A video encoding / decoding method and apparatus based on intra-prediction, and a recording medium for storing bitstreams.

Abstract

A video encoding / decoding method and apparatus are provided. The video decoding method relating to this disclosure includes the steps of: acquiring one or more candidate intra-prediction information based on intra-prediction information of surrounding blocks of the current block; constructing an intra-prediction candidate list based on the one or more candidate intra-prediction information; acquiring an intra-prediction candidate index indicating one of the candidate intra-prediction information included in the intra-prediction candidate list; and generating a predicted block of the current block by performing intra-prediction based on the candidate intra-prediction information indicated by the intra-prediction candidate index. The candidate intra-prediction information includes TIMD (Template based intra mode derivation) information, DIMD (Decoder side intra mode derivation) information or linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra smoothing) information, and CIIP (combined inter and intra It may include at least one of the following: prediction information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion information, peripheral reference sample characteristics information, or IBC (intra block copy) information.

Description

Technical Field

[0001] The present disclosure relates to a video encoding / decoding method and apparatus, and a recording medium for storing a bitstream, and particularly to a video encoding / decoding method and apparatus based on intra prediction, and a recording medium for storing a bitstream generated by the video encoding method / apparatus of the present disclosure.

Background Art

[0002] In recent years, the demand for high-resolution and high-quality videos such as HD (High Definition) videos and UHD (Ultra High Definition) videos has been increasing in various fields. As video data becomes higher in resolution and quality, the amount of information or bits to be transmitted increases more compared to existing video data. The increase in the amount of information or bits to be transmitted leads to an increase in transmission costs and storage costs.

[0003] Therefore, a highly efficient video compression technique for effectively transmitting, storing, and playing back information of high-resolution and high-quality videos is desired.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a video encoding / decoding method and apparatus with improved encoding / decoding efficiency.

[0005] Another object of the present disclosure is to provide a video encoding / decoding method and apparatus that effectively performs intra prediction.

[0006] Another object of the present disclosure is to provide a video encoding / decoding method and apparatus that effectively generates an intra prediction candidate list.

[0007] Another object of the present disclosure is to provide a video encoding / decoding method and apparatus that includes various prediction modes when generating an intra prediction candidate list.

[0008] Furthermore, this disclosure aims to provide a non-temporary computer-readable recording medium for storing a bitstream generated by a video encoding method or apparatus relating to this disclosure.

[0009] Furthermore, this disclosure aims to provide a non-temporary computer-readable recording medium that stores a bitstream that is received and decoded by the video decoding device relating to this disclosure and used for restoring video.

[0010] Furthermore, this disclosure aims to provide a method for transmitting a bitstream generated by a video encoding method or apparatus relating to this disclosure.

[0011] The technical challenges addressed in this disclosure are not limited to those mentioned above, and other technical challenges not mentioned above will be clearly understood by those with ordinary skill in the art to which this disclosure pertains from the following description. [Means for solving the problem]

[0012] According to one embodiment of the present disclosure, a video decoding method performed by a video decoding device includes the steps of: acquiring one or more candidate intra-prediction information based on intra-prediction information of surrounding blocks of the current block; configuring an intra-prediction candidate list based on the one or more candidate intra-prediction information; acquiring an intra-prediction candidate index indicating one of the candidate intra-prediction information included in the intra-prediction candidate list; and generating a predicted block of the current block by performing intra-prediction based on the candidate intra-prediction information indicated by the intra-prediction candidate index, wherein the candidate intra-prediction information includes TIMD (Template based intra mode derivation) information, DIMD (Decoder side intra mode derivation) information or linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra smoothing) information, CIIP (combined inter and It may include at least one of the following: intra prediction information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion information, peripheral reference sample characteristics information, or IBC (intra block copy) information.

[0013] According to one embodiment of the present disclosure, the peripheral block may be determined based on one of the following: template matching, bi-lateral matching, or SATD (Sum of absolute transformed differences).

[0014] According to one embodiment of the present disclosure, the intra-prediction candidate index may be determined based on one of the following: template matching, bi-lateral matching, or SATD (Sum of absolute transformed differences).

[0015] According to one embodiment of the present disclosure, the order of the candidate intra-prediction information included in the intra-prediction candidate list may be re-ordered based on one of template matching or bidirectional matching.

[0016] According to one embodiment of the present disclosure, the candidate intra-prediction information may include information regarding whether or not the candidate intra-prediction mode is applicable.

[0017] According to one embodiment of the present disclosure, the candidate intra-prediction information may further include additional information used for applying the corresponding candidate intra-prediction mode.

[0018] According to one embodiment of the present disclosure, the prediction block may be generated based on at least one of the candidate intra-prediction mode or the additional information.

[0019] According to one embodiment of the present disclosure, the number of candidate intra-prediction information included in the intra-prediction candidate list may be determined based on at least one of the following: the size of the current block, the location of subblocks within the current block, the statistical characteristics of the surrounding blocks, or whether a quadratic transformation is used on the current block.

[0020] According to one embodiment of the present disclosure, the acquisition order of the surrounding blocks may be determined based on at least one of the following: the size of the current block, the position of subblocks within the current block, the statistical characteristics of the surrounding blocks, or whether a quadratic transformation is used on the current block.

[0021] According to one embodiment of the present disclosure, the position of the surrounding block may be determined based on at least one of the following: the size of the current block, the position of subblocks within the current block, the statistical characteristics of the surrounding block, or whether a quadratic transformation is used on the current block.

[0022] According to one embodiment of the present disclosure, based on the fact that the current block is a color difference block, the intra-prediction candidate list may be configured based on first candidate intra-prediction information of surrounding blocks of the color difference block and second candidate intra-prediction information of rumor blocks corresponding to the color difference block.

[0023] According to one embodiment of the present disclosure, based on the fact that the second candidate intra-prediction information includes the linear model information, the intra-prediction candidate list may include at least one of the first intra-prediction candidate list composed of the linear model information or the second intra-prediction candidate list composed of information other than the linear model information.

[0024] According to one embodiment of the present disclosure, a video encoding method performed by a video encoding device includes the steps of: acquiring one or more candidate intra-prediction information based on intra-prediction information of surrounding blocks of the current block; configuring an intra-prediction candidate list based on the one or more candidate intra-prediction information; generating a predicted block of the current block based on one candidate intra-prediction information included in the intra-prediction candidate list; and encoding an intra-prediction candidate index indicating the one candidate intra-prediction information, wherein the candidate intra-prediction information is TIMD (Template based intra mode derivation) information, DIMD (Decoder side intra mode derivation) information or linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition) information. It may include at least one of the following: mode information, intra-TMP (template matching intra prediction) information, in-screen prediction direction mode information, extended planar information, intra-prediction fusion information, peripheral reference sample characteristic information, or IBC (intra block copy) information.

[0025] According to one embodiment of the present disclosure, the computer-readable recording medium may store a bitstream generated by a video encoding method.

[0026] According to an embodiment of the present disclosure, a method for transmitting a bitstream generated by a video encoding method, the video encoding method including: obtaining one or more candidate intra prediction information based on intra prediction information of surrounding blocks of a current block; constructing an intra prediction candidate list based on the one or more candidate intra prediction information; generating a predicted block of the current block based on one candidate intra prediction information included in the intra prediction candidate list; and encoding an intra prediction candidate index indicating the one candidate intra prediction information, wherein the candidate intra prediction information may include at least one of TIMD (Template based intra mode derivation) information, DIMD (Decoder side intra mode derivation) information, linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra TMP (template matching intra prediction) information, in-plane prediction direction mode information, extended planar information, Intra prediction fusion information, surrounding reference sample characteristic information, or IBC (intra block copy) information.

Advantages of the Invention

[0027] According to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus with improved encoding / decoding efficiency.

[0028] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that effectively perform intra prediction.

[0029] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that effectively generate an intra prediction candidate list.

[0030] Also, according to the present disclosure, it is possible to provide a video encoding / decoding method and apparatus that include various prediction modes when generating an intra prediction candidate list.

[0031] Also, according to the present disclosure, it is possible to provide a non-temporary computer-readable recording medium that stores a bitstream generated by the video encoding method or apparatus according to the present disclosure.

[0032] Also, according to the present disclosure, it is possible to provide a non-temporary computer-readable recording medium that stores a bitstream received and decoded by the video decoding apparatus according to the present disclosure and used for video restoration.

[0033] Also, according to the present disclosure, it is possible to provide a method for transmitting a bitstream generated by the video encoding method or apparatus according to the present disclosure.

[0034] The effects obtained by the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those of ordinary skill in the art to which the present disclosure pertains from the following description.

Brief Description of the Drawings

[0035] [Figure 1] It is a schematic diagram showing a video coding system to which an embodiment according to the present disclosure can be applied. [Figure 2]This is a schematic diagram showing a video encoding device to which the embodiments of this disclosure can be applied. [Figure 3] This is a schematic diagram showing an image decoding device to which the embodiments of this disclosure can be applied. [Figure 4] This is a flowchart of an intra-predictive-based video / image encoding method. [Figure 5] This diagram illustrates the configuration of the intra-prediction unit related to this disclosure. [Figure 6] This is a flowchart of an intra-predictive-based video / image decoding method. [Figure 7] This diagram illustrates the configuration of the intra-prediction unit related to this disclosure. [Figure 8] This figure shows the template area used in the TIMD (Template-based Intra Mode Derivation) mode related to this disclosure. [Figure 9] This is a diagram illustrating the template matching-based encoding / decoding method related to this disclosure. [Figure 10] This figure shows the positions of surrounding blocks for constituting an intra-prediction candidate list according to one embodiment of the present disclosure. [Figure 11] This figure shows the location of the surrounding block search according to one embodiment of the present disclosure. [Figure 12] This is a flowchart showing the method for applying the merger mode related to this disclosure. [Figure 13] This figure shows the search position of the corresponding rumor block according to one embodiment of the present disclosure. [Figure 14] This is a flowchart showing a method for applying the merged mode according to one embodiment of the present disclosure. [Figure 15] This flowchart shows an encoding method according to one embodiment of the present disclosure. [Figure 16] This is a flowchart showing a decoding method according to one embodiment of the present disclosure. [Figure 17] This figure illustrates a content streaming system to which the embodiments of this disclosure can be applied. [Modes for carrying out the invention]

[0036] Hereafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present disclosure pertains. However, the present disclosure may be embodied in various other forms and is not limited to the embodiments described herein.

[0037] In describing embodiments of this disclosure, if a specific description of a known configuration or function is deemed to obscure the gist of this disclosure, such detailed description will be omitted. In the figures, parts unrelated to the description of this disclosure will be omitted, and similar parts will be denoted by similar reference numerals.

[0038] In this disclosure, when one component is described as being “linked,” “joined,” or “connected” to another component, this may include not only direct linkages but also indirect linkages where other components exist in between. Furthermore, when one component is described as “containing” or “having” another component, this means, unless otherwise specified, that it may contain further other components rather than excluding them.

[0039] In this disclosure, terms such as "first," "second," etc., are used solely to distinguish one component from another, and do not limit the order or importance of the components unless otherwise specified. Therefore, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

[0040] In this disclosure, components are distinguished from each other solely to clearly describe their respective characteristics, and this does not necessarily mean that these components are separate. That is, multiple components may be integrated to constitute a single hardware or software unit, or a single component may be distributed to constitute multiple hardware or software units. Therefore, such integrated or distributed embodiments are also included in the scope of this disclosure, even without specific mention.

[0041] In this disclosure, the components described in various embodiments are not necessarily essential components, and some may be optional components. Therefore, embodiments consisting of a subset of the components described in one embodiment are also included in the scope of this disclosure. Furthermore, embodiments that further include other components in addition to the components described in various embodiments are also included in the scope of this disclosure.

[0042] This disclosure relates to the encoding and decoding of video, and the terms used in this disclosure may have their ordinary meanings in the art to which this disclosure pertains, unless newly defined in this disclosure.

[0043] In this disclosure, "video" can mean a collection of images in a sequence of time.

[0044] In this disclosure, "picture" generally refers to a unit representing a single video image for a specific time period, and "slice / tile" is an encoding unit that constitutes a part of a picture. A single picture may consist of one or more slices / tiles. A slice / tile may also contain one or more CTUs (coding tree units).

[0045] In this disclosure, “pixel” or “pel” can mean the smallest unit that constitutes a picture (or video). The term “sample” may also be used as a term corresponding to pixel. A sample may generally represent a pixel or a pixel value, or it may represent only the pixel / pixel value of the luma component, or only the pixel / pixel value of the chroma component.

[0046] In this disclosure, “unit” may represent a basic unit of image processing. A unit may include at least one of a specific region of a picture and information associated with that region. A unit may, as it may be, be replaced by terms such as “sample array,” “block,” or “area.” In general, an MxN block may include a set (or array) of samples (or sample arrays) or transform coefficients consisting of M columns and N rows.

[0047] In this disclosure, “current block” can mean one of the following: “current coding block,” “current coding unit,” “block to encode,” “block to decode,” or “block to process.” When prediction is performed, “current block” can mean “current prediction block” or “block to predict.” When transformation (inverse transformation) / quantization (inverse quantization) is performed, “current block” can mean “current transformation block” or “block to transform.” When filtering is performed, “current block” can mean “block to filter.”

[0048] In this disclosure, "current block" may mean a block containing both a rumor component block and a chroma component block, or "the rumor block of the current block," unless otherwise explicitly stated as a chroma block. The rumor component block of the current block may be expressed with an explicit mention of a rumor component block, such as "ruma block" or "current ruma block." Similarly, the chroma component block of the current block may be expressed with an explicit mention of a chroma component block, such as "chroma block" or "current chroma block."

[0049] In this disclosure, " / " and "," may be interpreted as "and / or." For example, "A / B" and "A, B" may be interpreted as "A and / or B." Also, "A / B / C" and "A, B, C" may mean "at least one of A, B and / or C."

[0050] In this disclosure, “or” may be interpreted as “and / or.” For example, “A or B” may mean 1) “A” only, 2) “B” only, or 3) “A and B.” Alternatively, in this disclosure, “or” may mean “additionally or alternatively.”

[0051] In this disclosure, “at least one A, B, and C” can mean “A only,” “B only,” “C only,” or “any combination of A, B, and C.” Also, “at least one A, B, or C” or “at least one A, B, and / or C” can mean “at least one A, B, and C.”

[0052] The parentheses used in this disclosure may mean "for example." For example, when "prediction (intra prediction)" is written, "intra prediction" may be proposed as an example of "prediction." In other words, "prediction" in this disclosure is not limited to "intra prediction," and "intra prediction" may be proposed as an example of "prediction." Similarly, when "prediction (i.e., intra prediction)" is written, "intra prediction" may be proposed as an example of "prediction."

[0053] Overview of the video coding system

[0054] Figure 1 is a schematic diagram showing a video coding system to which the embodiments of this disclosure can be applied.

[0055] A video coding system according to one embodiment may include an encoding device 10 and a decoding device 20. The encoding device 10 can transmit encoded video and / or image information or data to the decoding device 20 in file or streaming form via a digital storage medium or network.

[0056] An encoding device 10 according to one embodiment may include a video source generation unit 11, an encoding unit 12, and a transmission unit 13. A decoding device 20 according to one embodiment may include a receiving unit 21, a decoding unit 22, and a rendering unit 23. The encoding unit 12 may be called a video / image encoding unit, and the decoding unit 22 may be called a video / image decoding unit. The transmission unit 13 may be included in the encoding unit 12. The receiving unit 21 may be included in the decoding unit 22. The rendering unit 23 may include a display unit, and the display unit may be composed of a separate device or external component.

[0057] The video source generation unit 11 can acquire video / images through video / image capture, synthesis, or generation processes. The video source generation unit 11 may include a video / image capture device and / or a video / image generation device. The video / image capture device may include, for example, one or more cameras, or a video / image archive containing previously captured video / images. The video / image generation device may include, for example, a computer, a tablet, and a smartphone, and can generate video / images (electronically). For example, virtual video / images may be generated by a computer, in which case the video / image capture process may be replaced by a process in which related data is generated.

[0058] The encoding unit 12 can encode the input video / image data. The encoding unit 12 can perform a series of procedures such as prediction, transformation, and quantization for compression and encoding efficiency. The encoding unit 12 can output the encoded data (encoded video / image information) in the form of a bitstream.

[0059] The transmitting unit 13 can acquire encoded video / image information or data output in bitstream form and transmit it in file or streaming form to the receiving unit 21 of the decoding device 20 or other external object via a digital storage medium or network. The digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmitting unit 13 may include elements for generating media files in a predetermined file format and may include elements for transmission via a broadcast / communication network. The transmitting unit 13 may be provided as a transmission device separate from the encoding unit 12, in which case the transmission device may include at least one processor that acquires encoded video / image information or data output in bitstream form and a transmitting unit that transmits it in file or streaming form. The receiving unit 21 can extract / receive the bitstream from the storage medium or network and transmit it to the decoding unit 22.

[0060] The decoding unit 22 can decode the video / image by performing a series of procedures such as inverse quantization, inverse transform, and prediction, which correspond to the operation of the encoding unit 12.

[0061] The rendering unit 23 can render the decoded video / image. The rendered video / image may be displayed through the display unit.

[0062] Overview of video encoding equipment

[0063] Figure 2 is a schematic diagram showing a video encoding device to which the embodiments of this disclosure can be applied.

[0064] As shown in Figure 2, the video encoding device 100 may include a video splitting unit 110, a subtraction unit 115, a conversion unit 120, a quantization unit 130, an inverse quantization unit 140, an inverse conversion unit 150, an addition unit 155, a filtering unit 160, a memory 170, an inter-prediction unit 180, an intra-prediction unit 185, and an entropy encoding unit 190. The inter-prediction unit 180 and the intra-prediction unit 185 may be collectively called the "prediction unit". The conversion unit 120, the quantization unit 130, the inverse quantization unit 140, and the inverse conversion unit 150 may be included in the residual processing unit. The residual processing unit may further include a subtraction unit 115.

[0065] Depending on the embodiment, all or at least some of the multiple components constituting the video encoding device 100 may be embodied as a single hardware component (e.g., an encoder or a processor). Furthermore, the memory 170 may include a DPB (decoded picture buffer) and may be embodied by a digital storage medium.

[0066] The video splitting unit 110 can split the input video (or picture, frame) input to the video encoding device 100 into one or more processing units. For example, the processing units may be called coding units (CUs). Coding units can be obtained by recursively splitting a coding tree unit (CTU) or the largest coding unit (LCU) using a QT / BT / TT (Quad-tree / binary-tree / ternary-tree) structure. For example, one coding unit may be split into multiple coding units of deeper depth based on a quad-tree structure, a binary-tree structure, and / or a ternary-tree structure. For the splitting of coding units, a quad-tree structure may be applied first, followed by a binary-tree structure and / or a ternary-tree structure. The coding procedure according to this disclosure may be performed based on the final coding unit that is not further split. The maximum coding unit may be used directly as the final coding unit, or a lower-depth coding unit obtained by dividing the maximum coding unit may be used as the final coding unit. Here, the coding procedure may include procedures such as prediction, transformation, and / or restoration, which will be described later. As another example, the processing unit of the coding procedure may be a prediction unit (PU) or a transformation unit (TU). The prediction unit and the transformation unit may be divided or partitioned from the final coding unit, respectively. The prediction unit may be a unit of sample prediction, and the transformation unit may be a unit that derives transformation coefficients and / or a unit that derives a residual signal from transformation coefficients.

[0067] The prediction unit (inter-prediction unit 180 or intra-prediction unit 185) can make predictions for the block to be processed (current block) and generate a predicted block that includes prediction samples for the current block. The prediction unit can determine whether intra-prediction or inter-prediction is applied to the current block or on a CU basis. The prediction unit can generate various information regarding the prediction of the current block and transmit it to the entropy encoding unit 190. The prediction information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

[0068] The intra-prediction unit 185 can predict the current block by referring to a sample in the current picture. The referenced sample may be located in the vicinity of the current block or at a distance from it, depending on the intra-prediction mode and / or intra-prediction method. The intra-prediction mode may include a plurality of non-directional modes and a plurality of directional modes. The non-directional modes may include, for example, a DC mode and a planar mode. The directional modes may include, for example, 33 directional prediction modes or 65 directional prediction modes, depending on the accuracy of the prediction direction. However, this is an example, and more or fewer directional prediction modes may be used depending on the settings. The intra-prediction unit 185 can also determine the prediction mode to be applied to the current block using the prediction modes applied to the surrounding blocks.

[0069] The interprediction unit 180 can derive a predicted block relative to the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in units of blocks, subblocks, or samples based on the correlation of motion information between the surrounding blocks and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, the surrounding blocks may include spatial neighboring blocks existing in the current picture and temporal neighboring blocks existing in the reference picture. The reference picture containing the reference block and the reference picture containing the temporal neighboring block may be the same or different from each other. The temporal neighboring block may be called a collocated reference block, colCU, etc. The reference picture containing the temporal neighboring block may be called a collocated picture (colPic). For example, the interpretation unit 180 can construct a motion information candidate list based on surrounding blocks and generate information indicating which candidate is used to derive the motion vector and / or reference picture index of the current block. Interpretation may be performed based on various prediction modes; for example, in skip mode and merge mode, the interpretation unit 180 can use the motion information of surrounding blocks as the motion information of the current block. In skip mode, unlike merge mode, the residual signal does not need to be transmitted.In motion vector prediction (MVP) mode, the motion vectors of surrounding blocks are used as motion vector predictors, and the motion vector of the current block can be signaled by encoding the motion vector difference and an indicator for the motion vector predictor. The motion vector difference represents the difference between the motion vector of the current block and the motion vector predictor.

[0070] The prediction unit can generate a prediction signal based on various prediction methods and / or prediction techniques described later. For example, the prediction unit may apply intra-prediction or inter-prediction to predict the current block, or it may apply intra-prediction and inter-prediction simultaneously. A prediction method that applies intra-prediction and inter-prediction simultaneously to predict the current block may be called CIIP (combined inter and intra prediction). The prediction unit can also perform intra-block copy (IBC) to predict the current block. Intra-block copy may be used, for example, for coding content images / videos such as games, as in SCC (screen content coding). IBC is a method of predicting the current block using a reference block that has already been restored in the current picture at a predetermined distance from the current block. When IBC is applied, the position of the reference block in the current picture may be encoded as a vector (block vector) corresponding to the predetermined distance. IBC basically performs prediction within the current picture, but it may be performed similarly to inter-prediction in that it derives the reference block within the current picture. In other words, IBC can use at least one of the interpretation methods described in this disclosure.

[0071] The predicted signal generated by the prediction unit may be used to generate a restored signal or a residual signal. The subtraction unit 115 can generate a residual signal (residual block, residual sample array) by subtracting the predicted signal output from the prediction unit (predicted block, predicted sample array) from the input video signal (original block, original sample array). The generated residual signal may be transmitted to the conversion unit 120.

[0072] The transformation unit 120 can generate transformation coefficients by applying a transformation method to the residual signal. For example, the transformation method may include at least one of the following: DCT (Discrete Cosine Transform), DST (Discrete Sine Transform), KLT (Karhunen-Loeve Transform), GBT (Graph-Based Transform), or CNT (Conditionally Non-linear Transform). Here, GBT refers to the transformation obtained from a graph when the relationship information between pixels is represented by this graph. CNT refers to the transformation obtained by generating a prediction signal using all previously reconstructed pixels and obtaining a transformation based on it. The transformation process may be applied to pixel blocks of the same size and square shape, or to blocks of a variable size instead of square shape.

[0073] The quantization unit 130 can quantize the conversion coefficients and transmit them to the entropy encoding unit 190. The entropy encoding unit 190 can encode the quantized signal (information about the quantized conversion coefficients) and output it as a bitstream. The information about the quantized conversion coefficients may be called residual information. The quantization unit 130 can rearrange the block-shaped quantized conversion coefficients into a one-dimensional vector form based on the coefficient scan order, and can also generate information about the quantized conversion coefficients based on the one-dimensional vector form of the quantized conversion coefficients.

[0074] The entropy encoding unit 190 can perform various encoding methods, such as exponential Golomb, CAVLC (context-adaptive variable length coding), and CABAC (context-adaptive binary arithmetic coding). In addition to the quantized conversion coefficients, the entropy encoding unit 190 can also encode information necessary for video / image restoration (e.g., the values ​​of syntax elements) together or separately. The encoded information (e.g., encoded video / image information) may be transmitted or stored in the form of a bitstream in units of NAL (network abstraction layer) units. The video / image information may further include information about various parameter sets, such as an adaptation parameter set (APS), picture parameter set (PPS), sequence parameter set (SPS), or video parameter set (VPS). The video / image information may also further include general constraint information. The signaling information, transmitted information, and / or syntax elements referred to in this disclosure may be encoded by the encoding procedure described above and included in the bitstream.

[0075] The bitstream may be transmitted over a network or stored on a digital storage medium. Here, the network may include broadcasting networks and / or communication networks, and the digital storage medium may include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. A transmitting unit (not shown) for transmitting the signal output from the entropy encoding unit 190 and / or a storage unit (not shown) for storing it may be provided as an internal / external element of the video encoding device 100, or the transmitting unit may be provided as a component of the entropy encoding unit 190.

[0076] The quantized conversion coefficients output from the quantization unit 130 may be used to generate a resistive signal. For example, by applying inverse quantization and inverse transformation to the quantized conversion coefficients in the inverse quantization unit 140 and the inverse transformation unit 150, a resistive signal (residual block or resistive sample) can be reconstructed.

[0077] The adder 155 can generate a reconstructed signal (reconstructed picture, reconstructed block, reconstructed sample array) by adding the reconstructed residual signal to the predicted signal output from the inter-prediction unit 180 or the intra-prediction unit 185. When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block may be used as the reconstructed block. The adder 155 may be called the reconstruction unit or the reconstructed block generation unit. The generated reconstructed signal may be used for intra-prediction of the next block to be processed in the current picture, or, as described later, may be used for inter-prediction of the next picture after filtering.

[0078] On the other hand, LMCS (luma mapping with chroma scaling) may be applied during the picture encoding and / or restoration process.

[0079] The filtering unit 160 can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit 160 can apply various filtering methods to the restored picture to generate a modified restored picture, and store the modified restored picture in the memory 170, specifically in the DPB of the memory 170. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter. The filtering unit 160 can generate various filtering information and transmit it to the entropy encoding unit 190, as will be described later in the description of each filtering method. The filtering information may be encoded by the entropy encoding unit 190 and output in the form of a bitstream.

[0080] The corrected restored picture transmitted to memory 170 may be used as a reference picture in the interpretation unit 180. This allows the video encoding device 100 to avoid prediction mismatches between the video encoding device 100 and the video decoding device when interpretation is applied, and also improves encoding efficiency.

[0081] The DPB in memory 170 can store the corrected restored picture for use as a reference picture in the inter-prediction unit 180. Memory 170 can store motion information of blocks from which motion information in the current picture has been derived (or encoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information may be transmitted to the inter-prediction unit 180 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 170 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 185.

[0082] Overview of the video decoding device

[0083] Figure 3 is a schematic diagram showing an image decoding device to which the embodiments of this disclosure can be applied.

[0084] As shown in Figure 3, the video decoding device 200 may include an entropy decoding unit 210, an inverse quantization unit 220, an inverse transformation unit 230, an addition unit 235, a filtering unit 240, a memory 250, an inter-prediction unit 260, and an intra-prediction unit 265. The inter-prediction unit 260 and the intra-prediction unit 265 can be collectively referred to as the "prediction unit". The inverse quantization unit 220 and the inverse transformation unit 230 may be included in the residual processing unit.

[0085] All or at least some of the multiple components constituting the video decoding device 200 may be embodied as a single hardware component (e.g., a decoder or processor) depending on the embodiment. Furthermore, the memory 170 may include a DPB and may be embodied by a digital storage medium.

[0086] A video decoding device 200 that receives a bitstream containing video / image information can restore the image by performing a process corresponding to the process performed by the video encoding device 100 in Figure 2. For example, the video decoding device 200 can perform decoding using the processing unit applied in the video encoding device. Therefore, the decoding processing unit may be, for example, a coding unit. The coding unit may be a coding tree unit, or it may be obtained by dividing the largest coding unit. The restored video signal decoded and output by the video decoding device 200 may then be played back by a playback device (not shown).

[0087] The video decoding device 200 can receive the signal output from the video encoding device shown in Figure 2 in the form of a bitstream. The received signal may be decoded by the entropy decoding unit 210. For example, the entropy decoding unit 210 can parse the bitstream to derive information necessary for video restoration (or picture restoration) (e.g., video / image information). The video / image information may further include information about various parameter sets, such as an adaptation parameter set (APS), a picture parameter set (PPS), a sequence parameter set (SPS), or a video parameter set (VPS). The video / image information may also further include general constraint information. The video decoding device may further utilize the parameter set information and / or the general constraint information to decode the video. The signaling information, received information, and / or syntax elements referred to in this disclosure may be obtained from the bitstream by decoding through the decoding procedure. For example, the entropy decoding unit 210 can decode information in the bitstream based on a coding method such as exponential Golomb coding, CAVLC, or CABAC, and output the values ​​of syntax elements necessary for image restoration and the quantized values ​​of conversion coefficients related to the residual. More specifically, the CABAC entropy decoding method receives bins corresponding to each syntax element in the bitstream, determines a context model using the syntax element information to be decoded and the decoding information of the surrounding blocks and the blocks to be decoded, or symbol / bin information decoded in a previous stage, predicts the probability of bin occurrence based on the determined context model, performs arithmetic decoding of the bins, and generates symbols corresponding to the values ​​of each syntax element.In this case, the CABAC entropy decoding method can update the context model using the decoded symbol / bin information for the context model of the next symbol / bin after determining the context model. Information related to prediction from the information decoded by the entropy decoding unit 210 is provided to the prediction unit (inter-prediction unit 260 and intra-prediction unit 265), and residual values ​​that have been entropy decoded by the entropy decoding unit 210, i.e., quantized conversion coefficients and related parameter information, may be input to the inverse quantization unit 220. In addition, information related to filtering from the information decoded by the entropy decoding unit 210 may be provided to the filtering unit 240. On the other hand, a receiving unit (not shown) that receives signals output from the video encoding device may be further provided as an internal / external element of the video decoding device 200, or the receiving unit may be provided as a component of the entropy decoding unit 210.

[0088] On the other hand, the video decoding device according to this disclosure may be called a video / image / picture decoding device. The video decoding device may include an information decoder (video / image / picture information decoder) and / or a sample decoder (video / image / picture sample decoder). The information decoder may include an entropy decoding unit 210, and the sample decoder may include at least one of an inverse quantization unit 220, an inverse transformation unit 230, an addition unit 235, a filtering unit 240, a memory 250, an inter-prediction unit 260, and an intra-prediction unit 265.

[0089] The inverse quantization unit 220 can inverse quantize the quantized transformation coefficients and output the transformation coefficients. The inverse quantization unit 220 can rearrange the quantized transformation coefficients in a two-dimensional block form. In this case, the rearrangement may be performed based on the coefficient scan order performed by the video encoding device. The inverse quantization unit 220 can perform inverse quantization on the quantized transformation coefficients using quantization parameters (e.g., quantization step size information) and obtain the transformation coefficients.

[0090] The inverse conversion unit 230 can inversely convert the conversion coefficients to obtain residual signals (residual blocks, residual sample arrays).

[0091] The prediction unit can make predictions for the current block and generate a predicted block containing prediction samples for the current block. Based on the prediction information output from the entropy decoding unit 210, the prediction unit can determine whether intra-prediction or inter-prediction is applied to the current block and can determine a specific intra / inter-prediction mode (prediction method).

[0092] As mentioned in the description of the prediction unit of the video coding device 100, the prediction unit can generate prediction signals based on various prediction methods (techniques) described later.

[0093] The intra-prediction unit 265 can predict the current block by referring to the samples in the current picture. The description of the intra-prediction unit 185 may also apply to the intra-prediction unit 265.

[0094] The interprediction unit 260 can derive a predicted block relative to the current block based on a reference block (reference sample array) identified by motion vectors on the reference picture. In this case, in order to reduce the amount of motion information transmitted in interprediction mode, motion information can be predicted in block, subblock, or sample units based on the correlation of motion information between the surrounding block and the current block. The motion information may include motion vectors and reference picture indices. The motion information may further include interprediction direction information (L0 prediction, L1 prediction, Bi prediction, etc.). In the case of interprediction, the surrounding block may include spatially neighboring blocks present in the current picture and temporally neighboring blocks present in the reference picture. For example, the interprediction unit 260 can construct a motion information candidate list based on the surrounding blocks and derive the motion vector and / or reference picture index of the current block based on the received candidate selection information. Interprediction may be performed based on various prediction modes (methods), and the prediction information may include information indicating the mode (method) of interprediction for the current block.

[0095] The adder 235 can generate a restored signal (restored picture, restored block, restored sample array) by adding the acquired residual signal to the predicted signal (predicted block, predicted sample array) output from the prediction unit (including the inter-prediction unit 260 and / or intra-prediction unit 265). When there is no residual for the block to be processed, such as when skip mode is applied, the predicted block may be used as the restored block. The description of the adder 155 may also apply to the adder 235. The adder 235 may be called the restore unit or the restored block generation unit. The generated restored signal may be used for intra-prediction of the next block to be processed in the current picture, or, as described later, may be used for inter-prediction of the next picture after filtering.

[0096] The filtering unit 240 can improve subjective / objective image quality by applying filtering to the restored signal. For example, the filtering unit 240 can apply various filtering methods to the restored picture to generate a modified restored picture, and the modified restored picture can be stored in the memory 250, specifically in the DPB of the memory 250. The various filtering methods may include, for example, deblocking filtering, sample adaptive offset, adaptive loop filter, and bilateral filter.

[0097] The restored picture stored (modified) in the DPB of memory 250 may be used as a reference picture in the inter-prediction unit 260. Memory 250 can store motion information of blocks from which motion information in the current picture has been derived (or decoded) and / or motion information of blocks in the picture that have already been restored. The stored motion information can be transmitted to the inter-prediction unit 260 for use as motion information of spatially surrounding blocks or motion information of temporally surrounding blocks. Memory 250 can store restored samples of restored blocks in the current picture and transmit them to the intra-prediction unit 265.

[0098] In this specification, the embodiments described for the filtering unit 160, inter-prediction unit 180, and intra-prediction unit 185 of the video encoding device 100 may be applied identically or in a corresponding manner to the filtering unit 240, inter-prediction unit 260, and intra-prediction unit 265 of the video decoding device 200, respectively.

[0099] Overview of Intra Prediction

[0100] The following describes the intranet prediction related to this disclosure.

[0101] Intra prediction can mean a prediction that generates predicted samples for the current block based on reference samples within the picture to which the current block belongs (hereinafter, the current picture). When intra prediction is applied to the current block, surrounding reference samples to be used for intra prediction of the current block may be derived. The surrounding reference samples of the current block may include a total of 2 x nH samples adjacent to the left boundary and bottom-left of the nW x nH size current block, a total of 2 x nW samples adjacent to the top boundary and top-right of the current block, and one sample adjacent to the top-left of the current block. Alternatively, the surrounding reference samples of the current block may include upper surrounding samples in multiple columns and left surrounding samples in multiple rows. Furthermore, the surrounding reference samples of the current block may include a total of nH samples adjacent to the right boundary of the current block, which is nW x nH in size, a total of nW samples adjacent to the bottom boundary of the current block, and one sample adjacent to the bottom-right side of the current block.

[0102] However, some of the surrounding reference samples in the current block may not yet be decoded or available. In this case, the decoder can substitute the unavailable samples with available samples to construct the surrounding reference samples used for prediction. Alternatively, it can construct the surrounding reference samples used for prediction by interpolating the available samples.

[0103] If a neighboring reference sample is derived, (i) a predicted sample can be derived based on the average or interpolation of the neighboring reference samples of the current block, and (ii) the predicted sample can be derived based on a reference sample among the neighboring reference samples of the current block that is located in a specific (predicted) direction relative to the predicted sample. Case (i) can be called a non-directional mode or non-angular mode, and case (ii) can be called a directional mode or angular mode.

[0104] Alternatively, the predicted sample may be generated by interpolation between a first peripheral sample located in the prediction direction of the intra-prediction mode of the current block and a second peripheral sample located in the opposite direction, based on the predicted target sample of the current block from among the peripheral reference samples. In this case, it can be called linear interpolation intra-prediction (LIP).

[0105] Alternatively, chroma prediction samples may be generated based on lumen samples using a linear model. In this case, it can be called the LM (Linear Model) mode.

[0106] Furthermore, temporary predicted samples for the current block can be derived based on filtered peripheral reference samples, and the predicted samples for the current block can be derived by performing a weighted sum on the temporary predicted samples and at least one reference sample derived by the intra-prediction mode from the existing peripheral reference samples, i.e., unfiltered peripheral reference samples. In this case, it can be called PDPC (Position dependent intra-prediction).

[0107] Furthermore, among the multiple reference sample lines surrounding the current block, the reference sample line with the highest prediction accuracy can be selected, and the predicted sample can be derived using the reference sample located in the prediction direction along that line. In this case, information about the reference sample line used (e.g., intra_luma_ref_idx) may be encoded into a bitstream and signaled. This can be called MRL (multi-reference line intra prediction) or MRL-based intra prediction. If MRL is not applied, the reference sample can be derived from a reference sample line directly adjacent to the current block, in which case information about the reference sample line does not need to be signaled.

[0108] Furthermore, the current block can be divided into vertical or horizontal subpartitions, and intra-prediction can be performed for each subpartition based on the same intra-prediction mode. In this case, the peripheral reference samples for intra-prediction may be derived for each subpartition. That is, due to the encoding / decoding order, previously recovered samples from a subpartition may be used as peripheral reference samples for the current subpartition. In this case, the intra-prediction mode for the current block is applied identically to the subpartitions, but by deriving and using peripheral reference samples for each subpartition, the intra-prediction performance can be improved in some cases. Such a prediction method can be called ISP (intra sub-partitions) or ISP-based intra-prediction.

[0109] The intra-prediction methods described above can be distinguished from directional or non-directional intra-prediction modes and referred to by various terms such as intra-prediction type or additional intra-prediction mode. For example, the intra-prediction method (intra-prediction type or additional intra-prediction mode, etc.) may include at least one of the above-mentioned LIP, LM, PDPC, MRL, and ISP. General intra-prediction methods other than the specific intra-prediction types such as LIP, LM, PDPC, MRL, and ISP can be called normal intra-prediction types. Normal intra-prediction types may be generally applied when the above-mentioned specific intra-prediction types are not applicable, and predictions may be made based on the intra-prediction modes described above. On the other hand, post-processing filtering may be performed on the derived prediction samples as needed.

[0110] Specifically, the intra-prediction procedure may include an intra-prediction mode / type determination stage, a peripheral reference sample derivation stage, and an intra-prediction mode / type-based prediction sample derivation stage. Additionally, a post-filtering stage may be performed on the derived prediction samples as needed.

[0111] On the other hand, in addition to the intra-prediction types described above, ALWIP (affine linear weighted intra prediction) may be used. ALWIP can also be called LWIP (linear weighted intra prediction) or MIP (matrix weighted intra prediction or matrix-based intra prediction). When MIP is applied to a current block, prediction samples for the current block can be derived by i) using surrounding reference samples that have undergone an averaging procedure, ii) performing a matrix-vector-multiplication procedure, and iii) further performing horizontal / vertical interpolation procedures as needed. The intra-prediction mode used for MIP may be configured differently from the intra-prediction modes used in LIP, PDPC, MRL, ISP intra-prediction, and normal intra-prediction. The intra-prediction mode for MIP can be called the MIP intra-prediction mode, MIP prediction mode, or MIP mode. For example, the intra-prediction mode for MIP may be configured to use different metrics and offsets in the metrics-vector-multiplication. Here, the metrics can be called (MIP) weighted metrics, and the offset can be called (MIP) offset vectors or (MIP) bias vectors. The specific MIP method will be described later.

[0112] The intra-prediction-based block reconstruction procedure and the intra-prediction unit within the encoding device will be described later using Figures 4 and 5.

[0113] Figure 4 is a flowchart showing an intra-predictive-based video / image encoding method.

[0114] The encoding method in Figure 4 may be performed by the video encoding device in Figure 2. Specifically, step S410 may be performed by the intra-prediction unit 185, and step S420 may be performed by the residual processing unit. Specifically, step S420 may be performed by the subtraction unit 115. Step S430 may be performed by the entropy encoding unit 190. The prediction information in step S430 may be derived by the intra-prediction unit 185, and the residual information in step S430 may be derived by the residual processing unit. The residual information is information about the residual sample. The residual information may include information about the quantized conversion coefficients for the residual sample. As described above, the residual sample may be derived as a conversion coefficient by the conversion unit 120 of the video encoding device, and the conversion coefficient may be derived as a quantized conversion coefficient by the quantization unit 130. Information about the quantized conversion coefficients may be encoded in the entropy encoding unit 190 by the residual coding procedure.

[0115] The video encoding device can perform intra-prediction for the current block (S410). The video encoding device can determine the intra-prediction mode / type for the current block, derive peripheral reference samples for the current block, and then generate predicted samples within the current block based on the intra-prediction mode / type and the peripheral reference samples. Here, the steps of determining the intra-prediction mode / type, deriving peripheral reference samples, and generating predicted samples may be performed simultaneously, or one of the steps may be performed before the others.

[0116] Figure 5 is a diagram illustrating the configuration of the intra prediction unit 185 according to this disclosure.

[0117] As shown in Figure 5, the intra-prediction unit 185 of the video encoding device may include an intra-prediction mode / type determination unit 186, a reference sample derivation unit 187, and / or a prediction sample derivation unit 188. The intra-prediction mode / type determination unit 186 can determine the intra-prediction mode / type for the current block. The reference sample derivation unit 187 can derive the surrounding reference samples of the current block. The prediction sample derivation unit 188 can derive the prediction samples of the current block. On the other hand, although not shown, if a prediction sample filtering procedure described later is performed, the intra-prediction unit 185 may further include a prediction sample filter unit (not shown).

[0118] The video encoding device can determine which of a plurality of intra-prediction modes / types is to apply to the current block. The video encoding device can compare the rate distortion costs (RD costs) of the intra-prediction modes / types to determine the optimal intra-prediction mode / type for the current block.

[0119] On the other hand, the video encoding device can also perform a predictive sample filtering procedure. This predictive sample filtering may be called post-filtering. Some or all of the predictive samples may be filtered by the predictive sample filtering procedure. In some cases, the predictive sample filtering procedure may be omitted.

[0120] Referring again to Figure 4, the video encoding device can generate a residual sample for the current block based on the predicted sample or the filtered predicted sample (S420). The video encoding device can derive the residual sample by subtracting the predicted sample from the original sample of the current block. That is, the video encoding device can derive the residual sample value by subtracting the corresponding predicted sample value from the original sample value.

[0121] The video encoding device can encode video information including information relating to the intra prediction (prediction information) and residual information relating to the residual sample (S430). The prediction information may include the intra prediction mode information and / or the intra prediction method information. The video encoding device can output the encoded video information in the form of a bitstream. The output bitstream may be transmitted by a video decoding device via a storage medium or a network.

[0122] The residual information may include the residual coding syntax described later. The video encoding device can convert / quantize the residual samples and derive quantized conversion coefficients. The residual information may include information regarding the quantized conversion coefficients.

[0123] On the other hand, as mentioned above, the video encoding device can generate a restored picture (including restored samples and restored blocks). To do this, the video encoding device can decrypt the quantized conversion coefficients again to derive (corrected) residual samples. The reason for decrypting the residual samples again after converting / quantizing them is to derive the same residual samples as those derived by the video decoding device. Based on the predicted samples and the (corrected) residual samples, the video encoding device can generate a restored block containing restored samples for the current block. Based on the restored block, a restored picture for the current picture may be generated. As mentioned above, further procedures such as in-loop filtering may be applied to the restored picture.

[0124] Figure 6 is a flowchart showing an intra-predictive-based video / image decoding method.

[0125] The video decoding device can perform operations corresponding to those performed by the video encoding device.

[0126] The decoding method in Figure 6 may be performed by the video decoding device in Figure 3. Steps S610 to S630 may be performed by the intra-prediction unit 265, and the prediction information in step S610 and the residual information in step S640 may be obtained from the bitstream by the entropy decoding unit 210. The residual processing unit of the video decoding device can derive a residual sample for the current block based on the residual information (S640). Specifically, the inverse quantization unit 220 of the residual processing unit can derive conversion coefficients by performing inverse quantization based on the quantized conversion coefficients derived from the residual information, and the inverse transformation unit 230 of the residual processing unit can derive a residual sample for the current block by performing an inverse transformation on the conversion coefficients. Step S650 may be performed by the addition unit 235 or the reconstruction unit.

[0127] Specifically, the video decoding device can derive an intra-prediction mode / type for the current block based on the received prediction information (intra-prediction mode / type information) (S610). The video decoding device can also derive a peripheral reference sample for the current block (S620). Based on the intra-prediction mode / type and the peripheral reference sample, the video decoding device can generate prediction samples within the current block (S630). In this case, the video decoding device can perform a prediction sample filtering procedure. Prediction sample filtering may be called post-filtering. Some or all of the prediction samples may be filtered by the prediction sample filtering procedure. Depending on the circumstances, the prediction sample filtering procedure may be omitted.

[0128] The video decoding device can generate a residual sample for the current block based on the received residual information (S640). The video decoding device can generate a restored sample for the current block based on the predicted sample and the residual sample, and derive a restored block containing the restored sample (S650). A restored picture may be generated for the current picture based on the restored block. As previously mentioned, in-loop filtering procedures and the like may be further applied to the restored picture.

[0129] Figure 7 is a diagram illustrating the configuration of the intra prediction unit 265 according to this disclosure.

[0130] As shown in Figure 7, the intra-prediction unit 265 of the video decoding device may include an intra-prediction mode / type determination unit 266, a reference sample derivation unit 267, and a prediction sample derivation unit 268. The intra-prediction mode / type determination unit 266 determines the intra-prediction mode / type for the current block based on the intra-prediction mode / type information generated and signaled by the intra-prediction mode / type determination unit 186 of the video encoding device, and the reference sample derivation unit 266 can derive peripheral reference samples of the current block from the restored reference region in the current picture. The prediction sample derivation unit 268 can derive prediction samples of the current block. On the other hand, although not shown, if the prediction sample filtering procedure described above is performed, the intra-prediction unit 265 may further include a prediction sample filter (not shown).

[0131] The intra prediction mode information may include, for example, flag information (e.g., intra_luma_mpm_flag) indicating whether the MPM (most probable mode) or the remaining mode is applied to the current block. If the MPM is applied to the current block, the intra prediction mode information may further include index information (e.g., intra_luma_mpm_idx) indicating one of the intra prediction mode candidates (MPM candidates). The intra prediction mode candidates (MPM candidates) may consist of an MPM candidate list or an MPM list. If the MPM is not applied to the current block, the intra prediction mode information may further include remaining mode information (e.g., intra_luma_mpm_remainder) indicating one of the remaining intra prediction modes excluding the intra prediction mode candidates (MPM candidates). The video decoding device can determine the intra prediction mode of the current block based on the intra prediction mode information.

[0132] Furthermore, the intra-prediction method information may be embodied in various forms. For example, the intra-prediction method information may include intra-prediction method index information that indicates one of the intra-prediction methods. As another example, the intra-prediction method information may include reference sample line information (e.g., intra_luma_ref_idx) indicating whether the MRL is applied to the current block and, if so, which reference sample line is used; ISP flag information (e.g., intra_subpartitions_mode_flag) indicating whether the ISP is applied to the current block; ISP type information (e.g., intra_subpartitions_split_flag) indicating the subpartition splitting type if the ISP is applied; and at least one of the following flag information: flag information indicating whether PDPC is applied or flag information indicating whether LIP is applied. The intra-prediction type information may also include an MIP flag indicating whether MIP is applied to the current block. In this disclosure, the ISP flag information may be referred to as an ISP application indicator.

[0133] The intra-prediction mode information and / or the intra-prediction method information may be encoded / decoded using the coding methods described herein. For example, the intra-prediction mode information and / or the intra-prediction method information may be encoded / decoded by entropy coding (e.g., CABAC, CAVLC) based on truncated (rice) binary code.

[0134] On the other hand, the intra-prediction mode may further include a CCLM (cross-component linear model) mode for chroma samples, in addition to the PLANAR mode, DC mode, and directional intra-prediction mode. The CCLM mode may be divided into L_CCLM, T_CCLM, and LT_CCLM depending on whether the left sample, the upper sample, or both are considered for the derivation of the CCLM parameters, and may be applied only to chroma components.

[0135] The intra-prediction mode may be indexed as shown in Table 1 below, for example.

[0136] [Table 1]

[0137] On the other hand, the intra-prediction type (or additional intra-prediction mode, etc.) may include at least one of the above-mentioned LIP, PDPC, MRL, ISP, and MIP. The intra-prediction type may be indicated based on intra-prediction type information, which may be embodied in various forms. For example, the intra-prediction type information may include intra-prediction type index information indicating one of the intra-prediction types. As another example, the intra-prediction type information may include at least one of the following: reference sample line information (e.g., intra_luma_ref_idx) indicating whether the MRL is applied to the current block and, if so, which reference sample line is used; ISP flag information (e.g., intra_subpartitions_mode_flag) indicating whether the ISP is applied to the current block; ISP type information (e.g., intra_subpartitions_split_flag) indicating the split type of the subpartition when the ISP is applied; flag information indicating whether PDCP is applied or not; or flag information indicating whether LIP is applied or not. Furthermore, the intra prediction type information may include an MIP flag (or may be referred to as intra_mip_flag) indicating whether or not MIP is applied to the current block.

[0138] TIMD (Template-based intramode derivation) Overview

[0139] Figure 8 shows the template region used in the TIMD mode according to this disclosure. For the IPM (Intra Prediction Mode) intra-modes of the surrounding adjacent intra-blocks and inter-blocks, as shown in Figure 8, the SATD (sum of absolute transformed differences) between the predicted block predicted from the template region and the actual reconstructed sample can be calculated, and the mode with the smallest SATD can be selected as the intra-mode for the current block.

[0140] In other words, the first two intra-prediction modes with the minimum SATD are selected as TIMD modes. These two TIMD modes are fused with weighted values, and such weighted intra-predictions are now used to encode CU. PDPC (position dependent intra-prediction combination) may be included in the induction process of TIMD modes.

[0141] The costs of the two selected modes are compared to a threshold, and the two cost factors are applied in the test as follows:

[0142] JPEG2026511975000003.jpg753

[0143] If the above condition is true, fusion is applied; otherwise, only mode1 is used.

[0144] The weighted values ​​of the modes are calculated by their SATD costs as follows:

[0145] JPEG2026511975000004.jpg788

[0146] JPEG2026511975000005.jpg744

[0147] Template matching (TM)

[0148] Figure 9 is a diagram illustrating the template matching-based encoding / decoding method relating to this disclosure.

[0149] Template Matching (TM) is a method of inducing motion vectors at the decoder end that can refine the motion information of the current block by finding the template in the reference picture that is most similar to the template adjacent to the current block (for example, the current coding unit (CU)) (hereinafter referred to as the "current template"). The current template may be the block above and / or to the left of the current block, or a part of these adjacent blocks. The reference template may be determined to be the same size as the current template.

[0150] As shown in Figure 9, once the initial motion vector of the current block is induced, a search for a better motion vector may be performed in the region surrounding the initial motion vector. For example, the range of the region in which the search is performed may be within the [-8, +8]-pel search region centered on the initial motion vector. The size of the search step may be determined based on the AMVR mode of the current block. Furthermore, template matching may be performed sequentially with the bilateral matching process in merge mode.

[0151] If the current block prediction mode is AMVP mode, motion vector predictor candidates (MVP candidates) may be determined based on the template matching error. For example, a motion vector predictor candidate (MVP candidate) that minimizes the error between the current template and the reference template may be selected. Subsequently, template matching to improve the motion vector may be performed on the selected motion vector predictor candidate. In this case, template matching to improve the motion vector does not need to be performed on motion vector predictor candidates that have not been selected.

[0152] More specifically, the improvement of the selected motion vector predictor candidate may begin with full-pel (integer-pel) accuracy within the [-8,+8]-pel search region using iterative diamond search. Alternatively, in the case of 4-pel AMVR mode, it may begin with 4-pel accuracy. Subsequently, the AMVR mode may continue with half-pel and / or quarter-pel accuracy searches. According to this search process, the motion vector predictor candidate can maintain the same motion vector accuracy indicated by the AMVR mode even after the template matching process. In the iterative search process, if the difference between the previous minimum cost and the current minimum cost is less than an arbitrary threshold, the search process terminates. The threshold may be the same as the block region, i.e., the number of samples in the block. Table 2 shows examples of search patterns with AMVR mode and merge mode with AMVR.

[0153] [Table 2]

[0154] If the current block prediction mode is merge mode, a similar search method may be applied to the merge candidates indicated by the merge index. As shown in Table 2 above, template matching may be performed up to 1 / 8-Pell accuracy, or it may be skipped below Huff-Pell accuracy, which may be determined depending on whether or not an alternative interpolation filter is used by the merge motion information. In this case, the alternative interpolation filter may be the filter used when AMVR is in Huff-Pell mode. Also, if template matching is available, depending on whether or not bilateral matching (BM) is available, template matching may operate as an independent process, or it may operate as a process of further motion vector improvement between block-based bilateral matching and sub-block-based bilateral matching. Whether or not template matching and / or bilateral matching is available may be determined by an availability condition check. Above, the accuracy of the motion vector can mean the accuracy of the motion vector difference (MVD).

[0155] The following describes in detail a video encoding / decoding method according to one embodiment of this disclosure.

[0156] This disclosure may relate to intra-prediction. Specifically, this disclosure may relate to a method for adaptively selecting and / or applying an intra-prediction method by utilizing the encoded information of surrounding blocks when performing intra-prediction based on directional and / or non-directional modes in intra-prediction mode. That is, this disclosure may relate to a method for selecting and / or applying an intra-prediction method by utilizing the intra-prediction information of surrounding blocks (e.g., candidate intra-prediction information) when performing intra-prediction.

[0157] Figure 10 shows the positions of peripheral blocks for constructing an intra-prediction candidate list according to one embodiment of the present disclosure. In the case of existing intra-prediction, the intra-prediction candidate list (i.e., MPM list) of current block 1010 may be constructed by utilizing the intra-prediction information of peripheral blocks 1020, 1030, 1040, 1050, and 1060. In the case of ECM (Enhanced Compression Model), the intra-prediction candidate list of current block 1010 may be constructed by searching for and / or selecting the intra-prediction modes of the peripheral blocks in the order of left peripheral block 1020, upper peripheral block 1030, lower left peripheral block 1040, upper right peripheral block 1050, and upper left peripheral block 1060.

[0158] At this time, the intra-prediction candidate list for block 1010 may consist of directional intra-modes and / or non-directional intra-modes (e.g., Planar mode, DC mode). However, Versatile Video Coding (VVC) may have various intra-prediction modes for predicting the current block. For example, in addition to traditional intra-modes (directional mode, non-directional mode), the intra-prediction modes may include MRL (Multi Reference Line) prediction mode, ISP (Intra sub-partition) prediction mode, MIP (Matrix-based Intra Prediction) prediction mode, CCLM (Cross-Component Linear Model) prediction mode, and IBC (Intra Block Copy) prediction mode.

[0159] Additionally, in the case of ECM, the intra-prediction mode may include various intra-prediction modes such as extended planar mode, gradient PDPC (position dependent intra-prediction), TMRL (template-based MRL), 6-tap interpolation filter, DIMD (decoder side intra-mode derivation), TIMD (template-based intra-mode derivation), CIIP (combined inter and intra-prediction) PDPC blending, SGPM (spatial geometric partitioning mode), intra-prediction fusion, intra-TMP (intra-template matching), IBC, LM (linear mode) parameter signaling, MMLM (multi-model linear mode), chroma intra-fusion, CCCM (convolutional cross-component model), GLM (gradient linear model), and GL-CCCM (gradient and location based convolutional cross-component model). The various intra-prediction modes described above can be referred to as general intra-prediction information.

[0160] Existing intra-prediction candidate lists may consist only of traditional intra-modes (directional mode, non-directional mode). Therefore, various intra-prediction modes such as SGPM and intra-template matching mentioned above do not need to be considered when constructing the intra-prediction candidate list. In this case, there is a disadvantage in that not all intra-prediction information of surrounding blocks can be utilized.

[0161] This disclosure proposes a merged mode-based intra-prediction method that utilizes various intra-prediction information from surrounding blocks (i.e., general intra-prediction information) when predicting the intra-prediction of a current block. Specifically, this disclosure proposes a method for efficiently utilizing all general intra-prediction information, such as SGPM, GLM, CCCM, DIMD, and TIMD, in addition to the traditional prediction modes of surrounding blocks.

[0162] Example 1

[0163] This disclosure proposes a merging mode that utilizes general intra-prediction information of surrounding blocks when predicting the intra-prediction of a rumor block. In other words, this disclosure proposes a merging mode that utilizes various intra-prediction information of surrounding blocks when predicting the intra-prediction of a rumor block.

[0164] Currently, intra-prediction of a block only considers traditional intra-prediction information from surrounding blocks. However, since VVC and ECM use various additional methods during intra-prediction, intra-prediction that only considers traditional intra-prediction information is inefficient.

[0165] In embodiments relating to this disclosure, a list of candidate intra-predictions to be applied to the currently encoded block and / or currently decoded block can be constructed by utilizing general intra-prediction information of surrounding blocks. This allows the disclosure to select one candidate intra-prediction from among the candidate intra-prediction information included in the intra-prediction candidate list and apply it to the current block. In other words, the disclosure can perform intra-prediction by selecting one candidate intra-prediction from among the candidate intra-prediction information included in the intra-prediction candidate list.

[0166] To construct an intra-prediction candidate list, the disclosure can collect general intra-prediction information after searching the surrounding blocks of the current block to be encoded and / or decoded. The general intra-prediction information of the surrounding blocks may include the following prediction information:

[0167] - On-screen prediction direction mode information

[0168] - Extended planar information

[0169] - MRL information

[0170] - TMRL Information

[0171] - ISP information

[0172] - MIP information

[0173] - Interpolation filter information

[0174] - DIMD information

[0175] - TIMD information

[0176] - SGPM Information

[0177] - Intra prediction fusion information

[0178] - IntraTMP information

[0179] - IBC information

[0180] - Peripheral reference sample characteristic information

[0181] Here, specific mode information may include information indicating whether or not a specific mode is applied. For example, MRL information may include information indicating whether or not MRL is applied. As yet another example, TIMD information may include information indicating whether or not TIMD is applied. That is, general intra-prediction information may include intra-prediction coding status information of peripheral blocks that have been coded and / or decoded. More specifically, the "information" mentioned above may include various types of information such as mode information, mode index, reference sample index, reference sample characteristics, template matching information, mode merging, and weighting values.

[0182] For example, if the SGPM mode is applied to the left peripheral block 1020 in Figure 10, the SGPM application status may be true. In addition, the applied SGPM information (e.g., SGPM direction, intra-prediction mode applied to the two blocks, etc.) may also be collected. As another example, if the 33rd directional mode and TMRL are both applied to the upper right peripheral block 1050 in Figure 10, the applied intra-prediction mode, the reference sample line information selected as TMRL, etc., may be further collected.

[0183] As another example, if an intra-TMP is applied to the upper peripheral block 1030 in Figure 10, information such as whether or not an intra-TMP is applied and additional information about the applied intra-TMP may be collected. The intra-predictive information collection method for peripheral blocks proposed in this disclosure is not limited to the above examples, and if new intra-predictive information not included in the above examples is proposed, that intra-predictive information may also be collected by the same method.

[0184] The disclosure allows selecting surrounding blocks 1020, 1030, 1040, 1050, and 1060 in Figure 10 to explore surrounding blocks. This enables the disclosure to explore these surrounding blocks 1020, 1030, 1040, 1050, and 1060. In other words, intra-predictive information for surrounding blocks 1020, 1030, 1040, 1050, and 1060 may be collected. In this case, the disclosure can explore the surrounding blocks in the following search order.

[0185] - Left surrounding block 1020 -> Upper surrounding block 1030 -> Lower left surrounding block 1040 -> Upper right surrounding block 1050 -> Upper left surrounding block 1060

[0186] - Left surrounding block 1020 -> Upper surrounding block 1030 -> Upper right surrounding block 1050 -> Lower left surrounding block 1040 -> Upper left surrounding block 1060

[0187] - Upper surrounding block 1030 -> Left surrounding block 1020 -> Upper right surrounding block 1050 -> Lower left surrounding block 1040 -> Upper left surrounding block 1060

[0188] The peripheral block search order relating to this disclosure is not limited to the order described above, and this disclosure can search for peripheral blocks in various orders.

[0189] Figure 11 shows the location of the surrounding block search according to one embodiment of the present disclosure. In addition to searching for the surrounding block 1120 adjacent to the current block 1110, the present disclosure can also search for non-adjacent surrounding blocks 1130 and collect intra-prediction information. Referring to Figure 11, the present disclosure can collect intra-prediction information for the surrounding block 1120 adjacent to the current block, and then collect intra-prediction information for the surrounding block 1130 that is not adjacent to the current block. Furthermore, according to one embodiment of the present disclosure, the numbers of the surrounding blocks shown in Figure 11 can indicate the order in which the surrounding blocks are searched. However, the present disclosure is not limited to this, and surrounding blocks can be searched in various orders.

[0190] According to one embodiment of this disclosure, after comparing the reference sample characteristics of the current block with those of the surrounding blocks, intra-prediction information for the block may be collected only if certain conditions are met. In this case, the comparison between reference samples may be based on one of the following: template matching, bidirectional matching, or SATD (sum of absolute transformed differences). That is, the surrounding blocks that constitute the intra-prediction candidate list may be determined based on a comparison between the reference sample of the current block and the reference sample of the surrounding blocks.

[0191] Furthermore, according to one embodiment of the present disclosure, the intra-prediction index indicating candidate intra-prediction information in the intra-prediction candidate list may be determined based on one of template matching, bidirectional matching, or SATD.

[0192] The search locations and / or search order of adjacent and / or non-adjacent peripheral blocks proposed in this disclosure are not limited to the examples given above, and may have a wider variety of search locations, number of search locations, and / or search order.

[0193] When collecting intraprediction information from adjacent and / or non-adjacent surrounding blocks according to this disclosure, the intraprediction information to be applied to the current block may be collected from the surrounding blocks in a first-come, first-served order of N pieces. That is, after searching for surrounding blocks based on a predetermined order, N pieces of intraprediction information may be collected from the surrounding blocks. Once all N pieces of intraprediction information have been collected, the search for surrounding blocks may be terminated. In this case, N may be any natural number such as 3 or 6.

[0194] When collecting N intra-prediction information on a first-come, first-served basis through this disclosure, surrounding blocks that have the same intra-prediction information may be excluded from the intra-prediction candidate list by performing a pruning check in the following manner.

[0195] - Method 1. Perform a pruning check by checking whether intra-prediction mode is applied and all additional information used to apply intra-prediction mode.

[0196] - Method 2. Perform pruning checks by checking only whether intra-predictive mode is applied.

[0197] - Method 3. Do not perform pruning checks.

[0198] In other words, after searching for surrounding blocks in a predetermined order, intra-prediction information for surrounding blocks that have the same intra-prediction information may be excluded from the intra-prediction candidate list. For example, when performing a pruning check by checking only whether or not an intra-prediction mode is applied, as in Method 2, even if the additional information used to apply the intra-prediction mode (hereinafter referred to as "intra-prediction additional information") is different from each other, the intra-prediction information can be excluded from the intra-prediction candidate list by the pruning check. In other words, if the intra-prediction candidate list includes first intra-prediction information and second intra-prediction information, and the intra-prediction modes included in the first intra-prediction information and second intra-prediction information are the same, then even if the intra-prediction additional information included in the first intra-prediction information and second intra-prediction information is different from each other, the intra-prediction information added later (or the intra-prediction information added earlier) may be excluded from the intra-prediction candidate list.

[0199] Alternatively, the decoding complexity in the video decoding device 200 can be reduced by not performing a pruning check as in Method 3. Alternatively, the encoding complexity in the video encoding device 100 can be reduced by not performing a pruning check as in Method 3.

[0200] If, after searching adjacent and / or non-adjacent surrounding blocks, the intra-prediction candidate list is not filled with the N intra-prediction information items pre-configured, the intra-prediction candidate list may be filled with pre-configured default modes. In this case, the default modes may be set according to the predetermined number of intra-prediction information items in the intra-prediction candidate list. That is, if N intra-prediction information items are to be filled in the intra-prediction candidate list, N default modes may be set. The disclosure is not limited thereto, and M default modes may be set regardless of the number of intra-prediction information items in the intra-prediction candidate list.

[0201] According to one embodiment of this disclosure, after N candidate intra-prediction information is generated, the order of the candidate intra-prediction information may be reordered by template matching, bidirectional matching, or the like. For example, after all N candidate intra-prediction information is filled into the intra-prediction candidate list, template matching may be performed using peripheral reference samples similar to the TMRL or TIMD method, and then the candidate intra-prediction information may be reordered in order of template cost. In this case, the reordering of the candidate intra-prediction information in the intra-prediction candidate list may be performed in order of lowest template cost.

[0202] This disclosure allows for intra-prediction by selecting one of the N candidate intra-prediction information generated by the method described above and applying the selected candidate intra-prediction information to the current block. In this case, intra-prediction may be performed by the following method.

[0203] - Method 4. Apply only the intra-prediction modes included in the selected candidate intra-prediction information to the current block. The additional intra-prediction information is transmitted to the video decoding device 200.

[0204] - Method 5. Apply all intra-prediction modes and additional intra-prediction information included in the selected candidate intra-prediction information to the current block identically.

[0205] - Method 6. Modify and apply the intra-prediction mode and additional intra-prediction information included in the selected candidate intra-prediction information to suit the current block.

[0206] Taking Method 4 as an example, if the selected candidate intra-prediction information includes directional mode 50 as the intra-prediction mode and MRL index 7 as additional intra-prediction information, then directional mode 50 may be applied to the current block. In this case, a more suitable MRL index for the current block may be transmitted to the video decoder 200. That is, the video encoder 100 may apply only the intra-prediction mode from the candidate intra-prediction information to the current block, and the additional intra-prediction information may not be applied to the current block.

[0207] Taking Method 5 as an example, if the selected candidate intra-prediction information includes DIMD mode as an intra-prediction mode, and additional intra-prediction information includes information that Planar, mode 18, mode 50, mode 33, and mode 66 are combined, then intra-prediction for the current block may be performed by combining predictors generated in Planar, mode 18, mode 50, mode 33, and mode 66 and performing DIMD.

[0208] Taking Method 6 as an example, if the selected candidate intra-prediction information includes the SGPM mode as the intra-prediction mode, and the block division direction and intra-prediction information for the two divided blocks are included as additional intra-prediction information, then an adaptive intra-prediction for the current block may be performed by considering the position of the candidate block (surrounding block) indicating the selected candidate intra-prediction information and the position of the current block. In other words, an intra-prediction may be performed by adaptively applying the block division direction and the intra-prediction mode for the two divided blocks to the current block.

[0209] According to one embodiment of the present disclosure, the number of candidate intra-prediction information items constituting the intra-prediction candidate list, the surrounding block search position, the surrounding block search order, and the candidate intra-prediction information collected may be determined in various ways by the width of the input block, the height of the input block, the number of pixels in the input block, the position of subblocks within the input block, explicitly signaled syntactic elements, the statistical characteristics of surrounding pixels, and whether or not a quadratic transformation is used. Here, the input block may be the current block.

[0210] According to one embodiment of the present disclosure, an intra-prediction candidate index indicating one candidate intra-prediction information included in the intra-prediction candidate list may be determined based on at least one of the following: prediction mode (e.g., inter-prediction mode, intra-prediction mode), input block width, input block height, number of pixels in the input block, position of subblocks within the input block, explicitly signaled syntactic elements, statistical characteristics of surrounding pixels, and whether or not a quadratic transformation is used.

[0211] According to this disclosure, candidate intra-prediction information may be binary-coded using an appropriate binary-coded method and then transmitted to the video decoder 200. For example, the intra-prediction candidate index may be set to MPM mode, as in intraluma mode transmission, and the remaining intra-prediction information may be binary-coded separately. That is, the intra-prediction information of the current block may be set to MPM mode and binary-coded, and the remaining intra-prediction information may be binary-coded separately. This disclosure can save binary-coded bits by performing appropriate context modeling when binary-coding each intra-prediction piece of information. Alternatively, this disclosure can transmit candidate intra-prediction information to the video decoder 200 by using a binary-coded method such as truncated binary, truncated unary, or fixed length, taking into account the number of candidate intra-prediction pieces of information included in the intra-prediction candidate list.

[0212] Information indicating whether the method proposed in this disclosure (i.e., the merge mode) is applied (hereinafter referred to as "information on whether the merge mode is applied") may be signaled using HLS (High-level syntax). That is, information on whether the Bonn merge mode is applied may be signaled by VPS (video parameter set), SPS (sequence parameter set), PPS (picture parameter set), picture header, slice header, DCI, etc. For example, in order to determine whether the merge mode is applied on a PPS basis, information on whether the merge mode is applied may be signaled by the PPS.

[0213] Furthermore, the video decoding device 200 can adaptively determine whether or not the merged mode is applied without signaling information about whether or not the merged mode is applied. Alternatively, the video decoding device 200 can determine whether or not the merged mode is applied by parsing the information about whether or not the merged mode is applied. For example, the video encoding device 100 can transmit the merged mode application information on a CTU or CU basis. In this case, the information about whether or not the merged mode is applied may be transmitted to the video decoding device 200 using a 1-bit flag.

[0214] When the application of merge mode is determined by factors such as the size of a specific block, the shape of a specific block, or whether specific conditions are met, information regarding the application of merge mode may be signaled only when those conditions are met. In this case, the information regarding the application of merge mode may be transmitted to the video decoding device 200 using a 1-bit flag. Here, the specific block may be the current block or a surrounding block, and this disclosure is not limited thereto. For example, if the height of a specific block is four times or more the width of the specific block, merge mode may not be applied. In this case, signaling of information regarding the application of merge mode may be omitted. Furthermore, the application of merge mode may be implicitly inferred when specific conditions are met.

[0215] The coding unit may adaptively determine whether or not to signal information regarding the application of merged mode based on the information signaled by the HLS regarding the application of merged mode. For example, if the information signaled by the SPS regarding the application of merged mode is false (i.e., merged mode is not applied at the SPS level), then the coding unit does not need to apply merged mode, and therefore, information regarding the application of merged mode does not need to be signaled.

[0216] Figure 12 is a flowchart illustrating the method for applying the merged mode according to this disclosure. Referring to Figure 12, the video encoding device 100 and / or the video decoding device 200 can search for adjacent peripheral blocks and / or non-adjacent peripheral blocks (S1210). Here, adjacent peripheral blocks and non-adjacent peripheral blocks may be the blocks shown in Figure 11. The video encoding device 100 and / or the video decoding device 200 can collect intra-prediction information for adjacent peripheral blocks and / or non-adjacent peripheral blocks (S1230). The video encoding device 100 and / or the video decoding device 200 can construct an intra-prediction candidate list based on the collected intra-prediction information (S1250). The video encoding device 100 and / or the video decoding device 200 can select intra-prediction information from the intra-prediction candidate list (S1270). The video encoding device 100 and / or the video decoding device 200 can perform current block prediction based on the selected intra-prediction information (S1290). In other words, the video encoding device 100 and / or video decoding device 200 can generate a predicted block for the current block by applying selected intra-prediction information to the current block.

[0217] Example 2

[0218] This disclosure proposes a merging mode that utilizes general intra-prediction information of surrounding blocks and co-located rumor blocks in the current block during intra-prediction of a chroma block. In other words, this disclosure proposes a merging mode that utilizes various intra-prediction information of chroma surrounding blocks and corresponding rumor blocks during intra-prediction of a chroma block.

[0219] Currently, when intra-predicting a chroma block, not all intra-prediction information of surrounding blocks is considered; only traditional intra-prediction information is taken into account. Therefore, existing methods are likely inefficient in terms of selecting the intra-prediction mode for chroma blocks and compressing encoded information.

[0220] This disclosure proposes a method for performing intra-prediction using intra-prediction information of the chroma surrounding blocks and corresponding lumens blocks of the current chroma block. That is, an intra-prediction candidate list may be constructed based on the intra-prediction information of the surrounding blocks of the current chroma block and the intra-prediction information of the corresponding lumens blocks. The video encoding device 100 and / or video decoding device 200 can select one of the candidate intra-prediction information included in the constructed intra-prediction candidate list and apply it to the current block.

[0221] To construct an intra-prediction candidate list, the disclosure can collect intra-prediction information after searching for the surrounding blocks and corresponding rumor blocks of the current chroma block to be encoded and / or decoded. The intra-prediction information of the surrounding blocks of the current chroma block may include the following prediction information:

[0222] - On-screen prediction direction mode information

[0223] - Extended planar information

[0224] - Interpolation filter information

[0225] - DIMD information

[0226] - TIMD information

[0227] - Intrachroma prediction fusion information

[0228] - CCLM Information

[0229] - MMLM Information

[0230] - LM parameter signaling information

[0231] - CCCM information

[0232] - GLM Information

[0233] - GL-CCCM information

[0234] - Reference sample characteristics information

[0235] Here, the specific mode information may include information indicating whether or not a specific mode is applied. For example, CCLM information may include information indicating whether or not CCLM is applied. As yet another example, TIMD information may include information indicating whether or not TIMD is applied. That is, intra-prediction information may include intra-prediction coding status information for peripheral blocks and corresponding rumor blocks whose coding and / or decoding has been completed. More specifically, the "information" mentioned above may include various types of information such as mode information, mode index, reference sample index, reference sample characteristics, template matching information, mode merging, weighting values, model parameters, and filter information.

[0236] The method for collecting intra-predictive information for surrounding blocks and corresponding rumor blocks of the current chroma block as described herein is not limited to the method described above. If a new intra-predictive mode is proposed, the intra-predictive information may also be collected in that intra-predictive mode using the same method.

[0237] This disclosure allows selecting the surrounding blocks 1020, 1030, 1040, 1050, and 1060 in Figure 10 to explore the surrounding blocks of the current chroma block. This allows the disclosure to explore the said surrounding blocks 1020, 1030, 1040, 1050, and 1060. That is, intra-predictive information for the surrounding blocks 1020, 1030, 1040, 1050, and 1060 may be collected. In this case, the disclosure can explore the surrounding blocks in the following search order.

[0238] - Left surrounding block 1020 -> Upper surrounding block 1030 -> Lower left surrounding block 1040 -> Upper right surrounding block 1050 -> Upper left surrounding block 1060

[0239] - Left surrounding block 1020 -> Upper surrounding block 1030 -> Upper right surrounding block 1050 -> Lower left surrounding block 1040 -> Upper left surrounding block 1060

[0240] - Upper surrounding block 1030 -> Left surrounding block 1020 -> Upper right surrounding block 1050 -> Lower left surrounding block 1040 -> Upper left surrounding block 1060

[0241] The peripheral block search order relating to this disclosure is not limited to the order described above, and this disclosure can search for peripheral blocks in various orders.

[0242] Currently, the surrounding block search position for the chroma block can be directly applied as described in Figure 11 above. That is, in addition to searching for the surrounding block 1120 adjacent to the current block 1110, this disclosure can also search for non-adjacent surrounding blocks 1130 to collect intra-predictive information. Referring to Figure 11, this disclosure can collect intra-predictive information for the surrounding block 1120 adjacent to the current chroma block, and then collect intra-predictive information for the surrounding block 1130 that is not adjacent to the current chroma block. Furthermore, according to one embodiment of this disclosure, the numbers of the surrounding blocks shown in Figure 11 can indicate the surrounding block search order. However, this disclosure is not limited to this, and surrounding blocks can be searched in various orders.

[0243] Figure 13 shows the search locations of corresponding rumor blocks according to one embodiment of the present disclosure. The present disclosure can search for a corresponding rumor block 1320 that currently corresponds to chroma block 1310. Specifically, the video encoding device 100 and / or the video decoding device 200 can search for specific locations 1321, 1322, 1323, 1324, and 1325 within the corresponding rumor block and then collect intra-prediction information for those locations. In addition, the video encoding device 100 and / or the video decoding device 200 can search for surrounding blocks 1330, 1335, 1340, 1345, and 1350 of the corresponding rumor block and then collect intra-prediction information for those blocks.

[0244] The search order for specific locations 1321, 1322, 1323, 1324, and 1325 within the corresponding ruma block is 1321, 1322, 1323, 1324, and 1325, but the search order for specific locations within the corresponding ruma block according to this disclosure is not limited to this and may vary. Similarly, the search order for surrounding blocks 1330, 1335, 1340, 1345, and 1350 of the corresponding ruma block may be 1330, 1335, 1340, 1345, and 1350 in the order they are listed, but the search order for surrounding blocks of the corresponding ruma block according to this disclosure is not limited to this and may vary. If the intra-prediction mode included in the intra-prediction information of a searched block is a mode that cannot be applied to a chroma block, the collection of intra-prediction information for that block may be omitted.

[0245] According to one embodiment of the present disclosure, after comparing the reference sample characteristics of the current block with the reference sample characteristics of the surrounding blocks and corresponding rumor blocks, intra-prediction information for the block may be collected only if certain conditions are met. In this case, the comparison between reference samples may be based on one of the following: template matching, bidirectional matching, SATD comparison between reference samples, or correlation comparison between reference samples. That is, the surrounding blocks and / or corresponding rumor blocks that constitute the intra-prediction candidate list may be determined based on a comparison between the reference sample of the current block and the reference sample of the surrounding blocks and / or corresponding rumor blocks.

[0246] Furthermore, according to one embodiment of the present disclosure, the intra-prediction index, which indicates candidate intra-prediction information in the intra-prediction candidate list, may be determined based on one of the following: template matching, bidirectional matching, SATD comparison between reference samples, or correlation comparison between reference samples.

[0247] The search locations and / or search order of adjacent peripheral blocks, non-adjacent peripheral blocks, and / or corresponding rumor blocks proposed in this disclosure are not limited to the examples given above, and may have a wider variety of search locations, number of search locations, and / or search order.

[0248] When collecting intraprediction information in adjacent peripheral blocks, non-adjacent peripheral blocks, and / or corresponding rumor blocks according to this disclosure, the intraprediction information to be applied to the current block may be collected from the peripheral blocks and / or corresponding rumor blocks in a first-come, first-served order of N pieces. That is, after searching for peripheral blocks and / or corresponding rumor blocks based on a predetermined order, N pieces of intraprediction information may be collected from the peripheral blocks and / or corresponding rumor blocks. The search for peripheral blocks and / or corresponding rumor blocks may be terminated when all N pieces of intraprediction information have been collected. In this case, N may be any natural number, such as 3 or 6.

[0249] When collecting N intra-prediction information on a first-come, first-served basis through this disclosure, surrounding blocks and / or corresponding rumor blocks that have the same intra-prediction information may be excluded from the intra-prediction candidate list by performing a pruning check in the following manner.

[0250] - Method 7. Perform a pruning check by checking both whether intra-prediction mode is applied and the additional information used to apply intra-prediction mode.

[0251] - Method 8. Perform pruning checks by checking only whether intra-predictive mode is applied.

[0252] - Method 9. Do not perform pruning checks.

[0253] In other words, after searching for surrounding blocks and / or corresponding rumor blocks in a predetermined order, intra prediction information for surrounding blocks and / or corresponding rumor blocks that have the same intra prediction information may be excluded from the intra prediction candidate list. For example, when performing a pruning check by checking only whether or not an intra prediction mode is applied, as in Method 8, even if the additional information used to apply the intra prediction mode (hereinafter referred to as "intra prediction additional information") is different from each other, the intra prediction information may be excluded from the intra prediction candidate list by the pruning check. In other words, if the intra prediction candidate list includes first intra prediction information and second intra prediction information, and the intra prediction modes included in the first intra prediction information and second intra prediction information are the same, then even if the intra prediction additional information included in the first intra prediction information and second intra prediction information is different from each other, the intra prediction information added later (or the intra prediction information added earlier) may be excluded from the intra prediction candidate list.

[0254] Alternatively, the decoding complexity in the video decoding device 200 may be reduced by not performing a pruning check as in method 9. Alternatively, the encoding complexity in the video encoding device 100 may be reduced by not performing a pruning check as in method 9.

[0255] If, after searching for adjacent surrounding blocks and / or non-adjacent surrounding blocks and / or corresponding rumor blocks, the intra-prediction candidate list is not filled with N intra-prediction information pre-configured, the intra-prediction candidate list may be filled with pre-configured default modes. In this case, the default modes may be set according to the predetermined number of intra-prediction information in the intra-prediction candidate list. That is, if N intra-prediction information is to be filled in the intra-prediction candidate list, N default modes may be set. The disclosure is not limited thereto, and M default modes may be set regardless of the number of intra-prediction information in the intra-prediction candidate list.

[0256] According to one embodiment of the present disclosure, when collecting N candidate intra-prediction information, the video encoding device 100 and / or video decoding device 200 can separate linear models (LM, MMLM, CCCM, GLM, GL-CCCM, CCLM, etc.) and other modes (traditional intra-prediction modes) to generate two intra-prediction candidate lists. Alternatively, the video encoding device 100 and / or video decoding device 200 can select only the traditional intra-prediction modes to generate an intra-prediction candidate list. Alternatively, the video encoding device 100 and / or video decoding device 200 can select only linear models (LM, MMLM, CCCM, GLM, GL-CCCM, CCLM, etc.) to generate an intra-prediction candidate list.

[0257] According to one embodiment of this disclosure, after N candidate intra-prediction information is generated, the order of the candidate intra-prediction information may be reordered by template matching, bidirectional matching, or the like. For example, after all N candidate intra-prediction information is filled into the intra-prediction candidate list, template matching may be performed using peripheral reference samples, similar to the TIMD method, and then the candidate intra-prediction information may be reordered in order of template cost. In this case, the reordering of the candidate intra-prediction information in the intra-prediction candidate list may be performed in order of lowest template cost.

[0258] This disclosure allows for intra-prediction by selecting one of the N candidate intra-prediction information generated by the method described above and applying the selected candidate intra-prediction information to the current block. In this case, intra-prediction may be performed by the following method.

[0259] - Method 10. Apply only the intra-prediction modes included in the selected candidate intra-prediction information to the current block. The additional intra-prediction information is transmitted to the video decoding device 200.

[0260] - Method 11. Apply both the intra-prediction mode and additional intra-prediction information included in the selected candidate intra-prediction information to the current block identically.

[0261] - Method 12. Modify and apply the intra-prediction mode and additional intra-prediction information included in the selected candidate intra-prediction information to suit the current block.

[0262] According to one embodiment of the present disclosure, the number of candidate intra-prediction information items constituting the intra-prediction candidate list, the search positions of surrounding blocks and / or corresponding rumor blocks, the search order of surrounding blocks and / or corresponding rumor blocks, and the candidate intra-prediction information collected may be determined in various ways by the width of the input block, the height of the input block, the number of pixels in the input block, the position of subblocks within the input block, explicitly signaled syntactic elements, the statistical characteristics of surrounding pixels, and whether or not a quadratic transformation is used. Here, the input block may be the current block.

[0263] According to one embodiment of the present disclosure, an intra-prediction candidate index indicating one candidate intra-prediction information included in the intra-prediction candidate list may be determined based on at least one of the following: prediction mode (e.g., inter-prediction mode, intra-prediction mode), input block width, input block height, number of pixels in the input block, position of subblocks within the input block, explicitly signaled syntactic elements, statistical characteristics of surrounding pixels, and whether or not a quadratic transformation is used.

[0264] According to this disclosure, candidate intra-prediction information may be binary-coded using an appropriate binary-coded method and then transmitted by the video decoder 200. For example, the intra-prediction candidate index may be set to MPM mode, similar to intraluma mode transmission, and the remaining intra-prediction information may be binary-coded separately. That is, the intra-prediction information of the current block may be set to MPM mode and binary-coded, and the remaining intra-prediction information may be binary-coded separately. This disclosure can save binary-coded bits by performing appropriate context modeling when binary-coding each intra-prediction piece of information. Alternatively, this disclosure can transmit candidate intra-prediction information to the video decoder 200 by using a binary-coded method such as truncated binary, truncated unary, or fixed length, taking into account the number of candidate intra-prediction pieces of information included in the intra-prediction candidate list.

[0265] Information indicating whether the method proposed in this disclosure (i.e., the merge mode) is applied (hereinafter referred to as "information on whether the merge mode is applied") may be signaled using HLS (High-level syntax). That is, information on whether the Bonn merge mode is applied may be signaled using VPS (video parameter set), SPS (sequence parameter set), PPS (picture parameter set), picture header, slice header, DCI, etc. For example, in order to determine whether the merge mode is applied on a PPS basis, information on whether the merge mode is applied may be signaled using PPS.

[0266] Furthermore, the video decoding device 200 can adaptively determine whether or not the merged mode is applied without signaling information about whether or not the merged mode is applied. Alternatively, the video decoding device 200 can determine whether or not the merged mode is applied by parsing the information about whether or not the merged mode is applied. For example, the video encoding device 100 can transmit the merged mode application information on a CTU or CU basis. In this case, the information about whether or not the merged mode is applied may be transmitted to the video decoding device 200 by a 1-bit flag.

[0267] When the application of merge mode is determined by factors such as the size of a specific block, the shape of a specific block, or whether specific conditions are met, information regarding the application of merge mode may be signaled only when those conditions are met. In this case, the information regarding the application of merge mode may be transmitted to the video decoding device 200 by a 1-bit flag. Here, the specific block may be the current block, a surrounding block, or a corresponding rumor block, and this disclosure is not limited thereto. For example, merge mode may not be applied if the height of a specific block is four times or more the width of the specific block. In this case, signaling of information regarding the application of merge mode may be omitted. Furthermore, the application of merge mode may be implicitly inferred when specific conditions are met.

[0268] Whether or not information about the application of merged mode is signaled in the coding unit may be adaptively determined based on the information about the application of merged mode signaled in the HLS. For example, if the information about the application of merged mode signaled in the SPS is false (i.e., merged mode is not applied at the SPS level), then merged mode does not need to be applied in the coding unit, and therefore, information about the application of merged mode does not need to be signaled.

[0269] Figure 14 is a flowchart illustrating the method for applying the merged mode according to this disclosure. Referring to Figure 14, the video encoding device 100 and / or the video decoding device 200 can search for adjacent peripheral blocks, non-adjacent peripheral blocks, and / or corresponding rumor blocks (S1410). Here, adjacent peripheral blocks and / or non-adjacent peripheral blocks may be the blocks shown in Figure 11. The corresponding rumor block may be block 1320 shown in Figure 13. The video encoding device 100 and / or the video decoding device 200 can collect intra-prediction information for adjacent peripheral blocks, non-adjacent peripheral blocks, and / or corresponding rumor blocks (S1430). The video encoding device 100 and / or the video decoding device 200 can construct an intra-prediction candidate list based on the collected intra-prediction information (S1450). The video encoding device 100 and / or the video decoding device 200 can select intra-prediction information from the intra-prediction candidate list (S1470). The video encoding device 100 and / or the video decoding device 200 can perform current chroma block prediction based on selected intra-prediction information (S1490). That is, the video encoding device 100 and / or the video decoding device 200 can generate a predicted block of the current chroma block by applying the selected intra-prediction information to the current chroma block.

[0270] Figure 15 is a flowchart illustrating an encoding method according to one embodiment of the present disclosure. Referring to Figure 15, the video encoding device 100 can acquire one or more candidate intra-prediction information based on intra-prediction information of surrounding blocks of the current block (S1510). Here, candidate intra-prediction information may include at least one of the following: TIMD (Template based intra-mode derivation) information, DIMD (Decoder side intra-mode derivation) information or linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi-reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra-sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra-smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion information, peripheral reference sample characteristics information, or IBC (intra-block copy) information.

[0271] The video encoding device 100 can configure an intra-prediction candidate list (S1530). Specifically, the video encoding device 100 can configure an intra-prediction candidate list based on one or more candidate intra-prediction information. According to one embodiment of the present disclosure, when the current block is a color difference block, the intra-prediction candidate list may be configured based on a first candidate intra-prediction information of a block surrounding the color difference block and a second candidate intra-prediction information of a rumor block corresponding to the color difference block. That is, when the current block is a color difference block, the intra-prediction candidate list may be configured based on the intra-prediction information of a block surrounding the current block (i.e., the first candidate intra-prediction information) and the intra-prediction information of the corresponding rumor block (i.e., the second candidate intra-prediction information).

[0272] Furthermore, based on the fact that the second candidate intra-prediction information includes linear model information, the intra-prediction candidate list may include at least one of the following: a first intra-prediction candidate list composed of linear model information, or a second intra-prediction candidate list composed of information other than linear model information. That is, when the current block is a color difference block, the video encoding device 100 can separate the linear model information from the other information to form two intra-prediction candidate lists (i.e., a first intra-prediction candidate list and a second intra-prediction candidate list). Alternatively, when the current block is a color difference block, the video encoding device 100 can form an intra-prediction candidate list (i.e., a second intra-prediction candidate list) using only linear model information. Alternatively, when the current block is a color difference block, the video encoding device 100 can form an intra-prediction candidate list (i.e., a first intra-prediction candidate list) using only information other than linear model information.

[0273] The video encoding device 100 can generate a predicted block for the current block (S1550). Specifically, the video encoding device 100 can generate a predicted block for the current block based on one candidate intra-prediction information included in the intra-prediction candidate list.

[0274] The video encoding device 100 can encode an intra-prediction candidate index (S1570). Here, the intra-prediction candidate index may be information indicating one candidate intra-prediction information included in the intra-prediction candidate list.

[0275] Figure 16 is a flowchart showing a decoding method according to one embodiment of the present disclosure. Referring to Figure 16, the video decoding device 200 can acquire one or more candidate intra-prediction information based on intra-prediction information of surrounding blocks of the current block (S1610). Here, candidate intra-prediction information may include at least one of the following: TIMD (Template based intra-mode derivation) information, DIMD (Decoder side intra-mode derivation) information or linear model information, LIP (Linear interpolation intra prediction) information, PDPC (position dependent intra prediction) information, MRL (multi-reference line) information, TMRL (Template-based multiple reference line) information, ISP (intra-sub-partition) information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode dependent intra-smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion information, peripheral reference sample characteristics information, or IBC (intra-block copy) information.

[0276] The video decoding device 200 can configure an intra prediction candidate list (S1630). Specifically, the video decoding device 200 can configure an intra prediction candidate list based on one or more candidate intra prediction information. According to an embodiment of the present disclosure, when the current block is a chrominance block, the intra prediction candidate list may be configured based on the first candidate intra prediction information of the peripheral blocks of the chrominance block and the second candidate intra prediction information of the luminance block corresponding to the chrominance block. That is, when the current block is a chrominance block, the intra prediction candidate list may be configured based on the intra prediction information of the peripheral blocks of the current block (i.e., the first candidate intra prediction information) and the intra prediction information of the corresponding luminance block (i.e., the second candidate intra prediction information).

[0277] Further, based on the fact that the linear model information is included in the second candidate intra prediction information, the intra prediction candidate list may include at least one of a first intra prediction candidate list configured with the linear model information or a second intra prediction candidate list configured with information other than the linear model information. That is, when the current block is a chrominance block, the video decoding device 200 can separate the linear model information and the other information to configure two intra prediction candidate lists (i.e., the first intra prediction candidate list and the second intra prediction candidate list). Or, when the current block is a chrominance block, the video decoding device 200 can configure an intra prediction candidate list (i.e., the second intra prediction candidate list) only with the linear model information. Or, when the current block is a chrominance block, the video decoding device 200 can configure an intra prediction candidate list (i.e., the first intra prediction candidate list) only with information other than the linear model information.

[0278] The video decoding device 200 can obtain an intra prediction candidate index (S1650). Here, the intra prediction candidate index may be information indicating one candidate intra prediction information included in the intra prediction candidate list.

[0279] The video decoding device 200 can generate a predicted block of the current block (S1670). Specifically, the video decoding device 200 can generate a predicted block of the current block by performing intra prediction based on the candidate intra prediction information indicated by the intra prediction candidate index.

[0280] The exemplary method of the present disclosure is presented in a series of operations for the sake of clarity of explanation, but this is not for limiting the order in which the steps are performed. If necessary, each step may be performed simultaneously or in a different order. To implement the method according to the present disclosure, other steps may be further included in the exemplified steps, or the remaining steps may be included except for some steps, or still other steps may be included except for some steps.

[0281] In the present disclosure, a video encoding device or a video decoding device that performs a predetermined operation (step) can perform an operation (step) of checking the execution conditions or circumstances of the operation (step). For example, when it is described that a predetermined operation is performed when a predetermined condition is satisfied, the video encoding device or the video decoding device can perform the predetermined operation after performing an operation of checking whether the predetermined condition is satisfied.

[0282] The various embodiments of the present disclosure do not enumerate all possible combinations, but are for explaining representative aspects of the present disclosure. Matters described in the various embodiments may be applied independently or in combinations of two or more.

[0283] Furthermore, various embodiments of this disclosure may be embodied in hardware, firmware, software, or a combination thereof. In the case of hardware embodiment, they may be embodied in one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), general processors, controllers, microcontrollers, microprocessors, etc.

[0284] Furthermore, the video decoding and video encoding devices to which the embodiments of this disclosure are applied may be included in multimedia broadcasting transceivers, mobile communication terminals, home cinema video equipment, digital cinema video equipment, surveillance cameras, video conferencing equipment, real-time communication equipment such as video communication, mobile streaming equipment, storage media, camcorders, video-on-demand (VoD) service providers, over-the-top (OTT) video equipment, internet streaming service providers, 3D video equipment, image-phone video equipment, and medical video equipment, and may be used to process video signals or data signals. For example, over-the-top (OTT) video equipment may include game consoles, Blu-ray players, internet-connected TVs, home theater systems, smartphones, tablet PCs, and digital video recorders (DVRs).

[0285] Figure 17 illustrates a content streaming system to which the embodiments of this disclosure can be applied.

[0286] As shown in Figure 17, a content streaming system to which an embodiment of the present disclosure is applied may broadly include an encoding server, a streaming server, a web server, media storage, user equipment, and multimedia input devices.

[0287] The encoding server is responsible for compressing content input from multimedia input devices such as smartphones, cameras, and camcorders into digital data to generate a bitstream, and transmitting this bitstream to the streaming server. As another example, if a multimedia input device such as a smartphone, camera, or camcorder directly generates the bitstream, the encoding server may be omitted.

[0288] The bitstream may be generated by a video encoding method and / or video encoding apparatus to which an embodiment of the present disclosure is applied, and the streaming server may temporarily store the bitstream in the process of transmitting or receiving the bitstream.

[0289] The streaming server transmits multimedia data to user devices based on user requests via a web server, and the web server can act as an intermediary to inform users of available services. When a user requests a desired service from the web server, the web server transmits it to the streaming server, and the streaming server can transmit multimedia data to the user. In this case, the content streaming system may include a separate control server, in which case the control server can play a role in controlling commands and responses between the devices within the content streaming system.

[0290] The streaming server can receive content from media storage and / or encoding servers. For example, when receiving content from the encoding server, the content can be received in real time. In this case, in order to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0291] Examples of user devices include mobile phones, smartphones, laptop computers, digital broadcasting terminals, PDAs (personal digital assistants), PMPs (portable multimedia players), navigation systems, slate PCs, tablet PCs, ultrabooks, wearable devices (such as smartwatches, smart glasses, and HMDs), digital TVs, desktop computers, and digital signage.

[0292] Each server within the aforementioned content streaming system may be operated as a distributed server, in which case the data received by each server may be processed in a distributed manner.

[0293] The scope of this disclosure includes software or machine-executable instructions (e.g., operating systems, applications, firmware, programs, etc.) that enable the operation of various embodiments to be performed on a device or computer, and non-transitory computer-readable medium on which such software or instructions are stored and executable on a device or computer. [Industrial applicability]

[0294] The embodiments described herein can be used for encoding / decoding video.

Claims

1. A video decoding method performed by a video decoding device, The current step involves obtaining one or more candidate intra-prediction information based on the intra-prediction information of surrounding blocks in the current block. The steps include: constructing an intra-prediction candidate list based on one or more candidate intra-prediction information; The steps include obtaining an intra-prediction candidate index that indicates one candidate intra-prediction information included in the intra-prediction candidate list, The step of generating a predicted block for the current block by performing an intra prediction based on the candidate intra prediction information indicated by the intra prediction candidate index, The candidate intra prediction information includes TIMD (Template-based intra-mode derivative) information, DIMD (Decoder-side intra-mode derivative) information, or linear model information, LIP (Linear intervention intra prediction) information, PDPC (position-dependent intra prediction) information, MRL (multi-reference line) information, TMRL (Template-based multiple reference line) information, and ISP (intra sub-partition information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode-dependent intra smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion This includes at least one of the following: fusion information, peripheral reference sample characteristic information, or IBC (intrablock copy) information. Video decoding method.

2. The surrounding blocks are determined based on one of the following: template matching, bilateral matching, or SATD (Sum of absolute transformed differences). The video decoding method according to claim 1.

3. The aforementioned intra-prediction candidate index is determined based on one of the following: template matching, bilateral matching, or SATD (Sum of absolute transformed differences). The video decoding method according to claim 1.

4. The order of the candidate intra-prediction information included in the intra-prediction candidate list is rearranged based on either template matching or bidirectional matching. The video decoding method according to claim 1.

5. The candidate intra-prediction information includes information regarding whether the corresponding candidate intra-prediction mode is applicable. The video decoding method according to claim 1.

6. The candidate intra-prediction information further includes additional information used to apply the corresponding candidate intra-prediction mode. The video decoding method according to claim 5.

7. The prediction block is generated based on at least one of the candidate intra prediction mode or the additional information. The video decoding method according to claim 6.

8. The number of candidate intra-prediction information items included in the intra-prediction candidate list is determined based on at least one of the following: the size of the current block, the location of subblocks within the current block, the statistical characteristics of the surrounding blocks, or whether a quadratic transformation is used for the current block. The video decoding method according to claim 1.

9. The acquisition order of the surrounding blocks is determined based on at least one of the following: the size of the current block, the position of the subblocks within the current block, the statistical characteristics of the surrounding blocks, or whether a quadratic transformation is used on the current block. The video decoding method according to claim 1.

10. The position of the surrounding block is determined based on at least one of the following: the size of the current block, the position of subblocks within the current block, the statistical characteristics of the surrounding block, or whether a quadratic transformation is used on the current block. The video decoding method according to claim 1.

11. Based on the fact that the current block is a color difference block, the intra-prediction candidate list is constructed based on first candidate intra-prediction information for surrounding blocks of the color difference block and second candidate intra-prediction information for rumor blocks corresponding to the color difference block. The video decoding method according to claim 1.

12. Based on the fact that the second candidate intra-prediction information includes the linear model information, the intra-prediction candidate list includes at least one of the first intra-prediction candidate list composed of the linear model information or the second intra-prediction candidate list composed of information other than the linear model information. The video decoding method according to claim 11.

13. A video encoding method performed by a video encoding device, The current step involves obtaining one or more candidate intra-prediction information based on the intra-prediction information of surrounding blocks in the current block. The steps include: constructing an intra-prediction candidate list based on one or more candidate intra-prediction information; The steps include generating a predicted block for the current block based on one candidate intra prediction information included in the intra prediction candidate list, The step includes encoding an intra-prediction candidate index that represents one of the candidate intra-prediction pieces of information, The candidate intra prediction information includes TIMD (Template-based intra-mode derivative) information, DIMD (Decoder-side intra-mode derivative) information, or linear model information, LIP (Linear intervention intra prediction) information, PDPC (position-dependent intra prediction) information, MRL (multi-reference line) information, TMRL (Template-based multiple reference line) information, and ISP (intra sub-partition information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode-dependent intra smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion This includes at least one of the following: fusion information, peripheral reference sample characteristic information, or IBC (intrablock copy) information. Video encoding method.

14. A computer-readable recording medium storing a bitstream generated by the video encoding method described in claim 13.

15. A method for transmitting a bitstream generated by a video encoding method, wherein the video encoding method is The current step involves obtaining one or more candidate intra-prediction information based on the intra-prediction information of surrounding blocks in the current block. The steps include: constructing an intra-prediction candidate list based on one or more candidate intra-prediction information; The steps include generating a predicted block for the current block based on one candidate intra prediction information included in the intra prediction candidate list, The step includes encoding an intra-prediction candidate index that represents one of the candidate intra-prediction pieces of information, The candidate intra prediction information includes TIMD (Template-based intra-mode derivative) information, DIMD (Decoder-side intra-mode derivative) information, or linear model information, LIP (Linear intervention intra prediction) information, PDPC (position-dependent intra prediction) information, MRL (multi-reference line) information, TMRL (Template-based multiple reference line) information, and ISP (intra sub-partition information, MIP (matrix-based intra prediction) information, interpolation filter information, MDIS (mode-dependent intra smoothing) information, CIIP (combined inter and intra prediction) information, SGPM (spatial geometric partition mode) information, intra-TMP (template matching intra prediction) information, in-screen prediction directionality mode information, extended planar information, intra-prediction fusion This includes at least one of the following: fusion information, peripheral reference sample characteristic information, or IBC (intrablock copy) information. Bitstream transmission method.

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