WO2011034148A1 - Encoder apparatus, decoder apparatus, moving image encoder apparatus, moving image decoder apparatus, and encoding data - Google Patents

Abstract

An encoder apparatus comprises: an MV flag deciding unit (1115) that extracts, by use of information as to which PMV was selected from among a plurality of PMV candidates, MV candidates, which exist in an area where MV possibly exists, from among tentative MV candidates; and an MV index encoding unit (1153) that, if there are two or more MV indices determining the MV candidates extracted by the MV flag deciding unit (1115), encodes each of the MV indices.

Description

Encoding device, decoding device, moving image encoding device, moving image decoding device, and encoded data

The present invention mainly relates to a moving picture coding apparatus and a moving picture decoding apparatus that efficiently encode motion vectors.

In the field of video coding technology, image data is generally divided into a plurality of blocks, and coding is performed in units of divided blocks. In block unit coding, generation of a prediction signal of an input signal, calculation of a residual signal which is a difference between the input signal and the prediction signal, conversion of the calculated residual signal, quantization of conversion coefficients obtained by the conversion, Coding processing such as variable length coding of the quantized transform coefficients is performed.

Methods of generating a prediction signal include intra prediction using a reproduced image around a target block and inter prediction using a reproduced image of a frame already encoded / decoded.

Intra prediction includes a plurality of intra prediction modes such as DC prediction, horizontal prediction, vertical prediction, and information indicating which intra prediction mode to use is encoded.

In inter prediction, a frame ID for specifying a reference frame to be used for prediction and a motion vector (MV) are encoded.

The coding of the MV is performed by first calculating a motion vector predictor (PMV), which is a predicted value of the MV, and then coding the difference between the PMV and the MV. FIG. 16 is a diagram showing the configuration of the MV encoded data of Non-Patent Document 1. As shown in FIG. As shown in FIG. 16, MV is divided into PMV index indicating PMV, absolute value of difference between PMV and MV (MVD absolute value), and MVD code indicating whether the difference is positive or negative. Ru. The MVD absolute value and the MVD code are encoded in the order of the X component and the Y component, and the MVD code is not encoded when the MVD absolute value of each component is zero.

Here, the MVD absolute value is binarized and efficiently encoded by an arithmetic code using an adaptive probability. Although the MVD code is also binarized and encoded by the arithmetic code, in Non-Patent Document 1, the occurrence probability of 0 and 1 of the binarized code is always 0.5, and as a result of encoding, The code amount is equal to that in the fixed length coding.

Non-Patent Document 2 discloses a method of encoding MV as it is without separately encoding into an MVD absolute value and an MVD code. In this method, the existence probability of MV is estimated with a model using the sum of distribution functions using generalized Gaussian functions by calculating the distance between PMV and MV for each of a plurality of PMVs and using those distances. , Encode using a multilevel arithmetic code using the probability calculated from the estimated model.

In addition, Non-Patent Document 1 discloses a technique called MotionVectorCompetition (MVCOMP). In MVCOMP, coding efficiency is improved by using a plurality of motion vector predictor candidates (PMV candidates). Specifically, a PMV close to the MV to be encoded is selected from the PMV candidates, and an index (PMV index) specifying the PMV candidate is encoded. Next, the difference between PMV and MV is encoded. In MVCOMP, by selecting a suitable PMV from a plurality of PMV candidates, the difference between MV and PMV can be made smaller than in the case where one PMV is used, so the code amount of the difference can be reduced.

In Non-Patent Document 1, which calculates a plurality of motion vector predictor candidates (PMV candidates), selects one motion vector predictor (PMV) from the PMV candidates, and encodes the difference between the motion vector (MV) and the PMV. In the MV coding, since the information of the selected PMV is not used for the coding of the difference between the MV and the PMV, the code amount is large.

More specifically, the efficiency is lowered because the relationship between the selected PMV and the PMV candidate does not use the property that the possible region of the coding target MV is limited.

Furthermore, in the MV coding of Non-Patent Document 1, the MVD absolute value, which is the absolute value of the difference between PMV and MV, is efficiently coded by arithmetic coding using adaptive probability. EFFICIENT CODING did not occur because the fixed probability is used for the coding of parts other than the MVD absolute value.

On the other hand, in MV coding of Non-Patent Document 2, since MVD absolute values are not used, coding can be performed according to the existence probability of MV, but parameters for determining the characteristics of the distribution function in advance (for example, generalization Since it is necessary to calculate the standard deviation and shape parameter of the Gaussian function, it has been difficult to apply the MV coding of Non-Patent Document 2 to any image. In addition, since it is necessary to repeatedly calculate the value of the cumulative distribution function, there is a problem that the amount of computation is large even using the table reference described in Non-Patent Document 2. In addition, although the magnitude of the MVD absolute value tends to be spatially correlated, it is difficult to utilize such a tendency because the MVD absolute value is not separated.

In order to solve the above-mentioned subject, the present invention is provided with the following features. That is,
The encoding apparatus of the present invention generates prediction data from already encoded data when encoding predetermined data, and encodes a difference absolute value between the predetermined data and the prediction data. When the number of data candidates calculated by the encoding unit, the data candidate calculation unit for calculating data candidates from the difference absolute value and the prediction data, and the data candidate calculation unit is two or more, each data candidate And a data candidate identification flag encoding unit configured to set different flags to and encode the flag set for each data candidate.

The encoding apparatus according to the present invention generates, when encoding predetermined data, a plurality of prediction data candidates from already encoded data, and selects prediction data to be used for encoding from the prediction data candidates. A determination unit; a difference absolute value encoding unit encoding a difference absolute value between the predetermined data and the prediction data; a data candidate calculation unit calculating data candidates from the difference absolute value and the prediction data; And a data candidate determination unit that determines the validity of the data candidate calculated from the difference absolute value and the prediction data from the prediction data and the prediction data candidate, and the data candidate determined as valid by the data candidate determination unit The data candidate identification flag encoding unit may encode a flag that identifies the data candidate if the number is two or more.

The encoding apparatus according to the present invention generates, when encoding predetermined data, a plurality of prediction data candidates from already encoded data, and selects prediction data to be used for encoding from the prediction data candidates. A determination unit, and a difference absolute value encoding unit encoding the difference absolute value by arithmetically encoding the symbol sequence while setting the difference absolute value between the predetermined data and the prediction data as a symbol sequence; The difference absolute value encoding unit changes the appearance probability of each symbol used to arithmetically encode the symbol string according to the prediction data selected by the prediction data determination unit.

Also, the decoding device of the present invention generates a prediction data from the already encoded data, and a difference absolute value decoding unit that decodes the encoded difference absolute value when decoding predetermined data; The data candidate calculation unit that calculates data candidates from the value and the prediction data, and the number of data candidates generated by the data candidate calculation unit are different for each data candidate for each data candidate when the number of data candidates is two or more And a data candidate identification flag decoding unit that decodes a flag for which a value is set.

When decoding predetermined data, the decoding device according to the present invention decodes the encoded difference absolute value, generates a plurality of prediction data candidates from already encoded data, and generates a code from among the prediction data candidates A prediction data determination unit that selects prediction data to be used for quantization; a data candidate determination unit that determines the validity of data candidates calculated from the difference absolute value and the prediction data from the prediction data and the prediction data candidates; The data candidate identification flag decoding unit is configured to decode a flag that identifies the data candidate when the number of data candidates validated by the data candidate determination unit is two or more.

The decoding device according to the present invention generates a plurality of prediction data candidates from already encoded data when decoding predetermined data, and selects a prediction data determination unit that selects prediction data to be used for decoding from the prediction data candidates. A difference absolute value decoding unit that decodes the difference absolute value by arithmetically decoding a symbol string that is the difference absolute value between the predetermined data and the prediction data, the difference absolute value decoding unit including: The appearance probability of each symbol used to decode the symbol string is changed according to the prediction data selected by the prediction data determination unit.

By limiting the possible region of the motion vector using information on which prediction motion vector is selected from the plurality of motion vector predictor candidates, the restriction is used to encode or decode the motion vector, The code amount of the motion vector in the encoded data can be reduced. By reducing the code amount of the motion vector, coding efficiency in moving picture coding is improved.

FIG. 1 is a block diagram of a moving picture coding apparatus 100 according to a first embodiment of the present invention. It is a block diagram of the moving image decoding apparatus 200 of the 2nd Embodiment of this invention. It is a block diagram of motion vector encoding part 111 of a 1st embodiment of the present invention. It is a block diagram of the motion vector decoding part 211 of the 2nd Embodiment of this invention. It is a block diagram of the MV flag determination part 1115 by the 1st Embodiment of this invention. FIG. 10 is a block diagram of an MV selection unit 2115 according to a second embodiment of the present invention. It is a figure which shows the operation | movement flow of the MV candidate calculation part 5001 by the 1st, 2nd embodiment of this invention. It is a figure which shows the operation | movement flow of the MV candidate determination part 5002 by the 1st, 2nd embodiment of this invention. It is a figure which shows the operation | movement flow of the MV index determination part 5003 by the 1st Embodiment of this invention. It is a figure explaining the prediction motion vector of this invention. It is a figure explaining the example of the possible existence area | region of MV of this invention. It is a figure explaining another example of the possible existence area of MV of the present invention. It is a figure explaining another example of the possible existence area of MV of the present invention. It is a figure explaining the relationship between the possible area | region of MV of this invention, and MV candidate. It is a figure which shows the structure of the coding data of MV of this invention. It is a figure which shows the structure of the coding data of conventional MV. It is a block diagram of moving picture coding device 100 'of a 3rd embodiment of the present invention. It is a block diagram of motion vector encoding part 111 'of the 3rd Embodiment of this invention. It is a block diagram of the principal part which comprises the moving picture encoding device of the 3rd Embodiment of this invention. (A) shows the MV flag determination part 1115 'by 3rd Embodiment of this invention, (b) has shown the MV candidate sort part 5004. FIG. It is a block diagram of moving image decoding apparatus 200 'of the 4th Embodiment of this invention. It is a block diagram of motion vector decoding part 211 'of the 4th Embodiment of this invention. FIG. 20 is a block diagram of an MV selection unit 2115 'according to a fourth embodiment of the present invention. It is another figure which shows the structure of the coding data of MV of this invention. It is a schematic diagram which shows the 3rd Embodiment of this invention, and shows how to determine the value of the binary data allocated to each MV index. (A) schematically shows the relationship between PMV candidates and MV candidates that are likely to be selected, and (b) shows an example of binary data to be the value of the MV index to be arithmetically encoded. It is a block diagram of moving picture coding device 100 "of a 5th embodiment of the present invention. It is a block diagram of the variable-length-coding part 115 'of the 5th Embodiment of this invention. FIG. 21 is a block diagram of an MVD absolute value coding unit 1152 ′ according to a fifth embodiment of the present invention.

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

(Video encoding device)
FIG. 1 is a block diagram showing the configuration of a moving picture coding apparatus 100 according to the first embodiment of the present invention. The moving picture coding apparatus 100 includes a motion vector coding unit 111, a conversion unit 112, a quantization unit 113, a variable length coding unit 115, an inverse quantization unit 116, an inverse conversion unit 117, a frame memory 118, and an intra prediction unit 121. The inter prediction unit 123, the motion estimation unit 124, the prediction mode determination unit 125, the subtraction unit 101, and the addition unit 102 are included. Further, reference numeral 103 in the figure is a local decoded signal extracted from the frame memory 118.

In the moving picture coding apparatus 100, input image data is divided into a plurality of blocks, and coding is performed in units of divided blocks. In block-based coding, using the prediction signal obtained as the output of the prediction mode determination unit 125, the subtraction unit 101 calculates a residual signal that is the difference between the input signal and the prediction signal. The residual signal is converted into a transform coefficient by DCT or the like in the transform unit 112, and the transform coefficient is further quantized in the quantization unit 113. On the other hand, the quantized transform coefficients are input to the variable-length coding unit 115 and encoded. On the other hand, the quantization transformation coefficient is inversely quantized by the inverse quantization unit 116, and inverse transformation is performed by the inverse transformation unit 117 to obtain a decoded residual signal. The decoded residual signal is added to the prediction signal by the adder 102 and stored in the frame memory 118 as a local decoded signal.

(Generation of prediction signal)
Generation of a prediction signal is performed in the following procedure. The intra prediction unit 121 generates an intra prediction signal which is a prediction signal of the input signal, and calculates a coding cost for evaluating the goodness of prediction from the intra prediction signal and the input signal. The intra prediction signal and the coding cost (intra prediction cost) are input to the prediction mode determination unit 125.

As the coding cost, the sum of absolute differences between the input signal and the prediction signal may be used, or the sum of squared differences may be used. Furthermore, the code amount of the prediction parameter may be taken into consideration.

The inter prediction unit 123 receives a frame ID for specifying the reference frame, which is input from the motion estimation unit 124, and a motion vector (MV) indicating the extraction position on the reference frame as a relative position from the encoding target block. Generate an inter prediction signal. The generated inter prediction signal is input to the motion estimation unit 124 and the prediction mode determination unit 125.

The motion estimation unit 124 performs coding for evaluating the goodness of prediction using the inter prediction signal generated by the inter prediction unit 123 for a predetermined frame ID and a prediction parameter within the predetermined MV range. Calculate the cost.

Then, the motion estimation unit 124 inputs, to the prediction mode determination unit 125, among the above-mentioned prediction parameters, the prediction parameter that minimizes the calculated coding cost and the cost at that time (inter prediction cost).

The prediction mode determination unit 125 compares the intra prediction cost and the inter prediction cost, and selects the prediction mode with the smaller cost. The selected prediction mode and prediction parameters are input to the variable-length coding unit 115. Further, the prediction signal corresponding to the selected prediction mode is input to the subtraction unit 101 and the addition unit 102.

(Variable-length coding unit 115)
The variable-length coding unit 115 not only encodes the quantization conversion coefficient, but also encodes the prediction mode and the prediction parameter output from the prediction mode determination unit 125. When the prediction mode is inter prediction, the frame ID of the prediction parameters is encoded by the variable-length coding unit 115. The motion vector coding unit 111 performs processing necessary for coding the MV, and the variable-length coding unit 115 codes it as coded data.

(Motion vector encoding unit 111)
As shown in FIG. 3, the motion vector encoding unit 111 includes an MV storage unit 1111, a PMV candidate calculation unit 1112, a PMV determination unit 1113, an MVD calculation unit 1114, and an MV flag determination unit 1115. Reference numeral 301 in the figure indicates PMV candidates and the number of PMV candidates, and 302 indicates PMV.

The MV storage unit 1111 stores the MV input to the motion vector encoding unit 111. The PMV candidate calculation unit 1112 refers to the MV stored in the MV storage unit 1111 to calculate a motion vector predictor candidate (PMV candidate). The calculated PMV candidate and the number of PMV candidates are input to the PMV determination unit 1113 and the MV flag determination unit 1115. The number of PMV candidates is also input to a PMV index coding unit 1151 provided inside the variable length coding unit 115.

The PMV determination unit 1113 receives the MV, the PMV candidate, and the PMV candidate number, and among PMV candidates, the PMV candidate that minimizes the cost function PMVCOST (MV, PMV) calculated from the MV and the PMV candidate is regarded as a PMV. select. A flag (PMV index) for specifying the selected PMV is input to the PMV index encoding unit 1151, and the PMV index encoding unit 1151 encodes the PMV index based on the number of PMV candidates (described later) . The selected PMV is input to the MVD calculation unit 1114 and the MV flag determination unit 1115.

The MVD calculation unit 1114 calculates the absolute value (MVD absolute value) of the difference (MVD) between the input MV and PMV, and the MVD absolute value coding unit 1152 and the MV flag determination unit in the variable length coding unit 115 Enter 1115. The MVD absolute value encoding unit 1152 encodes the MVD absolute value.

The MV flag determination unit 1115 calculates the MV candidate and the MV candidate number from the input MV, PMV, PMV candidate, and PMV candidate number, and further, a flag (MV for specifying the MV from among the calculated MV candidates. Determine the index). The number of MV candidates and the MV index are input to the MV index coding unit 1153 in the variable-length coding unit 115. The MV index encoding unit 1153 encodes the MV index based on the number of MV candidates.

(Coding of PMV index and MV index)
The PMV index and the MV index are each coded according to the number of candidates.

Specifically, when the number of candidates is 1, the index is not encoded. When the number of candidates is 2, "0" or "1" is encoded in binary. When the number of candidates is 3, one of “0”, “10” and “11” is encoded. When the number of candidates is 4, any one of "00", "01", "10" and "11" is encoded. If there is a bias in the ratio of selection of each candidate, one of “0”, “10”, “110” and “111” may be encoded when the number of candidates is four. . Although binary encoding may use a fixed-length code in which the above-mentioned value is used as encoded data as it is, it is more preferable to use an arithmetic code which adaptively changes the occurrence probability of 0 and 1.

Hereinafter, the calculation method of the PMV candidate and the function PMVCOST will be described, and the possible region of the MV, which is the point of the present invention, will be described. Finally, the details of the MV flag determination unit 1115 will be described.

(Method of calculating PMV candidate)
FIG. 10 is a diagram for explaining a method of calculating PMV candidates. The MVs of the blocks adjacent to the left, upper and upper right of the block to be encoded are represented as mv_a, mv_b and mv_c, respectively. Also, the MV of the block spatially at the same position on the encoding target block and the reference image is expressed as mv_col. Also, the median value of the MVs of spatially adjacent blocks is expressed as mv_med. Specifically, calculation is performed by taking median values for each of the X component and the Y component of mv_a, mv_b, and mv_c.

Although it is preferable to use mv_med and mv_a or mv_med and mv_col as PMV candidates, the PMV candidates of the present invention are not limited to the above two, and the number of PMV candidates and PMV candidates are as PMV candidates. Other values can also be used. For example, the PMV candidate calculation unit 1112 may set three of mv_med, mv_a, and mv_col as PMV candidates.

(Function PMVCOST)
The function PMVCOST (MV, PMV) is a function that inputs MV and PMV and calculates a cost corresponding to the distance between MV and PMV. When coding an MV using a PMV, it is possible to reduce the amount of coding of the MV by selecting a PMV closer to the MV. The function PMVCOST calculates this distance.

PMVCOST is a function calculated from an MVD absolute value which is a difference absolute value between MV and PMV. That is, using arbitrary functions F and G,
PMVCOST = F (| MV_X-PMV_X |) + G (| MV_Y-PMV_Y |)
Let be a function that can be expressed by Here, | is a symbol indicating an absolute value. By defining the cost as such a function, even if MV and PMV can not be obtained, the cost can be calculated if an MVD absolute value, which is the difference between MV and PMV, is obtained.

For example, city value distance PMVCOST = | MV_X-PMV_X | + | MV_Y-PMV_Y |
Alternatively, Euclidean distance squared PMVCOST = | MV_X-PMV_X | ^ 2 + | MV_Y-PMV_Y | ^ 2
Can be used as the distance.

Also, as another distance, a cost function in which the code amount of the MV is considered can be considered. More specifically,
It is calculated by PMVCOST = R (| MV_X-PMV_X |) + R (| MV_Y-PMV_Y |). Here, R (X) is a function which receives the difference absolute value of MV as X and calculates the code amount or the amount corresponding to the code amount.

The distribution of MVD absolute values (= X) often concentrates around X = 0. In this case, it is preferable to use a code such that the code amount is a function R (X) such that the degree of increase decreases as X increases. Therefore, it is better to use LOG (X + 1) as R (X). Further, when the MVD absolute value X is 0, coding for indicating plus or minus is unnecessary, and therefore, the MVD can be encoded by one bit less than when the MVD absolute value X is other than 0. Taking this property into consideration, it is also preferable to use R (X) = 1 (when X is 0) and R (X) = X + 2 (when X is other than 0).

(Available area of MV)
FIG. 11 is a diagram for explaining the possible existence area of the MV when the number of PMV candidates is two. The PMV candidate calculation unit 1112 calculates PMV1 and PMV2 as PMV candidates, and the PMV determination unit 1113 shows a state where PMV1 is selected as the PMV. In addition, the city value distance is used for PMVCOST. The fact that PMV1 is selected by the PMV determination unit 1113 means that the distance between MV and PMV1 is equal to or smaller than the distance between MV and PMV2 with PMVCOST as the distance. That is,
PMVCOST (MV, PMV1) <= PMVCOST (MV, PMV2)
Is true. Therefore, the possible existence area of MV is limited to the above-mentioned area (shaded area in FIG. 11).

When PMVCOST is a city value distance, a line dividing the possible region of MV and the other region is a vertical bisector L1 of PMV1 and PMV2.

FIG. 12 is a diagram for explaining the possible existence area of the MV when the number of PMV candidates is three. Also in this case, the existence possible region of MV (hatched region in FIG. 12) is the following two expressions PMVCOST (MV, PMV1) <= PMVCOST (MV, PMV2)
PMVCOST (MV, PMV1) <= PMVCOST (MV, PMV3)
It is limited to the area in which both of them hold. As described above, when the number of PMV candidates is m (m is an integer of 1 or more), the possible region of MV is limited as a solution of simultaneous equations including m-1 inequalities.

FIG. 13 is a diagram showing a case where PMVCOST is not a city value distance. As shown in the figure, when PMVCOST is not a city-value distance, a line dividing the possible region of MV and the other region may be a curve. Although not shown, the line is not limited to a smooth curve but may be a broken line.

(MV flag determination unit 1115)
FIG. 5 is a block diagram showing a configuration of the MV flag determination unit 1115. The MV flag determination unit 1115 includes an MV candidate calculation unit 5001, an MV candidate determination unit 5002, and an MV index determination unit 5003. In the MV flag determination unit 1115, information on PMV, the difference absolute value (MVD absolute value) between PMV and MV is known.

FIG. 14 is a diagram showing the relationship between the MV candidate and the MV's possible existence area when the number of PMV candidates is 2 (PMV1 and PMV2). In the information of only the PMV and the MVD absolute value, the MV candidate usually includes four MV candidates of MV1 to MV4 (when both the X component and the Y component of the MVD absolute value are other than 0). Therefore, in order to specify an MV from PMV and MVD absolute values, an MV index for specifying one of four MV candidates is required. At this time, the code amount required to specify an MV from the four MV candidates is 2 bits.

Now, if the PMV to be encoded is PMV1, and the possible region of MV is limited as in FIG. 11, MV4 deviates from the possible region of MV in FIG. If the MV candidate outside the possible region of MV is excluded, the number of effective MV candidates is three. In this case, the amount of code required for coding the MV index can be reduced to 2 bits or less.

Hereinafter, in order to distinguish between an MV candidate determined from PMV and an MVD absolute value and an MV candidate within the MV's possible region among the aforementioned MV candidates, the former is regarded as a temporary MV candidate, and the latter is regarded as an MV candidate. I will call it.

(MV candidate calculation unit 5001)
The MV candidate calculation unit 5001 receives the PMV and the MVD absolute value, and calculates the number of temporary MV candidates and temporary MV candidates. FIG. 7 is a flowchart showing an operation flow of the MV candidate calculation unit 5001. The MVD absolute value and the X component and the Y component of PMV are expressed as (mvd_x, mvd_y) and (pmv_x, pmv_y), respectively.

S701 If mvd_x == 0 and mvd_y == 0, the process proceeds to S702, and if not, the process proceeds to S703.

S702 The temporary MV candidate number n is set to 1, and the temporary MV candidate tMV1 is calculated by the following.

tMV1 = (pmv_x, pmv_y)
S703 If mvd_x == 0, the process proceeds to S704, and if not, the process proceeds to S705.

S704 The temporary MV candidate number n is set to 2, and temporary MV candidates tMV1 and tMV2 are calculated by the following.

tMV1 = (pmv_x, pmv_y + mvd_x)
tMV2 = (pmv_x, pmv_y-mvd_x)
S705 If mvd_y == 0, the process proceeds to S706, and if not, the process proceeds to S707.

S706 The temporary MV candidate number n is set to 2, and temporary MV candidates tMV1 and tMV2 are calculated by the following.

tMV1 = (pmv_x + mvd_x, pmv_y)
tMV2 = (pmv_x−mvd_x, pmv_y)
S707 The temporary MV candidate number n is 4, and temporary MV candidates tMV1, tMV2, tMV3, and tMV4 are calculated by the following.

tMV1 = (pmv_x + mvd_x, pmv_y + mvd_y)
tMV2 = (pmv_x + mvd_x, pmv_y−mvd_y)
tMV3 = (pmv_x−mvd_x, pmv_y + mvd_y)
tMV4 = (pmv_x−mvd_x, pmv_y−mvd_y)
(MV candidate determination unit 5002)
The MV candidate determination unit 5002 receives the PMV, the provisional MV candidate, the number of provisional MV candidates, and the MVD absolute value, and determines whether or not the provisional MV candidate is in the possible existence area of the MV. By this determination, the MV candidate and the number of MV candidates obtained by excluding the temporary MV candidate outside the possible region of the MV are output to the MV index determination unit 5003.

FIG. 8 is a flowchart showing an operation flow of the MV candidate determination unit 5002.

In S801, the distance min_dist between PMV and MV is calculated using the cost function PMVCOST used in the PMV determination unit 1113. Although the MV is not input to the MV candidate determination unit 5002, as described above, the function PMVCOST can be calculated from the MVD absolute value which is the difference absolute value between PMV and MV.

The distance between the provisional MV candidate and the PMV candidate is always min_dist or more when the provisional MV candidate is in the MV possible region. Conversely, if the distance between the temporary MV candidate and the PMV candidate is less than min_dist, the temporary PMV candidate can be excluded as not being an MV candidate.

In step S802, a variable nn indicating an MV candidate index is initialized to one.

L801 A loop between L802 and S806 is performed n times until i becomes equal to the number of temporary MV candidates n, with the variable i indicating the temporary MV candidate index as a loop variable.

L802 A variable j indicating a PMV candidate index is set as a loop variable, and a loop from S803 to S804 is repeated m times until j becomes equal to the number of PMV candidates m.

In step S803, the distance dist_ij between the temporary MV candidate tMVi indicated by the temporary MV candidate index i and the PMV candidate PMVj indicated by the PMV candidate index j is calculated using the cost function PMVCOST used by the PMV determination unit 1113.

S804 If dist_ij is less than min_dist, the loop of variable j indicating the PMV index (loop of L802) is exited. If not, the loop of L802 is continued. In addition, that dist_ij is less than min_dist means that the tentative MV candidate tMVi is out of the possible range of the MV.

S805 Since the tentative MV candidate tMVi is determined to be in the possible region of MV, it is added to the MV candidate fMV. Specifically, tMVi is substituted for fMVnn.

In step S806, the variable nn indicating the MV candidate index is incremented by one.
According to the above operation flow, the number of candidate MVs nn and the candidate MVs of MV are obtained.

Note that by integrating the MV candidate calculation unit 5001 and the MV candidate determination unit 5002, it is also possible to calculate MV candidates without calculating all of the provisional MV candidates. In this case, the determination in the loop of L802 is performed each time the temporary MV candidates are calculated.

(MV index determination unit 5003)
The MV index determination unit 5003 determines which one of the MV candidates is the MV candidate from the input MV (the MV of the coding target block), the MV candidate, and the number of MV candidates, and determines the MV index indicating it. Do.

FIG. 9 is a flowchart showing an operation flow of the MV index determination unit 5003.

S901 is looped from 1 to the number of MV candidates nn for a loop variable i indicating an index of the L901 MV candidate.

In step S901, it is determined whether the MV candidate fMVi matches the MV. If they match, the processing proceeds to step S902. If they do not match, the loop continues until the loop termination condition.

S 902 substitutes i into the MV index ii.

The MV index ii is obtained by the above operation flow.

FIG. 15 is a diagram showing a configuration of encoded data of MV of the present invention. As shown in FIG. 15, MV is divided into a PMV index indicating PMV, an absolute value of a difference between PMV and MV (MVD absolute value), and an MV index and encoded. The MVD absolute value is encoded in the order of the X component and the Y component. When the number of PMV candidates is one, the PMV index is not encoded, and when the number of MV candidates is one, the MV index is not encoded.

The motion image coding apparatus 100 described above calculates a plurality of PMV candidates as MV predicted values, and selects and codes a PMV suitable for MV coding. The MV can be efficiently encoded by limiting the possible region of the MV using.

More specifically, after encoding the difference absolute value (MVD absolute value) of MV and PMV, excluding those outside the MV's possible existence area from temporary MV candidates determined from PMV and MVD absolute value The MV candidate is limited by and the MV index that uniquely identifies the MV from the limited MV candidate is encoded.

By limiting the possible existence area of the MV, it is possible to reduce the code amount of the MV index for specifying the MV from the MV candidate.

(Decoding device)
FIG. 2 is a block diagram showing the configuration of a moving picture decoding apparatus 200 according to the second embodiment of the present invention. The moving picture decoding apparatus 200 includes a motion vector decoding unit 211, a variable length coding / decoding unit 201, an inverse quantization unit 116, an inverse conversion unit 117, a frame memory 118, an intra prediction unit 121, an inter prediction unit 123, a prediction mode selection unit 225, an adder 102 is included. In addition, the code | symbol 203 in a figure means frame ID of prediction parameters.

Similarly to the moving picture coding apparatus 100, the moving picture decoding apparatus 200 divides input image data into a plurality of blocks, and decoding is performed in units of divided blocks. In block-based decoding, the variable-length coding / decoding unit 201 decodes prediction modes and quantized transform coefficients.

The prediction mode is a mode indicating whether the block is intra prediction or inter prediction. When the prediction mode is inter prediction, the prediction parameters frame ID and MV are decoded. The frame ID is decoded by the variable length coding / decoding unit 201. The MV is subjected to decoding processing by the variable-length coding / decoding unit 201 and the motion vector decoding unit 211.

The intra prediction unit 121 and the inter prediction unit 123 generate an intra prediction signal and an inter prediction signal from the decoded image (reproduced image) stored in the frame memory 118 using the decoded prediction parameter. The generated prediction signal is input to the prediction mode selection unit 225. The prediction mode selection unit 225 selects a prediction signal corresponding to the prediction mode and outputs the selected prediction signal to the addition unit 102.

The decoded quantization transformation coefficient is inverse-quantized by the inverse quantization unit 116, and the inverse transformation unit 117 performs transformation such as inverse DCT, and the decoded residual signal is output to the addition unit 102. The adder 102 adds the prediction signal and the decoded residual signal to generate a local decoded signal. The generated local decoded signal is output to the frame memory 118. The reproduced image output to the frame memory 118 is used as a reference image by the intra prediction unit 121 and the inter prediction unit 123 and is output to the outside of the moving image decoding apparatus 200.

FIG. 4 is a block diagram showing the configuration of the motion vector decoding unit 211. As shown in FIG. The motion vector decoding unit 211 includes an MV storage unit 1111, a PMV candidate calculation unit 1112, a PMV selection unit 2113, and an MV selection unit 2115.

The MV storage unit 1111 stores the MV decoded by the motion vector decoding unit 211. The PMV candidate calculation unit 1112 calculates PMV candidates. The calculated PMV candidate and the number of PMV candidates are input to the PMV selection unit 2113 and the MV selection unit 2115. The PMV candidate number is input to the PMV index decoding unit 2011 in the variable-length coding / decoding unit 201. The PMV index decoding unit 2011 decodes the PMV index using the number of PMV candidates, and inputs the PMV index to the PMV selection unit 2113. The PMV selection unit 2113 selects a candidate indicated by the PMV index from the PMV candidates, and inputs it to the MV selection unit 2115 as a PMV.

Further, following the PMV index, the variable-length coding / decoding unit 201 decodes the MVD absolute value by the internal MVD absolute value decoding unit 2012, and inputs the MVD to the MV selection unit 2115.

FIG. 6 is a block diagram showing the configuration of the MV selection unit 2115. The MV selection unit 2115 includes an MV candidate calculation unit 5001, an MV candidate determination unit 5002, and an MV extraction unit 6004. Since the MV candidate calculation unit 5001 and the MV candidate determination unit 5002 are described in the first embodiment and thus the description thereof is omitted, PMV and PMV candidates among provisional MV candidates calculated from PMV and MVD absolute values by these means are used. Those in the possible region of MV determined (== MV candidate) are calculated. The MV extraction unit 6004 decodes the MV by selecting a candidate indicated by the MV index from the MV candidates.

As described above, in the moving image decoding apparatus 200 described above, the PMV candidate and the PMV are used in a motion vector decoding method in which a plurality of PMV candidates are calculated as predicted values of MV and PMVs suitable for MV coding are selected and used for decoding. The encoded MV can be efficiently decoded by limiting the possible region of the MV.

More specifically, after the difference absolute value (MVD absolute value) between MV and PMV is decoded, those outside the possible region of MV are excluded from the provisional MV candidates determined from PMV and MVD absolute value Thus, the MV candidate is limited, and the MV is decoded by decoding the MV index that specifies the MV from the limited MV candidate.

By limiting the possible existence area of the MV, the MV can be decoded from the encoded data in which the code amount of the MV index necessary to specify the MV from the MV candidate is reduced.

(Video encoding device 100 ')
Next, a moving picture coding apparatus 100 ′ according to a third embodiment of the present invention will be described below with reference to FIGS. 17 to 19 and 23. FIG. 23 is a diagram showing the configuration of MV encoded data. As shown in FIG. 23, the encoded data of MV is composed of "MVD" part and "non-MVD" part.

The moving picture coding apparatus 100 ′ according to the present embodiment performs the arithmetic coding in consideration of the appearance probability of the MV candidate, and thereby the MV which is a flag for specifying the MV candidate as the existence candidate of the MV candidate is higher. The tendency that the code length after encoding of the index becomes short is strengthened, and the code amount of the MV index is reduced compared to the case where the appearance probability is not considered.

That is, the moving picture coding apparatus 100 ′ of the present embodiment further reduces the code amount of the “other than MVD” portion of FIG. 23 as compared to the moving picture coding apparatus 100 of the first embodiment. The code amount of MV coding can be further reduced. Therefore, the moving picture coding apparatus 100 'according to the present embodiment performs an operation of rearranging the MV candidates in the order in which the presence probability of the MV is estimated to be high.

FIG. 17 is a block diagram showing the configuration of a moving picture coding apparatus 100 'according to the third embodiment of the present invention. Similar to the moving picture coding apparatus 100 according to the first embodiment, the moving picture coding apparatus 100 ′ includes a converting unit 112, a quantizing unit 113, a variable length coding unit 115, an inverse quantizing unit 116, and an inverse converting unit. A frame memory 118, an intra prediction unit 121, an inter prediction unit 123, a motion estimation unit 124, a prediction mode determination unit 125, a subtraction unit 101, and an addition unit 102 are provided, but the configuration of the motion vector encoding unit 111 'is This differs from the motion vector encoding unit 111 of the first embodiment. The other members except the motion vector encoding unit 111 ′ perform the same operations as in the first embodiment, and thus the description of these members will be omitted, and the motion vector encoding unit 111 ′ will be described with reference to FIGS. I will refer to and explain.

As shown in FIG. 18, the motion vector encoding unit 111 ′ includes an MV storage unit 1111, a PMV candidate calculation unit 1112, a PMV determination unit 1113, and an MVD calculation unit 1114 like the motion vector encoding unit 111. The MV flag determination unit 1115 'is different from the MV flag determination unit 1115 of the first embodiment.

As shown in (a) of FIG. 19, in the MV flag determination unit 1115 ', an MV candidate sorting unit 5004 is provided between the MV candidate calculation unit 5001 and the MV candidate determination unit 5002. The MV candidate sorting unit 5004 includes an MV candidate cost calculating unit 5004a and a sorting unit 5004b, as shown in (b) of FIG.

The MV candidate sorting unit 5004 may be provided after the MV candidate determination unit 5002.

The MV candidate sorting unit 5004 receives the number of temporary MV candidates and the number of temporary MV candidates from the MV candidate calculation unit 5001 as an input value. The MV candidate cost calculation unit 5004a of the MV candidate sorting unit 5004 calculates, for each temporary MV candidate, the cost of the temporary MV candidate by using the coordinate value of the temporary MV candidate as an input and applying a function called MVCOST. MVC OST is a function that gives a larger value (or a smaller value) as it is estimated that the appearance probability of the MV candidate is higher, and various functions can be applied. Specifically, it is appropriate that the coordinate value of the MV candidate and the coordinate value of each PMV candidate (or PMV) are input, and the cost value increases as the distance between the provisional MV candidate and the PMV candidate increases. A specific example of such a function will be described later.

Then, the sorting unit 5004b rearranges the provisional MV candidates in ascending order of cost. Alternatively, the sorting unit 5004b may rearrange the provisional MV candidates in descending order of cost.

The MV candidate determination unit 5002 determines an MV candidate from among the provisional MV candidates in the same manner as in the first embodiment, and outputs the number of the MV candidate and the MV candidate to the MV index determination unit 5003.

The MV index determination unit 5003 receives the number of the MV candidate and the MV candidate, and determines the value of the binary data of the MV index to be assigned to each MV candidate. Here, how to determine the value of the binary data to be assigned to each MV index will be described below with reference to FIG.

(A) of FIG. 24 is a schematic diagram showing the relationship between PMV candidates and MV candidates that are easily selected. In FIG. 24, PMV0 indicates that the PMV is selected by the PMV determination unit 1113. Further, MV1 to MV4 indicate MV candidates output from the MV candidate determination unit 5002.

Generally, the smaller the distance between the MV candidate and the PMV candidate other than the selected PMV candidate, the tendency tends to be determined as the MV. The MV index determination unit 5003 uses this tendency to determine the value of binary data of the MV index.

That is, as described later, at the time of arithmetic coding, a high probability is assigned to “0” and a low probability is assigned to “1”. Assign "00" "01" "10" "11" to the MV candidate in the order sorted in the order of (in order of small cost). As a result, as shown in (b) of FIG. 24, "00" is allocated to MV1, "01" to MV2, "10" to MV3, and "11" to MV4.

Then, the MV index determination unit 5003 outputs the determined MV index to the MV index coding unit 1153. Then, the variable-length coding unit 115 performs arithmetic coding on each MV index based on the probabilities assigned to “0” and “1”.

Therefore, in the MV index code word, the code length of the MV1 code word is shortened, and the code length of the MV4 code word is increased. As a result, it can be seen that the average code length of the MV index code word is shorter than in the case of the first embodiment, and the code amount is reduced. Note that the MV index coding unit 1153 may adaptively change the probability assigned to “0” or “1” when performing arithmetic coding.

Also, the variable-length coding unit 115 may assign short codes in the order sorted by the MV candidate sort unit 5004 (in order of small cost) using fixed-length coding. For example, it is possible by allocating “0” “10” “110” “111”.

As described above, when binarization is performed by assigning an MV index according to an MV candidate having a high appearance probability, a method is used to bias the probability of “0” and “1” in the case of arithmetic coding. Can also be applied when the MV candidate determination unit 5002 is not used.

When the MV candidate determination unit 5002 is used, it is more efficient to perform encoding in accordance with the MV candidate having a high appearance probability. For example, when the number of MV candidates becomes 3 by the MV candidate determination unit 5002, a short code (or an arithmetic code) for an MV candidate having a high appearance probability, such as “0”, “10”, and “11” The code amount can be reduced by allocating a binary number sequence.

Also, when the number of MV candidates is not an integral power of 2 as in the case where the number of MV candidates is 3, generally the code or binary sequence corresponding to the MV candidate has an unequal length. In this case, the effectiveness of the process of allocating an MV index according to the appearance probability of the MV candidate is large. Taking this property into consideration, this process is applied only when it is most effective, that is, sorting of MV candidates is performed only when the number of MV candidates meets a specific condition (for example, when it is not an integral power of 2). It is also possible to do. Since this process requires the number of MV candidates determined to be valid, the MV candidate sorting unit 5004 is provided after the MV candidate determination unit 5002.

In the process of assigning the value of the MV index in accordance with the MV candidate having a high appearance probability, it is not necessary to use the literal sort of the MV candidate. If the number of MV candidates is at most about four, processing can be easily performed by combining a plurality of conditional branches.

For example, whether the MV candidate cost is in the order of cost A, cost B, cost C, and cost D is cost A <= cost B <= cost C <= cost D,
IF (cost A <= cost B and cost B <= cost C and cost C <= cost D)
It can be judged by the conditional branch statement. When the condition is satisfied, “00”, “01”, “10”, and “11” are assigned to the corresponding MV index, that is, the MV candidate of the cost A to the cost D. Whether it is another order or not can be easily implemented by arranging similar conditional branch statements.

In this case, the sorting unit 5004 b becomes unnecessary, and the MV index determination unit 5003 performs the MV index determination by the conditional branch using the MV candidate cost as described above.

In addition, if the process is performed in the order of the MV candidate costs for the minimum (or the maximum) N MV candidate costs instead of the order of the MV candidate costs, the process becomes easier. For example, the process of calculating the MV candidate with the MV candidate cost minimum (or maximum) and allocating a specific MV index can be realized only by the process of specifying the MV candidate of the minimum value and can be realized with an extremely simple configuration.

The present invention also includes such a simplified configuration that does not perform complete ordering of the MV candidates.

(Specific example of the MVCOST function)
The following functions 1 to 4 can be considered as specific examples of the MVCOST function.
Function 1: MV candidate Cost _{= Σ (| mv_x-pmv i} _x | + | mv_y-pmv i _y |) (i: 1 ~ N, PMV candidate pmv _i is not selected)
Function 1': MV candidate Cost _{= Σ ((mv_x-pmv i} _x) ^ 2 + (mv_y-pmv i _y) ^ 2) (i: 1 ~ N, pmv i is PMV candidates that were not selected, ^ squared Show)
Function 2: MV candidate cost = | mv_x | + | mv_y |
Function 3: MV candidate cost = | mv_x-pmv ₀ _x | + | mv_y-pmv ₀ _y | (pmv ₀ is a selected PMV candidate)
Function 4: MV candidate Cost _{= MIN (| mv_x-pmv i} _x | + | mv_y-pmv i _y |) (i: 1 ~ N, PMV candidate pmv _i is not selected)
The MVCOST function to be used is preferably function 1, but function 1 'or functions 2 to 4 may be used. Also, the function used as the MVCOST function may be changed according to the frame type. For example, function 1 may be used as the MVC OST function in P frame, and function 2 may be used as the MVC OST function in B frame. As described later, the MV index coding unit 1153 may code information indicating the MVCOST function used by the MV candidate cost calculation unit 5004a and record the coded information in the header of the coded data.

The PMV used for MV candidate cost calculation (input to the MVC OST function) need not be limited to the PMV candidates calculated by the PMV candidate calculation unit 1112, that is, PMV candidates to be selected by the PMV index (so Not "PMV candidate used for candidate cost calculation" but simply "PMV used for MV candidate cost calculation". For example, when mv_med and mv_col are calculated as PMV candidates in the PMV candidate calculation unit 1112, PMVs used for MV candidate cost calculation may be mv_med, mv_col, and mv_a.

It is necessary to limit the number of PMV candidates to a small number (2 is appropriate) in order to reduce the code amount of PMV index, but to estimate the appearance probability of MV candidates It is because there is no restriction.

Note that a PMV completely different from the PMV candidate to be selected by the PMV index, for example, mv_a may be a PMV candidate that is used for MV candidate cost calculation. Thus, considering PMV, function 2 is identical to using {0, 0} as PMV.

The PMV for calculating the MV candidate cost may be configured to use the PMV candidate of the PMV candidate calculating unit 1112 as it is as described above, or the PMV candidate calculating unit 1112 may be used for calculating the MV candidate cost separately from the PMV candidate. It may be configured to calculate PMV. Further, the motion vector encoding unit 111 ′ may be provided with means for calculating PMV different from the PMV candidate calculation unit 1112.

In this case, it is not an encoder / decoder that calculates a plurality of PMV candidates, selects a PMV suitable for MV coding, and encodes / decodes the difference between MV and PMV, but calculates a single PMV to calculate MV The present invention is also applicable to an encoding apparatus / decoding apparatus that encodes / decodes the difference between the and PMV. In this case, the configuration can also be realized by a configuration of a coding device that does not include the PMV candidate calculation unit 1112, the PMV determination unit 1113, the PMV index coding unit 1151, and the MV candidate determination unit 5002.

(About the PMVCOST function used by the PMV determination unit 1113)
As described above, the PMV determination unit 1113 receives the MV, the PMV candidate, and the PMV candidate number, and among the PMV candidates, selects a candidate for minimizing the cost function PMVCOST (MV, PMV) calculated from the MV and PMV. Although the PMV is selected as the PMV, the PMV determination unit 1113 may dynamically change the function used as the PMVCOST function according to the load condition of the motion vector encoding unit 111.

That is, as described above, although various functions can be applied as the PMVCOST function, among them, there is no change in the coding efficiency or the calculation amount such as PMVCOST = 0, PMVCOST = | MV_X-PMV_X | + Coding efficiency does not improve so much like | MV_Y-PMV_Y |, but the amount of computation is small, but PMVCOST = R (| MV_X-PMV_X |) + R (| MV_Y-PMV_Y |) greatly improves coding efficiency However, there are various things such as a large amount of calculation. Therefore, according to the load condition of the motion vector encoding unit 111, the PMV determination unit 1113 uses a function with high encoding efficiency when the load is light, and the operation amount when the load is a certain level or more. The PMV may be selected using a small function of In this case, the MV index encoding unit 1151 encodes information (flag) indicating the PMVCOST function used by the PMV determination unit 1113 and records the encoded information in the header of the encoded data. The header to be recorded may be a sequence header, a picture header, a slice header, an MB header or the like. There is also a method of coding data called sequence parameters and picture parameters first and coding and specifying the data by index for each sequence and picture without coding the header for each sequence or picture. Since such data is also treated as a header, a flag indicating a function may be encoded with these data.

As described above, by making the PMV selectable in accordance with the load condition of the motion vector encoding unit 111, it is possible to balance the encoding efficiency and the operation amount. Also, in order to simplify the configuration of the encoding apparatus or when the load of encoding is high, it is possible to perform encoding not using PMV restrictions by selecting PMVCOST = 0, that is, motion vector code The conversion unit 111 can freely select the PMV without considering the restriction of the PMV.

When selecting the PMVCOST function, it is necessary to use the same function as the PMVCOST function used in the PMV determination unit 1113 also in the MV candidate determination unit 5002. In order to simplify the coding apparatus, when PMVCOST = 0 is always selected in the coding apparatus, the provisional MV candidate becomes the MV candidate as it is, and therefore the coding apparatus is provided with the MV candidate determination unit 5002 for determining the MV candidate. No configuration is also possible.

(About the MVCOST function used by the MV candidate sorting unit 5004)
As for the MVCOST function used in the MV candidate sorting unit 5004, encoding efficiency and operation amount can be obtained by encoding information (flag) indicating the MVCOST function and recording it in the header of encoded data, as in the PMVCOST function. Balance. In the case where there is a strong demand for simplification of the configuration of the encoding device and speeding up of the encoding device, if MVC OST = 0, the sort itself becomes unnecessary and the amount of operation can be reduced.

When the PMVCOST function or the MVCOST function is changed according to the frame type, it is appropriate to encode a flag indicating the MVCOST function for each frame type.

(Decoding device 200 ')
Next, a decoding device 200 ′ according to a fourth embodiment of the present invention will be described below with reference to FIGS. 20 to 22.

FIG. 20 is a block diagram showing the configuration of a decoding apparatus 200 'according to the fourth embodiment of the present invention. Similar to the decoding device 200 of the second embodiment, the decoding device 200 ′ includes the variable-length coding / decoding unit 201, the inverse quantization unit 116, the inverse conversion unit 117, the frame memory 118, the intra prediction unit 121, and the inter prediction unit Although a prediction mode selection unit 225 and an addition unit 102 are provided, the motion vector decoding unit 211 'is different from the motion vector decoding unit 211 of the second embodiment. The other members except for the motion vector decoding unit 211 'perform the same operations as in the second embodiment, and thus the description of these members is omitted, and the motion vector decoding unit 211' is referred to FIG. 21 and FIG. I will explain it.

As shown in FIG. 21, the motion vector decoding unit 211 ′ includes the MV storage unit 1111, the PMV candidate calculation unit 1112, and the PMV selection unit 2113 as in the motion vector decoding unit 211, but the MV selection unit 2115 ′ This differs from the MV selection unit 2115 of the second embodiment.

As shown in FIG. 22, in the MV selection unit 2115 ', an MV candidate sorting unit 5004 is provided between the MV candidate calculation unit 5001 and the MV candidate determination unit 5002.

The MV candidate sorting unit 5004 receives the number of temporary MV candidates and the number of temporary MV candidates from the MV candidate calculation unit 5001 as an input value. The MV candidate sorting unit 5004 performs the same sort as the MV candidate sorting unit 5004 of the MV flag determination unit 1115 '. When the MV candidate sorting unit 5004 of the MV flag determination unit 1115 'dynamically changes the MVCOST function, the MV candidate sorting unit 5004 records the information indicating the MVCOST function recorded in the header of the encoded data. Sorting is performed by decoding and referencing.

When the PMV determination unit 1113 and the MV candidate determination unit 5002 dynamically change the PMVCOST function, the information indicating the PMVCOST function recorded in the header of the encoded data is decoded and the MV candidate determination unit 5002 Make a decision.

Then, the MV candidate determination unit 5002 determines an MV candidate from among the temporary MV candidates by the same method as that of the second embodiment, and outputs the number of the MV candidate and the MV candidate to the MV extraction unit 6004.

Finally, the MV extraction unit 6004 receives the number of the MV candidate and the MV candidate, and decodes the MV by selecting a candidate indicated by the MV index from the MV candidate.

Note that the decoding apparatus that calculates a single PMV and decodes the difference between MV and PMV is a decoding apparatus that does not include the PMV candidate calculation unit 1112, PMV selection unit 2113, PMV index decoding unit 2011, and MV candidate determination unit 5002. It can also be realized by the configuration.

(Moving picture coding apparatus 100 ′ ′)
Finally, a moving picture coding apparatus 100 ′ ′ according to a fifth embodiment of the present invention will be described below with reference to FIGS. 25 to 27.

The moving picture coding apparatus 100 ′ ′ according to the present embodiment improves coding efficiency of the MVD absolute value by adaptively switching the probability (context) used for arithmetic coding of the MVD according to the PMV. .

This switching is based on the observation that the magnitude of the MVD absolute value tends to correspond to the type of PMV used for calculating the MVD. More specifically, when the PMV candidates are mv_med and mv_col, the MVD absolute value tends to be smaller when mv_col is PMV than when mv_med is PMV. In the following configuration, “0” is adaptively applied in the arithmetic code without explicitly incorporating which PMV tends to decrease the MVD absolute value other than the initial value described later. Because the learning probability is "1", the effect can be realized.

25 is a block diagram showing the configuration of a moving picture coding apparatus 100 ′ ′ according to the fifth embodiment of the present invention. The moving picture coding apparatus 100 ′ ′ is the same as the moving picture coding apparatus 100 according to the first embodiment. Similarly, the motion vector encoding unit 111, the conversion unit 112, the quantization unit 113, the inverse quantization unit 116, the inverse conversion unit 117, the frame memory 118, the intra prediction unit 121, the inter prediction unit 123, the motion estimation unit 124, the prediction Although the mode determining unit 125, the subtracting unit 101, and the adding unit 102 are provided, the configuration of the variable-length coding unit 115 'is different from that of the variable-length coding unit 115 according to the first embodiment. The other members except for the variable-length coding unit 115 ′ perform the same operations as in the first embodiment, and thus the description of these members will be omitted, and the variable-length coding unit 115 ′ will be described with reference to FIGS. I will refer to and explain.

As shown in FIG. 26, the variable-length coding unit 115 'includes a PMV index coding unit 1151, an MVD absolute value coding unit 1152', and an MV index coding unit 1153. The PMV index coding unit 1151 and the MV index coding unit 1153 perform the same operations as in the first embodiment, so the MVD absolute value coding unit 1152 ′ will be described.

As shown in FIG. 27, the MVD absolute value coding unit 1152 'includes a context determination unit 1152a, a probability holding unit 1152b, a probability updating unit 1152c, a binarization unit 1152d, and an arithmetic coding unit 1152e.

The binarization unit 1152 d converts the MVD absolute value into a binary sequence of “0” and “1” and outputs the binary number sequence to the arithmetic coding unit 1152 e. The binarization unit 1152 d converts the MVD absolute value “n” into a binary number sequence in which one “0” is added after the n consecutive “1s”. For example, when n is 0, the binary sequence is "0", and when n is 2, the binary sequence is "110".

On the other hand, the context determination unit 1152a outputs, to the probability storage unit 1152b, the context index determined using the value of the PMV index input from the PMV determination unit 1113.

The context index has a value indicating whether it is an X component or a Y component, a value indicating the size of the MVD of the adjacent block already encoded / decoded, and what number binary sequence is processed It is preferable to determine the combination of the value indicating the value of p and the value of the PMV index. That is, 2 components, 3 values indicating the size of the MVD in steps, 3 values indicating in the vicinity of what number in the binary sequence are processed, and the number of PMV candidates is 2 In the case of (2), the context index to be output is determined from 24 context indexes of 2 × 3 × 3 × 2. In this case, the probability holding unit 1152 b is configured to hold twenty four “1” and “0” probabilities. If the value of the PMV index is used, other conditions may be used to determine the context index.

The arithmetic coding unit 1152 e codes a binary number sequence based on the probability of “1” or “0” held in the probability holding unit 1152 b corresponding to the context index input to the probability holding unit 1152 b. This embodiment adaptively encodes a binary number sequence (symbol sequence), that is, when encoding a binary number sequence, the probability of “1” “0” every time each bit is encoded. It is characterized in that it updates the

Regarding this, encoding of a binary number sequence will be described taking an example where the binary number sequence input to the arithmetic coding unit 1152 e is “110”. Note that the probability of “1” before encoding is P ₁ .

The arithmetic coding unit 1152 e codes the first bit “1” of “110” using the probability P ₁ . Then, the arithmetic coding unit 1152 e outputs the coded bit “1” to the probability updating unit 1152 c. The probability update unit 1152 c updates the probability of “1” to P ₂ when the coded bit is input.

Next, the arithmetic coding unit 1152e encodes "1" second bit "110" using the probability P _2. Then, the arithmetic coding unit 1152 e outputs the coded bit “1” to the probability updating unit 1152 c. The probability update unit 1152 c updates the probability of “1” to P ₃ when the coded bit is input.

Finally, the arithmetic coding unit 1152e encodes the "0" third bit of "110" using the probability 1-P _3. Then, the arithmetic coding unit 1152 e outputs coded data obtained by coding “110” with the probabilities P ₁ , P ₂ and 1−P ₃ .

By the way, the probability holding unit 1152b holds an initial value for initializing the probability in the sequence head, the frame head, the slice head, and the like. The initial value may be "0" or "1" with equal probability, that is, 0.5, but it is appropriate to use an appropriate value such as the average value of the appearance probability experimentally obtained in many sequences It is. In this case, the PMV candidate is temporally determined using the spatial prediction vector (eg, mv_med) determined from the MV of the already encoded / decoded block of the same frame and the MV of the already encoded / decoded block of the reference frame. In the case of a prediction vector (e.g., mv_col), it is appropriate to set an initial value so as to encode an MVD absolute value shorter in temporal prediction vector with a smaller code amount. In the above example, the initial value of the probability of “0” is set larger for the temporal prediction vector than for the spatial prediction vector.

As described above, since the moving picture coding apparatus 100 ′ ′ can switch the appearance probability of “0” “1” in the process of arithmetically coding a binary number sequence converted from the MVD absolute value, the MVD absolute The coding efficiency of the value can be improved.

(Additional items)
The MVD absolute value may not be divided into the absolute value of the X component and the absolute value of the Y component and encoded, but the sum of the absolute value of the X component and the absolute value of the Y component may be encoded. . In this case, PMVCOST = F (| MV_X-PMV_X | + | MV_Y-PMV_Y |). Further, the number of PMV tentative candidates is not limited to four, and changes depending on the value of the MVD absolute value. That is, when the sum of the absolute value of the X component and the absolute value of the Y component is 1, the number of MV temporary candidates is 8, and when the sum is 2, the number of MV temporary candidates is 16, and in general When the sum is N, the number of MV tentative candidates is 8N.

Further, in each of the embodiments described above, a program for realizing the functions of the moving picture coding apparatus and the moving picture decoding apparatus is recorded on a computer readable recording medium, and the program recorded on the recording medium May be read into a computer system and executed to control the moving picture coding apparatus and the moving picture decoding apparatus. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer-readable recording medium” means a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in a computer system. Furthermore, "computer-readable recording medium" holds a program dynamically for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, the volatile memory in the computer system serving as the server or the client in that case, also includes the one that holds the program for a certain period of time. Further, the program may be for realizing a part of the functions described above, and further, the function described above may be realized in combination with a program already recorded in the computer system. .

The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and the design and the like within the scope of the present invention are also claimed. include.

The encoding apparatus of the present invention further includes a data candidate cost calculation unit for calculating the cost of each data candidate, and the flag set for each data candidate by the data candidate identification flag encoding unit is the data candidate cost It is desirable that the flag be a flag corresponding to the cost of the data candidate calculated by the calculation unit. For example, in the encoding device, the data candidate identification flag encoding unit may include more symbols with higher probability of occurrence as the distance between the data candidate and the prediction data decreases as the value of the flag identifying the data candidate decreases. It is desirable to encode the flag by coding the symbol sequence and performing arithmetic coding on the symbol sequence.

In the encoding apparatus according to the present invention, the differential absolute value encoding unit encodes the differential absolute value for each component when the predetermined data and the prediction data are data including a plurality of components, Alternatively, it is desirable to encode the sum of absolute differences of each component.

A coding apparatus according to the present invention calculates a distance cost, which is a value according to the distance between the data candidate and the prediction data candidate, using a function having the data candidate and the prediction data candidate as inputs. A distance cost calculation unit capable of selecting a plurality of functions having different amounts of operation as the function, the difference absolute value coding unit coding an index indicating the function selected by the distance cost calculation unit It is desirable to

Further, in the encoding apparatus according to the present invention, it is preferable that the predetermined data is motion vector data.

The present invention also provides a motion estimation unit that estimates a motion vector between an input image and a reference image that has already been decoded, a motion vector encoding unit that encodes the motion vector, and the motion vector using the motion vector. An inter prediction unit that generates a prediction signal from a reference image, a difference calculation unit that calculates a difference between the prediction signal and the input image, a conversion unit that converts the difference, and quantization of a conversion coefficient obtained by the conversion Preferably, the motion image coding apparatus includes a quantization unit, and the feature coding apparatus is used for coding a motion vector in the motion vector coding unit.

The decoding device of the present invention further includes a data candidate cost calculation unit for calculating the cost of each data candidate, and the flag decoded by the data candidate identification flag decoding unit is calculated by the data candidate cost calculation unit. It is desirable that the flag corresponds to the cost of the data candidate.

In the decoding device according to the present invention, the differential absolute value decoding unit decodes the differential absolute value for each component when the predetermined data and the prediction data are data consisting of a plurality of components, or It is desirable to decode the sum of differential absolute values for each component.

Further, the decoding apparatus according to the present invention calculates distance cost, which is a value according to the distance between the data candidate and the prediction data candidate, using a function having the data candidate and the prediction data candidate as input. A distance cost calculation unit capable of selecting a plurality of functions having different amounts of operation as the function, the difference absolute value decoding unit decoding an index indicating the function selected by the distance cost calculation unit It is desirable to do.

In the decoding device according to the present invention, it is preferable that the predetermined data is motion vector data.

The present invention also provides a motion vector decoding unit that decodes a motion vector, a reference image that has already been decoded, an inter prediction unit that generates a prediction signal from the motion vector, and an inverse quantization unit that inversely quantizes transform coefficients. A moving image decoding apparatus including: an inverse conversion unit that inversely converts a conversion coefficient to generate a difference signal; and adding the prediction signal and the difference signal to reproduce a decoded signal, the motion of the motion vector decoding unit It is desirable to use the feature decoder for decoding vectors.

In addition, it is the coding data which a description encoding apparatus outputs, Comprising: The coding data containing the flag which specifies a data candidate are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 ... moving image encoder, 101 ... subtraction part, 102 ... addition part, 103 ... local decoding signal, 111 ... motion vector encoding part, 112 ... conversion part, 113 ... quantization part, 115 ... variable length coding part 116: inverse quantization unit 117: inverse transformation unit 118: frame memory 121: intra prediction unit 123: inter prediction unit 124: motion estimation unit 125: prediction mode determination unit 200: moving image decoding apparatus , 201: variable length coding and decoding unit, 203: prediction parameter, 211: motion vector decoding unit, 225: prediction mode selection unit, 301: number of PMV candidates and PMV candidates, 302: PMV, 1111: MV storage unit, 1112 PMV candidate calculation unit, 1113 ... PMV determination unit, 1114 ... MVD calculation unit, 1115 ... MV flag determination unit, 1151 ... PMV index code , 1152 ... MVD absolute value encoding unit, 1153 ... MV index encoding unit, 2011 ... PMV index decoding unit, 2012 ... MVD absolute value decoding unit, 2013 ... MV index decoding unit, 2113 ... PMV selection unit, 2115 ... MV Selection unit, 5001 ... MV candidate calculation unit, 5002 ... MV candidate determination unit, 5003 ... MV index determination unit, 6004 ... MV extraction unit

Claims (17)

1. A difference absolute value encoding unit that generates prediction data from data that has already been encoded and encodes the difference absolute value between the predetermined data and the prediction data when encoding the predetermined data;
   A data candidate calculation unit that calculates data candidates from the difference absolute value and the prediction data;
   A data candidate identification flag code that sets a different flag for each data candidate and encodes the flag set for each data candidate when the number of data candidates calculated by the data candidate calculation unit is two or more. And an encoding unit.
2. The encoding apparatus according to claim 1, wherein
   A data candidate cost calculation unit for calculating the cost of each data candidate;
   The flag set for each data candidate by the data candidate identification flag coding unit is a flag according to the cost of the data candidate calculated by the data candidate cost calculation unit. apparatus.
3. The encoding apparatus according to claim 1 or 2, wherein
   The difference absolute value encoding unit encodes the difference absolute value for each component when the predetermined data and the prediction data are data including a plurality of components, or the difference absolute value for each component An encoding device comprising encoding the sum of
4. A prediction data determination unit that generates a plurality of prediction data candidates from data that has already been encoded and encodes prediction data to be used for encoding from the prediction data candidates when encoding predetermined data;
   A difference absolute value encoding unit that encodes the difference absolute value between the predetermined data and the prediction data;
   A data candidate calculation unit that calculates data candidates from the difference absolute value and the prediction data;
   A data candidate determination unit that determines the validity of the data candidate calculated from the difference absolute value and the prediction data from the prediction data and the prediction data candidate;
   An encoding apparatus comprising: a data candidate identification flag encoding unit that encodes a flag identifying the data candidate when the number of data candidates validated by the data candidate determination unit is two or more. .
5. The encoding apparatus according to claim 4, wherein
   A distance cost calculation unit that calculates a distance cost that is a value according to the distance between the data candidate and the predicted data candidate using a function that receives the data candidate and the predicted data candidate as input, and performs calculation as the function It further comprises a distance cost calculation unit capable of selecting a plurality of functions with different amounts,
   The encoding apparatus according to claim 1, wherein the difference absolute value encoding unit encodes an index indicating a function selected by the distance cost calculation unit.
6. A prediction data determination unit that generates a plurality of prediction data candidates from data that has already been encoded and encodes prediction data to be used for encoding from the prediction data candidates when encoding predetermined data;
   A difference absolute value encoding unit that encodes the difference absolute value by using the difference absolute value between the predetermined data and the prediction data as a symbol string and performing arithmetic encoding on the symbol string;
   A coding unit characterized in that the difference absolute value coding unit changes the appearance probability of each symbol used to arithmetically code the symbol string according to the prediction data selected by the prediction data determination unit. .
7. The encoding apparatus according to any one of claims 1 to 6, wherein the predetermined data is motion vector data.
8. A motion estimation unit that estimates a motion vector between an input image and a reference image that has already been decoded, a motion vector encoding unit that encodes the motion vector, and a prediction signal from the reference image using the motion vector An inter prediction unit to generate, a difference calculation unit to calculate a difference between the prediction signal and the input image, a conversion unit to convert the difference, and a quantization unit to quantize a conversion coefficient obtained by the conversion A moving picture coding apparatus, wherein the coding apparatus according to claim 7 is used for coding a motion vector in the motion vector coding unit.
9. A difference absolute value decoding unit that decodes the encoded difference absolute value when decoding predetermined data;
   A data candidate calculation unit that generates prediction data from already encoded data and calculates data candidates from the difference absolute value and the prediction data;
   A data candidate identification flag decoding unit that decodes a flag in which a different value is set for each data candidate when the number of data candidates generated by the data candidate calculation unit is two or more; A decoding device characterized by comprising.
10. The decoding device according to claim 9, wherein
    A data candidate cost calculation unit for calculating the cost of each data candidate;
    A decoding device characterized in that the flag decoded by the data candidate identification flag decoding unit is a flag corresponding to the cost of the data candidate calculated by the data candidate cost calculation unit.
11. A decoding device according to claim 9 or 10, wherein
    The difference absolute value decoding unit decodes the difference absolute value for each component when the predetermined data and the prediction data are data including a plurality of components, or a sum of difference absolute values for each component A decoding device characterized by decoding.
12. When decoding predetermined data, the encoded differential absolute value is decoded, a plurality of prediction data candidates are generated from already encoded data, and the prediction data to be used for encoding is selected from the prediction data candidates The forecast data determination unit to
    A data candidate determination unit that determines the validity of the data candidate calculated from the difference absolute value and the prediction data from the prediction data and the prediction data candidate;
    A decoding apparatus comprising: a data candidate identification flag decoding unit that decodes a flag identifying the data candidate if the number of data candidates validated by the data candidate determination unit is two or more.
13. The decoding apparatus according to claim 12, wherein
    A distance cost calculation unit that calculates a distance cost that is a value according to the distance between the data candidate and the predicted data candidate using a function that receives the data candidate and the predicted data candidate as input, and performs calculation as the function It further comprises a distance cost calculation unit capable of selecting a plurality of functions with different amounts,
    The said difference absolute value decoding part decodes the index which shows the function which the said distance cost calculation part selected.
14. A prediction data determination unit that generates a plurality of prediction data candidates from already encoded data and decodes prediction data to be used for decoding from the prediction data candidates when decoding predetermined data;
    A difference absolute value decoding unit that decodes the difference absolute value by arithmetically decoding a symbol string that is the difference absolute value between the predetermined data and the prediction data;
    The difference absolute value decoding unit changes the appearance probability of each symbol used to decode the symbol string according to the prediction data selected by the prediction data determination unit.
15. The decoding apparatus according to any one of claims 9 to 14, wherein the predetermined data is motion vector data.
16. A motion vector decoding unit that decodes a motion vector, a reference image that has already been decoded, an inter prediction unit that generates a prediction signal from the motion vector, an inverse quantization unit that inversely quantizes transform coefficients, and inverse transform coefficients A moving picture decoding apparatus comprising: an inverse conversion unit for converting and generating a differential signal, and adding the prediction signal and the differential signal to reproduce a decoded signal, wherein the motion vector decoding unit performs decoding on the motion vector claim. 15. A moving picture decoding apparatus characterized by using the decoding apparatus according to 15.
17. It is the encoding data which the encoding apparatus of any one of Claims 1 to 7 outputs, Comprising: The encoding data containing the said flag.

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