JPH10191337A - Video coding apparatus and method and video multiplexing apparatus and method - Google Patents

Abstract

(57) Abstract: A moving picture coding apparatus for coding and multiplexing a plurality of moving picture signals and outputting the same at a fixed bit rate has a uniform quality of output moving pictures. SOLUTION: A quantization control unit 4 includes storage units 2-1 to 2-
A quantization width is obtained based on the sum total of the coding amounts of the moving picture coded signals accumulated in N, and the coding unit 1-1 uses the same quantization width.
.About.1-N. The multiplexing control unit 7 controls the encoding unit 1-1 to 1-1 based on the values obtained by the decoding delay time operation unit 5 and the frame code amount operation unit 6 so that overflow and underflow do not occur in the decoding device. The encoded video signal output at the 1-N variable bit rate is multiplexed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for compression-encoding a video signal and an apparatus for multiplexing the compression-encoded video signal. The present invention relates to encoding control and multiplexing control for improving the quality of an output video when a coded signal having a constant bit rate is generated.

[0002]

2. Description of the Related Art One of the methods of compression-encoding a plurality of videos and multiplexing them into one bit stream at a certain output bit rate is to output a sum of a plurality of compression-encoded moving images. There is a method of allocating a fixed bit rate to each moving image so that the bit rate is obtained. In this method, when a video having a high degree of complexity with respect to the assigned bit rate is input, a large deterioration in image quality occurs.
Also, when a video having a low complexity is input, stuffing increases and a band is wasted. Therefore, there is a contradictory problem that the image quality decreases when trying to effectively use the band, and the band cannot be effectively used and the number of multiplexable images decreases when trying to increase the image quality. Therefore, as an apparatus for solving this problem, Japanese Patent Application Laid-Open No.
Japanese Patent Publication No. 540 discloses a video encoder-based control device that makes the bit rate of an output moving image signal variable and improves the image quality of an output video. This device compares the coded video with the original video, increases the bit rate for video with large distortion, and at the same time reduces the bit rate of video with low distortion, thereby improving the image quality of each video. And the image quality as a whole is improved.

[0003]

However, in such a configuration, the bit rate is changed after the distortion amount is obtained. The image quality deteriorates only in the video immediately after the change.

When the bit rate of a compression-encoded moving image is variable, simple multiplexing is performed, for example, when the bit rate is proportional to the amount of bits generated in a certain period of time. In some cases, the input buffer of the decoding device that receives the coded signal overflows or underflows.

In view of this point, the present invention provides a moving picture encoding apparatus in which the picture quality of each output moving picture is always uniform, and the picture quality is not greatly degraded immediately after the picture is suddenly complicated by a scene change or the like. It is an object of the present invention to provide a video multiplexing device that outputs a video multiplexed signal in which an input buffer of the multiplexing device does not cause overflow or underflow.

[0006]

A moving picture coding apparatus according to the present invention is a moving picture coding apparatus for coding a plurality of moving picture signals, wherein the moving picture coding apparatus quantizes the moving picture signals with predetermined parameters. And a plurality of encoding means for encoding the plurality of video signals, and a quantization control means for simultaneously controlling parameters used by each of the quantization means. Things. According to this, the image quality of each output moving image can be made uniform.

Further, the moving picture multiplexing apparatus of the present invention is a moving picture multiplexing apparatus for multiplexing a plurality of coded moving picture signals obtained by coding a moving picture signal, A plurality of storage means for temporarily storing coded signals, and multiplexing means for multiplexing the plurality of moving picture coded signals stored in the plurality of storage means and outputting the multiplexed signal at a constant bit rate, Decoding delay time calculating means for calculating a time from when a specific bit of each of the plurality of moving picture coded signals is input to a decoding device until decoding is performed, and stored in the plurality of storage means, The operation of the frame code amount calculating means for calculating the code amount of the frame to which the specific bit of each of the plurality of encoded video signals belongs, the decoding delay time calculating means and the frame code amount calculating means. Multiplexing control means for controlling a plurality of first input code amounts which are code amounts of the plurality of encoded video signals input from the plurality of storage means to the multiplexing means based on the result. It is characterized by the following. According to this, multiplexing can be performed while always taking the decoding delay time of the decoding device into consideration, so that occurrence of overflow or underflow when the decoding device decodes the coded video signal is prevented. be able to.

The moving picture multiplexing method according to the present invention is a moving picture multiplexing method for multiplexing a plurality of coded moving picture signals, wherein a plurality of multiplexed codes corresponding to the plurality of coded moving picture signals are previously stored. Setting the amount to zero, calculating a frame code amount of a frame to which a specific bit of each of the plurality of encoded video signals belongs, and decoding each of the plurality of encoded video signals. A second step of calculating the time until the decoding, the third step of selecting a moving picture coded signal whose time until the decoding obtained in the second step is smaller than a predetermined time value, A fourth step of obtaining a plurality of first multiplexed code amounts based on the frame code amount of the moving picture coded signal selected in the third step; and obtaining a sum of the plurality of first multiplexed code amounts. Fifth stay And a sixth step of adding the plurality of first multiplexed code amounts to the plurality of multiplexed code amounts, respectively, and a seventh step of updating the predetermined time value. If the sum of the plurality of first multiplexed code amounts is equal to or more than a predetermined code amount, a plurality of second multiplexed code amounts are obtained and added to the plurality of multiplexed code amounts. And multiplexing the moving picture coded signals of the plurality of multiplexed code amounts. According to this, since the frames until the decoding time are as short as possible are multiplexed first, it is possible to prevent underflow when the decoding device is decoding the moving picture coded signal.

Further, the moving picture multiplexing method of the present invention is a moving picture multiplexing method for multiplexing a plurality of coded moving picture signals, wherein the plurality of coded moving picture signals not transmitted to a decoding device are provided. Based on the amount of code per frame and the time until the plurality of encoded video signals are decoded for each frame, based on a plurality of input buffers of the decoding device necessary for avoiding underflow. Determine the minimum transmission amount of, determine a plurality of transmission code amount lower limit based on the plurality of minimum transmission amount, before multiplexing the plurality of moving picture encoded signals,
The transmission code amount lower limit is multiplexed first. According to this, since the code amount necessary for preventing the occurrence of underflow is preferentially output, it is possible to prevent the occurrence of underflow when the decoding device is decoding the coded video signal.

The moving picture coding method according to the present invention further comprises the steps of: summing up the code amounts of the plurality of moving picture coding signals generated by coding a plurality of moving picture signals; A moving image coding method for simultaneously coding the plurality of moving image signals using a predetermined quantization width based on a difference between an output code amount temporarily stored and output, wherein a plurality of once stored multiple The encoding buffer occupancy is determined for each moving picture encoded signal, and when the moving picture encoded signals are not input to a plurality of input buffers of a predetermined time decoding device, the respective ones after the predetermined time The amount of free space in the input buffer is obtained for each of the moving picture encoded signals, and the respective buffer difference values obtained by subtracting the free space of each of the input buffers from the respective occupied amounts of each of the coding buffers are smaller than the predetermined value. The coded signal, and is characterized in that coding each moving image signal by using a small quantization width than said predetermined quantization width. According to this,
Even if the complexity of the video is extremely large and the generated code amount is suddenly increased in a part of the plurality of input moving image signals,
When the decoding device is decoding the video encoded signal,
It is possible to prevent underflow of the input buffer.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

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

1-1 to 1-N (N is a natural number) An encoding unit for compressing and encoding an input moving image by signal conversion and quantization. 2-1 to 2-N are encoding units 1-1 to 1--1. -N, a storage unit for storing the encoded video signal output from the multiplexing unit; 3, a multiplexing unit for multiplexing the encoded video signal and outputting the multiplexed video signal at a constant bit rate; The quantization control unit 5 that controls the quantization width in the quantization performed by N calculates a time (decoding delay time) from when a certain bit of the moving picture coded signal is input to the decoding device to when it is decoded. A decoding delay time calculation unit 6 is a frame code amount calculation unit that calculates the code amount of each frame of the moving picture coded signal stored in the storage units 2-1 to 2-N, and 7 controls the multiplexing unit 3. The multiplexing control unit 8 is configured to code the moving image coded signals stored in the storage units 2-1 to 2-N. An adder for adding the.

FIG. 15 is a detailed diagram of an example of the encoding unit 1-1 of FIG. Encoding sections 1-2 to 1-N have the same configuration. The moving image signal input to the encoding unit 1-1 is converted into a frame memory 108-1 by a differentiator 101-1.
Is converted into a difference image from the frame image stored in the. The difference image is converted by DCT (discrete cosine transform) means 10
It is converted to DCT coefficients by 2-1. The DCT coefficient is quantized by the quantization means 103-1 with the quantization width input to the quantization means 103-1 and then converted into a moving picture coded signal by the variable length coding means 104-1. Is done. The output signal of the quantization means 103-1 is also output to the inverse quantization means 105-1, and after being inversely quantized, converted into a decoded difference image by the inverse DCT means 106-1. The decoded difference image is added to the frame image stored in the frame memory 108-1 by the adder 107-1 and converted into a decoded image.
-1.

The operation of the above configuration will be described below. The encoded video signals output from the encoding units 1-1 to 1-N are temporarily stored in the storage units 2-1 to 2-N. The code amounts of the encoded moving image signals stored in the storage units 2-1 to 2-N are all added by the adder 8, and then output to the quantization control unit 4. The quantization control unit 4
The code amount output from the adder 8 is converted into a quantization width. FIG. 2 is a graph showing an example of this conversion method. The horizontal axis is the sum of the code amounts of the encoded video signals stored in the storage units 2-1 to 2-N. This value is the sum of the code amounts of the encoded video signals generated by encoding. , And the output code rate converted from the output bit rate. The vertical axis is the quantization width. In this embodiment, the larger the code amount, the larger the quantization width, and the smaller the code amount, the smaller the quantization width. The quantization control unit 4 calculates the value of one quantization width obtained in this manner,
Output to all encoding units 1-1 to 1-N. That is,
The same quantization width is set in all of the encoding units 1-1 to 1-N, and the encoding units 1-1 to 1-N perform quantization using this quantization width.

As described above, according to the present invention, since the input moving image is compression-coded using the same quantization width, the image quality of a plurality of output moving images can always be made uniform. . In addition, since the quantization control is performed based on the total code amount of the encoded moving image signals stored in the storage units 2-1 to 2-N, the output band can be used effectively.

In this embodiment, all encoding units 1
Although -1 to 1-N are controlled with the same quantization width, even if the quantization widths are made different due to restrictions such as setting a priority or an upper limit of the output bit rate for each encoding unit. However, this does not depart from the spirit of the present invention.

The decoding delay time calculation section 5 includes storage sections 2-1 to 2-1.
2-N, the decoding delay time of the bit transmitted first to the multiplexing unit 3 among the accumulated moving picture coded signals is obtained. The initial values are defined by the encoding units 1-1 to 1-
N is the decoding delay time of the first output bit, and is determined in advance from the size of the input buffer of the decoding device, the output bit rate of the multiplexing unit 3, and the like. After that, the value is updated according to the decoding procedure of the decoding device.

The frame code amount calculation unit 6 includes a storage unit 2-1.
In the moving picture coded signal stored in .about.2-N, the code amount of the frame including the bit transmitted to the multiplexing unit 3 first is obtained. The multiplexing control unit 7 uses the values obtained by the decoding delay time calculation unit 5 and the frame code amount calculation unit 6 to calculate
The calculation of the code amount to be sent from each of the storage units 2-1 to 2-N to the multiplexing unit 3 is repeated at a constant cycle. The multiplexing unit 3
The multiplexed video signal is multiplexed based on the code amount obtained by the multiplexing control unit 7 and output at a constant bit rate.

FIG. 17 is a detailed diagram of an example of the multiplexing control section 7 of FIG. The first parameter generation unit 71 determines the code amount of a frame including bits to be transmitted to the multiplexing unit 3 first among the moving image coded signals stored in the storage units 2-1 to 2-N. The decoding delay time is input. The first parameter generation unit 71 obtains a value obtained by dividing the frame code amount by the decoding delay time. The second parameter generation unit 72 includes a first parameter generation unit 71 for the storage units 2-1 to 2-N.
Find the sum of the values found by. Third parameter generator 73
Calculates a value obtained by dividing each of the values obtained by the first parameter generation unit 71 with respect to the accumulation units 2-1 to 2-N by the value obtained by the second parameter generation unit 72. The number of output bits of the moving image signal output from the multiplexing unit during the cycle of calculating the amount of code sent from each of the storage units 2-1 to 2-N to the multiplexing unit 3 is stored in the multiplexed code amount calculating unit 74. Is obtained, and the product of the number of bits and the value obtained by the third parameter generation unit 73 for each of the storage units 2-1 to 2-N is obtained. This value is stored in the storage units 2-1 to 2-N Each of them is output to the multiplexing unit 3 as a code amount to be sent to the multiplexing unit 3.

FIG. 18 is a block diagram of another multiplex coding apparatus and a moving picture multiplex apparatus according to the present embodiment. In the block diagram of FIG. 1, the free space of the input buffer of the decoding apparatus at the current time is shown. A decoding buffer free space calculation unit 9 for calculating
A storage code amount calculation unit 12 for calculating the number of bits stored in each of the storage units 2-1 to 2-N is added. The decoding buffer free space calculation unit 9 includes a timer. The decoding buffer free space calculation unit 9 receives the number of multiplexed bits from the multiplexing control unit 7 and adds this to the input buffer occupancy of each decoding device. Also, the code amount for each frame input to the input buffer of each decoding device is input from the frame code amount calculation unit 6 and the decoding delay time of the frame is input from the decoding delay time calculation unit 5. When the value of the timer reaches the value of the time at which the frame is decoded, the code amount of the decoded frame is subtracted from the input buffer occupancy of the decoding device. Then, a value obtained by subtracting the input buffer occupancy from the input buffer capacity of each decoding device is output to the multiplexing control unit 7 as the decoding buffer free space at the current time.

FIG. 19 is a detailed view of an example of the multiplexing control section 7 shown in FIG. 18, in which a minimum value selecting means 75 is added at a stage subsequent to the multiplexed code amount calculating section 74 shown in FIG. The minimum value selecting means 75 calculates the value obtained by the multiplexed code amount calculation unit 74 for each of the storage units 2-1 to 2-N, the decoding buffer free space at the current time obtained by the decoding buffer free space calculation unit 9, and The smallest value among the three values of the stored code amounts of the storage units 2-1 to 2-N obtained by the code amount calculation unit is output to the multiplexing unit 3 as the number of multiplexed bits.

FIG. 3 is a flow chart of the first embodiment of the moving picture multiplexing method according to the present invention.
Shows the operation of determining the code amount of the moving picture coded signal sent from the storage units 2-1 to 2-N to the multiplexing unit 3. First, the multiplexing control unit 7 obtains the number of bits of the encoded video signal output from the multiplexing unit 3 from the predetermined output bit rate and the cycle of the multiplexed code amount calculation (201). Next, the decoding delay time is read from the decoding delay time calculation unit 5 (20).
2). Next, the number of frame bits is read from the frame code amount calculator 6 (203). Next, in the procedure described later,
A first-order multiplex bit number is obtained (204). Next, the code amount of the encoded video signal stored in each of the storage units 2-1 to 2-N is obtained (205). Next, the amount of codes stored in the input buffer is subtracted from the capacity of the input buffer of the decoding device to determine the free space of the input buffer (2).
06). Next, for each of the moving picture encoded signals, the primary multiplexed bit number obtained in step 204, the code amount obtained in step 205, and the minimum value of the free space of the input buffer obtained in step 206 are obtained. The second-order multiplex bit number is set (207). Finally, the number of bits of the moving picture coded signal to be sent from the storage units 2-1 to 2-N to the multiplexing unit 3 is determined by the procedure described later (208). The above procedure is repeated in order.

FIG. 4 is a flowchart for explaining in detail the step 204 for obtaining the first-order multiplexed bit number in FIG. First, a value obtained by dividing the number of frame bits by the decoding delay time is obtained for each encoded moving image signal, and this value is defined as Ri (i = 1 to N) (301). Next, this R1
To RN are obtained (302). Next, the first-order multiplexed bit number P1i is obtained for each moving picture encoded signal by the following equation (303).

[0025]

(Equation 1)

Next, for each of the moving picture coded signals, the first-order multiplexed bit number P1i, the code amount obtained in step 205, and the minimum value of the free space of the input buffer obtained in step 206 are obtained. Secondary multiplex bit number P2
i.

FIG. 5 shows the storage units 2-1 to 2- in FIG.
6 is a flowchart illustrating in detail a step 208 for calculating the number of bits of a coded video signal to be transmitted to the multiplexing unit 3 from N. P1i and P1
If 2i (i = 1 to N) are the same, the process ends (40)
1). Otherwise, for each video encoded signal,
It is checked whether or not P1i and P2i (i = 1 to N) are the same (402).
The number of bits P3i that can be further multiplexed is obtained in addition to the number of secondary multiplexed bits obtained in (403).

[0028]

(Equation 2)

Here, min is the smaller of the code amount obtained in step 205 and the free space of the input buffer obtained in step 206.

If P1i and P2i are not the same,
P3i is set to 0 (404). Next, the total number of secondary multiplex bits obtained in step 207 is used to determine the number of bits D that is insufficient for the number of output bits by the following equation (4
05). Next, P3i obtained in steps 403 and 404
The sum S of (i = 1 to N) is obtained (406). Next, S
Is checked to see if is larger than D (407), and if it is larger, the number of multiplexed bits of the moving picture coded signal is

[0031]

(Equation 3)

(408), if S is not greater than D,

[0033]

(Equation 4)

(409). As described above, according to the present invention, the multiplexing is controlled based on the frame code amount of each moving image and the time at which the frame must be input to the decoding device. Can be prevented. Also, since the amount of code stored in the input buffer of the decoding device is always calculated and multiplexing is controlled so as not to transmit the amount of code exceeding the free space, it is possible to prevent the overflow of the input buffer of the decoding device. it can.

(Embodiment 2) Also in the second embodiment, the moving picture coding apparatus and the moving picture multiplexing apparatus shown in FIG. 1 are used.

FIG. 6 is a flow chart of a second embodiment of the moving picture multiplexing method according to the present invention.
Shows an operation of determining the number of multiplexed bits, which is the code amount of the moving picture coded signal transmitted from the storage units 2-1 to 2-N to the multiplexing unit 3. The multiplexing control unit 7 first obtains the total number of bits of the moving picture coded signal output from the multiplexing unit 3 from the predetermined output bit rate and the cycle of the multiplexed code amount calculation (501). Next, the lower limit value of the transmission amount is calculated for each of the moving picture coded signals by a procedure described later (50).
2) The moving image coded signal having the lower limit of the number of bits is output from the storage units 1-1 to 1-N to the multiplexing unit 3. next,
In order to select frames in ascending decoding delay time, an initial value is set to a reference time as a reference for comparison (5).
03). Next, from the frame code amount calculation unit 6 to the storage unit 1-
The number of bits of the first frame of 1 to 1-N is read (50
4). Next, from the decoding delay time calculation unit 5 to the storage units 1-1 to 1
Read the decoding delay time of the first frame of 1-N (50
5). Next, the decoding delay time of each of the encoded video signals is compared with the reference time (506). Then, for a video encoded signal whose decoding delay time is smaller than the reference time,
First, the free space of the input buffer of the decoder is obtained (50
7) the number of frame bits read in 504 and 507
In the maximum transmission code amount determined from the input buffer free space obtained in the above and the maximum output bit rate of the moving picture coded signal, the smallest value is defined as the number of primary multiplex bits and the moving picture code having a decoding delay time equal to or longer than the reference time For the coded signal, the first-order multiplex bit number is set to 0 (508). Next, the sum of the first-order multiplexed bit numbers is calculated. If the sum is 0, the cycle of the multiplexed code amount calculation ends (509). If the number of remaining output bits is smaller than the number of remaining bits (510), the number of primary multiplexed bits obtained in 508 is added to the number of multiplexed bits of the video encoded signal (511), and a frame period time is added to the reference time, for example. In addition, the reference time is updated (512). At this time, the encoded video signals of the first multiplex bit number are output from the storage units 1-1 to 1-N to the multiplexing unit 3, respectively.
If the number of primary multiplex bits is equal to or greater than the number of remaining bits of the number of output bits, a value obtained by proportionally distributing the number of remaining bits of the number of output bits according to the number of primary multiplex bits is defined as the number of secondary multiplex bits. (513) The obtained number of secondary multiplex bits is added to the number of multiplex bits of the video encoded signal, respectively (51).
4), the multiplex code amount calculation cycle ends. At this time,
The moving image coded signals having the number of secondary multiplex bits are output from the storage units 1-1 to 1-N to the multiplexing unit 3, respectively. The above procedure is repeated in order.

FIG. 7 is a graph for explaining step 502 for calculating the lower limit value of the transmission amount in FIG. The horizontal axis is the time axis, which indicates the time until the frame in the buffer is decoded. One scale is one frame cycle time. The vertical axis indicates the number of bits, where 0 or more indicates the number of bits of each frame in the encoder buffer, and 0 or less indicates the number of bits of each frame in the buffer of the decoder. The graph X shows the cumulative number of frame bits for each frame cycle time starting from the point A based on the number of frame bits of each moving picture encoded signal. The value on the time axis at point A is the time until decoding of the next frame to be decoded, and the value on the bit number axis is the code occupancy of the decoder input buffer. A graph Y shows a minimum transmission amount necessary for avoiding underflow. The graph Y is always tangent to the upper side of the graph X with the point B indicating the bit generation amount of the frame being encoded as a starting point, and 0 or more so that the maximum gradient does not exceed the maximum output bit rate of the video encoding device. Is a polygonal line drawn in the range. The number of bits in the cycle time of the multiplex code amount calculation on the horizontal axis is the lower limit value of the transmission amount obtained in step 502. In FIG. 7A, the lower limit is 0,
In (b), the lower limit is L (L> 0, (c) is an enlarged view of (b)). This lower limit is multiplexed before multiplexing the moving picture coded signal.

As described above, according to the present multiplexing method, a frame having a shortest decoding time is output first, and a code amount necessary for preventing occurrence of underflow is output with priority. The underflow of the input buffer of the decoding device can be prevented.

In the first embodiment of the moving picture coding apparatus and the moving picture coding method of the present invention described above, the maximum output bit rate of a coded moving picture signal and the capacity of an input buffer of a decoder are described. It is effective if there is no limit. But,
If the maximum output bit rate or the input buffer capacity is limited, in the first embodiment, the transmission of the moving picture coded signal cannot be made in time, and the buffer may underflow in the decoder. As an example, consider a case where a part of a plurality of input moving image signals has a very large video complexity and a generated code amount suddenly increases. At this time, in the decoder that decodes the coded video signal with the generated code amount increased, the input buffer is full because the code amount of the generated frame is larger than the code amount of the decoded frame. Becomes Therefore, the output code amount of the moving picture coded signal in which the generated code amount has not greatly increased,
The moving image coded signal stored in the storage unit downstream of the encoder decreases. Then, the code amount of the encoded video signal that can be output decreases, and as a result, the output bit rate from the multiplexing unit becomes insufficient. Since the quantization control always assumes that the output bit rate from the multiplexing unit is constant, a buffer underflow occurs in the decoder due to a decrease in the amount of transmission. Therefore, in order to prevent buffer underflow from occurring in the decoder, it is necessary to insert a signal that does not affect decoding (perform stuffing) in advance. Embodiments of the moving picture coding apparatus and the moving picture coding method of the present invention for realizing this will be described below.

(Embodiment 3) Next, a third embodiment of the present invention will be described. FIG. 8 is a block diagram of an embodiment of the moving picture coding apparatus and the moving picture multiplexing apparatus according to the present invention. 2-1 to 2-N and 3 to 8 are the same as those in FIG. Reference numeral 9 denotes a decoding buffer free space calculation unit for calculating the number of bits stored in the input buffer of the decoder, and obtaining a free space of the input buffer.
−N and the difference between the code amount of each moving picture coded signal stored in the decoding buffer free space calculation unit 9 and the decoding buffer free space corresponding to each of the storage units 2-1 to 2-N. The code amount difference calculation unit 11 to be determined is based on the difference value obtained by the code amount difference calculation unit 10, and the coding unit 1-1
Reference numerals 1 to 1-N denote stuffing control units that control the amount of stuffing performed on a coded video signal during encoding.

FIG. 16 is a detailed diagram of an example of the encoding unit 1-1 in FIG. 8, in which a stuffing unit 109-1 is added at the subsequent stage of the variable length encoding unit 104-1 in FIG. Encoding sections 1-2 to 1-N have the same configuration. The stuffing unit 109-1 inserts a stuffing bit of the stuffing amount given from the stuffing control unit 11 into the output signal of the variable length coding unit 104-1 and outputs the signal.

The operation of the above configuration will be described below. The decoding delay time calculation unit 5 is similar to FIG.
For each of the storage units 2-1 to 2-N, the decoding delay time of the bit transmitted to the multiplexing unit 3 in the moving picture coded signal stored first is determined, and the decoding buffer free space calculation unit 9 Output to Further, the frame code amount calculation unit 6
As in FIG. 1, the code amount of a frame including bits to be sent to the multiplexing unit 3 first among the moving picture coded signals stored in the storage units 2-1 to 2-N is calculated. Output to the decoding buffer free space calculation unit 9. The storage unit 2-1
The code amount of the moving picture coded signal stored in .about.2-N is all added by the adder 8, and then output to the decoding buffer free space calculation unit 9.

The decoding buffer free space calculating section 9 has a timer, and stores a moving picture output bit rate which is a bit rate assigned to a moving picture coded signal among output bit rates from the multiplexing section in advance. ing. First, the decoding buffer free space calculation unit 9 obtains the current free space of the decoding buffer from the decoding delay time and the code amount of each of the frames of the plurality of input moving picture encoded signals and the timer value. Next, based on the sum total of the code amounts of the moving picture coded signals stored in the storage units 2-1 to 2-N and the moving picture output bit rate of the moving picture coded signal output from the multiplexing unit, The time T for transmitting the moving picture encoded signals of the coding amounts of all the moving picture encoded signals stored in the units 2-1 to 2-N at the moving picture output bit rate is obtained by the following equation.

[0044]

(Equation 5)

Then, assuming that no moving picture coded signal has been input to the input buffer of the decoder during the time T from the present time, the free space of the input buffer of the decoder after the lapse of the time T is determined. . FIG. 9 is an explanatory diagram of the calculation performed by the decoding buffer free space calculation unit 9. FIG. 9A shows the current state of the storage unit and the input buffer of the decoder.
Is the current code amount in the storage unit, and B1 is the current free space in the decoder input buffer calculated by the decoding buffer free space calculation unit 9. Then, assuming that three frames are decoded by the decoder during the time T from the present time, the decoding buffer free space calculation unit 9 calculates B2 obtained by adding the code amount of three frames from the head of the input buffer to B1. The result is output (FIG. 9B).

The code amount difference calculating section 10 includes storage sections 2-1 to 2-1.
Difference between the code amount of each moving picture coded signal stored in 2-N and the decoding buffer free space corresponding to each of the storage units 2-1 to 2-N calculated by the decoding buffer free space calculating unit 9. And outputs the N difference values to the stuffing control unit 11.

FIG. 10 is a flowchart showing the operation of the stuffing control unit 11. First, the N difference values obtained by the code amount difference calculation unit 10 are respectively represented by Gi (i = 1 to
N), and Sp and Sm for obtaining the sum of the values are set to 0 (601). Next, it is checked whether or not each of G1 to GN is 0 or more (602). If it is 0 or more, it is added to Sp (603). If it is smaller than 0, the absolute value is added to Sm (604). Next, it is checked whether Sp is greater than 0,
If Sp is greater than 0, the process proceeds to steps 605 to 611 for calculating the number of stuffing bits, and if Sp is 0, the process ends without performing stuffing (612). Next, S
It is checked whether m is equal to or greater than Sp (605). If Sm is equal to or greater than Sp, it is checked whether each of G1 to GN is smaller than 0 (606), and if smaller, the number of stuffing bits for the moving picture coded signal corresponding to Gi is obtained by the following equation (607).

[0048]

(Equation 6)

If it is larger, the number of stuffing bits is set to 0 (608). If Sm is smaller than Sp, G
It is checked whether GN is smaller than 0 from 1 (60).
9) If the number is small, the number of stuffing bits for the video encoded signal corresponding to Gi is set as the absolute value of Gi (61).
0), and if larger, the number of stuffing bits is set to 0 (611).

As described above, in this embodiment, by performing stuffing on a coded video signal, if the number of generated bits of some coded video signals increases rapidly,
It is possible to prevent underflow that occurs in the decoding device when stuffing is not performed.

The method of determining the number of stuffing bits according to the present embodiment is merely an example. For example, the number of stuffing bits may be increased or decreased for byte alignment of a coded video signal, or a coefficient may be applied to Sp. Alternatively, the total number of stuffing bits may be increased or decreased, or Sp may be uniformly allocated to a moving picture coded signal having Sm smaller than 0. In the present embodiment, the code amount difference calculation unit 10
Although whether or not to perform stuffing is determined based on whether or not the value obtained in step 2 is 0 or more, a value other than 0 may be used.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described. FIG. 11 is a block diagram of an embodiment of the moving picture coding apparatus and the moving picture multiplexing apparatus according to the present invention. 11 is different from FIG. 8 in that the code amount difference calculation unit 10 outputs the difference value of the buffer to the quantization control unit 4. Others are the same as FIG. The operation of the above configuration will be described below. In the present embodiment, when the condition for performing the stuffing is satisfied in the third embodiment, the quantization control unit 4 controls the stuffing control of the encoding units 1-1 to 1-N to perform the stuffing. The value of the quantization width given to the quantization unit is reduced. That is, if the quantization width obtained by the quantization control unit 4 from the code amount output from the adder 8 is Q, the encoding unit 1
For example, for a coding unit that has been controlled to perform stuffing among −1 to 1−N, the quantization width is set to [k × Q].
And Where k is a positive number less than 1;
[N] represents the largest integer not exceeding n. The quantization control unit 4 receives the buffer difference value from the code amount difference calculation unit 10 and performs the same operation as in FIG. However, step 60
In steps 7 and 610, an operation of reducing the value of the quantization width is performed, and in steps 608 and 611, an operation of keeping the value of the quantization width as it is is performed.

As described above, in the present embodiment, instead of performing stuffing on a coded moving picture signal, the quantization width used in coding is reduced to increase the amount of codes, thereby generating a decoding device. The underflow can be prevented, and the image quality of the encoded moving image signal can be improved.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described. The device configuration is the same as that of the fourth embodiment. In the present embodiment, the quantization control unit 4
Increases the value of the quantization width given to the encoding unit that is not controlled to perform stuffing in the encoding units 1 to N in the third embodiment. That is, assuming that the quantization width obtained by the quantization control unit 4 from the code amount output from the adder 8 is Q, the encoding unit which is not controlled to perform stuffing among the encoding units 1 to N For example, the quantization width is [k × Q]. Here, k is a positive number greater than 1, and [n] represents the largest integer not exceeding n.

The quantization controller 4 includes a code amount difference calculator 10
The difference value of the buffer is input, and the same operation as in FIG. 10 is performed. However, in steps 607 and 610, an operation of increasing the value of the quantization width is performed, and in steps 608 and 611, an operation of maintaining the value of the quantization width is performed.

As described above, in the present embodiment, in contrast to the fourth embodiment, control is performed to reduce the generated code amount for a moving image signal on which stuffing has not been performed. The same effect as that of the fourth embodiment can be obtained. It should be noted that the fourth embodiment and the fifth embodiment are combined to increase the quantization width of a moving image signal having an increased amount of generated codes and to reduce the quantization width of other moving image signals. Is also good.

(Embodiment 6) Next, a sixth embodiment of the present invention will be described. FIG. 12 is a block diagram of an embodiment of the video encoding device and the video multiplexing device of the present invention. 12, the stuffing control unit 11 is removed from FIG. A multiplexing control unit 7 that performs necessary stuffing control on the multiplexing unit 3 outputs a stuffing code amount to the quantization control unit 4.

The operation of the above configuration will be described below. In the present embodiment, the quantization control unit 4
Are the accumulation units 2-1 to 2-N added by the adder 8
The quantization width is obtained based on the code amount of the moving picture coded signal stored in the.
In the present embodiment, the quantization control unit 4 executes Steps 601 to 604 in FIG. 10 to obtain Sp.
Next, this Sp is added to the sum of the code amounts of the encoded video signals stored in the storage units 2-1 to 2-N. Then, the quantization width is obtained in the same manner as in the first embodiment. The necessary stuffing is performed by the multiplexing unit 3 under the control of the multiplexing control unit 7. The quantization control unit 4 receives the stuffing code amount from the multiplexing control unit 7 and compares it with Sp. Then, Sp is adjusted so that the error between the cumulative value of Sp and the cumulative value of the stuffing code amount falls within a certain range. As described above, in the present embodiment, similar effects can be obtained with a simpler device configuration than in the third embodiment.

(Embodiment 7) Next, a seventh embodiment of the present invention will be described.

When the number of pixels constituting one screen of an input moving image signal is large, the processing speed may not be sufficient with one encoding device. One of the means for encoding such an input moving image signal is screen division encoding.

In the first to sixth embodiments, each encoder encodes a different moving image. However, the present invention can be applied to screen division encoding. FIG. 13 is a block diagram of an embodiment of the moving picture coding apparatus and the moving picture multiplexing apparatus according to the present invention. In FIG. 13, a screen division unit 12 is provided at a stage preceding the encoding units 1-1 to 1-N in FIG. The screen division unit 12
As shown in FIG. 14, the entire screen of the input moving image signal is divided into a plurality of partial screens, and the moving image signals of the partial screens are output to the encoding units 1-1 to 1-N. Encoding unit 1-1
1-N encodes the input video signal using the quantization width output from the quantization control unit 4. At this time, the encoding units 1-1 to 1-N are all given the same quantization width. The encoded video signals output from the encoding units 1-1 to 1-N are temporarily stored in the storage units 2-1 to 2-N. The code amounts of the encoded moving image signals stored in the storage units 2-1 to 2-N are all added by the adder 8, and then output to the quantization control unit 4. The quantization control unit 4 converts the code amount output from the adder 8 into a quantization width.

The frame code amount calculation section 6 includes a storage section 2-1.
In the moving picture coded signal stored in .about.2-N, the code amount of the frame including the bit transmitted to the multiplexing unit 3 first is obtained. The multiplexing control unit 7 stores the encoded video signals in the storage units 2-1 to 2-1 in the order of the number of bits of the value obtained by the frame code amount calculation unit 6 and in the order based on the screen division method.
The multiplexing unit 3 is controlled so as to be transmitted from each of the 2-N to the multiplexing unit 3. The multiplexing unit 3 multiplexes the coded moving image signal to form a coded signal of one screen based on the control of the multiplexing control unit 7 and outputs the multiplexed moving image signal at a constant bit rate.

As described above, in the present embodiment, when a screen is divided and coded, all partial screens are coded with the same quantization width, so that variations in image quality within the screen can be suppressed. it can.

In the present embodiment, one screen is divided into four in the horizontal direction. However, the division method may be not only the horizontal direction but also the vertical or horizontal / vertical combination. May be.

[0065]

As described above, according to the present invention, all the input moving pictures are compression-coded with the same quantization width.
The image quality of a plurality of output moving images can always be made uniform without evaluating the image quality of the encoded moving image. Further, even immediately after the image is rapidly complicated due to a scene change or the like, the image quality of the encoded moving image does not significantly deteriorate. Further, it is possible to generate a coded moving image signal in which the input buffer of the decoding device does not cause overflow or underflow.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video encoding device and a video multiplexing device according to a first embodiment of the present invention.

FIG. 2 is a view for explaining an embodiment of a method for obtaining a quantization width from a coding amount stored in a storage unit;

FIG. 3 is a flowchart of a moving image multiplexing method according to a first embodiment of the present invention;

FIG. 4 is a detailed flowchart of a method of obtaining the number of primary multiplex bits in step 204 of FIG. 3;

FIG. 5 is a detailed flowchart of a method of calculating the number of multiplexed bits in step 208 of FIG. 3;

FIG. 6 is a flowchart of a moving image multiplexing method according to a second embodiment of the present invention;

FIG. 7 is a view for explaining step 502 of calculating the lower limit value of the transmission amount in FIG. 6;

FIG. 8 is a block diagram of a video encoding device and a video multiplexing device according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram of a calculation performed by a decoding buffer free space calculation unit 9;

FIG. 10 is a flowchart showing the operation of the stuffing control unit 11;

FIG. 11 is a block diagram of a moving picture coding apparatus and a moving picture multiplexing apparatus according to fourth and fifth embodiments of the present invention.

FIG. 12 is a block diagram of a video encoding device and a video multiplexing device according to a sixth embodiment of the present invention.

FIG. 13 is a block diagram of a video encoding device and a video multiplexing device according to a seventh embodiment of the present invention.

FIG. 14 is a schematic diagram illustrating an example of a screen division method according to the seventh embodiment of the present invention.

FIG. 15 is a detailed diagram of an example of an encoding unit 1-1.

FIG. 16 is a detailed diagram of an example of an encoding unit 1-1.

FIG. 17 is a detailed diagram of an example of the multiplexing control section 7;

FIG. 18 is a block diagram of another multiplex encoding device and a moving image multiplexing device according to the first embodiment of the present invention.

FIG. 19 is a detailed diagram of an example of the multiplexing control section 7.

[Explanation of symbols]

 1-1 to 1-N encoding unit 2-1 to 2-N storage unit 3 multiplexing unit 4 quantization control unit 5 decoding delay time calculation unit 6 frame code amount calculation unit 7 multiplex control unit 8 adder 9 decoding Buffer free space calculation unit 10 Code amount difference calculation unit 11 Stuffing control unit 12 Screen division unit

Claims (23)

[Claims] 1. A moving picture coding apparatus for coding a plurality of moving picture signals, the apparatus further comprising quantization means for quantizing the moving picture signals with a predetermined quantization width, and A moving picture coding apparatus comprising: a plurality of coding means for coding a moving picture signal; and a quantization control means for simultaneously controlling a quantization width used by each of the quantization means. 2. The moving picture coding apparatus according to claim 1, wherein the quantization widths used by said quantization means are all the same value. 3. The image processing apparatus according to claim 1, further comprising a plurality of storage units for temporarily storing a plurality of encoded video signals in which the plurality of video signals are encoded, wherein the quantization control unit stores the encoded video signals in the storage unit. 2. The moving picture coding apparatus according to claim 1, wherein a quantization width used by each of the quantizing means is determined based on a total sum of code amounts of the plurality of coded moving picture signals. 4. A moving picture multiplexing apparatus for multiplexing a plurality of coded moving picture signals obtained by coding a moving picture signal, wherein each of the plurality of coded moving picture signals is temporarily stored. A plurality of storage means, a multiplexing means for multiplexing the plurality of encoded video signals stored in the plurality of storage means, and outputting the multiplexed video signals at a constant bit rate; Decoding delay time calculating means for calculating the time from when each specific bit is input to the decoding device to when it is decoded, and the plurality of moving picture encoded signals stored in the plurality of storing means, Frame code amount calculating means for calculating the code amount of the frame to which each of the specific bits belongs; and the plurality of storage means based on the calculation results of the decoding delay time calculating means and the frame code amount calculating means. A plurality of first codes, each of which is a code amount of the plurality of moving picture encoded signals input to the multiplexing unit from a stage;
A multiplexing control means for controlling the input code amount of the moving image. 5. A multiplexing control means, wherein a first parameter for calculating a plurality of first parameters, which is a ratio between a code amount calculated by the frame code amount calculation means and a time calculated by the decoding delay time calculation means, is obtained. Parameter generating means, second parameter generating means for obtaining a second parameter which is a sum of the plurality of first parameters, and a plurality of third parameters which are ratios of the plurality of first parameters to second parameters. Parameter generation means for obtaining the parameters of the plurality of encoded video signals stored in the plurality of storage means, and the plurality of first input codes based on the plurality of third parameters. 5. The moving picture multiplexing apparatus according to claim 4, further comprising multiplex code amount calculating means for calculating the amount. 6. A stored code amount calculating means for calculating a code amount of each of the moving picture coded signals stored in each of the storing means, and a specific bit of each of the moving picture coded signals is transmitted to a decoding device. A vacant capacity calculating means for calculating a vacant capacity of each input buffer of the decoding apparatus immediately before being inputted, wherein the multiplexed code amount calculating means converts a plurality of second input code amounts into the respective moving image coded signals; (1) the first input code amount obtained based on the third parameter;
(2) the code amount of the moving picture coded signal obtained by the accumulated code amount calculation means, and (3) the minimum value of the free space of the input buffer of the decoding device obtained by the free space calculation means, 6. The moving image multiplexing method according to claim 5, wherein a code amount of each of the moving image coded signals input from each of the storage units to the multiplexing unit is controlled using a plurality of second input code amounts. Device. 7. When the plurality of second input code amounts obtained by the multiplex code amount calculating means are different from the corresponding first code amount, the multiplex code amount calculating means sets the second input code amount. The moving picture multiplexing apparatus according to claim 6, wherein the amount is increased. 8. A moving picture coding method for coding a plurality of moving picture signals at the same time, wherein all the plurality of moving picture signals are coded using the same quantization width. Encoding method. 9. A moving picture coding method for coding a plurality of moving picture signals simultaneously, wherein a total sum of code amounts of a plurality of coded moving picture signals generated by coding the plurality of moving picture signals. And encoding using a quantization width based on a difference between an output code amount for temporarily storing and outputting the plurality of encoded video signals. 10. A video multiplexing method for storing and multiplexing a plurality of video encoded signals in a plurality of storage means,
A first step of calculating a time from when a specific bit of each of the plurality of encoded video signals is input to a decoding device having an input buffer to when it is decoded, and stored in the plurality of storage units. The second step of calculating the code amount of the frame to which each of the specific bits of the plurality of moving picture encoded signals belongs, based on the calculation results of the first step and the second step, A moving image multiplexing method, comprising: a third step of obtaining a plurality of multiplexed code amounts, each of which is a code amount with which each of the plurality of coded video signals is multiplexed. 11. The third step is a fourth step of obtaining a plurality of first parameters, which is a ratio between the code amount obtained in the second step and the time obtained in the first step. And a fifth step of obtaining a second parameter that is a sum of the first parameters; and a plurality of third parameters that are a ratio of the first parameter to the second parameter, The moving image according to claim 10, further comprising: a sixth step of obtaining each of the multiplexed signals; and a seventh step of obtaining the plurality of multiplexed code amounts based on each of the plurality of third parameters. Image multiplexing method. 12. An input multiplex code amount used for multiplexing the plurality of encoded video signals, wherein: (1) a multiplex code amount obtained based on the third parameter; The code amount of the coded video signal stored in the storage means and (3) the minimum value of the free space of the input buffer of the decoding device, and the multiplexing is performed using the input multiplexed code amounts. 12. The moving picture multiplexing method according to claim 11, wherein a code amount is controlled. 13. The moving picture multiplexing method according to claim 12, wherein the input multiplexing code amount is increased when at least one of the input multiplexing code amounts is different from the corresponding multiplexing code amount. Method. 14. A moving image multiplexing method for multiplexing a plurality of coded video signals, wherein a plurality of multiplexed code amounts corresponding to the plurality of coded video signals are set to zero in advance, A first step of calculating a frame code amount of a frame to which a specific bit of each of the plurality of encoded video signals belongs, and a second step of calculating a time until each of the plurality of encoded video signals is decoded. A second step, a third step of selecting a moving picture coded signal whose time until the decoding obtained in the second step is smaller than a predetermined time value, and a moving picture selected in the third step A fourth step of obtaining a plurality of first multiplexed code amounts based on the frame code amount of the coded signal; a fifth step of obtaining a sum of the plurality of first multiplexed code amounts; Multiple code amount A sixth step of adding the plurality of first multiplexed code amounts, and a seventh step of updating the predetermined time value, wherein the first to seventh steps are repeated, and If the sum of the first multiplexed code amounts is equal to or greater than a predetermined code amount, a plurality of second multiplexed code amounts are obtained and added to the plurality of multiplexed code amounts. A moving picture multiplexing method, comprising multiplexing the moving picture coded signal. 15. A moving picture multiplexing method for multiplexing a plurality of coded moving picture signals, wherein a code amount per frame of the plurality of coded moving picture signals not transmitted to a decoding device, A plurality of minimum transmission amounts necessary for avoiding underflow of a plurality of input buffers of the decoding device, based on a time until decoding of each of the plurality of encoded video signals for each frame, Determining a plurality of transmission code amount lower limit values based on the minimum transmission amount of the plurality of encoded video signals, and multiplexing the plurality of transmission code amount lower limit values before multiplexing the plurality of video coding signals. Video multiplexing method. 16. A moving picture coding apparatus for coding a plurality of moving picture signals, comprising: a quantizing means for quantizing the moving picture signal with a predetermined parameter; and a stuffing means for coding the quantized moving picture signal with a predetermined stuffing. Having both stuffing means to stuff by amount, and a plurality of encoding means for encoding the plurality of video signals, and a quantization control means for simultaneously controlling the parameters used by each quantization means,
A plurality of storage means for temporarily storing a plurality of moving image encoded signals in which the plurality of moving image signals are respectively encoded,
Multiplexing means for multiplexing the plurality of moving picture coded signals stored in the plurality of storage means and outputting at a constant bit rate, and a stuffing control means for controlling a stuffing amount used by each of the stuffing means, Virtual free space calculating means for obtaining free space of each of the input buffers after the predetermined time, when the plurality of moving image encoded signals are not input to the plurality of input buffers of the predetermined time decoding device. Wherein the quantization control means determines a parameter used by each of the quantization means based on the sum of the code amounts of the plurality of encoded video signals, and the stuffing control means The sum total of the code amount of the encoded moving image signal, the constant bit rate, and the number of encoded moving image signals stored in each of the storage units. A moving image coding apparatus for controlling each of the stuffing means based on a difference value between each code amount and each free space of each of the input buffers obtained by the virtual free space calculating means. . 17. A total sum of code amounts of a plurality of encoded video signals generated by encoding a plurality of video signals, and an output code amount for temporarily storing and outputting the plurality of encoded video signals. A video encoding method for simultaneously encoding the plurality of video signals using a predetermined quantization width based on a difference between the video data and the video data. When an encoded signal is obtained, and when the moving image encoded signals are not input to the plurality of input buffers of the decoding device for a predetermined time, the free space of each input buffer after the predetermined time is calculated for each of the moving images. For each of the moving picture coded signals, the respective buffer difference values obtained by subtracting the free space of each of the input buffers from the respective coded buffer occupancy amounts are smaller than a predetermined value.
A signal which does not affect the decoding of the code amount obtained by adding the buffer difference value larger than the predetermined value is distributed to the video encoded signal whose buffer difference value is smaller than the predetermined value and stuffing is performed. Moving image encoding method. 18. A moving picture coding apparatus for coding a plurality of moving picture signals, the apparatus further comprising quantization means for quantizing the moving picture signals with predetermined parameters, and further comprising: A plurality of encoding means for encoding a signal, a quantization control means for simultaneously controlling parameters used by each of the quantization means, and a plurality of moving picture encoded signals in which the plurality of moving picture signals are respectively encoded. A plurality of storage means for temporarily storing, a multiplexing means for multiplexing the plurality of encoded video signals stored in the plurality of storage means, and outputting the multiplexed video signal at a constant bit rate; Virtual free space calculating means for obtaining free space of each of the input buffers after the predetermined time when the plurality of moving picture coded signals are not input to the plurality of input buffers of the device; The control means controls the sum of the code amounts of the moving picture coded signals stored in the plurality of storing means, the constant bit rate, and the moving picture coded signals stored in each of the storing means. A moving picture code, wherein a parameter used by each quantization means is determined based on a difference value between a code amount and each free capacity of each input buffer obtained by the virtual free capacity calculation means. Device. 19. A sum of code amounts of a plurality of encoded video signals generated by encoding a plurality of video signals, and an output code amount for temporarily storing and outputting the plurality of encoded video signals. A video encoding method for simultaneously encoding the plurality of video signals using a predetermined quantization width based on a difference between the video data and the video data. When an encoded signal is obtained, and when the moving image encoded signals are not input to the plurality of input buffers of the decoding device for a predetermined time, the free space of each input buffer after the predetermined time is calculated for each of the moving images. For each of the moving picture coded signals, the respective buffer difference values obtained by subtracting the free space of each of the input buffers from the respective coded buffer occupancy amounts are smaller than a predetermined value.
A moving picture coding method comprising coding each moving picture signal using a quantization width smaller than the predetermined quantization width. 20. A sum of code amounts of a plurality of encoded video signals generated by encoding a plurality of video signals, and an output code amount for temporarily storing and outputting the encoded video signals. A video encoding method for simultaneously encoding the plurality of video signals using a predetermined quantization width based on a difference between the video data and the video data. When an encoded signal is obtained, and when the moving image encoded signals are not input to the plurality of input buffers of the decoding device for a predetermined time, the free space of each input buffer after the predetermined time is calculated for each of the moving images. For each of the moving picture coded signals, the respective buffer difference values obtained by subtracting the free space of each of the input buffers from each of the coded buffer occupancy amounts are larger than a predetermined value.
A moving picture coding method comprising coding each moving picture signal using a quantization width larger than the predetermined quantization width. 21. A sum of code amounts of a plurality of encoded video signals generated by encoding a plurality of video signals, and an output code amount for temporarily storing and outputting the encoded video signals. A video encoding method for simultaneously encoding the plurality of video signals using a predetermined quantization width based on a difference between the video data and the video data. When an encoded signal is obtained, and when the moving image encoded signals are not input to the plurality of input buffers of the decoding device for a predetermined time, the free space of each input buffer after the predetermined time is calculated for each of the moving images. For each of the video encoded signals, a buffer difference value obtained by subtracting the free space of each of the input buffers from the encoding buffer occupancy is obtained for each of the video encoded signals. Moving picture coding method in which the difference value is a value obtained by adding a predetermined value greater than the respective buffers difference value, and wherein the summing to the sum of the amount of codes. 22. The moving picture coding method according to claim 17, wherein the predetermined value is 0. 23. The moving picture coding apparatus according to claim 1, further comprising a screen dividing means for dividing an input moving picture signal into a plurality of moving picture signals at a stage preceding said plurality of coding means.