CN106331699B - Image coding method and image encoder - Google Patents

Abstract

The present invention provides a kind of image encoding method and image encoder, comprising: encoding block to be encoded is divided into M sub- encoding blocks；The first rate distortion costs value that encoding block corresponds to interframe 2N × 2N prediction mode is obtained, the rate distortion costs value that M sub- encoding blocks respectively correspond to interframe 2N × 2N prediction mode is obtained；Correspond to the rate distortion costs value of interframe 2N × 2N prediction mode according to M sub- encoding blocks, it determines that encoding block corresponds to the first estimated value of the rate distortion costs value of interframe 2N × N prediction mode, and corresponds to the second estimated value of the rate distortion costs value of interframe N × 2N prediction mode；According to the first rate distortion costs value, the first estimated value and the second estimated value, the optimal prediction modes of encoding block are determined；According to the optimal prediction modes of encoding block, predictive coding is carried out to encoding block.Present invention reduces the encoder complexities of image.

Description

Image coding method and image encoder

technical field

The present invention relates to the field of image encoding and decoding, and more particularly, to an image encoding method and an image encoder.

Background technique

Compared with H.264/AVC, the high-efficiency video coding (High Efficiency Video Coding, HEVC) standard protocol has obvious advantages. Under the same subjective experience, the HEVC code stream can be reduced by half. The HEVC coding architecture consists of modules such as intra-frame prediction, inter-frame prediction, Rate Distortion Optimization (RDO), entropy coding, and loop filtering.

Specifically, during encoding, with the largest coding unit (Largest Coding Unit, LCU) as the unit, the image block of size 64×64 is divided into four blocks of size 32×32, 16 blocks of size 16x16 and 64 blocks of size 8x8. Each coding block in each layer needs to use multiple inter prediction modes and multiple intra prediction modes for prediction, and find out the prediction mode that minimizes the rate-distortion cost of each coding block as the coding block. the optimal forecasting model. Each coding block is then predicted and encoded based on the optimal prediction mode for each coding block.

Specifically, taking a non-8×8 block as an example, each non-8×8 block can adopt multiple division modes (for example, each non-8×8 block can include 2N×2N, 2N×N, N×2N, etc. divisions) mode, where 2N×2N means that the image block is not divided, 2N×N means that the image block is divided into upper and lower sub-blocks, and N×2N means that the image block is divided into left and right sub-blocks) corresponding to inter-frame prediction mode, and intra-frame prediction modes corresponding to 35 angular directions in the 2N×2N split mode (that is, intra-frame prediction needs to be performed once in each angular direction). For an 8×8 block, each 8×8 block adopts the inter prediction modes corresponding to the following four partition modes: 2N×2N, 2N×N, N×2N and N×N, and 2N×2N and N×N two Intra prediction modes corresponding to each of the 35 angular directions in each of the split modes.

FIG. 1 is a coding frame diagram of HEVC in the prior art, which will be described in detail below with reference to FIG. 1 . As shown in Figure 1, taking the LCU as the unit, the image blocks are divided layer by layer to obtain 4 layers of blocks of different sizes, among which:

Layer 0: Perform inter-frame prediction corresponding to multiple division modes (including 2N×2N, 2N×N, N×2N) for 64×64 blocks, and intra-frame prediction corresponding to 35 angular directions in 2N×2N division mode ;

Layer 1: Perform inter-frame prediction corresponding to multiple partition modes (including 2N×2N, 2N×N, N×2N) for four 32×32 blocks, and 35 angular directions corresponding to the 2N×2N partition mode. Intra prediction;

Layer 2: Perform inter-frame predictions corresponding to 16 16×16 blocks in various division modes (including 2N×2N, 2N×N, N×2N), and 35 angular directions corresponding to the 2N×2N division mode. Intra prediction;

Layer 3: Perform inter-frame prediction under 4 partition modes (2N×2N, 2N×N, N×2N, N×N) for 64 8×8 blocks, as well as 2N×2N and N×N Intra prediction corresponding to each 35 directions in split mode.

As mentioned above, compared with H.264/AVC, when HEVC coding, not only the division of blocks becomes more complicated, which increases the number of coding blocks, but also the intra-frame and inter-frame prediction modes supported by each coding block increase. When coding an image block, it is necessary to use all the inter-frame and intra-frame prediction modes corresponding to each coding block for prediction, and select the prediction mode with the smallest rate-distortion cost as the optimal prediction mode for the coding block, resulting in The image coding complexity is high.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide an image encoding method and an image encoder, so as to reduce the complexity of image encoding.

In a first aspect, an image coding method is provided, including: dividing a coding block to be coded into M sub-coding blocks, where the coding block is an image block of the image, and M is a positive integer greater than or equal to 2; using The inter-frame 2N×2N prediction mode predicts the coding block, and obtains the first rate-distortion cost value of the coding block corresponding to the inter-frame 2N×2N prediction mode, and uses the inter-frame 2N×2N prediction mode to predict the M Predict the sub-coding blocks, and obtain the rate-distortion cost value of each of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode; according to the M sub-coding blocks corresponding to the inter-frame 2N×2N a rate-distortion cost value of the prediction mode, determining a first estimate of the rate-distortion cost value of the coding block corresponding to the inter 2N×N prediction mode, and determining the rate-distortion cost value corresponding to the inter 2N×2 prediction mode according to the M sub-coding blocks determine the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode; according to the first rate-distortion cost value, the first estimated value and the The second estimated value determines the optimal prediction mode of the coding block; and performs predictive coding on the coding block according to the optimal prediction mode of the coding block.

With reference to the first aspect, in an implementation manner of the first aspect, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block, so Determining, according to the rate-distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, the first estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, including: The upper left sub-coding block is determined according to the rate-distortion cost value of the upper-left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the upper-right sub-coding block corresponding to the inter 2N×2N prediction mode The image block formed with the upper right sub-coding block corresponds to the third estimated value of the rate-distortion cost value of the inter 2N×N prediction mode; according to the lower left sub-coding block corresponding to the rate-distortion of the inter 2N×2N prediction mode The cost value and the lower right sub-coding block correspond to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and it is determined that the image block composed of the lower-left sub-coding block and the lower-right sub-coding block corresponds to the inter-frame 2N×N prediction a fourth estimate of the rate-distortion cost value of the mode; the first estimate is calculated based on the third estimate and the fourth estimate.

With reference to the first aspect or any one of the above implementation manners, in another implementation manner of the first aspect, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, and a lower-left sub-coding block. The sub-coding block and the lower-right sub-coding block, the rate-distortion value of the coding block corresponding to the inter-frame N×2N prediction mode is determined according to the rate-distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode The second estimated value of the cost value includes: the rate-distortion cost value corresponding to the inter-frame 2N×2N prediction mode of the upper left sub-coding block and the rate-distortion value of the lower left sub-coding block corresponding to the inter-frame 2N×2N prediction mode The cost value is to determine the fifth estimated value of the rate-distortion cost value of the image block composed of the upper left sub-coding block and the lower left sub-coding block corresponding to the inter-frame N×2N prediction mode; according to the upper right sub-coding block corresponding to The rate-distortion cost value of the inter-frame 2N×2N prediction mode and the rate-distortion cost value of the lower-right sub-coding block corresponding to the inter-frame 2N×2N prediction mode are determined to determine the composition of the upper-right sub-coding block and the lower-right sub-coding block. The image block corresponds to a sixth estimate of the rate-distortion cost value of the inter N×2N prediction mode; the second estimate of the coding block is calculated based on the fifth estimate and the sixth estimate.

With reference to the first aspect or any one of the foregoing implementation manners, in another implementation manner of the first aspect, the first rate-distortion cost value, the first estimated value, and the second estimated value, and determining the optimal prediction mode for the coding block includes: determining the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the minimum value corresponds to When the inter-frame prediction mode is the inter-frame 2N×2N prediction mode, the inter-frame 2N×2N prediction mode is used as the optimal inter-frame prediction mode of the coding block; according to the optimal inter-frame prediction mode, the coding block is determined the optimal forecasting model.

With reference to the first aspect or any one of the foregoing implementation manners, in another implementation manner of the first aspect, the first rate-distortion cost value, the first estimated value, and the second estimated value, and determining the optimal prediction mode for the coding block includes: determining the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the minimum value corresponds to When the target inter-frame prediction mode is the inter-frame 2N×N prediction mode or the inter-frame N×2N prediction mode, use the target inter-frame prediction mode to predict the coding block, and obtain that the coding block corresponds to the target The second rate-distortion cost value of the inter-frame prediction mode; the inter-frame prediction mode corresponding to the smaller of the first rate-distortion cost value and the second rate-distortion cost value is taken as the optimal frame of the coding block inter prediction mode; according to the optimal inter prediction mode, determine the optimal prediction mode of the coding block.

With reference to the first aspect or any one of the above implementation manners, in another implementation manner of the first aspect, the optimal prediction of the coding block is determined according to the optimal inter-frame prediction mode of the coding block mode, including: when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is less than or equal to a preset threshold, using the optimal inter-frame prediction mode as the optimal prediction mode; or , when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is greater than the preset threshold, use the intra-frame prediction mode to predict the coding block, and obtain the coding block corresponding to The third rate-distortion cost value of the intra-frame prediction mode, the coding block corresponds to the prediction mode corresponding to the smaller value of the rate-distortion cost value of the optimal inter-frame prediction mode and the third rate-distortion cost value as the optimal prediction mode for the coding block.

With reference to the first aspect or any one of the above implementation manners, in another implementation manner of the first aspect, the optimal prediction of the coding block is determined according to the optimal inter-frame prediction mode of the coding block mode, including: when the optimal prediction modes of the M sub-coding blocks are all inter-frame prediction modes, determining the optimal inter-frame prediction mode as the optimal prediction mode of the coding block; or, when the When there is a sub-coding block whose optimal prediction mode is the intra-frame prediction mode among the M sub-coding blocks, use the intra-frame prediction mode to predict the coding block, and obtain the third rate of the coding block corresponding to the intra-frame prediction mode Distortion cost value, taking the prediction mode corresponding to the smaller of the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate-distortion cost value as the optimal value of the coding block forecast mode.

In a second aspect, an image encoder is provided, comprising: a division module configured to divide a coding block to be coded into M sub-coding blocks, where the coding block is an image block of the image, and M is greater than or equal to 2 A positive integer of The inter 2N×2N prediction mode performs prediction on the M sub-coding blocks divided by the dividing module, and obtains the rate-distortion of each sub-coding block in the M sub-coding blocks corresponding to the inter 2N×2N prediction mode. a cost value; a first determining module, configured to determine, according to the rate-distortion cost value of the M sub-coding blocks obtained by the obtaining module, corresponding to the inter-frame 2N×2N prediction mode, determine that the coding block corresponds to the inter-frame 2N×2N prediction mode a first estimate of the rate-distortion cost value of the N prediction mode, and determining that the coding block corresponds to the inter-frame N×2N prediction based on the rate-distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode a second estimated value of the rate-distortion cost value of the mode; a second determination module, configured to use the first rate-distortion cost value acquired by the acquiring module and the first estimated value determined by the first determining module and the second estimated value to determine the optimal prediction mode of the coding block; the coding module is configured to predict the coding block according to the optimal prediction mode of the coding block determined by the second determining module coding.

With reference to the second aspect, in an implementation manner of the second aspect, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block, so The first determining module is specifically configured to, according to the rate-distortion cost value of the upper left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the upper right sub-coding block corresponding to the inter 2N×2N prediction mode , determine that the image block composed of the upper left sub-coding block and the upper right sub-coding block corresponds to the third estimated value of the rate-distortion cost value of the inter-frame 2N×N prediction mode; The rate-distortion cost value of the 2N×2N prediction mode and the rate-distortion cost value of the lower right sub-coding block corresponding to the inter-frame 2N×2N prediction mode, determine the image block composed of the lower-left sub-coding block and the lower-right sub-coding block a fourth estimated value of the rate-distortion cost value corresponding to the inter 2N×N prediction mode; the first estimated value is calculated according to the third estimated value and the fourth estimated value.

With reference to the second aspect or any of the foregoing implementation manners, in another implementation manner of the second aspect, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, and a lower-left sub-coding block. a sub-coding block and a lower-right sub-coding block, the first determining module is specifically configured to, according to the rate-distortion cost value of the upper-left sub-coding block corresponding to the inter-frame 2N×2N prediction mode and the lower-left sub-coding block corresponding to the inter-frame The rate-distortion cost value of the 2N×2N prediction mode is determined, and the image block formed by the upper left sub-coding block and the lower left sub-coding block corresponds to the fifth estimated value of the rate-distortion cost value of the inter-frame N×2N prediction mode; according to The upper right sub-coding block corresponds to the rate-distortion cost value of the inter-frame 2N×2N prediction mode and the lower-right sub-coding block corresponds to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, determine the upper right sub-coding block and The image block formed by the lower right sub-coding block corresponds to the sixth estimated value of the rate-distortion cost value of the inter-frame N×2N prediction mode; the coding block is calculated according to the fifth estimated value and the sixth estimated value the second estimate of .

With reference to the second aspect or any one of the foregoing implementation manners, in another implementation manner of the second aspect, the second determination module is specifically configured to determine the first rate-distortion cost value, the first estimate value and the minimum value of the second estimated value; when the inter-frame prediction mode corresponding to the minimum value is the inter-frame 2N×2N prediction mode, the inter-frame 2N×2N prediction mode is used as the optimal coding block inter-frame prediction mode; according to the optimal inter-frame prediction mode, determine the optimal prediction mode of the coding block.

With reference to the second aspect or any one of the foregoing implementation manners, in another implementation manner of the second aspect, the second determination module is specifically configured to determine the first rate-distortion cost value, the first estimate value and the minimum value of the second estimated value; when the target inter-frame prediction mode corresponding to the minimum value is an inter-frame 2N×N prediction mode or an inter-frame N×2N prediction mode, the target inter-frame prediction mode is used mode to predict the coding block, and obtain the second rate-distortion cost value of the coding block corresponding to the target inter-frame prediction mode; the first rate-distortion cost value and the second rate-distortion cost value are The inter-frame prediction mode corresponding to the smaller value in is used as the optimal inter-frame prediction mode of the coding block; the optimal inter-frame prediction mode of the coding block is determined according to the optimal inter-frame prediction mode.

With reference to the second aspect or any one of the above implementation manners, in another implementation manner of the second aspect, the second determining module is specifically configured to, when the coding block corresponds to the optimal inter-frame prediction mode When the rate-distortion cost value is less than or equal to a preset threshold, the optimal inter-frame prediction mode is used as the optimal prediction mode; or, when the coding block corresponds to the rate-distortion rate of the optimal inter-frame prediction mode When the cost value is greater than the preset threshold, use the intra-frame prediction mode to predict the coding block, obtain the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode, and set the coding block corresponding to the intra-frame prediction mode. The prediction mode corresponding to the smaller of the rate-distortion cost value of the optimal inter-frame prediction mode and the third rate-distortion cost value is used as the optimal prediction mode of the coding block.

With reference to the second aspect or any one of the above implementation manners, in another implementation manner of the second aspect, the second determining module is specifically configured to be used when the optimal prediction modes of the M sub-coding blocks are frame When the inter prediction mode is used, the optimal inter prediction mode is determined as the optimal prediction mode of the coding block; or, when there is a sub coding block whose optimal prediction mode is the intra prediction mode in the M sub coding blocks when the intra-frame prediction mode is used to predict the coding block, and the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode is obtained, and the coding block is corresponding to the optimal inter-frame prediction mode The prediction mode corresponding to the smaller of the rate-distortion cost value and the third rate-distortion cost value is used as the optimal prediction mode of the coding block.

The embodiment of the present invention divides the coding block into M sub-coding blocks, obtains the rate-distortion cost values of the coding block and the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, and obtains the rate-distortion cost values of the M sub-coding blocks according to the rate-distortion generation of the M sub-coding blocks. The value determines the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, and the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode. The rate-distortion cost value of the coding block and the determined estimated value of the rate-distortion cost value of the coding block, determine the optimal prediction mode of the coding block, and it is not necessary to use all prediction modes to predict the coding block as in the prior art. The optimal prediction mode of the coding block is selected, thereby reducing the coding complexity of the image.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a coding frame diagram of HEVC in the prior art.

FIG. 2 is a schematic flowchart of an image coding method according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of division of a coding block into 4 sub-coding blocks.

FIG. 4 is an example diagram of an encoding block according to a 2N×N partition mode.

FIG. 5 is an example diagram of division of coding blocks according to an N×2N partition mode.

FIG. 6 is an exemplary diagram of an image encoding process according to an embodiment of the present invention.

FIG. 7 is an exemplary diagram of an image encoding process according to an embodiment of the present invention.

FIG. 8 is a schematic diagram of a sub-block combining manner.

FIG. 9 is a schematic flowchart of judging whether to continue performing intra-frame calculation based on an inter-frame calculation result according to an embodiment of the present invention.

FIG. 10 is a schematic flowchart of judging whether to continue performing intra-frame calculation based on an inter-frame calculation result according to an embodiment of the present invention.

FIG. 11 is a schematic structural diagram of an image encoder according to an embodiment of the present invention.

FIG. 12 is a schematic structural diagram of an image encoder according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

FIG. 2 is a schematic flowchart of an image coding method according to an embodiment of the present invention. The method of Figure 2 includes:

210. Divide the coding block to be coded into M sub-coding blocks, where the coding block is an image block of an image, and M is a positive integer greater than or equal to 2.

It should be understood that the shapes of the above coding blocks and the above sub-coding blocks may be squares.

The image coding method according to the embodiment of the present invention can be applied to the HEVC coding architecture. Specifically, in the HEVC architecture, the image block is firstly divided in the form of a quadtree based on the LCU to obtain a multi-layer coding block. For example, the size of the LCU can be 64×64, and the 64×64 image block is used as the coding block (or coding unit) of the 0th layer, and then the coding block of the 0th layer is divided in the form of a quadtree, Obtain four 32×32-sized coding blocks located in the first layer, and then divide the four 32×32-sized encoding blocks in the first layer in the form of a quadtree, to obtain 16 16 blocks located in the second layer ×16 coding blocks, and then divide the 16 16 × 16 coding blocks of the second layer in the form of quadtrees to obtain 64 8 × 8 coding blocks located in the third layer, and the step The coding block in 210 may be a coding block in any of the above-mentioned layers 0 to 3, and the M sub-blocks of the above-mentioned coding block may refer to 4 sub-codings that are divided into the coding block in the form of a quadtree. piece.

220. Use the inter-frame 2N×2N prediction mode to predict the coding block, obtain the first rate-distortion cost value of the coding block corresponding to the inter-frame 2N×2N prediction mode, and use the inter-frame 2N×2N prediction mode to predict the M sub-coding blocks. Prediction is performed, and the rate-distortion cost value of each of the M sub-coding blocks corresponding to the inter 2N×2N prediction mode is obtained.

It should be noted that the coding block may include an inter 2N×2N prediction mode, an inter N×2N prediction mode, and an inter 2N×N prediction mode. The so-called inter-frame 2N×2N prediction mode can refer to the inter-frame prediction in the 2N×2N segmentation mode, that is, the inter-frame prediction is performed directly without dividing the image block; Inter-frame prediction is performed in the N partition mode, that is, the image block is divided into upper and lower sub-blocks to perform inter-frame prediction; similarly, the inter-frame N×2N prediction mode can refer to the inter-frame prediction in the N×2N partition mode, that is, the image The block is divided into left and right sub-blocks for inter prediction.

230. Determine, according to the rate-distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, a first estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, and according to the M sub-coding blocks The block corresponds to the rate-distortion cost value of the inter 2Nx2N prediction mode, and a second estimate of the rate-distortion cost value of the coded block corresponding to the inter Nx2N prediction mode is determined.

An example is given by taking M sub-coding blocks as 4 sub-coding blocks as an example. As shown in FIG. 3 , the four sub-blocks include sub-block 0, sub-block 1, sub-block 2 and sub-block 3. The inter-frame 2N×N prediction mode is to perform inter-frame prediction after dividing the coding block into upper and lower sub-blocks. As shown in Figure 4, the upper and lower sub-blocks can be upper block 0 and lower block 1 respectively; The N×2N prediction mode is to perform inter-frame prediction after dividing the coding block into left and right sub-blocks. As shown in FIG. 5 , the left and right sub-blocks may be left block 0 and right block 1 respectively. In this embodiment of the present invention, the sub-blocks shown in FIG. 4 and FIG. 5 and the sub-blocks shown in The rate-distortion cost value is estimated, which will be described in detail later in conjunction with specific embodiments.

240. Determine an optimal prediction mode for the coding block according to the first rate-distortion cost value, the first estimated value, and the second estimated value.

There can be various implementations of step 240. For example, the minimum value can be selected from the first rate-distortion cost value, the first estimated value, and the second estimated value, and then the prediction mode corresponding to the minimum value is determined as the above-mentioned optimal prediction. or, determine the prediction mode corresponding to the minimum value as the optimal inter-frame prediction mode, and then compare the minimum value with the rate-distortion cost value of the intra-frame prediction mode of the coding block to obtain the above optimal forecast mode.

250. Perform predictive coding on the coding block according to the optimal prediction mode of the coding block.

The embodiment of the present invention divides the coding block into M sub-coding blocks, obtains the rate-distortion cost values of the coding block and the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, and obtains the rate-distortion cost values of the M sub-coding blocks according to the rate-distortion generation of the M sub-coding blocks. The value determines the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, and the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode. The rate-distortion cost value of the coding block and the determined estimated value of the rate-distortion cost value of the coding block, determine the optimal prediction mode of the coding block, and it is not necessary to use all prediction modes to predict the coding block as in the prior art. The optimal prediction mode of the coding block is selected, thereby reducing the coding complexity of the image.

Optionally, as an embodiment, M may be 4, and the M sub-coding blocks may include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. Step 230 may include: according to the upper-left sub-coding block The rate-distortion cost value corresponding to the inter-frame 2N×2N prediction mode and the rate-distortion cost value of the upper right sub-coding block corresponding to the inter-frame 2N×2N prediction mode, it is determined that the image block composed of the upper-left sub-coding block and the upper-right sub-coding block corresponds to The third estimate of the rate-distortion cost value of the inter 2N×N prediction mode; according to the rate-distortion cost value of the lower left sub-coding block corresponding to the inter 2N×2N prediction mode and the lower right sub-coding block corresponding to the inter 2N×2N prediction The rate-distortion cost value of the mode is determined, and the image block composed of the lower left sub-coding block and the lower right sub-coding block corresponds to the fourth estimated value of the rate-distortion cost value of the inter-frame 2N×N prediction mode; according to the third estimated value and the fourth estimated value value, calculate the first estimate.

3 and 4 , the rate-distortion cost value cost_0 of the upper left sub-coding block 0 corresponding to the inter 2N×2N prediction mode and the upper right sub-coding block 1 corresponding to the rate of the inter 2N×2N prediction mode in FIG. The distortion cost value cost_1 is weighted and summed to obtain the third estimate of the rate-distortion cost value of the upper block 0 in FIG. 4; the rate of the lower left sub-coding block 2 in FIG. The distortion cost value cost_2 and the rate-distortion cost value cost_3 of the lower right sub-coding block 3 corresponding to the inter-frame 2N×2N prediction mode are weighted and summed to obtain a fourth estimate of the rate-distortion cost value of the lower block 1 in FIG. 4 .

Optionally, as an embodiment, M may be 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. Step 230 may include: according to the correspondence between the upper-left sub-coding blocks Based on the rate-distortion cost value of the inter-frame 2N×2N prediction mode and the rate-distortion cost value of the lower-left sub-coding block corresponding to the inter-frame 2N×2N prediction mode, it is determined that the image block composed of the upper-left sub-coding block and the lower-left sub-coding block corresponds to the frame The fifth estimate of the rate-distortion cost value of the inter-N×2N prediction mode; according to the rate-distortion cost value of the upper right sub-coding block corresponding to the inter 2N×2N prediction mode and the lower right sub-coding block corresponding to the inter 2N×2N prediction mode The rate-distortion cost value is determined, and the image block composed of the upper right sub-coding block and the lower-right sub-coding block corresponds to the sixth estimated value of the rate-distortion cost value of the inter-frame N×2N prediction mode; according to the fifth estimated value and the sixth estimated value , calculate the second estimate of the coded block.

3 and 5 , the rate-distortion cost value cost_0 of the upper left sub-coding block 0 corresponding to the inter 2N×2N prediction mode and the lower left sub-coding block 2 corresponding to the rate of the inter 2N×2N prediction mode in FIG. The distortion cost value cost_2 is weighted and summed to obtain the fifth estimate of the rate-distortion cost value of the left block 0 in FIG. 5; the upper right sub-coding block 1 in FIG. The distortion cost value cost_1 and the rate-distortion cost value cost_3 of the lower right sub-coding block 3 corresponding to the inter 2N×2N prediction mode are weighted and summed to obtain the sixth estimated value of the rate-distortion cost value of the right block 1 in FIG. 5 .

Optionally, as an embodiment, step 240 may include: determining the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the inter-frame prediction mode corresponding to the minimum value is inter-frame 2N× In the 2N prediction mode, the inter-frame 2N×2N prediction mode is used as the optimal inter-frame prediction mode of the coding block; according to the optimal inter-frame prediction mode, the optimal prediction mode of the coding block is determined.

In the embodiment of the present invention, the inter-frame prediction mode corresponding to the minimum value is directly determined as the optimal inter-frame prediction mode, which further reduces the coding complexity of the image.

Optionally, as an embodiment, step 240 may include: determining the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the target inter-frame prediction mode corresponding to the minimum value is inter-frame 2N In the ×N prediction mode or the inter-frame N×2N prediction mode, the target inter-frame prediction mode is used to predict the coding block, and the second rate-distortion cost value of the coding block corresponding to the target inter-frame prediction mode is obtained; The inter-frame prediction mode corresponding to the smaller of the cost value and the second rate-distortion cost value is used as the optimal inter-frame prediction mode of the coding block; the optimal inter-frame prediction mode of the coding block is determined according to the optimal inter-frame prediction mode.

When the target inter-frame prediction mode corresponding to the minimum value is not the inter-frame 2N×2N prediction mode, the embodiment of the present invention does not directly determine the target inter-frame prediction mode as the optimal inter-frame prediction mode of the coding block, but needs to use the target inter-frame prediction mode. The target prediction mode predicts the coding block, and further verifies whether the rate-distortion cost value of the coding block corresponding to the target inter-frame prediction mode is really less than the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×2N prediction mode, which must be To a certain extent, the accuracy of determining the optimal inter-frame prediction mode is improved.

In addition, there can be various implementations for determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode of the coding block. For example, the optimal inter-frame prediction mode of the coding block can be directly used as the Optimal prediction mode; or, use the intra-frame prediction mode of the coding block for prediction, and then select from the optimal inter-frame prediction mode and intra-frame prediction mode of the coding block based on the rate-distortion algorithm to minimize the rate-distortion cost of the coding block , as the optimal prediction mode for the coding block.

Optionally, as an embodiment, the above-mentioned determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode of the coding block may include: when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is less than or When it is equal to the preset threshold, the optimal inter prediction mode is used as the optimal prediction mode; or, when the rate-distortion cost value of the coding block corresponding to the optimal inter prediction mode is greater than the preset threshold, the intra prediction mode is used for encoding block prediction, and obtain the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode, and set the coding block corresponding to the rate-distortion cost value of the optimal inter-frame prediction mode and the smaller value of the third rate-distortion cost value The corresponding prediction mode is used as the optimal prediction mode for the coded block.

In this embodiment of the present invention, the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is directly compared with a preset threshold. The optimal inter-frame prediction mode is determined as the optimal prediction mode of the coding block, which further reduces the coding complexity of the image. The value of the preset threshold can be determined according to experience or testing. When the rate-distortion cost value (hereinafter referred to as the current rate-distortion cost value) of the coding block corresponding to the optimal inter-frame prediction mode is less than the preset threshold, it can be considered that the The optimal inter-frame prediction mode can meet the coding requirements. Although continuing to determine the rate-distortion cost value of the coding block corresponding to other prediction modes may obtain a value smaller than the current rate-distortion cost value, it will not affect the coding performance. A qualitative improvement.

Optionally, as an embodiment, the above-mentioned determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode of the coding block may include: when the optimal prediction modes of the M sub-coding blocks are all inter-frame prediction modes, The optimal inter-frame prediction mode is determined as the optimal prediction mode of the coding block; or, when there are sub-coding blocks whose optimal prediction mode is the intra-frame prediction mode in the M sub-coding blocks, the intra-frame prediction mode is used to perform the coding on the coding block. Predict, and obtain the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode, and set the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate-distortion cost value corresponding to the smaller value The prediction mode serves as the optimal prediction mode for the coded block.

In this embodiment of the present invention, when the optimal prediction modes of the M sub-coding blocks are all inter-frame prediction modes, it can be inferred that the optimal prediction mode of the coding block is also the inter-frame prediction mode, and there is no need to further compare the coding blocks in the frame The rate-distortion cost value in the inter prediction mode and the intra prediction mode is further reduced, thereby further reducing the complexity of image coding.

The embodiments of the present invention are described in more detail below by taking an encoding process and framework in HEVC as an example. It should be noted that the examples in FIG. 6 to FIG. 10 are only for helping those skilled in the art to understand the embodiments of the present invention, and are not intended to limit the embodiments of the present invention to specific numerical values or specific scenarios exemplified. According to the examples shown in FIGS. 6 to 10 , those skilled in the art can obviously make various equivalent modifications or changes, and such modifications or changes also fall within the scope of the embodiments of the present invention.

First, the entire LCU coding process is divided into two parts: top-down (from layer 0 to layer 3) rough calculation and bottom-up (from layer 3 to layer 0) fine calculation.

When calculating from top to bottom, a part of intra-frame or inter-frame prediction modes can be calculated, and when calculating from bottom to top, the remaining prediction modes can be calculated. The rough calculation takes the calculation of only the inter-frame 2Nx2N prediction mode as an example, and the specific flow is shown in FIG. 6 .

In the rough calculation, the 0th layer can only calculate the inter-frame 2Nx2N prediction mode of 1 64x64 block; in the first layer, only 4 inter-frame 2Nx2N prediction modes of 32x32 blocks can be calculated; in the second layer, only 16 can be calculated. Inter-frame 2Nx2N prediction mode of 16x16 blocks; in the third layer, only 64 inter-frame NxN prediction modes of 8x8 blocks can be calculated. During the bottom-up fine calculation, the remaining prediction modes (including the inter-frame 2N×N prediction mode and the inter-frame N×2N prediction mode) may be calculated first, and then the intra-frame prediction mode may be calculated.

On the basis of the general architecture of Figure 6, the entire encoding process can be further improved, for example, adding intra-frame or inter-frame decision conditions during fine calculation, and then according to the information already obtained during rough calculation and/or the current layer The information obtained by predictive coding of the lower layer sub-blocks of the coding block and the added decision conditions are selectively used for intra-frame or inter-frame prediction of the coding block of the current layer, which is described in detail below with reference to FIG. 7 .

1. Condition and process for judging whether to do inter-frame during fine calculation

The rate-distortion cost value corresponding to the inter 2N×2N prediction mode of the sub-coding blocks of the lower layer is estimated to be the rate-distortion cost value corresponding to the inter 2N×N prediction mode and the inter N×2N prediction mode of the coding block of the current layer. As an example of value, the description is as follows:

Step 1: Record the rate-distortion cost value cost_2N×2N obtained by using the inter-frame 2Nx2N prediction mode for each coding block during rough calculation.

Take a coding block as an example for illustration. Assuming that the coding block supports two inter-frame prediction modes, merge and amvp, you can obtain the satd value and bit value of the coding block (as a whole, not divided) in the merge prediction mode. , and then you can use the distortion cost formula: cost=satd+λ*bit to calculate the rate-distortion cost value of the coding block in the merge prediction mode, and obtain the satd value and bit value of the coding block in the amvp prediction mode, and then use the Rate-distortion cost formula: cost=satd+λ*bit Calculate the rate-distortion cost of the coding block in the amvp prediction mode. The obtained rate-distortion cost value is taken as the rate-distortion cost value of the coding block corresponding to the inter 2N×2N prediction mode.

Step2: Based on the information recorded during the rough calculation, determine the estimated value of the rate-distortion cost value of the coding block of the current layer corresponding to the inter-frame 2N×N prediction mode, and the coding block of the current layer corresponding to the inter-frame N×2N prediction mode. Estimated rate-distortion cost.

Specifically, determining the estimated value of the rate-distortion cost value of the coding block of the current layer corresponding to the inter-frame 2N×N prediction mode is taken as an example for illustration. First, the recorded information may include the rate-distortion cost value of the 4 sub-coding blocks of the coding block corresponding to the inter 2N×2N prediction mode, for example, the rate-distortion cost value of each sub-coding block in the merge prediction mode, and the rate-distortion cost value of each sub-coding block in the merge prediction mode. Rate-distortion cost of the coded block in amvp prediction mode. Then, based on the rate-distortion cost formula, it can be combined in the manner shown in (a) in Figure 8 to obtain the optimal rate-distortion cost value as the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode Similarly, according to the method of (b) in Figure 8, the optimal rate-distortion cost value is obtained as the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode .

Step3: Select the minimum value of cost from the rate-distortion cost value of the coding block of the current layer corresponding to the inter-frame 2N×2N prediction mode and the estimated value determined in Step2, if the minimum value is the inter-frame 2N×N prediction mode If the estimated value of the rate-distortion cost value is the estimated value of the rate-distortion cost value, the inter-frame 2NxN prediction is performed on the coding block; if the minimum value is the estimated value of the inter-frame N×2N rate-distortion cost value, the inter-frame Nx2N prediction is performed on the coding block; is the rate-distortion cost value of the inter-frame 2N×2N prediction mode, then the inter-frame calculation is no longer performed.

2. Determine whether to do the conditions and processes in the frame during fine calculation

For an 8×8 block, the conditions and process for judging whether to perform an intra-frame are shown in FIG. 9 .

Specifically, after inter-frame selection, the current layer cost is compared with the preset threshold. If the cost is less than or equal to the threshold thr1, no intra-frame calculation is performed, otherwise, intra-frame 2Nx2N is performed. After calculation and selection, if the optimal prediction mode of the coding block is the intra-frame prediction mode, the intra-frame N×N prediction is performed again, otherwise, the intra-frame N×N prediction is not performed. In this embodiment, the threshold thr1 may be set to 1000. Of course, other threshold conditions can also be added as the decision conditions for whether to perform intra-frame calculation, for example, when the inter-frame cost is less than thr1, and/or the motion vector residual (Motion Vector Difference, MVD) is less than thr2 (for example, set to 80) When , do not perform intra-frame calculation, otherwise continue to perform intra-frame calculation.

For non-8×8 blocks, the flowchart shown in FIG. 10 may be used to determine whether to perform intra-frame calculation.

After the coding block of the current layer is selected among the frames, the prediction modes of the four sub-coding blocks of the coding block are counted. If the prediction modes of the four sub-coding blocks are all inter-frame prediction modes, the intra-frame 2Nx2N prediction mode of the coding block is not performed, otherwise, the intra-frame prediction mode of the coding block may continue to be executed. Of course, when preparing to execute the intra-frame prediction mode of the coding block, the computational complexity of the intra-frame calculation can also be reduced in some ways. For example, it is possible to first determine whether there are 0 or 1 in the intra-frame direction in the four sub-coding blocks, and if there is a 0 or 1, do the intra-frame 2Nx2N prediction of the coding block, otherwise, the direction difference of the adjacent intra-frame sub-blocks can be calculated. If the neighbor is less than the threshold thr, intra-frame 2Nx2N prediction is performed, otherwise, intra-frame 2Nx2N prediction may not be performed, which is not specifically limited in this embodiment of the present invention.

The image encoding method according to the embodiment of the present invention is described in detail above with reference to FIG. 1 to FIG. 10 , and the image encoder according to the embodiment of the present invention will be described in detail below with reference to FIG. 11 to FIG. 12 . It should be understood that the image encoders in FIG. 11 and FIG. 12 can implement various steps of the image encoding methods in FIGS. 1 to 10 , and repeated descriptions are appropriately omitted for brevity.

FIG. 11 is a schematic block diagram of an image encoder according to an embodiment of the present invention. The image encoder 1100 of FIG. 11 includes:

a dividing module 1110, configured to divide the coding block to be coded into M sub-coding blocks, where the coding block is an image block of the image, and M is a positive integer greater than or equal to 2;

The obtaining module 1120 is configured to predict the coding block by using the inter-frame 2N×2N prediction mode, and obtain the first rate-distortion cost value of the coding block corresponding to the inter-frame 2N×2N prediction mode, using the inter-frame 2N×2N prediction mode The 2N prediction mode predicts the M sub-coding blocks divided by the dividing module 1110, and obtains the rate-distortion cost value of each sub-coding block in the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode. ;

The first determining module 1130 is configured to determine, according to the rate-distortion cost value of the M sub-coding blocks obtained by the obtaining module 1120 corresponding to the inter-frame 2N×2N prediction mode, that the coding block corresponds to the inter-frame 2N×N a first estimate of the rate-distortion cost value of the prediction mode, and determining that the coding block corresponds to the inter-frame N×2N prediction mode according to the rate-distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode A second estimate of the rate-distortion cost of ;

The second determining module 1140 is configured to determine according to the first rate-distortion cost value acquired by the acquiring module 1120, the first estimated value and the second estimated value determined by the first determining module 1130 the optimal prediction mode for the coding block;

The coding module 1150 is configured to perform predictive coding on the coding block according to the optimal prediction mode of the coding block determined by the second determining module 1140 .

The embodiment of the present invention divides the coding block into M sub-coding blocks, obtains the rate-distortion cost values of the coding block and the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, and obtains the rate-distortion cost values of the M sub-coding blocks according to the rate-distortion generation of the M sub-coding blocks. The value determines the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, and the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode. The rate-distortion cost value of the coding block and the determined estimated value of the rate-distortion cost value of the coding block, determine the optimal prediction mode of the coding block, and it is not necessary to use all prediction modes to predict the coding block as in the prior art. The optimal prediction mode of the coding block is selected, thereby reducing the coding complexity of the image.

Optionally, as an embodiment, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. The first determining module 1130 specifically for determining the upper left sub-coding block according to the rate-distortion cost value of the upper left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the upper right sub-coding block corresponding to the inter 2N×2N prediction mode The image block composed of the coding block and the upper right sub-coding block corresponds to the third estimated value of the rate-distortion cost value of the inter-frame 2N×N prediction mode; The rate-distortion cost value and the lower-right sub-coding block correspond to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and it is determined that the image block composed of the lower-left sub-coding block and the lower-right sub-coding block corresponds to the inter-frame 2N×2N A fourth estimate of the rate-distortion cost value of the N prediction mode; the first estimate is calculated based on the third estimate and the fourth estimate.

Optionally, as an embodiment, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. The first determining module 1130 specifically for determining the upper left sub-coding block according to the rate-distortion cost value of the upper left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the lower left sub-coding block corresponding to the inter 2N×2N prediction mode The image block composed of the coding block and the lower left sub-coding block corresponds to the fifth estimated value of the rate-distortion cost value of the inter-frame N×2N prediction mode; according to the upper right sub-coding block corresponding to the inter-frame 2N×2N prediction mode The rate-distortion cost value and the lower-right sub-coding block correspond to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and it is determined that the image block composed of the upper-right sub-coding block and the lower-right sub-coding block corresponds to the inter-frame N× a sixth estimate of a rate-distortion cost value for a 2N prediction mode; calculating the second estimate of the coding block based on the fifth estimate and the sixth estimate.

Optionally, as an embodiment, the second determining module 1140 is specifically configured to determine the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the When the inter-frame prediction mode corresponding to the minimum value is the inter-frame 2N×2N prediction mode, the inter-frame 2N×2N prediction mode is used as the optimal inter-frame prediction mode of the coding block; according to the optimal inter-frame prediction mode, determine the optimal prediction mode for the coding block.

Optionally, as an embodiment, the second determining module 1140 is specifically configured to determine the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the When the target inter-frame prediction mode corresponding to the minimum value is the inter-frame 2N×N prediction mode or the inter-frame N×2N prediction mode, the target inter-frame prediction mode is used to predict the coding block, and the corresponding coding block is obtained. the second rate-distortion cost value of the target inter-frame prediction mode; the inter-frame prediction mode corresponding to the smaller of the first rate-distortion cost value and the second rate-distortion cost value is used as the coding block the optimal inter-frame prediction mode; according to the optimal inter-frame prediction mode, determine the optimal prediction mode of the coding block.

Optionally, as an embodiment, the second determining module 1140 is specifically configured to, when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is less than or equal to a preset threshold, determine the The optimal inter-frame prediction mode is used as the optimal prediction mode; or, when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is greater than the preset threshold, use the intra-frame prediction mode to performing prediction on the coding block, obtaining a third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode, and comparing the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the The prediction mode corresponding to the smaller value of the third rate-distortion cost value is used as the optimal prediction mode of the coding block.

Optionally, as an embodiment, the second determining module 1140 is specifically configured to, when the optimal prediction modes of the M sub-coding blocks are all inter prediction modes, determine the optimal inter prediction mode as the optimal prediction mode of the coding block; or, when there is a sub-coding block whose optimal prediction mode is the intra-frame prediction mode in the M sub-coding blocks, use the intra-frame prediction mode to predict the coding block, and Obtain the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode, and set the coding block corresponding to the rate-distortion cost value of the optimal inter-frame prediction mode and the third rate-distortion cost value. The prediction mode corresponding to the smaller value is used as the optimal prediction mode of the coding block.

FIG. 12 is a schematic block diagram of an image encoder according to an embodiment of the present invention. The image encoder 1300 of FIG. 12 includes:

a memory 1210 for storing programs;

The processor 1220 is configured to execute the program. When the program is executed, the processor 1220 is specifically configured to divide the encoding block to be encoded into M sub-encoding blocks, where the encoding block is an image block of the image, and the encoding block is an image block of the image. M is a positive integer greater than or equal to 2; use the inter-frame 2N×2N prediction mode to predict the coding block, and obtain the first rate-distortion cost value of the coding block corresponding to the inter-frame 2N×2N prediction mode, using the frame The inter 2N×2N prediction mode predicts the M sub-coding blocks, and obtains the rate-distortion cost value of each sub-coding block in the M sub-coding blocks corresponding to the inter 2N×2N prediction mode; according to the M sub-coding blocks sub-coding blocks corresponding to rate-distortion cost values of the inter 2N×2N prediction mode, determining a first estimate of the rate-distortion cost values of the coding blocks corresponding to the inter 2N×N prediction mode, and determining according to the M sub-coding The block corresponds to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and the second estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode is determined; according to the obtained first rate The distortion cost value, the first estimated value and the second estimated value determine the optimal prediction mode of the coding block; and perform predictive coding on the coding block according to the optimal prediction mode of the coding block.

The embodiment of the present invention divides the coding block into M sub-coding blocks, obtains the rate-distortion cost values of the coding block and the M sub-coding blocks corresponding to the inter-frame 2N×2N prediction mode, and obtains the rate-distortion cost values of the M sub-coding blocks according to the rate-distortion generation of the M sub-coding blocks. The value determines the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame 2N×N prediction mode, and the estimated value of the rate-distortion cost value of the coding block corresponding to the inter-frame N×2N prediction mode. The rate-distortion cost value of the coding block and the determined estimated value of the rate-distortion cost value of the coding block, determine the optimal prediction mode of the coding block, and it is not necessary to use all prediction modes to predict the coding block as in the prior art. The optimal prediction mode of the coding block is selected, thereby reducing the coding complexity of the image.

Optionally, as an embodiment, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. The processor 1220 is specifically configured to The upper left sub-coding block is determined according to the rate-distortion cost value of the upper-left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the upper-right sub-coding block corresponding to the inter 2N×2N prediction mode The image block formed with the upper right sub-coding block corresponds to the third estimated value of the rate-distortion cost value of the inter 2N×N prediction mode; according to the lower left sub-coding block corresponding to the rate-distortion of the inter 2N×2N prediction mode The cost value and the lower right sub-coding block correspond to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and it is determined that the image block composed of the lower-left sub-coding block and the lower-right sub-coding block corresponds to the inter-frame 2N×N prediction a fourth estimate of the rate-distortion cost value of the mode; the first estimate is calculated based on the third estimate and the fourth estimate.

Optionally, as an embodiment, the M is 4, and the M sub-coding blocks include an upper-left sub-coding block, an upper-right sub-coding block, a lower-left sub-coding block, and a lower-right sub-coding block. The processor 1220 is specifically configured to The upper left sub-coding block is determined according to the rate-distortion cost value of the upper left sub-coding block corresponding to the inter 2N×2N prediction mode and the rate-distortion cost value of the lower left sub-coding block corresponding to the inter 2N×2N prediction mode The image block formed with the lower left sub-coding block corresponds to the fifth estimate of the rate-distortion cost value of the inter-frame N×2N prediction mode; The cost value and the lower right sub-coding block correspond to the rate-distortion cost value of the inter-frame 2N×2N prediction mode, and it is determined that the image block composed of the upper-right sub-coding block and the lower-right sub-coding block corresponds to the inter-frame N×2N prediction a sixth estimate of the rate-distortion cost value of the mode; and calculating the second estimate of the coded block based on the fifth estimate and the sixth estimate.

Optionally, as an embodiment, the processor 1220 is specifically configured to determine the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the minimum value is When the corresponding inter-frame prediction mode is the inter-frame 2N×2N prediction mode, the inter-frame 2N×2N prediction mode is used as the optimal inter-frame prediction mode of the coding block; according to the optimal inter-frame prediction mode, determine the The optimal prediction mode for the coded block.

Optionally, as an embodiment, the processor 1220 is specifically configured to determine the minimum value among the first rate-distortion cost value, the first estimated value, and the second estimated value; when the minimum value is When the corresponding target inter-frame prediction mode is the inter-frame 2N×N prediction mode or the inter-frame N×2N prediction mode, use the target inter-frame prediction mode to predict the coding block, and obtain the coding block corresponding to the the second rate-distortion cost value of the target inter-frame prediction mode; the inter-frame prediction mode corresponding to the smaller value of the first rate-distortion cost value and the second rate-distortion cost value is taken as the maximum value of the coding block. an optimal inter-frame prediction mode; according to the optimal inter-frame prediction mode, an optimal prediction mode for the coding block is determined.

Optionally, as an embodiment, the processor 1220 is specifically configured to, when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is less than or equal to a preset threshold The inter-frame prediction mode is used as the optimal prediction mode; or, when the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is greater than the preset threshold, use the intra-frame prediction mode to The coding block is predicted, and the third rate-distortion cost value of the coding block corresponding to the intra-frame prediction mode is obtained, and the rate-distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate-distortion cost value corresponding to the optimal inter-frame prediction mode are obtained. The prediction mode corresponding to the smaller value of the rate-distortion cost value is used as the optimal prediction mode for the coding block.

Optionally, as an embodiment, the processor 1220 is specifically configured to, when the optimal prediction modes of the M sub-coding blocks are all inter prediction modes, determine the optimal inter prediction mode as the the optimal prediction mode of the coding block; or, when there is a sub-coding block whose optimal prediction mode is the intra-frame prediction mode in the M sub-coding blocks, use the intra-frame prediction mode to predict the coding block, and obtain the The coding block corresponds to the third rate-distortion cost value of the intra prediction mode, and the coding block corresponds to the smaller of the rate-distortion cost value of the optimal inter-frame prediction mode and the third rate-distortion cost value. The prediction mode corresponding to the value is used as the optimal prediction mode for the coding block.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described systems, devices and units may refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, Read-Only Memory (ROM, Read-Only Memory), Random Access Memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes .

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (14)

1. An image encoding method, comprising:

dividing a coding block to be coded into M sub-coding blocks, wherein the coding block is an image block of the image, and M is a positive integer greater than or equal to 2;

predicting the coding block by using an inter-frame 2Nx2N prediction mode, and acquiring a first rate distortion cost value of the coding block corresponding to the inter-frame 2Nx2N prediction mode;

predicting the M sub-coding blocks by using an inter-frame 2Nx2N prediction mode, and acquiring rate distortion cost values of each sub-coding block in the M sub-coding blocks, which respectively correspond to the inter-frame 2Nx2N prediction mode;

determining a first estimation value of the rate distortion cost value of the coding block corresponding to the inter-frame 2NxN prediction mode according to the rate distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2NxN prediction mode;

determining a second estimation value of the rate distortion cost value of the coding block corresponding to the inter-frame Nx2N prediction mode according to the rate distortion cost value of the M sub-coding blocks corresponding to the inter-frame 2Nx2N prediction mode;

determining an optimal prediction mode of the coding block according to the first rate distortion cost value, the first estimation value and the second estimation value;

and performing predictive coding on the coding block according to the optimal prediction mode of the coding block.

2. The method of claim 1, wherein M is 4, and the M sub-coding blocks comprise an upper left sub-coding block, an upper right sub-coding block, a lower left sub-coding block, and a lower right sub-coding block;

the determining a first estimate of the rate-distortion cost value of the coding block corresponding to the inter 2nx2N prediction mode according to the rate-distortion cost values of the M sub-coding blocks corresponding to the inter 2nx2N prediction mode comprises:

determining a third estimation value of the rate distortion cost value of the image block formed by the upper left sub-coding block and the upper right sub-coding block corresponding to the inter-frame 2NxN prediction mode according to the rate distortion cost value of the upper left sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate distortion cost value of the upper right sub-coding block corresponding to the inter-frame 2NxN prediction mode;

determining a fourth estimation value of the rate distortion cost value of the image block formed by the left lower sub-coding block and the right lower sub-coding block corresponding to the inter-frame 2NxN prediction mode according to the rate distortion cost value of the left lower sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate distortion cost value of the right lower sub-coding block corresponding to the inter-frame 2NxN prediction mode;

and calculating the first estimation value according to the third estimation value and the fourth estimation value.

3. The method of claim 1 wherein M is 4, wherein the M sub-coding blocks comprise an upper left sub-coding block, an upper right sub-coding block, a lower left sub-coding block, and a lower right sub-coding block, and wherein determining a second estimate of the rate-distortion cost value of the coding block corresponding to the inter nx2N prediction mode based on the rate-distortion cost values of the M sub-coding blocks corresponding to the inter 2nx2N prediction mode comprises:

determining a fifth estimation value of the rate distortion cost value of the image block formed by the upper left sub-coding block and the lower left sub-coding block corresponding to the inter-frame Nx2N prediction mode according to the rate distortion cost value of the upper left sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate distortion cost value of the lower left sub-coding block corresponding to the inter-frame 2Nx2N prediction mode;

according to the rate-distortion cost value of the upper right sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate-distortion cost value of the lower right sub-coding block corresponding to the inter-frame 2Nx2N prediction mode, determining a sixth estimation value of the rate-distortion cost value of the image block formed by the upper right sub-coding block and the lower right sub-coding block corresponding to the inter-frame Nx2N prediction mode;

and calculating the second estimation value of the coding block according to the fifth estimation value and the sixth estimation value.

4. The method of claim 1, wherein determining the optimal prediction mode for the coding block based on the first rate-distortion cost value, the first estimate, and the second estimate comprises:

determining a minimum of the first rate-distortion cost value, the first estimate, and the second estimate;

when the inter-frame prediction mode corresponding to the minimum value is an inter-frame 2Nx2N prediction mode, taking the inter-frame 2Nx2N prediction mode as the optimal inter-frame prediction mode of the coding block;

and determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode.

5. The method of claim 1, wherein determining the optimal prediction mode for the coding block based on the first rate-distortion cost value, the first estimate, and the second estimate comprises:

determining a minimum of the first rate-distortion cost value, the first estimate, and the second estimate;

when the target inter-frame prediction mode corresponding to the minimum value is an inter-frame 2NxN prediction mode or an inter-frame Nx2N prediction mode, predicting the coding block by using the target inter-frame prediction mode, and obtaining a second rate distortion cost value of the coding block corresponding to the target inter-frame prediction mode;

taking the inter-frame prediction mode corresponding to the smaller value of the first rate distortion cost value and the second rate distortion cost value as the optimal inter-frame prediction mode of the coding block;

and determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode.

6. The method of claim 4 or 5, wherein the determining the optimal prediction mode for the coding block based on the optimal inter prediction mode for the coding block comprises:

when the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is smaller than or equal to a preset threshold value, taking the optimal inter-frame prediction mode as the optimal prediction mode; or,

when the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is larger than the preset threshold value, predicting the coding block by using an intra-frame prediction mode, acquiring a third rate distortion cost value of the coding block corresponding to the intra-frame prediction mode, and taking a prediction mode corresponding to the smaller value of the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate distortion cost value as the optimal prediction mode of the coding block.

7. The method of claim 4 or 5, wherein the determining the optimal prediction mode for the coding block based on the optimal inter prediction mode for the coding block comprises:

when the optimal prediction modes of the M sub-coding blocks are all inter-frame prediction modes, determining the optimal inter-frame prediction mode as the optimal prediction mode of the coding block; or,

when a sub-coding block with the optimal prediction mode being an intra-frame prediction mode exists in the M sub-coding blocks, the intra-frame prediction mode is used for predicting the coding block, a third rate distortion cost value of the coding block corresponding to the intra-frame prediction mode is obtained, and the prediction mode corresponding to the smaller value of the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate distortion cost value is used as the optimal prediction mode of the coding block.

8. An image encoder, comprising:

the device comprises a dividing module, a coding module and a decoding module, wherein the dividing module is used for dividing a coding block to be coded into M sub-coding blocks, the coding block is an image block of the image, and M is a positive integer greater than or equal to 2;

an obtaining module, configured to predict the coding block using an inter-frame 2nx2N prediction mode, obtain a first rate-distortion cost value of the coding block corresponding to the inter-frame 2nx2N prediction mode, predict the M sub-coding blocks obtained by dividing by the dividing module using the inter-frame 2nx2N prediction mode, and obtain a rate-distortion cost value of each of the M sub-coding blocks corresponding to the inter-frame 2nx2N prediction mode;

a first determining module, configured to determine, according to the rate-distortion cost values of the M sub-coding blocks obtained by the obtaining module, corresponding to the inter-frame 2nx2N prediction mode, a first estimation value of the rate-distortion cost values of the coding blocks corresponding to the inter-frame 2nx2N prediction mode, and determine, according to the rate-distortion cost values of the M sub-coding blocks corresponding to the inter-frame 2nx2N prediction mode, a second estimation value of the rate-distortion cost values of the coding blocks corresponding to the inter-frame 2nx2N prediction mode;

a second determining module, configured to determine an optimal prediction mode of the coding block according to the first rate-distortion cost value obtained by the obtaining module, the first estimation value and the second estimation value determined by the first determining module;

and the coding module is used for carrying out predictive coding on the coding block according to the optimal prediction mode of the coding block determined by the second determining module.

9. The image encoder of claim 8, wherein M is 4, the M sub-coding blocks comprise an upper left sub-coding block, an upper right sub-coding block, a lower left sub-coding block, and a lower right sub-coding block, and the first determining module is specifically configured to determine a third estimate of the rate-distortion cost value of the image block consisting of the upper left sub-coding block and the upper right sub-coding block corresponding to the inter 2nx2N prediction mode based on the rate-distortion cost value of the upper left sub-coding block corresponding to the inter 2nx2N prediction mode and the rate-distortion cost value of the upper right sub-coding block corresponding to the inter 2nx2N prediction mode; determining a fourth estimation value of the rate distortion cost value of the image block formed by the left lower sub-coding block and the right lower sub-coding block corresponding to the inter-frame 2NxN prediction mode according to the rate distortion cost value of the left lower sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate distortion cost value of the right lower sub-coding block corresponding to the inter-frame 2NxN prediction mode; and calculating the first estimation value according to the third estimation value and the fourth estimation value.

10. The image encoder of claim 8, wherein M is 4, the M sub-coding blocks comprise an upper left sub-coding block, an upper right sub-coding block, a lower left sub-coding block, and a lower right sub-coding block, and the first determining module is specifically configured to determine a fifth estimate of the rate-distortion cost value of the image block consisting of the upper left sub-coding block and the lower left sub-coding block corresponding to the inter-nx 2N prediction mode based on the rate-distortion cost value of the upper left sub-coding block corresponding to the inter-2 nx2N prediction mode and the rate-distortion cost value of the lower left sub-coding block corresponding to the inter-2 nx2N prediction mode; according to the rate-distortion cost value of the upper right sub-coding block corresponding to the inter-frame 2Nx2N prediction mode and the rate-distortion cost value of the lower right sub-coding block corresponding to the inter-frame 2Nx2N prediction mode, determining a sixth estimation value of the rate-distortion cost value of the image block formed by the upper right sub-coding block and the lower right sub-coding block corresponding to the inter-frame Nx2N prediction mode; and calculating the second estimation value of the coding block according to the fifth estimation value and the sixth estimation value.

11. The image encoder of claim 8, wherein the second determination module is specifically configured to determine a minimum of the first rate-distortion cost value, the first estimate, and the second estimate; when the inter-frame prediction mode corresponding to the minimum value is an inter-frame 2Nx2N prediction mode, taking the inter-frame 2Nx2N prediction mode as the optimal inter-frame prediction mode of the coding block; and determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode.

12. The image encoder of claim 8, wherein the second determination module is specifically configured to determine a minimum of the first rate-distortion cost value, the first estimate, and the second estimate; when the target inter-frame prediction mode corresponding to the minimum value is an inter-frame 2NxN prediction mode or an inter-frame Nx2N prediction mode, predicting the coding block by using the target inter-frame prediction mode, and obtaining a second rate distortion cost value of the coding block corresponding to the target inter-frame prediction mode; taking the inter-frame prediction mode corresponding to the smaller value of the first rate distortion cost value and the second rate distortion cost value as the optimal inter-frame prediction mode of the coding block; and determining the optimal prediction mode of the coding block according to the optimal inter-frame prediction mode.

13. The image encoder according to claim 11 or 12, wherein the second determining module is specifically configured to take the optimal inter prediction mode as the optimal prediction mode when a rate-distortion cost value of the coding block corresponding to the optimal inter prediction mode is smaller than or equal to a preset threshold; or when the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode is larger than the preset threshold value, predicting the coding block by using an intra-frame prediction mode, acquiring a third rate distortion cost value of the coding block corresponding to the intra-frame prediction mode, and taking the prediction mode corresponding to the smaller value of the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate distortion cost value as the optimal prediction mode of the coding block.

14. The image encoder according to claim 11 or 12, wherein the second determining module is specifically configured to determine the optimal inter prediction mode as the optimal prediction mode of the coding block when the optimal prediction modes of the M sub-coding blocks are all inter prediction modes; or when a sub-coding block of which the optimal prediction mode is the intra-frame prediction mode exists in the M sub-coding blocks, predicting the coding block by using the intra-frame prediction mode, acquiring a third rate distortion cost value of the coding block corresponding to the intra-frame prediction mode, and taking the prediction mode corresponding to the smaller value of the rate distortion cost value of the coding block corresponding to the optimal inter-frame prediction mode and the third rate distortion cost value as the optimal prediction mode of the coding block.