JP2963269B2 - Motion compensation prediction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion compensation prediction apparatus, and more particularly, to original picture block data constituted by dividing a current picture inputted by raster scan and reference picture block data constituted by dividing a reference picture. The present invention relates to a motion-compensated prediction device that performs a block-matching operation to generate a motion vector and performs motion compensation on predicted screen block data (local decoded screen block) configured by dividing a predicted screen.

[0002]

2. Description of the Related Art In a high-efficiency encoding of a moving image signal, a motion compensation prediction method is well known as a factor for increasing a compression ratio. The block is divided into blocks of a certain size (for example, 16 pixels × 16 lines), and for each block, a block having the least prediction error is searched from, for example, prediction screens i1 to i3 as shown in FIG. is there.

A moving picture using such a motion compensation prediction method
FIG. 14 shows a configuration of a conventional example of an image encoding device ,
A subtractor 1 obtains a difference value between original image block data obtained by dividing the current screen input by raster scanning and a motion-compensated prediction screen, and this difference value is quantized (Q).
Then, the prediction error is generated by quantization in step 2 and sent to the receiving side, and the prediction error is added to the motion-compensated prediction screen by the adder 3 to generate a prediction screen and stored in the frame memory 4. Hereinafter, the block data may be abbreviated to simply represent the original image, the prediction screen, and so on.

[0004] The prediction screen stored in the frame memory 4 and the input original image are input to a motion compensation prediction device MC. A motion vector is generated by matching operation and sent to the receiving side. Also, the difference between the original picture to be input and the prediction screen is made as small as possible by giving the prediction screen of the frame memory 4 to the subtractor 1 by delaying the prediction screen of the frame memory 4 by the value indicated by the motion vector. Thus, the prediction error to be transmitted is minimized to achieve highly efficient encoding of the moving image signal.

[0005]

As a prediction method in the above-described motion compensation prediction method, a one-way prediction in which a prediction is performed from a forward direction or a backward direction as shown by arrows in FIGS. 3 (1) to (3), respectively. Predictive Coded Picture (below,
"P") and bidirectional prediction (Bidirectionary Predictive Code) that performs prediction from both front and rear directions.
d Picture (hereinafter may be abbreviated as “B”), and various predictions such as a case where the prediction screen uses the original image signal itself or a case where the local decode signal stored in the frame memory 4 is used. There is a method. still,
The screen I is a frame to be intra-coded, and prediction between frames is not performed.

In these cases, the method of reading and writing the image data is different from each other, but conventionally, there has been a problem that a circuit must be individually configured according to each prediction method.

Therefore, according to the present invention, a motion vector is obtained by performing a block matching operation using original image block data formed by dividing a current screen input by raster scanning and reference screen block data formed by dividing a reference screen. A motion-compensated prediction device that performs motion compensation on predicted screen block data that is generated and divided into predicted screens, so that even if the prediction method changes, it is possible to support various prediction methods without changing the circuit configuration. The purpose is to:

[0008]

FIG. 1 shows a principle of a motion compensation prediction apparatus according to the present invention for achieving the above object. In the present invention, original image block data and predicted screen block data are used. An external frame memory EFM capable of sequentially writing / reading is provided for each bank, and original image block data and reference screen block data necessary for motion compensation prediction in the forward, backward, or both forward and backward directions are read from the external frame memory EFM. This is characterized in that the motion vector is stored in the internal memory 10 and the matching operation unit 20 performs a block matching operation to generate a motion vector.

In the present invention, the original block data may be read from the external frame memory EFM as the reference screen block data.

In the present invention, the predicted screen block data may be read from the external frame memory EFM as the reference screen block data.

In the present invention, the external frame memory E
FM banks can be switched cyclically for use.

Further, according to the present invention, the external frame memory EFM is provided by a data bus DB for transmitting and receiving data in a time-division manner.
And can be connected.

[0013]

In the operation of the motion compensation prediction apparatus according to the present invention shown in FIG. 1, first, original picture block data (FIG. 2 (1)) constituted by dividing current screen data inputted by raster scan is used. The prediction screen block data (local decode data) configured by dividing the prediction screen stored in a frame memory (not shown) provided in the normal Writing to an external frame memory EFM different from the frame memory.

From this external frame memory EFM, original picture block data necessary for motion compensation prediction in the forward, backward, or both forward and backward directions and reference picture block data as shown in FIG.

This will be described with reference to FIG.
In the case of the prediction shown in FIG.
6 is generated by predicting the screen block P3 in the forward direction, for example, the above-described predicted screen block data is read from the external frame memory EFM as reference screen block data, or in the case of prediction shown in FIG.
For example, in the case of the screen block B9, the screen block P
8 and P10 are generated by predicting forward and backward directions, so that, for example, the above-described original image block data is read from the external frame memory EFM as reference screen block data.

The original block data and the reference screen block data thus read out are stored in the internal memory 10 having a higher access speed than the external frame memory EFM. By performing a calculation to generate a motion vector, motion compensation is performed on the predicted screen block data.

Thus, forward prediction, backward prediction,
Various prediction methods are supported by changing the capacity of the external frame memory EFM and the access to the external frame memory EFM according to a bidirectional prediction or a prediction method such as using original image block data for the reference screen or using prediction screen block data. Motion compensated prediction is realized.

If the banks of the external frame memory EFM are cyclically switched according to various prediction methods, the external frame memory EFM can be used effectively.

Further, by forming data into a bus to increase the bit width, it is possible to share and access the address lines without lowering the access speed to the external frame memory EFM.

[0020]

FIG. 4 shows a motion compensation prediction apparatus MC according to the present invention.
In this embodiment, an external frame memory EMF is provided in addition to the conventional example shown in FIG. 14, and the original block data of the raster-scanned input screen is shown in FIG. After passing through the motion compensation prediction device MC, the data is written into the external frame memory EFM, and the timing is adjusted by the delay circuit 6 and then supplied to the subtracter 1. In this embodiment, in the motion estimation, the original image block data is used as the reference screen block data, and the predicted screen block data from the frame memory 4 is also used as the reference screen block data. The memory FM2 has a two-sided configuration.

FIG. 5 shows an embodiment of the motion compensation prediction device MC shown in FIGS. 1 and 4. In this embodiment, the internal memory 10 stores the original block data read from the external frame memory EFM. RAM for writing data
10a and an internal RAM for writing original image block data or predicted screen block data as reference screen block data read from the external frame memory EFM
10b, these internal RAMs 10a,
10b is controlled by a memory control unit (address generation unit) 11.

Further, the matching calculation unit 20 determines the blocks i ₁ , i ₂ ,... On the prediction screen (for example, the previous screen in the case of inter-frame prediction) for the original block data on the current screen.
, I _n and a matching operation is performed to detect a block having the smallest error determined by a certain evaluation method. In this embodiment, a sum of absolute difference value method is employed as an evaluation method as shown in the figure. It comprises a subtracter 21, an absolute value circuit 22, an adder 23, and a register 24.

This means that the data (pixel value) in the original picture block on the current screen read from the internal RAM 10a is represented by X
_k (k = 1 to 256; when the block is 16 pixels × 16 pixels), the data in the block at the position i on the reference screen read from the internal RAM 10b (see FIG. 13) is represented by Y _{i, k} (k
= 1 to 256), the evaluation value S _i of the block i is obtained by the following equation (1): S _i = Σ | X _k −Y _{i, k} | The minimum i is detected by the minimum value detection unit 12 to become an optimal prediction block, and the motion vector at this time is generated via the conversion unit 13.

The operation of the above embodiment will be described with reference to the access order (memory bank switching order) of the external frame memory EFM shown in FIGS. FIGS. 6 to 8 correspond to the prediction methods of FIGS. 3 (1) to 3 (3), respectively.

First, raster-scanned input screen data is written to the external frame memory EFM. In this case, the input screen numbers shown at the top of FIGS. 6 to 8 only indicate that they correspond to the screens generated by the prediction processing shown in FIGS. 3 (1) to 3 (3), respectively. However, this does not indicate that the predicted screen is actually input.

Therefore, these input screens are stored as original picture block data in a plurality of banks (see FIG. 9) constituting the external frame memory EFM as shown by the numerals in the figure. Note that the horizontal line of the bank number indicates a period during which the screen block data needs to be held.

For example, in the example of FIG. 6, the screen I0 is the bank #
0, screen B1 is in bank # 1, screen B2 is in bank # 2
, And so on. However, in this case, the banks corresponding to the fifteen screens of the screens I0 to B14 are not necessarily required. In the example shown in FIG. 3A, the prediction is performed by a constant repetition. It suffices if there are six banks. The banks # 6 and # 7 are prepared for storing the predicted screen block data from the frame memories FM1 and FM2, not the original pictures.

The screen block data stored in each bank is read out in the order shown by the arrow in FIG. 3A and written into the internal RAM 10a in FIG. Is the B screen, the original images stored in the banks # 0 to # 5 are written into the internal RAM 10b as reference screens, and when the original block data is the P screen, the frame memories FM1 and FM2 stored in the banks # 6 and # 7. Is written in the internal RAM 10b as a reference screen. And FIG.
The matching calculation is performed by the matching calculation unit 20 of
A motion vector is output. The motion vector also includes information on forward prediction or backward prediction, and data from the frame memory FM1 or FM2 is selected accordingly, and the delay according to the motion vector is set in the variable delay circuit 5. A more favorable prediction value given is obtained.

It should be noted that whether the reference screen is an original picture or a prediction picture is not limited to the above, and a motion vector can be similarly generated in the opposite case.

FIG. 9 shows the access state of the external frame memory EFM at the time T1 in the example of FIG. 6. To explain this, the input original picture block data B8 is stored in the bank # of the external frame memory EFM. 2, the original image processed at the time T1 is not B8, but an earlier original image B4. This original image B4 is read from the bank # 4 and written into the internal RAM 10a, and the original image B4 is stored in the reference screen. Since the original images P3 and P6 are predicted and generated in the front-rear direction (see FIG. 3A), the original image P6 is read from the bank # 1, the original image P3 is read from the bank # 3, and written to the internal RAM 10b. To perform a matching operation.

At time T2, the input original block data B10 is stored in the bank # 3 of the external frame memory EFM. The original processed at this time T2 is the original P9. Is read from the bank # 4 and written into the internal RAM 10a. The original image P9 is subjected to a prediction process, stored in the frame memory 4 (for example, the frame memory FM1), and then written into the bank # 7 as predicted screen block data.

The original picture P9 is generated by forward prediction from the prediction picture P6 of the bank # 6, which is a reference picture (FIG. 3).
Therefore, in this case, the prediction screen P6 is read from the bank # 6, which has already been subjected to the prediction processing and written, written into the internal RAM 10b, and the matching operation is performed as described above (see FIG. 10) .

Similarly, in FIGS. 7 and 8, FIG.
And (3) respectively correspond to the external frame memories EFM
Access can be performed.

As can be seen from FIGS. 6 to 8, the capacity required for the external frame memory EFM is 8
Plane, 7 planes, and 5 planes.

FIG. 11 shows an embodiment in which the original picture block data and the reference picture block data between the external frame memory EFM and the motion compensation prediction device MC are connected to each other as 8-bit data by a bus DB. By connecting the buses in this manner, a set of addresses can be obtained. However, it is necessary to increase the data width of the bus DB in order to secure the access speed.
4 bits.

FIGS. 12 (1) and 12 (2) show P screen processing and B screen processing when the bus DB is used as in the embodiment of FIG. 11, respectively.
The memory access (bank switching) shown in FIGS. 6 to 9 can be executed by allocating the time slots TS0 to TS7 corresponding to the cycle.

[0037]

As described above, according to the motion compensation prediction apparatus of the present invention, the external frame memory which can sequentially write / read the original block data and the predicted screen block data for each bank is provided. Since the original block data and the reference screen block data necessary for the motion compensation prediction in the forward, backward, or both forward and backward directions are read from the memory and the block matching operation is performed to generate the motion vector, various types of motion compensation prediction are performed. It is possible to flexibly cope with the system by changing the capacity of the external frame memory and the access method.

Further, the external frame memory can be effectively used by cyclically using the bank of the external frame memory, and the address lines can be shared by busing data with the external frame memory.

[Brief description of the drawings]

FIG. 1 is a block diagram showing in principle the configuration of a motion compensation prediction device according to the present invention.

FIG. 2 is a block diagram showing an example of a scan order of screen block data in the motion compensation prediction device according to the present invention.

FIG. 3 is a diagram showing examples of various prediction methods used in the motion compensation prediction device according to the present invention.

FIG. 4 is a block diagram showing an embodiment of the entire encoding device using the motion compensation prediction device according to the present invention.

FIG. 5 is a block diagram showing an embodiment of a motion compensation prediction device according to the present invention.

FIG. 6 is a time chart showing an access order example (part 1) of an external frame memory by the motion compensation prediction apparatus according to the present invention.

FIG. 7 is a time chart showing an access order example (part 2) of the external frame memory by the motion compensation prediction device according to the present invention.

FIG. 8 is a time chart showing an access order example (part 3) of the external frame memory by the motion compensation prediction device according to the present invention.

FIG. 9 is a diagram showing an access state of an external frame memory at a time T1 in FIG. 6;

FIG. 10 is a diagram showing an access state of an external frame memory at time T2 in FIG. 6;

FIG. 11 is a block diagram showing an embodiment in which a data bus is shared in the motion compensation prediction device according to the present invention.

FIG. 12 is a diagram showing an example of time slot allocation when a data bus is shared as shown in FIG. 11;

FIG. 13 is a block diagram for explaining the principle of motion compensation.

FIG. 14 is a block diagram showing a conventional technique.

[Explanation of symbols]

 MC motion compensation prediction device EFM external frame memory 10 internal memory 20 matching operation unit 4 (FM1, FM2) frame memory In the drawings, the same reference numerals indicate the same or corresponding parts.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Matsuda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-265387 (JP, A) edited by Hiroshi Yasuda, “Multimedia Maruzen, June 1991, p. 131-132, Nikkei Electronics, No. 503, p. 209-222 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 7 / 24-7/68

Claims (5)

(57) [Claims] 1. A motion vector is generated and predicted by performing a block matching operation using original image block data formed by dividing a current screen input by raster scan and reference screen block data formed by dividing a reference screen. In a motion compensation prediction device (MC) that performs motion compensation on predicted screen block data configured by dividing a screen, the original block data and the predicted screen block data can be sequentially written / read for each bank. External frame memory
(EFM), read the original image block data and reference screen block data necessary for motion compensation prediction in the forward, backward, or both forward and backward directions from the external frame memory (EFM), and read them from the internal memory (10).
The motion compensation prediction apparatus characterized in that the motion vector is generated by performing a block matching calculation in a matching calculation unit (20). 2. The motion compensation prediction device according to claim 1, wherein said original picture block data is read from said external frame memory (EFM) as said reference picture block data. 3. The motion compensation prediction apparatus according to claim 1, wherein said predicted screen block data is read from said external frame memory (EFM) as said reference screen block data. 4. The motion compensation prediction device according to claim 1, wherein banks of the external frame memory (EFM) are cyclically switched and used. 5. A data bus for transmitting and receiving data in a time sharing manner.
5. The motion compensation prediction device according to claim 1, wherein the motion compensation prediction device is connected to the external frame memory (EFM) by (DB).