135results about How to "Improve rate-distortion performance" patented technology

A method of encoding video data using soft decision quantization makes use of iterative encoding to provide the ability to optimize encoding across different functional elements in a hybrid video encoder. Iterative encoding is used to allow quantization step size, motion prediction and quantization levels to be optimized despite their interrelated nature.

Systems and methods for error resilient transmission, rate control, and random access in video communication systems that use scalable video coding are provided. Error resilience is obtained by using information from low resolution layers to conceal or compensate loss of high resolution layer information. The same mechanism is used for rate control by selectively eliminating high resolution layer information from transmitted signals, which elimination can be compensated at the receiver using information from low resolution layers. Further, random access or switching between low and high resolutions is also achieved by using information from low resolution layers to compensate for high resolution spatial layer packets that may have not been received prior to the switching time.

The invention discloses a combined image compression / encryption method based on compressed sensing, which comprises the following steps of: firstly, a dictionary is formed by combining sub dictionaries obtained by classifying and training by combining a K-SVD method; secondly, an improved orthogonal matching pursuit algorithm is adopted in sparse coding; and finally, encryption is embedded in a compression process so that an encryption / compression algorithm of an image is realized. According to the invention, encryption and compression are tightly linked, therefore, on the premise of no basic influence to rate distortion performance, the attack resistance property and the stability of a system are further improved, the rate distortion performance of static image compression is superior to that of international main trend algorithms such as JEFG2000 and SPIHT at present, the image encryption performance is increased, and common attacks such as cipher text-only attack, chosen-ciphertext attack, known-plaintext attack and chosen-plaintext attack can be resisted. The invention can be used in image storage and transmission in the information security transmission fields such as internet, mobile telephones and video conferences.

The invention discloses a distributed video coding system with combined pixel domain-transform domain, belonging to the technical field of video coding, and mainly being used for solving the problems that the transform domain distributed video coding system has quantization loss and side information prediction precision is low. The system is mainly composed of a coding side, a feedback channel and a decoding side, wherein the coding side is used for independently coding an input video frame and respectively coding pixel domain information and transform domain information formed by dividing a Wyner-Ziv frame; the decoding side is used for jointly decoding a received code flow, updating the side information in the process of decoding the pixel domain information, and decoding the subsequent transform domain information; and the feedback channel is used for providing an information path for the decoding side to request a detection bit from the coding side. The distributed video coding system with combined pixel domain-transform domain lowers the loss on the useful information of the Wyner-Ziv frame, improves the prediction precision on the side information, improves the integral performance and the compression efficiency of the system and can be used for the simple video communication system of encoding equipment.

The invention relates to an HEVC interframe coding quick mode selection method, comprising the following steps of: 1, inputting frame video data; 2, selecting a coding tree unit (CTU) to be estimated; 3, calculating the depth estimation range of the current CTU; 4, selecting a CU to be estimated in the current CTU; 5, estimating a large size interframe prediction unit (PU) mode; 6, selecting to estimate a small size interframe PU mode or not; 7, estimating a symmetrical interframe PU mode; 8, selecting to estimate an asymmetrical interframe PU mode or not; 9, estimating an interframe PU mode; 10, selecting the optimum PU mode of the current CU; 11, ending the judgment of the CU partition; 12, repeating the steps 4 to the steps 11 until estimation of all CUs is completed; and 13, repeating the steps 2 to the steps 12 until estimation of all CTUs in the current frame is completed. According to the HEVC interframe coding quick mode selection method, the coding time of the HEVC can be effectively reduced, and meanwhile the good rate-distortion performance is kept.

The invention discloses a low-complexity method for selecting HEVC (High Efficiency Video Coding) coding multiple reference frames. The method comprises the following steps of inputting an original coding sequence, taking a code tree cell as the unit, and selecting the optimal reference frame for each coding cell through the operations of a, if the parent coding unit of the current coding unit is in an SKIP mode, taking the optimal reference frame of all forecast cells in the current coding unit as the optimal reference frame of the parent coding unit, and b, if the parent coding unit of the current coding unit is not in the SKIP mode, firstly selecting multiple reference frames for forecast cells in an inter-frame dividing mode of 2N*2N of the current coding unit, and calculating the rate distortion cost of each reference frame in the 2N*2N inter-frame dividing mode, gathering all reference frames of which the rate distortion costs are lower than a threshold in a reference frame set, and selecting the optimal reference frame for the rest inter-frame dividing modes in the reference frame set. The low-complexity method is capable of remarkably speeding up HEVC video coding.

The invention discloses a multi-view video code rate control method based on a key frame code rate-quantitative model. Code rate control is carried out at four layers including a view layer, a GOP layer, a frame layer and a macro block layer, and code rates among view points are allocated according to scale values of actual coding of the view points in the view layer; the total code rate of the whole GOP is allocated in the GOP layer and a coding quantization parameter of the key frame of each GOP is calculated according to the key frame code rate-quantitative model of the key frame, wherein the key frame code rate-quantitative model is obtained through analysis; code rates are allocated in the frame layer according to code rate allocation weights of B frame of different levels reasonably; and code rates of macro blocks are allocated in the macro block layer according to coding complexities of the macro blocks and coding quantization parameters of the macro blocks are solved. The multi-view video code rate control method has the advantages that the code rate-quantization model of the key frame is utilized, and an unequal code rate allocation strategy is adopted for the B frames of different levels, so that target bit allocation can be carried out more reasonably, code rate control is effectively carried out, and better rate-distortion performance and subjective quality are provided under the condition that code rate control precision is ensured.

A hybrid distributed video encoding method based on wavelet domain intra-frame mode decision capable of improving rate aberration performance, is characterized by the following steps: (1) a low complexity encoding, including the following steps: using traditional intra-frame encoder to code key frames, generating the reference frame of Wyner-Ziv frame by weighted average interpolation, generating a residual frame by a subtraction arithmetic, performing discrete wavelet switch DWT to the residual frame, generating a wavelet block, intra-frame mode decision of the wavelet block, entropy coding of the mode information, and inter-frame SW-SPIHT coding or intra-frame SPIHT coding of the wavelet block; (2) a high-complexity decoding, including the following: using traditional intra-frame decoding algorithm to decode key frames, adopting a motion estimation interpolation to produce side information frame of the Wyner-Ziv, generating the reference frame of the decoding terminal by weighting average interpolation, generating a residual frame of the decoding terminal by a subtraction arithmetic, performing DWT to the residual frame, entropy decoding of the mode information, adopting LBS to perform motion estimation to generate more accurate side information, fine reconstruction of wavelet coefficients, and recovering the original pixels by inverse discrete wavelet transform (IDWT) and addition operations.

The invention discloses a coding method of asymmetric stereoscopic videos, comprising the following steps of: in the coding process of each half resolution ratio down-sampling image of a right view point video by a video coding method with time domain prediction and view point space prediction, using a decoding reconstructed frame of the coded half resolution ratio down-sampling image of the right view point video as a time domain prediction reference frame, and using a half resolution ratio down-sampling image of a synchronous decoding reconstructed frame of a left view point video as a view point space prediction reference frame; and selecting a sampling direction according to the sizes of residual errors of macro blocks which can not only be horizontally predicted, but also be vertically predicted in an I frame image of the left view point video in the half resolution ratio down-sampling process, wherein the residual errors of the macro blocks are predicted by adopting a horizontal prediction mode and a vertical prediction mode, thus better rate-distortion performance can be obtained. Besides, because residual error information can be conveniently obtained during coding without additional calculation, the complexity of the coding can not be enhanced.

The invention discloses an H.264 / scalable video coding medius-grain scalability (SVC MGS) coding-oriented rate distortion mode selection method. Interlayer relevancy in scalable video coding is taken into account, a relationship between a residual prediction residual signal of a macro block in an enhancement layer and a reconstruction distortion signal of a corresponding macro block in a reference layer is analyzed, and values of the residual prediction residual signal and the reconstruction distortion signal are proven to be approximately equal, so that a novel method for determining a rate distortion model for the coding of the enhancement layer and a Lagrange multiplier, and a new Lagrange multiplier is used for MGS coding. A peak signal to noise ratio (PSNR) value of a reconstructed image obtained by the rate distortion optimization coding of the Lagrange multiplier determined by the method is higher than that obtained by the conventional Lagrange multiplier, and an accurate coding mode can be obtained in rate distortion mode selection. The rate distortion performance of coding based on the method is higher than that of the coding based on the conventional Lagrange multiplier.

The invention discloses a multi-layer residual coefficient image coding method based on compressed sensing. The method comprises the steps of dividing noise into 17 layers and training the 17 layers; substituting the 17 newly trained denoising models into an LDAMP iteration algorithm to complete compressed sensing image reconstruction; carrying out compressed sensing reconstruction on each layer and predicting a lower-layer measurement value to obtain a residual error, and carrying out quantization by adopting a block adaptive quantizer with the same quantization bit depth in the coding method; wherein the information needing to be transmitted by the current layer of the image coding end is the difference value between the quantization result of the real measurement value and the quantization result of the prediction measurement values of the reconstructed images of the measurement values of all previous layers of the layer; and the current layer of the image decoding end receiving the transmission information of the corresponding layer of the coding end, obtaining a measurement value or a residual coefficient after adaptive arithmetic decoding, and the image reconstruction of the current layer of the decoding end utilizing the received and recovered image measurement values of all previous layers. According to the multi-layer residual coefficient image coding method based on compressed sensing provided by the invention, the rate distortion performance of image coding based on image compressed sensing reconstruction can be effectively improved.

The invention discloses an SAR image transmission method based on compressed sensing and channel self-adaption. The SAR image transmission method comprises the steps that first, input SAR images are divided into small images with the same size; direction elevating and wavelet transformation are conducted on each small image; zero setting is conducted on coefficients with small amplitude values, only large coefficients in a small proportion are reserved, and then random measurement is conducted on a wavelet coefficient by a random matrix; then quantization is conducted on measurement values. Sampling values after being quantized are packaged before transmission. Random drop and error codes are added in a simulation transmission channel. The inverse operation of the above steps, namely, packaging, inverse quantization, wavelet coefficient reconstruction, wavelet inverse transformation and image combination, are conducted at a receiving end. According to the SAR image transmission method based on the compressed sensing and channel self-adaption, compressed sensing is used as an encoder of the SAR images, only two times of matrix multiplication are needed in the encoding process, and encoding of the SAR images is made to be simple. Due to the fact that an encoding end of the SAR images is placed in flight equipment such as an unmanned plane generally, the encoder is as simple as possible. The compressed sensing is introduced to be used as the compression encoder of the SAR images, and the problem that encoding of the SAR images is complex is solved.

The invention discloses a Wyner-Ziv-video-coding-based Wyner-Ziv frame code rate control system and a Wyner-Ziv-video-coding-based Wyner-Ziv frame code rate control method, which belong to the technical field of distributed video coding and mainly aim to solve the problem that channel resources are not utilized rationally in the quantization matrix selection of a conventional Wyner-Ziv frame. Thecontrol system provided by the invention comprises a training module, a code rate estimation module and a selection module, wherein the training module is used for determining a band rate distortion model coefficient; the code rate estimation module calculates an estimated code rate by utilizing band rate-distortion of source-channel coding; and the selection module selects an optimal quantization matrix from eight candidate quantization matrixes. In the system and the method, the code rate of a coefficient band is estimated by establishing the band rate-distortion of source-channel coding, so the determined quantization matrix is more accurate, and the rate distortion performance of distributed video coding (DVC) is improved. A code rate allocation method provided by the invention can beused for feedback code rate control-free Wyner-Ziv video coding system.

The invention relates to an HEVC intra-frame prediction mode fast selection method which comprises the following steps: (1) inputting a PU to be estimated, and establishing a practical useable intra-frame prediction mode assembly; (2) calculating the sum of absolute difference of all pixels in the PU to be estimated and adjacent pixels in space in the direction different from that of the PU to be estimated; (3) according to the sum of absolute difference of the adjacent pixels in space in the difference direction, judging texture direction characters of the PU to be estimated; (4) according to the texture direction characters, determining the crude mode search range; (5) according to the crude mode search range and the practical useable intra-frame prediction mode assembly, establishing a rate-distortion optimization candidate mode assembly; (6) selecting the optimal intra-frame prediction mode. According to the texture direction characters of the PU to be estimated, the crude search range of the prediction mode can be reduced, and then the number of candidate modes subjected to rate-distortion optimization can be reduced, so that the good code rate-distortion performance can be kept, and meanwhile the computation complexity of HEVC intra-frame prediction mode selection can be obviously reduced.

A method for motion compensated encoding of video data.The method comprises the steps of:generating a motion vector field of video pixels of a current frame to be coded based on a reference frame;obtaining segmenting information defining the division of the current frame into image segments;coding the motion vector field of an image segment Sk to provide compressed motion information comprising a motion coefficient vector ck comprising a set of motion coefficients ci, such that ci·fi(x,y) represents the motion vector field, whereby fi(x,y) defines a certain set of basis functions, wherein i is an index defining a correspondence between each basis function and a corresponding motion coefficient;predicting a motion vector field of a subsequent image segment SL with a set of predicted motion coefficients pi based upon the previously generated motion coefficient vector ck;generating for the subsequent segment SL a set of refinement motion coefficients ri corresponding to the difference between the set of motion coefficients ci and a set of predicted motion coefficients pi such that pi+ri=ci.Another aspects of the invention comprise corresponding video codec, mobile station, telecommunications network and computer program product.

A video encoding method determines the best video encoding mode for a macroblock in the SKIP mode and comparing this cost with other modes. This avoids sub-pixel interpolations for fractional pixels. This models the cost function in a quadratic model and computes the cost for a nearest integer pel and plural adjacent integer pels. This permits determination of the coefficients of the quadratic model. An estimated cost is obtained using the actual fractional pel position in the quadratic model. This can be used for obtaining the cost of a P Skip mode. This can be used for the decision of B direct or B skip modes in B frames.

A method of encoding video data using soft decision quantization makes use of iterative encoding to provide the ability to optimize encoding across different functional elements in a hybrid video encoder. Iterative encoding is used to allow quantization step size, motion prediction and quantization levels to be optimized despite their interrelated nature.

The invention discloses a mode decision based adaptive GOP (group of pictures) coding and decoding method which can improve rate distortion performance. Frames of the GOP which are to be coded are classified into key frame, secondary key frame and WZ frame, wherein the secondary key frame block is coded in an inter-frame mode, intra-frame mode or Skip mode; and the WZ frame block is coded in a WZmode, the intra-frame / WZ mode or Skip / WZ mode. The GOP decoding is classified into key frame decoding, secondary key frame decoding and WZ frame decoding, wherein, the key frame is decoded in the conventional intra-frame mode; the secondary key frame is decoded in the inter-frame mode, intra-frame mode or Skip mode; and the WZ frame is decoded in a WZ block mode, rough intra-frame block mode or Skip block mode. The decoded key frames and secondary key frames of the GOP are stored in a memory. By adopting the invention, both coding efficiency and final decoding quality can be improved for the whole system so that the rate distortion performance is improved greatly under the condition that the calculated amount is slightly improved.

The invention relates to a distributed video encoding method based on motion compensation refinement, which comprises the following steps of: (1) dividing a video sequence into a key frame and a WZ (working zone) frame at an encoding end, and then carrying out DCT (discrete cosine transform), quantization and Turbo encoding on the WZ frame; and (2) at a decoding end, adopting H.264 intra-frame decoding for the key frame, generating a forward motion compensation image and a backward motion compensation image by using an improved three-dimensional recurrent motion searching method, and then generating a side information decoding WZ frame by adopting a motion compensation interpolation method. The method has a reasonable design; by adopting the improved three-dimensional recurrent motion searching method (3DRS), the quality of side information (SI) can be effectively improved; simultaneously, the refinement of the SI is achieved by adopting a space-time boundary matching algorithm (STBMA); the more precise motion vector is obtained by adequately utilizing the smoothness of space and time; and the method has better rate distortion performance.

A method for encoding a current image in an image set is disclosed. The method incudes accessing a reference image for the current image, determining at least one prediction image wherein a prediction image is obtained from a geometric transform applied to the reference image, the prediction image being a prediction for at least one region of current image, encoding the current image based on the at least a prediction image using block matching compensation, generating a bitstream comprising the encoded image, an item representative of the reference image and an item representative of the at least one geometric transform.

The invention relates to an HEVC quantization parameter optimizing method based on a total code rate and information entropy model. The total code rate and information entropy model is used in the code rate control process to adjust the quantization parameters (QP)s in the HEVC coding process according to different sequence characters of different videos, the purposes of improving the rate-distortion performance and controlling the code rate more accurately are achieved, and the coding complexity cannot be obviously affected. The quantization parameter optimizing method is also suitable for calculating the QPs of H.264 / AVC, AVC and other video coding standards.

The invention discloses a side information generation method in distribution type video encoding. The differences of discrete cosine factors of same-position blocks between an original frame and a previous key frame adjacent to the original frame and between the original frame and a next key frame adjacent to the original frame are respectively calculated at an encoding end, the differences of the discrete cosine factors are compared with a preset threshold value, the classified information value is obtained, and therefore whether the position blocks are in a slow motion mode or a strenuous motion mode is judged; if the position blocks move slowly, the encoding end directly discards the position blocks and does not transmit the position blocks, and then the classified information value is directly transmitted to a decoding end, and the decoding end generates the side information directly according to an interpolation algorithm; if the position blocks move strenuously, the classified information value is transmitted to the decoding end, and the decoding end generates the side information according to a fine motion estimation interpolation algorithm. According to side information generation method in the distribution type video encoding, under the condition that encoding complexity is not increased, encoding efficiency is improved, the more accurate side information can be obtained with lower decoding cost, and therefore the image decoding quality is effectively improved.

The invention discloses an HEVC rate control model parameter updating algorithm based on distortion measurement. According to the algorithm, iterative computation is conducted on the parameter alpha and the parameter beta of a code rate control model through a minimum mean square error LMS method; D is set to represent distortion of a video subjected to compressed encoding; R represents the compressed code rate, and C and K represent model parameters related to video sequence characters; the lengths of the iterative steps used by the parameter C and the parameter K during one iteration are delta C and delta K respectively, and the target code rate is R; an R-D code rate distortion model is described through the formula: D(R)=CR-K; during code rate control, the relational expression between the code rate R and the lagrangian multiplier lambda is shown in the specification, and the iterative formula is shown in the specification. According to the HEVC rate control model parameter updating algorithm based on distortion measurement, iteration is conducted according to the video features before and after encoding, HEVC rate control model parameters are accurately updated by accurately measuring the distortion amount, and therefore the more accurate code rate control effect is obtained.

The invention discloses an image compression framework combining super-resolution and residual coding technology. The method includes establishing the mapping relationship of an original image and a sampling image compressed in different coding rate in an offline state, and constructing a super-resolution reconstruction model under each coding frequency; sampling the original image under iteration back projection to obtain the sampled small image; compressing the small image via a third-party encoder and transmitting the code stream and the de-noising auxiliary information; reconstructing the decoded small image into a big image at the decoding end by means of the super-resolution reconstruction model; suppressing the compressed noise in the big image through the combination with the de-noising auxiliary information; calculating the residual of the decoded big image and the original image at the coding end and transmitting the residual to the decoding end by means of the residual coding technology; and decoding the residual image at the decoding end, overlapping with the decoded big image, and recovering the final decoded image. An experiment shows that the framework provided can realize the compression ratio higher than JPEG2000.

The invention relates to a code rate control model updating method based on HEVC standards. In terms of different video sequence characteristics, the parameter alpha and the parameter beta of a code rate control model are adjusted in a self-adaptive mode according to the following methods including a code rate control model parameter alpha updating method and a code rate control model parameter beta updating method (please see equations in the specification), wherein alphanew is an updated parameter alpha, betanew is an updated parameter beta, lambdaold is an original value lambda obtained on the basis of a target code rate R, Rreal is a coded actual code rate, and D(Rreal) expresses video distortion on the basis of the coded actual code rate. According to the method, model parameters can be precisely updated, and therefore a more accurate code rate control effect can be obtained.

A method and a device for transmission and / or reception of digital signals are disclosed. In one embodiment, the method comprises quantizing a source digital signal to generate with different quantizations at least a first and a second bit-stream, of which at least one bit-stream is generated by an embedded quantization, transmitting at least one of the at least first and second bit-streams and generating a dequantized digital signal from at least parts of one of the transmitted at least first and second bit streams, whereby if in the generation of the dequantized digital signal the parts of the at least first and second bit-streams are combined, the combined dequantized signal is generated by an embedded dequantizer having at least two quantization levels and having at least one quantization interval at each quantization level which is finer than quantization intervals for dequantizing any of the at least first and second bit-streams.

Main points of the invention are as following: using rate distortion theory of message source of possessing statistic characteristics of Laplace distribution to build secondary rate distortion model; using secondary rate distortion model to control video encoding rate. Secondary rate distortion model built in the invention is better accorded with real characteristics of rate distortion of video message source. The invention makes encoding output rate of video sequence closer to given channel bandwidth. The invention raises accuracy for controlling video encoding rate, and raises video encoding quality. Advantages are: better performance of rate distortion, applicable to real time multimedia communication and stream media through network.

A distributed video encoder and decoder and a distributed video decoding method using adaptive quantization are provided. Adaptive quantization is performed at the time of encoding and decoding so that limited resources and information can be efficiently used, and a predetermined bit which is previously defined is included in a position of a bit which does not need to be transmitted for channel coding, thereby improving a bit rate-distortion performance as a whole.