CN113784139B - Pseudo-analog channel coding method and device based on two-dimensional chaotic coding - Google Patents
Pseudo-analog channel coding method and device based on two-dimensional chaotic coding Download PDFInfo
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Abstract
The invention relates to a pseudo-analog channel coding method and device based on two-dimensional chaotic coding, which specifically comprises the following steps: s1, a transmitting end acquires video pixel data to be transmitted, performs 3D-DCT operation on the video pixel data to obtain 3D-DCT coefficients and performs standardization processing; s2, performing coding protection by adopting two-dimensional chaotic coding on a low-frequency data part in the 3D-DCT coefficient, transmitting a high-frequency data part according to an original SoftCast, performing power distribution and whitening operation on data needing to be transmitted, and transmitting the data to a receiving end; s3, the receiving end carries out LLSE decoding according to the received data, then carries out data recovery on the coded low-frequency data part by using two-dimensional chaotic decoding, carries out inverse DCT operation according to the 3D-DCT coefficient obtained by decoding, and then carries out arrangement according to the sequence of each pixel block in video pixel data to obtain a reconstructed video. Compared with the prior art, the invention has the advantages of obviously improving the utilization capacity of bandwidth and the like under the condition of low signal to noise ratio.
Description
Technical Field
The invention relates to the field of pseudo-analog video transmission and analog channel coding, in particular to a pseudo-analog channel coding method and device based on two-dimensional chaotic coding.
Background
The traditional digital video transmission mode has the problem of cliff effect, and cannot adapt to the user requirements of different channel qualities in a multicast scene. In order to solve the "cliff effect" problem in digital video transmission, foreign research proposes a pseudo-analog video transmission scheme SoftCast. At the transmitting end, pseudo-analog video transmission schemes use decorrelation, power allocation and whitening instead of source coding and channel coding in digital video transmission. At the receiving end, the pseudo-analog video transmission scheme employs LLSE (Linear Least Square Estimator) coding to replace channel decoding and source decoding in digital video transmission. Because the transformations to the source in the pseudo-analog video transmission scheme are linear, the reconstructed video signal is linear with the noise signal. Therefore, the pseudo-analog video transmission mode has self-adaptability to the channel and can eliminate the cliff effect.
The hybrid digital-analog transmission mode still needs to rely on the data transmitted by the digital video and is affected by the cliff effect in the digital video transmission. In addition, improvements to the pseudo-analog video transmission scheme itself have focused mainly on the processing of video source data and the application of different scenarios. But currently, there is less research associated with improving SoftCast from the analog channel coding perspective.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a pseudo-analog channel coding method and device based on two-dimensional chaotic coding, which improve the bandwidth utilization capability of a pseudo-analog video transmission mode SoftCast from the aspect of analog channel coding.
The aim of the invention can be achieved by the following technical scheme:
a pseudo-analog channel coding method based on two-dimensional chaotic coding specifically comprises the following steps:
s1, a transmitting end acquires video pixel data to be transmitted, performs 3D-DCT operation on the video pixel data to obtain 3D-DCT coefficients and performs standardization processing;
s2, performing coding protection by adopting two-dimensional chaotic coding on a low-frequency data part in the 3D-DCT coefficient, transmitting a high-frequency data part according to an original SoftCast, performing power distribution and whitening operation on data needing to be transmitted, and transmitting the data to a receiving end;
s3, the receiving end carries out LLSE decoding according to the received data, then carries out data recovery on the coded low-frequency data part by using two-dimensional chaotic decoding, carries out inverse DCT operation according to the 3D-DCT coefficient obtained by decoding, and then carries out arrangement according to the sequence of each pixel block in video pixel data to obtain a reconstructed video.
The specific process of two-dimensional chaotic coding in the step S2 is to take the initial state of the chaotic system as a data information source, evolve a new state from the chaotic system, take the newly generated state as coding data, and carry out coding protection on the analog real-value signal transmitted by the SoftCast, thereby improving the utilization capacity of bandwidth.
Further, the pseudo-analog channel coding based on the two-dimensional chaotic coding can be combined with a pseudo-analog video transmission mode SoftCast to complete wireless video transmission, and a framework of a video transmission system required for completing wireless video transmission comprises a transmitting end pseudo-analog channel coding part and a receiving end pseudo-analog channel decoding part.
In the step S2, the two-dimensional chaotic coding adopts an improved Single-Input Baker' S analog coding algorithm, and the specific formula is as follows:
wherein max_v is the maximum value of the absolute value of the 3D-DCT coefficient, sign () is the sign function, x n and yn For the current two-dimensional input data value, x n+1 and yn+1 For redundant data generated by the current two-dimensional input data value, a chaotic function tent map data sequence x is formed 0 ,x 1 ,...,x N-1 And chaos function inverse function data sequence y 0 ,y 1 ,...,y N-1 ，x 0 and y0 For the same original data, N represents the length of the data sequence.
Further, the chaotic function data sequence and the chaotic function inverse function data sequence are combined to form a simulation coding data sequence x of the low-frequency data part 1-N ,x 2-N ,...,x 0 ,x 0 ,x 1 ,...,x N-1 And transmitting.
The relation between the redundant data and the original data received by the receiving end is as follows:
wherein ,x0 and y0 Original data of the same value, s= [ s ] 0 ,s 1 ,...,s N-2 ]Representing a data sequence x 0 ,x 1 ,...,x N-2 X is the sign of k,s and yk,s Respectively represents x in the case of a specific s 0 and y0 The kth redundant data, a k,s 、b k,s 、c k,s and dk,s K=0, 1 for the k-th set of coefficients in the particular s case;
the signals received by the receiver are as follows:
wherein i=0, 1,.. x,i and ry,i Representing the received ith set of two-dimensional data, x i and yi Represents the ith group of two-dimensional data transmitted by a transmitting end, n x,i and ny,i And (3) representing additive white gaussian noise of the i-th set of two-dimensional data.
Further, the two-dimensional chaotic decoding in the step S3 adopts improved Single-Input Baker' S analog decoding, specifically maximum likelihood decoding, and corresponding maximum likelihood decoding estimated valueThe following is shown:
wherein ,el,s and eu,s Respectively represent x 0 Minimum and maximum values of the value range, r x and ry For two receivedDimensional data, r x,k and ry,k Representing a received kth set of two-dimensional data, x k and yk Representing the kth group of two-dimensional data transmitted by the transmitting end, wherein max_v is the maximum value of the absolute value of the 3D-DCT coefficient.
Further, x 0 The calculation formulas of the minimum value and the maximum value of the value range are as follows:
further, the maximum likelihood decoding of the receiving end obtains an optimal solution according to the correlation of the input data as follows:
wherein ,for the optimal solution of maximum likelihood decoding in the x-direction for a specific s-case +.>For the calculated value of maximum likelihood decoding in the x-direction for a particular s-case +.>For the optimal solution of maximum likelihood decoding at a particular s-situation in the y-direction,is the calculated value of the maximum likelihood decoding in the y direction at a particular s-case.
Further, the decoding result can be expressed as:
wherein ,as 、b s 、c s and ds For the coefficients in the case of a particular s,is a as s Rank of (a)/(b)>C is s Is a rank of the transition.
Further, the expression is:
wherein ,is the calculated value of the maximum likelihood decoding in the x direction with s1 and s 2.
The low-frequency coefficient matrix height corresponding to the data to be coded and protected in the low-frequency data part occupies 1/D of the total coefficient matrix height, wherein D is a protection coefficient.
An apparatus using the pseudo-analog channel coding method based on two-dimensional chaotic coding, the apparatus comprising a memory storing a computer program and a processor invoking the computer program to perform steps S1 to S3 in the method as described above.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, the low-frequency data part in the 3D-DCT coefficient is subjected to coding protection by adopting the two-dimensional chaotic coding, the transmitted data is protected by adding the channel coding mode, the bandwidth utilization capacity is further improved, the Softcast reconstructed video quality is improved, and the problem that the bandwidth utilization capacity of the Softcast in a repeated data transmission mode is relatively low is effectively solved.
2. The invention aims to solve the problem of poor quality of pseudo-analog coding video under the condition of low signal-to-noise ratio, protects low frequency data by improving Single-Input Baker's analog coding, adjusts the data Input range to ensure that the low frequency data is suitable for the data of DCT coefficients, and selects a smaller number of low frequency DCT coefficients for protection. The improved two-dimensional chaotic coding Input data range can be suitable for the data range of 3D-DCT coefficients, the number of redundant data generated by original Single-Input Baker's analog coding is reduced, the number of transmitted data is reduced, and under the condition of low signal-to-noise ratio, the pseudo-analog channel coding method based on the two-dimensional chaotic coding can remarkably improve the quality of the reconstructed video of a soft receiving end.
Drawings
FIG. 1 is a schematic flow chart of the present invention.
FIG. 2 is a schematic diagram of coefficient protection according to an embodiment of the present invention;
FIG. 3 is a flow chart of the generation of a pseudo-analog coded data sequence based on two-dimensional chaotic coding of the invention;
FIG. 4 is a flow chart of pseudo-analog decoding based on two-dimensional chaotic encoding according to the present invention;
FIG. 5 is a graph showing the effect of parameter settings on system performance according to the present invention;
FIG. 6 is a schematic transmission effect diagram of the present invention, in which FIGS. 6 (a), (b) and (c) are effect diagrams under-10 db, 0db and 10db SNR, respectively;
FIG. 7 is a diagram showing the effect of pseudo-analog channel coding combined with SoftCast transmission based on one-dimensional chaotic coding according to the present invention, wherein FIGS. 7 (a), (b) and (c) are effect diagrams under-10 db, 0db and 10db signal to noise ratios, respectively;
FIG. 8 is a diagram of the transmission effect of pseudo-analog channel coding based on two-dimensional chaotic coding according to the present invention, wherein FIGS. 8 (a), (b) and (c) are effect diagrams under-10 db, 0db and 10db signal-to-noise ratios, respectively;
FIG. 9 is a graph showing performance comparisons of three wireless video transmission modes according to an embodiment of the present invention;
fig. 10 is a comparison diagram of performance of three wireless video transmission modes according to an embodiment of the present invention.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
Examples
As shown in fig. 1, the pseudo-analog channel coding method based on two-dimensional chaotic coding remarkably improves the bandwidth utilization capability under the condition of low signal-to-noise ratio, and specifically comprises the following steps:
s1, a transmitting end acquires video pixel data to be transmitted, performs 3D-DCT operation on the video pixel data to obtain 3D-DCT coefficients and performs standardization processing;
s2, performing coding protection by adopting two-dimensional chaotic coding on a low-frequency data part in the 3D-DCT coefficient, transmitting a high-frequency data part according to an original SoftCast, performing power distribution and whitening operation on data needing to be transmitted, and transmitting the data to a receiving end;
s3, the receiving end carries out LLSE decoding according to the received data, then carries out data recovery on the coded low-frequency data part by using two-dimensional chaotic decoding, carries out inverse DCT operation according to the 3D-DCT coefficient obtained by decoding, and then carries out arrangement according to the sequence of each pixel block in video pixel data to obtain a reconstructed video.
In the step S2, the specific process of two-dimensional chaotic coding is to take the initial state of the chaotic system as a data information source, evolve a new state from the chaotic system, take the newly generated state as coding data and carry out coding protection on the analog real-value signal transmitted by the SoftCast, thereby improving the utilization capacity of bandwidth.
The pseudo-analog channel coding based on the two-dimensional chaotic coding can be combined with a pseudo-analog video transmission mode SoftCast to complete wireless video transmission, and a framework of a video transmission system required for completing wireless video transmission comprises a transmitting end pseudo-analog channel coding part and a receiving end pseudo-analog channel decoding part.
The transmitting end pseudo-analog channel coding consists of two parts, wherein the first part is a power distribution process of SoftCast, different power weighting coefficients are distributed for each coefficient block, and the second part is a two-dimensional chaotic coding of low-frequency data, and the specific process comprises the following steps:
s21, acquiring video source data, expanding the range of Input data, adapting to DCT coefficients of different ranges, and generating improved Single-Input Baker' S analog coding redundant data by the following expression:
wherein ,xn and yn For the current two-dimensional input data value, x n+1 and yn+1 For redundant data generated from the current two-dimensional input data value, x 0 and y0 For the same original data, max_v is the maximum value of the absolute value of the 3D-DCT coefficient, sign () is the sign function;
s22, data sequence x generated by chaotic function tent map 0 ,x 1 ,...,x N-1 And a data sequence y generated by the tent map inverse function 0 ,y 1 ,...,y N-1 Is formed into a new data sequence, denoted as x 1-N ,x 2-N ,...,x 0 ,x 0 ,x 1 ,...,x N-1 N represents the length of the data sequence, and the process proceeds as shown in fig. 3;
s23, combining the original DCT coefficient data, the repeated low-frequency data and the redundant data generated by encoding into data to be transmitted.
The pseudo-analog channel decoding of the receiving end comprises two parts, wherein the first part is an LLSE decoding mode of an original SoftCast and is used for reconstructing the whole DCT coefficient, and the second part is an improved Single-Input Baker's analog decoding which adopts maximum likelihood decoding. A flow chart of the modified Single-Input Baker's analog decoding is shown in fig. 4. The specific implementation steps are as follows:
s31, two-dimensional data sequences received by the receiving end are x respectively 0 ,x 1 ,...,x N-1 and y0 ,y 1 ,...,y N-1 . N represents the length of the data sequence, and according to the coding formula in S21, the relation between the redundant data and the original data can be obtained as follows:
wherein ,x0 and y0 Original data of the same value, s= [ s ] 0 ,s 1 ,...,s N-2 ]Representing a data sequence x 0 ,x 1 ,...,x N-2 X is the sign of k,s and yk,s Respectively represents x in the case of a specific s 0 and y0 The kth redundant data, a k,s 、b k,s 、c k,s and dk,s K=0, 1 for the k-th set of coefficients in the particular s case;
s32, obtaining coefficient a k,s 、b k,s 、c k,s and dk,s The iterative relationship of (a) is:
wherein max_v represents the maximum value of the absolute value of the DCT coefficient, s k For the vector value corresponding to the kth group of data, a k+1,s 、b k+1,s 、c k+1,s and dk+1,s K=0, 1, …, N-2 for the k+1th set of coefficients for a particular s case;
s33, setting coefficient a k,s 、b k,s 、c k,s and dk,s The initial values of (2) are:
s34, assuming that the noise in the channel is additive gaussian white noise, the received signal may be expressed as:
wherein i=0, 1, …, N-1, r x,i and ry,i Representing the received ith set of two-dimensional data, x i and yi Represents the ith group of two-dimensional data transmitted by a transmitting end, n x,i and ny,i Additive white gaussian noise representing the i-th set of two-dimensional data;
s35, according to the estimated value representation of the maximum likelihood decoding, an optimal solution of the decoded data can be obtained, and the estimated value expression is as follows:
wherein ,el,s and eu,s Respectively represent x 0 Minimum and maximum values of the value range, r x and ry R for the received two-dimensional data x,k and ry,k Representing a received kth set of two-dimensional data, x k and yk Representing the kth group of two-dimensional data transmitted by the transmitting end, wherein max_v is the maximum value of the absolute value of the 3D-DCT coefficient.
x 0 The calculation formulas of the minimum value and the maximum value of the value range are as follows:
the maximum likelihood decoding at the receiving end obtains the optimal solution according to the correlation of the input data as follows:
wherein ,for the optimal solution of maximum likelihood decoding in the x-direction for a specific s-case +.>For the calculated value of maximum likelihood decoding in the x-direction for a particular s-case +.>For the optimal solution of maximum likelihood decoding at a particular s-situation in the y-direction,is the calculated value of the maximum likelihood decoding in the y direction at a particular s-case.
The result of the decoding can be expressed as:
wherein ,as 、b s 、c s and ds For the coefficients in the case of a particular s,is a as s Rank of (a)/(b)>C is s Is a rank of the transition.
The expression is:
wherein ,is the calculated value of the maximum likelihood decoding in the x direction with s1 and s 2.
The low frequency coefficient matrix height corresponding to the data to be code protected in the low frequency data part occupies 1/D of the total coefficient matrix height, wherein D is a protection coefficient. As shown in fig. 2, the coefficients near the upper left corner are low frequency coefficients, the coefficients near the lower right corner are high frequency coefficients, the absolute value of the low frequency coefficients is relatively greater than the absolute value of the high frequency coefficients, and the importance is greater. In this embodiment, the low frequency data portion in the 3D-DCT coefficient block is selected as the encoded original data for protection. In this embodiment, the protection factor is selected to be 4.
An apparatus using a pseudo-analog channel coding method based on two-dimensional chaotic coding includes a memory storing a computer program and a processor calling the computer program to execute steps S1 to S3 in the above method.
In specific implementation, the embodiment simulates the video transmission performance of a pseudo-analog video transmission mode based on two-dimensional chaotic coding. Based on Matlab simulation test platform, this example uses "Carphone" as the test sequence to analyze the results. First, the impact of the parameters on the transmission video quality is analyzed by adjusting the parameter value max_v in the encoding formula. And secondly, analyzing the performances of different wireless video transmission modes by comparing the original SoftCast, the repeatedly transmitted SoftCast and the pseudo-analog video transmission mode based on the two-dimensional chaotic coding.
The performance of the algorithm has a great correlation with the parameter settings in the algorithm, and the impact of the parameter on the video transmission is analyzed by adjusting the value of the parameter max_v in the encoding. When the ratio of the channel bandwidth to the video bandwidth is 2, the maximum value of all the absolute values of data in the DCT coefficient block is obtained through calculation, the parameter values in the coding formula are respectively set to be one half, one time and two times of the maximum value, and the peak signal-to-noise ratio (PSNR) of the reconstructed video of the receiving end under the three conditions is compared. As shown in fig. 5, the quality of the reconstructed video at the receiving end will be affected when the encoding parameters are different values.
Fig. 6 shows a 16 th frame image of a SoftCast receiving end reconstructed video in three cases of-10 dB, 0dB and 10dB signal-to-noise ratio (SNR) of the receiving end. When the signal-to-noise ratio of the receiving end is-10 dB, the 16 th frame image of the reconstructed video is shown as a figure 6 (a), and the PSNR of the image is 19.5dB. When the signal-to-noise ratio of the receiving end is 0dB, the 16 th frame image of the reconstructed video is shown in fig. 6 (b), and the PSNR of the image is 27.5dB. When the signal-to-noise ratio of the receiving end is 10dB, the 16 th frame image of the reconstructed video is shown in fig. 6 (c), and the PSNR of the image is 37.0dB; as shown in FIG. 7, the 16 th frame image of the reconstructed video of the receiving end is combined with the pseudo-analog channel coding based on the one-dimensional chaotic coding under the three conditions that the signal to noise ratio of the receiving end is-10 dB, 0dB and 10dB respectively. When the signal-to-noise ratio of the receiving end is-10 dB, the 16 th frame image of the reconstructed video is shown in fig. 7 (a), and the PSNR of the image is 21.7dB; when the signal-to-noise ratio of the receiving end is 0dB, the 16 th frame image of the reconstructed video is shown in fig. 7 (b), and the PSNR of the image is 27.5dB; when the signal-to-noise ratio of the receiving end is 10dB, the 16 th frame image of the reconstructed video is shown in fig. 7 (c), and the PSNR of the image is 37.0dB; as shown in FIG. 8, the 16 th frame image of the reconstructed video of the receiving end is combined with the pseudo-analog channel coding based on the two-dimensional chaotic coding under the three conditions that the signal to noise ratio of the receiving end is-10 dB, 0dB and 10dB respectively. When the signal-to-noise ratio of the receiving end is-10 dB, the 16 th frame image of the reconstructed video is shown in fig. 8 (a), and the PSNR of the image is 23.5dB; when the signal-to-noise ratio of the receiving end is 0dB, the 16 th frame image of the reconstructed video is shown in fig. 8 (b), and the PSNR of the image is 28.6dB; when the signal-to-noise ratio of the receiving end is 10dB, the 16 th frame image of the reconstructed video is shown in fig. 8 (c), and the PSNR of the image is 35.9dB.
Under the condition that the signal-to-noise ratio of the receiving end is-10 dB, PSNR of the reconstructed image of the receiving end based on the pseudo-analog channel coding combined with the SoftCast of the two-dimensional chaotic coding is 4.0dB higher than that of the reconstructed image of the SoftCast of the receiving end which is repeatedly transmitted for two times, and the PSNR is 1.8dB higher than that of the pseudo-analog channel coding combined with the SoftCast based on the one-dimensional chaotic coding. Under the condition that the signal-to-noise ratio of the receiving end is 10dB, the PSNR of the reconstructed video of the pseudo-analog channel coding combined with the SoftCast receiving end based on the two-dimensional chaotic coding is 1.1dB lower than that of the reconstructed video of the SoftCast receiving end which is repeatedly transmitted for two times.
In this embodiment, the video transmission performance is analyzed by comparing the PSNR of the reconstructed video at the receiving end of the wireless video transmission mode under different signal-to-noise ratios. As shown in fig. 9, under the condition of low signal-to-noise ratio, the PSNR of the pseudo-analog channel coding combined with the SoftCast receiving end reconstructed video based on the two-dimensional chaotic coding is higher than that of the SoftCast with repeated transmission twice and the pseudo-analog channel coding combined with the SoftCast based on the one-dimensional chaotic coding. When the signal-to-noise ratio of the receiving end is-10 dB, the PSNR of the reconstructed video of the receiving end based on the pseudo-analog channel coding of the two-dimensional chaotic coding and the SoftCast is 1.9dB higher than that of the pseudo-analog channel coding based on the one-dimensional chaotic coding and the SoftCast. When the signal-to-noise ratio of the receiving end is 20dB, the PSNR of the reconstructed video of the pseudo-analog channel coding combined SoftCast receiving end based on the two-dimensional chaotic coding is 1.6dB lower than that of the SoftCast which is repeatedly transmitted for two times.
Fig. 10 shows PSNR comparison results of three wireless video transmission modes of repeated transmission, namely SoftCast, pseudo-analog channel coding based on one-dimensional chaotic coding combined with SoftCast and pseudo-analog channel coding based on two-dimensional chaotic coding combined with SoftCast, under different bandwidths. When the ratio of the channel bandwidth to the video bandwidth is smaller than 5, PSNR of the pseudo-analog channel coding combined with the SoftCast receiving end reconstructed video based on the two-dimensional chaotic coding is higher than PSNR of the pseudo-analog channel coding combined with the SoftCast based on the one-dimensional chaotic coding. When the ratio of the channel bandwidth to the video bandwidth is 2, the PSNR of the reconstructed video of the pseudo-analog channel coding combined SoftCast receiving end based on the two-dimensional chaotic coding is 2.4dB higher than the SoftCast of the repeated transmission. When the ratio of the channel bandwidth to the video bandwidth is 3, the PSNR of the reconstructed video of the pseudo-analog channel coding combined SoftCast receiving end based on the two-dimensional chaotic coding is 4.1dB higher than the SoftCast of the repeated transmission. However, when the ratio of the channel bandwidth to the video bandwidth exceeds 5, the PSNR of the pseudo-analog channel coding combined SoftCast receiving end reconstructed video based on the two-dimensional chaotic coding will be lower than the pseudo-analog channel coding combined SoftCast based on the one-dimensional chaotic coding. Since the amount of low frequency coefficient data to be protected in the present embodiment is small, the protected low frequency coefficient occupies one sixteenth of the total coefficient data amount. Thus, as bandwidth increases, the gain from protecting a small portion of the low frequency data will become lower, while the gain from reducing noise for all coefficient retransmissions will be higher than protecting the low frequency coefficients.
In summary, the pseudo-analog channel coding based on the two-dimensional chaotic coding is combined with the SoftCast to be suitable for the condition of low signal to noise ratio. Under the condition of low signal-to-noise ratio, the PSNR of the reconstructed video of the pseudo-analog channel coding combined SoftCast receiving end based on the two-dimensional chaotic coding is higher than that of the repeated transmission SoftCast and the pseudo-analog channel coding combined SoftCast based on the one-dimensional chaotic coding.
Furthermore, the particular embodiments described herein may vary from one embodiment to another, and the above description is merely illustrative of the structure of the present invention. Equivalent or simple changes of the structure, characteristics and principle of the present invention are included in the protection scope of the present invention. Various modifications or additions to the described embodiments or similar methods may be made by those skilled in the art without departing from the structure of the invention or exceeding the scope of the invention as defined in the accompanying claims.
Claims (6)
1. A pseudo-analog channel coding method based on two-dimensional chaotic coding is characterized by comprising the following steps:
s1, a transmitting end acquires video pixel data to be transmitted, performs 3D-DCT operation on the video pixel data to obtain 3D-DCT coefficients and performs standardization processing;
s2, performing coding protection by adopting two-dimensional chaotic coding on a low-frequency data part in the 3D-DCT coefficient, transmitting a high-frequency data part according to an original SoftCast, performing power distribution and whitening operation on data needing to be transmitted, and transmitting the data to a receiving end;
s3, the receiving end carries out LLSE decoding according to the received data, then carries out data recovery on the coded low-frequency data part by using two-dimensional chaotic decoding, carries out inverse DCT operation according to the 3D-DCT coefficient obtained by decoding, and then carries out arrangement according to the sequence of each pixel block in video pixel data to obtain a reconstructed video;
in the step S2, the two-dimensional chaotic coding adopts an improved Single-Input Baker' S analog coding algorithm, and the specific formula is as follows:
wherein max_v is the maximum value of the absolute value of the 3D-DCT coefficient, sign () is the sign function, x n and yn For the current two-dimensional input data value, x n+1 and yn+1 For redundant data generated from the current two-dimensional input data value, a chaotic function data sequence x is formed 0 ,x 1 ,...,x N-1 And chaos function inverse function data sequence y 0 ,y 1 ,...,y N-1 ，x 0 and y0 N represents the length of the data sequence for the same original data;
the relation between the redundant data and the original data received by the receiving end is as follows:
wherein ,x0 and y0 Original data of the same value, s= [ s ] 0 ,s 1 ,...,s N-2 ]Representing a data sequence x 0 ,x 1 ,...,x N-2 X is the sign of k,s and yk,s Respectively represents x in the case of a specific s 0 and y0 The kth redundant data, a k,s 、b k,s 、c k,s and dk,s K=0, 1 for the k-th set of coefficients in the particular s case;
the signals received by the receiver are as follows:
wherein i=0, 1,.. x,i and ry,i Representing the received ith set of two-dimensional data, x i and yi Represents the ith group of two-dimensional data transmitted by a transmitting end, n x,i and ny,i Additive white gaussian noise representing group i two-dimensional data；
In the step S3, the two-dimensional chaotic decoding adopts improved Single-Input Baker' S analog decoding, specifically maximum likelihood decoding, and corresponding maximum likelihood decoding estimated valueThe following is shown:
wherein ,el,s and eu,s Respectively represent x 0 Minimum and maximum values of the value range, r x and ry R for the received two-dimensional data x,k and ry,k Representing a received kth set of two-dimensional data, x k and yk Representing the kth group of two-dimensional data transmitted by a transmitting end, wherein max_v is the maximum value of absolute values of 3D-DCT coefficients;
x 0 the calculation formulas of the minimum value and the maximum value of the value range are as follows:
wherein ,el,s and eu,s Respectively represent x 0 Minimum and maximum values of the range of values are taken.
2. The method of claim 1, wherein the specific two-dimensional chaotic coding in step S2 is to use an initial state of the chaotic system as a data source, evolve a new state from the chaotic system, and use the newly generated state as coded data.
3. The pseudo-analog channel coding method based on two-dimensional chaotic coding according to claim 1, wherein the chaotic function data sequence and the chaotic function inverse function data sequence are combined to form an analog coding data sequence of a low frequency data portion for transmission.
4. The pseudo-analog channel coding method based on two-dimensional chaotic coding according to claim 1, wherein the maximum likelihood decoding of the receiving end obtains an optimal solution according to the correlation of input data as follows:
wherein ,for the optimal solution of maximum likelihood decoding in the x-direction for a specific s-case +.>For the calculated value of maximum likelihood decoding in the x-direction for a particular s-case +.>For the optimal solution of maximum likelihood decoding in the y-direction for a specific s-case +.>Is the calculated value of the maximum likelihood decoding in the y direction at a particular s-case.
5. The pseudo-analog channel coding method based on two-dimensional chaotic coding according to claim 1, wherein a low-frequency coefficient matrix height corresponding to data to be coded and protected in the low-frequency data portion occupies 1/D of the total coefficient matrix height, wherein D is a protection coefficient.
6. An apparatus for a pseudo-analog channel coding method based on two-dimensional chaotic coding, characterized in that the apparatus comprises a memory and a processor, the memory storing a computer program, the processor invoking the computer program to perform the method according to any of claims 1-5.
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