JP2009111647A - Apparatus for detecting motion vector and method for detecting motion vector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for detecting a motion vector, which can reduce computational complexity of image coding processing while contributing to improvement of image quality and coding efficiency, and which can achieve high-speed processing and low power consumption. <P>SOLUTION: The apparatus for detecting a motion vector comprises an image data memory 101 for storing pixel values of a coding subject picture and a plurality of reference pictures, an initial search start position determination part 102 for selecting positions other than a position indicated by a zero vector on a block as a coding subject as an initial search start position of sequential search, and a motion search part 103 for searching a motion vector by the sequential search. The initial search start position determination part 102 sets the initial search start position of at least one reference picture in relation of identical parity with the coding subject picture to the position indicated by the zero vector to the block as the coding subject. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for detecting a motion vector of an encoding target block included in an encoding target image in an image compression encoding apparatus that compresses and records an image on a storage medium such as an optical disk, a magnetic disk, or a flash memory. Yes, especially H. The present invention relates to an apparatus for detecting a motion vector in an H.264 encoding system encoding apparatus.

  With the development of digital video technology, a technology for compressing data is being used and developed for digital video data in order to process an increasing amount of data. The development has emerged as a compression technique specialized for video data that takes advantage of the characteristics of video data. Further, with the improvement of the processing capability of information processing devices such as computers, complicated computations in compression techniques are possible, and the compression rate of video data is being greatly improved. For example, a compression technique employed in satellite and terrestrial digital high-definition broadcasting is a method called MPEG2, and satellite digital high-definition broadcasting compresses video data to about 1/30 by MPEG2.

  MPEG4 AVC / H.2 standardized as the next video compression technology of MPEG2. H.264 is said to achieve a compression rate approximately twice that of MPEG2. MPEG4 AVC / H. H.264 is also adopted as a moving picture compression method for Blu-ray, which is a standard for optical discs, and AVCHD, which is a standard for recording high-definition video with a video camera, and is expected to be used in a wide range of fields. However, MPEG4 AVC / H. In H.264, many compression techniques are implemented, and a high compression rate is realized by combining them (for example, see Non-Patent Document 1).

  In general, in the encoding of moving images, the amount of information is compressed by reducing redundancy in the time direction and the spatial direction. Therefore, in inter-picture predictive coding for the purpose of reducing temporal redundancy, motion detection and prediction image creation are performed in block units with reference to the front or rear picture, and the obtained prediction image and code are obtained. Encoding is performed on the difference value from the current picture. Here, a picture is a term representing one screen.

  A picture that performs intra-frame prediction coding without creating a prediction picture is called an I picture. A picture that performs inter-picture prediction coding with reference to only one picture is called a P picture. A picture that can be subjected to inter-picture prediction coding with reference to two pictures at the same time is called a B picture. A B picture can refer to two pictures as an arbitrary combination of display times from the front or rear.

  Motion compensation inter-picture prediction coding is used for coding a P picture or a B picture. The motion compensation inter-picture prediction encoding is an encoding method in which motion compensation is applied to inter-picture prediction encoding. Motion compensation does not simply predict from the pixel value of the reference picture, but detects the amount of motion (hereinafter referred to as a motion vector) of each part in the picture and performs prediction in consideration of the amount of motion. This is a method that improves and reduces the amount of data. For example, the amount of data is reduced by detecting the motion vector of the encoding target picture and encoding the prediction residual between the prediction value shifted by the motion vector and the encoding target picture. In the case of this method, since motion vector information is required at the time of decoding, the motion vector is also encoded and recorded or transmitted.

  The motion vector is detected in units of blocks. Specifically, the block on the encoding target picture side is fixed, the reference picture side block is moved within the search range, and is most similar to the encoding target block. A motion vector is detected by finding the position of the reference block. This process of searching for a motion vector is called motion vector detection.

  In motion vector detection, the target block is compared with a block at an arbitrary position in the reference picture, and the position of the most similar block is detected. In general, a comparison error between the target block and the reference block is used for determining whether or not they are similar. In particular, a sum of absolute difference (SAD) is often used. Note that, when a reference block is searched for in the entire reference picture, the amount of computation becomes enormous. Therefore, a search range in the reference picture is narrowed down, and the narrowed range is called a search range.

  Motion vector detection is known as the processing with the largest amount of calculation in the moving image encoding processing. Conventionally, many search methods for reducing the amount of calculation of motion vector detection have been studied. For example, there is a sequential search (see, for example, Patent Document 1). In the sequential search, the SAD is obtained for the reference block serving as the search start position and its surrounding reference blocks, the position having the smallest SAD is set as the search start position of the next step, and the SAD is obtained again for the reference block and its surrounding reference blocks. This process is repeated until the SAD at the search start position of the current step is minimized. For this reason, if there is a position that becomes the minimum point of SAD between the initial search start position and the position that should be detected as a motion vector, the search is aborted at the position that becomes the minimum point of SAD and is detected as a motion vector. There is a problem that it is not possible to reach the right position. In order to solve this problem, it is necessary to set the initial search start position as close as possible to the position to be detected as a motion vector.

As an initial search start position, a position indicated by a predicted motion vector (hereinafter referred to as PMV), a position obtained from a motion vector of a block encoded in the same positional relationship in the past, a zero vector (the same position as an encoding target block) In many cases, the position indicated by the relationship) is used. By setting the position indicated by the PMV as the initial search start position, it is possible to increase the accuracy of motion vector detection in a scene that moves uniformly over the entire screen (or a partial area of the screen). In addition, by using the position obtained from the motion vector of the block having the same positional relationship encoded in the past as the initial search start position, it is possible to improve the detection accuracy of the motion vector in a scene moving at a constant speed. . In addition, by setting the position pointed to by the 0 vector as the initial search start position, it is possible to improve the detection accuracy of the motion vector in the still region, which is effective in tracking subtitles and moving objects. Further, a technique is disclosed in which both the position indicated by the PMV and the position indicated by the 0 vector are set as the initial search start position (see, for example, Patent Document 2).
ITU-T Recommendation H. H.264 JP 2005-278156 A JP 2007-97028 A

  However, in the method of Patent Document 2 described above, a search using both the position indicated by the PMV and the position indicated by the 0 vector as the initial search start position is performed for each reference picture. There is a problem that the amount of calculation becomes large.

  The present invention has been made to solve such problems, and contributes to improvement in image quality and coding efficiency, while reducing the amount of calculation of image coding processing, and achieving high speed and low power consumption. It is an object of the present invention to provide a motion vector detection device and a motion vector detection method capable of performing the above.

  In order to achieve the above object, a motion vector detection method according to the present invention is a motion vector detection method for performing a motion vector search by a sequential search using a plurality of reference pictures, and the initial search start position of the sequential search. And an initial search start position determining step that can select a position other than the position indicated by the 0 vector for the block to be encoded, and a motion search step for performing a motion vector search by the sequential search, and the initial search start position In the determination step, the initial search start position of at least one reference picture having the same parity as that of the encoding target picture is set to a position indicated by the 0 vector with respect to the encoding target block.

  As described above, the initial search start position of at least one reference picture having the same parity as that of the encoding target picture is set to the position indicated by the 0 vector with respect to the encoding target block. Encoding efficiency when the region is included can be increased. In addition, the circuit scale and the amount of calculation can be reduced as compared with the method of increasing the coding efficiency by setting a plurality of initial search start positions for each reference picture as in Patent Document 2 and performing a search. . Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  Preferably, in the initial search start position determination step, among the reference pictures having the same parity relationship, an initial search start of a reference picture that is farthest in time in the display order with respect to the encoding target picture Let the position be a 0 vector.

  In this way, the initial search start position of the reference picture that is the farthest in time in the display order with respect to the encoding target picture among at least one reference picture having the same parity relationship as the encoding target picture is determined. By setting the position indicated by the 0 vector to the block to be encoded, it is possible to increase the encoding efficiency of the still area without decreasing the encoding efficiency of the area where the input image is moving. Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  Preferably, in the initial search start position determination step, the initial search start position of the reference picture included in the prediction direction with the larger number of reference pictures among the reference pictures having the same parity relationship is set as a zero vector. To do.

  As described above, the initial search start position of the reference picture included in the prediction direction in which the number of reference pictures is larger among at least one reference picture having the same parity as that of the encoding target picture is the encoding target. By setting the position indicated by the 0 vector with respect to the block, it is possible to increase the encoding efficiency of the still area without decreasing the encoding efficiency of the area where the input image is moving. Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  More preferably, in the initial search start position determining step, it is determined whether or not the initial search start position of the reference picture is set to 0 vector according to the motion vector information obtained from the motion search step.

  In this way, by determining whether the initial search start position of the reference picture is set to 0 vector according to the motion vector information obtained from the motion search step, only when the input image includes a still region By setting the initial search start position of the reference picture to the position indicated by the 0 vector with respect to the block to be encoded, the encoding efficiency of the still area without reducing the encoding efficiency of the moving area of the input image Can be increased. Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  The present invention can be realized not only as a motion vector detection apparatus including such means, but also as a motion vector detection method using steps included in the motion vector detection apparatus as a step, or a motion vector detection apparatus. It can also be realized as an integrated circuit provided with means included in the above, or as a program that causes a computer to function as means included in the motion vector detection device. Such a program can be distributed via a recording medium such as a CD-ROM (Compact Disc-Read Only Memory) or a communication network such as the Internet.

  According to the present invention, it is possible to reduce the calculation amount and power consumption of the motion vector detection process. Furthermore, it is possible to improve the coding efficiency, increase the speed, and reduce the power consumption.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an image coding apparatus according to an embodiment of the present invention. In the image coding apparatus according to the present embodiment, an input image is input, It is output as a H.264 encoded stream.

  H. In H.264 encoding, one picture is divided into one or a plurality of slices, and the slice is used as a processing unit. H. of this embodiment. In the H.264 encoding, it is assumed that one picture is one slice.

  The image encoding device 100 includes an image data memory 101, an encoding unit 104, and a motion vector detection unit 105.

  The image data memory 101 corresponds to the image storage means described in the claims, and stores the image data of the encoding target picture and the reference picture. The image data of the encoding target picture is image data of a screen to be encoded. The image data of the reference picture is image data of a screen that is referred to when detecting a motion vector, and is image data of a locally decoded screen. For example, the encoding target picture and the reference picture are both screens composed of 1920 pixels × 1088 pixels. The image data is a pixel value of a pixel included in the screen.

  The encoding unit 104 encodes a moving image in units of blocks, and outputs an encoded stream. The encoding unit 104 receives the input image, the image data of the local decoding screen, and the motion vector detected by the motion vector detection unit 105. Receiving these, the encoding unit 104 generates a predicted image in which motion compensation is performed in block units from the image data of the local decoding screen and the motion vector detected by the motion vector detecting unit 105, and the predicted image, the input image, The difference image data and motion vector are encoded, and an encoded stream is output.

  The motion vector detection unit 105 is a part that detects a motion vector of an encoding target block. The motion vector detection unit 105 includes an initial search start position determination unit 102 and a motion search unit 103.

  The initial search start position determination unit 102 corresponds to the initial search start position determination unit described in the claims, and determines the initial search start position of the motion search unit 103.

  The motion search unit 103 corresponds to the motion search means described in the claims, and encodes from the plurality of reference pictures included in the image data memory 101 with the position determined by the initial search start position determination unit 102 as the initial search start position. The position of the image block closest to the target block is searched, and the motion vector of the encoding target block is detected. Note that the encoding target block is a unit of an image to be subjected to motion compensation, and is a part of an image included in the encoding target picture. The encoding target block is, for example, 16 pixels × 16 pixels, or 16 pixels × 8 pixels, or 8 pixels × 16 pixels, or 8 pixels × 8 pixels, or 8 pixels × 4 pixels, or 4 pixels × 8 pixels, or It is composed of 4 pixels × 4 pixels.

  FIG. 2 is a block diagram showing a configuration of encoding section 104 included in image encoding apparatus 100 according to the embodiment of the present invention. The encoding unit 104 outputs a stream of encoded image data using the input image, the local decoded image, and the motion vector detected by the motion vector detection unit 105.

  The encoding unit 104 includes an in-plane prediction unit 201, a motion compensation unit 202, a subtractor 203, an orthogonal transform unit 204, a quantization unit 205, an inverse quantization unit 206, an inverse orthogonal transform unit 207, an adder 208, a switch 209, And an entropy encoding unit 210.

  Since the image data memory 101 and the motion vector detection unit 105 are parts common to FIGS. 1 and 2, the same reference numerals are given, and description thereof is omitted here.

  The input image is image data before compression. The input image is input to the in-plane prediction unit 201, the image data memory 101, and the subtracter 203.

  The motion compensation unit 202 generates a predicted image using the motion vector and the local decoded image. The motion compensation unit 202 acquires the motion vector detected by the motion vector detection unit 105, extracts an optimal image region for generating a predicted image from the local decoded image stored in the image data memory 101, and extracts the extracted image region A predicted image is generated by applying a motion vector to.

  The in-plane prediction unit 201 generates a predicted image using pixel values within the same screen. The in-plane prediction unit 201 generates a predicted image by performing in-plane prediction using the pixel values of the input image and the local decoded image.

  The switch 209 switches the data input source. The switch 209 switches the data input to the subtracter 203 and the adder 208 to either intra prediction or inter prediction.

  The subtracter 203 calculates the difference between the two input images. The subtractor 203 calculates the difference between the pixel value of the pixel included in the input image and the pixel value of the pixel included in the predicted image, and outputs the difference to the orthogonal transform unit 204.

  The orthogonal transform unit 204 transforms image data into frequency coefficients. The orthogonal transform unit 204 transforms the difference value input from the subtractor 203 into a frequency coefficient and outputs the frequency coefficient to the quantization unit 205.

  The quantization unit 205 quantizes the frequency coefficient. The quantization unit 205 quantizes the frequency coefficient input from the orthogonal transform unit 204 and outputs the quantized value to the entropy encoding unit 210.

  The inverse quantization unit 206 performs inverse quantization. The inverse quantization unit 206 restores the frequency coefficient by inverse quantization of the quantized value input from the quantization unit 205, and outputs the frequency coefficient to the inverse orthogonal transform unit 207.

  The inverse orthogonal transform unit 207 converts the frequency coefficient into a pixel value. The inverse orthogonal transform unit 207 converts the frequency coefficient input from the inverse quantization unit 206 into a pixel difference value by performing inverse frequency transform, and outputs the pixel difference value to the adder 208.

  The adder 208 generates image data by adding the two input image data. The adder 208 adds the predicted image output from either the in-plane prediction unit 201 or the motion compensation unit 202 and the pixel difference value according to the switching of the switch 209, and generates a local decoded image.

  The entropy encoding unit 210 performs entropy encoding processing. The entropy encoding unit 210 performs entropy encoding on the quantized value, the motion vector, and the like, and outputs a stream obtained thereby.

  Next, processing executed by the motion vector detection unit 105 of the image encoding device 100 configured as described above will be described with reference to FIGS. 3, 4, and 5.

  First, the initial search start position determination unit 102 determines the initial search start position of the motion search unit 103. Details of the initial search start position determination unit 102 will be described later. Next, the pixel data necessary for the search among the pixel data of the encoding target block of the encoding target picture and the pixel data of the reference picture is read from the image data memory 101. Next, the motion search unit 103 performs a sequential search within the search range of the reference picture, and detects a motion vector by finding the position of the reference block most similar to the encoding target block.

  FIG. 3 is a diagram illustrating an example of a reference relationship when the encoding target picture is encoded as a P picture. Picture I0 represents a picture to be coded as I picture, picture P1, picture P6 and picture P7 represent pictures to be coded as P pictures, picture B2, picture B3, picture B4 and picture B5 represent pictures to be coded as B pictures. And displayed in the order of display time. The arrow indicates that when the picture corresponding to the root of the arrow is the encoding target picture, the picture corresponding to the tip of the arrow is used as a reference picture.

  As illustrated in FIG. 3, when the initial search start position determination unit 102 encodes the current picture to be encoded as a P picture (the picture P6 and the picture P7 in FIG. 3 correspond), the top field picture P6 is a reference picture. As picture I0 and picture P1. Then, the initial search start position of the reference picture I0 having the same parity is set as the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture P1, the position obtained from the motion vector of the block having the same positional relationship encoded in the past may be selected, or determined by other methods. You may choose a location. For the picture P7 as the bottom field, the picture P1 and the picture P6 are selected as reference pictures. Then, the initial search start position of the reference picture P1 having the same parity relationship is set as the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture P6, or the position obtained from the motion vector of the block having the same positional relationship encoded in the past may be selected, or determined by other methods. You may choose a location.

  Note that having the same parity relationship means having the same field relationship. For example, if the encoding target picture is a top field, the reference picture having the same parity also belongs to the top field.

  FIG. 4 is a diagram showing an example of a reference relationship when the encoding target picture belongs to a frame positioned temporally next to the P picture and is encoded as a B picture. The meanings of symbols and arrows in the figure are the same as in FIG.

  As shown in FIG. 4, the initial search start position determination unit 102 belongs to a frame temporally positioned next to a P picture and is encoded as a B picture (picture B2, FIG. 4). For the picture B2 that is the top field, the picture I0, the picture P1, or the picture P6 is selected as the reference picture. Then, among the reference pictures having the same parity, the initial search start position of the reference picture P6 that is the farthest in the display order with respect to the encoding target picture is the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture I0 and the reference picture P1, the position obtained from the motion vector of the block having the same positional relationship encoded in the past may be selected, The position determined by the method may be selected. For the picture B3 as the bottom field, the picture P1, the picture B2, or the picture P7 is selected as a reference picture. Then, among the reference pictures having the same parity, the initial search start position of the reference picture P7 that is the farthest in the display order with respect to the encoding target picture is the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture P1 and the reference picture B2, or the position obtained from the motion vectors of the blocks having the same positional relationship encoded in the past may be selected. The position determined by the method may be selected.

  FIG. 5 is a diagram showing an example of a reference relationship when the encoding target picture belongs to a frame temporally located immediately before the P picture and is encoded as a B picture. The meanings of symbols and arrows in the figure are the same as in FIG.

  As shown in FIG. 5, the initial search start position determination unit 102 belongs to a frame temporally located immediately before a P picture and is encoded as a B picture (pictures B4 and B4 in FIG. 6). For picture B4, which is the top field, picture I0, picture P6, and picture P7 are selected as reference pictures. Then, among the reference pictures having the same parity, the initial search start position of the reference picture I0 that is the farthest in the display order with respect to the encoding target picture is the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture P6 and the reference picture P7, or the position obtained from the motion vectors of the blocks having the same positional relationship encoded in the past may be selected. The position determined by the method may be selected. For the picture B5 as the bottom field, the picture B4, the picture P1, or the picture P7 is selected as a reference picture. Then, among the reference pictures having the same parity, the initial search start position of the reference picture P1 that is the farthest in the display order with respect to the encoding target picture is the position indicated by the 0 vector. The position indicated by the PMV may be selected as the initial search start position of the reference picture B4 and the reference picture P7, the position obtained from the motion vector of the block having the same positional relationship encoded in the past may be selected, The position determined by the method may be selected.

  As described above, in the present embodiment, out of a plurality of reference pictures, out of at least one reference picture having the same parity relationship as that of the encoding target picture, the most temporal in the display order with respect to the encoding target picture. The initial search start position of the reference picture at a far position is set as the position indicated by the 0 vector for the block to be encoded. This is because the reference picture located at the farthest time distance in the display order with respect to the encoding target picture is less likely to be selected as the reference picture because there is little correlation with the encoding target picture in the moving part. It is. As a result, the coding efficiency of the still area can be increased without reducing the coding efficiency of the area where the input image is moving. Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this.

  For example, in the present embodiment, when the encoding target picture is encoded as a B picture, among the reference pictures having the same parity relationship, the temporal distance is the longest in the display order with respect to the encoding target picture. Although the initial search start position of the reference picture at the position is the position indicated by the zero vector, the initial search start position of the reference picture included in the prediction direction with the larger number of reference pictures may be the zero vector. In that case, when the encoding target picture is the picture B2, the initial search start position determination unit 102 sets the initial search start position of the reference picture I0 as the position indicated by the 0 vector. When the encoding target picture is B3, the initial search start position of the reference picture P1 is set to the position indicated by the 0 vector. When the encoding target picture is the picture B4, the initial search start position of the reference picture P6 is set to the position indicated by the 0 vector. When the encoding target picture is B5, the initial search start position of the reference picture P1 is set to the position indicated by the 0 vector.

  In this embodiment, the initial search start position of at least one reference picture is always determined to be the position indicated by the 0 vector, but is adaptively set to 0 using the motion vector information output from the encoding unit 104. It may be determined whether or not the position indicated by the vector is the initial search start position. In that case, for example, among the encoded motion vectors, the number of vectors close to the 0 vector is totaled, and only when the number is equal to or greater than a certain value, the initial search start position of at least one reference picture is set as the position indicated by the 0 vector. Also good.

  In this embodiment, the initial search start position of one reference picture is determined to be the position indicated by the 0 vector. However, two reference pictures having the position indicated by the 0 vector as the initial search start position may be used. However, the number may be set to be larger than that.

  Further, although a case has been described with the present embodiment where a maximum of three reference pictures exist, however, a maximum of four reference pictures may exist, or a maximum of two reference pictures may exist.

  In this embodiment, H.264 is used as the encoding method. Although the case of using H.264 has been described, for example, MPEG1, MPEG2, or VC1 may be used as an encoding method.

  As described above, in the motion vector detection device of the present invention, the initial search start position determination unit 102 determines the initial search start position and sets the initial search start position of the sequential search in the motion search unit 103. For this reason, among the plurality of reference pictures, the initial search start position of at least one reference picture having the same parity relationship as the encoding target picture is set as the position indicated by the 0 vector for the block to be encoded. As a result, the coding efficiency of the still area can be increased without lowering the coding efficiency of the moving area of the input image. Therefore, it is possible to reduce the calculation amount of the image encoding process, increase the speed, and reduce the power consumption while contributing to the improvement of the image quality and the encoding efficiency.

  Further, for example, each functional block in the block diagrams shown in FIGS. 1 and 2 is typically realized as an LSI which is an integrated circuit. This LSI may be made into one chip or a plurality of chips (for example, functional blocks other than the memory may be made into one chip). The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

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

  Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied as a possibility.

  Moreover, it is good also as another structure instead of making into one chip | tip only the unit which stores data among each functional block.

  According to the motion vector detection device of the present invention, the H.264 can be realized with a smaller circuit scale and power consumption. H.264 video encoding can be realized, and can be applied to personal computers, HDD recorders, DVD recorders, etc., as well as mobile phones with cameras.

It is a block diagram which shows the structure of the image coding apparatus which concerns on embodiment of this invention. It is a block diagram which shows the detailed structure of the image coding part of the image coding apparatus which concerns on embodiment of this invention. It is a figure which shows the 1st example of the reference relationship of the encoding object picture which concerns on embodiment. It is a figure which shows the 2nd example of the reference relationship of the encoding object picture which concerns on embodiment. It is a figure which shows the 3rd example of the reference relationship of the encoding object picture which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image coding apparatus 101 Image data memory 102 Initial search start position determination part 103 Motion search part 104 Encoding part 105 Motion vector detection part 201 In-plane prediction part 202 Motion compensation part 203 Subtractor 204 Orthogonal transformation part 205 Quantization part 206 Inverse quantization unit 207 Inverse orthogonal transform unit 208 Adder 209 Switch 210 Entropy encoding unit

Claims (9)

A motion vector detection method for performing motion vector search by sequential search using a plurality of reference pictures,
An initial search start position determining step capable of selecting other than the position indicated by the 0 vector for the block to be encoded as the initial search start position of the sequential search;
A motion search step for performing a motion vector search by the sequential search,
In the initial search start position determining step, the initial search start position of at least one reference picture having the same parity as that of the encoding target picture is set to a position indicated by the 0 vector with respect to the encoding target block. A feature motion vector detection method. The motion vector detection method according to claim 1, wherein the encoding target picture is encoded as a P picture. The motion vector detection method according to claim 1, wherein the encoding target picture is encoded as a B picture. In the initial search start position determination step, among the reference pictures having the same parity relationship, the initial search start position of the reference picture that is farthest in time in the display order with respect to the encoding target picture is set to 0. The motion vector detection method according to claim 3, wherein the vector is a vector. In the initial search start position determination step, an initial search start position of a reference picture included in a prediction direction with a larger number of reference pictures among the reference pictures having the same parity relationship is set as a zero vector. The motion vector detection method according to claim 3. 2. The initial search start position determination step determines whether or not to set the initial search start position of the reference picture as a zero vector according to motion vector information obtained from the motion search step. The motion vector detection method according to claim 5. A motion vector detection apparatus that performs motion vector search by sequential search using a plurality of reference pictures,
Image storage means for storing pixel values of the encoding target picture and the plurality of reference pictures;
Initial search start position determining means that can select other than the position indicated by the 0 vector for the block to be encoded as the initial search start position of the sequential search;
Motion search means for performing a motion vector search by the sequential search,
The initial search start position determining means sets an initial search start position of at least one reference picture having the same parity relationship as that of the encoding target picture as a position indicated by a zero vector for a block to be encoded. A motion vector detection device characterized by the above. An integrated circuit that performs motion vector search by sequential search using a plurality of reference pictures,
Image storage means for storing pixel values of the encoding target picture and the plurality of reference pictures;
Initial search start position determining means that can select other than the position indicated by the 0 vector for the block to be encoded as the initial search start position of the sequential search;
Motion search means for performing a motion vector search by the sequential search,
The initial search start position determining means sets an initial search start position of at least one reference picture having the same parity relationship as the encoding target picture as a position indicated by a zero vector for a block to be encoded. An integrated circuit characterized by. A motion vector detection program for causing a computer to perform motion vector search by sequential search using a plurality of reference pictures,
An initial search start position determining step capable of selecting other than the position indicated by the 0 vector for the block to be encoded as the initial search start position of the sequential search;
A motion search step for performing a motion vector search by the sequential search,
In the initial search start position determining step, the initial search start position of at least one reference picture having the same parity as that of the encoding target picture is set to a position indicated by a 0 vector with respect to the encoding target block. Feature motion vector detection program.

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