KR20200081179A - Method and apparatus for picture splitting for parallel processing - Google Patents

Abstract

The present disclosure discloses a method and device for dividing a picture for parallel processing. According to one aspect of an embodiment of the present invention, a method for composing one picture comprises the steps of: dividing one picture into tiles; setting information on the divided tiles as a picture level header; setting a plurality of tiles among the divided tiles as one tile group; setting information on the tile group as a tile group header; and configuring a network adaptive layer (NAL) unit by including the tile group and the tile group header.

Description

Picture splitting method and apparatus for parallel processing {METHOD AND APPARATUS FOR PICTURE SPLITTING FOR PARALLEL PROCESSING}

The present invention relates to a picture segmentation method and apparatus for parallel processing.

The content described in this section merely provides background information for the present invention and does not constitute a prior art.

Mobile devices such as smartphones and tablet PCs, and screen resolutions of digital TVs are increasing, and display devices are gradually increasing. In order to support this, high-definition video must be transmitted quickly. Fortunately, the speed of communication is increasing, and image compression techniques for providing high-quality video are also being developed. In addition, a parallelization technique has been developed for use in compressing and restoring images in order to service high-quality video. The parallelization technology enables simultaneous processing of a large amount of computation by using multiple processors at the same time. However, data to be processed in parallel should not affect each other.

An image is composed of a plurality of pictures, and each picture is divided into a plurality of slices or tiles and compressed. At this time, how each picture is divided and how information about the divided picture is transmitted affects parallelization of image compression and reconstruction. That is, depending on whether or not the divided slice/tile has a common characteristic, it may be a problem because it may affect parallel processing of image compression and reconstruction.

The present embodiment has a main purpose in a method of dividing a picture to provide parallel processing and a method of providing information about the divided picture.

According to an aspect of the present embodiment, a method of configuring a single picture includes: dividing the single picture into tiles, setting information about the divided tiles as a picture level header, and a plurality of the divided tiles Setting up one tile as one tile group, setting information about the tile group as a tile group header, and configuring the tile group and the tile group header as a network adaptive layer (NAL) unit It includes.

According to another aspect of the present embodiment, the video encoding apparatus constituting one picture includes a block dividing unit dividing the one picture into tiles, and information on the divided tile as a picture level header and the segmented tiles Includes an encoder configured to configure a plurality of tiles as one tile group, information about the tile group as a tile group header, and include the tile group and the tile group header as a network adaptive layer (NAL) unit. .

As described above, according to the present embodiment, the divided pictures can be processed in parallel, and encoding and decoding can be accelerated.

1 is an exemplary block diagram of an image encoding apparatus capable of implementing the techniques of the present disclosure.
2 is an exemplary diagram of block division using a QTBT structure.
3 is an exemplary diagram for a plurality of intra prediction modes.
4 is an exemplary block diagram of an image decoding apparatus capable of implementing the techniques of the present disclosure.
5 is a diagram showing an example of a slice constituting one picture.
6 is a view showing an example of a tile constituting one picture.
7 is a diagram illustrating an example of MCTS included in one picture.
8 is a diagram illustrating an NAL unit of a slice segment as an example.
9 is a diagram illustrating an example of a tile group according to the present disclosure.
10 is a diagram illustrating an NAL unit of a tile group according to the present disclosure as an example.
11 is a diagram illustrating an example of a tile group in a picture and a NAL unit of the tile group according to the present disclosure.
12 is a diagram specifically showing a tile group in a picture and a NAL unit of the tile group according to another embodiment of the present disclosure.
13 is a diagram illustrating that some regions refer to other regions in a tile group during inter prediction according to an embodiment of the present disclosure.
14 is a flowchart illustrating inter prediction according to an embodiment of the present disclosure.
15 is a flowchart illustrating a method of a video encoding apparatus configuring one picture according to the present disclosure.
16 is a flowchart illustrating a method for a video decoding apparatus to determine a picture composed of one according to the present disclosure.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible, even if they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. Throughout the specification, when a part is'included' or'equipped' a component, this means that other components may be further included rather than excluded other components unless specifically stated to the contrary. . In addition,'… Terms such as "unit" and "module" mean a unit that processes at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software.

1 is an exemplary block diagram of an image encoding apparatus capable of implementing the techniques of the present disclosure.

The image encoding apparatus includes a block division unit 110, a prediction unit 120, a subtractor 130, a transformation unit 140, a quantization unit 145, an encoding unit 150, an inverse quantization unit 160, and an inverse transformation unit ( 165), an adder 170, a filter unit 180 and a memory 190. In the video encoding apparatus, each component may be implemented by a hardware chip, or may be implemented by software, and one or more microprocessors may be implemented to execute functions of software corresponding to each component.

One image (video) is composed of a plurality of pictures. Each picture is divided into a plurality of regions, and encoding is performed for each region. For example, one picture is divided into one or more slices and/or tiles, and each slice or tile is divided into one or more coding tree units (CTUs). And each CTU is divided into one or more coding units (CUs) by a tree structure. Information applied to each CU is encoded as the syntax of the CU, and information commonly applied to CUs included in one CTU is encoded as the syntax of the CTU. In addition, information commonly applied to all blocks in one tile is encoded as the syntax of a tile or encoded as a syntax of a tile group in which a plurality of tiles are collected, and information applied to all blocks constituting one picture is It is encoded in a picture parameter set (PPS) or a picture header. Furthermore, information commonly referred to by a plurality of pictures is encoded in a sequence parameter set (SPS). In addition, information commonly referenced by one or more SPSs is encoded in a video parameter set (VPS).

The block dividing unit 110 determines the size of a coding tree unit (CTU). Information about the size of the CTU (CTU size) is encoded as a syntax of the SPS or PPS and transmitted to the video decoding apparatus. The block dividing unit 110 divides each picture constituting an image into a plurality of coding tree units (CTUs) of a determined size, and then recursively uses the CTU using a tree structure. Divide. A leaf node in a tree structure becomes a coding unit (CU), which is a basic unit of encoding. The tree structure includes a quad tree (QuadTree, QT) in which a parent node (or parent node) is divided into four sub-nodes (or child nodes) of the same size, or a binary tree (BinaryTree) in which a parent node is divided into two sub-nodes. , BT), or a ternary tree in which the upper node is divided into three lower nodes in a 1:2:1 ratio, or a structure in which one or more of these QT structures, BT structures, and TT structures are mixed. have. For example, a QTBT (QuadTree plus BinaryTree) structure may be used, or a QTBTTT (QuadTree plus BinaryTree TernaryTree) structure may be used.

2 shows a QTBTTT split tree structure. As shown in FIG. 2, the CTU may first be divided into a QT structure. The quadtree split may be repeated until the size of the splitting block reaches the minimum block size (MinQTSize) of the leaf node allowed in QT. The first flag (QT_split_flag) indicating whether each node of the QT structure is divided into four nodes of a lower layer is encoded by the encoder 150 and signaled to the video decoding apparatus.

If the leaf node of QT is not larger than the maximum block size (MaxBTSize) of the root node allowed by BT, it may be further divided into any one or more of BT structure or TT structure. In the BT structure and/or the TT structure, a plurality of split directions may exist. For example, there may be two directions in which a block of a corresponding node is divided horizontally and a vertically divided direction. As illustrated in FIG. 2, when BTTT splitting is started, a second flag (BTTT_split_flag) indicating whether nodes are split, a flag indicating additional splitting direction (vertical or horizontal) and/or splitting type (Binary or Ternary) The flag indicating) is encoded by the encoding unit 150 and signaled to the video decoding apparatus.

When QTBT is used as another example of a tree structure, there are two types of horizontally dividing a block of a corresponding node into two blocks of the same size (i.e., symmetric horizontal splitting) and a vertically dividing type (i.e., symmetric vertical splitting). Branches can exist. The split flag (split_flag) indicating whether each node of the BT structure is divided into blocks of a lower layer and split type information indicating a split type are encoded by the encoder 150 and transmitted to an image decoding apparatus. On the other hand, there may be further a type of dividing a block of a corresponding node into two blocks having an asymmetric shape. The asymmetric form may include a form of dividing a block of a corresponding node into two rectangular blocks having a size ratio of 1:3, or may include a form of dividing a block of a corresponding node diagonally.

CU may have various sizes according to QTBT or QTBTTT division from CTU. Hereinafter, a block corresponding to a CU (ie, a leaf node of QTBTTT) to be encoded or decoded is referred to as a'current block'.

The prediction unit 120 predicts the current block to generate a prediction block. The prediction unit 120 includes an intra prediction unit 122 and an inter prediction unit 124.

In general, each of the current blocks in a picture can be predictively coded. Prediction of the current block is generally performed using an intra prediction technique (using data from a picture containing the current block) or an inter prediction technique (using data from a picture coded before the picture containing the current block). Can be performed. Inter prediction includes both one-way prediction and two-way prediction.

The intra prediction unit 122 predicts pixels in the current block using pixels (reference pixels) located around the current block in the current picture including the current block. There are a plurality of intra prediction modes according to the prediction direction. For example, as shown in FIG. 3, the plurality of intra prediction modes may include 65 non-directional modes including a planar mode and a DC mode. Peripheral pixels to be used and expressions are defined differently for each prediction mode.

The intra prediction unit 122 may determine an intra prediction mode to be used to encode the current block. In some examples, the intra prediction unit 122 may encode the current block using various intra prediction modes and select an appropriate intra prediction mode to use from the tested modes. For example, the intra prediction unit 122 calculates rate distortion values using rate-distortion analysis for various tested intra prediction modes, and has the best rate distortion characteristics among the tested modes. The intra prediction mode can also be selected.

The intra prediction unit 122 selects one intra prediction mode from among a plurality of intra prediction modes, and predicts a current block by using neighboring pixels (reference pixels) and arithmetic expressions determined according to the selected intra prediction mode. Information on the selected intra prediction mode is encoded by the encoding unit 150 and transmitted to the image decoding apparatus.

The inter prediction unit 124 generates a prediction block for the current block through a motion compensation process. The block most similar to the current block is searched in the reference picture that is encoded and decoded before the current picture, and a predicted block for the current block is generated using the searched block. Then, a motion vector corresponding to displacement between the current block in the current picture and the prediction block in the reference picture is generated. In general, motion estimation is performed on luma components, and motion vectors calculated based on luma components are used for both luma components and chroma components. The motion information including information about the reference picture and motion vector used to predict the current block is encoded by the encoder 150 and transmitted to the video decoding apparatus.

The subtractor 130 subtracts the prediction block generated by the intra prediction unit 122 or the inter prediction unit 124 from the current block to generate a residual block.

The transform unit 140 converts a residual signal in a residual block having pixel values in a spatial domain into a transform coefficient in the frequency domain. The converter 140 may convert residual signals in the residual block by using the size of the current block as a transformation unit, or divide the residual block into a plurality of smaller sub-blocks, and convert the residual signals into sub-block-size transformation units. You can also convert. There may be various ways to divide the residual block into smaller sub-blocks. For example, it may be divided into predefined sub-blocks of the same size, or a quadtree (QT)-based partitioning using a residual block as a root node may be used.

The quantization unit 145 quantizes transform coefficients output from the transform unit 140 and outputs the quantized transform coefficients to the encoder 150.

The encoder 150 generates a bit stream by encoding quantized transform coefficients using an encoding method such as CABAC (Context-based Adaptive Binary Arithmetic Code). Such encoding is typically performed on quantized transform coefficients using one of a plurality of available scan schemes.

In addition, the encoder 150 encodes information such as a CTU size, a QT split flag, a BT split flag, a split direction, and a split type related to block splitting, so that the video decoding apparatus can split blocks in the same way as the video coding apparatus. To make.

Also, the encoding unit 150 encodes information about a prediction type indicating whether the current block is encoded by intra prediction or inter prediction, and intra prediction information (that is, intra prediction mode) according to the prediction type. Information) or inter prediction information (reference picture and motion vector information).

The inverse quantization unit 160 inversely quantizes the quantized transform coefficients output from the quantization unit 145 to generate transform coefficients. The inverse transform unit 165 restores the residual block by transforming transform coefficients output from the inverse quantization unit 160 from the frequency domain to the spatial domain.

The adder 170 restores the current block by adding the reconstructed residual block and the predicted block generated by the predictor 120. The pixels in the reconstructed current block are used as reference pixels when intra prediction of the next block.

The filter unit 180 filters the reconstructed pixels to reduce blocking artifacts, ringing artifacts, and blurring artifacts caused by block-based prediction and transformation/quantization. To perform. The filter unit 180 may include a deblocking filter 182 and a sample adaptive offset (SAO) filter 184.

The deblocking filter 180 filters the boundary between the restored blocks to remove blocking artifacts caused by block-level encoding/decoding, and the SAO filter 184 adds additional deblocking filtered images to the deblocking filter. Filtering is performed. The SAO filter 184 is a filter used to compensate for a difference between a reconstructed pixel and an original pixel caused by lossy coding.

The reconstructed blocks filtered through the deblocking filter 182 and the SAO filter 184 are stored in the memory 190. When all blocks in one picture are reconstructed, the reconstructed picture is used as a reference picture for inter prediction of a block in a picture to be encoded.

4 is an exemplary block diagram of an image decoding apparatus capable of implementing the techniques of the present disclosure.

The image decoding apparatus includes an image reconstructor 400 including a decoder 410, an inverse quantization unit 420, an inverse transform unit 430, a prediction unit 440, an adder 450, and a filter unit 460. And memory 470. Similar to the image encoding apparatus of FIG. 1, the image decoding apparatus may be implemented with each component implemented as a hardware chip, or may be implemented with software and a microprocessor may execute functions of software corresponding to each component.

The decoder 410 decodes the bit stream received from the video encoding apparatus, extracts information related to block partitioning, determines a current block to be decoded, prediction information necessary for restoring the current block, information about a residual signal, and the like. To extract.

The decoder 410 extracts information about the CTU size from a Sequence Parameter Set (SPS) or a Picture Parameter Set (PSP) to determine the size of the CTU, and divides the picture into CTUs of the determined size. Then, the CTU is determined as the top layer of the tree structure, that is, the root node, and the CTU is divided by using the tree structure by extracting the segmentation information for the CTU. For example, when the CTU is split using the QTBTTT structure, first, the first flag (QT_split_flag) related to the splitting of the QT is extracted, and each node is divided into four nodes of a lower layer. And, for the node corresponding to the leaf node of the QT, the second flag (BTTT_split_flag) and split direction (vertical / horizontal) and/or split type (binary / ternary) information related to the split of BTTT are extracted and the corresponding leaf node is BTTT Divide into structures. Through this, each node below the leaf node of QT is recursively divided into a BT or TT structure.

As another example, when a block is divided using a QTBTTT structure, information (eg, a flag) for partitioning is first extracted, and partition type information is extracted when the corresponding block is divided. When the division type is QT, each node is divided into four nodes corresponding to lower layers. If the segmentation type indicates that the QT segmentation is a leaf node (a node in which the QT segmentation no longer occurs) type, that is, segmented by BT or TT, additionally, information about the segmentation direction and segmentation type information that distinguishes whether the structure is a BT or TT structure Is extracted and split into BT or TT structures. As another example, when the CTU is split using the QTBT structure, the first flag (QT_split_flag) related to the division of the QT is extracted, and each node is divided into four nodes of a lower layer. Then, a split flag (split_flag) and split direction information indicating whether or not to be further split by BT is extracted for a node corresponding to a leaf node of QT.

On the other hand, when determining a current block to be decoded through partitioning of a tree structure, the decoder 410 extracts information about a prediction type indicating whether the current block is intra predicted or inter predicted.

When the prediction type information indicates intra prediction, the decoding unit 410 extracts syntax for intra prediction information (intra prediction mode) of the current block.

When the prediction type information indicates inter prediction, the decoder 410 extracts syntax for the inter prediction information, that is, information indicating a motion vector and a reference picture referenced by the motion vector.

Meanwhile, the decoding unit 410 extracts information about quantized transform coefficients of the current block as information about the residual signal.

The inverse quantization unit 420 inverse quantizes the quantized transform coefficients, and the inverse transform unit 430 inversely transforms the inverse quantized transform coefficients from the frequency domain to the spatial domain to restore residual signals to generate a residual block for the current block. .

The prediction unit 440 includes an intra prediction unit 442 and an inter prediction unit 444. The intra prediction unit 442 is activated when intra prediction is a prediction type of the current block, and the inter prediction unit 444 is activated when intra prediction is a prediction type of the current block.

The intra prediction unit 442 determines an intra prediction mode of a current block among a plurality of intra prediction modes from syntax for the intra prediction mode extracted from the decoding unit 410, and determines reference pixels around the current block according to the intra prediction mode. Use to predict the current block.

The inter prediction unit 444 determines a motion vector of a current block and a reference picture referred to by the motion vector using syntax for the intra prediction mode extracted from the decoding unit 410, and uses the motion vector and the reference picture. Predict the current block.

The adder 450 restores the current block by adding the residual block output from the inverse transform unit and the prediction block output from the inter prediction unit or the intra prediction unit. The pixels in the reconstructed current block are used as a reference pixel in intra prediction of a block to be decoded later.

By sequentially reconstructing the current blocks corresponding to the CUs by the image reconstructor 400, a CTU composed of CUs and a picture composed of CTUs are reconstructed.

The filter unit 460 includes a deblocking filter 462 and a SAO filter 464. The deblocking filter 462 deblocks the boundary between the reconstructed blocks in order to remove blocking artifacts caused by block-by-block decoding. The SAO filter 464 performs additional filtering on the reconstructed block after deblocking filtering to compensate for the difference between the reconstructed pixel and the original pixel caused by lossy coding. The reconstructed blocks filtered through the deblocking filter 462 and the SAO filter 464 are stored in the memory 470. When all blocks in one picture are reconstructed, the reconstructed picture is used as a reference picture for inter prediction of a block in a picture to be encoded.

The present disclosure proposes how an image encoding apparatus divides a picture and processes and configures information about the divided picture to process the divided picture in parallel.

Previously, a method of dividing a picture has been briefly described, but will be described in more detail here.

The first way to split a picture is to split the picture into slices. One picture may be composed of one or more slices. One picture is divided into CTU units to enable encoding and decoding. At this time, the one picture may be divided in the order of raster scan.

One slice may be composed of one or more slice segments. There are two types of slice segments: independent slice segments and dependent slice segments (or dependent slice segments). The independent slice segment is not dependent on other slice segments in inter prediction, intra prediction, coding mode and entropy coding, and header information for the independent slice segment exists. On the other hand, the dependent slice segment is dependent on other preceding independent slice segments in inter prediction, intra prediction, coding mode and entropy coding. The dependent slice segment mostly refers to the header information of the independent slice segment to which the dependent slice segment depends, and transmits only part of the header information as separate header information.

5 is a diagram illustrating an example of a slice constituting one picture.

In FIG. 5, one picture is composed of two slices 510 and 520. The first slice 510 is composed of one independent slice segment 512 and two dependent slice segments 514 and 516. The second slice 520 is composed of one independent slice segment. A slice boundary 530 exists between slices. The slice boundary 530 may exist only in the form of a horizontal axis boundary. For reference, as in the second slice 520, one slice may be composed of only independent slice segments.

Tables 1 and 2 below show syntax for slices.

Specifically, [Table 1] shows an example of the PPS. The PPS includes a flag (dependent_slice_segments_enabled_flag) indicating whether a dependent slice segment is included in a picture.

pic_parameter_set_rbsp(　) { pps_pic_parameter_set_id pps_seq_parameter_set_id dependent_slice_segments_enabled_flag … }

[Table 2] below shows an example of header information of a slice segment.

slice_segment_header(　) { first_slice_segment_in_pic_flag if( nal_unit_type >= BLA_W_LP && nal_unit_type <= RSV_IRAP_VCL23) no_output_of_prior_pics_flag slice_pic_parameter_set_id if( !first_slice_segment_in_pic_flag) { if( dependent_slice_segments_enabled_flag) dependent_slice_segment_flag slice_segment_address } if( !dependent_slice_segment_flag) { … } if(tiles_enabled_flag |　| entropy_coding_sync_enabled_flag) { num_entry_point_offsets if( num_entry_point_offsets> 0) { offset_len_minus1 for( i = 0; i <num_entry_point_offsets; i++) entry_point_offset_minus1[　i　] } } … }

The first slice segment in the picture is an independent slice segment. Therefore, in the header information of the slice segment, a flag indicating whether it is the first slice segment (first_slice_segment_in_pic_flag), and a flag indicating whether the slice segment except the first slice segment is an independent slice segment or a dependent slice segment (dependent_slice_segment_flag), and a slice segment A syntax (slice_segment_address) indicating the address of is included.

The second method is to divide a picture into one or more tiles, and group one or more tiles into one tile group. Like a slice, one picture may be composed of one or more tiles and/or tile groups. Can. When one picture is divided into a certain size/unit, the tile refers to a form divided into a plurality of columns and rows based on a certain unit. That is, one tile size is a multiple of a certain unit. For example, when a certain unit is CTU, one picture is divided into CTU units, and a tile is divided into a plurality of columns and rows by one picture in CTU units, and independently encoding and decoding. It is possible. Tiles are not dependent on other tiles in intra prediction and entropy coding. That is, tiles are always independently performed in intra prediction and entropy coding. However, in the case of inter prediction, related information may be transmitted as an encoder issue or in a format such as PPS, tile group header (TGH), and supplemental enhancement information (SEI). Whether to depend on other tiles in the in-loop filtering of tiles can be controlled by flags of PPS and/or TGH.

6 is a view showing an example of a tile constituting one picture.

In FIG. 6, one picture is divided into 3 columns and 3 rows, and is composed of 9 tiles. Tiles constituting one picture may be encoded or decoded in the order of raster scan, and multiple CTUs constituting one tile may be encoded or decoded in the order of raster scan. The number shown in FIG. 6 is a CTU number, and may be in the order of raster scan to be encoded or decoded.

On the other hand, vertically divided tiles have columnar boundaries 610 and 615, and horizontally divided tiles have row boundary 620 and 625. Tiles can be divided equally or individually depending on how you divide them.

[Table 3] below shows an example of syntax for tiles. Specifically, [Table 3] shows an example of the PPS.

pic_parameter_set_rbsp(　) { tiles_enabled_flag if( tiles_enabled_flag) { num_tile_columns_minus1 num_tile_rows_minus1 uniform_spacing_flag if( !uniform_spacing_flag) { for( i = 0; i <num_tile_columns_minus1; i++) column_width_minus1[　I　] for( i = 0; i <num_tile_rows_minus1; i++) row_height_minus1[　I　] } loop_filter_across_tiles_enabled_flag }

The PPS includes a flag (tiles_enabled_flag) indicating on/off of the tile function. When the flag is on, a plurality of syntaxes that can specify the size of a tile are additionally included in the PPS. For example, when the flag is on, syntax (num_tile_columns_minus1) indicating the number of tiles divided based on the vertical axis boundary of the picture minus 1, and the number of tiles divided by the horizontal axis boundary of the picture minus 1 The PPS may include a syntax (num_tile_rows_minus1) indicating, and a flag (uniform_spacing_flag) indicating that tiles are equally divided horizontally and vertically. If the tiles are not evenly divided horizontally and vertically (uniform_spacing_flag = off), the syntax (column_width_minus1) indicating the width for each tile based on the vertical axis boundary and the syntax (the height representing each tile based on the horizontal axis boundary) ( row_height_minus1) may be additionally included in the PPS. Finally, a flag (loop_filter_across_tiles_enabled_flag) indicating whether to execute the loop filter in the inter-tile boundary area may also be included in the PPS.

In addition, a motion constrained tile set (MCTS) describing whether or not to refer to inter-tile inter prediction may be included in a supplemental enhancement information (SEI) message. [Table 4] below shows an example of syntax for MCTS.

temporal_motion_constrained_tile_sets( payloadSize) { mc_all_tiles_exact_sample_value_match_flag each_tile_one_tile_set_flag if( !each_tile_one_tile_set_flag) { limited_tile_set_display_flag num_sets_in_message_minus1 for( i = 0; i <= num_sets_in_message_minus1; i++) { mcts_id[i] if( limited_tile_set_display_flag) display_tile_set_flag[　i　] num_tile_rects_in_set_minus1[　I　] for( j = 0; j <= num_tile_rects_in_set_minus1[　i　]; j++) { top_left_tile_index[　i　][　j　] bottom_right_tile_index[　I　][　j　] } if( !mc_all_tiles_exact_sample_value_match_flag) mc_exact_sample_value_match_flag[　i　] … } } else { … } }

In MCTS, syntax (num_sets_in_message_minus1) indicating the number of tile sets existing in one picture, syntax (num_tile_rects_in_set_minus1) indicating the number of tile rectangles constituting each tile set, and syntax indicating an index of tiles constituting each tile rectangular (top_left_tile_index[i][j], bottom_right_tile_index[i][j]).

7 is a diagram illustrating an example of MCTS included in one picture.

According to FIG. 7, one picture is composed of 48 tiles. The number shown in Fig. 7 indicates a tile index. The one picture includes one tile set 710, and the one tile set includes two tiles rectangular (720, 730). The first tile rectangular (720) includes three tiles, the upper left tile index is 16, and the lower right tile index is 32. The second tile rectangular (730) includes 9 tiles, the upper left tile index is 21, and the lower right tile index is 39. Tiles belonging to one tile set can be referred to each other during inter prediction.

If the MCTS of FIG. 7 is expressed using syntax for the MCTS of [Table 4],

num_sets_in_message_minus1 = 0;

mcts_id[0] = 0;

num_tile_rects_in_set_minus1[0] = 1;

{top_left_tile_index[0][0] = 16, bottom_right_tile_index[0][0] = 32},

{top_left_tile_index[0][1] = 21, bottom_right_tile_index[0][1] = 39};

Can be represented as

Slices are mainly used for parallel processing of pictures, and information related to encoding/decoding is included in a slice header and transmitted. On the other hand, in the case of a tile, there is no separate header, and some of the tile-related information is transmitted in a supplementary enhancement information (SEI) message.

Meanwhile, in the case of slices, the boundary may be determined only on the horizontal axis, but in the case of tiles, the boundary may be determined on the vertical axis as well as the horizontal axis. As the capacity and performance for the current image encoding/decoding device band processing is significantly improved, a row-wise processing method such as a conventional slice may limit parallel processing and quality improvement. Accordingly, the present disclosure proposes various methods of supplementing the characteristics of slices while using tiles for parallel processing and distributed processing. Specifically, the present disclosure proposes how to configure a divided picture into tiles and how to transfer information about tiles.

As described above, the'tile' according to the present disclosure may also be one picture divided into horizontal and vertical axes. However, the tile and/or tile group according to the present disclosure may be a basic unit constituting a Network Abstraction Layer (NAL), and similarly to (or dependent on) another tile and/or group of tiles, or other tiles and/or similar to slice segments. Or it may be independent of the tile group. In addition, the tile/tile group according to the present disclosure may include various information.

8 is a diagram illustrating an NAL unit of a slice segment as an example.

Specifically, the NAL unit is configured in the order of NALU header 810, slice segment header 820, and slice segment data 830. Each slice segment is composed of NAL units, and the NAL units are transmitted in the form of a bit stream.

On the other hand, in the case of a tile, there is no separate header, and some of the information related to the tile is transmitted in a supplementary enhancement information (SEI) message.

Hereinafter, a picture is divided into tiles in order to process the picture in parallel. However, the present disclosure proposes a method of defining tiles having similar characteristics or any number of tiles as a tile group and transmitting information about the tile group.

Specifically, tiles belonging to a tile group may refer to reference pictures to each other during inter prediction, and may also share arbitrary moving vector (MV) information. Alternatively, it is possible to signal whether or not related information is referenced/shared by syntax. In addition, tiles belonging to the tile group may control whether to filter pixel values located at a tile boundary when filtering in-loop through syntax. However, in intra prediction and/or entropy coding, tiles do not refer to each other because they do not correlate. The correlation between tiles belonging to the tile group may be defined as syntax in the tile group header.

9 is a diagram illustrating an example of a tile group according to the present disclosure.

9 shows that one picture is divided into 8 x 6 = 48 tiles. The 48 tiles may be divided into three groups 910, 920, and 930. Each divided tile group may be composed of independent NAL units.

10 is a diagram illustrating an NAL unit of a tile group according to the present disclosure as an example.

Similar to the NAL unit of the slice segment, the NAL unit of the tile group also includes a NALU header 1010, a tile group header 1020, tiles constituting the tile group, that is, a first tile 1030, a second tile ( 1040), the third tile 1050, and the fourth tile 1060. One NAL unit may be composed of one tile group. The tile group header 1020 includes common information of tiles 1030, 1040, 1050, and 1060 included in the tile group. One tile may be composed of a tile header and tile data. Alternatively, one tile may consist of tile data only. Finally, the NAL unit is generated and transmitted as a bit stream.

Meanwhile, when the NAL unit is configured as a tile group, information about the tile group may be previously defined as a NAL type. [Table 5] below shows an example of the NAL type. Here, the intra picture refers to an intra random access point (IRAP) picture, and the inter picture refers to a non-IRAP picture. The NAL type index value in [Table 5] is an example, and the indexes of IRAP and non-IRAP are interchangeable. Also, IRAP picture and/or non-IRAP picture may be further subdivided and defined as one or more NAL types. For example, a non-IRAP picture may be defined as a different NAL type depending on whether it is used as a reference picture.

NAL type index Name for NAL type NAL content NAL type class 0 Intra Coded TG of intra picture VCL One Inter Coded TG of inter picture VCL

11 is a diagram illustrating an example of a tile group in a picture and a NAL unit of the tile group according to the present disclosure.

According to FIG. 11, one picture is divided into 4 x 4 = 16 tiles, and 4 tiles 1110, 1120, 1130, and 1140 are included in one tile group. The tile group may be composed of one NAL unit, and the NAL unit includes a NALU header, a tile group header, a tile header 1112 of the first tile 1110 belonging to the tile group, and tile data 1114. Tile header 1122 of the first tile 1120, tile data 1124, tile header 1132 of the third tile 1130, tile data 1134, tile header 1142 of the fourth tile 1140, And tile data 1144. Alternatively, the tile data may be configured without tile headers for four tiles. At this time, four tiles 1110, 1120, 1130, and 1140 belonging to the tile group may be included in the NAL unit in the order of raster scan in the corresponding picture.

Hereinafter, a picture level header indicating information about one picture, a tile group header indicating information common to tiles belonging to one tile group, and a tile header indicating information on each tile will be described in detail. Here, the picture level header may be composed of one NAL unit separately from the tile group NAL unit. For example, the NAL unit for the picture level header may be defined as a non-VCL NAL type with a NAL type index value of "17".

First, a picture level header indicating information about one picture is described. [Table 6] below shows the syntax of the picture level header.

picture_header_rbsp(　) { picture_header_id … multiple _ tiles_in_pic_flag if( multiple_tiles_in_pic_flag) { num_tile_columns_minus1 num_tile_rows_minus1 uniform_spacing_flag if( !uniform_spacing_flag) { for( i = 0; i <num_tile_columns_minus1; i++) column_width_minus1 [i] for( i = 0; i <num_tile_rows_minus1; i++) row_height_minus1 [i] } } …

The picture level header includes tile (layout) information for one picture in addition to id (picture_header_id) for the picture header. That is, a syntax (multiple_tiles_in_pic_flag) indicating whether the number of tiles in one picture is one or more, and if the number of tiles is large, specific information about the layout of tiles is included in the picture level header. Here, a flag (multiple_tiles_in_pic_flag) indicating whether one picture is divided into a plurality of tiles may be replaced with a flag (single_tile_in_pic_flag) indicating whether one picture is composed of one tile. For example, if the number of tiles in the picture is plural, syntax for the number of tiles divided based on the horizontal axis of the picture (num_tile_columns_minus1), syntax for the number of tiles divided based on the vertical axis of the picture (num_tile_rows_minus1), and the picture The syntax (uniform_spacing_flag) indicating whether or not is equally divided into horizontal and vertical axes is included in the picture level header. If the picture is equally divided into horizontal and vertical axes, it is equally divided into the number of divided tiles, where the basic unit of division may be a multiple of m. Here, m may mean a basic unit that stores a moving vector (MV) in memory. Alternatively, m may be an integer determined by the encoder. At this time, the encoder must pass the value of m to the decoder through the bitstream. In addition, m may be a constant designated identically in the encoder and decoder. In general, when saving an MV, the MVs of both tiles located on the tile boundary are set to one MV, but may not be used. In the present disclosure, m is assumed to be 8 for convenience.

For example, if one picture has a resolution of 3840 x 2160, and the value of m is equally divided into 8, the number of horizontal tiles is 5, and the number of vertical tiles is 3, one tile is 768 x It has a resolution of 720, and one picture is composed of 5 x 3 = 15 tiles. In addition, all 15 tiles have the same size. Here, 768 and 720 are multiples of 8.

On the other hand, as in the HEVC standard, when the value of m is CTU size 64 under the same conditions, the tiles located on the upper two horizontal axes have a resolution of 768 x 704, and the tiles located on the last horizontal axis have a resolution of 768 x 752. . This means that the CTU size is a criterion for division, so that the tiles located on the upper two horizontal axes are divided into multiples of 64, and the tiles located on the last horizontal axis include the remaining area in addition to the tiles located on the upper two horizontal axes.

If the tiles are not evenly divided into horizontal and vertical axes, syntax (column_width_minus1) indicating the width for each tile based on the horizontal axis and syntax (row_height_minus1) indicating the height for each tile based on the horizontal axis are further added to the picture level header. Is included. Even in this case, the basic unit of division may be m.

Hereinafter, a tile group header indicating information common to all tiles belonging to one tile group will be described.

First, one tile group may be configured as one square shape.

[Table 7] below shows the syntax of the tile group header as an example.

tile_group_header(　) { tg_address tg_picture_header_id tg_type … if( multiple_tiles_in_pic_flag) { multiple_tiles_in_tg_flag if( multiple_tiles_in_tg_flag) { if (tg_type != intra) { tg_inter_prediction_across_tiles_enabled_flag tg_temporal_MV_across_tiles_enabled_flag } tg_loop_filter_across_tiles_enabled_flag } } … guard_band_enabled_flag if( guard_band_enabled_flag) { gb_padding_type gb_left_width gb_right_width gb_top_height gb_bottom_hiehgt } … tg_level_idc tg_tier_flag … init_qp_minus32 total_tiles = 0 if( multiple_tiles_in_tg_flag) { tg_num_tile_columns_minus1 tg_num_tile_rows_minus1 total_tiles = (tg_num_tile_columns_minus1 + 1) x (tg_num_tile_rows_minus1 + 1) } for( i = 0; i <total_tiles; i++) { tile_header() tile_data() } … }

The tile group header includes information about the tile group. For example, a syntax (tg_address) indicating the position of a tile group in a picture, a syntax (tg_picture_header_id) indicating an id of a picture header referred to by the tile group, and a syntax (tg_type) indicating a type of the tile group are in the tile group header. Is included. The position of the tile group in the picture may be displayed based on the position of the upper leftmost pixel of the picture. Alternatively, the position of the tile group in the picture may be displayed for each horizontal axis and vertical axis in a multiple form of a basic unit of picture division, or may be displayed as a single value in multiples of 8 in the raster scan order. In addition, the position of the tile group in the picture is indicated by an index for each horizontal axis and vertical axis of a tile at a top left position belonging to the tile group according to a tile layout, or one for a tile at a top left position in a raster scan order. It may be indicated by the index (tile id) of. The syntax (tg_picture_header_id) indicating the id of the picture header referenced by the tile group means an id value defined in the picture header. The type of the tile group means one of the B tile group, the P tile group, and the I tile group.

In addition, the tile group header includes a syntax (multiple_tiles_in_tg_flag) indicating whether a plurality of tiles exist in the tile group, a syntax indicating whether other neighboring tiles are referred to during inter-tile prediction within the tile group (tg_inter_prediction_across_tiles_enabled_flag), and merge Syntax (tg_temporal_MV_across_tiles_enabled_flag) indicating whether to use arbitrary MV (temporal MV) in the reference picture and surrounding tiles in the reference picture in the mode and the Advanced Motion Vector Prediction (AMVP) mode, whether to use the surrounding tile information during in-loop filtering A syntax indicating whether or not (tg_loop_filter_across_tiles_enabled_flag) may be included. Here, in the merge mode and AMVP mode, a syntax indicating whether to use a random MV (temporal MV) in a neighboring tile other than the corresponding tile in a reference picture is enabled after the corresponding function is enabled in a high-level header (eg, SPS) , When it is determined whether to use the corresponding function again at the corresponding tile group level, it may be determined whether to induce a random MV (temporal MV) between tiles. For example, when sps_temporal_mv_enabled_flag is activated and tg_temporal_mv_enabled_flag is activated, a tg_loop_filter_across_tiles_enabled_flag value can be defined. This syntax can be replaced with a syntax (tg_collocated_block_across_tiles_enabled_flag) indicating whether to refer to a neighboring tile when searching a collocated block to take an arbitrary MV (temporal mv). In addition, a syntax indicating whether to refer to a neighboring tile in inter-prediction of inter-tiles in the tile group and a syntax indicating whether to use neighboring tile information in the loop filtering may also be represented as one syntax. When the syntax prevents the reference to the neighboring tiles, the inter-prediction cannot reference the reconstructed pixel values of the neighboring tiles and the MV of the neighboring tiles.

In addition, the tile group header includes a syntax (guard_band_enabled_flag) indicating whether a part of the tile group is padded in a boundary area of the tile group, and a syntax (gb_padding_type) indicating a kind of a value filled in the padding area (for example, a tile group) Boundary pixel value: 0, the actual pixel value of adjacent tiles: 1, the average value taking into account the distance between the border pixel value and the actual pixel value of adjacent tiles: 2), the size of the left/right/top/bottom padding of the tile group The syntax (gb_left_width/ gb_right_width/gb_top_height/gb_bottom_height) may be included. The padding size of each side of the tile group may be displayed as a pixel value based on luma, or may be set in an array form. The syntax (gb_padding_type) indicating the type of the value to be filled in the padding area may be separately designated for each of the left/right/top/bottom padding areas of the tile group. For example, the actual pixel values 1 of adjacent tiles for the left and right padding areas of the tile group may be designated as the copy values 0 of the pixel values of the borders of the tile groups for the upper and lower padding areas. Further, the guard band information may be defined as padding for an input picture (tile group) during encoding, or may be defined as padding for a reference picture (tile group) during decoding.

The tile group header may include a syntax (tg_level_idc) indicating a level value for a tile group, and a syntax (tg_tier_flag) indicating a tier value of the tile group. The syntax is to inform the decoder of the resolution value, memory, etc. of the tile group, which is information required for decoding for each tile group. The two syntaxes can be limited to being transmitted when a separate flag (adaptive_level_tier_enabled_flag) is activated.

The tile group header includes syntax (init_qp_minus32) indicating a value obtained by subtracting 32 from an initial QP (Quantization Parameter) to be applied to a tile group, and syntax indicating a value obtained by subtracting 1 from the number of tiles included in the vertical axis in the tile group. (tg_num_tile_columns_minus1), a syntax (tg_num_tile_rows_minus1) indicating a value obtained by subtracting 1 from the number of tiles included as a horizontal axis reference in the tile group may be further included. Alternatively, the total number of tiles belonging to the tile may be expressed as an id (tile id) of the tile at the bottom-most position belonging to the tile group. The number of tiles included in the tile group may be expressed as one syntax (num_tiles_in_tg_minus1) by integrating on the horizontal and vertical axes. The syntax indicates a value obtained by subtracting 1 from the total number of tiles in the tile group.

This may be applied differently depending on the shape of the tile group. For example, when the tile group is rectangular, it can be expressed as a value obtained by subtracting 1 from the number of tiles included on the horizontal axis and the vertical axis or as an id (tile id) for the tile at the lowest position belonging to the tile group. Conversely, if the tile group type is a tile group defined in the raster scan order of tiles based on the layout of the tiles in the picture, the number of tiles included in the tile group is the total number of tiles in the tile group in the raster scan order. Can be specified as the number minus one.

The syntax indicating whether inter-prediction within a tile group, arbitrary MV (temporal MV), and loop filtering is applied may also be represented as in [Table 8] below.

tile_group_header(　) { … if( multiple_tiles_in_pic_flag) { multiple_tiles_in_tg_flag if( multiple_tiles_in_tg_flag) { all_independent_tiles_flag if( !all_independent_tiles_flag) { if (tg_type != intra) { tg_inter_prediction_across_tiles_disabled_flag tg_temporal_MV_across_tiles_disabled_flag } tg_loop_filter_across_tiles_disabled_flag } } } … }

It is possible to use a syntax (all_independent_tiles_flag) indicating that each tile is independently encoded and decoded while there are multiple tiles in the tile group. That is, it indicates that the syntax can be executed without reference to information on neighboring tiles in inter prediction and/or loop filtering. Specifically, if the value of the syntax is 0, neighboring tile information is used, and whether to reference inter prediction, arbitrary MV (temporal MV), and/or loop filter is specified separately.

Other syntaxes are the same as those described in [Table 7], and descriptions thereof are omitted here.

Among the syntaxes included in the tile group header, syntaxes related to the guard band may be included in any one of a picture level header and supplemental enhancement information (SEI).

Second, a plurality of tile rectangular may be configured as one tile group. In this case, the syntax of the tile group header can be expressed as [Table 9] below.

tile_group_header(　) { tg_picture_header_id tg_type … if( multiple_tiles_in_pic_flag) { multiple_tiles_in_tg_flag if( multiple_tiles_in_tg_flag) { num_tile_rectangulars_in_tg_minus1 for( i = 0; i <num_tile_rectangulars_in_tg_minus1; i++) { topleft_tile_id [i] bottomright_tile_id [i] hor_tiles = floor{(bottomright_tile_id[i]-topleft_tile_id[i]) / (column_width_minus1 + 1)} ver_tiles = bottomright_tile_id[i]-{topleft_tile_id[i] + (column_width_minus1 + 1) x (hor_tiles-1)} + 1 num_tiles[ i] = hor_tiles x ver_tiles } } } … if(multiple_tiles_in_tg_flag) { for( i = 0; i <num_tile_rectangular_minus1; i++) { if (tg_type != intra) { tg_inter_prediction_across_tiles_enabled_flag [i] tg_temporal_MV_across_tiles_enabled_flag [i] } tg_loop_filter_across_tiles_enabled_flag [i] } } … total_tiles = 0 if( tg_multiple_tiles_flag) { for( i = 0; i <num_tile_rectangular_minus1; i++) total_tiles += num_tiles[ i] } for( i = 0; i <total_tiles; i++) { tile_header() tile_data() } … }

The tile group header includes information about a plurality of tile rectangles. For example, the tile group header may include a syntax (num_tile_rectangular_minus1) indicating the number of tile rectangles included in the tile group, and a syntax (topleft_tile_id/bottomright_tile_id) indicating the tile upper and lower right tile id values of the tile rectangular. A syntax (tg_inter_prediction_across_tiles_enabled_flag[i]) indicating whether or not to refer to a neighboring tile in inter-tile prediction within the tile group described above, and random MV (temporal MV) in the merge mode and the AMVP mode are also derived and used in the surrounding tiles other than the tile The syntax (tg_temporal_MV_across_tiles_enabled_flag[i]) indicating whether or not to do this, and the syntax (tg_loop_filter_across_tiles_enabled_flag[i]) indicating whether to use neighboring tile information when loop filtering can be set for each tile rectangular.

12 is a diagram specifically showing a tile group in a picture and a NAL unit of the tile group according to another embodiment of the present disclosure.

As in Fig. 11, in Fig. 12, one picture is divided into 4 x 4 = 16 tiles. However, in FIG. 12, one tile group includes two tiles rectangular, the first tile rectangular is composed of two tiles 1210, 1230, and the second tile rectangular is also two tiles 1220, 1240. It consists of. In FIG. 12, one tile group is composed of one NAL unit. The NAL unit may include a NALU header, a tile group header, tile headers 1212, 1222, 1232, and 1242 of tiles belonging to the tile group and tile data 1214, 1224, 1234, and 1244. Alternatively, the tile data may be configured without tile headers for four tiles. Tiles belonging to the tile group may be included in the NAL unit in the raster scan order or may be included in the NAL unit in the raster scan order for each tile rectangular. In FIG. 12, tiles belonging to the tile group are included in the NAL unit in the order of raster scan.

Finally, the tile header and tile data will be described.

The tile header includes information about one tile. [Table 10] below shows the syntax of the tile header as an example.

tile_header(　) { start_code_prefix tile_idx … tile_qp_delta … }

For example, in the tile header, a syntax (start_code_prefix) indicating a starting point serving as an entry point so as to be randomly accessible to one tile among a plurality of tiles in a bit stream corresponding to one tile group, a picture level header The syntax (tile_idx) indicating the index of the tile based on the layout of the tile defined by △ for the QP value to be applied to the CTU and CU included in the tile based on the initial QP value provided by the tile group to which the tile belongs A syntax (tile_qp_delta) indicating the QP value is included. The tile index may be specified for each horizontal axis and vertical axis, or may be designated as one index in the order of raster scan.

Meanwhile, the QP value to be applied to the tile may be calculated using Equation 1 below.

[Table 11] below shows the syntax of tile data as an example.

tile_data(　) { do { coding_tree_unit() } while (!end_of_tile) }

13 is a diagram illustrating that some regions refer to other regions in a tile group during inter prediction according to an embodiment of the present disclosure.

13(b) shows a tile group in the current picture, and FIG. 13(a) shows the same tile group in the current picture in the reference picture. In (b) of FIG. 13, the rectangular area 1320 indicates a block to be coded, and an arrow 1330 indicates the movement of the rectangular area 1320. That is, the square region 1310 in FIG. 13A shows a reference block indicated by the MV of the encoding target block.

For example, when the syntax (tg_inter_prediction_across_tiles_enabled_flag) indicating whether to refer to inter-tile prediction in the tile group header is set to reference, the rectangular area 1310 in FIG. 13A can be used as a reference block. On the other hand, when the syntax is set to not reference, a reference block is generated with the pixel value in the upper right tile of the rectangular area 1320 in FIG. 13B without reference to another tile. At this time, a process for a case where the upper right tile is regarded as one picture and is referred to outside the picture boundary may be performed. That is, it means that the picture boundary pixel value is copied and padded, and a portion outside the boundary is filled with the boundary pixel. This will be described in detail with reference to FIG. 14 below.

14 is a flowchart illustrating inter prediction according to an embodiment of the present disclosure.

A reference picture, a motion vector difference (mvd), and a motion vector predictor (mvp), which are motion information of an encoding target block, are obtained (S1410).

The mv value of the encoding target block is derived using the obtained motion information (S1420).

The position of the region indicated by the mv value is determined (S1430).

It is checked whether the identified position of the area is within a current tile (S1440).

If the identified location of the region is within the current tile, a reference block is acquired within the current tile (S1450).

If the identified position of the area is not within the current tile, it is checked whether the identified area is within the tile group to which the current tile belongs (S1460).

If the identified position of the area is within a tile group to which the current tile belongs, it is checked whether other neighboring tiles are referred to in inter-prediction of a plurality of tiles in the tile group (S1470).

When it is determined that the neighboring tiles are referred to in the inter-prediction of a plurality of tiles in the tile group, a reference block is obtained in the tile group (S1480).

However, even if the identified position of the area is not within the tile group to which the current tile belongs, or the identified position of the area is within the tile group to which the current tile belongs, when inter-prediction among a plurality of tiles in a tile group does not refer to other adjacent tiles. If not, the padding method for copying the pixel value is used to fill the value of the corresponding reference block in addition to the tile group with boundary pixel values (S1490). Alternatively, the mv value is clipped to the nearest boundary value in the current tile.

15 is a flowchart illustrating a method of a video encoding apparatus configuring one picture according to the present disclosure.

The device, in particular, the block dividing unit of the device divides the one picture into tiles (S1510).

The encoding unit of the apparatus sets information on the divided tiles as a picture level header (S1520). Information on the divided tiles may be layout information of the divided tiles, specifically, whether the picture is equally divided on the horizontal axis and the vertical axis, the number of tiles divided on the horizontal axis, the number of tiles divided on the vertical axis, and the like. It may include.

The encoding unit sets a plurality of tiles among the divided tiles as one tile group (S1530). In detail, tiles having similar characteristics among the divided tiles may be set as the one tile group. In addition, the plurality of tiles may be composed of a plurality of tiles rectangular, and the plurality of tiles rectangular may be set as the one tile group.

The encoding unit sets information about the tile group as a tile group header (S1540). The tile group header may include information indicating the location of the tile group, whether to refer to other adjacent tiles when inter prediction between tiles within the tile group, or whether to use neighboring tile information when loop filtering. In addition, whether a certain portion is padded in the border region of the tile group with the tile group header, and if padding, information about a value filled in the padding region may be further included.

The encoding unit includes the tile group and the tile group header and is configured as a network adaptive layer (NAL) unit (S1550). The NAL unit may further include tile headers and tile data of tiles included in the tile group.

In the present disclosure, specifically, the block dividing unit and the encoding unit of the apparatus are referred to as performing the procedure, but one component may perform all of the procedure or a plurality of components may be divided to perform the procedure.

16 is a flowchart illustrating a method for a video decoding apparatus to determine a picture composed of one according to the present disclosure.

In detail, the apparatus, the decoder of the apparatus receives a bitstream, and decodes the received bitstream to distinguish a tile group and a tile group header included in the NAL unit (S1610).

The device infers information about the tile group from the tile group header (S1620).

The device determines a divided tile composed of the tile group (S1630).

The apparatus determines information on the tile divided from the picture level header (S1640).

15 and 16, it is described that the steps S1510 to S1550 are executed sequentially, but this is merely illustrative of the technical idea of an embodiment of the present invention. In other words, a person having ordinary knowledge in the technical field to which one embodiment of the present invention pertains may execute or change the order described in FIGS. 15 and 16 without departing from the essential characteristics of one embodiment of the present invention, or process S1510 to process Since one or more processes of S1550 are executed in parallel, various modifications and variations may be applied, so that FIGS. 15 and 16 are not limited to time series.

Meanwhile, the processes illustrated in FIGS. 15 and 16 may be implemented as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data readable by a computer system is stored. That is, the computer-readable recording medium includes magnetic storage media (eg, ROM, floppy disk, hard disk, etc.), optical reading media (eg, CD-ROM, DVD, etc.) and carrier waves (eg, the Internet). Storage). In addition, 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.

The above description is merely illustrative of the technical idea of the present embodiment, and those skilled in the art to which this embodiment belongs will be capable of various modifications and variations without departing from the essential characteristics of the present embodiment. Therefore, the present embodiments are not intended to limit the technical spirit of the present embodiment, but to explain, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of the present embodiment should be interpreted by the claims below, and all technical spirits within the equivalent range should be interpreted as being included in the scope of the present embodiment.

Claims (9)

In the method of constructing one picture,
Dividing the one picture into tiles,
Setting information on the divided tiles as a picture level header,
Setting a plurality of tiles among the divided tiles into one tile group,
Setting information about the tile group to a tile group header, and
A method of configuring one picture including the step of configuring the tile group and the tile group header into a network adaptive layer (NAL) unit. According to claim 1,
Information about the divided tiles,
A method of configuring one picture, characterized in that it is layout information of the divided tiles. According to claim 1,
Information about the divided tiles,
A method of constructing one picture characterized in that the pictures are equally divided into horizontal and vertical axes, the number of tiles divided by the horizontal axis, and the number of tiles divided by the vertical axis. According to claim 1,
The step of setting a plurality of tiles among the divided tiles into a single tile group,
A method of configuring a picture, characterized in that the steps of setting tiles of similar characteristics to the one tile group. According to claim 1,
Setting information about the tile group to a tile group header includes:
One that is characterized by setting information indicating the location of the tile group, whether to refer to other adjacent tiles when inter prediction between tiles within the tile group, and whether to use neighboring tile information during loop filtering as the tile group header. How to construct a picture. The method of claim 5,
Setting information about the tile group to a tile group header includes:
A method of constructing one picture, characterized in that whether a certain portion is padded in the border region of the tile group, or if padding is performed, setting information of a value to be filled in the padding region. According to claim 1,
The step of configuring the tile group and the tile group header as a NAL unit includes:
A method of configuring one picture, characterized in that it further comprises a tile header and tile data of tiles included in the tile group and configuring the NAL unit. According to claim 1,
The step of setting a plurality of tiles among the divided tiles into a single tile group,
A method of configuring a picture, characterized in that the plurality of tiles is composed of a plurality of tiles rectangular, and the plurality of tiles rectangular is set as the one tile group. In the video encoding apparatus constituting one picture,
A block division unit for dividing the one picture into tiles, and
Information on the divided tiles is set as a picture level header, a plurality of tiles among the divided tiles are set as one tile group, and information on the tile groups is set as a tile group header, and the tile group and the tile group header are set. An image encoding apparatus including an encoding unit comprising a network adaptive layer (NAL) unit including a.

Images