JP2004186839A - Moving picture encoding method and moving picture decoding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance an encoding efficiency by improving a prediction efficiency of particularly a color difference component in encoding between different field images. <P>SOLUTION: A production method of a motion vector of a color difference component is adaptively switched on the basis of parities of a reference source field and a reference destination field and information denoting a sampling positional relation of pixels of luminance and color difference in a Top field and a Bottom field in the case of predicting inter-fields with different parities. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a video encoding device and a video transcoding device having an inter-field prediction mode.
[0002]
[Prior art]
Since moving image data generally has a large data amount, high-efficiency coding is performed when it is transmitted from a transmitting device to a receiving device or when it is stored in a storage device. Here, “high-efficiency encoding” is an encoding process for converting a certain data sequence into another data sequence, and refers to a process for compressing the data amount.
[0003]
The moving image data includes data mainly including only frames and data including fields. Hereinafter, a conventional technique of a method of compressing a field image will be mainly described.
[0004]
As a high-efficiency encoding method for moving image data, an inter-frame / field prediction encoding method is known. FIG. 1 shows a block diagram of this interframe / field predictive coding. This encoding method utilizes the fact that moving image data has high correlation in the time direction. Briefly explaining the operation of FIG. 1, a difference image between an input original image and a prediction image is generated by a subtractor 39, and the difference image is subjected to an orthogonal transformation unit 31, a quantization unit 32, and a coefficient entropy encoding unit. Encode at 40. Further, the output of the quantization means 32 is restored to a difference image by the inverse quantization means 33 and the inverse orthogonal transform means 34, and the output is decoded from the difference image restored by the decoded image generation means 35 and the prediction image used at the time of encoding. Restore the image. The restored image is stored in the decoded image storage means 36, a motion vector calculation means 37 calculates a motion vector between the next input image, and a predicted image generation means 38 Generate an image. The generated motion vector is encoded by the vector entropy encoding unit 41, and is output via the MUX 42 together with the coefficient encoded data encoded by the coefficient entropy encoding unit 40. That is, moving image data generally has a high similarity between frame / field data at a certain timing and frame / field data at the next timing in many cases. I do. For example, in a data transmission system using an inter-frame / field predictive encoding method, in a transmission device, motion vector data representing “motion” from a previous frame / field image to a target frame / field image, and the previous frame / Difference data between the predicted image of the target frame / field and the actual image of the target frame / field created using the motion vector data from the image of the / frame, and sends the motion vector data and the difference data to the receiving device. I do. On the other hand, the receiving device reproduces an image of the target frame / field from the received motion vector data and difference data.
[0005]
The outline of the inter-frame / field predictive encoding in FIG. 1 has been described above, and the frame predictive encoding and the field predictive encoding will be further described below.
[0006]
FIGS. 2 and 3 show the above-mentioned ISO / IEC MPEG-2 / MPEG-4 (hereinafter referred to as MPEG-2, MPEG-4) and, as of August 2002, jointly standardized by ITU-T and ISO / IEC. ITU-TH. This is a description of a format used for encoding a field image, which is commonly used in Final Committee Draft (hereinafter abbreviated as AVC FCD) of H.264 / ISO / IEC MPEG-4 Part 10 (Advanced Video Coding: AVC). That is, each frame includes two fields, that is, a Top field and a Bottom field. FIG. 2 is a diagram illustrating the position of each pixel of luminance and color difference and the field to which they belong. As shown in FIG. 2, the odd-numbered lines of the first luminance line (50a), the third luminance line (50b), the fifth luminance line (50c), the seventh luminance line (50d),. The even-numbered lines such as the second luminance line (51a), the fourth luminance line (51b), the sixth luminance line (51c), the eighth luminance line (51d), etc., belong to the Bottom field. Similarly, the odd-numbered lines such as the first color difference line (52a), the third color difference line (52b)... Belong to the Top field, and the second color difference line (53a) and the fourth color difference line (53b). .. Belong to the Bottom field.
[0007]
The Top field and the Bottom field represent images at different times. Next, the spatial and temporal arrangement of the Top field and the Bottom field will be described with reference to FIG.
[0008]
Note that, from FIG. 3 onward, since the technology according to the present invention relates to the vertical component of the motion vector, in this specification, the pixel of the horizontal component is not shown, and the horizontal component of the motion vector is All are described as 0 for convenience. Further, in order to show the problems of the related art and the effects of the present invention, the positional relationship between the luminance and color difference pixel positions in each field is correctly illustrated.
[0009]
In FIG. 3, the vertical axis represents the pixel position of the vertical component of each field, and the horizontal axis represents the passage of time. Note that, in the horizontal components of the pixels of each image, there is no displacement of the position due to the field, and therefore, illustration and description of the pixels in the horizontal direction are omitted in this figure.
[0010]
As shown in FIG. 3, the pixel position of the chrominance component has a vertical component shifted by ４ pixel from the pixel position in the luminance field. This is because when a frame is composed of both the Top and Bottom fields, the relationship of the pixel positions as shown in FIG. 2 is satisfied. The time between both adjacent fields of each Top and Bottom (64a: 65a, 65a: 64b...) Is about 1/60 second in the case of the NTSC format. The time from the Top field to the Top field (64a: 64b...) Or the time from the Bottom field to the Bottom field (65a: 65b...) Is approximately 1/30 second.
[0011]
Hereinafter, the frame prediction coding mode and field prediction of a field image, which are adopted in MPEG-2 and AVC FCD, will be described. FIG. 4 illustrates a method of forming a frame from two consecutive fields (adjacent Top and Bottom fields) in the frame prediction mode. As shown in this figure, the frame is reconstructed from two temporally continuous fields (Top and Bottom fields).
[0012]
FIG. 5 illustrates the frame prediction mode. In this figure, it is assumed that each of the frames 84a, 84b, 84c,... Has been reconstructed from two consecutive fields (Top and Bottom fields) as described in FIG. In this frame prediction mode, encoding is performed on an encoding target frame composed of both Top and Bottom fields. As a reference image, one reference frame is formed from two fields (Top and Bottom fields) accumulated for continuous reference, and is used for prediction of a pre-encoding target frame. Then, the two frame images are encoded according to the block diagram shown in FIG. In the case of the frame prediction encoding mode, as for the method of expressing a motion vector, a zero vector, that is, (0, 0) indicates pixels at the same spatial position. Specifically, for a pixel 82 of luminance belonging to Frame # 2 (84b), a motion vector indicating a motion vector (0, 0) indicates a pixel position 81 of Frame # 1 (84a).
[0013]
Next, the field prediction encoding mode will be described. FIG. 6 is a diagram for explaining a prediction method in the inter-field prediction mode. In the field prediction mode, an encoding target is a single Top field (94a, 94b,...) Or a Bottom field (95a, 95b,...) Input as an original image. As a reference image, a Top field or a Bottom field stored in the past can be used. Here, that the original image field and the reference field have the same parity is generally defined as that both the original image field and the reference field are Top fields or both are Bottom fields. For example, in the field prediction of the same parity 90 in the figure, both the original image (94b) and the reference (94a) are Top fields. Similarly, that the original image field and the reference field have different parities is generally defined as one of the original image field and the reference field being the Top field and the other being the Bottom field. For example, in the field prediction of a different parity illustrated in FIG. 91, the original picture is a Bottom field (95a), and the reference is a Top field (94a). Then, the original image field image and the reference field image are encoded according to the block diagram shown in FIG.
[0014]
In the related art, in both the frame mode and the field mode, a motion vector is obtained based on the position of a pixel in each frame / field. A method of calculating a motion vector and a method of associating pixels when a motion vector is given in the conventional method will be described.
[0015]
FIG. 7 is a diagram that defines the coordinates of a frame / field image that is widely used in encoding such as MPEG-2, MPEG-1, and AVC FCD. In the figure, a white circle is a target frame / field and is a pixel definition position (271). Here, with respect to the coordinates in the frame / field image, the origin (0, 0) is set at the upper left in the screen, and the defined positions of the pixels in the horizontal and vertical directions are 1, 2, 3,. Value is assigned. That is, the coordinates of the nth pixel in the horizontal direction and the mth pixel in the vertical direction are (n, m). According to this, the coordinates of the position where the pixel is interpolated are similarly defined. That is, as for the position 270 of ● in the figure, the position of the position 270 is (1.5, 2.0) since it is located 1.5 pixels horizontally and 2 pixels vertically from the upper left pixel. It is expressed as Note that, in the field image, there are only half the pixels of the frame image in the vertical direction, but even in this case, the pixels are handled in the same manner as in FIG. 7 based on the positions of the pixels existing in each field.
[0016]
The definition of a motion vector between fields will be described using the coordinate system shown in FIG. FIG. 8 is a diagram illustrating a conventional method of calculating a motion vector between corresponding pixels between fields. In order to define a motion vector, a reference source position and a reference destination position are required. Then, a motion vector is defined between these two points. Here, a motion vector between a point whose coordinates 201 in the reference source field is (Xs, Ys) and a point whose coordinates 202 in the reference destination field are (Xd, Yd) is obtained. In a conventional method of calculating a motion vector between pixels corresponding to between fields, a motion vector is obtained by the same method described below, regardless of whether a reference source or a reference destination is a Top field or a Bottom field. I was In other words, the reference source field coordinates 201 (Xs, Ys) and the reference destination field coordinates 202 (Xd, Yd) are input to the motion vector calculation means 200, and (Xd-Xs, Yd) −Ys).
[0017]
FIG. 9 is a diagram illustrating a method of calculating a pixel indicated by a motion vector defined between fields in the related art. Here, it is assumed that the motion vector is derived by the method of FIG. In order to obtain the coordinates of the reference destination, the position of the reference source and the motion vector are required. In the case of this figure, (X, Y) of the motion vector 211 is given to a point whose coordinates 212 in the reference source field are (Xs, Ys), and the reference destination field obtained using both of them is obtained. It is assumed that the coordinates of are obtained. In the conventional method of calculating a motion vector between pixels corresponding to between fields, the reference source and the reference destination are determined by the same method described below, regardless of whether the Top field or the Bottom field is used. Was required. That is, the motion vector 211 (X, Y) and the reference source field coordinates 212 (Xs, Ys) are input to the pixel association unit 210, and the coordinates (Xs + X, Ys + Y) are given as the reference destination field coordinates 213. is there.
[0018]
The definition of the relationship between the vector and the pixel position in FIG. 9 is the same for the luminance component and the color difference component. Here, in the MPEG-1 / MPEG-2 / AVC FCD, which is a general moving picture coding method, only a luminance component is encoded as a vector, and a color difference component vector is derived by scaling the luminance component. Is done. In particular, in the AVC FCD, since the chrominance component is half the number of pixels of the luminance component in both the number of vertical pixels and the number of horizontal pixels, the motion vector for calculating the prediction pixel of the chrominance component is obtained by accurately calculating the motion vector of the luminance component. It is stipulated that it is scaled by half. FIG. 10 is a diagram illustrating a method of obtaining a color difference component motion vector from such a conventional luminance component motion vector.
[0019]
That is, when the luminance component motion vector 221 is (MV # x, MV # y) and the chrominance component motion vector is 222 (MVXC # x, MVXC # y), the chrominance component motion vector 222 is By means 220
(MVXC # x, MVXC # y) = (MV # x / 2, MV # y / 2) (Equation 1)
It is obtained according to the formula. In the conventional method, this derivation method is irrespective of whether the motion vector predicts between fields having the same parity or between fields having different parities.
[0020]
In the AVC FCD, the accuracy of the motion vector of the luminance component can be 1/4 pixel accuracy or 1/8 pixel accuracy. From this, as a result of Expression 1, a vector having a precision of a decimal point of 1/8 pixel precision or 1/16 pixel precision can be taken as the precision of the motion vector of the color difference component. FIG. 21 illustrates a method of calculating an interpolated pixel of a color difference component defined by the AVC FCD. In the figure, black circles indicate integer pixels, and dotted white circles indicate interpolation pixels. Here, the horizontal coordinate of the interpolation pixel G (256) is obtained by internally dividing each horizontal coordinate of the point A (250) and the point C (252) into α: 1−α, and the vertical coordinate is , And the vertical coordinates of point A (250) and point B (251) are internally divided into β: 1−β. Here, α and β are 0 or more and less than 1. When calculating the interpolated pixel G (256) defined by the position as described above, the surrounding integer pixels A (250), B (251), C (252), D (253), and α and β are used. Therefore, it is calculated as follows.
[0021]
G = (1-α) · (1-β) · A + (1-α) · β · B + α · (1-β) · C + α · β · D (Equation 2)
The method of interpolating the pixel of the color difference component using FIG. 21 is an example for obtaining an interpolated pixel, and there is no problem if another calculation method is used.
[0022]
[Non-patent document 1]
Document of Joint Video Team (JVT) of ISO / IEC and ITU-T VCEG
Document Name: Document JVT-D157d1
Title: Joint Final Committee Draft (JFCD) of Joint Video Specification (ITU-T Rec. H.264 | ISO / IEC 11496-10 AVC)
・ 6.1 Picture formats ・ ・ page 7
・ 6.2 Spatial subdivision of a picture into macroblocks ・ ・ page 9
・ 8.4.1.4 Chroma vectors ・ ・ page 63
・ 8.4.2.3 Chroma interpolation ・ ・ page 65
Generated: 2002/08/08
[0023]
[Problems to be solved by the invention]
In the case of this field coding mode, in prediction between fields having different original picture fields and reference fields, that is, fields having different parities, according to the definition of AVC FCD, zero vectors of both motion vectors of a luminance component and a chrominance component are not parallel. That is, in the conventional definition, when prediction is performed using the motion vector of the chrominance component obtained from the motion vector of the luminance component, a pixel at a position spatially shifted from the luminance component is used. This will be described with reference to FIG. In the drawing, it is assumed that the Top field 130, the Bottom field 131, and the Top field 132 are temporally continuous with time. Here, the Bottom field 131 is about to be encoded using the Top field 130. At this time, in the inter-field coding, the motion vector between the same lines in each field is defined as zero in the vertical direction. Therefore, when the zero vector (0, 0) is assigned to the pixel 133 a having the luminance belonging to the bottom field 131, this pixel is predicted from the pixel 135 a of the top field 130. Similarly, when the zero vector (0, 0) is assigned to the pixel 134 a of the color difference belonging to the bottom field 131, this pixel is predicted from the pixel 137 a of the top field 130. Similarly, the luminance pixel 133b and the chrominance pixel 134b belonging to the Top field 132 are predicted from the pixels 135b and 137b on the Bottom field 131, respectively. Since it is originally preferable that the motion vector of the color difference and the luminance be the same, if the motion vector of the luminance is left as it is, the pixels of the original color differences 134a and 134b are predicted from the positions of 136a and 136b, respectively. It is something to do.
[0024]
As mentioned above, prediction between fields with different parity
-The zero vectors of luminance and color difference are not parallel.
[0025]
That point was explained. This causes the following problem in the AVC FCD for all vectors in prediction between fields having different parities. Figures 12 and 13 illustrate this problem. Indicate the problem according to the AVC FCD.
FIG. 12 is a diagram for explaining a problem when a chrominance motion vector is obtained from a luminance motion vector in the related art when a reference destination is a Bottom field and a reference source is a Top field. In the AVC FCD, since the color difference component is half the number of pixels of the luminance component in both the number of vertical pixels and the number of horizontal pixels as in Equation 1, the motion vector for obtaining the predicted pixel of the color difference component is the motion of the luminance component. It is defined as a vector scaled by a factor of two. This is regardless of whether the motion vector predicts between frames, between fields of the same parity, or between fields of different parity.
[0026]
Now, it is shown that this definition poses a problem when obtaining a color difference motion vector from a luminance motion vector defined between fields of different parities. In FIG. 12, the pixel 140 of the reference source Top field luminance component has (0, 1) as the prediction vector, and as a result, the pixel position 141 of the reference destination Bottom field luminance component is indicated as the prediction value.
[0027]
In this case, the motion vector of the chrominance pixel belonging to the same block is obtained as the motion vector (0, 1/2) according to Equation 1. Then, when the prediction is performed using the motion vector (0,）) as the prediction value of the pixel 142 of the reference source Top field color difference component, the pixel position 143 of the reference destination Bottom field color difference component is used as the prediction value. .
[0028]
In this case, the luminance motion vector (0, 1) and the color difference motion vector (0, 1/2) are not parallel. Preferably, it is necessary to use the predicted pixel position 145 of the color difference component of the reference Bottom field to which a motion vector of a color difference parallel to the motion vector of the luminance is applied.
[0029]
FIG. 13 is a diagram for explaining a problem in obtaining a chrominance motion vector from a luminance motion vector in the related art when a reference destination is a Top field and a reference source is a Bottom field. As in the description of FIG. 12, in FIG. 13, the pixel 150 of the reference source Bottom field luminance component has (0, 1) as a prediction vector, and as a result, the pixel position 151 of the reference Top field luminance component is set to the predicted value. Pointed out.
[0030]
In this case, the motion vector of the chrominance pixel belonging to the same block is obtained as the motion vector (0, 1/2) according to Equation 1. Then, when the prediction is performed using the motion vector (0, 1/2) as the prediction value of the pixel 152 of the reference source Bottom field color difference component, the pixel position 153 of the reference destination Top field color difference component is used as the prediction value. .
[0031]
In this case, the luminance motion vector (0, 1) and the color difference motion vector (0, 1/2) are not parallel. Preferably, it is necessary to use the predicted pixel position 155 of the color difference component of the reference Top field to which a motion vector of a color difference parallel to the luminance motion vector is applied.
[0032]
As described above, when the parity of the field of the reference destination and the parity of the field of the reference source are different, the conventional prediction method refers to the pixel at the position shifted by the luminance and the chrominance. However, in the predicted image, the predicted image is shifted by the luminance and the color difference.
[0033]
[Means for solving the problem]
The present invention solves the above problem.
[0034]
First, the present invention (claim 1, claim 2, claim 3) in encoding will be described.
[0035]
According to the present invention, in a moving picture coding method for performing motion compensation prediction between fields for a moving picture signal composed of a plurality of fields, a motion vector of a luminance component and luminance and color difference pixels in a Top field and a Bottom field are used. A motion vector of a chrominance component parallel to the luminance component motion vector is generated from format information indicating the sampling positional relationship of the motion vector and the parities of the reference field and the reference source field of the motion vector. Claim 1).
[0036]
Further, in the present invention, in a moving picture coding method for performing motion compensation prediction between fields for a moving picture signal composed of a plurality of fields, a motion vector of a luminance component, a motion vector of a luminance component, a Top field, and a Bottom field. A plurality of chrominance component motion vector generation means for generating a chrominance component motion vector from format information indicating the sampling position relationship of the luminance and chrominance pixels in the pixel. A color difference component motion vector generation unit for selecting a color difference component motion vector generation unit used for generating a vector; and generating a color difference component prediction vector from the luminance information motion vector information by the color difference component motion vector generation unit selected by the selection unit. Characteristic video encoding method Claim 2). Here, the selection means selects one that generates a motion vector of a color difference component parallel to the luminance component.
[0037]
Here, the following three types of color difference component motion vector generating means are provided. First, the first chrominance component motion vector generation means is selected by the selection means when the reference destination field and the reference source field have the same parity. The second color difference component motion vector generation means is selected by the selection means when the reference destination field is the Top field and the reference source field is the Bottom field. The third chrominance component motion vector generation means is selected by the selection means when the reference field is a Bottom field and the reference source field is a Top field.
[0038]
The method of obtaining the motion vector of the color difference component parallel to the motion vector of the luminance component depends on the parity and format information of the reference source field and the reference destination field of the motion vector. When the two fields have the same parity, there are three types of cases: the former is a Top field and the latter is a Bottom field, and the former is a Bottom field and the latter is a Top field. Further, the calculation method is determined so that the luminance component and the color difference component become parallel according to the format information.
[0039]
In the present invention, an appropriate one is selected from the means for generating three types of color difference component motion vectors parallel to the luminance component motion vector according to the reference source and reference destination fields and format information, and the motion of the color difference component is selected. Generate a vector.
[0040]
In addition, claim 2 of the encoding method corresponds to claim 4 of the decoding method, and similarly claim 3 corresponds to claim 5, and the decoding side basically has the same function as the encoding side. Acts similarly.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present embodiment, an encoding apparatus will be mainly described using an example to which claims 1 and 2 are applied. Since the present invention relates to a vertical component of a motion vector, all horizontal components of the motion vector are set to 0 for convenience. Further, an embodiment to which the third and fourth aspects of the decoding apparatus are applied has the same configuration as that of the present embodiment.
[0042]
Hereinafter, embodiments will be described on the assumption that the present invention is applied to an AVC FCD.
[0043]
FIG. 14 is a diagram illustrating a method of calculating a color difference motion vector from a luminance motion vector according to the present invention. In this embodiment, in the embodiment of the means for generating a motion vector of a chrominance component from the motion vector of a luminance component in the field prediction, it is composed of three types of motion vector generation means for a chrominance component and one selecting means.
[0044]
The operation of the present invention in FIG. 14 will be described below. First, the motion vector 231 of the given luminance component is set to (MV # x, MV # y). Then, the luminance component vector 231 and the format information 239 are input to the first chrominance component motion vector generation unit 233, the second chrominance component motion vector generation unit 234, and the third chrominance component motion vector generation unit 235. give. Then, each output is input to the selection means 230. Then, the selection unit 230 determines the first, second, and third color difference component motion vector generation units based on the information of the parity 237 of the input source field of the motion vector and the parity 238 of the reference destination of the motion vector. One of the outputs is selected and output as a vector component (MVC # x, MVC # y) of the motion vector 232 of the color difference component.
[0045]
The operation of the first chrominance component vector generation means 233, the second chrominance component vector generation means 234, and the third chrominance component vector generation means 235 of FIG. 14 will be described below with reference to FIGS.
[0046]
FIG. 15 is a diagram illustrating a first color difference motion vector generation unit. In this embodiment, a luminance motion vector 261 having a vector value of (MV # x, MV # y) and format information 263 are input to the first chrominance component motion vector generating means 260, and (MVXC1 # x, MVXC1 # y) to output the first color difference motion vector candidate 262 having the vector value. Then, the first chrominance motion vector candidate 262 is calculated by the chrominance component motion vector generation means 260 from the luminance motion vector 261 as follows:
(MVXC1 # x, MVXC1 # y) = (MV # x / 2, MV # y / 2) (Equation 3)
Is calculated according to
[0047]
Then, the obtained first color difference motion vector candidate 262 is output to the selection means.
[0048]
FIG. 16 is a diagram for explaining the second chrominance motion vector generation means 270. In the present embodiment, a luminance motion vector 271 having a vector value of (MV # x, MV # y) and format information 273 are input to the second chrominance component motion vector generating means 270, and (MVXC2 # x, MVXC2 # y), indicating that a second color difference motion vector candidate 272 having a vector value is output. Then, the second color difference motion vector candidate 272 is obtained from the luminance motion vector 271 by the color difference component motion vector generation unit 270 using the following equation:
(MVXC2 # x, MVXC2 # y) = (MV # x / 2, MV # y / 2 + a) (Equation 4)
Is calculated according to Here, the value a is determined so that the luminance motion vector 271 and the first color difference motion vector candidate 272 are parallel from the format information F 273 representing the relationship between the luminance and the color difference pixel sampling position in the Top field and the Bottom field. Is done. One format is selected from a plurality of formats by the format information F273.
[0049]
Here, for example, as shown in FIG. 22, the format F = 0 corresponds to a case where chrominance pixels are arranged near odd-numbered luminance pixels in the Top field and chrominance pixels are arranged near even-numbered luminance pixels in the Bottom field. As shown in FIG. 23, the format F = 1 is the case where the chrominance pixels are arranged near the odd-numbered luminance pixels in both the Top field and the Bottom field.
[0050]
When the format is F = 0 as shown in FIG. 22, a = 1/4. When the format is F = 1 shown in FIG. 23, a = 0. The format information F 273 is not limited to information indicating the type of format, but may be information indicating the phase of the color difference component.
[0051]
The obtained second color difference motion vector candidate 272 is output to the selection unit.
[0052]
FIG. 17 is a diagram illustrating a third color difference motion vector generation unit. In this embodiment, a luminance motion vector 281 having a vector value of (MV # x, MV # y) and format information F283 are input to the third chrominance component motion vector generation unit 280, and (MVXC3 # x, MVXC3 # y) indicating that a third color difference motion vector candidate 282 having a vector value is output. The third color-difference motion vector candidate 282 is obtained from the luminance motion vector 281 by the color-difference component motion vector generation unit 280 using the following equation:
(MVXC3 # x, MVXC3 # y) = (MV # x / 2, MV # y / 2 + b) (Equation 5)
Is calculated according to Here, the value b is determined from the format information 283 so that the luminance motion vector 281 and the first color difference motion vector candidate 282 are parallel. One format is selected from a plurality of formats by the format information F.
[0053]
Here, when the format is F = 0 shown in FIG. 22 as in the above, b = −１ ／. When the format is F = 1 shown in FIG. 23, b = 0. Further, the format information F is not limited to information indicating the type of format, and may be information indicating the phase of the color difference component.
[0054]
Then, the obtained third color difference motion vector candidate 282 is output to the selection means.
[0055]
The format information described above indicates the positional relationship between the luminance pixels and the chrominance pixels of the Top field and the Bottom field. Even if a format other than the format described above is applied, each of the second and third chrominance components The motion vector generating means can cope with this by determining the values of a and b added to the color difference vector so that the motion vector of the color difference component is parallel to the motion vector of the luminance component.
[0056]
FIG. 18 is a view for explaining an embodiment of the selection means 240 in the present invention. First, in the present embodiment, the parity 247 of the reference field of the motion vector and the parity 248 of the reference field of the motion vector are each determined by the condition determination table 241 and the selection information 249 of the chrominance component motion vector generation means to be selected. Is output. In this embodiment, when the condition determination table 241 is used, when both the reference destination field and the reference source field are equal, selection information for selecting the first chrominance component motion vector candidate 244 is output. When the reference field is the Top field and the reference field is the Bottom field, selection information for selecting the second color difference component motion vector candidate 245 is output. When the reference field is a Bottom field and the reference source field is a Top field, selection information for selecting the third chrominance component motion vector candidate 246 is output.
[0057]
Here, the first chrominance component motion vector candidate 244 is at 262 in FIG. 15, the second chrominance component motion vector candidate 245 is at 272 in FIG. 16, and the third chrominance component motion vector candidate 246 is at 282 in FIG. , Are connected respectively. Then, the selector 243 selects one of the first chrominance component motion vector candidate 244, the second chrominance component motion vector candidate 245, and the third chrominance component motion vector candidate 246 according to the above-described selection information 249, (MVC # x, MVC # y) is output as the motion vector 242 of the color difference component.
[0058]
FIG. 19 shows an example of calculating a color difference component vector from a luminance component vector when the reference destination is the Bottom field and the reference source is the Top field according to the present invention. In the example of this figure, the motion vector (MV # x, MV # y) of the luminance for predicting the pixel 160 of the reference source Top field luminance component is (0, 1). In this case, the pixel position 161 of the reference bottom field field luminance component is selected for prediction of the luminance pixel 160. A process of obtaining a chrominance component motion vector for use in prediction of the pixel 162 of the reference source Top field chrominance component according to the configuration of FIG. 14 of the present embodiment will be described below.
[0059]
First, in the case of FIG. 19, the reference destination field is the Bottom field, and the reference source field is the Top field. Therefore, the third chrominance component motion vector candidate is selected as the selection information 249 from the condition determination table 241 in FIG. Here, according to Equation 5, for example, when the format information F = 0 is used, b = −１ ／ is determined so that the luminance motion vector and the third color difference component motion vector candidate become parallel. . Therefore, the third color difference component motion vector candidate is
(MVXC3 # x, MVXC3 # y) = (MV # x / 2, MV # y / 2-１ ／) = (0/2, −−４) = (0, ４) ( Equation 6)
It becomes. Then, this value is output as the motion vector 232 of the color difference component in FIG. When this vector (0, 1/4) is applied to the pixel 162 of the reference source Top field chrominance component, the pixel position 163 of the reference destination Bottom field chrominance component is used as a prediction value. In FIG. 19, the positional relationship between the pixels in the vertical direction corresponds to the actual case. As can be seen from the figure, it can be seen that the luminance component motion vector (0, 1) and the color difference component motion vector (0, ４) are parallel. Accordingly, the color shift between the luminance component and the color difference component, which has been a problem in the related art, is eliminated by the present invention.
FIG. 24 shows an example of a format different from that of FIG. In the example of this figure, the motion vector (MV # x, MV # y) of the luminance for predicting the pixel 300 of the reference source Top field luminance component is (0, 1). In this case, the pixel position 301 of the reference destination Bottom field luminance component is selected for prediction of the luminance pixel 300. A process of obtaining a chrominance component motion vector for use in prediction of the pixel 302 of the reference source Top field chrominance component according to the configuration of FIG. 14 of the present embodiment will be described below.
[0060]
First, in the case of FIG. 24, the reference destination field is a Bottom field, and the reference source field is a Top field. Therefore, the third chrominance component motion vector candidate is selected as the selection information 249 from the condition determination table 241 in FIG. Here, according to Equation 5, for example, when format information F = 1 is used, b = 0 is determined so that the luminance motion vector and the third color difference component motion vector candidate become parallel. Therefore, the third color difference component motion vector candidate is
(MVXC3 # x, MVXC3 # y) = (MV # x / 2, MV # y / 2-0) = (0/2, 1 / 2-0) = (0, 1/2) (Equation 7)
It becomes. Then, this value is output as the motion vector 232 of the color difference component in FIG. When this vector (0, 1/2) is applied to the pixel 302 of the reference source Top field chrominance component, the pixel position 303 of the reference destination Bottom field chrominance component is used as a prediction value. As can be seen from the figure, it can be seen that the luminance component motion vector (0,1) and the color difference component motion vector (0,1 / 2) are parallel. Accordingly, the color shift between the luminance component and the color difference component, which has been a problem in the related art, is eliminated by the present invention.
Similarly, FIG. 20 shows an example of calculating a color difference component vector from a luminance component vector when a reference destination is a Topo field and a reference source is a Bottom field according to the present invention. In the example of this figure, the motion vector (MV # x, MV # y) of the luminance for predicting the pixel 170 of the reference source Bottom field luminance component is (0, 1). In this case, the pixel position 171 of the reference destination Top field luminance component is selected for the prediction of the pixel 170 of the reference source Bottom field luminance component. A process of obtaining a chrominance component motion vector to be used for prediction of the pixel 172 of the reference source Bottom field chrominance component according to the configuration of FIG. 14 of the present embodiment will be described below.
[0061]
First, in the case of FIG. 20, the reference destination field is the Top field, and the reference source field is the Bottom field. From this, the second color difference component motion vector candidate is selected as the selection information 249 by the condition determination table 241 in FIG. Here, according to Equation 4, for example, when the format information F = 0 is used, a = 1/4 is determined so that the luminance motion vector and the second color difference component motion vector candidate become parallel.
[0062]
Therefore, the second color difference component motion vector candidate is
(MVXC2 # x, MVXC2 # y) = (MV # x / 2, MV # y / 2 + ／) = (0/2, +) = (0, 3/4) (Equation 8) )
It becomes. Then, this value is output as the motion vector 232 of the color difference component in FIG. When this vector (0, 3/4) is applied to the pixel 172 of the reference source Bottom field chrominance component, the pixel position 173 of the reference destination Top field chrominance component is used as a prediction value as a position used for prediction. In FIG. 20, the vertical positional relationship of each pixel corresponds to the actual case. As can be seen from the figure, it can be seen that the luminance component motion vector (0, 1) and the chrominance component motion vector (0, 3/4) are parallel.
[0063]
FIG. 25 shows an example of a format different from that of FIG. In the example of this figure, the luminance motion vector (MV # x, MV # y) for predicting the pixel 300 of the reference source Bottom field luminance component is (0, 1). In this case, the pixel position 311 of the reference destination Top field luminance component is selected for prediction of the pixel 310 of the reference source Bottom field luminance component. The process of obtaining a chrominance component motion vector for such a vector for use in predicting the pixel 312 of the reference source Bottom field chrominance component will be described below. The selection information 249 selects the second color difference component motion vector candidate from the condition determination table 241 in FIG. Here, according to Equation 4, for example, when format information F = 1 is used, a = 0 is determined so that the luminance motion vector and the second color difference component motion vector candidate become parallel.
[0064]
Therefore, the second color difference component motion vector candidate is
(MVXC2 # x, MVXC2 # y) = (MV # x / 2, MV # y / 2 + 0) = (0/2, 1/2 + 0) = (0, 1/2) (Equation 9)
It becomes. Then, this value is output as the motion vector 232 of the color difference component in FIG. When this vector (0, 1/2) is applied to the pixel 312 of the reference source Bottom field color difference component, the pixel position 313 of the reference destination Top field color difference component is used as a prediction value as a position used for prediction. As can be seen from the figure, it can be seen that the luminance component motion vector (0,1) and the color difference component motion vector (0,1 / 2) are parallel.
Accordingly, the color shift between the luminance component and the color difference component, which has been a problem in the related art, is eliminated by the present invention.
[0065]
Here, in the examples of FIG. 19, FIG. 20, FIG. 24, and FIG. 25, the case of a specific vector has been described. Prediction without deviation of color difference becomes possible.
[0066]
When the parities of both the reference destination field and the reference source field are equal, the above-described color shift does not occur. Therefore, the same configuration as that of the conventional luminance component motion vector to color difference component motion vector generation unit 220 in FIG. The result of the first chrominance component motion vector means 233 of the present invention is selected and used as the chrominance component motion vector 232. In this case, the chrominance component motion vector obtained by the present invention is equivalent to the result of the prior art, and thus the description in the present embodiment is omitted.
[0067]
Although the present embodiment has been described using the AVC FCD as an example, the description here is one embodiment, and does not limit the other embodiments.
[0068]
【The invention's effect】
According to the present invention, even in a format in which the positional relationship between the luminance pixel and the chrominance pixel is different between the fields having different parities and in the Top field and the Bottom field, the format information is used in parallel with the motion vector of the luminance component. The motion vector of the color difference component can be obtained, the prediction efficiency of the color difference component is improved, and the coding efficiency in moving image coding can be improved.
[0069]
[Brief description of the drawings]
FIG. 1 is a block diagram of an apparatus for enabling inter-frame prediction coding.
FIG. 2 is a view for explaining positions of respective pixels of luminance and chrominance and fields to which the pixels belong;
FIG. 3 is a view for explaining a vertical character space position of each pixel of luminance and chrominance in a field image.
FIG. 4 is a view for explaining the relationship between fields and frames in a frame encoding mode.
FIG. 5 is a diagram for explaining a prediction method in an inter-frame prediction coding mode.
FIG. 6 is a view for explaining a prediction method in an inter-field prediction mode.
FIG. 7 is a diagram illustrating coordinates of a field image.
FIG. 8 is a diagram illustrating a method of calculating a motion vector between corresponding pixels between fields in a conventional method.
FIG. 9 is a diagram illustrating a method of calculating a pixel indicated by a motion vector according to a conventional method.
FIG. 10 is a view for explaining a conventional method for obtaining a color difference motion vector from a luminance motion vector.
FIG. 11 is a diagram illustrating a zero vector between fields having different parities in the related art. FIG. 11 is a diagram illustrating the principle of Direct Mode.
FIG. 12 is a diagram illustrating a problem of the related art when a color difference motion vector is obtained from a luminance motion vector when a reference destination is a Bottom field and a reference source is a Top field.
FIG. 13 is a diagram illustrating a problem of the related art when a color difference motion vector is obtained from a luminance motion vector when a reference destination is a Top field and a reference source is a Bottom field.
FIG. 14 is a diagram illustrating a method for generating a chrominance motion vector from a luminance motion vector according to the present invention.
FIG. 15 is a diagram for explaining an embodiment of a first chrominance component motion vector generation unit according to the present invention.
FIG. 16 is a diagram for explaining an embodiment of a second chrominance component motion vector generation unit according to the present invention.
FIG. 17 is a diagram for explaining an embodiment of a third color difference component motion vector generation unit according to the present invention.
FIG. 18 is a view for explaining an embodiment of the selection means in the present invention.
FIG. 19 is a diagram illustrating an example of derivation of a chrominance motion vector from a luminance motion vector when a reference destination is a Bottom field and a reference source is a Top field when a format F = 0 according to the embodiment.
FIG. 20 is a view for explaining an example of deriving a chrominance motion vector from a luminance motion vector when a reference destination is a Top field and a reference source is a Bottom field in a format F = 0 according to the embodiment.
FIG. 21 is a diagram illustrating a method of calculating an interpolation pixel of a color difference component.
FIG. 22 is a view for explaining a format F = 0 in the embodiment.
FIG. 23 is a view for explaining a format F = 1 in the embodiment.
FIG. 24 is a diagram illustrating an example of derivation of a chrominance motion vector from a luminance motion vector when a reference destination is a Top field and a reference source is a Bottom field in a format F = 1 according to the embodiment.
FIG. 25 is a diagram illustrating an example of deriving a chrominance motion vector from a luminance motion vector when a reference destination is a Top field and a reference source is a Bottom field in a format F = 1 according to the embodiment.
[Explanation of symbols]
31 orthogonal transformation means
32 Quantization means
33 inverse quantization means
34 inverse orthogonal transformation means
35 Decoded image generation means
36 Decoded image storage means
37 Motion vector calculation means
38 Prediction image generation means
39 Prediction error signal generation means
40 Coefficient entropy coding means
41 Motion Vector Entropy Coding Means
42 Multiplexing means
50a-50d Top Field Luminance 1, 3, 5, 7th line
51a-51d Bottom Field Luminance 2, 4, 6, 8th line
52a-52b Top Field color difference first and third lines
53a-53b Bottom Field Color Difference 2nd and 4th Line
64a-64c Top Field
65a-65c Bottom Field
81 Frame # 1 luminance component
82 Frame # 2 luminance component
84a-84c Frame # 1 to # 3
90 Same parity inter-field prediction
91 Prediction between different parity fields
94a-94b Top Field
95a-95b Bottom Field
100a-100b Top Field
101a-101b Bottom Field
110a-110b Top Field
111a-111b Bottom Field
130 Top Field
131 Bottom Field
132 Top Field
133a-133b Luminance component to be encoded
134a-134b Color difference components to be encoded
135a-135b Luminance component of reference field
136a-136b Color difference component preferable as prediction
137a-137b Color difference component of reference field
140 Source Top field Pixel of luminance component
141 Pixel position of reference destination Bottom field luminance component used as predicted value
142 reference source Top field pixel of color difference component
143 Reference destination Bottom field used as predicted value Field position of color difference component
145 Predicted pixel position of preferred color difference component
150 pixels of reference source Bottom field luminance component
151 Pixel position of reference destination field luminance component used as prediction value
152 Pixel of reference source Bottom field color difference component
153 pixel position of reference destination field color difference component used as prediction value
155 Predicted pixel position of preferred color difference component
160 Pixel of reference source Top field luminance component
161 Reference destination Bottom field used as predicted value Pixel position of field luminance component
162 pixel of reference source Top field color difference component
163 Reference Bottom Field Used as Prediction Field Pixel Position of Color Difference Component
170 Pixel of reference source Bottom field luminance component
171 Pixel Position of Top Destination Field Luminance Component Used as Prediction Value
172 Pixel of reference source Bottom field color difference component
173: Pixel position of reference destination field color difference component used as predicted value
180 Position where coordinates are to be obtained
Definition position of 181 pixels
200 Motion vector calculation means
201 Reference field coordinates
202 Reference field coordinates
203 motion vector
210 pixel association means
211 motion vector
212 Source field coordinates
213 Reference field coordinates
220 Color difference component motion vector generation means
221 luminance component motion vector
222 color difference component motion vector
230 Selection means
231 Motion vector of luminance component
232 Color difference component motion vector
233 First color difference component motion vector generation means
234 Second color difference component motion vector generating means
235 Third color difference component motion vector generating means
237 Parity of reference field of motion vector
238 Parity of reference field of motion vector
239 Format information
240 selection means
241 Condition judgment table
242 Motion vector of color difference component
243 selector
244 Candidate for first chrominance component motion vector
245 Second color difference component motion vector candidate
246 Third color difference component motion vector candidate
247 Parity of reference field of motion vector
248 Parity of reference field of motion vector
249 Selection information
250 to 255 integer pixels
256 interpolation pixels
260 first color difference component motion vector generating means
261 luminance component motion vector
262 First color difference component motion vector candidate
263 Color difference phase information
270 Second color difference component motion vector generation means
271 luminance component motion vector
272 Second color difference component motion vector candidate
273 format information
280 Third color difference component motion vector generating means
281 luminance component motion vector
282 Third color difference component motion vector candidate
283 format information
300 pixels of reference source Top field luminance component
301 Pixel position of reference destination Bottom field luminance component used as predicted value
302 Reference source Top field Pixel of color difference component
303 Reference destination Bottom field used as prediction value Pixel position of field color difference component
310 pixel of reference source Bottom field luminance component
311 Pixel position of reference destination Top field luminance component used as prediction value
312 Pixel of reference source Bottom field color difference component
313 Pixel position of reference destination field color difference component used as prediction value

Claims (5)

In a moving picture coding method for performing motion compensation prediction between fields for a moving picture signal composed of a plurality of fields,
The motion vector of the luminance component, the format information indicating the sampling position relationship between the luminance and chrominance pixels in the Top field and the Bottom field, and the color difference parallel to the motion vector of the luminance component from the parity of the reference field and the reference source field of the motion vector A moving picture coding method characterized by generating a motion vector of a component. In a video encoding method for performing motion compensation prediction between fields for a video signal composed of a plurality of fields,
A luminance component motion vector generating means for generating a motion vector of a luminance component between fields,
A plurality of chrominance component motion vector generation means for generating a chrominance component motion vector from format information indicating a sampling position relationship between luminance and chrominance pixels in the Top field and the Bottom field and a luminance component motion vector;
Having a selection means for selecting one of the chrominance component motion vector generating means used for generating the chrominance vector, with the parity of the reference field and the reference source field of the motion vector being input,
A moving image encoding method, wherein a prediction vector of a color difference component is generated by a color difference component motion vector generation unit selected by the selection unit. The color difference component motion vector generation unit according to claim 2, wherein the color difference component motion vector generation unit generates a color difference component motion vector from the luminance component motion vector.
When the reference destination field and the reference source field have the same parity, first color difference component motion vector generation means selected by the selection means,
A second color difference component motion vector generation unit selected by the selection unit when the reference destination field is a Top field and the reference source field is a Bottom field;
A moving image encoding method, comprising: a third chrominance component motion vector generation unit selected by a selection unit when a reference destination field is a Bottom field and a reference source field is a Top field. In a video decoding method for performing motion compensation prediction between fields for a video signal composed of a plurality of fields,
A plurality of chrominance component motion vector generating means for generating a chrominance component motion vector from a luminance component motion vector and format information indicating a sampling position relationship between luminance and chrominance pixels in a Top field and a Bottom field;
Having a selection means for selecting one of the chrominance component motion vector generating means used for generating the chrominance vector, with the parity of the reference field and the reference source field of the motion vector being input,
A moving image decoding method, characterized in that a prediction vector of a chrominance component is generated from motion vector information of luminance information by a chrominance component motion vector generation unit selected by the selection unit. The color difference component motion vector generation unit according to claim 4, wherein the color difference component motion vector generation unit generates a color difference component motion vector from the luminance component motion vector.
When the reference destination field and the reference source field have the same parity, first color difference component motion vector generation means selected by the selection means,
A second color difference component motion vector generation unit selected by the selection unit when the reference destination field is a Top field and the reference source field is a Bottom field;
When the reference field is a Bottom field and the reference source field is a Top field, the method further comprises a third color difference component motion vector generation unit selected by the selection unit.

Images