The present, invention relates to a video encoding device and a video decoding device that use PCM encoding. Background Art
[0002]
Patent Literature (PTL) 1 proposes a video encoding net-hod for embedding, in an output bitstream, information indicating a block type that is not subjected to a transform process and an entropy encoding process, in order to guarantee a certain processing time for a video encoding device or a video decoding device.
[0 0031
An example of the block type that is not subjected to the transform process and the entropy encoding process is pulse code modulation (PCM) described in Nor, Patent Literature (NPL) 1. The term block type means an encoding type (below-mentioned intra prediction, inter prediction, and PCM) used for a block.
[0004]
A video encoding device described in NPL 1 has a structure shown in Fig. 14. The video encoding device shown in Fig. 14 is hereafter referred to as a typical video encoding device.
[0005]
A structure and an operation of the typical video encoding device that receives each frame of dig!tized video as input and outputs a bitstream are described below, with reference to Fig. 14.

[0006]
The video encoding device shown in Fig. 14 includes a transformer/quantizer 102, an entropy encoder 103, an inverse transformer/inverse quantizer 104, a buffer 105, a predictor 106, a PCM encoder 107, a PCM decoder 108, a multiplex data selector 109, a multiplexer 110, a switch 121, and a switch 122.
[0007]
The video encoding device shown in Fig. 14 divides each frame into blocks of 16 x 16 pixel size called macroblocks (MBs), and encodes each MB sequentially from top left of the frame. In AVC described in NPL 1, each MB is further drvided into blocks of 4 * 4 pixel si.ze, and each block of 4 x 4 pixel size is encoded.
[0008]
Fig. 15 is an explanatory diagram showing an example of block division in the case where the frame has a spatial reso ir.it ion of QCIF (Quarter Common Intermediate Format) . The following describes an operation of each unit while focusing only on pixel values of luminance, for simplicity's sake.
[0009]
A. prediction signal supplied from the predictor 106 is subtracted from the block-divided input video, and the result is i.nput to the transformer/quantizer 102 . There are two types of prediction signal, namely, an intra prediction signal and an inter-frame prediction signal. Each of the prediction signals is described below.
[ ooio;
The intra prediction signal is a prediction signal generated based on an image of a reconstructed picture that has the same display time as a current picture and is stored in the buffer 105. Referring to 8.3.1 Intra d=<4 prediction process for luma samples, 8.3.2 intra 8*8

prediction process for lama samples, and 8.3.3 Intra 16*16 oredictJ on process for luraa samples in NPL 1, intra prediction of three block sizes, i.o. Intra 4x4, intra 8*8, and Intra_16*16, are available.
[0011]
Intra 4*4 and Intra_8><8 are respectively intra orediction of 4 * 4 block size and 8*3 block size, as can be understood from (a) and (c) in Fig. 16. Each circle (o) in the drawing represents a reference pixel used for intra prediction, i.e. a pixel of the reconstructed picture having the same display time as the current picture.
[0012]
In intra prediction of Intra_4*4, reconstructed peripheral pixels are directly set as reference pixels, and used for padding (extrapolation) in nine directions shown in (b) in Fig. 16 to form the prediction signal. In intra prediction of Intra 8x8, pixels obtained by smoothing peripheral pixels of the image of the reconstructed picture by low-pass filters (1/2, 1/4, 1/2) shown under the right arrow in (c) in Fig. 16 are set as reference signals, arid used for extrapolation in the nine directions shown, in (b) in Fig. 16 to form the prediction signal.
[0013]
Similarly, Intra_16>ul6 is intra prediction of 16 x 16 block size, as can be understood from (a) .in Fig. 17. Each circle (o) in the drawing represents a reference pixel used for intra prediction, i.e. a. pixel of the reconstructed picture having the same display time as the current picture, as in Fig. 16. In intra prediction of Intra 16x16, peripheral pixels of the reconstructed image are directly set. as reference pixels, and used for extrapolation in four directions shown, in (b) in F.i g. 17 to form the prediction signal,
[0014]

Hereafter, an MB and a block encoded using the intra prediction signal, are respectively referred to as an intra MB and an intra block, a block size of intra prediction is referred, to as an intra prediction block size, and a direction of extrapolation is referred to as an intra prediction direction. The intra prediction block size and the intra prediction direction are prediction parameters related to intra pred i.ction . |0 01b:
The inter-frame prediction signal is a prediction signal generated from an image of a reconstructed picture that has a different display time from the one the current, picture has and is stored in the buffer 105. Hereaiter, an MB and a block encoded using the inter-frame prediction signal are respectively referred to as an inter MB and an inter block. A block size of inter prediction {inter prediction block size) can be selected from, for example, 16x16, 16x8, 8 * 16, 8*8, 8x4, 4*8, and 4x4. [0016]
Fig. 18 is an explanatory diagram showing an example of inter-frame prediction using 16 * 16 block size. A motion vector MV = (mvx, mvy) shown in Fig. 18 is a prediction parameter of inter-frame prediction, which indicates the amount of parallel translation of an inter-frame prediction block (inter-frame prediction signal) of a reference picture relative to a block to be encoded. In AVC, prediction parameters of inter-frame prediction include not only an inter-frame prediction direction representing a direction of the reference picture oC the inter-frame prediction signal relative to a picture to be encoded of the block to be encoded, but also a reference picture index for identifying the reference picture used for inter-frame prediction of the block to be encoded. This is because, in AVC, a plurality of reference pictures

stored in the buffer 105 can be used for inter-frame prediction.
[0017]
Inter-frame prediction is described in more detail in 8.4 Inter prediction process in NPL 1.
[00181
A picture encoded including only intra MBs is called an I picture. A picture encoded including not. only intra MBs but also inter MBs is called a P picture. A picture encoded including inter MBs that use not only one reference picture but two reference pictures simultaneously for inter-frame prediction is called a B picture. In the B picture, inter-frame predrction in which the direction of the reference picture of the inter-frame prediction signal relative to the picture to be encoded of the block to be encoded is to the past is called forward prediction, inter-frame prediction in which the direction of the reference picture of the inter-frame prediction signal relative to the picture to be encoded of the block to be encoded is to the future is called backward prediction, and inter-frame prediction involving both the past and the future is called bidirectional prediction. The' direction of inter-frame prediction (inter prediction direction) is a. prediction parameter of inter-frame prediction.
[0019]
The transformer/quantizer 102 frequency-transforms the image (prediction error image) from which the predictron signal has been subtracted.
[0020]
The transformer/quantizer 102 further quantizes the frequency-transformed prediction error image (frequency transform coefficient), with a predetermined quantization step width Qs. Hereafter, the quantized frequency transform coefficient rs referred to as a transform

quantization value.
[0021]
The entropy encoder 103 entropy-encodes the prediction parameters and the transform quantisation value. The prediction parameters are information relaxed to MB and block prediction, such as block type (intra prediction, inter prediction, and PCM), intra prediction block size, intra prediction direction, inter prediction block size, and motion vector mentioned above.
[0022]
The inverse transformer/inverse quantizer 10 4 inverse-quantizes the transform quantization value, with the quantization step width Qs. The inverse transformer/inverse quantizer 104 further inverse-frequency-transforms the frequency transform coefficient obtained by the inverse quantization. The prediction signal rs added to the reconstructed prediction error image obtained by the inverse frequency transform, and the result is supplied to the switch 122.
[0023]
The multiplex data selector 10 9 monitors the amount of input data of the entropy encoder 103 corresponding to the MB to be encoded. In the case where the entropy encoder 103 is capable of entropy-encoding the input data within a processing time of the MB, the multiplex data selector 109 selects the output data of the entropy encoder 103, and causes !:he selected data to be supplied to the multiplexer 110 via the swrtch 121. The multiplex data selector 109 further selects the output, data of the inverse transformer/inverse quantizer 104, and causes the selected data to be supplied to the buffer 105 via the switch 122.
[0024]
In the case where the entropy encoder 103 is not-capable of entropy-encoding the input data within the

processing Lime of the MB, the multiplex data selector 109 selects the output data of the PCM encoder 107 obtained, by PCM encoding the video of the MB, and causes the selected data to be supplied to the multiplexer 110 via the switch 121. The multiplex data selector 109 further selects the output data of the PCM decoder 108 obtained by PCM decoding the output data of the PCM encoder 107, and causes the selected data to be supplied to the buffer 105 via the switch 12 2,
[0025]
The buffer 105 stores the reconstructed image supplied, via the switch 122. The reconstructed image per frame is referred to as a reconstructed picture.
[0026]
The multiplexer 110 multiplexes the output data of the entropy encoder 103 and. the PCM encoder 107, and outputs the multiplexing result.
[0027]
Based on the operation described above, the .multiplexer "J 10 .in the video encoding device generates the bitstream.
Citation List Patent Literature
[0028]
PTL 1: Japanese Patent Application Laid-Open No. 2004-135251 Non Patent Literatures
[002 9]
NPL 1: ISO/IPC 14496-10 Advanced Video Coding NPL 2: "Test Model under Consideration", Document: JCTVC-B2 05, Joint Collaborative Team on Video Coding (JCT-VC} of ITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11 2nd Meeting: Geneva, CH, 21.-28 July, 2.010

NPL 3: W.-J. Chen, X. Wang, and M. Karczewi.cz, "CE5 Improved coding of inter prediction mode with LCEC," JCTVC-D37 0
NPL 4: S. Liu, Y.-W. Huang, S. Lei, "Remove Partition Size NxN," JCTVC-D432
Summary of Invention Technical Problem
[0030]
The typical technique described above guarantees a certain processing time for a video encoding device or a video decoding device by using, in MBs, PCM that does not involve a transform process and an entropy encoding process. [0031]
However, the typical technrque described above is baaed on video encoding that uses MBs of a fixed coding unit size (CU size). Accordingly, as described in NPL 2, when the typical technique described above is applied to video encoding (hereafter referred to as Test Model under Consideration scheme (TMuC scheme)) that uses coding units (coding tree blocks (CTBs)) of a quadtree structure shown in Fig. 19 where the CU size is variable and information (PCM header) indicating PCM is embedded rn the output bitstream in CTBs of all layers (i.e. all depths), there is a problem that the ratio of the number of bits of the PCM header included in the bitstream increases and so the quality of compressed video decreases. [0032]
Here, a maximum CTB is referred to as a largest coding tree block (LCTB), and a minimum CTB is referred to as a smallest coding tree block (SCTBj . In this Description, a block corresponding to the CTB is referred to as a coding unit (CU) . Moreover, a concept of a prediction unit (PU) (see Fig. 20) as a unit of prediction

for the CU is introduced in the TMuC scheme. Fig. 2 0 is an explanatory diagram for describing the PU, where only the squares from among the shapes shown in Fig. 20 are supported as the intra prediction block size. [0033]
NPL 3 describes improvements in signaling of inr.er prediction. NPL 4 describes improvements in signaling of inter prediction and intra prediction. [0034]
To solve the problem of the typical technique described above, the point that PCM may be selected in a higher-layer CU in order to guarantee a certain 'processing time for a video encoding device or a video decoding device is taken into consideration. The higher-layer CU rs a CU of a smaller depth value, as can be seen from Fig. 19. The number of higher-layer CUs per frame is smaller because their block size is larger. Since the number of higher-layer CUs is smaller, the ratio of the number of bits of the PCM header included in the bitstream can be reduced.
'[0035]
In the present invention, the problem is solved by limiting the depth of the CU for which the PCM header .is transmitted, in video encoding based on PCM encoding. That .is, in the present invention, the CU size for which the PCM header is transmitted is limited to a predetermined size.
Solution to Problem
[0036]
A video decoding device according to the present invention includes: extraction means for extracting PCM block size information from a bitstream; PCM block size determination means for determining a minimum value of a PCM block size for parsing a PCM header based on the PCM block size information; PCM header parsing means tor

parsing from the bitstream the PCM header whose block has equal to or more than the minimum value of the PCM block size; entropy decoding means for parsing transformed data of an image in the bitstream; PCM decodrng means for decoding by PCM decoding PCM data of the image in the bitstream.; and decoding control means for controlling the entropy decoding means and the PCM decoding means based on the PCM header.
[0037]
A video decoding method according to the present invention includes: extracting PCM block size information from a bitstream; determining a minimum value of a PCM block srze for parsing a PCM header based on the PCM block, size information; parsing from the bitstream. the PCM header whose block has egual to or more than the minimum value of the PCM block size; controlling an entropy decoding process and a PCM decoding process based on the PCM header; parsing transformed data of an image rn the bitstream upon the entropy decoding process being controlled; and decodrng by ?CM-decoding PCM data of the image in the bitstream upon the PCM decoding process berng controlled.
[0038]
A computer readable information recording medium storing a video decoding program according to the present invention causes a computer to execute: an extraction process of extracting PCM block size information from a bitstream; a PCM block size determination process of determining a minimum value of a PCM block size for parsing a PCM header based on the PCM block size information; a process of parsing from the bitstream the PCM header whose block has equal to or more than the minimum value of the PCM block size; and a process of controlling an entropy decoding process and a PCM decodrng process based on the PCM header, wherein the computer is caused to parses

transformed data of an image in the bitstream upon the entropy decoding process being controlled, and wherein the computer is caused to decode by PCM-decoding PCM data of I he .image in the Di I: stream, upon the PCM decoding process being controlled.
Advantageous Effects of Invention
[0039]
According to the present invention, the coding unit size for which the PCM header is signaled is limited to the predetermined size, so that the ratio of the number of bits of the PCM header in the bitstream can be kept lew and the quality of compressed video can be maintained, while guaranteeing a certain processrng time for the video encoding device.
[0040]
Moreover, according to the present invention,, the .interoperability of the video encoding device and the video decoding device can be enhanced by embedding, in the bitstream, the PCM coding unit size information for signaling the predetermined size to the video decoding device.
Brief Description of Drawings
[0041] ' [Fig. 1] Fig. 1 is a block d.i agram of a video encoding device in Exemplary Embodiment 1.
[Fig. 2) Fig. 2 is an explanatory diagram of list 1 indicating a PCM header in PU syntax.
[Fig. 3] Fig. 3 is an explanatory diagram, of list 2 indicating PCM coding unit size information in a sequence parameter set.
[Fig. 4] Fig. 4 is a flowchart showing a PCM header-writing operation.

[Fig. 5] Fig. b is a block diagram of a video decoding device in Exemplary Embodiment 2.
[Fig, 6] Fig. 6 is a flowchart showing a PCM header parsing operation.
[Fig. 7] Fig. 7 is an explanatory diagram of list 3 indicating PCM coding unit size information in a picture parameter set.
[Fig. 8] Fig. 8 is an explanatory diagram of list 4 indicating PCM coding unit size information in a slice header.
[Fig. 9] Fig. 9 is an explanatory diagram of list 1 indicating a PCM header in PU syntax in Exemplary Embodiment 3.
[Fig. 10] Fig. 10 is a flowchart showing a PCM header parsing operation in Exemplary Embodiment 3.
[Fig. 11] Fig. 11 is a block diagram showing a structural example of an information processing system capable of realizing functions of a video encoding device and a video decoding d.evice according to the present invention.
[Fig. 12] Fig. 12 is a block diagram showing a main part of a video encoding device according to the present invention.
[Fig. 13] Fig. 13 is a block diagram showing a main part of a video decoding device according to the present invention..
[Fig. 14] Fig. 14 is a block diagram of a. typical video encoding device,
[Fig. 15] Fig. 15 is an explanatory diagram showing an example of block division.
[Fig. 16] Fig. 16 is an explanatory diagram for describing prediction types.
[Fig. 17] Fig. 17 is an explanatory diagram for describing prediction types.

[Fig. 18] Fig. 18 is an explanatory diagram showing an example of inter-frame prediction using 16 x 16 block size as an 'example.
[Fig. 19] Fig. 19 is an explanatory diaqram for describing a CTB.
[Fig, 20] Fig. 20 is an explanatory diagram for describing a PU.
Description of Embodiment(s)
[0042] Exemplary Embodiment 1
Exemplary Embodiment 1 shows a video encoding device including: means for selecting output data of entropy encoding means or PCM encoding means in a CU size set from the outside; means for embedding, in a bitstream, a PCM header in the CU size set from the outside; and means for embedding, in the bitstream:, information related to a PCM coding unit size for signaling the CU size set from the outside to a video decoding device.
[0043]
To provide description using specific examples, rn this exemplary embodiment it is assumed that the CU size for which the PCM header is embedded in the bitstream is greater than or equal to a PCM coding unit srze set from the outside (pcmCodingUnitSize). It is also assumed that available coding unit sizes are 128, 64, 32, 16, and 8, and pcmCodingUnitSize is 16. It is further assumed that the information related to the PCM coding unit size is base-2 log (logarithm) of a value obtained by dividing the PCM coding unit size by the minimum coding unit size, as described later. Hence, in this exemplary embodiment, block sizes corresponding to CU sizes for which the PCM header is embedded in the bitstream are 128 x 12 8, 64 x 64, 32 * 32, and 16 x 16. Moreover, a specific value of the CU

size-related information embedded in the bits cream is 1 ( = log2{16/8)).
[0044]
As shown in Fig'. 1, the video encoding device in this exemplary embodiment includes a transformer/quantizer 102, an entropy encoder 103, an inverse transformer/inverse quantizer 104, a buffer 105, a predictor 106, a PCM encoder 107, a PCM decoder 108, a multiplex data selector 109, a multiplexer 110, a switch 121, and a switch 122, like the typical video encoding device shown in Fig, 14. The video encoding device in this exemplary embodiment shown in Fig. 1 differs from the' video encoding device shown in Fig. 14 in that pcmCodingUnitSize is supplied to the multiplex data selector 109 in order to transmit the PCM header in a CU size more than or equal to pcmCodingUnitSize, and pcmCodingUnitSize is also supplied to the multiplexer 110 in order to signal pcmCodingUnitSize to the video decoding device.
I. 0 0 4 5 ]
A prediction signal supplied from the predictor 106 is subtracted from, input video of a CU size, and the result is input to the transformer/quantizer 102.
[0046]
The transformer/quantizer 102 frequency-transforms the image (prediction error image) from which the prediction signal has been subtracted.
[0047]
The transformer/quantizer 102 further quantizes the frequency-transformed prediction error image (frequency transform coefficient), with a quantization step width Qs.
[0048]
The entropy encoder 103 entropy-encodes split_coding_unit_flag (see Fig. 19) for signaling the CU size, prediction parameters supplied from the predictor 106,

and the transform quantization value supplied from the transformer/quantizer 102. The prediction parameters are information related to prediction of the CU to bo encoded, such as block type (intra prediction, .inter prediction, and PCM), intra prediction block size, intra prediction direction, inter prediction block size, and motion vector.
[0049]
Based on pcmCod.i.ngUnitSize set from the outside via the multiplex data selector 109, the entropy encoder 103 in this exemplary embodiment entropy-encodes pcm_flag syntax, which indicates ON/OFF of PCM encoding, as OFF, in the case where the CU to be encoded has a size greater than or equal to pcmCodinqUnitSize and also has a prediction mode of intra prediction.
[0050]
The inverse transformer/inverse quantizer '! 01 inverse-quantizes the transform quantization value, with the quantization step width Qs . The .inverse transformer/inverse quantizer 104 further inverse-frequency-transforms the frequency transform coefficient obtained by the inverse quantization. The prediction signal is added to the reconstructed prediction error image obtained by the inverse frequency transform., and the result is supplied to the switch 122.
[0051]
The multiplex data selector 109 monitors the amount of input data of the entropy encoder 103 corresponding to the CU to be encoded that is greater than or equaJ to pcmCodingUnrtSize. In the case where the entropy encoder 103 is capable of entropy-encoding the input data within a processing time of the CO to be encoded: that is greater than or equal to pcrnCodingUnitSize, the multiplex data selector 10 9 selects the output data of the entropy encoder 103, and causes the selected data to be supplied to the

multiplexer 110 via the switch 121. The multiplex data selector 109 further selects the output data of the inverse transformer/inverse quantizer 104, and causes the selected data to be supplied to the buffer 105 via the switch 122.
[0052]
In the case where the entropy encoder 103 is not capable of entropy-encoding the input data within the processing time of the CU to be encoded, the multiplex data selector 109 first causes the entropy encoder 103 to entropy-encode and output information indicating that the CU greater than or equal to pcmCodingUnitSize is encoded by PCM encoding. In detail, the multiplex data selector 109 causes the entropy encodei 103 to entropy-encode and output mode table_id.x syntax or pred^mode syntax, which indicates a block type, as intra prediction, and entropy-encode and output the pcm_flag syntax, which indicates ON/OFF of PCM encoding, as ON, in a PU header of the CU.
[0053]
Next, the output bits of the entropy encoder "103 are byte-aidgned. In detail, the entropy encoder: 103 supplies a predetermined.amount of pern alignment zero bit syntax to the multiplexer 110. Moreover, an encoding engine of the entropy encoder 103 is initialized for subsequent encoding.
[0054]
After the encoding engine is initialized, the PCM encoder 107 encodes by PCM encoding the input video of the CU. Output data pcm_sample_luma[i] of luminance of the PCM encoder 107 has a pixel bit length bd.t depth d.uma of luminance of the input video. Here, -i (0 < i C 2551 is an index in raster scan order within the block of the CU. Likewise, output data pem sample chroma[i] (i: 0 < i < 128) of color difference of the PCM encoder 107 has a pixer bit length bit depth_chroma of color difference of the input video.

[0055]
After the input video of the CU is encoded by PCM encoding, the PCM decoder 108 decodes by PCM- decoding pcm_sample_luma [i] and pcrri_sample_chroma [i] .
[0056]
After the PCM decoding, the multiplex data selector
109 selects the output data of the PCM encoder 107, and causes the selected data to be supplied to the multiplexer
110 via the switch 121.
[0057]
Lastly, the multiplex data selector 109 selects the. output data of the PCM decoder 108, and causes the selected data to be supplied to the buffer 105 via the switch 122.
[0058]
When complying with Specification of syntax functions, categories, and descriptors in NPL 1 and 4.1.10 Prediction unit syntax in NPL 2, the 'above-mentioned mode_table idx syntax, pred_mode syntax, pcm_flag syntax, and pcm_alignment zero bit syntax can be signaled as represented in list 1 shown in Fig. 2. In list 1, a variable pern unit flag which is a signaling condition of the pcm_aLignment zero_bit syntax is ON only in the case where the pcm_flag syntax for PCM encoding ON is signaled. Otherwise, the variable pem^unit flag is OFF. This exemplary embodiment has a feature that, in lisL 1, the pem flag syntax is signaled only in the PU header of the CU of the size greater than or egual to pcmCodingUnitSize, according to the condition "if(currPredUnitSize >= pcmCodingUnitSize) " .
[0059]
The multiplexer 110 multiplexes the information (max_pcm coding_unit_hierarchy depth) related to the PCM coding unit size and the output data of the entropy encoder 103 and the PCM encoder 107, and outputs the multiplexing

result. When complying with 4.1.2 Sequence parameter set RBSP syntax in NPL 2, max_pcm_coding unit hierarchy depth syntax (base-2 log (logarithm) of a value obtained by dividing the PCM coding unit size by the m.inimum coding unit size, "1" in this exemplary embodiment) is multiplexed following log2 min coding_unit_size minus3 syntax and max_coding unit hierarchy_depth syntax of a sequence parameter set, as represented in list 2 shown in Fig. 3. Here, max_pcni coding unit_hierarchy depth may be called min_pom_coding_unit_hierarchy depth. The log'2 min coding unit size minus3 syntax and the max_coding_unit_hierarchy_depth syntax are information for determining a SCU size (MinCodingUnitSize) and a LCU size (MaxCodingUnitSize), respectively. MinCodingUnitSize and MaxCodingUnitSize are respectively computed as follows. [0060]
MinCodingUnitS.i ze = 1 << (log2_min_coding_unit size_minus3 + 3) [0061]
MaxCodingUnitSize = I << (log2_min_coding_unit size_mmus3 + 3 + max coding_unit_hierarchy_depth)
[0062]
The max_ coding_unit hierarchy depth synta.x and MinCodingUnitSize have the following relation.
[0063]
max pcm_coding unit hierarchy depth = log2 (pcmCodingUnitSize/MinCodingUnitSize)
[0064]
Based on the operation described above, the video encoding device according to the present invention generates the bitstream.
[0065]
The following describes a PCM header writing

operation which is a feature of the present invention, with reference to the flowchart in Fig. 4. [0066]
As shown in Fig. 4, in the case of not being capable of entropy-encoding within the processing time of the CU to be encoded, the entropy encoder 103 entropy-encodes the block type as intra prediction in step 5101. That, is, the entropy encoder 103 entropy-encodes the mode table idx syntax or the pred_mode syntax as intra prediction. In step S102, the entropy encoder 103 entropy-encodes the PCM header. In detail, the entropy encoder ]03 entropy-encodes one pcm_flaq syntax as ON. In step S103, the entropy encoder 103 byte-aligns the output bits by supplying the predetermined amount of the pem alignment zero bit syntax to the multiplexer 110. That is, the entropy encoder 103 outputs the predetermined amount of the
pem alignment^ zero bit syntax. The entropy encoder: 103 also initializes the encodrng engine. In step S104, the PCM encoder 107 encodes by PCM encoding the input video of the CU.
[0067]
The video encoding device in this exemplary embodiment includes: multiplex data selection means for selecting output data of entropy encoding means or PCM encodrng means in a coding unit size set from the outside; and multiplexing means for embedding, in a bitstream, a PCM header in the coding' unit size set from the outside. Therefore, the ratio of the number of bits of the PCM header in the bitstream can be kept low and the quality of compressed video can be maintained, while guaranteeing a certain processing time for the video encoding device.
[0068]
Moreover, the multiplexing means embeds, .in the bitstream, PCM coding unit size information for signaling

the CU size set from the outside to the video decoding device, where the CU size information can be expressed by, for example, a depth difference relative to a. depth of a LCU or a SCU. For instance, in the case of expression relative to the depth of the LCU (LCU depth), a CU size of a predetermined depth can be expressed as i/2[depzh ~ '-cc.dept.h) of the LCU size (1/4(depth " LCU-dePth> when converted to block size) . In the case of expression relative to the depth of the SCU (SCU_depth), a CU size of a predetermined depth can be expressed as 2':sc:'J-deptf' " depth) times the SCU size (4iSCU depf:h deptn) tj_mes when converted to block size) .
[0069]
By the inclusion of the multiplexing means having the above-mentioned feature, the present invention can enhance the interoperability of the video encoding device and the video decoding device.
[0070]
The video encoding device in this exemplary embodiment .Includes means for embedding, rn the bit stream, the information related to the coding unit size for which the PCM header is provided, so as to enable the PCM header to be parsed from, the bitstream and switching between entropy decoding means and PCM decoding means to be performed equally in video decoding. The interoperability of the video encoding device and the video decoding' device can thus be enhanced.
[0071] Exemplary Embodiment 2
Exemplary Embodiment 2 shows a video decoding device that decodes the bitstream generated by the video encoding device in Exemplary Embodiment 1.
[0072]
The video decoding device in. this exemplary embodiment includes: means for de-multiplexing PCM coding

unit size information multiplexed in the bitstream; block size means for determining a predetermined block size for which a PCM header is parsed, based on the de-multiplexed PCM coding unit size information; parsing means for parsing the PCM header from the bitstream in. the coding unit size determined by the block size means; and decoding control means for controlling entropy decoding means and. PCM decoding means based on the PCM header parsed by the parsing means.
[0073]
As shown in Fig. 5, the video decoding device in this exemplary embodiment includes a de-multiplexer 201, a decoding controller 202, a PCM decoder 203, an entropy decoder 204, an inverse transformer/inverse quantizer 206, a predictor 207, a buffer 208, a switch 221, and a switch 222.
[0074]
The de-multiplexer 201 de-multiplexes the input bitstream, and. extracts the PCM coding unit si ze information and the entropy-encoded or PCM-encoded video bitstream. The dc-multiplexer 201 de-multiplexes the max_pcm_coding_unit_hierarchy_depth syntax following the log2_min_coding _unit_size_minus3 syntax and the max_coding unit_h.i erarchy depth syntax in the sequence parameters, as represented in list 2 shown m Fig. 3. The de-mult, .i plcxer 201 v:ben determines, using the de¬multiplexed syntax values, the PCM coding unit size pcmCodingUnitSize for which pcm_flag as the PCM header is transmitted, as follows.
[0075]
pcmCodingUn] tSi. ze ^ 1 << (log2_m±n_coding_unit_size_minus3 + 3 t max_pcm_coding_unit_hierarchy_depth)
[0076]

Thus, the de-multiplexer 201 in this exemplary embodiment also has a function of determining the block size of the coding unit for which the PCM header is parsed, based on the de-multiplexed PCM coding unit size information.
[0077]
The entropy decoder 2 04 entropy-decodes the video b i t s t r e am.
[0078]
In the case where the coding unit (CU) to be entropy-decoded is not a PCM-encoded CU, the entropy decoder 2 04 entropy-decodes the prediction parameters and the transform quantization value of the CU, arid suppli.es them to the inverse transformer/inverse quantizer' 206 and the predictor 207.
[0079]
Note that a CU is PCM-encoded in the case where, after split_coding_unit flag (see Fig. 19} is entropy-decoded and the CU size is determined, the pem flag syntax indicating PCM encoding ON in the PU header is entropy-decoded. Thus, the entropy decoder 204 in this exemplary embodiment also has a function of parsing the PCM header Including the pcm_iilag syntax from the bitstream in the CU of the size greater than or equal to pcmCodingUnitSize.
[0080]
The inverse transformer/inverse quantizer 206 inverse-quantizes the transform quantization value of luminance and color difference, with a quantization step width. The inverse transformer/inverse quantizer 206 further inverse-frequency-transforms the frequency transform coefficient obtained by the inverse quantization.
[0081]
After the inverse frequency transform, the predictor 207 generates a prediction signal using an image of a

reconstructed picture stored in the buffer 208, based on the entropy-decoded prediction parameters.
[0082]
After the prediction signal generation, the prediction signal, supplied from the predictor 207 is added to the reconstructed prediction error image obtained by the inverse frequency transform by the inverse transformer/inverse quantizer 2 06, and the result is supplied to the switch 2 22.
[0083]
After the addition of the prediction signal, the decoding controller 202 switches the switch 222 to supply the reconstructed prediction error image to which the prediction signal has been added to the buffer 208 as the reconstructed image.
[ 0 0 8 4 ]
In the case where the CU is PCM-encoded, the decoding controller 202 causes a decoding engine of the entropy decoder 204 to be initialized.
[0085]
The decoding controller 2 02 then causes the video bitstream which is in the middle of entropy decoding, to be byte-aligned. The decoding controller 202 causes pcm_alignment_zero_b.it to be parsed from the video bitstream until byte-aligned.
[0086]
following this, the decoding controller 2 02 switches the switch 221 to supply the byte-aligned video bitstream to the PCM decoder 203.
[0087]
The PCM decoder 203 decodes by PCM decoding PCM-encoded luminance data pcm sample luma[i] and color difference data pcm_sample_chroma[i] corresponding to the block size of the CU, from the byte-aligned video bitstream.

[0088]
After the PCM decoding, the decoding controller 202 switches the switch 222 to supply the PCM decoded coding unit image to the buffer 208 as the reconstructed image. The decoding controller 202 switches the switch 221 to the entropy decoder 204, for decoding of a next macrobiock.
[0089]
The reconstructed, picture stored in the buffer 208 is then output as a decoded image.
[0090]
Based on the operation described above, the video decoding device in this exemplary embodiment generates the decoded image .
[0091]
The following describes a PCM header parsing operation which is a feature of the present invention, with reference to the flowchart in Fig. 6.
[0092]
As shown in Fig. 6, in the case where the CU rs PCM-encod.ed, the entropy decoder 204 entropy-decodes split_coding_ unit_ flag and determines the CU size in seep S201. In step S202, the entropy decoder 204 entropy-decodes the block type. That is, the entropy decoder 204 entropy-decodes the mode_table_idx syntax or the pred mode syntax. In steps S203 and S204, the entropy decoder 204 entropy-decodes the pcm_flag syntax only in the case where the block type is intra prediction and the CU size is a size greater than or equal to pcmCodingUnrtSize. Tn the case where the pem flag syntax is ON, in step S205 the entropy decoder 204 initializes the decoding engine. The entropy decoder 2 04 also byte-aligns the vrdeo bitstream by parsing the predetermined amount of the
pem alignment_zero bit syntax from the de-multiplexer 201, The PCM decoder 2 03 decodes by PCM decoding the PCM-encoded

luminance data pcm_sample luma[i] and color difference data pcm_sample_chroma[1] corresponding to the CU block size, from the byte-aligned video bitstream. In the case where the CU is not a PCM-encoded CU (step S2 03) or in the case where the entropy decoder 2 04 does not entropy-decode the pcm_flag syntax indicating PCM encoding ON in the PU header {step S204), the entropy decoder 204 entropy-decodes the prediction parameters and the transform quantization value of the following CU, and supplies them to the inverse transformer/inverse quantizer 206 and the predictor 207.
[0093]
The vrdeo decoding device in this exemplary embodiment can parse, based on the de-multiplexed PCM coding unit size information, the PCM header from the bitstream in the coding unit of the determined PCM coding unit size, and switch between the entropy decoding means and the PCM decoding means. Therefore, the bitstream in which the ratio of the number of bits of the PCM header is low to thereby maintain video quality can be decoded while guaranteeing a certain processing time for the video decoding device.
[0094]
Note that the video encoding device may multip.]_ex the PCM coding unit size information
(max_pcm coding_unit_hierarchy_depth) used in Exemplary Embodiment 1, in a picture parameter set or a slrce header as represented in list 3 shown in Fig. 7 or list 4 shown in Fig. 8. Similar.!.y, the -video decoding device may de¬multiplex the max pcm_cod.i.ng unit_hierarchy depth syntax from the picture parameter set or the slice header.
[0095]
Moreover, the max_pcm_coding_unit_hierarchy depth syntax may be base-2 log (logarithm) of a value obtained by dividing the maximum coding unit size (MaxCodingUnitSize)

by the PCM coding unit size (pcmCodingUnitSize). That is, the following expression may be used.
[0096]
max pern coding unit hierarchy depth = log2 (MaxCodingUnitSize/pcmCodingUnitSize)
[00 97]
In this case, in the video decoding device, the PCM coding unit size can be computed based on the max_pcm_coding_unit_bierarchy_depth syntax as follows.
[0098]
pcmCodingUnitSize = 1 << (log2 min coding unit size_minus3 + 3 + max _coding_un.it hierarchy depth -max_pcm_coding_unit_hierarchy depth)
[0099]
Note that the video encoding device may concatenate and encode the pem flag syntax with the mode table idx syntax or the pred_niode syntax. For example, in a CU of a size greater than or equal to the PCM coding unit, size, mode_table_idx = 0 (codeword 1) may be set as inter predrction, mode table idx = 1 (codeword 00) as intra prediction wrth pcm_flag = OFF, and mode table idx = 2 (codeword 01) as PCM. In a CU of a size less than the PCM codrng unit size, mode table_id.x = 0 (codeword 0) may be set as inter prediction, and mode_table_idx - 1 (codeword 1) as intra prediction with pcm_flag - OFF.
[010 0]
In this case, in the CU of the size greater than or equal to the PCM codrng unit size, the video decoding device interprets codeword 1 (mode_table idx = 0) as inter prediction, codeword 00 (mode_tabie idx = J.) as intra prediction with pcm_flag = OFF, and codeword 01 (mode_table_idx =2) as PCM. in the CU of the size less than the PCM coding unit size, the video decoding device

interprets codeword 0 (mode_table_ idx ^=0) as inter prediction, and codeword 1 (mode^table_idx = lj as intra prediction with pern flag = OFF.
[0101] Exemplary Embodiment 3
In each of the exemplary embodiments described above, PCM is selected rn a higher-layer CU in order to guarantee a certain processing time for the video encoding device or the video decoding device. However, in the case of taking into consideration that PCM tends to be selected in an image block having low inter-pixel correlation, i.e. PCM tends to be selected in a lower-layer CU of a divided small region, it is also significant to limit to a predetermined size or less the CU size for which PCM is selected. Based on such consideration, the ratio of the number of bits of the PCM header in the bitstream can also be reduced. The lower-layer CU mentioned here is a CU having a larger depth value, as can be seen from Fig. 19.
[0102]
In Exemplary Embodiment 3, a video encoding device limits the CU size for which PCM rs selected, to the predetermined size or less. The vrdeo encoding device has the same structure as shown in Fig. 1.
[0103]
In the case of limiting the CU size for: which PCM is selected to the predetermined size or less, the CU size for which the PCM header rs embedded in the bitstream :i s set to be less than or egual to the PCM coding unit size set from the outside (pcmCodrngUnitSize), as an example. Ic is also assumed that available coding unit sizes are 128, 64, 32, 16, and 8, and pcmCodingUnitSize is 16.
[ 010 4 J
In the video encoding device, the multiplex data selector 109 monitors the amount of input data of the

entropy encoder 103 corresponding to the CU to be encoded that is less than or equal to pcmCodingUnitSize. In the case where the entropy encoder 103 is capable of entropy-encoding' the input data within a processing time of the CU to be encoded that is less than or equal to
pcmCodingUn.i tSize, the multiplex data selector 109 selects the output data of the entropy encoder 103, and causes the selected data to be supplied to the multiplexer 110 via the switch 121. In the case where the entropy encoder 103 is not capable of entropy-encoding the input data within the processing time of the CU to be encoded, the multiplex data selector 109 first causes the entropy encoder 3.03 to entropy-encode and output information indicating that the CU whose size is less than or equal to pcmCodingUnrtSi ze is PCM-encoded. In detail, the multiplex data selector 109 causes the entropy encoder 103 to entropy-encode and output the mode table idx syntax or the pred mode syntax, which indicates the block type, as intra prediction, and entropy-encode and output the pcm flag syntax, which indicates ON/OFF of PCM encoding, as ON, in the PU header of the CU.
[0105]
In this exemplary embodiment, when complying with Specification of syntax functions, categories, and descriptors in NPL 1 and 4.1.10 Pred.i ction unit syntax in NPL 2, the 'video encoding device can signa] the above-mentioned mode table_idx syntax, pred mode syntax, pcm flag syntax, and pcm_alignment_zero_bit syntax as represented in list 1 shown in Fig. 9. In list 1 shown in Fig. 9, the variable pcm unit_flag which is a signaling condition of the pcm_alignment zero bit syntax is ON only in the case where the pcm_flag syntax for PCM encoding ON is signaled. Otherwise, the variable pcm_unit_flag is OFF. This exemplary embodiment has a feature that, in list 1, the pcm_flag syntax is signaled only in the PU header of the CU

whose size is less than or equal to pcmCodingUnitSize, according to the condition "if (currPredUni.tSize <^ pcrriCodingunitSize) " . The other processes of the vjdeo encoding device are the same as the processes in Exemplary Embodiment 1. Besides, the contents of list 1 in this exemplary embodiment are the same as the contents of list 1 shown in Fig. 2 in Exemplary Embodiment 1.
[0106] Exemplary Embodiment 4
Exemplary Embodiment 4 shows a video decoding device that decodes the bitstream generated by the video encoding device in Exemplary Embodiment 3.
[0107]
The video decoding device in Exemplary Embodiment 4 has the same structure as shown in Fig. 5. In Exemplary Embodiment 4, however, the video decoding device performs a PCM header parsing operation as shown in the flowchart in Fig. 10. In the case where the CU is PCM-encoded, the entropy decoder 204 entropy-decodes split_coding unit flag and determines the CU srze in step S201. In step S202, the entropy decoder 204 entropy-decodes the block type. That is, the entropy decoder 204 entropy-decodes the mode_table_idx syntax or the pred mode syntax. In steps S203B and S204, the entropy decoder 204 entropy-decodes the pcm__flag syntax only in the case where the block type is intra prediction and the CU size is a size less than or egual to pcmCodingUnitSize. In the case where the pcm flag syntax is ON, in step S205 the entropy decoder 204 initializes the decoding engine. The entropy decoder 2 04 also byte-aligns the video bitstream by parsing the predetermined amount of the pcm_alignment_zero_bit syntax from the de-multiplexer 201. The PCM decoder 203 decodes by PCM decoding the PCM-encoded luminance data pcm_sample_luma[i] and color difference data

pcm_sample_chroma[11 corresponding to the CO block size, from the byte-ali.gn.ed video bitstreara. The other processes of the video decoding device are the same as the processes in Exemplary Embodiment 2 .
[0108]
in the case of limiting to the predetermined size or less the CU size for which PCM is selected, the entropy decoder 204 in the video decoding device also has a function of parsing the PCM header including the pom flag syntax from the bitstream in the CU whose size is less than or equal to pcmCodingUnitSize.
[ 0 ] 0 9 !
in this exemplary embodiment, the bitstream .in which the ratio of the number of bits of the PCM header rs low to thereby maintain video quality can be decoded while guaranteeing a certain processing time for the video decoding device.
[0110]
Note that the video encoding device in Exemplary Embodiment 3 may concatenate and encode the pom flag syntax with the mode table_idx syntax or the pred mode syntax. For example, in a CU of a size less than or equal to the PCM coding unit size, mode_table idx = 0 (codeword 0) may be set as intra prediction with pcm_flag = OFF, mode_table idx = 1 (codeword 10} as inter predj.ct.iori/ and mode_table idx = 2 (codeword 11) as PCM. In a CU of a size greater than the PCM coding unit size, mode table idx = 0 (codeword 0} may be set as intra prediction with pern flag = OFF, and mode table idx = 1 (codeword 1) as inter prediction.
[0111]
In this case, in the CU of the size less than or equal to the PCM coding unrt size, the video decoding device in Exemplary Embodiment 4 interprets codeword 0

(mode^table_idx =0) as intra prediction with pcm flag -OFF, codeword 10 (mode table_idx =1) as inter prediction, and codeword 11 (mode_table_idx =2) as PCM. In the CU of the s.ize greater than the PCM coding unit size, the video decoding device interprets codeword 0 (mode_table idx = 0) as intra prediction with pcm_flag = OFF, and codeword 1 (mode table_idx = 1) as inter prediction.
[0112]
The pcm flag syntax may be concatenated and encoded with the pred_mode syntax, in the same manner as in the example of the mode_table_idx syntax.
[0113]
In the exemplary embodiments described above, in the case of limiting the PCM coding unit, size to the maximum coding unit size, the PCM block size information need not be explicitly embedded in the bitstream. This is because the information related to the maximum coding unit size implicitly includes the PCM block size information in such a case.
[0114]
In the exemplary embodiments described above, in the case of limiting the PCM coding unit size to one minimum coding unit size, the PCM block size information need not be explicitly embedded m the bitstream. This is because the information related, to the minimum codrng unit size implicitly includes the PCM block size information in such a case .
[0115]
The pcm_flag syntax may be concatenated and encoded with the pred_mode syntax, in the same manner as in the above-mentioned example of the mode table idx syntax. For instance, in an intra slice, syntax and codeword, can be associated as follows, as described in NPL 3 (note that this is based on an assumption that no N * N partition

(intra prediction-and inter prediction) exists in a. coding unit other than a minimum coding unit as described in NPI 4) •
[0116] [Correspondence between syntax and codeword in minimum coding unit including PCM encoding]
Syntax Codeword
Intra 2N*2N 1
Intra N*N 01
PCM 0 0
[0117] [Correspondence between syntax and codeword in CU other than minimum coding unit including PCM encoding]
Syntax Codeword
Intra 2Nx2N 1
PCM 0
[0118] [Correspondence between syntax and codeword in minimum coding unit not including PCM encoding]
Syntax Codeword
Intra 2N*2N 1
Intra NxN 0
[ 011 9 ] [Correspondence between syntax and codeword in minimum coding unit not including PCM encoding]
Syntax Codeword
Intra 2Nx2N none
Note that "CU including PCM encoding" is a CU of the PCM coding unit size, and "CU not including PCM encoding" is a CU of not the PCM coding unit size. In. this case, for example in the minimum coding unit including PCM encoding in the intra slice, the video decoding device interprets codeword 1 as 2N*2N 'Intra prediction, codeword 01 as N^N intra prediction, and codeword 00 as PCM.

[0120]
Likewise, in a non-intra slice, syntax and codeword can be associated as follows.
[01211 [Correspondence between syntax and codeword common to all CUs]
Syntax Codeword
Split 1
Skip 01
Inter 2Nx2N_MRG 001
Inter 2N><2N 0001
Others 0000
[Correspondence between syntax and codeword in minimum coding unit rncluding PCM encoding, following Others]
Syntax Codeword
Inter 2N*N 0
Inter Nx2N 01
Inter N*N 001
Intra 2N*2N 0001
Intra N*N 00001
PCM 0 0000
[0122] [Correspondence between syntax and codeword in CU other than minimum coding unit including PCM encoding, following Others]
Syntax Codeword
Inter 2N*N 0
Inter Nx2N 01
Intra 2N*2N 001
PCM 00 0
[0123] [Correspondence between syntax and codeword in minimum coding unit not including PCM encoding, following Others]
Syntax Codeword

[0124] [Correspondence between syntax and codeword in CU other than minimum coding unit not including PCM encoding, following Others]
Syntax Codeword
Inter 2N*N 0
Inter Nx2N 01
Intra 2Nx2N 00
[0125]
In this case, for example in the minimum coding unit, including PCM encoding, the video decoding device interprets codeword 0 following Others as 2N*N inter-prediction, codeword 01 as N*2N inter prediction, codeword 001 as NxN inter prediction, codeword 0001 as 2N*2N intra prediction, codeword 00001 as NxN intra prediction, and codeword 00000 as PCM.
[0126]
Note that the intra slice is a slice composed of only coding units encoded by intra prediction, and the non-intra slice is a slice including coding units encoded by inter prediction.
[0127]
Each of the exemplary embodiments described, above-may be realized by hardware, or may be realized by a computer program.
[0128]
An information processing system shown in Fig. 11 includes a processor 1001, a program memory 1002, a storage medium 1003 for storing video data, and a storage medium

1004 for storing a bitstream. The storage medium 1003 and the storage medium 1004 may be separate storage medra, or may be storage areas included in the same storage medium. As a storage medium, a magnetic storage medium such as a hard disk is applicable.
[0129]
In the information processing system shown in Fig. 11, a program for realizing the functions of the blocks (except the block of the buffer) shown in each of Figs. 1 and 5 is stored in the program memory 1002. The processor 1G01 realizes the functions of the video encoding device or the video decoding device shown in Fig. 1 or 5, by executing processing according to the program stored in the program memory 1002.
[ 013 0 |
Fig. 12 is a. block diagram showing a main part of a video encod.ing device according to the present invention. As shown in Fig. 12, the video encoding device according to the present invention includes: transform means 11 (e.g. the transformer/quantizer 102 shown in Fig. 1) for transforming an image block; entropy encoding means 12 (e.g. the entropy encoder 103 shown in Fig. 1) for entropy-encoding transformed data of the image block transformed by the transform means 11; PCM encoding means 13 (e.g. the PCM encoder 107 shown in Fig. 1) for encoding by PCM encoding the image block; multiplex data selection means 14 (e.g. the multiplex data selector 109 and the switch 121) for selecting output data of the entropy encoding means 12 (e.g. the entropy encoder 103 shown in Fig. 1) or the PCM encoding means 13, in a block of a block size set from, the outside; and multiplexing means 15 (e.g. the multiplexer' 110 shown in Frg. 1) for embedding a PCM header in a bitstream, in the block of the block srze set from the outside .

Fig. 13 is a block diagram showing a main part, of a video decoding device according to the present invention. As shown in Fig. 13, the video decoding device according to the present invention includes: de-multiplexing means 21 (e.g. the de-multiplexer 201 shown in Fig. 5) for de¬multiplexing a bitstream including PCM block size information; PCM block size determination means 2 2 (e.g. the de-multiplexer 201 shown in Fig. 5) for determining a PCM block size for which a PCM header is parsed, based on the PCM block size information de-multiplexed by the de-multrplexing means 21; PCM header parsing means 23 {e.g. the entropy decoder 2 04 shown in Fig. 5) for parsing the PCM header from the bitstream, in a block of the PCM block size determined by the PCM block size determination means 2 2; entropy decoding means 24 {e.g. the entropy decoder 204 shown in Fig. 5) tor entropy-decoding transformed data of an image in the bitstream; inverse transform means 25 (e.g. the inverse transformer/inverse quantizer 206 shown in Fig. 5) for inverse-transforming the transformed data entropy-decoded by the entropy decoding means 24; PCM decoding means 26 {e.g. the PCM decoder 203 shown in Pig. 5) for decoding by PCM decoding PCM data of the image in the bitstream; and decoding control means 2 7 (e.g. the decoding controller 202 shown in Fig. 5) for controlling the entropy decoding means 24 and the PCM decoding means 26, based on the PCM header parsea by the PCM header parsing means 23.
[0132]
The exemplary embodiments described above may be partly or wholly described in the following supplementary notes, though the present invention is not limited to the following structures.
[0133] (Supplementary note 1) A video encoding device wherein the

multiplexing means embeds, in the bitstream, information related to N as PCM block size information, in the case where the externally-set block size is greater than or equal to 1/4N of a block size corresponding to a maximum coding unit size or in the case where the externally-set block size is greater than or equal to 4N times a block size corresponding to a minimum coding unit size.
[0134] (Supplementary note 2) A video decoding device wherein the de-multiplexing means obtains information related to N as the PCM block size information, in the case where tne block srze is greater than or equal to 1/4'' of a block size corresponding to a maximum codrng unit size or in 'the case where the block size is greater than or equal to .41" times a block size corresponding to a minimum coding unit size.
[0135] (Supplementary note 3) A video encoding device wherein the multiplexing means embeds, in the bitstream, information related to N as PCM block size information, in the case where the externally-set block size is less than or equal to 1/4 of a block size corresponding to a maximum coding unit size or in the case where the externally-set block size is less than or equal to 4B times a block size corresponding to a minimum coding unit size.
[0136] (Supplementary note 4) A video decoding device wherein the de-multiplexing means obtains information related to N as the PCM block size information, in the case where the block size is less than or equal to 1/4W of a block size corresponding to a maximum coding unit size or in the case where the block size is less than or equal to 4* times a block size corresponding to a minimum coding unit size.
[0137]
Though the present invention has been described with

reference to the above exemplary embodiments arid examples, the present invention is not limited to the above exemplary embodiments and examples. Various changes understandable by those skilled in the art within the scope of the present invention can be made to the structures and details of the present invent],on.
[0138]
This application claims priority based on Japanese Patent Application No. 2010-264320 filed on November 26, 2010 and Japanese Patent Application No. 2011-026 331 filed on February 9, 2011, the disclosures of which are incorporated herein in their entirety.