JPH11252557A - Encoding and multiplexing device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transmission efficiency by allowing a multi-valueing means to allocate a surplus band for the set rate of an encoding means to reading of encoded data from a buffer corresponding to another encoding means. SOLUTION: The multi-valueing means allocates the surplus band for the set rate of the encoding means to reading of encoded data from the buffer corresponding to another encoding means. In a transmission system 30, e.g. a multiplexer 35 assigns a previously set band to encoders 41A to 41M respectively provided for respective hierarchical encoders 31A to 31N. On the other hand, the multiplexer 35 dynamically detects gaps in a band which is not required by the encoders 41A to 41M to allocate these gaps to the encoders 41A to 41M having no-margin, thereby the band of each layer is dynamically controlled to improve transmission efficiency.

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. 7) Problems to be Solved by the Invention Means for Solving the Problems Embodiments of the Invention (1) Principle (FIGS. 1 and 2) (2) Present Embodiment Configuration of Transmission System According to Embodiment (FIGS.
(FIG. 6) (3) Operation and effects of the present embodiment (FIGS. 1 to 6) (4) Other embodiments Effects of the present 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. 7 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 hierarchical coding devices 2A to 2N are provided, and each of the hierarchical coding devices 2A to 2N is provided.
HDTV (High Definition Televisio)
Video signals S1A to S1N of the n) system are provided.

[0007] The information layering unit 3 of each of the layer coding devices 2A to 2N sequentially filters and sub-samples the supplied video signals S1A to S1N, thereby hierarchically converting images having different resolutions. A plurality of video signals are created and supplied to the corresponding layer encoding units 4A to 4M as layer video signals S2A to S2M in the order of lower frequency components (that is, in order from the image having the lower resolution).

Each of the layer coding units 4A to 4M calculates the difference between the layer video signals S2A to S2M via the data bus 5 so that the video signals S2A to S2M are transmitted to the layer coding unit 4A.
The layer video signal S2A having the lowest frequency component obtained by down-sampling 1A is provided, and only the residual component obtained by subtracting the frequency component of the layer video signal S2A from the layer video signal S2B is provided to the layer encoding unit 4B. Can be In the same manner, only the residual component of the frequency component between the lower layer and the lower layer (that is, the portion obtained by subtracting a correlated image) sequentially becomes closer to the upper layer.
４4M.

Thus, each of the layer encoding units 4A to 4M
A residual component obtained by subtracting a correlation component for each layer from the given video signals S2A to S2M is, for example, MP
Based on the EG2 (Moving Picture Experts Group Phase 2) standard, compression encoding is performed at a preset specific set rate, and the obtained layer encoded data D2A to D2M are transmitted to the corresponding layer buffers 6A to 6M, respectively.
Note that each layer encoding unit 4A in each of the encoding devices 2A to 2N
The set rates of .about.4M are set so that the total sum falls within the broadcasting band of the digital multi-channel broadcasting.

Each of the layer buffers 6A to 6M sequentially takes in the supplied layer coded data D2A to D2M under the control of the hierarchical coding and multiplexing unit 8.

The hierarchical multiplexing control unit 8 monitors the amount of data in each of the layer buffers 6A to 6M via the control bus 7,
Based on the monitoring result, the layer coded data D2A to D2M are time-divided from each of the layer buffers 6A to 6M without bias.
Are respectively read.

As a result, each of these layer buffers 6A to 6A
Layer encoded data D2A to D2M read from M
Is provided to the multiplexer 10 as encoded data D3A via the data bus 9.

In the multiplexing device 10, a plurality of multiplexing buffers 11A to 11N provided corresponding to the respective hierarchical coding devices 2A to 2N, and each multiplexing buffer 1 is provided.
A multiplexing control unit 13 for controlling reading / writing of 1A to 11N, and sequentially takes in coded data D3A to D3N provided from each of the hierarchical coding devices 2A to 2N into the corresponding multiplexing buffers 11A to 11N.

The multiplexing control unit 13 monitors the amount of data in each of the multiplexing buffers 11A to 11N via the control bus 12, and based on the monitoring result, distributes the data from each of the multiplexing buffers 11A to 11N in a time-sharing manner without bias. Encoded data D3A to D3
N is read out. As a result, the encoded data D read from each of these multiplex buffers 11A to 11N.
3A to 3N are transmission data D via the data bus 14.
4 is given to the transmitting unit 8 and the transmitting unit 8
After predetermined signal processing such as PSK (Quadrature Phase 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.

The video signal S for such a plurality of channels
In a so-called fixed rate method for encoding 1A to S1N at a preset rate for each channel, encoded data D3A to D3N obtained by layering the video signals S1A to S1N without requiring complicated control. Can be time-division multiplexed in the broadcast band.

[0016]

However, according to the above-mentioned fixed rate method, the video signal S1 of each channel is not used.
Since A to S1N are always subjected to digital compression processing at a fixed rate, there is a problem that image quality degradation in a complicated picture or scene change becomes extremely large. In addition, according to the fixed rate method, it is necessary to add dummy data in order to keep the output rate constant even for a pattern that does not require a large number of codes, resulting in a problem that transmission efficiency is deteriorated.

To solve this problem, a statistical multiplexing method has been proposed as another method for encoding and multiplexing video signals S1A to S1N for a plurality of channels. This statistical multiplexing method detects the maximum difficulty of encoding each video signal, allocates more bands to video signals having the greater difficulty, and sets the total value of the encoding rate to the digital multi-channel. This is a method in which the encoding rate of each encoding device is set so as to be within the broadcast band of the broadcast.

According to such a statistical multiplexing method,
As described above, since the coding rate is allocated based on the difficulty of the picture for each channel, the transmission efficiency is better than the fixed rate method because the dummy data does not need to be added, and the image quality between the channels is averaged. There is an advantage that even difficult video can be transmitted with relatively high image quality.

However, according to such a statistical multiplexing method, since the amount of encoded data varies depending on the picture, the same video signals S1A to S1N are hierarchically encoded as in the transmission system 1 shown in FIG. Therefore, in the case of broadcasting on multiple channels, synchronization management between the channels becomes complicated, and there is a problem that it is difficult to make full use of the advantages of dynamic band control.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a coding multiplexing apparatus and a coding multiplexing method capable of significantly improving transmission efficiency.

[0021]

According to the present invention, there is provided a hierarchal means for converting an input video signal into a plurality of layer video signals having hierarchically different resolutions. After each layer video signal output from the means is compression-coded by a different coding means, the obtained coding data is multiplexed in a coding and multiplexing apparatus, which is provided corresponding to each of the coding means. Buffer for storing the encoded data output from the corresponding encoding means, and time-division of the encoded data stored in each buffer at a specific set rate preset for the corresponding encoding means. And multiplexing means for multiplexing each encoded data by reading the encoded data. And to distribute the readout of the encoded data from the corresponding buffer to other coding means.

As a result, in the coding and multiplexing apparatus, the band control for each layer can be dynamically performed, and the temporal change of the code amount at the time of coding can be absorbed between the layers. it can.

Also, in the present invention, after the input video signal is converted into a plurality of layer video signals having different hierarchies in resolution, each layer video signal is compression-encoded,
In an encoding and multiplexing method for multiplexing each of the obtained encoded data, a first step of storing the encoded data of each layer in a buffer and an encoded data stored in each buffer are respectively performed by a buffer. A second step of multiplexing each piece of encoded data by reading in a time-division manner at a specific set rate preset for each layer is provided. In the second step, a surplus bandwidth with respect to the set rate of the layer is provided. For reading encoded data from a buffer corresponding to another layer.

As a result, in this coding and multiplexing method, the band control for each layer can be dynamically performed, and the temporal change of the code amount at the time of coding can be absorbed between the layers. it can.

[0025]

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 S20 for a plurality of channels is provided.
A to S20N are respectively different from encoding devices 21A to 21
N to obtain the encoded data D2.
0A to D20N are multiplexed by a multiplexing device 22 into a predetermined transmission band.
Consider a case where virtual buffers 23A to 23N are provided between the encoding devices 21A to 21N and the multiplexing device 22, respectively.

In this case, the encoded data D20A to D20 from each of the encoding devices 21A to 21N to the buffers 23A to 23N.
In the writing of 20N, one picture unit is set as an access unit, and the access unit is instantaneously written, and the writing cycle is set to each of the encoding devices 21A to 21A.
It is assumed that this is the picture cycle of the video signals S20A to S20N input to the 1N. Also, each of the encoding devices 21A to 21A
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 21A to 21N are at the writing time of an arbitrary picture n to the buffers 23A to 23N based on the video signals S20A to S20N,
Buffers 23A-23 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 23A to 23A.
Tw [n] [s] is the time from writing to N until the head is read (hereinafter referred to as waiting time), and R ₀ [bps] to the set rate of the encoding devices 21A to 21N.
], 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 D20A to D2 for the code amount A given by
0N to can be extra transmitted within a set rate R ₀ for the encoder 21A through 21N.

Therefore, in this case, the encoding devices 21A to 21A to 21n are written from the writing time of the picture n to the writing time of the next picture n + 1 (corresponding to a picture cycle).
The read rate of the coded data D20A to D20N from the buffers 23A to 23N corresponding to 21N is represented by the following equation.

(Equation 4) By setting as follows, the encoding device 21A
Of the set rates R ₀ allocated to 21N, the following equation

(Equation 5) Can be allocated to the other encoding devices 21A to 21N as a surplus band (hereinafter referred to as a gap band).

In this case, however, the coded data D20 is transmitted from the buffers 23A to 23N corresponding to the other coding devices 21A to 21N by such a gap band allocating operation.
When A to D20N are read continuously at a high rate,
Overflow may occur in the buffer on the receiving side. Therefore, in order to avoid such overflow, it is necessary to set a limit on the amount of codes to be allocated to the gap band (hereinafter, this is referred to as a congestion limit).

In this case, a buffer 23A of a certain picture n
-23N, the picture n and a plurality of consecutive pictures n-5 to n-
FIG. 2 shows the relationship between each waiting time Tw [i] (i = n-5 to n) and the transmission time from when the first coded data D20A to D20N are written to the corresponding buffers 23A to 23N until they are decoded. It is assumed that the state shown in FIG.

In this state, the maximum value of the code amount that can be allocated 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.

In practice, the maximum code amount Z _max [bit]
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 21A to 21A is used.
It is necessary to limit the code amount per picture for N.

In practice, it is assumed that some of the encoding devices 21A to 21N are at the writing time of the picture n, and the maximum value C _max [bi of the code amount of the picture Nf several frames after the picture n is assumed.
t] is the encoded data D20A to D20N 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 21
Assuming that the set rate for A to 21N is R ₀ [bit], the picture period is Tf [s], and the offset period is T ₀ [s], the waiting time Tw [n + 1] of picture n + 1 is expressed by the following equation.

(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 the same reference numerals are assigned to parts corresponding to those in FIG. 7 shows the configuration of a digital multi-channel broadcast transmission system 30 according to the present embodiment. In the input stage, a plurality of hierarchical encoding devices 31A to 31N are provided, and the HDTV video signals S1A to S1N are supplied to the hierarchical encoding devices 31A to 31N, respectively.

Each of the hierarchical encoding devices 31A to 31N includes an information hierarchical unit 3 and encoding devices 41A to 41M.
By sequentially performing filtering and sub-sampling on 1A to S1N, a plurality of images having different resolutions are created hierarchically, and layer video signals S2A to S2M are arranged in order of lower frequency components (that is, images having lower resolution).
And the corresponding layer coding units 32A to 32M
To supply.

If the image is hierarchically divided and transmitted so that the resolution becomes finer sequentially from the image having the lower resolution, the receiving side can grasp the outline of the image at the initial stage of the transmission, so that the image can be quickly searched. It is very convenient when is required. In addition, it is possible to selectively receive a hierarchical image according to the error characteristics of the transmission path and the receiving conditions of the receiving side.
It is possible to select the reception quality of the video signal of the TV (Standard Definition Television) system according to the performance of the receiving side.

In each of the encoding devices 41A to 41M, a layer encoding unit 32A to 32M, a layer control unit 33
A to 33M and layer buffers 34A to 34M, and supplied layer video signals S2A to S2M.
Is input to each of the layer coding units 32A to 32M.

Each of the layer coding units 33A to 33M calculates the difference between the layer video signals S2A to S2M via the data bus 5 because there is a correlation between the images having different resolutions, thereby converting the video signal S1A. Layer video signal S having the lowest frequency component obtained by downsampling
2A is provided to the layer coding unit 32A, and only the residual component obtained by subtracting the frequency component of the layer video signal S2A from the layer video signal S2B is provided to the subsequent upper layer coding unit 32B. In the same manner, only the residual component of the frequency component between the lower layer and the upper layer (that is, a portion obtained by subtracting a correlated image) is sequentially provided to the layer encoding units 32C to 32M.

At this time, the layer control units 33A to 33M
Data occupancy information D30A to D30M provided from the layer buffers 34A to 34M, the code amount of each picture up to the picture n, and the encoding devices 41A to 41M.
By executing the code amount limit value calculation program shown in FIG. 4 based on the set rate or the like, the control value C _max of the code amount per picture is calculated, and the control value _Cmax is used as the control signal S30A
〜S30M are given to the layer coding units 32A to 32M.

Thus, the layer coding units 32A to 32M
Compress-encodes a residual component obtained by subtracting a correlation component for each layer from the input layer video signals S2A to S2M with a code amount not exceeding a limit value _Cmax obtained based on the control signals S30A to S30M. The layer encoded data D32A to D32M obtained are transmitted to the layer control units 33A to 33M.
Is stored in the layer buffers 34A to 34M at a picture cycle and for one picture at a time under the control of.

At this time, the layer control unit 33A sends the first control bus 3 from the reference time management unit 36 of the multiplexer 35.
, Reference time information of a 24-hour cycle (ST
C: System Time Clock) Based on D33, the time at which the layer coded data D32A to D32M of the picture n is written to the layer buffers 34A to 34M is tp [n], the buffer size on the receiving side is B, and the coding devices 41A to 4A are used.
Assuming that the set rate of 1M is R ₀ ,

(Equation 12) To calculate the time at which the picture n is to be decoded, and decode time information DTS (Decodi
ng Time Stamp) [n] is the DST added in advance to the layer coded data D32A to D32M of the picture n.
On the other hand, the layer encoded data D32A to
D32M added to the time reference value (PCR: Pr
gram Clock Reference) at the time of reference time information D
33, and store them in the layer buffers 34A to 34M together with the layer coded data D32A to D32M.

At this time, the layer control units 33A to 33A
M is the layer encoded data D32A to D32A of the picture n.
Layer buffers 34A-34 just before writing D32M
Based on the data occupation amount of M, the code amount of the picture n, the set rate, and the code amount of the picture n given from the layer coding units 32A to 32M, the surplus transmission code amount calculation program shown in FIG. The amount of code A that can be transmitted extra by execution is obtained, and this is transmitted to the multiplexing control unit 39 of the multiplexing device 35 via the second control bus 38 as surplus transmission code amount information D35A to D35M.

[0046] Further layer control unit 33A~33M includes a data occupancy of the Reiyabatsufua 34A~34M immediately before writing necessary information (e.g., picture n to determine the maximum value Z _max of the congestion restriction with this, the sign of the picture n The amount, the set rate, the picture cycle, the oldest picture number that has not reached the decoding time, etc.) are used as the congestion limit value calculation information D36A to D36M in the multiplexing device 35 via the second control bus 38. To the conversion control unit 39.

In the multiplexing control unit 39, surplus transmission code amount information D35A to D35 provided from the layer control units 33A to 33M of the encoding devices 41A to 41M, respectively.
Based on M, while recognizing how much gap band is generated in which coding device 41A-41M, for each of the coding devices 41A-41M in which no gap band is generated, the corresponding layer control unit 33A is used. -D congestion limit value calculation information D36A to D36M
The maximum value _Cmax of the code amount allocated to the gap bands of the other encoding devices 41A to 41M is calculated based on the congestion limit value calculation program shown in FIG.

Then, the multiplexing control unit 39, based on the result of this calculation, encodes each encoding device 4 in which no gap band is generated.
A sorting code amount Z ₁ to Z _m to other encoder 41A~41M from 1A～41M, sorting code amount A ₁ for each encoder 41A~41M occurring gap band
~ A _m by the following equation

(Equation 13) Is satisfied until the writing time to the subsequent layer buffers 34A to 34M of the picture n + 1 is reached.
Based on the determination result, for a layer in which no gap band occurs, the determination rate of the layer is R ₀ , and the picture period is Tf,

[Equation 14] , And for a layer in which a gap band occurs, a set rate R _{0 of the} layer and a picture period as Tf,

(Equation 15) At the rate of, the layer coded data D32A to D32D from the layer buffers 34A to 34M of the respective coding devices 41A to 41M.
32M is read in a time sharing manner.

The layer coded data D32A to D32M read in a time-sharing manner are thereafter transmitted to the transmission unit 15 via the data bus 40, and are subjected to predetermined signal processing in the transmission unit 15. Thereafter, the transmission signal S3 is transmitted to the receiving side via the antenna 16 and a communication satellite (not shown).

As described above, in the transmission system 30, the video signals S1A to S1M for a plurality of channels can be encoded and multiplexed and transmitted to the receiving side.

(3) Operation and Effect of the Embodiment In the above configuration, in the transmission system 30, the frequency components of the video signals S1A to S1N input to the respective hierarchical encoding devices 31A to 31N are sequentially divided into bands. As a result, when a plurality of layer video signals S2A to S2M having hierarchically varying resolutions with correlation are obtained,
The information is supplied to the corresponding encoding devices 41A to 41M provided in the respective hierarchical encoding devices 31A to 31N.

Each of the encoding devices 41A to 41M encodes a residual component obtained by subtracting a correlation component from each of the input layer video signals S2A to S2M.
Further, while calculating the code amount A that can be transmitted extra, the multiplexing control unit of the multiplexer 35 based on the calculation result and the congestion limit value calculation information D36A to D36M output from each of the coding devices 41A to 41M. In 39, the code amounts Z _{1 to} Z distributed from each of the encoding devices 41A to 41M in which no gap band is generated to the other encoding devices 41A to 41M.
_m and each of the encoding devices 41A to 41A in which a gap band is generated.
Determining a sorting code amount A ₁ to A _m for 1M, until the write time to Reiyabatsufua 34A~34M the picture that follows at a rate based on the determination result (n + 1),
Layer buffers 34A to 34A of each of the encoding devices 41A to 41M.
34M, the layer encoded data D32A to D32M are read in a time division manner.

Therefore, in the transmission system 30, when a gap band occurs, the transmission efficiency can be significantly improved by effectively utilizing the dummy data without adding dummy data as in the conventional fixed rate system. Can be improved.

Further, in the transmission system 30, the encoding devices 41A to 41M provided in the respective hierarchical encoding devices 31A to 31N only keep the code amount limit per picture. Since each picture can be reliably decoded at the specified decoding time without causing underflow, synchronization control between layers can be easily performed.

According to the above configuration, the multiplexing device 35 converts the preset band into each of the hierarchical coding devices 31A to 31N.
, While dynamically detecting gaps in bands not required by the encoding devices 41A to 41M, and distributing the gaps to the encoding devices 41A to 41M having no margin. With this configuration, it is possible to dynamically control the band of each layer, and thus to realize a transmission system capable of significantly improving transmission efficiency.

(4) Other Embodiments In the above-described embodiment, the multiplexing control unit 39 of the multiplexer 35 is assigned to each layer from the writing time of the picture n to the writing time of the picture n + 1. Layer buffers 34A to 34A corresponding to each layer in which a surplus band of the band is allocated to another layer.
The case where the readout rate from the 34M is varied has been described. However, the present invention is not limited to this. For example, the multiplexing control unit 39 constantly monitors the data occupancy of each of the layer buffers 34A to 34M, and selects one of the layer buffers. 34
When A to 34M becomes empty, the band allocated to that layer may be allocated to another layer.

In the above-described embodiment, a so-called spatial scalable system is used as a layering means for converting the video signal S1A (S1B to S1N) into a plurality of layered video signals S2A to S2M having hierarchically different resolutions. The case where the information layer unit 3 that performs the layering process is applied has been described. However, the present invention is not limited to this. As a method of performing the layer encoding process combining the layering unit and the encoding unit,
For example, an object-oriented coding (Object Oriented Coding) scheme that may be adopted in the MPEG4 standard may be applied. This object-oriented coding scheme is
When there is a video composed of a person and a background, this method reduces the image quality of the background and encodes the person so that the image has a high image quality. can do.

[0058]

As described above, according to the present invention, in a coding and multiplexing apparatus having a hierarchical means, a code output from the corresponding coding means is provided corresponding to each coding means. Multiplexing each coded data by reading the buffer storing the coded data and the coded data stored in each buffer in a time-division manner at a specific set rate preset for the corresponding coding means. Multiplexing means, and the multiplexing means allocates a surplus bandwidth for the set rate of the encoding means to reading of encoded data from a buffer corresponding to another encoding means, so that each It is possible to dynamically perform band control for each layer, and thus realize a coding and multiplexing apparatus that can significantly improve transmission efficiency.

Further, according to the present invention, in the coding and multiplexing method for performing the hierarchization process, the first step of storing the coded data of each layer in a buffer and the coded data stored in each buffer respectively Is read out in a time-division manner at a specific set rate preset for each layer, thereby multiplexing each encoded data.
In the second step, a surplus bandwidth for the set rate of a layer is allocated to reading of encoded data from a buffer corresponding to another layer, so that a bandwidth for each layer is allocated. Control can be performed dynamically, and thus a coding and multiplexing method that can significantly improve transmission efficiency can be realized.

[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 showing the configuration of a conventional fixed-rate transmission system.

[Explanation of symbols]

3 ... information layering unit, 5 ... data bus, 30 ... transmission system, 31A to 31N ... layer coding device, 32A
... 32M ... layer coding section, 33A-33M ... layer control section, 34A-34M ... layer buffer, 35 ...
... Multiplexing device, 36... Reference time management unit, 39... Multiplexing control unit, S1A to S1N... Video signal, S2A to S2
M: Layer video signal, D30A to D30M ... Data occupancy information, D32A to D32M ... Layer encoded data, D33 ... Reference time information, D35A to D35M ...
Surplus transmission code amount information, D36A to D36M... Information for calculating congestion limit value.

Claims (6)

[Claims] An image processing apparatus comprising: a layering means for converting an input video signal into a plurality of layered video signals having hierarchically different resolutions; In a coding and multiplexing apparatus for multiplexing each of the obtained coded data after compression-coding by means, the coding and multiplexing apparatus is provided in correspondence with each of the coding means and output from the corresponding coding means. A buffer for storing the coded data, and the coded data stored in each of the buffers are read out in a time-division manner at a specific set rate preset for the corresponding coding means, thereby obtaining each of the codes. Multiplexing means for multiplexing the encoded data, wherein the multiplexing means converts a surplus bandwidth of the encoding means with respect to the set rate into the other codes. Encoding multiplexing device characterized by distributing the readout of the encoded data from the buffer corresponding to the means. 2. The coding and multiplexing apparatus according to claim 1, wherein said multiplexing means limits respective bands allocated to said coding means so that a buffer on the decoding side does not overflow. 3. The encoding device according to claim 2, wherein said encoding means compresses and codes said layer video signal by limiting a code amount per picture so that a buffer on the decoding side does not underflow. 2. The encoding and multiplexing device according to 1. 4. A code for converting an input video signal into a plurality of layer video signals having different hierarchies hierarchically, compressing and coding each of the layer video signals, and multiplexing the obtained coded data. In the multiplexing and multiplexing method, a first step of storing the coded data of each layer in a buffer, and a step of storing the coded data stored in the buffer in a unique manner set in advance for each of the layers A second step of multiplexing each of the encoded data by reading out the data in a time-division manner at the set rate of the above. In the second step, a surplus bandwidth of the layer with respect to the set rate is converted into another band. A coding and multiplexing method, wherein the coding and multiplexing are performed by reading the coded data from the buffer corresponding to the layer. 5. The coding and multiplexing method according to claim 4, wherein in the second step, a band is allocated to each of the other layers so that the buffer on the decoding side does not overflow. . 6. The method according to claim 4, wherein in the first step, the layer video signal is compression-coded by limiting the amount of code per picture so that the buffer on the decoding side does not underflow. Encoding multiplexing method.