CN106303520A - A kind of Low Bit-Rate Video Coding method and system - Google Patents

Abstract

The open a kind of Low Bit-Rate Video Coding method and system of the present invention.This system includes that the first judging treatmenting module, the first conventional coding module, the second judging treatmenting module, the second conventional coding module, next coded frame judging treatmenting module, next coded frame arrange module.The inventive method, by the monitoring to film source image vision sensitizing range, adjusts in good time, limits the coding mode in this region, thus reach when low-bit-rate compact complexity film source, promotes the subjective and objective quality of video compress.

Description

A kind of Low Bit-Rate Video Coding method and system

Technical field

The present invention relates to coding and decoding video field, particularly relate to a kind of Low Bit-Rate Video Coding method and system.

Background technology

Low bit-rate video compression is not enough due to overall code check, and when the complicated film source of its coding, picture quality is anxious Acute decline.Wherein, relative to human eye sensitivity region, such deterioration problem, the pole of vision can be brought Degree discomfort.

Summary of the invention

It is an object of the invention to propose a kind of Low Bit-Rate Video Coding method and system, it is intended to solve existing During technology low-bit-rate compact complexity film source, the problem of image vision sensitizing range poor quality.

The technical scheme is that and be achieved in that,

A kind of Low Bit-Rate Video Coding method, comprises the following steps:

Step A: if judging bpp ＜ Thres₁, then step B is entered；Otherwise, current film source is carried out routine Coding；

Step B: if present frame is I or QP_t＜ Thres₂, then present frame is carried out conventional coding, so Rear entrance step D；Otherwise, step C is entered；

Step C: present frame is defined pattern-coding；

Step D: if next coded frame exists, then next one coded frame is set to present frame, then Enter step B；Otherwise, terminate；

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold.

Preferably,

The span of the first decision threshold is: Thres₁≤0.1；

The span of the second decision threshold is: Thres₂＜ 32.

Preferably,

Described present frame be defined pattern-coding comprise the following steps:

Step C1: initial value k=1 is set；

Step C2: if QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, Then enter step C3；Otherwise, present encoding block is carried out normal mode coding, subsequently into step C7；

Step C3: present encoding block is divided into the block of minimum code block size；

Step C4: calculate the critical parameter of present encoding block；

Step C5: the pattern that is predicted present encoding block limits；

Step C6: present encoding block is defined pattern-coding；

Step C7: if k is ＜ K, then make k=k+1, subsequently into step C2；Otherwise enter step C3；

Wherein, the arrangement sequence number of encoding block during k represents frame；K represents the encoding block number that a two field picture comprises； QP_{T, k}Represent the quantization parameter of present frame kth encoding block；Thres₃Represent the 3rd decision threshold, size(QP_{T, k}) represent present frame kth encoding block size；PU_maxRepresent maximum predicted block size； std_cuy_{T, k}Represent the mean square deviation of present encoding Block Brightness pixel；Thres₄、Thres₅Represent the 4th, the respectively Five decision thresholds, 5 ＜ Thres₄＜ 30 ＜ Thres₅。

Further preferably, the scope of the 3rd decision threshold is as follows: Thres₃＞ 35.

Further preferably, described present encoding block is defined pattern-coding particularly as follows:

When being predicted present encoding block, all prediction alternative mode supported at present encoding block are deleted Except being included inIn all predictive modes, then carry out rate distortion excellent Change, obtain optimum prediction；Then the change quantization of routine, entropy code are carried out；

Wherein,Represent that present encoding block inter prediction deletes collection；Represent Present encoding block infra-frame prediction deletes collection.

Further preferably, the critical parameter of described calculating present encoding block comprises the following steps:

Interim set is set；

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_lu, block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rdRespectively Represent present encoding block is divided into minimum code block size after, be positioned at present encoding block upper left, upper right, Lower-left, the luminance pixel values of bottom right block；Interim set number is not less than 3 and set covers all of block_lu, block_ru, block_ld, block_rd；

Calculate temporary variable lower；

Lower=getnote (max (std (Ω_i) | 1≤i≤6)),

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, then obtain Take the maximum in these mean square deviations, then be assigned to face by interim set subscript corresponding for this maximum Variations per hour lower；Getnote, max, std represent respectively the corresponding subscript of numerical variable of acquisition, maximizing, Seek mean square deviation.

Further preferably, described present encoding block is predicted pattern limit comprise the following steps:

Inter prediction is set and deletes integrated mode；

Calculate present encoding block infra-frame prediction and delete collection；

Wherein, V, H, DDR, DDL, plane, DC are intra prediction mode direction known in the industry.

A kind of Low Bit-Rate Video Coding system, including the first judging treatmenting module, the first conventional coding module, Second judging treatmenting module, the second conventional coding module, next coded frame judging treatmenting module, next Individual coded frame arranges module；

First judging treatmenting module, if for judging bpp ＜ Thres₁, then the second judging treatmenting module is entered ；Otherwise, the first conventional coding module is entered；

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold；

First conventional coding module, for current film source carries out conventional coding, terminates；

Second judging treatmenting module, if for judging that present frame is I or QP_t＜ Thres₂, then under entering One coded frame judging treatmenting module；Otherwise, definition mode code device is entered；

Wherein, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold；

Definition mode code device, for being defined pattern-coding to present frame；

Second conventional coding module, for present frame carries out conventional coding, encodes subsequently into the next one Frame judging treatmenting module；

Next coded frame judging treatmenting module, if for judging that next coded frame exists, then entered Next coded frame arranges module；Otherwise, terminate；

Next coded frame arranges module, for next one coded frame is set to present frame, subsequently into Second judging treatmenting module.

Preferably, described definition mode code device also includes:

Encoding block sequence number initial value arranges module, is used for arranging initial value k=1；

3rd judging treatmenting module, if for judging QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, then enter encoding block and divide module；Otherwise, the 3rd conventional coding is entered Module；

Wherein, the arrangement sequence number of encoding block during k represents frame；QP_{T, k}Represent present frame kth encoding block Quantization parameter；Thres₃Represent the 3rd decision threshold, Thres₃＞ 35；size(QP_{T, k}) represent present frame kth The size of individual encoding block；PU_maxRepresent maximum predicted block size；std_cuy_{T, k}Represent present encoding Block Brightness The mean square deviation of pixel；Thres₄、Thres₅Represent the four, the 5th decision thresholds respectively, 5 ＜ Thres₄＜ 30 ＜ Thres₅；

Encoding block divides module, for present encoding block is divided into the block of minimum code block size；

3rd conventional coding module, for carrying out normal mode coding to present encoding block, subsequently into volume Code module sequence number judge module；

Critical parameter calculates device, for calculating the critical parameter of present encoding block；

Predictive mode device for limiting, limits for present encoding block is predicted pattern；

Definition mode coding module, limits for present encoding block is predicted pattern；

Coding module sequence number judge module, if for judging k ＜ K, then entering next encoding block and arrange mould Block；Otherwise, next coded frame judging treatmenting module is entered；

Wherein, K represents the encoding block number that a two field picture comprises；

Next encoding block arranges module, is used for arranging k=k+1, subsequently into the 3rd judging treatmenting module.

Preferably, described critical parameter calculating device also includes:

Interim set arranges module, is used for arranging interim set；

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_lu, block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rdRespectively Represent present encoding block is divided into minimum code block size after, be positioned at present encoding block upper left, upper right, Lower-left, the luminance pixel values of bottom right block；Interim set number is not less than 3 and set covers all of block_lu, block_ru, block_ld, block_ld；

Temporary variable computing module, is used for calculating temporary variable lower；

Lower=getnote (max (std (Ω_i) | 1≤i≤6)),

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, then obtain Take the maximum in these mean square deviations, then be assigned to face by interim set subscript corresponding for this maximum Variations per hour lower；Getnote, max, std represent respectively the corresponding subscript of numerical variable of acquisition, maximizing, Seek mean square deviation；

Described predictive mode device for limiting includes:

Inter prediction is deleted integrated mode and is arranged module, is used for arranging

Wherein,Represent that present encoding block inter prediction deletes collection；

Infra-frame prediction deletes collection computing module, is used for calculating present encoding block infra-frame prediction and deletes collection；

Wherein,Represent that present encoding block infra-frame prediction deletes collection；V、H、DDR、 DDL, plane, DC are intra prediction mode direction known in the industry.

Beneficial effects of the present invention

The present invention proposes a kind of Low Bit-Rate Video Coding method and system.The present invention is by regarding sheet source images The monitoring of feel sensitizing range, adjusts in good time, limits the coding mode in this region, thus reach at low bit-rate Under, promote the subjective and objective quality of video compress.

Accompanying drawing explanation

Fig. 1 is preferred embodiment of the present invention Low Bit-Rate Video Coding method flow diagram；

Fig. 2 is that present frame is defined in Fig. 1 mode coding method flow chart；

Fig. 3 is the critical parameter method flow diagram calculating present encoding block in Fig. 2；

Fig. 4 is present encoding block to be predicted in Fig. 2 pattern limit method flow diagram；

Fig. 5 is preferred embodiment of the present invention Low Bit-Rate Video Coding system construction drawing；

Fig. 6 is definition mode code device structure chart in Fig. 5；

Fig. 7 is critical parameter computing device structure figure in Fig. 6；

Fig. 8 is predictive mode device for limiting structure chart in Fig. 6.

Detailed description of the invention

In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with accompanying drawing and Embodiment, is further elaborated to the present invention, for convenience of description, illustrate only and the present invention The part that embodiment is relevant.Should be appreciated that the specific embodiment that this place is described, be used only for explaining this Invention, not in order to limit the present invention.

The embodiment of the present invention proposes a kind of Low Bit-Rate Video Coding method and system.The embodiment of the present invention is passed through Monitoring to film source image vision sensitizing range, adjusts in good time, limits the coding mode in this region, thus Reach under low bit-rate, promote the subjective and objective quality of video compress.

Embodiment one

Fig. 1 is preferred embodiment of the present invention one Low Bit-Rate Video Coding method flow diagram；Described method bag Include following steps:

StepO: if bpp is ＜ Thres₁, then Step1 is entered；Otherwise, current film source is carried out conventional coding.

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold, Generally Thres₁≤0.1。

Step1: if present frame is I or QP_t＜ Thres₂, then present frame is carried out conventional coding, then enters Enter Step3；Otherwise, Step2 is entered.

Wherein, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold, usual Thres₂＜ 32.

Step2: present frame is defined pattern-coding.

Fig. 2 is that present frame is defined in Fig. 1 mode coding method flow chart；Described present frame is carried out Definition mode coding comprises the following steps: (Step21-Step27):

Step21: initial value k=1 is set.

Step22: if QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, Then enter Step23；Otherwise, present encoding block is carried out normal mode coding, subsequently into Step27.

Wherein, the arrangement sequence number of encoding block during k represents frame；QP_{T, k}Represent present frame kth coding The quantization parameter of block；Thres₃Represent the 3rd decision threshold, usual Thres₃＞ 35；size(QP_{T, k}) table Show the size of present frame kth encoding block；PU_maxRepresent maximum predicted block size；std_cuy_{T, k}Table Show the mean square deviation of present encoding Block Brightness pixel；Thres₄、Thres₅Represent the four, the 5th judgements respectively Threshold value, general 5 ＜ Thres₄＜ 30 ＜ Thres₅。

Step23: present encoding block is divided into the block of minimum code block size.

Step24: calculate the critical parameter of present encoding block.

Fig. 3 is the critical parameter method flow diagram calculating present encoding block in Fig. 2；Described calculating is current The critical parameter of encoding block comprises the following steps:

Step241: interim set is set.

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_lu, block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rd Represent respectively after present encoding block is divided into minimum code block size, be positioned at present encoding block Upper left, upper right, lower-left, the luminance pixel values of bottom right block；In using, interim set number can To select 6, it is also possible to select several less, but minimum needs 3, and it is all to collect desired covering Block_lu, block_ru, block_ld, block_rd。

Step242: calculate lower=getnote (max (std (Ω_i)|1≤i≤6))。

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, so Maximum in these mean square deviations of rear acquisition, then by under interim set corresponding for this maximum Footmark is assigned to temporary variable lower；Getnote, max, std represent that the corresponding numerical value of acquisition becomes respectively Amount subscript, maximizing, seek mean square deviation.

Step25: the pattern that is predicted present encoding block limits.

Fig. 4 is present encoding block to be predicted in Fig. 2 pattern limit method flow diagram；Described to working as Front encoding block is predicted pattern restriction method and comprises the following steps:

Step251:

Wherein,Represent that present encoding block inter prediction deletes collection.

Step252:

Wherein,Represent that present encoding block infra-frame prediction deletes collection；V、H、DDR、 DDL, plane, DC are intra prediction mode direction known in the industry.

Step26: present encoding block is defined pattern-coding.Specific as follows: present encoding block is entered During row prediction, all prediction alternative mode deletion supported at present encoding block is included inIn all predictive modes, then carry out rate-distortion optimization, Obtain optimum prediction；Then the change quantization of routine, entropy code are carried out.

Step27: if k is ＜ K, then, k=k+1, subsequently into Step22；Otherwise, Step3 is entered.

Wherein, K represents the encoding block number that a two field picture comprises.

Step3: if next coded frame exists, then next one coded frame is set to present frame, subsequently into Step1；Otherwise, terminate.

Embodiment two

Fig. 5 is preferred embodiment of the present invention one Low Bit-Rate Video Coding system construction drawing；This system includes One judging treatmenting module, the first conventional coding module, the second judging treatmenting module, the second conventional coding mould Block, next coded frame judging treatmenting module, next coded frame arrange module.

First judging treatmenting module, if for judging bpp ＜ Thres₁, then the second judging treatmenting module is entered ；Otherwise, the first conventional coding module is entered.

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold, Generally Thres₁≤0.1。

First conventional coding module, for current film source carries out conventional coding, terminates；

Second judging treatmenting module, if for judging that present frame is I or QP_t＜ Thres₂, then under entering One coded frame judging treatmenting module；Otherwise, definition mode code device is entered.

Wherein, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold, usual Thres₂＜ 32.

Definition mode code device, for being defined pattern-coding to present frame.

Second conventional coding module, for present frame carries out conventional coding, encodes subsequently into the next one Frame judging treatmenting module；

Next coded frame judging treatmenting module, if for judging that next coded frame exists, then entered Next coded frame arranges module；Otherwise, terminate.

Next coded frame arranges module, for next one coded frame is set to present frame, subsequently into Second judging treatmenting module.

Fig. 6 is definition mode code device structure chart in Fig. 5；Further, described definition mode coding dress Put and also include:

Encoding block sequence number initial value arranges module, is used for arranging initial value k=1.

3rd judging treatmenting module, if for judging QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, then enter encoding block and divide module；Otherwise, the 3rd conventional coding is entered Module；

Wherein, the arrangement sequence number of encoding block during k represents frame；QP_{T, k}Represent present frame kth encoding block Quantization parameter；Thres₃Represent the 3rd decision threshold, usual Thres₃＞ 35；size(QP_{T, k}) represent present frame The size of kth encoding block；PU_maxRepresent maximum predicted block size；std_cuy_{T, k}Represent present encoding block The mean square deviation of luminance pixel；Thres₄、Thres₅Represent the four, the 5th decision thresholds respectively, typically 5 ＜ Thres₄＜ 30 ＜ Thres₅。

Encoding block divides module, for present encoding block is divided into the block of minimum code block size.

3rd conventional coding module, for carrying out normal mode coding to present encoding block, subsequently into volume Code module sequence number judge module.

Critical parameter calculates device, for calculating the critical parameter of present encoding block.

Predictive mode device for limiting, limits for present encoding block is predicted pattern.

Definition mode coding module, limits for present encoding block is predicted pattern.

Coding module sequence number judge module, if for judging k ＜ K, then entering next encoding block and arrange mould Block；Otherwise, next coded frame judging treatmenting module is entered.

Wherein, K represents the encoding block number that a two field picture comprises.

Next encoding block arranges module, is used for arranging k=k+1, subsequently into the 3rd judging treatmenting module.

Fig. 7 is critical parameter computing device structure figure in Fig. 6；Further, described critical parameter calculates dress Put and also include:

Interim set arranges module, is used for arranging interim set.

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_lu, block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rdRespectively Represent present encoding block is divided into minimum code block size after, be positioned at present encoding block upper left, upper right, Lower-left, the luminance pixel values of bottom right block；In using, interim set number can select 6, it is also possible to few choosing Several, but minimum needs 3, and collect all of block of desired covering_lu, block_ru, block_ld, block_rd。

Temporary variable computing module, is used for calculating lower=getnote (max (std (Ω_i)|1≤i≤6))。

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, then obtain Take the maximum in these mean square deviations, then be assigned to face by interim set subscript corresponding for this maximum Variations per hour lower；Getnote, max, std represent respectively the corresponding subscript of numerical variable of acquisition, maximizing, Seek mean square deviation.

Fig. 8 is predictive mode device for limiting structure chart in Fig. 6.Described predictive mode device for limiting includes:

Inter prediction is deleted integrated mode and is arranged module, is used for arranging

Wherein,Represent that present encoding block inter prediction deletes collection.

Infra-frame prediction deletes collection computing module, is used for calculating present encoding block infra-frame prediction and deletes collection；

Wherein,Represent that present encoding block infra-frame prediction deletes collection；V、H、DDR、 DDL, plane, DC are intra prediction mode direction known in the industry.

It will be understood by those skilled in the art that realize in above-described embodiment method all or part of Step can be by what programmed instruction related hardware completed, and described program can be stored in a calculating In machine read/write memory medium, described storage medium can be ROM, RAM, disk, CD etc..

The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all at this Any amendment, equivalent and the improvement etc. made within the spirit of invention and principle, should be included in this Within the protection domain of invention.

Claims (10)

1. a Low Bit-Rate Video Coding method, it is characterised in that comprise the following steps:

Step A: if judging bpp ＜ Thres₁, then step B is entered；Otherwise, current film source is carried out routine Coding；

Step B: if present frame is I or QP_t＜ Thres₂, then present frame is carried out conventional coding, so Rear entrance step D；Otherwise, step C is entered；

Step C: present frame is defined pattern-coding；

Step D: if next coded frame exists, then next one coded frame is set to present frame, then Enter step B；Otherwise, terminate；

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold.

2. Low Bit-Rate Video Coding method as claimed in claim 1, it is characterised in that

The span of the first decision threshold is: Thres₁≤0.1；

The span of the second decision threshold is: Thres₂＜ 32.

3. Low Bit-Rate Video Coding method as claimed in claim 1, it is characterised in that described to currently Frame is defined pattern-coding and comprises the following steps:

Step C1: initial value k=1 is set；

Step C2: if QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, Then enter step C3；Otherwise, present encoding block is carried out normal mode coding, subsequently into step C7；

Step C3: present encoding block is divided into the block of minimum code block size；

Step C4: calculate the critical parameter of present encoding block；

Step C5: the pattern that is predicted present encoding block limits；

Step C6: present encoding block is defined pattern-coding；

Step C7: if k is ＜ K, then make k=k+1, subsequently into step C2；Otherwise enter step C3；

Wherein, the arrangement sequence number of encoding block during k represents frame；K represents the encoding block number that a two field picture comprises； QP_{T, k}Represent the quantization parameter of present frame kth encoding block；Thres₃Represent the 3rd decision threshold, size(QP_{T, k}) represent present frame kth encoding block size；PU_maxRepresent maximum predicted block size； std_cuy_{T, k}Represent the mean square deviation of present encoding Block Brightness pixel；Thres₄、Thres₅Represent the 4th, the respectively Five decision thresholds, 5 ＜ Thres₄＜ 30 ＜ Thres₅。

4. Low Bit-Rate Video Coding method as claimed in claim 3, it is characterised in that

The scope of the 3rd decision threshold is as follows: Thres₃＞ 35.

5. Low Bit-Rate Video Coding method as claimed in claim 3, it is characterised in that described to currently Encoding block be defined pattern-coding particularly as follows:

When being predicted present encoding block, all prediction alternative mode supported at present encoding block are deleted Except being included inIn all predictive modes, then carry out rate distortion excellent Change, obtain optimum prediction；Then the change quantization of routine, entropy code are carried out；

Wherein,Represent that present encoding block inter prediction deletes collection；Represent Present encoding block infra-frame prediction deletes collection.

6. Low Bit-Rate Video Coding method as claimed in claim 3, it is characterised in that described calculating is worked as The critical parameter of front encoding block comprises the following steps:

Interim set is set；

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_Lu,block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rdRespectively Represent present encoding block is divided into minimum code block size after, be positioned at present encoding block upper left, upper right, Lower-left, the luminance pixel values of bottom right block；Interim set number is not less than 3 and set covers all of block_lu, block_ru, block_ld, block_rd；

Calculate temporary variable lower；

Lower=getnote (max (std (Ω_i) | 1≤i≤6)),

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, then obtain Take the maximum in these mean square deviations, then be assigned to face by interim set subscript corresponding for this maximum Variations per hour lower；Getnote, max, std represent respectively the corresponding subscript of numerical variable of acquisition, maximizing, Seek mean square deviation.

7. Low Bit-Rate Video Coding method as claimed in claim 3, it is characterised in that described to currently Encoding block is predicted pattern restriction and comprises the following steps:

Inter prediction is set and deletes integrated mode；

$\mathrm{delte}\_\mathrm{mod}{e}_{t,k}^{\mathrm{inter}}=\mathrm{Skip}$ Pattern,

Calculate present encoding block infra-frame prediction and delete collection；

Wherein, V, H, DDR, DDL, plane, DC are intra prediction mode direction known in the industry.

8. a Low Bit-Rate Video Coding system, it is characterised in that include the first judging treatmenting module, One conventional coding module, the second judging treatmenting module, the second conventional coding module, next coded frame are sentenced Disconnected processing module, next coded frame arrange module；

First judging treatmenting module, if for judging bpp ＜ Thres₁, then the second judging treatmenting module is entered ；Otherwise, the first conventional coding module is entered；

Wherein,T_bit represents that target bit rate, width, height, fps divide Biao Shi the pixel columns of sheet source images, number of lines of pixels, sampling frame per second；Thres₁Represent the first decision threshold；

First conventional coding module, for current film source carries out conventional coding, terminates；

Second judging treatmenting module, if for judging that present frame is I or QP_t＜ Thres₂, then under entering One coded frame judging treatmenting module；Otherwise, definition mode code device is entered；

Wherein, QP_tRepresent present frame quantization parameter；Thres₂Represent the second decision threshold；

Definition mode code device, for being defined pattern-coding to present frame；

Second conventional coding module, for present frame carries out conventional coding, encodes subsequently into the next one Frame judging treatmenting module；

Next coded frame judging treatmenting module, if for judging that next coded frame exists, then entered Next coded frame arranges module；Otherwise, terminate；

Next coded frame arranges module, for next one coded frame is set to present frame, subsequently into Second judging treatmenting module.

9. Low Bit-Rate Video Coding system as claimed in claim 8, it is characterised in that described restriction mould Formula code device also includes:

Encoding block sequence number initial value arranges module, is used for arranging initial value k=1；

3rd judging treatmenting module, if for judging QP_{T, k}＞ Thres₃And size (QP_{T, k})=PU_maxAnd Thres₄＜ std_cuy_{T, k}＜ Thres₅, then enter encoding block and divide module；Otherwise, the 3rd conventional coding is entered Module；

Wherein, the arrangement sequence number of encoding block during k represents frame；QP_{T, k}Represent present frame kth encoding block Quantization parameter；Thres₃Represent the 3rd decision threshold, Thres₃＞ 35；size(QP_{T, k}) represent present frame kth The size of individual encoding block；PU_maxRepresent maximum predicted block size；std_cuy_{T, k}Represent present encoding Block Brightness The mean square deviation of pixel；Thres₄、Thres₅Represent the four, the 5th decision thresholds respectively, 5 ＜ Thres₄＜ 30 ＜ Thres₅；

Encoding block divides module, for present encoding block is divided into the block of minimum code block size；

3rd conventional coding module, for carrying out normal mode coding to present encoding block, subsequently into volume Code module sequence number judge module；

Critical parameter calculates device, for calculating the critical parameter of present encoding block；

Predictive mode device for limiting, limits for present encoding block is predicted pattern；

Definition mode coding module, limits for present encoding block is predicted pattern；

Coding module sequence number judge module, if for judging k ＜ K, then entering next encoding block and arrange mould Block；Otherwise, next coded frame judging treatmenting module is entered；

Wherein, K represents the encoding block number that a two field picture comprises；

Next encoding block arranges module, is used for arranging k=k+1, subsequently into the 3rd judging treatmenting module.

10. Low Bit-Rate Video Coding system as claimed in claim 9, it is characterised in that described judgement Parameter calculation apparatus also includes:

Interim set arranges module, is used for arranging interim set；

Ω₁={ block_lu, block_ru}、Ω₂={ block_lu, block_ld}、Ω₃={ block_lu, block_rd}、

Ω₄={ block_ru, block_ld}、Ω₅={ block_ru, block_rd}、Ω₆={ block_ld, block_rd}

Wherein, Ω_iRepresent that i-th is gathered temporarily, 1≤i≤6；block_lu, block_ru, block_ld, block_rdRespectively Represent present encoding block is divided into minimum code block size after, be positioned at present encoding block upper left, upper right, Lower-left, the luminance pixel values of bottom right block；Interim set number is not less than 3 and set covers all of block_lu, block_ru, block_ld, block_rd；

Temporary variable computing module, is used for calculating temporary variable lower；

Lower=getnote (max (std (Ω_i) | 1≤i≤6)),

Wherein, getnote (max (std (Ω_i) | 1≤i≤6)) represent the mean square deviation asking all interim set, then obtain Take the maximum in these mean square deviations, then be assigned to face by interim set subscript corresponding for this maximum Variations per hour lower；Getnote, max, std represent respectively the corresponding subscript of numerical variable of acquisition, maximizing, Seek mean square deviation；

Described predictive mode device for limiting includes:

Inter prediction is deleted integrated mode and is arranged module, is used for arrangingPattern；

Wherein,Represent that present encoding block inter prediction deletes collection；

Infra-frame prediction deletes collection computing module, is used for calculating present encoding block infra-frame prediction and deletes collection；

Wherein,Represent that present encoding block infra-frame prediction deletes collection；V、H、DDR、 DDL, plane, DC are intra prediction mode direction known in the industry.