JP2712646B2 - Video signal encoding device and video signal encoding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial application field B Outline of the invention C Conventional technology (Figs. 5 to 8) D Problems to be solved by the invention (Figs. 5 to 8) E Means for solving problems (Figs. 1 to 4) F action (Figs. 1 to 4) G Example (Figs. 1 to 4) (G1) First embodiment (Figs. 1 to 3) (G2 (2) Second Embodiment (FIG. 4) (G3) Other Embodiments H Effects of the Invention A Industrial Field of the Invention The present invention relates to a video signal encoding device and a video signal encoding method, and in particular, to a high efficiency encoding of a video signal. This is suitable for application when performing conversion processing into coded data.

B. Summary of the Invention The present invention relates to a video signal encoding apparatus and a video signal encoding method, wherein a quantization step is controlled in accordance with a change in relative image information of an encoded sub-region and an adjacent sub-region. By doing so, it is possible to generate transmission data in which the image of the changed portion is clearer.

C Conventional technology Conventionally, intra-frame coded data and inter-frame coded data obtained by efficiently coding a video signal composed of a moving image are
2. Description of the Related Art A video signal recording apparatus has been proposed in which a recording is performed on a recording medium such as a CD (compact disk) and the recorded data can be searched as needed.

This high-efficiency encoding process is performed, for example, at time t = t ₁ , t ₂ , t ₃ ... As shown in FIG.
1, when PC2, PC3 ... are digitally encoded and transmitted to a transmission system composed of, for example, a CD recording device, the digital data to be transmitted is compressed using the fact that the video signal has a large autocorrelation. In order to improve the transmission efficiency, the intra-frame encoding process involves, for example, adjoining the images PC1, PC2, PC3... One-dimensionally or two-dimensionally along the horizontal scanning line direction. Performs compression processing to find the difference between pixel data, and thus each image PC1, PC
2. Transmit the image data of the number of compressed bits for PC3.

In addition, the inter-frame encoding process obtains image data PC12, PC23,..., Which are differences of pixel data between adjacent images PC1, PC2, PC2, PC3,... Sequentially as shown in FIG. This for the initial image PC1 at the time t = t ₁ transmitting with intraframe coded processed image data.

Thus, the images PC1, PC2, PC3,... Can be highly efficiently coded into digital data having a significantly smaller number of bits as compared with the case where all the pixel data are transmitted, and transmitted to the transmission system.

Such a video signal encoding process is executed in the image data generating device 1 having the configuration shown in FIG.

Image data generating apparatus 1 is temporarily stored in the transmission buffer memory 3 by quantizing the video signal VD to a high-efficiency encoded data D _VD in the video signal encoding circuit unit 2, the high efficiency encoding, which is temporarily stored in the transmission buffer memory 3 reads the data D _VD as transmission data D _TRANS at a predetermined transmission speed, is adapted to transmit the image data recording and reproducing apparatus 5 composed of, for example, CD recording and reproducing apparatus via the transmission path 4 constituting the transmission system.

Here, the transmission buffer memory 3 transmits the transmission data D _TRANS at a transmission speed determined by the transmission capacity of the transmission path 4 to the image data recording / reproducing device 5 and, at the same time, the remaining data indicating the amount of data remaining in the transmission buffer memory 3. Signal D _RM
Is fed back to the video signal encoding circuit unit 2 via the feedback loop 6 so that the quantization step STEPG (the sixth step) when digitally encoding the video signal VD is performed.
By controlling the drawing) to control the amount of generated data of the high-efficiency encoded data D _VD supplied to the transmission buffer memory 3, thereby overflowing the data held in the transmission buffer memory 3, or so as not to underflow Control.

As shown in FIG. 7, the video signal encoding circuit unit 2 receives the video signal VD in the pre-processing unit 11, converts the luminance signal and the chroma signal into digital data, and then performs one field drop processing and one field line thinning. The data is converted into moving image data by performing processing and the like, and is converted into transmission unit block data S11 of 16 pixels (in the horizontal direction) × 16 lines of data (ie, data of 16 pixels × 16 pixels). And stores it in the current frame memory 12.

Thus, the current frame memory 12 holds the frame image data of the frame to be transmitted at present, and this is supplied to the addition input terminal of the subtraction circuit 13 as the current frame data S12.

The previous frame data S13 obtained from the previous frame memory 14 is given to the subtraction circuit 13 as a subtraction input, whereby the transmission unit block data of the current frame image data and the previous frame image data are output to the output terminal of the subtraction circuit 13. Deviation data S14 representing a deviation from the transmission unit block data is sequentially output, and this is output to a conversion coding circuit 15 such as a discrete cosine conversion circuit.
After conversion to S15, quantization is performed by the quantization circuit 16.

The quantized data S16 thus obtained from the quantizing circuit 16
Is again efficiently coded by the variable length coding circuit 17,
After the variable length coded data S17 is combined with the first and second management information S18 and S19 in the combining circuit 18, it is supplied to the transmission buffer memory 3 as transmission image data S20.

In addition to this, the quantized data S16 is inversely transformed in an inverse transform circuit 19 including an inverse quantizer and an inverse transform encoder, and is stored as decoded deviation data S21 in a previous frame memory 14 through an adder 20. Thus, the image data of the current frame sent to the buffer memory 3 is stored in the previous frame memory 14 as the previous frame image data.

On the other hand, the current frame data S12 of the current frame memory 12 is
The motion data is supplied to the motion compensating circuit 21 together with the previous frame data S22 of the previous frame memory 14, and the current frame data is compared with the previous frame data. With respect to the transmission unit block of the image portion, motion vector data S23 representing the motion vector is formed and supplied to the previous frame memory 14. At the same time, the motion vector data S23 is supplied to the decoding circuit 18 as the first management information S18, so that it is sent to the transmission buffer memory 3 as a part of the header information of the data corresponding to the deviation data S14.

Also, quantization step data S24 representing the quantization step STEPG used in the quantization processing in the quantization circuit 16
Is supplied to the variable-length encoding circuit 17 as a variable-length condition signal, and is also supplied to the decoding circuit 18 as second management information S19, and this is transmitted as a part of header information added to the data of the deviation data S14. It is compounded into data S20.

According to the above configuration, when attempting to transmit a fourth view image data PC1 at the time t ₁ of (A) as intraframe coded data, "0 as the frame data S13 before it is supplied to the subtraction circuit 13 Data (representing a blank image), whereby the current frame data S12 to be transmitted at present is supplied as it is to the conversion encoding circuit 15 as the deviation data S14 through the subtraction circuit 13.

At this time, the transform encoding circuit 15 sends the transformed encoded data S15 obtained by intra-frame encoding to the quantizing circuit 16, whereby the intra-frame encoded data is converted to the variable length encoded circuit.
17. At the same time as the transmission image data S20 is transmitted to the transmission buffer memory 3 through the decoding circuit 18, the deviation data S14, and thus the current frame data S12, is decoded by the inverse conversion circuit 19 into the decoded deviation data S21, It is stored in the frame memory 14.

Thus after the image data PC1 is transmitted as intraframe coded data, the image data PC2 at time t ₂ is the timing to be supplied to the subtraction circuit 13 as the current frame data S12, the image data of the previous frame from the previous frame memory 14 The image data PC1 is supplied to the subtraction circuit 13, and as a result, the subtraction circuit 13 outputs the image data PC1 representing the deviation between the image data PC2 given as the current frame data S12 and the image data PC1 given as the previous frame data S13.
The deviation data S14 corresponding to 2 (FIG. 4 (B)) is obtained as difference data constituting the inter-frame coded data.

This deviation data S14 is converted to a transform coding circuit 15, a quantization circuit 1
6, the variable length coding circuit 17 and the compounding circuit 18
Is transmitted to the transmission buffer memory 3 as transmission image data S20, and is also decoded by the inverse conversion circuit 19 and supplied to the addition circuit 20 as decoded deviation data S21.

At this time, the adder circuit 20 moves the difference data represented by the decoded deviation data S21 with respect to the image data PC1 of the previous frame held in the previous frame memory 14 by the motion vector data S23 obtained from the motion compensation circuit 21. The data is predicted based on the previous frame data, and is stored in the previous frame memory.

At this time, the motion compensating circuit 21 sends the previous frame image data PC1 held in the previous frame memory 14 and the motion vector data S23 representing the motion of the image data arriving as the current frame data S12. In step (2), the result of addition of the decoded deviation data S21 and the previous frame image data is stored in the vector position represented by the motion vector data S23, and the motion vector data S23 is transmitted to the transmission image data S
Send out as 20.

Thus the video signal coding circuit 2, t = t ₂ (FIG. 4 (A)) image data PC2 per transmitting, as inter-coded data, the image data of the current frame and image data PC1 of the previous frame of Image data P representing the difference from PC2
C12 is highly efficiently coded into inter-frame coded data including deviation data S14 and motion vector data S23, and supplied to the transmission buffer memory 3.

Similarly, when new image data arrives as the current frame data S12 at time points t ₃ , t _4, ..., The image data of the previous frame (that is, the previous frame data S 13) held in the previous frame memory 14 is used. The current frame data S12 can be efficiently coded as inter-frame coded data and transmitted to the transmission buffer memory 3.

The transmission buffer memory 3, which has received the transmission image data S20 sent out in this manner, sequentially stores the transmission image data S20 temporarily stored therein at a predetermined data transmission speed determined by the transmission capacity of the transmission line 4 in the transmission data D. _The data is read out as _TRANS and transmitted to the image data recording / reproducing apparatus 5. At this time, the remaining data signal S25 indicating the amount of data remaining inside is fed back to the quantization circuit 16 as a quantization step control signal. The data generation amount supplied as the transmission image data S20 from the video signal encoding circuit unit 2 is controlled.

If the remaining amount of data in the transmission buffer memory 3 has increased to the permissible upper limit, if the remaining amount is left unchecked, the transmission buffer memory 3 may overflow the data amount that can be stored. By controlling the quantization step STEPG of the quantization circuit 16 to be changed to a large value in accordance with the remaining data signal S25, the data generation amount of the quantization data S16 with respect to the deviation data S14 is reduced, whereby the transmission image is transmitted. The data amount of the data S20 is reduced, and as a result, the occurrence of overflow is avoided.

Conversely, when the remaining data is reduced to the permissible lower limit, the transmission buffer memory 3 may cause an underflow if left unchecked.
5, the quantization step STEPG of the quantization circuit 16 is controlled to a small value, thereby increasing the data generation amount of the quantization data S16 with respect to the deviation data S14, thereby increasing the data amount of the transmission image data S20. As a result, the occurrence of underflow in the transmission buffer memory 3 is avoided.

D Problems to be Solved by the Invention As described above, the conventional image data generating apparatus 1 significantly reduces the data transmission speed of the transmission data D _TRANS while matching the data transmission speed to the transmission condition limited based on the transmission capacity of the transmission path 4. As means for transmitting image information, the quantization step STEPG is controlled by paying attention to the fact that the remaining amount of data in the transmission buffer memory 3 may always be maintained so as not to cause overflow or underflow. Therefore, depending on the contents of the image data to be transmitted, the image quality of the generated image data may be degraded.

For example, in a case where a static region and a changing region are mixed as an image, an image in which image information rapidly changes, such as an image of an edge of a moving object, etc., is provided at a boundary portion between the static region and the changing region. When the quantization step STEPG is controlled such that the remaining amount of data in the transmission buffer memory 3 falls within a predetermined range as in the conventional case, the image information changes rapidly. There is a possibility that noise is generated in an image portion such as a portion.

In general, human visibility to a moving image is low in a region where image information changes (that is, a region where there is movement) and high in a static region of image information (that is, a region where there is no movement). Therefore, in the case where the static region and the changing region coexist in this way, the image quality of the data generated in the visual characteristics can be reduced even if the quantization step STEPG used for quantizing the changing region is increased. It is considered that deterioration can be prevented, and the quantization efficiency can be increased accordingly.

However, in practice, when the quantization step STEPG for the change area is increased and coarse quantization is performed as described above, in the generated data, a boundary image portion where image information rapidly changes between the change area and the still area is quantized. In this case, there is a possibility that noise is generated in the boundary image portion.

Such a phenomenon may occur at a boundary portion between a plurality of regions having different movements even in a change region.

The present invention has been made in consideration of the above points, and is intended to prevent deterioration in image quality of a boundary portion in a case where a single image includes a plurality of areas where image information relatively changes. And a video signal encoding method.

E Means for Solving the Problems In order to solve such problems, the first invention is directed to a video signal encoding device 2 and a method for encoding a digital video signal S14 with high efficiency. reduction step STEPG quantized on the basis of the adjacent image regions RG adjacent to the coded image region RGS ₀ to be transmitted
S _A, RGS _B, stillness data W representing the degree of change in the image information _{(W A, W B, W} C) to occur for RGS _C, stillness data W _{(W A, W B, W} C) quantization step STEPG based size of the to the motion data representing the movement of the coded picture area RGS ₀
Control the value of.

The second invention also provides a video signal encoding device 2 and a video signal encoding method for highly efficiently encoding a digital video signal S14, wherein the digital video signal S14 is quantized based on a quantization step STEPG to generate transmission data S16, An adjacent image area RG adjacent to the encoded image area RGS ₀ to be transmitted
S _A, RGS _B, stillness data W representing the degree of change in the image information _{(W A, W B, W} C) to occur for RGS _C, stillness data W _{(W A, W B, W} C) calculated conversion rate data rATIO based size of the to the motion data representing the movement of the coded picture area RGS _0, representing the remaining data amount of the transmission buffer memory 3 for temporarily storing transmission data S16 and the conversion rate data rATIO The value of the quantization step STEPG is controlled based on the remaining amount data.

F Action Stillness Data W for Encoded Image Region RGS _{0
(W A, W B, W} C) and the motion data of the encoded image area RGS ₀ indicates whether there is a boundary of the image in the position of the encoded image area RGS _0.

Accordingly, the quantization step STEPG is controlled based on the stillness data W (W _A , W _B , W _C ) of the adjacent image areas RGS _A , RGS _B , and RGS _C and the motion data of the coded image area RGS _0. Since the fine quantization can be performed on the boundary of the image, the image quality of the transmission data can be improved by this amount.

In addition, the conversion rate data RATIO is obtained based on the stillness data and the motion data, and thereby the value of the quantization step STEPG can be controlled, so that the quantization step can be easily controlled with a simple configuration. can do.

G Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

(G1) First Embodiment In FIG. 1 in which parts corresponding to those in FIG. 8 are denoted by the same reference numerals, the quantization circuit 16 uses a quantization step control signal S31 supplied from a data control circuit 31 to perform a quantization step S31.
TEPG controlled.

The data control circuit 31 transmits the transmission data information S33 given from the motion compensation circuit 21 and the remaining data signal S of the buffer memory 3.
25, the quantization step STEPG is calculated in accordance with the quantization step calculation processing procedure shown in FIG. 2, and this is sent out as the quantization step control signal S31.

In the quantization step calculation processing procedure shown in FIGS. 2A and 2B, the data control circuit 31 operates as shown in FIG.
The image of the frame is used as the main area RGM, and the main area RGM is
Sub-region RG consisting of transmission unit blocks of 16 pixels x 16 pixels
Each pixel data DATA constituting the significant image information of the sub-region RGS is quantized into transmission data.

That is, when the data control circuit 31 enters the quantization step calculation processing procedure in step SP1, it proceeds to step SP2.
The feedback buffer quantization step ST determined by the remaining data of the transmission buffer memory 3 allows the transmission buffer memory 3 to be known based on the remaining data signal S25.
EP _BF and all pixel data DATA in the sub-region to be encoded RGS _0
i (i = 0 to 255), and then step SP
At 3, it is determined whether or not all the pixel data DATA _i (i = 0 to 255) is smaller than the feedback quantization step STEP _BF .

If a positive result is obtained here, this means that the significant image information (for example, difference data between the previous frame and the current frame) of the main region RGM constituting the current frame, that is, the current frame, is substantially a numerical value “ It is in the state of "0" level, and thus represents no motion.

At this time, the data control circuit 31 proceeds to step SP4 and performs a feedback quantization step STEP _FB as a quantization step.
After the replacement with STEPG, the quantization step STEPG is sent to the quantization circuit 16 in step SP5.

Thus, the data control circuit 31 terminates the quantization step calculation processing procedure in step SP6.

When the data control circuit 31 is in such a state as to execute such processing, the transform coded signal S15 actually supplied from the transform coding circuit 15 to the quantization circuit 16 has no significant image information to be transmitted. As a result, the quantization circuit 16 sends the data of the numerical value "0" as the quantized data S16 due to being at the numerical value "0" level or the noise level, and is controlled to generate no data to be transmitted after all. You.

On the other hand, if a negative result is obtained in step SP3, this means that there is significant image information to be transmitted in any of the sub-regions RGS. At this time, the data control circuit 31 proceeds to step SP7 and Regarding the coded sub-region RGS ₀ having the significant image information (FIG. 3), the process starts to calculate the quantization step STEPG used when quantizing this.

Here quantization step STEPG for the coded sub-region RGS its value in relation to the significant image information of the adjacent sub-area adjacent to the target encoding subregion RGS ₀ is determined.

That data control circuit 31 step against the coded sub-region RGS ₀ in SP7, before along connexion one in the H direction (i.e. the horizontal scanning direction) adjacent sub areas RGS _A (FIG. 3)
It is determined whether or not the significant image information is still (i.e., whether there is a change compared to the image information of the adjacent sub-region RGS _A in the previous frame).

If a negative result is obtained here, this means that some movement has occurred in the adjacent sub-region RGS _A , and at this time, the data control circuit 31 proceeds to step SP8 and
Proceeding to the next step SP9 after setting the still-rate data W _A for the GS _A to the value "0".

When an affirmative result in step SP7 contrast is obtained, the data control circuit 31 the next step SP9 after setting the static rate data W _A numeric "3" in step SP10
Move on to

In this step SP9, the data control circuit 31 determines the significant image information of the immediately preceding adjacent sub-region RGS _B (FIG. 3) adjacent to the encoded sub-region RGS ₀ in the V direction (ie, the vertical scanning direction). It is determined whether or not the stationary frame is in the stationary state as compared with the previous frame. If a negative result is obtained, the stationary state data W _B of the adjacent sub-region RGS _B is obtained in step SP11.
Then, the process proceeds to the next step SP12. Following step after the data control circuit 31 which sets the numerical value "2" as still rate data W ₂ in step SP13 when a positive result is obtained for which the step SP9
Move to SP12.

In this step SP12, the data control circuit 31 sets the adjacent sub-region RGS _B adjacent in the H direction (ie, the horizontal scanning direction).
To the next adjacent sub-region RGS _C (encoded sub-region
(Adjacent to RGS _{0 in the} upper right direction)
For determining whether or not the change significantly the image information has occurred, the next after setting the numerical value "0" as the still index data W _C in step SP14 when a negative result is obtained step
Move to SP15. On the other hand, when a positive result is obtained in step SP12, the static ratio data W _C is obtained in step SP16.
After setting the numerical value “1” to the next step, the process proceeds to the next step SP15.

Thus, the data control circuit 31 detects the change in the image information of the significant image information of the adjacent sub-regions RGS _A , RGS _B, and RGS _C adjacent to the coded sub-region RGS ₀ during steps SP7 to SP15. When there is no change, weighting of the numerical value “0” is given as the static ratio data W _A , W _B , and W _C , whereas when there is a change, the static data W _A , W _B , and W _C
The following equation W _A = 3 (1) W _B = 2 (2) W _C = 1 (3) Weighting of numerical values “3”, “2” and “1” give.

Step SP10, the weighting process in SP13 and SP16 represent the degree of its rest state gives significantly image information of the coded sub-region RGS ₀ effects when adjacent subregions RGS _A, RGS _B and RGS _C are stationary ing.

That gave the weights of the numerical value "3" in step SP10 for the still index data W _A adjacent subregion RGS _A is
This means that a change in relative image information between the coded sub-region RGS _{0 in the} H direction is to be obtained from significant image information of one adjacent sub-region RGS _A.

Give the weight of adjacent sub-regions RGS _B and stationary rate data W numerical _B and W _C corresponding to RGS _C "2" and "1" is adjacent to the V direction in step SP13 and SP16 contrast, the 1, the significant image information that affects the significant image information of the encoded sub-region RGS ₀ in the V direction includes adjacent sub-regions RGS _B and
Is a significant image information of RGS _C, effect of these two adjacent sub-regions RGS receives from the entire _B and RGS _C may be considered to be substantially equal to the influence from the horizontal neighboring sub-regions RGS _A,
Accordance connexion value of the sum of the static rate data W _B and W _C (i.e. the value "2" + "1" = "3") selected such becomes equal to the value of the static rate data W _A (i.e. numerical value "3") did.

Secondly, the distance between the encoded sub-region RGS ₀ and the adjacent sub-regions RGS _B and RGS _C is smaller than that of the adjacent sub-region RGS _C because the adjacent sub-region RGS _B is shorter.
It can be considered that RGS _B is larger, and therefore weights “2” and “1” are given to the adjacent sub-regions RGS _B and RGS _{C in the} V direction.

After completing this processing, the data control circuit 31 proceeds to step
In SP15, the stationary ratio data W _A , W _B, and W _C of the adjacent sub-regions RGS _A , RGS _B, and RGS _C are represented by the following equation: W = W _A + W _B + W _{C. a,} W _B and W _C addition to the coding of three for subregions RGS ₀ neighboring subregion RGS _a, RG
Stillness ratio data W representing the overall degree of influence from S _B and RGS _C is obtained.

Subsequently, the data control circuit 31 enters a process of calculating the feedback quantization step conversion rate data RATIO based on the static rate data W.

That data control circuit 31 is larger still rate data W is 3 determines whether or not at step SP17, a positive result is motion vector shifting connexion the coded sub-region RGS ₀ to step SP18 when the obtained "0 Is determined.

If a negative result is obtained here, this means that while the significant image information of the adjacent sub-regions RGS _A , RGS _B and RGS _C does not change or is small, the motion of the image in the encoded sub-region RGS ₀ is small. There, indicates that the change in the image occurs at the position of the sub connexion the coded sub-region RGS _0.

At this time, the data control circuit 31 sets the largest numerical value "1.8" as the feedback quantization step conversion rate data RATIO in step SP19, and then, in step SP20, As described above, the value obtained by dividing the feedback quantization step STEP _FB by the feedback quantization step conversion rate data RATIO is calculated as the quantization step STEPG.

The data control circuit 31 outputs the quantization step STEPG calculated in this way to the quantization circuit 16 in step SP21 as the quantization control signal S31, and then ends the quantization step calculation processing procedure in step SP22.

By quantizing a result quantization circuit 16 using a quantization step STEPG the smallest numerical boundaries of the image in the coded sub-region RGS _0, by more finely quantized image information of the boundary It is possible to quantize an image of a boundary portion that is conspicuous to transmission data with higher image quality.

On the other hand, if a positive result is obtained in step SP18, this means that the change in the significant image information of the adjacent sub-regions RGS _A , RGS _B and RGS _C is "0" or small, whereas the coding is not performed. means that the image of the state in which there is no motion in the sub-region RGS ₀ has occurred. At this time, the data control circuit 31
Are adjacent sub-regions RGS _A , RGS _B and RG in step SP23.
After setting the fed back quantization step conversion data RATIO having a value corresponding to the manner of change in the significant image information S _C, to perform the calculation of the quantization step STEPG in step SP20.

In the case of this embodiment, the data control circuit 31 determines in step SP23 that the static ratio data W is a numerical value "6" (meaning that there is no change in the image information in all adjacent sub-regions RGS _A , RGS _B , RGS _C ). ), The largest value "1.8" is set as the feedback quantization step conversion rate data RATIO. Thus, the quantization circuit 16 sets the smallest value as the quantization step STEPG, thereby setting the adjacent sub-region RG
When an image state in which there is no image change in S _A , RGS _B and RGS _C and there is no image movement in the encoded sub-region RGS ₀ is obtained, the encoded sub-region RGS _{0 is set} to be the smallest. Fine quantization is performed by the quantization step STEPG.

The data control circuit 31 determines that the stillness ratio data W is 5 or 4
(Meaning that there is no image change in the adjacent sub-region RGS _A and one of RGS _B and RGS _C )
A slightly smaller numerical value "1.5" is set as the feedback quantization step conversion rate data RATIO. Thus the quantization circuit 16 performs a bit coarse quantization of the coded sub-region RGS ₀ for the image such that the image changes in the part of the image portion adjacent to the coded sub-region RGS _0.

Further, when the stillness ratio data W is a numerical value “3” (only the adjacent sub-region RGS _A is still,
Only the RGS _B and RGS _C are stationary), and a smaller value "1.2" is set as the feedback quantization step conversion rate data RATIO. Thus the data control circuit 31 executes a coarser quantization on the encoded sub-region RGS ₀ by further increasing the value of the quantization step STEPG.

When a negative result is obtained in step SP17, the data control circuit 31 determines whether or not the motion vector is 0 in step SP24.

If a negative result is obtained here, there is a change in the image of the adjacent sub-region RGS _A , which is most affected by the fact that the stillness ratio data W is equal to or smaller than the numerical value “3” (the adjacent sub-region RG).
Against S _B or one of RGS _C is stationary) the means it is detected that an image such that there is no movement of the image on a coded sub-region RGS _0. At this time, the data control circuit 31 sets the value of the feedback quantization step conversion rate data RATIO to a medium value "1.
After setting "5", an operation for obtaining the quantization step STEPG is executed in the above-mentioned step SP20.

Thus, the data control circuit 31 has a change in the image in the adjacent sub-region RGS _A adjacent in the H direction to the stationary coded sub-region RGS ₀ , and accordingly, the boundary of the image information is in the coded sub-region RGS _0. since, by performing a bit coarse quantization for the coded sub-region RGS _0, so that it is possible to generate the transmission data obtained by compressing the amount of data to the extent that does not degrade the image quality.

If a positive result is obtained in step SP24,
This means that at the same time that the image of the adjacent sub-regions RGS _A , RGS _B, and RGS _C has changed, the image of the encoded sub-region RGS ₀ has also moved, and at this time, the data control circuit 31 determines at step SP 26 After setting the feedback quantization step conversion rate data RATIO to a value "1.0" at which no conversion is performed for the feedback quantization step, step S
In P20, the operation of the quantization step STEPG is executed.

Thus, the data control circuit 31 reduces the feed-back quantization step STEP _FB when the image in the quantization circuit 16 moves with the adjacent sub-regions RGS _A , RGS _B and RGS _{C in the} sub-region RGS ₀ to be encoded. The coarse quantization is performed by using the image as it is without performing the control, and as a result, control is performed to suppress the data generation amount for the moving image portion having low visibility.

According to the configuration of FIG. 2, per quantizes the significant image information of the coded sub-region RGS _0, the adjacent sub-areas RGS _A, RGS _B
And at the same time to determine how to change the image in RGS _C, the coded sub-region RGS to determine the presence or absence of motion of _0. both relative change or according to the movement how quantization step ST
By selecting the EPG value, the main area R
The quantization step can be controlled so as to conform to the contents of the image information of each part of the GM, and thus transmission data of higher image quality can be generated as compared with the conventional case.

(G2) Second Embodiment FIG. 4 shows a second embodiment, and FIGS. 2 (A) and 2 (B).
The data control circuit 31 executes a quantization step calculation processing procedure in which steps SP18 and SP24 in FIG. 2 (B) are replaced with steps SP18X and SP24X, as indicated by the same reference numerals. I do. .

2 (A) and 2 (B), the data control circuit 31
It was to determine whether the motion vectors for only the coded sub-region RGS ₀ there is a motion in the coded sub-region RGS ₀ by the determination of whether a "0", 4th In the case of the embodiment shown in the figure, instead of this, “the difference between the motion vector of the encoded sub-region RGS _{0 and} the motion vector of the adjacent sub-region RGS _A is 0, and the encoded sub-region RGS ₀
Of the motion vector of the adjacent sub-region RGS _B is zero or not.

According to the configuration of FIG. 4, the quantization at the time of quantizing according to whether or not the motion of the significant image information in the encoded sub-region RGS ₀ matches the motion of the adjacent sub-regions RGS _A and RGS _B is determined. Chemical steps
By controlling STEPG, if there is an area with a different motion even in an image with motion on the image, the boundary part can be quantized with fine quantization steps, which can be further applied to the content of significant image information It is possible to generate transmission data having a reduced image quality.

(G3) Other Embodiments (1) In the above-described embodiment, in steps SP10, SP13 and SP16 (FIG. 2A), adjacent sub-regions RGS _A and RGS _A
Static rate data respectively different weight to S _B and RGS _C
Although the case where W _A , W _B and W _C are assigned has been described, the same effect as in the above case can be obtained by assigning the same weight instead.

(2) In the above embodiment, as shown in FIG. 3, the sub-region RGS _K adjacent to the adjacent sub-regions RGS _A and RGS _B is used.
Has been described in which the correlation with the sub-region RGS ₀ to be coded is not detected. Alternatively, the stationary rate data W for the adjacent sub-region including the change in the sub-region RGS _K is obtained. You may do it.

H Effect of the Invention As described above, according to the present invention, the quantization step is determined based on the motion of the image of the sub-region to be coded and the change of the adjacent sub-region. Can be finely quantized as necessary, thereby generating transmission data with further improved image quality.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an image data generating apparatus to which a video signal encoding method according to the present invention is applied, and FIGS. 2 (A) and 2 (B) show a video signal encoding method according to the present invention. FIG. 3 is a schematic diagram illustrating a method of detecting the content of image information, FIG. 4 is a flowchart illustrating a second embodiment, and FIG. 5 is a high-efficiency encoding method. FIG. 6 is a block diagram showing a conventional video signal encoding processing device, FIG. 7 is a characteristic curve diagram for explaining the quantization step, and FIG. 8 is a conventional image data generation device. It is a block diagram which shows an apparatus. Reference numeral 1 denotes an image data generating device, 2 ... a video signal encoding circuit, 3 ... a transmission buffer memory, 4 ... a transmission line, 5 ...
Image data recording / reproducing device, 15 conversion coding circuit, 16
... quantization circuit, 21 ... motion compensation circuit, 31 ... data control circuit.

Claims (4)

(57) [Claims] 1. A video signal encoding apparatus for encoding a digital video signal with high efficiency, comprising: means for quantizing the digital video signal based on a quantization step; Means for generating stillness data indicating the degree of change in image information for the image area; and a quantization step value based on the size of the stillness data and motion data indicating the motion of the encoded image area. A video signal encoding device, comprising: means for controlling. 2. A video signal encoding apparatus for encoding a digital video signal with high efficiency, comprising: means for quantizing the digital video signal based on a quantization step to generate transmission data; and temporarily storing the transmission data. A transmission buffer memory for transmitting data; a means for generating stillness data indicating a degree of change in image information for an adjacent image area adjacent to the encoded image area to be transmitted; Means for obtaining conversion rate data based on motion data representing the motion of the image area; means for controlling the value of the quantization step based on the conversion rate data and the remaining amount data indicating the remaining amount of data in the transmission buffer memory. A video signal encoding device comprising: 3. A video signal encoding method for encoding a digital video signal with high efficiency, wherein the digital video signal is quantized based on a quantization step, and an adjacent image area adjacent to an encoded image area to be transmitted is provided. Generating the degree of staticity data indicating the degree of change of the image information, and controlling the value of the quantization step based on the size of the degree of staticity data and the motion data indicating the motion of the encoded image area. A video signal encoding method characterized by the above-mentioned. 4. A video signal encoding method for efficiently encoding a digital video signal, comprising the steps of: quantizing a digital video signal based on a quantization step to generate transmission data; Generating stillness data representing the degree of change in image information for adjacent adjacent image areas, and obtaining conversion rate data based on the size of the stillness data and motion data representing the motion of the encoded image area. Video signal encoding characterized in that the value of the quantization step is controlled on the basis of the conversion rate data and the remaining data indicating the remaining data of the transmission buffer memory for temporarily storing the transmission data. Method.