the real application systems based on network code
Research.Recently, the application of some practical network codings is also, it has been proposed that D. Ferreira et al. propose one kind
RTNC (Real-Time Network Coding, real-time network coding) is in high-density wireless spatial flow media multicast system.He
Compare they and traditional unicast scheme system, its result shows that bandwidth used can be by using network code
To dramatically increase.F.H.P.Fitzek et al. carries out some practical studies on network code, and realizes a network
Based on coding image shared system.Although some above-mentioned prototypes are proposed by previous studies person, the reality of network code
Border is applied or seldom, and not yet realizes stable transmission and the efficient process of multicast video conference system.
A kind of processing method (application number CN201010116447.7) of video conferencing system of Chinese patent, wherein video council
Conference system includes home terminal device and at least one remote terminal unit, and the processing method includes：When passing through video conference
When system carries out video conference, feature is carried out respectively on the home terminal device and remote terminal unit in video conferencing system
Detection；Feature detection result based on home terminal device and remote terminal unit, for the current meeting of video conferencing system
Discuss scene setting conference model；Based on active conference pattern, home terminal device and remote terminal in video conferencing system
Frame of video segmentation is carried out on device, and pre-treatment is carried out to the region after segmentation to carry out Video coding.The program passes through entirety
Change the both ends of conference system, realize the region segmentation based on conference model, to adjust the scene focus of video, but its core is logical
Feature detection is crossed, the load of data transfer can not be reduced, when link-quality is very poor, the Media Stream of clear and smooth can not be provided.
Therefore urgent need wants a kind of data transfer stabilization, Media Stream adaptive ability is strong, causes different size and diverse location
Heterogeneous device can add the multicast mobile device video conference system based on network code of the meeting with different resolution
System.
The content of the invention
It is an object of the invention to provide a kind of multicast mobile device video conferencing system based on network code and processing side
Method, to solve the problems, such as that prior art data transfer load is big, overall performance stability is not good enough.
The invention provides following technical scheme：
A kind of multicast mobile device video conferencing system based on network code, the system is including some user terminals and extremely
A few encoder server, the encoder server are used for the initial data for receiving and recompiling the user terminal, and should
Data after recompiling return user terminal；Data processing between the encoder server and the user terminal includes following step
Suddenly：S1, determine treatment conditions：Encoder server is chosen as intermediate node and determines the basic parameter of the system；S2, number
According to coding：Encoder server obtains encoder matrix according to the basic parameter described in S1, and is prepared based on the encoder matrix, restructuring
Data, and then generate coded data packet and the coded data packet is returned into user terminal decoding；S3, data management：To in S2
Described encoder server sets the timer and double buffering worked in coordination, and judges and controls the weight of data in coded data packet
It is newly encoded/to delete.
Preferably, the basic parameter of the system includes finite field q, based on k frames caused by finite field q and finally original
The value of data L, wherein k in the multicast video conference system of operation is dynamic, and chooses q=256.
Preferably, periodically multicast packet is to the user terminal for the encoder server, and the encoder server is rear
Data encoding before one group of data transfer to being received in current period.
Preferably, the user terminal receives the multicast packet and the data is decoded and recover all primitive frames,
Wherein, the decoding throughput of user terminal is more than its receiving velocity.
Preferably, the acquisition methods of the encoder matrix include below equation：
Wherein, M is the matrix of n rows k row, and T is the matrix of k rows k row.
Preferably, the preparation, recombination data are based on below equation：
P=[P1,P2,...,Pn]=Gn*k× P=Gn*k[P1,P2..., Pn]T
Wherein, P1, P2, Pk... it is initial data, P1, P2..., PnIt is the data after encoder server coding.
Preferably, in the step S3, the double buffering matching has double buffering dispatching algorithm, and the double buffering scheduling is calculated
Method is used for the order of packets of the regular coded data packet；The timer is used to periodically check data in two buffering areas
Life span, if the time more than 0.1 second, delete two buffering areas in all data.
Preferably, the data management also includes the encoding rate control based on the coding controller, the coding-control
Device adjusts the dimension of coding vector according to decoding complex degree, wherein, decoding complex degree is：O (l × dimension × dimension).
The beneficial effects of the invention are as follows：
1st, from intermediate node of the encoder server as whole system, corresponding encoding scheme is set, is advantageous to be lifted
The reliability of transmission and the accuracy of data processing；
2nd, using double buffering and timer based on double buffering dispatching algorithm, be advantageous to overcome the suitable of coded data packet
Sequence entanglement and the freebuf for being advantageous to find high probability for new data, and then the operation for being advantageous to total system is steady
Qualitatively lifted；
3rd, controlled in data management using encoding rate, the real time data processing performance of lifting system；
4th, the present invention realizes the multicast of multi tate, overall performance stabilization by the data recombination coded treatment of intermediate node
Reliably, have wide range of applications.
Brief description of the drawings
Accompanying drawing is used for providing a further understanding of the present invention, and a part for constitution instruction, the reality with the present invention
Apply example to be used to explain the present invention together, be not construed as limiting the invention.In the accompanying drawings：
Fig. 1 is present system structural representation；
Fig. 2 is process flow step schematic diagram of the present invention；
Fig. 3 is multicast video conference system network model schematic diagram；
Fig. 4 is the code capacity curve map of multicast video conference system under distinct device；
Fig. 5 is the data recombination schematic diagram of data matrix；
Fig. 6 is data original size and different resolution contrast curve in system；
Fig. 7 is the data actual size block diagram in different coding strategy schemes；
Fig. 8 is the data format schematic diagram of intermediate node；
Fig. 9 is test experiments environment schematic；
Figure 10 is experimental program pictorial diagram；
Figure 11 is the decoding capability line chart for the equipment that multicast video conference system is run in test；
Figure 12 is signal intensity and packet loss line chart；
Figure 13 is the reliability line chart under different encoding schemes；
Figure 14 is the system delay time table (unit under different operating：Millisecond).
Embodiment
Embodiment one
A kind of multicast mobile device video conferencing system based on network code, the system is including some user terminals and extremely
A few encoder server, the encoder server are used for the initial data for receiving and recompiling the user terminal, and should
Data after recompiling return user terminal；Data processing between the encoder server and the user terminal includes following step
Suddenly：S1, determine treatment conditions：Encoder server is chosen as intermediate node and determines the basic parameter of the system；S2, number
According to coding：Encoder server obtains encoder matrix according to the basic parameter described in S1, and is prepared based on the encoder matrix, restructuring
Data, and then generate coded data packet and the coded data packet is returned into user terminal decoding；S3, data management：To in S2
Described encoder server sets the timer and double buffering worked in coordination, and judges and controls the weight of data in coded data packet
It is newly encoded/to delete.The basic parameter of system includes finite field q, based on k frames caused by finite field q and final initial data L,
Values of the wherein k in the multicast video conference system of operation is dynamic, and chooses q=256.
Wherein, periodically multicast packet is to the user terminal for encoder server, and the encoder server is in later group number
According to the data encoding before transmission to being received in current period.User terminal receive the multicast packet and to data decoding and
Recover all primitive frames, wherein, the decoding throughput of user terminal is more than its receiving velocity.
The acquisition methods of encoder matrix include below equation：
Wherein, M is the matrix of n rows k row, and T is the matrix of k rows k row.
The preparation, recombination data are based on below equation：
P=[P1,P2,...,Pn]=Gn*k× P=Gn*k[P1,P2..., Pn]T
Wherein, P1, P2, Pk... it is initial data, P1, P2..., PnIt is the data after encoder server coding.
In step S3, the double buffering matching has double buffering dispatching algorithm, and the double buffering dispatching algorithm is used for regular
The order of packets of the coded data packet；When the timer is used to periodically check the existence of data in two buffering areas
Between, if the time more than 0.1 second, delete two buffering areas in all data.Data management also includes being based on the coding
The encoding rate control of controller, the coding controller adjust the dimension k of coding vector according to decoding complex degree, wherein, decoding
Complexity is：O(l×k×k).
Wherein, double buffering dispatching algorithm is as follows：
1:A packet pkg is received.
2:if pkg.Gid is in receiving group A or B then
3:Copy data in pkg to corresponding buffer.
4:if the data in the buffer is enough to decode then
5:Decode the original frames.
6:Display the frames and clear this buffer.
7:end if
8:else
9:if there is a vacant buffer then
10:Record the arriving time.
11:Copy the data in this new group to the vacant buffer.
12:else
13:Clear the buffer in which the Gid is less than the other buffer.
14:end if
15:end if
Embodiment two
As shown in figure 3, being somebody's turn to do the data flow of the multicast mobile device video conferencing system based on network code can describe such as
Under：First, all user terminals pass through the present frame of TCP linkup transmits to encoder server；Secondly, successfully connect in encoder server
The frame from different user end is received, the data after coding are returned into all user terminals by multicast connects；Again, encoding service
As long as device receives enough data encodings, each user can decode all primitive frames.
Specifically, working as the plan implementation of network code in multicast video conference system, there are three basic parameter needs
It is determined that i.e. finite field q size, k size, and original final data L size are produced.Finite field gf (256) can be tieed up
Hold well balanced between computational efficiency and resource overhead.Therefore, in encoder server and user terminal, q is set as 256.This
Outside, k is arranged to active users.Encoder server is recompiled using n-k (n >=K) generator matrix and receives k frames, so
The data after coding are returned into user terminal afterwards.For each user terminal, when k independent packets are collected, it can be with
Decode original k frames.Values of the k in the multicast video conference system of operation is dynamic.Encoder server will periodically be compiled
The frame multicast of code is to user terminal, and before the transmission of next framing, encoder server is by it in all frames that currently period receives
Encoded.In order to avoid meaningless etc. to be delayed, when encoder server receives frame data, will start to start as early as possible.
In runtime, the arrival time of different frames is probably different, so the k values during different multicasts are always different
's.The size L of initial data is relevant with the frame definition of video flowing.In multicast video conference system, user terminal (i.e. source node)
Network code is not performed, encoder server (intermediate node) will all recompile operation.However, when data encoded is sent out
When sending user terminal back to, user terminal needs to decode and recover all primitive frames.For each mobile device (user terminal), it is solved
Code handling capacity should be greater than its receiving velocity.Therefore, decoding capability determines the size of initial data indirectly.
As shown in figure 4, in different user terminals, the code capacity of multicast video conference system be it is different, therefore
According to this optimization correlative coding rate, first, Android applications are all to use java language developments, and the coding in encoder server
Module is by JNI interface encapsulations in the C language storehouse of an opposite java code.Secondly, create within the library for multiplication
With the look-up table of division arithmetic.Again, all operations are all realized by Galois domains instead of the macro substitution of function call.
In an encoding process, it is encoded as described above shown in formula, M is the matrix of n rows k row, and T is the matrix of k rows k row.Pass through
Recompiled using encoder matrix, can be to ensure that it is all that any user terminal can be successfully decoded as long as k is received according to block
Initial data.In addition, even if user terminal only receives K-1 data block, it can recover all using the framework of oneself
Original frame.In most cases, it can even recover all primitive frames.Then, encoder server can generate solution
The coded data packet for the Line independent determined.Because selection q is 256, so will there are enough linear dependence vectors to recompile
The frame received.
As shown in Figures 5 to 7, the reorganization process of data, and the system coding situation under varying environment are shown,
In actual environment, the rate requirement of user is always different.Have several reasons, such as the multi-size of video camera, to APS away from
From APS transimission power etc..By reorganizing the data of same framing, it can not only improve bandwidth efficiency, but also can
To meet the demand of the heterogeneous device of different rates.If data encoding strategy in the past is by handling wanting for multi -rate transmission
Ask, then substantial amounts of bandwidth will be wasted.
As shown in figure 8, framework (i) refers to the byte arrays from the present frame of i-node.The S1-S3 of three bytes is used for representing
The size of frame.Pid represents the identifier of mobile device.In the size that the byte arrays of coded data, K refer to, S1-S K are every
The size of individual encoding block, and the block that C1-CK is used to generate coding using storage coding vector.In NCVCS, 2048 words are often surrounded by
The coded data of section.The size of the size of initial data, the size of coded data and application layer data in each bag is as follows：
The information rate of multicast video conference system can be expressed as LO/LP。
In encoding rate control, when multicast video conference system is operated in real environment, the quantity of client is dynamic
Change.When client is seldom, client should send the video of high-frequency or high quality, with the increase of customer quantity, decoding
Complexity can accordingly increase, and in this case, client needs to reduce transmission frequency, and such user terminal can be within the object time
Initial data is decoded.If client can not decode to initial data in time, data will block in user terminal, and this will significantly
Reduce real-time performance.
The capacity of user terminal process have to be larger than reception capacity, can so tolerate the delay jitter of burst.When k becomes high
When, the size of the coded data in each group will increase, and this will increase the time delay of decoding.In this case, user terminal
Need to reduce information content, reduce the resolution ratio of video or the frame rate of reduction.
The encoding rate control strategy that encoder server uses is the dimension k for changing coding vector.The decoding of network code is answered
Miscellaneous degree is O (l × k × k), and wherein l refers to the length of data, and k is then the quantity of user terminal in this group.When the frame received
Another user terminal is encoded to from a user terminal, decoding complexity is O (l × k1 × k1+ ...+O (l × kj × kj), wherein k
=k1+k2+ ...+kj.In this way, the fault-tolerant ability of user terminal can be lifted.When k is reduced to 1, the program will deteriorate to tradition
Multicasting technology application.
Embodiment three
As shown in figure 9, building real test platform, the operation for testing the multicast video conference system is handled.
The testing stand by a CS (encoder server), three WAPs and based on Android operation system ten
Five equipment are formed.Wherein, eight equipment (being designated as SR) not only send the video of oneself, but also receive and come from other participants
Video, other seven equipment (being designated as R) only receive video.Experimental situation is as shown in Figure 9.
Three AP connect wired connection with CS, so wireless channel will not be taken.The CS of test platform is a notebook
Computer, it is equipped with 4.7G CPU and 4G internal memories.The video that all SR captures obtain from video camera, is then sent by TCP and regarded
Frequency is to CS connections with the transmission that assures success.Frame is recompiled, linkup transmit coded data is controlled by multicast, now WR2 is forwarded
Multicast information WR1 and WR3.Finally, the data of 15 all mobile devices are decoded, then carries out multicast connects.Figure 10
Show experimental program.
Based on this, the test analysis of the feasibility of the program, reliability and delay performance is carried out：
First, feasibility
As shown in figure 11, we have tested the decoding capability of the Android device in final section, but obtain these
When as a result, the computing resource of system is otherwise fully engaged.Decoding performance can not possibly represent multicast video meeting system under ideal conditions
Performance during system operation, the decoder module of encoder server are operationally used as a thread, and the system needs to do many work,
Such as video preview frame-grab, the compression of data compression, transmission of video, display etc..It would therefore be desirable to assess in actual environment
Decoding capability.
Compared with the result in Fig. 4, decoding capability is also reduced when running multicast video conference system.When k be equal to 8, solution
Code handling capacity is about 1MB/s, is as a result shown in the operating video quality of multicast video conference system and transmission frequency.
2nd, reliability
In experimental situation, such as position, preceding there is obstacle, transmitting in the signal intensity of Radio Link always because of a variety of causes
The influence of the unlike signal intensity such as power AP, different bursts dropping ratios is produced naturally.Therefore we obtain test platform and set
Standby packet loss, then the reliability of the program and traditional scheme is assessed.
As shown in figure 12, for android system to we provide an interface to obtain WiFi signal intensity, value is from 0
To 100, this value is higher, and signal intensity is poorer.According to Figure 12, bursts dropping ratio and signal intensity do not have strict linear pass
System.There is several factors that this phenomenon, such as delay jitter are may result in, the diversity of access point and network congestion etc..
As shown in figure 13, when no maintenance kit is actively sent, the recovery framework of multicast video conference system is than traditional
The method of multicast is small, because the loss of any packet in a group can cause the decoding of all frames to be lost during the transmission
Lose, and when the packet of some reparations is actively sent to user terminal, this performance will be improved.
3rd, delay analysis
On the basis of experiment, we assess the delay hair that compared for multicast video conference system and traditional multicasting method
Send, recompile, multicast and decoding cases, as shown in figure 14, when k is equal to 8, eight frames will be chosen as sample, this eight kinds of frameworks
Total size be 196KB.When k is equal to 4, four frames will be selected, and size is 104KB.The equipment of different size has different performances
Difference.In our experiment, using equipment Galaxy S4, encoder server is a CPU AMD a8-4500m notebook,
It is equipped with 1.9GHz 4G internal memories.
In traditional multicasting technology and multicast video conference system, each user terminal only sends 1 frame during experiment.According to knot
Fruit, transmission time are almost identical.When traditional method of multicasting is used, it need not be encoded to different frames,
Its time being used for required for showing a frame is about 30 milliseconds, and in this programme, when k is equal to 8, multicast video conference system needs
246 milliseconds of all 8 frames of display.It can be observed, the recompiling of this programme but adds calculating of the operation decoding more than 20% and prolonged
Late, certain negative effect is produced to Consumer's Experience.
In multicast video conference system, the advantage of network code can be more obvious.It is traditional when packet loss rate is high
Method must use transmission strategy again, to ensure the service quality in multicast network.However, transmission will produce twice again
Transmission delay.When using this programme coding, it can avoid transmitting again.Although the packet of some redundancies is introduced into, always
Across the task delay of body is relatively low.Therefore, bandwidth availability ratio can be improved using this programme.
When initial data decodes, client needs to obtain receiving matrix by finding the inverse matrix.When k is very high, inverse matrix will
There is substantial amounts of computing cost.In testing, k is less than or equal to 8, therefore the protocol overhead is less than 0.2 millisecond.Therefore, inverse square is obtained
Time needed for battle array is not included in fig. 14.But when the quantity increase of client, this delay is then specifically contemplated that.
The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the invention, although with reference to foregoing reality
Apply example the present invention is described in detail, for those skilled in the art, it still can be to foregoing each implementation
Technical scheme described in example is modified, or carries out equivalent substitution to which part technical characteristic.All essences in the present invention
God any modification, equivalent substitution and improvements made etc., should be included in the scope of the protection with principle.
Claims (8)
1. a kind of multicast mobile device video conferencing system based on network code, it is characterised in that the system includes some
User terminal and at least one encoder server, the encoder server are used for the original number for receiving and recompiling the user terminal
According to, and the data after recompiling are returned into user terminal；Data processing between the encoder server and the user terminal
Comprise the following steps：
S1, determine treatment conditions：Encoder server is chosen as intermediate node and determines the basic parameter of the system；
S2, data encoding：Encoder server obtains encoder matrix according to the basic parameter described in S1, and is based on the encoder matrix
Prepare, recombination data, and then generate coded data packet and the coded data packet is returned into user terminal decoding；
S3, data management：The timer and double buffering worked in coordination are set to the encoder server described in S2, judges and controls
Data recompiles/deletes in coded data packet processed.
2. a kind of multicast mobile device video conferencing system based on network code according to claim 1, its feature exist
In the basic parameter of the system includes finite field q, based on k frames caused by finite field q and final initial data L, wherein k
Value in the multicast video conference system of operation is dynamic, and chooses q=256.
3. a kind of multicast mobile device video conferencing system based on network code according to claim 2, its feature exist
In periodically multicast packet is to the user terminal for the encoder server, and the encoder server is in later group data transfer
Data encoding to being received in current period before.
4. a kind of multicast mobile device video conferencing system based on network code according to claim 3, its feature exist
In, the user terminal receives the multicast packet and the data is decoded and recover all primitive frames, wherein, user terminal
Decoding throughput is more than its receiving velocity.
5. a kind of multicast mobile device video conferencing system based on network code according to claim 1, its feature exist
In the acquisition methods of the encoder matrix include below equation：
Wherein, M is the matrix of n rows k row, and T is the matrix of k rows k row.
6. a kind of multicast mobile device video conferencing system based on network code according to claim 5, its feature exist
In the preparation, recombination data are based on below equation：
P=[P1,P2,...,Pn]=Gn*k× P=Gn*k[P1,P2..., Pn]T
Wherein, P1, P2, Pk... it is initial data, P1, P2..., PnIt is the data after encoder server coding.
7. a kind of multicast mobile device video conferencing system based on network code according to claim 1, its feature exist
In in the step S3, the double buffering matching has double buffering dispatching algorithm, and the double buffering dispatching algorithm is used for regular institute
State the order of packets of coded data packet；The timer is used for the life span for periodically checking data in two buffering areas,
If the time more than 0.1 second, deletes all data in two buffering areas.
8. a kind of multicast mobile device video conferencing system based on network code according to claim 5, its feature exist
In the data management also includes the encoding rate control based on the coding controller, and the coding controller is multiple according to decoding
The dimension of miscellaneous degree adjustment coding vector, wherein, decoding complex degree is：O (l × dimension × dimension).
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| CN109618170A (en) * | 2018-12-04 | 2019-04-12 | 嘉兴国电通新能源科技有限公司 | D2D real-time video streaming transmission method based on network code |
| CN109729307A (en) * | 2019-02-28 | 2019-05-07 | 北京理工大学 | A kind of multicast desktop video conferencing system based on fountain codes |
| CN110769413A (en) * | 2019-09-24 | 2020-02-07 | 厦门大学 | Data transmission method and system for multi-party conference |
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| CN109618170B (en) * | 2018-12-04 | 2021-10-01 | 嘉兴国电通新能源科技有限公司 | D2D real-time video streaming transmission method based on network coding |
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