JP2001008207A - Dynamic image coder and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a code amount controller that relates to high efficiency coding of a dynamic image and is especially suitable for variable bit rate coding in real time. SOLUTION: This dynamic image coder that encodes a dynamic image is provided with a means 23 that detects a generated code amount of each image, a means 22 that detects a mean quantization scale of each image, a means 25 that detects at least a coding image characteristic of a received image in the received image and a motion compensation prediction image, a means 24 that calculates complexity of an image pattern on the basis of the generated code amount detected by the code amount detection means 23, the mean quantization scale detected by the quantization scale detecting means 22, and the coding picture characteristic detected by the image characteristic detecting means 25, and a means 14 that decides an assigned code amount of a picture going to be coded next on the basis of the generated code amount, the complexity of the image pattern and a coding image characteristic and decides the quantization scale of the image about to be coded next on the basis of the assigned code amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high-efficiency coding of moving images, and more particularly to a code amount control apparatus and method suitable for performing variable bit rate coding in real time.

[0002]

2. Description of the Related Art MPEG2 has already been defined as an international standard for technology for efficiently encoding moving images such as TV signals. M
PEG2 divides a `` frame '' image that composes a moving image into 16 × 16 pixel blocks called `` macroblocks '', and in each macroblock unit, a reference image separated by a predetermined number of frames before or after a predetermined time frame. A motion compensation called "motion vector" is obtained between the encoded images, and a "motion compensation prediction" technique for constructing the encoded image from the reference image based on the motion amount, and an error signal of the motion compensation prediction or the encoded image The "transform coding" technology, which compresses the amount of information using DCT (discrete cosine transform), which is a type of orthogonal transform,
It is stipulated based on two image coding element technologies.

FIG. 5 shows an example of the configuration of a conventional MPEG2 moving picture coding apparatus. FIG. 4 shows an example of an encoded picture structure. In the motion-compensated prediction, as in the coded picture structure shown in FIG.
It is composed of a combination of three types of pictures having different prediction methods, called a picture (forward prediction coding) and a B picture (bidirectional prediction coding). As shown in FIG. 5, in the transform coding, the output of the subtractor 71, which is the error signal of the motion compensation prediction by the motion compensator 77 in the P and B pictures, DCT is performed by the DCT unit 72.

[0004] After the DCT coefficient obtained by the DCT unit 72 is quantized by the quantizer 73 under the control of the output of the code amount control unit 90, it is variable-length together with other accompanying information such as a motion vector. Variable length encoder 7
5 is output after the code string is stored in the buffer 76 as a “bit stream”. At this time, the quantization scale is controlled by the code amount control unit 90 in accordance with the sufficiency of the buffer 76. On the other hand, the output coefficient of the quantizer 73 is
The signals are supplied to an inverse quantizer 77 and an IDCT unit 78, locally decoded, and stored in a frame memory 81 for each block.

[0005] Since MPEG2 is variable-length coding, the amount of generated code (bit rate) per unit time is not constant. Therefore, it is possible to control the bit rate to a required bit rate by appropriately changing the quantization scale at the time of quantization in the quantizer 73 for each macroblock. MPEG
2 In Test Model 5, a fixed bit rate control method that makes the generated code amount constant in GOP units has been proposed.

The fixed bit rate control method in Test Model 5 is an effective method for applications requiring a constant transfer rate. However, since almost the same code amount is assigned to any part of the moving image sequence, a sufficient code amount is not provided to a complex scene including a large amount of information, resulting in image quality deterioration. On the other hand, in the case of a simple scene with a small amount of information, the code amount becomes excessive and wasteful, and an appropriate rate control method is used for applications where a variable transfer rate is possible such as DVD-Video. I couldn't say.

[0007] A variable bit rate control method is a rate control method that solves the above problems. JP-A-6-14
No. 1298 discloses an encoding device using variable bit rate control. In this device, first, provisional encoding is performed on an input moving image using a fixed quantization scale, and the generated code amount is counted for each unit time. Next, the target transfer rate of each part is set based on the generated code amount at the time of provisional encoding so that the generated code amount of the entire input moving image becomes a required value. Then, while performing control so as to match the target transfer rate, the second encoding, that is, actual encoding, is performed on the input moving image.

However, in the above-mentioned conventional example, encoding must be performed at least twice in order to obtain an output bit stream. In applications requiring real-time performance, a two-pass system such as this apparatus is used. Variable bit rate control cannot be used.

On the other hand, there is also a variable bit rate control method for encoding a moving picture almost in real time, that is, a variable bit rate control method of a one-pass system. Japanese Patent Application Laid-Open No. H10-164577 discloses an encoding apparatus using a one-pass variable bit rate control method, for example, in FIG.

FIG. 6 shows an example of the configuration of a moving picture coding apparatus according to this conventional example. The same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In this conventional device, the code amount stored in the buffer 76 is supplied to the generated code amount detector 83, and the generated code amount by the generated code amount detector 83 and the quantization scale from the quantizer 73 are averaged. Of the quantization scale in the screen by the average quantization scale detector 82, the product of the average value of the quantization scales in the screen is calculated as “screen complexity” by the screen complexity calculator 84, and the past screen complexity is calculated. The variable bit rate control is realized by the code amount controller 74 by determining the target generated code amount or the target quantization scale of the screen based on the ratio of the current screen complexity to the average value of the degrees.

[0011]

However, in the above-described conventional one-pass method, the current screen to be coded is provisionally coded to determine the current screen complexity, or the provisional coding is not performed. In order to make the screen complexity of the same picture type immediately before the current screen complexity, in the case of provisional encoding, the delay due to the provisional encoding becomes a problem even in the one-pass method, and the circuit scale increases and the processing is increased. It gets complicated.

On the other hand, if the screen complexity changes, such as when a scene change occurs immediately before the current screen to be coded without provisional coding, the same picture immediately before use as the current screen complexity is used. There is a problem that the screen complexity of the type differs from the actual screen complexity and an inappropriate code amount is allocated.

In view of the above, the present invention provides a one-pass variable bit rate control method for encoding a moving picture almost in real time, which is capable of more appropriately allocating a code amount while minimizing the increase in delay and circuit size. It is an object of the present invention to provide an apparatus and a method for implementing the method.

[0014]

Accordingly, in the present invention, MPEG
In a moving image coding apparatus based on variable bit rate control provided with means for motion compensation prediction, orthogonal transformation, quantization, and variable length coding, such as 2nd, first, a generated code amount of each image, an average quantization scale, Detected image characteristics (activity). The detection of the generated code amount and the average quantization scale of each moving image is performed during the actual coding operation without provisional coding, and a predetermined value is calculated for a product of the generated code amount of each image and the average quantization scale. Is performed and the screen complexity is obtained.
The screen complexity is added for each coded picture type for an image within a predetermined time from the picture immediately after the end of the coding, and the average screen complexity of each picture type is calculated.

On the other hand, the detection of the encoded image characteristics is performed prior to (prior to) the actual encoding operation, and the activity of the encoded image is calculated for each image. The screen complexity of the current image to be encoded is estimated by multiplying the screen complexity of the previous image of the same picture type by the ratio of the activity of the image to be encoded to the activity in the image, By reflecting the estimated screen complexity and the ratio of the average screen complexity in a certain section to the code amount allocation based on the target bit rate, a one-pass method for allocating the code amount corresponding to the image change without increasing the delay. Variable bit rate control of the system becomes possible.

Further, as for the P and B pictures for which motion compensation prediction is performed for detecting the characteristics of the coded image, the absolute value or the absolute value of the error image in the motion compensation prediction or the difference image between the coded image and the reference image in the motion vector detection. By using the square error and the degree of variation of the motion vector in combination, it becomes possible to estimate the screen complexity of an image to be encoded in accordance with the encoding characteristics.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment
Will be described below with reference to FIG. It is assumed that the original image is previously divided into macroblocks by an image block divider (not shown).

In the divided source image, motion compensation prediction is not performed for the I picture, and the source image block itself is sent to the DCT unit 12 via the subtractor 11 and
After that, the quantization is performed by the quantizer 13 using the quantization scale sent from the code amount controller 14. The quantized signal is converted into a code by the variable length encoder 15,
The code is output after being adjusted in the next buffer 16. On the other hand, the output coefficient of the quantizer 13 is the inverse quantizer 1
7. Local decoding is performed by the IDCT unit 18, and the output of the motion compensation predictor 19 is stored in the frame memory 21 for each block without being added by the adder 20.

For P and B pictures, the divided original moving picture and predetermined locally decoded picture blocks stored in the frame memory 21 are supplied to a motion compensation predictor 19, where motion vector detection and motion compensation are performed. Then, a difference between pixels of the predicted image block and the original image block is calculated by the subtractor 11, and the error image block, which is the difference value, is calculated by DC.
It is sent to the T unit 12.

Thereafter, the DCT is performed in the same manner as the I picture.
The difference value is subjected to DCT by the encoder 12, quantized by the quantizer 13 by the quantization scale sent from the code amount controller 14, converted into a code by the variable length encoder 15, and then converted by the next buffer 16. The code is output after the adjustment.

On the other hand, the output coefficients of the quantizer 13 are locally decoded by an inverse quantizer 17 and an IDCT unit 18 and then the predicted image block is added for each pixel by an adder 20. 21. For each picture, the quantizer 13 calculates the quantization scale for each macroblock from the average quantization scale detector 2.
2, the quantization scale for one frame is added, and the average quantization scale for one frame is calculated.

On the other hand, the generated code amount is monitored in the buffer 16, and the value is sent to the generated code amount detector 23. The generated code amount detector 23 adds the generated code amount for each frame, and detects the generated code amount for one frame. The average quantization scale and generated code amount detected for each frame are sent to the screen complexity calculator 24 for each frame.

On the other hand, the image characteristic detector 25 is supplied with a moving image obtained by dividing the original image at the time of input, detects an activity which is a parameter indicating image characteristics for each frame of the moving image in units of macroblocks, and for each frame. The result is added, and the result is sent to the screen complexity calculator 24 frame by frame. Here, the operation of detecting the image characteristics by the image characteristic detector 25 is performed prior to the actual encoding operation. As parameters indicating the image characteristics, variance of luminance values, difference values between pixels, and the like can be considered, but other parameters may be used as long as they indicate image characteristics.

The screen complexity calculator 24 multiplies the average quantization scale of each supplied frame by the generated code amount and then performs a predetermined conversion on the multiplication result. Complexity is required. The screen complexity is calculated by adding the value within a certain period for each coded picture type and then dividing by the number of frames of the same picture type within that period to obtain an average screen complexity of each of the I, P, and B picture types. ave (I picture), Xp-ave (P picture) and Xb-ave (B picture) are calculated.

During the certain period, the number of frames predetermined in time before the picture for which encoding has just finished, for example, a certain number of frames such as 15 frames or 300 frames, may be used. In some cases, such as from a frame to an image for which encoding has just finished, the number of frames is sequentially increased. Note that, even in the case of the former fixed number of frames, if the number of encoded frames does not satisfy the predetermined certain period, the number of frames is sequentially increased similarly to the latter.

Up to the portion where the screen complexity of the portion which has already been encoded is obtained is the same as in the conventional example, but in the present invention, the current image is encoded according to the activity of the current image to be encoded. The part for estimating the screen complexity differs from the conventional example. Also in the following description, i corresponds to an I picture, p corresponds to a P picture, and b corresponds to a B picture.

That is, the screen complexity Xi, Xp, Xb of the current image to be encoded is the activity ACTi, ACTp, ACTb of the current image and the screen complexity Xi- of the image of the same picture type encoded immediately before. p, Xp-p, Xb-p, the activity of the previously coded image of the same picture type
From ACTi-p, ACTp-p and ACTb-p, it can be estimated by the following equations (1), (2) and (3).

(I picture) Xi = Xi-p · (ACTi / ACTi-p) (1)

(P picture) Xp = Xp-p · (ACTp / ACTp-p) (2)

(B picture) Xb = Xb-p · (ACTb / ACTb-p) (3)

In the initial state, if there is no encoded frame of the same picture type,
The screen complexity and activity of images of each picture type may be obtained in advance for some images, and these may be statistically averaged in accordance with the average frequency of occurrence of moving images, and may be used as initial values.

Thereafter, the average screen complexity Xi-ave, Xp-ave, Xb-ave of each picture type and the estimated screen complexity Xi, Xp, Xb of the current image to be coded are calculated by the code amount controller 14. Sent to The code amount controller 14 sets (determines) the assigned code amount of the image to be coded next (from now on) and sets (determines) the quantization scale for variable bit rate control.

The target average bit rate is BitRate, the number of frames per second is PictureRate, and one encoding unit, 1G
Assuming that the number of frames of the OP (usually the interval between I pictures) is N, the average allocated code amount Rave of one GOP is given by the following equation (4). Rave = (BitRate / PictureRate) N (4)

If Rave in the above equation is the required code amount of 1 GOP at the time of average screen complexity, the 1 GOP image including the current image to be coded is uniformly obtained by the screen complexity calculator 24. Assuming that it is equal to the estimated screen complexity of the current image, the required allocated code amount Rc of one GOP required to keep the image quality constant is given by the following equations (5), (6), and (7).

(I picture) Rc = Rave · (Xi / Xi-ave) (5)

(P picture) Rc = Rave · (Xp / Xp-ave) (6)

(B picture) Rc = Rave · (Xb / Xb-ave) (7)

By appropriately allocating the required allocated code amount Rc in the above equation to each picture of 1 GOP, the target code amount of the current image to be coded is calculated. MPEG as an example
2 The target code amount allocation method of Test Model 5 is described below, but other methods may be used. The number of frames of the P and B pictures included in one GOP is Np, Nb, and the setting ratio of the quantization scale of the P and B pictures to the I picture is Kp.
Kb. At this time, the target allocation code amount of each picture type
Ti, Tp, and Tb are given by the following equations (8), (9), and (10).

Note that MAX [A, B] indicates an operation of selecting the larger one of A and B. In the MPEG2 Test Model 5, Xi, Xp, and Xb are the screen complexity of the picture coded immediately before, but may be the estimated screen complexity of the current picture to be coded.

(I picture) Ti = MAX [A, B] A = Rc / (1 + Np.Xp / (Xi.Kp) + Nb.Xb / (Xi.Kb)) B = BitRate / (8.PictureRate (8)

(P picture) Tp = MAX [C, D] C = Rc / (Np + Nb · Kp · Xb / (Kb · Xp)) D = BitRate / (8 · PictureRate) (9)

(B picture) Tb = MAX [E, F] E = Rc / (Np + NpKbXp / (KpKb)) F = BitRate / (8PictureRate) (10)

Based on the target allocated code amount determined by the above equation and the generated code amount of each macroblock detected in the buffer 16, the quantization scale of each macroblock is determined using the method of MPEG2 Test Model 5. I do. The activity of each macroblock is also sent from the image characteristic detector 25 to the code amount controller 14, and is used for adaptive quantization control for changing the quantization scale of each macroblock based on the activity in the MPEG2 Test Model 5. However, the adaptive quantization control need not be performed. Alternatively, the quantization scale of each macroblock may be determined by a completely different method.

The quantization scale of each macroblock output from the code amount controller 14 is sent to the quantizer 13, and the current image (an original image after DCT or an error image block for motion compensation prediction) is obtained. The data is quantized by the quantizer 13 at this quantization scale, subjected to variable-length encoding by the variable-length encoder 15, adjusted by the next buffer 16, and then output as a code. The quantization scale for each macroblock of the quantizer 13 and the generated code amount monitored by the buffer 16 are sent to the average quantization scale detector 22 and the generated code amount detector 23, respectively, and the code amount control of the next picture is performed. Used for

Next, the second embodiment of the moving picture coding apparatus of the present invention will be described.
Will be described below with reference to FIG. The second embodiment differs from the first embodiment only in the configuration and operation of the image characteristic detector shown in FIG. 3, and FIG. Vessel 1
9 is different from FIG. 1 in that a motion compensation signal is supplied, and the description of other parts is omitted. The image characteristic detector shown in FIG. 3 is an ACTcur detector 25A, ACTp
It comprises a red detector 25B, an ACTmv detector 25C, and a picture activity calculator 25D.

In the embodiment shown in FIGS. 2 and 3, the input to the image characteristic detector 25 is divided into macroblock units as in the first embodiment, since no motion compensation prediction is performed for an I picture. Is input, only activity (ACTcur), which is a parameter indicating image characteristics in macroblock units, is detected and added in frame units.
It is sent to the screen complexity calculator 24 as an I-picture activity ACTi.

On the other hand, when the input to the image characteristic detector 25 shown in FIG. 2 is a P and B picture, in addition to the divided original image, an error image or a motion vector in the motion compensation prediction in macroblock units is detected. The difference image between the coded image and the reference image and the motion vector used in the motion compensation prediction are input from the motion compensation predictor 19 shown in FIG. From the divided original image, the activity (actual image) ACTcur
Is detected.

On the other hand, the error image in the motion compensation prediction in the macroblock unit or the difference image between the coded image in the motion vector detection and the reference image is subjected to the sum of absolute values or the sum of the square errors in the error image.
Is detected as Further, the motion vector used in the motion compensated prediction has an absolute value of a difference between each component and an adjacent macroblock, and is detected as ACTmv.

Then, ACTmb is calculated for each macroblock by the operation of the following equation (11), and ACTmb is added for one frame, and the activities ACTp and AC of the P and B pictures are calculated.
It is sent to the screen complexity calculator 24 as Tb.

ACTmb = a · ACTcur + b · ACTpred + c · ACTmv (11)

The values of the constants a, b, and c are changed for each picture, each macroblock prediction mode (intra, unidirectional prediction, or bidirectional prediction). For example, in the case of intra, prediction is not performed like an I picture.
Since b = c = 0, and it is considered that the generated code amount is larger than that of the block to be predicted, the value of a is increased.

As described above, by detecting the activity in accordance with the prediction mode or the like, compared with the first embodiment,
It is possible to estimate the screen complexity in accordance with the encoding characteristics. In the first embodiment, the average screen complexity required for obtaining the required allocated code amount Rc of 1 GOP is obtained for each coded picture type. After adding the screen complexity of each frame in, the value obtained by dividing by the number of frames in that period is obtained as the average screen complexity X-ave, and the estimated screen complexity Xk of the current image (k = i or p or b ), The following equation (12)
The required allocated code amount Rc of one GOP may be obtained by the following. This may be applied to the second embodiment.

Rc = Rave · (Xk / X-ave) (where k = i or p or b) (12)

In the first and second embodiments, the picture coding structure is such that an I picture, a P picture, a B picture as shown in FIG.
Although it has been described that there are three types of pictures, there may be only two types such as an I picture and a P picture and an I picture and a B picture. Also, all pictures may be I pictures for which motion compensation prediction is not performed. However,
The second embodiment in the case of only I-pictures is exactly the same as the first embodiment because the input to the image characteristic detecting unit 25 is only the divided original image.

[0055]

As described above, according to the present invention, when a moving image is encoded by variable bit rate control, the generated code amount and average quantization scale of an image in a fixed section after the coding is completed, and And the encoded image characteristic (activity) of the current image to be encoded is detected, and a value obtained by performing a predetermined operation on the product of the generated code amount and the average quantization scale is obtained as the screen complexity. Above, the screen complexity of the image to be encoded is estimated by multiplying the complexity of the previous image of the same picture type by the ratio of the activity of the image to be encoded to the activity in the image, By reflecting the estimated value and the ratio of the average screen complexity in a certain section to the code amount allocation based on the target bit rate, the delay does not increase. Variable bit rate control one-pass performing code amount allocation in response to changes of the image.

Further, as for the P and B pictures for which motion compensation prediction is performed for detecting the above-mentioned coded image characteristics, the absolute value or the absolute value of the difference image between the coded image and the reference image in the motion compensation detection or the motion image detection is used. By using the square error and the degree of variation of the motion vector in combination, it becomes possible to estimate the screen complexity of an image to be encoded in accordance with the encoding characteristics.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a moving picture coding apparatus and method according to the present invention.
It is a figure showing an example of.

FIG. 2 shows a second example of the moving picture coding apparatus and method according to the present invention.
It is a figure showing an example of.

FIG. 3 is a diagram showing an embodiment of an image characteristic detector according to the second embodiment of the present invention.

FIG. 4 is a diagram showing an embodiment of a coded picture structure.

FIG. 5 is a diagram illustrating a configuration example of a general moving image encoding device.

FIG. 6 is a diagram illustrating a configuration example of a conventional moving picture encoding device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Subtractor 12 DCT unit 13 Quantizer 14 Code amount controller 15 Variable length encoder 16 Buffer 17 Dequantizer 18 IDCT unit 19 Motion compensation predictor 20 Adder 21 Frame memory 22 Average quantization scale detector 23 Generated code amount detector 24 Screen complexity calculator 25 Image characteristic detector 25A ACTcur detector 25B ACTpred detector 25C ACTmv detector 25D Picture activity calculator ACTcur Original image activity ACTi, ACTp, ACTb Current image activity ACTi-p , ACTp-p, ACTb-p Activity of the image of the same picture type coded immediately before ACTmv Motion vector characteristic ACTpred Error image activity Rave Average allocated code amount Rc Allocated code amount of image Xi, Xp, Xb Screen complexity of current image Degree Xi-ave, Xp-ave, Xb-ave Average screen complexity

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK06 MA00 MA05 MA23 MC11 MC38 ME01 PP05 PP06 PP07 SS13 TA46 TA57 TB04 TB08 TC02 TC10 TC16 TC18 TC38 TD01 TD03 TD04 TD14 UA02 UA33 5J064 AA02 BA09 BA16 BB03 BC08 BC08 BC08

Claims (9)

[Claims] 1. A moving picture coding apparatus for coding an input moving picture by including a motion compensation predicting means, an orthogonal transform means, a quantizing means, and a variable length coding means, comprising the steps of: Means for detecting the generated code amount of; and means for detecting an average quantization scale of each image of the input moving image; and at least the motion compensated prediction image generated by the input moving image and the motion compensation prediction means. Means for detecting a coded image characteristic of the input moving image, an amount of generated codes detected by the means for detecting the generated code amount, an average quantization scale detected by the means for detecting the average quantization scale, and Means for calculating the complexity of the screen from the encoded image characteristics detected by the means for detecting the image characteristics; and a generated code detected by the means for detecting the generated code amount. From the screen complexity calculated by the means for calculating the amount and the complexity of the screen and the coded image characteristics detected by the means for detecting the coded image characteristics, the allocated code amount of the image to be coded next is calculated. Means for determining the quantization scale of the image to be coded next from the allocated code amount. 2. The moving picture coding apparatus according to claim 1, wherein the amount of generated code is detected by the means for detecting the amount of generated code, and the average quantization scale is detected by the means for detecting the average quantization scale. The detection performs the detection at the time of the actual encoding operation, and the detection of the encoded image characteristic by the means for detecting the image characteristic is characterized in that the detection is performed prior to the actual encoding operation. Video encoding device. 3. The moving picture coding apparatus according to claim 1, wherein the means for calculating the complexity of the screen comprises a product of the detected generated code amount and the average quantization scale. Is obtained for each picture type (I picture, P picture, B picture), and the screen complexity of the latest past picture of the same picture type as the picture to be encoded next is obtained. A moving image code which obtains a current screen complexity by multiplying a ratio of an encoded image characteristic of the image to be next encoded to an encoded image characteristic in an image in which the past screen complexity is calculated. Device. 4. The moving picture coding apparatus according to claim 1, wherein an assigned code quantity of an image to be encoded next is determined from the generated code quantity and the screen complexity. Determining the allocated code amount by multiplying an average allocated code amount by a ratio of the calculated current screen complexity to an average value of the past screen complexity for a certain period of time. Encoding device. 5. The moving picture coding apparatus according to claim 4, wherein the average value of the past screen complexity in a certain period is obtained for each picture type (I picture, P picture, B picture). Moving image code, wherein the allocated code amount is determined by multiplying an average allocated code amount by a ratio of the calculated current screen complexity to the average value of the same picture type as an image to be encoded. Device. 6. The moving picture coding apparatus according to claim 1, wherein said means for detecting a coded picture characteristic of the input picture or the motion-compensated predicted picture comprises an image of the input picture. A picture type (I picture, P picture, B picture) comprising means for detecting characteristics, means for detecting an image property of an error image of the motion compensated prediction image, and means for detecting a motion vector property in the motion compensated prediction.
Constants for different and prediction modes are multiplied to the respective characteristic values of the detected image characteristics of the input image, the image characteristics of the error image of the motion compensated prediction image, and the motion vector characteristics in the motion compensation prediction, and then added. A moving image coding apparatus for determining the characteristics of the coded image. 7. A moving picture coding method for coding an input moving picture by including a motion compensation prediction step, an orthogonal transformation step, a quantization step, and a variable length coding step, wherein each image of the input moving picture is Detecting the generated code amount of; and detecting an average quantization scale of each image of the input moving image; and at least the motion compensated prediction image generated by the input moving image and the motion compensation prediction step. Detecting the coded image characteristic of the input moving image, and the generated code amount detected by the step of detecting the generated code amount, the average quantization scale detected by the step of detecting the average quantization scale, and Calculating the complexity of the screen from the encoded image characteristic detected by the step of detecting the image characteristic; The generated code amount detected by the raw code amount detecting step and the screen complexity calculated by the step of calculating the screen complexity and the coded image characteristic detected by the step of detecting the coded image characteristic are calculated. Determining the allocated code amount of the image to be encoded next, and determining the quantization scale of the image to be encoded next from the allocated code amount. . 8. The moving picture coding method according to claim 7, wherein the amount of generated code is detected by the step of detecting the amount of generated code, and the average quantization scale is detected by the step of detecting the average quantization scale. The detection performs the detection at the time of the actual encoding operation, and the detection of the encoded image characteristic by the step of detecting the image characteristic is characterized in that the detection is performed prior to the actual encoding operation. Video encoding method. 9. The moving picture encoding method according to claim 7, wherein the step of calculating the complexity of the screen comprises a product of the detected generated code amount and the average quantization scale. The past screen complexity obtained with reference to the picture type (I
Picture, P-picture, B-picture), and for the screen complexity of the latest past image of the same picture type as the next image to be coded, A moving image encoding method for obtaining a current screen complexity by multiplying a ratio of an encoded image characteristic of an image to be encoded to the next image.