WO2015056941A1

WO2015056941A1 - Multilayer-based image encoding/decoding method and apparatus

Info

Publication number: WO2015056941A1
Application number: PCT/KR2014/009580
Authority: WO
Inventors: 강정원; 이진호; 이하현; 최진수; 김진웅
Original assignee: 한국전자통신연구원
Priority date: 2013-10-14
Filing date: 2014-10-13
Publication date: 2015-04-23

Abstract

Disclosed are an image decoding method and an image decoding apparatus which support a plurality of layers. The image decoding method comprises the steps of: obtaining information indicating whether or not tile-related information exists; and obtaining the tile-related information on the basis of the information indicating whether or not the tile-related information exits.

Description

Multi-layer Based Image Coding / Decoding Method and Apparatus

The present invention relates to image encoding and decoding, and more particularly, to a method of representing tiles and pictures when one or more layers exist in a video bitstream.

Recently, as a multimedia environment is established, various terminals and networks are used, and user demands are diversifying accordingly.

For example, as the performance and computing capability of the terminal are diversified, the supporting performance is also diversified by device. In addition, the network in which information is transmitted is also diversified not only in the external structure such as wired and wireless networks, but also in functions such as the type of information to be transmitted, the amount and speed of information. The user selects a terminal and a network to be used according to a desired function, and the spectrum of terminals and networks provided to the user by the enterprise is also diversified.

In this regard, as a broadcast having a high definition (HD) resolution has been expanded and serviced not only in Korea but also in the world, many users are getting used to high resolution and high quality images. Accordingly, many video service related organizations are making great efforts to develop next generation video devices.

In addition, as interest in Ultra High Definition (UHD), which has more than four times the resolution of HDTV, is increasing, the demand for technology for compressing and processing higher resolution and higher quality images is increasing.

In order to compress and process an image, an inter prediction technique for predicting a pixel value included in a current picture from a previous and / or subsequent picture in time, another pixel included in the current picture using pixel information in the current picture An intra prediction technique for predicting a value, an entropy encoding technique for allocating a short sign to a high frequency symbol and a long code to a low frequency symbol may be used.

As described above, in consideration of the needs of terminals and networks having different supporting functions and diversified users, the quality, size, frame, etc. of the supported images need to be diversified accordingly.

As such, due to heterogeneous communication networks and terminals of various functions and types, scalability that variously supports image quality, resolution, size, frame rate, viewpoint, etc., has become an important function of a video format.

Therefore, in order to provide a service required by a user in various environments based on a highly efficient video encoding method, it is necessary to provide a scalability function to enable efficient video encoding and decoding in terms of time, space, image quality, and viewpoint. .

The present invention provides an image encoding / decoding method and apparatus capable of improving image encoding / decoding efficiency.

The present invention provides a method and apparatus for signaling tile related information in scalable video coding that can improve encoding / decoding efficiency.

The present invention provides a method and apparatus for signaling information related to representation format in scalable video coding that can improve encoding / decoding efficiency.

According to an embodiment of the present invention, an image decoding method supporting a plurality of layers is provided. The image decoding method includes acquiring information indicating whether tile related information exists and acquiring the tile related information based on information indicating whether the tile related information exists.

The tile related information may be information indicating whether a position of a tile existing in a picture of a current layer corresponds to a position of a tile existing in a picture of a reference layer referenced by the current layer.

According to another embodiment of the present invention, an image decoding method supporting a plurality of layers is provided. The image decoding method may further include obtaining information indicating whether chroma format related information and bit-depth related information exist, and whether the chrominance format related information and bit depth related information exist. And obtaining the color difference format related information and the bit depth related information based on the information indicating the.

In the present invention, when there is one or more tiles per layer in the hierarchical bitstream, parallel encoding / decoding of the hierarchical bitstream is possible through signaling of correlation between layers. Encoding / decoding can be facilitated. In addition, encoding / decoding efficiency may be improved by signaling efficient picture representation related information.

1 is a block diagram illustrating a configuration of an image encoding apparatus according to an embodiment of the present invention.

2 is a block diagram illustrating a configuration of an image decoding apparatus according to an embodiment of the present invention.

3 is a conceptual diagram schematically illustrating an embodiment of a scalable video coding structure using multiple layers to which the present invention can be applied.

4 is a diagram illustrating a tile area that is removed and emptied in one picture.

5 is a flowchart schematically illustrating a method of acquiring tile related information in a scalable video coding structure supporting a plurality of layers according to an embodiment of the present invention.

6 is a flowchart schematically illustrating a method of acquiring representation format related information in a scalable video coding structure supporting a plurality of layers according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely with reference to drawings. In describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the description may be omitted.

When a component is referred to herein as being “connected” or “connected” to another component, it may mean that it is directly connected to or connected to that other component, or another component in between. It may also mean that an element exists. In addition, the description "includes" a specific configuration in this specification does not exclude a configuration other than the configuration, it means that additional configuration may be included in the scope of the technical spirit of the present invention or the present invention.

Terms such as 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. For example, without departing from the scope of the present invention, the first configuration may be referred to as the second configuration, and similarly, the second configuration may also be referred to as the first configuration.

In addition, the components 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. In other words, 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.

In addition, some of 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.

A scalable video encoding apparatus supporting a multi-layer structure may be implemented by extending a general image encoding apparatus having a single layer structure. The block diagram of FIG. 1 shows an embodiment of an image encoding apparatus that can be the basis of a scalable video encoding apparatus applicable to a multilayer structure.

Referring to FIG. 1, the image encoding apparatus 100 may include an inter predictor 110, an intra predictor 120, a switch 115, a subtractor 125, a transformer 130, a quantizer 140, and entropy. An encoder 150, an inverse quantizer 160, an inverse transformer 170, an adder 175, a filter 180, and a reference picture buffer 190 are included.

The image encoding apparatus 100 may encode an input image in an intra mode or an inter mode and output a bitstream.

In the intra mode, the switch 115 may be switched to intra, and in the inter mode, the switch 115 may be switched to inter. Intra prediction means intra prediction and inter prediction means inter prediction. The image encoding apparatus 100 may generate a prediction block for an input block of an input image and then encode a residual between the input block and the prediction block. In this case, the input image may mean an original picture.

In the intra mode, the intra predictor 120 may use a sample value of an already encoded / decoded block around the current block as a reference sample. The intra prediction unit 120 may perform spatial prediction using the reference sample and generate prediction samples for the current block.

In the inter mode, the inter prediction unit 110 may identify a motion vector specifying a reference block having a smallest difference from an input block (current block) in a reference picture stored in the reference picture buffer 190 during a motion prediction process. You can get it. The inter prediction unit 110 may generate a prediction block for the current block by performing motion compensation using the motion vector and the reference picture stored in the reference picture buffer 190.

In the case of a multi-layer structure, inter prediction applied in inter mode may include inter layer prediction. The inter prediction unit 110 may construct an inter-layer reference picture by sampling a picture of the reference layer, and perform inter-layer prediction by including an inter-layer reference picture in the reference picture list. The reference relationship between layers may be signaled through information specifying dependencies between layers.

Meanwhile, when the current layer picture and the reference layer picture are the same size, sampling applied to the reference layer picture may mean generation of a reference sample by copying a sample from the reference layer picture. When the resolution of the current layer picture and the reference layer picture are different, sampling applied to the reference layer picture may mean upsampling.

For example, when the resolution between layers is different, an interlayer reference picture may be configured by upsampling a reconstructed picture of a reference layer between layers that support scalability with respect to resolution.

Which layer picture is used to configure the inter-layer reference picture may be determined in consideration of an encoding cost. The encoding apparatus may transmit information specifying the layer to which the picture to be used as the inter-layer reference picture belongs, to the decoding apparatus.

In addition, a layer referred to in inter-layer prediction, that is, a picture used for prediction of the current block in the reference layer, may be a picture of the same access unit (AU) as the current picture (picture to be predicted in the current layer).

The subtractor 125 may generate a residual block by the difference between the input block and the generated prediction block.

The transform unit 130 may output a transform coefficient by performing a transform on the residual block. Here, the transform coefficient may mean a coefficient value generated by performing transform on the residual block and / or the residual signal. Hereinafter, in the present specification, a quantized transform coefficient level generated by applying quantization to a transform coefficient may also be referred to as a transform coefficient.

When the transform skip mode is applied, the transform unit 130 may omit the transform on the residual block.

The quantization unit 140 may quantize the input transform coefficient according to a quantization parameter or a quantization parameter, and output a quantized coefficient. Quantized coefficients may be referred to as quantized transform coefficient levels. In this case, the quantization unit 140 may quantize the input transform coefficients using the quantization matrix.

The entropy encoder 150 may output a bitstream by entropy encoding the values calculated by the quantizer 140 or the encoding parameter values calculated in the encoding process according to a probability distribution. The entropy encoder 150 may entropy encode information (eg, syntax elements) for video decoding in addition to the pixel information of the video.

The encoding parameter is information necessary for encoding and decoding, and may include information that may be inferred in the encoding or decoding process as well as information encoded in the encoding apparatus and delivered to the decoding apparatus, such as a syntax element.

For example, encoding parameters may include intra / inter prediction modes, moving / motion vectors, reference image indexes, coding block patterns, presence or absence of residual signals, transform coefficients, quantized transform coefficients, quantization parameters, block sizes, block division information, and the like. Or statistics.

The residual signal may mean a difference between the original signal and the prediction signal, and a signal in which the difference between the original signal and the prediction signal is transformed or a signal in which the difference between the original signal and the prediction signal is transformed and quantized It may mean. The residual signal may be referred to as a residual block in block units.

When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence and a large number of bits are allocated to a symbol having a low probability of occurrence, whereby the size of the bit string for the symbols to be encoded is increased. Can be reduced. Therefore, compression performance of image encoding may be increased through entropy encoding.

The entropy encoder 150 may use an encoding method such as exponential golomb, context-adaptive variable length coding (CAVLC), or context-adaptive binary arithmetic coding (CABAC). For example, the entropy encoder 150 may perform entropy encoding by using a variable length coding (VLC) table. In addition, the entropy encoder 150 derives a binarization method of a target symbol and a probability model of a target symbol / bin, and then performs entropy encoding using the derived binarization method or a probability model. You may.

Since the image encoding apparatus 100 according to the embodiment of FIG. 1 performs inter prediction encoding, that is, inter prediction encoding, the currently encoded image needs to be decoded and stored to be used as a reference image. Accordingly, the quantized coefficients may be inversely quantized by the inverse quantizer 160 and inversely transformed by the inverse transformer 170. The inverse quantized and inverse transformed coefficients are added to the prediction block through the adder 175 and a reconstructed block is generated.

The reconstruction block passes through the filter unit 180, and the filter unit 180 applies at least one or more of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the reconstructed block or reconstructed picture. can do. The filter unit 180 may be referred to as an adaptive in-loop filter. The deblocking filter can remove block distortion generated at the boundary between blocks. SAO can add an appropriate offset to the pixel value to compensate for coding errors. The ALF may perform filtering based on a value obtained by comparing the reconstructed image with the original image. The reconstructed block that has passed through the filter unit 180 may be stored in the reference picture buffer 190.

A scalable video decoding apparatus supporting a multi-layer structure may be implemented by extending a general image decoding apparatus having a single layer structure. The block diagram of FIG. 2 illustrates an embodiment of an image decoding apparatus that may be the basis of a scalable video decoding apparatus applicable to a multilayer structure.

2, the image decoding apparatus 200 may include an entropy decoder 210, an inverse quantizer 220, an inverse transformer 230, an intra predictor 240, an inter predictor 250, and an adder 255. ), A filter unit 260 and a reference picture buffer 270.

The image decoding apparatus 200 may receive a bitstream output from the encoder and perform decoding in an intra mode or an inter mode, and output a reconstructed image, that is, a reconstructed image.

In the intra mode, the switch may be switched to intra, and in the inter mode, the switch may be switched to inter.

The image decoding apparatus 200 may obtain a reconstructed residual block from the received bitstream, generate a prediction block, and then add the reconstructed residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block. .

The entropy decoder 210 may entropy decode the input bitstream according to a probability distribution, and output information such as quantized coefficients and syntax elements.

The quantized coefficients are inversely quantized by the inverse quantizer 220 and inversely transformed by the inverse transformer 230. As a result of inverse quantization / inverse transformation of the quantized coefficients, a reconstructed residual block may be generated. In this case, the inverse quantization unit 220 may apply a quantization matrix to the quantized coefficients.

In the intra mode, the intra predictor 240 may perform spatial prediction using sample values of blocks already decoded around the current block, and generate prediction samples for the current block.

In the inter mode, the inter prediction unit 250 may generate a prediction block for the current block by performing motion compensation using the reference picture stored in the motion vector and the reference picture buffer 270.

In the case of a multi-layer structure, inter prediction applied in inter mode may include inter layer prediction. The inter prediction unit 250 may construct an interlayer reference picture by sampling a picture of the reference layer, and perform interlayer prediction by including an interlayer reference picture in a reference picture list. The reference relationship between layers may be signaled through information specifying dependencies between layers.

For example, if inter-layer prediction is applied between layers that support scalability with respect to resolution when inter-layer resolution is different, the inter-layer reference picture may be configured by upsampling the reconstructed picture of the reference layer.

In this case, information specifying a layer to which a picture to be used as an inter-layer reference picture belongs may be transmitted from the encoding apparatus to the decoding apparatus.

The reconstructed residual block and the predictive block are added at the adder 255 to generate a reconstructed block. In other words, the residual sample and the predictive sample are added to generate a reconstructed sample or a reconstructed picture.

The reconstructed picture is filtered by the filter unit 260. The filter unit 260 may apply at least one or more of the deblocking filter, SAO, and ALF to the reconstructed block or the reconstructed picture. The filter unit 260 outputs a modified or filtered reconstructed picture. The reconstructed picture may be stored in the reference picture buffer 270 and used for inter prediction.

In addition, the image decoding apparatus 200 may further include a parser (not shown) that parses information related to an encoded image included in the bitstream. The parser may include the entropy decoder 210 or may be included in the entropy decoder 210. Such a parser may also be implemented as one component of the decoder.

In FIG. 1 and FIG. 2, one encoding device / decoding device processes both encoding / decoding for multiple layers. However, this is for convenience of description. The encoding device / decoding device may be configured for each layer.

In this case, the encoding device / decoding device of the upper layer may perform encoding / decoding of the corresponding upper layer by using the information of the upper layer and the information of the lower layer. For example, the prediction unit (inter prediction unit) of the upper layer may perform intra prediction or inter prediction on the current block by using pixel information or picture information of the upper layer, and receives picture information reconstructed from the lower layer and Inter prediction (inter layer prediction) may be performed on the current block of the upper layer by using the interlayer prediction. Here, only the prediction between layers has been described as an example. However, the encoding device / decoding device performs encoding / decoding on the current layer by using information of another layer regardless of whether the device is configured for each layer or one device processes multiple layers. can do.

In the present invention, the layer may include a view. In this case, in the case of inter-layer prediction, information of another layer between layers specified as having dependence by information specifying dependency between layers is not merely performed by using information of a lower layer. Inter layer prediction may be performed using.

3 is a conceptual diagram schematically illustrating an embodiment of a scalable video coding structure using multiple layers to which the present invention can be applied. In FIG. 3, a GOP (Group of Picture) represents a picture group, that is, a group of pictures.

In order to transmit image data, a transmission medium is required, and its performance varies depending on the transmission medium according to various network environments. A scalable video coding method may be provided for application to such various transmission media or network environments.

A video coding method that supports scalability (hereinafter, referred to as 'scalable coding' or 'scalable video coding') removes redundancy between layers by using texture information, motion information, and residual signals between layers. A coding method that improves encoding and decoding performance. The scalable video coding method has various scales in terms of spatial, temporal, image quality (or quality), and view according to ambient conditions such as transmission bit rate, transmission error rate, and system resources. It can provide the ability.

Scalable video coding may be performed using multiple layers structure to provide a bitstream applicable to various network situations. For example, the scalable video coding structure may include a base layer that compresses and processes image data using a general image decoding method, and compresses the image data using both the decoding information of the base layer and a general image decoding method. May include an enhancement layer for processing.

The base layer may be referred to as a base layer or may be referred to as a lower layer. The enhancement layer may be referred to as an enhancement layer or a higher layer. In this case, the lower layer may mean a layer that supports a lower level of scalability (spatial, temporal, image quality, or viewpoint scalability) than a specific layer, and the upper layer may have a higher level of scalability than a specific layer. It may mean a layer that supports (spatial, temporal, image quality, or view scalability). A layer referred to for encoding / decoding of another layer may be referred to as a reference layer (reference layer), and a layer encoded / decoded using another layer may be referred to as a current layer (current layer). The reference layer may be lower than the current layer, and the current layer may be higher than the reference layer.

The layer may be based on spatial (eg, image size), temporal (eg, decoding order, image output order, frame rate), image quality, complexity, view, etc. Means a set of image and bitstream to be distinguished.

Referring to FIG. 3, for example, the base layer may be defined as a standard definition (SD), a frame rate of 15 Hz, and a 1 Mbps bit rate, and the first enhancement layer may be a high definition (HD), a frame rate of 30 Hz, and a 3.9 Mbps bit rate. The second enhancement layer may be defined as 4K-UHD (ultra high definition), a frame rate of 60 Hz, and a bit rate of 27.2 Mbps.

The format, frame rate, bit rate, etc. are exemplary and may be determined differently as necessary. In addition, the number of hierarchies used is not limited to this embodiment and may be determined differently according to a situation. For example, if the transmission bandwidth is 4 Mbps, the frame rate of the first enhancement layer HD may be reduced and transmitted at 15 Hz or less.

The scalable video coding method may provide temporal, spatial, image quality, and view scalability by the method described above in the embodiment of FIG. 3. In the present specification, scalable video coding has the same meaning as scalable video encoding in terms of encoding and scalable video decoding in terms of decoding.

In the HEVC (High Efficiency Video Coding) standard, there is a method of dividing one picture into a tile form and encoding the picture independently. In other words, parallel processing is possible by dividing one picture into a plurality of tiles and independently encoding / decoding each divided tile in one picture. Therefore, information indicating how a picture in a bitstream is configured in a tile form is required. In HEVC, such tile related information is described in a picture parameter set (PPS). In addition, in HEVC, information related to picture representation, such as spatial resolution, chroma format, and bit-depth related information, is described in a Sequence Parameter Set (SPS).

In the case of scalable video coding, which is a video standard that extends HEVC to provide scalability, there may be a plurality of layers in a bitstream and correlations between layers may exist. Accordingly, the present invention provides a method for efficiently encoding / decoding tile related information through signaling of correlation between layers when a picture is composed of one or more tiles for each layer in the hierarchical bitstream. The present invention also provides a method for efficiently signaling picture representation related information in scalable video coding.

타일 관련 정보Tile related information

A tile refers to a rectangular area composed of coding tree blocks or coding tree units in a picture and may be a sequence of coding tree blocks or coding tree units. A tile always consists of integer coding tree units. Here, the coding tree block or the coding tree unit may be a processing unit of samples in the picture.

For example, one picture may be divided into two tiles by a vertical tile boundary in the picture. Each divided tile includes integer coding tree units and may be a rectangular area.

In the scalable HEVC (SHVC) standard for supporting scalable video coding and the multiview HEVC (MV-HEVC) standard for supporting multi-view, information related to tiles can be signaled in a video parameter set (VPS) and a PPS. . Particularly, in the VPS, there is flag information indicating whether the positions of tiles included in the corresponding layer are encoded / decoded so as to correspond / match with the positions of the tiles included in the reference layers of the corresponding layer. In this case, when the spatial resolution of the reference layer does not match the spatial resolution of the corresponding layer, the spatial resolution of the reference layer is scaled to be the same as the spatial resolution of the corresponding layer, and the positions of the tiles included in the scaled reference layer It may be determined whether to correspond / match with the position of the tiles of the layer based on the.

Matching / matching positions between tiles means that the boundary portions of the tiles match / match. Accordingly, tile_boundaries_aligned_flag [i] [j] is used as a flag indicating whether the positions of the tiles included in the layer are encoded / decoded to correspond / match the positions of the tiles included in the reference layers of the layer. Can be. tile_boundaries_aligned_flag [i] [j] indicates whether the i-th layer is aligned with the j-th reference layer and the position of the tile (the boundary of the tiles). However, when only one tile is included for each layer in the entire bitstream, it is not necessary to signal tile_boundaries_aligned_flag [i] [j].

Therefore, it may be efficient to signal tile_boundaries_aligned_flag [i] [j] only when there is a picture including at least two tiles.

Hereinafter, the present invention will be described using syntax as an example for a method of efficiently signaling tile_boundaries_aligned_flag [i] [j].

Table 1 is an example of a syntax illustrating a method of signaling tile_boundaries_aligned_flag [i] [j] according to an embodiment of the present invention.

Table 1

Referring to Table 1, when the vps_tiles_enabled_flag has a value of 1, it means that a picture including two or more tiles among pictures referring to the corresponding VPS may exist. When vps_tiles_enabled_flag has a value of 0, it means that all pictures of the CVS (Coded Video Stream) contain only one tile.

For example, when vps_tiles_enabled_flag is 1, tile_boundaries_aligned_flag [i] [j] may be signaled.

Table 2 is another example of a syntax illustrating a method of signaling tile_boundaries_aligned_flag [i] [j] according to an embodiment of the present invention.

TABLE 2

Referring to Table 2, when tiles_not_in_use_flag has a value of 1, it means that all pictures of the CVS include only one tile. When tiles_not_in_use_flag has a value of 0, it means that a picture including two or more tiles among pictures referring to the corresponding VPS may exist.

For example, when tiles_not_in_use_flag is 0, tile_boundaries_aligned_flag [i] [j] may be signaled.

Table 3 is another example of a syntax illustrating a method of signaling tile_boundaries_aligned_flag [i] [j] according to an embodiment of the present invention.

TABLE 3

Referring to Table 3, when vps_tiles_enabled_flag [i] has a value of 1, it means that each picture of the i-th layer includes at least two tiles. When vps_tiles_enabled_flag [i] has a value of 0, it means that all pictures of the i-th layer include only one tile.

For example, when vps_tiles_enabled_flag [i] is 1, tile_boundaries_aligned_flag [i] [j] may be signaled.

Table 4 is an example of a syntax that describes a method for signaling in a PPS using vps_tiles_enabled_flag signaled in the VPS of Table 1 according to an embodiment of the present invention.

Table 4

Referring to Table 4, when tiles_enabled_flag has a value of 1, it means that all pictures referring to the corresponding PPS include two or more tiles. When tiles_enabled_flag has a value of 0, it means that all pictures referring to the PPS include only one tile. If the tiles_enabled_flag value is not signaled, the tiles_enabled_flag value is assumed to be zero.

As shown in Table 4, whether tiles_enabled_flag is signaled or not may be determined by vps_tiles_enabled_flag. However, regardless of vps_tiles_enabled_flag, when tiles_enabled_flag is signaled as shown in Table 5, the value of tiles_enabled_flag should be 1 only when the value of vps_tiles_enabled_flag is 1. In other words, when the value of vps_tiles_enabled_flag is 0, the value of tiles_enabled_flag should always be 0.

Table 5

Table 6 is an example of a syntax that describes a method for signaling sps_tiles_enabled_flag without signaling vps_tiles_enabled_flag in an SPS according to an embodiment of the present invention.

Table 6

Referring to Table 6, when sps_tiles_enabled_flag has a value of 1, it means that all pictures referring to the corresponding SPS include two or more tiles. When sps_tiles_enabled_flag has a value of 0, it means that all pictures referring to the corresponding SPS include one tile.

In association with Table 6, instead of Table 4, PPS may signal tiles_enabled_flag as shown in Table 7 below.

TABLE 7

PPS에서 tiles_enabled_flag의 수정(revision of tile-enabled flag in PPS)Revision of tile-enabled flag in PPS

According to the HEVC standard, tiles_enabled_flag has the following restrictions.

"For all PPSs enabled in the CVS (coded video stream), tiles_enabled_flag must have the same value."

In accordance with the above constraints, the present invention proposes a method of signaling tiles_enabled_flag in the SPS without signaling in the PPS when the layer identifier (nuh_layer_id) value is greater than 0 in order to make the PPSs included in the CVS consistent and simple.

Table 8 is an example of a syntax that describes a method for signaling tiles_enabled_flag in an SPS based on layer identifier (nuh_layer_id) information according to an embodiment of the present invention.

Table 8

The meanings of the syntaxes shown in Table 8 are the same as described above, and thus description of the syntax is omitted here.

Table 9 is another example of a syntax illustrating a method of signaling tiles_enabled_flag based on layer identifier (nuh_layer_id) information according to an embodiment of the present invention.

Table 9

Referring to Table 9, when tiles_enabled_flag has a value of 1, it means that all pictures referring to the corresponding PPS include two or more tiles. When tiles_enabled_flag has a value of 0, it means that all pictures referring to the corresponding PPS include only one tile. If the tiles_enabled_flag value is not signaled, the tiles_enabled_flag value is inferred as the sps_tiles_enabled_flag value.

At this time, the tiles_enabled_flag value should have the same value for all PPSs activated in a specific layer of the CVS.

VPS에서 타일 정보(Tile information in VPS)Tile information in VPS

Some CVSs may be complicated to decode in real time in some decoders. If the tile related information is delivered to the decoder, the decoder can know in advance whether it can decode the CVS. That is, tile related information signaled in the VPS may be useful for session negotiation. In addition, if pictures in a particular layer have the same tile setting, that is, in the form of the same default tile, it may not be necessary to signal tile related information in every PPS.

Therefore, in the present invention, it is proposed to describe default tile related information or information related to the maximum and minimum number of tiles in VPS.

Example 1

Table 10 is an example of a syntax that describes a method for signaling tile related information in a VPS according to an embodiment of the present invention.

Table 10

Referring to Table 10, when tiles_not_in_use_flag has a value of 1, it means that all the pictures of the CVS include only one tile. When tiles_not_in_use_flag has a value of 0, it means that a picture including two or more tiles among pictures referring to the corresponding VPS may exist.

When default_tile_info_flag [i] has a value of 1, it may mean that the picture of the i-th layer has a default tile setting. When default_tile_info_flag [i] has a value of 0, it indicates that a picture of the i-th layer may or may not have a default tile setting.

A value of num_tile_columns_minus1 [i] plus 1 represents the number of tile columns of a partitioning picture of the i-th layer. If num_tile_columns_minus1 [i] is not signaled, num_tile_columns_minus1 [i] is assumed to be 0.

A value of num_tile_rows_minus1 [i] plus 1 represents the number of tile rows dividing a picture of the i-th layer. If num_tile_rows_minus1 [i] is not signaled, num_tile_rows_minus1 [i] is assumed to be zero.

When uniform_spacing_flag [i] has a value of 1, it means that a tile column and a tile row are positioned at regular intervals in a picture of the i-th layer. If Uniform_spacing_flag [i] has a value of 0, it means that the tile column and the tile row are not located at regular intervals in the picture of the i-th layer, where column_width_minus1 of each tile [i] [j] and row_height_minus1 [i] [j] may be used to signal the width of the column and the height of the row. If the uniform_spacing_flag value does not exist, the uniform_spacing_flag value may be assumed to be 1.

column_width_minus1 [i] [j] The value of plus 1 describes the width of the column of the j-th tile of the i-th layer in units of coding tree blocks.

row_height_minus1 [i] [j] plus 1 indicates the height of the row of the j-th tile of the i-th layer in units of coding tree blocks.

When loop_filter_across_tiles_enabled_flag [i] has a value of 1, it indicates that in-loop filtering is performed on the tile boundary portion in the picture of the i-th layer. When loop_filter_across_tiles_enabled_flag [i] has a value of 0, it indicates that in-loop filtering is not performed on the tile boundary portion of the picture of the i-th layer. In-loop filtering operations include a deblocking filter and an adaptive offset filter operation. If the loop_filter_across_tiles_enabled_flag value is not signaled, the loop_filter_across_tiles_enabled_flag value is assumed to be 1.

As shown in Table 10, instead of sending tile related information in the VPS, the same information as above may be signaled in a supplemental enhancement information (SEI) message.

In addition, the PPS may be modified to update only tile-related information signaled by the PPS when necessary.

Table 11 is an example of a syntax that describes a method of updating tile related information signaled by a PPS according to an embodiment of the present invention only when necessary.

Table 11

Referring to Table 11, when tiles_enabled_flag has a value of 1, it means that all pictures referring to the corresponding PPS include two or more tiles. When tiles_enabled_flag has a value of 0, it means that all pictures referring to the PPS include only one tile. If the tiles_enabled_flag value is not signaled, the tiles_enabled_flag value is inferred to a value of zero.

When update_tiles_info_flag has a value of 1, it indicates that tile related information of pictures referring to the corresponding PPS is updated. When update_tiles_info_flag has a value of 0, it indicates that tile related information of pictures referring to the corresponding PPS is not updated.

Example 2

Table 12 is another example of a syntax that describes a method of signaling tile related information in a VPS according to an embodiment of the present invention.

Table 12

The update mechanism of the PPS can be applied only to the number of tiles and the loop filter signaling, as shown in Table 13 below.

Table 13

The semantics of the syntaxes shown in Tables 12 and 13 have the same meanings as the syntaxes described in Tables 10 and 11 of the first embodiment.

Example 3

Table 14 is another example of a syntax illustrating a method of signaling tile related information in a VPS according to an embodiment of the present invention.

Table 14

The semantics of the syntaxes shown in Table 14 are the same as the syntaxes described in Tables 10 and 11 of the first embodiment.

Example 4

Table 15 is another example of a syntax illustrating a method of signaling tile related information in a VPS according to an embodiment of the present invention.

Table 15

Referring to Table 15, when min_max_tile_info_flag [i] has a value of 1, it means that the maximum tile number and the minimum tile number of the picture of the i-th layer included in the bitstream are signaled. If min_max_tile_info_flag [i] has a value of 0, it means that the maximum tile number and the minimum tile number of the picture of the i-th layer included in the bitstream are not signaled.

The value of max_num_tile_columns_minus1 [i] plus 1 represents the maximum number of tile columns of a partitioning picture of the i-th layer. If max_num_tile_columns_minus1 [i] is not signaled, max_num_tile_columns_minus1 [i] is assumed to be zero.

The value of min_num_tile_columns_minus1 [i] plus 1 represents the minimum number of tile columns of a partitioning picture of the i-th layer. If min_num_tile_columns_minus1 [i] is not signaled, min_num_tile_columns_minus1 [i] is assumed to be zero.

The value of max_num_tile_rows_minus1 [i] plus 1 represents the maximum number of tile rows dividing a picture of the i-th layer. If max_num_tile_rows_minus1 [i] is not signaled, max_num_tile_rows_minus1 [i] is assumed to be zero.

The value of min_num_tile_rows_minus1 [i] plus 1 represents the minimum number of tile rows of partitioning pictures of the i-th layer. If min_num_tile_rows_minus1 [i] is not signaled, min_num_tile_rows_minus1 [i] is assumed to be zero.

Example 5

Table 16 is another example of a syntax illustrating a method of signaling tile related information in a VPS according to an embodiment of the present invention.

Table 16

Referring to Table 16, when max_tile_info_flag [i] has a value of 1, it means that the maximum number of tiles of the picture of the i-th layer included in the bitstream is signaled. When max_tile_info_flag [i] has a value of 0, it means that the maximum number of tiles of the picture of the i-th layer included in the bitstream is not signaled.

When min_tile_info_flag [i] has a value of 1, it means that the minimum number of tiles of the picture of the i-th layer included in the bitstream is signaled. If min_tile_info_flag [i] has a value of 0, it means that the minimum number of tiles of the picture of the i-th layer included in the bitstream is not signaled.

The fourth embodiment and the fifth embodiment may be signaled in vps_vui ().

SPS에서 타일 정보(Tile information in SPS)Tile information in SPS

In general, the tile settings of pictures in a particular layer will be the same, so other ways of describing tile related information can be described in the SPS. If the tile related information is not modified in the VPS, the SPS may be modified as shown in Table 17 below.

Table 17 is an example of a syntax that describes a method for signaling tile related information in an SPS according to an embodiment of the present invention.

Table 17

The semantics of the syntaxes described in Table 17 are the same as the syntaxes for signaling tile information in the VPS described above, and thus description thereof is omitted here.

존재하지 않는 타일 영역에 대한 기술(Description of not-present tile sets)Description of not-present tile sets

Currently independently decodable regions (ie tile regions or tile sets) in a CVS can be described in “inter-layer constrained tile sets SEI messages” and “motion-constrained SEI messages”. Portions outside the described region (regions other than independently decodable regions in the CVS) may be skipped without sending encoded data for that portion.

However, as shown in FIG. 4, there may be a tile set later intentionally removed and empty. This tile area may later be filled by a device present in the content delivery path (used for advertising boxes, etc.). To this end, it would be helpful if the decoder could know which tile regions (ie, independently decodable regions) were removed.

The current "inter-layer constrained tile sets SEI messages" describe only the independently decodable region, and does not describe which region is removed from the transmission path.

Accordingly, the present invention provides a method for describing information about a tile region so that a decodable region and a removed region within a picture can be identified.

For example, a flag may be added to each defined tile area to indicate whether a tile area in a picture exists.

Table 18 is an example of syntax illustrating a method of using a flag indicating whether a tile area exists according to an embodiment of the present invention.

Table 18

Referring to Table 18, when present_flag [i] is a value of 1, it means that a recognized tile set exists in the CVS. If present_flag [i] is a value of 0, it means that there is no tile region recognized in the CVS.

As another example, you can create a new SEI message indicating whether each tile region exists in CVS. In this case, the “inter-layer constrained tile sets SEI message” does not need to be modified.

표현 포맷의 수정(Revision of representation formats)Revision of representation formats

Hereinafter, the present invention proposes a method for improving the expression of the "representation format" described in the VPS and SPS.

Table 19 is an example of a syntax that describes a method for signaling a representation format according to an embodiment of the present invention.

Table 19

Referring to Table 19, vps_rep_format_idx [i] represents an index of a list of rep_format () syntax applied to the i-th layer.

The syntax of Table 19 may be modified as shown in Table 20 below. When modified as shown in Table 20, when the VPS parsing process in the decoder or the middle box is vps_num_rep_formats_minus1 = 0, there is an advantage that it is not necessary to signal the “for” loop.

Table 20 is another example of a syntax illustrating a method of signaling a representation format according to an embodiment of the present invention.

Table 20

When one picture size or bit-depth is changed for only a few layers, information about a representation format may be signaled as shown in Table 21 below to prevent signaling of redundant information.

Table 21 shows an example of a representation format syntax for improving signaling of duplicate information according to an embodiment of the present invention.

Table 21

Referring to Table 21, when chroma_size_vps_present_flag has a value of 1, it indicates that information related to chroma format and picture size is included in the syntax. When chroma_size_vps_present_flag has a value of 0, it means that the chroma format and the picture size related information refer to the previously signaled rep_format (). The value of chroma_size_vps_present_flag of the first rep_format () must be 1.

When bit_depth_vps_present_flag has a value of 1, it indicates that bit-depth related information is included in the syntax. When bit_depth_vps_present_flag has a value of 0, it means that bit-depth related information refers to previously signaled rep_format (). The value of bit_depth_vps_present_flag of the first rep_format () must be 1.

When one picture size is different for each layer but the color difference format and the bit depth are not different for each layer, information about a representation format may be signaled as shown in Table 22 below to prevent signaling of redundant information.

Table 22 is another example showing a representation format syntax for improving signaling of redundant information according to an embodiment of the present invention.

Table 22

Referring to Table 22, when depth_chroma_vps_present_flag has a value of 1, it indicates that information related to chroma format and bit-depth is included in the syntax. When the depth_chroma_vps_present_flag has a value of 0, it means that the chroma format and the bit-depth related information refer to the previously signaled rep_format (). In this case, previously signaled rep_format () may mean rep_format () applied to a layer immediately below the layer to which the current rep_format () is applied. The value of depth_chroma_vps_present_flag of the first rep_format () must be 1.

In addition, in SPS, update_re_format_flag is replaced with update_bit_depth_flag indicating that update_chroma_size_flag and bit-depth related update information exist, indicating that update information related to the chroma format and picture size exists, as shown in Table 23 below. It can also be.

Table 23 is an example of a syntax that describes a method for signaling chrominance format, picture size, and bit depth related update information in an SPS according to an embodiment of the present invention.

Table 23

Referring to Table 23, when update_chroma_size_flag has a value of 1, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples are signaled in the SPS, and all layers in which the nuh_layer_id value referring to the SPS is greater than 0 use the signaled values. . At this time, a layer whose nuh_layer_id value is greater than 0 does not use chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples related values signaled in the VPS.

If update_chroma_size_flag has a value of 0, it indicates that chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples values are not signaled in the SPS, and that all layers referring to that SPS are signaled in the VPS: chroma_format_idc, separate_colour_ight_flag, pic_colour_plane_flag_information, do. If update_chroma_size_flag is not signaled, the update_chroma_size_flag value is assumed to be 1.

When a current picture having a value of nuh_layer_id greater than 0 (nuh_layer_id = layerIdCurr> 0) refers to a specific SPS, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples may be considered or restricted to the following values.

When the nuh_layer_id value of the activated SPS is 0, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, pic_height_in_luma_samples values are vps_ref_format_idx [j] -th rep_format () of chroma_format_id_fla_pic_height_flag_picma_flag_pic_plane_flag In this case, j is LayerIdxInVps [layerIdCurr], and chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples values signaled by the activated SPS are ignored.

When an active non-base layer refers to an SPS that is also used in the base layer, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, pic_height_in_luma_samples values are inferred from the VPS, where the SPS has a nuh_layer_id value of zero. In the case of an activated base layer, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, and pic_height_in_luma_samples values signaled in the activated SPS are applied.

If the nuh_layer_id value of the activated SPS is greater than 0, the following applies.

If the value of update_chroma_size_flag is 0, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, pic_height_in_luma_samples values are vsp_ref_format_idx [j] -th rep_format () of chroma_format_idc, separate_colour_fla_in_flag_information_flag. In this case, j is LayerIdxInVps [layerIdCurr].

If the value of update_chroma_size_flag is 1, chroma_format_idc, separate_colour_plane_flag, pic_width_in_luma_samples, pic_height_in_luma_samples values should be chroma_format_idc, separate_color_flag, separate_colour_plane_flag, separate_color_height_in_lu__s_in_lus In this case, j is LayerIdxInVps [layerIdCurr].

When update_bit_depth_flag has a value of 1, bit_depth_luma_minus8 and bit_depth_chroma_minus8 are signaled in the SPS, and all layers whose nuh_layer_id value referring to the SPS is greater than 0 use the signaled values. At this time, in a layer having a nuh_layer_id value greater than 0, values related to bit_depth_luma_minus8 and bit_depth_chroma_minus8 signaled by the VPS are not used.

When update_bit_depth_flag has a value of 0, it indicates that bit_depth_luma_minus8 and bit_depth_chroma_minus8 values are not signaled to the SPS, and all layers referring to the SPS use bit_depth_luma_minus8 and bit_depth_chroma_minus8 values that are signaled by the VPS. If update_bit_depth_flag is not signaled, the update_bit_depth_flag value is assumed to be 1.

When the current picture having a value of nuh_layer_id greater than 0 (nuh_layer_id = layerIdCurr> 0) refers to a specific SPS, bit_depth_luma_minus8 and bit_depth_chroma_minus8 may be regarded or restricted as the following values.

If the nuh_layer_id value of the activated SPS is 0, the bit_depth_luma_minus8 and bit_depth_chroma_minus8 values are regarded as bit_depth_luma_minus8 and bit_depth_chroma_minus8 of vps_ref_format_idx [j] -th rep_format () of the activated VPS. At this time, j is LayerIdxInVps [layerIdCurr], and bit_depth_luma_minus8 and bit_depth_chroma_minus8 values signaled by the activated SPS are ignored.

When an active non-base layer refers to an SPS that is also used in the base layer, the bit_depth_luma_minus8 and bit_depth_chroma_minus8 values are inferred from the VPS, where the SPS has a nuh_layer_id value of zero. In the case of the activated base layer, the bit_depth_luma_minus8 and bit_depth_chroma_minus8 values signaled in the activated SPS are applied.

If the update_bit_depth_flag value is 0, the bit_depth_luma_minus8 and bit_depth_chroma_minus8 values are considered bit_depth_luma_minus8 and bit_depth_chroma_minus8 of vps_ref_format_idx [j] -th rep_format () of the activated VPS. In this case, j is LayerIdxInVps [layerIdCurr].

If update_bit_depth_flag is 1, bit_depth_luma_minus8 and bit_depth_chroma_minus8 should be less than or equal to bit_depth_luma_minus8 of vps_ref_format_idx [j] -th rep_format () of the activated VPS. In this case, j is LayerIdxInVps [layerIdCurr].

VPS extension에서의 sps_max_sub_layers_minus1 시그널링 관련Sps_max_sub_layers_minus1 signaling related in VPS extension

The number of temporal sub-layers per layer included in the bitstream may be signaled in the VPS extension.

Table 24 is an example of a syntax that describes a method for signaling the number of maximum temporal sub-layers according to an embodiment of the present invention.

Table 24

Referring to Table 24, when vps_sub_layers_max_minus_present_flag is 1, it indicates that the sub_layer_vps_max_minus1 [i] value is signaled, and when vps_sub_layers_max_minus_present_flag is 0, it indicates that the sub_layer_vps_max_minus1 [i] value is not signaled.

sub_layers_vps_max_minus1 [i] +1 indicates the maximum number of temporal sub-layers present in the layer whose nuh_layer_id value is layer_id_in_nuh [i]. The value of sub_layers_vps_max_minus1 [i] has a range from 0 to vps_max_sub_layers_minus1, and if the value of sub_layer_vps_max_minus1 [i] is not signaled, the value of sub_layers_vps_max_minus1 [i] is inferred as the value of vps_max_sub_layers_minus1.

On the other hand, in the SPS, when the layer referring to the SPS has a nuh_layer_id value of 0, sps_max_sub_layers_minus1 for indicating the maximum number of temporal sub-layers that the layer can have is signaled. However, the SPS does not separately signal sps_max_sub_layers_minus1 to indicate the maximum number of temporal sub-layers that the layer may have when the layer referring to the SPS has a nuh_layer_id value greater than zero. In this case, the value of vps_max_sub_layers_minus1 + 1, which is the number of temporal sub-layers present in the entire bitstream, is determined, not the number of temporal sub-layers of the corresponding layer.

However, as described above, when signaling the maximum number of temporal sub-layers per layer in the VPS extension, it is clear that the sps_max_sub_layers_minus1 value when the nuh_layer_id value is greater than 0 is determined as the sub_layers_vps_max_minus1 [i] value as follows. can do.

sps_max_sub_layers_minus1 + 1 indicates the maximum number of temporal sub-layers that the layer can have when the layer referring to the SPS has nuh_layer_id greater than zero. sps_max_sub_layers_minus1 has a value between 0 and 6. If sps_max_sub_layers_minus1 is not signaled, the sps_max_sub_layers_minus1 value is inferred to be equal to the sub_layers_vps_max_minus1 [i] value of the i-th layer whose nuh_layer_id value is layer_id_in_nuh_ [i].

VPS에서의 temporal_id_nesting_flag 시그널링Temporal_id_nesting_flag signaling in VPS

The vps_temporal_id_nesting_flag signaled in the VPS is used to indicate that switching-up of the temporal sublayer is possible for all layers of the bitstream. That is, when the value of vps_max_sub_layers_minus1 is greater than 0, the value of vps_temporal_id_nesting_flag indicates whether additional inter prediction is restricted for the CVS (coded video bitstream) referring to the corresponding VPS. If the value of vps_max_sub_layers_minus1 is 0, vps_temporal_id_nesting_flag must have a value of 1.

However, it may also be useful to know whether a decoder or bitstream extractor can switch up layer by layer without analyzing the SPS. Accordingly, a method of signaling temporal_id_nesting_flag indicating whether switching up is possible for each layer in the VPS is proposed as shown in Table 25 below.

Table 25 is an example of a syntax illustrating a method of signaling a flag indicating whether switching up is possible for each layer according to an embodiment of the present invention.

Table 25

Referring to Table 25, when the value of vps_layer_temporal_id_nesting_present_flag is 1, it indicates that vps_layer_temporal_id_nesting_flag [i] exists. If the value of vps_layer_temporal_id_nesting_present_flag is 0, this indicates that vps_layer_temporal_id_nesting_flag [i] is not signaled.

vps_layer_temporal_id_nesting_flag [i] indicates whether inter-screen prediction is additionally restricted to the picture of the i-th layer when sub_layers_vps_max_minus1 [i] is greater than zero. When sub_layers_vps_max_minus [i] is 0, vps_layer_temporal_id_nesting_flag [i] must have a value of 1. If vps_layer_temporal_id_nesting_flag [i] is not signaled, it is inferred that vps_layer_temporal_id_nesting_flag [i] is equal to the vps_temporal_id_nesting_flag value.

In addition, the semantics of sps_temporal_id_nesting_flag signaled in the SPS may be modified as follows.

sps_temporal_id_nesting_flag indicates whether additional inter prediction is restricted to CVS (coded video stream) referring to the SPS when sps_max_sub_layers_minus1 is greater than zero.

When the vps_temporal_id_nesting_flag value is 1, the sps_temporal_id_nesting_flag value must be 1. If sps_max_sub_layers_minus1 is 0, the sps_temporal_id_nesting_flag value must be 1. If the sps_temporal_id_nesting_flag value is not signaled, it is inferred that the sps_temporal_id_nesting_flag value is the same as the vps_layer_temporal_id_nesting_flag [i] value of the i-th layer whose nuh_layer_id value is layer_id_in_nuh [i].

The method of FIG. 5 may be performed by the image decoding apparatus (more specifically, the entropy decoding unit) of FIG. 2 described above. In the present embodiment, it is described as being performed by the decoding apparatus for convenience of explanation, but the reverse process may be performed by the encoding apparatus.

Referring to FIG. 5, the decoding apparatus obtains information indicating whether tile related information exists (S500).

The decoding apparatus may receive a scalable bitstream and entropy decode it to obtain information indicating whether tile related information is present.

The information indicating whether the tile related information exists may be information indicating whether a picture including two or more tiles among the pictures in the layer exists as described above.

For example, when there is a picture including two or more tiles among the pictures in the layer, information indicating whether tile related information exists may be set as tile related information. On the other hand, when there is no picture including two or more tiles among the pictures in the layer, that is, when all the pictures in the layer include only one tile, the information indicating whether the tile related information exists is related to the tile The information may be set to no present.

The decoding apparatus obtains tile related information based on information indicating whether tile related information exists (S510).

If it is indicated that the tile related information exists in the bitstream, the decoding apparatus may obtain the entropy decoding of the tile related information.

The tile related information may be information indicating whether the position of the tile existing in the picture of the current layer corresponds to the position of the tile existing in the picture of the reference layer referenced by the current layer. For example, as described above, the tile related information may be tile_boundaries_aligned_flag.

Information indicating whether the tile related information exists and the tile related information may be transmitted from the encoder through the VPS, PPS, SPS and the like.

The process of acquiring the tile related information based on the information indicating whether the tile related information exists according to the above-described embodiment of the present invention may be performed as in the syntaxes described in Tables 1 to 7, or It is also applicable to several combinations of these.

The method of FIG. 6 may be performed by the image decoding apparatus (more specifically, the entropy decoding unit) of FIG. 2 described above. In the present embodiment, it is described as being performed by the decoding apparatus for convenience of explanation, but the reverse process may be performed by the encoding apparatus.

Referring to FIG. 6, the decoding apparatus obtains information indicating whether color information related to chroma format and bit depth related information exist (S600).

The decoding apparatus may receive a scalable bitstream and entropy decode it to obtain information indicating whether color difference format related information and bit depth related information exist.

Information indicating whether the color difference format related information and the bit depth related information exist has been described with reference to Tables 19 to 23, and may be, for example, rep_format_idx_present_flag, depth_chroma_vps_present_flag, chroma_size_vps_present_flag, and bit_depth_vps_present_flag.

The decoding apparatus obtains the color difference format related information and the bit depth related information based on the information indicating whether the color difference format related information and the bit depth related information exist.

If it is indicated that color difference format related information and bit depth related information exist in the bitstream, the decoding apparatus may obtain the entropy decoding by using the color difference format related information and the bit depth related information.

The color difference format related information is information about color difference and luma sampling, and there are monochrome sampling, 4: 2: 0 sampling, 4: 2: 2 sampling, and 4: 4: 4 sampling color difference formats.

Motochrome sampling refers to a sample array consisting only of luma arrays. 4: 2: 0 sampling means that each of the two color difference arrays is half the height and half the width of the luma array. 4: 2: 2 sampling means that each of the two chroma arrays has a height and a half width of the luma array. 4: 4: 4 Sampling means that each of the two color difference arrays is equal to the height and width of the luma array, or treated as monochrome sampling.

If it is indicated that color difference format related information and bit depth related information in the bitstream do not exist, the color difference format related information refers to previously signaled color difference format related information, and the bit depth related information is related to the previously signaled bit depth related information. You can refer to the information.

The information indicating whether the color difference format related information and the bit depth related information exist, the color difference format related information, and the bit depth related information include a rep_format () which is a syntax for describing information related to VPS, PPS, SPS, and expression format. Can be transmitted from the encoder.

The process of acquiring the color difference format related information and the bit depth related information based on the information indicating whether the color difference format related information and the bit depth related information exist according to the above-described embodiments of the present invention is performed through Tables 19 to 23. Since it has been described, a detailed description thereof will be omitted here.

The method according to the present invention described above may be stored in a computer-readable recording medium that is produced as a program for execution on a computer, and examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape , Floppy disks, optical data storage devices, and the like, and also include those implemented in the form of carrier waves (eg, transmission over the Internet).

The computer readable recording medium can be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the method can be easily inferred by programmers in the art to which the present invention belongs.

In the above embodiments, the methods are described based on a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and certain steps may occur in a different order or at the same time than other steps described above. Can be. Also, one of ordinary skill in the art appreciates that the steps shown in the flowcharts are not exclusive, that other steps may be included, or that one or more steps in the flowcharts may be deleted without affecting the scope of the present invention. I can understand.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

In the video decoding method that supports a plurality of layers,

Obtaining information indicating whether tile related information exists; And

Acquiring the tile related information based on information indicating whether the tile related information exists;

The tile related information is information indicating whether a position of a tile existing in a picture of a current layer corresponds to a position of a tile existing in a picture of a reference layer referenced by the current layer. Way.
The method of claim 1,

The information indicating whether the tile related information exists,

And determining whether the tile related information exists according to whether a picture including two or more tiles among the pictures in the layer exists.
The method of claim 2,

And when there is a picture including two or more tiles among the pictures in the layer, information indicating whether the tile related information exists indicates that the tile related information exists.
The method of claim 2,

If there is no picture including two or more tiles among the pictures in the layer, the information indicating whether the tile related information exists indicates that the tile related information does not exist. .
In the video decoding method that supports a plurality of layers,

Obtaining information indicating whether color information related to chroma format and bit depth related information exist; And

And obtaining the color difference format related information and the bit depth related information based on the information indicating whether the color difference format related information and the bit depth related information exist.
The method of claim 5,

If the color difference format related information does not exist,

And the chrominance format related information refers to previously signaled chrominance format related information.
The method of claim 5,

If the bit depth related information does not exist,

The bit depth related information refers to previously signaled bit depth related information.
In the video decoding apparatus supporting a plurality of layers,

Obtaining information indicating whether tile related information exists,

An entropy decoder configured to obtain the tile related information based on information indicating whether the tile related information exists;

The tile related information is information indicating whether a position of a tile existing in a picture of a current layer corresponds to a position of a tile existing in a picture of a reference layer referenced by the current layer. Device.
In the video decoding apparatus supporting a plurality of layers,

Acquires information indicating whether chroma-format information and bit-depth-related information exist;

And an entropy decoding unit configured to obtain the color difference format related information and the bit depth related information based on the information indicating whether the color difference format related information and the bit depth related information exist.