WO2015083988A1 - Procédé et dispositif de codage/décodage de signal vidéo multi-couche - Google Patents

Procédé et dispositif de codage/décodage de signal vidéo multi-couche Download PDF

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WO2015083988A1
WO2015083988A1 PCT/KR2014/011547 KR2014011547W WO2015083988A1 WO 2015083988 A1 WO2015083988 A1 WO 2015083988A1 KR 2014011547 W KR2014011547 W KR 2014011547W WO 2015083988 A1 WO2015083988 A1 WO 2015083988A1
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layer
prediction
direct dependency
inter
picture
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PCT/KR2014/011547
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Korean (ko)
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이배근
김주영
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주식회사 케이티
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
    • H04N19/31—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability in the temporal domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/103—Selection of coding mode or of prediction mode
    • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/174—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a slice, e.g. a line of blocks or a group of blocks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/187—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a scalable video layer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

  • the present invention relates to a method and apparatus for encoding / decoding multilayer video signals.
  • High efficiency image compression techniques can be used to solve these problems caused by high resolution and high quality image data.
  • An inter-screen prediction technique for predicting pixel values included in the current picture from a picture before or after the current picture using an image compression technique an intra prediction technique for predicting pixel values included in a current picture using pixel information in the current picture
  • An object of the present invention is to provide a method and apparatus for determining a corresponding picture of a reference layer used for inter-layer prediction of a current picture of a current layer in encoding / decoding a multilayer video signal.
  • An object of the present invention is to provide a method and apparatus for upsampling a corresponding picture of a reference layer for inter-layer texture prediction or inter-layer motion prediction in encoding / decoding a multilayer video signal.
  • An object of the present invention is to provide a method and apparatus for effectively determining a direct dependency type used for inter-layer prediction of a current layer in encoding / decoding a multilayer video signal.
  • An object of the present invention is to provide a method and apparatus for effectively deriving texture information or motion information of a current layer through inter-layer prediction in encoding / decoding a multilayer video signal.
  • the method and apparatus for decoding a multilayer video signal determine a reference layer used for inter-layer prediction of a current layer based on a direct dependency flag, and reference the reference based on interlayer reference information of the current picture. Determines whether the corresponding picture of the layer is used for inter-layer prediction of the current picture of the current layer, and when the corresponding picture of the reference layer is used for inter-layer prediction of the current picture, according to a direct dependency type. At least one of inter-layer texture prediction or inter-layer motion prediction of the current picture is performed using the corresponding picture.
  • the interlayer reference information may include at least one of an interlayer prediction flag, reference picture number information, or a reference layer identifier.
  • the direct dependency type may be a first type in which the current picture refers only to texture information of a corresponding picture of the reference layer, and wherein the current picture is the same as that of the reference layer.
  • the second type may refer to either a second type for referring to only motion information of a corresponding picture or a third type for referring to both texture information and motion information of a corresponding picture of the reference layer.
  • the direct dependency type is determined based on a default direct dependency present flag.
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence.
  • the direct dependency type is a direct dependency type used in the entire video sequence. If the value of the default direct dependency present flag is 0, the direct dependency type is inter-layer between the layers in the current layer in relation to the reference layer. And is determined based on the direct dependency type information for identifying the direct dependency type used for prediction.
  • the method and apparatus for encoding a multilayer video signal determine a reference layer used for inter-layer prediction of a current layer based on a direct dependency flag, and reference the reference based on interlayer reference information of the current picture. Determines whether the corresponding picture of the layer is used for inter-layer prediction of the current picture of the current layer, and if the corresponding picture of the reference layer is used for inter-layer prediction of the current picture, according to the direct dependency type. At least one of inter-layer texture prediction or inter-layer motion prediction of the current picture is performed by using a corresponding picture.
  • the interlayer reference information may include at least one of an interlayer prediction flag, reference picture number information, or a reference layer identifier.
  • the direct dependency type may be a first type in which the current picture refers only to texture information of a corresponding picture of the reference layer, and the current picture is the same as that of the reference layer.
  • the second type may refer to either a second type for referring to only motion information of a corresponding picture or a third type for referring to both texture information and motion information of a corresponding picture of the reference layer.
  • the direct dependency type is determined based on a default direct dependency present flag.
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence.
  • the direct dependency type is a direct dependency type used in the entire video sequence. If the value of the default direct dependency present flag is 0, the direct dependency type is inter-layer between the layers in the current layer in relation to the reference layer. And is determined based on the direct dependency type information for identifying the direct dependency type used for prediction.
  • the memory can be effectively managed by adaptively using the corresponding picture of the reference layer for inter-layer prediction of the current picture of the current layer.
  • texture information and / or motion information of the current layer can be effectively derived through inter-layer prediction according to the direct dependency type.
  • FIG. 1 is a block diagram schematically illustrating an encoding apparatus according to an embodiment of the present invention.
  • FIG. 2 is a block diagram schematically illustrating a decoding apparatus according to an embodiment of the present invention.
  • FIG. 3 is a flowchart illustrating a process of performing inter-layer prediction of a current layer using a corresponding picture of a reference layer according to an embodiment to which the present invention is applied.
  • FIG. 4 illustrates a method of determining a corresponding picture of a reference layer used for inter-layer prediction based on a reference active flag as an embodiment to which the present invention is applied.
  • FIG. 5 illustrates a method of acquiring interlayer reference information about a current picture according to an embodiment to which the present invention is applied.
  • FIG. 6 illustrates a syntax table of interlayer reference information according to an embodiment to which the present invention is applied.
  • FIG. 7 illustrates a method of determining a direct dependency type of a current picture based on direct dependency type information (direct_dependency_type) according to an embodiment to which the present invention is applied.
  • FIG. 8 illustrates a method of determining a direct dependency type of a current picture based on a default direct dependency present flag according to an embodiment to which the present invention is applied.
  • FIG. 9 illustrates a method of determining a direct dependency type of a current picture based on default direct dependency mode information (default_direct_dependency_mode) according to an embodiment to which the present invention is applied.
  • FIG. 10 illustrates a method of determining a direct dependency type of a current picture based on a default direct dependency present flag or a layer-default direct dependency present flag according to an embodiment to which the present invention is applied. will be.
  • FIG. 11 illustrates an embodiment to which the present invention is applied and determines a direct dependency type of a current picture based on default direct dependency mode information (default_direct_dependency_mode) or layer-default direct dependency mode information (layer_default_direct_dependency_mode). The method is shown.
  • default_direct_dependency_mode default direct dependency mode information
  • layer_default_direct_dependency_mode layer-default direct dependency mode information
  • FIG. 12 is a flowchart illustrating a method of upsampling a corresponding picture of a reference layer according to an embodiment to which the present invention is applied.
  • the method and apparatus for decoding a multilayer video signal determine a reference layer used for inter-layer prediction of a current layer based on a direct dependency flag, and reference the reference based on interlayer reference information of the current picture. Determines whether the corresponding picture of the layer is used for inter-layer prediction of the current picture of the current layer, and when the corresponding picture of the reference layer is used for inter-layer prediction of the current picture, according to a direct dependency type. At least one of inter-layer texture prediction or inter-layer motion prediction of the current picture is performed using the corresponding picture.
  • the interlayer reference information may include at least one of an interlayer prediction flag, reference picture number information, or a reference layer identifier.
  • the direct dependency type may be a first type in which the current picture refers only to texture information of a corresponding picture of the reference layer, and wherein the current picture is the same as that of the reference layer.
  • the second type may refer to either a second type for referring to only motion information of a corresponding picture or a third type for referring to both texture information and motion information of a corresponding picture of the reference layer.
  • the direct dependency type is determined based on a default direct dependency present flag.
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence.
  • the direct dependency type is a direct dependency type used in the entire video sequence. If the value of the default direct dependency present flag is 0, the direct dependency type is inter-layer between the layers in the current layer in relation to the reference layer. And is determined based on the direct dependency type information for identifying the direct dependency type used for prediction.
  • the method and apparatus for encoding a multilayer video signal determine a reference layer used for inter-layer prediction of a current layer based on a direct dependency flag, and reference the reference based on interlayer reference information of the current picture. Determines whether the corresponding picture of the layer is used for inter-layer prediction of the current picture of the current layer, and if the corresponding picture of the reference layer is used for inter-layer prediction of the current picture, according to the direct dependency type. At least one of inter-layer texture prediction or inter-layer motion prediction of the current picture is performed by using a corresponding picture.
  • the interlayer reference information may include at least one of an interlayer prediction flag, reference picture number information, or a reference layer identifier.
  • the direct dependency type may be a first type in which the current picture refers only to texture information of a corresponding picture of the reference layer, and the current picture is the same as that of the reference layer.
  • the second type may refer to either a second type for referring to only motion information of a corresponding picture or a third type for referring to both texture information and motion information of a corresponding picture of the reference layer.
  • the direct dependency type is determined based on a default direct dependency present flag.
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence.
  • the direct dependency type is a direct dependency type used in the entire video sequence. If the value of the default direct dependency present flag is 0, the direct dependency type is inter-layer between the layers in the current layer in relation to the reference layer. And is determined based on the direct dependency type information for identifying the direct dependency type used for prediction.
  • first and second may be used to describe various configurations, but the configurations are not limited by the terms. The terms are used to distinguish one configuration from another.
  • first configuration may be referred to as the second configuration, and similarly, the second configuration may also be referred to as the first configuration.
  • each component shown in the embodiments of the present invention are independently shown to represent different characteristic functions, and do not mean that each component is made of separate hardware or one software component unit.
  • each component is listed as a component for convenience of description, and at least two of the components may form one component, or one component may be divided into a plurality of components to perform a function.
  • the integrated and separated embodiments of each component are also included in the scope of the present invention without departing from the spirit of the present invention.
  • the components may not be essential components for performing essential functions in the present invention, but may be optional components for improving performance.
  • the present invention can be implemented including only the components essential for implementing the essentials of the present invention except for the components used for improving performance, and the structure including only the essential components except for the optional components used for improving performance. Also included in the scope of the present invention.
  • Encoding and decoding of video that supports multiple layers in a bitstream is called scalable video coding. Since there is a strong correlation between the plurality of layers, the prediction may be performed by using this correlation to remove redundant elements of data and to improve encoding performance of an image. Performing prediction of the current layer using information of another layer is referred to as inter-layer prediction or inter-layer prediction in the following.
  • the plurality of layers may have different resolutions, where the resolution may mean at least one of spatial resolution, temporal resolution, and image quality. Resampling such as up-sampling or downsampling of a layer may be performed to adjust the resolution during inter-layer prediction.
  • FIG. 1 is a block diagram schematically illustrating an encoding apparatus according to an embodiment of the present invention.
  • the encoding apparatus 100 includes an encoder 100a for an upper layer and an encoder 100b for a lower layer.
  • the upper layer may be expressed as a current layer or an enhancement layer
  • the lower layer may be expressed as an enhancement layer, a base layer, or a reference layer having a lower resolution than the upper layer.
  • the upper layer and the lower layer may have at least one of a spatial resolution, a temporal resolution according to a frame rate, and an image quality according to a color format or a quantization size. When a resolution change is necessary to perform inter-layer prediction, upsampling or downsampling of a layer may be performed.
  • the encoder 100a of the upper layer may include a divider 110, a predictor 120, a transformer 130, a quantizer 140, a reorderer 150, an entropy encoder 160, and an inverse quantizer ( 170, an inverse transform unit 180, a filter unit 190, and a memory 195.
  • the encoder 100b of the lower layer includes a divider 111, a predictor 125, a transformer 131, a quantizer 141, a reordering unit 151, an entropy encoder 161, and an inverse quantizer ( 171, an inverse transform unit 181, a filter unit 191, and a memory 196.
  • the encoder may be implemented by the image encoding method described in the following embodiments of the present invention, but operations in some components may not be performed to reduce the complexity of the encoding apparatus or for fast real time encoding.
  • some limited number of methods are used without selecting the optimal intra intra coding method using all intra prediction modes in order to perform encoding in real time.
  • a method of selecting one intra prediction mode among them as a final intra prediction mode using the intra prediction mode of the image may be used.
  • the unit of a block processed by the encoding apparatus may be a coding unit that performs encoding, a prediction unit that performs prediction, or a transformation unit that performs transformation.
  • a coding unit may be represented by a term such as a coding unit (CU), a prediction unit is a prediction unit (PU), and a transformation unit is a transform unit (TU).
  • the splitters 110 and 111 divide a layer image into a combination of a plurality of coding blocks, prediction blocks, and transform blocks, and one of the coding blocks, prediction blocks, and transform blocks according to a predetermined criterion (for example, a cost function). You can split the layer by selecting the combination of. For example, to split a coding unit in a layer image, a recursive tree structure such as a quad tree structure may be used.
  • a recursive tree structure such as a quad tree structure may be used.
  • the meaning of the coding block may be used not only as a block for encoding but also as a block for decoding.
  • the prediction block may be a unit for performing prediction such as intra prediction or inter prediction.
  • the block for performing intra prediction may be a block having a square shape such as 2N ⁇ 2N or N ⁇ N.
  • As a block for performing inter prediction there is a prediction block partitioning method using Asymmetric Motion Partitioning (AMP), which is a square form such as 2Nx2N and NxN, or a rectangular form or asymmetric form such as 2NxN and Nx2N.
  • AMP Asymmetric Motion Partitioning
  • the transform unit 115 may change a method of performing the transform.
  • the prediction units 120 and 125 of the encoders 100a and 100b may include the intra prediction units 121 and 126 performing intra prediction and the inter prediction unit performing inter prediction. (122, 127).
  • the predictor 120 of the higher layer encoder 100a may further include an inter-layer predictor 123 that performs prediction on the higher layer by using information of the lower layer.
  • the prediction units 120 and 125 may determine whether to use inter prediction or intra prediction on the prediction block.
  • the process of determining the intra prediction mode in units of prediction blocks and performing the intra prediction based on the determined intra prediction mode may be performed in units of transform blocks.
  • the residual value (residual block) between the generated prediction block and the original block may be input to the transformers 130 and 131.
  • prediction mode information and motion information used for prediction may be encoded by the entropy encoder 130 together with the residual value and transmitted to the decoding apparatus.
  • the original block may be encoded as it is and transmitted to the decoder without performing prediction through the prediction units 120 and 125.
  • PCM Pulse Coded Modulation
  • the intra prediction units 121 and 126 may generate an intra prediction block based on reference pixels present around the current block (the block to be predicted).
  • the intra prediction mode may have a directional prediction mode using a reference pixel according to a prediction direction and a non-directional mode without considering the prediction direction.
  • the mode for predicting luma information and the mode for predicting color difference information may be different.
  • an intra prediction mode in which luma information is predicted or predicted luma information may be used. If the reference pixel is not available, the unusable reference pixel may be replaced with another pixel, and a prediction block may be generated using the reference pixel.
  • the prediction block may include a plurality of transform blocks. If the prediction block has the same size as the transform block when the intra prediction is performed, pixels present on the left side of the prediction block, pixels present on the upper left side, and top Intra-prediction of the prediction block may be performed based on the pixels present in the. However, when the prediction block is different from the size of the transform block when the intra prediction is performed, and a plurality of transform blocks are included in the prediction block, intra prediction is performed by using neighboring pixels adjacent to the transform block as reference pixels. Can be done.
  • the neighboring pixel adjacent to the transform block may include at least one of the neighboring pixel adjacent to the prediction block and the pixels already decoded in the prediction block.
  • the intra prediction method may generate a prediction block after applying a mode dependent intra smoothing (MDIS) filter to a reference pixel according to the intra prediction mode.
  • MDIS mode dependent intra smoothing
  • the type of MDIS filter applied to the reference pixel may be different.
  • the MDIS filter is an additional filter applied to the predicted block in the picture by performing the intra prediction and may be used to reduce the residual present in the predicted block in the picture generated after performing the prediction with the reference pixel.
  • filtering on a reference pixel and some columns included in the predicted block in the screen may perform different filtering according to the direction of the intra prediction mode.
  • the inter prediction units 122 and 127 may perform prediction by referring to information of a block included in at least one of a previous picture or a subsequent picture of the current picture.
  • the inter prediction units 122 and 127 may include a reference picture interpolator, a motion predictor, and a motion compensator.
  • the reference picture interpolation unit may receive reference picture information from the memories 195 and 196 and generate pixel information of an integer pixel or less in the reference picture.
  • a DCT-based 8-tap interpolation filter having different filter coefficients may be used to generate pixel information of integer pixels or less in units of 1/4 pixels.
  • a DCT-based interpolation filter having different filter coefficients may be used to generate pixel information of an integer pixel or less in units of 1/8 pixels.
  • the inter prediction units 122 and 127 may perform motion prediction based on the reference picture interpolated by the reference picture interpolator.
  • various methods such as a full search-based block matching algorithm (FBMA), a three step search (TSS), and a new three-step search algorithm (NTS) may be used.
  • the motion vector may have a motion vector value of 1/2 or 1/4 pixel units based on the interpolated pixels.
  • the inter prediction units 122 and 127 may perform prediction on the current block by applying one inter prediction method among various inter prediction methods.
  • various methods such as a skip method, a merge method, and a motion vector predictor (MVP), may be used as the inter prediction method.
  • MVP motion vector predictor
  • motion information that is, information such as a reference index, a motion vector, and a residual signal
  • motion information is entropy coded and transmitted to a decoder.
  • the skip mode since the residual signal is not generated, the conversion and quantization processes for the residual signal may be omitted.
  • the interlayer prediction unit 123 performs interlayer prediction for predicting an upper layer by using information of a lower layer.
  • the inter-layer prediction unit 123 may perform inter-layer prediction using texture information, motion information, etc. of the lower layer.
  • prediction of a current block of an upper layer may be performed using motion information on a picture of a lower layer (reference layer) using a picture of a lower layer as a reference picture.
  • the picture of the reference layer used as the reference picture in inter-layer prediction may be a picture sampled according to the resolution of the current layer.
  • the motion information may include a motion vector and a reference index. In this case, the value of the motion vector for the picture of the reference layer may be set to (0,0).
  • the inter-layer prediction unit 123 may perform inter-layer texture prediction, inter-layer motion prediction, inter-layer syntax prediction, and inter-layer difference prediction.
  • Inter-layer texture prediction may derive the texture of the current layer based on the texture of the reference layer.
  • the texture of the reference layer may be sampled according to the resolution of the current layer, and the inter-layer predictor 123 may predict the texture of the current layer based on the sampled texture of the reference layer.
  • Inter-layer motion prediction may derive the motion vector of the current layer based on the motion vector of the reference layer.
  • the motion vector of the reference layer may be scaled according to the resolution of the current layer.
  • the syntax of the current layer may be predicted based on the syntax of the reference layer.
  • the inter-layer prediction unit 123 may use the syntax of the reference layer as the syntax of the current layer.
  • the picture of the current layer may be reconstructed using the difference between the reconstructed image of the reference layer and the reconstructed image of the current layer.
  • a residual block including residual information which is a difference between the predicted block generated by the predictors 120 and 125 and the reconstructed block of the predicted block, is generated, and the residual block is input to the transformers 130 and 131.
  • the transform units 130 and 131 may transform the residual block using a transform method such as a discrete cosine transform (DCT) or a discrete sine transform (DST). Whether DCT or DST is applied to transform the residual block may be determined based on intra prediction mode information of the prediction block used to generate the residual block and size information of the prediction block. That is, the transformers 130 and 131 may apply the transformation method differently according to the size of the prediction block and the prediction method.
  • a transform method such as a discrete cosine transform (DCT) or a discrete sine transform (DST).
  • DCT discrete cosine transform
  • DST discrete sine transform
  • the quantizers 140 and 141 may quantize the values transformed by the transformers 130 and 131 into the frequency domain.
  • the quantization coefficient may change depending on the block or the importance of the image.
  • the values calculated by the quantizers 140 and 141 may be provided to the dequantizers 170 and 17 and the reordering units 150 and 151.
  • the reordering units 150 and 151 may reorder coefficient values with respect to the quantized residual value.
  • the reordering units 150 and 151 may change the two-dimensional block shape coefficients into a one-dimensional vector form through a coefficient scanning method.
  • the realignment units 150 and 151 may scan DC coefficients to coefficients in the high frequency region by using a Zig-Zag scan method and change them into one-dimensional vectors.
  • a vertical scan method for scanning two-dimensional block shape coefficients in a column direction, not a zig-zag scan method, and a horizontal scan method for scanning two-dimensional block shape coefficients in a row direction Can be used. That is, according to the size of the transform block and the intra prediction mode, it is possible to determine which scan method among zigzag-scan, vertical scan and horizontal scan is used.
  • the entropy encoders 160 and 161 may perform entropy encoding based on the values calculated by the reordering units 150 and 151. Entropy encoding may use various encoding methods such as, for example, Exponential Golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC).
  • Exponential Golomb Context-Adaptive Variable Length Coding
  • CABAC Context-Adaptive Binary Arithmetic Coding
  • the entropy encoders 160 and 161 transmit residual value coefficient information, block type information, prediction mode information, partition unit information, prediction block information, and the like of the coding block from the reordering units 150 and 151 and the prediction units 120 and 125. Entropy encoding may be performed based on a predetermined encoding method by receiving various information such as unit information, motion information, reference frame information, block interpolation information, and filtering information. In addition, the entropy encoder 160 or 161 may entropy-encode coefficient values of coding units input from the reordering unit 150 or 151.
  • the entropy encoders 160 and 161 may encode the intra prediction mode information of the current block by performing binarization on the intra prediction mode information.
  • the entropy encoder 160 or 161 may include a codeword mapping unit for performing such a binarization operation, and may perform different binarization according to the size of a prediction block for performing intra prediction.
  • the codeword mapping unit the codeword mapping table may be adaptively generated or stored in advance through a binarization operation.
  • the entropy encoders 160 and 161 may express prediction mode information in the current screen using a codenum mapping unit for performing codenum mapping and a codeword mapping unit for performing codeword mapping. In the codenum mapping unit and the codeword mapping unit, a codenum mapping table and a codeword mapping table may be generated or stored.
  • the inverse quantizers 170 and 171 and the inverse transformers 180 and 181 inverse quantize the quantized values in the quantizers 140 and 141 and inversely transform the converted values in the transformers 130 and 131.
  • the residual values generated by the inverse quantizers 170 and 171 and the inverse transformers 180 and 181 may be predicted by the motion estimator, the motion compensator, and the intra prediction unit included in the predictors 120 and 125. It may be combined with the prediction block to generate a reconstructed block.
  • the filter units 190 and 191 may include at least one of a deblocking filter and an offset correction unit.
  • the deblocking filter may remove block distortion caused by boundaries between blocks in the reconstructed picture.
  • it may be determined whether to apply a deblocking filter to the current block based on the pixels included in several columns or rows included in the block.
  • a strong filter or a weak filter may be applied according to the required deblocking filtering strength.
  • horizontal filtering and vertical filtering may be performed in parallel when vertical filtering and horizontal filtering are performed.
  • the offset correction unit may correct the offset with respect to the original image on a pixel-by-pixel basis for the deblocking image.
  • the pixels included in the image are divided into predetermined areas, and then, the area to be offset is determined and the offset is applied to the corresponding area, or the offset is applied considering the edge information of each pixel. Can be used.
  • the filter units 190 and 191 may apply only the deblocking filter or both the deblocking filter and the offset correction without applying both the deblocking filter and the offset correction.
  • the memories 195 and 196 may store reconstructed blocks or pictures calculated by the filters 190 and 191, and the stored reconstructed blocks or pictures may be provided to the predictors 120 and 125 when performing inter prediction. have.
  • the information output from the entropy encoder 100b of the lower layer and the information output from the entropy encoder 100a of the upper layer may be multiplexed by the MUX 197 and output as a bitstream.
  • the MUX 197 may be included in the encoder 100a of the upper layer or the encoder 100b of the lower layer, or may be implemented as an independent device or module separate from the encoder 100.
  • FIG. 2 is a block diagram schematically illustrating a decoding apparatus according to an embodiment of the present invention.
  • the decoding apparatus 200 includes a decoder 200a of an upper layer and a decoder 200b of a lower layer.
  • the decoder 200a of the upper layer includes an entropy decoder 210, a reordering unit 220, an inverse quantization unit 230, an inverse transform unit 240, a prediction unit 250, a filter unit 260, and a memory 270. ) May be included.
  • the lower layer decoding unit 200b includes an entropy decoding unit 211, a reordering unit 221, an inverse quantization unit 231, an inverse transform unit 241, a prediction unit 251, a filter unit 261, and a memory 271. ) May be included.
  • the DEMUX 280 may demultiplex information for each layer and transmit the information to the decoders 200a and 200b for each layer.
  • the input bitstream may be decoded in a procedure opposite to that of the encoding apparatus.
  • the entropy decoders 210 and 211 may perform entropy decoding in a procedure opposite to that of the entropy encoder in the encoding apparatus.
  • Information for generating a prediction block among the information decoded by the entropy decoders 210 and 211 is provided to the predictors 250 and 251, and the residual value obtained by entropy decoding by the entropy decoders 210 and 211 is a reordering unit. It may be input to (220, 221).
  • the entropy decoders 210 and 211 may use at least one of CABAC and CAVLC.
  • the entropy decoders 210 and 211 may decode information related to intra prediction and inter prediction performed by the encoding apparatus.
  • the entropy decoder 210 or 211 may include a codeword mapping unit and include a codeword mapping table for generating a received codeword as an intra prediction mode number.
  • the codeword mapping table may be stored in advance or generated adaptively.
  • a codenum mapping unit for performing codenum mapping may be additionally provided.
  • the reordering units 220 and 221 may reorder the bitstreams entropy decoded by the entropy decoding units 210 and 211 based on a method of rearranging the bitstreams by the encoder. Coefficients expressed in the form of a one-dimensional vector may be reconstructed by reconstructing the coefficients in a two-dimensional block form.
  • the reordering units 220 and 221 may be realigned by receiving information related to coefficient scanning performed by the encoder and performing reverse scanning based on the scanning order performed by the corresponding encoder.
  • the inverse quantization units 230 and 231 may perform inverse quantization based on quantization parameters provided by the encoding apparatus and coefficient values of the rearranged block.
  • the inverse transformers 240 and 241 may perform inverse DCT or inverse DST on the DCT or DST performed by the transformers 130 and 131 with respect to the quantization result performed by the encoding apparatus.
  • the inverse transform may be performed based on a transmission unit determined by the encoding apparatus.
  • the DCT and the DST may be selectively performed by the transform unit of the encoding apparatus according to a plurality of pieces of information, such as a prediction method, a size of the current block, and a prediction direction.
  • the inverse transformers 240 and 241 of the decoding apparatus may convert Inverse transformation may be performed based on the performed transformation information. When the transform is performed, the transform may be performed based on the coding block rather than the transform block.
  • the prediction units 250 and 251 may generate the prediction blocks based on the prediction block generation related information provided by the entropy decoding units 210 and 211 and previously decoded blocks or picture information provided by the memories 270 and 271. .
  • the predictors 250 and 251 may include a prediction unit determiner, an inter prediction unit, and an intra prediction unit.
  • the prediction unit discriminator receives various information such as prediction unit information input from the entropy decoder, prediction mode information of the intra prediction method, and motion prediction related information of the inter prediction method, and distinguishes the prediction block from the current coding block. It is possible to determine whether to perform this inter prediction or intra prediction.
  • the inter prediction unit uses information required for inter prediction of the current prediction block provided by the encoding apparatus to the current prediction block based on information included in at least one of a previous picture or a subsequent picture of the current picture including the current prediction block. Inter prediction can be performed.
  • a motion prediction method of a prediction block included in a coding block based on a coding block uses a skip mode, a merge mode, a motion vector predictor (MVP) (AMVP). Mode) can be determined.
  • the intra prediction unit may generate a prediction block based on the reconstructed pixel information in the current picture.
  • intra prediction may be performed based on intra prediction mode information of the prediction block provided by the encoding apparatus.
  • the intra prediction unit is an MDIS filter that performs filtering on the reference pixel of the current block, a reference pixel interpolator that generates a reference pixel of an integer value or less by interpolating the reference pixel, and filters when the prediction mode of the current block is DC mode. It may include a DC filter for generating a prediction block through.
  • the predictor 250 of the upper layer decoder 200a may further include an inter-layer predictor that performs inter-layer prediction for predicting an upper layer by using information of the lower layer.
  • the inter-layer prediction unit may perform inter-layer prediction using intra prediction mode information and motion information.
  • prediction of a current block of an upper layer may be performed using motion information of a lower layer (reference layer) picture using a picture of a lower layer as a reference picture.
  • the picture of the reference layer used as the reference picture in inter-layer prediction may be a picture sampled according to the resolution of the current layer.
  • the motion information may include a motion vector and a reference index.
  • the value of the motion vector for the picture of the reference layer may be set to (0,0).
  • inter-layer prediction unit 123 may further perform inter-layer texture prediction, inter-layer motion prediction, inter-layer syntax prediction, and inter-layer difference prediction.
  • Inter-layer texture prediction may derive the texture of the current layer based on the texture of the reference layer.
  • the texture of the reference layer may be sampled according to the resolution of the current layer, and the inter-layer predictor may predict the texture of the current layer based on the sampled texture.
  • Inter-layer motion prediction may derive the motion vector of the current layer based on the motion vector of the reference layer. In this case, the motion vector of the reference layer may be scaled according to the resolution of the current layer.
  • the syntax of the current layer may be predicted based on the syntax of the reference layer.
  • the inter-layer prediction unit 123 may use the syntax of the reference layer as the syntax of the current layer.
  • the picture of the current layer may be reconstructed using the difference between the reconstructed image of the reference layer and the reconstructed image of the current layer.
  • the reconstructed block or picture may be provided to the filter units 260 and 261.
  • the filter units 260 and 261 may include a deblocking filter and an offset correction unit.
  • the deblocking filter of the decoding apparatus may receive the deblocking filter related information provided by the encoding apparatus and perform the deblocking filtering on the corresponding block in the decoding apparatus.
  • the offset correction unit may perform offset correction on the reconstructed image based on the type of offset correction and offset value information applied to the image during encoding.
  • the memories 270 and 271 may store the reconstructed picture or block to be used as the reference picture or the reference block, and output the reconstructed picture.
  • the encoding apparatus and the decoding apparatus may encode three or more layers instead of two layers.
  • a plurality of encoders for a higher layer and a decoder for a higher layer may be provided in correspondence to the number of upper layers. Can be.
  • SVC Scalable Video Coding
  • the current layer may generate a prediction sample of the current layer by using a decoded picture of a reference layer used for inter-layer prediction as a reference picture.
  • the picture of the decoded reference layer matches the scalability of the current layer.
  • Resampling may be performed and then used as a reference picture for inter-layer prediction of the current layer. Resampling means up-sampling or downsampling samples of a reference layer picture according to a picture size of a current layer.
  • the current layer refers to a layer on which current encoding or decoding is performed, and may be an enhancement layer or an upper layer.
  • the reference layer refers to a layer referenced by the current layer for inter-layer prediction and may be a base layer or a lower layer.
  • a picture (ie, a reference picture) of a reference layer used for inter-layer prediction of the current layer may be referred to as an interlayer reference picture or an inter-layer reference picture.
  • FIG. 3 is a flowchart illustrating a process of performing inter-layer prediction of a current layer using a corresponding picture of a reference layer according to an embodiment to which the present invention is applied.
  • a reference layer used for inter-layer prediction of the current layer may be determined (S300).
  • the current layer may perform inter-layer prediction by selectively using all or some layers of the plurality of layers included in the video sequence.
  • a layer (hereinafter referred to as a reference layer) used for inter-layer prediction of the current layer may be determined based on a direct dependency flag.
  • the direct dependency flag direct_dependency_flag [i] [j] may indicate whether the i th layer (ie, the current layer) is a layer having direct dependency on the j th layer.
  • the direct dependency flag may indicate whether the j th layer is used for inter-layer prediction of the i th layer.
  • the j th layer may be used for inter-layer prediction of the i th current layer.
  • the j th layer may be used. It may not be used for inter-layer prediction of the i th current layer.
  • the corresponding picture of the reference layer may mean a picture located at the same time zone as the current picture of the current layer.
  • the corresponding picture may mean a picture having the same picture order count (POC) information as the current picture of the current layer.
  • POC picture order count
  • the corresponding picture of the reference layer may be included in the same Access Unit (AU) as the current picture of the current layer.
  • the corresponding picture may have the same temporal level ID (TemporalID) as the current picture of the current layer.
  • the temporal level identifier may specify each of a plurality of sub-layers that are scalable in accordance with temporal resolution.
  • the current picture may use a corresponding picture of one or more reference layers for inter-layer prediction, and a method of determining the corresponding picture will be described with reference to FIGS. 4 to 6.
  • inter-layer texture prediction or layer prediction of the current picture according to the direct dependency type using the corresponding picture may be performed (S320).
  • the direct dependency type is i) a first type in which the current picture refers only to texture information of the corresponding picture of the reference layer, ii) a second type in which the current picture refers only to motion information of the corresponding picture of the reference layer, or iii).
  • the current picture may include at least one of the third types referring to both texture information and motion information of the corresponding picture of the reference layer.
  • the current picture may selectively use any one of the first to third types described above, and a method of determining the direct dependency type of the current picture will be described with reference to FIGS. 7 to 11.
  • the current picture may be used for inter-layer prediction by upsampling the corresponding picture of the reference layer. That is, texture information (ie, sample) and / or motion information of the corresponding picture of the reference layer may be upsampled in consideration of spatial resolution, and the texture information and / or motion information of the current picture may be predicted using this.
  • texture information ie, sample
  • / or motion information of the corresponding picture of the reference layer may be upsampled in consideration of spatial resolution, and the texture information and / or motion information of the current picture may be predicted using this.
  • FIG. 4 illustrates a method of determining a corresponding picture of a reference layer used for inter-layer prediction based on a reference active flag as an embodiment to which the present invention is applied.
  • a reference active flag may be obtained from a bitstream (S400).
  • the reference active flag all_ref_layers_active_flag may indicate whether the constraint that the corresponding picture of all reference layers having direct dependency with the current layer is used for inter-layer prediction of the current picture is applied.
  • the reference active flag may be obtained from a video parameter set of the bitstream.
  • whether the layer has a direct dependency with the current layer may be determined based on the direct dependency flag direct_dependency_flag [i] [j], as described with reference to FIG. 3.
  • step S410 it may be determined whether the value of the reference active flag acquired in step S400 is 1.
  • the corresponding pictures of all the reference layers having direct dependency with the current layer are used for inter-layer prediction of the current picture.
  • the corresponding pictures of all the reference layers having direct dependency with the current layer may be included in the reference picture list of the current picture. Accordingly, the corresponding pictures of all the reference layers having direct dependency with the current layer may be determined as corresponding pictures used for inter-layer prediction of the current picture (S420).
  • the current picture of the current layer may perform inter-layer prediction using corresponding pictures of all reference layers having direct dependency on the current layer, and some correspondence among all reference layers having direct dependency on the current layer.
  • Inter-layer prediction may be performed using only pictures. That is, when the value of the reference active flag is 0, corresponding pictures of all reference layers having direct dependency with the current layer may be included in the reference picture list of the current picture, or only some corresponding pictures may be selectively included. Therefore, it is necessary to specify the corresponding picture used for inter-layer prediction of the current picture among the reference layers having the current layer and direct dependency. To this end, interlayer reference information about the current picture may be obtained (S430).
  • the interlayer reference information may include at least one of an interlayer prediction flag, reference picture number information, or a reference layer identifier.
  • the interlayer prediction flag may indicate whether inter-layer prediction is used in the decoding process of the current picture.
  • the reference picture number information may indicate the number of corresponding pictures used for inter-layer prediction of the current picture.
  • the reference picture number information may be encoded and signaled by subtracting 1 from the number of corresponding pictures used for inter-layer prediction of the current picture for coding efficiency.
  • the reference layer identifier may mean a layer identifier (layerId) of a layer including a corresponding picture used for inter-layer prediction of the current picture.
  • a corresponding picture used for inter-layer prediction of the current picture may be determined based on the interlayer reference information acquired in step S430 (S440).
  • the corresponding picture of the layer specified by the reference layer identifier among the reference layers having direct dependency on the current layer may be determined as the corresponding picture used for inter-layer prediction of the current picture.
  • FIG. 5 illustrates a method of obtaining interlayer reference information on a current picture as an embodiment to which the present invention is applied
  • FIG. 6 illustrates a syntax table of interlayer reference information as an embodiment to which the present invention is applied. It is shown.
  • an interlayer prediction flag may be obtained based on a reference active flag (S500).
  • the interlayer prediction flag inter_layer_pred_enabled_flag may be obtained only when the value of the reference active flag all_ref_layers_active_flag is 0 (S600).
  • the value of the reference active flag is 1, this may mean that corresponding pictures of all reference layers having direct dependency on the current layer are used for inter-layer prediction of the current picture. Thus, in this case, there is no need to signal the interlayer prediction flag in the header information (eg, slice segment header) of the current picture.
  • the interlayer prediction flag may be obtained.
  • the layer identifier of the current layer is 0, this is because the current layer corresponds to a base layer that does not perform inter-layer prediction among a plurality of layers included in the video sequence.
  • the interlayer prediction flag may be obtained when the number NumDirectRefLayers of the reference layer having direct dependency with the current layer is at least one. This is because when there is no layer having direct dependency on the current layer, all pictures of the current layer do not perform inter-layer prediction.
  • step S500 it may be checked whether the value of the interlayer prediction flag acquired in step S500 is 1 (S510).
  • step S510 when the value of the interlayer prediction flag is 1, reference picture number information may be obtained (S520).
  • the reference picture number information may indicate the number of corresponding pictures used for inter-layer prediction of the current picture among the corresponding pictures of the reference layer having direct dependency on the current layer.
  • the reference picture number information may be limitedly obtained based on the maximum active reference flag.
  • the maximum active reference flag may indicate whether only at least one corresponding picture is used for inter-layer prediction of the current picture. For example, when the value of the maximum active reference flag is 1, the current picture performs inter-layer prediction using only at least one corresponding picture. When the value of the maximum active reference flag is 0, the current picture is one or more corresponding. Inter-layer prediction may be performed using a picture.
  • reference picture number information may be obtained only when the value of the maximum active reference flag max_one_active_ref_layer_flag is zero. That is, when the value of the maximum active reference flag is 1, it is not necessary to signal reference picture number information because the number of corresponding pictures used for inter-layer prediction of the current picture is limited to one.
  • a reference layer identifier may be obtained based on the reference picture number information acquired in S520 (S530).
  • the number of corresponding pictures (NumActiveRefLayerPics) used for inter-layer prediction of the current picture and the current layer have direct dependency.
  • the number of reference layers NumDirectRefLayers is different, a reference layer identifier may be obtained.
  • the variable NumActiveRefLayerPics is a variable derived from the reference picture number information. For example, when reference picture number information is encoded by subtracting 1 from the number of corresponding pictures used for inter-layer prediction of the current picture, the variable NumActiveRefLayerPics adds 1 to the reference picture number information acquired in step S520. Can be induced.
  • FIG. 7 illustrates a method of determining a direct dependency type of a current picture based on direct dependency type information (direct_dependency_type) according to an embodiment to which the present invention is applied.
  • direct dependency type information direct_dependency_type [i] [j] may be obtained from the bitstream (S700).
  • the direct dependency type information may mean information for identifying a direct dependency type for inter-layer prediction of a current layer.
  • the direct dependency type information may be obtained for each reference layer used for inter-layer prediction of the current layer.
  • the i th layer refers only to texture information of the j th layer.
  • the i th layer is motion of the j th layer.
  • the i th layer may refer to both texture information and motion information of the j th layer.
  • the direct dependency type of the current layer is determined in relation to each reference layer according to the direct dependency type information, and the inter-layer texture prediction or inter-layer motion prediction of the current picture is determined according to the determined direct dependency type. At least one of the following may be performed.
  • FIG. 8 illustrates a method of determining a direct dependency type of a current picture based on a default direct dependency present flag according to an embodiment to which the present invention is applied.
  • a default direct dependency present flag (default_direct_dependency_present_flag) may be obtained from a bitstream (S800).
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence. For example, if the value of the default direct dependency present flag is 1, this indicates that the same direct dependency type is used throughout the video sequence, and the value of the default direct dependency present flag is 0. In this case, this may indicate that the same direct dependency type is not used throughout the video sequence. That is, when the value of the default direct dependency present flag is 0, a different direct dependency type may be used for each reference layer for the current layer.
  • default direct dependency type information (default_direct_dependency_type) may be obtained (S810).
  • the default direct dependency type information may indicate a direct dependency type used in the entire video sequence. Specifically, when the value of the default direct dependency type information is 0, all inter-layer prediction in the video sequence is performed by referring to texture information of a reference layer only. When the value of the default direct dependency type information is 1, the video is performed. All inter-layer prediction in the sequence is performed by referring only to the motion information of the reference layer. If the value of the default direct dependency type information is 2, all inter-layer prediction in the video sequence is performed on the texture information and motion information of the reference layer. Can be performed by referring to all of them.
  • the direct dependency type of the current picture may be determined according to the value of the default direct dependency type information applied to the entire video sequence.
  • step S800 when the value of the default direct dependency present flag in step S800 is 0, direct dependency type information direct_dependency_type [i] [j] may be obtained (S820).
  • the direct dependency type information direct_dependency_type [i] [j] is obtained for each j-th layer (i.e., reference layer) used for inter-layer prediction of the i-th layer (ie, the current layer).
  • the direct dependency type for inter-layer prediction of the i-th layer may be identified. This has been described with reference to FIG. 7, and a detailed description thereof will be omitted.
  • FIG. 9 illustrates a method of determining a direct dependency type of a current picture based on default direct dependency mode information (default_direct_dependency_mode) according to an embodiment to which the present invention is applied.
  • default direct dependency mode information (default_direct_dependency_mode) may be obtained from a bitstream (S900).
  • the default direct dependency mode information may indicate whether the same direct dependency type is used in the entire video sequence and the direct dependency type used in the entire video sequence.
  • the value of the default direct dependency mode information when the value of the default direct dependency mode information is 0, this may indicate that the same direct dependency type is not used in the entire video sequence. If the value of the default direct dependency mode information is 1, all inter-layer prediction in the video sequence is performed by referring to texture information of a reference layer only. If the value of the default direct dependency mode information is 2, All inter-layer prediction is performed by referring only to motion information of the reference layer. When the value of the default direct dependency mode information is 3, all inter-layer prediction in the video sequence refers to both texture information and motion information of the reference layer. It may indicate that it is performed.
  • the direct dependency type of the current picture may be determined according to the value of the default direct dependency mode information.
  • direct dependency type information direct_dependency_type [i] [j] may be obtained (S910).
  • the direct dependency type information direct_dependency_type [i] [j] is obtained for each j-th layer (i.e., reference layer) used for inter-layer prediction of the i-th layer (ie, the current layer).
  • the direct dependency type for inter-layer prediction of the i-th layer may be identified. This has been described with reference to FIG. 7, and a detailed description thereof will be omitted.
  • FIG. 10 illustrates a method of determining a direct dependency type of a current picture based on a default direct dependency present flag or a layer-default direct dependency present flag according to an embodiment to which the present invention is applied. will be.
  • a default direct dependency present flag (default_direct_dependency_present_flag) may be obtained from a bitstream (S1000).
  • the default direct dependency present flag may indicate whether the same direct dependency type is used in the entire video sequence. For example, if the value of the default direct dependency present flag is 1, this indicates that the same direct dependency type is used throughout the video sequence, and the value of the default direct dependency present flag is 0. In this case, this may indicate that the same direct dependency type is not used throughout the video sequence. That is, when the value of the default direct dependency present flag is 0, a different direct dependency type may be used for each reference layer for the current layer.
  • default direct dependency type information (default_direct_dependency_type) may be obtained (S1010).
  • the default direct dependency type information may indicate a direct dependency type used in the entire video sequence. Specifically, when the value of the default direct dependency type information is 0, all inter-layer prediction in the video sequence is performed by referring to texture information of a reference layer only. When the value of the default direct dependency type information is 1, the video is performed. All inter-layer prediction in the sequence is performed by referring only to the motion information of the reference layer. If the value of the default direct dependency type information is 2, all inter-layer prediction in the video sequence is performed on the texture information and motion information of the reference layer. Can be performed by referring to all of them.
  • the direct dependency type of the current picture may be determined according to the value of the default direct dependency type information applied to the entire video sequence.
  • a layer-default direct dependency present flag (layer_default_direct_dependency_present_flag [i]) may be obtained (S1020).
  • the layer-default direct dependency present flag may indicate whether the i th layer uses the same direct dependency type in relation to all reference layers used for inter-layer prediction. .
  • the value of the layer-default direct dependency present flag is 1, the same direct dependency type is used in inter-layer prediction of the i-th layer, and the value of the layer-default direct dependency present flag is 0 may indicate that a different direct dependency type may be used for each reference layer in inter-layer prediction of the i-th layer.
  • step S1030 layer-default direct dependency type information (layer_default_direct_dependency_type [i]) may be obtained (S1030).
  • the layer-default direct dependency type information layer_default_direct_dependency_type [i] may identify a direct dependency type that is identically used in all reference layers of the i th layer.
  • all inter-layer predictions in the i-th layer are performed by referring only to texture information of the reference layer, and that of the layer-default direct dependency type information. If the value is 1, all inter-layer prediction in the i-th layer is performed by referring to only motion information of the reference layer. If the value of the layer-default direct dependency type information is 2, all inter-layer prediction in the i-th layer is This may be performed by referring to both texture information and motion information of the reference layer.
  • the direct dependency type of the current picture of the i th layer (ie, the current layer) may be determined according to the obtained layer-default direct dependency type information.
  • step S1020 When the value of the layer-default direct dependency present flag in step S1020 is 0, direct dependency type information direct_dependency_type [i] [j] may be obtained (S1040).
  • the direct dependency type information direct_dependency_type [i] [j] is obtained for each j-th layer (i.e., reference layer) used for inter-layer prediction of the i-th layer (ie, the current layer).
  • the direct dependency type for inter-layer prediction of the i-th layer may be identified. This has been described with reference to FIG. 7, and a detailed description thereof will be omitted.
  • FIG. 11 illustrates an embodiment to which the present invention is applied and determines a direct dependency type of a current picture based on default direct dependency mode information (default_direct_dependency_mode) or layer-default direct dependency mode information (layer_default_direct_dependency_mode). The method is shown.
  • default_direct_dependency_mode default direct dependency mode information
  • layer_default_direct_dependency_mode layer-default direct dependency mode information
  • default direct dependency mode information (default_direct_dependency_mode) may be obtained from a bitstream (S1100).
  • the default direct dependency mode information may indicate whether the same direct dependency type is used in the entire video sequence and the direct dependency type used in the entire video sequence.
  • the value of the default direct dependency mode information when the value of the default direct dependency mode information is 0, this may indicate that the same direct dependency type is not used in the entire video sequence. If the value of the default direct dependency mode information is 1, all inter-layer prediction in the video sequence is performed by referring to texture information of a reference layer only. If the value of the default direct dependency mode information is 2, All inter-layer prediction is performed by referring only to motion information of the reference layer. When the value of the default direct dependency mode information is 3, all inter-layer prediction in the video sequence refers to both texture information and motion information of the reference layer. It may indicate that it is performed.
  • the direct dependency type of the current picture may be determined according to the value of the default direct dependency mode information.
  • layer_default_direct_dependency_mode [i] may be obtained from the bitstream (S1110).
  • the layer-default direct dependency mode information may indicate whether the same direct dependency type is used in inter-layer prediction of the i th layer and a direct dependency type used in the i th layer.
  • the value of the layer-default direct dependency mode information when the value of the layer-default direct dependency mode information is 0, this may indicate that the same direct dependency type is not used in inter-layer prediction of the i-th layer.
  • the value of the layer-default direct dependency mode information is 1, all inter-layer prediction in the i-th layer is performed by referring only to texture information of a reference layer, and the value of the layer-default direct dependency mode information is 2. In this case, all inter-layer prediction in the i-th layer is performed by referring to only motion information of the reference layer.
  • the value of the layer-default direct dependency mode information is 3, all inter-layer prediction in the i-th layer is performed by the reference layer. This may be performed by referring to both texture information and motion information.
  • the direct dependency type of the current picture may be determined according to the value of the layer-default direct dependency mode information.
  • the direct dependency type information direct_dependency_type [i] [j] is obtained for each j-th layer (i.e., reference layer) used for inter-layer prediction of the i-th layer (ie, the current layer).
  • the direct dependency type for inter-layer prediction of the i-th layer may be identified. This has been described with reference to FIG. 7, and a detailed description thereof will be omitted.
  • FIG. 12 is a flowchart illustrating a method of upsampling a corresponding picture of a reference layer according to an embodiment to which the present invention is applied.
  • a reference sample position of a reference layer corresponding to the current sample position of the current layer may be derived (S1200).
  • the reference sample position corresponding to the current sample position may be derived in consideration of the resolution difference between the two. That is, the aspect ratio may be considered between the picture of the current layer and the picture of the reference layer.
  • an offset for correcting this may be required.
  • the reference sample position may be derived in consideration of the scale factor and the upsampled reference layer offset.
  • the scale factor may be calculated based on a ratio of the width and the height between the current picture of the current layer and the corresponding picture of the reference layer.
  • the upsampled reference layer offset refers to position difference information between any sample located at the edge of the current picture and any sample located at the edge of the reference picture (hereinafter referred to as an interlayer reference picture) used for inter-layer prediction. can do.
  • the upsampled reference layer offset includes horizontal position information in the horizontal / vertical direction between the upper left sample of the current picture and the upper left sample of the interlayer reference picture, and the lower right sample of the current picture and the lower right sample of the interlayer reference picture.
  • Position difference information in the horizontal / vertical direction of the liver may be included.
  • the upsampled reference layer offset may be obtained from the bitstream.
  • the upsampled reference layer offset may be obtained from at least one of a video parameter set, a sequence parameter set, a picture parameter set, and a slice header. Can be.
  • a filter coefficient of the upsampling filter may be determined in consideration of the phase of the reference sample position derived in step S1200 (S1210).
  • the upsampling filter may be any one of a fixed upsampling filter and an adaptive upsampling filter.
  • the fixed upsampling filter may mean an upsampling filter having a predetermined filter coefficient without considering the feature of the image.
  • a tap filter may be used as the fixed upsampling filter, which may be defined for the luminance component and the chrominance component, respectively.
  • a fixed upsampling filter having an accuracy of 1/16 sample units will be described with reference to Tables 1 to 2.
  • Table 1 is a table that defines the filter coefficients of the fixed upsampling filter for the luminance component.
  • interpolation may be performed using a reference sample of a reference layer corresponding to the current sample of the current layer and a neighboring sample adjacent to the reference sample.
  • the neighbor sample may be specified according to the direction in which interpolation is performed. For example, when performing interpolation in the horizontal direction, the neighboring sample may include three consecutive samples to the left and four consecutive samples to the right based on the reference sample. Alternatively, when performing interpolation in the vertical direction, the neighboring sample may include three consecutive samples at the top and four consecutive samples at the bottom based on the reference sample.
  • the fixed upsampling filter may use different filter coefficients for each phase p. Except in the case where phase p is zero, the magnitude of each filter coefficient may be defined to fall in the range of 0 to 63. This means that the filtering is performed with a precision of 6 bits.
  • a phase p of 0 means a position of an integer multiple of n times when interpolated in units of 1 / n samples.
  • Table 2 is a table that defines the filter coefficients of the fixed upsampling filter for the chrominance components.
  • a 4-tap filter may be applied unlike the luminance component. That is, interpolation may be performed using a reference sample of a reference layer corresponding to the current sample of the current layer and a neighboring sample adjacent to the reference sample.
  • the neighbor sample may be specified according to the direction in which interpolation is performed. For example, when performing interpolation in the horizontal direction, the neighboring sample may include one sample to the left and two samples to the right based on the reference sample. Alternatively, when performing interpolation in the vertical direction, the neighboring sample may include one sample continuous to the top and two samples continuous to the bottom based on the reference sample.
  • each filter coefficient may be defined to be in the range of 0 to 62. This also means filtering with 6bits precision.
  • an 8-tap filter is applied to the luminance component and a 4-tap filter to the chrominance component
  • the present invention is not limited thereto, and the order of the tap filter may be variably determined in consideration of coding efficiency.
  • the order of the tap filter may be variably determined in consideration of coding efficiency.
  • an optimal filter coefficient may be determined by an encoder in consideration of characteristics of an image, signaled, and transmitted to a decoder.
  • the adaptive upsampling filter uses the filter coefficients that are adaptively determined in the encoder. Since the characteristics of the image are different in picture units, coding efficiency can be improved by using an adaptive upsampling filter that can express the characteristics of the image better than using a fixed upsampling filter in all cases.
  • the interlayer reference picture may be generated by applying the filter coefficient determined in operation S1210 to the corresponding picture of the reference layer (S1220).
  • interpolation may be performed by applying the determined filter coefficients of the upsampling filter to samples of the corresponding picture.
  • the interpolation may be performed primarily in the horizontal direction, and may be performed in the vertical direction secondary to the sample generated after the horizontal interpolation.
  • the present invention can be used to code a video signal of a multilayer structure.

Abstract

Un procédé de codage/décodage de signal vidéo multi-couche selon la présente invention, détermine une image de référence qui est utilisée pour une prédiction inter-couche d'une image actuelle d'après un drapeau de dépendance directe, détermine si une image correspondante de la couche de référence est utilisée pour une prédiction inter-couche de l'image actuelle de la couche actuelle d'après des informations de référence inter-couche de l'image actuelle et,si l'image correspondante de la couche de référence est utilisée pour une prédiction inter-couche de l'image actuelle, exécute une prédiction de texture inter-couche ou une prédiction de mouvement inter-couche de l'image actuelle au moyen de l'image correspondante d'après le type de dépendance directe.
PCT/KR2014/011547 2013-12-03 2014-11-28 Procédé et dispositif de codage/décodage de signal vidéo multi-couche WO2015083988A1 (fr)

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KR20120072718A (ko) * 2010-12-24 2012-07-04 전자부품연구원 액세스 유닛 단위 처리를 이용한 스케일러블 비디오 코딩의 복호화 장치 및 방법
WO2013147557A1 (fr) * 2012-03-29 2013-10-03 엘지전자 주식회사 Procédé de prédiction entre couches, et dispositif de codage et dispositif de décodage l'utilisant
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