CN100446452C - Data transmission protection based on correcting and eleting codes - Google Patents
Data transmission protection based on correcting and eleting codes Download PDFInfo
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- CN100446452C CN100446452C CNB2005100661467A CN200510066146A CN100446452C CN 100446452 C CN100446452 C CN 100446452C CN B2005100661467 A CNB2005100661467 A CN B2005100661467A CN 200510066146 A CN200510066146 A CN 200510066146A CN 100446452 C CN100446452 C CN 100446452C
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
- H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
- H03M13/11—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits using multiple parity bits
- H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/37—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35
- H03M13/3761—Decoding methods or techniques, not specific to the particular type of coding provided for in groups H03M13/03 - H03M13/35 using code combining, i.e. using combining of codeword portions which may have been transmitted separately, e.g. Digital Fountain codes, Raptor codes or Luby Transform [LT] codes
Abstract
The present invention provides a method for data transmission protection based on erasure codes. The data transmission protecting method has the core that one an erasure code with a correcting node layer is arranged, and the data transmission protection is carried out according to the erasure code. The method for data transmission protection is only provided with the erasure code with the correcting node layer under the condition of ensuring no obvious drop of the ability in data transmission protection. The operation quantity for the erasure code to generate the correcting node layer is effectively reduced, and the delaying time of data transmission is greatly reduced, so that the protecting performance and the performance-to-price ratio of the data transmission are improved, and the method for data transmission protection of the present invention can be better suitable for the technical field of H.263, H.264, etc. Accordingly, the technical scheme provided by the present invention realizes the purposes that the performance-to-price ratio and the efficiency of the data transmission are improved, and the application of the new technology, such as the H.264, etc. is promoted.
Description
Technical field
The present invention relates to anti-packet loss mistake technical field in the communication system, be specifically related to a kind of data transmission protection based on correcting and eleting codes.
Background technology
Correcting and eleting codes is the anti-widely packet loss mistake of an a kind of use technology.
Tornado sign indicating number in the correcting and eleting codes is because it is with respect to other correcting and eleting codes such as Reed-Solomon sign indicating number etc.; have characteristics such as simple in structure, that computing is efficient, protective capability is strong; in the data transmission procedure of reality, especially in the real-time Transmission process of audio frequency, video data, obtained to use comparatively widely.
So-called Tornado sign indicating number, exactly the data code flow order is divided into piecemeal the identical unit one by one (Unit) of size, also be called back end (Data Nodes), according to certain mathematical operation rule these back end are calculated then, produce the check-node (Parity Nodes or CheckNodes) of ground floor, continue to produce the check-node of the second layer according to identical or different mathematical operation rule computings for the check-node of ground floor, and the like, can generate the 3rd layer, the 4th layer, until the check-node of N layer.
Because each node layer number successively decreases according to fixing ratio in the Tornado sign indicating number, one of the structure image that makes the Tornado sign indicating number is the pyramid of half-twist to the right, as shown in Figure 1.According to the sum rule of geometric progression as can be known, the interstitial content in the whole pyramid structure is the p multiple of back end number, and p wherein is integer not necessarily.
Above-mentioned multiple relation makes the Tornado sign indicating number in data transmission procedure, finally the interstitial content and the back end number n that need handle in coding side and decoding end is a kind of linear relationship, this means that the encoding and decoding end handles time complexity that the Tornado sign indicating number needs and the data section n that counts and have linear relationship, promptly have linear session characteristic (1inear-time).
Have the linear session characteristic just because of the Tornado sign indicating number, make its operation efficiency height, be applicable to the real time communication of communication system.
Each check-node of Tornado sign indicating number and each back end all send to receiving terminal by transmitting terminal by network.If in network transmission process, part of nodes has been lost, because upper layer node has been participated in the generation of lower level node, be that the information of upper layer node has been included in lower level node and more in the lower level node, therefore, the node of losing can by the lower level node of enough numbers or more lower level node recover fully.If each node is a bag, the bag of then losing can be wrapped fully by other that correctly receives and recover, thereby realizes the transfer of data protection.
At present, adopt the Tornado sign indicating number to realize comprising the steps: based on the data transmission protection of video compression coding H.261/H.263/H.263+/H.263++/H.264
Structure at step 1, design Tornado sign indicating number.Be specially: according to given protective capability, other requires, concrete data type such as audio frequency still be factor determination data node size such as video, speed size be the L1 bit, according to the scale factor that contracts of passing of interstitial content between the number of stories m of factor specified data interstitial content n, integrity checking interstitial content L such as acceptable maximum network delay in the concrete application, middle verification layer, each layer
Deng, determine left side degree distribution vector and the right degree distribution vector of the bigraph (bipartite graph) between the node of any adjacent two layers.Pass the scale factor that contracts and be used to describe the proportionate relationship that contracts of passing on the adjacent two layers interstitial content.
To step 2, adopt the mode of Random Graph coupling to generate bigraph (bipartite graph) at random between each adjacent two layers node according to above-mentioned left side degree distribution vector and the right degree distribution vector.
To step 3, beginning data transmission procedure, the H.261/H.263/H.263+/H.263++/H.264 video encoder of transmitting terminal produces data code flow, and this data code flow need carry out the transfer of data protection.
To step 4, the data code flow that needs protection, be divided into equal-sized back end D with L1 bit
0, D
1, D
2, D
3... .D
T
To step 5, make t=0.
To step 6, obtain D
t, D
T+1... .D
T+n-1N data node.
To step 7, according to the bigraph (bipartite graph) at random between the definite adjacent two layers node of step 2 is a said n data node D
t, D
T+1... .D
T+n-1Successively generate each middle check-node layer MC
(0), MC
(1)... MC
(m)With terminal check node layer FC.
To step 8, with back end D
t, D
T+1... .D
T+n-1With check-node in each the check-node layer that generates by step 7 all by being sent to receiving terminal after the packing of network packing manner such as UDP/IP or TCP/IP.
Judge according to the numerical value of t, T whether all back end dispose to step 9, transmitting terminal, if all back end dispose, to step 10; Otherwise t=t+n is to step 6.
Communication process at step 10, transmitting terminal finishes.
Because transmitting terminal carries out on one side often that encoding compression sends in the real time communication process, be not temporal sequencing so above-mentioned steps 3 to step 8 represents, but sequencing in logic.
Said process is described transmitting terminal, for receiving terminal, after receiving terminal receives a collection of back end and check-node, at first should judge which back end be receive and in fact lost, and recoverable back end, then, for above-mentioned that lost and recoverable back end according to the recovery of decoding of the general decode procedure of Tornado sign indicating number.Receiving terminal repeats above-mentioned reception and recovery process, finishes up to communication process.
Though the Tornado sign indicating number has characteristics such as simple in structure, that computing is efficient, protective capability is strong with respect to other correcting and eleting codes; but; because the Tornado sign indicating number need generate a plurality of intermediate level of nodes; need adopt relatively more complicated computational methods such as Reed-Solomon when needing the check-node in calculating layer by layer and the generation terminal check node layer; increase a large amount of evaluation works to transmitting terminal; Chuan Shu video data is big as itself amount of calculation of compressed encoding H.264 if desired; then need transmitting terminal to have very strong computing capability, H.264 wait The Application of Technology thereby limited.
By the structure of Tornado sign indicating number as can be seen, if the every node layer data of Tornado sign indicating number are with respect to the scale factor that successively decreases of last node layer number
And m=3 because the number of the 3rd layer of check-node is 2 at least, then can instead release back end number n=16.That is to say, if with a two field picture as a data node, then adopt the Tornado sign indicating number can bring the time delay of 16 frames.In the application of reality, the video communication frame per second can not surpass 30fps, and 16 frames add the time delay of others with regard to the corresponding time delay that surpasses 0.5 second so, makes the time delay of video Data Transmission just very big.Even if m=2, because the time delay that the Tornado sign indicating number brings also had more than 0.25 second.
Because NAL (Network Adaption Layer network adaptation layer) data format H.264 is that IETF (Internet Engineering Task Force) just finishes; the existing method that realizes the transfer of data protection based on the Tornado sign indicating number at function H.264NAL, and does not H.264NAL reach the best fit effect.
Summary of the invention
The objective of the invention is to; a kind of data transmission protection based on correcting and eleting codes is provided; by the correcting and eleting codes that one deck check-node layer is only arranged is set; under the situation that does not have significantly to descend in the transfer of data protective capability, what overcome prior art requires shortcoming high, that the data transmission period delay is long, H.264 restriction waits technology to use to the transmitting terminal computing capability.
For achieving the above object, a kind of data transmission protection based on correcting and eleting codes provided by the invention comprises:
Big young pathbreaker's data code flow according to the packet of back end correspondence in the Tornado code data node layer is divided into the back end that pre-determines the back end number; According to the incidence relation of the XOR between described Tornado code data node layer and the check-node layer and at random bigraph (bipartite graph) be that the described back end of cutting apart generates the check-node layer that one deck has the check-node that pre-determines the check-node number;
The check-node of described back end of cutting apart and generation is transferred to receiving terminal;
Described receiving terminal is when determining that transmitting the back end of losing can be resumed, according to the described back end of losing of incidence relation recovery of the check-node of its reception, described bigraph (bipartite graph) at random, described XOR.
Comprise before the described method: determine in the size, back end layer of the packet of back end correspondence in the back end layer of described Tornado sign indicating number check-node number in back end number, the check-node layer; Determine the bigraph (bipartite graph) at random between described back end layer and the check-node layer and the incidence relation of XOR.
Determine the back end number that comprises in the size, back end layer of the packet of back end correspondence in the back end layer of described Tornado sign indicating number, the check-node number that the check-node layer comprises according to message transmission rate, data type, data protection Capability Requirement, network delay demand.
The step of the bigraph (bipartite graph) at random between wherein definite described back end layer and the check-node layer and the incidence relation of XOR comprises: left side degree distribution vector, the right degree distribution vector of determining bigraph (bipartite graph);
Generate bigraph (bipartite graph) at random between described back end layer and the check-node layer according to described left side degree distribution vector, the right degree distribution vector by the mode of coupling at random, and carry out the incidence relation of XOR between definite described back end layer and the check-node layer according to described bigraph (bipartite graph) at random.
Described data code flow comprises:
The data code flow of the data cell of the data cell of adaptation layer encapsulation Network Based or level of abstraction Network Based encapsulation; And being divided into the step with the back end that pre-determines the back end number according to big young pathbreaker's data code flow of the packet of back end correspondence in the described Tornado code data node layer is specially:
The position piece that the data cell of the adaptation layer Network Based of predetermined number or level of abstraction Network Based encapsulation is formed is divided into back end according to back end size in the back end layer of described Tornado sign indicating number.
The data cell of described adaptation layer Network Based encapsulation comprises: based on the data cell of network adaptation layer encapsulation H.263;
The data cell of described level of abstraction Network Based encapsulation comprises: based on the data cell of network abstract layer encapsulation H.264.
Describedly be divided into step according to big young pathbreaker's data code flow of the packet of back end correspondence in the described Tornado code data node layer and also comprise with the back end that pre-determines the back end number:
When the size of determining institute's rheme piece be the integral multiple of back end size in the back end layer of described Tornado sign indicating number, fill the length of institute's rheme piece, making a piece after the filling is the integral multiple of back end size in the back end layer of described Tornado sign indicating number.
Described method also comprises: the corresponding relation of determining each data type and each transfer of data protection class; According to each transfer of data protection class a plurality of Tornado sign indicating numbers that all have one deck check-node layer and have different check-node numbers are set.
Described method comprises: the data type of determining each data according to the predetermined information of each Data-carrying in the data code flow; Data type, each data type according to described each data are determined the corresponding transfer of data protection class of each data in the described data code flow with the corresponding relation of transfer of data protection class; According to described transfer of data protection class data code flow is divided into corresponding son stream; Determine the corresponding Tornado sign indicating number of each son stream.
Described predetermined information specifically comprises:
Based on the H.264 non-texture information and the texture information of the data cell of network abstract layer.
Description by technique scheme as can be known, the present invention is guaranteeing under the situation that the transfer of data protective capability does not have significantly to descend, by the correcting and eleting codes that only has one deck check-node layer is set, reduced the operand of correcting and eleting codes generation check-node layer, reduced the data transfer delay time, transfer of data protective value and cost ratio are improved, data transmission protection of the present invention can be applicable to H.264 wait new technology; By the data cell of network adaptation layer or network abstract layer encapsulation is carried out cutting apart of back end, make data transmission protection of the present invention can with H.263, H.264 wait technology to obtain good the cooperation; By different types of data being adopted correcting and eleting codes with different protective capabilities, as to the high correcting and eleting codes of important The data redundancy, general data is adopted the low correcting and eleting codes of redundancy, make the present invention realize heavily protections such as non-at different data such as important view data, general image data etc., all kinds of significant datas can be recovered under high packet loss environment as much as possible, make data code flow under the identical situation of the average redundancy rate of correcting and eleting codes, can access maximum transfer of data protection; Thereby realized raising transfer of data protectiveness price ratio, improved data transmission efficiency, promoted H.264 to wait the new technology application aims by technical scheme provided by the invention.
Description of drawings
Fig. 1 is the structural representation of Tornado sign indicating number in the prior art;
Fig. 2 is the structural representation of the improved Tornado sign indicating number of the present invention;
Fig. 3 is the improved Tornado sign indicating number of the present invention and unit matching H.264NAL realizes the schematic diagram of transfer of data protection;
Fig. 4 is the data format schematic diagram of H.264NAL unit.
Embodiment
Adopting the Tornado sign indicating number to carry out in the process of transfer of data protection; the Tornado code check node layer that multilayer is set can strengthen the transfer of data protective capability to a certain extent; but; the Tornado code check node layer that multilayer is set also can make the operand of Tornado sign indicating number big, thereby makes data pay the long cost of time delay in transmitting the protection process.If can guarantee under the situation that the transfer of data protective capability does not have significantly to descend; reduce the number of plies of check-node layer; just can effectively reduce the operand of Tornado sign indicating number, reduce the time delay in the data transmission procedure greatly, thereby seek higher transfer of data protective value-cost ratio.
Therefore, core of the present invention is: the correcting and eleting codes that only has one deck check-node layer is set, carries out the transfer of data protection according to described correcting and eleting codes.
Based on core concept of the present invention technical scheme provided by the invention is further described below.
Correcting and eleting codes of the present invention only has one deck check-node layer, removed the middle check-node layer of Tornado sign indicating number, equally, also removed the nonnegotiable demands that produces last one deck check-node in the Tornado sign indicating number according to the Reed-Solomon coding, like this, correcting and eleting codes of the present invention only has one deck back end layer and one deck check-node layer as shown in Figure 2, we can say that correcting and eleting codes of the present invention is a kind of Tornado sign indicating number of designs simplification, is a kind of improved Tornado sign indicating number.
In the back end of the improved Tornado sign indicating number of the present invention size L1, the back end layer in the number n of back end, the check-node layer check-node number L can come according to the actual requirements to determine.As according to the check-node number L that comprises in the back end number n that comprises in back end size L1, the back end layer in message transmission rate, data type such as voice data/video data etc., data protection Capability Requirement, the factor specified data node layer such as maximum network delay that can receive, the check-node layer.
If the Tornado sign indicating number has the middle check-node layer of m layer in the setting prior art, and from m intermediate layer of back end layer to the, the geometric ratio of the interstitial content between the adjacent two layers is passed the factor that contracts (being used to describe the identical proportionate relationship that contracts of passing on the adjacent two layers interstitial content) and is
, the interstitial content between final layer and the m layer geometric ratio pass the factor that contracts and be
Then total node of Tornado sign indicating number is counted TotalNode and is in the prior art:
Because Total
Node=n+L, therefore, the setting of L is conditional,
L can not set arbitrarily.Owing to need to guarantee that the node number of every node layer in the Tornado sign indicating number all is an integer, therefore need
And
All be integer, this condition is called implicit integer node said conditions.According to this condition, if the m in the given Tornado sign indicating number and
Just can calculate the condition that n need satisfy, as work as m=3,
Then can calculate n=16k, wherein k is any natural number.Hence one can see that, and the minimum value that n can obtain is 16, and the code check r of Tornado sign indicating number is in the prior art:
And redundancy rate 1-r is:
The improved Tornado sign indicating number of the present invention makes improved Tornado sign indicating number no longer need the condition of above-mentioned implicit integer interstitial content owing to there is not middle check-node layer, and the check-node number L of the check-node layer of the improved Tornado sign indicating number of the present invention is:
The geometric ratio of the back end layer of improved Tornado sign indicating number of the present invention and the interstitial content of check-node layer is passed the factor that contracts
Can be provided with arbitrarily, under the condition of given back end number n, L can set flexibly.
The code check r of the improved Tornado sign indicating number of the present invention is:
The redundancy rate 1-r of the improved Tornado sign indicating number of the present invention is:
The improved Tornado sign indicating number of the present invention can be expressed as TN (n+L, n), as TN (30,20), verification interstitial content L=10 in back end number n=20, the check-node layer in the expression back end layer.At this moment, the present invention improved Tornado sign indicating number
And code check r=2/3=66.7%.
Relatively the code check of Tornado sign indicating number, redundancy rate are passed the factor that contracts having identical back end number n and geometric ratio as can be known in code check, redundancy rate and the prior art of the improved Tornado sign indicating number of the present invention
Under the condition, the code check of the improved Tornado sign indicating number of the present invention has increased by 1/6 than the code check of former Tornado sign indicating number, the percentage that improves is: 33%, redundancy rate has reduced than the redundancy rate of former Tornado sign indicating number, and therefore, the efficiency of transmission of the improved Tornado sign indicating number of the present invention has improved.The data transfer delay time that the Tornado sign indicating number of prior art is introduced is 0.5 second at least, and the data transfer delay that improved Tornado sign indicating number is introduced is when video frame rate reaches normal level and is 30fps, minimumly can be 1/15=0.07 second, according to video frame rate is that 8fps calculates, the longest 0.25s that also is no more than of data transfer delay time that improved Tornado sign indicating number is introduced.
After the back end number n of determining the improved Tornado sign indicating number of the present invention, check-node number L, back end size, need to determine to generate the pre-defined algorithm of check-node and the incidence relation of back end layer and check-node layer by back end.The incidence relation of back end layer and check-node layer is the generation which back end has participated in check-node in the check-node layer in the back end layer.
The present invention determines that the incidence relation between Tornado sign indicating number in the method for back end layer and the incidence relation of check-node layer in the improved Tornado sign indicating number and the prior art two-layer is identical, and detailed process is:
Incidence relation between back end layer and the check-node layer is the topological relation of a kind of figure in itself, and this incidence relation can be described with bigraph (bipartite graph) (Bipartite Graph).In branch's " graph theory " (Graph Theory) of discrete mathematics, bigraph (bipartite graph) also is called bigraph, is a kind of special figure.Two node set about this figure is divided into, or two summits (vertex) set about claiming, limit (Edge) is the connection arc between left and right two nodes, the incidence relation between the left and right node is represented on the limit, be present between a pair of node that belongs to left and right sides node set, and do not have the limit between any two nodes in the same node set.
For instance, incidence relation between back end layer and the check-node layer is: if exist related between back end i and the check-node j, be that back end i has participated in the computing that generates check-node j, between back end i and check-node j, have a limit so; Vice versa.If the form according to sufficient and necessary condition can be expressed as the incidence relation between back end i and the check-node j: back end i has participated in the computing that generates check-node j, and and if only if exists a limit between back end i and the check-node j.
Only there is 1 bigraph (bipartite graph) in the improved Tornado sign indicating number of the present invention, i.e. bigraph (bipartite graph) between back end layer and the check-node layer, and have two bigraph (bipartite graph)s in the Tornado sign indicating number of prior art at least.
Because incidence relation is the relation of a kind of multi-to-multi (Many-to-many) in essence, therefore, can there be a plurality of nodes related with it for back end i in the above-mentioned example and check-node j.That is to say that back end i can participate in the generation computing of a plurality of check-nodes in the check-node layer, and check-node j can be generated by a plurality of back end in the back end layer.
According to the term in the graph theory, be called the number of degrees (degree) of this node with a related limit number of node, for the bigraph (bipartite graph) in the improved Tornado sign indicating number of the present invention two degree sequences are arranged: left side degree sequence and the right degree sequence.Left side degree sequence is exactly the sequence that left sibling promptly generates the number of degrees formation of each node in the node set, and right degree sequence is exactly the sequence that right node promptly is generated the number of degrees formation of each node in the node set.
According to the left side degree sequence of node, the degree that the right degree sequence can define the limit, as for limit e, if the degree of the back end i on its left side for 2., and the degree of the check-node j on the right is for 8., left degree that then we can say limit e is for 2., right degree is for 8..
In the improved Tornado sign indicating number of the present invention; the limit that exists in the bigraph (bipartite graph) is many more; incidence relation promptly between two node set is many more; then the transfer of data protective capability is strong more; be the transfer of data protective capability with about incidence relation between two node chances relevant, with concrete which back end and the related no direct relation of which check-node.More strictly speaking, left side degree distribution vector and the right degree distribution vector are key factors of the improved Tornado code data transmission of decision protective capability.
The present invention is after the check-node number of the back end number of determining the back end size of improved Tornado sign indicating number, back end layer, check-node layer, the left side degree distribution vector of the bigraph (bipartite graph) of design data node layer and check-node layer and the right degree distribution vector, and generate the bigraph (bipartite graph) at random of back end layer and check-node layer by the mode of coupling at random, this at random in the bigraph (bipartite graph) limit related with which node be at random, but on macroscopic view, the distribution of limit degree meets by the left side degree distribution vector and the given regularity of distribution of the right degree distribution vector.
The back end layer of the improved Tornado sign indicating number of the present invention and the pre-defined algorithm between the check-node layer are XOR algorithm XOR (eXclusive OR), perhaps also are called mould two and add computing (addition modulo 2).The XOR computing is a kind of bit arithmetic, and the back end of improved Tornado sign indicating number is an equilong binary position piece (BitBlock), and check-node is exactly to carry out the position piece that forms behind the XOR between the corresponding position of position piece of two data nodes.If two length is respectively the position piece of L: A=[a
0, a
1, a
2... .., a
L], B=[b
0, b
1, b
2... .., b
L], then the result behind A and the B XOR is defined as: A/B=[a
0/ b
0, a
1/ b
1, a
2/ b
2...., a
L/ b
L].
Adopt the XOR computing to be because XOR has following mathematical property: for any binary variable a, b has: (a/b)/and b=a.Equally, for any binary digit block variable A=[a
0, a
1, a
2... .., a
L], B=[b
0, b
1, b
2... .., b
L], have: (A/B)/B=A.If A, B are back end, then (A/B) is exactly check-node, like this, in the back end transmission course, A loses when back end, and back end B and check-node (A/B) are received to rectify and really receive, then the receiving terminal back end A that can recover to lose by (A/B)/B=A.
It is a example simple, the most basic that receiving terminal recovers to transmit the back end of losing according to formula (A/B)/B=A, can also construct a plurality of recovery equations of losing node that relate to of a series of complexity more according to formula (A/B)/B=A.All lost such as back end A, B, C, but check-node A/B, A/C, A/B/C are received to rectify really and receive, then receiving terminal can come restore data node A according to formula (A/B)/(A/C)/(A/B/C)=A.
In a word, during back end that receiving terminal recovers to lose in the decode procedure of the improved Tornado sign indicating number according to the present invention, its restore data node principle is: for bigraph (bipartite graph), if there is a right node correctly to be received, and with have only a left sibling to lose in all left siblings that this right side node is associated, so, this left sibling of losing just can by this right node and all left siblings of not losing mutually XOR recover.
In the concrete application in the technology H.264 the data transmission protection based on correcting and eleting codes of the present invention is described with the improved Tornado sign indicating number of the present invention below.
H.264 the video compression coding standard is that ITU-T (International Telecommunications Union) associating ISO/IEC (International Standards Organization/International Electrotechnical Commission) MPEG (Motion Picture Experts Group) International Standards Organization formulates, and H.264 becomes the mainstream standard in the multimedia communication gradually.
Owing to H.264 use multiple high efficient coding algorithm, make video code flow very responsive to channel error code, with the IP network is example, although IP network has adopted a lot of qos policys at bearing bed, still problems such as network bandwidth fluctuation, packet loss, packet delay can frequently occur, in practical video communication, the deteriroation of image quality that the IP network packet loss causes is very serious, to cause the collapse of decoding end system when sometimes or even intolerable, serious.That is to say, H.264 with respect to other video compression coding standard, because its ability is stronger, efficient is higher, and function is abundanter, makes that its ability to bear for the network deletion error is also lower, even single primary mistake also may cause the rapid decline that recovers video quality.
Therefore, in based on video communication H.264, must adopt effective anti-packet loss mistake technology and, guarantee to recover the quality of image in conjunction with the various video anti-error code method.
The present invention has taked the fit step of following two practicalities for effectively cooperating with H.264 waiting technology as much as possible:
Measure one, after the data code flow of exporting behind the video encoder compressed encoding is H.264 packed through NAL (network abstract layer), continuous H.264NAL unit (NAL Unit with predetermined number, abbreviation NALU) is set to a big position piece, as shown in Figure 3, carry out the processes such as generation of the cutting apart of back end, check-node again according to this big position piece, carry out Network Transmission then.Be the present invention when the partition data node, be that realize on the basis with unit H.264NAL.
In the application of reality, for the data length that guarantees this big position piece is the integral multiple of back end size, when the present invention can also be not the integral multiple of back end size at the data length of big position piece, fill this piece, as filling 0 of several number at the afterbody of this big position piece, the data length that makes this piece is the integral multiple of back end size.
H.264NAL be equivalent to a network adaptation layer, can guarantee that thereon data code flow and concrete transmission network are irrelevant, can be fit to the transmission of packing of a lot of concrete procotols by the H.264NAL unit after H.264NAL adaptive.In the same other technologies that exist to H.264NAL similar network adaptation layer,, can be suitable for above-mentioned measure equally as H.263 waiting in the technology.
Measure two, in determining the check-node layer of the improved Tornado sign indicating number of the present invention during the verification interstitial content, it is also conceivable that H.264NAL loaded information in the unit, determine that according to loaded information in the unit H.264NAL it is general data or significant data, should adopt the high improved Tornado sign indicating number of redundancy to significant data, general data is then adopted the relatively low improved Tornado sign indicating number of redundancy.H.264NAL the concrete structure of unit as shown in Figure 4.
In Fig. 4, H.264NAL the unit is made up of NAL header and NAL load.The NAL header has comprised the forbidden_zero_bit of 1 bit, the Nal_ref_idc of 2 bits and the Nal_unit_type of 5 bits, and wherein forbidden_zero_bit always is zero; Nal_unit_type represents the type of NALU, is H.264 defining 12 types altogether in the technology at present; The meaning of Nal_ref_idc is: if the value of Nal_ref_idc is zero, represent that then Slice or Slice data that H.264NAL this deposit non-reference picture in unit cut apart, H.264NAL this can not influence the decoding of its follow-up H.264NAL unit in the unit; If the value of Nal_ref_idc is a non-zero, be that value is 1, represent that then Slice or Slice data that H.264NAL this deposit a sequence/picture parameter set or reference picture in unit cut apart, H.264NAL this can have a strong impact on the decoding of its follow-up H.264NAL unit in the unit.
Therefore; when using the improved Tornado sign indicating number of the present invention that H.264 code stream is carried out the transfer of data protection; at first can video data be divided into two classes according to the value of Nal_ref_idc in the unit H.264NAL: a class is that significance map is as data; the value that is Nal_ref_idc is 1 H.264NAL unit; another kind of is general image data, and promptly the value of Nal_ref_idc is 0 H.264NAL unit.Then, using redundancy higher to significance map as data is that code check is lower, and the improved Tornado sign indicating number that protective capability is strong carries out the transfer of data protection, as using the improved Tornado sign indicating number of TN (30,20); And can use redundancy less to general image data is that code check is higher, and the more weak improved Tornado sign indicating number of protective capability carries out the transfer of data protection, as using the improved Tornado sign indicating number of TN (24,20).
In other technologies; equally can be according to the content in the predetermined information of Data-carrying; come the type of specified data; thereby determine its significance level according to the type of data; then; to the redundancy of the different improvement Tornado sign indicating number of the The data of different significance levels, to realize the non-heavy data transmission protection that waits.
By this non-heavy transfer of data protection algorithm that waits, can guarantee effectively that all kinds of important informations can correctly be recovered with high probability under high packet loss environment, thereby can guarantee the correctness, video image quality etc. of transfer of data as much as possible.
Below at a kind of data type in H.264, the data transmission protection based on correcting and eleting codes provided by the invention is elaborated in the application process in the technology H.264.
In step 1, at first determine the improved Tornado sign indicating number of the present invention TN (M+N, N), wherein: N is the back end number, M is the check-node number.Then, design bigraph (bipartite graph) at random between back end and the check-node.
To step 2, H.264NALU transmitting terminal collects S continuously, H.264NALU form a big position piece with this S, if the length of this big position piece is not the integral multiple of back end length, then need this this big position piece number of fillers, be the integral multiple of back end length, the method for number of fillers as fill at the end of big position piece several continuous 0 etc.Then, transmitting terminal is divided into N the little position piece that length is the L1 bit with this big position piece, as N data node.
The bigraph (bipartite graph) at random that arrive step 3, designs according to step 1 adopts the XOR computing to generate M check-node to N data node.
To step 4, N data node and M check-node are packed according to concrete procotol, and be sent to receiving terminal by network.
Judge all H.264NALU whether all disposing to step 5, transmitting terminal, if all dispose, to step 6; Otherwise, to step 2.
Communication process at step 6, transmitting terminal finishes.
Said process is described transmitting terminal, for receiving terminal, after receiving terminal receives a collection of back end and check-node, at first should judge which back end be receive and in fact lost, and recoverable back end, then, for above-mentioned that lost and recoverable back end according to the recovery of decoding of the general decode procedure of the improved Tornado sign indicating number of the present invention.Receiving terminal repeats above-mentioned reception and recovery process, finishes up to communication process.
When H.264 the present invention is applied in the technology, video code flow should be divided into a plurality of son streams according to data type, as video code flow being divided into two son streams according to the NALU attribute, wherein the NALU of important view data forms a son stream, the NALU of general image data forms a son stream,, adopt redundancy correcting and eleting codes higher, that protective capability is stronger to utilize above-mentioned steps to carry out the transfer of data protection and handle as substream of data for significance map; For general image data stream, adopt redundancy correcting and eleting codes lower, that protective capability is more weak to utilize above-mentioned steps to carry out the transfer of data protection.Thereby, all kinds of significant datas can be recovered under high packet loss environment as much as possible, make data code flow under the identical situation of the average redundancy rate of correcting and eleting codes, can access maximum transfer of data protection.
Show when adopting the improved Tornado sign indicating number of the present invention that data are transmitted protection that below by experiment the protective capability when it transmits protection with respect to available technology adopting Tornado sign indicating number to data aspect protective capability does not significantly descend.
Experiment one: under the same conditions, use the comparison of improved Tornado sign indicating number of the present invention and Tornado sign indicating number of the prior art to the recovery capability of data node.
Setting the improved Tornado sign indicating number of the present invention is TNnew (32,16), promptly has 16 data nodes and total node number and be 32 improved Tornado sign indicating number.The Tornado sign indicating number is number of stories m=3 of TNorg (32,16) and middle verification layer in the setting prior art, and the geometric ratio of the interstitial content of back end layer and check-node layer is passed the factor that contracts
Promptly have 16 data nodes and total node number and be 32 correcting and eleting codes.Because
Therefore, Tornado sign indicating number of the prior art need be divided into 5 layers, and wherein, 1 layer is the back end layer, and 4 layers is the check-node layer.
Under the situation of losing different pieces of information node number, use improved Tornado sign indicating number of the present invention and Tornado sign indicating number of the prior art as shown in table 1 to the recovery probability of data node.
Table 1
| Lose the |
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| TNnew | 100％ | 100％ | 99.9％ | 99.47％ | 98.38％ | 96.17％ | 92.53％ | 86.67％ |
| TNorg | 100％ | 100％ | 100％ | 99.9％ | 99.3％ | 97.7％ | 94.1％ | 87.5％ |
| Lose the node number | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| TNnew | 78.23％ | 67.38％ | 53.94％ | 39.32％ | 25.19％ | 13.41％ | 5.28％ | 1.17％ |
| TNorg | 76.7％ | 62.6％ | 47.4％ | 31.5％ | 18.6％ | 9.3％ | 3.5％ | 1.2％ |
As can be seen from Table 1, under the identical condition of redundancy overhead, promptly have under the condition of identical check-node number and identical data node number at the Tornado of prior art sign indicating number and the improved Tornado sign indicating number of the present invention, use improved Tornado sign indicating number of the present invention and Tornado sign indicating number of the prior art when recovering the back end of losing, both recovery probability differ seldom, as under worst situation, promptly lose 16 data nodes equally, the recovery probability of Tornado sign indicating number of the prior art is 1.2%, and the recovery probability of improved Tornado sign indicating number of the present invention is 1.17%.
This shows; the improved Tornado sign indicating number of the present invention is aspect the transfer of data protective capability; significantly do not descend with respect to prior art; and the present invention improved Tornado sign indicating number is owing to reduced operand that correcting and eleting codes generates the check-node layer, reduced the data transfer delay time; transfer of data protective value and cost ratio are improved, data transmission protection of the present invention can be applicable to H.264 wait new technology.
Because PSNR (Peak Signal-to-Noise Ratio; Y-PSNR) be the importance degree figureofmerit of video image quality, below by the two couples of the present invention of experiment the improved Tornado sign indicating number that adopts same check-node number to significant data in the video image and non-significant data carry out the video Data Transmission protection, PSNR when adopting two kinds of improved Tornado sign indicating numbers with different check node number respectively the significant data in the video image and general data to be carried out the video Data Transmission protection compares.
Experiment two: the improved Tornado sign indicating number of setting single check-node number is TN (28,20), and two kinds of improved Tornado sign indicating numbers with different check node number are TN1 (30,20) and TN2 (26,20).
The average bit rate of the code check of TN (28,20) and TN1 (30,20) and TN2 (26,20) is identical, therefore, adopts these two kinds of strategies that video Data Transmission is protected, and it is identical aspect redundancy overhead.
When testing at the Foreman image sequence, the comparative result of PSNR is as shown in table 2.
Table 2
| Packet loss: | 0％ | 2％ | 4％ | 6％ | 8％ | 10％ | 12％ | 14％ | 16％ |
| PSNR1 | 36.26 | 36.26 | 35.67 | 33.40 | 26.89 | 23.47 | 21.33 | 21.07 | 20.80 |
| PSNR2 | 36.26 | 36.26 | 34.48 | 35.18 | 34.23 | 33.12 | 27.02 | 24.35 | 22.56 |
Wherein: PSNR1 and TN (28,20) correspondence, PSNR2 and TN1 (30,20) and TN2 (26,20) correspondence.
When testing at the Container image sequence, the comparative result of PSNR is as shown in table 3.
Table 3
| Packet loss: | 0％ | 2％ | 4％ | 6％ | 8％ | 10％ | 12％ | 14％ | 16％ |
| PSNR1 | 35.77 | 35.77 | 35.77 | 35.06 | 34.81 | 33.25 | 32.90 | 29.70 | 28.66 |
| PSNR2 | 35.77 | 35.77 | 35.19 | 35.77 | 35.52 | 34.92 | 34.20 | 33.86 | 33.01 |
Wherein: PSNR1 and TN (28,20) correspondence, PSNR2 and TN1 (30,20) and TN2 (26,20) correspondence.
From table 2, table 3, can obviously find out; have at communication network under the environment of identical packet loss; PSNR when carrying out the video Data Transmission protection than the correcting and eleting codes that only adopts a kind of protective capability when adopting the correcting and eleting codes of two kinds of different protective capabilities to carry out the video Data Transmission protection to H.264 significant data and general data obviously improves; and identical aspect redundancy overhead, make the present invention on the transfer of data protective capability, have good advantages.
Though described the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and do not break away from spirit of the present invention, and the claim of application documents of the present invention comprises these distortion and variation.
Claims (10)
1, a kind of data transmission protection based on correcting and eleting codes is characterized in that, comprising:
Big young pathbreaker's data code flow according to the packet of back end correspondence in the Tornado code data node layer is divided into the back end that pre-determines the back end number;
According to the incidence relation of the XOR between described Tornado code data node layer and the check-node layer and at random bigraph (bipartite graph) be that the described back end of cutting apart generates the check-node layer that one deck has the check-node that pre-determines the check-node number;
The check-node of described back end of cutting apart and generation is transferred to receiving terminal;
Described receiving terminal is when determining that transmitting the back end of losing can be resumed, according to the described back end of losing of incidence relation recovery of the check-node of its reception, described bigraph (bipartite graph) at random, described XOR.
2, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 1 is characterized in that, comprises before the described method:
Determine in the size, back end layer of the packet of back end correspondence in the back end layer of described Tornado sign indicating number check-node number in back end number, the check-node layer;
Determine the bigraph (bipartite graph) at random between described back end layer and the check-node layer and the incidence relation of XOR.
3, a kind of data transmission protection as claimed in claim 2 based on correcting and eleting codes; it is characterized in that, determine the back end number that comprises in the size, back end layer of the packet of back end correspondence in the back end layer of described Tornado sign indicating number, the check-node number that the check-node layer comprises according to message transmission rate, data type, data protection Capability Requirement, network delay demand.
4, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 2 is characterized in that, the step of the bigraph (bipartite graph) at random between wherein definite described back end layer and the check-node layer and the incidence relation of XOR comprises:
Determine left side degree distribution vector, the right degree distribution vector of bigraph (bipartite graph);
Generate bigraph (bipartite graph) at random between described back end layer and the check-node layer according to described left side degree distribution vector, the right degree distribution vector by the mode of coupling at random, and carry out the incidence relation of XOR between definite described back end layer and the check-node layer according to described bigraph (bipartite graph) at random.
5, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 1 is characterized in that described data code flow comprises: the data code flow of the data cell of the data cell of adaptation layer encapsulation Network Based or level of abstraction Network Based encapsulation;
And being divided into the step with the back end that pre-determines the back end number according to big young pathbreaker's data code flow of the packet of back end correspondence in the described Tornado code data node layer is specially:
The position piece that the data cell of the adaptation layer Network Based of predetermined number or level of abstraction Network Based encapsulation is formed is divided into back end according to back end size in the back end layer of described Tornado sign indicating number.
6, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 5 is characterized in that:
The data cell of described adaptation layer Network Based encapsulation comprises: based on the data cell of network adaptation layer encapsulation H.263;
The data cell of described level of abstraction Network Based encapsulation comprises: based on the data cell of network abstract layer encapsulation H.264.
7, a kind of data transmission protection as claimed in claim 5 based on correcting and eleting codes; it is characterized in that, describedly be divided into step according to big young pathbreaker's data code flow of the packet of back end correspondence in the described Tornado code data node layer and also comprise with the back end that pre-determines the back end number:
When the size of determining institute's rheme piece be the integral multiple of back end size in the back end layer of described Tornado sign indicating number, fill the length of institute's rheme piece, making a piece after the filling is the integral multiple of back end size in the back end layer of described Tornado sign indicating number.
8, as the described a kind of data transmission protection of the described arbitrary claim of claim 1 to 7, it is characterized in that, also comprise based on correcting and eleting codes:
Determine the corresponding relation of each data type and each transfer of data protection class;
According to each transfer of data protection class a plurality of Tornado sign indicating numbers that all have one deck check-node layer and have different check-node numbers are set.
9, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 8 is characterized in that, also comprises:
Determine the data type of each data according to the predetermined information of each Data-carrying in the data code flow;
Data type, each data type according to described each data are determined the corresponding transfer of data protection class of each data in the described data code flow with the corresponding relation of transfer of data protection class;
According to described transfer of data protection class data code flow is divided into corresponding son stream;
Determine the corresponding Tornado sign indicating number of each son stream.
10, a kind of data transmission protection based on correcting and eleting codes as claimed in claim 9 is characterized in that described predetermined information specifically comprises: based on the H.264 non-texture information and the texture information of the data cell of network abstract layer.
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| CNB2005100661467A CN100446452C (en) | 2005-04-21 | 2005-04-21 | Data transmission protection based on correcting and eleting codes |
| PCT/CN2006/000389 WO2006111063A1 (en) | 2005-04-21 | 2006-03-14 | A method for protecting data transmitting based on erasure codes |
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| US9848209B2 (en) | 2008-04-02 | 2017-12-19 | Microsoft Technology Licensing, Llc | Adaptive error detection for MPEG-2 error concealment |
| US9924184B2 (en) | 2008-06-30 | 2018-03-20 | Microsoft Technology Licensing, Llc | Error detection, protection and recovery for video decoding |
| US9788018B2 (en) | 2008-06-30 | 2017-10-10 | Microsoft Technology Licensing, Llc | Error concealment techniques in video decoding |
| US9131241B2 (en) | 2008-11-25 | 2015-09-08 | Microsoft Technology Licensing, Llc | Adjusting hardware acceleration for video playback based on error detection |
| US8340510B2 (en) | 2009-07-17 | 2012-12-25 | Microsoft Corporation | Implementing channel start and file seek for decoder |
| CN102263606B (en) * | 2010-05-28 | 2014-02-19 | 华为技术有限公司 | Channel data coding and decoding method and device |
| CN102843212B (en) * | 2012-08-03 | 2016-10-26 | 南京中兴新软件有限责任公司 | Coding and decoding processing method and device |
| CN104393960B (en) * | 2014-12-09 | 2017-08-11 | 南京邮电大学 | A kind of satellite network star based on correcting and eleting codes ground multipath method for reliable transmission |
| CN110532126B (en) * | 2019-07-26 | 2020-10-27 | 西安交通大学 | Method and device for rapidly recovering erasure code storage system data and storage medium |
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| H1264 的网络传输适应性解决方案. 马海燕.北京广播学院学报(自然科学版)，第12卷第1期. 2005 |
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