JP2913896B2 - Video encoding device and video decoding 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 moving picture coding apparatus and a decoding apparatus, and more particularly to a moving picture coding apparatus which divides an input image into lattice-like blocks and performs irreversible coding and decoding processing for each block. And a decoding device.

[0002]

2. Description of the Related Art In a moving picture coding apparatus, data is processed by an irreversible coding process, and a data amount is reduced by giving the data a deformation that is hardly noticeable. For this reason, distortion is inevitably generated, and it is important how the distortion can be visually suppressed.

[0003] In a moving picture coding apparatus that divides a moving picture signal into blocks for each frame and performs irreversible coding processing for each block, there is no correlation between adjacent blocks in the degree of distortion due to irreversible coding processing. In addition, a portion where a discontinuous change not present in the original image occurs at a block boundary due to distortion occurs. The distortion generated at the boundary between blocks is called block distortion. In particular, in a moving picture encoding device that requires a high compression ratio, block distortion is easily noticeable and is a main cause of subjective image quality deterioration.

Conventionally, a spatial filter has been provided in a decoding apparatus in order to remove the block distortion. This is to suppress discontinuous changes of block boundaries by smoothing neighboring pixels of an image by a spatial filter.

FIG. 7 is a block diagram showing the configuration of a conventional moving picture coding apparatus and moving picture decoding apparatus.

[0006] The conventional moving picture coding apparatus and moving picture decoding apparatus are constituted by a moving picture coding apparatus 3 and a moving picture decoding apparatus 4 as shown in FIG. The video encoding device 3 includes an image input unit 31 and a block position generation unit 33
, A blocking unit 36, and an irreversible encoding unit 30. The video decoding device 4 includes an irreversible decoding unit 40, an inverse blocking unit 43, a block position generation unit 45, an image output unit 46, and a spatial filter 47.

Next, the operation of the conventional moving picture coding apparatus and moving picture decoding apparatus will be described.

[0008] The image input unit 31 of the moving picture coding apparatus 3
An input image signal A is input, and image data is temporarily stored.
Block position generating unit 33 then outputs the block position signal indicating the position of the reading blocks from the image input unit 31. The image input unit 31 outputs pixel data corresponding to the address according to the address signal input from the blocking unit 36. The blocking unit 36 receives the block position signal and calculates the address of the pixel data in the current block. And outputs the address to the image input unit 31, lossy coding unit 3 0 pixel data corresponding to the address
Output to Lossy coding unit 3 0 receives the pixel data of each block to generate coded data J performs lossy coding processing on pixel data.

The coded data J is input to the irreversible decoding unit 40 of the moving picture decoding apparatus 4 through a communication line. The irreversible decoding unit 40 receives the code data J and calculates restored pixel data for each block. The restored pixel data is output to the reverse blocking unit 43. Block position generator 45
Operates in the same manner as the block position generator 33 and outputs a block position signal. This block position signal is then:
The position of the restored pixel data output from the irreversible decoding unit 40 in the frame is shown. The reverse blocking unit 43 receives the restored pixel data for each block, and also receives a block position signal indicating the position of the block in the frame, and calculates the address of the pixel data in the image output unit 46. The address and the corresponding pixel data are output to the image output unit 46.
The image output unit 46 receives the address and the image data, and temporarily stores the pixel data at a location indicated by the address. The image output unit 46 outputs an image signal sequentially from a position where the pixel data is completed. The spatial filter 47 inputs an image signal,
Performs smoothing of neighboring pixels, and outputs the resulting image to the output image signal.
Output as signal Q. To give an example of a spatial filter,
There are the following.

[0010]

Here,

[0012]

[0013] is image data before filter processing,

[0014]

Is image data after the filtering process.

Also,

[0017]

The coefficient to be multiplied depends on the characteristics of the desired filter.

In the spatial filter processing, it is necessary to perform the above formula for all the pixels in the frame, and a lot of calculations are required. Also, as can be seen from the above equation, this spatial filter is the same as averaging by weighting the pixel data of neighboring pixels. That is, discontinuous change of pixel data at a block boundary is suppressed.

[0020]

In the conventional moving picture coding apparatus and moving picture decoding apparatus, the spatial filter suppresses not only discontinuous changes due to block distortion but also changes in pixel data included in the original image. Therefore, there is a disadvantage that an image is blurred. In addition, since the spatial filter processing requires a lot of calculations and requires real-time processing within one frame time, there is a disadvantage that hardware cost is high.

[0021]

A moving picture encoding apparatus and a moving picture decoding apparatus according to the present invention provide a moving picture signal for each frame.
And irreversible encoding is performed for each block.
A video encoding device unit for outputting encoded data by
Lossless decoding of encoded data for each block
Video decoding that outputs decoded and restored image data
And a moving picture decoding apparatus comprising the same.
In the encoding device, the video encoding device unit
An image input unit moving image signal Ru sequentially stored to <br/> be temporarily held one frame minutes, this for each frame of the moving image signal
A blocking unit that divides a moving image signal for one frame into blocks of a predetermined number of pixels;
Wherein for switching the position of the blocks for each frame
Set the offset value indicating the position of the block boundary .
And an offset setting unit for supplying the offset value.
And then the position of the block read from the image input unit.
A first block for outputting a block position signal instructing
A click position generator, in response to the supply of said block position signal
It is determined whether the current block being processed is an incomplete block over an edge of a moving image frame, and the current block to be determined is an incomplete block.
Activate the incomplete block decision signal when
A replenishment designation signal that mainly specifies the replenishment method for incomplete blocks
A boundary block decision unit that outputs the partial block
When the signal is deactivated, it responds to the supply of the block position signal.
Calculate the address of the pixel data in the current block in response
To access the image input unit, and
First block pixel corresponding to receiving supply of pixel data
And the blocking unit for outputting data, the incomplete block
Upon activation of the click determination signal, the incomplete to complete the block by block replenish predetermined <br/> pixel data, the current blanking in response to the supply of the replenishing designation signal
Calculate the address of pixel data in the frame within the lock
Used for refilling pixels outside the frame
Calculate the address of the pixel data and activate the image input unit.
Sesushi receives supply of addresses corresponding pixel data
An incomplete block replenishment unit for outputting corresponding second block pixel data, and the first or second block pixel data.
And a non-reversible encoding unit that generates a motion image encoded data do not lossless encoding process for each of the blocks in response to the supply of over data, the moving image decoding device unit, the moving image coding
Coded data is supplied and the video encoded data
Restores the pixel data of the block to be removed and restores the pixel data
A lossy decoding unit for outputting the motion image encoded data
To switch the position of the block every frame
Set an offset value indicating the position of the block boundary
A second offset setting unit for supplying the offset value
In the frame of the block of the restored pixel data in response to
Output a block position signal indicating the position at
And the block position generator, the instructions before Symbol block position signal
Responsively restores the restored pixel data in the block to a moving image
Reverse block mapping to a predetermined position in the frame
A locking unit and the restored pixel data of the frame.
And an image output unit for storing and holding and outputting as a restored image signal .

[0022]

[0023]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a moving picture coding apparatus and a moving picture decoding apparatus according to the present invention.

This embodiment comprises a moving picture coding apparatus 1 and a moving picture decoding apparatus 2 as shown in FIG.
The moving image encoding apparatus 1 includes an image input unit 11, an offset setting unit 12, a block position generating unit 13, a boundary block determining unit 14, an incomplete block supplementing unit 15, a blocking unit 16, an information source code And an irreversible encoding unit 10 composed of an encoding unit 17 and a variable-length encoding unit 18.

The moving picture decoding apparatus 2 comprises a variable length decoding unit 2
1 and an information source decoding unit 22, an irreversible decoding unit 20, an inverse blocking unit 23, an offset setting unit 24, a block position generating unit 25, and an image output unit 26. I have.

Next, the operation of this embodiment will be described.

In this embodiment, discrete cosine transform (hereinafter referred to as DC) is performed as information source encoding processing and information source decoding processing.
T) is used. One block is processed as eight pixels in the vertical direction and eight pixels in the horizontal direction, that is, 8 × 8 pixels.

First, the image input unit 11 of the moving picture coding apparatus 1
Receives an input moving image signal A and temporarily stores pixel data. The offset setting unit 21 sets an offset value B indicating the position of a block boundary for each frame in the block position generating unit 1.
Output to 3. The block position generator 13 outputs a block position signal C indicating the position of the block to be read next from the image input unit 11. The boundary block determination unit 14 receives the block position signal C, determines whether the block is an incomplete block, and outputs an incomplete block determination signal D. When the block to be determined is an incomplete block, the boundary block determination unit 14 outputs a replenishment designation signal E indicating a replenishment method to the incomplete block replenishment unit 15. The image input unit 11 responds to an address signal F input from the incomplete block replenishment unit 15 and the blocking unit 16
The pixel data G corresponding to the address F is output. The blocking unit 16 receives the incomplete block determination signal D and operates when the block to be determined is not an incomplete block. When the block to be determined is not an incomplete block, the blocking unit 16 receives the block position signal C and calculates the address of the pixel data in the current block. Next, the calculated address is output to the image input unit 11 as an address signal F, and pixel data G corresponding to the address is input. The pixel data G is output to the information source coding unit 17 as pixel data H.

The incomplete block replenishment unit 15 receives the incomplete block determination signal D and operates as follows when the block to be determined is an incomplete block. That is, the replenishment designation signal E is input, and the address of the pixel data is calculated for the pixels in the frame in the current block. For pixels outside the frame, the address of pixel data used for replenishment is calculated. Next, the calculated address is output to the image input unit 11 as an address signal F, and pixel data G corresponding to the address is input. The pixel data G is output to the information source coding unit 17 as pixel data H. The information source coding unit 17 receives the pixel data G for each block, performs DCT on the pixel data, and quantizes the obtained DCT transform coefficient to calculate a quantized DCT coefficient. The quantized DCT coefficient I is output to the variable length coding unit 18. The variable length coding unit 18 receives the quantized DCT coefficient I, allocates a variable length code corresponding to the data,
The code data J is output.

The code data J is input to the variable length decoding unit 21 of the video decoding device 2 through a communication line or the like. The variable length decoding unit 21 extracts a variable length code from the input code data J and restores the corresponding quantized DCT coefficient. The quantized DCT coefficient K is output to the information source decoding unit 22. The information source decoding unit 22 calculates the quantized DCT coefficient K
, And the data is inversely quantized to obtain a DCT transform coefficient, and the DCT transform coefficient is inversely DCTed to calculate restored pixel data L for each block. The restored pixel data L is output to the reverse blocking unit 23.

The offset setting section 24 and the block position generating section 25 are provided with the offset setting section 12 of the moving picture coding apparatus 1.
It operates in the same manner as the block position generator 13 and outputs an offset position O and a block position signal P, respectively. The block position signal P indicates the position in the frame of the block of the restored pixel data output from the information source decoding unit 22 at that time. The reverse blocking unit 23 receives the restored pixel data L for each block and a block position signal P indicating the position of the block in the frame. The reverse blocking unit 23 calculates coordinates indicating the position of the pixel in the block from the input block position signal P. Next, when the coordinates indicate a pixel in the frame, an address of the pixel in the image output unit 26 is calculated, and the calculated address and the corresponding pixel data are output as an address signal M and pixel data N. Output to the unit 26. When the coordinates do not indicate a pixel in the frame, the output to the image output unit 26 is not performed.

The image output unit 26 receives the address signal M and the pixel data N, and temporarily stores the pixel data at the location indicated by the address. The image output unit 26 outputs the image signal Q sequentially from the place where the pixel data is arranged.

In this embodiment, two patterns shown in FIGS. 2A and 2B are prepared as the positions of the block boundaries, and are changed in the order of (A) and (B) for each frame. The switching of the block boundary position is performed by the offset setting unit 12 in which the offset value B indicating the position of the first block of the frame is set for each frame.
3 is performed.

FIGS. 3A to 3C show a method of supplementing pixels of an incomplete block in this embodiment.

The two-dimensional DCT of an 8 × 8 pixel block is
It is represented by the following equation.

[0037]

In the block in which the vertical line of the frame is axisymmetrically added as shown in FIG. 3 (A), F (u, v) = 0 (u: odd number) and half of the DCT coefficient due to the nature of the cosine function. Becomes 0.

Similarly, as shown in FIG. 3 (B), the block supplemented to the axis line on the horizontal line of the frame has F (u, v) = 0 (v: odd number) due to the nature of the cosine function, and the DCT Half of the coefficient is 0.

Similarly, the block supplemented as shown in FIG. 3 (C) has F (u, v) = 0 (u: odd number or v: odd number) due to the nature of the cosine function, and is a quarter of the DCT coefficient. 3 becomes 0.

Next, a second embodiment of the present invention will be described with reference to FIGS.

This embodiment is different from the first embodiment in that four patterns shown in FIGS. 4A to 4D are prepared as the positions of the block boundaries, and (A) and (B) are prepared for each frame. ,
(C) and (D).

The pixel replacement method for the incomplete block in the case of FIG. 4B is the same as that of the first embodiment.

The pixel replenishment method of the incomplete block in FIGS. 4C and 4D is performed as shown in FIGS. 5A to 5E.

The block supplemented as shown in FIG. 5 (A) has F (u, v) = 0 (u = 1,2,3,5,6,7) due to the nature of the cosine function, and the DCT coefficient Three quarters is zero.

FIG. 5 (C) The blocks replenished like NC are:
From the nature of the cosine function, F (u, v) = 0 (u = 1,2,3,5,6,7 or v
= 1, 2, 3, 5, 6, 7), and 15/16 of the DCT coefficient becomes 0.

Next, a third embodiment of the present invention will be described with reference to FIG.

The difference between the present embodiment and the first embodiment is that the method of supplementing the pixel data of the incomplete block is different. Reverse blocking unit 2 of video decoding device 2
The third process is different from that of the first embodiment.

The area surrounded by the dotted line in FIG. 6 indicates an area covered by a block (hereinafter, referred to as a block area). The hatched portion represents an area that extends outside the frame of the block area. In this embodiment, the hatched portions are supplemented by pixel data of pixels outside the block area of the frame. The pixel used for replenishment is determined by the following equation.

[0050]

Here, (x, y) is the coordinates of the pixel in the shaded area.

[0052]

(Xmin, ymin) is the coordinates of the pixel at the upper left corner of the frame, and (xmax, ymax) is the coordinates of the pixel at the lower right corner of the frame.

When the current block is a complete block, the incomplete block replenishment unit 15 calculates the address of the pixel data for the pixels in the frame in the current block. For pixels outside the frame, the address of the pixel data used for replenishment determined by the above rule is calculated.
Next, the calculated address is output to the image input unit 11 as an address signal F, and pixel data G corresponding to the address is input. The pixel data G is transmitted to the information source coding unit 17.
Is output as pixel data H.

The inverse blocking section 23 calculates the coordinates of the pixels in the block from the block position signal P input from the block position generating section 25. When the coordinates indicate a pixel in the frame, the address of the pixel is calculated. When the coordinates indicate a pixel outside the frame, the address of the pixel used for replenishment is calculated, and the calculated address is used as an address signal M. Output to the image output unit 26.

[0056]

As described above, the moving picture coding apparatus and the moving picture decoding apparatus of the present invention change the position of the block distortion for each frame, so that the block distortion is inconspicuous and visually good. This has the effect of obtaining a proper reproduced image.
Further, since no spatial filter is used, there is an effect that blurring of an image does not occur. Further, there is an effect that hardware cost for realizing the spatial filter is unnecessary and the cost is low.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a moving picture coding apparatus and a moving picture decoding apparatus according to the present invention.

FIG. 2 is a diagram illustrating a method of dividing a block in a moving image encoding device and a moving image decoding device according to the present embodiment.

FIG. 3 is a diagram illustrating a method of supplementing an incomplete block in the video encoding device and the video decoding device of the present embodiment.

FIG. 4 is a diagram illustrating a block dividing method according to a second embodiment.

FIG. 5 is a diagram showing a method of replenishing incomplete blocks in the second embodiment.

FIG. 6 is a diagram showing a method for replenishing incomplete blocks in a third embodiment.

FIG. 7 is a block diagram illustrating an example of a conventional video encoding device and a conventional video decoding device.

[Explanation of symbols]

 1,3 moving picture coding device 2,4 moving picture decoding device 10,30 irreversible coding unit 11,31 image input unit 12,24 offset setting unit 13,25,33,45 block position generating unit 14 boundary block judgment Unit 15 Incomplete block supplementing unit 16, 36 Blocking unit 17 Information source coding unit 18 Variable length coding unit 20, 40 Irreversible decoding unit 21 Variable length decoding unit 22 Information source decoding unit 23, 43 Reverse blocking unit 26 , 46 Image output unit 47 Spatial filter

Claims (5)

(57) [Claims] (1)Video signal is divided into blocks for each frame
Divide and perform irreversible encoding for each block to encode
A video encoding unit for outputting a data,
The encoded data is decoded by irreversible
From the video decoding unit that outputs the original image data
The moving picture coding apparatus and the moving picture decoding apparatus
And The video encoding device unit receives One video signal
Lame minutesStore sequentially and hold temporarilyAn image input unit to perform, for one frame of the moving image signaleveryToFor this one frame
Video signalA block that is divided into blocks of a predetermined number of pixels
A locking unit, for one frame of the video signaleveryThe position of the block
To switchIndicates the position of the block boundaryOffice
Set the cut valueFirstAn offset setting section,In response to the supply of the offset value,
Block position indicating the position of the block to be read from
A first block position generator for outputting a signal; In response to the supply of the block position signal Before currently being processed
The current block is the edge of the frame of the video
Determine if the block is an incomplete blockAnd judge
Incomplete if the current block of interest is an incomplete block
Activate all block judgment signals and incomplete block
Outputs a replenishment designation signal that specifies the replenishment methodBoundary
A lock determination unit;When the incomplete block signal is deactivated, the block
The pixel data in the current block is responsive to the supply of the position signal.
Access to the image input unit by calculating the address of the
Receiving the pixel data corresponding to this address and responding
Blocking unit that outputs first block pixel data
When, SaidWhen the incomplete block determination signal is activated,incomplete
On the blockPredeterminedBy supplementing the pixel data
In order to complete the block,
pls respondOf pixel data in a frame in the current block
Calculate the address and address pixels outside the frame.
Calculate the address of the pixel data used for replenishment
The image input unit is accessed and the pixel data corresponding to these addresses is accessed.
Data corresponding to the second block pixel data
OutputAn incomplete block replenishing unit;In response to the supply of the first or second block pixel data
handThe blockeveryToUnfortunatePerforms lossless encoding and performs video coding
Generate encrypted dataUnfortunateWith a lossless encoding unit, The video decoding device unit is configured to transmit the encoded video data.
Supplied, and from this encoded video data,
Restore the locked pixel data and output the restored pixel data
An irreversible decoding unit; The block is provided every frame of the encoded video data.
Indicate the position of the block boundary to switch the position of the block.
A second offset setting unit for setting an offset value; ,Before the restoration pixel data in response to the supply of the offset value
Block position indicating the position of the block in the frame
A second block position generator for outputting a position signal; PreviousIn response to the instruction of the block position signal,
Of the restored pixel data of a moving image frame
A reverse blocking unit that maps to Store and hold the restored pixel data of the frame and restore
An image output unit that outputs the image signal. Specially
Moving picture coding deviceAnd a video decoding device. Wherein said partial block refill unit, as well as replenishing the pixel data so as to be axisymmetric with respect to the edges of the frame, the non-reversible encoding unit, wherein using discrete cosine transform non 2. The moving picture coding apparatus and moving picture decoding according to claim 1, wherein lossless coding processing is performed.
Device . Wherein the partial block replenishment unit, an incomplete block according to the left edge of the frame and replacement by the pixel data of the defective block according to the right edge of the frame, according to the upper edge of the frame not The complete block is supplemented with the pixel data of the incomplete block on the lower edge of the frame to complete the block, and the incomplete block on the upper and lower edges of the frame is not encoded. Item 3. The video encoding device and the video decoding device according to Item 1. 4. The moving image according to claim 1 , wherein the reverse blocking unit discards the pixel data outside the frame in an incomplete block on the edge of the frame and does not output the pixel data to the image output unit. An image encoding device and a moving image decoding device. 5. The inverse blocking unit maps, for an incomplete block on the left edge of the frame, the pixel data of a portion protruding from the left edge as the pixel data on the right edge of the frame, 2. The moving image according to claim 1, wherein, for an incomplete block on an upper edge of the frame, the pixel data of a portion protruding from the upper edge is mapped as the pixel data on a lower edge of the frame. 3. An encoding device and a moving image decoding device.