JPH05260461A - Motion compensation prediction device - Google Patents

Abstract

PURPOSE:To allow the device to be compatible with various prediction systems by reading original picture block data and reference picture block data required for the motion compensation prediction in both forward and reverse directions from an external frame memory to implement block matching calculation thereby generating a motion vector. CONSTITUTION:Original picture block data and reference picture block data required for the motion compensation prediction in a forward direction or in a backward direction or in both the forward and reverse directions are read in the unit of blocks from an external frame memory EFM. The data are stored in an internal memory 10 with a faster access speed than that of the external frame memory EFM, the data are sequentially read from the memory 10, block matching calculation is implemented by a matching arithmetic operation section 20, a motion vector is generated and motion compensation is applied to prediction picture block data. Then the capacity of the external frame memory EFM and accessing thereto are changed depending on the prediction method such as forward prediction or use of original picture block data for a reference picture and the motion compensation prediction corresponding to various prediction systems is realized.

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 formed by dividing a current picture input by raster scan and reference picture block data formed by dividing a reference picture. The present invention relates to a motion compensation prediction device that performs motion compensation on prediction screen block data (local decoded screen block) configured by performing block matching calculation to generate a motion vector and dividing a prediction screen.

[0002]

2. Description of the Related Art A motion-compensated prediction method is well known as an element for increasing the compression rate in high-efficiency coding of a moving picture signal. This motion-compensated prediction method is shown in FIG. 13 (1). The block is divided into blocks of a certain size (for example, 16 pixels × 16 lines), and for each block, for example, the block with the smallest prediction error is searched from the prediction screens i1 to i3 as shown in FIG. is there.

The structure of a conventional example of such a motion-compensated prediction method is shown in FIG. 14, in which original image block data formed by dividing a current screen input by raster scanning and a motion-compensated predicted screen are displayed. Subtractor 1 calculates the difference value of
This difference value is quantized by the quantizer (Q) 2 to generate a prediction error and sent to the receiving side, and the prediction screen is obtained by adding this prediction error and the motion-compensated prediction screen by the adder 3. It is generated and stored in the frame memory 4.
In the following description, the block data may be omitted by simply abbreviating the original image, the prediction screen, and so on.

Then, the prediction screen stored in the frame memory 4 and the input original image are input to the motion compensation prediction device MC, a motion vector is generated by a matching calculation and sent to the receiving side, and the motion vector is delayed by a variable delay. The prediction screen of the frame memory 4 which is also given to the unit (VDL) 5 is delayed by the value indicated by the motion vector and sent to the subtractor 1, so that the difference value between the input original image and the prediction screen is made as small as possible. In this way, the prediction error to be transmitted is minimized to achieve high-efficiency coding of moving image signals.

[0005]

As a prediction method in the motion compensation prediction method as described above, a unidirectional method for predicting 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)
d Picture, which may be abbreviated as “B” hereinafter) and the like, and various predictions such as the case where the original picture signal itself is used as the prediction screen and the 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 that is intra-frame coded, and prediction between frames is not performed.

In these cases, the method of reading image data and the method of writing image data are different from each other, but in the past, there was a problem that a circuit had to be individually configured according to each prediction method.

Therefore, according to the present invention, a block matching operation is performed by using the original image block data formed by dividing the current screen input by the raster scan and the reference screen block data formed by dividing the reference screen to obtain the motion vector. In a motion-compensated prediction device that performs motion compensation on prediction screen block data that is generated by dividing a prediction screen, it is possible to support various prediction methods without changing the circuit configuration even if the prediction method changes. The purpose is to

[0008]

FIG. 1 shows the 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 prediction screen block data are 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 direction, backward direction, or both front and rear directions are read from the external frame memory EFM. It is characterized in that a motion vector is generated by storing it in the internal memory 10 and performing a block matching calculation in the matching calculation unit 20.

Further, in the present invention, the original picture 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.

According to the present invention, the external frame memory E
The FM bank can be used cyclically by switching.

Further, according to the present invention, the external frame memory EFM is provided by a data bus DB which transmits and receives data in a time division manner.
Can be connected with.

[0013]

In the operation of the motion compensation prediction apparatus according to the present invention shown in FIG. 1, first, the original image block data (the original image block data formed by dividing the current screen data input by the raster scan as shown in FIG. (See (2) in the figure) and prediction screen block data (local decoded data) configured by dividing a prediction screen stored in a frame memory (not shown) provided in a normal encoding device Writing to an external frame memory EFM different from the frame memory.

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

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

The original image block data and the reference screen block data thus read out are stored in the internal memory 10 having an access speed faster than that of the external frame memory EFM, and are sequentially read out from the internal memory 10 and the matching operation unit 20 performs block matching. Motion compensation is performed on the prediction screen block data by performing a calculation to generate a motion vector.

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 the prediction method such as bidirectional prediction or using the original image block data for the reference screen or the predicted 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 effectively used.

Further, by making the data into a bus and widening the bit width, the address lines can be shared and accessed without reducing the access speed with the external frame memory EFM.

[0020]

FIG. 4 is a block diagram of a motion compensation prediction device MC according to the present invention.
An example of the entire encoding apparatus using (LSI) is shown. In this example, an external frame memory EMF is provided in addition to the conventional example of FIG. 14, and the original image block data of the raster-scanned input screen is The data is passed through the motion compensation prediction device MC, written in the external frame memory EFM, and timing-matched by the delay circuit 6, and then given to the subtractor 1. In this embodiment, in the motion prediction, 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 structure.

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

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

This is because the data (pixel value) in the original picture block on the current screen read from the internal RAM 10a is X-valued.
_k (k = 1 to 256; when the block is 16 pixels × 16 pixels), the data in the block (see FIG. 13) at the position i on the reference screen read from the internal RAM 10b is Y _{i, k} (k
= 1 to 256), the evaluation value S _i of the block i is obtained by S _i = Σ | X _k −Y _{i, k} | The minimum i is detected by the minimum value detection unit 12 and becomes the optimum 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 sequence (memory bank switching sequence) of the external frame memory EFM shown in FIGS. 6 to 8 correspond to the prediction methods of FIGS. 3 (1) to 3), respectively.

First, the raster-scanned input screen data is written in 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 process shown in FIGS. 3 (1) to 3), respectively. , It does not mean that the predicted screen is actually input.

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

For example, in the example of FIG. 6, the screen I0 is bank #
0, screen B1 in bank # 1, screen B2 in bank # 2
It is stored in, and so on. However, in this case, banks corresponding to 15 screens of screens I0 to B14 are not required, and in the example shown in FIG. 3 (1), prediction is performed by a certain repetition, so as shown in FIG. It would be good if there were 6 banks. Further, the banks # 6 and # 7 are prepared to store predicted screen block data from the frame memories FM1 and FM2 instead of the original images.

In the screen block data thus stored in each bank, original images are read out in the order shown by the arrow in FIG. 3 (1) and written in the internal RAM 10a in FIG. Becomes the B screen, the original images stored in the banks # 0 to # 5 are written to the internal RAM 10b as the reference screen, and when the original image block data becomes the P screen, the frame memories FM1 and FM2 stored in the banks # 6 and # 7 are stored. The prediction screen of is written in the internal RAM 10b as a reference screen. And FIG.
Matching operation is executed by the matching operation unit 20 of
The motion vector is output. This motion vector also includes information of forward prediction or backward prediction, the data from the frame memory FM1 or FM2 is selected accordingly, and the variable delay circuit 5 delays the delay according to the motion vector. A more favorable predictive value is given.

It should be noted that whether the reference screen is the original image or the prediction screen is not limited as described above, and the motion vector can be similarly generated in the opposite case.

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

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

Further, the original picture P9 is forward predicted and generated from the prediction screen P6 of the bank # 6 which is the reference screen (FIG. 3).
(1)), the prediction screen P6 is read from the bank # 6 which is already subjected to the prediction process and written, and is written in the internal RAM 10b, and the matching operation is executed as described above.

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

As can be seen from FIGS. 6 to 8, the capacity required for the external frame memory EFM is 8 each.
There are 7 faces and 5 faces.

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 apparatus MC are connected as 8-bit data by a bus DB, respectively. By connecting to the bus in this way, it is possible to form one set of addresses. However, in order to secure the access speed, it is necessary to widen the data width of the bus DB, which is 8 times 6
It is 4 bits.

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 capable of sequentially writing / reading the original image block data and the prediction screen block data for each bank is provided, and the external frame memory is provided. Since the original image block data and the reference screen block data necessary for the motion compensation prediction in the forward, backward, or both front and rear directions are read from the memory and the block matching operation is performed to generate the motion vector, various motion compensation predictions are performed. It is possible to flexibly deal with the system by changing the capacity of the external frame memory and the access method.

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

[Brief description of drawings]

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

[Fig. 4] 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 diagram showing an example (No. 1) of access order of the external frame memory by the motion compensation prediction device according to the present invention.

FIG. 7 is a time chart diagram showing an example (No. 2) of access order of the external frame memory by the motion compensation prediction device according to the present invention.

FIG. 8 is a time chart diagram showing an access sequence example (No. 3) of the external frame memory by the motion compensation prediction device according to the present invention.

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

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

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 the data bus is shared as shown in FIG.

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 calculation 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 Tsutomu Fujigo 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa, Fujitsu Limited (72) Inventor, Kiichi Matsuda 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (5)

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