CN103152652A - Video frame data network transmission method based on Cauchy reed-solomon (RS) code - Google Patents

Abstract

The invention discloses a video frame data network transmission method based on a Cauchy reed-solomon (RS) code, and the method comprises the steps of previously defining a Cauchy RS generation matrix, utilizing the Cauchy RS generation matrix to conduct twice Cauchy RS coding on each video frame, then diagonally intertwining multiple video frame data packet sequences and a primary verifying packet sequence corresponding to each video frame, and enabling the data packet sequence and the corresponding primary verifying packet sequence to be disordered; and after the diagonal intertwining, transmitting the data packet and the verifying packet to the network, after all data packets in the current video frame group are received by a receiving end of the network, restoring a lost data packet by utilizing a primary verifying packet or a secondary verifying packet, and regrouping the restored data packet and the received data packet into video data to be decoded. The video frame data network transmission method based on the Cauchy reed-solomon (RS) code is simple to operate, easy to realize and capable of high efficiently restoring the lost video frame data packet in the network transmission process.

Description

A kind of video requency frame data network transfer method based on Cauchy RS coding

Technical field

The present invention relates to the audio-video frequency data network transmission field, be specifically related to a kind of video requency frame data network transfer method based on Cauchy RS coding.

Background technology

Obtaining many achievements aspect the research of network data transmitting both at home and abroad at present, as automatic retransmission mechanism (ARQ), the forward error correction coding algorithm (FEC) that need not to retransmit or in conjunction with the realization mechanism of autonomous retransmission and forward error correction, wherein the realization of FEC has again several different methods, as Turbo code, Pro-MPEG CoP3 code, Raptor code and RS code etc.

Automatic retransmission mechanism (ARQ) namely need to send repeat requests to transmitting terminal when receiving terminal detects data-bag lost, transmitting terminal sends according to the repeat requests bag that receives the packet that needs retransmit again.Simple on this Method And Principle, but have problems on realizing, as need to the transmitting terminal buffer memory sent but the packet also confirmed maybe need to retransmit until be identified; And when being applied to complicated network topology structure (as there being the network environment of multistage route), when perhaps applying to the height time-delay high packet loss environment such as the deep space communication field, data retransmission can be introduced larger time-delay, and this can't make us accepting in requirement of real-time higher video system field.

FEC (Forward Error Correction, forward error correction) is a kind of data encoding technique based on mistake and error correction coding, often uses it that the mistake that occurs in communication process is corrected in the communications field.FEC is a kind of loss recovery strategy that real-time video is used that well is applicable to.

The Raptor code is a kind of in the FEC coding method, its main thought is to adopt two step coding methods, at first with traditional correcting and eleting codes, the source symbol is carried out precoding, generates intermediate symbols, then adopt the LT that weakens again to encode to middle symbol, finally generate coded identification.Need to do twice computing to the source symbol when realizing like this coding, and twice computing be different computings, implementing can more complicated.

Summary of the invention

The invention provides a kind of video requency frame data network transfer method based on Cauchy RS coding, simple to operate, be easy to realize, can recover expeditiously the video requency frame data bag of losing in network transmission process.

A kind of video requency frame data network transfer method based on Cauchy RS coding comprises the following steps:

A, a pre-defined Cauchy RS generator matrix; The line number of this Cauchy RS generator matrix is greater than the number-of-packet of each frame frame of video;

B, the video requency frame data after compressing are packaged into the sequence of data packet that meets network application-level protocol;

Cauchy's submatrix of c, the described Cauchy RS of choice of dynamical generator matrix utilizes the Cauchy's submatrix select, by a matrix operation, the sequence of data packet of each frame of video is carried out twice Cauchy RS coding and obtains corresponding verification bag;

Described twice Cauchy RS coding comprises:

The sequence of data packet of c-1, each frame of video carries out computing with corresponding Cauchy's submatrix and generates a verification bag;

C-2, all frame of video are divided into some frame of video groups, all sequence of data packet in each frame of video group carry out computing with corresponding Cauchy's submatrix and generate secondary verification bag;

D, a verification bag in all packets in step b sequence of data packet and step c is done the diagonal angle interweave, generate interweave rear out of order packet and a verification packet sequence; Carry out the diagonal angle when interweaving, in the array that packet and verification bag consist of, if the end of last column comprises the room, the cyclic shift when this room does not participate in the diagonal angle and interweaves;

E, secondary verification packet sequence, out of order packet and verification packet sequence are sent to network;

F, receive described secondary verification packet sequence, out of order packet and a verification packet sequence from network, the inverse process that interweaves according to the steps d diagonal angle is to out of order packet and a verification packet sequence rearrangement;

G, according to described secondary verification packet sequence and the rearrangement after packet and a verification packet sequence judged whether data-bag lost, if there is no data-bag lost, the packet that receives is delivered to video decoder decodes; If data-bag lost is arranged, after utilizing verification bag or secondary verification bag that the missing data bag is recovered, deliver to video decoder decodes together with the packet that receives.

It is as follows that in described step g, the missing data bag recovers concrete operations:

G-1, for each frame of video in each frame of video group, if the data-bag lost quantity of this frame of video is less than or equal to the quantity of a verification bag corresponding to this frame of video that correctly receives, the inverse matrix of the Cauchy RS submatrix that the packet of this frame of video that will receive and verification packet sequence are corresponding with this frame of video multiplies each other and doing once that decoding recovers the missing data bag;

G-2, for all frame of video in each frame of video group, if through in this frame of video group behind step g-1, still unrecovered data-bag lost quantity is less than or equal to the quantity of secondary verification bag corresponding to this frame of video group that correctly receives, the inverse matrix of the Cauchy RS submatrix that the packet of this frame of video group that will receive and secondary verification packet sequence are corresponding with this frame of video group multiplies each other and makees secondary decoding recovery missing data bag.

through behind step g-1, in each frame of video group, the packet of existing partial loss utilizes a verification bag to recover, the quantity of secondary verification bag that will be corresponding with the frame of video group that correctly receives less than the quantity of the missing data bag that recovers compares, if still unrecovered data-bag lost quantity is less than or equal to the quantity of secondary verification bag corresponding to this frame of video group that correctly receives, utilize secondary verification bag to carry out the recovery of lost data packets, if still unrecovered data-bag lost quantity is greater than the quantity of secondary verification bag corresponding to this frame of video group that correctly receives, can not realize the recovery to the missing data bag.

With respect to automatic retransmission mechanism, the present invention takes full advantage of FEC loss recovery algorithm and is applicable to the advantage that real-time video is used, and can realize the real-time recovery of lost package under the prerequisite that does not retransmit.FEC loss recovery algorithm with respect to Raptor code and so on, principle of the present invention is simple, and twice coding in the algorithm implementation procedure is the computing of same kind, therefore can realize that twice coding generates required verification packet sequence by once-through operation, realize easily, take full advantage of the time-delay that interweaves and introduce, in the situation that increase a small amount of verification bag and time-delay, can obviously improve receiving terminal missing data bag recovery rate.

Description of drawings

Fig. 1 is the video requency frame data network transfer method schematic flow sheet that the present invention is based on Cauchy RS coding;

Fig. 2 is the video requency frame data network transfer method diagonal angle that the present invention is based on Cauchy RS coding schematic diagram when interweaving;

Fig. 3 the present invention is based on lost data packets recovery process flow chart in the video requency frame data network transfer method of Cauchy RS coding.

Embodiment

Below in conjunction with accompanying drawing, the video requency frame data network transfer method that the present invention is based on Cauchy RS coding is described in detail.

As shown in Figure 1, based on the video requency frame data network transfer method of Cauchy RS coding, at first, with camera collection to video signal obtain video requency frame data VF after by video encoding and decoding standard (as H.264) compression coding _n, be packaged into sequence of data packet S through network application-level protocol _n=[s ₁s ₂S _k]; Then to S _nDo Cauchy RS coding twice; In order to strengthen the recovery rate under continuous data packet loss environment, the present invention is after finishing twice Cauchy RS coding to each frame of video, a plurality of video requency frame data packet sequences and a verification packet sequence corresponding to each frame of video are done the diagonal angle interweave, make a verification packet sequence of sequence of data packet and correspondence out of order; After finishing the diagonal angle and interweaving, packet and verification bag are sent on IP network, after the receiving terminal of network receives all packets in the current video frame group, recover the missing data bag according to deinterleaving and decoding recovery process, send to decoder to carry out the video decompression decoding packet that recovers and the packet that receives reformulation one-frame video data at last, the specific implementation process is as follows:

A, a pre-defined Cauchy RS generator matrix are as follows, and the line number of this Cauchy RS generator matrix is greater than the number-of-packet of each frame frame of video;

This Cauchy RS generator matrix is a finite field gf (2 ^P) on The Cauchy matrix of row m row.

B, the video requency frame data after compressing are packaged into the sequence of data packet that meets network application-level protocol;

If the data packet sequence that k ' frame video requency frame data forms is classified S=[S as ₁S ₂S _k’], S wherein _iThe sequence of data packet S of i frame in the frame of video group _i=[s _1is _2iS _ki], s _jiBe j packet in i frame video requency frame data packet sequence.

Cauchy's submatrix of c, the described Cauchy RS of choice of dynamical generator matrix utilizes the Cauchy's submatrix select, by a matrix operation, the sequence of data packet of each frame of video is carried out twice Cauchy RS coding and obtains corresponding verification bag, and matrix operation is as follows;

Wherein, E _kiK _iThe rank unit matrix, k _iThe quantity of the packet that comprises in corresponding i frame frame of video.

The quantity of the packet that comprises according to every frame frame of video is chosen the corresponding submatrix of size, i.e. k during each computing in Cauchy RS generator matrix ₁, k ₂K _k’Different.

When supposing to carry out for the first time Cauchy RS coding, a verification bag number of the data packet sequence column-generation of every frame frame of video is m ₁, when carrying out for the second time Cauchy RS coding, the secondary verification bag number that the sequence of data packet group of the individual frame of video of k ' generates is m ₂

Make m ₂〉=m ₁, m=max (m ₁, m ₂)=m ₂, with (b _mn) _i(1≤m≤k _i, 1≤n≤M, M are the total amount of byte in m packet) and n byte of m packet in expression i frame frame of video, use (b` _mn) _iN byte of a m verification bag in (1≤m≤m1,1≤n≤M ', M ' they are m the total amount of byte in a verification bag) expression i frame frame of video, so

${\left(b_{\mathrm{mn}}^{`}\right)}_1={\left(b_{1n}\right)}_1{c}_{1m}\⊕{\left(b_{2n}\right)}_1{c}_{2m}\⊕\·\·\·\⊕{\left(b_{k_{1}n}\right)}_1{c}_{k_{1}m}$

${\left(b_{\mathrm{mn}}^{`}\right)}_2={\left(b_{1n}\right)}_2{c}_{(k_1+1)m}\⊕{\left(b_{2n}\right)}_2{c}_{(k_1+2)m}\⊕\·\·\·\⊕{\left(b_{k_{2}n}\right)}_2{c}_{(k_1+k_2)m}$

…,1≤m≤m ₁

${\left(b_{\mathrm{mn}}^{`}\right)}_{k^{\′}}={\left(b_{1n}\right)}_{k^{\′}}{c}_{(\left(\underset{l=1}{\overset{k^{\′}-1}{\mathrm{\Σ}}}{k}_l\right)+1)m}\⊕{\left(b_{2n}\right)}_{k^{\′}}{c}_{(\left(\underset{l=1}{\overset{k^{\′}-1}{\mathrm{\Σ}}}{k}_l\right)+2)m}\⊕\·\·\·\⊕{\left(b_{k_{k^{\′}}n}\right)}_{k^{\′}}{c}_{(\left(\underset{l=1}{\overset{k^{\′}-1}{\mathrm{\Σ}}}{k}_l\right)+k^{\′})m}$

According to the quantity of the packet that comprises in each frame of video group, choose the corresponding submatrix of size in Cauchy RS generator matrix, use

The secondary verification packet sequence that obtains after the expression secondary coding, n byte of m secondary verification bag, so:

$b_{\mathrm{mn}}^{`}={\left(b_{1n}\right)}_1{c}_{1m}\⊕\·\·\·\⊕{\left(b_{k_{1}n}\right)}_1{c}_{k_{1}m}\⊕{\left(b_{1n}\right)}_2{c}_{(k_1+1)m}\⊕\·\·\·\⊕{\left(b_{k_{2}n}\right)}_2{c}_{(k_1+k_2)m}\⊕\·\·\·$

$\⊕{\left(b_{1n}\right)}_{k^{\′}}{c}_{(\left(\underset{l=1}{\overset{k^{\′}-1}{\mathrm{\Σ}}}{k}_l\right)+1)m}\⊕\·\·\·\⊕{\left(b_{k_{k^{\′}}n}\right)}_{k^{\′}}{c}_{(\left(\underset{l=1}{\overset{k^{\′}-1}{\mathrm{\Σ}}}{k}_l\right)+k^{\′})m},1\≤m\≤m_2$

$=\left\{\begin{array}{c}{\left(b_{\mathrm{mn}}^{`}\right)}_{k_1}\&CirclePlus;{\left(b_{\mathrm{mn}}^{`}\right)}_{k_2}\&CirclePlus;\&CenterDot;\&CenterDot;\&CenterDot;\&CirclePlus;{\left(b_{\mathrm{mn}}^{`}\right)}_{k_{k^{\&prime;}}},1\&le;m\&le;m_1\\ {\left(b_{1n}\right)}_1{c}_{1i}\&CirclePlus;{\left(b_{2n}\right)}_1{c}_{2m}\&CirclePlus;\&CenterDot;\&CenterDot;\&CenterDot;\&CirclePlus;{\left(b_{k_{k^{\&prime;}}n}\right)}_{k^{\&prime;}}{c}_{(\left(\underset{l=1}{\overset{k^{\&prime;}-1}{\mathrm{\&Sigma;}}}{k}_l\right)+k^{\&prime;})m},m_1<m\&le;m_2\end{array}\right.$

According to above-mentioned formula, the front m of the secondary verification packet sequence that obtains during secondary coding ₁When individual bag can be by first encoding, a verification packet sequence of every frame video requency frame data bag directly obtains by XOR, therefore, only need to do matrix multiplication operation just can obtain encoding verification bag and the secondary verification bag of needs in the algorithm implementation procedure.

D, a verification bag in all packets in step b sequence of data packet and step c is done the diagonal angle interweave, generate interweave rear out of order packet and a verification packet sequence; Carry out the diagonal angle when interweaving, in the array that packet and verification bag consist of, if the end of last column comprises the room, the cyclic shift when this room does not participate in the diagonal angle and interweaves;

Diagonal angle of the present invention interweaves as shown in Figure 2, the columns of stipulating the array that all packets and verification bag are lined up is L, with all packets and verification bag (packet and a verification bag add up to N, the corresponding packet of element in each frame in figure or a verification bag) sequentially write successively, complete line number is R _f=N/L, if N is the integral multiple of L, N packet and a verification bag just consist of a R so _fIf N is not the integral multiple of L, so also there is the incomplete row of delegation (being that last column comprises the room) in the array of * L, and its element number that comprises is L _r=NmodL.

When the diagonal angle interweaves, the first row element position is constant, move one in the relative first row circulation of each element of secondary series, move two in the 3rd relative first row circulation of each element of row, the like, to the last one be listed as, move (j-1) position in the i.e. relative first row circulation of each element in the j row, above-mentioned when respectively being listed in cyclic shift, if column element comprises the room of last incompleteline, this room does not participate in the cyclic shift of element, and the packet unification time verification bag after N is reset calls over, and namely completes to interweave.

E, secondary verification packet sequence, out of order packet and verification packet sequence are sent to network;

F, receive described secondary verification packet sequence, out of order packet and a verification packet sequence from network, the inverse process that interweaves according to the steps d diagonal angle is to out of order packet and a verification packet sequence rearrangement;

G, has as shown in Figure 3 judged whether data-bag lost according to packet and a verification packet sequence after described secondary verification packet sequence and rearrangement, if there is no data-bag lost, the packet that receives is delivered to video decoder decodes; If data-bag lost is arranged, after by the following method the missing data bag being recovered, deliver to video decoder decodes together with the packet that receives, it is as follows that the missing data bag recovers concrete operations:

G-1, for each frame of video in each frame of video group, if the data-bag lost quantity of this frame of video is less than or equal to the quantity of a verification bag corresponding to this frame of video that correctly receives, the inverse matrix of the packet of this frame of video that will receive and verification packet sequence and Cauchy RS submatrix multiplies each other and doing once that decoding recovers the missing data bag;

G-2, for all frame of video in each frame of video group, if through in this frame of video group behind step g-1, still unrecovered data-bag lost quantity is less than or equal to the quantity of secondary verification bag corresponding to this frame of video group that correctly receives, the inverse matrix of the packet of this frame of video group that will receive and secondary verification packet sequence and Cauchy RS submatrix multiplies each other and makees secondary decoding recovery missing data bag.

Matrix computations method during recovery data packets is as follows:

Suppose that packet and a verification packet sequence of receiving are R=[s ₁s ₂S _iS _jS _kf ₁f ₂F _iF _m], S '=[s wherein ₁s ₂S _iS _jS _k] be packet, F '=[f ₁f ₂F _iF _m] be the corresponding verification bag of packet, assumed lost s _i, s _jTwo packets and verification bag of a fi fill 0 in the position of lost data packets, so S '=[s ₁s ₂0 _i0 _jS _k], F '=[f ₁f ₂0 _iF _m].

Owing to only losing two packets, data-bag lost quantity less than the quantity of a verification bag corresponding to this frame of video (2＜m), therefore, appoint from a verification packet sequence and get two verification bags that correctly receive, might as well get f ₁And f ₂, the first two columns in corresponding Cauchy RS matrix:

$C^{\&prime;}=\left[\begin{array}{cc}{c}_{11}& c_{12}\\ c_{21}& c_{22}\\ \&CenterDot;& \&CenterDot;\\ \&CenterDot;& \&CenterDot;\\ \&CenterDot;& \&CenterDot;\\ c_{k1}& c_{k2}\end{array}\right]$

S so "=F '-S ' C ' is exactly two packet s that lose _iAnd s _jTwo bags obtaining of each byte XOR, owing to having lost i packet and j the packet in the packet, get Matrix C ' in the capable and j of i capablely consist of new matrix:

$C^{\&prime;\&prime;}=\left[\begin{array}{cc}{c}_{i1}& c_{i2}\\ c_{j1}& c_{j2}\end{array}\right]$

Two packets losing are S _L=[s _is _j]=S " C " ^-1

Claims (4)

1. the video requency frame data network transfer method based on Cauchy RS coding, is characterized in that, comprises the following steps:

A, a pre-defined Cauchy RS generator matrix;

B, the video requency frame data after compressing are packaged into the sequence of data packet that meets network application-level protocol;

Cauchy's submatrix of c, the described Cauchy RS of choice of dynamical generator matrix utilizes the Cauchy's submatrix select, by a matrix operation, the sequence of data packet of each frame of video is carried out twice Cauchy RS coding and obtains corresponding verification bag;

Described twice Cauchy RS coding comprises:

The sequence of data packet of c-1, each frame of video carries out computing with corresponding Cauchy's submatrix and generates a verification bag;

C-2, all frame of video are divided into some frame of video groups, all sequence of data packet in each frame of video group carry out computing with corresponding Cauchy's submatrix and generate secondary verification bag;

D, a verification bag in all packets in step b sequence of data packet and step c is done the diagonal angle interweave, generate interweave rear out of order packet and a verification packet sequence;

E, secondary verification packet sequence, out of order packet and verification packet sequence are sent to network;

F, receive described secondary verification packet sequence, out of order packet and a verification packet sequence from network, the inverse process that interweaves according to the steps d diagonal angle is to out of order packet and a verification packet sequence rearrangement;

G, according to described secondary verification packet sequence and the rearrangement after packet and a verification packet sequence judged whether data-bag lost, if there is no data-bag lost, the packet that receives is delivered to video decoder decodes; If data-bag lost is arranged, after utilizing verification bag or secondary verification bag that the missing data bag is recovered, deliver to video decoder decodes together with the packet that receives.

2. the video requency frame data network transfer method based on Cauchy RS coding as claimed in claim 1, is characterized in that, the line number of the Cauchy RS generator matrix that defines in described step a is greater than the number-of-packet of each frame frame of video.

3. the video requency frame data network transfer method based on Cauchy RS coding as claimed in claim 1, it is characterized in that, carry out the diagonal angle in described steps d when interweaving, in the array that packet and verification bag consist of, if the end of last column comprises the room, the cyclic shift when this room does not participate in the diagonal angle and interweaves.

4. the video requency frame data network transfer method based on Cauchy RS coding as claimed in claim 1, is characterized in that, it is as follows that in described step g, the missing data bag recovers concrete operations:

G-1, for each frame of video in each frame of video group, if the data-bag lost quantity of this frame of video is less than or equal to the quantity of a verification bag corresponding to this frame of video that correctly receives, the inverse matrix of the Cauchy RS submatrix that the packet of this frame of video that will receive and verification packet sequence are corresponding with this frame of video multiplies each other and doing once that decoding recovers the missing data bag;

G-2, for all frame of video in each frame of video group, if through in this frame of video group behind step g-1, still unrecovered data-bag lost quantity is less than or equal to the quantity of secondary verification bag corresponding to this frame of video group that correctly receives, the inverse matrix of the packet of this frame of video group that will receive and secondary verification packet sequence and Cauchy RS submatrix multiplies each other and makees secondary decoding recovery missing data bag.

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