JP2000324087A - Method and device for multiplexing signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To multiplex a plurality of signals by keeping transmission restriction of a received data stream in the case of applying statistic multiplexing to a plurality of the signals that are coded at a variable rate. SOLUTION: Buffers 111-11N of a multiplexer section 10 receive coded streams CS1-CSN such as AV(audio visual) data, a buffer 12 receives a DSM-CC data stream DS, the signals read from the buffers 111-11N, 12 are given to a selector 15, where the signals are multiplexed. A multiplex request section 22 makes a multiplex request of the DSM-CC data stream to a multiplex control circuit 20 on the basis of transmission restrictions such as tCDownloadScenario, DII time-out and DSI time-out received at its terminal 21 and a multiplex delay time in the buffer 12. Thus, the title device multiplexes the streams by keeping the transmission restrictions of the DSM-CC data streams.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal multiplexing method and apparatus for statistically multiplexing a plurality of variable rate coded signals, for example, a DSM-CC data carousel in a satellite or terrestrial digital multi-channel broadcasting system. The present invention relates to a signal multiplexing method and apparatus for multiplexing a data stream of a system.

[0002]

2. Description of the Related Art For example, in a digital multi-channel broadcasting system using satellites or terrestrial waves, various services by transmitting additional data such as an EPG (Electronic Program Guide), so-called data broadcasting services, are desired to be enhanced. ing.

[0003] The content of such a data broadcasting service is created using a specific description format that enables the service to be expressed by a receiver as intended by the content creator. The description format is, for example, MHEG (Mu
ltimedia and Hypermedia information coding Experts
Group) standard, and content creators
Create content data using an authoring tool. In addition, as an example of a method for transmitting the content of such a data broadcasting service, DSM-CC
(Digital Storage Media-Command and Control) has been proposed, and this DSM-CC carousel transmission system is based on MPEG2-6 (ISO / IEC 18).
138-6).

In a conventional multiplexing apparatus based on statistical multiplexing, with respect to the input of a data stream by a data carousel system in DSM-CC (Digital Storage Media-Command and Control), the input generated code rate is positively increased. There was no control means, and multiplexing was performed without changing the code rate.

Hereinafter, an example of a conventional multiplexing apparatus will be described with reference to the drawings. FIG. 8 shows an example of a conventional multiplexing apparatus using statistical multiplexing.

In FIG. 8, a plurality of signals, for example, N
Signals S _{1 to} S _N are respectively supplied to the variable rate encoder 61 _1.
To 61 _N , variable-rate encoded, sent to the multiplexing unit 60, and statistically multiplexed.

[0007] In the multiplexing device according to statistical multiplexing shown in FIG. 8, depending on the coding rate which varies with time by the contents of the signals input to the variable rate encoding unit 61 ₁ to 61 _N, the dynamic Is assigned to the band. However, since the transmission capacity of the transmission line after multiplexing is limited, when trying to multiplex data with the same input timing,
One of the data is kept waiting in the buffer in the multiplexer, and a multiplex delay occurs.

Next, an example of a multiplexing apparatus when the data stream from the data encoding section 63 of the DSM-CC data carousel system as shown in FIG. 9 is added to the multiplexing section 60 in FIG. 8 will be considered. .

In FIG. 9, data D such as contents of a data broadcasting service is sent to a data encoding unit 63 of the DSM-CC data carousel system and encoded.
The data stream from the SM-CC data encoding unit 63 is input to the multiplexing unit 60.

Here, the DSM-CC carousel transmission system will be described. The creator of the content of the data broadcasting service as described above creates content data using, for example, the MHEG authoring tool, and the content data has a directory structure as shown in FIG. 10 as an example. In FIG. 10, a file i (i = 1, 2,...) Is data that constitutes one scene.

In the DSM-CC data carousel system,
A unit for receiving data is called a module, and a normal module is associated with each file in FIG. In FIG. 10, for example, sub directories 31 and 32 corresponding to each scene are provided in a root directory 30 corresponding to one broadcast program, and files 33 and 34 corresponding to video, audio, data, and the like are provided in the sub directory 31. , 35 are provided. Some files are provided in another subdirectory or root directory.

Next, referring to FIG.
The procedure for converting to the SM-CC section format will be described.

In the DSM-CC data carousel system,
The data is converted into a section format, which is one of the transmission formats of MPEG2, and the size of the section is limited to 4 KB according to the MPEG2 standard. Therefore, as shown in FIG. 11, the module 40 corresponding to the one file is mechanically divided into blocks 41 having a common size called a block size. Last block 4
Only 2 may be smaller than the block size.

A DSM-CC header 43 is added to one block 41 mechanically divided as described above,
(Download Data Block), and a header 45 and a CRC (Cyclic Redundancy) for converting to a section format which is one of the transmission formats of MPEG2.
Check Code) 46 to form a section. The section made in this way should not exceed 4KB
The above block size is selected. The section storing the DDB structure is hereinafter referred to as a DDB section. In this way, a DDB section is created from all modules constituting one data broadcasting service. In the DSM-CC data carousel system, DDB
DII (Download Info Indication) and DSI (Down) are used as control information necessary to correctly receive a section.
Two download control messages of “load Server Initiate” are prepared. Note that D
The DB is classified as a download data message.

FIG. 12 shows the packet structure of the DDB in the DSM-CC section, and FIG. 13 shows the packet structure of the DII. These FIG. 12,
In FIG. 13, when the table_id (8 bits), which is the first item (field) of the DSMCC_section (), is 0x3C (“3C” in hexadecimal notation, “60” in decimal), the above DDB
0x3B indicates the above DII or DSI. When the messageId field of the message header of the DII structure is 0x1002, the T
S (transport stream). Furthermore, the dsmcc_section_length of the DSMCC_section () (12
The bit) field indicates the length of the following section, which can be up to 4093 (bytes).

In the DDBC packet structure of DSMCC_section () shown in FIG.
Id is bl of Download_Data_Block () in section_number
The lower 8 bits of ockNumber are described, and the last section number is described in last_section_number. Also, Do
dsmccD which is the header at the beginning of wnload_Data_Block ()
ownloadDataHeader () contains protocolDiscriminatoer,
dsmccType, messageId, downloadId, adaptationLeng
th, messageLength, dsmccadaptationHeader, etc. are provided, adaptationLength is the length of dsmccadaptationHeader, and messageLength is Dom from dsmccadaptationHeader.
It indicates the length to the end of blockData of wnload_Data_Block (). Also, of Download_Data_Block ()
The block number is described in blockNumber, and the lower 8 bits of this block number are the above sectio of DSMCC_section ().
Described in n_number.

In the DII packet structure of DSMCC_section () shown in FIG. 13, tr_id is added to table_id_extention.
The lower 16 bits are described. Also, DownloadInfoIn
In dication () (DII), information such as a carousel timeout value and a block size, and information such as the size and version of each module are described. That is, downloadId, blocksize, windowsize, ackPer
iod, tCDownloadWindow, tCDownloadSenario, compat
ibilityDescriptor () etc. and numb indicating the number of modules
erOfModules, moduleId for each module, moduleSi
ze, moduleVersion, moduleInfoLength, moduleInfoBy
te and so on. In the case of the configuration as shown in FIG. 10, a plurality of DIIs associated with subdirectories and information for linking them are described in the DSI. When the configuration of the content data is simple, the DSI may not be used.

DII and DSI are converted into a section format by adding a header and a CRC similarly to DDB. The sections storing these DII structures and DSI structures are hereinafter referred to as DII sections and DSI sections, respectively. In the DSM-CC data carousel system, a DDB section, a DII section,
The DSI section is converted into an MPEG2 transport stream (hereinafter abbreviated as TS) and repeatedly transmitted. As shown in FIG.
Are attached to the surface of a virtual rotating body, and data is sequentially sent to the multiplexing device according to the rotation of the carousel.

That is, in FIG. 14, M1, M
The module 51 of, for example, M1 of the modules 51, 52,... Of M2,... Is divided into several blocks as described with reference to FIG. 53 ₁ , 53 ₂ , 5
3 ₃ is a, each section is a transport stream of. These transport-streamed DDB sections 55 are arranged in the carousel 58.

As described above, the DSI section 56, the DII section 57, and the DDB section 55 are arranged in the carousel 58 and are periodically transmitted.
When all data on the carousel grows, the carousel 1
The period becomes longer, and the period of a specific section, such as a DII section that contains module information and a DDB section that contains the first scene when receiving a data broadcasting service, which should be able to be received with a short waiting time at the time of reception, is also included. It becomes longer according to. Therefore, the section where it is desirable to be able to receive with such a short waiting time,
By arranging and transmitting a plurality of carousels on the carousel as far as possible from each other, the transmission interval can be made shorter than in other sections.

In the data encoder of the DSM-CC data carousel system configured as described above, the encoding rate is determined by the total data capacity of the carousel and the period of the carousel. However, in the actual encoding device, the carousel data expanded on the memory is sequentially transmitted to the multiplexing device in accordance with the set encoding rate. May be considered as the rotation cycle of

[0022]

Incidentally, the conventional multiplexing apparatus does not have a function of performing multiplexing while securely observing the transmission restriction of the input DSM-CC stream.

The "transmission constraint" referred to here is the DSM-C
Some of the standards that must be adhered to when transmitting the C stream are as follows. (1) "tCDownloadScenario": D of the above-mentioned DII
This is a 4-byte field stored in the SM-CC control message. MPEG2-6 (ISO / IEC
In the 18138-6) standard, the value is set to one cycle or more of the carousel in order to use the module for timeout of module acquisition in the receiver. (2) "time_out_value_DII": DVB digital broadcasting standard
This is a 4-byte field stored in the “data broadcasting descriptor” defined in the (DVB specification for data broadcasting), and is a timeout value when receiving DII. (3) "time_out_value_DSI": Similar to (2), this is a 4-byte field stored in the "data broadcast descriptor" and is a timeout value when receiving a DSM-CC control message called DSI.

Here, as described above, the DSM-CC data stream is used except for the case of updating a module.
Although the data is sent to the multiplexing device at a constant coding rate, there has been no means for analyzing the transmission constraint, and the transmitted data has been multiplexed as it is. Therefore, in the case of a multiplexing apparatus based on statistical multiplexing, when competition between streams occurs during multiplexing, that is, when trying to multiplex streams having the same input timing, one of the streams is buffered in the multiplexing apparatus. Therefore, there is a possibility that the DSM-CC data stream is transmitted in a state where the above-mentioned transmission constraint, which should be strictly observed, is not observed.

The present invention has been made in view of the above problems, and enables multiplexing while observing transmission restrictions of a data stream such as a DSM-CC data stream to which data is periodically transmitted. It is an object to provide a signal multiplexing method and apparatus.

[0026]

In other words, a signal multiplexing method and apparatus according to the present invention provide a method for statistically multiplexing a plurality of signals subjected to variable rate coding, wherein at least one of the input signals is periodically multiplexed. The object of the present invention is to solve the above problem by analyzing a data stream, outputting a multiplexing request, and controlling the multiplexing of the data stream in response to the multiplexing request.

Here, the periodic data stream is a data stream of the DSM-CC data carousel system, and the multiplex request is output based on transmission restrictions of the data stream.

As the multiplex request, the multiplex request is made stepwise based on a multiplex delay time from the input time of the data stream. In addition, it is also possible to detect each multiplex delay time from the input time of each of the plurality of input signals, and to prioritize multiplexing from a signal having a large delay amount among these multiplex delay times. In addition, based on the priority of each of the plurality of input signals, multiplexing may be performed by giving priority to a signal having a higher priority. These may be appropriately combined.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a signal multiplexing method and apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a signal multiplexing apparatus according to a first embodiment of the present invention. In the first embodiment of the present invention, a data stream in which data is periodically transmitted is used for at least one of the input signals, and the data stream is analyzed to determine a multiplex interval or a cycle. The data stream is multiplexed so as to be within the multiplexing interval. Specifically, the periodic data stream is a data stream of the DSM-CC data carousel system, the transmission unit is a section, and the data stream is transmitted so as to comply with transmission restrictions such as a timeout value of the DSM-CC stream. Perform multiplexing control.

In FIG. 1, for example,
G2 (ISO / IEC 18138) scheme plurality of signals obtained by the variable rate encoded by such, for example, N pieces of encoded streams CS ₁ to CS _N are statistical multiplexing is sent to the multiplexer 10. Further, a data stream DS obtained by encoding data such as contents of a data broadcasting service in a data encoding unit of the DSM-CC data carousel system is input to the multiplexing unit 10.
N pieces of encoded streams CS ₁ to CS _N can multiplexer 10
Sent to the buffer 11 ₁ to 11 _N, the data stream D
S is sent to the buffer 12 of the multiplexing unit 10, and is read out from these buffers 11 _{1 to} 11 _N and 12 to be output to the selector 1
Sent to 5.

The multiplexing control circuit 20 controls the reading of data from these buffers 11 _{1 to} 11 _N and 12 and also controls the selection of the selector 15. The multiplex request unit 22 is a unit that requests the multiplex control circuit 20 to multiplex a DSM-CC stream. The multiplexing request unit 22 is supplied from the data encoding device or the like via the terminal 21 with the total data amount of the carousel and each timeout value, that is, for example, tCDownloadScenario, DII timeout, and DSI timeout as described above, as additional information. You. Further, the multiplexing request unit 22 includes an input time t1 to the buffer 12 for temporarily storing the data stream DS of the DSM-CC, and a multiplexing time (from the buffer 12 to the selector 1).
5) is supplied.

In FIG. 1, for the data stream DS input to the buffer 12 in TP (transport packet) units, the input time t1 of the TP at the time of entering the buffer 12 is sent to the multiplex request unit 22. Be recorded. In the multiplex request unit 22, the acquired tCDownloadScena
Based on the value of rio, the first DSM-CC data stream
The TP multiplexing interval T1 of the following equation is expressed by the following equation: T1 = tCDownloadScenario / (carousel total data amount / 1
TP). The data amount for one TP in the formula is MPEG
It becomes 188 bytes by the rule of 2.

Further, based on the DII timeout indicating the DII transmission interval and the DSI timeout indicating the DSI multiplexing interval, the multiplexing interval T of the second and third TPs is determined.
2. Find T3. First, the T contained in the carousel
The number of Ps (TPC) is determined by the following equation: TPC = total data amount of carousel / 1 data amount for 1 TP. By counting the number of TPs with this TPC as an upper limit, one cycle of the carousel is known, and DII
Number of TPs between t and DII (tpc1), and DSI
And the number of TPs between the DSI and the DSI (tpc2) are measured. When a plurality of DII and DSI exist in the carousel, tpc1 and tpc2 having the largest values respectively.
Is used.

Next, the DII timeout value Time_out_val
By using ue_DII, T2 = Time_out_value_DII / tpc1 to obtain a TP multiplexing interval T2.
TP multiplexing interval T3 is set to DSI timeout value Time_out
Using _value_DSI, T3 = Time_out_value_DSI / tpc2. Of these T1, T2, T3,
The smallest value, that is, the strictest value, is determined as the multiplexing interval T of TP. That is, T = min (T1, T2, T3).

The TP in the data stream always has a period T
By multiplexing at the following intervals, any timeout value can be observed. For example, 3 as a multiplex request
When using different levels, level LV1: request to multiplex if there is no other competing data, level LV2: request to multiplex with priority over other AV data, and level LV3: more than any other data. It is required to give priority to multiplexing.

FIG. 2 shows an example of the AV such as MPEG2.
(Audio-visual) and N buffers 11 ₁ to 11 _N for storing a data stream, the DSM-CC data carousel scheme buffer 12 for storing the data streams, buffer 13 and the selector 15 for storing SI data is control data Connected to these buffers 1
1 ₁ to 11 _N, the data from the 12 and 13 selected by the selector 15 shows a case of multiplexing. Normally, among these data, the SI data (control data) in the buffer 13 has the highest priority, and is multiplexed prior to other data.

In FIG. 2, at the level LV1, N buffers 111 to ₁ for storing AV streams are used.
1 _N and buffer 12 for storing DSM-CC stream
The data is read out and multiplexed in order from the buffer with the highest priority among the buffers, for example, from the buffer with the largest buffer occupancy (data storage amount). However, the priority is lower than the SI data. Next, at the level LV2, DS
A buffer 12 for storing the M-CC stream, read in preference to any of the N buffers 11 ₁ to 11 _N for storing an AV stream and multiplexed, but priority than SI data is low. Further, in the level LV3, in preference to any of the N buffers 11 ₁ to 11 _N, store SI data buffer 13 for storing the AV stream, reads a DSM-CC data from the buffer 12 are multiplexed.

These multiple request levels LV1 to LV3
Is determined by the relationship between the current time t2 and the input time t1 to the multiplexed data buffer. The two thresholds QT1 and QT2 below the minimum multiplexing interval T are defined as QT1
<QT2 <T, t2−t1 <QT1
Is a level 1 multiplex request, QT1 <t2-t1 <Q
In the case of T2, a multiplex request of level LV2, QT2 <t2-
If t1 <T, a multiplex request for level LV3 is made. The multiplexing control circuit operates the selector to perform multiplexing according to the request issued from the multiplexing request unit. By always making a multiplexing request as described above, multiplexing at a fixed TP multiplexing interval T or less can be always maintained, and multiplexing can be performed while observing the transmission restriction of the DSM-CC stream.

Next, the multiplexing interval and the level LV1
The multiplexing request of LV3 will be described in more detail.

FIG. 3 shows three types of D in a state where streams other than the DSM-CC stream are not multiplexed.
An example is shown in which only SM-CC streams DS ₁ , DS ₂ and DS ₃ are multiplexed, and each data stream DS
Shows the transition of the delay amount corresponding to _1, DS _2, DS _3. In the case as shown in FIG. 3, the threshold value QT1 can be determined by, for example, QT1 = (data amount of one packet × number of multiplexed channels) / output bit rate. This is because DS streams are not multiplexed except for DSM-CC streams.
This corresponds to the maximum value of the delay amount when only the M-CC stream is multiplexed. That is, when a delay exceeding the delay amount in this state occurs, a multiplex request of the level LV2 is performed.

The threshold value QT2 is a value determined in consideration of actual operation, and for example, a value of about QT2 = T × 0.8 can be used.

FIG. 4 shows an example in which other stream packets besides the DSM-CC stream are multiplexed. In the example of FIG. 4, the other AV stream data ST
Further, since the control data SI and the like are multiplexed, the delay amount increases beyond the threshold value QT1, and in some cases, exceeds the threshold value QT2. The multiplex request level LV1 is maintained until the delay amount exceeds the threshold value QT1, but when the delay amount exceeds the threshold value QT1, the multiplex request level becomes LV2. When the delay amount exceeds the threshold value QT2, the multiplex request level becomes LV3. That is, when the delay time is within the range between QT1 and QT2, the level is set to LV2, and when the delay time is within the range between QT2 and T, the level is set to LV3.

The operation of the first embodiment of the present invention as described above is summarized in a flowchart of FIG.

In FIG. 5, in the first step S1, the above-mentioned transmission constraint, that is, tCDownloadSce
nario, DII timeout, DSI timeout, etc. are detected. In the next step S2, the tCDownloadSce
T of the DSM-CC data stream based on the value of nario
The P multiplex interval T1 is determined, the TP multiplex intervals T2 and T3 are determined based on the DII timeout indicating the DII transmission interval and the DSI timeout indicating the DSI multiplex interval, respectively, and the smallest value among these T1, T2 and T3 is obtained. To T
The multiplexing interval T of P is determined. In the next step S3, the threshold values QT1 and QT2 of the multiplex request level described above are set.

Next, in step S4, the delay amount of the buffer of the DSM-CC data stream, that is, t2
-Detect t1. In the next step S5, step S5
4 is equal to the threshold value Q2.
It is determined whether or not it is smaller than T1 (t2−t1 <QT1). If YES, the process proceeds to step S6, and if NO, the process proceeds to step S7. In step S6, the level L
A multiplex request for V1 is made. In step S7, step S4
Is equal to the threshold value Q2.
Larger than T1 and smaller than the threshold value QT2 (QT1
It is determined whether or not <t2−t1 <QT2). If YES, the process proceeds to step S8, and if NO, the process proceeds to step S9. In step S8, a multiplex request for the level LV2 is made, and in step S9, a multiplex request for the level LV3 is made. After steps S6, S8 and S9, step S
Returning to 4, the buffer delay amount t2-t1 is detected.

According to the first embodiment of the present invention described above, multiplexing can be performed while observing the transmission restriction of the data stream of the DSM-CC system, and multiplexing that does not cause failure on the receiving side. It becomes possible to transmit.
Also, by providing a level in the multiplexing request, efficient multiplexing becomes possible without preventing multiplexing of other streams and multiplexing only the DSM-CC data stream.

In the first embodiment, the total data amount of the carousel and the time-out value tCDownl
Although oadScenario, DII timeout, and DSI timeout are obtained from the outside via the terminal 21, tCDownloadScenario may be obtained by analyzing the syntax of the DII section of the DSM-CC data stream. .

That is, as shown in FIG.
2 for the DII section in the DSM-CC data encoded stream stored in
The value of tCDownloadScenario is obtained by analyzing the syntax shown in FIG.
Send to From the terminal 21, the total data amount of the carousel and the respective values of the DII timeout and the DSI timeout are sent to the multiplex request unit 22. Other configurations and operations are the same as those in FIG. 1 described above, and thus description thereof will be omitted.

Next, the second embodiment of the signal multiplexer according to the present invention will be described.
The embodiment will be described with reference to FIG.
In FIG. 7, N encoded streams CS ₁ -C
S _N is sent to the buffer 11 ₁ to 11 _N of the multiplexer 10,
DSM-CC data stream DS is sent to buffer 12 and sent to the selector 15 is read from these buffers 11 ₁ to 11 _N, 12. Multiplex control circuit 20
Controls the reading of data from these buffers 11 _{1 to} 11 _N and 12 and also controls the selector 15 to switch and select. The terminal 21 is supplied with the total data amount of the carousel, the DII timeout, and the DSI timeout from an external data encoding device or the like.
Sent to The multiplexing request unit 25 requests the multiplexing control circuit 20 to multiplex the DSM-CC stream. The stream analysis unit 23 stores the DSM-
By analyzing the syntax of the DII section in the CC encoded data stream, the tCDownloadS
The value of cenario is acquired and sent to the multiplex request unit 25. The multiplexing request unit 25 according to the second embodiment constantly monitors the multiplexed TS stream output from the selector 15. That is, the multiplexing request unit 25 checks the PID (packet ID) of the DSM-CC stream and the multiplexing interval Δt of the packet, and finds the difference between the TP multiplexing interval T calculated in the same manner as in the first embodiment. Find out. Based on the result, the multiplexing request unit 25 makes a multiplexing request to the multiplexing control circuit 20.

More specifically, for example, threshold values QT1 and QT2 are set in the same manner as in the first embodiment, and Δt <QT1
Is the multiplex request of level LV1, QT1 <Δt <QT
In the case of 2, multiplex request of level LV2, QT2 <Δt <T
In the case of, a multiplex request for level LV3 is made. The multiplexing control circuit performs multiplexing by operating the selector according to the multiplexing request from the multiplexing request unit.

The other configuration and operation of the second embodiment are the same as those of the first embodiment, and thus the description is omitted.

By performing multiplexing by making a multiplex request as described above, multiplex transmission can be performed while observing the transmission restrictions of the DSM-CC stream.

It should be noted that the present invention is not limited to only the above-described embodiment. For example, in the above-described embodiment, the number of multiplex request is three, but the number is not limited to this. For example, if a multiplex request has been issued, the multiplex request may always be multiplexed, or the multiplex request may be divided more finely using four or five or more multiplex request levels.

[0055]

According to the signal multiplexing method and apparatus of the present invention, when statistically multiplexing a plurality of signals subjected to variable rate coding, data is periodically transmitted to at least one of the input signals. The data stream is used, the data stream is analyzed, a multiplexing request is output, and the data stream is multiplexed and controlled in response to the multiplexing request. It is possible to multiplex while guarding, and it is possible to perform multiplex transmission without causing a failure on the receiving side.

By providing a level for the multiplex request,
Efficient multiplexing is possible without multiplexing other data streams and multiplexing only DSM-CC data streams.

Further, by making a multiplex request in consideration of one or both of the multiplex delay time of the data stream and the priority of the data stream, the delay time and the priority can be reduced without causing a failure on the receiving side. Also, optimized data transmission can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a multiplexing unit that multiplexes a plurality of types of data streams.

FIG. 3 is a diagram illustrating an example of a change in a buffer delay amount during data stream multiplexing.

FIG. 4 is a diagram illustrating another example of a change in a buffer delay amount during data stream multiplexing.

FIG. 5 is a flowchart for explaining the operation of the first exemplary embodiment of the present invention.

FIG. 6 is a block diagram showing another configuration example of the first embodiment of the present invention.

FIG. 7 is a block diagram showing a schematic configuration of a second embodiment of the present invention.

FIG. 8 is a block diagram illustrating an example of a multiplexing apparatus using statistical multiplexing.

FIG. 9 is a block diagram showing another example of a multiplexing apparatus using statistical multiplexing.

FIG. 10 is a diagram showing a directory structure for explaining contents of a data broadcasting service.

FIG. 11 is a diagram for explaining modules and sections in the DSM-CC data carousel system.

FIG. 12 is a diagram for explaining the structure of a DDB section in the DSM-CC data carousel method.

FIG. 13 is a diagram for explaining the structure of a DII section in the DSM-CC data carousel system.

FIG. 14 is a diagram for explaining data transmission in the DSM-CC data carousel system.

[Explanation of symbols]

10, 60 multiplexing section, 11, 61 variable rate coding section, 21, 63 DSM-CC data coding section, 2
3 multiplex buffer, 24 rate control means, 25
Section separation circuit, 26 section analysis circuit,
28 multiplex control unit

Claims (12)

[Claims] 1. A signal multiplexing method for statistically multiplexing a plurality of variable-rate-encoded signals, wherein a data stream in which data is periodically transmitted to at least one of input signals is used. And outputting a multiplexing request, and multiplexing the data stream in response to the multiplexing request. 2. The method of claim 2, wherein the periodic data stream is a DSM.
2. The signal multiplexing method according to claim 1, wherein the signal is a data stream of a CC data carousel system, and the multiplexing request is output based on transmission restrictions of the data stream. 3. The signal multiplexing method according to claim 1, wherein the multiplexing request is made stepwise based on a multiplex delay time from the input time of the periodic data stream. 4. A method for detecting each multiplex delay time from the input time of each of the plurality of input signals, and multiplexing the signals with a larger delay amount among the multiplex delay times with priority. The signal multiplexing method according to claim 1, wherein: 5. The signal multiplexing method according to claim 1, wherein the multiplexing is performed in such a manner that a signal having a higher priority is preferentially multiplexed based on the respective priorities of the plurality of input signals. 6. The method according to claim 1, further comprising detecting respective multiplex delay times of the plurality of input signals from respective input times, and multiplexing the signals in an order based on the respective multiplex delay times and the priority. The signal multiplexing method according to claim 5, wherein 7. A signal multiplexing apparatus for statistically multiplexing a plurality of signals subjected to variable rate coding, wherein at least one of input signals uses a data stream in which data is periodically transmitted, and A signal multiplexing apparatus comprising: a multiplexing request unit that analyzes the data stream and outputs a multiplexing request; and a multiplexing control unit that multiplexes and controls the data stream in response to the multiplexing request. 8. The periodic data stream is a DSM.
8. A signal multiplexing method according to claim 7, wherein the multiplexing request means outputs the multiplexing request based on a transmission restriction of a data stream of a DSM-CC data carousel method. Device. 9. The signal multiplexing apparatus according to claim 7, wherein said multiplexing request means makes the multiplexing request stepwise based on a multiplexing delay time from an input time of said periodic data stream. apparatus. 10. The multiplex requesting means detects each multiplex delay time from the input time of each of the plurality of input signals, and gives priority to a signal having a large delay amount among these multiplex delay times. The signal multiplexing device according to claim 7, wherein the multiplexing request is made. 11. The multiplexing request unit according to claim 7, wherein said multiplexing requesting unit issues a multiplexing request with a higher priority to a higher priority signal based on the respective priorities of said plurality of input signals. Signal multiplexer. 12. The multiplex requesting means detects each multiplex delay time from the input time of each of the plurality of input signals, and determines the multiplex delay time in an order based on each of the multiplex delay times and the priority. 12. The signal multiplexing device according to claim 11, wherein a multiplexing request is made according to the request.