JP6259272B2 - Video encoding apparatus and video encoding program - Google Patents

Description

  The present invention relates to a video encoding device and a video encoding program that perform video encoding using motion prediction.

  MPEG-2, MPEG-4, and MPEG-4 / AVC are widely used as video encoding technologies, and recently, High Efficiency Video Coding (HEVC), which is a next-generation video encoding standard, is being standardized. . In the video coding standard, intra-frame coding that performs coding using information closed in one picture and inter-screen coding that performs coding using a plurality of temporally continuous pictures are used. Yes. In inter-frame coding, motion prediction processing is performed to reduce the difference value between the screens, and the information amount is reduced by encoding the difference value and the motion vector information. However, in order to capture the correct motion of the video and reduce the difference value to be encoded, a large amount of computation is required for motion prediction processing.

  MPEG-4 / AVC and HEVC employ a method of encoding the difference between the prediction vector calculated from the motion vectors of the blocks around the target block and the motion vector of the target block. Coding efficiency can be improved by efficiently selecting a position having a small prediction residual. For this reason, a general coder often uses a method of searching around a point indicated by a prediction vector as a search center. As for HEVC, the more efficient one can be selected from the two prediction vectors, so that the search is performed around the two prediction vectors as the search centers. There is a possibility that the search processing is increased as compared with the case of H.264 / AVC.

  As a prior art for performing motion vector detection using a method for narrowing down search center candidates, there is a method of calculating a motion vector evaluation value of each search center candidate and using a search center candidate that is equal to or less than a threshold (for example, a patent Reference 1).

Japanese Patent No. 5286573

  However, since the video encoding device described in Patent Document 1 calculates the difference between the block pixel at the position indicated by the prediction vector and the pixel of the target block, the pixel value needs to be read, which increases the amount of processing. is there.

  The present invention has been made in view of such circumstances, and a video encoding device capable of reducing the processing amount without reducing the encoding efficiency without reading all reference images of the search center. An object of the present invention is to provide a video encoding program.

The present invention is a video encoding apparatus that uses temporal correlation of a picture of an input video signal, performs motion prediction for each target block of the target picture, and encodes the difference thereof. A reference image of a picture and a decoded video signal of a motion prediction destination is reduced, and a first motion prediction process is performed using a coding block of a picture of the reduced input video signal and a search area of the reference image of the reduced decoded video signal. A motion vector determining means for determining a motion vector by executing, a prediction vector calculating means for calculating a prediction vector from the peripheral blocks of the target coding block, and a vector indicating a point serving as a search center point of the second motion prediction process A search center determining unit that selects one or more of the motion vector and the prediction vector determined by the first motion prediction process When, a motion prediction unit which performs the second motion prediction processing using the determined the search center point, the search center determination means compares the cost value and the threshold value of the motion vector, the motion vector If it is determined that the larger cost value, excluded from the candidates of vectors indicating point which the motion vector and the search center point, the determined motion vector and the previous SL prediction vector and the smaller the cost value If the total number is larger than the number of desired as the candidate with the cost value of the position closest to the motion vector in each prediction vector calculated by the prediction vector calculation unit among all the motion vectors evaluated in the motion vector determining means indicated is calculated, the calculated the motion vector corresponding to the cost value, the total number is desired number in order from the cost value smaller again And in the point indicated by the prediction vector and the point indicated by the motion vector obtained by choosing, characterized in that the search center point used for the second motion prediction processing.

The present invention is a video encoding apparatus that uses temporal correlation of a picture of an input video signal, performs motion prediction for each target block of the target picture, and encodes the difference thereof. A reference image of a picture and a decoded video signal of a motion prediction destination is reduced, and a first motion prediction process is performed using a coding block of a picture of the reduced input video signal and a search area of the reference image of the reduced decoded video signal. A motion vector determining means for determining a motion vector by executing, a prediction vector calculating means for calculating a prediction vector from the peripheral blocks of the target coding block, and a vector indicating a point serving as a search center point of the second motion prediction process A search center determining unit that selects one or more of the motion vector and the prediction vector determined by the first motion prediction process When, a motion prediction unit which performs the second motion prediction processing using the determined the search center point, the search center determination means compares the cost value and the threshold value of the motion vector, the motion vector If it is determined that the larger cost value, excluded from the candidates of vectors indicating point which the motion vector and the search center point, the determined motion vector and the previous SL prediction vector and the smaller the cost value If the total number is larger than the number of desired as the candidate with, it calculates the distance between each prediction vector calculated by the motion vector and the predicted vector calculating means determined by the motion vector determining means, corresponding to the calculated the distance the motion vectors, the total number is the predicted point indicated by the motion vectors obtained by selecting until a desired number in order of the distance is less Characterized by a search center point using a point indicated by vector in the second motion prediction processing.

The present invention is a video encoding apparatus that uses temporal correlation of a picture of an input video signal, performs motion prediction for each target block of the target picture, and encodes the difference thereof. A reference image of a picture and a decoded video signal of a motion prediction destination is reduced, and a first motion prediction process is performed using a coding block of a picture of the reduced input video signal and a search area of the reference image of the reduced decoded video signal. A motion vector determining means for determining a motion vector by executing, a prediction vector calculating means for calculating a prediction vector from the peripheral blocks of the target coding block, and a vector indicating a point serving as a search center point of the second motion prediction process A search center determining unit that selects one or more of the motion vector and the prediction vector determined by the first motion prediction process When, a motion prediction unit which performs the second motion prediction processing using the determined the search center point, the search center determination means, before Ki予 measuring each prediction vector calculated by the vector calculating unit position indicated A difference between the minimum cost value and the cost value of the motion vector is calculated and compared with a threshold value. When it is determined that the threshold value is larger, the vector indicating a point that becomes the search center point of the motion vector excluded from the candidates, when the total number of the determined motion vector and the previous SL predicted vector and the smaller of the threshold is larger than the number of desired as the candidate, among the motion vectors determined by the motion vector determining means calculating a closest cost value of the motion vector position indicated in each prediction vector calculated by the prediction vector calculation unit, corresponding to the calculated the cost value the motion vector The uses and that the total number in the order of the cost value small differences indicated by the prediction vector and the point indicated by the motion vectors obtained by selecting until a desired number of the second motion prediction process The search center point is used.

The present invention is a video encoding apparatus that uses temporal correlation of a picture of an input video signal, performs motion prediction for each target block of the target picture, and encodes the difference thereof. A reference image of a picture and a decoded video signal of a motion prediction destination is reduced, and a first motion prediction process is performed using a coding block of a picture of the reduced input video signal and a search area of the reference image of the reduced decoded video signal. A motion vector determining means for determining a motion vector by executing, a prediction vector calculating means for calculating a prediction vector from the peripheral blocks of the target coding block, and a vector indicating a point serving as a search center point of the second motion prediction process A search center determining unit that selects one or more of the motion vector and the prediction vector determined by the first motion prediction process When, a motion prediction unit determined by using the search center point performs the second motion prediction processing, and a minimum value before Ki予 measuring cost values of each predicted vector is pointing position calculated by the vector calculating means The difference between the cost value of the motion vector is calculated and compared with a threshold value, and when the threshold value is determined to be larger, the motion vector is excluded from vector candidates indicating points serving as search center points, and If the total number of the determined motion vector and the previous SL predicted vector the smaller threshold is larger than the number of desired as the candidate, calculated by the motion vector and the predicted vector calculating means determined by the motion vector determining means calculates the distance between each prediction vector, the motion vector corresponding to the calculated the distance, the total number in order of the distance is smaller becomes the desired number or Characterized by a search center point using a point indicated by the prediction vector and the point indicated by the motion vectors obtained by selecting the second motion prediction processing.

  The present invention is a video encoding program for causing a computer to function as the video encoding device.

  According to the present invention, in a video encoding method having a motion prediction unit in which a plurality of motion search center candidates exist, a search center candidate can be obtained from motion vector information and a previous motion search result without reading pixel values. By determining the above, it is possible to reduce the amount of processing without lowering the coding efficiency.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a block diagram which shows the structure of the inter prediction process part 102 shown in FIG. It is a figure which shows the position of the prediction vector in HEVC encoding specification. 3 is a flowchart showing a processing operation of a search center determining unit 204 shown in FIG. 3 is a flowchart showing a processing operation of a search center determining unit 204 shown in FIG. 3 is a flowchart showing a processing operation of a search center determining unit 204 shown in FIG. 3 is a flowchart showing a processing operation of a search center determining unit 204 shown in FIG.

<First Embodiment>
Hereinafter, a video encoding apparatus according to a first embodiment of the present invention will be described with reference to the drawings. The “encoded block” used below is MPEG-2 or H.264. The H.264 / AVC standard indicates a macro block, and HEVC indicates a coding unit (CU) or a prediction unit (PU). FIG. 1 is a block diagram showing the configuration of the embodiment. In the video encoding apparatus 100, the inter prediction process 102 is particularly different from the conventional technology, and the other part is H.264. This is the same as the conventional general configuration used as a video encoding device such as H.264 / AVC or HEVC.

  The video encoding device 100 receives a video signal (original image) to be encoded, divides a picture of the input video signal into blocks, encodes each block, and outputs the bit stream as an encoded stream. For this encoding, the prediction residual signal generation unit 103 obtains a difference between the input video signal and the prediction signal output from the intra prediction processing unit 101 or the inter prediction processing unit 102, and outputs it as a prediction residual signal. To do. The transform / quantization processing unit 104 performs orthogonal transform such as discrete cosine transform on the prediction residual signal, quantizes the transform coefficient, and outputs the quantized transform coefficient. The entropy encoding processing unit 105 performs entropy encoding on the quantized transform coefficient and outputs it as an encoded stream.

  On the other hand, the quantized transform coefficient is also input to the inverse quantization / inverse transform processing unit 106, where inverse quantization and inverse orthogonal transform are performed, and a prediction residual decoded signal is output. The decoded signal generation unit 107 adds the prediction residual decoded signal and the prediction signal output from the intra prediction processing unit 101 or the inter prediction processing unit 102, and generates a decoded signal of the encoding target block. This decoded signal is input to the loop filter processing unit 108 for use as a reference image by the inter prediction processing unit 102. The loop filter processing unit 108 performs filtering processing to reduce coding distortion, and inputs the image after the filtering processing to the inter prediction processing unit 102 as a reference image.

  Next, the configuration of the inter prediction processing unit 102 illustrated in FIG. 1 will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of the inter prediction processing unit 102 shown in FIG. The input video signal (original image) and the decoded signal are input to the reduced image generation unit 201. The reduced image generation unit 201 performs a reduction process on the input image and the reference image. The reduced image generation unit 201 outputs the reduced input image and reference image to the pre-search processing unit 202. The pre-search processing unit 202 performs a motion search process on the reduced image. The pre-search processing unit 202 outputs the motion vector resulting from the search and other mode information to the search center determination unit 204, respectively.

  The prediction vector generation unit 203 determines the H.264 from the motion vector information around the target block. A prediction vector defined by H.264 / AVC or HEVC is calculated and output to the search center determination unit 204. The search center determination unit 204 determines a search center by a method described later using the motion vector information of the pre-search result and the prediction vector information output from the prediction vector generation unit 203, and outputs the search center to the motion search processing unit 205. The motion search processing unit 205 performs a motion search process using the motion vector designated by the search center determining unit 204 as a search center. For the search for decimal pixels or less, a motion search process is performed based on the image output from the decimal image generation unit 206. The finally determined motion vector information and the prediction difference image are output to the prediction residual signal generation unit 103.

  In the present embodiment, the search center determination unit 204 shown in FIG. 2 selects the optimum search center from a plurality of search center candidates, thereby reducing the processing amount required for the motion search process without reducing the encoding efficiency. is there.

  The following will be described as an embodiment based on the HEVC standard. In HEVC, two prediction vectors are generated by the prediction vector generation unit 203, and it is possible to perform encoding by selecting the one with higher encoding efficiency. FIG. 3 is a diagram illustrating the position of a prediction vector in the HEVC standard. First, an already-encoded block including the lower left (A0) pixel of the target block 301 is referred to. If the encoding mode has a motion vector, the motion vector is set as a prediction vector (hereinafter referred to as MVP1).

  When the encoded block including the A0 pixel is in the encoding mode having no motion vector, the encoded block including the A1 pixel is referred to. Is a prediction vector MVP1. The same processing is performed for the upper pixel of the target block 301, and B1 and B2 are referred to in order from the encoded block including the pixel B0, and the motion vector is predicted when the encoding mode has a motion vector. Let it be a vector (hereinafter referred to as MVP2). As described above, the prediction vector generation unit 203 generates one prediction vector MVP1 from A0 and A1, generates one prediction vector MVP2 from B0, B1, and B2, and outputs it to the search center determination unit 204. In the prediction vector determination in this embodiment, it is also possible to use a motion vector of a peripheral block in the middle of encoding as a prediction vector. In the present embodiment, an arbitrary motion vector can be added to the prediction vector in addition to the prediction vector and output to the search center determination unit 204.

  The search center determination unit 204 selects two vectors from the three motion vectors (hereinafter referred to as MVpre) searched by the pre-search processing unit 202 and the prediction vectors MVP1 and MVP2 generated by the prediction vector generation unit 203. Will be described. The cost value used in the following description is the sum of absolute differences (SAD) between the original image and the reference image indicated by the motion vector, or the sum of absolute differences (SATD) of values obtained by performing two-dimensional Hadamard transform on the difference values. And a value represented by the sum of motion vector cost values obtained by simply estimating the amount of code generated when the motion vector is encoded.

  FIG. 4 is a flowchart showing a processing operation for selecting an optimum search center from a plurality of search center candidates. First, the search center determining unit 204 calculates the cost value Cost_MVpre of the motion vector determined by the pre-search processing unit 202, and determines whether or not the value is larger than the threshold value TH (step S1). As a result of this determination, if the value is larger than the threshold value TH, the search center determining unit 204 determines that the motion vector obtained by the pre-search process is inaccurate and excludes it from the search center candidates, that is, MVP1 and MVP2 are search centers. (Step S2). The cost value shown here is the SAD (sum of absolute differences) between the pixel value of the target block and the pixel value at the position indicated by the motion vector or the sum of absolute differences (SATD) of values obtained by performing two-dimensional Hadamard transform on the difference value. ) And the number of bits (vector cost) necessary for encoding the motion vector. In some cases, the cost value may be a value of only SAD or only SATD without considering the vector cost.

  On the other hand, when Cost_MVpre is equal to or smaller than the threshold value TH, the search center determining unit 204 determines the cost value Cost_MVP1 at the position indicated by the motion vector closest to MVP1 among all the motion vectors evaluated by the pre-search processing unit 202, and MVP2. Is compared with the cost value Cost_MVP2 at the position indicated by the motion vector closest to (step S3). When Cost_MVP1 is small, MVpre and MVP1 are determined as search centers (step S4), and when Cost_MVP2 is small, MVpre and MVP2 are determined as search centers (step S5).

  Further, it is possible even when there are two or more motion vectors searched by the pre-search processing unit 202 or when there are three or more prediction vectors generated from the prediction vector generation unit 203. The processing operation in the case where there are two motion vectors (hereinafter referred to as MVpre1 and MVpre2) and three prediction vectors (hereinafter referred to as MVP1, MVP2, and MVP3) searched by the pre-search processing unit 202 will be described.

  First, the search center determination unit 204 calculates the cost values Cost_MVpre1 and Cost_MVpre2 of the motion vector determined by the pre-search processing unit 202, and determines whether or not the values are larger than the threshold value TH. As a result of this determination, if the value is larger than the threshold value TH, the search center determination unit 204 determines that the motion vector obtained by the pre-search process is inaccurate and excludes it from the search center candidate. This process is performed for each of MVpre1 and MVpre2. If the total number of motion vectors and prediction vectors not excluded in this process is equal to or less than the number of desired motion vector candidates, the vector is determined as the search center.

  When the total number of motion vectors and prediction vectors not excluded in this process is larger than the number of desired motion vector candidates, the search center determination unit 204 includes all the motion vectors evaluated by the pre-search processing unit 202. The cost value Cost_MVP1 at the position indicated by the motion vector closest to MVP1 is compared with the cost value Cost_MVP2 at the position indicated by the motion vector closest to MVP2 and the cost value Cost_MVP3 at the position indicated by the motion vector closest to MVP3. Then, the motion vector is determined as the search center in ascending order of the cost value, and the process ends when the desired number of motion vector candidates is reached.

Second Embodiment
Next, a video encoding apparatus according to the second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in that the processing operation (FIG. 4) of the search center determining unit 204 shown in FIG. 2 is different. FIG. 5 is a flowchart showing the processing operation of the search center determination unit 204 according to the second embodiment. With reference to FIG. 5, the processing operation of the search center determination unit 204 according to the second embodiment will be described.

  First, the search center determining unit 204 calculates the cost value Cost_MVpre of the motion vector determined by the pre-search processing unit 202 as in the first embodiment, and determines whether or not the value is greater than the threshold value TH (step S11). As a result of this determination, if the value is larger than the threshold value TH, it is excluded from the search center candidates and MVP1 and MVP2 are determined as search centers (step S12).

  On the other hand, if Cost_MVpre is equal to or less than the threshold value TH, the search center determining unit 204 compares the sum of absolute differences of the motion vector components of MVpre and MVP1 with the sum of absolute differences of the motion vector components of MVpre and MVP2 (step S13). Then, the smaller one is determined as the search center (steps S14 and S15). Here, the motion vector components of MVpre, MVP1, and MVP2 are respectively MVprex, MVprey, MVP1x, MVP1y, MVP2x, and MVP2y.

  This indicates that a motion vector indicating a location close to the motion vector of MVpre is selected. Since the pre-search processing unit 202 is the result of performing the search process once on the reduced image, it is assumed that the encoding efficiency is better when the MVP closer to the motion vector of the pre-search processing unit 202 is selected. However, if the MVpre and the selected MVP are exactly the same or substantially the same vector, the motion search process 205 may increase the number of times that the same position is searched twice, which is contrary to the second embodiment. Alternatively, the MVP farther from the motion vector of the pre-search processing unit 202 may be selected.

  Next, the processing operation when there are two motion vectors (hereinafter referred to as MVpre1 and MVpre2) searched by the pre-search processing unit 202 and three prediction vectors (hereinafter referred to as MVP1, MVP2, and MVP3) will be described.

  First, the search center determination unit 204 calculates the cost values Cost_MVpre1 and Cost_MVpre2 of the motion vector determined by the pre-search processing unit 202, and determines whether or not the values are larger than the threshold value TH. As a result of this determination, if the value is larger than the threshold value TH, the search center determination unit 204 determines that the motion vector obtained by the pre-search process is inaccurate and excludes it from the search center candidate. This process is performed for each of MVpre1 and MVpre2. If the total number of motion vectors and prediction vectors not excluded in this process is equal to or less than the number of desired motion vector candidates, the vector is determined as the search center.

  When the total number of motion vectors and prediction vectors not excluded in this process is larger than the number of desired motion vector candidates, the search center determination unit 204 determines the sum of absolute differences of motion vector components of MVpre and MVP1 and The difference absolute value sum of the motion vector components of MVpre and MVP2 is compared with the difference absolute value sum of the motion vector components of MVpre and MVP3. Then, the search center is determined in order from the smallest MVP, and the process ends when the desired number of motion vector candidates is reached.

<Third Embodiment>
Next, a video encoding device according to a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment in that the processing operation (FIG. 4) of the search center determining unit 204 shown in FIG. 2 is different. FIG. 6 is a flowchart showing the processing operation of the search center determining unit 204 according to the third embodiment. With reference to FIG. 6, the processing operation of the search center determination unit 204 according to the third embodiment will be described.

  First, the search center determination unit 204 calculates the difference between the cost value Cost_MVP1 calculated by the pre-search processing unit 202 indicated by MVP1 and the cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by MVP2 and Cost_MVpre. The threshold value TH is compared (step S21). If this difference is smaller than the threshold value TH, it is predicted that MVpre will give a result very similar to MVP1 and MVP2. In this case, since the final search result is improved for the prediction vector obtained from the peripheral blocks of the target block, the search center determining unit 204 selects MVP1 and MVP2 (step S22).

  When the difference between the smaller value of CostMVP1 and CostMVP2 and CostMVpre is equal to or greater than the threshold value TH, the search center determination unit 204 and the cost value Cost_MVP1 calculated by the pre-search processing unit 202 indicated by MVP1 are the same as in the first embodiment. The cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by MVP2 is compared (step S23). As a result of the comparison, if CostMVP1 is small, the search center determining unit 204 determines MVpre and MVP1 as search centers (step S24). On the other hand, when CostMVP2 is small, the search center determining unit 204 determines MVpre and MVP2 as search centers (step S25).

  Next, the processing operation when there are two motion vectors (hereinafter referred to as MVpre1 and MVpre2) searched by the pre-search processing unit 202 and three prediction vectors (hereinafter referred to as MVP1, MVP2, and MVP3) will be described.

  First, the search center determination unit 204 calculates the cost value Cost_MVP1 calculated by the pre-search processing unit 202 indicated by the MVP1 and the cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by the MVP2 and the pre-search processing unit 202 indicated by the MVP3. The difference between the minimum value of the cost value Cost_MVP3 and Cost_MVpre1 and Cost_MVpre2 is calculated and compared with the threshold value TH. It is predicted that MVpre whose difference is smaller than the threshold TH will give a result that is very similar to MVP1, MVP2, and MVP3. In that case, since the final search result is improved for the prediction vector obtained from the peripheral block of the target block, the MVpre is excluded from the search center candidates.

  If the total number of motion vectors and prediction vectors not excluded in this process is equal to or less than the number of desired motion vector candidates, the vector is determined as the search center. If the total number of motion vectors and prediction vectors not excluded in this process is larger than the desired number of motion vector candidates, the search center determination unit 204, as in the first embodiment, indicates the pre-pointing point indicated by MVP1. The cost value Cost_MVP1 calculated by the search processing unit 202 and the cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by the MVP2 are compared with the cost value Cost_MVP3 calculated by the pre-search processing unit 202 indicated by the MVP3. As a result of this comparison, the search center is determined in ascending order of Cost, and the process ends when the desired number of motion vector candidates is reached.

<Fourth embodiment>
Next, a video encoding device according to a fourth embodiment of the present invention will be described. The fourth embodiment differs from the first embodiment in that the processing operation (FIG. 4) of the search center determination unit 204 shown in FIG. 2 is different. FIG. 7 is a flowchart showing the processing operation of the search center determining unit 204 according to the fourth embodiment. The fourth embodiment is a method combining the fourth embodiment and the second embodiment. With reference to FIG. 6, the processing operation of the search center determination unit 204 according to the third embodiment will be described.

  First, the search center determination unit 204 calculates the difference between the cost value Cost_MVP1 calculated by the pre-search processing unit 202 indicated by MVP1 and the cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by MVP2 and Cost_MVpre. Then, it is determined whether or not the threshold value TH is smaller (step S31). If the difference is smaller than the threshold value TH as a result of this determination, the search center determining unit 204 selects MVP1 and MVP2 (step S32).

  If the difference between the smaller value of Cost_MVP1 and Cost_MVP2 and Cost_MVpre is equal to or greater than the threshold value TH, the search center determining unit 204 determines the sum of absolute differences of the motion vector components of MVpre and MVP1 and the difference of the motion vector components of MVpre and MVP2. The sum of absolute values is compared (step S33). And the search center determination part 204 determines a smaller one as a search center as a result of this comparison (step S34, S35).

  Next, the processing operation when there are two motion vectors (hereinafter referred to as MVpre1 and MVpre2) searched by the pre-search processing unit 202 and three prediction vectors (hereinafter referred to as MVP1, MVP2, and MVP3) will be described.

  First, the search center determination unit 204 calculates the cost value Cost_MVP1 calculated by the pre-search processing unit 202 indicated by the MVP1 and the cost value Cost_MVP2 calculated by the pre-search processing unit 202 indicated by the MVP2 and the pre-search processing unit 202 indicated by the MVP3. The difference between the minimum value of the cost value Cost_MVP3 and Cost_MVpre1 and Cost_MVpre2 is calculated and compared with the threshold value TH. It is predicted that MVpre whose difference is smaller than the threshold TH will give a result that is very similar to MVP1, MVP2, and MVP3. In that case, since the final search result is improved for the prediction vector obtained from the peripheral block of the target block, the MVpre is excluded from the search center candidates.

  If the total number of motion vectors and prediction vectors not excluded in this process is equal to or less than the number of desired motion vector candidates, the vector is determined as the search center. When the total number of motion vectors and prediction vectors not excluded in this process is larger than the desired number of motion vector candidates, the search center determination unit 204 determines the absolute difference value between the motion vector components of MVpre and MVP1. The sum of absolute differences of motion vector components of MVpre and MVP2 is compared with the sum of absolute differences of motion vector components of MVpre and MVP3. Then, the search center is determined in order from the smallest MVP, and the process ends when the desired number of motion vector candidates is reached.

  As described above, by performing motion search by selecting two search centers in advance from the three search center candidate points MVpre, MVP1, and MVP2, it is possible to reduce the processing amount required for motion search by 2/3. It becomes.

  As described above, in the video encoder that uses the temporal correlation of the input image and performs motion prediction in units of rectangular coding blocks and processes the difference, the target coding block and the motion prediction destination The reference image is reduced and the motion prediction is performed, the prediction vector is calculated from the surrounding blocks of the target coding block, the search center point used for the motion prediction process is determined from the determined motion vector and the prediction vector, This is a video coding method characterized in that the amount of processing is reduced without reducing the coding efficiency by performing motion prediction processing using the determined search center point.

  According to this configuration, it is possible to determine the search center candidate from the motion vector information and the previous-stage motion search result without reading all the search center reference images, thereby reducing the processing amount without reducing the encoding efficiency. Can be reduced.

  You may make it implement | achieve the image coding apparatus in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be realized using hardware such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

  As mentioned above, although embodiment of this invention has been described with reference to drawings, the said embodiment is only the illustration of this invention, and it is clear that this invention is not limited to the said embodiment. is there. Therefore, additions, omissions, substitutions, and other modifications of the components may be made without departing from the technical idea and scope of the present invention.

  The present invention can be applied to a video encoding device and a video encoding program in which the amount of computation required for motion search processing is limited.

  DESCRIPTION OF SYMBOLS 100 ... Video coding apparatus, 101 ... Intra prediction process part, 102 ... Inter prediction process part, 103 ... Prediction residual signal generation part, 104 ... Transformation / quantization process part, 105 ... Entropy encoding unit, 106 ... Inverse quantization / inverse transformation processing unit, 107 ... Decoded signal generation unit, 108 ... Loop filter processing unit, 201 ... Reduced image generation unit, 202 ..Pre-search processing unit, 203... Prediction vector generation unit, 204... Search center determination unit, 205... Motion search processing unit, 206.

Claims (5)

A video encoding device that uses temporal correlation of a picture of an input video signal, performs motion prediction on a target block basis for each encoding block, and performs encoding processing of the difference,
The reference picture of the picture of the input video signal and the reference picture of the decoded video signal of the motion prediction destination is reduced, and the first encoded block of the picture of the reduced input video signal and the search area of the reference picture of the reduced decoded video signal are used. Motion vector determining means for determining a motion vector by executing the motion prediction process of
Prediction vector calculation means for calculating a prediction vector from the peripheral blocks of the target coding block;
Search center determination means for selecting one or more of the motion vector determined by the first motion prediction process and the prediction vector as a vector indicating a point serving as a search center point of the second motion prediction process;
Motion prediction means for performing the second motion prediction process using the determined search center point;
With
The search center determining means includes
When the cost value of the motion vector is compared with a threshold value and it is determined that the cost value of the motion vector is larger, the motion vector is excluded from vector candidates indicating points serving as search center points,
If the total number of the determined motion vector and the previous SL predicted vector the smaller of the cost value is larger than the number of desired as the candidate predicted vector calculation of all motion vectors evaluated in the motion vector determining means calculating a cost value of the motion vector closest position indicated in each prediction vector calculated by means of the calculated the motion vector corresponding to the cost value, the total number is desired in order from the cost values those small again number to become until selected and obtained movies picture coding apparatus you characterized in that the a point indicated by the motion vector that the indicated prediction vector and search center point used for the second motion prediction processing. A video encoding device that uses temporal correlation of a picture of an input video signal, performs motion prediction on a target block basis for each encoding block, and performs encoding processing of the difference,
The reference picture of the picture of the input video signal and the reference picture of the decoded video signal of the motion prediction destination is reduced, and the first encoded block of the picture of the reduced input video signal and the search area of the reference picture of the reduced decoded video signal are used. Motion vector determining means for determining a motion vector by executing the motion prediction process of
Prediction vector calculation means for calculating a prediction vector from the peripheral blocks of the target coding block;
Search center determination means for selecting one or more of the motion vector determined by the first motion prediction process and the prediction vector as a vector indicating a point serving as a search center point of the second motion prediction process;
Motion prediction means for performing the second motion prediction process using the determined search center point;
With
The search center determining means includes
When the cost value of the motion vector is compared with a threshold value and it is determined that the cost value of the motion vector is larger, the motion vector is excluded from vector candidates indicating points serving as search center points,
If the total number of the determined motion vector and the previous SL predicted vector the smaller of the cost value is larger than the number of desired as the candidate, with the motion vector and the predicted vector calculating means determined by the motion vector determining means calculated by calculating the distance between each prediction vector, the motion vector corresponding to the calculated the distance, the total number in order of the distance is small motion vectors obtained by selecting until a desired number of Film image encoding apparatus you characterized in that the search center point using a point indicated by the prediction vector and the point shown in the second motion prediction processing. A video encoding device that uses temporal correlation of a picture of an input video signal, performs motion prediction on a target block basis for each encoding block, and performs encoding processing of the difference,
The reference picture of the picture of the input video signal and the reference picture of the decoded video signal of the motion prediction destination is reduced, and the first encoded block of the picture of the reduced input video signal and the search area of the reference picture of the reduced decoded video signal are used. Motion vector determining means for determining a motion vector by executing the motion prediction process of
Prediction vector calculation means for calculating a prediction vector from the peripheral blocks of the target coding block;
Search center determination means for selecting one or more of the motion vector determined by the first motion prediction process and the prediction vector as a vector indicating a point serving as a search center point of the second motion prediction process;
Motion prediction means for performing the second motion prediction process using the determined search center point;
With
The search center determining means includes
Compared to calculate the difference between the cost value of the minimum value and the motion vector of the previous Ki予 measuring cost values of each predicted vector is pointing position calculated by the vector calculating unit threshold, it is determined that towards the threshold is greater The motion vector is excluded from vector candidates indicating the search center point,
If the total number of the determined motion vector and the previous SL predicted vector and the smaller of the threshold is large number by remote desired as the candidate, in the prediction vector calculation means of the motion vector determined by the motion vector determining means calculated motion vector closest to each prediction vector points to calculate the cost value of the position, the calculated the motion vector corresponding to the cost value, the total number in the order of the cost value small again within a desired number made up selected and obtained movies picture coding apparatus you characterized in that the a point indicated by the motion vector that the indicated prediction vector and search center point used for the second motion prediction processing. A video encoding device that uses temporal correlation of a picture of an input video signal, performs motion prediction on a target block basis for each encoding block, and performs encoding processing of the difference,
The reference picture of the picture of the input video signal and the reference picture of the decoded video signal of the motion prediction destination is reduced, and the first encoded block of the picture of the reduced input video signal and the search area of the reference picture of the reduced decoded video signal are used. Motion vector determining means for determining a motion vector by executing the motion prediction process of
Prediction vector calculation means for calculating a prediction vector from the peripheral blocks of the target coding block;
Search center determination means for selecting one or more of the motion vector determined by the first motion prediction process and the prediction vector as a vector indicating a point serving as a search center point of the second motion prediction process;
Motion prediction means for performing the second motion prediction process using the determined search center point;
With
The search center determining means includes
Compared to calculate the difference between the cost value of the minimum value and the motion vector of the previous Ki予 measuring cost values of each predicted vector is pointing position calculated by the vector calculating unit threshold, it is determined that towards the threshold is greater The motion vector is excluded from vector candidates indicating the search center point,
If greater than the number total number of the motion vector toward said threshold is determined to be smaller as the previous SL predicted vector is desired as the candidate, calculated by the motion vector and the predicted vector calculating means determined by the motion vector determining means The motion vector obtained by calculating the distance to each predicted vector and selecting the motion vector corresponding to the calculated distance in order from the smallest distance until the total number reaches the desired number is shown. point and the predicted vector to that movies picture encoding apparatus characterized in that the search center point used for the second motion prediction processing and the point indicated. A video encoding program for causing a computer to function as the video encoding device according to any one of claims 1 to 4 .

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