KR101824058B1 - Method and apparatus for video encoding considering adaptive loop filtering, and method and apparatus for video decoding considering adaptive loop filtering - Google Patents

Abstract

The present invention receives and parses a bitstream of encoded video, and extracts a bitstream of the encoded video from the bitstream, including the image data of the current picture allocated to the largest encoding unit, which is the largest unit of encoding, the encoding depth per encoding unit, And extracts filter coefficient information for loop filtering of the current picture, decodes the encoded image data for each maximum encoding unit based on the information on the encoding depth and encoding mode for each maximum encoding unit, decodes the current picture FIG. 1 is a block diagram of a video decoding apparatus according to an embodiment of the present invention; FIG. 2 is a block diagram of a video decoding apparatus according to an embodiment of the present invention;

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for encoding video using adaptive loop filtering, a method and apparatus for video decoding,

The present invention relates to encoding and decoding of video.

Background of the Invention [0002] As the development and dissemination of hardware capable of playing back and storing high-resolution or high-definition video content increases the need for video codecs to effectively encode or decode high-definition or high-definition video content. According to the conventional video codec, video is encoded according to a limited encoding method based on a macroblock of a predetermined size. In addition, the existing video codec also uses loop filtering to improve the quality of reconstructed image data.

The present invention relates to the encoding and decoding of video using adaptive loop filtering by continuous one-dimensional filtering.

According to an embodiment of the present invention, there is provided a video decoding method using loop filtering by continuous one-dimensional filtering, comprising: receiving and parsing a bitstream of encoded video; Extracts from the bitstream the video data of the current picture allocated to the largest coding unit which is the coding unit of the maximum size, the coding depth and the coding mode of each coding unit, and the filter coefficient information for loop filtering of the current picture step; Decoding the encoded image data for each maximum encoding unit based on information on the encoding depth and the encoding mode for each maximum encoding unit; And performing deblocking on the decoded image data of the current picture and performing loop filtering by continuous one-dimensional filtering on the deblocked data.

An encoding unit according to an embodiment may be characterized by a maximum size and a depth.

Depth indicates a stage in which coding units are hierarchically divided. As the depth increases, the depth coding units can be divided from the maximum coding unit to the minimum coding unit. In the present specification, it is defined that the depth is deepened from a high depth or a high depth toward a low depth or a bottom depth. As the depth increases, the number of division of the maximum encoding unit increases and the total number of divisions of the maximum encoding unit corresponds to 'maximum depth'. The maximum size and the maximum depth of the encoding unit may be preset.

The extracting of the filter coefficient information according to an exemplary embodiment includes extracting residual information for difference values between successive filter coefficients for each one-dimensional filter among the plurality of one-dimensional filters.

The performing of the loop filtering according to an exemplary embodiment may restore the current picture by continuously performing one-dimensional filtering in the horizontal direction and one-dimensional filtering in the vertical direction.

The performing of the loop filtering may include deriving a filter coefficient of each one-dimensional filter using residual information of the extracted filter coefficients; And performing the continuous one-dimensional filtering using the filter coefficient of each of the derived one-dimensional filters.

The step of deriving the filter coefficients according to an embodiment may include calculating a current filter coefficient by adding a difference value between a current filter coefficient and a previous filter coefficient to the previous filter coefficient for each one-dimensional filter, Lt; / RTI >

The step of performing the loop filtering according to an exemplary embodiment may include filtering five horizontal direction one-dimensional filter coefficients for nine consecutive data in the horizontal direction among the deblocked image data; And filtering the nine deblocked image data with five vertical direction one-dimensional filter coefficients for nine consecutive data in the vertical direction.

According to an embodiment of the present invention, there is provided a video encoding method using loop filtering by continuous one-dimensional filtering, the method comprising: dividing a current picture into at least one maximum encoding unit which is a maximum-size encoding unit; Encoding the at least one divided area in which the area of the maximum encoding unit is divided for each depth, based on a depth that increases as the number of times of dividing the area of the maximum encoding unit increases, Determining a depth at which the result is to be output; A decoding step of decoding the encoded image data, the depth information and the prediction mode encoding information of the at least one divided area for each of the maximum encoding units, and performing loop filtering by continuous one-dimensional filtering after deblocking during encoding of the current picture And encoding and outputting the filter coefficient information.

The step of outputting the filter coefficient information of the loop filtering according to an embodiment includes encoding the difference value between the current filter coefficient and the previous filter coefficient as the residual information for each one-dimensional filter.

According to one embodiment, the maximum encoding unit includes the depth-dependent encoding units according to at least one depth, each low-depth encoding unit includes a plurality of high-depth encoding units, The coding depth indicates a depth with the smallest coding error among at least one depth coding unit hierarchically differentiated from the maximum coding unit.

According to an embodiment of the present invention, a video decoding apparatus using loop filtering by continuous one-dimensional filtering includes a receiver for receiving and parsing a bitstream of encoded video; Extracting, from the bitstream, image data of a current picture allocated to a maximum coding unit which is a coding unit of a maximum size, information on a coding depth and a coding mode of each coding unit, and filter coefficient information for loop filtering of the current picture And An image data decoding unit for decoding the image data encoded by the maximum encoding unit based on the encoding depth and the encoding mode of the maximum encoding unit; And a loop filtering unit for performing deblocking on the decoded image data of the current picture and performing loop filtering by continuous one-dimensional filtering on the deblocked data.

According to an embodiment of the present invention, a video encoding apparatus using loop filtering by continuous one-dimensional filtering includes a maximum encoding unit division unit that divides a current picture into at least one maximum encoding unit, which is a maximum-size encoding unit; Encoding the at least one divided area in which the area of the maximum encoding unit is divided for each depth, based on a depth that increases as the number of times of dividing the area of the maximum encoding unit increases, An encoding depth determination unit for determining a depth at which a result is output; Performing a loop filtering process performed by continuous one-dimensional filtering after deblocking during coding of the current picture, and encoding information regarding a depth and a prediction mode for each of the at least one divided region, And outputs the encoded filter coefficient information.

The present invention includes a computer-readable recording medium on which a program for implementing a video decoding method according to an embodiment is recorded. The present invention also includes a computer-readable recording medium on which a program for implementing a video encoding method according to an embodiment is recorded.

1 shows a block diagram of a video encoding apparatus according to an embodiment of the present invention.
2 shows a block diagram of a video decoding apparatus according to an embodiment of the present invention.
FIG. 3 illustrates a concept of an encoding unit according to an embodiment of the present invention.
4 is a block diagram of an image encoding unit based on an encoding unit according to an embodiment of the present invention.
5 is a block diagram of a video decoding unit based on an encoding unit according to an embodiment of the present invention.
FIG. 6 illustrates a depth-based coding unit and a prediction unit according to an embodiment of the present invention.
FIG. 7 shows a relationship between an encoding unit and a conversion unit according to an embodiment of the present invention.
FIG. 8 illustrates depth-specific encoding information, in accordance with an embodiment of the present invention.
FIG. 9 shows a depth encoding unit according to an embodiment of the present invention.
FIGS. 10A, 10B, and 10C illustrate the relationship between an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.
FIG. 11 shows encoding information for each encoding unit according to an embodiment of the present invention.
12 shows a flowchart of a video coding method according to an embodiment of the present invention.
13 shows a flowchart of a video decoding method according to an embodiment of the present invention.
14 shows a video encoding apparatus using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.
FIG. 15 illustrates a video decoding apparatus that uses loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.
Figure 16 shows a flow diagram of continuous one-dimensional filtering according to an embodiment of the present invention.
17 shows a flowchart of loop filtering according to another embodiment of the present invention.
18 shows a video encoding method using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.
19 shows a video decoding method using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.

Hereinafter, a video encoding apparatus and a video decoding apparatus, a video encoding method, and a video decoding method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 26. Referring to FIGS. 1 to 14, encoding and decoding of video based on spatially hierarchical data units according to an embodiment of the present invention will be described below, and with reference to FIGS. 14 to 26, The encoding of video and adaptation of video using adaptive loop filtering is described below.

Hereinafter, a video encoding apparatus, a video encoding apparatus, a video encoding method, and a video decoding method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 13.

1 shows a block diagram of a video encoding apparatus according to an embodiment of the present invention.

The video coding apparatus 100 according to an embodiment includes a maximum coding unit division unit 110, a coding depth determination unit 120, and an output unit 130.

The maximum coding unit division unit 110 may divide a current picture based on a maximum coding unit which is a coding unit of a maximum size for a current picture of an image. If the current picture is larger than the maximum encoding unit, the image data of the current picture may be divided into at least one maximum encoding unit. The image data may be output to the coding depth determination unit 120 for each of at least one maximum coding unit.

An encoding unit according to an embodiment may be characterized by a maximum size and a depth. Depth indicates a stage in which coding units are hierarchically divided. As the depth increases, the depth coding units can be divided from the maximum coding unit to the minimum coding unit. The depth of the maximum encoding unit is the highest depth and the minimum encoding unit can be defined as the least significant encoding unit. As the depth of the maximum encoding unit increases, the size of the depth-dependent encoding unit decreases, so that the encoding unit of the higher depth may include a plurality of lower-depth encoding units.

As described above, according to the maximum size of an encoding unit, the image data of the current picture is divided into a maximum encoding unit, and each maximum encoding unit may include encoding units divided by depth. Since the maximum encoding unit according to an embodiment is divided by depth, image data of a spatial domain included in the maximum encoding unit can be hierarchically classified according to depth.

The maximum depth for limiting the total number of times the height and width of the maximum encoding unit can be hierarchically divided and the maximum size of the encoding unit may be preset.

The coding depth determiner 120 encodes at least one divided area in which the area of the maximum coding unit is divided for each depth, and determines the depth at which the final coding result is output for each of at least one of the divided areas. That is, the coding depth determination unit 120 selects the depth at which the smallest coding error occurs, and determines the coding depth as the coding depth by coding the image data in units of depth coding for each maximum coding unit of the current picture. The determined coding depth and the image data of each coding unit are output to the output unit 130.

The image data in the maximum encoding unit is encoded based on the depth encoding unit according to at least one depth below the maximum depth, and the encoding results based on the respective depth encoding units are compared. As a result of the comparison of the encoding error of the depth-dependent encoding unit, the depth with the smallest encoding error can be selected. At least one coding depth may be determined for each maximum coding unit.

As the depth of the maximum encoding unit increases, the encoding unit is hierarchically divided and divided, and the number of encoding units increases. In addition, even if encoding units of the same depth included in one maximum encoding unit, the encoding error of each data is measured and it is determined whether or not the encoding unit is divided into lower depths. Therefore, even if the data included in one maximum coding unit has a different coding error according to the position, the coding depth can be determined depending on the position. Accordingly, one or more coding depths may be set for one maximum coding unit, and data of the maximum coding unit may be divided according to one or more coding depth encoding units.

The predictive encoding and frequency conversion of the maximum encoding unit can be performed. Likewise, predictive coding and frequency conversion are performed on the basis of the depth coding unit for each maximum coding unit and for each depth below the maximum depth.

Since the number of coding units per depth is increased every time the maximum coding unit is divided by the depth, the coding including the predictive coding and the frequency conversion should be performed for every depth coding unit as the depth increases. For convenience of explanation, predictive coding and frequency conversion will be described based on a coding unit of a current depth among at least one maximum coding unit.

The video encoding apparatus 100 according to an exemplary embodiment may select various sizes or types of data units for encoding image data. To encode the image data, a step such as predictive encoding, frequency conversion, and entropy encoding is performed. The same data unit may be used for all steps, and the data unit may be changed step by step.

For example, the video coding apparatus 100 can select not only a coding unit for coding image data but also a data unit different from the coding unit in order to perform predictive coding of the image data of the coding unit.

For predictive coding of the maximum coding unit, predictive coding may be performed based on the partial data unit of the coding unit for each depth of the maximum coding unit. The partial data unit of the encoding unit may include a data unit in which at least one of the height and the width of the encoding unit and the depth encoding unit is divided.

For example, when the size of the encoding unit is 2Nx2N (where N is a positive integer), the size of the partial data unit may be 2Nx2N, 2NxN, Nx2N, NxN, and the like. Prediction coding may be performed based on data units of various types, in addition to data units of a type in which at least one of height and width of coding units is divided by half. Hereinafter, a data unit on which prediction encoding is based may be referred to as a 'prediction unit'.

The prediction mode of the encoding unit may be at least one of an intra mode, an inter mode, and a skip mode. For example, the intra mode and the inter mode can be performed for prediction units of 2Nx2N, 2NxN, Nx2N, and NxN sizes. In addition, the skip mode can be performed only for a prediction unit of 2Nx2N size. Encoding is performed independently for each prediction unit within an encoding unit, and a prediction mode having the smallest encoding error can be selected.

In addition, the video encoding apparatus 100 according to an exemplary embodiment may perform frequency conversion of image data of an encoding unit based on not only an encoding unit for encoding image data but also a data unit different from the encoding unit.

For frequency conversion of a coding unit, frequency conversion may be performed based on a data unit having a size smaller than or equal to the coding unit. For example, a data unit for frequency conversion may include a data unit for intra mode and a data unit for inter mode. Hereinafter, the data unit on which the frequency conversion is based may be referred to as a 'conversion unit'.

The coding information according to the coding depth needs not only the coding depth but also prediction related information and frequency conversion related information. Therefore, the coding depth determiner 120 not only determines the coding depth at which the minimum coding error is generated, but also the partition type in which the coding unit of the coding depth is divided into prediction units, the prediction unit-specific prediction mode, Can be determined.

The coding depth determination unit 120 may measure the coding error of the depth-dependent coding unit using a Lagrangian Multiplier-based rate-distortion optimization technique.

The output unit 130 outputs, in the form of a bit stream, video data of the maximum encoding unit encoded based on at least one encoding depth determined by the encoding depth determination unit 120 and information on the depth encoding mode.

The encoded image data may be a result of encoding residual data of the image.

The information on the depth-dependent coding mode may include coding depth information, partition type information of a prediction unit of a coding unit of coding depth, prediction mode information per prediction unit, size information of a conversion unit, and the like.

The coding depth information can be defined using depth division information indicating whether or not coding is performed at the lower depth coding unit without coding at the current depth. If the current depth of the current encoding unit is the encoding depth, the current encoding unit is encoded in the current depth encoding unit, so that the division information of the current depth can be defined so as not to be further divided into lower depths. On the other hand, if the current depth of the current encoding unit is not the encoding depth, the encoding using the lower depth encoding unit should be tried. Therefore, the division information of the current depth may be defined to be divided into the lower depth encoding units.

If the current depth is not the encoding depth, encoding is performed on the encoding unit divided into lower-depth encoding units. Since there are one or more lower-level coding units in the current-depth coding unit, the coding is repeatedly performed for each lower-level coding unit so that recursive coding can be performed for each coding unit of the same depth.

At least one coding depth is determined in one maximum coding unit and at least one coding mode information is determined for each coding depth so that information on at least one coding mode can be determined for one maximum coding unit. Since the data of the maximum encoding unit is hierarchically divided according to the depth and the depth of encoding may be different for each position, information on the encoding depth and the encoding mode may be set for the data.

Accordingly, the output unit 130 according to the embodiment can set the corresponding encoding information for each minimum encoding unit included in the maximum encoding unit. That is, the coding unit of the coding depth includes at least one minimum coding unit that holds the same coding information. By using this, if the neighboring minimum encoding units have the same depth encoding information, it can be the minimum encoding unit included in the same maximum encoding unit.

For example, the encoding information output through the output unit 130 may be classified into encoding information per depth unit and encoding information per prediction unit. The under-coding-by-depth coding unit information may include prediction mode information and partition size information. The encoding information to be transmitted for each prediction unit includes information about the estimation direction of the inter mode, information about the reference picture index of the inter mode, information on the motion vector, information on the chroma component of the intra mode, information on the interpolation mode of the intra mode And the like. Information on the maximum size of a coding unit defined for each picture, slice or GOP, and information on the maximum depth can be inserted into the header of the bitstream.

According to the simplest embodiment of the video coding apparatus 100, the coding unit for depth is a coding unit which is half the height and width of the coding unit of one layer higher depth. That is, if the size of the current depth encoding unit is 2Nx2N, the size of the lower depth encoding unit is NxN. In addition, the current encoding unit of 2Nx2N size can include a maximum of 4 sub-depth encoding units of NxN size.

Therefore, the video decoding apparatus 100 according to an embodiment determines an encoding unit of an optimal shape and size for each maximum encoding unit based on the size and the maximum depth of the maximum encoding unit determined in consideration of the characteristics of the current picture . In addition, since each encoding unit can be encoded by various prediction modes, frequency conversion methods, and the like, an optimal encoding mode can be determined in consideration of image characteristics of encoding units of various image sizes.

Therefore, if an image having a very high image resolution or a very large data amount is encoded in units of existing macroblocks, the number of macroblocks per picture becomes excessively large. This increases the amount of compression information generated for each macroblock, so that the burden of transmission of compressed information increases and the data compression efficiency tends to decrease. Therefore, the video encoding apparatus according to an embodiment can increase the maximum size of the encoding unit in consideration of the image size, and adjust the encoding unit in consideration of the image characteristic, so that the image compression efficiency can be increased.

2 shows a block diagram of a video decoding apparatus according to an embodiment of the present invention.

The video decoding apparatus 200 includes a receiving unit 210, an image data and encoding information extracting unit 220, and an image data decoding unit 230. The definition of various terms such as coding unit, depth, prediction unit, conversion unit, and information on various coding modes for various processing of the video decoding apparatus 200 according to an embodiment is the same as that of FIG. 1 and the video coding apparatus 100 Are the same as described above.

The receiving unit 205 receives and parses the bitstream of the encoded video. The image data and encoding information extracting unit 220 extracts image data for each maximum encoding unit from the parsed bit stream and outputs the extracted image data to the image data decoding unit 230. The image data and encoding information extracting unit 220 can extract information on the maximum size of the encoding unit of the current picture from the header of the current picture.

Also, the image data and encoding information extracting unit 220 extracts information on the encoding depth and the encoding mode for each maximum encoding unit from the parsed bitstream. The information on the extracted coding depth and coding mode is output to the image data decoding unit 230. That is, the video data of the bit stream can be divided into the maximum encoding units, and the video data decoding unit 230 can decode the video data per maximum encoding unit.

Information on the coding depth and the coding mode per coding unit can be set for one or more coding depth information, and the information on the coding mode for each coding depth includes information on partition type information, prediction mode information, Size information of the conversion unit, and the like. In addition, as the encoding depth information, depth-based segmentation information may be extracted.

The encoding depth and encoding mode information extracted by the image data and encoding information extracting unit 220 may be encoded in the encoding unit such as the video encoding apparatus 100 according to one embodiment, And information on the coding depth and coding mode determined to repeatedly perform coding for each unit to generate the minimum coding error. Therefore, the video decoding apparatus 200 can decode the data according to the coding scheme that generates the minimum coding error to recover the video.

The image data and encoding information extracting unit 220 can extract information on the encoding depth and the encoding mode for each minimum encoding unit. If information on the coding depth and the coding mode of the corresponding maximum coding unit is recorded for each minimum coding unit, the minimum coding units having the same coding depth and information on the coding mode are estimated as data units included in the same maximum coding unit . That is, if the minimum coding units of the same information are collected and decoded, it is possible to decode based on the coding units of the coding depth with the smallest coding error.

The image data decoding unit 230 decodes the image data of each maximum encoding unit based on the information on the encoding depth and the encoding mode for each maximum encoding unit to reconstruct the current picture. The image data decoding unit 230 can decode the image data for each coding unit of at least one coding depth based on the coding depth information for each coding unit. The decoding process may include a prediction process including intra prediction and motion compensation, and an inverse frequency conversion process.

The image data decoding unit 230 decodes each of the prediction units and prediction modes for each coding unit on the basis of the partition type information and the prediction mode information of the prediction unit of the coding unit for each coding depth for each coding unit, Or motion compensation.

In addition, the image data decoding unit 230 may perform frequency inverse transform for each encoding unit on the basis of the size information of the conversion unit of each encoding depth-based encoding unit for frequency inverse conversion for each maximum encoding unit .

The image data decoding unit 230 can determine the coding depth of the current maximum encoding unit using the division information by depth. If the partition information indicates that the current depth is to be decoded, the current depth is the depth of the encoding. Therefore, the image data decoding unit 230 can decode the current depth encoding unit for the image data of the current maximum encoding unit using the partition type, the prediction mode, and the conversion unit size information of the prediction unit.

That is, it is possible to observe the encoding information set for the minimum encoding unit and to decode the minimum encoding units that hold the encoding information including the same division information, into one data unit.

The video decoding apparatus 200 according to an exemplary embodiment recursively performs encoding for each maximum encoding unit in the encoding process to obtain information on an encoding unit that has generated the minimum encoding error and can use the encoded information for decoding the current picture have. That is, it is possible to decode video data in the optimal encoding unit for each maximum encoding unit.

Accordingly, even if an image with a high resolution or an excessively large amount of data is used, the information on the optimal encoding mode transmitted from the encoding end is used, and the image data is efficiently encoded according to the encoding unit size and encoding mode, Can be decoded and restored.

FIG. 3 shows the concept of a hierarchical coding unit.

An example of an encoding unit may include 32x32, 16x16, 8x8, and 4x4 from an encoding unit with a width x height of 64x64. In addition to the square-shaped encoding units, there may be encoding units whose width x height is 64x32, 32x64, 32x16, 16x32, 16x8, 8x16, 8x4, 4x8.

With respect to the video data 310, the resolution is set to 1920 x 1080, the maximum size of the encoding unit is set to 64, and the maximum depth is set to 2. With respect to the video data 320, the resolution is set to 1920 x 1080, the maximum size of the encoding unit is set to 64, and the maximum depth is set to 4. With respect to the video data 330, the resolution is set to 352 x 288, the maximum size of the encoding unit is set to 16, and the maximum depth is set to 2.

It is preferable that the maximum size of the coding size is relatively large in order to improve the coding efficiency as well as to accurately characterize the image characteristics when the resolution or the data amount is large. Therefore, the maximum size of the video data 310 and 320 having the higher resolution than the video data 330 can be selected to be 64. FIG.

The maximum depth indicates the total number of layers in the hierarchical encoding unit. Therefore, since the maximum depth of the video data 310 is 2, the encoding unit 315 of the video data 310 is encoded from a maximum encoding unit having a major axis size of 64, Units. On the other hand, since the maximum depth of the video data 330 is 2, the encoding unit 335 of the video data 330 has a depth of two layers from the encoding units having the major axis size of 16, Units.

Since the maximum depth of the video data 320 is 4, the encoding unit 325 of the video data 320 has a depth of four layers from 32 to 16, 8, and 4 Encoding units. The deeper the depth, the better the ability to express detail.

4 is a block diagram of an image encoding unit based on an encoding unit according to an embodiment of the present invention.

The image encoding unit 400 according to an exemplary embodiment includes operations to encode image data in the encoding depth determination unit 120 of the video encoding apparatus 100. That is, the intraprediction unit 410 performs intraprediction on the intra-mode encoding unit of the current frame 405, and the motion estimation unit 420 and the motion compensation unit 425 perform intraprediction on the current frame 405 of the inter- And a reference frame 495. The inter-frame estimation and the motion compensation are performed using the reference frame and the reference frame.

The data output from the intraprediction unit 410, the motion estimation unit 420 and the motion compensation unit 425 is output as a quantized transform coefficient through the frequency transform unit 430 and the quantization unit 440. The quantized transform coefficients are reconstructed into spatial domain data through the inverse quantization unit 460 and the frequency inverse transform unit 470 and the data of the reconstructed spatial domain is passed through the deblocking unit 480 and the loop filtering unit 490 Processed and output to the reference frame 495. [ The quantized transform coefficient may be output to the bitstream 455 via the entropy encoding unit 450.

The motion estimation unit 420, the motion compensation unit 425, and the frequency transformation unit 420, which are components of the image encoding unit 400, are applied to the video encoding apparatus 100 according to an embodiment of the present invention. The quantization unit 440, the entropy encoding unit 450, the inverse quantization unit 460, the frequency inverse transform unit 470, the deblocking unit 480, and the loop filtering unit 490, The work should be performed based on the depth encoding unit considering the maximum depth.

In particular, the intra prediction unit 410, the motion estimation unit 420, and the motion compensation unit 425 determine the prediction unit and the prediction mode in the coding unit in consideration of the maximum size and depth of the coding unit, and the frequency conversion unit 430 ) Should consider the size of the conversion unit considering the maximum size and depth of the encoding unit.

5 is a block diagram of an image decoding unit based on an encoding unit according to an embodiment of the present invention.

The bitstream 505 passes through the parsing unit 510 and the encoded image data to be decoded and the encoding-related information necessary for decoding are parsed. The encoded image data is output as inverse quantized data through the entropy decoding unit 520 and the inverse quantization unit 530, and the image data in the spatial domain is restored through the frequency inverse transform unit 540.

The intra-prediction unit 550 performs intraprediction on the intra-mode encoding unit for the video data in the spatial domain, and the motion compensating unit 560 performs intra-prediction on the intra-mode encoding unit using the reference frame 585 And performs motion compensation for the motion compensation.

The data in the spatial domain that has passed through the intra prediction unit 550 and the motion compensation unit 560 may be post-processed through the deblocking unit 570 and the loop filtering unit 580 and output to the reconstruction frame 595. Further, the post-processed data via deblocking unit 570 and loop filtering unit 580 may be output as reference frame 585.

In order to decode the image data in the image data decoding unit 230 of the video decoding apparatus 200, operations after the parsing unit 510 of the image decoding unit 500 according to the embodiment may be performed.

The entropy decoding unit 520, the inverse quantization unit 530, and the frequency inverse transforming unit 520, which are components of the image decoding unit 400, in order to be applied to the video decoding apparatus 200 according to one embodiment. The intraprediction unit 550, the motion compensation unit 560, the deblocking unit 570 and the loop filtering unit 580 all have to perform an operation based on the encoding unit of the encoding depth for each maximum encoding unit .

In particular, the intra prediction unit 550 and the motion compensation unit 560 determine a coding unit and a prediction mode in consideration of the maximum size and depth of a coding unit, and the frequency inverse transform unit 540 sets the maximum size and depth of the coding unit The size of the conversion unit should be considered.

FIG. 6 illustrates a depth-based coding unit and a prediction unit according to an embodiment of the present invention.

The video encoding apparatus 100 and the video decoding apparatus 200 according to an exemplary embodiment use a hierarchical encoding unit to consider an image characteristic. The maximum height, width, and maximum depth of the encoding unit may be adaptively determined according to the characteristics of the image, or may be variously set according to the demand of the user. The size of each coding unit may be determined according to the maximum size of a predetermined coding unit.

The hierarchical structure 600 of the encoding unit according to an embodiment shows a case where the maximum height and width of the encoding unit is 64 and the maximum depth is 4. Since the depth is deeper along the vertical axis of the hierarchical structure 600 of the encoding unit according to the embodiment, the height and width of the encoding unit for each depth are divided. In addition, along the horizontal axis of the hierarchical structure 600 of the coding unit, a prediction unit which is a partial data unit on which prediction coding of each depth coding unit is based is shown.

That is, the coding unit 610 is the largest coding unit among the hierarchical structures 600 of the coding units and has a depth of 0, and the size of the coding units, that is, the height and the width, is 64x64. A depth-1 encoding unit 620 having a size of 32x32, a depth-2 encoding unit 620 having a size 16x16, a depth-3 encoding unit 640 having a size 8x8, a depth 4x4 having a size 4x4, There is an encoding unit 650. An encoding unit 650 of depth 4 of size 4x4 is the minimum encoding unit.

The partial data units are arranged as a prediction unit of the encoding unit along the horizontal axis for each depth. That is, the prediction unit of the encoding unit 610 having a size of 64x64 with a depth of 0 is a partial data unit 610 having a size of 64x64, partial data units 612 having a size of 64x32 included in the encoding unit 610 of size 64x64, Partial data units 614 of size 32x64, and partial data units 616 of size 32x32. Conversely, the encoding unit may be a minimum-sized square data unit including the conversion units 610, 612, 614, and 616.

Likewise, the prediction unit of the encoding unit 620 of the size 32x32 of the depth 1 is the partial data unit 620 of the size 32x32, the partial data units 622 of the size 32x16, and the partial data unit 620 of the size 32x32 included in the encoding unit 620 of the size 32x32, Partial data units 624 of size 16x32, partial data units 626 of size 16x16.

Likewise, the prediction unit of a 16x16 size 16x16 encoding unit is a 16x16 partial data unit 630, a 16x8 partial data unit 632, and a 16x16 partial data unit 630 included in the 16x16 encoding unit 630, Partial data units 634 of size 8x16, and partial data units 636 of size 8x8.

Likewise, the prediction unit of the encoding unit 640 of the size 8x8 of the depth 3 includes the partial data unit 640 of the size 8x8, the partial data units 642 of the size 8x4, and the partial data units 640 of the size 8x8 included in the encoding unit 640 of the size 8x8, Partial data units 644 of size 4x8, and partial data units 646 of size 4x4.

Finally, a coding unit 650 of size 4x4 is the minimum coding unit and the coding unit of the lowest depth, and the prediction unit is a data unit 650 of size 4x4.

The coding depth determiner 120 of the video coding apparatus 100 according to an exemplary embodiment of the present invention determines the coding depth of the maximum coding unit 610 by multiplying the coding unit of each depth included in the maximum coding unit 610 Encoding is performed.

The number of coding units per depth to include data of the same range and size increases as the depth of the coding unit increases. For example, for data containing one coding unit at depth 1, four coding units at depth 2 are required. Therefore, in order to compare the encoding results of the same data by depth, they should be encoded using a single depth 1 encoding unit and four depth 2 encoding units, respectively.

For each depth-of-field coding, encoding is performed for each prediction unit of the depth-dependent coding unit along the horizontal axis of the hierarchical structure 600 of the coding unit, and a representative coding error, which is the smallest coding error at the corresponding depth, is selected . In addition, depths are deepened along the vertical axis of the hierarchical structure 600 of encoding units, and the minimum encoding errors can be retrieved by comparing the representative encoding errors per depth by performing encoding for each depth. The depth at which the minimum coding error occurs among the maximum coding units 610 can be selected as the coding depth and the partition type of the maximum coding unit 610. [

FIG. 7 shows a relationship between an encoding unit and a conversion unit according to an embodiment of the present invention.

The video coding apparatus 100 or the video decoding apparatus 200 according to an embodiment encodes or decodes an image in units of coding units smaller than or equal to the maximum coding unit for each maximum coding unit. The size of the conversion unit for frequency conversion during encoding can be selected based on data units that are not larger than the respective encoding units.

For example, in the video encoding apparatus 100 or the video encoding apparatus 200 according to an embodiment, when the current encoding unit 710 is 64x64 size, the 32x32 conversion unit 720 The frequency conversion can be performed.

In addition, the data of the encoding unit 710 of 64x64 size is encoded by performing the frequency conversion with the conversion units of 32x32, 16x16, 8x8, and 4x4 size of 64x64 or smaller, respectively, and then the conversion unit having the smallest error with the original Can be selected.

FIG. 8 illustrates depth-specific encoding information, in accordance with an embodiment of the present invention.

The encoding information encoding unit of the video encoding apparatus 100 according to an embodiment is information on an encoding mode, and includes information on a partition type 800, information on a prediction mode 810, Information 820 on the unit size can be encoded and transmitted.

The partition type information 800 indicates information on a type in which the current encoding unit is divided as a prediction unit for predictive encoding of the current encoding unit. For example, the current encoding unit CU_0 of depth 0 and size 2Nx2N includes a prediction unit 802 of size 2Nx2N, a prediction unit 804 of size 2NxN, a prediction unit 806 of size Nx2N, a prediction unit 808 of size NxN ) And can be used as a prediction unit. In this case, information 800 regarding the partition type of the current encoding unit includes a prediction unit 802 of size 2Nx2N, a prediction unit 804 of size 2NxN, a prediction unit 806 of size Nx2N, and a prediction unit 808 of size NxN. Lt; / RTI >

The information 810 on the prediction mode indicates the prediction mode of each prediction unit. The prediction unit indicated by the information 800 relating to the partition type is predicted to be one of the intra mode 812, the inter mode 814 and the skip mode 816 through the prediction mode information 810, for example. Can be set.

In addition, the information 820 on the conversion unit size indicates whether to perform frequency conversion on the basis of which conversion unit the current encoding unit is performed. For example, the conversion unit may be one of a first intra-conversion unit size 822, a second intra-conversion unit size 824, a first inter-conversion unit size 826, have.

The encoding information extracting unit of the video decoding apparatus 200 according to the embodiment extracts the information 800 about the partition type, the information 810 about the prediction mode, the information 820 about the conversion unit size ) Can be extracted and used for decoding.

FIG. 9 shows a depth encoding unit according to an embodiment of the present invention.

Partition information may be used to indicate changes in depth. The division information indicates whether the current-depth encoding unit is divided into lower-depth encoding units.

The prediction unit 910 for the prediction encoding of the coding units of depth 0 and 2N_0x2N_0 has a partition type 912 of 2N_0x2N_0 size, a partition type 914 of 2N_0xN_0 size, a partition type 916 of N_0x2N_0 size, a partition of size N_0xN_0 Type < / RTI >

For each partition type, predictive encoding should be repeatedly performed for each prediction unit of 2N_0x2N_0 size, two 2N_0xN_0 size prediction units, two N_0x2N_0 size prediction units, and four N_0xN_0 size prediction units. For a prediction unit of size 2N_0x2N_0, size N_0x2N_0, size 2N_0xN_0, and size N_0xN_0, predictive coding may be performed in intra mode and inter mode. The skip mode can be performed only for predictive encoding in a prediction unit of size 2N_0x2N_0.

If the coding error by the partition type 918 of the size N_0xN_0 is the smallest, the depth 0 is changed to 1 (920), and the coding units 922, 924, 926 and 928 of the partition type of the depth 2 and the size N_0xN_0 are changed The minimum coding error can be repeatedly searched for.

Since encoding is repeatedly performed on the encoding units 922, 924, 926, and 928 of the same depth, encoding of only one of the encoding units of depth 1, for example, will be described. The prediction unit 930 for predicting the coding unit of the depth 1 and the size 2N_1x2N_1 (= N_0xN_0) includes a partition type 932 of size 2N_1x2N_1, a partition type 934 of size 2N_1xN_1, a partition type 936 of size N_1x2N_1, , And a partition type 938 of size N_1xN_1. For each partition type, predictive coding should be repeatedly performed for each prediction unit of a size 2N_1x2N_1, a prediction unit of two sizes 2N_1xN_1, a prediction unit of two sizes N_1x2N_1, and a prediction unit of four sizes N_1xN_1.

If the coding error by the partition type 938 of the size N_1xN_1 is the smallest, the coding units 942, 944, 946 and 948 of the depth 2 and the size N_2xN_2 are changed while changing the depth 1 to the depth 2 (940) The minimum coding error can be repeatedly searched for.

If the maximum depth is d, the depth-based segmentation information can be set until the depth d-1. That is, the prediction unit 950 for predictive coding of the coding unit of the depth d-1 and the size 2N_ (d-1) x2N_ (d-1) A partition type 954 of size 2N_ (d-1) xN_ (d-1), a partition type 956 of size N_ (d-1) x2N_ 1) xN_ (d-1) < / RTI >

(D-1) x2N_ (d-1), two predicted units of two sizes 2N_ (d-1) (d-1) x2N_ (d-1), four sizes N_ (d-1) xN_ (d-1). Since the maximum depth is d, the coding unit 952 of depth d-1 no longer undergoes the division process.

The video coding apparatus 100 according to an exemplary embodiment compares depth-based coding errors to determine the depth of coding for the coding unit 912, and selects the depth at which the smallest coding error occurs.

For example, a coding error for a coding unit of depth 0 is predicted for each partition type 912, 914, 916, and 918, and a prediction unit in which the smallest coding error occurs is determined. Similarly, a prediction unit having the smallest coding error can be searched for every depth 0, 1, ..., d-1. At the depth d, the encoding error can be determined through predictive encoding based on the prediction unit 960, which is the encoding unit of size 2N_dx2N_d.

In this way, the minimum coding error of each of the depths 0, 1, ..., d-1, and d is compared and the depth with the smallest error is selected to be determined as the coding depth. The coding depth and the prediction unit of the corresponding depth can be encoded and transmitted as information on the coding mode. In addition, since the coding unit must be divided from the depth 0 to the coding depth, only the division information of the coding depth is set to '0', and the division information by depth is set to '1' except for the coding depth.

The encoding information extracting unit 220 of the video decoding apparatus 200 according to an exemplary embodiment may extract information on the encoding depth and prediction unit of the encoding unit 912 and decode the encoding unit 912. [ The video decoding apparatus 200 according to an exemplary embodiment of the present invention uses division information by depth to grasp the depth with the division information of '0' as a coding depth and can use it for decoding using information on the coding mode for the corresponding depth have.

FIGS. 10A, 10B, and 10C illustrate the relationship between an encoding unit, a prediction unit, and a frequency conversion unit according to an embodiment of the present invention.

The coding unit 1010 is coding units for coding depth determined by the video coding apparatus 100 according to the embodiment with respect to the maximum coding unit. The prediction unit 1060 is a prediction unit of each coding depth unit among the coding units 1010 and the conversion unit 1070 is a conversion unit of each coding depth unit.

When the depth of the maximum encoding unit is 0, the depth of the encoding units 1012 and 1054 is 1 and the depth of the encoding units 1014, 1016, 1018, 1028, 1050, The coding units 1020, 1022, 1024, 1026, 1030, 1032 and 1048 have a depth of 3 and the coding units 1040, 1042, 1044 and 1046 have a depth of 4.

A portion (1014, 1016, 1022, 1032, 1048, 1050, 1052, 1054) of the prediction units 1060 is a type in which the coding unit is divided. That is, the prediction units 1014, 1022, 1050 and 1054 are partition types of 2NxN, the prediction units 1016, 1048 and 1052 are partition types of Nx2N, and the prediction units 1032 are partition types of NxN. That is, the prediction unit of the depth-dependent coding units 1010 is smaller than or equal to each coding unit.

The image data of a part 1052 of the conversion units 1070 is subjected to frequency conversion or frequency inverse conversion in units of data smaller in size than the encoding unit. The conversion units 1014, 1016, 1022, 1032, 1048, 1050, 1052, and 1054 are data units of different sizes or types when compared with the prediction units of the prediction units 1060. That is, the video encoding apparatus 100 according to the embodiment and the video decoding apparatus 200 according to an embodiment can perform the intra prediction / motion estimation / motion compensation operation for the same encoding unit and the frequency conversion / , Each based on a separate data unit.

FIG. 11 shows encoding information for each encoding unit according to an embodiment of the present invention.

The output unit 130 of the video encoding apparatus 100 according to an exemplary embodiment outputs encoding information for each encoding unit and the encoding information extracting unit 220 of the video decoding apparatus 200 according to an exemplary embodiment extracts encoding information for each encoding unit It is possible to extract the encoding information.

The encoding information may include division information for the encoding unit, partition type information, prediction mode information, and conversion unit size information. The encoding information shown in FIG. 11 is an example that can be set in the video encoding apparatus 100 according to the embodiment and the video encoding apparatus 200 according to an embodiment.

The division information may indicate the coding depth of the corresponding encoding unit. That is, since depths that are no longer divided according to the division information are coding depths, partition type information, prediction mode, and conversion unit size information can be defined with respect to the coding depth. When it is necessary to further divide by one division according to the division information, encoding should be performed independently for each of four divided sub-depth coding units.

As the partition type information, the partition type of the conversion unit of the coding unit of the coding depth can be represented by 2Nx2N, 2NxN, Nx2N and NxN. The prediction mode may be represented by one of an intra mode, an inter mode, and a skip mode. The intra mode and the inter mode can be defined in the partition types 2Nx2N, 2NxN, Nx2N and NxN, and the skip mode can be defined only in the partition type 2Nx2N. The conversion unit size can be set to two kinds of sizes in the intra mode and two kinds of sizes in the inter mode.

The encoding unit-specific encoding information of the belonging encoding depth may be stored for each minimum encoding unit in the encoding unit. Therefore, if encoding information held in each of the adjacent minimum encoding units is checked, it can be confirmed whether or not the encoding information is included in the encoding unit of the same encoding depth. In addition, since the encoding unit of the encoding depth can be identified by using the encoding information held in the minimum encoding unit, the distribution of encoding depths in the maximum encoding unit can be inferred.

In this case, when the current encoding unit is predicted with reference to the neighboring data unit, the encoding information of the minimum encoding unit in the depth encoding unit adjacent to the current encoding unit is directly used, so that the data of the minimum encoding unit can be referred to.

In yet another embodiment, the encoding information of the depth encoding unit may be stored only for the minimum encoding unit represented in the depth encoding unit. In this case, when the current encoding unit is predicted by referring to the surrounding encoding unit, the data adjacent to the current encoding unit in the depth encoding unit may be retrieved using the encoding information of the adjacent depth encoding unit.

12 shows a flowchart of a video coding method according to an embodiment of the present invention.

In step 1210, the current picture is divided into at least one maximum encoding unit. In addition, the maximum depth indicating the possible total number of divisions may be set in advance.

In step 1220, the area of the maximum coding unit is coded at least in one divided area for each depth, and the depth at which the final coding result is output for each of at least one of the divided areas is determined. The maximum encoding unit is divided into stages, and each time the depth is deepened, it is necessary to repeatedly perform encoding for each lower-depth encoding unit.

For each depth-based coding unit, the conversion unit for each partition type having the smallest coding error should be determined. In order to determine the coding depth that causes the minimum coding error of the coding unit, the coding error should be measured and compared for each coding unit of each depth.

In step 1230, video data as a final encoding result for each of at least one divided area and information on the coding depth and coding mode are output for each maximum coding unit. The information on the encoding mode may include information on the encoding depth or division information, partition type information of the encoding depth, prediction mode information, and conversion unit size information. Information on the encoded encoding mode can be transmitted to the decoding end together with the encoded video data.

13 shows a flowchart of a video decoding method according to an embodiment of the present invention.

In step 1310, a bitstream for the encoded video is received and parsed.

In step 1320, the image data of the current picture allocated to the largest coding unit of the maximum size from the parsed bitstream, and information on the coding depth and coding mode of each coding unit are extracted. The coding depth for each maximum coding unit is the depth selected with the smallest coding error for each maximum coding unit in the process of coding the current picture. The encoding of the maximum encoding unit is the image data encoded based on at least one data unit obtained by dividing the maximum encoding unit hierarchically by depth. Accordingly, the decoding efficiency of the image can be improved by decoding each image data after grasping the coding depth for each coding unit.

In step 1330, the image data of each maximum encoding unit is decoded based on the information on the encoding depth and the encoding mode for each maximum encoding unit. The decoded image data can be reproduced by a reproducing apparatus, stored in a storage medium, or transmitted via a network.

Hereinafter, video encoding and video decoding using adaptive loop filtering according to an embodiment of the present invention will be described with reference to FIGS. 14 to 26. FIG.

14 shows a video encoding apparatus using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.

The video encoding apparatus 1400 according to one embodiment includes a maximum encoding unit division unit 1410, a coding depth determination unit 1420, and an output unit 1460. The output unit 1460 includes an encoded image data output unit 1430, an encoded information output unit 1440, and a loop filter coefficient information output unit 1450.

The maximum coding unit division unit 1410 and the coding depth determination unit 1420 are identical to the maximum coding unit division unit 110 and the coding depth determination unit 120 of the video coding apparatus 100 described above with reference to FIG. Lt; / RTI > The encoded video data output unit 1430 and the encoded information output unit 1440 perform some functions of the output unit 130 of the video encoding apparatus 100 described above with reference to FIG.

However, the video encoding of the video encoding device 1400 includes loop filtering performed by continuous one-dimensional filtering according to an embodiment. Loop filtering features of the video encoding apparatus 1400 according to one embodiment are described below.

According to an embodiment, the maximum coding unit division unit 1410 divides the current picture based on the maximum coding unit which is a coding unit of the maximum size for the current picture of the picture, and the coding depth determination unit 1420 divides the current picture by the maximum coding unit The image data is encoded in a depth-dependent encoding unit to determine a depth at which a final encoding result is output for each of at least one of the divided regions.

The image data output unit 1430, which is encoded according to an embodiment, outputs a bit stream of image data of the maximum encoding unit encoded based on the encoding depth. The encoding information output unit 1440 encodes and outputs information on the depth encoding mode for each maximum encoding unit.

The loop filter coefficient information output unit 1450 according to an embodiment encodes and outputs filter coefficient information of loop filtering performed by continuous one-dimensional filtering after deblocking during encoding of a current picture. Loop filtering according to one embodiment is by continuous filtering of a plurality of one-dimensional filters. Loop filtering may be performed separately for luma components and chroma components.

When the video encoding apparatus 1400 according to the embodiment corresponds to the image encoding unit 400, the quantized transform coefficients are restored into the time domain data through the inverse quantization unit 460 and the frequency inverse transform unit 470 And the reference frame 495 is generated through the deblocking unit 480 and the loop filtering unit 490 in the reconstructed time domain data. The loop filter coefficient information output unit 1450 according to an exemplary embodiment may encode and output a filter coefficient used in the loop filtering unit 490. [

The encoded filter coefficient information includes information on filter coefficients for each one-dimensional filter, and the information on the filter coefficients of each one-dimensional filter may include information on the difference value between successive filter coefficients . That is, the residual component of the filter coefficient of each one-dimensional filter can be encoded. Specifically, the loop filter coefficient information output unit 1450 can code the difference between the current filter coefficient and the previous filter coefficient as residual information for each one-dimensional filter.

Continuous one-dimensional filtering may be continuous filtering of a one-dimensional filter in the horizontal direction and a one-dimensional filter in the vertical direction. Specifically, horizontal one-dimensional filtering is performed on nine consecutive deblocked data in the horizontal direction, and vertical one-dimensional filtering is performed on nine consecutive deblocked data in the vertical direction continuously can do. In this case, the one-dimensional filter in the horizontal direction and the one-dimensional filter in the vertical direction are symmetrical filters, and the number of filter coefficients may be five each.

The filter coefficients of the one-dimensional filter can be determined by a Wiener filter approach.

The video encoding apparatus 1400 according to an exemplary embodiment sets the type, number, size, quantization bit, coefficient, filtering direction, whether or not to perform filtering, and whether or not to perform learning filtering, of each one-dimensional filter, Information about a one-dimensional filter set of filtering may be encoded and transmitted.

Information about the one-dimensional filter set may be set in units of data such as a picture, a slice, and a sequence.

For example, the type of each one-dimensional filter may be determined by a predetermined filter including a Wiener filter, a symmetric filter or an asymmetric filter. If the one-dimensional filter is a binner filter, the filter coefficient information may include information about the cross-correlation matrix instead of individual coefficients, since the filter coefficient may be determined by the cross-correlation matrix between the filters.

The filtering direction of each one-dimensional filter may be determined in the filtering direction for pixels located on a straight line of a predetermined angle. For example, one-dimensional filtering according to a filtering direction of a predetermined angle of ± 0 to 180 ° such as vertical (± 90 °), horizontal (0 °, 180 °), diagonal .

Alternatively, the filtering direction of each one-dimensional filter may be adaptively determined to the local image characteristic of the image data. For example, the edge of the local image in the image data may be detected, and the filter may be determined so that one-dimensional filtering is performed along the filtering direction along the detected edge direction.

It is possible to classify a plurality of one-dimensional filter sets into a sub-filter set including one or more successive one-dimensional filters, and to decide whether to perform one-dimensional filtering for each sub-filter set. That is, the filters of the same sub-filter set may all be determined whether filtering is performed or not.

It can be determined whether the result of the one-dimensional filtering of the previous pixel is a running filtering scheme that affects one-dimensional filtering of the current pixel. According to the one-dimensional filtering according to the running filtering method, as the filtering result of the previous pixel is updated, the filtering of the current pixel can be performed by continuously receiving the filtered data of the previous pixel.

FIG. 15 illustrates a video decoding apparatus that uses loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.

The video decoding apparatus 1500 according to an exemplary embodiment includes a receiving unit 1501, an extracting unit 1505, and a video data decoding unit 1540. The extraction unit 1505 includes an image data acquisition unit 1510, an encoding information extraction unit 1520, and a loop filter coefficient information extraction unit 1530. The image data decoding unit 1540 corresponds to the image data decoding unit 230 of the video decoding apparatus 200 described above with reference to FIG. 2, and the image data obtaining unit 1510 and the encoding information extracting unit 1520 And performs a part of the function of the extracting unit 220 of the video decoding apparatus 200.

However, the image data decoding unit 1540 includes a loop filtering performing unit 1550 that performs loop filtering by continuous one-dimensional filtering. Features for performing and decoding adaptive loop filtering by continuous one-dimensional filtering of the video decoding apparatus 1500 according to one embodiment are described below.

The receiving unit 1501 receives and parses a bitstream of the encoded video, and the extracting unit 1505 extracts various encoded information from the parsed bitstream. The image data obtaining unit 1510 can obtain the image data encoded per maximum encoding unit from the parsed received bitstream. The encoding information extracting unit 1520 parses the received bit stream, and extracts information on the encoding depth and the encoding mode for each maximum encoding unit from the header for the current picture.

The loop filter coefficient information extracting unit 1530 extracts filter coefficient information for loop filtering of the current picture. The loop filter coefficient information extracting unit 1530 can extract the filter coefficients of a plurality of one-dimensional filters when loop filtering is performed by continuous one-dimensional filtering.

The loop filter coefficient information extracting unit 1530 may extract residual information about difference values between successive filter coefficients for each one-dimensional filter among the plurality of one-dimensional filters of continuous one-dimensional filtering.

The image data decoding unit 1540 decodes the encoded image data of each maximum encoding unit based on information on the encoding depth and the encoding mode for each maximum encoding unit to reconstruct the current picture. The video data decoding unit 1540 performs deblocking on the data of the current picture decoded into the video data in the time domain and outputs the filter coefficients extracted from the loop filter coefficient information extracting unit 1530 to the deblocked data To perform loop filtering. Loop filtering may be performed separately for luma components and chroma components.

When the image data decoding unit 1540 according to an embodiment corresponds to the image decoding unit 500, the loop filtering unit 1550 of the image data decoding unit 1540 corresponds to the loop filtering unit 580, The deblocking unit 570 can perform continuous one-dimensional filtering on the data deblocked. The deblocked and loop filtered data is stored in a buffer and can be used as a reference picture for motion compensation of the next picture.

The loop filtering performing unit 1550 continuously performs one-dimensional filtering in the horizontal direction and one-dimensional filtering in the vertical direction, and restores the current picture. The loop filtering performing unit 1550 can derive the filter coefficients of each one-dimensional filter by using the residual information of the filter coefficients extracted from the loop filter coefficient information extracting unit 1530. [

For example, for each one-dimensional filter, the current filter coefficient may be derived by adding the difference between the current filter coefficient and the previous filter coefficient to the previous filter coefficient. Using the filter coefficients of each derived one-dimensional filter, continuous one-dimensional filtering can be performed on the deblocked data. Deblocking reduces the block effect of the decoded data, and loop filtering minimizes the error between the reconstructed image and the original image.

For a specific understanding of the invention, loop filtering by continuous one-dimensional filtering in the horizontal and vertical directions will be described below with reference to the mathematical expression.

The current filter coefficient can be derived according to equation (1).

Where i represents the index of the one-dimensional filter and j represents the index of the filter coefficient of each one-dimensional filter. c [i] [j] denotes the current filter coefficient, adaptive_loop_filter_prev [i] [j] denotes the previous filter coefficient, and adaptive_loop_filter [i] [j] denotes the residual component of the filter coefficient transmitted as the filter coefficient information.

That is, the current filter coefficient may be derived as the sum of the previous filter coefficient and the residual component. The current filter coefficient c [i] [j] is updated to adaptive_loop_filter_prev [i] [j] to derive the next filter coefficient after deriving the current filter coefficient.

Loop filtering by continuous one-dimensional filtering can be performed according to equations (2) and (3). In Equations (2) and (3), i represents the width direction index of the current picture, and j represents the height direction index of the current picture.

p _{i, j} represents the deblocked data of the current picture, and q _{i, j} represents the one-dimensional filtered data in the horizontal direction with respect to the deblocked data. Using the filter coefficient c of the symmetric filter, it is symmetrically filtered using five filter coefficients for the nine deblocked data.

f _{i, j} represents one-dimensional filtered data in the vertical direction with respect to q _{i, j} . Since the filter coefficient c follows the running filtering method, vertical one-dimensional filtering is continuously performed on the one-dimensional filtered data in the horizontal direction.

In the case of a symmetric filter, the advantage is that the coefficients of all filters can be set even if only a small number of coefficients are required for a one-dimensional filter compared to a two-dimensional filter. Thus, there is a relatively small number of bits associated with the filter characteristics that a plurality of one-dimensional filter sets should be inserted into the transmitted bitstream than a two-dimensional filter.

Also, the capacity of the memory for storing the temporary data during the filtering is smaller than that of the two-dimensional filter. The amount of computation of filtering by the two-dimensional filter is considerably larger than that of the one-dimensional filtering. In the case of running filtering, it is impossible to perform concurrent processing by multiple filtering which is impossible in two dimensions, but it is possible to perform concurrent processing by a one-dimensional filter.

However, loop filtering according to an embodiment is not limited to continuous one-dimensional filtering in the horizontal direction and the vertical direction. The loop filtering according to one embodiment can be implemented with continuous filtering of any number of one-dimensional filters, and each one-dimensional filtering can be performed in any direction.

In addition to the filter coefficient information, the video decoding apparatus 1500 according to an exemplary embodiment receives information on a one-dimensional filter set of loop filtering, and determines a type, a number, a size, a quantization bit, a coefficient, Whether or not filtering is performed, and whether or not running filtering is performed. Accordingly, the loop filtering performing unit 1550 can perform loop filtering by combining various one-dimensional filters.

The post-processing by loop filtering can reduce the distortion between the original image and the reconstructed image caused by complicated loss compression. Further, by using the loop-filtered image as a reference image, the image quality of a resultant image of prediction or motion compensation can be improved.

Through the combination of one-dimensional filters of various features, it is possible to perform adaptive loop filtering in consideration of image characteristics, system environment or user needs. In addition, since a continuous one-dimensional filter is used instead of a two-dimensional filter, it is advantageous in various aspects such as memory, calculation amount, and transmission bit compared to a two-dimensional filter. Furthermore, since the residual components of the filter coefficients are encoded and transmitted, the burden of transmitting the filter coefficients can be reduced.

Figure 16 shows a flow diagram of continuous one-dimensional filtering according to an embodiment of the present invention.

Loop filtering can be performed by successively filtering a plurality of one-dimensional filters. In step 1610, the deblocked restored image is input. In step 1620, it is determined whether all the filters of the first filter, the second filter, and the Nth filter are used. If it is determined not to use all the filters, . If it is determined in step 1620 to perform filtering by all of the filters, one-dimensional filtering of the first filtering direction using the first filter in step 1630, second filtering using the second filter in step 1640, One-dimensional filtering of the filtering direction, and one-dimensional filtering of the N-th filtering direction using the N-th filter in step 1650.

In step 1660, deblocked restored image data or successively one-dimensionally filtered data is stored in a buffer or reproduced in a playback apparatus.

17 shows a flowchart of loop filtering according to another embodiment of the present invention.

The filtering direction of the one-dimensional filter of one embodiment may be adaptively determined to the characteristics of the local image through analysis of the image characteristics. For example, the filtering direction may be adaptively determined to the edge direction of the local image to preserve the edge of the image.

If the restored image data is input in step 1710, an edge is detected for each pixel of the restored image data in step 1720. In step 1730, one-dimensional filtering is performed according to the detected edge direction, and the filtered data in step 1740 is stored or reproduced on the playback device.

Information regarding the first-order filter set including the filtering direction determined according to the edge direction in the video encoding process is encoded and provided to the decoding end. In the video decoding process, information about the loop filter is read from the received data, and one-dimensional filtering according to a filtering direction such as an edge direction of a predetermined one-dimensional filter can be performed.

18 shows a video encoding method using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.

In step 1810, the current picture is divided into at least one maximum coding unit, which is a coding unit of the maximum size. In step 1820, the coding unit is coded in at least one divided area, The depth at which the final encoding result is output is determined.

In step 1830, the image data, the encoding depth, and the encoding mode information encoded with one encoding depth are coded and output for each maximum encoding unit. In addition, the filter coefficient information of the loop filtering performed by continuous one-dimensional filtering after deblocking during coding of the current picture can be encoded and output. The filter coefficient information may include information on a residual component between successive filter coefficients. Loop filtering can be performed by continuous filtering of a one-dimensional filter in the horizontal direction and a one-dimensional filter in the vertical direction. The one-dimensional filter may be a symmetric filter, and the filter coefficient of the one-dimensional filter may be in accordance with the binar filter method.

19 shows a video decoding method using loop filtering by continuous one-dimensional filtering according to an embodiment of the present invention.

In step 1910, a bitstream for the encoded video is received and parsed.

The image data of the current picture allocated to the maximum encoding unit of the maximum size from the bitstream parsed in step 1920, and information on the encoding depth and encoding mode of each maximum encoding unit are extracted. Further, filter coefficient information for loop filtering of the current picture is extracted. The filter coefficient information may include information on a residual component between filter coefficients of each one-dimensional filter. The extracted filter coefficient information may be a coefficient of a one-dimensional filter in a horizontal direction and a one-dimensional filter in a vertical direction.

In step 1930, the encoded image data of the maximum encoding unit can be decoded based on the information on the encoding depth and the encoding mode for each encoding unit, and the encoding unit pattern information.

In step 1940, deblocking is performed on the decoded image data of the current picture, and loop filtering by continuous one-dimensional filtering is performed on the deblocked data. When the residual of the filter coefficient is extracted as the filter coefficient information, the current filter coefficient can be derived by adding the residual component of the filter coefficient and the previous filter coefficient. Continuous one-dimensional filtering can be performed using the filter coefficients derived for each one-dimensional filter. Loop filtering may be performed separately for luma components and chroma components.

Due to the large data amount of a large-capacity image or a high-resolution image, the computation amount may be very burdensome when the image is decoded by a relatively small-sized macro block. The present invention uses an encoding unit of a size appropriately selected for the image size, and divides the size of the encoding unit hierarchically according to the detailed information of the image even within the maximum size encoding unit. Based on an encoding unit of a hierarchical structure, encoding units having a minimum encoding error for each maximum encoding unit are determined. That is, efficient decoding can be performed based on a coding unit of a hierarchical structure.

In addition, in order to reduce the computational burden of post-processing on a large-capacity image or a high-resolution image, continuous one-dimensional filtering is introduced instead of two-dimensional filtering as loop filtering performed after deblocking. As a result, not only the spreading amount but also the transmission bit of the filter coefficient can be reduced. Further, the transmission efficiency can be further increased by transmitting the residual component of the filter coefficient instead of the filter coefficient.

The above-described embodiments of the present invention can be embodied in a general-purpose digital computer that can be embodied as a program that can be executed by a computer and operates the program using a computer-readable recording medium. The computer readable recording medium may be a magnetic storage medium such as a ROM, a floppy disk, a hard disk, etc., an optical reading medium such as a CD-ROM or a DVD and a carrier wave such as the Internet Lt; / RTI > transmission).

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (2)

Obtaining information on size information of a maximum coding unit which is a coding unit of the maximum size from the bitstream and whether to perform loop filtering to compensate the pixel value;
Dividing a picture based on size information of the maximum encoding unit and determining the maximum encoding unit;
Generating prediction data by performing prediction on at least one prediction unit in the maximum coding unit;
Performing inverse transform on at least one conversion unit in the maximum encoding unit to generate residual data;
Reconstructing the encoded image data of the maximum encoding unit using the prediction data and the residual data;
Determining a direction of an edge of the reconstructed image data of the maximum encoding unit; And
Performing loop filtering on deblocking filtered data of the reconstructed image data of the maximum encoding unit based on information on whether to perform the loop filtering,
The loop filtering is performed according to the determined direction of the edge,
Wherein the at least one conversion unit is determined independently of the at least one prediction unit. An extracting unit for obtaining size information of a maximum encoding unit which is an encoding unit of a maximum size from the bitstream and information on whether to perform loop filtering to compensate for pixel values; And
And a prediction unit for generating predictive data by performing prediction on at least one prediction unit in the maximum coding unit, and generating prediction data in at least one of the maximum coding unit and the maximum coding unit, Reconstructing the encoded image data of the maximum encoding unit using the predictive data and the residual data, and restoring the reconstructed image data of the maximum encoding unit by performing inverse transformation on one transform unit to generate residual data, Decodes the deblocking filtered data of the reconstructed image data of the maximum encoding unit based on information on whether to perform loop filtering or not, Including,
The loop filtering is performed according to the determined direction of the edge,
Wherein the at least one conversion unit is determined independently of the at least one prediction unit.

Images