JPH11252556A - Coding and multiplexing system and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a coding and multiplexing system and its method with a simple configuration where transmission efficiency is considerably enhanced. SOLUTION: In this coding and multiplexing system, a multiplexer means 35 assigns an excess frequency band with respect to a setting rate of storage means 21A-21N and coding means 22A-22N for a frequency band for reading coded data from an 2nd buffer 34 corresponding to other coding means. In this coding and multiplexing method, an excess frequency band with respect to a setting rate of each channel is assigned for a frequency band for reading coded data from the 2nd buffer 34 of other channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order.

BACKGROUND OF THE INVENTION Prior Art (FIG. 8) Problems to be Solved by the Invention (FIG. 8) Means for Solving the Problems Embodiments of the Invention (1) Principle (FIGS. 1 and 2) 2) Configuration of transmission system according to this embodiment (FIGS. 3 to 3)
(FIG. 6) (3) Operation and effects of this embodiment (FIGS. 1 to 6) (4) Other embodiments (FIGS. 1 to 7) Effects of the invention

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding and multiplexing apparatus and an encoding and multiplexing method, and is suitably applied to, for example, a digital multi-channel broadcast transmission system.

[0004]

2. Description of the Related Art In recent years, communication satellites (C
S: Communication Satellite) has started digital multi-channel broadcasting. In the near future, a similar service is scheduled for a broadcasting satellite (BS) or a broadcasting system using a terrestrial wave or a cable.

[0005] In such digital multi-channel broadcasting, a video signal of each channel is subjected to digital compression processing on the transmission side, and the obtained coded data is subjected to a limited band of, for example, about 30 [bps]. This is hereinafter referred to as a broadcast band) and transmitted.

FIG. 8 shows an example of the configuration of the transmitting side in such a digital multi-channel broadcasting system. In such a transmission system 1, a plurality of encoding devices 2A to 2N are provided, and video signals S1A to S1N are provided to each of the encoding devices 2A to 2N.

Each of the encoding devices 2A to 2N converts the supplied video signals S1A to S1N into, for example, MPEG2 (Mo
ving Picture Experts Group Phase 2) Compression-encode at a specific set rate set in advance based on the standard, and transmit the obtained encoded data D1A to D1N to the multiplexer 3. The set rates of the encoding devices 2A to 2N are set so that the sum is within the broadcasting band of the digital multi-channel broadcasting.

[0008] In the multiplexing device 3, each encoding device 2
A plurality of buffers 4A to 4N provided corresponding to A to 2N, respectively, and a multiplexing control unit 5 for controlling reading and writing of each of the buffers 4A to 4N.
N to give encoded data D1A to D1N
Are sequentially taken into the corresponding buffers 4A to 4N.

The multiplexing control unit 5 monitors the amount of data in each of the buffers 4A to 4N via the control bus 6, and based on the monitoring result, time-divisionally distributes each of the buffers 4A to 4N without bias.
The encoded data D1A to D1N are read from N.

As a result, the coded data D1A to D1N read from each of the buffers 4A to 4N are provided to the transmitting unit 8 as transmission data D2 via the data bus 7, and the transmitting unit 8 performs QPSK (Quadrature Phase).
After predetermined signal processing such as Shift Keying (modulation) is performed, the signal is transmitted as a transmission signal S2 to the receiving side via the antenna 9 and a communication satellite (not shown) in order.

[0011] Such a video signal S for a plurality of channels.
In a so-called fixed rate method for encoding 1A to S1N at a preset rate for each channel, coded data D1A to D1N of each video signal S1A to S1N is stored in a broadcast band without requiring complicated control. There is an advantage that time division multiplexing is possible.

[0012]

At present, in digital multi-channel broadcasting, even a material such as a movie whose content is already determined is encoded and broadcast in real time. In this case, as a method of encoding and broadcasting a material whose content has already been determined, a method of encoding and storing the material in advance and reading it out according to the broadcast time can be considered. According to such a method, since the material can be encoded by multi-pass, there is an advantage that encoded data optimized in comparison with real-time encoding processing can be obtained.

However, in order to make full use of such advantages, the fixed rate system has its limitations. That is, in the fixed rate method, dummy data is added to a pattern having a small code amount in order to fix the rate of each channel.

For this reason, in the fixed-rate system, a plurality of variable-rate coded data having already determined code amounts and coded data obtained by real-time coding are multiplexed within a limited broadcast band with high transmission efficiency. There was a difficult problem.

The present invention has been made in view of the above points, and is intended to propose a coded multiplexing apparatus and a coded multiplexing method having a simple configuration capable of significantly improving transmission efficiency. is there.

[0016]

According to the present invention, there is provided an encoding / multiplexing apparatus comprising a plurality of first buffers each storing first encoded data read from a storage means. A plurality of second buffers for respectively storing second encoded data obtained by compression-encoding the video signal output from the corresponding encoding means;
By reading the first and second encoded data stored in each of the first and second buffers in a time-division manner at a specific setting rate preset for the corresponding storage means or encoding means, respectively. Multiplexing means for multiplexing each of the first and second encoded data, wherein the multiplexing means assigns a surplus bandwidth to the set rates of the storage means and the encoding means to correspond to other encoding means. To read the second encoded data from the second buffer.

As a result, in this encoding and multiplexing apparatus, the band control for each channel can be dynamically performed, and the temporal change of the difficulty in encoding can be absorbed over each channel. Can be.

According to the present invention, in the coding and multiplexing method, the first coded data for one or a plurality of channels previously compressed and coded and stored are read out and stored in different first buffers. , Input 1
Alternatively, a first step of compressing and encoding video signals for a plurality of channels and storing the obtained second encoded data in different second buffers, respectively, and storing the encoded data in the first and second buffers, respectively. The second encoded data is multiplexed by reading the first and second encoded data in a time-division manner at a specific set rate preset for each channel. In the second step, the surplus bandwidth for the set rate of each channel is allocated to reading of the second encoded data from the second buffer of another channel.

As a result, according to this encoding and multiplexing method,
Band control for each channel can be dynamically performed, and a temporal change in difficulty in encoding can be absorbed over each channel.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Principle As shown in FIG. 1, a video signal S10 for a plurality of channels is provided.
A to S10N are respectively different from encoding devices 11A to 11
N to obtain the respective encoded data D1.
For a multiplexing system 10 that multiplexes the signals 0A to D10N within a predetermined transmission band by the multiplexing device 12, virtual buffers 13A to 13A to coded devices 11A to 11N and the multiplexing device 12, respectively. Consider the case where 13N is provided.

In this case, the coded data D10A to D10 from each of the coding devices 11A to 11N to the buffers 13A to 13N.
In writing 10N, one picture unit is set as an access unit, and the access unit is instantaneously written. The writing cycle is set to each of the encoding devices 11A to 11A.
It is assumed that the picture period is the picture cycle of the video signals S10A to S10N input to the 1N. Also, each of the encoding devices 11A to 11A
In N, it is assumed that a unique coding rate is set in advance so that the total does not exceed the broadcasting band of the digital multi-channel broadcasting.

If the encoding devices 11A to 11N are the writing times of arbitrary pictures n to the buffers 13A to 13N based on the video signals S10A to S10N,
Buffers 13A-13 just before writing the picture n
The data occupancy of N is C ₀ [bit], the code amount of picture n is C [n] [bit], and picture n is a buffer 13A to 13A.
Tw [n] [s] is the time from writing to N to reading of the head (hereinafter referred to as a waiting time), and the set rate of the encoding devices 11A to 11N is R ₀ [bps
], And if the picture period is Tf [s], the waiting time Tw [n + 1] of the following picture n + 1 is given by the following equation.

(Equation 1) Given by

The waiting time Tw [n + 1] is given by the following equation.

(Equation 2) If

(Equation 3) Encoded data D10A to D1 for the code amount A given by
0N to can be extra transmitted within a set rate R ₀ for the encoding device 11A to 11N.

Accordingly, in this case, the coding device 11A is provided between the writing time of the picture n and the writing time of the next picture n + 1 (corresponding to one picture cycle).
The reading rate of the encoded data D10A to D10N from the buffers 13A to 13N corresponding to

(Equation 4) By setting as follows, the encoding device 11A
Of the set rates R ₀ assigned to 11N

(Equation 5) Is defined as a surplus band (hereinafter, referred to as a gap band), and this is referred to as other coding devices 11A to 11N.
Can be sorted.

In this case, however, the coded data D10 is transmitted from the buffers 13A to 13N corresponding to the other coding devices 11A to 11N by such a gap band allocating operation.
When A to D10N are read continuously at a high rate,
Overflow may occur in the buffer on the receiving side. Therefore, in order to avoid such an overflow, it is necessary to provide a limit on the amount of codes to be allocated to the gap bands of the other encoding devices 11A to 11N (hereinafter, this will be referred to as a congestion limit).

In this case, a buffer 13A of a certain picture n
-13N, the picture n and a plurality of consecutive pictures n-5 to n-
FIG. 2 shows the relationship between the waiting time Tw [i] (i = n-5 to n) and the transmission time from the writing of one coded data D10A to D10N to the corresponding buffers 13A to 13N until the decoding. It is assumed that the state shown in FIG.

In this state, the maximum value of the code amount that can be distributed to another gap band by the writing time of the next picture n + 1 is, as shown in FIG. 2B, the picture n that has not reached the decoding time. All the waiting times from −5 to n can be estimated retroactively and obtained as a value whose minimum value is zero.

Actually, the maximum value Z _max [bit] of the code amount
Is the oldest picture number that has not reached the decryption time
The waiting time Tw [n] of the picture n is expressed by the following equation as Nb.

(Equation 6) And the waiting time Tw [i] of each picture i (i = Nb to n-1) up to the picture number Nb that has not reached the previous decoding time is given by

(Equation 7) By the following equation,

(Equation 8) Can be obtained as

On the other hand, in order to avoid underflow of the buffer on the receiving side, each of the encoding devices 11A to 11A
It is necessary to limit the code amount per picture for N.

Assuming that a certain encoding apparatus 11A to 11N is the writing time of the picture n, the maximum value C _max [bi of the code amount of the picture Nf several frames after the picture n is actually assumed.
t] is the encoded data D10A to D10N of the picture n
C ₀ The data occupancy quantity of code buffer immediately before writing
[Bit], the code amount of the picture n is C [n] [bit], the waiting time of the picture n is Tw [n] [s], and its encoding device 11
R ₀ [bit] setting rate for A～11N, Tf [s] a picture period, the offset period as T ₀ [s], the following equation to picture n + 1 of the waiting time Tw [n + 1]

(Equation 9) The waiting time Tw [i] of the subsequent picture i (i ≧ n + 2) is calculated by the following equation.

(Equation 10) By the following equation,

[Equation 11] Can be obtained as

(2) Configuration of Transmission System According to the Present Embodiment FIG. 3 in which parts corresponding to those in FIG. 7 are denoted by the same reference numerals, shows the configuration of a digital multi-channel broadcast transmission system 20 according to the present embodiment. And a plurality of data storage devices 21A to 21N and encoding devices 22A to 22N are provided.

Each of the data storage devices 21A to 21N includes a data storage unit 23, a control unit 24, a format conversion unit 25, and a buffer 26.
The data storage unit 23 stores encoded data D20 obtained by optimally encoding a video signal of a broadcast material in advance.

The encoded data D20 is sent to the control unit 2
4 at a predetermined timing under the control of
After the data is converted into a predetermined format in the format conversion unit 25, the data is stored as encoded data D21 in the buffer 26 at a picture cycle and one picture at a time under the control of the control unit 24. You.

At this time, the control unit 24 receives the reference time information (STC: System T) of a 24-hour cycle provided from the reference time management unit 28 of the multiplexer 27 via the first control bus 29.
imeClock) Based on D22, the time when the encoded data D21 of the picture n is written to the buffer 26 is tp [n].
, The buffer size of the receiving side is B, and the maximum rate of the encoded data D21 output from the format conversion unit 25 (hereinafter referred to as the set rate of the data storage devices 21A to 21M) is _R0.

(Equation 12) To calculate the decoding time of the picture n, and decoding time information (DTS: Decoding T
ime Stamp) [n] is the encoded data D2 of the picture n
1, while replacing a time reference value (PCR: Program Clock Reference) added to the encoded data D21 with a time obtained based on the reference time information D22 at that time. Is stored in the buffer 26 together with the encoded data D21.

At this time, the control unit 24 sets the buffer 26 immediately before writing the encoded data D21 of the picture n.
4 based on the data occupation amount C ₀ , the set rate (highest rate) R _{0 of} the channel, and the code amount C [n] of the picture n given from the format converter 25. By executing the arithmetic program, the code amount A that can be transmitted extra within the range of the set rate R ₀ is obtained, and this is calculated as the surplus transmission code amount information D23A to
The data is transmitted to the multiplexing control unit 31 of the multiplexing device 27 via the second control bus 30 as D23N.

On the other hand, in each of the encoding devices 22A to 22N, the encoding unit 32, the encoding control unit 33, and the buffer 3
4 and supplied video signals S1A-S
1N is input to the encoding unit 32, respectively.

At this time, the encoding control unit 33 sets the buffer 3
4 based on the data occupancy amount information D24 given from, the code amount of each picture up to the picture n, and the set rate _{R0 of the} channel by executing the code amount limit value calculation program shown in FIG. , The control value C _max of the code amount per picture is calculated, and
20 is given to the encoding unit 32.

Thus, the encoding section 32 compresses and encodes the input video signals S1A to S1N with a code amount not exceeding the limit value _Cmax obtained based on the control signal S20, and performs coding control on the obtained coded data D25. Under the control of the unit 33, the buffer 3 collectively collects one picture at a cycle of one picture.
4 is stored.

At this time, the encoding control unit 33 sends the first control bus 29 from the reference time management unit 28 of the multiplexer 27.
Calculates the time to decode the picture n based on the reference time information D22 given through
The decoding time information DTS [n] representing the time is replaced with the DST previously added to the encoded data D25 of the picture n, and the time reference value (STC) added to the encoded data D25 is The time is replaced with the time obtained based on the reference time information D22, and these are stored in the buffer 34 together with the coded data D25.

Further, at this time, the encoding control unit 33 sets the data occupancy of the buffer 34 immediately before writing the encoded data D25 of the picture n and the encoding devices 22A to 22A.
Based on the set rate R _{0 of} 2N and the code amount C [n] of the picture n given from the encoding unit 32, the code amount that can be transmitted extra by executing the surplus transmission code amount calculation program shown in FIG. A is obtained and transmitted to the multiplexing control unit 31 of the multiplexing device 27 via the second control bus 30 as surplus transmission code amount information D26A to D26N.

Further, the coding control unit 33 also controls the data occupation amount C ₀ of the buffer 34 immediately before writing the coded data D 25 of the picture n necessary for obtaining the maximum value Z _max of the congestion limit, and Information such as the code amount C [n] and the set rate R _{0 of the} channel (hereinafter referred to as congestion limit value calculation information) D27A to D27N of the multiplexer 27 via the second control bus 30 It is sent to the multiplexing control unit 31.

In the multiplexing control unit 31, the control unit 24 of each of the data storage devices 21A to 21N and each of the encoding devices 2
Surplus transmission code amount information D23A to D23N, D26A to
Which of the data storage devices 21A to 21A is based on D26N.
N, and / or how much gap band is generated in the encoding devices 22A to 22N, and is given from the corresponding encoding control unit 33 for each of the encoding devices 22A to 22N in which no gap band is generated. The data storage device 21 based on the congestion limit value calculation information D27A to D27N
A~21N and or other encoder 22A~22N convergence limit value calculation program a maximum value Z _max of the amount of codes to be distributed to the gaps band 6 of the sub connexion is calculated.

Then, the multiplexing control section 31 determines, based on the result of this operation, the video signals S1A to S1A by the channels (the encoding devices 22A to 22N) in which no gap band is generated.
1N corresponds to a channel for which real-time encoding is performed), and code amounts A _{1 to} A to be allocated to other channels, respectively.
_m , each channel in which a gap band has occurred (the channel from which stored data is read by the data storage devices 21A to 21N, and the video signal S by the encoding devices 22A to 22N).
1A to S1N correspond to real-time encoded channels) and the code amounts Z _{1 to} Z _m to be distributed from other channels to the following formulas:

(Equation 13) Is determined so as to satisfy the following conditions.Up to the writing time of the subsequent picture n + 1, based on the determination result, for a channel in which no gap band occurs, the set rate of the channel is set to R ₀ , the picture cycle is set to Tf, and the other is set to Tf. equation code amount to distribute to the channel as a ₁ to a _m

[Equation 14] , And for a channel in which a gap band is generated, the following equation is used, where R _{0 is} the set rate of the channel, Tf is the picture cycle, and Z _{1 to} Z _m is the code amount distributed from the other channels.

(Equation 15) The buffer 26 of each data storage device 21A-21N and the buffer 34 of each encoding device 22A-22N at each rate of
, The encoded data D21 and D25 are read out in a time-division manner.

The coded data D21 and D25 read out in a time-division manner are thereafter transmitted to the transmission unit 8 via the data bus 35, and after being subjected to predetermined signal processing in the transmission unit 8, , As a transmission signal S2 to the receiving side via the antenna 9 and a communication satellite (not shown).

As described above, in the transmission system 20, the video signal which has been encoded in advance or the video signal S1A to S1N which has not been encoded can be efficiently multiplexed and transmitted to the receiving side. .

(3) Operation and effect of the present embodiment In the above configuration, in the transmission system 20, in each of the data storage devices 21A to 21N, the data storage unit 23
The encoded data D21 stored in the encoding device 22A is read out and stored in the buffer 26.
In N, the coded data D25 obtained by the real-time coding is stored in the buffer 34, while each of the data storage devices 21A to 21N and each of the coding devices 22A to 22N are stored.
Calculates a gap band corresponding to the set rate of the channel, and based on the calculation result, a reading rate of the coded data D21 and D25 from the buffers 26 and 34 of the channel in which the gap band has occurred (corresponding to the set rate of the channel). ), And distributes the reading of the encoded data D21 and D25 from the buffers 26 and 34 of other channels in which no gap band is generated.

Therefore, in the transmission system 20, even when a gap band occurs in any of the channels, the gap band can be effectively used without adding dummy data unlike the conventional fixed rate system.

Further, in this transmission system 20, each of the encoding devices 22A to 22N merely specifies the code amount per picture and does not cause overflow and underflow in the buffer on the receiving side. Since each picture can be decoded at the same decoding time, synchronization control between channels can be easily performed.

According to the above configuration, the multiplexing device 27 operates at the preset rate at each of the data storage devices 21A-2A.
The encoded data D21 and D25 are transmitted from the 1N buffer 26 and the buffers 34 of the encoding devices 22A to 22N, respectively.
While the data storage devices 21A to 21N and / or the encoding devices 22A to 22N dynamically detect gaps in bands that are not required, and replace the
By assigning the band to ２２22N, the band of each channel can be dynamically controlled, and a transmission system that can significantly improve the transmission efficiency can be realized.

(4) Other Embodiments In the above-described embodiment, a case has been described in which the present invention is applied to the transmission system 20 for digital multi-channel broadcasting. However, the present invention is not limited to this. In addition, the present invention can be widely applied to an encoding and multiplexing apparatus used for various other systems.

In the above-described embodiment, the coding control unit 33 of each of the coding devices 22A to 22N uses the code amount limit value calculation program shown in FIG. 4 to execute the code amount limit value C _max for each picture. Has been described, but the present invention is not limited to this. The limit value C _max of the code generation amount may be calculated by another arithmetic program.

Further, in the above embodiment, the control unit 24 of each of the data storage devices 21A to 21N and the coding control unit 33 of each of the coding devices 22A to 22N are based on the surplus transmission code amount calculation program shown in FIG. Although the case where the extra code amount A that can be transmitted at the set rate is calculated by using the calculation method described above, the present invention is not limited to this. A may be calculated.

Further, in the above-described embodiment, the multiplexing control unit 31 of the multiplexing device 27 controls the other coding devices 22A to 22A based on the congestion limit value calculation program shown in FIG.
The case where the maximum value Z _max of the code amount allocated to N is calculated has been described. However, the present invention is not limited to this.
It may be calculated the maximum value Z _max of the amount of codes to be distributed to 2A～22N.

Further, in the above-described embodiment, the multiplexing control unit 31 of the multiplexing device 27 sets the surplus portion of the band allocated to each channel from the writing time of the picture n to the writing time of the next picture n + 1. Has been described in which the readout rate from the corresponding buffers 26 and 34 of each channel is dynamically controlled, but the present invention is not limited to this. The multiplexing control unit 31 controls the data occupation amount of the buffer 26 of each of the data storage devices 21A to 21N and the encoding devices 22A to 2N.
The data occupancy of the 2N buffer 34 is sequentially monitored, and when the buffers 26 and 34 become empty, the data storage devices 21A to 21N and the encoding devices 22A to 22N are used.
The band (set rate) allocated to N may be allocated to the other encoding devices 22A to 22N.

Further, in the above-described embodiment, the case where each of the data storage devices 21A to 21N is constructed as shown in FIG. 3 has been described. However, the present invention is not limited to this, and is shown in FIG. As described above, one data storage unit 21A 'to 21N' is provided with one data storage unit 23 and one control unit 24, and a plurality of format conversion units 25A to 25N and a plurality of buffers 26A to 26N are provided. Encoded data D20 stored in
Are shifted in time, and each format converter 25A to 25N
May be subjected to a format conversion process.
By doing so, the present invention can be applied to a system for providing near-on-demand services.

[0057]

As described above, according to the present invention, in a coding and multiplexing apparatus, a plurality of first buffers for storing first coded data read from storage means and corresponding codes are stored. A plurality of second buffers for respectively storing second encoded data obtained by compression-encoding the video signal output from the encoding means, and the first and second buffers respectively stored in the first and second buffers. Multiplexing means for multiplexing each of the first and second coded data by reading out the coded data in a time-division manner at a specific set rate preset for the corresponding storage means or coding means. And the multiplexing means allocates the surplus bandwidth to the set rates of the storage means and the encoding means to read the encoded data from the second buffer corresponding to the other encoding means. By the the, you can perform bandwidth control for each channel dynamically, thus possible to realize a coding multiplexer which can dramatically improving the transmission efficiency.

Further, according to the present invention, in the coding and multiplexing method, the first coded data of one or a plurality of channels, which have been compressed and coded in advance, are respectively read and stored in different first buffers. In addition, a first step of compressing and encoding an input video signal for one or a plurality of channels and storing the obtained second encoded data in different second buffers, respectively, and a first step and a second step, respectively. By reading the first and second encoded data stored in the buffer in a time-division manner at a specific set rate preset for each channel, each of the first and second encoded data is read out. A second step for multiplexing is provided. In the second step, a surplus band for the set rate of each channel is converted to a second code from a second buffer of another channel. Reduction by the the so distributes the read data, the bandwidth control for each channel dynamically can be performed, thus possible to realize a coding multiplexing method that can dramatically improving the transmission efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an encoding and multiplexing system used for explaining the principle of the present invention.

FIG. 2 is a schematic diagram for explaining congestion control;

FIG. 3 is a block diagram showing a configuration of a transmission system according to the present embodiment.

FIG. 4 is a schematic diagram illustrating a code amount control value calculation program.

FIG. 5 is a schematic diagram illustrating a surplus transmission code amount calculation program.

FIG. 6 is a schematic diagram illustrating a congestion limit value calculation program.

FIG. 7 is a block diagram for explaining another embodiment.

FIG. 8 is a block diagram showing a configuration of a conventional fixed-rate transmission system.

[Explanation of symbols]

20 transmission system, 21A-21N data storage device, 22A-22N encoding device, 23 data storage unit, 24 control unit, 25 format conversion unit, 26, 34 buffer , 27... Multiplexing unit, 28
... Reference time management unit 31 multiplex control unit 32
Encoding unit, 33 ... Encoding control unit, 34 ... Buffer,
35 multiplexing device 36 reference time management unit 39
... Multiplexing control unit, S1A to S1N ... Video signal, D2
0, D21, D25 ... coded data, D22 ... reference time information, D23A to D23N, D26A to D26N ...
... surplus transmission code amount information, D27A to D27N ... congestion limit value calculation information.

Claims (7)

[Claims] 1. One or a plurality of storage means for storing first encoded data which has been compressed and encoded in advance, and said storage means are provided in correspondence with each of said storage means, and are stored in the corresponding storage means. Reading means for reading out the first coded data, respectively; and reading means provided in correspondence with each of the reading means, respectively storing the first coded data read from the storage means by the corresponding reading means. A first buffer for compressing and encoding each of the input video signals;
Or, a plurality of encoding means, and second encoded data which are provided in correspondence with each of the encoding means and are obtained by compression-encoding the video signal output from the corresponding encoding means, respectively. A second buffer and the first and second coded data stored in the first and second buffers, respectively, are stored in a unique preset for the corresponding storage means or the coding means. Multiplexing means for performing multiplexing by reading in a time-division manner at a set rate, wherein the multiplexing means converts a surplus bandwidth of the storage means and the encoding means with respect to the set rate into another encoding method. The coding / multiplexing apparatus according to any one of claims 1 to 3, wherein the sorting is performed for reading the second coded data from the second buffer. 2. The method according to claim 1, wherein the multiplexing means limits the amount of reading of the encoded data from each of the buffers corresponding to the other encoding means so that the buffer on the decoding side does not overflow. The coding and multiplexing device according to claim 1. 3. An encoding apparatus according to claim 1, wherein each of said encoding means encodes the input video signal by limiting a code amount per picture so that a buffer on a decoding side does not underflow. 2. The coding and multiplexing device according to claim 1. 4. A plurality of said reading means and a plurality of first buffers respectively corresponding to said reading means are provided for one said storing means, and each said reading means is provided with a corresponding one of said storing means. 2. The coding and multiplexing apparatus according to claim 1, wherein the same coded data is read out from the means at a staggered time, and the read out coded data is stored in the corresponding first buffer. 5. A video signal for one or a plurality of channels which is read out and stored in a different first buffer, respectively, and reads out the first coded data for one or a plurality of channels which have been compressed and stored in advance. A first step of compressing and encoding the obtained second encoded data in different second buffers, respectively; and a first step of storing the first and second stored data in the first and second buffers, respectively. A second step of multiplexing each of the first and second encoded data by reading out the two encoded data in a time-division manner at a specific set rate preset for each of the channels. In the second step, a surplus band of each of the channels with respect to the set rate is converted into the second coding from the second buffer of another channel. Encoding multiplexing method characterized by allocating a reading of over data. 6. The second step is characterized in that the amount of reading of the encoded data from each of the buffers corresponding to the other encoding means is limited so that the buffer on the decoding side does not overflow. The coding and multiplexing method according to claim 5, wherein 7. The first step is characterized in that the video signal is encoded by limiting the code amount per picture for each channel so that the buffer on the decoding side does not underflow. The coding and multiplexing method according to claim 5.