WO2012043676A1

WO2012043676A1 - Decoding device, encoding device, and data structure

Info

Publication number: WO2012043676A1
Application number: PCT/JP2011/072280
Authority: WO
Inventors: 将伸八杉; 山本　智幸; 知宏猪飼
Original assignee: シャープ株式会社
Priority date: 2010-09-29
Filing date: 2011-09-28
Publication date: 2012-04-05

Abstract

An intra-prediction image generation unit (12c) specifies a prediction mode and a prediction mode group, and when the specified prediction mode group is a first prediction mode group, a prediction parameter corresponding to the prediction mode specified by the aforementioned prediction mode specification means is selected from a first prediction parameter group, and when the specified prediction mode group is a second prediction mode group, a prediction parameter corresponding to the prediction mode specified by the aforementioned prediction mode specification means is selected from a second prediction parameter group.

Description

Decoding device, encoding device, and data structure

The present invention relates to a decoding device that decodes encoded data and an encoding device that generates encoded data. The present invention also relates to the data structure of encoded data generated by the encoding device and referenced by the decoding device.

In order to efficiently transmit or record a moving image, a moving image encoding device (encoding device) that generates encoded data by encoding the moving image, and decoding by decoding the encoded data A video decoding device (decoding device) that generates an image is used. As a specific moving picture encoding method, for example, H.264 is used. H.264 / MPEG-4. AVC (Non-Patent Document 1), VCEG (Video Coding Expert Group) adopted by KTA software, which is a codec for joint development, and TMuC (Test Model Under Consideration) software, a successor codec. There are some methods.

In such an encoding method, an image (picture) constituting a moving image is a slice obtained by dividing the image, a coding unit obtained by dividing the slice (macroblock or coding unit (Coding Unit)) And is managed by a hierarchical structure composed of blocks and partitions obtained by dividing an encoding unit, and is normally encoded block by block.

In such an encoding method, a predicted image is usually generated based on a local decoded image obtained by encoding / decoding an input image, and a difference image (“residual” between the predicted image and the input image is generated. (Sometimes referred to as “difference image” or “prediction residual”). As methods for generating a predicted image, methods called inter-screen prediction (inter prediction) and intra-screen prediction (intra prediction) are known.

In inter prediction, a prediction image in a prediction target frame is generated for each prediction unit by applying motion compensation using a motion vector to a reference image in a reference frame (decoded image) obtained by decoding the entire frame. Is done.

On the other hand, in intra prediction, predicted images in the frame are sequentially generated based on locally decoded images in the same frame. H. H.264 / MPEG-4. As an example of intra prediction used in AVC, any prediction direction is selected from prediction directions included in a predetermined prediction direction group for each prediction unit (for example, partition), and a locally decoded image is used. And a method of generating a pixel value on the prediction unit by extrapolating the pixel value of the reference pixel in the selected prediction direction (sometimes referred to as “basic prediction”).

In Non-Patent Document 2, for each prediction unit, an edge direction is calculated based on pixel values of pixels around the prediction unit, and a pixel value of a reference pixel in the locally decoded image is extrapolated to the calculated edge direction. Thus, a method of generating a pixel value on the prediction unit (a method called Differential Coding of Intra Modes (DCIM), sometimes called “edge prediction” or “edge-based prediction”) is disclosed.

Hereinafter, the method disclosed in Non-Patent Document 2 will be described in more detail with reference to (a) to (c) of FIG. (A) of FIG. 10 is a diagram schematically showing a prediction unit CurrentBlock to be processed and pixels located around the prediction unit.

According to the method disclosed in Non-Patent Document 2, first, for each pixel located in the vicinity of the prediction unit, an edge vector a _i (i = 1 to N, N is the total number of surrounding pixels to be referred to). Calculated. Here, a Sobel operator (also referred to as a Sobel filter) is used to calculate the edge vector a _i .

Subsequently, the function S (θ) shown below
S (θ) = Σ <e, a _i > ²
Is defined. Here, e represents a unit vector whose angle between the direction of itself and the horizontal direction is θ, and the symbol <,> represents the inner product of both vectors. The symbol Σ indicates that a sum from 1 to N is taken for the subscript i.

Subsequently, an argument θ ^* that maximizes the function S (θ) ^.
θ ^* = argmaxS (θ)
Is calculated, and the direction represented by θ ^* is set as the predicted direction. Finally, the pixel value on the prediction unit is generated by extrapolating the pixel value of the reference pixel in the prediction direction. Here, the argument θ ^* that maximizes the function S (θ) is also referred to as “neighbors' suggested prediction direction”. Note that the calculation of the argument θ ^* is performed in both the encoding device and the decoding device, and thus the argument θ ^* itself is not encoded.

Further, according to the method disclosed in Non-Patent Document 2, the direction represented by θ ^* + Δθ can be used as the prediction direction. Here, Δθ indicates direction adjustment, and Δθ used in the encoding device needs to be encoded and transmitted to the decoding device. Specifically, Δθ is quantized using a quantization step size δθ, and the following quantization index k
k = Δθ / δθ
Are encoded. The decoding apparatus sets θ ^* + k × δθ as the prediction direction. FIG. 10B shows an example of the prediction direction specified by the quantization index k (k = −2, −1, 0, 1, 2).

Further, in the method disclosed in Non-Patent Document 2, intra prediction using the edge-based prediction described above is performed, or H.264 / MPEG-4. A 1-bit flag specifying whether to perform basic prediction used in AVC is encoded for each prediction unit.

(C) of FIG. 10 is a table showing each syntax disclosed in Non-Patent Document 2 together with a descriptor associated with each syntax. Descriptor ae (v) shown in (c) of FIG. 10 indicates that the syntax associated with the descriptor is arithmetically encoded.

The syntax use_neighbor_dir shown in (c) of FIG. H.264 / MPEG-4. This is a flag for designating one of AVC basic predictions.

In the decoding apparatus, first, the flag use_neighbor_dir is decoded first, and when the flag use_neighbor_dir indicates that edge-based prediction is used, the syntax adjust_neighbor_dir representing the quantization index k described above is decoded. . On the other hand, when the flag use_neighbor_dir indicates that edge-based prediction is not used, the syntax most_prob_mode is decoded. Here, the syntax most_prob_mode is a flag indicating whether or not the estimated prediction mode estimated from the prediction mode used for prediction of a partition around the target partition is the same as the prediction mode of the target partition. When the syntax most_prob_mode indicates that the estimated prediction mode is not the same as the prediction mode of the target partition, the syntax rem_intra_pred_mode that specifies the prediction mode assigned to the target partition is subsequently decoded.

As described above, according to the method disclosed in Non-Patent Document 2, edge-based prediction or H.264 H.264 / MPEG-4. An intra-predicted image is generated by selectively using one of basic predictions used in AVC. Further, when edge-based prediction is used, only the quantization index k needs to be encoded. Therefore, when edge-based prediction is frequently used in the generation of a predicted image, H.264 is used. H.264 / MPEG-4. Compared to the case where only basic prediction used in AVC is used, the amount of encoded data can be reduced.

However, edge-based prediction may not be frequently used depending on the characteristics of the image to be encoded. In the method disclosed in Non-Patent Document 2, even in such a case, edge-based prediction and H.264 H.264 / MPEG-4. Since it is necessary to encode a flag that designates one of basic predictions used in AVC, there has been a problem that the amount of encoded data is not reduced or not as much as expected.

The present invention has been made in view of the above-mentioned problems, and the object thereof is edge-based prediction or H.264. H.264 / MPEG-4. Encoding apparatus, decoding apparatus, and encoded data capable of reducing the code amount of encoded data while selectively improving any one of basic predictions used in AVC It is to realize the data structure.

In order to solve the above problem, the decoding apparatus according to the present invention specifies a prediction mode set element composed of a first prediction mode group element and a second prediction mode group element by a single code. A decoding device that decodes encoded data obtained by encoding together with prediction mode designation information, and generates a decoded image by adding a prediction image generated for each prediction unit to a prediction residual decoded from the encoded data. A prediction mode specifying means for specifying a prediction mode specified by the prediction mode specification information from the code according to a predetermined correspondence between the code and a prediction mode specified by the code; And a prediction mode designated by the prediction mode designation information from the code in accordance with a predetermined correspondence relationship between the prediction mode group to which the prediction mode designated by the code belongs. A prediction mode group specifying means for specifying a prediction mode group to which the user belongs, and a prediction parameter selection means for selecting a prediction parameter, wherein the prediction mode group specified by the prediction mode group specifying means is the first prediction mode group Selecting a prediction parameter corresponding to the prediction mode specified by the prediction mode specifying means from a first prediction parameter group consisting of one or more prediction parameters corresponding to the first prediction mode group, and the prediction mode group specifying means When the prediction mode group specified by is the second prediction mode group, the prediction mode specifying means includes the second prediction parameter group including one or more predetermined prediction parameters corresponding to the second prediction mode group. A prediction parameter selection means for selecting a prediction parameter corresponding to the prediction mode specified by the prediction parameter, and a prediction parameter selected by the prediction parameter selection means. Depending on the parameters is characterized in that it comprises a, the predicted image generating means for generating the predicted image.

The prediction mode designation information included in the encoded data decoded by the decoding apparatus configured as described above includes elements of a prediction mode set including elements of the first prediction mode group and elements of the second prediction mode group. Is specified by a single code. In addition, the prediction mode group specifying unit included in the decoding device has the prediction mode designation information from the code according to a predetermined correspondence relationship between the code and a prediction mode group to which the prediction mode designated by the code belongs. A prediction mode group to which the designated prediction mode belongs is specified. Therefore, in the encoded data decoded by the decoding apparatus configured as described above, the prediction modes to be referred to when generating a prediction image are the first prediction mode group and the second prediction mode group. Of these, a code for designating which prediction mode group belongs is not necessary.

Therefore, the encoded data referred to by the decoding apparatus configured as described above selectively uses the prediction parameter belonging to the first prediction mode group and the prediction parameter belonging to the second prediction mode group. Generating a prediction image requires a code for designating which prediction mode group the prediction mode to be referred to when generating the prediction image belongs while improving the prediction accuracy of the prediction image Compared with the structure to perform, reduction of the code amount of coding data can be aimed at.

Note that the prediction unit may be a PU (Prediction Unit) described in the embodiment, or may be a partition obtained by dividing the PU.

An encoding apparatus according to the present invention is an encoding apparatus that generates encoded data by encoding residual data between an original image and a predicted image generated for each prediction unit, and includes a prediction parameter. Prediction parameter selection means for selecting a prediction parameter for selecting a prediction parameter from a first prediction parameter group consisting of one or more prediction parameters or a second prediction parameter group consisting of one or more predetermined prediction parameters The parameter selection means, the prediction image generation means for generating the prediction image according to the prediction parameter selected by the prediction parameter selection means, and the prediction mode corresponding to the prediction parameter selected by the prediction parameter selection means by a single code Prediction mode specification information encoding means for encoding the prediction mode specification information to be specified, and the single code Are elements of a first prediction mode group consisting of prediction modes corresponding to the first prediction parameter group and elements of a second prediction mode group consisting of prediction modes corresponding to each element of the second prediction parameter group It is characterized in that the elements of the prediction mode set consisting of

According to the coding apparatus according to the present invention configured as described above, prediction is performed by selectively using the prediction parameter belonging to the first prediction mode group and the prediction parameter belonging to the second prediction mode group. By generating an image, the prediction accuracy of the predicted image can be improved. In addition, since the prediction mode corresponding to the selected prediction parameter is specified by a single code, encoded data with a small code amount can be generated.

Note that the prediction unit may be a PU (Prediction Unit) described in the embodiment or a partition obtained by dividing the PU.

The following encoded data structure is also included in the scope of the present invention.

In a data structure of encoded data generated by encoding residual data between an original image and a predicted image generated for each prediction unit, a prediction parameter to be selected by the decoding device to generate a predicted image is set. Prediction mode designation information that designates a corresponding prediction mode by a single code, and the single code is determined in advance as an element of a first prediction mode group consisting of prediction modes corresponding to one or more prediction parameters. A data structure of encoded data, characterized in that elements of a prediction parameter set comprising elements of a second prediction mode group consisting of a prediction mode corresponding to each of the predicted parameters are identified from each other.

As described above, the decoding apparatus according to the present invention uses the residual data between the original image and the prediction image generated for each prediction unit as the elements of the first prediction mode group and the elements of the second prediction mode group. A decoding apparatus that decodes encoded data obtained by encoding together with prediction mode specifying information that specifies elements of a prediction mode set consisting of a single code, and the prediction mode specified by the code and the code; A prediction mode specifying means for specifying a prediction mode specified by the prediction mode specifying information from the code according to a predetermined correspondence relationship between the code and a prediction mode group to which the prediction mode specified by the code and the code belongs. Prediction mode group specifying means for specifying a prediction mode group to which the prediction mode specified by the prediction mode specification information belongs from the code according to a predetermined correspondence relationship between Prediction parameter selection means for selecting a meter, and when the prediction mode group specified by the prediction mode group specifying means is the first prediction mode group, the prediction parameter selection means includes one or more prediction parameters derived with reference to a decoded image. When the prediction parameter corresponding to the prediction mode specified by the prediction mode specifying unit is selected from the first prediction parameter group, and the prediction mode group specified by the prediction mode group specifying unit is the second prediction mode group, A prediction parameter selection unit that selects a prediction parameter corresponding to the prediction mode specified by the prediction mode specification unit from a second prediction parameter group that includes one or more predetermined prediction parameters, and a prediction parameter selection unit selected And a predicted image generating means for generating the predicted image according to a prediction parameter. .

According to the decoding apparatus of the present invention, a code for designating which prediction mode group a prediction mode to be referred to when generating a prediction image belongs while improving the prediction accuracy of the prediction image Compared to a configuration that requires the above, the amount of encoded data can be reduced.

It is a flowchart which shows the flow of the production | generation process of the intra estimated image by the moving image decoding apparatus which concerns on embodiment of this invention. The data structure of the encoding data produced | generated by the moving image encoder which concerns on the 1st Embodiment of this invention, and referred by the moving image decoder which concerns on embodiment of this invention, Comprising: (a) FIG. 4 is a diagram illustrating a configuration of a picture layer of encoded data, (b) is a diagram illustrating a configuration of a slice layer included in the picture layer, and (c) is a configuration of an LCU layer included in the slice layer. (D) is a figure which shows the structure of the leaf CU contained in a CU layer, (e) is a figure which shows the structure of the inter prediction information about leaf CU. (F) is a figure which shows the structure of the intra prediction information about leaf CU. It is a block diagram which shows the structure of the moving image decoding apparatus which concerns on embodiment of this invention. It is a figure for demonstrating operation | movement of the moving image decoding apparatus which concerns on embodiment of this invention, Comprising: (a) is prediction mode which the moving image decoding apparatus which concerns on embodiment of this invention refers, Comprising: It is a figure which shows the prediction mode contained in the extended set which consists of basic prediction mode and one edge-based prediction mode with a prediction mode index, (b) is the pixel which belongs to an object partition, and its periphery decoded It is a figure which shows a pixel. In the moving image decoding apparatus which concerns on embodiment of this invention, it is a figure for demonstrating the production | generation process of an intra estimated image when edge base prediction mode is selected, Comprising: (a) is object partition. (B) is a figure which shows the parameter which designates a correction angle with the prediction direction after correction | amendment. It is for demonstrating the prediction mode determination process in the moving image decoding apparatus which concerns on embodiment of this invention, Comprising: (a) is encoded by the moving image encoder which concerns on embodiment of this invention, and this invention It is a table | surface which shows the structure of the intra prediction parameter referred by the moving image decoding apparatus which concerns on embodiment of this, (b) is determined about the prediction mode allocated to the partition of the periphery of an object partition, and an object partition It is a figure which shows the example of estimated prediction mode, (c) is a table | surface which shows the example of the correspondence of a prediction mode index, estimated prediction mode, and syntax rem_intra_pred_mode ', (d) is syntax rem_intra_pred_mode'. It is a table | surface which shows the example of the binary code allocated to each value of. It is a flowchart which shows the flow of the production | generation process of the intra estimated image by the moving image decoding apparatus which concerns on a comparative example. It is for demonstrating the prediction mode determination process in the moving image decoding apparatus which concerns on the modification of embodiment of this invention, Comprising: (a) is the prediction mode which the moving image decoding apparatus which concerns on a modification refers. FIG. 4 is a diagram illustrating prediction modes included in an extended set including a plurality of basic prediction modes and a plurality of edge-based prediction modes, together with a prediction mode index, and FIG. 5B is referenced by a video decoding device according to a modified example. It is a figure which shows the structure of the intra prediction parameter to perform. It is a block diagram which shows the structure of the moving image encoder which concerns on embodiment of this invention. In the conventional moving image decoding apparatus, it is a figure for demonstrating the production | generation process of an intra prediction image when edge-based prediction mode is selected, Comprising: (a) is a target partition with the periphery partition of a target partition. (B) is a figure which shows the parameter which designates a correction angle with the prediction direction after correction | amendment, (c) shows the structure of the intra prediction parameter which the conventional moving image decoding apparatus refers to. It is a table. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating that the moving image decoding apparatus and moving image encoding apparatus which concern on embodiment of this invention can be utilized for transmission / reception of a moving image, (a) is the transmitter which mounts a moving image encoding apparatus FIG. 2B is a block diagram showing a configuration of a receiving device equipped with a video decoding device. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating that the moving image decoding apparatus and moving image encoding apparatus which concern on embodiment of this invention can be utilized for recording and reproduction | regeneration of a moving image, (a) is mounted with the moving image encoding apparatus. It is the block diagram which showed the structure of the recording device, (b) is the block which showed the structure of the reproducing | regenerating apparatus carrying a moving image decoding apparatus.

Embodiments of a decoding apparatus and an encoding apparatus according to the present invention will be described below with reference to the drawings. Note that the decoding apparatus according to the present embodiment decodes a moving image from encoded data. Therefore, hereinafter, this is referred to as “moving image decoding apparatus”. In addition, the encoding device according to the present embodiment generates encoded data by encoding a moving image. Therefore, in the following, this is referred to as a “video encoding device”.

However, the scope of application of the present invention is not limited to this. That is, as will be apparent from the following description, the feature of the present invention lies in intra prediction, and is established without assuming a plurality of frames. That is, the present invention can be applied to a general decoding apparatus and a general encoding apparatus regardless of whether the target is a moving image or a still image.

(Configuration of encoded data # 1)
Prior to the description of the moving picture decoding apparatus 1 according to the present embodiment, the configuration of the encoded data # 1 generated by the moving picture encoding apparatus 2 according to the present embodiment and decoded by the moving picture decoding apparatus 1 will be described with reference to FIG. Will be described with reference to FIG. The encoded data # 1 has a hierarchical structure including a sequence layer, a GOP (Group Of Pictures) layer, a picture layer, a slice layer, and a maximum coding unit (LCU: Large Coding Unit) layer.

FIG. 2 shows the hierarchical structure below the picture layer in the encoded data # 1. FIGS. 2A to 2F are a picture layer P, a slice layer S, an LCU layer LCU, a leaf CU included in the LCU (denoted as CUL in FIG. 2D), and inter prediction (inter-screen prediction), respectively. It is a figure which shows the structure of inter prediction information PI_Inter which is the prediction information PI about a partition, and intra prediction information PI_Intra which is the prediction information PI about an intra prediction (prediction in a screen) partition.

(Picture layer)
The picture layer P is a set of data that is referenced by the video decoding device 1 in order to decode a target picture that is a processing target picture. As shown in FIG. 2A, the picture layer P includes a picture header PH and slice layers S1 to SNs (Ns is the total number of slice layers included in the picture layer P).

The picture header PH includes a coding parameter group that is referred to by the video decoding device 1 in order to determine a decoding method of the target picture. For example, the encoding mode information (entropy_coding_mode_flag) indicating the variable length encoding mode used in encoding by the moving image encoding device 2 is an example of an encoding parameter included in the picture header PH. When entropy_coding_mode_flag is 0, the picture is CAVLC (Context-based Adaptive Variable Length Coding).
When entropy_coding_mode_flag is 1, the picture is encoded by CABAC (Context-based Adaptive Binary Arithmetic Coding).

(Slice layer)
Each slice layer S included in the picture layer P is a set of data referred to by the video decoding device 1 in order to decode a target slice that is a slice to be processed. As shown in FIG. 2B, the slice layer S includes a slice header SH and LCU layers LCU1 to LCUn (Nc is the total number of LCUs included in the slice S).

The slice header SH includes a coding parameter group that the moving image decoding apparatus 1 refers to in order to determine a decoding method of the target slice. Slice type designation information (slice_type) for designating a slice type is an example of an encoding parameter included in the slice header SH. Further, the slice header SH includes a filter parameter FP that is referred to by a loop filter included in the video decoding device 1.

As slice types that can be specified by the slice type specification information, (1) I slice using only intra prediction at the time of encoding, and (2) P using unidirectional prediction or intra prediction at the time of encoding. Slice, (3) B-slice using unidirectional prediction, bidirectional prediction, or intra prediction at the time of encoding.

(LCU layer)
Each LCU layer LCU included in the slice layer S is a set of data that the video decoding device 1 refers to in order to decode the target LCU that is the processing target LCU.

The LCU layer LCU is composed of a plurality of coding units (CU: Coding Units) obtained by hierarchically dividing the LCU into a quadtree. In other words, the LCU layer LCU is a coding unit corresponding to the highest level in a hierarchical structure that recursively includes a plurality of CUs. As shown in FIG. 2C, each CU included in the LCU layer LCU has a hierarchical structure that recursively includes a CU header CUH and a plurality of CUs obtained by dividing the CU into quadtrees. is doing.

The size of each CU excluding the LCU is half the size of the CU to which the CU directly belongs (that is, the CU one layer higher than the CU), and the size that each CU can take is encoded data # 1. Dependent on the size and hierarchical depth of the LCU included in the sequence parameter set SPS. For example, when the size of the LCU is 128 × 128 pixels and the maximum hierarchical depth is 5, the CUs in the hierarchical level below the LCU have five sizes, that is, 128 × 128 pixels and 64 × 64 pixels. , 32 × 32 pixels, 16 × 16 pixels, and 8 × 8 pixels. A CU that is not further divided is called a leaf CU.

(CU header)
The CU header CUH includes a coding parameter referred to by the video decoding device 1 in order to determine a decoding method of the target CU. Specifically, as shown in FIG. 2C, a CU division flag SP_CU that specifies whether or not the target CU is further divided into four subordinate CUs is included. When the CU division flag SP_CU is 0, that is, when the CU is not further divided, the CU is a leaf CU.

(Leaf CU)
A CU (CU leaf) that is not further divided is handled as a prediction unit (PU: Prediction Unit) and a transform unit (TU: Transform Unit).

As shown in FIG. 2 (d), the leaf CU (denoted as CUL in FIG. 2 (d)) includes (1) PU information PUI that is referred to when the moving image decoding apparatus 1 generates a predicted image, and (2) The TU information TUI that is referred to when the residual data is decoded by the moving picture decoding apparatus 1 is included.

The skip flag SKIP is a flag indicating whether or not the skip mode is applied to the target PU. When the value of the skip flag SKIP is 1, that is, when the skip mode is applied to the target leaf, PU information PUI and TU information TUI in the leaf CU are omitted. Note that the skip flag SKIP is omitted for the I slice.

The PU information PUI includes a skip flag SKIP, prediction type information PT, and prediction information PI as shown in FIG. The prediction type information PT is information that specifies whether intra prediction or inter prediction is used as a predicted image generation method for the target leaf CU (target PU). The prediction information PI includes intra prediction information PI_Intra or inter prediction information PI_Inter depending on which prediction method is specified by the prediction type information PT. Hereinafter, a PU to which intra prediction is applied is also referred to as an intra PU, and a PU to which inter prediction is applied is also referred to as an inter PU.

The PU information PUI includes information specifying the shape and size of each partition included in the target PU and the position in the target PU. Here, the partition is one or a plurality of non-overlapping areas constituting the target leaf CU, and the generation of the predicted image is performed in units of partitions.

As shown in FIG. 2D, the TU information TUI specifies a quantization parameter difference Δqp (tu_qp_delta) that specifies the magnitude of the quantization step, and a division pattern for each block of the target leaf CU (target TU). TU partition information SP_TU and quantized prediction residuals QD1 to QDNT (NT is the total number of blocks included in the target TU) are included.

The quantization parameter difference Δqp is a difference qp−qp ′ between the quantization parameter qp in the target TU and the quantization parameter qp ′ in the TU encoded immediately before the TU.

TU partition information SP_TU is information that specifies the shape and size of each block included in the target TU and the position in the target TU. Each TU can be, for example, a size from 64 × 64 pixels to 2 × 2 pixels. Here, the block is one or a plurality of non-overlapping areas constituting the target leaf CU, and encoding / decoding of the prediction residual is performed in units of blocks.

Each quantized prediction residual QD is encoded data generated by the moving image encoding apparatus 2 performing the following processes 1 to 3 on a target block that is a processing target block. Process 1: DCT transform (Discrete Cosine Transform) is performed on the prediction residual obtained by subtracting the prediction image from the encoding target image. Process 2: The DCT coefficient obtained in Process 1 is quantized. Process 3: The DCT coefficient quantized in Process 2 is variable length encoded. The quantization parameter qp described above represents the magnitude of the quantization step QP used when the moving picture coding apparatus 2 quantizes the DCT coefficient (QP = 2 ^{qp / 6} ).

(Inter prediction information PI_Inter)
The inter prediction information PI_Inter includes a coding parameter that is referred to when the video decoding device 1 generates an inter prediction image by inter prediction. As shown in FIG. 2 (e), the inter prediction information PI_Inter includes inter PU partition information SP_Inter that specifies a partition pattern for each partition of the target PU, and inter prediction parameters PP_Inter1 to PP_InterNe (Ne for each partition). The total number of inter prediction partitions included in the target PU).

Specifically, the inter-PU partition information SP_Inter is information for designating the shape and size of each inter prediction partition included in the target PU (inter PU) and the position in the target PU.

The inter PU is composed of four symmetric splittings of 2N × 2N pixels, 2N × N pixels, N × 2N pixels, and N × N pixels, and 2N × nU pixels, 2N × nD pixels, and nL × 2N. It is possible to divide into 8 types of partitions in total by four asymmetric splits of pixels and nR × 2N pixels. Here, the specific value of N is defined by the size of the CU to which the PU belongs, and the specific values of nU, nD, nL, and nR are determined according to the value of N. For example, an inter PU of 128 × 128 pixels is 128 × 128 pixels, 128 × 64 pixels, 64 × 128 pixels, 64 × 64 pixels, 128 × 32 pixels, 128 × 96 pixels, 32 × 128 pixels, and 96 × It is possible to divide into 128-pixel inter prediction partitions.

(Inter prediction parameter)
As illustrated in FIG. 2E, the inter prediction parameter PP_Inter includes a reference image index RI, an estimated motion vector index PMVI, and a motion vector residual MVD.

(Intra prediction information PI_Intra)
The intra prediction information PI_Intra includes an encoding parameter that is referred to when the video decoding device 1 generates an intra predicted image by intra prediction. As shown in FIG. 2 (f), the intra prediction information PI_Intra includes intra PU partition information SP_Intra that specifies a partition pattern of the target PU (intra PU) into each partition, and intra prediction parameters PP_Intra1 to PP_IntraNa for each partition. (Na is the total number of intra prediction partitions included in the target PU).

Specifically, the intra-PU partition information SP_Intra is information that specifies the shape and size of each intra-predicted partition included in the target PU, and the position in the target PU. The intra PU split information SP_Intra includes an intra split flag (intra_split_flag) that specifies whether or not the target PU is split into partitions. If the intra partition flag is 1, the target PU is divided symmetrically into four partitions. If the intra partition flag is 0, the target PU is not divided and the target PU itself is one partition. Are treated as Therefore, if the size of the target PU is 2N × 2N pixels, the intra prediction partition can take any of 2N × 2N pixels (no division) and N × N pixels (four divisions) (where, N = 2 ⁿ , n is an arbitrary integer of 1 or more). For example, a 128 × 128 pixel intra PU can be divided into 128 × 128 pixel and 64 × 64 pixel intra prediction partitions.

(Intra prediction parameter PP_Intra)
As shown in FIG. 2F, the intra prediction parameter PP_Intra includes an estimation flag MPM, a residual prediction mode index RIPM, and an additional index AI. The intra prediction parameter PP_Intra is a parameter for designating an intra prediction method (prediction mode) for each partition.

The estimation flag MPM is a flag indicating whether or not the prediction mode estimated based on the prediction mode allocated to the peripheral partition of the target partition that is the processing target is the same as the prediction mode for the target partition. . Here, examples of partitions around the target partition include a partition adjacent to the upper side of the target partition and a partition adjacent to the left side of the target partition.

The residual prediction mode index RIPM is an index included in the intra prediction parameter PP_Intra when the estimated prediction mode and the prediction mode for the target partition are different, and is an index for designating a prediction mode assigned to the target partition. It is.

The additional index AI is an index for specifying the intra prediction method for the target partition in more detail when the prediction mode assigned to the target partition is a predetermined prediction mode.

(Moving picture decoding apparatus 1)
Hereinafter, the moving picture decoding apparatus 1 according to the present embodiment will be described with reference to FIGS. The moving picture decoding apparatus 1 includes H.264 as a part thereof. H.264 / MPEG-4. Decoding device including technology adopted in KTA software which is a codec for joint development in AVC and VCEG (Video Coding Expert Group), and technology adopted in TMuC (Test Model under Consideration) software which is a successor codec It is.

FIG. 3 is a block diagram showing a configuration of the moving picture decoding apparatus 1. As illustrated in FIG. 3, the video decoding device 1 includes a variable length code decoding unit 11, a predicted image generation unit 12, an inverse quantization / inverse conversion unit 13, an adder 14, a frame memory 15, and a loop filter 16. I have. As shown in FIG. 3, the predicted image generation unit 12 includes a motion vector restoration unit 12a, an inter predicted image generation unit 12b, an intra predicted image generation unit 12c, and a prediction method determination unit 12d. The moving picture decoding apparatus 1 is an apparatus for generating moving picture # 2 by decoding encoded data # 1.

(Variable-length code decoding unit 11)
The variable length code decoding unit 11 decodes the prediction parameter PP related to each partition from the encoded data # 1, and supplies the decoded prediction parameter PP to the predicted image generation unit 12. Specifically, for the inter prediction partition, the variable length code decoding unit 11 receives the inter prediction parameter PP_Inter including the reference image index RI, the estimated motion vector index PMVI, and the motion vector residual MVD from the encoded data # 1. These are decoded and supplied to the motion vector restoration unit 12a. On the other hand, for the intra prediction partition, the intra prediction parameter PP_Intra including the estimation flag MPM, the residual index RIPM, and the additional index AI is decoded from the encoded data # 1, and these are supplied to the intra prediction image generation unit 12c. In addition, the variable length code decoding unit 11 supplies size designation information for designating the size of the partition to the intra predicted image generation unit 12c (not shown).

Also, the variable length code decoding unit 11 decodes the prediction type information PT for each partition from the encoded data # 1, and supplies this to the prediction method determination unit 12d. Further, the variable length code decoding unit 11 decodes the quantization prediction residual QD for each block and the quantization parameter difference Δqp for the TU including the block from the encoded data # 1, and performs inverse quantization / inverse This is supplied to the conversion unit 13. Further, the variable length code decoding unit 11 decodes the filter parameter FP from the encoded data # 1 and supplies this to the loop filter 16.

As a specific decoding method by the variable-length code decoding unit 11, CABAC (Context-based Adaptive Binary Arithmetic Coding) which is one arithmetic coding / decoding method, or one non-arithmetic encoding / decoding method is used. A certain CAVLC (Context-based Adaptive Variable Variable Length Coding) is used. Here, CABAC is an encoding / decoding scheme that performs adaptive binary arithmetic coding based on context, and CALVC is an encoding / decoding scheme that uses a set of variable length codes that adaptively switch contexts. It is. CABAC has a larger code amount reduction effect than CAVLC, but also has an aspect of increasing the processing amount.

The variable length code decoding unit 11 refers to the encoding mode information (entropy_coding_mode_flag) included in the picture header PH of the encoded data # 1 to determine whether the target picture has been encoded by CABAC or by CAVLC. Can be identified. In addition, the variable length code decoding unit 11 decodes the target picture using a decoding method corresponding to the identified encoding method.

(Predicted image generation unit 12)
The predicted image generation unit 12 identifies whether each partition is an inter prediction partition for performing inter prediction or an intra prediction partition for performing intra prediction based on the prediction type information PT for each partition. In the former case, the inter prediction image Pred_Inter is generated, and the generated inter prediction image Pred_Inter is supplied to the adder 14 as the prediction image Pred. In the latter case, the intra prediction image Pred_Intra is generated, The generated intra predicted image Pred_Intra is supplied to the adder 14. Note that, when the skip mode is applied to the processing target PU, the predicted image generation unit 12 omits decoding of other parameters belonging to the PU.

(Motion vector restoration unit 12a)
The motion vector restoration unit 12a restores the motion vector mv related to each inter prediction partition from the motion vector residual MVD related to that partition and the restored motion vector mv ′ related to another partition. Specifically, (1) the estimated motion vector pmv is derived from the restored motion vector mv ′ according to the estimation method specified by the estimated motion vector index PMVI, and (2) the derived estimated motion vector pmv and the motion vector remaining are derived. The motion vector mv is obtained by adding the difference MVD. It should be noted that the restored motion vector mv ′ relating to other partitions can be read from the frame memory 15. The motion vector restoration unit 12a supplies the restored motion vector mv to the inter predicted image generation unit 12b together with the corresponding reference image index RI.

(Inter prediction image generation unit 12b)
The inter prediction image generation unit 12b generates a motion compensated image mc related to each inter prediction partition by inter-screen prediction. Specifically, using the motion vector mv supplied from the motion vector restoration unit 12a, the motion compensation image mc from the filtered decoded image P_ALF ′ designated by the reference image index RI supplied from the motion vector restoration unit 12a. Is generated. Here, the filtered decoded image P_ALF ′ is an image obtained by performing the filtering process by the loop filter 16 on the decoded image that has already been decoded for the entire frame, and the inter predicted image generation unit 12b. Can read out the pixel value of each pixel constituting the filtered decoded image P_ALF ′ from the frame memory 15. The motion compensated image mc generated by the inter predicted image generation unit 12b is supplied to the prediction method determination unit 12d as an inter predicted image Pred_Inter.

(Intra predicted image generation unit 12c)
The intra predicted image generation unit 12c generates a predicted image Pred_Intra related to each intra prediction partition. Specifically, first, a prediction mode is specified based on the intra prediction parameter PP_Intra supplied from the variable length code decoding unit 11, and the specified prediction mode is assigned to the target partition in, for example, raster scan order. Subsequently, a predicted image Pred_Intra is generated from the (local) decoded image P by intra prediction according to the prediction method indicated by the prediction mode. The intra predicted image Pred_Intra generated by the intra predicted image generation unit 12c is supplied to the prediction method determination unit 12d. Note that the intra predicted image generation unit 12c may be configured to generate the predicted image Pred_Intra from the filtered decoded image P_ALF by intra prediction.

Since the method of generating the intra predicted image Pred_Intra by the intra predicted image generation unit 12c will be described later, the description thereof is omitted here.

(Prediction method determination unit 12d)
The prediction method determination unit 12d determines whether each partition is an inter prediction partition that should perform inter prediction or an intra prediction partition that should perform intra prediction based on the prediction type information PT about the PU to which each partition belongs. To do. In the former case, the inter prediction image Pred_Inter generated by the inter prediction image generation unit 12b is supplied to the adder 14 as the prediction image Pred. In the latter case, the inter prediction image generation unit 12c generates the inter prediction image Pred_Inter. The intra predicted image Pred_Intra that has been processed is supplied to the adder 14 as the predicted image Pred.

(Inverse quantization / inverse transform unit 13)
The inverse quantization / inverse transform unit 13 (1) inversely quantizes the quantized prediction residual QD, (2) performs inverse DCT (Discrete Cosine Transform) transform on the DCT coefficient obtained by the inverse quantization, and (3) The prediction residual D obtained by the inverse DCT transform is supplied to the adder 14. When the quantization prediction residual QD is inversely quantized, the inverse quantization / inverse transform unit 13 derives the quantization step QP from the quantization parameter difference Δqp supplied from the variable length code decoding unit 11. The quantization parameter qp can be derived by adding the quantization parameter difference Δqp to the quantization parameter qp ′ relating to the TU that has been inversely quantized / inversely DCT transformed immediately before, and the quantization step QP is derived from the quantization step qp, for example, QP = 2 ^{pq / 6} . The generation of the prediction residual D by the inverse quantization / inverse transform unit 13 is performed in units of blocks obtained by dividing TUs or TUs.

(Adder 14)
The adder 14 generates the decoded image P by adding the prediction image Pred supplied from the prediction image generation unit 12 and the prediction residual D supplied from the inverse quantization / inverse conversion unit 13. The generated decoded image P is stored in the frame memory 15.

(Loop filter 16)
The loop filter 16 reads the decoded image P from the frame memory 15 and performs block noise reduction processing at one or both of the partition boundary and the block boundary of the decoded image P. In addition, the loop filter 16 performs adaptive filter processing using the filter parameter FP decoded from the encoded data # 1 on the decoded image subjected to the block noise reduction processing, and the adaptive filter processing Is output to the frame memory 15 as a filtered decoded image P_ALF.

(Generation process of intra prediction image Pred_Intra by intra prediction image generation unit 12c)
Hereinafter, the intra-prediction image Pred_Intra generation processing by the intra-prediction image generation unit 12c will be described with reference to different drawings.

The intra-predicted image generation unit 12c (1) a basic prediction mode that designates one or more predetermined prediction directions and DC prediction, and (2) calculation using pixel values around the target partition Prediction mode that determines the prediction direction by, for example, an edge whose prediction direction is the edge direction calculated from pixel values around the target partition (or the direction represented by the sum of the angle indicated by the edge direction and the correction angle) Based on the prediction mode specified by the intra prediction parameter PP_Intra among the base prediction modes, the intra prediction image Pred_Intra in the target partition is generated.

In other words, the intra-predicted image generation unit 12c is designated by an intra-prediction parameter PP_Intra from a set of prediction modes (hereinafter also referred to as “extended set”) including one or a plurality of basic prediction modes and an edge-based prediction mode. A prediction mode to be selected is selected, and an intra prediction image Pred_Intra in the target partition is generated based on the selected prediction mode.

Hereinafter, a set of basic prediction modes that specify one or more predetermined prediction directions and DC prediction is also referred to as a basic prediction mode set. That is, the extended set includes a prediction mode included in the basic prediction mode set and an edge-based prediction mode.

(A) of FIG. 4 is a figure which shows each prediction mode contained in an extended set with the prediction mode index attached | subjected to each said prediction mode. 4A shows each direction prediction mode belonging to the basic prediction mode set and the prediction direction indicated by each direction prediction mode. As shown in FIG. 4A, the edge-based prediction mode is specified by index 1, and the DC prediction mode included in the basic prediction mode is specified by index 0, and each directional prediction included in the basic prediction mode set is included. The mode is specified by indexes 2-9.

Note that the information indicating the correspondence between each index and each prediction mode, and the information indicating the correspondence between each direction prediction mode belonging to the basic prediction mode set and each prediction direction are moving images that generate encoded data # 1. A common configuration can be used for both the image encoding device and the moving image decoding device 1 that decodes the encoded data # 1. The moving picture decoding apparatus 1 stores such information in its own memory, and whether the prediction mode specified by the decoded index is the edge-based prediction mode, the DC prediction mode, or It is possible to identify the direction prediction mode, and when the prediction mode specified by the decoded index is the direction prediction mode, which prediction direction the direction prediction mode specifies. Can be identified.

The information indicating the correspondence between each index and each prediction mode, and the information indicating the correspondence between each direction prediction mode belonging to the basic prediction mode set and each prediction direction are, for example, for each sequence, for each picture, or Further, a configuration may be adopted in which, for each slice, transmission is performed from the moving image encoding device to the moving image decoding device 1.

In FIG. 4A, the edge-based prediction mode is assigned to index 1, but the present embodiment is not limited to this, and the characteristics of the image to be decoded and the edge-based prediction mode are An optimum index can be assigned according to the frequency selected. For example, in the configuration in which the prediction mode specified by a smaller index among the prediction modes assigned to the partitions around the target partition is set as the estimated prediction mode for the target partition, the prediction mode with the smaller index is selected. Will be more frequent. In the case of such a configuration, when the decoding target image includes many edges, it is preferable to assign a smaller index to the edge-based prediction mode. On the other hand, when the prediction mode having a smaller index is selected at a higher frequency and the image to be decoded includes many edges, the edge-based prediction mode is selected. It is preferable to assign a larger index to this.

Further, in FIG. 4A, the case where the basic prediction mode set includes a prediction mode that specifies any one of eight different direction predictions is taken as an example, but the present embodiment is limited to this. Is not to be done. For example, as the basic prediction mode set, a set including a prediction mode that specifies any of nine or more different directions may be used. As such an example, for example, a set including a prediction mode for designating any of 16 different directions and a prediction mode for designating any of 32 different directions can be given.

In addition, as a prediction mode included in the basic prediction mode set, one of one or more predetermined directions or one or more non-directional prediction modes (for example, DC prediction) is designated. The present embodiment is not limited by the number of prediction modes included in the basic prediction mode set.

In the following, first, the intra-predicted image generation unit 12c will specifically describe the processing for generating the intra-predicted image Pred_Intra in the edge-based prediction mode and the basic prediction mode, and then refer to the intra-predicted image generation unit 12c. Each syntax included in the intra-prediction parameter PP_Intra to be performed and a specific flow of the intra-prediction image Pred_Intra generation process by the intra-prediction image generation unit 12c will be described.

(Prediction image calculation processing in edge-based prediction mode)
First, prediction image calculation processing by the intra-prediction image generation unit 12c in the edge-based prediction mode will be specifically described with reference to (a) to (b) of FIG.

FIG. 5A shows the target partition OP together with the partitions NP2 and NP3 adjacent to the target partition OP and the partition NP1 sharing the top left vertex of the target partition. FIG. 5A shows a case where the target partition OP and the partitions NP1 to NP3 are all 4 × 4 pixels, but the present embodiment is not limited to this, and the target partition OP is four. The present invention can also be applied when the size is other than × 4 pixels or when the partitions NP1 to NP3 are other than 4 × 4 pixels. It is assumed that the pixel values of the pixels included in the partitions NP1 to NP3 shown in FIG. 5A have been decoded.

First, the intra predicted image generation unit 12c calculates edge vectors b _i (i = 1 to M, M is the total number of pixels included in the partitions NP1 to 3) for each pixel included in the partitions NP1 to NP3. Here, the calculation of the edge vectors b _i is Sobel operator (Sobel operators, also referred to as a Sobel filter) Gx, and may be used to Gy. Here, the Sobel filters Gx and Gy are filter matrices used for calculating the image gradient along the x direction and the image gradient along the y direction, respectively. For example, as a 3 × 3 matrix, ,

Given by. The intra predicted image generation unit 12c calculates, as the edge direction, a direction orthogonal to the calculated image gradient in the x direction and the image gradient represented by the image gradient along the y direction.

Subsequently, the intra predicted image generation unit 12c has a function T (α) shown below.
T (α) = Σ <e, b _i > ²
Define Here, e represents a unit vector whose angle between its own direction and the horizontal direction (x direction) is α, and the symbol <,> represents the inner product of both vectors. The symbol Σ indicates that the subscript i is to be summed from 1 to M.

Subsequently, the intra predicted image generation unit 12c sets an argument α ^* that maximizes the function T (α) ^.
α ^* = argmaxS (α)
And the direction represented by α ^* is set to the edge direction for the target partition. In the above description, it is assumed that the angle α and the angle α ^* are represented with the horizontal right direction being 0 degrees and the clockwise direction being positive (the same applies to the expression of the following angles).

In addition, when the encoded data # 1 includes a syntax adjust_neighb_dir (second code) described later, the intra predicted image generation unit 12c corrects the angle (direction correction) indicated by the syntax adjust_neighb_dir. Δα is added to the angle indicated by the edge direction calculated for the target partition, and the direction represented by α ^* + Δα is set as the prediction direction for the target partition.

The correction angle Δα is given by Δα = t × δα, for example, where the value indicated by the syntax adjust_neighb_dir is represented by t. Here, δα represents a quantization step size for designating the roughness of quantization when the correction angle is quantized. In this embodiment, δα is a certainty factor s shown below.

As a function of, it is calculated for each partition individually. The quantization step size δα has a property that it is a decreasing function of the certainty factor s. In addition, the intra predicted image generation unit 12c may be configured to use, for example, a predetermined quantization step size δα instead of the configuration in which the quantization step size δα is calculated individually for each partition. Further, in the video encoding device that generates the encoded data # 1, the quantization step size δα is encoded for each slice or for each LCU, the quantization step is included in the encoded data # 1, and the intra prediction image The generation unit 12c may be configured to use the quantization step size δα decoded from the encoded data # 1.

FIG. 5B shows an example of the prediction direction specified by the value t (t = −2, −1, 0, 1, 2) indicated by the syntax adjust_neighb_dir.

In the edge-based prediction mode, the intra-predicted image generation unit 12c extrapolates the decoded pixel values for pixels around the target partition in the prediction direction determined as described above, so that An intra prediction image Pred_Intra is generated. Note that if there are decoded pixels on both sides along the prediction direction, the intra predicted image Pred_Intra may be generated by interpolating the pixel values of these pixels.

For example, the intra-predicted image generation unit 12c sets the pixel among the decoded pixels that are located on the virtual line segment that faces the reverse direction of the prediction direction, starting from the pixel position of the prediction target pixel in the target partition. The intra predicted image Pred_Intra in the target partition is generated by setting the pixel value of the closest pixel (hereinafter also referred to as the closest pixel) to the pixel value of the prediction target pixel. Further, the pixel value of the prediction target pixel may be a value calculated using the pixel value of the nearest pixel and the pixel values of the pixels around the nearest pixel.

In the above description, when the intra predicted image generation unit 12c calculates the edge direction, the partition adjacent to the upper side of the target partition, the partition adjacent to the left side of the target partition, and the upper left vertex of the target partition are shared. Although the case where the pixel values of the pixels belonging to the partition to be referred to is taken as an example, the present embodiment is not limited to this, and the intra-predicted image generation unit 12c is more generally set around the target partition. The edge direction can be calculated with reference to the decoded pixel values belonging to the reference region.

(Prediction image calculation processing in basic prediction mode)
Next, the prediction image generation processing by the intra prediction image generation unit 12c in the basic prediction mode will be specifically described.

When the DC prediction mode is selected for the target partition, the intra predicted image generation unit 12c generates an intra predicted image Pred_Intra for the target partition by taking an average value of decoded pixel values around the target partition. .

Further, when the direction prediction mode designated by any of the indexes 2 to 9 is selected, the intra predicted image generation unit 12c decodes the periphery of the target partition along the prediction direction indicated by the selected direction prediction mode. The intra predicted image Pred_Intra for the target partition is generated by extrapolating the completed pixel values. Note that if there are decoded pixels on both sides along the prediction direction, the intra predicted image Pred_Intra may be generated by interpolating the pixel values of these pixels.

Hereinafter, with reference to FIG. 4B, an example of a predicted image calculation process performed by the intra predicted image generation unit 12c will be described in more detail. In the following example, the description will be made on the assumption that the size of the target partition is 4 × 4 pixels, but this does not limit the present embodiment.

FIG. 4B is a diagram showing each pixel (prediction target pixel) of the target partition, which is 4 × 4 pixels, and pixels (reference pixels) around the target partition. As shown in FIG. 4B, the prediction target pixels are denoted by a to p, the reference pixels are denoted by A to M, and the pixel X (X is any of a to p or A to M). Let the pixel value be represented by X. Further, it is assumed that the reference pixels A to M have all been decoded.

(Prediction mode 0)
When the index of the allocated prediction mode is 0 (DC prediction), the intra predicted image generation unit 12c converts the pixel values a to p into the following formulas a to p = ave (A, B, C, D, I, J, K, L)
Generate by. Here, ave (...) Indicates that an element included in parentheses is averaged.

(Prediction mode 2)
When the allocated prediction mode index is 2, the intra-predicted image generation unit 12c converts the pixel values a to p into the following formulas a, e, i, m = A,
b, f, j, n = B,
c, g, k, o = C,
d, h, l, p = D
Generate by.

(Prediction mode 5)
When the allocated prediction mode index is 5, the intra-predicted image generation unit 12c converts the pixel values a to p into the following expression d = (B + (C × 2) + D + 2) >> 2,
c, h = (A + (B × 2) + C + 2) >> 2,
b, g, l = (M + (A × 2) + B + 2) >> 2,
a, f, k, p = (I + (M × 2) + A + 2) >> 2,
e, j, o = (J + (I × 2) + M + 2) >> 2,
i, n = (K + (J × 2) + I + 2) >> 2,
m = (L + (K × 2) + J + 2) >> 2
Generate by. Here, “>>” represents a right shift operation, and for any positive integer x, s, the value of x >> s is equal to the value obtained by rounding down the decimal part of x ÷ (2 ＾ s).

Also, the intra predicted image generation unit 12c can calculate the pixel values a to p by the same method for the basic prediction modes other than the above prediction modes.

In addition, the intra predicted image generation unit 12c generates an intra predicted image Pred_Intra in the edge-based prediction mode by performing substantially the same process as described above using the prediction direction calculated in the edge-based prediction mode. Can do.

(Syntax included in the intra prediction parameter PP_Intra)
Next, with reference to FIGS. 6A to 6C, the syntax included in the intra prediction parameter PP_Intra referred to by the intra predicted image generation unit 12c will be described in detail.

6A is a diagram showing each syntax included in the intra prediction parameter PP_Intra (indicated as read_intra_pred_mode () in FIG. 6A) together with a corresponding descriptor. As shown in FIG. 6A, the intra prediction parameter PP_Intra includes the syntax most_prob_mode ′, rem_intra_pred_mode ′, and adjust_neighb_dir. Each syntax is associated with one of a descriptor ae (v) and a descriptor vlc (v). Here, the descriptor ae (v) is obtained by performing arithmetic coding (CABAC coding) on the syntax associated with the descriptor by the moving picture coding apparatus that generates the coded data # 1. The descriptor vlc has been subjected to non-arithmetic coding (CAVLC coding) in the moving picture coding apparatus that generates the coded data # 1. It is a thing. In particular, vlc (1) is 1-bit fixed length coding, and vlc (v) is variable length coding.

The syntax most_prob_mode ′ shown in (a) of FIG. 6 includes an estimated prediction mode estimated for the target partition based on prediction modes assigned to the peripheral partitions of the target partition, and a prediction mode for the target partition. The syntax is 1 when they are the same, and 0 when the estimated prediction mode is different from the prediction mode for the target partition. The syntax most_prob_mode ′ corresponds to the estimation flag MPM described above.

As the estimated prediction mode, for example, among the prediction mode index allocated to the partition adjacent to the upper side of the target partition and the prediction mode index allocated to the partition adjacent to the left side of the target partition, A prediction mode specified by a small index can be used.

FIG. 6B shows a prediction mode in which a prediction mode with an index of 1 is assigned to a partition adjacent to the upper side of the target partition, and a prediction mode of 5 with respect to a partition adjacent to the left side of the target partition. It is a figure which shows the case where is allocated. In the example shown in FIG. 6B, a prediction mode with an index of 1 is used as the estimated prediction mode for the target partition.

The syntax rem_intra_pred_mode ′ shown in FIG. 6A is a syntax included in the intra prediction parameter PP_Intra when the estimated prediction mode is different from the prediction mode for the target partition, and is assigned to the target partition. Is a syntax for specifying the prediction mode to be performed. The syntax rem_intra_pred_mode 'corresponds to the above-described residual prediction mode index RIPM.

(C) of FIG. 6 is a table | surface which shows a response | compatibility with each value of syntax rem_intra_pred_mode ', and each prediction mode index, when an estimated prediction mode is a prediction mode designated by the index 1. FIG. As shown in (c) of FIG. 6, an estimated prediction mode (prediction mode specified by index 1 in (c) of FIG. 6) among the prediction modes included in the extended set by the syntax rem_intra_pred_mode ′. Any prediction mode is specified except for. Therefore, when the number of prediction modes included in the extended set is 10, rem_intra_pred_mode ′ specifies any one of the nine prediction modes excluding the estimated prediction mode among the ten prediction modes. become.

(D) of FIG. 6 is a table exemplifying the correspondence between each possible value (0 to 8) of the syntax rem_intra_pred_mode 'and each binary code (Binary Code) included in the encoded data # 1. As shown in FIG. 6D, the syntax rem_intra_pred_mode ′ = 0 to 6 corresponds to a 3-bit code, and the syntax rem_intra_pred_mode ′ = 7, 8 corresponds to a 4-bit code. Correspond.

As described above, in the configuration using the prediction mode specified by the smaller index among the prediction modes allocated to the peripheral partitions of the target partition as the estimated prediction mode, the prediction mode having a smaller index has a higher frequency. Tend to be selected. Therefore, in the example shown in (d) of FIG. 6, a code having a larger number of bits is assigned to a prediction mode that is selected less frequently (prediction mode specified by the syntax rem_intra_pred_mode ′ = 7, 8). It is done. Thus, by assigning a code having a variable code length according to the frequency selected, an increase in the code amount of encoded data # 1 can be suppressed.

Note that the method of specifying the prediction mode by the syntax rem_intra_pred_mode ′ is not limited to the above-described example. For example, the prediction mode with low usage frequency is deleted from the prediction modes included in the extension set so that the number of prediction modes specified by the syntax rem_intra_pred_mode 'is 2 ⁿ -1 (n is a natural number), and the remaining It is good also as a structure which designates prediction mode with syntax rem_intra_pred_mode '.

Here, the intra predicted image generation unit 12c can determine the frequency of use of the prediction mode, for example, based on the appearance frequency of the prediction mode assigned to the already decoded partition in the target frame. In such a configuration, the prediction mode to be deleted is determined for each partition.

In addition, the intra predicted image generation unit 12c can determine the use frequency of the prediction mode according to the appearance frequency of the prediction mode in a frame decoded immediately before the target frame or in a plurality of frames that have already been decoded. . In such a configuration, the prediction mode to be deleted is determined for each frame. Moreover, it is good also as a structure which determines beforehand the usage frequency of prediction mode for every sequence. In such a configuration, the prediction mode to be deleted is determined for each sequence.

The syntax adjust_neighb_dir shown in FIG. 6A is a syntax included in the intra prediction parameter PP_Intra when the edge-based prediction mode is designated for the target partition. When the syntax adjust_neighb_dir is included in the intra prediction parameter PP_Intra, as described above, the intra prediction image generation unit 12c sets the direction obtained by adding the correction angle indicated by the syntax adjust_neighb_dir to the calculated edge direction. Set the prediction direction for. Note that the value that can be taken by the syntax adjust_neighb_dir is not limited to the example shown in FIG. 5B. In general, any one of −A to + A is designated. Can do.

(Flow of intra prediction image generation processing by the intra prediction image generation unit 12c)
Next, a flow of processing for generating the intra predicted image Pred_Intra by the intra predicted image generation unit 12c will be described with reference to FIG.

FIG. 1 is a flowchart showing a flow of processing for generating an intra predicted image Pred_Intra by the intra predicted image generation unit 12c.

(Step S101)
First, the intra predicted image generation unit 12c determines whether or not the syntax most_prob_mode ′ decoded from the encoded data # 1 and supplied from the variable length code decoding unit 11 is “1”.

(Step S102)
If the syntax most_prob_mode ′ is 1 (Yes in step S101), the estimated prediction mode is set to the temporary prediction mode for the target partition.

(Step S103)
If the syntax most_prob_mode ′ is not 1 (No in step S101), the syntax rem_intra_pred_mode ′ decoded from the encoded data # 1 and supplied from the variable length code decoding unit 11 is referred to by the syntax rem_intra_pred_mode ′. The designated prediction mode is set to the temporary prediction mode for the target partition.

(Step S104)
Subsequently, it is determined whether or not the temporary prediction mode is an edge-based prediction mode. Here, whether or not the temporary prediction mode is the edge-based prediction mode can be determined by referring to information indicating a correspondence relationship between each index and each prediction mode. For example, when the extended set shown in FIG. 4A is used, when the index assigned to the temporary prediction mode is 1, it can be determined that the temporary prediction mode is the edge-based prediction mode. .

(Step S105)
When the temporary prediction mode is the edge-based prediction mode (Yes in step S104), the edge direction is calculated. For specific edge direction calculation, the method described in (Prediction image calculation processing in edge-based prediction mode) may be used.

(Step S106)
When the temporary prediction mode is the edge-based prediction mode and the intra prediction parameter PP_Intra includes the syntax adjust_neighb_dir, the correction angle specified by the syntax adjust_neighb_dir is added to the edge direction. Then, the prediction direction assigned to the target partition is determined. For the specific calculation of the correction angle, the method described in (Prediction image calculation processing in edge-based prediction mode) may be used.

(Step S107)
When the temporary prediction mode is not the edge-based prediction mode (No in step S104), the temporary prediction mode is set to the prediction mode (target prediction mode) for the target partition. That is, the prediction direction indicated by the temporary prediction mode is assigned to the target partition. The provisional prediction mode not being the edge-based prediction mode corresponds to the provisional prediction mode being one of the basic prediction modes included in the basic prediction mode set described above.

(Step S108)
Finally, the intra prediction image Pred_Intra for the target partition is generated by extrapolating the pixel values of pixels around the target partition in the prediction direction assigned to the target partition. Note that if there are decoded pixels on both sides along the prediction direction, the intra predicted image Pred_Intra may be generated by interpolating the pixel values of these pixels.

The above is the flow of processing for generating the intra predicted image Pred_Intra by the intra predicted image generation unit 12c.

In the above description, the case where each prediction mode included in the extended set is specified by the index shown in FIG. 4 is taken as an example, but the present embodiment is not limited to this. For example, the index assigned to the edge-based prediction mode may be configured to be changeable depending on the characteristics of the decoding target image. Specifically, when the decoding target image includes more edges, the edge-based prediction mode may be specified by a smaller index.

Further, in the above description, the case where the extended set is configured by the basic prediction mode and the edge-based prediction mode has been described. However, the present embodiment is not limited to this, and in general, the extended set The present invention can be widely applied when the set is composed of a predetermined basic prediction mode and a prediction mode using a parameter (for example, prediction direction) calculated for each partition.

As described above, the video decoding device 1 according to the present embodiment uses the residual data between the original image and the prediction image generated for each prediction unit as the elements of the first prediction mode group and the second prediction mode. A decoding apparatus that decodes encoded data obtained by encoding together with prediction mode specifying information that specifies elements of a prediction mode set consisting of elements of a group by a single code, and the code and the code specify Prediction mode specifying means for specifying a prediction mode specified by the prediction mode designation information from the code according to a predetermined correspondence relationship with the prediction mode, and a prediction mode to which the prediction mode designated by the code and the code belongs Prediction mode group specifying means for specifying a prediction mode group to which the prediction mode specified by the prediction mode specifying information belongs from the code according to a predetermined correspondence relationship with the group One or more prediction parameters derived by referring to a decoded image when the prediction mode group specified by the prediction mode group specifying means is a first prediction mode group, which is a prediction parameter selection means for selecting a prediction parameter. A prediction parameter corresponding to the prediction mode specified by the prediction mode specifying means is selected from the first prediction parameter group, and the prediction mode group specified by the prediction mode group specifying means is the second prediction mode group. A prediction parameter selection unit that selects a prediction parameter corresponding to the prediction mode specified by the prediction mode specifying unit from a second prediction parameter group including one or more predetermined prediction parameters, and a prediction parameter selection unit. Prediction image generation means for generating the prediction image according to the selected prediction parameter. It can be expressed as a decoding device according to.

Here, in the above-described example, the first prediction mode group is a group composed of one edge-based prediction mode, but in <Modification 3> described later, a group composed of a plurality of edge-based prediction modes. It is.

Further, the second prediction mode group refers to the basic prediction mode set in the above-described example.

The single code refers to, for example, the binary code shown in FIG. 6D, and a predetermined correspondence between the code and the prediction mode specified by the code. Indicates, for example, a correspondence relationship between rem_intra_pred_mode ′ illustrated in FIG. 6C and the prediction mode index.

Further, as a predetermined correspondence relationship between the code and the prediction mode group to which the prediction mode specified by the code belongs, for example, in the above-described example, each index and each prediction mode described in step S104 It is determined by the information indicating the correspondence relationship.

(Effect of intra prediction image generation processing by the intra prediction image generation unit 12c)
Hereinafter, the effects of the intra prediction image generation processing by the intra prediction image generation unit 12c will be described in comparison with the intra prediction image generation processing by the intra prediction image generation unit according to the comparative example.

First, with reference to FIG. 7, the intra prediction image generation processing by the intra prediction image generation unit according to the comparative example will be described. For example, the intra predicted image generation unit according to the comparative example generates an intra predicted image with reference to an intra prediction parameter having a conventional syntax shown in FIG.

FIG. 7 is a flowchart showing a flow of intra prediction image generation processing by the intra prediction image generation unit according to the comparative example.

(Step S201)
First, the intra predicted image generation unit according to the comparative example refers to the syntax use_neighb_dir shown in (c) of FIG. 10 and determines whether or not the syntax use_neighb_dir specifies the edge-based prediction mode for the target partition. To do. Here, the syntax use_neighb_dir is a 1-bit syntax that takes 1 when the edge-based prediction mode is designated and takes 0 when the basic prediction mode is designated. Accordingly, the syntax use_neighb_dir is a syntax that specifies whether the prediction mode to be allocated to the target partition is selected from the basic prediction mode or the edge-based prediction mode.

(Step S202)
If the edge-based prediction mode is specified for the target partition (Yes in step S201), the edge direction is calculated.

(Step S203)
When the edge-based prediction mode is specified for the target partition and the encoded data includes the syntax adjust_neighb_dir, the correction angle specified by the syntax adjust_neighb_dir is added in the edge direction. To determine the prediction direction to be assigned to the target partition.

(Step S204)
If the edge-based prediction mode is not specified for the target partition (No in step S201), it is determined whether or not the syntax most_prob_mode is 1.

(Step S205)
When the syntax most_prob_mode is 1 (Yes in step S204), the prediction mode is assigned to a partition around the target partition, and is specified by a smaller index among the prediction modes included in the basic prediction mode set. The estimated prediction mode that is the prediction mode to be set is set to the prediction mode (target prediction mode) for the target partition. That is, the prediction direction indicated by the estimated prediction mode is assigned to the target partition.

(Step S206)
If the syntax most_prob_mode is not 1 (No in step S204), the syntax rem_intra_pred_mode is referred to, and the prediction mode specified by the syntax rem_intra_pred_mode is set as the prediction mode for the target partition. That is, the prediction direction indicated by the prediction mode specified by the syntax rem_intra_pred_mode is assigned to the target partition. Here, the prediction mode specified by the syntax rem_intra_pred_mode is a prediction mode included in the basic prediction mode set.

(Step S207)
Finally, an intra prediction image for the target partition is generated by extrapolating the pixel values of pixels around the target partition in the prediction direction assigned to the target partition. Note that if there are decoded pixels on both sides along the prediction direction, the intra predicted image Pred_Intra may be generated by interpolating the pixel values of these pixels.

The above is the flow of intra prediction image generation processing by the intra prediction image generation unit according to the comparative example.

Hereinafter, the code amount of the intra prediction parameter referred to by the intra prediction image generation unit according to the comparative example is compared with the code amount of the intra prediction parameter PP_Intra referred to by the intra prediction image generation unit 12c according to the present embodiment. The effect which the intra estimated image production | generation part 12c which concerns on embodiment, and intra prediction parameter PP_Intra play is demonstrated. In the following description, the case where the intra prediction parameters according to the comparative example and the intra prediction parameter PP_Intra according to the present embodiment are non-arithmetic coded (CAVLC coding) will be described as an example. However, it can be estimated in the same way when arithmetic coding (CABAC coding) is performed.

(Code amount of intra prediction parameter referred to by intra prediction image generating unit according to comparative example)
First, the code amount of the intra prediction parameter referred to by the intra predicted image generation unit according to the comparative example will be described.

As described above, the syntax use_neighb_dir is expressed by a 1-bit code, and the syntax most_prob_mode is also expressed by a 1-bit code. On the other hand, if the number of prediction modes included in the basic prediction mode set is 9, the syntax rem_intra_pred_mode for specifying any one of the nine prediction modes excluding the estimated prediction mode is represented by a 3-bit code. Expressed. In the following description, it is assumed that the syntax adjust_neighb_dir is expressed by a p-bit code.

In addition, an average ratio in which the edge-based prediction mode is selected is expressed as u, and an average ratio in which the estimated prediction mode is not selected is expressed as v. Here, the average ratios u and v represent, for example, the total number of partitions included in a sequence as Ntot, the total number of partitions for which the edge-based prediction mode is selected as Nedge, and the estimated prediction mode is not selected. If the total number of partitions (not estimated) is expressed as Nmpm, it can be expressed as u = Nedge / Ntot, v = Nmpm / Ntot.

Under such a premise, the code amount Q per partition of the intra prediction parameters referred to by the intra prediction image generation unit according to the comparative example can be estimated as follows.

Q = 1 + u × p + (1−u) × (1 + 3 × v) (1)
Here, the first term of Expression (1) represents the contribution of the syntax use_neighb_dir, and the second term represents the contribution of the syntax adjust_neighb_dir when the edge-based prediction mode is selected. The third term of Equation (1) represents the contribution when the basic prediction mode set is selected. In particular, the first term in the second parenthesis of the third term of Equation (1) represents the contribution of the syntax most_prob_mode, and the second term in the second parenthesis of the third term of Equation (1) is the syntax. It represents the contribution of rem_intra_pred_mode.

(Code amount of intra prediction parameter PP_Intra referenced by the intra predicted image generation unit 12c)
Subsequently, the code amount of the intra prediction parameter PP_Intra referred to by the intra predicted image generation unit 12c according to the present embodiment will be described.

As described above, the syntax most_prob_mode ′ in the intra prediction parameter PP_Intra is expressed by a 1-bit code. On the other hand, the syntax rem_intra_pred_mode ′ in the intra prediction parameter PP_Intra is represented on the average by a 3 + w bit code. Here, the value of w depends on how the code length corresponding to each value of the syntax rem_intra_pred_mode ′ is set. For example, the code length of the syntax rem_intra_pred_mode ′ is shown in FIG. If it is set as shown, the specific value of w can be estimated to be about 0.1 to 0.2.

In addition, an average ratio in which the edge-based prediction mode is selected in the intra-predicted image generation unit 12c is expressed as u ′, and an average ratio in which the estimated prediction mode is not selected in the intra-predicted image generation unit 12c is expressed as v ′. To.

Under such a premise, the code amount Q ′ per partition of the intra prediction parameter PP_Intra referred to by the intra prediction image generation unit 12c can be estimated as follows.

Q ′ = 1 + u ′ × p + v ′ × (3 + w) (2)
Here, the first term of Expression (2) represents the contribution of the syntax most_prob_mode ′, and the second term represents the contribution of the syntax adjust_neighb_dir. In addition, the third term of Expression (3) represents the contribution of the syntax rem_intra_pred_mode ′.

Since u ′ and v ′ in Expression (2) are considered to be substantially equal to u and v in Expression (1), respectively, the code amount Q of the intra prediction parameter referred to by the intra predicted image generation unit according to the comparative example. And the code amount Q ′ of the intra prediction parameter PP_Intra referred to by the intra predicted image generation unit 12c can be expressed as follows.

QQ ′ = (1−u) × (1 + 3 × v) −v × (3 + w)
= 1−u−3 × u × v−v × w (3)
In the range where QQ ′ shown in Equation (3) is positive, the code amount Q ′ of the intra prediction parameter PP_Intra referred to by the intra prediction image generation unit 12c is referred to by the intra prediction image generation unit according to the comparative example. It becomes smaller than the code amount Q of the intra prediction parameter.

On the other hand, as is clear from Equation (3), Q−Q ′ is a decreasing function of u, v, and w in the range of u ≧ 0, v ≧ 0, and w ≧ 0. Therefore, the smaller the u, v, and w, the smaller the code amount Q ′ of the intra prediction parameter PP_Intra compared to the comparative example. In other words, the smaller the average rate at which the edge-based prediction mode is selected and the smaller the average rate at which the estimated prediction mode is not selected, the more the code amount Q ′ of the intra prediction parameter PP_Intra is in the comparative example. Smaller than that. Also, the smaller the value of w, the smaller the code amount Q ′ of the intra prediction parameter PP_Intra compared to the comparative example.

Therefore, according to the configuration of the intra prediction parameter PP_Intra in the present embodiment, for example, the code amount can be reduced for an image with a low frequency in which the edge-based prediction mode is selected. Also, the amount of codes can be reduced for an image with a high frequency of selecting the estimated prediction mode. An example of an image with a low frequency in which the edge-based prediction mode is selected is a relatively flat image. An example of an image with a high frequency of selecting the estimated prediction mode is an image with high spatial correlation.

Thus, according to the configuration of the intra prediction parameter PP_Intra in the present embodiment, for example, the code amount is higher than that of the intra prediction parameter according to the comparative example for an image having a high spatial correlation and a relatively flat image. Reduced. Moreover, according to the intra estimated image production | generation part 12c in this embodiment, the intra estimated image Pred_Intra can be produced | generated appropriately with reference to such intra prediction parameters PP_Intra with small code amount.

In addition, the effect of code amount reduction in the intra prediction parameter PP_Intra is that, when each syntax included in the intra prediction parameter PP_Intra and the intra prediction parameter according to the comparative example is subjected to non-arithmetic coding (CAVLC coding). It will be bigger. This is because the intra prediction parameter according to the comparative example always requires a 1-bit code when encoding the syntax use_neighb_dir, whereas the intra prediction parameter PP_Intra according to the present embodiment This is because the syntax is unnecessary.

Further, in the intra prediction parameter PP_Intra according to the present embodiment, as described above, since the edge-based prediction mode is included as an estimation target in the estimated prediction mode, if the estimated prediction mode is selected, edge-based prediction is performed with 1 bit. The mode can be described, and in this respect, even with arithmetic coding (CABAC coding), the code amount can be reduced.

<Modification 1>
The structure of the moving image decoding apparatus 1 which concerns on this embodiment, and intra prediction parameter PP_Intra is not limited to the example mentioned above. Below, the 1st of the moving image decoding apparatus which concerns on this embodiment, and the modification of intra prediction parameter PP_Intra are demonstrated.

In the present modification, when the intra prediction parameter PP_Intra included in the encoded data # 1 is arithmetically encoded / decoded (CABAC encoding / decoding), the intra prediction parameter PP_Intra is illustrated in (c) of FIG. When intra prediction parameters (that is, the same as the intra prediction parameters according to the comparative example) having the syntaxes shown above are used, and the intra prediction parameter PP_Intra is non-arithmetic encoded / decoded (CAVLC encoded / decoded) Uses an intra prediction parameter composed of the syntax shown in FIG. 6A as the intra prediction parameter PP_Intra.

The intra prediction image generation unit 12c refers to the encoding mode information (entropy_coding_mode_flag) included in the picture header of the encoded data, and identifies which encoding method is used to encode the intra prediction parameter PP_Intra. be able to.

When the intra prediction parameter PP_Intra is configured in this way, the video decoding device determines whether the intra prediction parameter PP_Intra is arithmetically encoded or non-arithmographically encoded, respectively. The processing shown in FIGS. 7 and 1 may be performed.

As described above, the intra prediction parameter shown in FIG. 6A has a large code amount reduction effect particularly in non-arithmetic coding / decoding (CAVLC coding / decoding). In addition, it is possible to effectively reduce the code amount of the encoded data # 1.

<Modification 2>
Subsequently, a moving image decoding apparatus according to the present embodiment and a second modification of the intra prediction parameter PP_Intra will be described.

In this modification, in the video encoding device, the configuration shown in (a) of FIG. 6 and the configuration shown in (c) of FIG. 10 are selectively used as the intra prediction parameter PP_Intra. A flag indicating which intra prediction parameter is used is included in the encoded data. Here, selection of which configuration is used as the intra prediction parameter PP_Intra is adaptively performed so that the coding efficiency is further increased.

The moving picture decoding apparatus according to the present modification can identify the configuration of the intra-prediction parameter PP_Intra by referring to the above flag, so that the intra-prediction image can be appropriately generated. it can.

According to the configuration of the present modification, the code amount of the encoded data # 1 is more effectively reduced, so that the encoding efficiency can be improved more effectively.

<Modification 3>
Subsequently, a moving image decoding apparatus according to the present embodiment and a third modification of the intra prediction parameter PP_Intra will be described with reference to (a) to (b) of FIG.

In this modification, an extended set is configured by adding a plurality of edge-based prediction modes to the basic prediction mode set.

(A) of FIG. 8 is a figure which illustrates the prediction mode contained in the extended set in this modification. As shown in FIG. 8A, in this modification, for example, three edge-based prediction modes are added to the basic prediction mode set. In FIG. 8A, “edge-based prediction” is an edge-based prediction mode that has already been described, and indicates a prediction mode in which correction by the correction angle Δα is not performed. On the other hand, “edge-based prediction−Δα” is the edge-based prediction mode already described, and indicates a prediction mode in which correction of “−Δα” is performed using the correction angle Δα. “Edge-based prediction + Δα” is an edge-based prediction mode that has already been described, and indicates a prediction mode in which “+ Δα” is corrected using the correction angle Δα.

In the example shown in FIG. 8A, three edge-based prediction modes are designated by indexes 1 to 3, respectively, and prediction modes included in the basic prediction mode set are designated by

indexes

0 and 4 to 11, respectively. The

(B) of FIG. 8 is a table | surface which shows each syntax which comprises the intra prediction parameter which concerns on this modification. As shown in FIG. 8B, the intra prediction parameters according to this modification include the syntax most_prob_mode ″ and the syntax rem_intra_pred_mode ″, but the syntax shown in FIG. Does not include the tax adjust_neighb_dir.

Here, the syntax most_prob_mode '' is the same as the syntax most_prob_mode 'described above, and the estimated prediction mode estimated from the prediction modes assigned to the surrounding partitions of the target partition is the same as the prediction mode for the target partition. This is a syntax that takes 1 when it is and 0 otherwise. Since any of a plurality of edge-based prediction modes may be assigned to a partition around the target partition, when the syntax most_prob_mode '' is 1, a plurality of edge-based prediction modes are set for the target partition. Any of the modes may be selected.

Also, the syntax rem_intra_pred_mode '' is a syntax for designating one of the prediction modes other than the estimated prediction mode among the prediction modes included in the extended set, almost the same as the syntax rem_intra_pred_mode ′ already described. . Note that, unlike the syntax rem_intra_pred_mode ', the syntax rem_intra_pred_mode' 'may specify any of the plurality of edge-based prediction modes.

As described above, according to the intra prediction parameter according to the present modification, only the syntax most_prob_mode '' and the syntax rem_intra_pred_mode '' are used to change from the plurality of basic prediction modes and the plurality of edge-based prediction modes to the target partition. A prediction mode to be assigned can be selected. Therefore, according to the present modification, the configuration of the intra prediction parameter can be simplified.

Note that, in this modification as well, information indicating which index corresponds to the edge-based prediction mode can be configured to be shared between the video encoding device and the video decoding device.

(Moving picture encoding device 2)
A configuration of the moving picture encoding apparatus 2 according to the present embodiment will be described with reference to FIG. The moving image encoding apparatus 2 includes H.264 as a part thereof. H.264 / MPEG-4. Coding including technology adopted in KTA software, which is a codec for joint development in AVC and VCEG (Video Coding Expert Group), and technology adopted in TMuC (Test Model under Consideration) software, which is the successor codec Device.

FIG. 9 is a block diagram showing a configuration of the moving picture encoding apparatus 2. As illustrated in FIG. 9, the moving image encoding apparatus 2 includes a predicted image generation unit 21, a transform / quantization unit 22, an inverse quantization / inverse transform unit 23, an adder 24, a frame memory 25, a loop filter 26, a variable A long code encoding unit 27 and a subtracter 28 are provided. As shown in FIG. 9, the predicted image generation unit 21 includes an intra predicted image generation unit 21 a, a motion vector detection unit 21 b, an inter predicted image generation unit 21 c, a prediction method control unit 21 d, and a motion vector redundancy deletion unit. 21e. The moving image encoding device 2 is a device that generates encoded data # 1 by encoding moving image # 10 (encoding target image).

(Predicted image generation unit 21)
The predicted image generation unit 21 recursively divides the processing target LCU into one or a plurality of lower-order CUs, further divides each leaf CU into one or a plurality of partitions, and uses an inter-screen prediction for each partition. A predicted image Pred_Inter or an intra predicted image Pred_Intra using intra prediction is generated. The generated inter prediction image Pred_Inter and intra prediction image Pred_Intra are supplied to the adder 24 and the subtracter 28 as the prediction image Pred.

Note that the prediction image generation unit 21 omits encoding of other parameters belonging to the PU for the PU to which the skip mode is applied. Also, (1) the mode of division into lower CUs and partitions in the target LCU, (2) whether to apply the skip mode, and (3) which of the inter predicted image Pred_Inter and the intra predicted image Pred_Intra for each partition Whether to generate is determined so as to optimize the encoding efficiency.

(Intra predicted image generation unit 21a)
The intra predicted image generation unit 21a generates a predicted image Pred_Intra for each partition by intra prediction. Specifically, (1) a prediction mode used for intra prediction is selected for each partition, and (2) a prediction image Pred_Intra is generated from the decoded image P using the selected prediction mode. The intra predicted image generation unit 21a supplies the generated intra predicted image Pred_Intra to the prediction method control unit 21d.

More specifically, the intra-prediction image generation unit 21a selects any one of the prediction modes included in the above-described basic prediction mode set and the prediction mode included in the extended set including the edge-based prediction mode. The intra prediction image Pred_Intra is generated according to the method indicated by the selected prediction mode. When the edge-based prediction mode is selected and when the basic prediction mode is selected, the intra-prediction image Pred_Intra generation processing is almost the same as the generation processing by the intra-prediction image generation unit 12c included in the video decoding device 1. It is.

In addition, the intra predicted image generation unit 21a determines an estimated prediction mode for the target partition from the prediction modes assigned to the peripheral partitions of the target partition, and the estimated prediction mode and the prediction mode actually selected for the target partition Are supplied as a part of the intra prediction parameter PP_Intra to the variable length code encoding unit 27 via the prediction scheme control unit 21d, and the variable length code encoding unit 27 The flag is included in the encoded data # 1 as syntax most_prob_mode ′.

In addition, when the estimated prediction mode for the target partition is different from the prediction mode actually selected for the target partition, the intra predicted image generation unit 21a sets a residual prediction mode index indicating the prediction mode for the target partition, As a part of the intra prediction parameter PP_Intra, it is supplied to the variable length code encoding unit 27 via the prediction scheme control unit 21d, and the variable length code encoding unit 27 encodes the residual prediction mode index as syntax rem_intra_pred_mode '. The configuration includes data # 1.

Further, when the intra-predicted image generation unit 21a selects the edge-based prediction mode and the correction using the correction angle Δα is performed on the calculated edge direction, the correction angle Δα is quantized. A parameter (quantization index) t obtained by dividing by the size δα is supplied as a part of the intra prediction parameter PP_Intra to the variable length code encoding unit 27 via the prediction scheme control unit 21d, and variable length code encoding is performed. The unit 27 is configured to include the parameter t in the encoded data # 1 as the syntax adjust_neighb_dir. Note that the quantization step size δα may be determined using a method similar to the method described in the description of the intra predicted image generation unit 12c.

Note that the intra-predicted image generation unit 21a may be configured to set a plurality of correction angle candidates and select a plurality of correction angle candidates that have higher encoding efficiency.

As described above, the intra prediction parameter PP_Intra supplied from the intra predicted image generation unit 21a to the variable length code encoding unit 27 is configured to have the syntaxes illustrated in FIG.

(Motion vector detection unit 21b)
The motion vector detection unit 21b detects a motion vector mv regarding each partition. Specifically, (1) the filtered decoded image P_ALF ′ used as the reference image is selected, and (2) the target partition is searched by searching for the region that best approximates the target partition in the selected filtered decoded image P_ALF ′. Detects a motion vector mv. Here, the filtered decoded image P_ALF ′ is an image obtained by performing adaptive filter processing by the loop filter 26 on the decoded image that has already been decoded for the entire frame, and is a motion vector detection unit. 21b can read out the pixel value of each pixel constituting the filtered decoded image P_ALF ′ from the frame memory 25. The motion vector detection unit 21b supplies the detected motion vector mv to the inter predicted image generation unit 21c and the motion vector redundancy deletion unit 21e together with the reference image index RI that specifies the filtered decoded image P_ALF ′ used as the reference image. To do.

(Inter prediction image generation unit 21c)
The inter prediction image generation unit 21c generates a motion compensated image mc related to each inter prediction partition by inter-screen prediction. Specifically, the motion compensation image mc is obtained from the filtered decoded image P_ALF ′ designated by the reference image index RI supplied from the motion vector detection unit 21b, using the motion vector mv supplied from the motion vector detection unit 21b. Generate. Similar to the motion vector detection unit 21b, the inter prediction image generation unit 21c can read out the pixel value of each pixel constituting the filtered decoded image P_ALF ′ from the frame memory 25. The inter prediction image generation unit 21c supplies the generated motion compensated image mc (inter prediction image Pred_Inter) together with the reference image index RI supplied from the motion vector detection unit 21b to the prediction method control unit 21d.

(Prediction method controller 21d)
The prediction scheme control unit 21d compares the intra predicted image Pred_Intra and the inter predicted image Pred_Inter with the encoding target image, and selects whether to perform intra prediction or inter prediction. When the intra prediction is selected, the prediction scheme control unit 21d supplies the intra prediction image Pred_Intra as the prediction image Pred to the adder 24 and the subtracter 28, and sets the intra prediction parameter PP_Intra supplied from the intra prediction image generation unit 21a. This is supplied to the variable length code encoding unit 27. On the other hand, when the inter prediction is selected, the prediction scheme control unit 21d supplies the inter prediction image Pred_Inter as the prediction image Pred to the adder 24 and the subtracter 28, and the reference image index RI and motion vector redundancy described later. The estimated motion vector index PMVI and the motion vector residual MVD supplied from the deletion unit 21e are supplied to the variable length code encoding unit 27 as an inter prediction parameter PP_Inter.

(Motion vector redundancy deleting unit 21e)
The motion vector redundancy deletion unit 21e deletes redundancy in the motion vector mv detected by the motion vector detection unit 21b. Specifically, (1) an estimation method used for estimating the motion vector mv is selected, (2) an estimated motion vector pmv is derived according to the selected estimation method, and (3) the estimated motion vector pmv is subtracted from the motion vector mv. As a result, a motion vector residual MVD is generated. The motion vector redundancy deleting unit 21e supplies the generated motion vector residual MVD to the prediction method control unit 21d together with the estimated motion vector index PMVI indicating the selected estimation method.

(Transformation / quantization unit 22)
The transform / quantization unit 22 performs (1) DCT transform (Discrete Cosine Transform) for each block (transform unit) on the prediction residual D obtained by subtracting the predicted image Pred from the encoding target image, and (2) obtains the DCT transform. The obtained DCT coefficients are quantized, and (3) the quantized prediction residual QD obtained by the quantization is supplied to the variable length code encoding unit 27 and the inverse quantization / inverse transform unit 23. The transform / quantization unit 22 (1) selects a quantization step QP to be used for quantization for each TU, and (2) sets a quantization parameter difference Δqp indicating the size of the selected quantization step QP. The variable length code encoding unit 28 is supplied, and (3) the selected quantization step QP is supplied to the inverse quantization / inverse transform unit 23. Here, the quantization parameter difference Δqp is the quantization parameter related to the TU that has been DCT transformed / quantized immediately before from the value of the quantization parameter qp (for example, QP = 2 ^{pq / 6} ) relating to the macroblock to be DCT transformed / quantized. It refers to the difference value obtained by subtracting the value of qp ′.

(Inverse quantization / inverse transform unit 23)
The inverse quantization / inverse transform unit 23 (1) inversely quantizes the quantized prediction residual QD, (2) performs inverse DCT (Discrete Cosine Transform) transformation on the DCT coefficient obtained by the inverse quantization, and (3) The prediction residual D obtained by the inverse DCT transform is supplied to the adder 24. When the quantization prediction residual QD is inversely quantized, the quantization step QP supplied from the transform / quantization unit 22 is used. Note that the prediction residual D output from the inverse quantization / inverse transform unit 23 is obtained by adding a quantization error to the prediction residual D input to the transform / quantization unit 22. Common names are used for this purpose.

(Adder 24)
The adder 24 adds the predicted image Pred selected by the prediction scheme control unit 21d to the prediction residual D generated by the inverse quantization / inverse transform unit 23, thereby obtaining the (local) decoded image P. Generate. The (local) decoded image P generated by the adder 24 is supplied to the loop filter 26 and stored in the frame memory 25, and is used as a reference image in intra prediction.

(Variable-length code encoding unit 27)
The variable length code encoding unit 27 (1) the quantization prediction residual QD and Δqp supplied from the transform / quantization unit 22, and (2) the quantization parameter PP (inter prediction) supplied from the prediction scheme control unit 21d. The parameter PP_Inter and the intra prediction parameter PP_Intra) and (3) the filter parameter FP supplied from the loop filter 26 are variable-length-encoded to generate encoded data # 1.

As a specific encoding method by the variable length code encoding unit 27, CABAC (Context-based Adaptive Binary Arithmetic Coding) which is one arithmetic coding / decoding method, or one non-arithmetic encoding / decoding method is used. CAVLC (Context-based Adaptive VLC) which is a method is used.

The variable length code encoding unit 27 determines which encoding method of CABAC or CAVLC is to be used for each picture, performs encoding using the determined encoding method, and specifies the determined encoding method The mode information (entropy_coding_mode_flag) is included in the picture header PH of the encoded data # 1.

(Subtractor 28)
The subtracter 28 generates the prediction residual D by subtracting the prediction image Pred selected by the prediction method control unit 21d from the encoding target image. The prediction residual D generated by the subtracter 28 is DCT transformed / quantized by the transform / quantization unit 22.

(Loop filter 26)
The loop filter 26 reads the decoded image P from the frame memory 25 and performs block noise reduction processing at one or both of the partition boundary and the block boundary of the decoded image P. The loop filter 26 performs adaptive filter processing using the adaptively calculated filter parameter FP on the decoded image subjected to block noise reduction processing, and the adaptive filter processing is performed. The decoded image P is output to the frame memory 25 as a filtered decoded image P_ALF. The filtered decoded image P_ALF is mainly used as a reference image in the inter predicted image generation unit 21c.

<Modification 1 '>
As described in <Modification 1>, the configuration of the intra prediction parameters encoded by the moving image encoding device 2 is not limited to the example illustrated in FIG. When the intra prediction parameter PP_Intra is arithmetically encoded (CABAC encoding) in the moving image encoding device 2, the intra prediction parameter including each syntax shown in FIG. 10C is used as the intra prediction parameter PP_Intra. (That is, the same intra prediction parameter according to the comparative example) is included in the encoded data # 1, and the intra prediction parameter PP_Intra is obtained when the intra prediction parameter PP_Intra is non-arithmetic encoded (CAVLC encoded). As an example, the encoded data # 1 may include intra prediction parameters including the syntaxes illustrated in FIG. Note that assigning different contexts to each syntax is effective in improving the arithmetic coding efficiency.

<Modification 2 '>
Further, as described in <Modification 2>, the moving picture encoding apparatus 2 uses the configuration illustrated in FIG. 6A and the configuration illustrated in FIG. 10C as the intra prediction parameter PP_Intra. May be selectively used, and a flag indicating which intra prediction parameter is used may be included in the encoded data # 1. Here, the selection of which configuration is used as the intra prediction parameter PP_Intra is adaptively performed by the video encoding device 2 so that the encoding efficiency is further increased.

<Modification 3 '>
Further, as described in <Modification 3>, the moving picture encoding apparatus 2 is configured to select a prediction mode for each partition from the prediction modes included in the extended set illustrated in FIG. The intra prediction parameter PP_Intra having the syntax shown in FIG. 8B may be included in the encoded data # 1.

According to this modification, the configuration of the intra prediction parameter PP_Intra can be simplified.

[Application example]
The above-described moving image encoding device 2 and moving image decoding device 1 can be used by being mounted on various devices that perform transmission, reception, recording, and reproduction of moving images.

First, it will be described with reference to FIG. 11 that the above-described moving image encoding device 2 and moving image decoding device 1 can be used for transmission and reception of moving images.

(A) of FIG. 11 is a block diagram showing a configuration of a transmission apparatus PROD_A in which the moving picture encoding apparatus 2 is mounted. As illustrated in FIG. 11A, the transmission device PROD_A modulates a carrier wave with an encoding unit PROD_A1 that obtains encoded data by encoding a moving image, and with the encoded data obtained by the encoding unit PROD_A1. Thus, a modulation unit PROD_A2 that obtains a modulation signal and a transmission unit PROD_A3 that transmits the modulation signal obtained by the modulation unit PROD_A2 are provided. The moving image encoding apparatus 2 described above is used as the encoding unit PROD_A1.

The transmission device PROD_A is a camera PROD_A4 that captures a moving image, a recording medium PROD_A5 that records the moving image, and an input terminal PROD_A6 for inputting the moving image from the outside as a supply source of the moving image input to the encoding unit PROD_A1. May be further provided. FIG. 11A illustrates a configuration in which the transmission apparatus PROD_A includes all of these, but some of them may be omitted.

The recording medium PROD_A5 may be a recording of a non-encoded moving image, or a recording of a moving image encoded by a recording encoding scheme different from the transmission encoding scheme. It may be a thing. In the latter case, a decoding unit (not shown) for decoding the encoded data read from the recording medium PROD_A5 according to the recording encoding method may be interposed between the recording medium PROD_A5 and the encoding unit PROD_A1.

(B) of FIG. 11 is a block diagram illustrating a configuration of a receiving device PROD_B in which the moving image decoding device 1 is mounted. As illustrated in FIG. 11B, the receiving device PROD_B includes a receiving unit PROD_B1 that receives a modulated signal, a demodulating unit PROD_B2 that obtains encoded data by demodulating the modulated signal received by the receiving unit PROD_B1, and a demodulator. A decoding unit PROD_B3 that obtains a moving image by decoding the encoded data obtained by the unit PROD_B2. The moving picture decoding apparatus 1 described above is used as the decoding unit PROD_B3.

The receiving device PROD_B has a display PROD_B4 for displaying a 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. PROD_B6 may be further provided. FIG. 11B illustrates a configuration in which all of these are provided in the receiving device PROD_B, but some of them may be omitted.

The recording medium PROD_B5 may be used for recording a non-encoded moving image, or may be encoded using a recording encoding method different from the transmission encoding method. May be. In the latter case, an encoding unit (not shown) for encoding the moving image acquired from the decoding unit PROD_B3 according to the recording encoding method may be interposed between the decoding unit PROD_B3 and the recording medium PROD_B5.

Note that the transmission medium for transmitting the modulation 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 transmission destination is not specified in advance) or communication (here, transmission in which the transmission destination is specified in advance). Refers to the embodiment). That is, the transmission of the modulation signal may be realized by any of wireless broadcasting, wired broadcasting, wireless communication, and wired communication.

For example, a terrestrial digital broadcast broadcasting station (broadcasting equipment or the like) / receiving station (such as a television receiver) is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives a modulated signal by wireless broadcasting. Further, a broadcasting station (such as broadcasting equipment) / receiving station (such as a television receiver) of cable television broadcasting is an example of a transmitting device PROD_A / receiving device PROD_B that transmits and receives a modulated signal by cable broadcasting.

Also, a server (workstation etc.) / Client (television receiver, personal computer, smart phone etc.) such as VOD (Video On Demand) service and video sharing service using the Internet is a transmitting device for transmitting and receiving modulated signals by communication. This is an example of PROD_A / reception device PROD_B (usually, either a wireless or wired transmission medium is used in a LAN, and a wired transmission medium is used in a WAN). Here, the personal computer includes a desktop PC, a laptop PC, and a tablet PC. The smartphone also includes a multi-function mobile phone terminal.

In addition to the function of decoding the encoded data downloaded from the server and displaying it on the display, the video sharing service client has a function of encoding a 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 transmission device PROD_A and the reception device PROD_B.

Next, it will be described with reference to FIG. 12 that the above-described moving image encoding device 2 and moving image decoding device 1 can be used for recording and reproduction of moving images.

(A) of FIG. 12 is a block diagram showing a configuration of a recording apparatus PROD_C in which the above-described moving picture encoding apparatus 2 is mounted. As shown in FIG. 12 (a), the recording device PROD_C has an encoding unit PROD_C1 that obtains encoded data by encoding a moving image, and the encoded data obtained by the encoding unit PROD_C1 on the recording medium PROD_M. A writing unit PROD_C2 for writing. The moving image encoding apparatus 2 described above is used as the encoding 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 of the type connected to the recording device PROD_C, such as a card or USB (Universal Serial Bus) flash memory, or (3) DVD (Digital Versatile Disk) or BD (Blu-ray Disk: registration) Or a drive device (not shown) built in the recording device PROD_C.

The recording device PROD_C receives a moving image as a supply source of a moving image to be input to the encoding unit PROD_C1, a camera PROD_C3 that captures a moving image, an input terminal PROD_C4 for inputting a moving image from the outside, and a moving image. The receiving unit PROD_C5 may be further provided. FIG. 12A illustrates a configuration in which the recording apparatus PROD_C includes all of these, but some of them may be omitted.

The receiving unit PROD_C5 may receive a non-encoded moving image, or may receive encoded data encoded by a transmission encoding scheme different from the recording encoding scheme. You may do. In the latter case, a transmission decoding unit (not shown) that decodes encoded data encoded by the transmission encoding method may be interposed between the reception unit PROD_C5 and the encoding unit PROD_C1.

Examples of such a recording device PROD_C include a DVD recorder, a BD recorder, and an HD (Hard Disk) recorder (in this case, the input terminal PROD_C4 or the receiving unit PROD_C5 is a main source of moving images). In addition, a camcorder (in this case, the camera PROD_C3 is a main source of moving images), a personal computer (in this case, the receiving unit PROD_C5 is a main source of moving images), a smartphone (in this case, the camera PROD_C3 or The receiving unit PROD_C5 is a main source of moving images) is an example of such a recording apparatus PROD_C.

(B) of FIG. 12 is a block showing a configuration of a playback device PROD_D equipped with the above-described video decoding device 1. As shown in (b) of FIG. 12, the playback device PROD_D reads a moving image by decoding a read unit PROD_D1 that reads encoded data written on the recording medium PROD_M and a coded data read by the read unit PROD_D1. And a decoding unit PROD_D2 to be obtained. The moving picture decoding apparatus 1 described above is used as the decoding unit PROD_D2.

Note that the recording medium PROD_M may be of the 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 (3) may be loaded into a drive device (not shown) built in the playback device PROD_D, such as DVD or BD. Good.

In addition, the playback device PROD_D has a display PROD_D3 that displays a moving image, an output terminal PROD_D4 that outputs the moving image to the outside, and a transmission unit that transmits the moving image as a supply destination of the moving image output by the decoding unit PROD_D2. PROD_D5 may be further provided. FIG. 12B illustrates a configuration in which the playback apparatus PROD_D includes all of these, but a part of the configuration may be omitted.

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

Examples of such a playback device PROD_D include a DVD player, a BD player, and an HDD player (in this case, an output terminal PROD_D4 to which a television receiver or the like is connected is a main supply destination of moving images). . In addition, a television receiver (in this case, the display PROD_D3 is a main destination of moving images), a desktop PC (in this case, the output terminal PROD_D4 or the transmission unit PROD_D5 is a main destination of moving images), Laptop type or tablet type PC (in this case, display PROD_D3 or transmission unit PROD_D5 is the main supply destination of moving images), smartphone (in this case, display PROD_D3 or transmission unit PROD_D5 is the main supply destination of moving images) ) Is an example of such a playback device PROD_D.

(Appendix 1)
Finally, each block of the moving picture decoding apparatus 1 and the moving picture encoding apparatus 2 described above may be realized in hardware by a logic circuit formed on an integrated circuit (IC chip), or may be a CPU (Central It may be realized by software using a Processing Unit).

In the latter case, each device includes a CPU that executes instructions of a program that realizes each function, a ROM (Read （Memory) that stores the program, a RAM (Random Memory) that expands the program, the program, and various types A storage device (recording medium) such as a memory for storing data is provided. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of each of the above devices, which is software that realizes the above-described functions, is recorded so as to be readable by a computer. This can also be achieved by supplying to each of the above devices and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

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 disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. IC cards (including memory cards) / optical cards, semiconductor memories such as mask ROM / EPROM / EEPROM / flash ROM, or PLD (Programmable logic device) or FPGA (Field Programmable Gate Array) Logic circuits can be used.

Also, each of the above devices may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network (Virtual Private Network), telephone line network, mobile communication network, satellite communication network, etc. can be used. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even in the case of wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR ( It can also be used by wireless such as High Data Rate, NFC (Near Field Communication), DLNA (Digital Living Network Alliance), mobile phone network, satellite line, and terrestrial digital network.

(Appendix 2)
As described above, the decoding apparatus according to the present invention has the prediction mode designation information for designating the elements of the prediction mode set including the elements of the first prediction mode group and the elements of the second prediction mode group by a single code. A decoding device for generating a decoded image by decoding encoded data obtained by encoding together with a prediction image generated for each prediction unit to a prediction residual decoded from the encoded data, Prediction mode specifying means for specifying a prediction mode specified by the prediction mode specification information from the code according to a predetermined correspondence between the code and a prediction mode specified by the code; The prediction mode to which the prediction mode specified by the prediction mode specification information belongs from the code according to a predetermined correspondence relationship with the prediction mode group to which the specified prediction mode belongs A prediction mode group specifying means for specifying a group of commands and a prediction parameter selection means for selecting a prediction parameter, wherein the prediction mode group specified by the prediction mode group specifying means is the first prediction mode group, The prediction mode corresponding to the prediction mode specified by the prediction mode specifying unit is selected from the first prediction parameter group including one or more prediction parameters corresponding to the prediction mode group, and the prediction mode group specifying unit specifies When the prediction mode group is the second prediction mode group, the prediction mode specifying unit specifies the second prediction parameter group including one or more predetermined prediction parameters corresponding to the second prediction mode group. A prediction parameter selection means for selecting a prediction parameter corresponding to the prediction mode, and a prediction parameter selected by the prediction parameter selection means. Is characterized in that it comprises a, the predicted image generating means for generating the predicted image Te.

In the decoding device according to the present invention, the single code is composed of first designation information and second designation information, and the prediction mode specifying unit is configured such that the first designation information is a target prediction unit. When the estimated prediction mode estimated based on the prediction mode assigned to the surrounding prediction units is the same as the target prediction mode assigned to the target prediction unit, the estimated prediction mode is selected. When the estimated prediction mode and the target prediction mode are different, it is preferable to further decode the second designation information and select a prediction mode using the estimated prediction mode and the second designation information.

According to said structure, the 1st designation | designated information is estimated based on the prediction mode allocated to the prediction unit of the circumference | surroundings of a target prediction unit, The target prediction mode allocated to the said target prediction unit, If the estimated prediction mode is different from the target prediction mode, the second designation information is further decoded, and the estimated prediction mode and the first prediction mode are selected. Since the prediction mode is selected using the designation information 2, the code amount of the single code is reduced, and the coding efficiency is improved.

In the decoding apparatus according to the present invention, the number of the first prediction parameters is greater than 1, and the prediction parameter selection unit is configured such that the prediction mode group specified by the prediction mode group specifying unit is the first prediction mode. In the case of a group, it is preferable to decode a second code different from the single code and select a prediction parameter corresponding to the second code from the first prediction parameter group.

According to the above configuration, when the prediction mode group specified by the prediction mode group specifying unit is the first prediction mode group, the second code different from the single code is decoded, and the first code Since the prediction parameter corresponding to the second code is selected from one prediction parameter group, the prediction parameter can be appropriately decoded.

In the decoding device according to the present invention, the first prediction parameter group includes a prediction direction derived by referring to a decoded pixel value located around a target prediction unit that is a processing target prediction unit. The predicted image generation means includes a decoded pixel value positioned around the target prediction unit along the direction indicated by the prediction parameter when the prediction parameter selection means selects the prediction parameter. It is preferable to generate a prediction image for the target prediction unit by extrapolating or interpolating.

According to the above configuration, the first prediction parameter group includes a prediction parameter indicating a prediction direction derived with reference to a decoded pixel value located around the target prediction unit that is a prediction unit to be processed. included.

Further, according to the above configuration, the prediction image generation unit, the prediction image generation unit, when the prediction parameter selection unit selects the prediction parameter, the target prediction unit along the direction indicated by the prediction parameter. A predicted image for the target prediction unit is generated by extrapolating or interpolating the decoded pixel values located in the vicinity of.

Generally, the directionality of the image in the decoded image around the target prediction unit tends to have a high correlation with the directionality of the prediction target image in the target prediction unit. Therefore, according to the above configuration, by using the prediction parameter indicating the prediction direction derived by referring to the decoded pixel values located around the target prediction unit, prediction with high prediction accuracy for the target prediction unit is performed. An image can be generated.

In the decoding device according to the present invention, the first prediction parameter group includes a prediction direction indicating a prediction direction derived with reference to a decoded image located around a target prediction unit that is a prediction unit to be processed. A prediction parameter indicating a prediction direction obtained by adding one or a plurality of correction directions to the prediction direction, and the prediction image generation unit selects the prediction parameter by the prediction parameter selection unit. In this case, it is preferable to generate a prediction image for the target prediction unit by extrapolating or interpolating decoded pixel values located around the target prediction unit along the direction indicated by the prediction parameter. .

According to the above configuration, the first prediction parameter group includes a prediction parameter indicating a prediction direction derived by referring to a decoded image located around the target prediction unit that is a processing target prediction unit; A prediction parameter indicating a prediction direction obtained by adding one or a plurality of correction directions to the prediction direction.

In addition, when the prediction parameter selection unit selects the prediction parameter, the prediction image generation unit extrapolates or decodes a decoded pixel value located around the target prediction unit along the direction indicated by the prediction parameter. A prediction image for the target prediction unit is generated by interpolation.

Here, the correction direction is more accurate in predicting the predicted image than in using only the predicted direction derived with reference to the decoded image located around the target prediction unit in the encoding device that generates encoded data. Selected to increase.

Therefore, according to the above configuration, it is possible to further improve the prediction accuracy of the predicted image as compared with the configuration in which the first prediction parameter group includes only the prediction parameter indicating the prediction direction.

Also, compared to a configuration in which a code for designating one or a plurality of correction directions needs to be encoded, the configuration of encoded data and the decoding process are simplified.

The decoding apparatus according to the present invention further comprises an encoding scheme identifying means for identifying whether or not the encoded data is arithmetically encoded, and the prediction parameter selecting means includes the encoded data It is preferable to select a prediction parameter in accordance with the prediction mode specified by the prediction mode specifying unit and the prediction mode group specified by the prediction mode group specifying unit only when it is not arithmetically encoded.

According to the decoding apparatus according to the present invention, when the encoded data is non-arithmetic encoded, the effect of reducing the code amount of the encoded data tends to increase.

Therefore, as described above, it further includes an encoding scheme identifying means for identifying whether or not the encoded data is arithmetically encoded, and the prediction parameter selecting means specifies the prediction mode for the target prediction unit. Only when the information is not arithmetically encoded, it is sufficient to select the prediction mode specified by the prediction mode specifying unit and the prediction parameter corresponding to the prediction mode group specified by the prediction mode group specifying unit. The amount of code can be reduced.

In the decoding apparatus according to the present invention, the prediction parameter selection unit includes the prediction mode specified by the prediction mode specifying unit and the prediction mode only when the predetermined flag included in the encoded data has a predetermined value. It is preferable to select a prediction parameter corresponding to the prediction mode group specified by the prediction mode group specifying means.

According to said structure, the said encoding data designates the prediction mode designation | designated information which designates the element of the prediction mode set which consists of the element of a 1st prediction mode group, and the element of a 2nd prediction mode group by a single code | symbol. The decoding apparatus performs a decoding process with reference to the single code when the predetermined flag has a predetermined value. Can do.

Therefore, according to the above configuration, it is possible to selectively switch between performing the decoding process referring to the single code or performing the decoding process referring to a code different from the single code.

In the above configuration, the first prediction mode group includes a prediction parameter indicating a prediction direction derived by referring to a pixel value of a decoded image located around a target prediction unit that is a processing target prediction unit. A data structure of encoded data, characterized in that a corresponding prediction mode is included.

In the above configuration, the first prediction mode group includes a prediction parameter indicating a prediction direction derived by referring to a pixel value of a decoded image located around a target prediction unit that is a processing target prediction unit. An encoding comprising: a corresponding prediction mode; and a prediction mode corresponding to a prediction parameter indicating a prediction direction obtained by adding one or a plurality of correction directions to the prediction direction. The data structure of the data.

In the above configuration, the encoded data has the same estimated prediction mode estimated based on the prediction mode assigned to the prediction units around the target prediction unit and the prediction mode assigned to the target prediction unit. 1st designation | designated information which shows whether it exists, and when the said estimation prediction mode and the prediction mode allocated to the said object prediction unit differ, the prediction mode allocated to the said object prediction unit is designated. A data structure of encoded data, further comprising second designation information.

(Appendix 3)
As described above, in this specification, residual data between an original image and a predicted image generated for each prediction unit is obtained from the elements of the first prediction mode group and the elements of the second prediction mode group. A decoding apparatus for decoding encoded data obtained by encoding together with prediction mode specifying information specifying elements of a prediction mode set by a single code, between the code and the prediction mode specified by the code Between the prediction mode specifying means for specifying the prediction mode specified by the prediction mode specification information from the code and the prediction mode group to which the prediction mode specified by the code belongs. A prediction mode group specifying means for specifying a prediction mode group to which the prediction mode specified by the prediction mode specification information belongs from the code and a prediction parameter are selected according to a predetermined correspondence. When the prediction mode group specified by the prediction mode group specifying means is the first prediction mode group, a first parameter including one or more prediction parameters derived with reference to the decoded image is selected. When a prediction parameter corresponding to the prediction mode specified by the prediction mode specifying unit is selected from the prediction parameter group, and the prediction mode group specified by the prediction mode group specifying unit is the second prediction mode group, it is determined in advance. A prediction parameter selection means for selecting a prediction parameter corresponding to the prediction mode specified by the prediction mode specification means from the second prediction parameter group consisting of one or more prediction parameters, and a prediction parameter selected by the prediction parameter selection means. And a prediction image generating means for generating the prediction image according to the above description. It has been.

In the decoding device according to the present invention, the first prediction parameter group includes a prediction parameter indicating an edge direction of a decoded image located around a target prediction unit that is a processing target prediction unit, and the prediction parameter The image generation means extrapolates or interpolates decoded pixel values located around the target prediction unit along the direction indicated by the prediction parameter when the prediction parameter selection means selects the prediction parameter. It is preferable to generate a prediction image for the target prediction unit by the above.

According to the above configuration, the first prediction parameter group includes the prediction parameter indicating the edge direction of the decoded image located around the target prediction unit that is the processing target prediction unit.

In general, when an edge exists in a decoded image around the target prediction unit, the direction of the edge is highly correlated with the direction of the edge in the prediction target image in the target prediction unit or the directionality of the prediction target image. Tend. Therefore, according to the above configuration, a prediction image with high prediction accuracy can be generated for the target prediction unit by using the prediction parameter indicating the edge direction.

In the decoding device according to the present invention, the first prediction parameter group includes a prediction parameter indicating an edge direction of a decoded image located around a target prediction unit that is a prediction unit to be processed, and the edge direction. A prediction parameter indicating a prediction direction obtained by adding any one or a plurality of correction directions to the prediction image generation unit, when the prediction parameter selection unit selects the prediction parameter, the prediction parameter generation unit It is preferable to generate a prediction image for the target prediction unit by extrapolating or interpolating decoded pixel values located around the target prediction unit along the direction indicated by.

According to the above configuration, the first prediction parameter group includes the prediction parameter indicating the edge direction of the decoded image located around the target prediction unit that is the prediction unit to be processed, and 1 or 1 in the edge direction. And a prediction parameter indicating a prediction direction obtained by adding any of a plurality of correction directions.

Here, the correction direction is selected so that the prediction accuracy of the prediction image is higher than that in the case of using only the edge direction in the encoding device that generates the encoded data.

Therefore, according to the above configuration, it is possible to further improve the prediction accuracy of the predicted image as compared with the configuration in which the first prediction parameter group includes only the prediction parameter indicating the edge direction.

The decoding apparatus according to the present invention further includes an encoding scheme identifying means for identifying whether or not the prediction mode designation information is arithmetically encoded, and the prediction parameter selecting means includes the target prediction unit. Only when the prediction mode designation information is not arithmetically encoded, the prediction mode specified by the prediction mode specifying unit and the prediction parameter corresponding to the prediction mode group specified by the prediction mode group specifying unit are selected. It is preferable.

According to the decoding apparatus according to the present invention, when the prediction mode designation information is non-arithmetic encoded, the effect of reducing the code amount of the encoded data tends to increase.

Therefore, as described above, the encoding mode identifying means for identifying whether or not the prediction mode designation information is arithmetically encoded is further provided, and the prediction parameter selection means includes the prediction mode for the target prediction unit. Only when the designation information is not arithmetically encoded, by selecting the prediction mode specified by the prediction mode specifying means and the prediction parameter according to the prediction mode group specified by the prediction mode group specifying means, A sufficient amount of code can be reduced.

An encoding apparatus according to the present invention is an encoding apparatus that generates encoded data by encoding residual data between an original image and a predicted image generated for each prediction unit, and includes a prediction parameter. A first prediction parameter group comprising one or more prediction parameters derived by referring to a locally decoded image, or a second prediction comprising one or more predetermined prediction parameters. Corresponding to a prediction parameter selection unit that selects a prediction parameter from a parameter group, a prediction image generation unit that generates the prediction image according to the prediction parameter selected by the prediction parameter selection unit, and a prediction parameter selected by the prediction parameter selection unit Prediction mode designation information code that encodes prediction mode designation information that designates the prediction mode to be performed by a single code And the single code is assigned to each element of the first prediction mode group consisting of prediction modes corresponding to each element of the first prediction parameter group and each element of the second prediction parameter group. It is characterized in that the elements of the prediction mode set including the elements of the second prediction mode group consisting of the corresponding prediction modes are distinguished from each other.

In a data structure of encoded data generated by encoding residual data between an original image and a predicted image generated for each prediction unit, a prediction parameter to be selected by the decoding device to generate a predicted image is set. Prediction mode designation information for designating a corresponding prediction mode by a single code, and the single code is a prediction corresponding to each of one or more prediction parameters derived by the encoding device with reference to a locally decoded image The elements of the first prediction mode group consisting of the mode and the elements of the prediction parameter set consisting of the elements of the second prediction mode group consisting of the prediction mode corresponding to each of the predetermined prediction parameters are mutually identified. is there,
A data structure of encoded data characterized by the above.

The first prediction mode group includes a prediction mode corresponding to a prediction parameter indicating an edge direction of a decoded image located around a target prediction unit that is a processing target prediction unit. Data structure of encoded data to be performed.

The first prediction mode group includes a prediction mode corresponding to a prediction parameter indicating an edge direction of a decoded image located around a target prediction unit that is a prediction unit to be processed, and one or more in the edge direction. A data structure of encoded data, comprising: a prediction mode corresponding to a prediction parameter indicating a prediction direction obtained by adding any of the correction directions.

In the encoded data, whether or not the estimated prediction mode estimated based on the prediction mode assigned to the prediction unit around the target prediction unit and the prediction mode assigned to the target prediction unit are the same. Including first designation information to indicate,
When the estimated prediction mode is different from the prediction mode assigned to the target prediction unit, the prediction prediction mode further includes second designation information for designating a prediction mode assigned to the target prediction unit. Data structure of encoded data.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

The present invention can be suitably applied to a decoding device that decodes encoded data and an encoding device that generates encoded data. Further, the present invention can be suitably applied to the data structure of encoded data generated by the encoding device and referenced by the decoding device.

1 Video decoding device (decoding device)
11 Variable length code decoding unit (prediction mode specifying means)
12 Prediction image generation unit 12b Inter prediction image generation unit 12c Intra prediction image generation unit (prediction mode group specifying unit, prediction parameter selection unit, prediction image generation unit)
15 frame memory 2 video encoding device (encoding device)
21 prediction image generation unit 21a intra prediction image generation unit 21c inter prediction image generation unit (prediction parameter selection unit, prediction image generation unit)
25 Frame memory 27 Variable length code encoding unit (prediction mode designation information encoding means)

Claims

Decoding encoded data obtained by encoding together with prediction mode designating information for designating elements of a prediction mode set composed of elements of the first prediction mode group and elements of the second prediction mode group by a single code A decoding device that generates a decoded image by adding a prediction image generated for each prediction unit to a prediction residual decoded from encoded data,
Prediction mode specifying means for specifying the prediction mode specified by the prediction mode specification information from the code according to a predetermined correspondence between the code and the prediction mode specified by the code;
A prediction mode for specifying a prediction mode group to which a prediction mode specified by the prediction mode specifying information belongs from the code according to a predetermined correspondence relationship between the code and a prediction mode group to which the prediction mode specified by the code belongs Group identification means;
Prediction parameter selection means for selecting a prediction parameter,
When the prediction mode group specified by the prediction mode group specifying means is the first prediction mode group, the prediction mode is selected from the first prediction parameter group including one or more prediction parameters corresponding to the first prediction mode group. Select the prediction parameter corresponding to the prediction mode specified by the specifying means,
When the prediction mode group specified by the prediction mode group specifying means is the second prediction mode group, from the second prediction parameter group including one or more predetermined prediction parameters corresponding to the second prediction mode group A prediction parameter selection means for selecting a prediction parameter corresponding to the prediction mode specified by the prediction mode specifying means;
A decoding apparatus comprising: predicted image generation means for generating the predicted image in accordance with the prediction parameter selected by the prediction parameter selection means.
The single code is composed of first designation information and second designation information, and the prediction mode specifying means includes a prediction mode in which the first designation information is assigned to a prediction unit around the target prediction unit. When the estimated prediction mode estimated based on the target prediction mode and the target prediction mode assigned to the target prediction unit are the same, the estimated prediction mode is selected, and the estimated prediction mode and the target prediction mode are 2. The decoding apparatus according to claim 1, wherein if different, the second designation information is further decoded, and the prediction mode is selected using the estimated prediction mode and the second designation information.
The number of the first prediction parameters is greater than 1, and the prediction parameter selection unit is configured to use the single prediction mode group when the prediction mode group identified by the prediction mode group identification unit is the first prediction mode group. The decoding apparatus according to claim 1 or 2, wherein a second code different from the code is decoded, and a prediction parameter corresponding to the second code is selected from the first prediction parameter group.
The first prediction parameter group includes a prediction parameter indicating a prediction direction derived by referring to a decoded pixel value located around a target prediction unit that is a processing target prediction unit,
When the prediction parameter selection unit selects the prediction parameter, the prediction image generation unit extrapolates or interpolates the decoded pixel values located around the target prediction unit along the direction indicated by the prediction parameter. To generate a prediction image for the target prediction unit,
The decoding device according to any one of claims 1 to 3, wherein
The first prediction parameter group includes a prediction parameter indicating a prediction direction derived by referring to a decoded image located around a target prediction unit that is a processing target prediction unit, and one or a plurality of prediction directions in the prediction direction. A prediction parameter indicating a prediction direction obtained by adding any of the correction directions,
When the prediction parameter selection unit selects the prediction parameter, the prediction image generation unit extrapolates or interpolates the decoded pixel values located around the target prediction unit along the direction indicated by the prediction parameter. To generate a prediction image for the target prediction unit,
The decoding apparatus according to claim 3.
Encoding means for identifying whether or not the encoded data is arithmetically encoded, further comprising:
The prediction parameter selection means responds to the prediction mode specified by the prediction mode specifying means and the prediction mode group specified by the prediction mode group specifying means only when the encoded data is not arithmetically encoded. Select forecast parameters,
The decoding device according to claim 1, wherein
The prediction parameter selection means is the prediction mode specified by the prediction mode specifying means and the prediction mode specified by the prediction mode group specifying means only when a predetermined flag included in the encoded data has a predetermined value. Select prediction parameters according to the group,
The decoding device according to claim 1, wherein
An encoding device that generates encoded data by encoding residual data between an original image and a predicted image generated for each prediction unit,
Prediction parameter selection means for selecting a prediction parameter, wherein a prediction parameter is obtained from a first prediction parameter group consisting of one or more prediction parameters or a second prediction parameter group consisting of one or more predetermined prediction parameters. A prediction parameter selection means to select;
A predicted image generating means for generating the predicted image according to the prediction parameter selected by the prediction parameter selecting means;
Prediction mode designation information encoding means for encoding prediction mode designation information for designating a prediction mode corresponding to the prediction parameter selected by the prediction parameter selection means by a single code, and
The single code includes a first prediction mode group element including a prediction mode corresponding to the first prediction parameter group and a second prediction mode corresponding to each element of the second prediction parameter group. The elements of the prediction mode set consisting of the elements of the prediction mode group are distinguished from each other.
An encoding apparatus characterized by that.
In the data structure of the encoded data generated by encoding the residual data between the original image and the predicted image generated for each prediction unit,
Including prediction mode designation information that designates a prediction mode corresponding to a prediction parameter to be selected by the decoding device to generate a prediction image by a single code;
The single code is an element of a first prediction mode group consisting of prediction modes corresponding to one or more prediction parameters, and a second prediction mode group consisting of prediction modes corresponding to each of the predetermined prediction parameters. The elements of the prediction parameter set consisting of
A data structure of encoded data characterized by the above.
The first prediction mode group includes a prediction mode corresponding to a prediction parameter indicating a prediction direction derived by referring to a pixel value of a decoded image located around a target prediction unit that is a processing target prediction unit. The encoded data structure according to claim 9, wherein the encoded data structure is included.
The first prediction mode group includes a prediction mode corresponding to a prediction parameter indicating a prediction direction derived by referring to a pixel value of a decoded image located around a target prediction unit that is a processing target prediction unit; A prediction mode corresponding to a prediction parameter indicating a prediction direction obtained by adding any one or a plurality of correction directions to the prediction direction.
The data structure of encoded data according to claim 9.
In the encoded data, whether or not the estimated prediction mode estimated based on the prediction mode assigned to the prediction unit around the target prediction unit and the prediction mode assigned to the target prediction unit are the same. Including first designation information to indicate,
In the case where the estimated prediction mode and the prediction mode assigned to the target prediction unit are different from each other, second prediction information that specifies the prediction mode assigned to the target prediction unit is further included.
The data structure of encoded data according to any one of claims 9 to 11, wherein the data structure is encoded data.