JPH09130787A - Dynamic image coder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the dynamic image coder that encodes an image at a coding frame rate in response to image quality with a small delay. SOLUTION: The coder is provided with a coding section 117 coding a received moving image signal, an output buffer 115 receiving coded data from the coding section 117 and transmits the data at a prescribed transmission rate, and a coding control circuit 116 selecting frames to be coded. Then the coding control circuit 116 calculates an object code amount for each frame based on a coding bit rate, a coding frame rate and a permissible delay time set externally, compares the calculated amount with a code amount generated actually to conduct coding control in which a quantization circuit 106 and a switch 101 are controlled and quantization parameters and number of skipped frames are adjusted.

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 for compressing and coding a moving picture into a small amount of information, and in particular, at a coding frame rate according to the picture quality and at the time of outputting the coded data The present invention relates to a moving picture coding device capable of suppressing the above.

[0002]

2. Description of the Related Art In a system for transmitting and storing images, such as a TV telephone, a TV conference system, a portable information terminal, a digital video disc system and a digital TV broadcasting system, the image has a small amount of information for transmission or storage. Various techniques such as motion compensation, discrete cosine transform, subband encoding, and pyramid encoding, and a combination of these have been developed as compression encoding techniques.

In addition, ISO / MPEG1, MPEG2, ITU-T /
H. 261, H .; 262 is specified. All of these are compression coding methods that combine motion-compensated adaptive prediction and discrete cosine transform, and are described in Reference 1 (edited by Hiroshi Yasuda, "International Standard for Multimedia Coding", Maruzen, June 1991).
Month) etc. for details.

In a moving picture coding apparatus using such a picture compression coding technique, when a moving picture is coded at a low bit rate of 64 kbps or less, it is difficult to code at the frame rate of an input moving picture signal. Therefore, it is general that the input moving image signal is encoded every few frames, and the encoding frame rate is lowered to perform encoding. Then, when the encoding of one frame is completed, 1
All the encoded data of the frame is temporarily held in the output buffer, and is output to the communication path or another system according to the preset transmission rate (encoding bit rate) of the encoded data.

How much the coding frame rate is set is very important because it greatly affects the coding quality. However, if the frame rate of the input moving image signal is 30 Hz when the frame rate of encoding is fixed, the frame rate of encoding is 30, 15, 10, 7.5 depending on how many frames are encoded. , 6, 5,
It is decided to be a discrete value such as 4.29 or 3 Hz. Therefore, for example, there are cases where encoding at 10 Hz results in good motion but poor image quality, and encoding at 7.5 Hz results in good image quality but poor motion. In addition, there is a problem that a moving scene appears and the image quality suddenly deteriorates.

Therefore, coding control is being considered in which the coding frame rate is changed according to the change in image quality. For example, PSTN (Public Switched T
H.264, which is a standard method of moving image coding for elephon Network public telephone network). 263 simulation model TMN5 (ITU
-T TSS LBC-95 SG15 WP15 / 1
VIDEO CODE TEST MODEL, T
MN5, Jan. 1995) employs a variable frame rate code amount control algorithm in which the coding frame rate changes during coding (TMN algorithm). The TMN algorithm increases the target coding frame rate of the next frame and decreases the target coded data amount (target code amount) of the frame as the average of the quantization parameter QP of the preceding frame decreases. As described above, conversely, when the average of the quantization parameter QP of the previous frame increases, the target encoding frame rate of the next frame decreases, and control is performed so that the target encoding amount of the frame increases. .

[0007]

When such a compression coding method is applied to moving picture coding for communication or broadcasting, it is desired that the delay is low in order to enable real-time communication. However, unlike the TMN algorithm, the conventional moving picture coding apparatus that changes the coded frame according to the fluctuation of the image quality and controls the generated coded data amount does not consider the delay in the output buffer. In addition, there is a problem that a large delay may occur when the encoded data is output.

Therefore, an object of the present invention is to provide a moving picture coding apparatus capable of suppressing a delay amount at the time of outputting coded data at a coding frame rate according to image quality.

[0009]

The moving picture coding apparatus of the present invention temporarily holds the coding means for coding the input image signal and the coded data output from the coding means, and is predetermined. Output means for outputting at the specified transmission rate,
The transmission rate and the predetermined encoding frame rate are determined so that the delay time when outputting the encoded data held in the output means at the transmission rate is within the predetermined allowable delay time. By setting the target code amount for each frame by adjusting the code amount to be generated, and by including a control unit that controls the code amount generated by the encoding unit based on the target code amount, the image quality is improved. It is possible to suppress the delay amount at the time of outputting the encoded data at the encoding frame rate according to the above.

Further, the moving picture coding apparatus of the present invention comprises coding means for quantizing and coding an orthogonal transform coefficient obtained by orthogonally transforming an input image signal or a prediction residual signal for the input image signal. An output unit that temporarily holds the encoded data output from the encoding unit and outputs the encoded data at a predetermined transmission rate; and an output unit that outputs the encoded data held by the output unit at the transmission rate. The target code amount for each frame is set by adjusting the code amount determined by the transmission rate and the predetermined encoding frame rate so that the delay time is within the predetermined allowable delay time. Then, based on this target code amount, the first control means for controlling the quantization parameter at the time of quantization by the encoding means, and the encoding held in the output means. Second control for skipping the input image signal input to the encoding unit in frame units until the code amount of data reaches a value determined by the transmission rate, the allowable delay time, and the encoding frame rate By including the control means described above, it becomes possible to suppress the delay amount at the time of outputting the encoded data at the encoded frame rate according to the image quality.

Further, the first control means controls the quantization parameter of the encoding means on the basis of the target code amount and the image complexity of the input image signal, so that the code according to the image quality can be obtained. It is possible to suppress the delay amount at the time of outputting the encoded data at the encoded frame rate.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows the configuration of a moving picture coding apparatus according to this embodiment.

In FIG. 1, the input moving image signal input to the encoding unit 117 is as follows.
01, where the input moving image signal of the frame to be encoded is selected under the control of the encoding control circuit 116 and divided into macroblocks by the blocking circuit 102. The input moving image signal divided into macroblocks is input to the subtractor 103, and the difference between the input moving image signal and a predicted image signal generated as described later is calculated to generate a prediction residual signal. One of the prediction residual signal and the input moving image signal from the blocking circuit 102 is
A mode is selected by the mode selection switch 104, and a discrete cosine transform is performed by a DCT (discrete cosine transform) circuit 105. The DCT coefficient data obtained by the DCT circuit 105 is
It is quantized by the quantization circuit 106. The signal quantized by the quantization circuit 106 is branched into two, and one of them is variable length coded by the variable length coding circuit 113. On the other hand, the quantization circuit 10
The other of the signals quantized by 6 and divided into two is the inverse quantization circuit 107 and the IDCT (inverse discrete cosine transform) circuit 10.
8, the processing reverse to the processing of the quantization circuit 106 and the DCT circuit 105 is sequentially performed, and then the adder 109 adds the predicted image signal input via the switch 112 to generate a locally decoded signal. It The locally decoded signal is stored in the frame memory 110 and is input to the motion compensation circuit 111 to generate a predicted image signal.

In the encoding control circuit 116, the encoding unit 11
The encoding unit 117 is controlled based on the encoding information of No. 7, the encoded data amount (code amount) from the variable length encoding circuit 113, and the buffer amount of the output buffer 115, and necessary information is supplied to the variable length encoding circuit. Come to 113. The data encoded by the variable length encoding circuit 113 is multiplexed by the multiplexing circuit 114, smoothed by the output buffer 115 at a constant output rate (encoding bit rate), and sent as encoded data.

The encoding control circuit 116 notifies the encoding bit rate (rate (bits / sec)) of the encoded data output from the output buffer 115 and the encoding frame rate (f_rate ((Hz)). And a signal notifying the allowable delay time of the encoded data output from the output buffer 115, that is, the allowable delay time (limit_delay (msec)) is input, and information preset by these signals is input. Based on the delay time of the encoded data output from the output buffer 115 by the allowable delay time (limit_de
The code amount generated by the encoding unit 117 is controlled so as to be within lay (msec)).

Next, the principle of the present invention will be described with reference to FIG. Note that, here, when the encoding of one frame is completed, all the encoded data of one frame is input to the output buffer 115, and the encoding bit rate rate is set.
Output from the output buffer according to (bits / sec).

Average delay time ave_delay (mse
c) depends on the buffer amount B of the output buffer 115. The delay time delay_time (msec) in the frame of frame number (f_no) n is 100, which is obtained by dividing the peak buffer amount value B [n] at the end of encoding of the frame of frame number n by the encoding bit rate rate.
It is a value multiplied by zero. Average delay time ave_delay
Is the average of the delay times thus obtained.

In this embodiment, basically, the target code amount target is calculated for each frame to be encoded, and the quantization parameter, the encoding frame rate, that is, the number of frames to be skipped is changed on the basis of the target amount. Thus, the delay time is controlled to be kept constant.

The initial value of the target code amount target for each frame is a value obtained by dividing the coding bit rate rate by the set coding frame rate f_rate. Here, the frame rate f_rate to be set does not have to be a value obtained by dividing the frame rate FR of the input moving image signal by a natural number. Therefore, the encoding frame rate f to be set
_Rate is not a discrete value as in the case of the fixed coding frame rate, but the degree of freedom is increased. For example, f_ra
A value such as 7.25 (Hz) can be set for te. However, in order to keep the delay time setting, the average delay time ave_delay up to that point is set to the set value limi.
When t_delay is exceeded, the target code amount target for each frame is reduced by the amount exceeding t_delay.

The method of determining which frame is to be encoded next is as follows. That is, the buffer amount B corresponds to the preset encoding bit rate and the allowable delay time rate * limit_dela.
The encoded data is transmitted until it becomes less than or equal to the amount obtained by subtracting the default target code amount rate / frame (bits) from y / 1000 (bits). At this time, f_cnt is a value indicating how many frames are to be coded next.
Let be represented by. By performing control in this way, if the generated code amount in the next frame is suppressed within the target code amount,
Delay time delay_time is set value limit_d
It cannot be larger than elay.

The actual generated code amount is the target code amount target.
When t is greatly exceeded, f_cnt becomes large, more input frames are skipped, the coding frame rate is lowered, and conversely, when the generated code amount is much lower than the target code amount, f_cnt becomes small. , The coding frame rate increases without skipping than usual.

As described above, the target code amount t for each frame
In addition to setting the target to limit the amount of generated code,
As a result, by determining the frame to be encoded next based on the generated code amount, the encoding frame rate according to the image quality is realized, and the average delay time of the encoded data output from the output buffer 115 is realized. However, it can be suppressed within the set allowable delay time.

FIG. 3 is a coding control circuit 1 for performing coding processing for each frame in the moving picture coding apparatus of FIG.
16 is a flowchart for explaining the control processing operation for each 16 frames.

First, before encoding for each frame, a target code amount target for each frame is set (step S101), and the quantization circuit 10 is set based on the target.
The reference quantization parameter b_QP for each frame when the quantization in 6 is performed is set (step S102).

Next, before the encoding process for each macroblock, the quantization parameter QP is calculated (step S103), and the quantization circuit 106 is controlled based on the value to perform the encoding process. (Step S104).
This quantization parameter QP is a quantization parameter in intraframe coding.

After the completion of the encoding process for one frame, the number of frames f_c for which the encoding is skipped by the process described later.
nt is obtained, and the frame to be encoded next is determined (step S105). Then, the input moving image signal switch 101 is controlled so as to skip (thinning) the frames of the number of frames f_cnt.

Next, the setting processing operation of the target code amount target for each frame in step S101 of FIG. 3 will be described in detail with reference to the flowchart shown in FIG.

The target code amount target for each frame is
The first frame (frame number f_no = 1) is set to a preset encoding bit rate rate as an initial value (steps S201 to S).
202). 2nd frame onward (frame number f_no
= 2 or more), first, the set encoding bit rate r
ate is set to the set encoding frame rate f_rat
It is set by a value divided by e (step S203). However, if the average delay time ave_delay of the coded data of the frames encoded up to the previous time exceeds the set delay time limit_delay (step S204), the code amount corresponding to the exceeded time is t.
It is subtracted from the target (step S205).

When the value of the set target is smaller than the value obtained by dividing the set value rate by the frame rate FR of the input moving image signal (step S206), the control may be broken. Therefore, the code amount is prioritized over the delay amount, and the target is rate / FR.
Is set (step S207).

Next, the reference quantization parameter b_QP for each frame in step S102 of FIG. 3 will be described. The reference quantization parameter b_QP can be obtained by the equation (1).

[0031]

(Equation 1)

However, b_QP is limited to 1 to 31. Note that pre_QP represents an average quantization parameter one frame before, pre_frame_bits represents a code amount one frame before, and α represents a reaction parameter of the first quantization parameter.

In addition to the above, there are the following methods for obtaining the reference quantization parameter b_QP. That is, the standard deviation sgm of the motion-guaranteed prediction error signal (signal 118 in FIG. 1) for one screen is calculated in advance, and the standard deviation sgm is calculated.
And the target code amount target. This standard deviation is calculated after subtracting the average value for each small area (for example, 8 × 8 block unit). b_QP can be obtained from the equation (2).

[0034]

(Equation 2)

Here, a and b are constants, and a = 0.
25, b = about 1.5. Next, the quantization parameter QP in step S103 of FIG. 3 will be described. The quantization parameter QP can be obtained by the equation (3). Note that the quantization parameter QP can be calculated for each macroblock, but in the present embodiment,
QP is calculated for each macroblock line.

[0036]

(Equation 3)

However, QP is limited to 1 to 31. In Expression (3), mb is the current number of macroblocks (1 to MB), MB is the number of macroblocks per frame, β is the reaction parameter of the second quantization parameter, and the array encoded_bits is , The generated code amount of each macroblock.

Next, with reference to the flow chart shown in FIG. 5, the coded frame determination processing operation in step S105 of FIG. 3 will be described. Where f_cnt
Indicates the number of frames to be encoded next, that is, the number of frames skipped for encoding.

First, when the variable length coding circuit 113 notifies the code amount generated in that frame, it is added to the buffer amount B of the output buffer 115 at that time (step S301).

The method of determining the value f_cnt indicating the number of frames to be coded next is as follows. First, f_
Initialize by setting the value of cnt to "0" (step S
302). Then, the set encoding bit rate rat
A value obtained by dividing e by the frame rate FR of the input moving image signal,
That is, the code amount corresponding to the transmission rate of the input moving image signal at the frame rate FR is subtracted from the buffer amount B (step S303), and the code amount corresponding to the allowable delay time (limit_delay) set by the buffer amount B. From (rate × limit_delay / 1000), the default code amount per frame (rate / f_
until the value is less than or equal to the value obtained by subtracting the
5), f_cnt is increased (step S30)
4). As a result, the number of frames skipped for encoding is f_
cnt is obtained.

Next, another control processing operation for each frame of the encoding control circuit 116 when performing the encoding processing will be described with reference to the flow chart shown in FIG. This encoding control method calculates the activity of the prediction residual signal 118 selected by the switch 109 before encoding, sets a target code amount for each macroblock, and responds to more image quality. It is characterized by performing coding control. The activity of the prediction residual signal 118 is
The image state information indicating the complexity of the image to be encoded for each macroblock indicates that the larger the value of this activity, the larger the code amount needs to be.

First, before encoding for each frame, a target code amount Target for each frame is set (step S
401), and the target code amount t for each macroblock
The target_mb is set (step S402). Then, the reference quantization parameter b_QP for each frame is set (step S403).

Next, before the encoding process for each macroblock, the quantization parameter QP is calculated (step S404), and the encoding process (step S405) is performed based on the calculated value.

After the encoding process for one frame is completed, the number f_cnt of frames for skipping encoding is calculated, and the frame to be encoded next is determined (step S406). FIG.
Target code amount t for each frame in step S401 of
The setting processing operation of the target is similar to that of FIG.

The setting of the target code amount target_mb for each macroblock in step S402 of FIG. 6 is obtained from the equations (4) to (9) for each macroblock mode. First, the activity of an intra-coded macroblock (hereinafter referred to as an intra macroblock) is calculated according to the equations (4) and (5).

Here, each macroblock is H.264 as shown in FIG. 261, MPEG1, H263, and other formats commonly used for luminance signals (Y) having four 8 × 8 pixel blocks and color difference signals (Cb, Cr) for two 8 × 8 pixel blocks. It consists of 6 blocks.

Also, the original_picture
Shows the input video signal of each macroblock,
dc is the average value of the macro blocks of the input moving image signal calculated by the equation (5).

[0048]

(Equation 4)

[0049]

(Equation 5) As a result, the target code amount ta for each intra macroblock ta
rget_mb is calculated by the equation (6).

[0050]

(Equation 6)

Note that intra represents the number of intra macroblocks in the frame, inter represents the number of inter macroblocks in the frame, and not_coded represents the number of uncoded macroblocks in the frame. In the inter-frame coding macroblock (hereinafter referred to as an inter macroblock), the activity is calculated according to the equation (7), and the target code amount ta of each macroblock is expressed by the equation (8).
Calculate rget_mb. Note that pred_pictu
re is a predicted image signal of each macroblock generated by the motion compensation circuit 111.

[0052]

(Equation 7)

[0053]

(Equation 8) The activity ratio comp is calculated from the data encoded one frame before according to the equation (9).

[0054]

(Equation 9)

Here, encoded_bits represents the generated code amount of each macroblock, and QP represents the value of the quantization parameter in each macroblock. The reference quantization parameter b_QP for each frame in step S403 of FIG.
It is obtained by the equations (10) and (11).

[0056]

(Equation 10)

[0057]

[Equation 11]

However, b_QP is 1. . . Limited to 31. Note that frame_act is the activity of the current frame, pre_QP is the average quantization parameter one frame before, pre_frame_bits
Is the code amount of one frame before, pre_frame_ac
t is the activity of the frame one frame before, α
Represents the reaction parameter of the first quantization parameter.

The quantization parameter QP in step S409 of FIG. 6 is obtained by the equation (12). The quantization parameter QP can be calculated for each macroblock, but in the present embodiment, the QP is calculated for each macroblock line.

[0060]

(Equation 12)

However, QP is 1. . . Limited to 31. Note that mb is the current number of macroblocks (1 to M
B), MB is the number of macroblocks per frame,
β represents the reaction parameter of the second quantization parameter, and the array encoded_bits represents the generated code amount of each macroblock.

The coded frame determination processing operation in step S406 of FIG. 6 is similar to that of FIG. 5, and determines f_cnt. In the present embodiment, the description has been made on the frame-by-frame basis, but it goes without saying that field-based encoding can also be carried out.

FIG. 8 shows a second embodiment in which the moving picture coding apparatus of the present invention is applied to a wireless communication system. In FIG. 8, the wireless communication system is an image transmission system 2
0 and an image reproduction system 21, and images are transmitted and received via a base station 41 provided with a network 40.

The image transmission system 20 is provided with an information current coding unit 22 having an image signal input unit 21 and an error resilience processing unit 23, a transmission line coding unit 24, and a radio unit 25, and has an information source code. In the digitization unit 22, the discrete cosine transform (DCT)
And quantization are performed, and the transmission line encoding unit 24 performs error detection and correction of encoded data.

The moving picture coding apparatus according to the present invention is applied to the main part of the information source coding section 22. Further, the image reproduction system 30 includes a wireless unit 31, a transmission line combination unit 32, an information source combination unit 33 including an error resilience processing unit 34, and an image signal output unit 35.

FIG. 9 shows an example of a wireless communication system according to the second embodiment, and as shown in FIG. 9, it is of a laptop type via the base stations 41, 42 and 43 of the communication network 40. A terminal 50 "such as a personal computer 51 or a desktop personal computer 52" transmits and receives a moving image.

For example, the image signal input by the camera 51a as an image signal input unit provided in the personal computer 51 is encoded by the information source encoding unit 22 incorporated in the personal computer 51. The coded data output from the information source coding unit 22 is multiplexed with other voice and data information, and then wirelessly transmitted via the wireless unit 25 and the antenna 51b incorporated in the personal computer 51. This transmitted radio signal is transmitted to the antenna 52 of the personal computer 52 via the base stations 41 to 43 provided in the network 40.
a, it is received via the wireless unit 31 incorporated in the personal computer 52. The signal received by the wireless unit 31 is decomposed into coded data and audio data of the image signal. Of these, the coded data of the image signal is decoded by the information source decoding unit 33 incorporated in the personal computer 52 and displayed on the display of the personal computer 52.

On the other hand, the image signal input by the camera 52b as the image signal input unit 21 provided in the personal computer 52 is encoded in the same manner as above by using the information source encoding unit 22 incorporated in the personal computer 52. It The encoded data is multiplexed with other voice and data information, and is wirelessly transmitted by the wireless unit 25 and the antenna 52a incorporated in the personal computer 52. The transmitted radio signal is received via the base stations 41 to 43 provided in the network 40, the antenna 51a of the personal computer 51, and the wireless unit 31 incorporated in the personal computer 51. The signal received by the wireless unit 31 is decomposed into coded data of an image signal and voice or data information. Of these, the coded data of the image signal is decoded by the information source decoding unit 33 incorporated in the personal computer 51 and displayed on the display of the personal computer 51.

As described above, according to the above embodiment, in the encoding control circuit 116, the output buffer 1
The delay time when outputting the coded data held in 15 at a predetermined coding bit rate (rate) is a predetermined allowable delay time (lim).
it_delay) so that the coding bit rate (rate) and the coding frame rate (f_rat)
e) encoding amount (rate / f_rat)
By adjusting e), the target code amount t for each frame t
The target is set, and the quantization circuit 106 and the switch 101 of the encoding unit 117 are controlled based on it (specifically, the quantization step parameter and the number of frames f_cnt to be skipped without encoding are calculated. By doing so, it becomes possible to suppress the delay amount at the time of outputting the encoded data at the encoding frame rate according to the image quality.

Further, the activity representing the image complexity of the input moving image signal is calculated for each macroblock on the basis of the prediction residual signal 118, and the quantization parameter is calculated in consideration of the activity. It is possible to perform encoding control according to the image quality.

[0071]

As described above, according to the present invention,
It is possible to provide a moving image encoding device that can suppress the delay amount at the time of outputting encoded data at an encoding frame rate according to image quality.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing the configuration of a moving image encoding device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of processing operation of an encoding control circuit.

FIG. 3 is a flowchart for explaining a processing operation for one frame of the encoding control circuit.

FIG. 4 is a flowchart for explaining a target code amount setting processing operation for each frame.

FIG. 5 is a flowchart illustrating a processing operation for determining a coding frame rate.

FIG. 6 is a flowchart for explaining another processing operation for one frame of the encoding control circuit.

FIG. 7 is a diagram for explaining a macroblock format.

FIG. 8 is a diagram schematically showing a configuration of a wireless communication system to which the present invention is applied.

FIG. 9 is a diagram showing an example of a wireless communication system to which the present invention is applied.

[Explanation of symbols]

101 ... Input moving image signal switch, 102 ... Blocking circuit, 103 ... Subtractor, 104 ... Mode selection switch,
105 ... DCT circuit, 106 ... Quantization circuit, 107 ... Inverse quantization circuit, 108 ... IDCT circuit, 109 ... Adder,
110 ... Frame memory, 111 ... Motion compensation circuit, 1
12 ... Switch, 113 ... Variable length coding circuit, 114 ...
Multiplexing circuit, 115 ... Output buffer, 116 ... Encoding control circuit, 117 ... Encoding section.

Claims (3)

[Claims] 1. An encoding means for encoding an input image signal, an output means for temporarily holding encoded data output from the encoding means and outputting at a predetermined transmission rate, and an output means for the output means. A code amount determined by the transmission rate and a predetermined encoding frame rate so that the delay time when the stored encoded data is output at the transmission rate is within a predetermined allowable delay time. By setting a target code amount for each frame by adjusting, and a control means for controlling the code amount generated by the encoding means based on the target code amount. Encoding device. 2. An encoding means for quantizing and encoding an orthogonal transform coefficient obtained by orthogonally transforming an input image signal or a prediction residual signal for the input image signal, and a code output from this encoding means. Output means for temporarily holding the encoded data and outputting the encoded data at a predetermined transmission rate, and a delay time for outputting the encoded data held by the output means at the transmission rate is a predetermined allowable delay. The target code amount for each frame is set by adjusting the code amount determined by the transmission rate and the predetermined encoding frame rate so that it is within time, and based on this target code amount, A first control unit that controls a quantization parameter when quantizing by the encoding unit, and a code amount of the encoded data held in the output unit is the transmission rate. And second control means for controlling the input image signal input to the encoding means to be skipped frame by frame until a value determined by the allowable delay time and the encoding frame rate is reached. And a moving picture coding device. 3. An encoding means for quantizing and encoding an orthogonal transform coefficient obtained by orthogonally transforming an input image signal or a prediction residual signal for this input image signal, and a code output from this encoding means. Output means for temporarily holding the encoded data and outputting the encoded data at a predetermined transmission rate, and a delay time for outputting the encoded data held by the output means at the transmission rate is a predetermined allowable delay. The target code amount for each frame is set by adjusting the code amount determined by the transmission rate and the predetermined coding frame rate so that it is within the time, and the target code amount and the input image are set. First control means for controlling a quantization parameter for quantization by the encoding means based on the image complexity of the signal; and the encoding data held in the output means. A control for skipping the input image signal input to the encoding unit in frame units until the code amount of the data reaches a value determined by the transmission rate, the allowable delay time, and the encoding frame rate. 2. A moving picture coding device, comprising: