JPH10224800A - Motion vector coding method and decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of motion vector coding considerably. SOLUTION: A coding discriminator 310 references motion vector information 306 to discriminate which information is to be coded by a motion vector coder 313. A switch 311 selects a 1st motion vector 300 or a 2nd motion vector 301 according to a command of the coding discrimination device 310, the selected motion vector is coded by the motion vector coder 313 and the result is outputted as a motion vector coding signal 302. Furthermore, a switch 312 is used to select the 2nd motion vector 312, which is coded by a motion vector coder 314 and outputted as a motion vector coding signal 303 when the coding of the 2nd motion vector 301 is required (the motion vector is in existence), the motion vector is not code by the motion vector coder 313, or when the, coding of the 2nd motion vector 301 is required (the motion vector is in existence) and the motion vector coder 313 cannot code part of information of the 2nd motion vector 301.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion vector encoding / decoding method used for efficiently encoding a motion vector required for encoding an image, and a method similar to the motion vector encoding. An image encoding method / decoding method used for efficiently encoding an image signal by performing motion compensation on the principle of, and a motion vector encoding device / decoding device realizing the same by hardware, and The present invention relates to a recording medium on which a program to be realized by software is recorded.

[0002]

2. Description of the Related Art In image signal coding, motion compensation coding with reference to a motion vector is known as efficient coding. Motion compensation coding requires a motion vector, and efficient image coding requires efficient motion vector coding. As a conventional motion vector encoding method, a method of calculating a predicted value of a motion vector and encoding a difference value between a coded motion vector and a predicted value of a motion vector, as represented by MPEG1 / 2, is generally used. It is a target. Note that the prediction value of a conventional motion vector such as MPEG1 / 2 is always one, and sufficient performance can be obtained to encode a simple motion image. On the other hand, for images with complex movements,
The prediction values of a plurality of motion vectors created based on several criteria are compared with the motion vector to be coded, and the difference between the prediction value of the motion vector closest to the motion vector to be coded and the motion vector to be coded is calculated. Encoding efficiency is obtained by encoding a reference value identification signal that identifies a predicted value of a motion vector close to the encoded motion vector.

An image signal sometimes has a plurality of motion vectors for pixel values at the same position.

For example, in the case of encoding on an object basis,
There are both a motion vector of the shape of the object and a motion vector of the pixel value of the object. Efficient encoding can be realized by encoding both motion vectors collectively.

[0005]

However, when there are a plurality of motion vector prediction values, it is necessary to encode the reference value specifying signal. The conversion efficiency does not improve so much. If the reference value specifying signal can be saved without deteriorating the coding efficiency, the coding efficiency can be further improved.

In the case where a plurality of motion vectors are provided for the pixel value at the same position, conventionally, only a method of differentially encoding one motion vector with the other motion vector has been considered.

In view of the above, the present invention adaptively encodes a reference value specifying signal when there are a plurality of predicted values of a motion vector, thereby degrading the reference value specifying signal without deteriorating the coding efficiency. And to greatly improve the coding efficiency. Also, when a plurality of motion vectors are provided for the pixel value at the same position, one of the motion vectors is coded as the other motion vector, thereby significantly improving the efficiency of the latter motion vector coding. And

[0008]

According to a first aspect of the present invention, there is provided a motion vector encoding method for encoding an input motion vector with reference to a plurality of motion vector prediction value candidates. The motion vector prediction value in one of two modes: a mode for determining a motion vector prediction value from the plurality of motion vector prediction value candidates according to a predetermined rule, and a mode for selecting one of the plurality of motion vector prediction value candidates. And outputting a coded signal obtained by coding the input motion vector with reference to the motion vector prediction value and a signal indicating the mode.

According to a second aspect of the present invention, a coded signal obtained by coding a motion vector and a signal indicating a selection mode of a motion vector referred to in the coding are input, and the coding is performed by referring to a plurality of motion vector prediction value candidates. A motion vector encoding method for decoding the obtained motion vector, wherein a motion vector prediction value is determined according to a predetermined rule from the plurality of motion vector prediction value candidates corresponding to the selection mode, or the plurality of motion vectors are determined. A motion vector decoding method for deriving a motion vector prediction value by selecting one of the vector prediction value candidates, decoding the input coded signal with reference to the motion vector prediction value, and outputting a motion vector. .

A third aspect of the present invention is an image encoding method for encoding an input image signal with reference to a plurality of motion vector predicted value candidates, wherein the motion vector predicted value The motion vector prediction value is derived in one of two modes, a mode in which a predetermined rule is determined and a mode in which one is selected from the plurality of motion vector prediction value candidates, and the input is performed by referring to the motion vector prediction value. This is an image encoding method for outputting an encoded signal obtained by encoding the encoded image signal and a signal indicating the mode.

According to a fourth aspect of the present invention, a coded signal obtained by coding an image signal and a signal indicating a motion vector selection mode referred to in the coding are input, and coding is performed by referring to a plurality of motion vector prediction value candidates. An image coding method for decoding the obtained image signal, wherein a motion vector prediction value is determined from a plurality of motion vector prediction value candidates according to a predetermined rule in accordance with the selection mode, or the plurality of motion vectors are determined. An image decoding method for selecting one of prediction value candidates to derive a motion vector prediction value, decoding the input coded signal with reference to the motion vector prediction value, and outputting an image signal.

A fifth aspect of the present invention is a motion vector encoding method for encoding a motion vector inputted with reference to a plurality of motion vector prediction value candidates. The motion vector prediction value candidates are compared with each other, and one is selected according to a predetermined rule to obtain a motion vector prediction value. If the predetermined condition is not satisfied, the input motion vector is extracted from the plurality of motion vector prediction value candidates. Reference is made to select one according to a predetermined rule to obtain a motion vector prediction value, generate information for specifying the selected motion vector prediction value, and code the input motion vector by referring to the motion vector prediction value. A motion vector encoding method that outputs information specifying the motion vector prediction value and a signal obtained by encoding the motion vector.

According to a sixth aspect of the present invention, there is provided a motion vector decoding method for decoding an input motion vector coded signal with reference to a plurality of motion vector prediction value candidates and information for specifying a motion vector candidate from the motion vector prediction value candidates. A predetermined condition is satisfied, the plurality of motion vector predicted value candidates are compared with each other, and one is selected according to a predetermined rule as a motion vector predicted value, and the predetermined condition is not satisfied. In this case, one of the plurality of motion vector predicted value candidates is selected with reference to the information for specifying the motion vector predicted value, and is set as a motion vector predicted value, and the input code is referred to with reference to the motion vector predicted value. This is a motion vector decoding method for decoding and outputting the converted motion vector.

A seventh invention is a motion vector coding method for coding a plurality of motion vectors, wherein one of the plurality of motion vectors is selected, and the selected motion vector is coded by the first method. , A motion vector encoding method for encoding the unselected motion vector by a second method when it is necessary to encode the unselected motion vector.

An eighth invention is a motion vector decoding method for decoding a plurality of motion vectors by decoding a coded signal obtained by coding one or more motion vectors, wherein the coded signal is converted to a first signal. The motion vector is decoded by the second method, and if two or more motion vectors are encoded in the encoded signal, the motion vector is decoded by the second method. If the number of motion vectors is one, the first method is used. Is a motion vector decoding method for determining what the decoded vector corresponds to, and outputting as a corresponding motion vector.

A ninth aspect of the present invention is a motion vector coding apparatus for coding a motion vector inputted with reference to a plurality of motion vector prediction value candidates. Coding determination means for deriving a motion vector prediction value in one of two modes, a mode in which a value is determined according to a predetermined rule and a mode in which one is selected from the plurality of motion vector prediction value candidates; A motion vector encoding unit that encodes the input motion vector with reference to a motion vector encoding device that outputs an encoded signal encoded by the motion vector encoding unit and a signal indicating the mode. is there.

According to a tenth aspect of the present invention, a coded signal obtained by coding a motion vector and a signal indicating a motion vector selection mode referred to in the coding are input, and coding is performed by referring to a plurality of motion vector prediction value candidates. A motion vector encoding device that decodes the obtained motion vector, wherein the motion vector prediction value is adaptively determined from the plurality of motion vector prediction value candidates corresponding to the selection mode, or the motion vector prediction value is determined according to a predetermined rule. Encoding determination means for selecting one of a plurality of motion vector predicted value candidates to derive a motion vector predicted value, and motion vector decoding for decoding the input coded signal with reference to the motion vector predicted value Means for outputting a motion vector decoded by the vector decoding means.

An eleventh invention is an image coding apparatus for coding an image signal inputted with reference to a plurality of motion vector predicted value candidates, wherein the motion vector predicted value is calculated from the plurality of motion vector predicted value candidates. Encoding determination means for deriving a motion vector prediction value in one of two modes, a mode in which the motion vector prediction value is determined according to a predetermined rule and a mode in which one is selected from the plurality of motion vector prediction value candidates. An image encoding apparatus comprising: a motion compensation encoding unit that encodes the input image signal with reference to the input unit; and outputs a coded signal encoded by the motion compensation encoding unit and a signal indicating the mode.

According to a twelfth aspect of the present invention, a coded signal obtained by coding an image signal and a signal indicating a motion vector selection mode referred to in the coding are input, and the coding is performed by referring to a plurality of motion vector prediction value candidates. An image coding apparatus for decoding the obtained image signal, wherein a motion vector prediction value is determined from a plurality of motion vector prediction value candidates in accordance with the selection mode by a predetermined rule, or the plurality of motion vectors are determined. Encoding decision means for selecting one of the prediction value candidates to derive a motion vector prediction value, and motion compensation decoding means for decoding the input coded signal with reference to the motion vector prediction value, An image decoding device for outputting an image signal decoded by the motion compensation decoding means.

A thirteenth invention is a motion vector coding device for coding a plurality of motion vectors, wherein a selecting means for selecting one of the plurality of motion vectors, and a coding means for coding the selected motion vector. Motion vector encoding means comprising: a first motion vector encoding means, and a second motion vector encoding means for encoding the unselected motion vector when it is necessary to encode the unselected motion vector. It is an encoding device.

A fourteenth invention is a motion vector decoding device for decoding a plurality of motion vectors by decoding a coded signal obtained by coding one or more motion vectors, wherein the motion vector decoding device decodes the coded signal. A first motion vector decoding unit that performs decoding; a second motion vector decoding unit that decodes another motion vector if two or more motion vectors are encoded in the encoded signal; In one case, an encoding determination unit that determines a signal corresponding to a vector decoded by the first method, and a motion vector of a corresponding signal obtained by decoding the motion vector decoded based on the determination result. This is a motion vector decoding device provided with a selection unit that outputs a motion vector.

A fifteenth aspect of the present invention is a motion vector coding apparatus for coding a motion vector inputted with reference to a plurality of motion vector prediction value candidates, wherein the plurality of motion vector candidate values are input to the plurality of motion vector prediction values. Encoding determination means for determining whether or not one of the motion vector prediction value candidates can be selected, and outputting the result; and, when one of the prediction value candidates cannot be selected with reference to the output of the encoding determination means, Reference value determining means for comparing one of the motion vector candidate values with the input motion vector, selecting one motion vector predicted value candidate according to a predetermined rule, and outputting information for specifying the selected motion vector predicted value candidate; If one of the prediction value candidates can be selected by referring to the output of the encoding determination means, one of the plurality of motion vector prediction value candidates is determined according to a predetermined rule.
And selecting and outputting one of the prediction value candidates. If one of the prediction value candidates cannot be selected, the prediction value generation means for outputting the motion vector prediction value candidate specified by the reference value determination means output; A motion vector encoding unit that encodes and outputs the input motion vector with reference to the
A motion vector encoding apparatus, wherein the output of the reference value determination means and the output of the motion vector encoding means are output from the apparatus.

According to a sixteenth aspect of the present invention, there is provided a motion vector decoding apparatus for decoding a motion vector coded signal inputted with reference to a plurality of motion vector prediction value candidates and information for specifying a motion vector candidate from the motion vector prediction value candidates. Encoding means for determining whether or not one of the plurality of motion vector prediction value candidates can be selected by using the plurality of motion vector candidate values as input, and outputting the encoding judgment means If one of the predicted value candidates can be selected with reference to the above, one is selected and output according to a predetermined rule from the plurality of motion vector predicted value candidates, and one is not selectable from the predicted value candidates. Predictive value generating means for outputting a motion vector predictive value candidate corresponding to the information specifying the motion vector candidate; and the inputted motion vector with reference to the output of the predictive value generating means. Includes a motion vector decoding means decodes and outputs the torque encoded signal, said a motion vector decoding apparatus according to an output of the motion vector decoding means outputs the device.

A nineteenth aspect of the present invention is a recording medium for a computer, in which a program for realizing at least one of the first to twelfth aspects is recorded.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram of a motion vector coding apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a motion vector to be coded, 2 is a candidate for a first motion vector prediction value, 3 is a candidate for a second motion vector prediction value, and 20 is a code indicating whether to adaptively select a motion vector prediction value. An encoding determiner that outputs adaptive selection presence / absence information 10 indicating the presence / absence of adaptive selection with reference to the coding determination information 4, and a prediction value candidate information 5 of an input motion vector prediction value candidate and an adaptive selection presence / absence A reference value determiner for selecting a motion vector prediction value by the switch 22 with reference to the information 10;
Reference numeral 23 denotes a motion vector encoder that encodes the encoded motion vector with reference to the motion vector prediction value and outputs the encoded motion vector signal 11.

The operation of the motion vector coding apparatus according to the first embodiment configured as described above will be described below. When a motion vector is encoded, efficient encoding is possible by encoding a difference value between an encoded motion vector and a motion vector prediction value. May be referred to. FIG. 2 is an explanatory diagram when a motion vector is selected from within the screen. In conventional encoding, the encoded motion vector
When encoding MV0, the motion vectors MV1, MV2 and MV3
To generate one motion vector prediction value. However, if three of MV1, MV2 and MV3 are set as motion vector predicted value candidates, and one of the three motion vectors is adaptively selected as a motion vector predicted value when encoding MV0,
In some cases, the coding efficiency can be reduced more than selecting one motion vector prediction value by a predetermined method. FIG. 3 is an explanatory diagram when a motion vector is selected from between screens.
MV1 and MV2 are motion vectors of screens at different times. Two of MV1 and MV2 are set as motion vector prediction value candidates, and one of the two motion vectors is adaptively used as a motion vector prediction value when encoding MV0. , The coding efficiency may be reduced more than selecting one motion vector prediction value by a predetermined method. Note that FIG. 3 is not necessarily a screen at a different time, and prediction of an enhancement layer from a base layer in the case of hierarchical encoding, and a shape signal of an object or a pixel value signal of an object in the case of encoding on an object basis. The same effect can be realized from one prediction to the other. As a method of adaptively selecting a motion vector predicted value from a plurality of motion vector predicted value candidates, a method of selecting a motion vector predicted value based on the value of an encoded / decoded motion vector is one of typical methods. For example, in the example of FIG. 2, the value of the encoded / decoded motion vector
It is determined which of MV1, MV2 and MV3 is to be the motion vector prediction value. Such a method of adaptively selecting a motion vector prediction value from a plurality of motion vector prediction value candidates is very effective for an image signal whose motion vectors are spatially correlated, but is very effective for an image signal having little correlation. Conversely, a normal method of selecting one motion vector prediction value by a predetermined method has higher encoding efficiency. Therefore, a method of selecting one motion vector predicted value by a predetermined method and a method of adaptively selecting a motion vector predicted value from a plurality of motion vector predicted value candidates can be switched in a predetermined unit. The motion vector encoding apparatus according to the first embodiment shown in FIG. 1 outputs the adaptive selection presence / absence information 10 for identifying which method to encode for each unit.

The coding decision unit 20 outputs the adaptive selection presence / absence information 10 indicating the presence / absence of adaptive selection with reference to the coding decision information 4. Examples of the encoding determination information 4 include a case where it is desired to forcibly select a motion vector at the previous time in the case of bidirectional predictive encoding (MPEG B frame) which can refer to a motion vector before and after the time. When the coding efficiency is degraded when the motion vector prediction value is adaptively selected from the motion vector prediction value candidates, or when the shape signal of the object and the pixel value signal of the object are independently coded by the coding on a per-object basis. It is used to notify the encoding determiner 20 that prohibition of reference from one motion vector to the other motion vector. The reference value determination unit 21 refers to the prediction value candidate information 5 to select one from a plurality of motion vector prediction value candidates and notifies the switch 22 of the selection. As an example of the predicted value candidate information 5, a signal indicating whether the motion vector predicted value candidate can be referred to at the time of decoding (whether the referenced motion vector is already coded and can be correctly decoded). Also, there is a signal indicating whether the object is a contour portion, inside the object, or outside the object in object-based coding. The switch 22 selects one of the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 based on the determination result of the reference value determiner 21 and notifies the motion vector encoder 23 of the selected one. The motion vector encoder 23 encodes the motion vector to be encoded 1 with reference to the output of the switch 22 and outputs the encoded motion vector signal 11.
Output as In the motion vector coding apparatus according to the first embodiment shown in FIG. 1, adaptive selection presence / absence information 10 and a motion vector coded signal 11 are output and used for decoding. In normal use, the prediction value candidate information 5 does not need to be coded because it uses a signal that can be correctly decoded from other information at the time of decoding. It may be transmitted to the decoding device as an output of the device. Also, the cycle of switching the adaptive selection presence / absence information 10 in the encoding decision unit 20 is preferably in frame units or several lines (MPEG 1/2 macroblock slice).
Any value can be set as long as it is an integral multiple of the cycle at which the switch 22 is switched.

Although three or two of MV1, MV2 and MV3 have been described as motion vector prediction value candidates in the description of FIGS. 2 and 3, motion vectors derived from those motion vectors (for example, MV1 and MV2) are shown. Average value and the average value of MV2 and MV3) may be used as a motion vector prediction value candidate, and if some motion vectors of MV1, MV2 and MV3 do not exist, a predetermined value (for example, a zero vector) is used instead. It is also possible to use.

(Embodiment 2) FIG. 4 is a block diagram of a motion vector decoding apparatus according to Embodiment 2. In the figure, devices that perform the same operations as those of the motion vector encoding device according to the first embodiment in FIG. 1 are assigned the same numbers, and descriptions of the operations are omitted. Reference numeral 24 denotes a motion vector decoder which decodes the motion vector coded signal 11 with reference to the motion vector predicted value of the switch 22 and outputs a decoded motion vector 12.

The operation of the motion vector decoding apparatus according to the second embodiment configured as described above will be described below. The motion vector decoding apparatus according to the second embodiment receives adaptive selection presence / absence information 10 and motion vector coded signal 11 as inputs, and outputs first motion vector prediction value candidate 2, second motion vector prediction value candidate 3, and adaptive selection presence / absence. This is a device that outputs a decoded motion vector 12 with reference to information 10, and can decode a coded signal of the motion vector coding device according to the first embodiment in FIG. As described in the first embodiment, in normal use, the prediction value candidate information 5 can be correctly decoded from another information at the time of decoding. However, if necessary, the motion vector coding apparatus And is input to the decoding device. Motion vector decoder 2
4 decodes the coded motion vector signal 11 with reference to the predicted motion vector value of the switch 22 and outputs a decoded motion vector 12. When the motion vector coded signal 11 is differentially coded with the motion vector predicted value, the motion vector decoder 24 can be realized by an adder that adds the motion vector coded signal 11 and the motion vector predicted value.

(Embodiment 3) FIG. 5 is a block diagram of a motion vector coding apparatus according to Embodiment 3 of the present invention. In the figure, devices that perform the same operations as those of the motion vector encoding device according to the first embodiment in FIG. 1 are denoted by the same reference numerals, and descriptions of the operations are omitted. In the figure, reference numeral 30 denotes a first motion vector predicted value candidate 2 and a second motion vector predicted value candidate 3
An encoding determiner that outputs adaptive selection presence / absence information 10 indicating the presence / absence of adaptive selection with reference to the encoding determination information 4 and
Reference numeral 31 denotes a motion vector predicted value selection signal with reference to the encoded motion vector 1, the first motion vector predicted value candidate 2, the second motion vector predicted value candidate 3, the predicted value candidate information 5, and the adaptive selection presence / absence information 10. 8 is a reference value decision unit that outputs 8; 33 is a switch that outputs a motion vector predicted value selection signal 8 when a motion vector predicted value cannot be uniquely determined from the predicted value candidate information 5; Is a switch that outputs the output of the switch 34 as the motion vector prediction value selection signal 13 when.

The operation of the motion vector coding apparatus according to the third embodiment configured as described above will be described below. In the motion vector encoding device according to the first embodiment, the reference value determination unit 21 uses the prediction value candidate information 5 and the adaptive selection presence / absence information 10
A motion vector prediction value selection signal is determined with reference to only the reference value. Although the motion vector encoding apparatus according to the first embodiment can realize more efficient encoding than the conventional motion vector encoding apparatus, if the number of bits needs to be further reduced, the first It is necessary to compare the vector predicted value candidate 2 and the second motion vector predicted value candidate 3 with the coded motion vector 1 and select a motion vector predicted value candidate having a small number of coded bits of the coded motion vector 1. It is.
However, in this case, the motion vector predicted value selection signal 8 indicating which motion vector predicted value was selected.
Must be transmitted to the decoding side, and it is important to reduce the number of bits of the motion vector prediction value selection signal 8. Therefore, if the switch 34 is turned on and the motion vector predicted value selection signal 8 is output as the motion vector predicted value selection signal 13 only when the adaptive selection presence / absence information 10 indicates the adaptive selection, the adaptive selection presence / absence information 10 determines the adaptive selection. When not shown, the transmission of the motion vector prediction value selection signal 8 becomes unnecessary, and the number of bits can be saved. In addition, when the decoding side can uniquely determine whether the motion vector prediction value is the first motion vector prediction value candidate 2 or the second motion vector prediction value candidate 3 in the prediction value candidate information 5, The transmission of the vector prediction value selection signal 8 becomes unnecessary.

The coding decision unit 30 refers to the first motion vector predicted value candidate 2, the second motion vector predicted value candidate 3, and the coding decision information 4 to determine whether or not there is an adaptive selection. The information 10 is output. For example, a first motion vector predicted value candidate 2 and a second motion vector predicted value candidate 3
Almost coincides with each other, the coding efficiency hardly changes even if any of the motion vector prediction value candidates is used as the motion vector prediction value. The number of bits of the predicted value selection signal 8 can be reduced without deteriorating the conversion efficiency. When the adaptive selection presence / absence information 10 gives an instruction to perform adaptive selection, the reference value determiner 31 converts the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 into the encoded motion vector 1. If a motion vector predicted value candidate that can efficiently encode the encoded motion vector 1 can be selected as a motion vector predicted value by the instruction of the predicted value candidate information 5, it can be selected as a motion vector predicted value. If not, the switch 22 is notified by the motion vector predicted value selection signal 8 so that the other is used as the motion vector predicted value. The switch 33 is turned on only when the motion vector prediction value cannot be uniquely determined correctly on the decoding side in the prediction value candidate information 5, and the switch 3 is turned on.
4 is turned on only when the adaptive selection presence / absence information 10 gives an instruction to perform adaptive selection. In the motion vector encoding apparatus according to the third embodiment shown in FIG. 5, a motion vector prediction value selection signal 13 and a motion vector encoded signal 11 are output and used for decoding. As in the case of the motion vector coding apparatus according to the first embodiment, in normal use, the prediction value candidate information 5 uses a signal that can be correctly decoded from other information during decoding. However, if necessary, the motion vector may be transmitted to the decoding device as an output of the motion vector coding device.

(Embodiment 4) FIG. 6 is a block diagram of a motion vector decoding apparatus according to Embodiment 4. In the same figure, devices that perform the same operations as those of the motion vector encoding device of the third embodiment shown in FIG. 5 and the motion vector decoding device of the second embodiment shown in FIG. Is omitted. Reference numeral 40 denotes a switch that outputs a motion vector prediction value selection signal according to the prediction value candidate information 5, and 41 denotes a switch that outputs a motion vector prediction value selection signal according to the adaptive selection presence / absence information 10.

The operation of the motion vector decoding apparatus according to the fourth embodiment configured as described above will be described below. The motion vector decoding apparatus according to the fourth embodiment includes a motion vector prediction value selection signal 13 and a motion vector encoded signal 11
And outputs the decoded motion vector 12 with reference to the first motion vector predicted value candidate 2, the second motion vector predicted value candidate 3, and the encoding determination information 4.
It is possible to decode the encoded signal of the motion vector encoding device according to the third embodiment. As described in the third embodiment, in normal use, the predicted value candidate information 5
Can be correctly decoded from other information at the time of decoding, but if necessary, it is transmitted as an output of the motion vector encoding device and becomes an input of the decoding device. The switch 40 selects one of the first motion vector prediction value candidate 2 and the second motion vector prediction value candidate 3 if the motion vector prediction value can be uniquely determined based on the prediction value candidate information 5, and so on. If not, a motion vector prediction value selection signal 13 is output. The switch 41 is a switch 4 if the adaptive selection presence / absence information 10 indicates an adaptive motion vector prediction value selection.
If the output of 0 is selected and the adaptive selection is not instructed, the motion vector predicted value selects either the first motion vector predicted value candidate 2 or the second motion vector predicted value candidate 3. However, when one of the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 is selected by the switches 40 and 41, the same motion vector as the motion vector selected by the motion vector encoding device is used. Select a vector. The operation of the other devices is the same as that of the motion vector encoding device of the third embodiment of FIG. 5 and the motion vector decoding device of the second embodiment of FIG. 4, and as described above, the operation of the third embodiment of FIG. Since the adaptive selection presence / absence information 8 of the motion vector encoding device can be correctly decoded, the motion vector can be correctly decoded.

(Embodiment 5) FIG.
3 is a block diagram of a specific configuration example of FIG. In the figure,
Devices that perform the same operations as those of the motion vector encoding device according to the third embodiment in FIG. 5 and the motion vector decoding device according to the fourth embodiment in FIG. 6 are given the same numbers, and descriptions of the operations are omitted. 100 is a subtractor and 101 is a comparator.

The operation of the coding decision unit 30 of FIG. 7 configured as described above will be described. The encoding determiner 30 calculates a difference value between the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 by a differentiator 100, compares the difference value with a coding determination information 4 by a comparator 101, When the difference value is equal to or greater than the coding determination information 4, the adaptive selection presence / absence information 10 indicates that the adaptive selection is to be performed. When the difference value is equal to or greater than the coding determination information 4, the adaptive selection is not performed. is there.
If the difference between the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 is small, there is almost no difference between the case where the motion vector predicted value is adaptively selected and the case where the motion vector predicted value is fixedly selected. Prohibiting the adaptive selection has the effect of reducing the number of bits of the predicted value selection signal 13. In addition,
When the value of the coding determination information 4 in the fifth embodiment is large, it is easy to perform adaptive selection using the adaptive selection presence / absence information 10, and thus has a meaning of a parameter that changes the ratio of adaptive selection.

(Embodiment 6) FIG. 8 shows a reference value decision unit 31.
3 is a block diagram of a specific configuration example of FIG. In the figure,
Devices that perform the same operations as those of the motion vector encoding apparatus according to the third embodiment in FIG. 5 are denoted by the same reference numerals, and descriptions of the operations will be omitted. 110 and 111 are subtractors, 112 is a comparator,
Reference numerals 113, 114 and 115 are switches.

The operation of the reference value determiner 31 of FIG. 8 configured as described above will be described. The encoding determiner 30 calculates a difference value between the encoded motion vector 1 and the first motion vector predicted value candidate 2 and the second motion vector predicted value candidate 3 by the difference units 110 and 111, respectively. The motion vector prediction value candidate which becomes a small absolute difference value by comparing the difference values of the unit 112 is selected by the switch 113.
When the prediction value candidate information 5 cannot refer to any of the motion vector prediction value candidates (cannot correctly refer to the decoding side), the switch 114 selects one that can be referred to. 113 output is selected. The switch 115 selects a predetermined one when the adaptive selection presence / absence information 10 prohibits the adaptive selection, and selects the output of the switch 114 when the adaptive selection is permitted.

As described above, an appropriate predicted value of a motion vector can be determined with reference to the predicted value candidate information 5 and the adaptive selection presence / absence information 10.

(Embodiment 7) FIG. 9 is a block diagram of a specific configuration example of the motion vector encoder 23. In the same figure, devices that perform the same operations as those of the motion vector coding device of the first embodiment in FIG. 1 and the motion vector coding device of the third embodiment in FIG. 5 are denoted by the same reference numerals, and description of the operations is omitted. I do. 120 is a subtractor and 121 is a difference vector encoder.

The operation of the motion vector encoder 23 of FIG. 9 configured as described above will be described. The difference unit 120 calculates a difference value (difference vector) between the encoded motion vector 1 and the motion vector prediction value 7, and
The motion vector is coded at 21 and becomes a motion vector coded signal 11.
The motion vector prediction value 7 is a vector having a small difference value from the encoded motion vector 1, and the output of the differentiator 120 has a distribution concentrated on the zero vector. Therefore, efficient motion vector coding can be performed by performing variable-length coding with a short code length near the zero vector in the difference vector encoder 121.

(Embodiment 8) FIG. 10 is a block diagram of a specific configuration example of the motion vector decoder 24. In the same figure, the devices having the same operations as those of the motion vector decoding device of the second embodiment of FIG. 4 and the motion vector decoding device of the fourth embodiment of FIG. 6 are denoted by the same reference numerals, and the description of the operations is omitted. I do. 130 is a difference vector decoder, 131
Is an adder.

The operation of the motion vector decoder 24 configured as described above and shown in FIG. 10 will be described. Embodiment 8
The motion vector decoder performs the decoding operation of the motion vector encoder according to the seventh embodiment. The difference vector decoder 130 decodes the motion vector coded signal 11 to decode a difference value (difference vector) from the motion vector prediction value 7, and the adder 131 outputs the difference vector decoder 1
30 and the motion vector prediction value 7 are added and output as a decoded motion vector 12. As described above, the decoding operation of the motion vector encoder according to Embodiment 7 can be performed correctly.

(Embodiment 9) FIG. 11 is a block diagram of an image coding apparatus according to Embodiment 9 of the present invention. In the figure, devices that perform the same operations as those of the motion vector encoding device according to the first embodiment in FIG. 1 are denoted by the same reference numerals, and descriptions of the operations are omitted. In the figure, reference numeral 220 denotes a motion compensation encoder that performs motion compensation encoding on the encoded image signal 201 with reference to the motion vector prediction value output from the switch 22, and outputs an image encoded signal 211.

The operation of the image coding apparatus according to the ninth embodiment configured as described above will be described below.

The image coding apparatus according to the ninth embodiment selects one of a plurality of motion vector prediction value candidates as a motion vector prediction value, and converts the coded image signal 201 into a motion compensation code with the selected motion vector prediction value. And outputs it as an image encoded signal 211. The method of determining the motion vector prediction value is the same as that of the motion vector coding apparatus according to the first embodiment in FIG. 1, and the first motion vector prediction value candidate 2 and the second motion vector prediction value candidate 3 are decoded on the decoding side. If known, the reference value determiner 21 selects one of the two vectors with a small motion compensation error as the motion vector prediction value, thereby improving the coding efficiency. As the motion vector predicted value candidate, each motion vector at the same spatial position at the previous time and the next time may be used. Either motion vector of the degree signal may be used to encode the other signal. For example, each motion vector of the shape signal and the pixel value signal can be used as a motion vector prediction value candidate, and the transparency signal can be motion-compensated.

(Embodiment 10) FIG. 12 shows Embodiment 1 of the present invention.
0 is a block diagram of an image decoding device of No. 0. FIG. In the same figure, devices that perform the same operations as those of the motion vector decoding device according to the second embodiment of FIG. 4 and the devices of the image encoding device according to the ninth embodiment of FIG. Omitted. In the figure, reference numeral 221 denotes an image coded signal 21 with reference to a motion vector prediction value output from the switch 22.
1 is a motion compensation decoder that performs motion compensation decoding on 1 and outputs a decoded image signal 212.

The operation of the image decoding apparatus according to the tenth embodiment configured as described above will be described below. The image decoding apparatus according to the tenth embodiment refers to the motion vector prediction value output from the switch 22 and
Is a device that decodes The method of determining the motion vector prediction value is the same as that of the motion vector decoding apparatus according to the second embodiment in FIG. 4, and the first motion vector prediction value candidate 2 and the second motion vector prediction value candidate 3 are decoded on the decoding side. If known, the motion vector prediction value referred to in the motion compensation coding of the image encoding device can be generated by the same method as that of the motion vector decoding device of the second embodiment in FIG. Can be decrypted.

(Embodiment 11) FIG. 13 is a block diagram of an image coding apparatus according to Embodiment 11 of the present invention. In the same figure, devices that perform the same operations as those of the motion vector encoding device of the third embodiment of FIG. 5 and the image encoding device of the ninth embodiment of FIG. 11 are given the same numbers, and descriptions of the operations are omitted. .

The operation of the image coding apparatus according to the eleventh embodiment configured as described above will be described below. The difference between the image coding apparatus according to the eleventh embodiment and the image coding apparatus according to the ninth embodiment is that the image coding apparatus according to the ninth embodiment uses the same motion vector prediction value as the motion vector coding apparatus according to the first embodiment. The image coding apparatus according to the eleventh embodiment performs the motion compensation coding with reference to the same motion vector prediction value as the motion vector coding apparatus according to the third embodiment, while performing the motion compensation coding with reference to the reference. . However, since the coded motion vector 1 does not exist in the image coding apparatus according to the eleventh embodiment of FIG. 13, the reference value decision unit 31 does not refer to the coded motion vector 1 in the motion vector prediction value selection signal 8. To determine.

(Embodiment 12) FIG. 14 shows Embodiment 1 of the present invention.
2 is a block diagram of a second image decoding device. FIG. In the figure, the operation is the same as that of the apparatus of the motion vector decoding device of the fourth embodiment in FIG. 6, the image decoding device of the tenth embodiment of FIG. 12, and the image coding device of the eleventh embodiment of FIG. The devices are assigned the same numbers, and descriptions of their operations are omitted.

The operation of the image decoding apparatus according to the twelfth embodiment configured as described above will be described below. The difference between the image decoding apparatus according to the twelfth embodiment and the image decoding apparatus according to the tenth embodiment is that the image decoding apparatus according to the tenth embodiment uses the same motion vector prediction value as the motion vector decoding apparatus according to the second embodiment. The image decoding apparatus according to the twelfth embodiment performs the motion compensation decoding with reference to the same motion vector prediction value as the motion vector decoding apparatus according to the fourth embodiment, while performing the motion compensation decoding with reference. .

(Embodiment 13) FIG. 15 is a block diagram of a specific configuration example of the motion compensation encoder 220. In the figure, devices that perform the same operations as those of the image encoding device according to the ninth embodiment in FIG. 11 are assigned the same numbers, and descriptions of the operations are omitted. 230 is a memory, 231 is a subtractor, 232 is an encoder, 233 is a decoder, and 234 is an adder.

The operation of the motion compensation encoder 220 of FIG. 15 configured as described above will be described. The motion compensation encoder 220 in FIG. 15 is a configuration of a typical motion compensation encoder used in MPEG1 / 2. The decoded image signal is stored in the memory 230, and the motion vector prediction value 7
Are output to the subtractor 231. The subtractor 231 calculates a difference value between the encoded image signal 201 and the output of the memory 230, and encodes the difference value by the encoder 232. The encoder 232 performs orthogonal transform, quantization, and variable-length encoding, and outputs an encoded image signal 211. The decoder 233 decodes the coded image signal 211, adds the coded image signal 211 to the output of the memory 230 by the adder 234, stores the sum in the memory 230, and uses it for coding the subsequent image signal. The decoder 233 performs variable-length decoding, inverse quantization, and inverse orthogonal transform, which are the reverse processes of the encoder 232. Note that the encoder 232 and the decoder 233 may perform predictive coding, subband coding, or wavelet coding instead of orthogonal transform, and may use fixed-length coding instead of variable-length coding. It is.

(Embodiment 14) FIG. 16 is a block diagram of a specific configuration example of the motion compensation decoder 221. In the same figure, the devices having the same operations as those of the motion compensation decoder of the tenth embodiment of FIG. 12 and the motion compensation decoder of the thirteenth embodiment of FIG. I do.

The operation of the motion compensation decoder 221 configured as described above and shown in FIG. 16 will be described. Embodiment 14
The motion-compensated decoder of (13) performs the decoding operation of the motion-compensated encoder of Embodiment 13. The configuration of the motion compensation decoder according to the fourteenth embodiment is a part of the motion compensation decoder according to the thirteenth embodiment in FIG. 15, and the operation of this part is the same as that in the motion compensation decoder according to the thirteenth embodiment in FIG. This is the same as that described above.

(Embodiment 15) FIG.
5 is a block diagram of a motion vector coding device of FIG. In the figure, 300 is the first motion vector, 301 is the second motion vector.
, 313 is a motion vector encoder that encodes a motion vector and outputs a motion vector encoded signal 302, 314 is a motion vector encoder that encodes a motion vector and outputs a motion vector encoded signal 303,
310 is a motion vector 300 and a motion vector 301
This is an encoding determiner that switches the switches 311 and 312 and switches the encoding mode of the motion vector encoder 313 with reference to the motion vector information 306 serving as an index for switching.

The operation of the motion vector coding apparatus according to the fifteenth embodiment configured as described above will be described below. The motion vector coding apparatus according to the fifteenth embodiment is a motion vector coding apparatus that codes two motion vectors, that is, a first motion vector 300 and a second motion vector 301 at the same time. FIG. 18 is an explanatory diagram for simultaneously encoding two motion vectors. Each screen is divided into macroblocks like MPEG1 / 2, and motion vectors that need to be encoded are indicated by arrows for each macroblock. That is, a macroblock without an arrow indicates that it is not necessary to encode a motion vector because the macroblock has been encoded in the screen or the encoding has been omitted. FIG. 18A shows the first
18 (b) means the second motion vector 301. FIG. Motion vectors can be efficiently coded by using the correlation between adjacent motion vectors, but when the number of motion vectors is small, the coding efficiency is not improved because the correlation between adjacent motion vectors cannot be used sufficiently. . Therefore, if there is a correlation between the first motion vector 300 and the second motion vector 301, a part of one motion vector is collectively encoded with the other motion vector, so that a correlation between adjacent motion vectors is obtained. It can be used effectively. FIG. 18C shows the state shown in FIG.
When the motion vector of FIG. 18A exists, the motion vector is set as the motion vector of FIG. 18C. When the motion vector of FIG. 18A does not exist and when the motion vector of FIG. The motion vector is shown in FIG.
Of the motion vector. On the other hand, FIG.
In the case where both the motion vector of FIG. 18A and the motion vector of FIG. 18B exist, the motion vector of FIG. 18B is used as the motion vector of FIG.
If each of the motion vectors in FIG. 18 (c) can be correctly specified at the time of decoding as to whether the motion vector in FIG. 18 (a) or FIG. 18 (b), the motion vector in FIG. 1) instead of encoding the motion vector
By encoding the motion vector of FIG. 8 (c) and the motion vector of FIG. 18 (d), it is possible to correctly encode and decode the motion vector. Since the number of adjacent motion vectors in the motion vector of FIG. 18C is large, efficient encoding can be performed by sufficiently utilizing the correlation between adjacent motion vectors, while FIG. 18) has a strong correlation with the motion vector at the same macroblock position, so that efficient encoding using the correlation between the motion vectors of FIGS. 18D and 18C is possible.

The image signal is an image signal for each object, and the motion vector of the shape signal of the object corresponds to FIG. 18 (a), and the motion vector of the pixel value signal of the object corresponds to FIG. 18 (b). The shape signal is a signal that identifies whether the object is inside or outside the object. Since the value is uniform inside and outside the object, the effect of motion compensation coding of the shape information is limited to the contour of the object. Is done. In the coding of an object shape signal, coding is conventionally performed in the following four modes.

1. 1. A code indicating that the object is outside the object. 2. Code indicating that the object is inside the object 3. A code indicating the intra-frame encoding at the object boundary portion and intra-frame encoded data. These are a code indicating motion compensation coding, a motion vector, and motion compensation coded data. From this,
4. Since the motion vector of the shape is not encoded except in the case of, if the motion vector is encoded, it can be uniquely determined from the shape signal that the motion vector is always the motion vector of the pixel value signal. Further, the shape signal inside the object is always 2. , The motion vector inside the object can always be determined to be the motion vector of the pixel value signal. By doing so, no special additional information is needed.
It is possible to specify whether each of the motion vectors in (d) is the motion vector in FIG. 18 (a) or the motion vector in FIG. 18 (b). FIG. 19 is an explanatory diagram of the concept of specifying which motion vector.

The coding determiner 310 calculates the motion vector information 3
18 or the motion vector shown in FIG.
It is determined which of the motion vectors in FIG. 8B is to be encoded by the motion vector encoder 313. The motion vector information 306 is for notifying whether or not each of the motion vectors shown in FIGS. 18A and 18B exists, and the coding mode of the shape signal described with reference to FIG. 19 is an example. The switch 311 selects one of the first motion vector 300 and the second motion vector 301 according to a command from the encoding determiner 310, encodes the selected motion vector with the motion vector encoder 313, and outputs it as a motion vector encoded signal 302. The switch 312 is used when the encoding of the second motion vector 301 is necessary (the motion vector exists) and the encoding is not performed by the motion vector encoder 313, or when the encoding of the second motion vector 301 is performed. Is necessary (there is a motion vector), and when some information of the second motion vector 301 is not encoded by the motion vector encoder 313, the motion vector encoder 314 encodes the motion It is output as a vector coded signal 303. The input motion vector is the first motion vector 30
When it is necessary to change the encoding method of the motion vector encoder 313 depending on either 0 or the second motion vector 301, the encoding decision unit 310 issues a command to the motion vector encoder 313 to perform encoding. Switch ways. When only a part of the second motion vector 301 is encoded by the motion vector encoder 313, the data of the second motion vector 301 which is not encoded by the motion vector encoder 313 is used. Is encoded.

(Embodiment 16) FIG. 20 shows Embodiment 1 of the present invention.
6 is a block diagram of a motion vector decoding device No. 6; FIG. In the same figure, devices that operate in the same way as the devices of the motion vector encoding device according to the fifteenth embodiment of FIG.
The description of the operation is omitted. A motion vector decoder 315 decodes a motion vector and outputs a decoded motion vector 304. A motion vector decoder 316 decodes a motion vector and outputs a decoded motion vector 305. Switch 318 for switching the output of the encoder 313 is a motion vector encoder 314.
Is a switch for switching the output.

The operation of the motion vector decoding apparatus according to the sixteenth embodiment configured as described above will be described below. The motion vector decoding apparatus according to the sixteenth embodiment switches between the switches 317 and 318, the motion vector decoder 315 and the motion vector decoder 316 according to the instruction of the coding determiner 310, and
02 and the motion vector coded signal 303 are decoded, and the same switching as the motion vector coder is performed by the command of the coding determinator 310, whereby the motion vector coder of the fifteenth embodiment of FIG. The encoded signal can be decoded. That is, the motion vector decoder 315 performs the reverse operation of the motion vector encoder 313 of FIG. 17 according to the instruction of the encoding determiner 310, and the motion vector decoder 316 performs the operation of the motion vector encoder 31 of FIG.
4 is performed in the reverse order. Note that when only a part of the second motion vector 301 is encoded by the motion vector encoder 313 in FIG. 17, other data is referred to with reference to a part of the data decoded by the motion vector decoder 315. Is decoded by the motion vector decoder 316. The switches 317 and 318 output the decoded first motion vector as the decoded motion vector 304 and output the decoded second motion vector as the decoded motion vector 305 in response to an instruction from the encoding determiner 310. Switch.

(Embodiment 17) FIG. 21 shows a specific example of a motion vector encoding method for encoding two motion vectors. As shown in FIG. 21A, the first motion vector is a motion vector with integer precision, and the second motion vector is a motion vector with real number precision. Therefore, the first motion vector encoder (the motion vector encoder 31 in FIG. 17)
In 3), since integer precision is sufficient to encode the first motion vector, it is appropriate from the viewpoint of encoding efficiency to use a motion vector encoder that performs encoding with integer precision.
On the other hand, considering that the first motion vector and the second motion vector are simultaneously encoded, the second motion vector encoder (the motion vector encoder 314 in FIG. 17) as shown in FIG. ) Requires real number precision to encode the second motion vector. However, there is no first motion vector and the second motion vector with real precision
When encoding is performed by the motion vector encoder, the first motion vector encoder can encode only integer precision, and thus cannot perform encoding with real number precision. Therefore, FIG.
As shown in (c), the real number is separated into an integer part and a decimal part,
If the integer part is encoded by the first motion vector encoder and the decimal part is encoded by the second motion vector encoder, the second
Can be encoded with decimal precision.

It should be noted that the second motion vector encoder encodes a motion vector including an integer part (when encoding the second motion vector) and encodes only a decimal part. It is also possible to switch the coding scheme or switch the code table of the variable length code. Also, the operation of the motion vector encoder has been described, but it is obvious that a motion vector decoder can also realize the same.

(Embodiment 18) The present invention is realized by a program, and is recorded on a recording medium such as a floppy disk and transferred, so that it can be easily implemented by another independent computer system. . FIG. 22 shows a floppy disk as an example of the recording medium.

In the eighteenth embodiment, a floppy disk is shown as a recording medium.
-If the program can be recorded, such as a ROM or a cassette, the present invention can be similarly implemented.

Further, in the first to seventeenth embodiments, only the embodiment in which there are two motion vector predicted value candidates and the number of motion vectors to be coded has been described. it can.

[0071]

As described above, according to the present invention, the reference value specifying signal is adaptively encoded when there are a plurality of predicted values of the motion vector, so that the reference value can be obtained without deteriorating the encoding efficiency. The value specifying signal can be saved and the coding efficiency can be greatly improved. Further, when there are a plurality of motion vectors for the pixel value at the same position, encoding the one motion vector as the other motion vector can greatly improve the efficiency of the latter motion vector encoding.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motion vector encoding device according to a first embodiment;

FIG. 2 is an explanatory diagram when a motion vector is selected from within a screen.

FIG. 3 is an explanatory diagram when a motion vector is selected from between screens;

FIG. 4 is a block diagram of a motion vector decoding device according to a second embodiment;

FIG. 5 is a block diagram of a motion vector encoding device according to a third embodiment;

FIG. 6 is a block diagram of a motion vector decoding device according to a fourth embodiment.

FIG. 7 is a block diagram of a specific configuration example of an encoding determination unit 30;

FIG. 8 is a block diagram of a specific configuration example of a reference value determiner 31;

FIG. 9 is a block diagram of a specific configuration example of a motion vector encoder 23;

FIG. 10 is a block diagram of a specific configuration example of a motion vector decoder 24;

FIG. 11 is a block diagram of an image encoding device according to a ninth embodiment.

FIG. 12 is a block diagram of an image decoding apparatus according to a tenth embodiment.

FIG. 13 is a block diagram of an image encoding device according to an eleventh embodiment.

FIG. 14 is a block diagram of an image decoding apparatus according to a twelfth embodiment.

FIG. 15 is a block diagram of a specific configuration example of a motion compensation encoder 220;

FIG. 16 is a block diagram of a specific configuration example of a motion compensation decoder 221.

FIG. 17 is a block diagram of a motion vector encoding device according to a fifteenth embodiment;

FIG. 18 is an explanatory diagram for simultaneously encoding two motion vectors.

FIG. 19 is an explanatory diagram of a concept for specifying which motion vector is used.

FIG. 20 is a block diagram of a motion vector decoding device according to a sixteenth embodiment.

FIG. 21 is a diagram showing a specific example of a motion vector encoding method.

FIG. 22 is a block diagram of a recording medium according to Embodiment 18 of the present invention;

[Explanation of symbols]

 20, 30, 310 Encoding decision unit 21, 31 Reference value decision unit 23, 313, 314 Motion vector encoding unit 24, 315, 316 Motion vector decoding unit

Claims (21)

[Claims] 1. A motion vector encoding method for encoding a motion vector input with reference to a plurality of motion vector prediction value candidates, wherein a motion vector prediction value is determined from the plurality of motion vector prediction value candidates. A motion vector prediction value is derived in one of two modes, a mode and a mode in which one of the plurality of motion vector prediction value candidates is selected according to a predetermined rule, and the input motion is determined with reference to the motion vector prediction value. A motion vector coding method for outputting a coded signal obtained by coding a vector and a signal indicating the mode. 2. A motion vector coded by referring to a coded signal obtained by coding a motion vector and a signal indicating a motion vector selection mode referred to in the coding, and referring to a plurality of motion vector prediction value candidates. A motion vector encoding method for decoding a plurality of motion vector prediction values from the plurality of motion vector prediction value candidates corresponding to the selection mode, A motion vector decoding method that derives a motion vector prediction value by selecting one of the above, and decodes the input coded signal with reference to the motion vector prediction value to output a motion vector. 3. An image encoding method for encoding an image signal input with reference to a plurality of motion vector prediction value candidates, wherein a mode for determining a motion vector prediction value from the plurality of motion vector prediction value candidates is provided. And deriving a motion vector prediction value in one of two modes of selecting one of the plurality of motion vector prediction value candidates according to a predetermined rule, and referring to the motion vector prediction value, the input image signal. An image encoding method for outputting an encoded signal obtained by encoding the above and a signal indicating the mode. 4. An image signal obtained by inputting an encoded signal obtained by encoding an image signal and a signal indicating a motion vector selection mode referred to in the encoding, and referring to a plurality of motion vector prediction value candidates. An image decoding method for decoding a plurality of motion vector prediction values from the plurality of motion vector prediction value candidates corresponding to the selection mode, or from the plurality of motion vector prediction value candidates An image decoding method for selecting one of them to derive a motion vector prediction value, decoding the input coded signal with reference to the motion vector prediction value, and outputting an image signal. 5. A motion vector encoding method for encoding a motion vector input with reference to a plurality of motion vector prediction value candidates, wherein the plurality of motion vector prediction value candidates are satisfied when a predetermined condition is satisfied. The candidates are compared with each other and one is selected according to a predetermined rule to obtain a motion vector prediction value. If the predetermined condition is not satisfied, a predetermined reference is made by referring to the input motion vector from the plurality of motion vector prediction value candidates. Selecting one as a motion vector prediction value by using the rule of (1) and generating information for specifying the selected motion vector prediction value, encoding the input motion vector with reference to the motion vector prediction value, A motion vector encoding method that outputs information specifying a vector prediction value and a signal obtained by encoding the motion vector. 6. The motion vector encoding method according to claim 5, wherein the predetermined condition is that a plurality of motion vector prediction value candidates are compared with each other to calculate a difference between the candidates, and the difference is equal to or smaller than a predetermined value. 7. A motion vector decoding method for decoding an input motion vector coded signal with reference to a plurality of motion vector predicted value candidates and information for specifying a motion vector candidate from the motion vector predicted value candidates. When a predetermined condition is satisfied, the plurality of motion vector prediction value candidates are compared with each other, and one is selected according to a predetermined rule to obtain a motion vector prediction value, and when the predetermined condition is not satisfied, One of the plurality of motion vector predicted value candidates is selected with reference to information for specifying a vector predicted value to be a motion vector predicted value, and the input and encoded motion vector is referred to by referring to the motion vector predicted value. A motion vector decoding method for decoding and outputting. 8. The motion vector decoding method according to claim 7, wherein the predetermined condition is that a plurality of motion vector prediction value candidates are compared with each other to calculate a difference therebetween, and the difference is equal to or less than a predetermined value. 9. A motion vector encoding method for encoding one or more motion vectors, wherein one of the plurality of motion vectors is selected, and the selected motion vector is encoded by a first method. A motion vector coding method for coding a non-selected motion vector by a second method when it is necessary to code a non-selected motion vector. 10. The motion vector encoding method according to claim 9, wherein when encoding at least one motion vector, encoding is always performed by the first method. 11. A motion vector decoding method for decoding a plurality of motion vectors by decoding a coded signal obtained by coding one or more motion vectors, wherein the coded signal is decoded by a first method. The vector is decoded, and if two or more motion vectors are encoded in the encoded signal, the motion vector is decoded by the second method, and if the number of motion vectors is one, the motion vector is decoded by the first method. A motion vector decoding method for determining what a vector corresponds to and outputting as a corresponding motion vector. 12. When encoding at least one of a plurality of motion vectors, encoding is performed by a first method.
2. The motion vector encoding method according to 1. 13. A motion vector encoding apparatus for encoding a motion vector inputted by referring to a plurality of motion vector prediction value candidates, wherein a motion vector prediction value is determined from the plurality of motion vector prediction value candidates by a predetermined value. Encoding determining means for deriving a motion vector predicted value in one of two modes, a mode determined by a rule and a mode of selecting one of the plurality of motion vector predicted value candidates; and referring to the motion vector predicted value. A motion vector encoding device comprising: a motion vector encoding unit that encodes the input motion vector; and outputs a coded signal encoded by the motion vector encoding unit and a signal indicating the mode. 14. A motion vector coded by inputting a coded signal obtained by coding a motion vector and a signal indicating a motion vector selection mode referred to in the coding, and by referring to a plurality of motion vector prediction value candidates. A motion vector prediction device that determines a motion vector prediction value from the plurality of motion vector prediction value candidates according to a predetermined rule in accordance with the selection mode, or the motion vector prediction value candidate And a motion vector decoding unit for decoding the input coded signal by referring to the motion vector prediction value, and Motion vector decoding device for outputting a motion vector decoded by the decoding means. 15. An image coding apparatus for coding an image signal input with reference to a plurality of motion vector prediction value candidates, wherein the motion vector prediction value is calculated from the plurality of motion vector prediction value candidates by a predetermined rule. And a mode in which one of the plurality of motion vector prediction value candidates is selected.
Encoding determination means for deriving a motion vector prediction value in one of two modes, and motion compensation encoding means for encoding the input image signal with reference to the motion vector prediction value, wherein the motion compensation code An image encoding apparatus that outputs an encoded signal encoded by an encoding unit and a signal indicating the mode. 16. An image signal coded by inputting a coded signal obtained by coding an image signal and a signal indicating a motion vector selection mode referred to in the coding, and by referring to a plurality of motion vector prediction value candidates. An image encoding apparatus that adaptively determines a motion vector prediction value from the plurality of motion vector prediction value candidates corresponding to the selection mode, or according to a predetermined rule. Encoding decision means for selecting one of the value candidates to derive a motion vector prediction value, and motion compensation decoding means for decoding the input coded signal with reference to the motion vector prediction value, An image decoding device that outputs an image signal decoded by a motion compensation decoding unit. 17. A motion vector encoding apparatus for encoding a plurality of motion vectors, comprising: a selection unit for selecting one of the plurality of motion vectors; and a first motion vector for encoding the selected motion vector. A motion vector coding apparatus comprising: coding means; and second motion vector coding means for coding the unselected motion vector when it is necessary to code the unselected motion vector. 18. A motion vector decoding device for decoding a plurality of motion vectors by decoding a coded signal obtained by coding one or more motion vectors, comprising: a first decoding means for decoding the coded signal; Motion vector decoding means, second motion vector decoding means for decoding other motion vectors if two or more motion vectors are encoded in the encoded signal, and Encoding determining means for determining to which signal the vector decoded by the first motion vector decoding means corresponds; and a motion vector of a signal corresponding to the motion vector decoded based on the determination result A motion vector decoding device including a selection unit that outputs a motion vector. 19. A motion vector encoding apparatus which encodes a motion vector input by referring to a plurality of motion vector prediction value candidates, wherein said plurality of motion vector prediction value candidates are used as inputs. Encoding determining means for determining whether one of the value candidates can be selected and outputting the determined result; and referring to the output of the encoding determining means, if one of the predicted value candidates cannot be selected, the plurality of motion vector candidates Reference value determining means for comparing a value with the input motion vector, selecting one motion vector prediction value candidate according to a predetermined rule, and outputting information for specifying the selected motion vector prediction value candidate; If one of the predicted value candidates can be selected with reference to the output of the judging means, one of the plurality of motion vector predicted value candidates is selected and output according to a predetermined rule. If one of them cannot be selected, a predicted value generating means for outputting a motion vector predicted value candidate specified by the output of the reference value determining means, and the input motion vector is encoded by referring to the output of the predicted value generating means. A motion vector encoding apparatus comprising: a motion vector encoding means for converting and outputting the reference value determination means and an output of the motion vector encoding means. 20. A motion vector decoding apparatus for decoding a motion vector coded signal inputted by referring to a plurality of motion vector predicted value candidates and information for specifying a motion vector candidate from the motion vector predicted value candidates. Encoding determination means for determining whether one of the plurality of motion vector prediction value candidates can be selected by using the plurality of motion vector candidate values as input and outputting the result, and When one of the predicted value candidates can be selected, one is selected and output according to a predetermined rule from the plurality of motion vector predicted value candidates. When one of the predicted value candidates cannot be selected, the motion vector is selected. Prediction value generation means for outputting a motion vector prediction value candidate corresponding to the information specifying the candidate,
Motion vector decoding means for decoding the input motion vector coded signal with reference to the output of the prediction value generation means and outputting the decoded signal, wherein the motion vector decoding means outputs the output of the apparatus. apparatus. 21. A recording medium for a computer, wherein a program for implementing at least one of claims 1 to 12 is recorded.