CN103152652B - A kind of video requency frame data network transfer method of encoding based on Cauchy RS - Google Patents

Abstract

The invention discloses a kind of video requency frame data network transfer method of encoding based on Cauchy RS, comprise the following steps: a pre-defined Cauchy RS generator matrix, this Cauchy RS generator matrix is utilized to be after twice Cauchy RS encode to each frame of video, do diagonal angle to multiple video requency frame data packet sequence and once verification packet sequence corresponding to each frame of video to interweave, make sequence of data packet and corresponding once verification packet sequence out of order; After finishing diagonal angle intertexture, packet and verification bag are sent to network, after the receiving terminal of network receives all packets in current video frame group, utilizing the packet that once verification is wrapped or secondary verification is wrapped losing to recover, decoding after the packet recovered and the packet reformulation video data received.The present invention is based on the video requency frame data network transfer method that Cauchy RS encodes, simple to operate, be easy to realize, the video requency frame data bag lost in network transmission process can be recovered expeditiously.

Description

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

Technical field

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

Background technology

In the research of network data transmitting, many achievements are achieved both at home and abroad at present, as automatic retransmission mechanism (ARQ), without the need to the forward error correction coding algorithm (FEC) that retransmits or the realization mechanism in conjunction with autonomous retransmission and forward error correction, wherein the realization of FEC has again multiple method, as Turbo code, Pro-MPEGCoP3 code, Raptor code and RS code etc.

Automatic retransmission mechanism (ARQ) namely needs when receiving terminal detects data-bag lost to send repeat requests to transmitting terminal, and transmitting terminal sends the packet needing to retransmit again according to the repeat requests bag received.Simple on this Method And Principle, but there are problems on realizing, sent at transmitting terminal buffer memory as needed but also do not carry out the packet that confirms, until be identified or need to retransmit; And when being applied to complicated network topology structure (as there is the network environment of multistage route), or when applying to the high time delay high packet loss environment of such as field of deep space communication and so on, data retransmission can introduce larger time delay, and this cannot make us in the video system field that requirement of real-time is higher accepting.

FEC (ForwardErrorCorrection, forward error correction) is a kind of data encoding technique based on mistake and error correction coding, often in the communications field uses it to correct the mistake occurred in communication process.FEC is a kind of loss recovery strategy being well applicable to real-time video application.

Raptor code is the one in FEC coding method, its main thought is the coding method of employing two step, first carries out precoding with traditional correcting and eleting codes to source symbol, generates intermediate symbols, then adopt the LT weakened again to encode to intermediate symbols, finally generate coded identification.Need to do twice computing to source symbol during such realization coding, and twice computing is different computings, implementing can more complicated.

Summary of the invention

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

Based on the video requency frame data network transfer method that Cauchy RS encodes, comprise 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, by compression after video requency frame data be packaged into the sequence of data packet meeting network application-level protocol;

Cauchy's submatrix of Cauchy RS generator matrix described in c, choice of dynamical, utilizes the Cauchy's submatrix selected, and carries out twice Cauchy RS coding obtain corresponding verification bag by a matrix operation to the sequence of data packet of each frame of video;

Described twice Cauchy RS coding comprises:

Sequence of data packet and corresponding Cauchy's submatrix of c-1, each frame of video carry out computing and generate and once verify 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 and corresponding Cauchy's submatrix carry out computing and generate secondary and verify and wrap;

D, all packets in step b sequence of data packet and the once verification bag in step c done to diagonal angle and interweave, to generate after interweaving out of order packet and once verify packet sequence; Carry out diagonal angle when interweaving, packet and once verification wrap in the array that forms, if the end of last column comprises room, then cyclic shift when this room does not participate in diagonal angle intertexture;

E, secondary verified packet sequence, out of order packet and once verify packet sequence and be sent to network;

F, from secondary verification packet sequence, out of order packet and once verify packet sequence described in network reception, according to the inverse process that steps d diagonal angle interweaves, to out of order packet with once verify packet sequence and resequence;

G, according to the packet after described secondary verification packet sequence and rearrangement with once verify packet sequence and judged whether data-bag lost, if there is no data-bag lost, then the packet received is delivered to video decoder decodes; If there is data-bag lost, then, after utilizing once verification bag or secondary verification bag to recover the packet lost, deliver to video decoder decodes together with the packet received.

The data packet recovery concrete operations of losing in described step g are as follows:

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 once verifying bag corresponding to this frame of video of correctly receiving, be then multiplied the packet of this frame of video received with the inverse matrix once verifying the packet sequence Cauchy RS submatrix corresponding with this frame of video that doing once decodes and recover the packet lost;

G-2, for all frame of video in each frame of video group, 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 of correctly receiving in this frame of video group after step g-1, then the inverse matrix of the packet of this frame of video group received and the secondary verification packet sequence Cauchy RS submatrix corresponding with this frame of video group is multiplied and does the packet that decode in two phases recovers to lose.

After step g-1, in each frame of video group, the packet of existing partial loss utilizes once verification bag to recover, secondary corresponding with the frame of video group correctly received for the quantity of the packet not having the loss recovered is verified the quantity of wrapping compare, 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 of correctly receiving, secondary is then utilized to verify the recovery of wrapping and carrying out 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 of correctly receiving, then can not realize the recovery to the packet lost.

Relative to automatic retransmission mechanism, the present invention takes full advantage of the advantage that FEC loss recovery algorithm is applicable to real-time video application, can realize the real-time recovery of lost package under the prerequisite of not carrying out retransmitting.Relative to the FEC loss recovery algorithm of Raptor code and so on, principle of the present invention is simple, and twice coding in algorithm realization process is the computing of same kind, therefore can by once-through operation realize twice coding generate needed for verification packet sequence, realize easily, making full use of the time delay interweaving and introduce, when increasing a small amount of verification bag and time delay, the data packet recovery rate that receiving terminal is lost can be significantly improved.

Accompanying drawing explanation

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

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

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

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 Cauchy RS encode video requency frame data network transfer method, first, by camera collection to video signal by obtaining video requency frame data VF after 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 _nbe twice Cauchy RS to encode; In order to strengthen the recovery rate under continuous data packet loss environment, the present invention is after finishing twice Cauchy RS and encoding to each frame of video, do diagonal angle to multiple video requency frame data packet sequence and once verification packet sequence corresponding to each frame of video to interweave, make sequence of data packet and corresponding once verification packet sequence out of order; After finishing diagonal angle intertexture, packet and verification bag are sent in IP network, after the receiving terminal of network receives all packets in current video frame group, the packet lost is recovered according to deinterleaving and decoding recovery process, finally the packet recovered and the packet received being reformulated one-frame video data sends to decoder to carry out video decompression decoding, and 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 that row m arranges.

B, by compression after video requency frame data be packaged into the sequence of data packet meeting network application-level protocol;

If the data packet sequence of k ' frame video requency frame data composition is classified as S=[S ₁s ₂s _{k '}], wherein S _ithe sequence of data packet S of the i-th frame in frame of video group _i=[s _1is _2is _ki], s _jiit is the jth packet in the i-th frame video requency frame data packet sequence.

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

Wherein, E _kik _irank unit matrix, k _ithe quantity of the packet comprised in corresponding i-th frame frame of video.

According to the quantity of the packet that every frame frame of video comprises, in Cauchy RS generator matrix, choose the corresponding submatrix of size, i.e. k during each computing ₁, k ₂k _{k '}different.

When supposing that carrying out first time Cauchy RS encodes, the once verification bag number of the data packet sequence column-generation of every frame frame of video is m ₁, when carrying out 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 is the total amount of byte in m data bag) and represent the n-th byte of m data bag in the i-th frame frame of video, with (b` _mn) _i(1≤m≤m1,1≤n≤M ', M ' be m the total amount of byte once verifying in bag) represent individual the n-th byte once verifying bag of m in the i-th 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 comprised in each frame of video group, in Cauchy RS generator matrix, choose the corresponding submatrix of size, use the secondary verification packet sequence obtained after representing secondary coding, the n-th 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 obtained during secondary coding ₁individual bag directly can be obtained by XOR by the once verification packet sequence of frame video requency frame data bag every during first encoding, therefore, in algorithm realization process, only need to do just can obtain encoding the once verification bag of needs and the secondary verification of matrix multiplication operation wrap.

D, all packets in step b sequence of data packet and the once verification bag in step c done to diagonal angle and interweave, to generate after interweaving out of order packet and once verify packet sequence; Carry out diagonal angle when interweaving, packet and once verification wrap in the array that forms, if the end of last column comprises room, then cyclic shift when this room does not participate in diagonal angle intertexture;

Diagonal angle of the present invention interweaves as shown in Figure 2, specifying all packets and once verifying the columns wrapping the array lined up is L, by all packets and once verify bag (packet and once verification bag add up to N, the corresponding packet of element in each frame in figure or one once verify bag) order writes successively, then and complete line number is R _f=N/L, if N is the integral multiple of L, so N number of packet and once verification bag just form a R _fthe array of × L, if N is not the integral multiple of L, so also there is the incomplete row of a line (namely last column comprises room), its element number comprised is L _r=NmodL.

When diagonal angle interweaves, first row element position is constant, the relative first row circulation of each element of secondary series moves one, the relative first row circulation of each element of 3rd row moves two, the like, to the last row, namely the relative first row circulation of each element in jth row moves (j-1) position, above-mentioned when being respectively listed in cyclic shift, if column element comprises the room of last incompleteline, then this room does not participate in the cyclic shift of element, is sequentially read by time verification bag of the packet unification after N number of rearrangement, namely completes intertexture.

E, secondary verified packet sequence, out of order packet and once verify packet sequence and be sent to network;

F, from secondary verification packet sequence, out of order packet and once verify packet sequence described in network reception, according to the inverse process that steps d diagonal angle interweaves, to out of order packet with once verify packet sequence and resequence;

G, as shown in Figure 3, according to the packet after described secondary verification packet sequence and rearrangement and once verification packet sequence judged whether data-bag lost, if there is no data-bag lost, then the packet received is delivered to video decoder decodes; If there is data-bag lost, then, after recovering the packet lost by the following method, deliver to video decoder decodes together with the packet received, the data packet recovery concrete operations of loss are as follows:

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 once verifying bag corresponding to this frame of video of correctly receiving, then by the packet of this frame of video received with once verify packet sequence and to be multiplied with the inverse matrix of Cauchy RS submatrix that doing once decodes and to recover the packet lost;

G-2, for all frame of video in each frame of video group, 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 of correctly receiving in this frame of video group after step g-1, then the packet of this frame of video group received and secondary verification packet sequence is multiplied with the inverse matrix of Cauchy RS submatrix and does the packet that decode in two phases recovers to lose.

Matrix computational approach during recovery data packets is as follows:

Supposing the packet that receives and once verifying packet sequence is R=[s ₁s ₂s _is _js _kf ₁f ₂f _if _m], wherein S '=[s ₁s ₂s _is _js _k] be packet, F '=[f ₁f ₂f _if _m] once verification bag corresponding to packet, assumed lost s _i, s _jtwo packets and a fi once verify bag, fill 0, so S '=[s in the position of lost data packets ₁s ₂0 _i0 _js _k], F '=[f ₁f ₂0 _if _m].

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

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

So S "=F '-S ' C ' be exactly lose two packet s _iand s _jtwo bags obtaining of each byte XOR, owing to lost i-th packet in packet and a jth packet, get Matrix C ' in the i-th row and jth row form new matrix:

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

Two packets then lost are S _l=[s _is _j]=S " C " ^-1.

Claims (3)

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

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

B, by compression after video requency frame data be packaged into the sequence of data packet meeting network application-level protocol;

C, the number-of-packet comprised according to every frame frame of video, Cauchy's submatrix of the corresponding described Cauchy RS generator matrix of choice of dynamical size, utilize the Cauchy's submatrix selected, by a matrix operation, twice Cauchy RS coding is carried out to the sequence of data packet of each frame of video and obtain corresponding verification bag;

Described twice Cauchy RS coding comprises:

Sequence of data packet and corresponding Cauchy's submatrix of c-1, each frame of video carry out computing and generate and once verify 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 and corresponding Cauchy's submatrix carry out computing and generate secondary and verify and wrap;

D, all packets in step b sequence of data packet and the once verification bag in step c done to diagonal angle and interweave, to generate after interweaving out of order packet and once verify packet sequence;

E, secondary verified packet sequence, out of order packet and once verify packet sequence and be sent to network;

F, from secondary verification packet sequence, out of order packet and once verify packet sequence described in network reception, according to the inverse process that steps d diagonal angle interweaves, to out of order packet with once verify packet sequence and resequence;

G, according to the packet after described secondary verification packet sequence and rearrangement with once verify packet sequence and judged whether data-bag lost, if there is no data-bag lost, then the packet received is delivered to video decoder decodes; If there is data-bag lost, then, after utilizing once verification bag or secondary verification bag to recover the packet lost, deliver to video decoder decodes together with the packet received.

2. as claimed in claim 1 based on the video requency frame data network transfer method that Cauchy RS encodes, it is characterized in that, when carrying out diagonal angle intertexture in described steps d, packet and once verification wrap in the array that forms, if the end of last column comprises room, then this room does not participate in cyclic shift when diagonal angle interweaves.

3., as claimed in claim 1 based on the video requency frame data network transfer method that Cauchy RS encodes, it is characterized in that, the data packet recovery concrete operations of losing in described step g are as follows:

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 once verifying bag corresponding to this frame of video of correctly receiving, be then multiplied the packet of this frame of video received with the inverse matrix once verifying the packet sequence Cauchy RS submatrix corresponding with this frame of video that doing once decodes and recover the packet lost;

G-2, for all frame of video in each frame of video group, 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 of correctly receiving in this frame of video group after step g-1, then the packet of this frame of video group received and secondary verification packet sequence is multiplied with the inverse matrix of Cauchy RS submatrix and does the packet that decode in two phases recovers to lose.