JP2020141285A - Image decoder - Google Patents

Abstract

To provide an image decoder that does not need to store pixels in a line buffer more than necessary.SOLUTION: An intra prediction image generation unit (310) in a moving image decoder (31) generates an intra prediction image by referring to any of pixels included in any of areas of multiple horizontal lines, multiple vertical lines, and an upper left area of a target block. An availability setting unit (313) sets pixels contained in at least one of the vertical lines and the horizontal lines to be unavailable in the area.SELECTED DRAWING: Figure 7

Description

Embodiments of the present invention relate to an image decoding device.

In order to efficiently transmit or record an image, an image coding device that generates coded data by encoding the image and an image decoding device that generates a decoded image by decoding the coded data It is used.

Specific image coding methods include, for example, methods proposed by H.264 / AVC and HEVC (High-Efficiency Video Coding).

In such an image coding method, the image (picture) constituting the image is a slice obtained by dividing the image, a coding tree unit (CTU) obtained by dividing the slice, and the like. A coding unit (sometimes called a coding unit (CU)) obtained by dividing a coding tree unit, and a transformation unit (TU: Transform Unit) obtained by dividing a coding unit. ) Is managed by a hierarchical structure, and each CU is encoded / decoded.

Further, in such an image coding method, a predicted image is usually generated based on a locally decoded image obtained by encoding / decoding an input image, and the predicted image is subtracted from the input image (original image). The prediction error (sometimes referred to as "difference image" or "residual image") obtained in the above process is encoded. Examples of the method for generating a prediction image include inter-screen prediction (inter-screen prediction) and in-screen prediction (intra-prediction).

Further, Non-Patent Document 1 is mentioned as a recent image coding and decoding technique. Non-Patent Document 1 discloses a decoding technique for generating an intra-predicted image using a Multi Reference Line (MRL) and generating a decoded image based on the intra-predicted image.

"CE3: Multiple reference line intra prediction (Test 1.1.1, 1.1.2, 1.1.3 and 1.1.4)", JVET-L0283-v2, Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29/WG 11 12th Meeting: Macao, CN, 3-12 Oct. 2018

When M RL is used as in Non-Patent Document 1, there is a possibility that the pixels referred to when generating the intra-predicted image are stored in the line buffer more than necessary.

An object of the present invention is to provide an image decoding device that does not need to store pixels referred to when generating an intra-predicted image in a line buffer more than necessary.

In order to solve the above problems, the image decoding device according to one aspect of the present invention uses a reference sample availability setting unit for setting the availability of each pixel and pixels set as available by the reference sample availability setting unit. It includes an intra-prediction image generation unit that generates an intra-prediction image by reference, and the intra-prediction image generation unit is a horizontal line above the target block, and the distance from the target block is determined by a plurality of predetermined values. Any of the plurality of horizontal lines specified respectively, or any of the plurality of vertical lines on the left side of the target block and the distance from the target block is defined by the plurality of predetermined values. Further, referring to any of the pixels included in the upper left region of the target block, which includes the pixels at the positions where each of the plurality of horizontal lines intersects with each of the plurality of vertical lines. The intra-prediction image of the target block is generated, and the reference sample availability setting unit is a pixel included in at least one of the plurality of vertical lines and horizontal lines in the upper left region of the target block. Is set to unavailable.

In order to solve the above problems, the image decoding device according to one aspect of the present invention uses a reference sample availability setting unit for setting the availability of each pixel and pixels set as available by the reference sample availability setting unit. It includes an intra-prediction image generation unit that generates an intra-prediction image by reference, and the intra-prediction image generation unit is a horizontal line above the target block, and the distance from the target block is determined by a plurality of predetermined values. One of the plurality of horizontal lines specified for each, and any of the plurality of vertical lines on the left side of the target block whose distance from the target block is defined by the plurality of predetermined values. , Is used to generate an intra-predicted image of the target block, and the reference sample availability setting unit includes pixels included in the horizontal line at the upper right of the target block and the vertical line at the lower left of the target block. At least one of the pixels included in is set to be unavailable.

According to the above configuration, it is possible to provide an image decoding device in which the line buffer does not need to store the pixels referred to when generating the intra prediction image more than necessary.

It is the schematic which shows the structure of the image transmission system which concerns on this embodiment. It is a figure which showed the structure of the transmitting device equipped with the moving image coding device which concerns on this embodiment, and the receiving device equipped with moving image decoding device. (a) shows a transmitting device equipped with a moving image coding device, and (b) shows a receiving device equipped with a moving image decoding device. It is a figure which showed the structure of the recording device which carried out the moving image coding device which concerns on this embodiment, and the reproduction device which carried out moving image decoding device. (a) shows a recording device equipped with a moving image coding device, and (b) shows a reproducing device equipped with a moving image decoding device. It is a figure which shows the hierarchical structure of the data of a coded stream. It is a figure which shows the division example of CTU. It is a schematic diagram which shows the type (mode number) of an intra prediction mode. It is the schematic which shows the structure of the moving image decoding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the intra prediction parameter decoding unit. It is a figure for demonstrating the line buffer. It is a figure for demonstrating MRL (Multi Reference Line) in intra prediction. It is a figure which shows the structure of the intra prediction image generation part. It is a figure for demonstrating an example of setting of the availability of each pixel by the availability setting unit. It is a figure for demonstrating an example of setting of the availability of each pixel by the availability setting unit. It is a block diagram which shows the structure of the moving image coding apparatus which concerns on this embodiment. It is the schematic which shows the structure of the intra prediction parameter coding part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing the configuration of the image transmission system 1 according to the present embodiment.

The image transmission system 1 is a system that transmits a coded stream in which a coded image is encoded, decodes the transmitted coded stream, and displays an image. The image transmission system 1 includes a moving image coding device (image coding device) 11, a network 21, a moving image decoding device (image decoding device) 31, and a moving image display device (image display device) 41. ..

The image T is input to the moving image coding device 11.

The network 21 transmits the coded stream Te generated by the moving image coding device 11 to the moving image decoding device 31. The network 21 is an Internet (Internet), a wide area network (WAN: Wide Area Network), a small network (LAN: Local Area Network), or a combination thereof. The network 21 is not necessarily limited to a two-way communication network, but may be a one-way communication network that transmits broadcast waves such as terrestrial digital broadcasting and satellite broadcasting. Further, the network 21 may be replaced with a storage medium such as a DVD (Digital Versatile Disc: registered trademark) or BD (Blue-ray Disc: registered trademark) on which an encoded stream Te is recorded.

The moving image decoding device 31 decodes each of the coded streams Te transmitted by the network 21 and generates one or a plurality of decoded images Td.

The moving image display device 41 displays all or a part of one or a plurality of decoded images Td generated by the moving image decoding device 31. The moving image display device 41 includes, for example, a display device such as a liquid crystal display or an organic EL (Electro-luminescence) display. Examples of the display form include stationary, mobile, and HMD. Further, when the moving image decoding device 31 has a high processing capacity, a high-quality image is displayed, and when the moving image decoding device 31 has a lower processing power, an image that does not require a high processing power and a display power is displayed. ..

<Operator>
The operators used herein are described below.

>> is the right bit shift, << is the left bit shift, & is the bitwise AND, | is the bitwise OR, | = is the OR assignment operator, and || is the OR.

x? y: z is a ternary operator that takes y when x is true (other than 0) and z when x is false (0).

Clip3 (a, b, c) is a function that clips c to a value greater than or equal to a and less than or equal to b, returning a if c <a, returning b if c> b, and other cases. Is a function that returns c (where a <= b).

abs (a) is a function that returns the absolute value of a.

Int (a) is a function that returns an integer value of a.

floor (a) is a function that returns the largest integer less than or equal to a.

ceil (a) is a function that returns the largest integer greater than or equal to a.

a / d represents the division of a by d (rounded down to the nearest whole number).

<Structure of coded stream Te>
Prior to the detailed description of the moving image coding device 11 and the moving image decoding device 31 according to the present embodiment, the data of the coded stream Te generated by the moving image coding device 11 and decoded by the moving image decoding device 31. The structure will be described.

FIG. 4 is a diagram showing a hierarchical structure of data in the coded stream Te. The coded stream Te typically includes a sequence and a plurality of pictures that make up the sequence. In FIGS. 4 (a) to 4 (f), a coded video sequence that defines the sequence SEQ, a coded picture that defines the picture PICT, a coded slice that defines the slice S, and a coded slice that defines the slice data, respectively. It is a figure which shows the coded tree unit included in the data, the coded slice data, and the coded unit included in a coded tree unit.

(Encoded video sequence)
The coded video sequence defines a set of data that the moving image decoding device 31 refers to in order to decode the sequence SEQ to be processed. As shown in FIG. 4A, the sequence SEQ includes a video parameter set (Video Parameter Set), a sequence parameter set SPS (Sequence Parameter Set), a picture parameter set PPS (Picture Parameter Set), a picture PICT, and an addition. Includes SEI (Supplemental Enhancement Information).

The video parameter set VPS is a set of coding parameters common to a plurality of moving images in a moving image composed of a plurality of layers, and a set of coding parameters related to the plurality of layers included in the moving image and individual layers. The set is defined.

The sequence parameter set SPS defines a set of coding parameters that the moving image decoding device 31 refers to in order to decode the target sequence. For example, the width and height of the picture are specified. In addition, there may be a plurality of SPS. In that case, select one of multiple SPSs from PPS.

The picture parameter set PPS defines a set of coding parameters that the moving image decoding device 31 refers to in order to decode each picture in the target sequence. For example, a reference value of the quantization width used for decoding a picture (pic_init_qp_minus26) and a flag indicating the application of weighted prediction (weighted_pred_flag) are included. There may be a plurality of PPSs. In that case, one of a plurality of PPSs is selected from each picture in the target sequence.

(Encoded picture)
The coded picture defines a set of data referred to by the moving image decoding device 31 in order to decode the picture PICT to be processed. The picture PICT includes slices 0 to NS-1 as shown in FIG. 4 (b) (NS is the total number of slices contained in the picture PICT).

In the following, when it is not necessary to distinguish between slice 0 and slice NS-1, the subscripts of the symbols may be omitted. The same applies to the data included in the coded stream Te described below and with subscripts.

(Coded slice)
The coded slice defines a set of data referred to by the moving image decoding device 31 in order to decode the slice S to be processed. The slice contains a slice header and slice data as shown in FIG. 4 (c).

The slice header contains a group of coding parameters referred to by the moving image decoding device 31 to determine the decoding method of the target slice. The slice type specification information (slice_type) that specifies the slice type is an example of the coding parameters included in the slice header.

Slice types that can be specified by the slice type specification information include (1) I slices that use only intra-prediction during coding, and (2) P-slices that use unidirectional prediction or intra-prediction during coding. (3) Examples thereof include a B slice that uses unidirectional prediction, bidirectional prediction, or intra prediction at the time of coding. Note that the inter-prediction is not limited to single prediction and bi-prediction, and a prediction image may be generated using more reference pictures. Hereinafter, when referred to as P and B slices, they refer to slices containing blocks for which inter-prediction can be used.

The slice header may include a reference (pic_parameter_set_id) to the picture parameter set PPS.

(Coded slice data)
The coded slice data defines a set of data referred to by the moving image decoding device 31 in order to decode the slice data to be processed. The slice data includes the CTU, as shown in (d) of FIG. A CTU is a fixed-size (for example, 64x64) block that constitutes a slice, and is sometimes called a maximum coding unit (LCU: Largest Coding Unit).

(Encoded tree unit)
FIG. 4 (e) defines a set of data referred to by the moving image decoding device 31 in order to decode the CTU to be processed. CTU is the basis of coding processing by recursive quadtree division (QT (Quad Tree) division), quadtree division (BT (Binary Tree) division) or ternary tree division (TT (Ternary Tree) division). It is divided into a coding unit CU, which is a typical unit. The combination of BT division and TT division is called multi-tree division (MT (Multi Tree) division). A tree-structured node obtained by recursive quadtree division is called a coding node. The intermediate nodes of the quadtree, binary, and ternary tree are coded nodes, and the CTU itself is defined as the highest level coded node.

FIG. 5 is a diagram showing an example of CTU division. The CU is the terminal node of the encoding node and is not divided any further. CU is a basic unit of coding processing ((a) in FIG. 5). In the case of quadtree division, the coding node is divided into four coding nodes ((b) in FIG. 5). In the case of a vertical binary split, the coded node is divided into two coded nodes in the vertical or horizontal direction (FIGS. 5 (c) and 5 (d)). In the case of the ternary tree division, the coding node is divided into three coding nodes in the vertical direction or the horizontal direction ((e) and (f) in FIG. 5).

If the CTU size is 64x64 pixels, the CU size is 64x64 pixels, 64x32 pixels, 32x64 pixels, 32x32 pixels, 64x16 pixels, 16x64 pixels, 32x16 pixels, 16x32 pixels, 16x16 pixels, 64x8 pixels, 8x64 pixels. , 32x8 pixels, 8x32 pixels, 16x8 pixels, 8x16 pixels, 8x8 pixels, 64x4 pixels, 4x64 pixels, 32x4 pixels, 4x32 pixels, 16x4 pixels, 4x16 pixels, 8x4 pixels, 4x8 pixels, and 4x4 pixels. ..

(Encoding unit)
As shown in (f) of FIG. 4, a set of data referred to by the moving image decoding device 31 in order to decode the coding unit to be processed is defined. Specifically, the CU is composed of a CU header CUH, prediction parameters, conversion parameters, quantization conversion coefficients, and the like. The CU header defines the prediction mode and so on.

The prediction process may be performed in CU units or in sub-CU units that are further divided CUs. If the size of the CU and the sub CU are equal, there is only one sub CU in the CU. If the CU is larger than the size of the sub CU, the CU is split into sub CUs. For example, when the CU is 8x8 and the sub CU is 4x4, the CU is divided into four sub CUs consisting of two horizontal divisions and two vertical divisions.

There are two types of prediction (prediction mode): intra prediction and inter prediction. Intra prediction refers to prediction within the same picture, and inter prediction refers to prediction processing performed between different pictures (for example, between display times and between layer images).

The conversion / quantization process is performed in CU units, but the quantization conversion coefficient may be entropy-encoded in subblock units such as 4x4.

(Prediction parameter)
The prediction image is derived by the prediction parameters associated with the block. Prediction parameters include intra-prediction and inter-prediction prediction parameters.

Hereinafter, the prediction parameters of the intra prediction will be described. The intra prediction parameters are composed of the luminance prediction mode IntraPredModeY and the color difference prediction mode IntraPredModeC. FIG. 6 is a schematic diagram showing the types (mode numbers) of the intra prediction modes. As shown in FIG. 6, there are 94 types (-14 to 80) of intra prediction modes, for example. For the intra prediction mode, select 67 modes from them and use them. For example, planar prediction (0), DC prediction (1), Angular prediction (2-66). In addition, LM modes (81-83) may be added for color difference.

Syntax elements for deriving intra prediction parameters include, for example, intra_luma_mpm_flag, intra_luma_mpm_idx, intra_luma_mpm_remainder and the like.

(MPM)
intra_luma_mpm_flag is a flag indicating whether or not IntraPredModeY and MPM (Most Probable Mode) of the target block match. MPM is a prediction mode included in the MPM candidate list mpmCandList []. The MPM candidate list is a list that stores candidates that are estimated to have a high probability of being applied to the target block from the intra prediction mode of the adjacent block and the predetermined intra prediction mode. When intra_luma_mpm_pred_flag is 1, the IntraPredModeY of the target block is derived using the MPM candidate list and the index intra_luma_mpm_idx.

IntraPredModeY = mpmCandList [intra_luma_mpm_idx]
(REM)
When intra_luma_mpm_pred_flag is 0, it is derived using intra_luma_mpm_remainder from the remaining modes excluding the intra prediction mode included in the MPM candidate list from the entire intra prediction mode.

(Configuration of moving image decoding device)
The configuration of the moving image decoding device 31 (FIG. 7) according to the present embodiment will be described.

The moving image decoding device 31 includes an entropy decoding unit 301, a parameter decoding unit (predicted image decoding device) 302, a loop filter 305, a reference picture memory 306, a predicted parameter memory 307, a predicted image generator (predicted image generator) 308, and a reverse. It is composed of a quantization / inverse conversion unit 311 and an addition unit 312. In addition, in accordance with the moving image coding device 11 described later, there is also a configuration in which the moving image decoding device 31 does not include the loop filter 305.

The parameter decoding unit 302 further includes a header decoding unit 3020, a CT information decoding unit 3021, and a CU decoding unit 3022 (prediction mode decoding unit) (not shown), and the CU decoding unit 3022 further includes a TU decoding unit 3024. ing. These may be generically called a decoding module. The header decoding unit 3020 decodes the parameter set information such as SPS and PPS and the slice header (slice information) from the encoded data. The CT information decoding unit 3021 decodes the CT from the encoded data. The CU decoding unit 3022 decodes the CU from the encoded data. The TU decoding unit 3024 decodes the QP update information (quantization correction value) and the quantization prediction error (residual_coding) from the coded data when the TU contains a prediction error.

Further, the parameter decoding unit 302 includes an inter-prediction parameter decoding unit 303 and an intra-prediction parameter decoding unit 304 (not shown). The prediction image generation unit 308 includes an inter prediction image generation unit 309 and an intra prediction image generation unit 310.

In the following, an example in which CTU and CU are used as the processing unit will be described, but the processing is not limited to this example, and processing may be performed in sub-CU units. Alternatively, CTU and CU may be read as blocks and sub-CUs may be read as sub-blocks, and processing may be performed in units of blocks or sub-blocks.

The entropy decoding unit 301 performs entropy decoding on the coded stream Te input from the outside, and decodes each code (syntax element). For entropy coding, a method of variable-length coding of syntax elements using a context (probability model) adaptively selected according to the type of syntax element and the surrounding situation, a predetermined table, or There is a method of variable-length coding the syntax element using a calculation formula. The former CABAC (Context Adaptive Binary Arithmetic Coding) stores a stochastic model updated for each encoded or decoded picture (slice) in memory. Then, as the initial state of the context of the P picture or the B picture, the probability model of the picture using the same slice type and the same slice level quantization parameter is set from the probability models stored in the memory. This initial state is used for encoding and decoding processing. These codes include prediction information for generating a prediction image, prediction error for generating a difference image, and the like.

The entropy decoding unit 301 outputs these codes to the parameter decoding unit 302. The control of which code is decoded is performed based on the instruction of the parameter decoding unit 302.

(Structure of Intra Prediction Parameter Decoding Unit 304)
The intra prediction parameter decoding unit 304 derives an intra prediction parameter, for example, an intrapred mode, by referring to the prediction parameter stored in the prediction parameter memory 307, based on the code input from the entropy decoding unit 301. The intra prediction parameter decoding unit 304 outputs the derived intra prediction parameter to the prediction image generation unit 308, and stores it in the prediction parameter memory 307. The intra prediction parameter decoding unit 304 may derive an intra prediction mode that differs depending on the brightness and the color difference.

FIG. 8 is a schematic view showing the configuration of the intra-prediction parameter decoding unit 304 of the parameter decoding unit 302. As shown in FIG. 8, the intra prediction parameter decoding unit 304 includes a luminance intra prediction parameter decoding unit 3042 and a color difference intra prediction parameter decoding unit 3043.

The intra prediction parameter decoding unit 304 receives a syntax element from the entropy decoding unit 301. When intra_luma_mpm_flag is 1, the intra prediction parameter decoding unit 304 outputs intra_luma_mpm_idx to the MPM parameter decoding unit 30422 in the luminance intra prediction parameter decoding unit 3042. When the intra_luma_mpm_flag is 0, the intra prediction parameter decoding unit 304 outputs the intra_luma_mpm_remainder to the non-MPM parameter decoding unit 30423 of the luminance intra prediction parameter decoding unit 3042. Further, the intra prediction parameter decoding unit 304 outputs the syntax element of the color difference intra prediction parameter to the color difference intra prediction parameter decoding unit 3043.

The luminance intra prediction parameter decoding unit 3042 includes an MPM candidate list derivation unit 30421, an MPM parameter decoding unit 30422, a non-MPM parameter decoding unit 30423, and an MRL parameter decoding unit 30424.

The MPM parameter decoding unit 30422 derives the luminance prediction mode IntraPredModeY with reference to the MPM candidate list mpmCandList [] and intra_luma_mpm_idx derived by the MPM candidate list derivation unit 30421, and outputs the luminance prediction mode to the intra prediction image generation unit 310.

The non-MPM parameter decoding unit 30423 derives RemIntraPredMode as IntraPredModeY from the MPM candidate list mpmCandList [] and intra_luma_mpm_remainder, and outputs it to the intra prediction image generation unit 310.

The MRL parameter decoding unit 30424 derives RefLineIdx (refIdx) from intra_luma_ref_idx.
If intra_luma_ref_idx = 0, RefLineIdx = 0
If intra_luma_ref_idx = 1, RefLineIdx = 1
If intra_luma_ref_idx = 2, RefLineIdx = 3
The color difference intra prediction parameter decoding unit 3043 derives the color difference prediction mode IntraPredModeC from the syntax element of the color difference intra prediction parameter and outputs it to the intra prediction image generation unit 310.

The loop filter 305 is a filter provided in the coding loop, which removes block distortion and ringing distortion to improve image quality. The loop filter 305 applies filters such as a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to the decoded image of the CU generated by the addition unit 312.

The reference picture memory 306 stores the decoded image of the CU generated by the addition unit 312 at a predetermined position for each target picture and the target CU. The reference picture memory 306 also functions as a line buffer.

Hereinafter, the line buffer (line memory) will be described with reference to FIG. FIG. 9 is a diagram for explaining the line buffer. In the present embodiment, the line buffer is a buffer for holding the reference pixel referred to in the intra prediction. As shown in FIG. 9A, the line buffer has the upper pixel value (horizontal line L1), the left pixel value (vertical line L2), and the upper left pixel value (area R) of the target block with respect to the target CTU. To hold. The line buffer shown in FIG. 9A may be stored in the reference picture memory 306 as a one-dimensional array as shown in FIG. 9C.

Further, in FIG. 9B, prior to the process of generating the decoded image of the target block b1, the horizontal line l1 on the upper side of the target block b1, the vertical line l2 on the left side of the target block b1 and the target are stored in the line buffer. The pixel value of each pixel included in the upper left region r of block b1 is retained. The line buffer is overwritten each time the addition unit 312, which will be described later, generates a decoded image of the target block by referring to the intra prediction image and the prediction error. For example, after the addition unit 312 generates the decoded image of the target block b1 shown in FIG. 9B, the line buffer is overwritten by the pixel value shown in FIG. 9D. That is, the line buffer lines the rightmost pixel of the target block b1 (the pixel on the left side of b2), the area of the upper left region of the target block b2, and the upper pixel of the target block b3 to be decoded after the target block b2. Store in a buffer.

In the above example, the reference picture memory 306 also functions as a line buffer, but the present embodiment is not limited to this. In the present embodiment, the moving image decoding device 31 may have a line buffer separate from the reference picture memory 306, and the pixel values stored in the line buffer may be supplied to the unfiltered reference image setting unit 3102.

The prediction parameter memory 307 stores prediction parameters at predetermined positions for each decoding target block. Specifically, the prediction parameter memory 307 stores the parameters derived by the parameter decoding unit 302, the pred mode decoded by the entropy decoding unit 301, and the like.

PredMode, prediction parameters, etc. are input to the prediction image generation unit 308. Further, the prediction image generation unit 308 reads the reference picture from the reference picture memory 306. The prediction image generation unit 308 generates a prediction image of a block or a subblock by using the prediction parameter and the read reference picture (reference picture block) in the prediction mode indicated by predMode. Here, the reference picture block is a set of pixels on the reference picture (usually called a block because it is rectangular), and is an area to be referred to for generating a predicted image.

(Intra prediction image generation unit 310)
When the predMode indicates the intra prediction mode, the intra prediction image generation unit 310 performs the intra prediction using the intra prediction parameters input from the intra prediction parameter decoding unit 304 and the reference pixels read from the reference picture memory 306.

The intra prediction image generation unit 310 generates an intra prediction image by referring to the pixels set as available by the availability setting unit 313. The intra prediction image generation unit 310 reads pixels adjacent to the target block from the reference picture memory 306. The pixel to be referred to differs depending on the intra prediction mode.

The intra prediction image generation unit 310 refers to the read decoded pixel value and the IntraPredMode to generate a prediction image of the target block. The intra prediction image generation unit 310 outputs the prediction image of the generated block to the addition unit 312.

In the following, a process in which the intra-prediction image generation unit 310 generates an intra-prediction image by Angular prediction using MRL (Multi Reference Line) will be described with reference to FIG.

FIG. 10 is a diagram for explaining MRL in intra-prediction.

In HEVC, among the horizontal lines adjacent to the upper side of the target block, the vertical lines adjacent to the left side of the target block, and the pixels included in the upper left area of the target block, the pixels included in one line directly in contact with the target block. By referring to it, an intra prediction image of the target block is generated.

On the other hand, in MRL, as shown in (a) of FIG. 10, a plurality of vertical lines (A and B) on the left side of the target block, a plurality of horizontal lines (D and E) on the upper side of the target block, and a target block. The upper left area (C) of is available for reference.

More specifically, in MRL, any of a plurality of horizontal lines on the upper side of the target block, any of a plurality of vertical lines on the left side of the target block, and any of the pixels included in the upper left region C of the target block. The intra prediction image of the target block is generated with reference to. In the MRL, the pixel value of the region E in FIG. 10A may be generated (using) by copying the pixel value of the rightmost pixel of the region D. Further, in the MRL, the pixel value of the area A may be generated by using the pixel value of the pixel at the lower end of the area B.

The upper left region C of the above-mentioned target block is an region including pixels at positions where each of the plurality of horizontal lines and each of the plurality of vertical lines intersect. Further, in the above-mentioned plurality of horizontal lines and vertical lines, the distance from the target block is defined by a plurality of predetermined values (RefLineIdx = 0, RefLineIdx = 1 and RefLineIdx = 3). RefLineIdx is a variable derived from the syntax element intra_luma_ref_idx and represents the position of the line of the adjacent pixel to be referenced. The relationship between syntax elements and variables is shown in Fig. 10 (b).

Here, as shown in FIG. 10A, RefLineIdx = 0 defines a horizontal line on the upper side of one pixel of the target block and a vertical line on the left side of one pixel of the target block. That is, RefLineIdx = 0 defines horizontal lines and vertical lines adjacent to the upper and left sides of the target block. RefLineIdx = 1 defines a horizontal line on the upper side of two pixels of the target block and a vertical line on the left side of two pixels of the target block. RefLineIdx = 3 defines a horizontal line on the upper side of 4 pixels of the target block and a vertical line on the left side of 4 pixels of the target block. Here, the line of RefLineIdx = 2, that is, the horizontal line 3 pixels above the prediction target block and the vertical line 3 pixels left side of the target block are not referred to when generating the intra prediction image.

As described above, the line buffer needs to store a plurality of horizontal lines on the upper side of the target block, a plurality of vertical lines on the left side of the target block, and pixels included in the upper left region of the target block. The multiple horizontal lines above the target block are stored in the line buffer by the width of the CTU x the number of pixels (for example, 128 x 3 (= 384) pixels), and the multiple vertical lines on the left side of the target block are the height of the CTU. Only the number of pixels of × lines (for example, 128 × 3 (= 384) pixels) may be stored in the line buffer. On the other hand, for the pixels included in the upper left area of the target block, it is necessary to store as many pixels in the line buffer as the number of blocks that can be generated by the block division within 1 CTU. Specifically, when the moving image decoding device 31 divides 1 CTU (ctbSize) into a constant multiple of the minimum block size (MinCbSize), the upper left region of the target block (divided block) is ctbSize / MinCbSize at the maximum. For example, if the CTU size is 128x128 (= 16364) pixels and the minimum block size is 4x4 = 16 pixels, 32 areas in the upper left of the target block are generated. Here, when the number of pixels in the upper left area of the target block to be stored is 11, it is necessary to store 11 × 32 (= 352) pixels in the line buffer. From the viewpoint of processing speed, the moving image decoding device 31 does not need to keep the raster scan as the scanning order, and there is a case where a larger upper left region of the target block is generated depending on the division.

As shown in FIG. 10, when MRL is used (when MRL is on), for example, any of three horizontal lines, any of three vertical lines, and 4 × 4 (= 16) at the upper left of the target block. An intra-predicted image of the target block is generated by referring to any of the regions composed of pixels. Then, the target block is referred to by the three horizontal lines on the upper side of the target block defined by RefLineIdx = 0, RefLineIdx = 1 and RefLineIdx = 3, the three vertical lines on the left side, and the upper left area of the target block. Generate an intra-prediction image of. In this case, the upper horizontal line and the left vertical line of the target block each store three times as many pixels in the line buffer as compared with the case where the horizontal line and the vertical line are one line (when MRL is off). There is a need. In addition, the line buffer stores 11 times as many pixels in the upper left area of the target block when MRL is on as compared with the case where only pixels that share vertices with the target block are referenced (when MRL is off). There is a need.

Further, for example, in a configuration in which only the pixels of the line used are retained instead of storing the pixels of three lines in the line buffer, only two lines, the line referenced by the target block and the line referenced by the previous block, are used. It is sufficient to store 3 lines, and it is not necessary to store 3 lines in the line buffer. However, since it refers to at least two lines, the line buffer has twice as many pixels in each of the upper horizontal line and left vertical line areas as compared to the case where MTL is off (1 line). Must be stored in the line buffer. Also, in the upper left region of the target block, it is necessary to store 11 times as many pixels as in the case where MRL is off.

On the other hand, the intra prediction image generation unit 310 of the present embodiment generates an intra prediction image by referring only to the pixels set to be available by the availability setting unit 313. For example, the intra prediction image generation unit 310 generates an intra prediction image by referring only to the pixels sharing the apex with the target block in the upper left region of the target block. Therefore, it is possible to reduce the number of pixels to be referred to when generating the intra prediction image, and it is possible to reduce the size of the line buffer.

(Pixel reference method by intra prediction image generation unit 310)
Hereinafter, a pixel reference method when the intra prediction image generation unit 310 generates an intra prediction image will be described in detail with reference to FIG. 10.

When the vertical line on the left side of the target block specified by RefLineIdx, the upper left area of the target block, and the horizontal line on the upper side of the target block are all available, the intra prediction image generation unit 310 of the adjacent block of the target block The image is referred to as the intra reference image refN [] [] as it is, and the intra prediction image of the target block is generated.

When the vertical line on the left side of the target block specified by RefLineIdx, the upper left area of the target block, and the horizontal line on the upper side of the target block are all impossible, the intra prediction image generation unit 310 uses the image refN [] of the reference line. Set 1 << (BitDepth-1) in [] and generate an intra-predicted image using the image refN [] []. Here, BitDepth indicates the bit depth of the pixel value, for example, 10 bits.

If some of the images are available among the plurality of horizontal lines on the upper side of the target block and the plurality of vertical lines on the left side of the target block, the intra prediction image generation unit 310 refers to the available pixels. Then, the image refN [] [] is derived, and the intra-predicted image of the target block is generated using the image refN [] [].

(Details of pixel reference method by intra prediction image generation unit 310)
More specifically, when the upper left coordinate of the target block is (xTbTmp, yTbTmp), the width is bW, and the height is bH, the intra prediction image generation unit 310 performs the intra by the following REFS step (reference sample step). Derived the reference image p [] [] (x = -1 --RefLineIdx, y = -1 --RefLineIdx..refH ―― 1 and x = -RefLineIdx..refW ―― 1, y = ―― 1 --RefLineIdx) used for the prediction image. To do.

REFS step 0: refW = 2 * bW, refH = 2 * bH
REFS step 1: Availability setting unit (reference sample availability setting unit) 313 derives the availability of reference images refN [x] [y] and refN [x] [y] from adjacent images of the target block (x). = -1 --RefLineIdx, y = -1 --RefLineIdx..refH --1 and x = --RefLineIdx..refW --1, y = -1 --RefLineIdx)
REFS step 2: The intra prediction image generation unit 310 uses the available pixels when at least one pixel of the reference image refN [x] [y] is marked as unavailable for intra prediction. Derivation of [] [].

REFS step 3: The intra-prediction image generation unit 310 filters the reference image refN [x] [y] to derive the intra-prediction reference image p [x] [y] (x = -1 --RefLineIdx, y). = -1 --RefLineIdx..refH --1 and x = -RefLineIdx..refW --1, y = -1 --RefLineIdx).

(Details of pixel reference method by intra prediction image generation unit 310)
The intra prediction image generation unit 310 uses the reference image refN [] [] (x = -1 --RefLineIdx) for the intra prediction image by the following SUBS step when the width and height of the reference image refN are refW and refH. , y = -1 --RefLineIdx..refH --1 and x = -RefLineIdx..refW --1, y = -1 --RefLineIdx).

SUBS step 1: Availability setting unit 313 uses x = -1 --RefLineIdx, y = -1 --RefLineIdx..refH-1 and x = -RefLineId..refW --1, y = -1 --RefLineIdx pixels refN [ If all of x] [y] are not available, set pixel refN [x] [y] to 1 << (bitDepth-1).

SUBS step 2: The availability setting unit 313 uses x = -1-RefLineIdx, y = -1-RefLineIdx..refH-1 and x = -RefLineIdx..refW-1, y, except for the example shown in SUBS step 1. = -1-If any of the pixels refN [x] [y] of RefLineIdx is not available, the following processing is performed in order.

SUBS step 3: When refN [-1-RefLineIdx] [refH-1] is not available, the availability setting unit 313 starts from the lower left pixel (x = -1-RefLineIdx, y = refH-1) to the upper left. Search for pixels refN [x] [y] belonging to the vertical line on the left side of the target block toward the pixels (x = -1-RefLineIdx, y = -1-RefLineIdx). The availability setting unit 313 further increases the upper side of the target block from the upper left pixel (x = -RefLineIdx, y = -1-RefLineIdx) toward the upper right pixel (x = refW-1, y = -1-RefLineIdx). Search for pixels that belong to the horizontal line of. The availability setting unit 313 sets the pixel value refN [x] [y] of the pixel marked as available for intra-prediction first found to refN [-1-RefLineIdx] [refH-1]. For example, it can be expressed by the following formula.
Found = FALSE
for (x = -1-RefLineIdx, y = refH-1; y <= -1-RefLineIdx && found == FALSE; y = y + 1) {
if (pixels of (x, y) are available) {
refN [-1-RefLineIdx] [refH-1] = refN [x] [y]
found = TRUE
}
}
for (x = -RefLineIdx, y = -1-RefLineIdx; x <= refW-1 && found == FALSE; x = x + 1) {
if (pixels of (x, y) are available) {
refN [-1-RefLineIdx] [refH-1] = refN [x] [y]
found = TRUE
}
}
SUB step 4:
Next, the availability setting unit 313 targets from the lower left pixel (x = -1-RefLineIdx, y = refH-2) to the upper left pixel (x = -1-RefLineIdx, y = -1-RefLineIdx). Search for pixels refN [x] [y] that belong to the vertical line on the left side of the block. When refN [x] [y] is marked as unavailable for intra-prediction, the availability setting unit 313 sets the position (x, y +) below the unreferenceable pixel position (x, y). Set the pixel refN [x] [y + 1] of 1) to the target pixel refN [x] [y].
for (x = -1-RefLineIdx, y = refH-2; y <= -1-RefLineIdx; y = y-1)
if ((x, y) pixels are not available) {
refN [x] [y] = refN [x] [y + 1]
}
SUBS step 5:
Next, the availability setting unit 313 is located above the target block from the upper left pixel (x = 0, y = -1-RefLineIdx) toward the upper right pixel (x = refW-1, y = -1-RefLineIdx). Search for pixels refN [x] [y] that belong to the horizontal line of. When refN [x] [y] is marked as unavailable for intra-prediction, the availability setting unit 313 sets the position (x-1, y) to the left of the unreferenceable pixel position (x, y). ) Pixel refN [x-1] [y] is set to the target pixel refN [x] [y].
for (x = 0, y = -1-RefLineIdx; x <= refW-1; x = x + 1)
if ((x, y) pixels are not available) {
refN [x] [-1] = refN [x-1] [-1]
}
SUBS Step 4:
Finally, the availability setting unit 313 resets the pixel refN [x] [y] that has completed the above step to be usable for intra prediction.

The above process can also be expressed as follows.

For example, the intra prediction image generation unit 310 is located at the lower left in the vertical line and the horizontal line (L-shaped line formed by 4n + 1 pixels) defined by RefLineIdx = 0 shown in FIG. 10A. An intra-predicted image of the target block is generated by referring to the L-shaped line from the pixel of 1 to the upper right pixel. Here, 2n = bW + nH.

Further, even in the above-mentioned L-shaped line, there are pixels that cannot be used (for example, undecoded pixels or pixels outside the picture). In this case, the intra prediction image generation unit 310 generates the pixel value of the unusable pixel by using the pixel value of the previous pixel in the above-mentioned L-shaped line. Subsequently, the intra prediction image generation unit 310 generates an intra prediction image using the generated pixel values.

In the above example, the intra prediction image generation unit 310 cannot be used from the lower left pixel to the upper right pixel in the L-shaped line consisting of the vertical line and the horizontal line defined by the value of RefLineIdx = 0. Searching for new pixels. However, the present embodiment is not limited to this. In the present embodiment, the intra prediction image generation unit 310, for example, in an L-shaped line consisting of a vertical line and a horizontal line defined by RefLineIdx = 1 or RefLineIdx = 3, from the upper right pixel to the lower left pixel. , You may search for unusable pixels.

(Details of the predicted image generator)
Next, the details of the configuration of the intra-prediction image generation unit 310 will be described with reference to FIG. The intra prediction image generation unit 310 includes a prediction target block setting unit 3101, an unfiltered reference image setting unit 3102 (first reference image setting unit), a filtered reference image setting unit 3103 (second reference image setting unit), and an intra. It includes a prediction unit 3104 and a prediction image correction unit 3105 (prediction image correction unit, filter switching unit, weight coefficient changing unit).

Based on each reference pixel (unfiltered reference image) on the reference area R, the filtered reference image generated by applying the reference pixel filter (first filter), and the intra prediction mode, the intra prediction unit 3104 is a prediction target block. (Prediction image before correction) is generated and output to the prediction image correction unit 3105. The prediction image correction unit 3105 corrects the provisional prediction image according to the intra prediction mode, generates a prediction image (corrected prediction image), and outputs the prediction image.

Hereinafter, each unit included in the intra-prediction image generation unit 310 will be described.

(Prediction target block setting unit 3101)
The prediction target block setting unit 3101 sets the target CU as the prediction target block, and outputs information (prediction target block information) regarding the prediction target block. The prediction target block information includes at least an index indicating the size, position, brightness or color difference of the prediction target block.

(Unfiltered reference image setting unit 3102)
The unfiltered reference image setting unit 3102 is included in a plurality of horizontal lines on the upper side of the target block, a plurality of vertical lines on the left side of the target block, and an area on the upper left of the target block based on the size and position of the prediction target block. The pixel to be used is set as the reference area R. Subsequently, each pixel value (unfiltered reference image, boundary pixel) in the reference area R is set with each decoded pixel value at the corresponding position on the reference picture memory 306.

(Filtered reference image setting unit 3103)
The filtered reference image setting unit 3103 applies a reference pixel filter (first filter) to the unfiltered reference image according to the intra prediction mode, and filters each position (x, y) on the reference area R. Derivation of the reference image s [x] [y]. Specifically, a low-pass filter is applied to the unfiltered reference image at the position (x, y) and its surroundings, and the filtered reference image is derived. It is not always necessary to apply the low-pass filter to all the intra-prediction modes, and the low-pass filter may be applied to some of the intra-prediction modes. In the filtered reference image setting unit 3103, the filter applied to the unfiltered reference image on the reference area R is called a "reference pixel filter (first filter)", whereas in the prediction image correction unit 3105 described later. A filter that corrects a tentatively predicted image is called a "boundary filter (second filter)".

(Structure of Intra Prediction Unit 3104)
The intra prediction unit 3104 generates a tentative prediction image (provisional prediction pixel value, pre-correction prediction image) of the prediction target block based on the intra prediction mode, the unfiltered reference image, and the filtered reference pixel value, and the prediction image correction unit Output to 3105. The intra prediction unit 3104 includes a Planar prediction unit 31041, a DC prediction unit 31042, an Angular prediction unit 31043, and an LM prediction unit 31044 inside. The intra prediction unit 3104 selects a specific prediction unit according to the intra prediction mode, and inputs an unfiltered reference image and a filtered reference image. The relationship between the intra prediction mode and the corresponding prediction unit is as follows.
・ Planar Prediction ・ ・ ・ Planar Prediction Department 31041
・ DC prediction ・ ・ ・ DC prediction unit 31042
・ Angular Prediction ・ ・ ・ Angular Prediction Department 31043
・ LM prediction ・ ・ ・ LM prediction unit 31044
(Planar forecast)
The Planar prediction unit 31041 linearly adds a plurality of filtered reference images according to the distance between the prediction target pixel position and the reference pixel position to generate a tentative prediction image, and outputs the provisional prediction image to the prediction image correction unit 3105.

(DC prediction)
The DC prediction unit 31042 derives a DC prediction value corresponding to the average value of the filtered reference images s [x] [y], and outputs a provisional prediction image q [x] [y] using the DC prediction value as a pixel value. To do.

(Angular prediction)
The Angular prediction unit 31043 generates a tentative prediction image q [x] [y] using the filtered reference images s [x] [y] in the prediction direction (reference direction) indicated by the intra prediction mode, and the prediction image correction unit. Output to 3105.

(LM prediction)
The LM prediction unit 31044 predicts the pixel value of the color difference based on the pixel value of the luminance. Specifically, it is a method of generating a predicted image of a color difference image (Cb, Cr) using a linear model based on a decoded luminance image. LM prediction includes CCLM (Cross-Component Linear Model prediction) prediction and MMLM (Multiple Model ccLM) prediction. CCLM prediction is a prediction method that uses one linear model for predicting the color difference from the luminance for one block. MMLM prediction is a prediction method that uses two or more linear models for predicting the color difference from the luminance for one block.

(Structure of Prediction Image Correction Unit 3105)
The prediction image correction unit 3105 corrects the tentative prediction image output from the intra prediction unit 3104 according to the intra prediction mode. Specifically, the prediction image correction unit 3105 weights and adds the unfiltered reference image and the provisional prediction image to each pixel of the provisional prediction image according to the distance between the reference region R and the target prediction pixel (weighted average). By doing so, the predicted image (corrected predicted image) Pred obtained by modifying the provisional predicted image is derived. In some intra-prediction modes, the prediction image correction unit 3105 may not correct the provisional prediction image, and the output of the intra-prediction unit 3104 may be used as the prediction image as it is.

(Availability setting unit 313)
The availability setting unit (reference sample availability setting unit) 313 sets the image refN [x] [y] that the intra prediction image generation unit 310 refers to when generating the intra prediction image on the target image currSample [] []. Derived from the adjacent image of the target block. Further, the availability setting unit 313 sets the availability of each pixel refN [x] [y], that is, whether it can be used or not for intra prediction. RefN [] [] may be described as refUnfilt [] [] to emphasize that the image is before applying the loop filter.

The availability setting unit 313 derives the adjacent position (xNbTmp, yNbTmp) from the coordinates (xTbCmp, yTbCmp) on the upper left of the target block and the relative position (x, y) from the upper left of the target block by the following equation.

(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
The availability setting unit 313 derives availableN indicating whether or not the pixels of the adjacent block N (xNbY, yNbY) of the target block (xCurr, yCurr) are available. Here, (xCurr, yCurr) is the position of the upper left sample of the target block when the upper left sample of the target picture is the origin. (xNbY, yNbY) is the position included in the adjacent block of the target block when the upper left sample of the target block is the origin. The availability setting unit 313 sets the luminance coordinates of (xCurrY, yCurrY) and (xNbY, yNbY) as follows according to whether or not the color component (cIdx) has the luminance (cIdx = 0). You may.

(xCurr, yCurr) = (xTbY, yTbY) = (cIdx = 0)? (XTbCmp, yTbCmp) :( xTbCmp << 1, yTbCmp << 1)
(xNbY, yNbY) = (cIdx = 0)? (XNbCmp, yNbCmp) :( xNbCmp << 1, yNbCmp << 1)
The availability setting unit 313 sets availableN to FALSE (not available) when (xNbY, yNbY) is not available, and to TRUE (available) when it is available. That is, the availability setting unit 313 derives availableN as FALSE when one or more of the following conditions are true.

xNbY <0
yNbY <0
xNbY> = pic_width_in_luma_samples
yNbY> = pic_height_in_luma_samples
Further, the availability setting unit 313 may further derive availableN as FALSE when the adjacent block and the target pixel are different segments (tiles, etc.). For example, the availability setting unit 313 may derive availableN as FALSE when the tile IDs of (xNbY, yNbY) and (xCurr, yCurr) are different.

The availability setting unit 313 sets (marks) the reference pixel refN [x] [y] to be unavailable for intra-prediction (hereinafter, simply unavailable) when availableN is FALSE, and in other cases. In addition, the reference pixel refN [x] [y] is set (marked) to be usable for intra-prediction (hereinafter, simply available), and the pixel at the position (xNbCmp, yNbCmp) is referred to as the reference pixel refN [x] [y]. May be set to.

The reference image refN [] [], which is set to be unusable, is set to be usable by substituting a substitute pixel by the above-mentioned pixel reference method described above.

(Outline of the configuration example of the availability setting unit 313 in this embodiment)
The availability setting unit 313 may set the pixels included in at least one of the plurality of vertical lines and horizontal lines to be unavailable in the upper left region of the target block. According to the above configuration, the intra prediction image generation unit 310 generates an intra prediction image by referring only to the pixels set to be available by the availability setting unit 313 among the plurality of vertical lines and horizontal lines. May be good. Therefore, there is an effect that the pixels referred to when the intra prediction image is generated do not need to be stored in the line buffer more than necessary.

(Example 1 of pixel selection by the intra prediction image generation unit 310)
The intra prediction image generation unit 310 stores only a part of the pixels (usable pixels) among the pixels included in the upper left area of the target block, and the other pixels (unusable pixels) can be used. It may be generated from various pixels. The intra prediction image generation unit 310 may generate an intra prediction image using the generated reference pixel value. The availability setting unit 313 sets the pixels outside the picture, the undecoded pixels, or the pixels not stored in the line buffer to be unusable, and the decoded pixels or the pixels stored in the line buffer can be used. When set to, the intra prediction image generation unit 310 may derive unusable pixels from available pixels.

Hereinafter, the use pixel selection example 1 will be described in more detail with reference to FIG. Here, the availability setting unit 313 sets the pixels included in the upper left region of the target block, other than the pixels sharing the apex with the target block, to be unusable.

Specifically, as shown in FIG. 10 (c), the availability setting unit 313 sets the pixels (xCurr-1, yCurr-1) of RefLineIdx = 0 included in the area C to be available, and RefLineIdx. Pixels with! = 0 (RefLineIdx> 0) are set to unavailable.

For example, when availableN is FALSE or (RefLineIdx> 0, x <0, and y <0), the availability setting unit 313 sets the reference pixel refN [x] [y] to be unavailable. (Mark) may be used. In other cases, the availability setting unit 313 sets (marks) the reference pixel refN [x] [y] to be available, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [x] [y]. ] May be set.

Further, since the result does not change even if RefLineIdx is not distinguished, when availableN is FALSE or (x <0 and y <0), the availability setting unit 313 uses the reference pixel refN [x] [y]. May be set (marked) as unavailable. In other cases, the availability setting unit 313 sets (marks) the reference pixel refN [x] [y] to be available, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [x] [y]. ] May be set.

Alternatively, when the intra prediction image generation unit 310 derives the position of the reference pixel (xNbCmp, yNbCmp) from the upper left position (xTbCmp, yTbCmp) of the target block and the relative position (x, y) from the upper left position. , When RefLineIdx> 0, x <0, and y <0, the position may be derived from the diagonal position (xTbCmp-1, yTbCmp-1) as in the following equation.
if (RefLineIdx> 0 && x <0 && y <0)
(xNbCmp, yNbCmp) = (xTbCmp-1, yTbCmp-1)
Otherwise
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
Further, the intra prediction image generation unit 310 may derive the RefLineIdx by the following without distinguishing it.
if (x <0 && y <0)
(xNbCmp, yNbCmp) = (xTbCmp-1, yTbCmp-1)
Otherwise
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
Alternatively, the intra prediction image generation unit 310 sets (marks) the reference pixel refN [x] [y] as unavailable when availableN is FALSE, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [ It may be set to xTbCmp-1] [yTbCmp-1]. In other cases, the intra prediction image generation unit 310 sets (marks) the reference pixel refN [x] [y] to be available, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [xTbCmp + x]. It may be set to [yTbCmp + y].

According to the above configuration, when the intra prediction image generation unit 310 refers to the pixels included in the upper left region of the target block, the intra prediction image generation unit 310 can generate the intra prediction image by referring only to the pixels sharing the vertices with the target block. Therefore, in the upper left region of the target block, there is an effect that the same number of pixels as in the case of referencing only the pixels sharing the vertices with the target block need to be stored in the line buffer. That is, the line memory can be reduced.

(Example 2 of pixel selection by the intra prediction image generation unit 310)
Hereinafter, the use pixel selection example 2 will be described with reference to FIG. Here, the availability setting unit 313 cannot use pixels other than the positions where each of the plurality of horizontal lines and each of the plurality of vertical lines intersect among the pixels included in the upper left area of the target block. Set to. That is, the availability setting unit 313 sets the pixels in the upper left region of the target block to be available with the same x-coordinate and y-coordinate.

Specifically, as shown in (d) of FIG. 10, the availability setting unit 313 makes it possible to use pixels in which x-xCurr = y-yCurr, where (x, y) is the pixel in region C. It may be set to disable pixels with x-xCurr! = Y-yCurr.

For example, when availableN is FALSE or (RefLineIdx> 0 and x! = Y), the availability setting unit 313 sets (marks) the reference pixel refN [x] [y] to be unavailable and positions (marks) it. The pixel of xNbCmp, yNbCmp) may be set to the reference pixel refN [x-offset] [y-offset]. In other cases, the availability setting unit 313 sets (marks) the reference pixel refN [x] [y] to be available, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [x] [y]. May be set to.

Here, (x, y) is the relative position from the upper left position of the target block.
x = -1-RefLineIdx, y = (-1-RefLineIdx) .. (refH-1), and
It takes the value of x = (-1-RefLineIdx) .. (refW-1), y = -1-RefLineIdx. However, the width refW and the height refH of the reference pixel may be derived from the width bW and the height bH of the target block by the following equation.

refW = bW * 2
refH = bH * 2
The intra prediction image generation unit 310 generates the pixel value of the pixel set to be unavailable among the pixels included in the upper left region of the target block by using the pixel value of the pixel set to be available. May be good. Further, the intra prediction image generation unit 310 may generate an intra prediction image using the generated pixel values.

For example, when the pixel of the region C is (x, y), the intra prediction image generation unit 310 may derive the pixel value of (x, y) from refN [x] [y] by the following equation. .. currSamples [] [] is the target image.
refN [x] [y] = currSamples [xCurr-offset] [yCurr-offset]
Here, if (x, y) = (xCurr-i, yCurr-j), offset is a value that minimizes abs (i-offset) + abs (j-offset) (however, offset = 1,2, Any of 4).

For example, if RefLineIdx = 1, the value of currSamples [xCurr-2] [yCurr-2] (refN [x] [y] of x = -2, y = -2) is the pixel set to be available. Is the value of. Therefore, the intra-prediction image generator 310 sets the currSamples [xCurr-1] [yCurr-2] (x = -1, y = -2 refN [x] [y]) values to be unavailable. And the values of currSamples [xCurr-2] [yCurr-1] (refN [x] [y] of x = -2, y = -1) are set to available currSamples [xCurr-2] [yCurr- 2] (refN [x] [y] of x = -2, y = -2) or currSamples [xCurr-1] [yCurr-1] (refN [x] [y] of x = -1, y = -1 ]) Is generated using the pixel value.

Alternatively, the intra prediction image generation unit 310 derives the position of the reference pixel (xNbCmp, yNbCmp) from the upper left position (xTbCmp, yTbCmp) of the target block and the relative position (x, y) from the upper left of the target block. As shown in the following formula, when RefLineIdx> 0, x <0, and y <0, the reference pixel is from the diagonal position (xTbCmp- (RefLineIdx + 1), yTbCmp- (RefLineIdx + 1)). The position of may be derived.
if (RefLineIdx> 0 && x <0 && y <0)
(xNbCmp, yNbCmp) = (xTbCmp- (RefLineIdx + 1), yTbCmp- (RefLineIdx + 1))
Otherwise
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
Further, the intra prediction image generation unit 310 may derive the RefLineIdx by the following without distinguishing it.
if (x <0 && y <0)
(xNbCmp, yNbCmp) = (xTbCmp- (RefLineIdx + 1), yTbCmp- (RefLineIdx + 1))
Otherwise
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
Alternatively, the intra prediction image generation unit 310 sets (marks) the reference pixel refN [x] [y] as unavailable when availableN is FALSE, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [ It may be set to xTbCmp- (RefLineIdx + 1)] [yTbCmp- (RefLineIdx + 1)]. In other cases, the reference pixel refN [x] [y] may be set (marked) to be available, and the pixel at the position (xNbCmp, yNbCmp) may be set to the reference pixel refN [x] [y]. here,
x = -1-RefLineIdx, y = (-1-RefLineIdx) .. (refH-1), and
It takes the value of x = (-1-RefLineIdx) .. (refW-1), y = -1-RefLineIdx. However, the width refW and the height refH of the reference pixel may be derived from the width bW and the height bH of the target block by the following equation.

refW = bW * 2
refH = bH * 2
According to the above configuration, when the intra prediction image generation unit 310 refers to the pixels included in the upper left region of the target block, it refers only to the pixels whose distance from (xCb, yCb) is the same in both the x-coordinate and the y-coordinate. And an intra prediction image can be generated. Therefore, in the upper left region of the target block, three times as many pixels as when only the pixels sharing the vertices with the target block are referenced may be stored in the line buffer. This has the effect that it is not necessary to store the pixels referred to when generating the intra prediction image in the line buffer more than necessary.

In one of the above examples, the intra prediction image generation unit 310 uses the formula refN [x] [y] = currSamples [xCurr] to set the pixel value refN [x] [y] of the position (x, y) in the region C. Although it is derived by [offset] [yCurr-offset], it is not limited to this in the present embodiment. For example, the intra prediction image generation unit 310 includes pixels of currSamples [xCurr-offset] [yCurr-offset] (for example, offset = 1,2,4), currSamples [xCurr] [y], and currSamples [x] [yCurr]. ] Pixels may be derived. In the present embodiment, when the pixel of the region C is (x, y), the intra prediction image generation unit 310 sets the pixel value refN [x] [y] of (x, y) by any of the following equations. It may be derived ((e) in FIG. 10).
refN [x] [y] = currSamples [xCurr-1] [yCurr-1]
refN [x] [y] = (currSamples [xCurr-1] [yCurr-1] + currSamples [x] [yCurr]) / 2
refN [x] [y] = (currSamples [xCurr-1] [yCurr-1] + currSamples [xCurr] [y]) / 2
refN [x] [y] = (currSamples [xCurr-1] [yCurr-1] * 2 + currSamples [x] [yCurr] + currSamples [xCurr] [y]) / 4
[Modification example]
The configuration of the intra prediction image generation unit 310 and the availability setting unit 313 is not limited to the above example.

In the present embodiment, the intra prediction image generation unit 310 is a horizontal line on the upper side of the target block, and any one of a plurality of horizontal lines whose distance from the target block is defined by a plurality of predetermined values. An intra prediction image of the target block may be generated by reference. Further, the intra prediction image generation unit 310 refers to any of a plurality of vertical lines on the left side of the target block, each of which is defined by a plurality of predetermined values for the distance from the target block. An intra prediction image of the target block may be generated.

The availability setting unit 313 may set at least one of the pixels included in the horizontal line on the upper right of the target block and the pixels included in the vertical line on the lower left of the target block to be unavailable. ..

The intra prediction image generation unit 310 may generate the pixel value of the pixel set to be unavailable by referring to the pixel value of the pixel set to be available. Then, the intra prediction image generation unit 310 may generate an intra prediction image using the generated pixel values.

Even with the above configuration, the intra prediction image generation unit 310 can generate an intra prediction image by referring only to the pixels set to be available by the availability setting unit 313. Therefore, there is an effect that the line buffer does not need to store the pixels to be referred to when generating the intra prediction image more than necessary.

(Example 3 of pixel selection by the intra prediction image generation unit 310)
Hereinafter, a usage pixel selection example 3 by the availability setting unit 313 will be described with reference to FIG. FIG. 12 is a diagram for explaining an example of setting the availability of each pixel by the availability setting unit 313.

In FIG. 12, the intra prediction image generation unit 310 generates an intra prediction image of the target block b4 with reference to the upper horizontal line and the left vertical line of the target block b4. Further, the availability setting unit 313 sets the pixel D2 included in the upper right horizontal line of the target block b4 and the pixel B2 included in the lower left vertical line of the target block b4 to be unusable.

In this case, the intra prediction image generation unit 310 refers to pixel D2 included in the upper right horizontal line and pixel B2 included in the lower left vertical line among the upper horizontal line and the left vertical line of the target block b4. Intra prediction image can be generated without. This has the effect that it is not necessary to store the pixels referred to when generating the intra prediction image in the line buffer more than necessary.

(Example 4 of pixel selection by the intra prediction image generation unit 310)
Hereinafter, a usage pixel selection example 4 by the availability setting unit 313 will be described with reference to FIG. FIG. 13 is a diagram for explaining an example of setting the availability of each pixel by the availability setting unit 313.

In FIG. 13, the intra prediction image generation unit 310 generates an intra prediction image of the target block b4 with reference to the upper horizontal line and the left vertical line of the target block b4.

In addition, the availability setting unit 313 sets half of the pixel D2 included in the upper right horizontal line of the target block b4 and the pixel B2 included in the lower left vertical line of the target block b4 to be unusable. For example, the availability setting unit 313 is included in the pixel D22 included in the right half of the horizontal line on the upper right of the target block b4 and the vertical line on the lower left of the target block b4, as shown in FIG. 13A. Pixel B22 included in the lower half may be disabled. Further, as shown in (b) of FIG. 13, the availability setting unit 313 can use the pixels included in the upper right horizontal line and the pixels included in the lower left vertical line of the target block b4 every other pixel (D21). , B21) and unavailable (D22, B22).

In this case, the intra prediction image generation unit 310 has half of the pixels included in the upper right horizontal line of the upper horizontal line of the target block b4 and half of the pixels included in the lower left vertical line of the left vertical line. Intra-predicted images can be generated without reference to. This has the effect that it is not necessary to store the pixels referred to when generating the intra prediction image in the line buffer more than necessary.

For example, the intra prediction image generation unit 310 derives the position of the reference pixel (xNbCmp, yNbCmp) from the upper left position (xTbCmp, yTbCmp) of the target block and the relative position (x, y) from the upper left of the target block. When RefLineIdx> 0 and the x coordinate is larger than a predetermined threshold value (for example, bW * 3/2), the intra prediction image generation unit 310 is a position clipped in the x direction as a reference position (xNbCmp, yNbCmp). You may use (xTbCmp + bW * 3 / 2-1, yTbCmp + y). Similarly, the intra prediction image generation unit 310 clips in the y direction as a reference position (xNbCmp, yNbCmp) when RefLineIdx> 0 and the y coordinate is larger than a predetermined threshold value (for example, bH * 3/2). The specified position (xTbCmp + x, yTbCmp + bH * 3 / 2-1) may be used.
if (RefLineIdx> 0 &&x> bW * 3/2)
(xNbCmp, yNbCmp) = (xTbCmp + bW * 3 / 2-1, yTbCmp + y)
Otherwise if (RefLineIdx> 0 &&y> bH * 3/2)
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + bH * 3 / 2-1)
Otherwise
(xNbCmp, yNbCmp) = (xTbCmp + x, yTbCmp + y)
The intra prediction image generation unit 310 sets (marks) the reference pixel refN [x] [y] as unavailable when availableN is FALSE, and sets the pixel at the position (xNbCmp, yNbCmp) as the reference pixel refN [xTbCmp +). It may be set to bW * 3 / 2-1] [yTbCmp + y] or refN [xTbCmp + x] [yTbCmp + bH * 3 / 2-1]. In other cases, the reference pixel refN [x] [y] is set (marked) to be available, and the pixel at the position (xNbCmp, yNbCmp) is set to the reference pixel refN [xTbCmp + x] [yTbCmp + y]. You may. here,
x = -1-RefLineIdx, y = (-1-RefLineIdx) .. (refH-1), and
It takes the value of x = (-1-RefLineIdx) .. (refW-1), y = -1-RefLineIdx. However, the width refW and the height refH of the reference pixel may be derived from the width bW and the height bH of the target block by the following equation.

refW = bW * 2
refH = bH * 2
The inverse quantization / inverse conversion unit 311 inversely quantizes the quantization conversion coefficient input from the entropy decoding unit 301 to obtain the conversion coefficient. This quantization transform coefficient is a coefficient obtained by performing frequency conversion such as DCT (Discrete Cosine Transform) or DST (Discrete Sine Transform) on the prediction error in the coding process. Is. The inverse quantization / inverse conversion unit 311 performs inverse frequency conversion such as inverse DCT and inverse DST on the obtained conversion coefficient, and calculates a prediction error. The inverse quantization / inverse conversion unit 311 outputs the prediction error to the addition unit 312.

The addition unit 312 adds the prediction image of the block input from the prediction image generation unit 308 and the prediction error input from the inverse quantization / inverse conversion unit 311 for each pixel to generate a decoded image of the block. The addition unit 312 stores the decoded image of the block in the reference picture memory 306, and outputs the decoded image to the loop filter 305.

(Configuration of moving image encoding device)
Next, the configuration of the moving image coding device 11 according to the present embodiment will be described. FIG. 14 is a block diagram showing the configuration of the moving image coding device 11 according to the present embodiment. The moving image coding device 11 includes a prediction image generation unit 101, a subtraction unit 102, a conversion / quantization unit 103, an inverse quantization / inverse conversion unit 105, an addition unit 106, a loop filter 107, and a prediction parameter memory (prediction parameter storage unit). , Frame memory) 108, reference picture memory (reference image storage unit, frame memory) 109, coding parameter determination unit 110, parameter coding unit 111, and entropy coding unit 104.

The prediction image generation unit 101 generates a prediction image for each CU, which is a region in which each picture of the image T is divided. The prediction image generation unit 101 has the same operation as the prediction image generation unit 308 described above, and the description thereof will be omitted.

The subtraction unit 102 subtracts the pixel value of the predicted image of the block input from the prediction image generation unit 101 from the pixel value of the image T to generate a prediction error. The subtraction unit 102 outputs the prediction error to the conversion / quantization unit 103.

The conversion / quantization unit 103 calculates the conversion coefficient by frequency conversion with respect to the prediction error input from the subtraction unit 102, and derives the quantization conversion coefficient by quantization. The conversion / quantization unit 103 outputs the quantization conversion coefficient to the entropy coding unit 104 and the inverse quantization / inverse conversion unit 105.

The inverse quantization / inverse conversion unit 105 is the same as the inverse quantization / inverse conversion unit 311 (FIG. 7) in the moving image decoding device 31, and the description thereof will be omitted. The calculated prediction error is output to the addition unit 106.

A quantization conversion coefficient is input to the entropy coding unit 104 from the conversion / quantization unit 103, and a coding parameter is input from the parameter coding unit 111.

The entropy coding unit 104 entropy-encodes the division information, prediction parameters, quantization conversion coefficient, etc. to generate a coded stream Te and outputs it.

The parameter coding unit 111 includes a header coding unit 1110 (not shown), a CT information coding unit 1111, a CU coding unit 1112 (prediction mode coding unit), an inter prediction parameter coding unit 112, and an intra prediction parameter coding unit. It has 113. The CU coding unit 1112 further includes a TU coding unit 1114.

(Structure of Intra Prediction Parameter Encoding Unit 113)
The intra prediction parameter coding unit 113 derives a coding format (for example, intra_luma_mpm_flag, intra_luma_mpm_idx, intra_luma_mpm_remainder, etc.) from the intra prediction mode IntraPredMode input from the coding parameter determination unit 110. The intra prediction parameter coding unit 113 includes a configuration that is partially the same as the configuration in which the intra prediction parameter decoding unit 304 derives the intra prediction parameter.

FIG. 15 is a schematic diagram showing the configuration of the intra-prediction parameter coding unit 113 of the parameter coding unit 111. The intra prediction parameter coding unit 113 includes a parameter coding control unit 1131, a brightness intra prediction parameter derivation unit 1132, a color difference intra prediction parameter derivation unit 1133, and an MRL parameter derivation unit 11324.

The luminance prediction mode IntraPredModeY and the color difference prediction mode IntraPredModeC are input to the parameter coding control unit 1131 from the coding parameter determination unit 110. The parameter coding control unit 1131 determines the intra_luma_mpm_flag by referring to the MPM candidate list mpmCandList [] of the MPM candidate list derivation unit 30421. Then, the intra_luma_mpm_flag and the IntraPredModeY are output to the luminance intra prediction parameter derivation unit 1132. In addition, IntraPredModeC is output to the color difference intra prediction parameter derivation unit 1133.

The brightness intra-prediction parameter derivation unit 1132 includes an MPM candidate list derivation unit 30421 (candidate list derivation unit), an MPM parameter derivation unit 11322, a non-MPM parameter derivation unit 11323, and an MRL parameter derivation unit 11324. ..

The MPM candidate list derivation unit 30421 derives the MPM candidate list mpmCandList [] by referring to the intra prediction mode of the adjacent block stored in the prediction parameter memory 108. The MPM parameter derivation unit 11322 derives intra_luma_mpm_idx from IntraPredModeY and the MPM candidate list mpmCandList [] when intra_luma_mpm_flag is 1, and outputs it to the entropy coding unit 104. The non-MPM parameter derivation unit 11323 derives RemIntraPredMode from IntraPredModeY and the MPM candidate list mpmCandList [] when intra_luma_mpm_flag is 0, and outputs intra_luma_mpm_remaining to the entropy encoding unit 104.

The color difference intra prediction parameter derivation unit 1133 derives chroma_intra_pred_mode from IntraPredModeY and IntraPredModeC and outputs it.

The MRL parameter derivation unit 11324 derives intra_luma_ref_idx from the index RefLineIdx indicating the reference line.

The addition unit 106 generates a decoded image by adding the pixel value of the prediction image of the block input from the prediction image generation unit 101 and the prediction error input from the inverse quantization / inverse conversion unit 105 for each pixel. The addition unit 106 stores the generated decoded image in the reference picture memory 109.

The loop filter 107 applies a deblocking filter, SAO, and ALF to the decoded image generated by the addition unit 106. The loop filter 107 does not necessarily have to include the above three types of filters, and may have, for example, a configuration of only a deblocking filter.

The prediction parameter memory 108 stores the prediction parameters generated by the coding parameter determination unit 110 at predetermined positions for each target picture and CU.

The reference picture memory 109 stores the decoded image generated by the loop filter 107 at a predetermined position for each target picture and CU.

The coding parameter determination unit 110 selects one set from the plurality of sets of coding parameters. The coding parameter is the above-mentioned QT, BT or TT division information, prediction parameter, or a parameter to be coded generated in connection with these. The prediction image generation unit 101 generates a prediction image using these coding parameters.

The coding parameter determination unit 110 calculates an RD cost value indicating the magnitude of the amount of information and the coding error for each of the plurality of sets. The RD cost value is, for example, the sum of the code amount and the squared error multiplied by the coefficient λ. The code amount is the amount of information of the coded stream Te obtained by entropy-coding the quantization error and the coded parameters. The square error is the sum of squares of the prediction error calculated by the subtraction unit 102. The coefficient λ is a real number greater than the preset zero. The coding parameter determination unit 110 selects the set of coding parameters that minimizes the calculated cost value. As a result, the entropy coding unit 104 outputs the selected set of coding parameters as the coding stream Te. The coding parameter determination unit 110 stores the determined coding parameter in the prediction parameter memory 108.

A part of the moving image coding device 11 and the moving image decoding device 31 in the above-described embodiment, for example, the entropy decoding unit 301, the parameter decoding unit 302, the loop filter 305, the predicted image generation unit 308, and the inverse quantization / reverse. Conversion unit 311, Addition unit 312, Prediction image generation unit 101, Subtraction unit 102, Conversion / quantization unit 103, Entropy coding unit 104, Inverse quantization / inverse conversion unit 105, Loop filter 107, Coding parameter determination unit 110 , The parameter coding unit 111 may be realized by a computer. In that case, the program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. The "computer system" referred to here is a computer system built in any of the moving image coding device 11 and the moving image decoding device 31, and includes hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Furthermore, a "computer-readable recording medium" is a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In that case, a program may be held for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client. Further, the above-mentioned program may be a program for realizing a part of the above-mentioned functions, and may be a program for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

[Additional notes]
A part or all of the moving image coding device 11 and the moving image decoding device 31 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the moving image coding device 11 and the moving image decoding device 31 may be made into a processor individually, or a part or all of them may be integrated into a processor. Further, the method of making an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, when an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like are made without departing from the gist of the present invention. It is possible to do.

[Application example]
The moving image coding device 11 and the moving image decoding device 31 described above can be mounted on and used in various devices for transmitting, receiving, recording, and reproducing moving images. The moving image may be a natural moving image captured by a camera or the like, or an artificial moving image (including CG and GUI) generated by a computer or the like.

First, it will be described with reference to FIG. 2 that the moving image coding device 11 and the moving image decoding device 31 described above can be used for transmitting and receiving moving images.

FIG. 2A is a block diagram showing the configuration of the transmission device PROD_A equipped with the moving image coding device 11. As shown in the figure, the transmitter PROD_A has a coding unit PROD_A1 that obtains encoded data by encoding a moving image, and a modulation signal by modulating a carrier with the coded data obtained by the coding unit PROD_A1. It includes a modulation unit PROD_A2 to obtain and a transmission unit PROD_A3 to transmit the modulation signal obtained by the modulation unit PROD_A2. The moving image coding device 11 described above is used as the coding unit PROD_A1.

The transmitter PROD_A has a camera PROD_A4 for capturing a moving image, a recording medium PROD_A5 for recording a moving image, an input terminal PROD_A6 for inputting a moving image from the outside, and a moving image as a source of the moving image to be input to the coding unit PROD_A1. , An image processing unit A7 for generating or processing an image may be further provided. In the figure, the configuration in which the transmitter PROD_A is provided with all of these is illustrated, but some of them may be omitted.

The recording medium PROD_A5 may be a recording of an unencoded moving image, or a moving image encoded by a recording coding method different from the transmission coding method. It may be a thing. In the latter case, a decoding unit (not shown) that decodes the coded data read from the recording medium PROD_A5 according to the recording coding method may be interposed between the recording medium PROD_A5 and the coding unit PROD_A1.

FIG. 2B is a block diagram showing the configuration of the receiving device PROD_B equipped with the moving image decoding device 31. As shown in the figure, the receiving device PROD_B is obtained by a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains coded data by demodulating the modulated signal received by the receiving unit PROD_B1, and a demodulating unit PROD_B2. It includes a decoding unit PROD_B3 that obtains a moving image by decoding the coded data. The moving image decoding device 31 described above is used as the decoding unit PROD_B3.

The receiving device PROD_B is a display PROD_B4 for displaying the moving image, a recording medium PROD_B5 for recording the moving image, and an output terminal for outputting the moving image to the outside as a supply destination of the moving image output by the decoding unit PROD_B3. It may also have PROD_B6. In the figure, the configuration in which the receiving device PROD_B is provided with all of these is illustrated, but some of them may be omitted.

The recording medium PROD_B5 may be used for recording an unencoded moving image, or may be encoded by a recording encoding method different from the transmission coding method. You may. In the latter case, a coding unit (not shown) that encodes the moving image acquired from the decoding unit PROD_B3 according to the recording coding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

The transmission medium for transmitting the modulated signal may be wireless or wired. Further, the transmission mode for transmitting the modulated signal may be broadcasting (here, a transmission mode in which the destination is not specified in advance) or communication (here, transmission in which the destination is specified in advance). Refers to an aspect). That is, the transmission of the modulated signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a broadcasting station (broadcasting equipment, etc.) / receiving station (television receiver, etc.) of terrestrial digital broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals by radio broadcasting. Further, a broadcasting station (broadcasting equipment, etc.) / receiving station (television receiver, etc.) of cable television broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives modulated signals by wired broadcasting.

In addition, servers (workstations, etc.) / clients (television receivers, personal computers, smartphones, etc.) for VOD (Video On Demand) services and video sharing services using the Internet are transmitters that send and receive modulated signals via communication. This is an example of PROD_A / receiver PROD_B (usually, in LAN, either wireless or wired is used as a transmission medium, and in WAN, wired is used as a transmission medium). Here, personal computers include desktop PCs, laptop PCs, and tablet PCs. Smartphones also include multifunctional mobile phone terminals.

The client of the video sharing service has a function of decoding the encoded data downloaded from the server and displaying it on the display, as well as a function of encoding the moving image captured by the camera and uploading it to the server. That is, the client of the video sharing service functions as both the transmitting device PROD_A and the receiving device PROD_B.

Next, it will be described with reference to FIG. 3 that the moving image coding device 11 and the moving image decoding device 31 described above can be used for recording and reproducing a moving image.

FIG. 3A is a block diagram showing the configuration of the recording device PROD_C equipped with the above-mentioned moving image coding device 11. As shown in the figure, the recording device PROD_C has a coding unit PROD_C1 that obtains coded data by encoding a moving image and a writing unit PROD_C2 that writes the coded data obtained by the coding unit PROD_C1 to the recording medium PROD_M. And have. The moving image coding device 11 described above is used as the coding unit PROD_C1.

The recording medium PROD_M may be of a type built in the recording device PROD_C, such as (1) HDD (Hard Disk Drive) or SSD (Solid State Drive), or (2) SD memory. It may be a type that is connected to the recording device PROD_C, such as a card or USB (Universal Serial Bus) flash memory, or (3) DVD (Digital Versatile Disc: registered trademark) or BD (Blu-ray). It may be loaded in a drive device (not shown) built in the recording device PROD_C, such as Disc (registered trademark).

Further, the recording device PROD_C has a camera PROD_C3 that captures a moving image, an input terminal PROD_C4 for inputting a moving image from the outside, and a reception for receiving the moving image as a source of the moving image to be input to the coding unit PROD_C1. The unit PROD_C5 and the image processing unit PROD_C6 for generating or processing an image may be further provided. In the figure, the configuration provided by the recording device PROD_C is illustrated, but some of them may be omitted.

The receiving unit PROD_C5 may receive an unencoded moving image, or receives coded data encoded by a transmission coding method different from the recording coding method. It may be something to do. In the latter case, a transmission decoding unit (not shown) that decodes the coded data encoded by the transmission coding method may be interposed between the receiving unit PROD_C5 and the coding unit PROD_C1.

Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, an HDD (Hard Disk Drive) recorder, and the like (in this case, the input terminal PROD_C4 or the receiving unit PROD_C5 is the main source of moving images). .. In addition, a camcorder (in this case, the camera PROD_C3 is the main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 or the image processing unit C6 is the main source of moving images), and a smartphone (this In this case, the camera PROD_C3 or the receiving unit PROD_C5 is the main source of moving images), etc. are also examples of such a recording device PROD_C.

FIG. 3B is a block showing the configuration of the playback device PROD_D equipped with the above-mentioned moving image decoding device 31. As shown in the figure, the playback device PROD_D includes a reading unit PROD_D1 that reads the coded data written in the recording medium PROD_M, and a decoding unit PROD_D2 that obtains a moving image by decoding the coded data read by the reading unit PROD_D1. , Is equipped. The moving image decoding device 31 described above is used as the decoding unit PROD_D2.

The recording medium PROD_M may be of a type built into the playback device PROD_D, such as (1) HDD or SSD, or (2) such as an SD memory card or USB flash memory. It may be of a type connected to the playback device PROD_D, or may be loaded into a drive device (not shown) built in the playback device PROD_D, such as (3) DVD or BD. Good.

Further, the playback device PROD_D has a display PROD_D3 for displaying the moving image, an output terminal PROD_D4 for outputting the moving image to the outside, and a transmitting unit for transmitting the moving image as a supply destination of the moving image output by the decoding unit PROD_D2. It may also have PROD_D5. In the figure, the configuration in which the playback device PROD_D is provided with all of these is illustrated, but some of them may be omitted.

The transmission unit PROD_D5 may transmit an unencoded moving image, or transmits coded data encoded by a transmission coding method different from the recording coding method. It may be something to do. In the latter case, it is preferable to interpose a coding unit (not shown) that encodes the moving image by a coding method for transmission between the decoding unit PROD_D2 and the transmitting unit PROD_D5.

Examples of such a playback device PROD_D include a DVD player, a BD player, an HDD player, and the like (in this case, the output terminal PROD_D4 to which a television receiver or the like is connected is the main supply destination of the moving image). .. In addition, a television receiver (in this case, display PROD_D3 is the main supply destination of moving images) and digital signage (also called electronic signage or electronic bulletin board, etc., and display PROD_D3 or transmitter PROD_D5 is the main supply destination of moving images. (First), desktop PC (in this case, output terminal PROD_D4 or transmitter PROD_D5 is the main supply destination of moving images), laptop or tablet PC (in this case, display PROD_D3 or transmitter PROD_D5 is video) An example of such a playback device PROD_D is a smartphone (in this case, the display PROD_D3 or the transmitter PROD_D5 is the main supply destination of the moving image), which is the main supply destination of the image.

(Hardware realization and software realization)
Further, each block of the moving image decoding device 31 and the moving image coding device 11 described above may be realized in hardware by a logic circuit formed on an integrated circuit (IC chip), or may be realized by hardware, or a CPU (Central Processing). It may be realized by software using Unit).

In the latter case, each of the above devices is a CPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the above program, a RAM (Random Access Memory) that expands the above program, the above program, and various types. It is equipped with a storage device (recording medium) such as a memory for storing data. Then, an object of the embodiment of the present invention is a record in which the program code (execution format program, intermediate code program, source program) of the control program of each of the above devices, which is software for realizing the above-mentioned functions, is recorded readable by a computer. It can also be achieved by supplying the medium to each of the above devices and having the computer (or CPU or MPU) read and execute the program code recorded on the recording medium.

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and CD-ROMs (Compact Disc Read-Only Memory) / MO disks (Magneto-Optical discs). ) / MD (Mini Disc) / DVD (Digital Versatile Disc: registered trademark) / CD-R (CD Recordable) / Blu-ray Disc (registered trademark) and other disks including magneto-optical disks, IC cards (memory cards) ) / Cards such as optical cards, mask ROM / EPROM (Erasable Programmable Read-Only Memory) / EEPROM (Electrically Erasable and Programmable Read-Only Memory: registered trademark) / semiconductor memory such as flash ROM, or PLD ( Logic circuits such as Programmable logic device) and FPGA (Field Programmable Gate Array) can be used.

Further, each of the above devices may be configured to be connectable to a communication network, and the above program code may be supplied via the communication network. This communication network is not particularly limited as long as it can transmit the program code. For example, Internet, Intranet, Extranet, LAN (Local Area Network), ISDN (Integrated Services Digital Network), VAN (Value-Added Network), CATV (Community Antenna television / Cable Television) communication network, Virtual Private network (Virtual Private) Network), telephone line network, mobile communication network, satellite communication network, etc. can be used. Further, the transmission medium constituting this communication network may be any medium as long as it can transmit the program code, and is not limited to a specific configuration or type. For example, even wired such as IEEE (Institute of Electrical and Electronic Engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared data such as IrDA (Infrared Data Association) and remote control , BlueTooth (registered trademark), IEEE802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance: registered trademark), mobile phone network, satellite line, terrestrial digital broadcasting network, etc. It is also available wirelessly. The embodiment of the present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

The embodiment of the present invention is suitably applied to a moving image decoding device that decodes coded data in which image data is encoded, and a moving image coding device that generates coded data in which image data is encoded. be able to. Further, it can be suitably applied to the data structure of the coded data generated by the moving image coding device and referenced by the moving image decoding device.

31 Video decoding device (image decoding device)
301 Entropy Decryptor
302 Parameter decoder
303 Inter prediction parameter decoding unit
304 Intra Prediction Parameter Decoder
308 Prediction image generator
309 Inter-prediction image generator
310 Intra prediction image generator
311 Inverse quantization / inverse conversion
312 Addition part
313 Availability Settings (Reference Sample Availability Settings)
11 Image encoder
101 Prediction image generator
102 Subtraction section
103 Conversion / Quantization Department
104 Entropy encoding section
105 Inverse quantization / inverse conversion
107 Loop filter
110 Coded parameter determination unit
111 Parameter encoding section
112 Inter-prediction parameter encoding section
113 Intra Prediction Parameter Encoding Unit
b1, b2, b3, b4 target block

Claims (6)

Reference sample availability setting unit that sets the availability of each pixel,
It is provided with an intra-prediction image generation unit that generates an intra-prediction image by referring to the pixels set to be available by the above reference sample availability setting unit.
The above intra-prediction image generation unit
Any of a plurality of horizontal lines above the target block whose distance from the target block is defined by a plurality of predetermined values.
One of a plurality of vertical lines on the left side of the target block whose distance from the target block is defined by the plurality of predetermined values, and
The target block with reference to any of the pixels included in the upper left region of the target block, which includes pixels at positions where each of the plurality of horizontal lines intersects with each of the plurality of vertical lines. It generates an intra-prediction image of
The reference sample availability setting unit is characterized in that, in the upper left region of the target block, pixels included in at least one of the plurality of vertical lines and horizontal lines are set to be unusable. Image decoding device. The above reference sample availability setting section
The image decoding apparatus according to claim 1, wherein among the pixels included in the upper left region of the target block, pixels other than the pixels sharing the apex with the target block are set to be unusable. The above reference sample availability setting section
Of the pixels included in the upper left area of the target block,
The image decoding apparatus according to claim 1, wherein pixels other than the positions where each of the plurality of horizontal lines and each of the plurality of vertical lines intersects are set to be unusable. The above intra-prediction image generation unit
Of the pixels included in the upper left area of the target block, the pixel values of the pixels set to be unavailable are generated using the pixel values of the pixels set to be available.
The image decoding apparatus according to claim 3, wherein an intra-predicted image is generated using the generated pixel values. Reference sample availability setting unit that sets the availability of each pixel,
It is provided with an intra-prediction image generation unit that generates an intra-prediction image by referring to the pixels set to be available by the above reference sample availability setting unit.
The above intra-prediction image generation unit
A horizontal line on the upper side of the target block, whichever is one of a plurality of horizontal lines whose distance from the target block is defined by a plurality of predetermined values, and a vertical line on the left side of the target block. Any of a plurality of vertical lines whose distance from the target block is defined by each of the above-mentioned predetermined values.
Is used to generate an intra-prediction image of the above target block.
The above reference sample availability setting section
An image decoding apparatus characterized in that at least one of the pixels included in the horizontal line on the upper right of the target block and the pixels included in the vertical line on the lower left of the target block is set to be unavailable. .. The above intra-prediction image generation unit
A claim characterized in that a pixel value of a pixel set to be unavailable is generated with reference to a pixel value of a pixel set to be available, and an intra prediction image is generated using the generated pixel value. The image decoding apparatus according to 5.

Images