JP4362950B2 - Signal multiplexing apparatus and method, and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal multiplexing apparatus and method, and a recording medium, for example, a signal suitable for use in adjusting a coding rate of a data stream of a DSM-CC data carousel method multiplexed on a digital multichannel broadcast wave. The present invention relates to a multiplexing apparatus and method, and a recording medium.
[0002]
[Prior art]
For example, in a satellite digital multi-channel broadcasting system or a terrestrial digital multi-channel broadcasting system, additional data such as an EPG (electronic program guide) is multiplexed by multiplexing with a normal broadcasting signal (AV (Audio Visual) signal, etc.). Enhancement of various services by transmission, so-called data broadcasting services is desired.
[0003]
The content of such a data broadcasting service is created using a specific description format so that the service as intended by the content creator can be expressed on the receiving side. As this description format, for example, MHEG (Multimedia and Hypermedia information coding Experts Group) is used, and a content creator creates content data by using an authoring tool of MHEG.
[0004]
In addition, as an example of a method for transmitting content of a data broadcasting service, DSM-CC (Digital Storage Media Command and Control) (digital storage media-command and control) standardized by MPEG2-6 (ISO / 1EC18138-6). A control) data carousel transmission system (details will be described later) has been proposed.
[0005]
  Here, a multiplexing apparatus 10 that multiplexes a plurality of signals will be described with reference to FIG. In FIG. 1, a plurality of signals S₁Thru S_NIs, for example, an AV signal of a program broadcast simultaneously.pluralSignal S₁Thru S_NAre encoded by the variable rate encoding units 11-1 to 11-N at a variable encoding rate that changes in accordance with the signal content (image complexity, etc.) and supplied to the multiplexing unit 13. The
[0006]
Data D₁To D_NIs data broadcasting service content, etc., which are encoded by the DSM-CC data encoding units 12-1 to 12-N in conformity with the DSM-CC data carousel transmission system, and the obtained data streams are It is supplied to the multiplexing unit 13.
[0007]
  EncodedsignalS1Thru SNAnd data D1To DNAre multiplexed by the multiplexing unit 13 and output as a multiplexed stream to the subsequent stage.
[0008]
Note that the encoding rate of the multiplexed stream output from the multiplexing unit 13 is limited depending on the transmission capacity of the transmission path to the subsequent stage, so that each encoded stream supplied to the multiplexing unit 13 is When the sum of the coding rates exceeds the transmission capacity of the transmission path, the multiplexing unit 13 uses, for example, some packets from the coded streams input from the variable rate coding units 11-1 to 11-N. Are deleted and multiplexed, and the encoding rate of the multiplexed stream is adjusted to be equal to or lower than the transmission capacity of the transmission path.
[0009]
Here, the DSM-CC data carousel transmission system will be described. As described above, a content creator of a data broadcasting service creates content data using, for example, an authoring tool of MHEG. The produced content data has, for example, a directory structure as shown in FIG. In FIG. 2, a file FN (N = 1, 2, 3) is data that constitutes one scene.
[0010]
In the DSM-CC data carousel transmission system, a unit for communicating data is referred to as a module. Normally, one module is associated with one file FN shown in FIG. In FIG. 2, for example, subdirectories SD1 and SD2 corresponding to each scene are provided in a root directory RD corresponding to one broadcast program, and files F1 and F1 corresponding to video data, audio data, control data, and the like are provided in the subdirectory SD1. F2 and F3 are provided. Some files FN are provided in other subdirectories or root directories. Further, when the structure of the content data is simple, the subdirectory SD may not be provided.
[0011]
In the DSM-CC data carousel transmission method, data to be transmitted is converted into a section format, which is one of the transmission formats defined by MPEG2. The data amount of the section is limited to 4 KB by the MPEG2 standard. A procedure for converting one module (file) into the DSM-CC section format will be described with reference to FIG.
[0012]
A module (corresponding to one file) shown in FIG. 3A is mechanically divided into blocks B1 to Bk having a common size, as shown in FIG. 3B. However, only the last block Bk may be smaller than the common block size. The common block size is determined so that the size of a DDB section described later does not exceed 4 KB.
[0013]
Each block B mechanically divided₁Thru B_kAs shown in FIG. 3 (C), a DSM-CC header is added and converted into a DDB (Download Data Block) structure. Further, as shown in FIG. 3 (D), the section header and CRC (Cyclic Redundancy) are converted. Check Code) is added and converted to DSM-CC section. Hereinafter, the DSM-CC section storing the DDB structure is also referred to as a DDB section. In this way, all the modules constituting one data broadcasting service are converted into DDB sections.
[0014]
In the DSM-CC data carousel transmission method, DII (Download Info Indication) and DSI (Download Server Initiate) are prepared as control information (download control message) necessary for correctly receiving the DDB section on the receiving side. . DII corresponds to the root directory RD in FIG. 2, and DSI corresponds to the subdirectory SD in FIG. Note that DDB and DSI are classified as download data messages, whereas DII and DSI are classified as download control messages.
[0015]
DII and DSI are DSM-CC sections, similar to DDB. Hereinafter, DII and DSI into DSM-CC sections are described as DII sections and DSI sections, respectively. The DDB section, the DII section, and the DSI section are converted into an MPEG2 transport stream (hereinafter referred to as TS), and are periodically and repeatedly transmitted. Specifically, as shown in FIG. 4, a DDB section, a DII section, and a DSI section are pasted on a virtual rotator called a carousel, and are sequentially transmitted in accordance with the rotation of the carousel.
[0016]
That is, as shown in FIG. 4 (A), the module is divided into a plurality of blocks having a common size as described above, and sectioned for each block as shown in FIG. 4 (B). Further, as shown in FIG. 4 (C), each DDB section is converted into a transport stream, and as shown in FIG. 4 (D), the DDB section converted into a transport stream is arranged on the carousel. A DSI section and a DII section corresponding to the module are also arranged on the carousel, and are sequentially transmitted according to the rotation of the carousel.
[0017]
By the way, when the sum total of the data amount of the DDB section, the DII section, and the DSI section arranged on the carousel becomes large, the rotation period of the carousel becomes long. Therefore, a specific section that should be able to be received with a short waiting time, such as a DII section that stores module information or a DDB section that stores the first scene when receiving a data broadcasting service, is transmitted. The period that is performed also becomes longer with the rotation period of the carousel.
[0018]
Therefore, in practice, by preparing multiple sections that should be received frequently, such as the DII section and the DDB section in which the first scene is stored, prepare them by distributing them on the carousel. The section is transmitted at a shorter cycle than the other sections.
[0019]
Meanwhile, as described above, the multiplexing unit 13 in FIG. 1 adjusts the encoding rate of the generated multiplexed stream so as to be equal to or less than the transmission capacity of the transmission path to the subsequent stage. Although it is possible to reduce the coding rate of the data stream from 11-1 to 11-N, it is possible to reduce the coding rate of the data stream from the DSM-CC data coding units 12-1 to 12-N. could not.
[0020]
This is because the data stream encoded by the DSM-CC data carousel transmission system periodically sends the same data at the carousel cycle, and suppose that a part of the data is temporarily transmitted by the multiplexing unit 13 at an arbitrary timing. Even if discarded, the same data is repeated in the next cycle. However, when such data discarding is performed for the purpose of controlling the coding rate, the interval of the same data transmitted without being discarded exceeds the timeout value of each section described as control information of the data stream. This is because there is a possibility that the receiving side may determine that the data does not exist in the stream.
[0021]
The timeout value is a value described in a 4-byte field called tCDownload Scenario that is described as a module-common parameter in DII, and is based on the MPEG2-6 (ISO / IEC18138-6) standard. It is supposed to be a value of one cycle or more of the carousel for the purpose of using for the module acquisition timeout in The timeout value means that the data acquisition may be delayed until the worst time on the receiving side. In a data stream where there is a large difference between this value and the actual carousel period, allow enough time. Can be considered as being sent out.
[0022]
Therefore, for example, the present applicant has set the encoding rate of the data stream from the DSM-CC data encoding units 12-1 to 12-N as Japanese Patent Application No. 11-051862 (hereinafter referred to as the prior application). A method of reducing before inputting to the multiplexing unit 13 is proposed.
[0023]
  In the prior application, the DSM-CC data encoding unit 21 and the multiplexing unit13In the rate control means, the number of the same number of modules left on the carousel (hereinafter referred to as frequency level) is set on the carousel by a number equal to or higher than the frequency level. The encoding rate of the data stream is reduced by appropriately selecting existing modules and discarding them.
[0024]
[Problems to be solved by the invention]
Therefore, in the prior application, the modules to be discarded are selected according to the preset frequency level, so the modules that are most abundant on the carousel cannot be preferentially selected and discarded. There is a possibility that a module to be biased to a specific module, in other words, a module to remain on the carousel is biased.
[0025]
The present invention has been made in view of such a situation. When the data stream encoding rate is reduced, the frequency level is adaptively changed to cause a situation in which modules remaining on the carousel are biased. It is to be able to deter doing.
[0026]
[Means for Solving the Problems]
  The signal multiplexing apparatus according to the present invention includes a conversion unit that converts at least one of a plurality of signals into a periodic data stream in which at least one of all modules included in the signal is included in one period; Data streamBuffering to bufferMeans,BufferedPeriodic data stream dataOccupationDetecting means for detecting the amount;InspectionOutIsDataOccupationQuantity andOutput cyclic data streamSetting means for setting the frequency level based on the period;SettingConstantIsBased on the frequency levelFor one cycleData streamInA determination means for determining a module to be discarded among all the included modules;BufferedFrom a periodic data stream,Decided to discard modulesDiscard the module andDo not discard the restModuleBuffering meansReading means to read fromWhen the ratio of the period in which the detected data occupancy is smaller than the preset lower limit value to the output period is smaller than the first threshold value, the setting means tends to lower the frequency level from the current level. If set and greater than the second threshold greater than the first threshold, set the frequency level to be higher than the current level.
[0027]
The converting means can convert all the modules included in the signal into a periodic data stream including at least one or more in one period using a DSM-CC data carousel transmission system.
[0029]
  The signal multiplexing method of the present invention includes a conversion step of converting at least one of a plurality of signals into a periodic data stream in which at least one of all modules included in the signal is included in one period; Data streamBuffering that causes the buffering means to bufferControl steps;BufferedPeriodic data stream dataOccupationA detection step for detecting the amount;InspectionOutIsDataOccupationQuantity andOutput cyclic data streamA setting step for setting the frequency level based on the period;SettingConstantIsBased on the frequency levelFor one cycleData streamInA decision step for deciding which module to discard from all included modules;BufferedFrom a periodic data stream,Decided to discard modulesDiscard the module andDo not discard the restModuleBuffering meansRead step to read fromIn the setting step, when the ratio of the period in which the detected data occupancy is smaller than the preset lower limit value to the output cycle is smaller than the first threshold, the frequency level is set to be lower than the current level. If set and greater than the second threshold greater than the first threshold, set the frequency level to be higher than the current level.
[0030]
  Recording medium of the present inventionbodyConverting at least one signal of a plurality of signals into a periodic data stream in which all modules included in the signal are included in at least one or more in one period, and a periodic data streamBuffering that causes the buffering means to bufferControl steps;BufferedPeriodic data stream dataOccupationA detection step for detecting the amount;InspectionOutIsDataOccupationQuantity andOutput cyclic data streamA setting step for setting the frequency level based on the period;SettingConstantIsBased on the frequency levelFor one cycleData streamInA decision step for determining a module to be discarded among all the included modules;BufferedFrom a periodic data stream,Decided to discard modulesDiscard the module andDo not discard the restModuleBuffering meansRead step to read fromIn the setting step, when the ratio of the period in which the detected data occupancy is smaller than the preset lower limit value to the output cycle is smaller than the first threshold, the frequency level is set to be lower than the current level. If the signal multiplexing apparatus sets the frequency level to be higher than the current level when the second threshold is larger than the second threshold,ComputerThe program to be executed is recorded.
[0031]
  Main departureLightIn the method, at least one signal of a plurality of signals is converted into a periodic data stream in which all modules included in the signal are included in at least one period, and the periodic data stream is converted into a periodic data stream.Buffered and buffered in buffering meansPeriodic data stream dataOccupationThe amount is detected. In addition, the detected dataOccupationQuantity andOutput cyclic data streamBased on the period, a frequency level is set, and based on the set frequency level,For one cycleData streamInThe module to be discarded is determined from all the included modules,BufferedFrom a periodic data stream,Decided to discard modulesThe module is discarded, andDo not discard the restModule isBuffering meansRead from. The frequency level setting isWhen the ratio of the period in which the detected data occupation amount is smaller than the preset lower limit value to the output cycle is smaller than the first threshold, the frequency level is set to be lower than the current level, and the first If it is larger than the second threshold value that is larger than the threshold value, the frequency level is set to be higher than the current level.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 shows a configuration example of the multiplexing apparatus 20 to which the present invention is applied. The multiplexing device 20 is provided in a broadcasting station such as a satellite digital multi-channel broadcasting system, a terrestrial digital multi-channel broadcasting system, a cable digital multi-channel broadcasting system, etc., and data D such as contents of a data broadcasting service.₁To D_NAre encoded and then multiplexed and output as a multiplexed stream. In the multiplexing device 20, the data D₁To D_NAre respectively input to the DSM-CC data encoding units 21-1 to 21-N.
[0033]
The DSM-CC data encoding unit 21-1 receives the input data D₁Is converted into a DSM-CC section, converted into a data stream, and output to the multiplexing buffer 23-1 and the rate control unit 24-1 of the encoding rate reduction unit 22-1. The DSM-CC data encoding unit 21-1 also receives data D₁Is output to the rate control unit 24-1 of the coding rate reduction unit 22-1. Here, the control information is a table indicating the period T of the carousel and the number of the same modules existing on the carousel (consisting of an identifier for identifying the module (Module Id) and the number of the same modules existing on the carousel. Etc.).
[0034]
The multiplexing buffer 23-1 temporarily stores a DDB section, a DII section, or a DSI section (hereinafter simply referred to as a section) that constitutes a data stream input from the DSM-CC data encoding unit 21-1. Based on the control from the rate control unit 24-1, the stored section is discarded or output to the multiplexing unit 25.
[0035]
The rate control unit 24-1 determines whether or not to discard the section stored in the multiplexing buffer 23-1 based on the data stream and control data input from the DSM-CC data encoding unit 21-1. Judgment is made, and section reading from the multiplex buffer 23-1 is controlled in accordance with the judgment result.
[0036]
Note that the DSM-CC data encoding unit 21-N to rate control unit 24-N are the same as the DSM-CC data encoding unit 21-1 to rate control unit 24-1, and thus the description thereof is omitted.
[0037]
The multiplexing unit 25 multiplexes the data stream with the reduced encoding rate input from the multiplexing buffers 23-1 to 23 -N, and outputs the obtained multiplexed stream to the subsequent stage. The multiplexing unit 25 also supplies the multiplexing control unit 26 with the transmission capacity of the transmission path to the subsequent stage.
[0038]
The multiplexing control unit 26 controls the drive 27 to read a control program stored in the magnetic disk 28, the optical disk 29, the magneto-optical disk 30, or the semiconductor memory 31, and based on the read control program, Each part of the multiplexer 20 is controlled. In particular, the multiplexing control unit 26 determines the output rate of the data stream after the encoding rate output from the encoding rate reduction units 23-1 to 23 -N is reduced, and the corresponding rate control unit 24. The information (output rate) is output to -1 to 24-N.
[0039]
FIG. 6 shows a detailed configuration example of the rate control unit 24-1. The section separator 41 separates the first packet from each DDB section (consisting of a plurality of transport packets) included in the data stream input from the DSM-CC data encoder 21-1, and analyzes the section. To the unit 42. The section analysis unit 42 analyzes the first packet of the DDB section input from the section separation unit 41, identifies the module to which the DDB section belongs, and outputs the identification result to the rate control algorithm processing unit 43.
[0040]
Specifically, by determining whether or not the value of the Section Number field in the first packet of the DDB section is 0x00, it is determined whether or not the DDB section is the first DDB section of the module to which it belongs. To do. After it is determined that the value of the Section Number field is 0x00, it can be determined that the input DDB sections again belong to the same module until the value of the Section Number field is determined to be 0x00. Furthermore, the module to which it belongs is identified by reading the value of the Module Id field in the first packet of the DDB section.
[0041]
The rate control algorithm processing unit 24-1 adaptively changes the frequency level based on the control information input from the DSM-CC data encoding unit 21-1 and the data occupation amount read from the multiplexing buffer 23-1. To do. The rate control algorithm processing unit 24-1 further determines candidate modules to be discarded from the data stream corresponding to the changed frequency level, and adapts to the encoding rate controlled by the multiplexing control unit 26. The module to be discarded is selected from the candidates, and the section currently stored in the multiplexing buffer 23-1 corresponds to the selected module based on the identification result input from the section analysis unit 42. It is determined whether or not there is, and read control of the multiplex buffer 23-1 is performed in accordance with the determination result.
[0042]
Here, the principle of adaptively changing the frequency level will be described with reference to FIGS. FIG. 7 is an example showing, in time series, the order in which modules (that is, DDB sections) arranged on the carousel are transmitted. In this example, the DSI section and the DII section are omitted.
[0043]
In the example of FIG. 7, seven types of modules whose Module Id is 0x001 to 0x0007 are arranged with a margin of 1 to 4 (indicating the number of identical modules existing on the carousel) on the carousel. In this case, the frequency level of the module can be set in the range of 1 to 3.
[0044]
FIG. 8 shows modules that are candidates for discarding when the module frequency level is set to 1 to 3. That is, when the frequency level is set to 1, for each carousel period, each module with Module Id of 0x004 or 0x0005 is regarded as a candidate for discarding, and only two modules with Module Id of 0x006 are included. Only three modules whose Module Id is 0x007 are considered as candidates for discard. Assuming that the size of each module is the same, if all modules that are candidates for discarding are discarded, the bit rate of the input data stream can be reduced by about 7/14.
[0045]
When the frequency level is set to 2, for each carousel period, only one module with Module Id of 0x006 is considered as a candidate for discard and only two modules with Module Id of 0x007 are considered as candidates for discard. . If all modules that are candidates for discarding are discarded, the bit rate of the input data stream can be reduced by about 3/14.
[0046]
When the frequency level is set to 3, only one module whose Module Id is 0x007 is regarded as a discard candidate every carousel period. If all modules that are candidates for discarding are discarded, the bit rate of the input data stream can be reduced by about 1/14.
[0047]
However, if there is a margin in the output rate, try to avoid discarding modules more than necessary.
[0048]
Next, conditions for changing the frequency level will be described with reference to the example shown in FIG. In the example of FIG. 9 as well, as in FIG. 7, it is assumed that seven types of modules are arranged on the carousel, and the sizes of the modules are the same. If the output rate of the data stream instructed from the multiplex control unit 26 requires discarding of 3 modules out of 14 modules on the carousel, if the frequency level is 1, FIG. As shown in FIG. 3, the module to be discarded may be biased. In other words, the modules remaining on the carousel without being discarded are also biased. In such a case, the frequency level is changed to 2 as shown in FIG. 9B in order to reduce the bias of the modules remaining in the carousel.
[0049]
The change of the frequency level is executed based on the amount of data stored in the multiplex buffer 23 (hereinafter referred to as data occupation amount). For example, as shown in FIG. 10, the data occupation amount of the multiplex buffer 23 changes during one carousel period.
[0050]
Regarding the data occupancy of the multiplex buffer 23, the output rate of the multiplexed stream from the multiplexing unit 25 is ensured to be equal to or higher than the sum of the output rates of the data streams from the encoding rate reduction units 22-1 to 22-N. Since the data occupation amount of the multiplex buffer 23 is extremely small, the module is not discarded when the data occupation amount is equal to or less than the predetermined threshold value R. The threshold R is, for example, about 1 packet (188 bytes). In FIG. 10, the period during which the data occupation amount is equal to or less than the threshold value R is Td.
[0051]
Conversely, when the output rate of the multiplexed stream from the multiplexing unit 25 is equal to or less than the sum of the output rates of the data streams from the encoding rate reduction units 22-1 to 22-N, the data in the multiplexing buffer 23 Since the occupation amount gradually increases and the bankruptcy is caused, the frequency level is lowered to increase the number of modules to be discarded.
[0052]
Next, the operation of the rate control algorithm processing unit 24-1 that adaptively changes the frequency level will be described with reference to the flowchart of FIG. In step S <b> 1, the rate control algorithm processing unit 24-1 acquires the carousel period T from the DSM-CC data encoding unit 21. In step S2, the rate control algorithm processing unit 24-1 resets the value t of the built-in timer to 0 and starts measuring time.
[0053]
In step S3, the rate control algorithm processing unit 24-1 acquires the data occupation amount of the multiplexing buffer 23-1. In step S4, the rate control algorithm processing unit 24-1 determines whether or not the data occupation amount of the multiplex buffer 23-1 is smaller than the threshold R, and if it is determined that the data occupation amount is smaller than the threshold, Proceeding to S5, the present time is classified into the period Td. If it is determined in step S4 that the data occupation amount is not smaller than the threshold value, the process in step S5 is skipped.
In step S6, the rate control algorithm processing unit 24-1 determines whether the built-in timer value t has reached the carousel cycle T or not. When it is determined that the built-in timer value t does not reach the carousel period T, the processes of steps S3 to S6 are repeated until the timer value t reaches the carousel period T. When it is determined that the timer value t has reached the carousel period T, the process proceeds to step S7. By the processes in steps S3 to S6, a period Td in which the data occupation amount in one carousel cycle is equal to or less than the threshold value R is measured.
[0054]
In step S7, the rate control algorithm processing unit 24-1 divides the period Td by the carousel period T (hereinafter, the division result is described as Td / T). Of course, 0 <Td / T ≦ 1.
[0055]
In step S8, the rate control algorithm processing unit 24-1 determines whether Td / T satisfies the following expression (1).
Threshold B <Td / T <1 (1)
[0056]
Here, the threshold value B is a value close to 1 (for example, 0.8). When it is determined that Td / T satisfies the inequality (1), the process proceeds to step S9, and the frequency level is increased by 1 (for example, changed from the frequency level 1 to the frequency level 2). If it is determined in step S8 that Td / T does not satisfy inequality (1), the process of step S9 is skipped.
[0057]
In step S10, the rate control algorithm processing unit 24-1 determines whether Td / T satisfies the following equation (2).
0 <Td / T <threshold A (2)
[0058]
Here, the threshold A is set to a value close to 0 (for example, 0.2). When it is determined that Td / T satisfies the inequality (2), the process proceeds to step S11, and the frequency level is decreased by 1 (for example, changed from frequency level 3 to frequency level 2). However, if the current level is frequency level 1, the frequency level cannot be lowered, and this is notified to the multiplexing control unit 26. If it is determined in step S10 that Td / T does not satisfy inequality (2), the process of step S11 is skipped.
[0059]
The mainland level is not changed when the ratio Td / T of the period Td in which the data occupation amount of the multiplex buffer 23-1 is smaller than the threshold R to the carousel cycle T satisfies the following expression (3).
Threshold A ≦ Td / T ≦ Threshold B (3)
[0060]
As described above, when the frequency level is adaptively changed based on the data occupancy of the multiplex buffer, the modules remaining on the carousel are biased when the module is discarded from the carousel and the data stream output rate is reduced. It is possible to suppress the occurrence of such a situation.
[0061]
By the way, the series of processes described above can be executed by hardware, but can also be executed by software. When a series of processing is executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a recording medium in a general-purpose personal computer or the like.
[0062]
As shown in FIG. 5, this recording medium is distributed to provide a program to the user separately from the computer, and includes a magnetic disk 28 (including a floppy disk) on which the program is recorded, an optical disk 29 (CD- It is not only composed of a package medium consisting of ROM (compact disc-read only memory), DVD (digital versatile disc), magneto-optical disc 30 (including MD (mini disc)), or semiconductor memory 31. It is configured by a ROM, a hard disk or the like on which a program is recorded, which is provided to the user in a state of being pre-installed in the computer.
[0063]
In the present specification, the step of describing the program recorded in the recording medium is not limited to the processing performed in time series according to the described order, but is not necessarily performed in time series, either in parallel or individually. The process to be executed is also included.
[0064]
【The invention's effect】
  As aboveLightAccording toMosquitoIt is possible to suppress the occurrence of a situation in which the modules remaining on the rouxel are biased.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a configuration of a conventional multiplexing apparatus 10;
FIG. 2 is a diagram showing a directory structure of content of a data broadcasting service.
FIG. 3 is a diagram for explaining modules and sections in a DSM-CC data carousel transmission system;
FIG. 4 is a diagram for explaining data transmission in a DSM-CC data carousel transmission scheme;
FIG. 5 is a block diagram showing a configuration example of a multiplexing device 20 according to an embodiment of the present invention.
6 is a block diagram illustrating a configuration example of a rate control unit 24-1 in FIG.
FIG. 7 is a diagram showing an example of modules arranged on a carousel.
FIG. 8 is a diagram for explaining the principle of changing the frequency level;
FIG. 9 is a diagram for explaining the principle of changing the frequency level;
FIG. 10 is a diagram for explaining the principle of changing the frequency level.
FIG. 11 is a flowchart for explaining the operation of the rate control algorithm processing unit 24-1 in FIG. 6;
[Explanation of symbols]
20 multiplexers, 21 DSM-CC data encoding unit, 22 encoding rate reduction unit, 23 multiplexing buffer, 24 rate control unit, 25 multiplexing unit, 26 multiplexing control unit, 41 section separation unit, 42 section analysis unit, 43 Rate control algorithm processor

Claims (4)

In a signal multiplexing device that statistically multiplexes a plurality of signals by variable rate coding,
Conversion means for converting at least one signal of the plurality of signals into a periodic data stream in which all modules included in the signal are included in at least one or more in one period;
Buffering means for buffering the periodic data stream;
Detecting means for detecting data occupancy of the periodic data stream being buffered ;
Based on the output period of the detection by said data occupancy rate and the periodic data stream, and setting means for setting a frequency level,
Based on the frequency level is set, determining means for determining the module to be discarded from among all the modules included in the data stream for one period,
From the periodic data stream being buffered, and discarding the module determined in module to discard, and saw including a reading means for reading the rest of the modules that are not discarded from the buffering means,
The setting means has a ratio of a period in which the detected data occupation amount is smaller than a preset lower limit value with respect to the output cycle,
If smaller than the first threshold, set the frequency level to be lower than the current level,
A signal multiplexer that sets the frequency level to be higher than the current level when the frequency is larger than a second threshold that is larger than the first threshold . The converting means converts to a periodic data stream in which all modules included in the signal are included in at least one or more using a DSM-CC data carousel transmission system.
Signal multiplexing apparatus according to 請 Motomeko 1. In a signal multiplexing method of a signal multiplexing apparatus for statistically multiplexing a plurality of signals by variable rate coding,
A conversion step of converting at least one signal of the plurality of signals into a periodic data stream in which all modules included in the signal are included in at least one cycle;
A buffering control step for buffering the periodic data stream in a buffering means ;
A detecting step for detecting data occupancy of the periodic data stream being buffered ;
Based on the output period of the detection by said data occupancy rate and the periodic data stream, a setting step of setting a frequency level,
Based on the frequency level is set, a determination step of determining a module to discard from all the modules included in the data stream for one period,
From the periodic data stream being buffered, and discarding the module determined in module to discard, and viewed including the steps of: reading the remainder of the modules that are not discarded from the buffering means,
In the setting step, a ratio of a period in which the detected data occupation amount is smaller than a preset lower limit value with respect to the output cycle is
If smaller than the first threshold, set the frequency level to be lower than the current level,
A signal multiplexing method for setting the frequency level to be higher than the current level when the frequency is larger than a second threshold larger than the first threshold . A program for controlling a signal multiplexer that statistically multiplexes a plurality of signals by variable rate coding,
A conversion step of converting at least one signal of the plurality of signals into a periodic data stream in which all modules included in the signal are included in at least one cycle;
A buffering control step for buffering the periodic data stream in a buffering means ;
A detecting step for detecting data occupancy of the periodic data stream being buffered ;
Based on the output period of the detection by said data occupancy rate and the periodic data stream, a setting step of setting a frequency level,
Based on the frequency level is set, a determination step of determining a module to discard from all the modules included in the data stream for one period,
From the periodic data stream being buffered, and discarding the module determined in module to discard, and viewed including the steps of: reading the remainder of the modules that are not discarded from the buffering means,
In the setting step, a ratio of a period in which the detected data occupation amount is smaller than a preset lower limit value with respect to the output cycle is
If smaller than the first threshold, set the frequency level to be lower than the current level,
When the frequency is larger than the second threshold value that is larger than the first threshold value, the frequency level is set to be higher than the current level.
A recording medium on which a program for causing a computer of a signal multiplexing apparatus to execute processing is recorded.

Images