KR19990026427A - Motion vector distance calculation method in frame memory - Google Patents

Abstract

The present invention relates to a motion vector distance calculation method in a frame memory used in a motion compensation device.

In the method of the present invention, one frame includes a plurality of RAS boxes, and the RAS box includes 8 macroblocks (MB0 to MB7) of 8 macroblocks * 1 macroblock format. In order to obtain the motion vector distance MVD corresponding to the jump address according to the predicted macroblock reference point, determining the position of the reference point and the first to fifth motion vector distances MVD1 according to the position of each reference point. MVD5) is inferred from the block position and the macroblock position to calculate a plurality of motion vector distances in the horizontal or vertical direction according to the position of the reference point of the predicted macroblock.

Description

Method for calculating of moving-vector distances in a frame memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame memory for a motion compensation device, and more particularly, to calculate a plurality of motion vector distances based on a reference point in order to read a macroblock predicted by motion compensation from a frame memory in a field structure frame memory. It is about a method.

The motion compensation technique used in the Moving Picture Experts Group (MPEG) -2 standard is to reduce temporal redundancy by estimating and compensating for motion between two adjacent temporal pictures in macroblock units. That is, in the motion estimation and compensation process, a neighboring image is compared with the current image to detect a motion vector, which is information about an object's motion, and the current image is predicted using the motion vector.

In an MPEG-2 video encoder using such a motion compensation technique, the P picture performs forward motion compensation on the basis of the I picture or P picture of the previous picture with respect to the current picture, and the B picture performs the current picture. The best one is selected from among motion compensation blocks obtained by performing forward motion compensation, reverse motion compensation, and interpolated motion compensation based on the I picture or P picture of the previous picture and the I picture or P picture of the next picture.

The frame memory is used to store the I picture or P picture of the previous picture and the I picture or P picture of the next picture as the reference picture for motion compensation. In addition, the frame memory is used to temporarily store the decoded picture and read out the display order in a MPEG-2 video decoder because the decoding order and the display order are different from each other.

However, the frame memory as described above has a capacity to store at least three frames of image data according to the I picture and the P picture or the distance M between the P picture and the P picture, and therefore, the price is expensive, and thus, the entire picture. In addition to raising the price of the decoder, there is a problem that the delay time from the completion of decoding to the display increases.

Accordingly, the present invention has been made to solve the above problems, and includes a region for storing reference image data, a region for storing decoded image data for display, and an encoded bitstream input to an image decoder. A frame memory in which an area to be stored is implemented on one memory module, comprising: a plurality of frames based on a reference point according to a position of a reference point of a macroblock predicted to read a macroblock predicted by motion compensation from a frame memory The purpose of the present invention is to provide a method of calculating the distance of a dog vector.

In the apparatus of the present invention for providing the above object, one frame is composed of a plurality of RAS boxes, the RAS box is a frame consisting of eight macroblocks (MB0 ~ MB7) of 8 macroblocks * 1 macroblock format In the memory, calculating a reference point of the predicted macroblock, determining a block in which the reference point is located, and determining the first to fifth motion vector distances MVD1 to MVD5 according to the block in which the reference point is located. It characterized in that it comprises the step of calculating.

1 is a diagram showing the structure of a frame memory adopted in the present invention;

2 is a diagram illustrating a scheduling order of the frame memory shown in FIG. 1;

3 is a view showing an example of a method for setting a RAS box for one frame used in the present invention in the frame memory shown in FIG. 1;

4 is a view showing an example of a macroblock structure in the RAS box shown in FIG.

FIG. 5 is a diagram illustrating horizontal and vertical distances of each motion vector according to a block in which a predicted macroblock is located in a frame memory having the structure shown in FIGS. 3 and 4;

6 is a flowchart illustrating a motion vector distance calculation method according to the present invention.

* Explanation of symbols for main parts of the drawings

100: frame memory

100-1 to 100-4: First to fourth frame storage areas

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

1 illustrates a structure of a frame memory adopted in the present invention, in which the frame memory 100 includes a restored image data write operation, a data read operation for motion compensation, and a data read operation for display to a memory controller (not shown). Is controlled by The frame memory 100 has two memory banks, bank 1 and bank 2, bank 1 has first and second frame storage areas 100-1 and 100-2, and bank 2 stores third and fourth frames. There are regions 100-3 and 100-4. Here, the first to fourth frame storage areas 100-1, 100-2, 100-3, and 100-4 have a capacity for storing pixel data of one frame, respectively, and the first to fourth frame storage areas 100-1, 100-. 2,100-3 and 100-4 each have 1,024 row addresses, and have a column address of 256 words (where 1 word is 8 bits). One address stores eight Y pixels, two Cr pixels, two Cb pixels, and a total of 12 pixel data. Here, 1,024 row addresses mean the number of RAS boxes. The 256-word column address is derived by eight macroblocks per one RAS box * 32 boxes per macroblock (= 256 boxes).

The actual physical row address of the frame memory 100 is 000 _H to 3FF _H , 400 _H to 7FF _H for the first to fourth frame storage areas 100-1 to 100-4, respectively. , 800 _H to BFF _H and C00 _H to FFF _H. However, the first to fourth frame storage regions 100-1 to 100-4 exist independently, and the second and fourth frames corresponding to the macroblocks located at predetermined row addresses of the first frame storage region 100-1 are respectively provided. The macroblocks of the third frame storage areas 100-2 and 100-3 have the same row address. As such, the row address in the first to third frame storage areas 100-1 to 100-3 is referred to as a virtual row address. Then, based on the scheduling order of the frame memory 100 as shown in FIG. 2 during motion compensation, an address used to convert a virtual row address in a corresponding storage area in which a reference image is located into a physical row address is framed. It is called the frame offset address and is called RA [11:10]. That is, if RA [11:10] is '00', the first frame storage area 100-1, if '01', the second frame storage area 100-2, and if the '10', the third frame storage area 100 -3) and '11' indicate the fourth frame storage areas 100-4, respectively.

Here, the first and second frame storage areas 100-1 and 100-2 are used to store reconstructed I-picture or motion-compensated P-picture image data for use as a reference image for motion compensation and simultaneously for display. The three-frame storage area 100-3 is used to store the motion compensated B-picture image data, and the fourth frame storage area 100-4 stores the encoded bitstream input to the image decoder in units of predetermined bits. Used to save.

FIG. 2 shows a scheduling order of the frame memory 100 shown in FIG. 1, and the decoding order is I, P, B, B, P, B, B, P, B, B, P, B, B, I. , P, B, B, ... and the display order is I, B, B, P, B, B, P, B, B, P, B, B, P, I, B, B, ... For example, the display latency is 2 pictures. Here, the underlined portion indicates the picture currently being decoded, the arrow indicates the picture to be referred for motion compensation, and the storage area to which 'D' is added indicates that image data is fetched for display.

FIG. 3 shows an example of a method for setting a RAS box for one frame in the frame memory 100 shown in FIG. 1. For example, when one frame includes 1,920 pixels * 1,088 pixels, 30 RAS boxes * 34 It is divided into RAS boxes, a total of 1,020 Row Address Strobe (RAS) boxes. That is, the number of the RAS box is the row address (RA) of the frame memory 100. Here, one RAS box is composed of eight macroblocks * 1 macroblocks and a total of eight macroblocks MB0 to MB7. Each macroblock is divided into four blocks b0 to b3 when the luminance Y block is taken as an example.

FIG. 4 shows an example of a macroblock structure in the RAS box shown in FIG. 3, with four luminance (Y) blocks b0 to b3, one color difference (Cr) block, and one color difference (Cb) block. Four luminance (Y) blocks are composed of eight boxes (b0-0 to b0-7, b1-0 to b1-7, b2-0 to b2-7, and b3-0 to b3-7), respectively. Each of the two color difference (Cr, Cb) blocks has eight sub boxes (sb0-0 to sb0-7, sb1-0 to sb1-7, sb2-0 to sb2-7, and sb3-0 to sb3-7). It consists of. Then, 8 pixel data in 8 * 1 format for each box constituting the Y block, 2 pixel data in 2 * 1 format for each box constituting the Cr block, and 2 * 1 format for each box constituting the Cb block. There are two pixel data of.

3 and 4, when looking at the open dress CA [7: 0], the position of the macroblock in one RAS box is CA [7: 5] and the position of the block in the macroblock. CA [4: 3], the position of the box in the block is called CA [2: 0], and the position of the pixel in the box is called the pixel address PA [2: 0]. In addition, a line in which the row address is changed in one frame is called a RAS line, and a line in which the open address is changed is called a CAS (Column Address Strobe) line.

5 is a block in which a start address of a current macroblock to be motion compensated, that is, a slice position and a macroblock position (mb-position), and a macroblock MBp predicted from vertical and horizontal motion vectors are located. It shows the horizontal and vertical distance of each motion vector according to.

6 is a flowchart illustrating a method of calculating a motion vector distance according to the present invention, wherein the reference point calculation step (step 61) of the predicted macroblock MB is performed, and the motion vector distance is calculated according to the block in which the reference point is located. (62th to 69th steps).

Next, a motion vector distance calculation method according to the present invention will be described with reference to FIGS. 5 and 6.

First, the method of the present invention calculates the reference point of the macroblock predicted by the motion compensation based on the slice position and the macroblock position and the motion vector of the macroblock used for the prediction (step 61), and the frame memory 100 In operation 62, 64, 66, and 68, the block in which the reference point of the predicted macroblock is located is determined. Looking at each case according to the position of the reference point as follows.

First, when the reference point of the predicted macroblock MBp is located in the block b0 as shown in case a shown in FIG. 5, the first to fifth motion vectors are as follows based on the reference point RP. The distances MVD1 to MVD5 are obtained (step 63).

MVD1 = RP + x

MVD2 = RP + (x + x ') = RP + mv_h (inc)

MVD3 = RP + y

MVD4 = RP + x + y

MVD5 = RP + y + x + x '= RP + mv_h (inc) + y

Second, when the reference point of the macroblock MBp predicted as in case b is located in the block b1, the first to fifth motion vector distances MVD1 to MVD5 as follows based on the reference point RP. (Step 65).

MVD1 = RP + x '

MVD2 = RP + (x + x ') = RP + mv_h (inc)

MVD3 = RP + y

MVD4 = RP + x '+ y

MVD5 = RP + y + x + x '= RP + mv_h (inc) + y

Third, when the reference point of the macroblock MBp predicted as in case c is located in the block b2, the first to fifth motion vector distances MVD1 to MVD5 as follows based on the reference point RP. (Step 67).

MVD1 = RP + x

MVD2 = RP + (x + x ') = RP + mv_h (inc)

MVD3 = RP + y '

MVD4 = RP + x + y '

MVD5 = RP + y '+ x + x' = RP + mv_h (inc) + y '

Fourth, when the reference point of the macroblock MBp predicted as in case d is located in the block b3, the first to fifth motion vector distances MVD1 to MVD5 as follows based on the reference point RP. (Step 69).

MVD1 = RP + x '

MVD2 = RP + (x + x ') = RP + mv_h (inc)

MVD3 = RP + y '

MVD4 = RP + x '+ y'

MVD5 = RP + y '+ x + x' = RP + mv_h (inc) + y '

In the cases a to d, look at x

Since blk _{i + 1} = blk _i + 1, the horizontal motion vector mv_h (3) is increased by one.

Since blk _{i + 1} = blk _i -1 and MB _{i + 1} = MB _i + 1, the horizontal motion vector mv_h (3) is decreased by 1 and the horizontal motion vector mv_h (9: 4) is increased by one. do. And look at y

Since blk _{i + 1} = blk _i + 2, the vertical motion vector mv_v (3) is increased by one. Looking at y ',

Since blk _{i + 1} = blk _i -2 and MB _{i + 1} = MB _i + 120, the vertical motion vector mv_v (3) is decreased by 1 and the vertical motion vector mv_v (5: 4) is increased by one. Becomes

here,

x + x ': mv_h _{i + 1} = mv_h _i + 1, which is represented by an increment of the horizontal motion vector mv_h (9: 4), that is, mv_h (inc). Also,

y + y ': mv_v _{i + 1} = mv_v _i +120, which is represented by an increment of the vertical motion vector mv_v (5: 4), that is, mv_v (inc).

On the other hand, the above detailed description is intended to describe particular embodiments presented herein and is not intended to limit the present invention. Those skilled in the art may make various changes and modifications according to the structure of the RAS box and the structure of the macroblock block within the technical spirit of the present invention with reference to the above detailed description and drawings.

As described above, in the method of the present invention, the first to fourth frame storage regions are implemented on one memory module, and in a frame memory having a field structure, the method is predicted by a start address and a motion vector of a current macroblock. A plurality of motion vector distances in the horizontal or vertical direction may be calculated according to the position of the reference point of the macroblock predicted to read the macroblock from the frame memory.

Claims (1)

In one frame is composed of a plurality of RAS box, the RAS box is a frame memory consisting of eight macroblocks (MB0 ~ MB7) of 8 macroblocks * 1 macroblock format, Calculating a reference point of the predicted macroblock; Determining a block in which the reference point is located; And And calculating first to fifth motion vector distances (MVD1 to MVD5) according to the block in which the reference point is located.