WO2012090478A1

WO2012090478A1 - Moving image coding method and moving image decoding method

Info

Publication number: WO2012090478A1
Application number: PCT/JP2011/007281
Authority: WO
Inventors: 敏康杉尾; 西　孝啓; 陽司柴原; 寿郎笹井
Original assignee: パナソニック株式会社
Priority date: 2010-12-28
Filing date: 2011-12-26
Publication date: 2012-07-05

Abstract

An image coding method for assigning at least two or more reference picture indexes to at least one or more reference pictures different from a picture to be coded including a block to be coded, and coding the block to be coded, said image coding method comprising: a same reference picture determination step for, when the two or more reference picture indexes are used when the block to be coded is coded, determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same pictures (S403); and a prediction direction switching step for, on the basis of the result of the determination in the same reference picture determination step, switching the prediction direction when the block to be coded is coded in a predetermined coding mode (S404, S405).

Description

Moving picture encoding method and moving picture decoding method

The present invention relates to a moving image encoding method and a moving image decoding method.

In the moving image encoding process, in general, the amount of information is compressed using redundancy in the spatial direction and temporal direction of a moving image. As a method of using redundancy in the spatial direction, conversion to the frequency domain is used, and as a method of using redundancy in the temporal direction, inter-picture prediction (hereinafter referred to as inter prediction) encoding processing is used. . In the inter prediction encoding process, when a certain picture is encoded, an encoded picture that is ahead or behind in the display time order with respect to the encoding target picture is used as a reference picture. Then, by detecting the motion vector of the encoding target picture with respect to the reference picture and taking the difference between the predicted image data obtained by performing motion compensation based on the motion vector and the image data of the encoding target picture, time Remove direction redundancy.

, H. already standardized. In the moving picture encoding method called H.264, three types of picture types, i.e., I picture, P picture, and B picture, are used for compressing the amount of information. An I picture is a picture that does not perform inter prediction coding processing, that is, performs intra-picture prediction (hereinafter referred to as intra prediction) coding processing. The P picture is a picture that performs inter prediction encoding with reference to one already encoded picture that is in front of or behind the current picture in display time order. The B picture is a picture that performs inter prediction encoding with reference to two already encoded pictures that are in front of or behind the current picture in display time order.

H. In the moving picture encoding method called H.264, the inter prediction encoding mode of each encoding target block in a B picture was used for generating a difference value between predicted image data and the encoding target block, and predicted image data. The motion vector detection mode that encodes the motion vector, and only the difference value of the image data are encoded, the direct mode that predicts the motion vector from the peripheral blocks, and the difference value and motion vector of the image data are not encoded. There is a skip mode in which a predicted image at a position indicated by a motion vector predicted from a peripheral block or the like is a decoded image as it is.

Also, the motion vector detection mode for B pictures includes two-way prediction in which a prediction image is generated with reference to two already-encoded pictures ahead or behind the current picture as a prediction direction, and forward or backward. Unidirectional prediction for generating a prediction image with reference to one already-encoded picture can be selected.

On the other hand, in the B picture skip mode and direct mode, the prediction direction of the block to be encoded is determined according to the prediction mode of the neighboring blocks and the like. A specific example will be described with reference to FIG. In FIG. 31, the left adjacent encoded block of the encoding target block is adjacent block A, the upper adjacent encoded block of the encoding target block is adjacent block B, and the upper right adjacent encoded block of the encoding target block is shown. Is an adjacent block C. Further, the adjacent block A is bidirectional prediction, the adjacent block B is unidirectional prediction, and the adjacent block C is unidirectional prediction. The prediction direction in the skip mode of the encoding target block is bidirectional prediction if there is bidirectional prediction even in one of the adjacent blocks. In the case of FIG. 31, bidirectional prediction is used as the prediction direction of the encoding target block. Selected.

However, in the conventional method for determining the prediction direction of the skip mode and the direct mode, for example, bi-directional prediction is always selected even though the detection accuracy of the bi-directional prediction vector 2 in the adjacent block A in FIG. There is a problem that predicted images in the skip mode and the direct mode are deteriorated, leading to deterioration of encoding efficiency.

An object of the present invention is to solve the above-described problem. By using a new criterion for selecting a prediction direction of a skip mode and a direct mode, a skip mode most suitable for an encoding target picture and It aims at deriving the prediction direction of the direct mode and improving the coding efficiency.

In order to achieve the above object, in the video encoding method according to an aspect of the present invention, at least two or more reference pictures different from the encoding target picture including the encoding target block are included. An image encoding method for encoding the encoding target block by allocating a reference picture index, and when the two or more reference picture indexes are used when encoding the encoding target block, the 2 Based on the same reference picture determination step for determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same picture, and the determination result in the same reference picture determination step, the coding target block is set to a predetermined code. A prediction direction switching step of switching a prediction direction when encoding in the encoding mode.

In the moving picture decoding method according to an aspect of the present invention, at least two or more reference picture indexes are assigned to at least one or more reference pictures different from the decoding target picture including the decoding target block. An image decoding method for decoding the decoding target block, wherein the two or more reference picture indexes are used when the two or more reference picture indexes are used when decoding the decoding target block. And decoding the block to be decoded in a predetermined decoding mode based on the same reference picture determining step for determining whether or not the reference picture indicated by is the same picture and the determination result in the same reference picture determining step A prediction direction switching step for switching the prediction direction.

Thus, when determining the prediction direction of the skip mode, it is possible to select the optimal prediction direction for the block to be encoded, so that the encoding efficiency can be improved. In particular, when the reference picture indicated by reference picture index 1 in prediction direction 1 and the reference picture indicated by reference picture index 2 in prediction direction 2 are the same picture, unidirectional prediction is selected regardless of the prediction direction of adjacent blocks. By doing so, the quality of a prediction image can be improved and encoding efficiency can be improved.

According to the present invention, it is possible to derive the prediction direction of the skip mode most suitable for the encoding target picture by using a new criterion for selecting the prediction direction of the skip mode and the direct mode, Encoding efficiency can be improved.

FIG. 1 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using a moving picture coding method according to the present invention. FIG. 2 is a diagram illustrating an example of a reference list in a B picture. FIG. 3 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present invention. FIG. 4 is a diagram illustrating a determination flow of the skip mode prediction direction in the skip mode prediction direction determination unit. FIG. 5 is a diagram illustrating an inter prediction mode determination flow in the inter prediction control unit. FIG. 6 is a diagram showing a processing flow for the CostInter calculation method. FIG. 7 is a diagram illustrating a processing flow for the CostDirect calculation method. FIG. 8 is a diagram illustrating a method of calculating the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2. FIG. 9 is a diagram illustrating a processing flow for the CostSkip calculation method. FIG. 10A is a diagram illustrating an example of a predicted image generation process. FIG. 10B is a diagram illustrating another example of the predicted image generation process. FIG. 11 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the second embodiment. FIG. 12 is a diagram showing an outline of the processing flow of the moving picture coding method according to the second embodiment. FIG. 13 is a diagram illustrating a determination flow of the skip mode prediction direction addition flag. FIG. 14 is a diagram illustrating a processing flow of the CostSkip calculation method in the skip mode according to the second embodiment. FIG. 15 is a block diagram illustrating a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the third embodiment. FIG. 16 is a process flow diagram of the video encoding method according to Embodiment 3. FIG. 17 is a block diagram illustrating a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the fourth embodiment. FIG. 18 is a diagram illustrating an outline of a processing flow of the moving picture coding method according to the fourth embodiment. FIG. 19 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the fifth embodiment. FIG. 20 is a diagram showing an outline of a processing flow of the moving picture decoding method according to the fifth embodiment. FIG. 21 is a diagram illustrating an example of a bitstream syntax in the moving picture decoding method according to the fifth embodiment. FIG. 22 is a block diagram illustrating a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the sixth embodiment. FIG. 23 is a diagram showing an outline of a processing flow of the moving picture decoding method according to the sixth embodiment. FIG. 24 is a diagram illustrating an example of a bitstream syntax in the moving picture decoding method according to the sixth embodiment. FIG. 25 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the seventh embodiment. FIG. 26 is a diagram showing an outline of a processing flow of the moving picture decoding method according to the seventh embodiment. FIG. 27 is a diagram illustrating an example of a bitstream syntax in the moving picture decoding method according to the seventh embodiment. FIG. 28 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the eighth embodiment. FIG. 29 is a diagram showing an outline of a processing flow of the moving picture decoding method according to the eighth embodiment. FIG. 30 is a diagram illustrating an example of a bitstream syntax in the moving picture decoding method according to the eighth embodiment. FIG. 31 is a diagram illustrating a method of determining the prediction direction of the encoding target block. FIG. 32 is a block diagram illustrating a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the ninth embodiment. FIG. 33 is a diagram illustrating an example of a reference list in a B picture. FIG. 34 is a diagram showing an outline of the processing flow of the moving picture coding method according to the ninth embodiment. FIG. 35 is a diagram showing a flow for determining the direct mode prediction direction. FIG. 36 is a diagram illustrating a determination flow of the inter prediction mode. FIG. 37 is a diagram showing a processing flow for the CostInter calculation method. FIG. 38 is a diagram showing a processing flow for the CostDirect calculation method. FIG. 39 is a diagram illustrating a method of calculating the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2. FIG. 40 is a diagram illustrating a processing flow for the CostSkip calculation method. FIG. 41 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the tenth embodiment. FIG. 42 is a diagram showing an outline of the processing flow of the moving picture coding method according to the tenth embodiment. FIG. 43 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the eleventh embodiment. FIG. 44 is a diagram showing an outline of the processing flow of the video encoding method according to Embodiment 11. FIG. 45 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the twelfth embodiment. FIG. 46 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the twelfth embodiment. FIG. 47 is a diagram illustrating an example of bitstream syntax in the video decoding method according to Embodiment 12. FIG. 48 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the thirteenth embodiment. FIG. 49 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the thirteenth embodiment. FIG. 50 is a diagram illustrating an example of bitstream syntax in the video decoding method according to Embodiment 13. FIG. 51 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the fourteenth embodiment. FIG. 52 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the fourteenth embodiment. FIG. 53 is a diagram illustrating an example of the bitstream syntax in the video decoding method according to the fourteenth embodiment. FIG. 54 is an overall configuration diagram of a content supply system that implements a content distribution service. FIG. 55 is an overall configuration diagram of a digital broadcasting system. FIG. 56 is a block diagram illustrating a configuration example of a television. FIG. 57 is a block diagram illustrating a configuration example of an information reproducing / recording unit that reads and writes information from and on a recording medium that is an optical disk. FIG. 58 shows an example of the structure of a recording medium that is an optical disk. 59A is a diagram illustrating an example of a mobile phone, and FIG. 59B is a block diagram illustrating a configuration example of the mobile phone. FIG. 60 shows a structure of multiplexed data. FIG. 61 is a diagram schematically showing how each stream is multiplexed in the multiplexed data. FIG. 62 is a diagram showing in more detail how the video stream is stored in the PES packet sequence. FIG. 63 is a diagram showing the structure of TS packets and source packets in multiplexed data. FIG. 64 shows the data structure of the PMT. FIG. 65 shows the internal structure of the multiplexed data information. FIG. 66 shows the internal structure of stream attribute information. FIG. 67 is a diagram showing steps for identifying video data. FIG. 68 is a block diagram illustrating a configuration example of an integrated circuit that implements the moving picture coding method and the moving picture decoding method according to each embodiment. FIG. 69 is a diagram showing a configuration for switching drive frequencies. FIG. 70 is a diagram illustrating steps for identifying video data and switching between driving frequencies. FIG. 71 is a diagram showing an example of a lookup table in which video data standards are associated with drive frequencies. 72A is a diagram illustrating an example of a configuration for sharing a module of a signal processing unit, and FIG. 72B is a diagram illustrating another example of a configuration of sharing a module of a signal processing unit.

Hereinafter, embodiments of the invention will be described with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of the constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. The present invention is limited only by the claims. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are not necessarily required to achieve the object of the present invention. It will be described as constituting a preferred form.

In addition, the same code | symbol is attached | subjected to the same component and description may be abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using a moving picture coding method according to the present invention.

As illustrated in FIG. 1, the moving image encoding apparatus includes an orthogonal transform unit 101, a quantization unit 102, an inverse quantization unit 103, an inverse orthogonal transform unit 104, a block memory 105, a frame memory 106, an intra prediction unit 107, an inter prediction unit 107, and an inter prediction unit 107. A prediction unit 108, an inter prediction control unit 109, a picture type determination unit 110, a reference picture list management unit 111, a skip mode prediction direction determination unit 112, and a variable length coding unit 113 are provided.

The orthogonal transform unit 101 performs transformation from the image domain to the frequency domain on the prediction error data between the predicted image data generated by the means described later and the input image sequence. The quantization unit 102 performs a quantization process on the prediction error data converted into the frequency domain. The inverse quantization unit 103 performs inverse quantization processing on the prediction error data quantized by the quantization unit 102. The inverse orthogonal transform unit 104 performs transform from the frequency domain to the image domain on the prediction error data subjected to the inverse quantization process. The block memory 105 stores the decoded image obtained from the predicted image data and the prediction error data subjected to the inverse quantization process in units of blocks. The frame memory 106 stores the decoded image in units of frames. The picture type determination unit 110 determines which of the I picture, B picture, and P picture is to be used to encode the input image sequence, and generates picture type information. The intra prediction unit 107 uses the decoded image in units of blocks stored in the block memory 105 to generate predicted image data based on intra prediction of the encoding target block. The inter prediction unit 108 generates predicted image data by inter prediction of the encoding target block, using the decoded image in units of frames stored in the frame memory 106.

The reference picture list management unit 111 assigns a reference picture index to an encoded reference picture to be referred to in inter prediction, and creates a reference list together with a display order and the like. Since B pictures can be encoded with reference to two pictures, two reference lists are held. FIG. 2 shows an example of a reference list in a B picture. A reference picture list 1 in FIG. 2 is an example of a reference picture list in the prediction direction 1 in bi-directional prediction, and is displayed as a reference picture 1 in the display order 2 in the value 0 of the reference picture index 1 and a value 1 in the reference picture index 1. A reference picture 2 in display order 0 is assigned to a reference picture 2 in order 1 and a value 2 of reference picture index 1. That is, the reference picture index is assigned to the encoding target picture in the order of time in display order. On the other hand, the reference picture list 2 is an example of the reference picture list in the prediction direction 2 in the bi-directional prediction. The reference picture index 2 has a value 0 of the reference picture index 2 and the reference picture index 2 has the value 1 of the reference picture index 2. Reference picture 3 in display order 0 is assigned to value 2 of reference picture 1 and reference picture index 2 of 2. In this way, it is possible to assign different reference picture indexes for each reference picture for each prediction direction (

reference pictures

1 and 2 in FIG. 2), or to assign the same reference picture index (see FIG. 2). Picture 3).

In the present embodiment, the reference pictures are managed in the reference picture index and the display order. However, the reference pictures may be managed in the reference picture index and the encoding order.

The skip mode prediction direction determination unit 112 uses the reference picture lists 1 and 2 created by the reference picture list management unit 111 to determine the prediction direction of the skip mode of the encoding target block by a method to be described later.

The variable length encoding unit 113 generates a bitstream by performing variable length encoding processing on the quantized prediction error data, inter prediction mode, inter prediction direction, skip flag, and picture type information.

FIG. 3 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present invention. In S301, the prediction direction when the encoding target block is encoded in the skip mode is determined. In S302, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction determined in S301. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the direction is performed to determine a more efficient inter prediction mode. The cost calculation method will be described later. In S303, it is determined whether or not the inter prediction mode determined in S302 is the skip mode. If the determination result in S302 is true, a predicted image in skip mode is generated in S304, and the skip flag is set to 1 and attached to the bit stream of the encoding target block. If the determination result in S303 is false, inter prediction is performed according to the determined inter prediction mode, predictive image data is generated, the skip flag is set to 0, and the bitstream of the block to be encoded is attached. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode and an inter prediction direction are attached to the bit stream of the encoding target block.

FIG. 4 is a diagram illustrating a flow of determining the skip mode prediction direction in the skip mode prediction direction determination unit 112. In general, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, motion vectors in the prediction direction 1 and the prediction direction 2 are used in bidirectional prediction. Although selected, only the motion vector in the prediction direction 1 may be used in the unidirectional prediction, and the motion vector in the prediction direction 2 may decrease as a whole. In this case, if bi-directional prediction is selected as the prediction direction of the skip mode, there is a tendency that there are few motion vectors in the prediction direction 2 of the adjacent blocks that can be used for generation of the prediction motion vector in the prediction direction 2. There is a possibility that the accuracy of the predicted motion vector will be low. Therefore, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, by fixing the prediction direction in the skip mode to unidirectional prediction, Encoding efficiency can be improved. In the present embodiment, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, the prediction direction in the skip mode is fixed in one direction. However, when the reference picture index assignment method for the reference pictures in the reference picture list 1 and the reference picture list 2 is the same, the prediction direction in the skip mode may be fixed to unidirectional prediction. Even in such a case, the motion vector of the prediction direction 1 and the prediction direction 2 is selected in the bidirectional prediction, but only the motion vector of the prediction direction 1 may be used in the unidirectional prediction. Since the motion vector of 2 is reduced, encoding efficiency can be improved by fixing the prediction direction of the skip mode to unidirectional prediction.

In S401, the value of the reference picture index 1 in the prediction direction 1 in the skip mode is determined. For example, the reference picture index 1 with a value of 0 may always be used in the skip mode. In S402, the value of the reference picture index 2 in the prediction direction 2 in the skip mode is determined. For example, a reference picture index 2 of 0 may always be used in the skip mode. In S403, it is determined using the reference picture list 1 and the reference picture list 2 whether the reference picture indicated by the value of the reference picture index 1 and the reference picture indicated by the value of the reference picture index 2 are the same picture. For example, the display order of the reference picture indicated by the reference picture index 1 is obtained from the reference picture list 1 and is compared with the display order of the reference picture indicated by the reference picture index 2 from the reference picture list 2. Can be determined. If it is determined in S403 that the pictures to be referred to in the prediction direction 1 and the prediction direction 2 are the same picture, the prediction direction flag in the skip mode is set to unidirectional prediction in S404, and the prediction direction 1 and the prediction direction are determined in S403. If it is determined that the two reference pictures are not the same picture, the prediction mode flag in the skip mode is set to bidirectional prediction in S405.

In this embodiment, the value 0 is always used as the value of the reference picture index in the skip mode, but the minimum value of the reference picture index value of an adjacent block or the like may be used. In this embodiment, whether or not the pictures are the same is determined using the display order in S403, but may be determined using the encoding order or the like.

In S403, when the reference picture index is assigned to the reference pictures in the reference picture list 1 and the reference picture list 2 in the same way, they may be determined as the same picture. Such a configuration is effective, for example, when a picture corresponding to a predetermined index value is used as a reference picture. In the case where the picture corresponding to the index of 0 is used as the reference picture, when the index allocation method for the reference pictures in the reference picture list 1 and the reference picture list 2 is the same, the reference picture list 1 and the reference picture list The pictures corresponding to the index of 0 of 2 are the same.

FIG. 5 is a diagram showing an inter prediction mode determination flow in the inter prediction control unit 109.

In S501, a cost CostInter of a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result is calculated by a method described later. In S502, a prediction vector is generated using a motion vector such as an adjacent block, and a cost CostDirect in a direct mode for generating a prediction image using the prediction vector is calculated by a method described later. In S503, according to the determined skip mode prediction direction flag, the cost CostSkip of the skip mode for generating the predicted image is calculated by the method described later. In step S504, CostInter, CostDirect, and CostSkip are compared to determine whether CostInter is the minimum. If the determination result in S504 is true, in S505, the inter prediction mode is determined as the motion vector detection mode, and the inter prediction mode is set in the motion vector detection mode. If the determination result in S504 is false, CostDirect and CostSkip are compared in S506 to determine whether CostDirect is small. If the determination result in S506 is true, the inter prediction mode is determined to be the direct mode in S507, and the inter prediction mode information is set to the direct mode. If the determination result in S506 is false, the inter prediction mode is set to the skip mode in S508, and the skip mode is set to the inter prediction mode information.

Next, the CostInter calculation method of S501 in FIG. 5 will be described in detail using the processing flow of FIG. In S601, motion detection is performed on reference picture 1 indicated by reference picture index 1 in prediction direction 1 and reference picture 2 indicated by reference picture index 2 in prediction direction 2, and motion vector 1 and motion vector for each reference picture are detected. 2 is generated. Here, in motion detection, a difference value between a coding target block in a coded picture and a block in a reference picture is calculated, and a block in the reference picture having the smallest difference value is set as a reference block. Then, a motion vector is obtained from the encoding target block position and the reference block position. In S602, a prediction image in the prediction direction 1 is generated using the motion vector 1 obtained in S601, and the cost CostInterUni1 is calculated by, for example, the following equation of the RD optimization model.

In Equation 1, D represents encoding distortion, and a pixel value obtained by encoding and decoding a block to be encoded using a prediction image generated with a certain motion vector, and an original pixel value of the block to be encoded The sum of absolute differences is used. R represents the generated code amount, and the code amount necessary for encoding the motion vector used for predictive image generation is used. Λ is Lagrange's undetermined multiplier. In step S603, a predicted image in the prediction direction 2 is generated using the motion vector 2 obtained in step S601, and CostInterUni2 is calculated from Equation 1. In S604, a bidirectional prediction image is generated using the motion vector 1 and the motion vector 2 obtained in S601, and CostInterBi is calculated from Equation 1. Here, the bidirectional prediction image is, for example, a prediction image obtained from the motion vector 1 and a prediction image obtained from the motion vector 2 obtained by performing an arithmetic average for each pixel as the bidirectional prediction image. In step S605, the values of CostInterUni1, CostInterUni2, and CostInterBi are compared to determine whether CostInterBi is the minimum. If the determination result in S605 is true, in S606, the prediction direction of the motion vector detection mode is determined to be bidirectional prediction, and CostInterBi is set to CostInter. If the determination result in S605 is false, CostInterUni1 and CostInterUni2 are compared in S607 to determine whether the value of CostInterUni1 is small. If the determination result in S607 is true, in S608, the motion vector detection mode is determined as one-way prediction 1 in the prediction direction 1, and CostInterUni1 is set to CostInter. If the determination result in S607 is false, in S609, the motion vector detection mode is determined as unidirectional prediction 2 in the prediction direction 2, and CostInterUni2 is set to CostInter.

In the present embodiment, the addition average for each pixel is performed at the time of bidirectional prediction image generation, but a weighted addition average or the like may be performed.

Next, the CostDirect calculation method of S502 in FIG. 5 will be described in detail using the processing flow of FIG. In S701, the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2 are calculated. Here, the direct vector is calculated using, for example, a motion vector of an adjacent block. An example of this will be described with reference to FIG. In FIG. 8, a motion vector MV_A is a motion vector of an adjacent block A located on the left side of the encoding target block, and a motion vector MV_B is a motion vector and a motion vector of an adjacent block B located on the upper side of the encoding target block. MV_C is a motion vector of the adjacent block C located on the upper right side of the encoding target block. The direct vector is calculated from, for example, an intermediate value Median (MV_A, MV_B, MV_C) of MV_A, MV_B, and MV_C that are motion vectors of adjacent blocks. Here, the intermediate value is derived as follows.

The direct vector 1 in the prediction direction 1 is calculated from Equation 2 using the motion vector in the prediction direction 1 of the adjacent block. Further, the direct vector 2 in the prediction direction 2 is calculated from Equation 2 using the motion vector in the prediction direction 2 of the adjacent block. If there is no adjacent block having the same prediction direction as the encoding target block, a motion vector having a value of 0 may be used as the direct vector.

In S702, a bidirectional prediction image is generated using the direct vector 1 and the direct vector 2 obtained in S701, and CostDirectBi is calculated from Equation 1. Here, the bidirectional prediction image is, for example, a prediction image obtained from the direct vector 1 and a prediction image obtained from the direct vector 2 obtained by performing an addition average for each pixel as the bidirectional prediction image. In S703, a predicted image in the prediction direction 1 is generated using the direct vector 1, and its cost CostDirectUni1 is calculated from Equation 1. In S704, a predicted image in the prediction direction 2 is generated using the direct vector 2 obtained in S701, and CostDirectUni2 is calculated from Equation 1. In S705, the values of CostDirectUni1, CostDirectUni2, and CostDirectBi are compared to determine whether CostDirectBi is minimum. If the determination result in S705 is true, in S706, the direct mode prediction direction is determined to be bidirectional prediction, and CostDirctBi is set to CostDirect. If the determination result in S705 is false, CostDirectUni1 and CostDirectUni2 are compared in S707 to determine whether the value of CostDirectUni1 is small. If the determination result in S707 is true, in S708, the direct mode is determined as one-way prediction 1 in the prediction direction 1, and CostDirectUni1 is set to CostDirect. If the determination result in S707 is false, in S709, the direct mode is determined as one-way prediction 2 in the prediction direction 2, and CostDirectUni2 is set to CostDirect.

Next, the CostSkip calculation method of S503 in FIG. 5 will be described in detail using the processing flow of FIG. In S901, it is determined whether or not the skip mode prediction direction flag determined by the skip mode prediction direction determination unit 112 is unidirectional prediction. If the determination result in S901 is true, a predicted image in the prediction direction 1 is generated using the direct vector 1 in S902, and its cost CostSkip is calculated from Equation 1. If the determination result in S901 is false, a bidirectional prediction image is generated using the direct vector 1 and the direct vector 2 in S903, and CostSkip is calculated from Equation 1. Here, the bidirectional prediction image is, for example, a prediction image obtained from the direct vector 1 and a prediction image obtained from the direct vector 2 obtained by performing an addition average for each pixel as the bidirectional prediction image. FIG. 10A and FIG. 10B are diagrams showing specific examples when the predicted image is generated. FIG. 10A is an example when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture. In this case, the processing flow of FIG. Thus, the skip mode prediction direction flag is unidirectional prediction, and the prediction image generated by the direct vector 1 in the prediction direction 1 is used for encoding. On the other hand, FIG. 10B is an example in which the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are different pictures. In this case, FIG. From the processing flow, the skip mode prediction direction flag becomes bidirectional prediction, and a bidirectional prediction image generated using the direct vector 1 and the direct vector 2 is used for encoding.

In the present embodiment, when the skip mode prediction direction flag is unidirectional prediction, the prediction image is generated using the direct vector 1, but it may be generated using the direct vector 2.

Thus, according to the present invention, when determining the prediction direction of the skip mode, it is possible to select the optimal prediction direction for the block to be encoded, so that the encoding efficiency can be improved. In particular, when the reference picture indicated by reference picture index 1 in prediction direction 1 and the reference picture indicated by reference picture index 2 in prediction direction 2 are the same picture, unidirectional prediction is selected regardless of the prediction direction of adjacent blocks. By doing so, the quality of a prediction image can be improved and encoding efficiency can be improved.

(Embodiment 2)
FIG. 11 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the present invention. In the present embodiment, instead of the skip mode prediction direction determination unit 112 of the first embodiment, a skip mode prediction direction addition determination unit 112a is newly provided, and when the skip mode prediction direction addition flag is on, the skip mode Even in this case, the configuration differs from the other embodiments in that the inter prediction direction is attached to each encoding target block.

FIG. 12 is an outline of the processing flow of the moving picture coding method according to the present embodiment. In step S1201, it is determined whether or not to add a prediction direction when the encoding target block is encoded in the skip mode, and when it is added, the skip mode addition flag is turned on. In S1202, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction direction added in S1201. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the above is performed to determine a more efficient inter prediction mode. Here, Formula 1 etc. are utilized for the cost calculation method. In S1203, it is determined whether or not the inter prediction mode determined in S1202 is the skip mode. If the determination result in S1203 is true, it is determined in S1204 whether the skip mode addition flag is on. If the determination result in S1204 is true, a predicted image in skip mode is generated in S1205, and the skip flag is set to 1. Is attached to the bit stream of the encoding target block. Also, the inter prediction direction in the skip mode is attached to the bitstream. If the determination result in S1204 is false, skip mode prediction image generation is performed, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S1203 is false, inter prediction is performed according to the determined inter prediction mode, predictive image data is generated, the skip flag is set to 0, and the bitstream of the encoding target block is attached. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode and an inter prediction direction are attached to the bit stream of the encoding target block.

FIG. 13 is a diagram illustrating a determination flow of the skip mode prediction direction addition flag in the skip mode prediction direction addition determination unit 112a.

In S1301, the value of the reference picture index 1 in the prediction direction 1 in the skip mode is determined. For example, the reference picture index 1 with a value of 0 may always be used in the skip mode. In S1302, the value of the reference picture index 2 in the prediction direction 2 in the skip mode is determined. For example, a reference picture index 2 of 0 may always be used in the skip mode. In S1303, it is determined using reference picture lists 1 and 2 whether the reference picture indicated by the value of reference picture index 1 and the reference picture indicated by the value of reference picture index 2 are the same picture. For example, the display order of the reference picture indicated by the reference picture index 1 is obtained from the reference picture list 1 and is compared with the display order of the reference picture indicated by the reference picture index 2 from the reference picture list 2. it can. If it is determined in S1303 that the pictures referred to in the prediction direction 1 and the prediction direction 2 are the same picture, the prediction direction addition flag in the skip mode is set to ON in S1304. If it is determined in S1303 that the reference pictures in

prediction directions

1 and 2 are not the same picture, the prediction direction addition flag in the skip mode is set to OFF in S1305.

In this embodiment, the value 0 is always used as the value of the reference picture index in the skip mode, but the minimum value of the reference picture index value of an adjacent block or the like may be used. In the present embodiment, it is determined whether or not the pictures are the same using the display order in S1303, but may be determined using the encoding order or the like.

Next, a method of calculating the SkipSkip in the skip mode according to the present embodiment will be described in detail using the processing flow of FIG. Note that the determination flow of the inter prediction mode and the calculation method of CostInter and CostDirect are the same as those in FIGS. 5, 6, and 7 of the first embodiment, and thus description thereof is omitted.

In S1401, the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2 are calculated by the method described in the first embodiment. Then, a bidirectional prediction image is generated using the obtained direct vector 1 and direct vector 2, and CostSkipBi is calculated from Equation 1. Here, the bidirectional prediction image is, for example, a prediction image obtained from the direct vector 1 and a prediction image obtained from the direct vector 2 obtained by performing an addition average for each pixel as the bidirectional prediction image. In S1402, it is determined whether the skip mode prediction direction addition flag is on. If the determination result in S1402 is true, a predicted image in the prediction direction 1 is generated using the direct vector 1 in S1403, and its cost CostSkipUni1 is calculated from Equation 1. In S1404, a predicted image in the prediction direction 2 is generated using the direct vector 2 obtained in S1401, and CostSkipUni2 is calculated from Equation 1. In S1405, the values of CostSkipUni1, CostSkipUni2, and CostSkipBi are compared to determine whether CostSkipUni1 is minimum. If the determination result in S1405 is true, in S1406, the skip mode is determined as one-way prediction 1 in the prediction direction 1, and CostSkipUni1 is set to CostSkip. If the determination result in S1405 is false, CostSkipUni2 and CostSkipBi are compared in S1407 to determine whether the value of CostSkipUni2 is small. If the determination in S1407 is true, in S1408, the skip mode is determined as one-way prediction 2 in the prediction direction 2, and CostSkipUni2 is set to CostSkip. If both the determination result in S1402 and the determination result in S1407 are false, in S1409, the skip mode is determined to be bidirectional prediction, and CostSkipBi is set to CostSkip.

Thus, according to the present invention, when determining the prediction direction of the skip mode, it is possible to select the optimal prediction direction for the block to be encoded, so that the encoding efficiency can be improved. In particular, when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, the prediction direction is set even in the skip mode regardless of the prediction direction of the adjacent block. By being attached to the bitstream, by selecting the optimal prediction direction for the block to be encoded, the quality of the predicted image can be improved and the encoding efficiency can be improved.

(Embodiment 3)
FIG. 15 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the present embodiment. In the present embodiment, header information (for example, an H.264 picture parameter set or slice) that gives the skip mode prediction direction flag generated by the skip mode prediction direction determination unit 112 to the bit stream for each processing unit such as a picture. The configuration differs from the other embodiments in that it is attached to a header or the like.

FIG. 16 is an outline of a processing flow of the moving picture coding method according to the present embodiment. In S1601, the prediction direction when the encoding target block is encoded in the skip mode is determined, and the determined skip mode prediction direction flag is attached to the picture header or the like. Here, the flow of FIG. 4 of Embodiment 1 etc. can be utilized for the determination method of the prediction direction of skip mode. In S1602, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction determined in S1601. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the direction is performed to determine a more efficient inter prediction mode. Here, Formula 1 etc. are utilized for the cost calculation method. In S1603, it is determined whether the inter prediction mode determined in S1602 is a skip mode. If the determination result in S1603 is true, in S1604, a predicted image in the skip mode is generated, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S1603 is false, inter prediction is performed according to the determined inter prediction mode, prediction image data is generated, the skip flag is set to 0, and the bit stream of the block to be encoded is attached. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode and an inter prediction direction are attached to the bit stream of the encoding target block. In addition, since the inter prediction mode determination method etc. are the same as that of Embodiment 1, description is abbreviate | omitted.

Thus, according to the present invention, since the skip mode prediction direction flag is explicitly added to the picture header or the like, the prediction mode of the skip mode can be flexibly switched for each picture, and the coding efficiency It becomes possible to improve.

(Embodiment 4)
FIG. 17 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the present embodiment. In the present embodiment, header information (for example, a picture parameter set of H.264) that adds the skip mode prediction direction addition flag generated by the skip mode prediction direction addition determination unit 112a to the bit stream for each processing unit such as a picture. In other respects, the configuration differs from the other embodiments.

FIG. 18 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present embodiment. In step S1801, it is determined whether or not to add a prediction direction when the encoding target block is encoded in the skip mode, and when it is added, the skip mode addition flag is turned on. Then, the determined skip mode prediction direction addition flag is attached to the picture header or the like. Here, as a method of determining the prediction direction addition, FIG. 13 of the second embodiment can be used. In S1802, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction direction added in S1801. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the above is performed to determine a more efficient inter prediction mode. Here, Formula 1 etc. are utilized for the cost calculation method. In S1803, it is determined whether or not the inter prediction mode determined in S1802 is the skip mode. If the determination result in S1803 is true, it is determined in S1804 whether the skip mode addition flag is on. If the determination result in S1804 is true, a predicted image in the skip mode is generated in S1805, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. Also, the inter prediction direction in the skip mode is attached to the bitstream. If the determination result in S1804 is false, predicted image generation in the skip mode is performed, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S1803 is false, inter prediction is performed according to the determined inter prediction mode, predictive image data is generated, the skip flag is set to 0, and the bitstream of the encoding target block is attached. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode and an inter prediction direction are attached to the bit stream of the encoding target block. In addition, since the inter prediction mode determination method etc. are the same as that of Embodiment 2, description is abbreviate | omitted.

As described above, according to the present invention, since the skip mode prediction direction addition flag is explicitly added to the picture header or the like, whether to add the prediction mode of the skip mode can be flexibly switched for each picture. Thus, the encoding efficiency can be improved.

(Embodiment 5)
FIG. 19 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment.

As illustrated in FIG. 19, the moving picture decoding apparatus includes a variable length decoding unit 1901, an inverse quantization unit 1902, an inverse orthogonal transform unit 1903, a block memory 1904, a frame memory 1905, an intra prediction unit 1906, and an inter prediction unit 1907. An inter prediction control unit 1908, a reference picture list management unit 1909, and a skip mode prediction direction determination unit 1910.

The variable length decoding unit 1901 performs variable length decoding processing on the input bitstream, and performs the picture type information, the inter prediction mode, the inter prediction direction, the skip flag, and the quantized coefficient that has been subjected to the variable length decoding processing. Is generated. The inverse quantization unit 1902 performs an inverse quantization process on the quantized coefficient that has been subjected to the variable length decoding process. The inverse orthogonal transform unit 1903 transforms the orthogonal transform coefficient that has been subjected to the inverse quantization process from the frequency domain to the image domain to obtain prediction error image data. The block memory 1904 stores prediction error image data and an image sequence generated by adding the prediction image data in units of blocks. The frame memory 1905 stores the image sequence in units of frames. The intra prediction unit 1906 generates predicted image data of the decoding target block by performing intra prediction using the block-by-block image sequence stored in the block memory 1904. The inter prediction unit 1907 generates predicted image data of the decoding target block by performing inter prediction using the frame-by-frame image sequence stored in the frame memory 1905. The inter prediction control unit 1908 controls the motion vector and the prediction image data generation method in the inter prediction according to the inter prediction mode, the inter prediction direction, and the skip flag.

The reference picture list management unit 1909 assigns a reference picture index to an encoded reference picture to be referred to in inter prediction, and creates a reference list along with the display order (similar to FIG. 2 in the first embodiment). Since B pictures can be encoded with reference to two pictures, two reference lists are held.

In this embodiment, the reference picture is managed in the reference picture index and the display order. However, the reference picture may be managed in the reference picture index and the encoding order.

The skip mode prediction direction determination unit 1910 uses the reference picture lists 1 and 2 created by the reference picture list management unit 1909 to determine the prediction mode of the skip mode of the encoding target block. Note that the flow for determining the skip mode prediction direction flag is the same as that in FIG.

Finally, a decoded image sequence is generated by adding the decoded prediction error image data and the prediction image data.

FIG. 20 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the present embodiment. In S2001, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S2001 is true, it is determined in S2002 whether the skip mode prediction direction flag is unidirectional prediction. If the determination result in S2002 is true, direct vector 1 is calculated in S2003, and a one-way predicted image is generated. If the determination result in S2002 is false, in S2004, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S2001 is false, that is, if it is not the skip mode, it is determined in S2005 whether the decoded inter prediction mode is the motion vector detection mode. If the determination result in S2005 is true, a predicted image is generated in S2006 using the decoded inter prediction direction and motion vector. If the determination result in S2005 is false, that is, the direct mode, in S2007, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction, and a predicted image is generated.

In the present embodiment, the one-way predicted image in the skip mode is generated using the direct vector 1 in S2003 of FIG. 20, but the one-way prediction is performed using the direct vector 2 together with the moving picture coding method. A predicted image may be generated.

FIG. 21 is a diagram illustrating an example of a bitstream syntax in the video decoding method according to the present embodiment. In FIG. 21, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction.

As described above, according to the present invention, when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, the prediction direction of the adjacent block is affected. Instead, it is possible to appropriately decode a bitstream with improved encoding efficiency by selecting unidirectional prediction.

(Embodiment 6)
FIG. 22 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment. In the present embodiment, instead of the skip mode prediction direction determination unit 1910 of the fifth embodiment, a skip mode prediction direction addition determination unit 1910a is newly provided, and when the skip mode prediction direction addition flag is on, the skip mode Even in this case, the configuration is different from the other embodiments in that a bitstream in which the inter prediction direction is associated with each encoding target block can be decoded. Note that the skip mode prediction direction addition determination flow is the same as that of FIG.

FIG. 23 is a diagram showing an outline of the processing flow of the video decoding method according to the present embodiment. In S2301, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S2301 is true, it is determined in S2302 whether the skip mode prediction direction addition flag is on. If the determination result in S2302 is true, in S2303, the inter prediction direction is decoded, and at least one of the direct vector 1 and the direct vector 2 is calculated according to the decoded inter prediction direction, and one-way or bidirectional prediction is performed. Generate an image. If the determination result in S2302 is false, the direct vector 1 and the direct vector 2 are calculated to generate a bidirectional prediction image. If the determination result in S2301 is false, that is, if it is not the skip mode, it is determined in S2305 whether the decoded inter prediction mode is the motion vector detection mode. If the determination result in S2305 is true, a predicted image is generated in S2306 using the decoded inter prediction direction and motion vector. If the determination result in S2305 is false, that is, if it is the direct mode, in S2307, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction, and a predicted image is generated.

FIG. 24 is a diagram showing an example of the bitstream syntax in the video decoding method according to the present embodiment. In FIG. 24, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction.

As described above, according to the present invention, when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, the prediction direction of the adjacent block is affected. In addition, by attaching the prediction direction to the bitstream even in the skip mode, it is possible to appropriately decode the bitstream with improved encoding efficiency.

(Embodiment 7)
FIG. 25 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment. In the present embodiment, header information (for example, H.264 picture parameter set or slice) that gives the skip mode prediction direction flag generated by the skip mode prediction direction determination unit 1910 to the bit stream for each processing unit such as a picture. The configuration differs from the other embodiments in that the bit stream attached to the header or the like can be decoded.

FIG. 26 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the present embodiment. In S2601, it is determined whether or not the skip flag decoded from the bit stream is 1. If the determination result in S2601 is true, it is determined in S2602 whether or not the skip mode prediction direction flag decoded from the bitstream is unidirectional prediction. If S2602 is true, in S2603, the direct vector 1 is calculated and a one-way predicted image is generated. If the determination result in S2602 is false, in S2604, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S2601 is false, that is, if it is not the skip mode, it is determined in S2605 whether the decoded inter prediction mode is the motion vector detection mode. If the determination result in S2605 is true, a predicted image is generated in S2606 using the decoded inter prediction direction and motion vector. If the determination result in S2605 is false, that is, if it is the direct mode, in S2607, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction, and a predicted image is generated.

In this embodiment, the one-way predicted image in the skip mode is generated using the direct vector 1 in S2603 of FIG. 26. However, the one-way image using the direct vector 2 is combined with the moving image coding method. A predicted image may be generated.

FIG. 27 is a diagram illustrating an example of a bitstream syntax in the video decoding method according to the present embodiment. In FIG. 27, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction. Also, skip_pred_idc added to the picture header or the like represents the skip flag prediction direction.

As described above, according to the present invention, coding efficiency is improved by flexibly switching the prediction direction of the skip mode for each picture by explicitly assigning the skip mode prediction direction flag to the picture header or the like. It becomes possible to properly decode the bitstream.

(Embodiment 8)
FIG. 28 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment. In the present embodiment, header information (for example, a picture parameter set of H.264) that adds a skip mode prediction direction addition flag generated by the skip mode prediction direction addition determination unit 1910a to a bit stream for each processing unit such as a picture. The configuration differs from the other embodiments in that the bit stream can be decoded by being attached to the header.

FIG. 29 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the present embodiment. In S2901, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S2901 is true, it is determined in S2902 whether or not the skip mode prediction direction addition flag decoded from the bitstream is on. If the determination result in S2902 is true, in S2903, the inter prediction direction is decoded, and at least one of the direct vector 1 and the direct vector 2 is calculated according to the decoded inter prediction direction, and one-way or bidirectional prediction is performed. Generate an image. If the determination result in S2902 is false, a direct vector 1 and a direct vector 2 are calculated to generate a bidirectional prediction image. If the determination result in S2901 is false, that is, if it is not the skip mode, it is determined in S2905 whether the decoded inter prediction mode is the motion vector detection mode. If the determination result in S2905 is true, a predicted image is generated in S2906 using the decoded inter prediction direction and motion vector. If the determination result in S2905 is false, that is, if it is the direct mode, in S2907, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction, and a prediction image is generated.

FIG. 30 is a diagram illustrating an example of a bitstream syntax in the video decoding method according to the present embodiment. In FIG. 30, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction. Further, skip_add_dir added to the picture header or the like represents a skip flag prediction direction addition flag.

As described above, according to the present invention, by explicitly assigning the skip mode prediction direction addition flag to the picture header or the like, it is possible to flexibly switch whether to add the prediction mode of the skip mode for each picture. It is possible to appropriately decode a bit stream with improved efficiency.

(Embodiment 9)
FIG. 32 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the present embodiment.

As shown in FIG. 32, the moving image encoding apparatus includes an orthogonal transform unit 3201, a quantization unit 3202, an inverse quantization unit 3203, an inverse orthogonal transform unit 3204, a block memory 3205, a frame memory 3206, an intra prediction unit 3207, an inter prediction unit A prediction unit 3208, an inter prediction control unit 3209, a picture type determination unit 3210, a reference picture list management unit 3211, a direct mode prediction direction determination unit 3212, and a variable length encoding unit 3213 are provided.

The orthogonal transform unit 3201 performs transformation from the image domain to the frequency domain on the prediction error data between the predicted image data generated by the means described later and the input image sequence. The quantization unit 3202 performs a quantization process on the prediction error data converted into the frequency domain. The inverse quantization unit 3203 performs inverse quantization processing on the prediction error data quantized by the quantization unit 3202. The inverse orthogonal transform unit 3204 performs transform from the frequency domain to the image domain on the prediction error data subjected to the inverse quantization process. The block memory 3205 stores the decoded image obtained from the prediction image data and the prediction error data subjected to the inverse quantization process in units of blocks. The frame memory 3206 stores the decoded image in units of frames. The picture type determination unit 3210 determines which of the I picture, B picture, or P picture is used to encode the input image sequence, and generates picture type information. The intra prediction unit 3207 uses the decoded image in units of blocks stored in the block memory 3205 to generate predicted image data based on intra prediction of the encoding target block. The inter prediction unit 3208 uses the decoded image in units of frames stored in the frame memory 3206 to generate predicted image data based on inter prediction of the current block.

The reference picture list management unit 3211 assigns a reference picture index to an encoded reference picture that is referred to in inter prediction, and creates a reference list together with a display order and the like. Since B pictures can be encoded with reference to two pictures, two reference lists are held. FIG. 33 shows an example of a reference list in a B picture. A reference picture list 1 in FIG. 33 is an example of a reference picture list in the prediction direction 1 in bi-directional prediction, and is displayed as a reference picture 1 with a reference picture index 1 value 0 and a reference picture index 1 with a reference picture index 1 value 1. A reference picture 2 in display order 0 is assigned to a reference picture 2 in order 1 and a value 2 of reference picture index 1. That is, the reference picture index is assigned to the encoding target picture in the order of time in display order. On the other hand, the reference picture list 2 is an example of the reference picture list in the prediction direction 2 in the bi-directional prediction. The reference picture index 2 has a value 0 of the reference picture index 2 and the reference picture index 2 has the value 1 of the reference picture index 2. Reference picture 3 in display order 0 is assigned to value 2 of reference picture 1 and reference picture index 2 of 2. In this way, it is possible to assign different reference picture indexes for each reference picture for each prediction direction (

reference pictures

1 and 2 in FIG. 33), or to assign the same reference picture index (see FIG. 33). Picture 3).

The direct mode prediction direction determination unit 3212 uses the reference picture list 1 and the reference picture list 2 created by the reference picture list management unit 3211 to determine the direct mode prediction direction of the block to be encoded by a method described later. .

The variable length coding unit 3213 generates a bitstream by performing variable length coding processing on the quantized prediction error data, inter prediction mode, inter prediction direction flag, skip flag, and picture type information. .

FIG. 34 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present embodiment. In S3401, the prediction direction when the encoding target block is encoded in the direct mode is determined. In S3402, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction determined in S3401. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the direction is performed, and a more efficient inter prediction mode is determined. The cost calculation method will be described later. In S3403, it is determined whether the inter prediction mode determined in S3402 is the skip mode. If the determination result in S3402 is true, in S3404, a predicted image in the skip mode is generated, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S3403 is false, it is determined in S3405 whether or not the determined inter prediction mode is the direct mode and the direct prediction direction fixed flag determined by the method described later is on. If the determination result in S3405 is true, in S3406, a bi-directional prediction image in the direct mode is generated, the skip flag is set to 0, and it is attached to the bit stream of the encoding target block. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode is attached to the bit stream of the encoding target block. If the determination result in S3405 is false, inter prediction is performed according to the determined inter prediction mode, predictive image data is generated, the skip flag is set to 0, and the bitstream of the encoding target block is attached. In addition, the inter prediction mode indicating the motion vector detection mode or the direct mode, and the unidirectional prediction in which the inter prediction direction is the prediction direction 1, the unidirectional prediction in the prediction direction 2, or the prediction direction 1 and the prediction direction 2 are set. An inter prediction direction flag indicating whether or not the bidirectional prediction is used is attached to the bit stream of the block to be encoded.

FIG. 35 is a diagram showing a direct mode prediction direction determination flow in the direct mode prediction direction determination unit 3212. In general, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, the costs of bidirectional prediction and unidirectional prediction tend to be relatively close. Therefore, by fixing to one of the prediction directions, it is not necessary to attach an inter prediction direction flag for each encoding target block. In the present embodiment, description will be given below using an example in which the prediction is fixed to bidirectional prediction that can generate a prediction image with relatively little noise due to the influence of addition averaging or the like. In the case of an image with little influence of noise or the like, it may be fixed to unidirectional prediction from the viewpoint of processing amount.

In S3501, the value of the reference picture index 1 in the prediction direction 1 in the direct mode is determined. For example, in the direct mode, the reference picture index 1 having a value of 0 may always be used. In S3502, the value of the reference picture index 2 in the prediction direction 2 in the direct mode is determined. For example, the reference picture index 2 having a value of 0 may always be used in the direct mode. In S3503, it is determined using the reference picture list 1 and the reference picture list 2 whether the reference picture indicated by the value of the reference picture index 1 and the reference picture indicated by the value of the reference picture index 2 are the same picture. For example, the display order of the reference picture indicated by the reference picture index 1 is obtained from the reference picture list 1 and is compared with the display order of the reference picture indicated by the reference picture index 2 from the reference picture list 2. it can. If it is determined in S3503 that the pictures to be referenced in the prediction direction 1 and the prediction direction 2 are the same picture, in S3504, the direct mode prediction direction is determined to be bidirectional prediction, and the direct mode prediction direction fixed flag is turned on. Set to. If it is determined in S3503 that the reference pictures in the prediction direction 1 and the prediction direction 2 are not the same picture, the direct mode prediction direction fixed flag is set to OFF in S3505.

In this embodiment, the value 0 is always used as the value of the reference picture index in the direct mode, but the minimum value of the reference picture index value of an adjacent block or the like may be used. In this embodiment, whether or not the pictures are the same is determined using the display order in S3503, but may be determined using the encoding order or the like.

In S3503, when the reference picture index is assigned to the reference pictures in the reference picture list 1 and the reference picture list 2 in the same way, they may be determined as the same picture. Such a configuration is effective, for example, when a picture corresponding to a predetermined index value is used as a reference picture. In the case where the picture corresponding to the index of 0 is used as the reference picture, when the index allocation method for the reference pictures in the reference picture list 1 and the reference picture list 2 is the same, the reference picture list 1 and the reference picture list The pictures corresponding to the index of 0 of 2 are the same.

FIG. 36 is a diagram showing an inter prediction mode determination flow in the inter prediction control unit 3209.

In S3601, a cost CostInter of a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result is calculated by a method described later. In S3602, a cost CostDirect in a direct mode for generating a prediction vector using a motion vector such as an adjacent block and generating a prediction image using the prediction vector is calculated by a method described later. In S3603, according to the determined skip mode prediction direction flag, the cost CostSkip of the skip mode for generating the predicted image is calculated by the method described later. In S3604, CostInter, CostDirect, and CostSkip are compared to determine whether CostInter is the minimum. If the determination result in S3604 is true, the inter prediction mode is determined to be the motion vector detection mode in S3605, and the inter prediction mode is set to the motion vector detection mode. If the determination result in S3604 is false, a comparison between CostDirect and CostSkip is performed in S3606 to determine whether CostDirect is small. If the determination result in S3606 is true, the inter prediction mode is determined to be the direct mode in S3607, and the inter prediction mode is set to the direct mode. If the determination in S3606 is false, the inter prediction mode is set to the skip mode in S3608, and the skip mode is set to the inter prediction mode.

Next, the CostInter calculation method in S3601 in FIG. 36 will be described in detail using the processing flow in FIG. S3701 performs motion detection on reference picture 1 indicated by reference picture index 1 in prediction direction 1 and reference picture 2 indicated by reference picture index 2 in prediction direction 2, and motion vector 1 and motion vector for each reference picture are detected. 2 is generated. Here, in motion detection, a difference value between a coding target block in a coded picture and a block in a reference picture is calculated, and a block in the reference picture having the smallest difference value is set as a reference block. Then, a motion vector is obtained from the encoding target block position and the reference block position. In S3702, a prediction image in the prediction direction 1 is generated using the motion vector 1 obtained in S3701, and the cost CostInterUni1 is calculated by, for example, the following equation of the RD optimization model.

In Expression 5, D represents encoding distortion, and a pixel value obtained by encoding and decoding a block to be encoded using a prediction image generated with a certain motion vector, and an original pixel value of the block to be encoded The sum of absolute differences is used. R represents the generated code amount, and the code amount necessary for encoding the motion vector used for predictive image generation is used. Λ is Lagrange's undetermined multiplier. In S3703, a prediction image in the prediction direction 2 is generated using the motion vector 2 obtained in S3701, and CostInterUni2 is calculated from Equation 5. In S3704, a bidirectional prediction image is generated using the motion vector 1 and the motion vector 2 obtained in S3701, and CostInterBi is calculated from Equation 5. Here, the bidirectional prediction image is, for example, a prediction image obtained from the motion vector 1 and a prediction image obtained from the motion vector 2 obtained by performing an arithmetic average for each pixel as the bidirectional prediction image. In S3705, the values of CostInterUni1, CostInterUni2, and CostInterBi are compared to determine whether CostInterBi is minimum. If the determination result in S3705 is true, in S3706, the prediction direction of the motion vector detection mode is determined to be bidirectional prediction, and CostInterBi is set to CostInter. If the determination result in S3705 is false, CostInterUni1 and CostInterUni2 are compared in S3707 to determine whether the value of CostInterUni1 is small. If the determination result in S3707 is true, in S3708, the motion vector detection mode is determined to be one-way prediction 1 in the prediction direction 1, and CostInterUni1 is set to CostInter. If the determination result in S3707 is false, in S3709, the motion vector detection mode is determined as unidirectional prediction 2 in the prediction direction 2, and CostInterUni2 is set to CostInter.

Next, the CostDirect calculation method of S3602 in FIG. 36 will be described in detail using the processing flow of FIG. In S3801, the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2 are calculated. Here, the direct vector is calculated using, for example, a motion vector of an adjacent block. An example will be described with reference to FIG. In FIG. 39, a motion vector MV_A is a motion vector of an adjacent block A located on the left side of the encoding target block, and a motion vector MV_B is a motion vector and a motion vector of an adjacent block B located above the encoding target block. MV_C is a motion vector of the adjacent block C located on the upper right side of the encoding target block. The direct vector is calculated from, for example, an intermediate value Median (MV_A, MV_B, MV_C) of MV_A, MV_B, and MV_C that are motion vectors of adjacent blocks. Here, the intermediate value is derived as follows.

The direct vector 1 in the prediction direction 1 is calculated from Equation 6 using the motion vector in the prediction direction 1 of the adjacent block. Further, the direct vector 2 in the prediction direction 2 is calculated from Equation 2 using the motion vector in the prediction direction 2 of the adjacent block. If there is no adjacent block having the same prediction direction as the encoding target block, a motion vector having a value of 0 may be used as the direct vector.

In S3802, a bidirectional prediction image is generated using the direct vector 1 and the direct vector 2 obtained in S3801, and CostDirectBi is calculated from Equation 5. Here, the bidirectional prediction image is, for example, a bidirectional prediction image obtained by averaging the prediction image obtained from the direct vector 1 and the prediction image obtained from the direct vector 2 for each pixel. In S3803, it is determined whether the direct mode prediction direction flag is off. If the determination result in S3803 is true, a predicted image in the prediction direction 1 is generated using the direct vector 1 in S3804, and the cost CostDirectUni1 is calculated from Equation 1. In S3805, a predicted image in the prediction direction 2 is generated using the direct vector 2 obtained in S3801, and CostDirectUni2 is calculated from Equation 5. In S3806, the values of CostDirectUni1, CostDirectUni2, and CostDirectBi are compared to determine whether CostDirectBi is minimum. If the determination result in S3806 is true, in S3807, the direct mode prediction direction is determined to be bidirectional prediction, and CostDirctBi is set to CostDirect. If S3806 is false, CostDirectUni1 and CostDirectUni2 are compared in S3808 to determine whether the value of CostDirectUni1 is small. If the determination result in S3808 is true, in S3809, the direct mode is determined as one-way prediction 1 in the prediction direction 1, and CostDirectUni1 is set to CostDirect. If the determination result in S3808 is false, in S3810, the direct mode is determined as one-way prediction 2 in the prediction direction 2, and CostDirectUni2 is set to CostDirect. If the direct prediction direction fixed flag is ON in S3803, in S3807, the direct mode prediction direction is determined to be bidirectional prediction, and CostDirctBi is set to CostDirect.

Next, the CostSkip calculation method in S3603 in FIG. 36 will be described in detail using the processing flow in FIG. In S4001, the direct vector 1 in the prediction direction 1 and the direct vector 2 in the prediction direction 2 are calculated. In S4002, a bidirectional prediction image is generated using the direct vector 1 and the direct vector 2, and CostSkip is calculated from Equation 5. Here, the bidirectional prediction image is, for example, a prediction image obtained from the direct vector 1 and a prediction image obtained from the direct vector 2 obtained by performing an addition average for each pixel as the bidirectional prediction image.

As described above, according to the present invention, when determining the prediction direction of the direct mode, the optimal prediction direction for the encoding target block is selected and attached to the bitstream regardless of the prediction direction of the neighboring blocks. Therefore, the quality of the prediction image in the direct mode can be improved, and the encoding efficiency can be improved.

Also, when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, the costs of bidirectional prediction and unidirectional prediction tend to be relatively close. Therefore, the direct mode prediction direction is fixed to bidirectional prediction that can generate a prediction image with relatively little noise. As a result, it is not necessary to always associate the prediction direction flag in the direct mode for each block to be encoded, and it is possible to improve the encoding efficiency by suppressing the amount of extra information.

(Embodiment 10)
FIG. 41 is a block diagram showing a configuration of an embodiment of a video encoding apparatus using the video encoding method according to the present embodiment. In the present embodiment, the header information (for example, the H.264 picture parameter set or the header parameter that gives the direct mode prediction direction fixed flag generated by the direct mode prediction direction determination unit 3212 to the bit stream for each processing unit such as a picture) The configuration differs from the other embodiments in that it is attached to a slice header or the like.

FIG. 42 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present embodiment. In S4201, the prediction direction when the encoding target block is encoded in the direct mode is determined, and the determined direct prediction direction fixed flag is attached to the picture header or the like. Here, as a method for determining the prediction direction in the direct mode, the flow of FIG. 35 of the ninth embodiment can be used. In S4202, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction determined in S4201. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the direction is performed to determine a more efficient inter prediction mode. Here, Formula 5 etc. are utilized for the cost calculation method. In S4203, it is determined whether the inter prediction mode determined in S4202 is the skip mode. If the determination result in S4203 is true, in S4204, a predicted image in the skip mode is generated, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S4203 is false, it is determined in S4205 whether the determined inter prediction mode is the direct mode and the direct prediction direction fixed flag is on. If the determination result in S4205 is true, in S4206, a bi-directional prediction image in the direct mode is generated, the skip flag is set to 0, and it is attached to the bit stream of the encoding target block. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode is attached to the bit stream of the encoding target block. If the determination result in S4205 is false, inter prediction is performed according to the determined inter prediction mode, predictive image data is generated, the skip flag is set to 0, and the bit stream of the encoding target block is attached. In addition, the inter prediction mode indicating the motion vector detection mode or the direct mode, and the unidirectional prediction in which the inter prediction direction is the prediction direction 1, the unidirectional prediction in the prediction direction 2, or the prediction direction 1 and the prediction direction 2 are set. An inter prediction direction flag indicating whether or not the bidirectional prediction is used is attached to the bit stream of the block to be encoded. Note that the inter prediction mode determination method and the like are the same as those in Embodiment 9, and thus the description thereof is omitted.

As described above, according to the present invention, since the direct mode prediction direction fixed flag is explicitly added to the picture header or the like, whether or not the direct mode prediction direction is fixed to bidirectional prediction can be flexibly determined for each picture. It becomes possible to switch, and it becomes possible to improve encoding efficiency.

(Embodiment 11)
FIG. 43 is a block diagram showing a configuration of an embodiment of a moving picture coding apparatus using the moving picture coding method according to the present embodiment. In the present embodiment, header information (for example, header information) that gives the direct mode prediction direction flag generated by the direct mode prediction direction determination unit 3212 and the direct mode prediction direction fixed flag to the bitstream for each processing unit such as a picture. H.264 picture parameter set, slice header, etc.) is different from the other embodiments.

FIG. 44 is a diagram showing an outline of the processing flow of the moving picture coding method according to the present embodiment. In S4401, the prediction direction when the encoding target block is encoded in the direct mode is determined, and the determined direct mode prediction direction fixed flag and the direct prediction direction flag are attached to the picture header or the like. Here, as a method for determining the prediction direction in the direct mode, the flow of FIG. 35 of the ninth embodiment can be used. In S4402, a motion vector detection mode for generating a predicted image using a motion vector based on a motion detection result, a direct mode for generating a predicted image using a predicted motion vector generated from an adjacent block, and the prediction determined in S4401. The cost comparison of the skip mode for generating a predicted image using the predicted motion vector generated according to the direction is performed to determine a more efficient inter prediction mode. Here, Formula 5 etc. are utilized for the cost calculation method. In S4403, it is determined whether the inter prediction mode determined in S4402 is a skip mode. If the determination result in S4403 is true, a predicted image in skip mode is generated in S4404, and the skip flag is set to 1 to accompany the bit stream of the encoding target block. If the determination result in S4403 is false, it is determined in S4405 whether the determined inter prediction mode is the direct mode and the direct prediction direction fixed flag is on. If the determination result in S4405 is true, in S4406, a prediction image is generated according to the prediction direction of the direct mode determined in S4401, and the skip flag is set to 0 and is attached to the bit stream of the encoding target block. In addition, an inter prediction mode indicating the motion vector detection mode or the direct mode is attached to the bit stream of the encoding target block. If the determination result in S4405 is false, inter prediction is performed according to the determined inter prediction mode, predicted image data is generated, the skip flag is set to 0, and the bit stream of the block to be encoded is attached. In addition, an inter prediction mode and an inter prediction direction flag indicating the motion vector detection mode or the direct mode are attached to the bit stream of the encoding target block. Note that the inter prediction mode determination method and the like are the same as those in Embodiment 9, and thus the description thereof is omitted.

Thus, according to the present invention, whether the direct mode prediction direction is fixed to a certain prediction direction in order to explicitly give the direct mode prediction direction fixed flag and the direct prediction direction flag to the picture header or the like. Can be flexibly switched for each picture, and the encoding efficiency can be improved.

(Embodiment 12)
FIG. 45 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment.

As shown in FIG. 45, the moving picture decoding apparatus includes a variable length decoding unit 4501, an inverse quantization unit 4502, an inverse orthogonal transform unit 4503, a block memory 4504, a frame memory 4505, an intra prediction unit 4506, and an inter prediction unit 4507. , An inter prediction control unit 4508, a reference picture list management unit 4509, and a direct mode prediction direction determination unit 4510.

The variable length decoding unit 4501 performs variable length decoding processing on the input bitstream, and performs quantization on which picture type information, inter prediction mode, inter prediction direction flag, skip flag, and variable length decoding processing are performed. Generate coefficients. The inverse quantization unit 4502 performs an inverse quantization process on the quantization coefficient that has been subjected to the variable length decoding process. The inverse orthogonal transform unit 4503 transforms the orthogonal transform coefficient that has been subjected to the inverse quantization process from the frequency domain to the image domain to obtain prediction error image data. The block memory 4504 stores prediction error image data and an image sequence generated by adding the prediction image data in units of blocks. The frame memory 4505 stores the image sequence in units of frames. The intra prediction unit 4506 generates predicted image data of the decoding target block by performing intra prediction using the block-by-block image sequence stored in the block memory 4504. The inter prediction unit 4507 generates predicted image data of the decoding target block by performing inter prediction using the frame-by-frame image sequence stored in the frame memory 4505. The inter prediction control unit 4508 controls the motion vector and the prediction image data generation method in the inter prediction according to the inter prediction mode, the inter prediction direction, and the skip flag.

The reference picture list management unit 4509 assigns a reference picture index to an encoded reference picture to be referred to in inter prediction, and creates a reference list along with the display order (similar to FIG. 33 in the ninth embodiment). Since B pictures can be encoded with reference to two pictures, two reference lists are held.

The direct mode prediction direction determination unit 4510 uses the reference picture list 1 and the reference picture list 2 created by the reference picture list management unit 4509 to determine the direct mode prediction direction of the block to be encoded, and the direct mode prediction direction Set a fixed flag. Note that the determination flow of the direct mode prediction direction fixed flag is the same as that in FIG.

FIG. 46 is a diagram showing an outline of the processing flow of the video decoding method according to the present embodiment. In S4601, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S4601 is true, direct vector 1 and direct vector 2 are calculated in S4602, and a bidirectional prediction image is generated. If the determination result in S4601 is false, that is, if it is not the skip mode, it is determined in S4603 whether the decoded prediction mode is the direct mode. If the determination result in S4603 is true, it is determined in S4604 whether the direct mode prediction direction fixed flag is on. If the determination result in S4604 is true, in S4605, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S4604 is false, in S4606, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction, and a predicted image is generated. If the determination result in S4603 is false, that is, the motion vector detection mode, a predicted image is generated using the decoded inter prediction direction and motion vector. In this embodiment, if the direct mode prediction direction fixed flag is on in S4605, a bidirectional prediction image is generated. However, for example, a unidirectional prediction image is generated in accordance with the encoding method. It doesn't matter if you do.

FIG. 47 is a diagram showing an example of bitstream syntax in the video decoding method according to the present embodiment. In FIG. 47, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction flag.

Thus, according to the present invention, when determining the prediction direction of the direct mode, by selecting the optimal prediction direction for the encoding target block and attaching it to the bitstream regardless of the prediction direction of the neighboring blocks. It becomes possible to appropriately decode a bit stream with improved encoding efficiency.

When the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, the prediction direction in the direct mode is fixed to bidirectional prediction, and the direct mode By not attaching the prediction direction flag to the bitstream, it is possible to appropriately decode a bitstream that has improved the encoding efficiency by suppressing the amount of extra information.

(Embodiment 13)
FIG. 48 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment. In the present embodiment, header information (for example, H.264 picture parameter set or slice) that gives the direct mode prediction direction fixed flag generated by the variable length decoding unit 4501 to the bitstream for each processing unit such as a picture. The configuration differs from the other embodiments in that the bit stream attached to the header or the like can be decoded.

FIG. 49 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the present embodiment. In S4901, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S4901 is true, in S4902, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S4901 is false, that is, if it is not the skip mode, it is determined in S4903 whether the decoded prediction mode is the direct mode. If the determination result in S4903 is true, it is determined whether the direct mode prediction direction fixed flag decoded from the bitstream in S4904 is on. If the determination result in S4904 is true, in S4905, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S4904 is false, in S4906, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction flag, and a predicted image is generated. If the determination result in S4903 is false, that is, the motion vector detection mode, a predicted image is generated using the decoded inter prediction direction flag and motion vector. In this embodiment, if the direct mode prediction direction fixed flag is on in S4905, a bidirectional prediction image is generated. However, in accordance with the encoding method, for example, a unidirectional prediction image is generated. It doesn't matter if you do. FIG. 50 is a diagram illustrating an example of the bitstream syntax in the video decoding method according to the present embodiment. In FIG. 50, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction flag. Also, fixed_direct_pred added to the picture header or the like represents a direct mode prediction direction fixed flag.

As described above, according to the present invention, whether or not to fix the direct mode prediction direction to bidirectional prediction can be flexibly set for each picture by explicitly assigning the direct mode prediction direction fixed flag to the picture header or the like. By switching to, it becomes possible to appropriately decode a bit stream with improved encoding efficiency.

(Embodiment 14)
FIG. 51 is a block diagram showing a configuration of an embodiment of a moving picture decoding apparatus using the moving picture decoding method according to the present embodiment. In the present embodiment, header information (for example, H.264) that adds the direct prediction direction flag and the direct mode prediction direction fixed flag generated by the variable length decoding unit 4501 to the bitstream for each processing unit such as a picture. H.264 picture parameter set, slice header, etc.) can be decoded, and the configuration is different from the other embodiments.

FIG. 52 is a diagram showing an outline of the processing flow of the moving picture decoding method according to the present embodiment. In S5201, it is determined whether or not the skip flag decoded from the bitstream is 1. If the determination result in S5201 is true, in S5202, the direct vector 1 and the direct vector 2 are calculated, and a bidirectional prediction image is generated. If the determination result in S5201 is false, that is, if it is not the skip mode, it is determined in S5203 whether the decoded prediction mode is the direct mode. If the determination result in S5203 is true, it is determined in S5204 whether the direct mode prediction direction fixed flag decoded from the bit stream is on. If the determination result in S5204 is true, in S5205, the direct vector 1 and the direct vector 2 are calculated according to the direct mode prediction flag decoded from the bit stream, and a predicted image is generated. If the determination result in S5204 is false, in S5206, the direct vector 1 and the direct vector 2 are calculated according to the decoded inter prediction direction flag, and a predicted image is generated. If the determination result in S5203 is false, that is, the motion vector detection mode, a predicted image is generated using the decoded inter prediction direction flag and motion vector.

FIG. 53 is a diagram showing an example of the bitstream syntax in the video decoding method according to the present embodiment. In FIG. 53, skip_flag represents a skip flag, pred_mode represents an inter prediction mode, and inter_pred_idc represents an inter prediction direction flag. Further, fixed_direct_pred added to a picture header or the like represents a direct mode prediction direction fixed flag, and direct_pred_idc represents a direct prediction direction flag.

As described above, according to the present invention, the direct mode prediction direction fixed flag and the direct prediction direction flag are explicitly added to the picture header or the like, thereby fixing the direct mode prediction direction to a certain prediction direction. It is possible to appropriately decode a bit stream with improved coding efficiency by switching whether or not for each picture.

(Embodiment 15)
In this embodiment, a case where Embodiment 1 and Embodiment 9 are combined will be described. In Embodiment 1, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, the prediction direction in the skip mode is fixed to unidirectional prediction. This shows an example of improving the coding efficiency.

Also, in Embodiment 9, when the reference picture indicated by the reference picture index 1 in the prediction direction 1 and the reference picture indicated by the reference picture index 2 in the prediction direction 2 are the same picture, bi-directional prediction in the direct mode and one piece Since the cost with direction prediction tends to be relatively close, the prediction direction flag of direct mode is encoded by fixing the prediction direction of direct mode to either bidirectional prediction or unidirectional prediction. An example has been shown in which it is not necessary to always accompany each block, and the encoding efficiency is improved by suppressing the amount of extra information.

When combining Embodiment 1 and Embodiment 9, if the reference picture indicated by reference index 1 in prediction direction 1 and the reference picture indicated by reference index 2 in prediction direction 2 are the same picture, skip mode By fixing the prediction direction to unidirectional prediction, it is possible to improve the coding efficiency of the skip mode, but in the skip mode, some encoding targets for which bi-directional prediction is less expensive than unidirectional prediction The block will be encoded as direct mode bi-directional prediction. Therefore, by fixing the prediction direction of the direct mode to bidirectional prediction, it is not necessary to always attach more prediction direction flags of the direct mode for each encoding target block, and the amount of extra information is suppressed. Thus, encoding efficiency can be improved.

That is, when the reference picture indicated by the reference index 1 in the prediction direction 1 and the reference picture indicated by the reference index 2 in the prediction direction 2 are the same picture, the prediction direction in the skip mode is fixed to unidirectional prediction, and the direct mode The prediction direction is fixed to bidirectional prediction. By fixing the prediction direction of the skip mode to one direction, the prediction accuracy can be improved. However, for some coding target blocks, the bidirectional prediction has a higher prediction accuracy. Accordingly, by fixing the prediction direction of the direct mode in both directions, it becomes possible to improve the prediction accuracy of some coding target blocks whose prediction accuracy is reduced by fixing the skip mode to unidirectional prediction. . Furthermore, by fixing the direct mode to bidirectional prediction, the direct mode prediction direction flag becomes unnecessary, and thus the encoding efficiency can be further improved. Thus, with the configuration of the fifteenth embodiment, it is possible to improve the prediction accuracy while improving the encoding efficiency.

(Embodiment 16)
By recording a program for realizing the configuration of the moving picture encoding method or the moving picture decoding method shown in each of the above embodiments on a storage medium, the computer system in which the processing shown in each of the above embodiments is independent It becomes possible to carry out easily. The storage medium may be any medium that can record a program, such as a magnetic disk, an optical disk, a magneto-optical disk, an IC card, and a semiconductor memory.

Further, application examples of the moving picture encoding method and the moving picture decoding method shown in the above embodiments and a system using the same will be described.

FIG. 54 is a diagram showing an overall configuration of a content supply system ex100 that realizes a content distribution service. A communication service providing area is divided into desired sizes, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed wireless stations, are installed in each cell.

This content supply system ex100 includes a computer ex111, a PDA (Personal Digital Assistant) ex112, a camera ex113, a mobile phone ex114, a game machine ex115 via the Internet ex101, the Internet service provider ex102, the telephone network ex104, and the base stations ex106 to ex110. Etc. are connected.

However, the content supply system ex100 is not limited to the configuration as shown in FIG. 54, and any element may be connected in combination. In addition, each device may be directly connected to the telephone network ex104 without going from the base station ex106, which is a fixed wireless station, to ex110. In addition, the devices may be directly connected to each other via short-range wireless or the like.

The camera ex113 is a device that can shoot moving images such as a digital video camera, and the camera ex116 is a device that can shoot still images and movies such as a digital camera. The mobile phone ex114 is a GSM (registered trademark) (Global System for Mobile Communications) system, a CDMA (Code Division Multiple Access) system, a W-CDMA (Wideband-Code Division Multiple Access) system, or an LTE (Long Term Evolution). It is possible to use any of the above-mentioned systems, HSPA (High Speed Packet Access) mobile phone, PHS (Personal Handyphone System), or the like.

In the content supply system ex100, the camera ex113 and the like are connected to the streaming server ex103 through the base station ex109 and the telephone network ex104, thereby enabling live distribution and the like. In live distribution, the content (for example, music live video) captured by the user using the camera ex113 is encoded as described in the above embodiments, and transmitted to the streaming server ex103. On the other hand, the streaming server ex103 stream-distributes the content data transmitted to the requested client. Examples of the client include a computer ex111, a PDA ex112, a camera ex113, a mobile phone ex114, and a game machine ex115 that can decode the encoded data. Each device that receives the distributed data decodes the received data and reproduces it.

Note that the captured data may be encoded by the camera ex113, the streaming server ex103 that performs data transmission processing, or may be shared with each other. Similarly, the decryption processing of the distributed data may be performed by the client, the streaming server ex103, or may be performed in common with each other. In addition to the camera ex113, still images and / or moving image data captured by the camera ex116 may be transmitted to the streaming server ex103 via the computer ex111. The encoding process in this case may be performed by any of the camera ex116, the computer ex111, and the streaming server ex103, or may be performed in a shared manner.

Further, these encoding / decoding processes are generally performed in the computer ex111 and the LSI ex500 included in each device. The LSI ex500 may be configured as a single chip or a plurality of chips. It should be noted that moving image encoding / decoding software is incorporated into some recording medium (CD-ROM, flexible disk, hard disk, etc.) that can be read by the computer ex111, etc., and encoding / decoding processing is performed using the software. May be. Furthermore, when the mobile phone ex114 is equipped with a camera, moving image data acquired by the camera may be transmitted. The moving image data at this time is data encoded by the LSI ex500 included in the mobile phone ex114.

Further, the streaming server ex103 may be a plurality of servers or a plurality of computers, and may process, record, and distribute data in a distributed manner.

As described above, in the content supply system ex100, the encoded data can be received and reproduced by the client. Thus, in the content supply system ex100, the information transmitted by the user can be received, decrypted and reproduced by the client in real time, and personal broadcasting can be realized even for a user who does not have special rights or facilities.

In addition to the example of the content supply system ex100, as shown in FIG. 55, at least one of the video encoding device and the video decoding device of each of the above embodiments is incorporated in the digital broadcasting system ex200. be able to. Specifically, in the broadcast station ex201, multiplexed data obtained by multiplexing music data and the like on video data is transmitted to a communication or satellite ex202 via radio waves. This video data is data encoded by the moving image encoding method described in the above embodiments. Receiving this, the broadcasting satellite ex202 transmits a radio wave for broadcasting, and this radio wave is received by a home antenna ex204 capable of receiving satellite broadcasting. The received multiplexed data is decoded and reproduced by a device such as the television (receiver) ex300 or the set top box (STB) ex217.

Also, a reader / recorder ex218 that reads and decodes multiplexed data recorded on a recording medium ex215 such as a DVD or a BD, or encodes a video signal on the recording medium ex215 and, in some cases, multiplexes and writes it with a music signal. It is possible to mount the moving picture decoding apparatus or moving picture encoding apparatus described in the above embodiments. In this case, the reproduced video signal is displayed on the monitor ex219, and the video signal can be reproduced in another device or system using the recording medium ex215 on which the multiplexed data is recorded. Alternatively, a moving picture decoding apparatus may be mounted in a set-top box ex217 connected to a cable ex203 for cable television or an antenna ex204 for satellite / terrestrial broadcasting and displayed on the monitor ex219 of the television. At this time, the moving picture decoding apparatus may be incorporated in the television instead of the set top box.

FIG. 56 is a diagram illustrating a television (receiver) ex300 that uses the video decoding method and the video encoding method described in each of the above embodiments. The television ex300 obtains or outputs multiplexed data in which audio data is multiplexed with video data via the antenna ex204 or the cable ex203 that receives the broadcast, and demodulates the received multiplexed data. Alternatively, the modulation / demodulation unit ex302 that modulates multiplexed data to be transmitted to the outside, and the demodulated multiplexed data is separated into video data and audio data, or the video data and audio data encoded by the signal processing unit ex306 Is provided with a multiplexing / demultiplexing unit ex303.

Further, the television ex300 decodes the audio data and the video data, or encodes each information, the audio signal processing unit ex304, the signal processing unit ex306 including the video signal processing unit ex305, and the decoded audio signal. A speaker ex307 for outputting, and an output unit ex309 having a display unit ex308 such as a display for displaying the decoded video signal. Furthermore, the television ex300 includes an interface unit ex317 including an operation input unit ex312 that receives an input of a user operation. Furthermore, the television ex300 includes a control unit ex310 that performs overall control of each unit, and a power supply circuit unit ex311 that supplies power to each unit. In addition to the operation input unit ex312, the interface unit ex317 includes a bridge unit ex313 connected to an external device such as a reader / recorder ex218, a recording unit ex216 such as an SD card, and an external recording unit such as a hard disk. A driver ex315 for connecting to a medium, a modem ex316 for connecting to a telephone network, and the like may be included. Note that the recording medium ex216 is capable of electrically recording information by using a nonvolatile / volatile semiconductor memory element to be stored. Each part of the television ex300 is connected to each other via a synchronous bus.

First, a configuration in which the television ex300 decodes and reproduces multiplexed data acquired from the outside by the antenna ex204 and the like will be described. The television ex300 receives a user operation from the remote controller ex220 or the like, and demultiplexes the multiplexed data demodulated by the modulation / demodulation unit ex302 by the multiplexing / demultiplexing unit ex303 based on the control of the control unit ex310 having a CPU or the like. Furthermore, in the television ex300, the separated audio data is decoded by the audio signal processing unit ex304, and the separated video data is decoded by the video signal processing unit ex305 using the decoding method described in each of the above embodiments. The decoded audio signal and video signal are output from the output unit ex309 to the outside. At the time of output, these signals may be temporarily stored in the buffers ex318, ex319, etc. so that the audio signal and the video signal are reproduced in synchronization. Also, the television ex300 may read multiplexed data from recording media ex215 and ex216 such as a magnetic / optical disk and an SD card, not from broadcasting. Next, a configuration in which the television ex300 encodes an audio signal or a video signal and transmits the signal to the outside or to a recording medium will be described. The television ex300 receives a user operation from the remote controller ex220 and the like, encodes an audio signal with the audio signal processing unit ex304, and converts the video signal with the video signal processing unit ex305 based on the control of the control unit ex310. Encoding is performed using the encoding method described in (1). The encoded audio signal and video signal are multiplexed by the multiplexing / demultiplexing unit ex303 and output to the outside. When multiplexing, these signals may be temporarily stored in the buffers ex320, ex321, etc. so that the audio signal and the video signal are synchronized. Note that a plurality of buffers ex318, ex319, ex320, and ex321 may be provided as illustrated, or one or more buffers may be shared. Further, in addition to the illustrated example, data may be stored in the buffer as a buffer material that prevents system overflow and underflow, for example, between the modulation / demodulation unit ex302 and the multiplexing / demultiplexing unit ex303.

In addition to acquiring audio data and video data from broadcasts, recording media, and the like, the television ex300 has a configuration for receiving AV input of a microphone and a camera, and performs encoding processing on the data acquired from them. Also good. Here, the television ex300 has been described as a configuration capable of the above-described encoding processing, multiplexing, and external output, but these processing cannot be performed, and only the above-described reception, decoding processing, and external output are possible. It may be a configuration.

In addition, when reading or writing multiplexed data from a recording medium by the reader / recorder ex218, the decoding process or the encoding process may be performed by either the television ex300 or the reader / recorder ex218, The reader / recorder ex218 may share with each other.

As an example, FIG. 57 shows the configuration of the information reproducing / recording unit ex400 when data is read from or written to an optical disk. The information reproducing / recording unit ex400 includes elements ex401, ex402, ex403, ex404, ex405, ex406, and ex407 described below. The optical head ex401 irradiates a laser spot on the recording surface of the recording medium ex215 that is an optical disk to write information, and detects reflected light from the recording surface of the recording medium ex215 to read the information. The modulation recording unit ex402 electrically drives a semiconductor laser built in the optical head ex401 and modulates the laser beam according to the recording data. The reproduction demodulator ex403 amplifies the reproduction signal obtained by electrically detecting the reflected light from the recording surface by the photodetector built in the optical head ex401, separates and demodulates the signal component recorded on the recording medium ex215, and is necessary To play back information. The buffer ex404 temporarily holds information to be recorded on the recording medium ex215 and information reproduced from the recording medium ex215. The disk motor ex405 rotates the recording medium ex215. The servo controller ex406 moves the optical head ex401 to a predetermined information track while controlling the rotational drive of the disk motor ex405, and performs a laser spot tracking process. The system control unit ex407 controls the entire information reproduction / recording unit ex400. In the reading and writing processes described above, the system control unit ex407 uses various kinds of information held in the buffer ex404, and generates and adds new information as necessary, and the modulation recording unit ex402, the reproduction demodulation unit This is realized by recording / reproducing information through the optical head ex401 while operating the ex403 and the servo control unit ex406 in a coordinated manner. The system control unit ex407 is composed of, for example, a microprocessor, and executes these processes by executing a read / write program.

In the above, the optical head ex401 has been described as irradiating a laser spot. However, a configuration in which higher-density recording is performed using near-field light may be used.

FIG. 58 shows a schematic diagram of a recording medium ex215 that is an optical disk. Guide grooves (grooves) are formed in a spiral shape on the recording surface of the recording medium ex215, and address information indicating the absolute position on the disc is recorded in advance on the information track ex230 by changing the shape of the groove. This address information includes information for specifying the position of the recording block ex231 that is a unit for recording data, and the recording block is specified by reproducing the information track ex230 and reading the address information in a recording or reproducing apparatus. Can do. Further, the recording medium ex215 includes a data recording area ex233, an inner peripheral area ex232, and an outer peripheral area ex234. The area used for recording user data is the data recording area ex233, and the inner circumference area ex232 and the outer circumference area ex234 arranged on the inner or outer circumference of the data recording area ex233 are used for specific purposes other than user data recording. Used. The information reproducing / recording unit ex400 reads / writes encoded audio data, video data, or multiplexed data obtained by multiplexing these data with respect to the data recording area ex233 of the recording medium ex215.

In the above description, an optical disk such as a single-layer DVD or BD has been described as an example. However, the present invention is not limited to these, and an optical disk having a multilayer structure and capable of recording other than the surface may be used. Also, an optical disc with a multi-dimensional recording / reproducing structure, such as recording information using light of different wavelengths in the same place on the disc, or recording different layers of information from various angles. It may be.

Also, in the digital broadcasting system ex200, the car ex210 having the antenna ex205 can receive data from the satellite ex202 and the like, and the moving image can be reproduced on a display device such as the car navigation ex211 that the car ex210 has. Note that the configuration of the car navigation ex211 may be, for example, the configuration shown in FIG. 56 with the addition of a GPS receiver, and the same may be considered for the computer ex111, the mobile phone ex114, and the like.

FIG. 59 (a) is a diagram showing a mobile phone ex114 using the moving picture decoding method and the moving picture encoding method described in the above embodiment. The mobile phone ex114 includes an antenna ex350 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex365 capable of capturing video and still images, a video captured by the camera unit ex365, a video received by the antenna ex350, and the like Is provided with a display unit ex358 such as a liquid crystal display for displaying the decrypted data. The mobile phone ex114 further includes a main body unit having an operation key unit ex366, an audio output unit ex357 such as a speaker for outputting audio, an audio input unit ex356 such as a microphone for inputting audio, a captured video, In the memory unit ex367 for storing encoded data or decoded data such as still images, recorded audio, received video, still images, mails, or the like, or an interface unit with a recording medium for storing data A slot ex364 is provided.

Furthermore, a configuration example of the mobile phone ex114 will be described with reference to FIG. The mobile phone ex114 has a power supply circuit part ex361, an operation input control part ex362, and a video signal processing part ex355 with respect to a main control part ex360 that comprehensively controls each part of the main body including the display part ex358 and the operation key part ex366. , A camera interface unit ex363, an LCD (Liquid Crystal Display) control unit ex359, a modulation / demodulation unit ex352, a multiplexing / demultiplexing unit ex353, an audio signal processing unit ex354, a slot unit ex364, and a memory unit ex367 are connected to each other via a bus ex370. ing.

When the end of call and the power key are turned on by the user's operation, the power supply circuit ex361 starts up the mobile phone ex114 in an operable state by supplying power from the battery pack to each unit.

The cellular phone ex114 converts the audio signal collected by the audio input unit ex356 in the voice call mode into a digital audio signal by the audio signal processing unit ex354 based on the control of the main control unit ex360 having a CPU, a ROM, a RAM, and the like. Then, this is subjected to spectrum spread processing by the modulation / demodulation unit ex352, digital-analog conversion processing and frequency conversion processing are performed by the transmission / reception unit ex351, and then transmitted via the antenna ex350. The mobile phone ex114 also amplifies the received data received via the antenna ex350 in the voice call mode, performs frequency conversion processing and analog-digital conversion processing, performs spectrum despreading processing by the modulation / demodulation unit ex352, and performs voice signal processing unit After being converted into an analog audio signal by ex354, this is output from the audio output unit ex356.

Further, when an e-mail is transmitted in the data communication mode, the text data of the e-mail input by operating the operation key unit ex366 of the main unit is sent to the main control unit ex360 via the operation input control unit ex362. The main control unit ex360 performs spread spectrum processing on the text data in the modulation / demodulation unit ex352, performs digital analog conversion processing and frequency conversion processing in the transmission / reception unit ex351, and then transmits the text data to the base station ex110 via the antenna ex350. . In the case of receiving an e-mail, almost the reverse process is performed on the received data and output to the display unit ex358.

When transmitting video, still images, or video and audio in the data communication mode, the video signal processing unit ex355 compresses the video signal supplied from the camera unit ex365 by the moving image encoding method described in the above embodiments. The encoded video data is sent to the multiplexing / separating unit ex353. The audio signal processing unit ex354 encodes the audio signal picked up by the audio signal input unit ex356 while the camera unit ex365 images a video, a still image, and the like, and the encoded audio data is sent to the multiplexing / separating unit ex353. Send it out.

The multiplexing / demultiplexing unit ex353 multiplexes the encoded video data supplied from the video signal processing unit ex355 and the encoded audio data supplied from the audio signal processing unit ex354 by a predetermined method, and is obtained as a result. The multiplexed data is subjected to spread spectrum processing by the modulation / demodulation circuit unit ex352, subjected to digital analog conversion processing and frequency conversion processing by the transmission / reception unit ex351, and then transmitted via the antenna ex350.

Decode multiplexed data received via antenna ex350 when receiving video file data linked to a homepage, etc. in data communication mode, or when receiving e-mail with video and / or audio attached Therefore, the multiplexing / separating unit ex353 separates the multiplexed data into a video data bit stream and an audio data bit stream, and performs video signal processing on the video data encoded via the synchronization bus ex370. The encoded audio data is supplied to the audio signal processing unit ex354 while being supplied to the unit ex355. The video signal processing unit ex355 decodes the video signal by decoding using the video decoding method corresponding to the video encoding method described in each of the above embodiments, and the display unit ex358 via the LCD control unit ex359. From, for example, video and still images included in a moving image file linked to a home page are displayed. The audio signal processing unit ex354 decodes the audio signal, and the audio is output from the audio output unit ex357.

In addition to the transmission / reception type terminal having both the encoder and the decoder, the terminal such as the mobile phone ex114 is referred to as a transmission terminal having only an encoder and a receiving terminal having only a decoder. There are three possible mounting formats. Furthermore, in the digital broadcasting system ex200, it has been described that multiplexed data in which music data is multiplexed with video data is received and transmitted. However, in addition to audio data, character data related to video is multiplexed. It may be converted data, or may be video data itself instead of multiplexed data.

As described above, the moving picture encoding method or the moving picture decoding method shown in each of the above embodiments can be used in any of the above-described devices / systems. The described effect can be obtained.

Further, the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the present invention.

(Embodiment 17)
The moving picture coding method or apparatus shown in the above embodiments and the moving picture coding method or apparatus compliant with different standards such as MPEG-2, MPEG4-AVC, and VC-1 are appropriately switched as necessary. Thus, it is also possible to generate video data.

Here, when a plurality of pieces of video data conforming to different standards are generated, it is necessary to select a decoding method corresponding to each standard when decoding. However, since it is impossible to identify which standard the video data to be decoded complies with, there arises a problem that an appropriate decoding method cannot be selected.

In order to solve this problem, multiplexed data obtained by multiplexing audio data or the like with video data is configured to include identification information indicating which standard the video data conforms to. A specific configuration of multiplexed data including video data generated by the moving picture encoding method or apparatus shown in the above embodiments will be described below. The multiplexed data is a digital stream in the MPEG-2 transport stream format.

FIG. 60 shows a structure of multiplexed data. As shown in FIG. 60, multiplexed data is obtained by multiplexing one or more of a video stream, an audio stream, a presentation graphics stream (PG), and an interactive graphics stream. The video stream indicates the main video and sub-video of the movie, the audio stream (IG) indicates the main audio portion of the movie and the sub-audio mixed with the main audio, and the presentation graphics stream indicates the subtitles of the movie. Here, the main video indicates a normal video displayed on the screen, and the sub-video is a video displayed on a small screen in the main video. The interactive graphics stream indicates an interactive screen created by arranging GUI components on the screen. The video stream is encoded by the moving image encoding method or apparatus shown in the above embodiments, or the moving image encoding method or apparatus conforming to the conventional standards such as MPEG-2, MPEG4-AVC, and VC-1. ing. The audio stream is encoded by a method such as Dolby AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, or linear PCM.

Each stream included in the multiplexed data is identified by PID. For example, 0x1011 for video streams used for movie images, 0x1100 to 0x111F for audio streams, 0x1200 to 0x121F for presentation graphics, 0x1400 to 0x141F for interactive graphics streams, 0x1B00 to 0x1B1F are assigned to video streams used for sub-pictures, and 0x1A00 to 0x1A1F are assigned to audio streams used for sub-audio mixed with the main audio.

FIG. 61 is a diagram schematically showing how multiplexed data is multiplexed. First, a video stream ex235 composed of a plurality of video frames and an audio stream ex238 composed of a plurality of audio frames are converted into PES packet sequences ex236 and ex239, respectively, and converted into TS packets ex237 and ex240. Similarly, the data of the presentation graphics stream ex241 and interactive graphics ex244 are converted into PES packet sequences ex242 and ex245, respectively, and further converted into TS packets ex243 and ex246. The multiplexed data ex247 is configured by multiplexing these TS packets into one stream.

FIG. 62 shows in more detail how the video stream is stored in the PES packet sequence. The first row in FIG. 62 shows a video frame sequence of the video stream. The second level shows a PES packet sequence. As shown by arrows yy1, yy2, yy3, and yy4 in FIG. 62, a plurality of Video Presentation Units in a video stream are divided into pictures, B pictures, and P pictures, and are stored in the payload of the PES packet. . Each PES packet has a PES header, and a PTS (Presentation Time-Stamp) that is a display time of a picture and a DTS (Decoding Time-Stamp) that is a decoding time of a picture are stored in the PES header.

FIG. 63 shows the format of TS packets that are finally written in the multiplexed data. The TS packet is a 188-byte fixed-length packet composed of a 4-byte TS header having information such as a PID for identifying a stream and a 184-byte TS payload for storing data. The PES packet is divided and stored in the TS payload. The In the case of a BD-ROM, a 4-byte TP_Extra_Header is added to a TS packet, forms a 192-byte source packet, and is written in multiplexed data. In TP_Extra_Header, information such as ATS (Arrival_Time_Stamp) is described. ATS indicates the transfer start time of the TS packet to the PID filter of the decoder. Source packets are arranged in the multiplexed data as shown in the lower part of FIG. 63, and the number incremented from the head of the multiplexed data is called SPN (source packet number).

In addition, TS packets included in the multiplexed data include PAT (Program Association Table), PMT (Program Map Table), PCR (Program Clock Reference), and the like in addition to each stream such as video / audio / caption. PAT indicates what the PID of the PMT used in the multiplexed data is, and the PID of the PAT itself is registered as 0. The PMT has the PID of each stream such as video / audio / subtitles included in the multiplexed data and the attribute information of the stream corresponding to each PID, and has various descriptors related to the multiplexed data. The descriptor includes copy control information for instructing permission / non-permission of copying of multiplexed data. In order to synchronize the ATC (Arrival Time Clock), which is the ATS time axis, and the STC (System Time Clock), which is the PTS / DTS time axis, the PCR corresponds to the ATS in which the PCR packet is transferred to the decoder. Contains STC time information.

FIG. 64 is a diagram for explaining the data structure of the PMT in detail. A PMT header describing the length of data included in the PMT is arranged at the head of the PMT. After that, a plurality of descriptors related to multiplexed data are arranged. The copy control information and the like are described as descriptors. After the descriptor, a plurality of pieces of stream information regarding each stream included in the multiplexed data are arranged. The stream information includes a stream descriptor in which a stream type, a stream PID, and stream attribute information (frame rate, aspect ratio, etc.) are described to identify a compression codec of the stream. There are as many stream descriptors as the number of streams existing in the multiplexed data.

When recording on a recording medium or the like, the multiplexed data is recorded together with the multiplexed data information file.

As shown in FIG. 65, the multiplexed data information file is management information of multiplexed data, has a one-to-one correspondence with the multiplexed data, and includes multiplexed data information, stream attribute information, and an entry map.

As shown in FIG. 65, the multiplexed data information includes a system rate, a reproduction start time, and a reproduction end time. The system rate indicates a maximum transfer rate of multiplexed data to a PID filter of a system target decoder described later. The ATS interval included in the multiplexed data is set to be equal to or less than the system rate. The playback start time is the PTS of the first video frame of the multiplexed data, and the playback end time is set by adding the playback interval for one frame to the PTS of the video frame at the end of the multiplexed data.

In the stream attribute information, as shown in FIG. 66, attribute information about each stream included in the multiplexed data is registered for each PID. The attribute information has different information for each video stream, audio stream, presentation graphics stream, and interactive graphics stream. The video stream attribute information includes the compression codec used to compress the video stream, the resolution of the individual picture data constituting the video stream, the aspect ratio, and the frame rate. It has information such as how much it is. The audio stream attribute information includes the compression codec used to compress the audio stream, the number of channels included in the audio stream, the language supported, and the sampling frequency. With information. These pieces of information are used for initialization of the decoder before the player reproduces it.

In this embodiment, among the multiplexed data, the stream type included in the PMT is used. Also, when multiplexed data is recorded on the recording medium, video stream attribute information included in the multiplexed data information is used. Specifically, in the video encoding method or apparatus shown in each of the above embodiments, the video encoding shown in each of the above embodiments for the stream type or video stream attribute information included in the PMT. There is provided a step or means for setting unique information indicating that the video data is generated by the method or apparatus. With this configuration, it is possible to discriminate between video data generated by the moving picture encoding method or apparatus described in the above embodiments and video data compliant with other standards.

FIG. 67 shows the steps of the moving picture decoding method according to the present embodiment. In step exS100, the stream type included in the PMT or the video stream attribute information included in the multiplexed data information is acquired from the multiplexed data. Next, in step exS101, it is determined whether or not the stream type or the video stream attribute information indicates multiplexed data generated by the moving picture encoding method or apparatus described in the above embodiments. To do. When it is determined that the stream type or the video stream attribute information is generated by the moving image encoding method or apparatus described in the above embodiments, in step exS102, the above embodiments are performed. Decoding is performed by the moving picture decoding method shown in the form. If the stream type or video stream attribute information indicates that it conforms to a standard such as conventional MPEG-2, MPEG4-AVC, or VC-1, in step exS103, the conventional information Decoding is performed by a moving image decoding method compliant with the standard.

In this way, by setting a new unique value in the stream type or video stream attribute information, whether or not decoding is possible with the moving picture decoding method or apparatus described in each of the above embodiments is performed. Judgment can be made. Therefore, even when multiplexed data conforming to different standards is input, an appropriate decoding method or apparatus can be selected, and therefore decoding can be performed without causing an error. In addition, the moving picture encoding method or apparatus or the moving picture decoding method or apparatus described in this embodiment can be used in any of the above-described devices and systems.

(Embodiment 18)
The moving picture encoding method and apparatus and moving picture decoding method and apparatus described in the above embodiments are typically realized by an LSI that is an integrated circuit. As an example, FIG. 68 shows a configuration of the LSI ex500 that is made into one chip. The LSI ex500 includes elements ex501, ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 described below, and each element is connected via a bus ex510. The power supply circuit unit ex505 is activated to an operable state by supplying power to each unit when the power supply is on.

For example, when performing the encoding process, the LSI ex500 performs the microphone ex117 and the camera ex113 by the AV I / O ex509 based on the control of the control unit ex501 including the CPU ex502, the memory controller ex503, the stream controller ex504, the drive frequency control unit ex512, and the like. The AV signal is input from the above. The input AV signal is temporarily stored in an external memory ex511 such as SDRAM. Based on the control of the control unit ex501, the accumulated data is divided into a plurality of times as appropriate according to the processing amount and the processing speed and sent to the signal processing unit ex507, and the signal processing unit ex507 encodes an audio signal and / or video. Signal encoding is performed. Here, the encoding process of the video signal is the encoding process described in the above embodiments. The signal processing unit ex507 further performs processing such as multiplexing the encoded audio data and the encoded video data according to circumstances, and outputs the result from the stream I / Oex 506 to the outside. The output multiplexed data is transmitted to the base station ex107 or written to the recording medium ex215. It should be noted that data should be temporarily stored in the buffer ex508 so as to be synchronized when multiplexing.

In the above description, the memory ex511 is described as an external configuration of the LSI ex500. However, a configuration included in the LSI ex500 may be used. The number of buffers ex508 is not limited to one, and a plurality of buffers may be provided. The LSI ex500 may be made into one chip or a plurality of chips.

In the above description, the control unit ex510 includes the CPU ex502, the memory controller ex503, the stream controller ex504, the drive frequency control unit ex512, and the like, but the configuration of the control unit ex510 is not limited to this configuration. For example, the signal processing unit ex507 may further include a CPU. By providing a CPU also in the signal processing unit ex507, the processing speed can be further improved. As another example, the CPU ex502 may be configured to include a signal processing unit ex507 or, for example, an audio signal processing unit that is a part of the signal processing unit ex507. In such a case, the control unit ex501 is configured to include a signal processing unit ex507 or a CPU ex502 having a part thereof.

In addition, although it was set as LSI here, it may be called IC, system LSI, super LSI, and ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of progress in semiconductor technology or other derived technology, it is naturally possible to integrate functional blocks using this technology. Biotechnology can be applied.

(Embodiment 19)
When decoding the video data generated by the moving picture encoding method or apparatus shown in the above embodiments, the video data conforming to the conventional standards such as MPEG-2, MPEG4-AVC, and VC-1 is decoded. It is conceivable that the amount of processing increases compared to the case. Therefore, in LSI ex500, it is necessary to set a driving frequency higher than the driving frequency of CPU ex502 when decoding video data compliant with the conventional standard. However, when the drive frequency is increased, there is a problem that power consumption increases.

In order to solve this problem, moving picture decoding devices such as the television ex300 and LSI ex500 are configured to identify which standard the video data conforms to and switch the driving frequency in accordance with the standard. FIG. 69 shows a configuration ex800 in the present embodiment. The drive frequency switching unit ex803 sets the drive frequency high when the video data is generated by the moving image encoding method or apparatus described in the above embodiments. Then, the decoding processing unit ex801 that executes the moving picture decoding method described in each of the above embodiments is instructed to decode the video data. On the other hand, when the video data is video data compliant with the conventional standard, compared to the case where the video data is generated by the moving picture encoding method or apparatus shown in the above embodiments, Set the drive frequency low. Then, it instructs the decoding processing unit ex802 compliant with the conventional standard to decode the video data.

More specifically, the drive frequency switching unit ex803 includes the CPU ex502 and the drive frequency control unit ex512 in FIG. Also, the decoding processing unit ex801 that executes the moving picture decoding method shown in each of the above embodiments and the decoding processing unit ex802 that complies with the conventional standard correspond to the signal processing unit ex507 in FIG. The CPU ex502 identifies which standard the video data conforms to. Then, based on the signal from the CPU ex502, the drive frequency control unit ex512 sets the drive frequency. Further, based on the signal from the CPU ex502, the signal processing unit ex507 decodes the video data. Here, for the identification of the video data, for example, the identification information described in Embodiment B may be used. The identification information is not limited to that described in Embodiment B, and any information that can identify which standard the video data conforms to may be used. For example, it is possible to identify which standard the video data conforms to based on an external signal that identifies whether the video data is used for a television or a disk. In some cases, identification may be performed based on such an external signal. In addition, the selection of the driving frequency in the CPU ex502 may be performed based on, for example, a lookup table in which video data standards and driving frequencies are associated with each other as shown in FIG. The look-up table is stored in the buffer ex508 or the internal memory of the LSI, and the CPU ex502 can select the drive frequency by referring to the look-up table.

FIG. 70 shows steps for executing the method of the present embodiment. First, in step exS200, the signal processing unit ex507 acquires identification information from the multiplexed data. Next, in step exS201, the CPU ex502 identifies whether the video data is generated by the encoding method or apparatus described in each of the above embodiments based on the identification information. When the video data is generated by the encoding method or apparatus shown in the above embodiments, in step exS202, the CPU ex502 sends a signal for setting the drive frequency high to the drive frequency control unit ex512. Then, the drive frequency control unit ex512 sets a high drive frequency. On the other hand, if it indicates that the video data conforms to the conventional standards such as MPEG-2, MPEG4-AVC, and VC-1, in step exS203, the CPU ex502 drives the signal for setting the drive frequency low. This is sent to the frequency control unit ex512. Then, in the drive frequency control unit ex512, the drive frequency is set to be lower than that in the case where the video data is generated by the encoding method or apparatus described in the above embodiments.

Furthermore, the power saving effect can be further enhanced by changing the voltage applied to the LSI ex500 or the device including the LSI ex500 in conjunction with the switching of the driving frequency. For example, when the drive frequency is set low, it is conceivable that the voltage applied to the LSI ex500 or the device including the LSI ex500 is set low as compared with the case where the drive frequency is set high.

In addition, the setting method of the driving frequency may be set to a high driving frequency when the processing amount at the time of decoding is large, and to a low driving frequency when the processing amount at the time of decoding is small. It is not limited to the method. For example, the amount of processing for decoding video data compliant with the MPEG4-AVC standard is larger than the amount of processing for decoding video data generated by the moving picture encoding method or apparatus described in the above embodiments. It is conceivable that the setting of the driving frequency is reversed to that in the case described above.

Furthermore, the method for setting the drive frequency is not limited to the configuration in which the drive frequency is lowered. For example, when the identification information indicates that the video data is generated by the moving image encoding method or apparatus described in the above embodiments, the voltage applied to the LSIex500 or the apparatus including the LSIex500 is set high. However, when it is shown that the video data conforms to the conventional standards such as MPEG-2, MPEG4-AVC, VC-1, etc., it is also possible to set the voltage applied to the LSIex500 or the device including the LSIex500 low. It is done. As another example, when the identification information indicates that the video data is generated by the moving image encoding method or apparatus described in the above embodiments, the driving of the CPU ex502 is stopped. If the video data conforms to the standards such as MPEG-2, MPEG4-AVC, VC-1, etc., the CPU ex502 is temporarily stopped because there is room in processing. Is also possible. Even when the identification information indicates that the video data is generated by the moving image encoding method or apparatus described in each of the above embodiments, if there is a margin for processing, the CPU ex502 is temporarily driven. It can also be stopped. In this case, it is conceivable to set the stop time shorter than in the case where the video data conforms to the conventional standards such as MPEG-2, MPEG4-AVC, and VC-1.

Thus, it is possible to save power by switching the drive frequency according to the standard to which the video data conforms. In addition, when the battery is used to drive the LSI ex500 or the device including the LSI ex500, it is possible to extend the life of the battery with power saving.

(Embodiment 20)
A plurality of video data that conforms to different standards may be input to the above-described devices and systems such as a television and a mobile phone. As described above, the signal processing unit ex507 of the LSI ex500 needs to support a plurality of standards in order to be able to decode even when a plurality of video data complying with different standards is input. However, when the signal processing unit ex507 corresponding to each standard is used individually, there is a problem that the circuit scale of the LSI ex500 increases and the cost increases.

In order to solve this problem, a decoding processing unit for executing the moving picture decoding method shown in each of the above embodiments and a decoding conforming to a standard such as MPEG-2, MPEG4-AVC, or VC-1 The processing unit is partly shared. An example of this configuration is shown as ex900 in FIG. For example, the moving picture decoding method shown in each of the above embodiments and the moving picture decoding method compliant with the MPEG4-AVC standard are processed in processes such as entropy coding, inverse quantization, deblocking filter, and motion compensation. Some contents are common. For the common processing content, the decoding processing unit ex902 corresponding to the MPEG4-AVC standard is shared, and for the other processing content unique to the present invention not corresponding to the MPEG4-AVC standard, the dedicated decoding processing unit ex901 is used. Configuration is conceivable. In particular, since the present invention is characterized by inverse quantization, for example, a dedicated decoding processing unit ex901 is used for inverse quantization, and other entropy coding, deblocking filter, motion compensation, and the like are used. For any or all of the processes, it is conceivable to share the decoding processing unit. Regarding the sharing of the decoding processing unit, regarding the common processing content, the decoding processing unit for executing the moving picture decoding method described in each of the above embodiments is shared, and the processing content specific to the MPEG4-AVC standard As for, a configuration using a dedicated decoding processing unit may be used.

Further, ex1000 in FIG. 72 (b) shows another example in which processing is partially shared. In this example, a dedicated decoding processing unit ex1001 corresponding to processing content unique to the present invention, a dedicated decoding processing unit ex1002 corresponding to processing content specific to other conventional standards, and a moving picture decoding method of the present invention A common decoding processing unit ex1003 corresponding to processing contents common to other conventional video decoding methods is used. Here, the dedicated decoding processing units ex1001 and ex1002 are not necessarily specialized in the processing content specific to the present invention or other conventional standards, and may be capable of executing other general-purpose processing. Also, the configuration of the present embodiment can be implemented by LSI ex500.

As described above, by sharing the decoding processing unit with respect to the processing contents common to the moving picture decoding method of the present invention and the moving picture decoding method of the conventional standard, the circuit scale of the LSI is reduced, and the cost is reduced. It is possible to reduce.

The present invention relates to a moving image encoding method, a moving image encoding device, a moving image decoding method, and a moving image decoding device. Improve efficiency.

101, 3201

Orthogonal transformation unit

102, 3202

Quantization unit

103, 1902, 3203, 4502

Inverse quantization unit

104, 1903, 3204, 4503 Inverse

orthogonal transformation unit

105, 1904, 3205, 4504

Block memory

106, 1905, 3206, 4505

Frame memory

107, 1906, 3207, 4506

Intra prediction unit

108, 1907, 3208, 4507

Inter prediction unit

109, 1908, 3209, 4508 Inter

prediction control unit

110, 3210 Picture

type determination unit

111, 1909, 3211, 4509 Reference picture

list Management unit

112, 1910 Skip mode prediction

direction determination unit

112a, 1910a Skip mode prediction direction

addition determination unit

113, 3213 Variable

length coding unit

1901, 4501 Variable length decoding unit 3212, 4510 Direct mode prediction direction determination unit

Claims

A video encoding method for encoding at least one reference picture index assigned to at least one reference picture different from an encoding target picture including an encoding target block and encoding the encoding target block. And
The same reference for determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same picture when the two or more reference picture indexes are used when the encoding target block is encoded A picture determination step;
A video encoding method comprising: a prediction direction switching step of switching a prediction direction when encoding the block to be encoded in a predetermined encoding mode based on a determination result in the same reference picture determination step.
The predetermined encoding mode is a skip mode;
In the prediction direction switching step,
If the determination result in the same reference picture determination step is true, the prediction direction of the skip mode is set to unidirectional prediction that performs encoding with reference to one reference picture,
The prediction mode in the skip mode is set to bi-prediction in which encoding is performed with reference to at least two reference pictures if the determination result in the same reference picture determination step is false. Video encoding method.
A video encoding method for encoding at least one reference picture index assigned to at least one reference picture different from an encoding target picture including an encoding target block and encoding the encoding target block. And
The same reference for determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same picture when the two or more reference picture indexes are used when the encoding target block is encoded A picture determination step;
A prediction direction adding step of adding a prediction direction when encoding the block to be encoded in a predetermined encoding mode based on a determination result in the same reference picture determination step.
The predetermined encoding mode is a skip mode;
The prediction direction adding step includes
If the determination result in the same reference picture determination step is false, the prediction direction of the skip mode is set to bi-prediction that performs encoding with reference to at least two reference pictures,
If the determination result in the same reference picture determination step is true, in addition to the bi-directional prediction, uni-directional prediction that performs encoding with reference to one reference picture is added to the prediction direction of the skip mode. The moving picture coding method according to claim 3, wherein the prediction direction used for coding the block to be coded is finally added to the bitstream.
A video encoding method for encoding at least one reference picture index assigned to at least one reference picture different from an encoding target picture including an encoding target block and encoding the encoding target block. And
When using the two or more reference picture indexes when encoding the encoding target block,
Adding a prediction direction to the header information when the encoding target block is encoded in a predetermined encoding mode;
Encoding the block to be encoded in a predetermined encoding mode based on the prediction direction.
The predetermined encoding mode is a skip mode;
When the prediction direction added to the header information is unidirectional prediction, the encoding target block is encoded with reference to one reference picture,
The moving picture encoding method according to claim 5, wherein when the prediction direction added to the header information is bi-directional prediction, the encoding target block is encoded with reference to at least two reference pictures.
A video encoding method for encoding at least one reference picture index assigned to at least one reference picture different from an encoding target picture including an encoding target block and encoding the encoding target block. And
Whether or not to add a prediction direction when encoding the encoding target block in a predetermined encoding mode when the two or more reference picture indexes are used when encoding the encoding target block Adding a flag representing the header information;
And a step of encoding the block to be encoded in a predetermined encoding mode based on the flag.
The predetermined encoding mode is a skip mode;
When the flag added to the header information is off, the encoding target block is encoded using bi-directional prediction that refers to at least two or more reference pictures.
When the flag added to the header information is on, in addition to the bi-directional prediction, uni-directional prediction is performed by referring to one reference picture and finally encoding of the block to be encoded The moving image encoding method according to claim 7, wherein the prediction direction used for conversion is added to a bitstream.
The moving picture coding method according to any one of claims 1 to 8, wherein in the same reference picture determination step, determination is performed using a display order or an encoding order of the reference pictures to which the reference picture index is assigned.
A moving picture decoding method in which at least two or more reference picture indexes are assigned to at least one or more reference pictures different from a decoding target picture including a decoding target block, and the decoding target block is decoded. And
The same reference for determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same picture when using the two or more reference picture indexes when decoding the decoding target block A picture determination step;
A video decoding method comprising: a prediction direction switching step of switching a prediction direction when decoding the block to be decoded in a predetermined decoding mode based on a determination result in the same reference picture determination step.
The predetermined decoding mode is a skip mode;
In the prediction direction switching step,
If the determination result in the same reference picture determination step is true, the prediction direction of the skip mode is set to one-way prediction in which decoding is performed with reference to one reference picture,
11. The prediction direction of the skip mode is set to bi-prediction in which decoding is performed with reference to at least two reference pictures if the determination result in the same reference picture determination step is false. A video decoding method.
A moving picture decoding method in which at least two or more reference picture indexes are assigned to at least one or more reference pictures different from a decoding target picture including a decoding target block, and the decoding target block is decoded. And
The same reference for determining whether or not the reference pictures indicated by the two or more reference picture indexes are the same picture when using the two or more reference picture indexes when decoding the decoding target block A picture determination step;
Decoding a prediction direction when decoding the decoding target block in a predetermined decoding mode based on a determination result in the same reference picture determining step.
The predetermined decoding mode is a skip mode;
If the determination result in the same reference picture determination step is false, the prediction direction of the skip mode is set to bi-prediction that performs decoding with reference to at least two reference pictures,
13. If the determination result in the same reference picture determination step is true, the prediction direction in the skip mode is decoded from a bitstream, and the decoding target block is decoded based on the decoded prediction direction. The moving picture decoding method as described.
A moving picture decoding method in which at least two or more reference picture indexes are assigned to at least one or more reference pictures different from a decoding target picture including a decoding target block, and the decoding target block is decoded. And
When the two or more reference picture indexes are used when decoding the decoding target block,
Decoding the prediction direction when decoding the decoding target block in a predetermined decoding mode from header information;
Decoding the block to be decoded in a predetermined decoding mode based on the decoded prediction direction.
The predetermined decoding mode is a skip mode;
When the prediction direction decoded from the header information is unidirectional prediction, the decoding target block is decoded with reference to one reference picture,
The moving picture decoding method according to claim 14, wherein when the prediction direction decoded from the header information is bi-directional prediction, the decoding target block is decoded with reference to at least two reference pictures.
A moving picture decoding method in which at least two or more reference picture indexes are assigned to at least one or more reference pictures different from a decoding target picture including a decoding target block, and the decoding target block is decoded. And
When using the two or more reference picture indexes when decoding the decoding target block,
Decoding a flag indicating whether or not a prediction direction is added when decoding the decoding target block in a predetermined decoding mode from header information;
Decoding the block to be decoded in a predetermined decoding mode based on the flag.
The predetermined decoding mode is a skip mode;
When the flag decoded from the header is OFF, the decoding target block is decoded using bi-directional prediction that references at least two reference pictures.
The video decoding according to claim 16, wherein when the flag decoded from the header information is on, the prediction direction is decoded from a bitstream, and the decoding target block is decoded based on the decoded prediction direction. Method.
The moving picture decoding method according to any one of claims 10 to 17, wherein the same reference picture determination step is determined using a display order or an encoding order of the reference pictures to which the reference picture index is assigned.