WO2013001795A1

WO2013001795A1 - Image encoding method, image decoding method, image encoding device, and image decoding device

Info

Publication number: WO2013001795A1
Application number: PCT/JP2012/004138
Authority: WO
Inventors: 寿郎笹井; 西　孝啓; 陽司柴原; 敏康杉尾; 京子谷川; 徹松延
Original assignee: パナソニック株式会社
Priority date: 2011-06-29
Filing date: 2012-06-27
Publication date: 2013-01-03

Abstract

　An image encoding method comprising the following steps: a motion detection step (S11) in which the motion vector of a block to be encoded relative to a reference picture is derived; a motion prediction step (S12) in which the motion vector of the block to be encoded is predicted on the basis of previously encoded blocks; and an encoding step (S13) in which the difference vector between the derived motion vector and the predicted motion vector is encoded. The encoding step (S13) comprises: a binarization step (S14) in which the difference vector is binarized; a context calculation step (S15) in which a context index is calculated on the basis of at least the reference picture; and an arithmetic encoding step (S16) in which a symbol occurrence probability corresponding to the context index is used to arithmetically encode the binarized difference vector.

Description

Image encoding method, image decoding method, image encoding device, and image decoding device

The present invention relates to an image encoding method and an image encoding apparatus for encoding a motion vector of an encoding target block and an image decoding method for decoding an encoded motion vector in order to encode an image for each block. And an image decoding apparatus.

Generally, when encoding a moving image, the image encoding device compresses the information amount of the moving image by reducing redundancy in the spatial direction and the time direction of the moving image. At this time, intra prediction (also referred to as intra prediction or intra picture prediction) is used as a method of reducing redundancy in the spatial direction. In addition, as a method for reducing temporal redundancy, inter prediction (also referred to as inter-frame prediction or inter-picture prediction) is used (see, for example, Non-Patent Document 1).

For example, when encoding an encoding target picture by inter prediction, the image encoding apparatus uses a coded picture in front of or behind the encoding target picture in the display order as a reference picture. Then, the image encoding device derives a motion vector of each block by performing motion detection of the encoding target picture with respect to the reference picture. The image encoding device generates predicted image data by performing motion compensation using the motion vector derived as described above. Then, the image encoding device encodes a difference between the generated predicted image data and image data of the encoding target picture. Furthermore, the image encoding device encodes information for specifying a motion vector used for motion compensation.

However, it is required to further improve the encoding efficiency with respect to image encoding and decoding.

Therefore, an object of one embodiment of the present invention is to provide an image encoding method, an image encoding device, an image decoding method, and an image decoding device that can improve encoding efficiency.

An image encoding method according to an aspect of the present invention is an image encoding method for encoding a motion vector of an encoding target block in order to encode a plurality of pictures for each block, and performs motion detection. The motion detection step for deriving the motion vector of the encoding target block with respect to the reference picture, the motion prediction step for predicting the motion vector of the encoding target block based on the motion vector of the encoded block, and An encoding step of encoding a difference vector between the motion vector and the predicted motion vector, and the encoding step includes a binarization step of binarizing the difference vector, and at least the reference picture A context calculation step for calculating a context index of the difference vector based on Using symbols occurrence probability corresponding to the context indexes, including an arithmetic coding step of arithmetic coding the binarized said difference vector.

These general or specific aspects may be realized by a recording medium such as an apparatus, a system, a method, an integrated circuit, a computer program, or a computer-readable CD-ROM (Compact Disc Read Only Memory). The present invention may be realized by any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a recording medium.

According to one embodiment of the present invention, encoding efficiency can be improved.

FIG. 1 is a block diagram illustrating a functional configuration of the image encoding device according to the first embodiment. FIG. 2 is a flowchart showing the processing operation of the image coding apparatus according to Embodiment 1. FIG. 3 is a diagram for explaining an example of a context index calculation method according to the first embodiment. FIG. 4 is a diagram for explaining another example of the context index calculation method according to the first embodiment. FIG. 5 is a diagram for explaining another example of the context index calculation method according to the first embodiment. FIG. 6 is a block diagram illustrating a functional configuration of the image decoding apparatus according to Embodiment 1. FIG. 7 is a flowchart showing the processing operation of the image decoding apparatus according to Embodiment 1. FIG. 8 is a block diagram illustrating a functional configuration of the image encoding device according to the second embodiment. FIG. 9 is a block diagram illustrating a functional configuration of the image decoding apparatus according to the second embodiment. FIG. 10 is a block diagram of an image coding apparatus according to Embodiment 3. FIG. 11 is a flowchart showing the operation of the image coding apparatus according to Embodiment 3. FIG. 12 is a diagram for explaining an example of a prediction vector calculation method. FIG. 13 is a diagram illustrating an example of the data structure of the header portion of the encoded block data. FIG. 14 is a diagram illustrating an example of a data structure of an encoded stream. FIG. 15 is a diagram illustrating an example of a reference relationship in 3D video. FIG. 16 is a block diagram of an image decoding apparatus according to Embodiment 3. FIG. 17 is a flowchart showing an operation of the image decoding apparatus according to the third embodiment. FIG. 18 is an overall configuration diagram of a content supply system that implements a content distribution service. FIG. 19 is an overall configuration diagram of a digital broadcasting system. FIG. 20 is a block diagram illustrating a configuration example of a television. FIG. 21 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. 22 is a diagram illustrating a structure example of a recording medium that is an optical disk. FIG. 23A is a diagram illustrating an example of a mobile phone. FIG. 23B is a block diagram illustrating a configuration example of a mobile phone. FIG. 24 is a diagram showing a structure of multiplexed data. FIG. 25 is a diagram schematically showing how each stream is multiplexed in the multiplexed data. FIG. 26 is a diagram showing in more detail how the video stream is stored in the PES packet sequence. FIG. 27 is a diagram illustrating the structure of TS packets and source packets in multiplexed data. FIG. 28 shows the data structure of the PMT. FIG. 29 is a diagram showing an internal configuration of multiplexed data information. FIG. 30 shows the internal structure of stream attribute information. FIG. 31 is a diagram showing steps for identifying video data. FIG. 32 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. 33 is a diagram illustrating a configuration for switching the driving frequency. FIG. 34 is a diagram illustrating steps for identifying video data and switching between driving frequencies. FIG. 35 is a diagram illustrating an example of a look-up table in which video data standards are associated with drive frequencies. FIG. 36A is a diagram illustrating an example of a configuration for sharing a module of a signal processing unit. FIG. 36B is a diagram illustrating another example of a configuration for sharing a module of a signal processing unit. FIG. 37 is a diagram illustrating an example of a reference picture list. FIG. 38 is a diagram for explaining the time direct mode.

(Knowledge that became the basis of the present invention)
H., which is an already standardized video encoding system. In H.264 (Non-Patent Document 1), three types of pictures, i.e., I-picture, P-picture, and B-picture, are used to compress the amount of information.

In an I picture, only intra prediction is performed out of inter prediction and intra prediction. In the P picture, inter prediction is performed with reference to one already encoded picture that is in front of or behind the P picture in the display order. That is, in the P picture, inter prediction is performed by unidirectional prediction.

In the B picture, inter prediction is performed with reference to two already encoded pictures that are in front of or behind the B picture in the display order. That is, in the B picture, inter prediction is performed by bidirectional prediction.

Note that the expression bi-directional prediction may mean only predicting image data by referring to one reference picture from both the front and rear. In addition, the expression bi-directional prediction may include predicting image data with reference to two reference pictures from either the front or the rear. In the latter case, bidirectional prediction may be expressed as bi-prediction.

The image encoding device generates a reference picture list for specifying a reference picture during inter prediction. In the reference picture list, the image coding apparatus assigns a reference picture index to a reference picture that is referred to in inter prediction. Note that the image coding apparatus refers to two pictures when coding a B picture. Therefore, the image coding apparatus holds two reference picture lists L0 and L1.

FIG. 37 is a diagram showing an example of a reference picture list. The reference picture lists L0 and L1 shown in FIG. 37 are examples of two reference picture lists in bi-directional prediction.

The image coding apparatus assigns a reference picture index of “0” to the second reference picture in the display order in the reference picture list L0. Also, the image coding apparatus assigns a reference picture index “1” to the first reference picture in the display order. Then, the image coding apparatus assigns a reference picture index “2” to the 0th reference picture in the display order. That is, the image coding apparatus assigns the reference picture index to the coding target picture in the order close to the display order.

On the other hand, the image coding apparatus assigns a reference picture index of “0” to the second reference picture in the display order in the reference picture list L1. Also, the image coding apparatus assigns a reference picture index “2” to the first reference picture in the display order. Then, the image coding apparatus assigns a reference picture index of “1” to the 0th reference picture in the display order.

Thus, the image coding apparatus may assign different reference picture indexes for each reference picture list to the same reference picture. Further, the image coding apparatus may assign the same reference picture index to the same reference picture.

Also, the reference picture list L0 may correspond to the first prediction direction, and the reference picture list L1 may correspond to the second prediction direction. Here, the first prediction direction and the second prediction direction are either one of the front side and the rear side, and are different from each other. Typically, the reference picture list L0 is used to specify a reference picture that is ahead of the current picture in the display order. The reference picture list L1 is used to specify a reference picture that is behind the current picture in the display order.

In inter prediction, there are a plurality of prediction modes for predicting image data of a block to be encoded. The prediction mode may indicate not only inter prediction or intra prediction, but also a detailed mode included in the inter prediction or intra prediction. The image encoding device selects a prediction mode to be applied to prediction of image data of the block to be encoded from among a plurality of prediction modes.

For example, the image coding apparatus selects, as the prediction mode, bi-directional prediction that generates a predicted image with reference to two pictures that are in front of or behind the current picture in the display order. In addition, for example, the image encoding apparatus selects, as a prediction mode, unidirectional prediction that generates a predicted image with reference to one picture that is in front of or behind the current picture in display order. For example, the image encoding apparatus selects a prediction mode called a temporal direct mode.

FIG. 38 is a diagram for explaining the time direct mode. Specifically, FIG. 38 illustrates a case where the block to be encoded of the picture B2 is encoded using a motion vector obtained in the temporal direct mode.

In this case, the image coding apparatus uses the motion vector vb used when coding the co-located block. The co-located block is included in the picture P3 which is a reference picture behind the picture B2 in the display order. The position of the co-located block matches the position of the encoding target block. The motion vector vb of the co-located block points to the picture P1.

The image coding apparatus uses two motion vectors va1 and va2 parallel to the motion vector vb to perform coding from both the front reference picture P1 and the rear reference picture P3. Two reference blocks corresponding to the target block are specified. Then, the image encoding device encodes the encoding target block by bidirectional prediction.

That is, the image coding apparatus uses the motion vector va1 for the picture P1 and uses the motion vector va2 for the picture P3. Then, the image encoding device specifies two reference blocks and encodes the encoding target block by bidirectional prediction.

The two motion vectors va1 and va2 are parallel to the motion vector vb. The image encoding device acquires two motion vectors va1 and va2 by expanding and contracting the motion vector vb according to the ratio of the temporal distance between the three pictures P1, B2, and P3.

Also, it has been studied to use a prediction motion vector designation mode when coding a motion vector of a coding target block in a B picture or a P picture (Non-Patent Document 2). An image coding apparatus that uses a predicted motion vector designation mode generates a plurality of motion vector predictor candidates based on a coded block adjacent to a coding target block. Then, the image encoding device selects a motion vector predictor from among the plurality of generated candidates.

The image encoding device encodes the motion vector of the encoding target block using the selected prediction motion vector. Specifically, the difference vector between the motion vector of the encoding target block and the selected prediction motion vector is variable-length encoded.

Also, the image coding apparatus adds the index of the selected motion vector predictor (also referred to as a motion vector predictor index) to the encoded bitstream. Thereby, the image decoding apparatus can select the same prediction motion vector as the prediction motion vector selected at the time of encoding at the time of decoding.

Next, variable length coding such as the difference between the predicted image data and the image data of the encoding target picture and the difference vector between the predicted motion vector and the motion vector will be described. H. In H.264, as one of the variable length coding methods, there is context adaptive arithmetic coding (CABAC: Context Adaptive Binary Arithmetic Coding). This CABAC will be described below.

In CABAC, the image coding apparatus holds a plurality of symbol occurrence probabilities, which are binary symbol occurrence probabilities, in association with context indexes. This symbol occurrence probability is initialized at the head of the slice.

First, the image coding apparatus performs binarization (binarization) of a multi-value signal such as a difference between predicted image data and image data of an encoding target picture and a difference vector between a predicted motion vector and a motion vector. A binary signal is generated.

Subsequently, the image encoding device calculates a context index based on the peripheral information of the encoding target block and the binary signal. The context index is information for selecting one symbol occurrence probability from a plurality of held symbol occurrence probabilities. The image coding apparatus arithmetically codes the binary signal using the symbol occurrence probability corresponding to the context index calculated in this way. Then, the image coding apparatus updates the symbol occurrence probability corresponding to the calculated context index based on the binary symbol included in the binary signal.

As described above, the image coding apparatus arithmetically codes a binary signal using the peripheral information of the block to be coded and the symbol occurrence probability updated for each context index based on the binary signal. As a result, the image encoding apparatus can arithmetically encode a binary signal using a symbol occurrence probability suitable for an encoding target, and can improve encoding efficiency.

However, conventionally, when a difference vector between a predicted motion vector and a motion vector is arithmetically encoded, the context index is calculated without considering the characteristics of the difference vector. That is, difference vectors having different symbol occurrence probabilities are also arithmetically encoded using the same context index. As a result, it is difficult to perform arithmetic coding using a symbol occurrence probability that is suitable for a difference vector to be coded, and there is a problem that coding efficiency is lowered.

Thus, an image encoding method according to an aspect of the present invention is an image encoding method for encoding a motion vector of an encoding target block in order to encode a plurality of pictures for each block, and performs motion detection. A motion detection step for deriving a motion vector of the block to be encoded with respect to the reference picture, a motion prediction step for predicting a motion vector of the block to be encoded based on the motion vector of the encoded block, and a derivation An encoding step for encoding a difference vector between the predicted motion vector and the predicted motion vector, wherein the encoding step includes a binarization step for binarizing the difference vector, and at least the reference A context calculation step for calculating a context index of the difference vector based on a picture. When, using the calculated symbol occurrence probability corresponding to the context index, including an arithmetic coding step of arithmetic coding the binarized said difference vector.

According to this configuration, the context index of the difference vector can be calculated based on the reference picture. That is, the context index can be switched according to the characteristic of the difference vector. As a result, the symbol generation probability learning efficiency can be improved, and the encoding efficiency of arithmetic encoding can be improved.

For example, in the context calculating step, the context index may be calculated so that the context index changes depending on whether the reference picture is an inter-view reference picture or not.

Generally, a motion vector for an inter-view reference picture has a very small component (vertical component) in a direction orthogonal to the direction of parallax. That is, the motion vector for the inter-view reference picture and the motion vector for the temporal reference picture (in-view reference picture) have different characteristics. Therefore, by calculating the context index of the difference vector so that the context index differs depending on whether the reference picture is an inter-view reference picture, the learning efficiency of the symbol occurrence probability can be improved, and arithmetic coding is performed. The encoding efficiency can be improved.

Also, for example, in the context calculation step, the context index is changed so that only a vertical component of a vertical component and a horizontal component of the difference vector changes depending on whether the reference picture is an inter-view reference picture. May be calculated.

According to this configuration, it is possible to calculate the context index based on the reference picture only for the vertical component that is a component in a direction in which the characteristics are greatly different among the components in the two directions of the motion vector. Accordingly, since the types of context indexes can be further reduced, the memory area for holding the symbol occurrence probability can be further reduced.

Further, for example, in the context calculating step, the context index may be calculated so that the context index changes for each reference picture list in which the reference picture is designated.

Generally, in one of the two reference picture lists, a temporally forward picture is often designated as a reference picture, and on the other hand, a temporally backward picture is often designated as a reference picture. Depending on whether the reference picture is forward or backward in time, the motion vector characteristics are also different. Therefore, by calculating the context index of the difference vector so that the context index is different for each reference picture list, the learning efficiency of the symbol occurrence probability can be improved, and the coding efficiency of arithmetic coding can be improved. It becomes.

For example, in the context calculation step, the context index may be calculated so that the context index changes for each reference picture.

Generally, when the reference picture is different, the characteristics (size, direction, etc.) of the motion vector and the difference vector obtained from the motion vector are often different. If the characteristics of the difference vector are different, the occurrence probability of the binary symbol included in the binary signal of the difference vector is also different. Therefore, by calculating the context index of the difference vector so that the context index is different for each reference picture, the learning efficiency of the symbol occurrence probability can be improved, and the coding efficiency of arithmetic coding can be improved. Become.

For example, the encoding step may further include an update step of updating a symbol occurrence probability corresponding to the calculated context index based on a binary symbol included in the binarized difference vector. .

According to this configuration, the symbol occurrence probability can be updated, and the coding efficiency of arithmetic coding can be improved.

An image decoding method according to an aspect of the present invention is an image decoding method for restoring a motion vector of a decoding target block in order to decode a plurality of pictures encoded for each block. A decoding step for decoding a difference vector, a motion prediction step for predicting a motion vector of a block to be decoded based on a motion vector of a decoded block, and the decoded difference vector and the predicted motion vector are added. A restoring step of restoring a motion vector of the decoding target block with respect to a reference picture, wherein the decoding step calculates a context index of the encoded difference vector based on at least the reference picture Step and the calculated context index Using a corresponding symbol occurrence probability, comprising an arithmetic decoding step of arithmetic decoding the difference vector encoded, an inverse binarization step of debinarization the difference vectors arithmetic decoding.

According to this configuration, the context index of the difference vector can be calculated based on the reference picture. That is, the context index can be switched according to the characteristic of the difference vector. As a result, it is possible to improve the learning efficiency of the symbol occurrence probability and appropriately decode a picture encoded with high encoding efficiency.

Generally, a motion vector for an inter-view reference picture has a very small component (vertical component) in a direction orthogonal to the direction of parallax. That is, the motion vector for the inter-view reference picture and the motion vector for the temporal reference picture (in-view reference picture) have different characteristics. Therefore, by calculating the context index of the difference vector so that the context index varies depending on whether or not the reference picture is an inter-view reference picture, it is possible to improve the learning efficiency of the symbol occurrence probability and achieve high coding It is possible to appropriately decode a picture encoded with efficiency.

Further, for example, in the context calculation step, the context index is changed so that only a vertical component of a vertical component and a horizontal component of the difference vector changes depending on whether the reference picture is an inter-view reference picture or not. May be calculated.

Generally, in one of the two reference picture lists, a temporally forward picture is often designated as a reference picture, and on the other hand, a temporally backward picture is often designated as a reference picture. Depending on whether the reference picture is forward or backward in time, the motion vector characteristics are also different. Therefore, by calculating the context index of the difference vector so that the context index is different for each reference picture list, the learning efficiency of the symbol occurrence probability can be improved, and the picture encoded with high encoding efficiency can be appropriately selected. Decoding is possible.

Generally, when the reference picture is different, the characteristics (size, direction, etc.) of the motion vector and the difference vector obtained from the motion vector are often different. If the characteristics of the difference vector are different, the occurrence probability of the binary symbol included in the binary signal of the difference vector is also different. Therefore, by calculating the context index of the difference vector so that the context index is different for each reference picture, the learning efficiency of the symbol occurrence probability can be improved, and the picture encoded with high encoding efficiency is appropriately decoded. It becomes possible to do.

Further, for example, the decoding step may further include an update step of updating a symbol occurrence probability corresponding to the calculated context index based on a binary symbol included in the arithmetically decoded difference vector.

According to this configuration, the symbol occurrence probability can be updated, and a picture encoded with high encoding efficiency can be appropriately decoded.

Note that these general or specific aspects may be realized by a recording medium such as a device, a system, an integrated circuit, a computer program, or a computer-readable CD-ROM. The device, system, integrated circuit, computer program And any combination of recording media.

Hereinafter, an image decoding device and an image encoding device according to an aspect of the present invention will be specifically described with reference to the drawings.

Note that each of the embodiments described below shows a 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. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a functional configuration of an image encoding device 10 according to the first embodiment. The image encoding apparatus 10 according to the present embodiment encodes a motion vector of an encoding target block in order to encode a plurality of pictures for each block. As illustrated in FIG. 1, the image encoding device 10 includes a motion detection unit 11, a motion prediction unit 12, and an encoding unit 13.

The motion detection unit 11 derives a motion vector of the encoding target block with respect to the reference picture by performing motion detection. For example, the motion detection unit 11 derives a motion vector as follows.

First, the motion detection unit 11 calculates the difference between the image data of the encoding target block and the image data of each of a plurality of blocks in the reference picture. Then, the motion detection unit 11 determines a block having the smallest difference as a reference block among a plurality of blocks in the reference picture. Then, the motion detection unit 11 derives a motion vector from the positional relationship between the encoding target block and the reference block.

The motion prediction unit 12 predicts the motion vector of the encoding target block based on the motion vector of the encoded block. Hereinafter, the motion vector of the encoding target block predicted by the motion prediction unit 12 is referred to as a predicted motion vector.

For example, the motion prediction unit 12 predicts a motion vector of one of the encoded blocks adjacent to the encoding target block as a predicted motion vector. Further, for example, the motion prediction unit 12 may predict the median value or the average value of the motion vectors of the encoded blocks spatially adjacent to the encoding target block as the predicted motion vector. For example, the motion prediction unit 12 may predict the motion vector of the encoding target block in the temporal direct mode. In addition, the motion prediction unit 12 may determine, for example, a motion vector derived by a predetermined method as a predicted motion vector.

The encoding unit 13 encodes a difference vector between the motion vector derived by the motion detection unit 11 and the motion vector predicted by the motion prediction unit 12. That is, the encoding unit 13 generates an encoded difference vector. The encoding unit 13 includes a binarization unit 14, a context control unit 15, an arithmetic encoding unit 16, and a symbol occurrence probability storage unit 17.

The binarization unit 14 binarizes the difference vector. That is, the binarization unit 14 converts the multilevel signal indicating the difference vector into a binary signal.

The context control unit 15 calculates a context index of the difference vector based on at least the reference picture. That is, the context control unit 15 calculates the context index of the difference vector so that the context index changes depending on the reference picture referenced in the prediction of the current block.

The context index is information for specifying the symbol occurrence probability necessary for arithmetically encoding the encoding target. That is, the context index is information for selecting one symbol occurrence probability from a plurality of symbol occurrence probabilities stored in the symbol occurrence probability storage unit 17. Details of this context index calculation method will be described later.

Note that the context control unit 15 may calculate a context index based on syntax or coding conditions of neighboring blocks in addition to the reference picture.

Further, the context control unit 15 reads the symbol occurrence probability corresponding to the calculated context index from the symbol occurrence probability storage unit 17. Then, the context control unit 15 outputs the read symbol occurrence probability to the arithmetic coding unit 16.

The context control unit 15 is a symbol occurrence probability stored in the symbol occurrence probability storage unit 17 based on the binary symbol included in the binarized difference vector, and is calculated by the context control unit 15. The symbol occurrence probability corresponding to the given context index is updated.

The arithmetic encoding unit 16 arithmetically encodes the binarized difference vector using the symbol occurrence probability corresponding to the context index calculated by the context control unit 15. That is, the arithmetic encoding unit 16 generates an encoded difference vector by arithmetically encoding the binarized difference vector using the symbol occurrence probability output from the context control unit 15.

The symbol occurrence probability storage unit 17 stores a plurality of symbol occurrence probabilities in association with a plurality of context indexes. The symbol occurrence probability is the occurrence probability of a binary symbol. Specifically, the symbol occurrence probability is represented by, for example, a dominant symbol and a probability state number. A dominant symbol is a binary symbol having a higher probability of occurrence of two binary symbols. The probability state number is information for specifying the occurrence probability of the dominant symbol and the inferior symbol.

Next, the processing operation of the image coding apparatus 10 configured as described above will be described.

FIG. 2 is a flowchart showing the processing operation of the image coding apparatus 10 according to the first embodiment. The process flow described below is repeated for each encoding target block.

First, the motion detection unit 11 derives a motion vector of the encoding target block (S11). Subsequently, the motion prediction unit 12 predicts the motion vector of the encoding target block based on the motion vector of the encoded block (S12).

Next, the encoding unit 13 encodes a difference vector between the motion vector derived in step S11 and the motion vector predicted in step S12 (S13). This step S13 includes the following steps S14 to S17.

The binarization unit 14 binarizes the difference vector of the encoding target block (S14). The context control unit 15 calculates a context index of the difference vector based on at least the reference picture (S15). The arithmetic encoding unit 16 arithmetically encodes the difference vector binarized in step S14 using the symbol occurrence probability corresponding to the context index calculated in step S15 (S16). The context control unit 15 updates the symbol occurrence probability corresponding to the calculated context index based on the binary symbol included in the binarized difference vector (S17).

Here, a specific example of the context index calculation method in step S15 will be described.

FIG. 3 is a diagram for explaining an example of a context index calculation method according to the first embodiment. FIG. 3 shows a plurality of pictures B0 to B4 in the display order.

Motion vectors MvL0_1, MvL0_2, and MvL0_3 are motion vectors used for prediction of the first, second, and third blocks. The reference picture index RefL0_1 is a reference picture index specified in the reference picture list L0 when the first and second blocks are predicted. Further, the reference picture index RefL0_2 is a reference picture index specified by the reference picture list L0 when the third block is encoded.

In the example of FIG. 3, the context control unit 15 calculates the context index so that the context index changes for each reference picture.

That is, the context control unit 15 calculates the context index of the difference vector so that the context indexes of the difference vectors of the first and third blocks having different reference pictures are different from each other. Specifically, for example, the context control unit 15 determines the contexts of the difference vectors so that the context index of the difference vector obtained from the motion vector MvL0_1 and the context index of the difference vector obtained from the motion vector MvL0_3 are different from each other. Calculate the index.

Generally, when the reference picture is different, the characteristics (size, direction, etc.) of the motion vector and the difference vector obtained from the motion vector are often different. If the characteristics of the difference vector are different, the occurrence probability of the binary symbol included in the binary signal of the difference vector is also different. Therefore, by calculating the context index of the difference vector so that the context index changes for each reference picture as in the example of FIG. 3, the learning efficiency of the symbol occurrence probability can be improved, and the coding efficiency of arithmetic coding Can be improved.

Next, another specific example of the context index calculation method will be described with reference to FIG.

FIG. 4 is a diagram for explaining another example of the context index calculation method according to the first embodiment. FIG. 4 shows a plurality of pictures B0 to B4 in the display order.

The motion vectors MvL0_1 and MvL1_1 are motion vectors used for prediction (bidirectional prediction) of the first block. The motion vectors MvL0_2 and MvL1_2 are motion vectors used for the prediction (bidirectional prediction) of the second block.

The reference picture indexes RefL0_1 and RefL0_2 are reference picture indexes specified by the reference picture list L0 when the first and second blocks are predicted. The reference picture indexes RefL1_1 and RefL1_2 are reference picture indexes specified in the reference picture list L1 when the first and second blocks are predicted.

In the example of FIG. 4, the context control unit 15 calculates the context index so that the context index changes for each reference picture list in which the reference picture is specified.

That is, the context control unit 15 calculates the context indexes of the difference vectors obtained from the motion vectors corresponding to each of the reference picture lists L0 and L1, so that they are different from each other. Specifically, the context control unit 15, for example, a difference vector context index obtained from the motion vector MvL0_1 (reference picture list L0) and a difference vector context index obtained from the motion vector MvL1_1 (reference picture list L1) The context indices of those difference vectors are calculated so that are different from each other.

In general, in one of the reference picture lists L0 and L1, a temporally forward picture is often designated as a reference picture, and on the other hand, a temporally backward picture is often designated as a reference picture. . Depending on whether the reference picture is forward or backward in time, the motion vector characteristics are also different. Therefore, by calculating the context index of the difference vector so that the context index changes for each reference picture list as in the example of FIG. 4, the learning efficiency of the symbol occurrence probability can be improved, and the coding of arithmetic coding is performed. Efficiency can be improved.

Also, the types of context index can be reduced compared to the case where the context index is different for each reference picture as in the example of FIG. Therefore, in the example of FIG. 4, the memory area for the symbol occurrence probability held in association with the context index can be reduced as compared with the example of FIG. Furthermore, in the example of FIG. 4, it is possible to suppress a decrease in learning efficiency due to the subdivision of the context index.

It should be noted that the context index changes between the case where only one of the reference picture lists L0 and L1 is used and the case where both the reference picture lists L0 and L1 are used. A context index may be calculated. Specifically, when only one of the reference picture lists L0 and L1 is used (for example, the first block in FIG. 3), the context index of the difference vector obtained from the motion vector MvL0_1 (reference picture list L0) and the reference picture When both lists L0 and L1 are used (for example, the first block in FIG. 4), the context index of the difference vector obtained from each of motion vector MvL0_1 (reference picture list L0) and motion vector MvL1_1 (reference picture list L1) The context indices of those difference vectors may be calculated such that.

Even in such a case, the types of context index can be reduced. In addition, it is possible to suppress a decrease in learning efficiency caused by subdividing the context index.

FIG. 5 is a diagram for explaining another example of the context index calculation method according to the first embodiment. FIG. 5 shows a plurality of pictures encoded by MVC (Multiview Video Coding). Each of the two views of the base view and the non-base view is composed of a plurality of pictures.

In MVC, a non-base view picture can be encoded by referring to a base view picture. When a non-base view picture is predicted with reference to a base view picture, the display order of the reference picture matches the display order of the encoding target picture.

FIG. 5 shows a plurality of pictures B00 to B04 in the base view and a plurality of pictures B10 to B14 in the non-base view in the display order.

Motion vectors MvL0_1, MvL0_2 and MvL0_3 are motion vectors used for prediction of the first, second and third blocks. The reference picture indexes RefL0_0, RefL0_1, and RefL0_2 are reference picture indexes specified in the reference picture list L0 when predicting the first, second, and third blocks.

In the example of FIG. 5, the context control unit 15 calculates the context index so that the context index changes depending on whether or not the reference picture is an inter-view reference picture. The inter-view reference picture is a picture included in the base view that is referred to in prediction of a picture included in the non-base view.

That is, the context control unit 15 includes the context index of the difference vector of the first block whose reference picture is the inter-view reference picture, and the context of the difference vector of the second and third blocks whose reference picture is not the inter-view reference picture. The context index of the difference vector is calculated so that the indexes are different from each other. Specifically, for example, the context control unit 15 determines the contexts of the difference vectors so that the context index of the difference vector obtained from the motion vector MvL0_1 is different from the context index of the difference vector obtained from the motion vector MvL0_2. Calculate the index.

Generally, a motion vector for an inter-view reference picture has a very small component (vertical component) in a direction orthogonal to the direction of parallax. That is, the motion vector for the inter-view reference picture and the motion vector for the temporal reference picture (in-view reference picture) have different characteristics. Accordingly, by calculating the context index of the difference vector so that the context index changes depending on whether or not the reference picture is an inter-view reference picture as in the example of FIG. 5, the symbol generation probability learning efficiency is improved. It is possible to improve the coding efficiency of arithmetic coding.

Further, in the example of FIG. 5, since the types of context indexes can be reduced compared to the example of FIG. 3, the memory area for holding the symbol occurrence probability can also be reduced. Furthermore, it is possible to suppress a decrease in learning efficiency due to the subdivision of the context index.

Note that the context control unit 15 calculates the context index so that only the vertical component of the vertical component and horizontal component of the difference vector changes depending on whether the reference picture is an inter-view reference picture or not. Is preferred. Thereby, the image coding apparatus 10 can calculate the context index based on the reference picture only for the vertical component which is a component in a direction in which the characteristics are greatly different from the components in the two directions of the motion vector. Accordingly, since the types of context indexes can be further reduced, the memory area for holding the symbol occurrence probability can be further reduced.

As described above, according to the image coding apparatus 10 according to the present embodiment, the context index of the difference vector can be calculated based on the reference picture. That is, the image encoding device 10 can switch the context index according to the characteristic of the difference vector. As a result, the image encoding device 10 can improve the learning efficiency of the symbol occurrence probability, and can improve the encoding efficiency of the arithmetic encoding of the difference vector.

Next, the image decoding device 20 that decodes the difference vector encoded by the image encoding device 10 as described above and restores the motion vector will be described.

FIG. 6 is a block diagram illustrating a functional configuration of the image decoding device 20 according to the first embodiment. The image decoding apparatus 20 according to the present embodiment restores the motion vector of the decoding target block in order to decode a plurality of pictures encoded for each block. As illustrated in FIG. 6, the image decoding device 20 includes a decoding unit 21, a motion prediction unit 26, and a restoration unit 27.

The decoding unit 21 decodes the encoded difference vector. The decoding unit 21 includes a context control unit 22, an arithmetic decoding unit 23, an inverse binarization unit 24, and a symbol occurrence probability storage unit 25.

The context control unit 22 calculates the context index of the encoded difference vector based on at least the reference picture, similarly to the context control unit 15 in FIG. That is, the context control unit 22 calculates the context index based on the reference picture so that the context index changes depending on the reference picture referenced in the prediction of the decoding target block. The reference picture is specified using, for example, a reference picture index included in the reference picture list.

Furthermore, the context control unit 22 reads the symbol occurrence probability corresponding to the calculated context index from the symbol occurrence probability storage unit 25. Then, the context control unit 22 outputs the read symbol occurrence probability to the arithmetic decoding unit 23.

Further, the context control unit 22 updates the symbol occurrence probability corresponding to the calculated context index, which is stored in the symbol occurrence probability storage unit 25, based on the binary symbol included in the arithmetically decoded difference vector. .

The arithmetic decoding unit 23 arithmetically decodes the encoded difference vector using the symbol occurrence probability corresponding to the calculated context index. That is, the arithmetic decoding unit 23 arithmetically decodes the encoded difference vector using the symbol occurrence probability output from the context control unit 22.

The inverse binarization unit 24 binarizes the arithmetically decoded difference vector. That is, the inverse binarization unit 24 converts the binary signal indicating the difference vector into a multi-value signal.

The symbol occurrence probability storage unit 25 stores a plurality of symbol occurrence probabilities in association with a plurality of context indexes, similarly to the symbol occurrence probability storage unit 17 of FIG. Note that the plurality of symbol occurrence probabilities are initialized, for example, in a predetermined processing unit (for example, a slice).

The motion prediction unit 26 predicts the motion vector of the decoding target block based on the motion vector of the decoded block, similarly to the motion prediction unit 12 of FIG. The motion prediction unit 26 needs to predict a motion vector by the same method as the prediction method used at the time of encoding. The prediction method used at the time of encoding may be determined in advance by a standard or the like, or may be specified by an index included in the encoded bitstream.

The restoration unit 27 restores the motion vector of the decoding target block with respect to the reference picture by adding the decoded difference vector and the predicted motion vector.

FIG. 7 is a flowchart showing the processing operation of the image decoding apparatus 20 according to the first embodiment. The process flow described below is repeated for each decoding target block.

First, the decoding unit 21 decodes the encoded difference vector (S21). This step S21 includes the following steps S22 to S25.

The context control unit 22 calculates a context index based on at least the reference picture (S22). The arithmetic decoding unit 23 arithmetically decodes the encoded difference vector using the symbol occurrence probability corresponding to the context index calculated in step S22 (S23). The inverse binarization unit 24 binarizes the arithmetically decoded difference vector (S24). The context control unit 22 updates the symbol occurrence probability corresponding to the calculated context index based on the binary symbol included in the arithmetically decoded difference vector (S25).

Subsequently, the motion prediction unit 26 predicts the motion vector of the encoding target block based on the motion vector of the encoded block (S26). Finally, the restoring unit 27 restores the motion vector of the decoding target block with respect to the reference picture by adding the difference vector decoded in step S21 and the motion vector predicted in step S26 (S27).

As described above, according to the image decoding device 20 according to the present embodiment, the difference vector encoded by the image encoding device 10 can be decoded.

Note that the context index calculation method described with reference to FIGS. 3 to 5 is an example, and the context index need not necessarily be calculated using the above-described calculation method. For example, the context control unit 15 may calculate the context index by combining the calculation methods of FIGS. That is, the context control unit 15 changes the context index according to whether or not the reference picture is an inter-view reference picture, and changes the context index for each reference picture list in which the reference picture is specified. A context index may be calculated.

Also, the context control unit 15 may calculate a context index by selecting one calculation method from among a plurality of context index calculation methods. For example, the context control unit 15 may select a calculation method having the lowest cost determined by encoding efficiency, memory amount, and the like from among a plurality of context index calculation methods.

In such a case, the image encoding device 10 may encode information indicating the selected calculation method together with the difference vector. Information indicating this calculation method may be written in, for example, a sequence header or a slice header.

H. In H.264, the context index of each of the horizontal component and the vertical component of the difference vector is switched in units of one or more bits. In such a case, the difference in context index of the difference vector means that a combination of context indexes corresponding to one or more bit units in at least one of the horizontal component and the vertical component is different.

Note that the symbol occurrence probability update step (S17, S25) in the arithmetic coding method or the arithmetic decoding method may be skipped in order to reduce the calculation processing amount. In this case, the effect of learning the symbol occurrence probability by using the context cannot be obtained. However, even in this case, the effect of improving the coding efficiency can be expected by arithmetically encoding or decoding the difference vector using the symbol occurrence probability calculated in advance.

(Embodiment 2)
Next, as an application example of the image encoding device 10 and the image decoding device 20 according to Embodiment 1, an image encoding device 100 and an image decoding device 200 according to Embodiment 2 will be described.

FIG. 8 is a block diagram showing a functional configuration of the image coding apparatus 100 according to the second embodiment. Image coding apparatus 100 according to the present embodiment includes subtraction unit 101, orthogonal transform unit 102, quantization unit 103, variable length coding unit 104, inverse quantization unit 105, and inverse orthogonal transform unit 106. An adder 107, a block memory 108, an intra prediction unit 109, a frame memory 110, an inter prediction unit 111, a switch 112, an inter prediction control unit 113, and a picture type determination unit 114. Below, each component with which the image coding apparatus 100 is provided is demonstrated.

The subtraction unit 101 generates prediction error data by subtracting predicted image data from input image data. The orthogonal transform unit 102 transforms the prediction error data generated by the subtraction unit 101 from the image domain to the frequency domain. The quantization unit 103 quantizes the prediction error data converted into the frequency domain by the orthogonal transform unit 102.

The inverse quantization unit 105 inversely quantizes the prediction error data quantized by the quantization unit 103. The inverse orthogonal transform unit 106 transforms the prediction error data inversely quantized by the inverse quantization unit 105 from the frequency domain to the image domain. The adding unit 107 generates reconstructed image data by adding the prediction error data converted into the image region by the inverse orthogonal transform unit 106 and the predicted image data output from the switch 112.

The block memory 108 is a memory for storing the reconstructed image data in units of blocks. The frame memory 110 is a memory for storing the reconstructed image data in units of frames.

The intra prediction unit 109 performs intra prediction using the reconstructed image data in units of blocks stored in the block memory 108, thereby generating predicted image data of the encoding target block.

The inter prediction unit 111 derives the motion vector of the encoding target picture for the reference picture for each block by performing motion detection in the same manner as the motion detection unit 11 of the first embodiment. Further, the inter prediction unit 111 performs inter prediction using the derived motion vector and the reconstructed image data in units of frames stored in the frame memory 110. That is, the inter prediction unit 111 generates predicted image data of the encoding target picture by performing motion compensation for each block using the motion vector and the reference picture.

Switch 112 switches the prediction mode to intra prediction or inter prediction. That is, the switch 112 outputs one of the predicted image data generated by the intra prediction unit 109 and the predicted image data generated by the inter prediction unit 111.

The picture type determining unit 114 determines which of the I picture, B picture, and P picture is used to encode the input image data, and generates picture type information indicating the determined picture type.

The inter prediction control unit 113 predicts the motion vector of the block to be encoded with respect to the reference picture based on the motion vector of the encoded block, similarly to the motion prediction unit 12 of the first embodiment. In the present embodiment, the inter prediction control unit 113 predicts a motion vector by selecting one prediction motion vector from one or more prediction motion vector candidates included in the list.

The candidate for one or more motion vector predictors included in the list is a candidate based on the motion vector of the encoded block. Specifically, the list may include motion vectors of blocks included in the encoding target picture and spatially adjacent to the encoding target block as prediction motion vector candidates. In addition, the list may include motion vectors of blocks that are included in one or more pictures different from the current picture to be encoded and that spatially match the current target block as prediction motion vector candidates. Good.

The variable length encoding unit 104 generates an encoded bitstream by arithmetically encoding quantized prediction error data, an index indicating a prediction motion vector, a difference vector, and picture type information.

Note that the variable-length encoding unit 104 arithmetically encodes the difference vector using the context index calculated based on the reference picture, similarly to the encoding unit 13 of the first embodiment. Since the detailed functional configuration regarding the encoding of the difference vector in the variable length encoding unit 104 is the same as that of the encoding unit 13 in FIG. 1, illustration and description thereof are omitted.

FIG. 9 is a block diagram illustrating a functional configuration of the image decoding apparatus 200 according to the second embodiment. The image decoding apparatus 200 according to the present embodiment includes a variable length decoding unit 204, an inverse quantization unit 205, an inverse orthogonal transform unit 206, an addition unit 207, a block memory 208, an intra prediction unit 209, a frame A memory 210, an inter prediction unit 211, a switch 212, and an inter prediction control unit 213 are provided. Below, each component with which the image decoding apparatus 200 is provided is demonstrated.

The variable length decoding unit 204 decodes picture type information, an index indicating a prediction motion vector, a difference vector, prediction error data, and the like by performing variable length decoding on the input encoded bitstream.

Note that the variable length decoding unit 204 arithmetically decodes the encoded difference vector using the context index calculated based on the reference picture, similarly to the decoding unit 21 of the first embodiment. The detailed functional configuration regarding decoding of the encoded difference vector in the variable length decoding unit 204 is the same as that of the decoding unit 21 in FIG.

The inverse quantization unit 205 inversely quantizes the decoded prediction error data. The inverse orthogonal transform unit 206 transforms the inversely quantized prediction error data from the frequency domain to the image domain. The adding unit 207 generates decoded image data by adding the predicted image data and the prediction error data.

The block memory 208 is a memory for storing decoded image data in units of blocks. The frame memory 210 is a memory for storing decoded image data in units of frames.

The intra prediction unit 209 generates predicted image data of the decoding target block by executing intra prediction using the decoded image data in units of blocks stored in the block memory 208.

The inter prediction unit 211 restores the motion vector of the decoding target block with respect to the reference picture by adding the decoded difference vector and the predicted motion vector, similarly to the restoration unit 27 of the first embodiment. Furthermore, the inter prediction unit 211 performs inter prediction using the restored motion vector and the decoded image data in units of frames stored in the frame memory 210. That is, the inter prediction unit 211 generates prediction image data of a decoding target picture by performing motion compensation for each block using a motion vector and a reference picture.

Switch 212 switches the prediction mode to intra prediction or inter prediction. That is, the switch 212 outputs one of the predicted image data generated by the intra prediction unit 209 and the predicted image data generated by the inter prediction unit 211.

The inter prediction control unit 213 predicts the motion vector of the decoding target block with respect to the reference picture based on the motion vector of the decoded block, similarly to the motion prediction unit 26 of the first embodiment. In the present embodiment, the inter prediction control unit 213 predicts a motion vector by selecting one prediction motion vector from one or more prediction motion vector candidates included in the list.

Note that the process executed by the inter prediction control unit 213 is the same as the process executed by the inter prediction control unit 113 on the encoding side. That is, in the above encoding process, the inter prediction control unit 213 is realized by changing the encoding part to decoding. Note that the inter prediction control unit 213 uses the index indicating the prediction motion vector decoded by the variable length decoding unit 204 to select one prediction motion vector from one or more prediction motion vector candidates included in the list. select.

(Embodiment 3)
The number of applications for video-on-demand services, including video conferencing, digital video broadcasting, and video content streaming over the Internet, is rising, and these applications Rely on sending. When video data is transmitted or recorded, a significant amount of data is transmitted through a conventional transmission line with limited bandwidth or stored in a conventional storage medium with limited data capacity. Is done. In order to transmit and store video information on conventional transmission channels and storage media, it is essential to compress or reduce the amount of digital data.

Therefore, a plurality of video coding standards have been developed for compressing video data. Such a video coding standard is, for example, H.264. ITU-T standard indicated by 26x and ISO / IEC standard indicated by MPEG-x. The latest and most advanced video coding standard is currently H.264. H.264 / MPEG-4 AVC standard (see Non-Patent Document 3).

The coding approach that underlies most of these standards is based on predictive coding including the main steps shown in (a) to (d) below. (A) The video frame is divided into pixel blocks in order to compress the data of each video frame at the block level. (B) Identify temporal and spatial redundancy by predicting individual blocks from previously encoded video data. (C) The specified redundancy is removed by subtracting the prediction data from the video data. (D) The remaining data (residual block) is compressed by Fourier transform, quantization, and entropy coding.

In the above step (a), the current video coding standard differs in the prediction mode used to predict each macroblock. Most video coding standards use motion detection and motion compensation (interframe prediction) to predict video data from previously encoded and decoded frames. Alternatively, the block data may be extrapolated from adjacent blocks in the same frame (intra frame prediction).

However, in the case of encoding by interframe prediction, it is necessary to include information for specifying a motion vector in the encoded stream. That is, there is a problem that the encoding efficiency is reduced by the amount of information for specifying the motion vector.

Therefore, the image encoding method and the image decoding method according to the present embodiment perform encoding and decoding by appropriately switching whether or not information for specifying a motion vector is included in the encoded stream.

The image decoding method according to the present embodiment is a method for generating decoded blocks by decoding encoded block data. Specifically, using a motion vector calculation step for individually calculating an x component and a y component of a motion vector indicating the motion of the decoded block in a reference image, and using the motion vector acquired in the motion vector acquisition step, Decoding the encoded block data to generate the decoded block. The data structure of the encoded block data includes a first data structure including both x component specifying information for specifying the x component of the motion vector and y component specifying information for specifying the y component of the motion vector. Or the second data structure including only the x component specifying information of the x component specifying information and the y component specifying information. The motion vector calculation step includes a determination step of determining a data structure of the encoded block data, and the motion vector based on the x component identification information when the determination step determines the first data structure. And the x component when the second data structure is determined in the first calculation step of calculating the y component of the motion vector from the y component specifying information and the determination step. A second calculation step of calculating the x component of the motion vector from the specific information and calculating the y component of the motion vector as 0.

According to the above configuration, the presence / absence of the y component identification information can be determined from the data structure of the encoded block data, and the motion vector can be calculated appropriately. As a result, it is possible to effectively suppress a decrease in encoding efficiency.

Also, for example, the motion vector may be represented by the sum of a prediction vector and a difference vector. The x component identification information may be an x component of the difference vector. The y component identification information may be a y component of the difference vector. In the first calculation step, the x component and the y component of the prediction vector are individually predicted from the motion vector of the decoded block decoded in the past, and the components of the difference vector and the prediction vector are added to each other. The x and y components of the motion vector may be calculated. On the other hand, in the second calculation step, the x component of the prediction vector is predicted from the motion vector of the decoded block decoded in the past, and the x component of the difference vector and the x component of the prediction vector are added to calculate the motion. The x component of the vector may be calculated.

For example, in the determination step, the data structure of the encoded block data is determined by referring to a y component encoding flag included in a slice header of a slice including the decoded block or a picture header of a picture including the decoded block. You may judge.

Further, for example, in the determination step, when a value indicating that the y component identification information is not encoded is set in the y component encoding flag of the picture header, all the blocks included in the picture are included. You may determine with the said encoding block data being the said 2nd data structure. On the other hand, in the determination step, when a value indicating that the y component specifying information is not encoded is set in the y component encoding flag of the slice header, the y component encoding flag of the picture header is set. Regardless of the value of, it may be determined that the encoded block data of all the blocks included in the slice has the second data structure.

The image encoding method according to the present embodiment is a method for generating encoded block data by encoding a target block. Specifically, using a motion vector calculation step for individually calculating an x component and a y component of a motion vector indicating the motion of the target block in a reference image, and using the motion vector acquired in the motion vector acquisition step, An encoding step of encoding the target block to generate the encoded block data. In the encoding step, when the y component of the motion vector is not 0, the x component specifying information for specifying the x component of the motion vector and the y component specifying for specifying the y component of the motion vector Both of the information are included in the encoded block data. On the other hand, in the encoding step, when the y component of the motion vector is 0, only the x component specifying information of the x component specifying information and the y component specifying information is included in the encoded block data.

According to the above configuration, it is possible to switch whether to include the y component identification information of the motion vector in the encoded block data as necessary. As a result, it is possible to effectively suppress a decrease in encoding efficiency.

Also, for example, the motion vector calculation step specifies a first prediction block of the target block by searching in the reference image in a horizontal direction and a vertical direction, and the motion vector corresponding to the first prediction block A first calculation step for individually calculating the x component and the y component of the first prediction block, and a second prediction block of the target block is specified by searching in the reference image only in the horizontal direction, and the second prediction block And a second calculation step of calculating only the x component of the motion vector corresponding to. The image encoding method further includes encoding the target block using the first prediction block, and including both the x component specifying information and the y component specifying information in the encoded block data. A first encoding cost and a second encoding cost when the target block is encoded using the second prediction block and only the x component specifying information is included in the encoded block data. A cost determination step for determining the magnitude relationship may be included. In the encoding step, when it is determined in the cost determination step that the first encoding cost is small, the x component specifying information and the y component specifying information corresponding to the first prediction block Both may be included in the encoded block data. On the other hand, in the encoding step, when it is determined in the cost determining step that the second encoding cost is small, only the x component specifying information corresponding to the second prediction block is stored in the encoded block data. May be included.

Further, for example, the target image including the target block may be one of the images constituting the 3D video. In the encoding step, when the reference image and the target image are the same viewpoint image, both the x component specifying information and the y component specifying information may be included in the encoded block data. On the other hand, in the encoding step, when the reference image and the target image are other viewpoint images at the same time, only the x component specifying information may be included in the encoded block data.

These general or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM. The system, method, integrated circuit, computer program Alternatively, it may be realized by any combination of recording media.

Hereinafter, the image encoding device and the image decoding device according to the present embodiment will be specifically described with reference to the drawings.

FIG. 10 is a block diagram showing a configuration of the image coding apparatus according to the present embodiment. An image encoding apparatus 1000 illustrated in FIG. 10 includes an encoding processing unit 1100 and an encoding control unit 1200.

The encoding processing unit 1100 generates an encoded stream by encoding a moving image. A moving image is composed of a plurality of images, and each image is composed of a plurality of blocks. Then, encoded block data is generated by encoding each block. This set of encoded block data is defined as an encoded stream.

As shown in FIG. 10, the encoding processing unit 1100 includes a subtractor 1101, an orthogonal transform unit 1102, a quantization unit 1103, an entropy encoding unit 1104, an inverse quantization unit 1105, an inverse orthogonal transform unit 1106, and an adder 1107. , A deblocking filter 1108, a memory 1109, an in-plane prediction unit 1110, a motion compensation unit 1111, a motion detection unit 1112, and a switch 1113.

The subtractor 1101 acquires a moving image and also acquires a predicted image (predicted block) from the switch 1113. Then, the subtractor 1101 generates a residual image (residual block) by subtracting the predicted image from the encoding target block included in the moving image.

The orthogonal transform unit 1102 performs orthogonal transform such as discrete cosine transform on the residual image generated by the subtractor 1101, thereby transforming the residual image into a coefficient block composed of a plurality of frequency coefficients. The quantization unit 1103 generates a quantized coefficient block by quantizing each frequency coefficient included in the coefficient block.

The entropy encoding unit 1104 performs entropy encoding (variable length encoding) on the coefficient block quantized by the quantization unit 1103 and the motion vector detected by the motion detection unit 1112, thereby generating an encoded stream (encoding). Block data).

The entropy encoding unit 1104 includes both the x component specifying information and the y component specifying information in the encoded block data when the y component of the acquired motion vector is not 0. On the other hand, when the y component of the motion vector is 0, the entropy encoding unit 1104 includes only the x component specifying information of the x component specifying information and the y component specifying information in the encoded block data, and the y component specifying information Is not included in the encoded block data.

The inverse quantization unit 1105 performs inverse quantization on the coefficient block quantized by the quantization unit 1103. The inverse orthogonal transform unit 1106 generates a decoded residual image (decoded residual block) by performing inverse orthogonal transform such as inverse discrete cosine transform on each frequency coefficient included in the inverse quantized coefficient block. To do.

The adder 1107 acquires a predicted image from the switch 1113, and generates a local decoded image (decoded block) by adding the predicted image and the decoded residual image generated by the inverse orthogonal transform unit 1106.

The deblocking filter 1108 removes block distortion of the local decoded image generated by the adder 1107 and stores the local decoded image in the memory 1109.

The in-plane prediction unit 1110 generates a predicted image by performing in-plane prediction on the current block using the locally decoded image generated by the adder 1107.

The motion detection unit 1112 detects a motion vector for the encoding target block included in the moving image, and outputs the detected motion vector to the motion compensation unit 1111 and the entropy encoding unit 1104. Details of the motion vector detection method will be described later.

The motion compensation unit 1111 refers to the image stored in the memory 1109 as a reference image, and performs motion compensation on the coding target block by using the motion vector detected by the motion detection unit 1112. The motion compensation unit 1111 generates a prediction image for the encoding target block through such motion compensation.

The switch 1113 outputs the prediction image generated by the in-plane prediction unit 1110 to the subtractor 1101 and the adder 1107 when the current block is subjected to intra-frame prediction encoding. On the other hand, the switch 1113 outputs the prediction image generated by the motion compensation unit 1111 to the subtractor 1101 and the adder 1107 when the encoding target block is subjected to inter-frame prediction encoding.

The encoding control unit 1200 controls the operation of the encoding processing unit 1100. As an example, the encoding control unit 1200 calculates in either of the first and second calculation processes to be described later in consideration of the characteristics of the moving image to be encoded or the encoding cost when the moving image is encoded. It is determined whether to perform the encoding process using the motion vector thus determined.

Referring to FIG. 11, a process for determining a motion vector calculation method in consideration of encoding cost and encoding a target block using a motion vector specified by the determined calculation method will be described. FIG. 11 is a flowchart showing the procedure of the encoding process according to the present embodiment.

First, the encoding control unit 1200 causes the motion detection unit 1112 to specify the motion vector of the encoding target block using the first calculation process (S11). The first calculation process is to specify the first prediction block of the encoding target block by searching in the reference image in the horizontal direction and the vertical direction, and the x component of the motion vector corresponding to the first prediction block and This is a process of calculating the y component individually.

That is, the motion detection unit 1112 is a two-dimensional region including a block (corresponding block) corresponding to an encoding target block position in the reference image (a position corresponding to the position of the encoding target block in the encoding target image). A block closest to the encoding target block (first prediction block) is searched. Then, the motion detection unit 1112 sets a vector from the corresponding block toward the first prediction block as a motion vector.

Next, the encoding control unit 1200 causes the motion detection unit 1112 to specify the motion vector of the encoding target block using the second calculation process (S12). The second calculation process is a process for specifying the second prediction block of the target block by searching the reference image only in the horizontal direction and calculating only the x component of the motion vector corresponding to the second prediction block. It is.

That is, the motion detection unit 1112 searches for the second prediction block in the left and right one-dimensional regions of the corresponding block in the reference image. Then, the motion detection unit 1112 sets a vector from the corresponding block to the second prediction block as a motion vector.

In addition, the execution order of said step S11 and step S12 is not limited to said example, You may perform in a reverse order and may execute in parallel. In this embodiment, the x component is described as a horizontal component, and the y component is a vertical component. However, the present invention is not limited to this. That is, the x component and the y component only need to represent components in two directions that intersect (orthogonal) each other.

Next, the encoding control unit 1200 encodes the encoding target block using the motion vector specified in the first calculation process (first encoding cost), and the second The encoding cost (second encoding cost) when the encoding target block is encoded using the motion vector specified in the calculation process is compared (S13).

For example, the encoding cost can be calculated by Equation 1 below. In Expression 1, D represents encoding distortion, and a difference between a pixel value obtained by encoding 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 absolute value sum 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. Further, λ is a Lagrange multiplier.

Here, the first encoding cost is the encoding cost when the target block is encoded using the first prediction block and both the x component specifying information and the y component specifying information are included in the encoded block data. Point to. On the other hand, the second encoding cost is the encoding cost when the target block is encoded using the second prediction block, only the x component specifying information is included in the encoded block data, and the y component specifying information is omitted. Point to.

Then, when it is determined that the first encoding cost is smaller than the second encoding cost (Yes in S13), the encoding control unit 1200 encodes the encoding target block using the first prediction block. And the encoding processing unit 1100 is controlled to include both the x component specifying information and the y component specifying information of the motion vector corresponding to the first prediction block in the encoded block data (S14).

More specifically, the subtractor 1101 generates a residual block by subtracting the corresponding pixel value of the first prediction block from each pixel value of the encoding target block. The orthogonal transform unit 1102 performs orthogonal transform on the pixel values of the residual block to generate a frequency coefficient block. The quantization unit 1103 quantizes the frequency coefficient block to generate a quantization coefficient block. Then, the entropy encoding unit 1104 entropy encodes the quantized coefficient block to generate encoded block data. Further, the entropy encoding unit 1104 includes the x component specifying information and the y component specifying information of the motion vector in the encoded block data.

Also, the inverse quantization unit 1105 generates a frequency coefficient block by inverse quantization of the quantized coefficient block. The inverse orthogonal transform unit 1106 performs an inverse orthogonal transform on the frequency coefficient block to generate a residual block. The adder 1107 adds a corresponding pixel value of the first prediction block to each pixel value of the residual block, thereby generating a decoded block. Then, the deblocking filter 1108 applies the deblocking filter process to the decoded block and stores it in the memory 1109. The decoded block stored in the memory 1109 is referred to when the subsequent encoding target block is encoded.

On the other hand, when it is determined that the second coding cost is smaller than the first coding cost (No in S13), the coding control unit 1200 codes the coding target block using the second prediction block. In addition, the encoding processing unit 1100 is controlled so that only the x component specifying information of the motion vector corresponding to the second prediction block is included in the encoded block data (S15).

The encoding process in step S15 is common to step S14 except that the second prediction block is used instead of the first prediction block, and that the y component identification information is not included in the encoded block data. The description will not be repeated. If the first and second encoding costs are the same, either step S14 or step S15 may be executed.

As described above, the encoding control unit 1200 according to the present embodiment omits the first encoding cost when the search (block matching) in the reference image is not limited and the y component of the motion vector. Encoding processing so that the target block is encoded using the motion vector specified in the calculation processing with the lower cost compared with the second encoding cost reflecting the improvement in encoding efficiency due to The unit 1100 is controlled. Thereby, encoding efficiency can be improved dramatically.

Here, typically, “x component identification information” refers to the x component of the difference vector, and “y component identification information” refers to the y component of the difference vector, but the x component and y component of the motion vector are The information is not limited to this as long as it can be specified. The motion vector is represented by the sum of the prediction vector and the difference vector. That is, the difference vector is obtained by subtracting the prediction vector from the motion vector detected by the motion detection unit 1112.

For example, as shown in FIG. 12, the prediction vector can be calculated using a motion vector of an adjacent block that is adjacent to the target block and encoded before the target block. For example, the motion vector mvA of the adjacent block A adjacent to the left side of the target block, the motion vector mvB of the adjacent block B adjacent to the upper side of the target block, and the motion vector mvC of the adjacent block C adjacent to the upper right of the target block The median value (or average value) for each component may be the prediction vector mv of the target block. However, when the y component identification information is not included in the encoded block data, the y component of the difference vector is not calculated by the above method but is set to 0 (fixed value).

And the x component specifying information and the y component specifying information calculated in this way are stored in, for example, the data structure shown in FIG. FIG. 13 is a diagram illustrating an example of the header information of the encoded block data (Prediction unit syntax).

In the data structure shown in FIG. 13, the x component specifying information is stored in “mvd_lc [x0] [y0] [0]” (any one of the 24th, 33rd, and 42nd lines). On the other hand, the y component identification information is stored in “mvd_lc [x0] [y0] [1]” (any one of the 26th, 35th, and 44th lines).

When the y component identification information is stored in the encoded block data, the y component identification information is encoded in the y component encoding flag ("mvd_y_code" in FIG. 13) (stored in the encoded block data). (For example, “1”) is set. On the other hand, when the y component identification information is not stored in the encoded block data, the y component identification information is not encoded (stored in the encoded block data) in the y component encoding flag ("mvd_y_code" in FIG. 13). A value (for example, “0”) is set.

The y component encoding flag is stored in a block header, a slice header, a picture header (PPS), or the like shown in FIG. Furthermore, the y component encoding flag may be stored in a sequence parameter set (Sequence Parameter Set: SPS) higher than the picture header.

The encoded stream shown in FIG. 14 includes a plurality of picture headers and a plurality of picture data. One picture data includes a plurality of slice headers and a plurality of slice data as encoded data of one image. One slice data includes a plurality of block headers and a plurality of block data as encoded data of one slice. The block header includes information shown in FIG. 13, for example, and the block data includes encoded data of each pixel constituting the block.

Here, the y component encoding flag stored in the picture header affects all the encoded block data included in the picture. In other words, when “0 (no y component identification information is included)” is set in the y component encoding flag of the picture header, in principle, y component identification is performed for all encoded block data included in the picture. Information is not included (the encoded block data has the second data structure).

However, when the y component encoding flag is set in the slice header, whether or not the y component specifying information is stored in all the encoded block data included in the slice depends on the y component encoding flag in the picture header. Regardless of the value of y, it follows the set value of the y component encoding flag of the slice header. The same applies when the y component encoding flag is set in the block header.

That is, in order to determine whether or not the y component identification information is stored in the encoded block data, first, it is confirmed whether or not the y component encoding flag is set in the block header of the encoded block data. If it is set, it follows the set value. When the y component encoding flag is not set in the block header, it is confirmed whether or not the y component encoding flag is set in the slice header of the slice including the encoded block data. According to the set value. Further, when the y component encoding flag is not set in the slice header, the set value of the y component encoding flag in the picture header of the picture including the slice is followed.

In the above example, the motion vector calculation method is determined based on the coding cost, but the motion vector determination method in the present invention is not limited to this. For example, when the encoding target moving image is 3D video and the encoding target image and the reference image are other viewpoint images at the same time, the encoding control unit 1200 performs the motion vector in the second calculation process. The motion detection unit 1112 may be controlled so as to specify.

The 3D video is, for example, a left-eye image and a right-eye image that have parallax with each other, and the left-eye image is viewed only by the viewer's left eye, and the right-eye image is viewed by the viewer. The viewer can feel a three-dimensional effect by viewing only with his right eye.

Here, as shown in FIG. 15, one of the left-eye image and the right-eye image (left-eye image in the example of FIG. 15) is called “Base View” and is taken at the same viewpoint and at different times. The motion vector can be specified with reference to the image. On the other hand, the other of the left-eye image and the right-eye image (right-eye image in the example of FIG. 12) is called “Dependent View” and is an image (for example, FIG. The motion vector can be identified by referring to images before and after the 15 target images) or images taken from another viewpoint at the same time (for example, an image above the target image in FIG. 15).

Also, the parallax refers to a horizontal shift when comparing other viewpoint images (left eye image and right eye image) taken at the same time. That is, it can be said that the other viewpoint images at the same time are shifted in the horizontal direction by the amount of parallax, and there is substantially no vertical shift. In such a case, the motion detection unit 1112 can find an appropriate prediction block corresponding to the encoding target block only by searching the reference image only in the horizontal direction. That is, even if encoding is performed using the motion vector specified in the second calculation process, the encoding efficiency does not decrease. Furthermore, since it is not necessary to include the y component identification information in the encoded block data, the encoding efficiency is improved accordingly.

Also, in the example of calculating the encoding cost described above, it is necessary to always execute both the first and second calculation processes and to perform the encoding process using the two calculated motion vectors. On the other hand, in the method of switching the calculation process according to the characteristics of the 3D video, only one of the first and second calculation processes needs to be executed, so that the processing load on the image coding apparatus 1000 is greatly reduced. be able to.

As yet another example, when the shooting information of the moving image is acquired together with the moving image to be encoded, the encoding control unit 1200 selects one of the first and second calculation processes based on the shooting information. May be. For example, if the shooting information indicates that panning (an operation that changes the direction of the camera in the left-right direction (horizontal direction)), a large shift in the horizontal direction occurs in each image while panning, and the vertical It can be evaluated that there is almost no deviation in the direction. Therefore, the encoding control unit 1200 may control the motion detection unit 1112 so that the motion vector is specified by the second calculation process even in such a case.

FIG. 16 is a block diagram showing a configuration of the image decoding apparatus according to the present embodiment. An image decoding apparatus 2000 illustrated in FIG. 16 includes a decoding processing unit 2100 and a decoding control unit 2200. The decoding processing unit 2100 generates a decoded image including a plurality of decoding blocks by sequentially decoding the encoded block data included in the encoded stream.

As shown in FIG. 16, the decoding processing unit 2100 includes an entropy decoding unit 2101, an inverse quantization unit 2102, an inverse orthogonal transform unit 2103, an adder 2104, a deblocking filter 2105, a memory 2106, an in-plane prediction unit 2107, a motion A compensation unit 2108 and a switch 2109 are provided.

The entropy decoding unit 2101 acquires an encoded stream and performs entropy decoding (variable length decoding) on the encoded stream.

The inverse quantization unit 2102 inversely quantizes the quantized coefficient block generated by entropy decoding by the entropy decoding unit 2101. The inverse orthogonal transform unit 2103 generates a decoded residual image by performing inverse orthogonal transform such as inverse discrete cosine transform on each frequency coefficient included in the inverse quantized coefficient block.

The adder 2104 obtains a predicted image from the switch 2109, and generates a decoded image (decoded block) by adding the predicted image and the decoded residual image generated by the inverse orthogonal transform unit 2103.

The deblocking filter 2105 removes block distortion of the decoded image generated by the adder 2104, stores the decoded image in the memory 2106, and outputs the decoded image.

The in-plane prediction unit 2107 generates a predicted image by performing in-plane prediction on the decoding target block using the decoded image generated by the adder 2104.

The motion compensation unit 2108 performs motion compensation on the decoding target block by using the reference image and the motion vector for the image stored in the memory 2106. The motion compensation unit 2108 generates a prediction image for the decoding target block by such motion compensation. Details of the motion vector acquisition method will be described later.

The switch 2109 outputs the prediction image generated by the in-plane prediction unit 2107 to the adder 2104 when the decoding target block is subjected to the plane prediction encoding. On the other hand, the switch 2109 outputs the prediction image generated by the motion compensation unit 2108 to the adder 2104 when the decoding target block is subjected to inter-frame prediction encoding.

The decoding control unit 2200 controls the decoding processing unit 2100. For example, the decoding control unit 2200 determines the data structure of the encoded block data, and acquires a motion vector by a method according to the determined data structure.

Referring to FIG. 17, a process of acquiring a motion vector by a method according to the data structure of encoded block data and decoding the encoded block data using the acquired motion vector will be described. FIG. 17 is a flowchart showing the procedure of the decoding process according to the present embodiment.

First, the decoding control unit 2200 determines the data structure of the encoded block data (S21). Here, the data structure of the coded block data is the first data structure including both the x component specifying information and the y component specifying information of the motion vector, or the x component specifying of the x component specifying information and the y component specifying information. One of the second data structures containing only information.

Then, the decoding control unit 2200 causes the entropy decoding unit 2101 to entropy decode the block header, slice header, or picture header shown in FIG. 14, and refers to the y component encoding flag set in these The data structure of the encoded block data can be determined.

When the encoded block data has the first data structure, the decoding control unit 2200 individually calculates the x component and the y component of the motion vector (S22). Specifically, the decoding control unit 2200 specifies x component identification information (“mvd_lc [x0] [y0] [0]” in FIG. 13) that is the x component of the difference vector and y component identification that is the y component of the difference vector. Information (“mvd_lc [x0] [y0] [1]” in FIG. 13) is acquired from the encoded block data. Next, the decoding control unit 2200 calculates the x component and the y component of the prediction vector by the method described with reference to FIG. The decoding control unit 2200 adds the x component of the difference vector and the x component of the prediction vector to calculate the x component of the motion vector, and adds the y component of the difference vector and the y component of the prediction vector to perform motion. Calculate the y component of the vector.

On the other hand, when the encoded block data has the second data structure, the decoding control unit 2200 calculates the x component of the motion vector by the same method as described above, and calculates the y component of the motion vector as 0 (S23). ).

Then, the decoding control unit 2200 causes the decoding processing unit 2100 to decode the encoded block data using the calculated motion vector (S24). Thereby, a decoding block is obtained. The operations of the inverse quantization unit 2102, the inverse orthogonal transform unit 2103, the adder 2104, the deblocking filter 2105, the memory 2106, the in-plane prediction unit 2107, and the switch 2109 are the same as the function blocks having the same names shown in FIG. Common.

The entropy decoding unit 2101 entropy-decodes the encoded block data, generates a quantized coefficient block of the corresponding block of the decoded block, and outputs it to the inverse quantization unit 2102. In addition, the motion compensation unit 2108 generates a prediction block of the decoded block using the motion vector specified by the above-described process.

A value (for example, “0”) indicating that the y component identification information is not encoded (not stored in the encoded block data) is set in the y component encoding flag (“mvd_y_code” in FIG. 13). In this case, the y component of the motion vector may be encoded and decoded as a y component offset value instead of 0 as a y constant offset value. For example, in the case of 3D video using a plurality of cameras, a certain horizontal shift may always occur due to camera alignment.

In this case, the deviation is detected on the encoding side, for example, encoded in addition to the header information, and encoded as the y component when the y component identification information is not encoded. On the decoding side, for example, the y-component offset value is restored from the header information and decoded as the y-component value, thereby improving the coding efficiency in the present invention even if there is a deviation. Stream can be correctly decoded.

(Embodiment 4)
By recording a program for realizing the configuration of the moving image encoding method (image encoding method) or the moving image decoding method (image decoding method) shown in each of the above embodiments on a storage medium, each of the above embodiments It is possible to easily execute the processing shown in the form in the independent computer system. 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.

Furthermore, application examples of the moving picture coding method (picture coding method) and the moving picture decoding method (picture decoding method) shown in the above embodiments and a system using the same will be described. The system has an image encoding / decoding device including an image encoding device using an image encoding method and an image decoding device using an image decoding method. Other configurations in the system can be appropriately changed according to circumstances.

FIG. 18 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 shown in FIG. 18 and may be connected by combining any of the elements. 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 Terminal 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, content that is shot by a user using the camera ex113 (for example, music live video) is encoded as described in each of the above embodiments (that is, in one aspect of the present invention). Functions as an image encoding device), and transmits it 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 (that is, functions as an image decoding device according to one embodiment of the present invention).

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. 19, the digital broadcasting system ex200 also includes at least the moving image encoding device (image encoding device) or the moving image decoding according to each of the above embodiments. Any of the devices (image decoding devices) can be incorporated. 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 each of the above embodiments (that is, data encoded by the image encoding apparatus according to one aspect of the present invention). 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 an apparatus such as the television (receiver) ex300 or the set top box (STB) ex217 (that is, functions as an image decoding apparatus according to one embodiment of the present invention).

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. 20 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.

The television ex300 also decodes the audio data and the video data, or encodes the information, the audio signal processing unit ex304, the video signal processing unit ex305 (the image encoding device or the image according to one embodiment of the present invention) A signal processing unit ex306 that functions as a decoding device), a speaker ex307 that outputs the decoded audio signal, and an output unit ex309 that includes a display unit ex308 such as a display that displays 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. 21 shows a 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 information reflected 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 control unit 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 types of information held in the buffer ex404, and generates and adds new information as necessary. 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 includes, 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. 22 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. The configuration of the car navigation ex211 may be, for example, the configuration shown in FIG. 20 with a GPS receiving unit added, and the same may be considered for the computer ex111, the mobile phone ex114, and the like.

FIG. 23A is a diagram showing the mobile phone ex114 using the video decoding method and the video 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 a user operation, the power supply circuit unit 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 ex357.

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. Encode (that is, function as an image encoding device according to an aspect of the present invention), and send the encoded video data to the multiplexing / demultiplexing unit ex353. The audio signal processing unit ex354 encodes the audio signal picked up by the audio input unit ex356 while the camera unit ex365 images a video, a still image, etc., and sends the encoded audio data to the multiplexing / separating unit ex353. To do.

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 unit (modulation / demodulation circuit unit) ex352, 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 (that is, an image according to an aspect of the present invention). For example, video and still images included in the moving image file linked to the home page are displayed from the display unit ex358 via the LCD control unit ex359. 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 or the like is multiplexed with video data is received and transmitted, but data in which character data or the like related to video is multiplexed in addition to audio data It 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 5)
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. 24 is a diagram showing a structure of multiplexed data. As shown in FIG. 24, 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. 25 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. 26 shows in more detail how the video stream is stored in the PES packet sequence. The first row in FIG. 26 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. 26, a plurality of Video Presentation Units in the video stream are divided into each picture, and 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. 27 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. In the multiplexed data, source packets are arranged as shown in the lower part of FIG. 27, 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. 28 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. 29, 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.

The multiplexed data information includes a system rate, a reproduction start time, and a reproduction end time as shown in FIG. 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. 30, the attribute information for 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. 31 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 6)
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. 32 shows a configuration of an 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 uses the AV I / O ex509 to perform the microphone ex117 and the camera ex113 based on the control of the control unit ex501 including the CPU ex502, the memory controller ex503, the stream controller ex504, the driving 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 ex501 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 ex501 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 advances in semiconductor technology or other derived technology, it is naturally also possible to integrate functional blocks using this technology. Biotechnology can be applied.

(Embodiment 7)
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. 33 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 identification of video data, for example, the identification information described in the fifth embodiment may be used. The identification information is not limited to that described in the fifth embodiment, 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. Further, the selection of the driving frequency in the CPU ex502 may be performed based on, for example, a look-up 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. 34 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 8)
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. 36A. 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 common processing contents, the decoding processing unit ex902 corresponding to the MPEG4-AVC standard is shared, and for other processing contents specific to one aspect of the present invention that do not correspond to the MPEG4-AVC standard, a dedicated decoding processing unit A configuration using ex901 is conceivable. 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. 36B shows another example in which processing is partially shared. In this example, a dedicated decoding processing unit ex1001 corresponding to the processing content specific to one aspect of the present invention, a dedicated decoding processing unit ex1002 corresponding to the processing content specific to another conventional standard, and one aspect of the present invention And a common decoding processing unit ex1003 corresponding to the processing contents common to the moving image decoding method according to the above and other conventional moving image decoding methods. Here, the dedicated decoding processing units ex1001 and ex1002 are not necessarily specialized in one aspect of the present invention or processing content specific to other conventional standards, and can execute other general-purpose processing. Also good. Also, the configuration of the present embodiment can be implemented by LSI ex500.

As described above, the processing content common to the moving picture decoding method according to one aspect of the present invention and the moving picture decoding method of the conventional standard reduces the circuit scale of the LSI by sharing the decoding processing unit, In addition, the cost can be reduced.

The image encoding method and the image decoding method according to an aspect of the present invention can be used in, for example, a television receiver, a digital video recorder, a car navigation, a mobile phone, a digital camera, a digital video camera, or the like.

10, 100, 1000

Image encoding device

11, 1112

Motion detection unit

12, 26 Motion prediction unit 13 Encoding unit 14

Binarization unit

15, 22 Context control unit 16

Arithmetic encoding unit

17, 25 Symbol occurrence

probability storage unit

20 , 200, 2000 Image decoding device 21 Decoding unit 23 Arithmetic decoding unit 24 Inverse binarization unit 27 Restoration unit 101

Subtraction unit

102, 1102

Orthogonal transformation unit

103, 1103 Quantization unit 104 Variable

length encoding unit

105, 205, 1105, 2102

Inverse quantization unit

106, 206, 1106, 2103 Inverse

orthogonal transform unit

107, 207

Adder unit

108, 208

Block memory

109, 209

Intra prediction unit

110, 210

Frame memory

111, 211

Inter prediction unit

112, 212, 1113, 2109 Switch 113, 213 A Data prediction unit 114 picture type determination unit 204 variable length decoding unit 1100 encoding processing unit 1101 subtractor 1104

entropy encoding unit

1107, 2104

adder

1108, 2105

deblocking filter

1109, 2106

memory

1110, 2107 intra prediction unit 1111 2108 Motion compensation unit 1200 Encoding control unit 2100 Decoding processing unit 2200 Decoding control unit 2101 Entropy decoding unit

Claims

An image encoding method for encoding a motion vector of an encoding target block in order to encode a plurality of pictures for each block,
A motion detection step of deriving a motion vector of an encoding target block with respect to a reference picture by performing motion detection;
A motion prediction step of predicting a motion vector of the encoding target block based on a motion vector of the encoded block;
Encoding a difference vector between the derived motion vector and the predicted motion vector; and
The encoding step includes
A binarization step for binarizing the difference vector;
A context calculation step of calculating a context index of the difference vector based on at least the reference picture;
And an arithmetic encoding step of arithmetically encoding the binarized difference vector using a symbol occurrence probability corresponding to the calculated context index.
The image coding method according to claim 1, wherein in the context calculation step, the context index is calculated so that the context index changes depending on whether or not the reference picture is an inter-view reference picture.
In the context calculating step, the context index is calculated so that only the vertical component of the vertical component and horizontal component of the difference vector changes depending on whether the reference picture is an inter-view reference picture or not. The image encoding method according to claim 2.
The image encoding method according to any one of claims 1 to 3, wherein in the context calculation step, the context index is calculated so that the context index changes for each reference picture list in which the reference picture is specified.
The image coding method according to claim 1, wherein in the context calculation step, the context index is calculated so that the context index changes for each reference picture.
The encoding step further comprises:
The update step of updating a symbol occurrence probability corresponding to the calculated context index based on a binary symbol included in the binarized difference vector, according to any one of claims 1 to 5. Image coding method.
An image decoding method for restoring a motion vector of a decoding target block in order to decode a plurality of pictures encoded for each block,
A decoding step of decoding the encoded difference vector;
A motion prediction step for predicting a motion vector of a decoding target block based on a motion vector of the decoded block;
Restoring the motion vector of the block to be decoded with respect to a reference picture by adding the decoded difference vector and the predicted motion vector; and
The decoding step includes
Calculating a context index of the encoded difference vector based on at least the reference picture;
An arithmetic decoding step of arithmetically decoding the encoded difference vector using a symbol occurrence probability corresponding to the calculated context index;
An image decoding method comprising: an inverse binarizing step for inverse binarizing the arithmetically decoded difference vector.
The image decoding method according to claim 7, wherein in the context calculating step, the context index is calculated so that the context index changes depending on whether or not the reference picture is an inter-view reference picture.
In the context calculating step, the context index is calculated so that only the vertical component of the vertical component and horizontal component of the difference vector changes depending on whether the reference picture is an inter-view reference picture or not. The image decoding method according to claim 8.
The image decoding method according to any one of claims 7 to 9, wherein in the context calculating step, the context index is calculated so that the context index changes for each reference picture list in which the reference picture is specified.
The image decoding method according to claim 7, wherein in the context calculating step, the context index is calculated so that the context index changes for each reference picture.
The decoding step further comprises:
The image according to any one of claims 7 to 11, further comprising an update step of updating a symbol occurrence probability corresponding to the calculated context index based on a binary symbol included in the arithmetically decoded difference vector. Decryption method.
An image encoding device that encodes a motion vector of an encoding target block in order to encode a plurality of pictures for each block,
A motion detection unit that derives a motion vector of an encoding target block with respect to a reference picture by performing motion detection;
A motion prediction unit that predicts a motion vector of the encoding target block based on a motion vector of the encoded block;
An encoding unit that encodes a difference vector between the derived motion vector and the predicted motion vector;
The encoding unit includes:
A binarization unit for binarizing the difference vector;
A context controller that calculates a context index of the difference vector based on at least the reference picture;
An image encoding device comprising: an arithmetic encoding unit that arithmetically encodes the binarized difference vector using a symbol occurrence probability corresponding to the calculated context index.
An image decoding apparatus for restoring a motion vector of a decoding target block in order to decode a plurality of pictures encoded for each block,
A decoding unit for decoding the encoded difference vector;
A motion prediction unit that predicts a motion vector of a decoding target block based on a motion vector of a decoded block;
A restoration unit for restoring the motion vector of the block to be decoded with respect to a reference picture by adding the decoded difference vector and the predicted motion vector;
The decoding unit
A context controller that calculates a context index of the encoded difference vector based on at least the reference picture;
An arithmetic decoding unit that arithmetically decodes the encoded difference vector using a symbol occurrence probability corresponding to the calculated context index;
An image decoding apparatus comprising: an inverse binarization unit that inversely binarizes the arithmetically decoded difference vector.
An image encoding device according to claim 13,
An image encoding / decoding device comprising the image decoding device according to claim 14.