Adaptive quantization parameter encoding and decoding method and device based upon quad tree structure

Abstract

To provide a video encoding / decoding method and device enabling a quantization parameter differential value to be allocated to various levels when a block is segmented into a quad tree structure.SOLUTION: There is provided a method and device that records a quantization parameter differential value based on a quadtree segmentation in a largest coding unit (LCU), and adaptively predicting a quantization parameter value based on context information of a neighboring coding unit (CU). The method and device are configured to: effectively present block information having the quantization parameter differential value based on segmentation information of the CU; and, when predicting the quantization parameter value, perform an adaptive prediction utilizing the context information on the neighboring CU such as block size, block segmentation, quantization parameter value, etc.SELECTED DRAWING: Figure 1b

Description

[Technical Field]

[0001] The present invention relates to a video encoding / decoding apparatus and method, and more particularly to a video encoding / decoding method and apparatus that displays blocks having quantization / dequantization differential values ​​based on a quad tree structure for a coding unit (CU) in a largest coding unit (LCU), and adaptively predicts / decodes quantization / dequantization parameter values ​​using context information of blocks located around the block to be encoded / decoded.

[0002] HEVC encodes / decodes input video in units of coding units (CUs). The largest CU in a frame is called the Largest Coding Unit (LCU), and such an LCU can be divided into multiple CUs based on quadtree partitioning information before encoding / decoding. HEVC assigns one quantization parameter value to each LCU, and the quantization parameter value of the LCU to be currently encoded is predicted by the previous LCU based on the raster scan order. [Background technology]

[0003] In H.264 / AVC, encoding / decoding is performed in units of macroblocks, and quantization / dequantization values ​​are assigned to each macroblock. The quantization parameter value assigned to each macroblock is predicted from the quantization parameter value of the macroblock located to the left of the macroblock in the frame. Encoding is performed by recording the corresponding value in the macroblock to be encoded for the difference value generated after the quantization parameter value prediction process. The decoder decodes the quantization parameter value by adding the quantization parameter difference value decoded in the entropy decoding step to the quantization parameter value of the macroblock located to the left.

[0004] However, when a relatively large LCU is assigned compared to the size of the input image, it is not possible to effectively control the bit rate using the quantization parameter value recorded in units of LCU. Also, when a quantization parameter value is assigned in units of CU, a problem occurs in that the subjective image quality is reduced due to the difference in the quantization parameter value between neighboring CUs. Therefore, it is necessary to assign quantization parameter values ​​to various block sizes from CU to LCU units according to the input image, and to optimize the prediction direction of the quantization parameter using context information of blocks neighboring the block to be encoded. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method and apparatus for encoding / decoding quantization / dequantization parameter values ​​based on various quad-tree structures based on CU partition information. The present invention also provides a method and apparatus for predicting quantization / dequantization parameter values ​​in an effective direction using context information of neighboring blocks.

[0006] The problems to be solved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not described will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0007] To solve the above problem, an image encoding device according to an embodiment of the present invention includes a quantization differential value recording block unit determination unit that determines a block unit in which a quantization parameter differential value is recorded when an LCU in an image is divided into a plurality of CUs in a quad tree form or is encoded into a single CU; a quantization unit that performs quantization using a quantization value assigned to each block unit; a quantization prediction block determination unit that adaptively determines a prediction block using context information of neighboring blocks to predict a quantization value used in a block to be encoded; a quantization parameter differential value generation unit that generates a quantization differential value of a block to be encoded using a quantization parameter of the prediction block obtained based on the context information; and a quantization parameter recording unit that records division information for the quantization differential value recording block unit and the quantization parameter differential value of the corresponding block.

[0008] To solve the above problem, a video decoding apparatus according to an embodiment of the present invention includes an inverse quantization parameter difference value block division flag derivation unit that decodes information on a block having an inverse quantization parameter difference value in units of an LCU, an inverse quantization parameter difference value recording block unit determination unit that determines a block unit in which an inverse quantization parameter difference value is recorded within an LCU using the decoded inverse quantization parameter difference value block division flag, an inverse quantization parameter difference value derivation unit that decodes an inverse quantization parameter difference value according to the inverse quantization parameter difference value block division flag, an inverse quantization parameter value prediction block determination unit that determines a block used for prediction to decode an inverse quantization parameter value of a block to be decoded using context information of neighboring blocks, an inverse quantization parameter value derivation unit that decodes an inverse quantization parameter value used in the inverse quantization process, and an inverse quantization unit that performs inverse quantization using the decoded inverse quantization parameter value. [Effects of the Invention]

[0009] The method and apparatus for adaptively encoding and decoding quantization / dequantization parameters based on a quad-tree structure according to an embodiment of the present invention allows for the allocation of quantization parameter difference values ​​to various levels when a block is divided into a quad-tree structure. The allocation of quantization parameter difference values ​​at various levels allows for more precise bit rate adjustment than the allocation of a single quantization parameter value per LCU. Furthermore, when predicting / decoding block-based quantization / dequantization parameter values, the method and apparatus adaptively determine a prediction direction using context information of neighboring blocks in addition to the zigzag scan method based on the quad-tree structure, thereby solving the problem of subjective image quality degradation caused by a large difference in quantization value between neighboring blocks. [Brief explanation of the drawings]

[0010] [Figure 1a] As a first embodiment of the present invention, a method and apparatus for adaptively assigning quantization parameter values ​​to blocks having a quadtree structure in a video encoding device and encoding the blocks will be described. [Figure 1b] As a first embodiment of the present invention, a method and apparatus for adaptive dequantization parameter decoding based on a quadtree structure in a video decoding device will be described. [Figure 2] The configuration of a video decoding device according to a first embodiment of the present invention is shown. [Figure 3] 1 shows a context for quantization difference value control based on a quadtree structure recorded in a sequence parameter set according to a first embodiment of the present invention. [Figure 4a] 4 shows variables that are set to initial values ​​in slice data according to the first embodiment of the present invention. [Figure 4b] 4 shows variables that are set to initial values ​​in slice data according to the first embodiment of the present invention. [Figure 5] 10 illustrates quantization / dequantization parameter difference values ​​recorded in units of CUs according to the first embodiment of the present invention and the context of the conditions under which the corresponding difference values ​​exist. [Figure 6a]10 shows the operations of a quantization difference value recording block unit determination unit and an inverse quantization difference value recording block unit determination unit according to an embodiment of the present invention. [Figure 6b] 10 shows the operations of a quantization difference value recording block unit determination unit and an inverse quantization difference value recording block unit determination unit according to an embodiment of the present invention. [Figure 6c] 10 shows the operations of a quantization difference value recording block unit determination unit and an inverse quantization difference value recording block unit determination unit according to an embodiment of the present invention. [Figure 7a] 1 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a first embodiment of the present invention. [Figure 7b] 1 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a first embodiment of the present invention. [Figure 8a] 10 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a second embodiment of the present invention. [Figure 8b] 10 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a second embodiment of the present invention. [Figure 9a] 10 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a third embodiment of the present invention. [Figure 9b] 10 shows a quantization parameter value prediction block determiner and an inverse quantization parameter value prediction block determiner according to a third embodiment of the present invention. [Figure 10a] 10 shows a quantization parameter value prediction block determination unit 102 and an inverse quantization parameter value prediction block determination unit 123 according to a fourth embodiment of the present invention. [Figure 10b] 10 shows a quantization parameter value prediction block determination unit 102 and an inverse quantization parameter value prediction block determination unit 123 according to a fourth embodiment of the present invention. [Figure 11a] 10 shows a quantization parameter value prediction block determination unit and an inverse quantization parameter value prediction block determination unit according to a fifth embodiment of the present invention. [Figure 11b]10 shows a quantization parameter value prediction block determination unit and an inverse quantization parameter value prediction block determination unit according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an apparatus for encoding and decoding adaptive quantization / dequantization parameters based on a quadtree structure according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] FIG. 1a shows a method and apparatus for adaptively assigning quantization parameter values ​​to a block having a quadtree structure in a video encoding device and encoding the block, as a first embodiment of the present invention.

[0013] Referring to FIG. 1a, the adaptive quantization parameter encoding method and apparatus based on a quad-tree structure includes a quantization difference value recording block unit determination unit 100, a quantization unit 101, a quantization parameter value prediction block determination unit 102, a quantization parameter difference value generation unit 103, and a quantization parameter recording unit 104.

[0014] The quantization difference value recording block unit determination unit 100 determines a block unit based on CU division information of a corresponding LCU in an image so that the quantization difference value can be recorded for each CU unit or a group of multiple CUs. Information on the block for recording the quantization difference value can be configured in a quad tree structure.

[0015] The quantization unit 101 performs quantization on an input block using the value of a quantization parameter assigned to the block.

[0016] The quantization parameter value prediction block determination unit 102 determines a prediction block to be used for predicting a quantization value by using context information of CUs located around a corresponding CU in order to effectively encode a quantization value assigned to each CU or an arbitrary CU. The context information includes the size of the block, the position of the block, and a prediction mode of the block.

[0017] The quantization parameter difference value generating unit 103 generates a quantization parameter difference value by subtracting the quantization parameter value of the current block from the quantization parameter value of the quantization value prediction block determined by the quantization parameter value prediction block determining unit 102 .

[0018] The quantization parameter recording unit 104 provides a sequence parameter set, flag information applied / not applied to each slice, flag information used to indicate division information of a block including a quantization differential value in an LCU, and a quantization parameter differential value for adaptive quantization parameter coding based on a quad tree structure.

[0019] FIG. 1b shows a method and apparatus for adaptive dequantization parameter decoding based on a quadtree structure in a video decoding device as a first embodiment of the present invention.

[0020] Referring to FIG. 1b, the adaptive inverse quantization parameter decoding method and apparatus based on a quad-tree structure includes an inverse quantization parameter difference value block division flag derivation unit 120, an inverse quantization difference value recording block unit determination unit 121, an inverse quantization parameter difference value derivation unit 122, an inverse quantization parameter value prediction block determination unit 123, an inverse quantization parameter value derivation unit 124, and an inverse quantization unit 125.

[0021] The inverse quantization parameter difference value block division flag derivation unit 120 decodes a sequence parameter set and a block division flag for a block having an inverse quantization parameter difference value in LCU units in slice data.

[0022] The inverse quantization differential value recording block unit determination unit 121 determines a block in which the inverse quantization parameter differential value is to be recorded, using the decoded inverse quantization parameter differential value block division flag and the CU division flag. Information on the block in which the quantization differential value is to be recorded is configured in a quad tree structure.

[0023] The inverse quantization parameter difference value derivation unit 122 derives an inverse quantization parameter difference value for each block determined by the inverse quantization difference value recording block unit determination unit 121 .

[0024] The inverse quantization parameter value prediction block determination unit 123 adaptively determines a block to reference when performing inverse quantization using context information of neighboring blocks, such as the size, position, and prediction mode of the block.

[0025] The inverse quantization parameter value derivation unit 124 derives an inverse quantization parameter value to be used by the inverse quantization unit 125 by adding the inverse quantization parameter value of the predicted block calculated via the inverse quantization parameter value prediction block determination unit 123 and the inverse quantization parameter difference value calculated by the inverse quantization parameter difference value derivation unit 122.

[0026] The inverse quantization unit 125 performs inverse quantization on the input block using the parameters calculated by the inverse quantization parameter value derivation unit 124 and the like.

[0027] FIG. 2 shows the configuration of a video decoding device according to a first embodiment of the present invention.

[0028] Referring to FIG. 2, the video decoding apparatus includes an entropy decoding unit 200, a quadtree-based inverse quantization parameter derivation unit 210, a reordering unit 220, an inverse quantization unit 230, an inverse discrete cosine transform coding unit 240, an intra / inter prediction unit 250, and a filtering unit 260.

[0029] The entropy decoding unit 200 includes an inverse quantization parameter difference value block division flag derivation unit 120 that derives a block division flag used for adaptive inverse quantization based on a quad tree structure, an inverse quantization difference value recording block unit determination unit 121 that determines a block in which a quantization parameter is recorded from the derived block division flag, and an inverse quantization parameter difference value derivation unit 122 that decodes an inverse quantization parameter difference value recorded in the corresponding block.

[0030] The quad-tree-based inverse quantization parameter derivation unit 210 includes an inverse quantization parameter value prediction block determination unit 123 that determines a prediction block to be referenced when decoding the inverse quantization parameter, and an inverse quantization parameter value derivation unit 124 that calculates the inverse quantization parameter by adding the inverse quantization parameter of the prediction block and the derived inverse quantization parameter difference value, and the corresponding block plays a role of restoring the inverse quantization parameter for a block of a quad-tree structure.

[0031] FIG. 3 shows a context for quantization difference value control based on a quadtree structure recorded in a sequence parameter set according to a first embodiment of the present invention.

[0032] If the value of cu_qp_delta_enabled_flag(300) in the sequence parameter set is 1, it means that the quantization / dequantization parameter difference values ​​can be controlled for various quad tree blocks from the smallest CU to the largest CU in all slices in the sequence.

[0033] FIG. 4a shows variables that are set to initial values ​​in slice data according to a first embodiment of the present invention.

[0034] When a slice is divided into a quad tree structure and encoded / decoded, it is first divided into LCU units, which are quad trees of the largest size, and encoding / decoding is performed on the corresponding LCUs in the order of progressive scanning. When encoding / decoding each LCU, the corresponding LCU may be divided into multiple CU regions based on the quad tree structure again, and this division process may be performed up to the size of the smallest CU.

[0035] 4a, isCuQpDeltaCoded400 is a variable for controlling the quantization / dequantization parameter difference value that can be recorded in each CU when any CU is again divided into N CUs. This value is always initialized to 0 before performing encoding / decoding for each LCU in a slice.

[0036] In Figure 4a, the coding_tree 401 function is a function that performs encoding / decoding for one LCU within a slice. The fourth factor value of this function is a flag indicating whether a quantization / dequantization parameter difference value exists within the corresponding CU. Since at least one quantization / dequantization parameter difference value is recorded per LCU, this value is always set to 1 before performing encoding / decoding for each LCU within a slice.

[0037] FIG. 4b shows a context for block division of inverse quantization parameter difference values ​​recorded in a coding tree block according to a first embodiment of the present invention.

[0038] The coding tree block represents the context for a CU. A 2Nx2N CU is split into four NxN CUs by the split_coding_unit_flag 420 and then coded / decoded. Alternatively, the CU is not split into smaller CUs and is coded / decoded as a 2Nx2N CU, which is the current size.

[0039] The current CU receives cu_qp_delta_exist_flag 421, which is a flag indicating whether a quantization / dequantization parameter difference value exists in a higher-level CU. When the current CU, which has a size of 2Nx2N, is split again into NxN CUs according to the value of split_coding_unit_flag 420, split_qp_delta_flag 422 is additionally coded / decoded. This additional division information is coded / decoded only when the value of cu_qp_delta_enable_flag 300 recorded in the sequence parameter set and cu_qp_delta_exist_flag 421 input from the higher CU are set to 1. The value of split_qp_delta_flag 422 is coded / decoded only when the current CU, which has a size of 2Nx2N, is split into NxN CUs, and this value is input as the value of cu_qp_delta_exist_flag 421 when coding / decoding a lower-level CU, which has a size of NxN.

[0040] If the value of split_qp_detla_flag 422 is 0, the current CU of 2N×2N size is divided into CUs of N×N size, but the size of the block for recording the quantization / dequantization parameter difference value is not further divided from 2N×2N to blocks of N×N size. If the value of split_qp_detla_flag 422 is 0, the value of IsCuQpDeltaCoded 400 is additionally initialized to 0 so that when the current CU is divided into CUs of N×N size, the quantization / dequantization parameter difference value is recorded only in the first N×N CU.

[0041] FIG. 5 illustrates quantization / dequantization parameter difference values ​​recorded in units of CUs according to the first embodiment of the present invention and the context of the conditions under which the corresponding difference values ​​exist.

[0042] If a CU is not in skip mode, a quantization / dequantization parameter difference value is recorded in the CU. If the values ​​of cu_qp_delta_exist_flag 500 and 421 are 1, this means that a quantization / dequantization parameter difference value exists in the current CU, and in this case, the value of cu_qp_delta 501 is recorded on a CU-by-CU basis according to the value of cu_qp_delta_enabled_flag 300 recorded in the sequence parameter set. For example, if the values ​​of cu_qp_delta_exist_flag 500 and 421 are 1 and the value of cu_qp_delta_enabled_flag 300 is 0, cu_qp_delta 501 is not recorded.

[0043] As another example, when a 2Nx2N CU is split into four NxN CUs in a quadtree structure, only one quantization / dequantization parameter difference value can be recorded. In this case, the quantization / dequantization parameter difference value is recorded in the first CU of the four CUs, and no quantization / dequantization parameter difference value is recorded in the remaining three CUs. In this case, the value of split_qp_delta_flag 422, which is encoded / decoded in the 2Nx2N CU, is 0, so the value of cu_qp_delta_exist_flag 500 input to the NxN CU is 0. Therefore, although cu_qp_delta 501 does not exist in the four split NxN CUs, the IsCuQpDeltaCoded variable can be used to record the cu_qp_delta 501 value in the first NxN CU. For the remaining three CUs, the first CU changes the IsCuQpDeltaCoded value to 1 after decoding cu_qp_delta 501, and therefore the cu_qp_delta 501 value is not recorded.

[0044] In this case, the value condition of cu_qp_delta_enabled_flag 300 recorded in the sequence parameter set is checked at the same time, and only if the value is 1, the value of cu_qp_delta 501 can be recorded.

[0045] FIG. 6a shows the operations of the quantization difference value recording block unit determination unit 100 and the inverse quantization difference value recording block unit determination unit 121 according to the first embodiment of the present invention.

[0046] A 2Nx2N LCU to be encoded / decoded is divided into four NxN CUs, and each CU is divided again for processing. Even if a 2Nx2N LCU is divided into multiple CUs for encoding / decoding, if the value of split_qp_delta_flag 422 is 0 as shown in Figure 6a, the quantization / dequantization parameter difference value is recorded in the first CU of the LCU. The remaining CUs of the LCU use the quantization / dequantization parameter value restored in the first CU as is.

[0047] FIG. 6b shows the operations of the quantization difference value recording block unit determination unit 100 and the inverse quantization difference value recording block unit determination unit 121 according to the second embodiment of the present invention.

[0048] A 2Nx2N LCU to be coded / decoded is divided into four CUs in the first step, and the second CU of the CUs is split again. In this case, when a flag for CU splitting is coded / decoded in the first step, split_qp_delta_flag 422 and 630, which are split flags for quantization / dequantization parameter values, are additionally coded / decoded. If the value is 1, it means that all four divided CUs have quantization / dequantization parameter differential values, so split flags split_qp_delta_flag 422 and 631 for quantization / dequantization parameter values ​​are additionally coded / decoded in this step.

[0049] Even in this case, the second NxN CU is split up to the third step, but because the block split flags for quantization / dequantization, split_qp_delta_flag 422 and 631, are 0, one quantization / dequantization parameter value is assigned to multiple CUs.

[0050] FIG. 6c shows the operations of the quantization difference value recording block unit determination unit 100 and the inverse quantization difference value recording block unit determination unit 121 according to the third embodiment of the present invention.

[0051] Figure 6c shows a case where a 2Nx2N LCU to be encoded / decoded is divided into four CUs in the first step, and the second CU of the CUs is divided again. Even if the second CU is divided into four CUs again and the divided CU is divided into four CUs again, the size of the block in which the quantization / dequantization parameter difference values ​​are recorded can be determined based on the values ​​of split_qp_delta_flag 422 and 661. Figure 6c shows that a CU is divided into up to three pieces of depth information, but the quantization / dequantization parameter difference values ​​have up to two pieces of depth information.

[0052] FIG. 7a shows the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the first embodiment of the present invention.

[0053] The encoder assigns quantization parameter values ​​to the CU blocks determined by the quantization differential value recording block unit determination unit 100, and uses previously used quantization parameter values ​​for the remaining CU blocks. In this case, the quantization parameter values ​​are predicted using the quantization parameter values ​​of the previous blocks, and only the quantization parameter differential values ​​are actually coded.

[0054] In the decoder, the inverse quantization parameter difference value derivation unit 122 decodes the inverse quantization parameter difference value, and then calculates the inverse quantization parameter value by adding the corresponding difference value to the inverse quantization parameter value of the block used for prediction.

[0055] The quantization parameter value prediction block determination unit 102 and the inverse quantization parameter value prediction block determination unit 123 determine neighboring blocks to be referenced when predicting the quantization parameter value of the current block in the encoder and decoder, respectively.

[0056] In Figure 7a, in order to predict the corresponding value when a quantization / dequantization parameter value is assigned to the CU 720 to be encoded / decoded, the average value, minimum value, maximum value, etc. of the quantization parameter values ​​of the CU (712, 702; Lc, Tc) having the largest block size at each boundary among the CUs (710, 711, 712; La, Lb, Lc) located adjacent to the left boundary of the current CU 720 and the CUs (700, 701, 702; Ta, Tb, Tc) located adjacent to the upper boundary are used.

[0057] FIG. 7b shows another example of the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the first embodiment of the present invention.

[0058] Even when an LCU is divided into multiple CUs for encoding / decoding, the CU with the largest block size among the CUs located adjacent to the current CU 750 to be encoded / decoded is selected at the left and upper boundaries, and the average, minimum, maximum, etc. of the quantization parameter values ​​used by the two CUs are then used to predict the quantization parameter value of the current CU.

[0059] FIG. 8a shows the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the second embodiment of the present invention.

[0060] When predicting the quantization parameter value of the current CU 840 to be encoded / decoded, the CU in the largest block among the CUs located adjacent to the current CU is referenced. In this case, if there are multiple CUs with the largest size, the CU (820; La) located adjacent to the top of the left boundary is selected, and the CU (800; Ta) located adjacent to the left of the left boundary is referenced preferentially, and the average, maximum, minimum, etc. of the quantization parameter value of the current CU is used.

[0061] FIG. 8b shows another example of the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the second embodiment of the present invention.

[0062] Even when an LCU is divided into multiple CUs for encoding / decoding, the CU with the largest block size among the CUs located adjacent to the current CU 890 to be encoded / decoded is referenced. In this case, if there are multiple CUs with the largest block size at the left boundary, the CU (870; La) located adjacent to the top is used as the reference block. If there are multiple CUs with the largest block size at the top boundary, the CU (850; Ta) located adjacent to the left is used as the reference block. After determining the blocks to be referenced on the left and top in this manner, the maximum, minimum, and average quantization values ​​of the two blocks are calculated, and the quantization parameter value of the CU 890 to be encoded / decoded is predicted using the calculated values.

[0063] FIG. 9a shows the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the third embodiment of the present invention.

[0064] When predicting the quantization parameter value of the current CU 920 to be encoded / decoded, all referable CUs (900, 901, 902, 910, 911, 912; Ta, Tb, Tc, La, Lb, Lc) located adjacent to the CU are selected as reference blocks. The encoder predicts the quantization parameter value of the CU 920 to be encoded using the maximum, minimum, average, etc. of the quantization parameter values ​​of all referable CUs, and then encodes the quantization parameter difference value.

[0065] The decoder decodes the inverse quantization parameter value of the CU 920 to be decoded by adding the maximum, minimum, and average values ​​of the inverse quantization parameter values ​​of all CUs that can refer to the decoded quantization parameter difference value.

[0066] FIG. 9b shows another example of the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the third embodiment of the present invention.

[0067] Even when the CU 950 to be encoded / decoded is located within an LCU, the quantization parameter value is predicted using all referable CUs (930, 931, 932, 940, 941, 942; La, Lb, Lc, Ta, Tb, Tc) located adjacent to the CU.

[0068] The encoder predicts the quantization parameter value of the CU 950 to be encoded using the average, maximum, minimum, etc. of the quantization parameter values ​​of all surrounding referable CUs, and encodes only the difference value.

[0069] When the decoder restores the inverse quantization parameter value of the CU 950 to be decoded, it decodes the inverse quantization parameter value by adding the average, maximum, and minimum values ​​of the inverse quantization parameter values ​​of all surrounding referable CUs.

[0070] FIG. 10a shows the quantization parameter value prediction block determination unit 102 and the inverse quantization parameter value prediction block determination unit 123 according to the fourth embodiment of the present invention.

[0071] When encoding / decoding a CU 1020 located at an LCU boundary, the CU (1012; Tc) with the largest block size is referenced from the CUs (1010, 1011, 1012; La, Lb, Lc) that are adjacent to the left boundary of the CU. If there is one or more CUs with the largest block size among the CUs that are accessible from the left boundary, the CU located adjacently at the top of the CU is selected as the reference block.

[0072] The encoder predicts the quantization parameter value of the CU 1020 to be coded using the quantization parameter value of the CU (1012; Tc) selected as the reference block at the left boundary, and then codes the difference value.

[0073] The decoder decodes the inverse quantization parameter difference value of the CU 1020 to be decoded, and then decodes the inverse quantization parameter value by adding the inverse quantization parameter value of the CU (1012; Tc) selected as the reference block at the left boundary.

[0074] FIG. 10b shows another example of the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the fourth embodiment of the present invention.

[0075] When an LCU is divided into multiple CUs for encoding / decoding, the CU (1030; La) having the largest block size is referenced from among the CUs (1030, 1031, 1032; La, Lb, Lc) located adjacent to the left boundary of the CU 1050 to be encoded / decoded. In this case, if there is one or more CUs with the largest block size at the left boundary, the CU (1030; La) located adjacently at the top of the corresponding block is selected as the reference block.

[0076] The encoder predicts the quantization parameter value of the CU 1050 to be coded using the quantization parameter value of the CU (1030; La) selected as the reference block at the left boundary, and then codes the difference value.

[0077] The decoder decodes the inverse quantization parameter difference value of the CU 1050 to be decoded, and then decodes the inverse quantization parameter value by adding the inverse quantization parameter value of the CU (1030; La) selected as the reference block at the left boundary.

[0078] FIG. 11a shows the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the fifth embodiment of the present invention.

[0079] When encoding / decoding a CU 1120 located at an LCU boundary, all of the referenceable CUs (1110, 1111, 1112; La, Lb, Lc) adjacent to the left boundary of the CU are used as reference blocks.

[0080] The encoder predicts the quantization parameter value of the CU 1120 to be encoded using the average, maximum, minimum, etc. of the quantization parameter values ​​of the referenceable CUs (1110, 1111, 1112; La, Lb, Lc) adjacent to the left boundary, and then encodes only the difference value.

[0081] The decoder decodes the inverse quantization parameter difference value of the CU 1120 to be decoded, and then decodes the inverse quantization parameter value of the CU 1120 to be decoded by adding the average value, maximum value, minimum value, etc. of the inverse quantization parameter values ​​of the referenceable CUs (1110, 1111, 1112; La, Lb, Lc) adjacent to the left boundary.

[0082] FIG. 11b shows another example of the quantization parameter value prediction block determiner 102 and the inverse quantization parameter value prediction block determiner 123 according to the fifth embodiment of the present invention.

[0083] When an LCU is divided into multiple CUs for encoding / decoding, all referenceable CUs located adjacent to the left boundary of the CU 1150 to be encoded / decoded are used as reference blocks.

[0084] The encoder predicts the quantization parameter value of the CU 1150 to be encoded based on the average, minimum, maximum, etc. of the quantization parameter values ​​of all referable CUs located adjacent to the left boundary, and then encodes the difference value.

[0085] The decoder decodes the inverse quantization parameter difference value of the CU 1150 to be decoded, and then decodes the inverse quantization parameter value by adding the average value, minimum value, maximum value, etc. of the quantization parameter values ​​of all referable CUs located adjacent to the left boundary.

Claims

1. 1. A video encoding method, comprising: determining a first block having one quantized difference value; performing inverse quantization on the first block using an inverse quantization parameter value assigned to the first block; determining a plurality of second blocks used in inverse quantization parameter value prediction; determining the quantization difference value based on subtracting a predicted inverse quantization parameter value determined by the inverse quantization parameter value prediction from the inverse quantization parameter value; Equipped with when the first block is divided into a plurality of sub-blocks, the quantized difference value is coded for a first sub-block within the first block, and the quantized difference value is not coded for other sub-blocks within the first block; the other sub-blocks use the same quantization parameter value as the first sub-block; The video encoding method, wherein the plurality of second blocks includes an uppermost block among a plurality of adjacent blocks adjacent to the left of the first block.

2. 1. A video decoding method, comprising: determining a first block having one quantized difference value; determining a plurality of second blocks used in inverse quantization parameter value prediction; determining an inverse quantization parameter value based on adding a predicted inverse quantization parameter value determined by the inverse quantization parameter value prediction to the quantization difference value; performing inverse quantization using the determined inverse quantization parameter value; Equipped with when the first block is divided into a plurality of sub-blocks, the quantized difference value is signaled for a first sub-block within the first block, and the quantized difference value is not signaled for other sub-blocks within the first block; the other sub-blocks use the same quantization parameter value as the first sub-block; The method of claim 1, wherein the second blocks include an uppermost block among a plurality of adjacent blocks adjacent to the left of the first block.

3. 1. A method for transmitting a bitstream, the method comprising: determining a first block having one quantized difference value; performing inverse quantization on the first block using an inverse quantization parameter value assigned to the first block; determining a plurality of second blocks used in inverse quantization parameter value prediction; determining the quantization difference value based on subtracting a predicted inverse quantization parameter value determined by the inverse quantization parameter value prediction from the inverse quantization parameter value; encoding the quantized difference values ​​into the bitstream; transmitting the bitstream containing the encoded quantized difference values; Equipped with when the first block is divided into a plurality of sub-blocks, the quantized difference value is coded for a first sub-block within the first block, and the quantized difference value is not coded for other sub-blocks within the first block; the other sub-blocks use the same quantization parameter value as the first sub-block; 10. A method for transmitting a bitstream, wherein the second blocks include an uppermost block among a plurality of adjacent blocks adjacent to the left of the first block.

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