JPH09116520A - Multiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain efficient multiplex transmission and to reduce a delay time attended with multiplex processing by providing a multiplex control means that selects coded data multiplexed and outputted by a multiplexer means based on stored data amount of coded data among coded data stored in plural multiplex buffers. SOLUTION: Coded data 21a-21n are given to multiplex buffers 11a-11n and stored in them till being multiplexed. A multiplexer section 12 multiplexes coded data 22a-22n outputted from the multiplex buffers 11a-11n and provides an output of a multiplexed stream 24. Every time the multiplex buffers 11a-11n store the coded data 21a-21n and output data having been stored in the multiplexer section 12, the multiplex buffers 11a-11n output buffer storage data 23a-23n denoting the remaining data storage amount. A multiplexer control section 13 select any of coded data to be multiplexed based on the buffer storage data 23a-23n received from the multiplex buffers 11a-11n and provides an output of a multiplex selection signal 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexing device for performing multiplexing for encoding and transmitting or storing multimedia data such as digitized audio, video and other data, and more particularly to a multiplex device. It is applied to a channel program multiplexing device. Specific applications include satellite, terrestrial, cable, digital broadcasting systems using optical fibers, video-on-demand (VOD), and video conferencing systems.

[0002]

[Prior art]

Conventional example 1. FIG. 11 shows, for example, Hattori, Tanaka, Asano, Asai,
Sakado: "Satellite Broadcasting Quality Codec", Mitsubishi Electric Technical Report, Vol. 67, No. 7, pp. 33-38 (19
It is a block diagram of the multimedia multiplexing apparatus shown by 93). In FIG. 11, 110 is a video encoding unit that sources-codes the video signal 101 to generate a video-encoded bit string 104, and 111 is an audio encoding unit that sources-source codes the audio signal 102 to generate an audio-encoded bit string 105. Reference numeral 112 denotes a data encoding unit that performs various processes on the data signal 103 to generate a data encoded bit sequence 106, and 100 denotes a video encoded bit sequence 10.
4, the audio coded bit string 105 and the data coded bit string 106 are multiplexed to form one multiplexed bit string 107.
It is a conventional media multiplexing unit that generates

Next, the operation of the conventional multimedia multiplexer will be described. The video signal 101, the audio signal 102, and the data signal 103 respectively include a video encoding unit 110, an audio encoding unit 111, and a data encoding unit 1.
12 is information source coded, and is video coded bit string 104,
An audio coded bit string 105 and a data coded bit string 106 are generated. In the media multiplexing unit 100,
The video coded bit string 111, the audio coded bit string 112, and the data coded bit string 113 are multiplexed into one multiplexed bit string 107.

The multiplexing is performed in units of a predetermined multiplex frame. FIG. 12 shows a conventional media multiplexing unit 10
2 is an explanatory view of a multiplexing method in 0, in which 120 is a multiplexed frame for transmitting a multiplexed bit string, 121 is a synchronization bit for ensuring multiplexing frame synchronization, and 122 is a video encoded bit string 104. A video slot 123, an audio slot 123 in which the audio coded bit string 105 is stored, and a data slot 124 in which the data coded bit string 106 is stored.

The coded data of each medium is multiplexed in units of a multiplexed frame having a predetermined repetition frequency, and a video coded bit string 10 is stored in a predetermined video slot 122 in a conventional media multiplexing unit 100.
4, the audio coded bit 105 is accommodated in the audio slot 123, and the data coded bit string 106 is accommodated in the data slot 124, thereby performing time division multiplexing. Further, a synchronization bit 121 of a unique word is arranged at the head bit of the multiplexed frame 120 for the purpose of ensuring synchronization on the receiving side of the multiplexed frame 120.

Conventional example 2. As another conventional example, the one described in Japanese Patent Laid-Open No. 4-219041 is shown in FIG. 13, 125a to 125n are buffers for accumulating packets input from the input ports 126a to 126n, 127a to 127n are counters for counting the number of waiting packets accumulated in the accumulating buffers 125a to 125n, and 128 is this counter. Counter 127a-
A polling unit that is connected to 127n and determines the sending port from the number of waiting packets and the offset value, 12
Numeral 9 is connected to the counters 127a to 127n, and a queue length monitoring unit for determining a sending port from the number of waiting packets and an offset value, and 130 is a counter 127 corresponding to the buffer 125 in which the media with the strictest discard request is accumulated. By comparing the count value with the threshold value of the number of waiting packets for the medium having the strictest discarding request, the limit switching unit for switching between the limit polling unit and the queue length monitoring unit, 131 is the buffer 125a to 125a.
It is a switch that selects and outputs one of n based on the control from the restricted polling unit 128 or the queue length monitoring unit 129. The restriction polling unit 128, the queue length monitoring unit 129, and the restriction switching unit 130 constitute a multiplexing control device 132. In such a multimedia packet multiplexer, first, the packets input from the input ports 126a to 126n are temporarily stored in the buffers 125a to 125n, at which time the corresponding counter increments by one.

The limit switching unit 130 has a threshold value for the number of waiting packets for the medium with the strictest discard request, and the buffer 125 for storing the medium with the strictest discard request.
When the number of waiting packets is less than or equal to the threshold value, the restricted polling unit 128 is compared with the value of the counter 127 corresponding to
Is used, and if the threshold value is exceeded, the queue length monitoring unit 129 is used.

The restricted polling unit 128 sequentially selects each of the buffers 125a to 125n, inputs them to the switch 131, and sends them one packet at a time. Here, the restricted polling unit 128 has an offset value corresponding to each of the input ports 126a to 126n and showing a smaller value for a medium having a higher delay request, and the value of each counter 127a to 127n is less than or equal to each offset value. In this case, the number of waiting packets is regarded as 0 and the port is skipped. This allows
A packet of media with a high delay is preferentially transmitted.

Further, the queue length monitoring unit 129 regards the number of waiting packets as a logical offset, and the media with a higher discarding request has a lower offset value, and regards the value obtained by subtracting this offset value from the number of waiting packets as the logical waiting packet number. , Select the port with the largest number of logical wait packets. As a result, packets of media that are strict in discarding are preferentially transmitted.

After the port is selected, each packet is sent as a multiplexed output, and the counter value of the selected port is decreased by one. By the above operation, the priority control of the packet of the medium that is strict in discarding and the priority control of the medium that is strict in the delay are independently performed.

[0011]

In the multimedia multiplexing apparatus shown in the prior art example 1, the coded data of each medium is time-division multiplexed at a predetermined fixed rate, and the encoded data of each medium is multiplexed. The encoded data will be multiplexed at a fixed bit rate.

Therefore, when variable rate (bit rate) coding is performed such that the bit rate changes with time, a slot having a width that can correspond to the maximum bit rate of the coded data of each medium in the transmission frame. Data cannot be completely transmitted unless all the media are secured. When such a slot is prepared, the size of the multiplexed frame becomes large, so that it may take a long time to secure synchronization of the multiplexed frame on the receiving side, or if the encoded data does not reach the maximum bit rate. Since the dummy data will be transmitted to the remaining part of the relevant slot, the transmission efficiency will decrease, and in the multiplexed bit string after multiplexing, only a fixed transmission rate will be given to each medium, so I want to transmit There is a problem in that it is not possible to flexibly adapt to the increase or decrease of encoded data, and a transmission delay occurs due to multiplexing.

Particularly when the number of media to be multiplexed is large, the size of the multiplexed frame becomes large, so that a program (program) consisting of video, audio, data, etc.
In a multi-channel broadcasting service in which a plurality of channels are collected, multiplexed into one multiplexed frame, and delivered by using a satellite or a coaxial cable, a decrease in multiplexing efficiency and a transmission delay are significant.

Further, since the video, audio, and data are multiplexed by storing them at a predetermined fixed position in the multiplexed frame, in addition to the change of the bit rate of each individual medium as described above, It was difficult to flexibly respond to changes in the contents of transmission data such as the presence or absence of media, and efficiently multiplex.

Further, in the multimedia packet multiplexing apparatus shown in the above-mentioned conventional example 2, since the number of packets stored in the buffer is used as a criterion for selecting a transmission packet, for example, from each input port depending on the type of media. If the size of incoming packets is different, the multiplexing controller cannot detect the free space of the buffer capacity only by the number of packets. Therefore, in order to perform appropriate control without buffer overflow 1
The size of each buffer (especially the maximum amount) must be set individually for each buffer, and the variable bit rate encoding changes the amount of data generated per unit time as described above. In this case, there is a problem in that it is not possible to perform control to feed back the variable bit rate encoding operation according to the data amount instead of the buffered number and suppress the transmission delay associated with multiplexing.

The present invention has been made to solve the above problems, and flexibly and appropriately responds to changes in the transmission rate of individual media to be multiplexed, the presence or absence of individual media, and the like. Therefore, it is possible to efficiently perform multiplex transmission and to suppress the delay time associated with multiplexing.

[0017]

According to the present invention, there is provided a multiplexing device for multiplexing a plurality of pieces of coded data which are multiplexed and output by the multiplexing means on the basis of the accumulated data amount of the coded data in each multiplexing buffer means. It is provided with a multiplexing control means for selecting from encoded data accumulated in the encoding buffer means.

Further, the multiplexing control means is preferentially selected as the multiplexed output from the coded data accumulated in the multiplexing buffer means having the largest accumulation amount among the accumulation data amounts of the respective multiplexing buffer means. It is something that is done.

Alternatively, the multiplexing control means has a weighting means for weighting the accumulated data amount of each of the multiplexing buffer means, and the multiplexed output is selected based on the accumulated data amount weighted by the weighting means. It was done like this.

In addition, an invalid data generating means for generating invalid data is provided, and the multiplex control means is provided to invalidate the invalid data generating means when the amount of data stored in each of the multiplex buffer means is less than a predetermined amount. The invalid data output by is selected as the multiplexed output.

Further, the transmission control data generating means for generating the transmission control data and the interrupt timer means for measuring the interval for transmitting the transmission control data are provided, and the output of the transmission control data generating means is based on the time measurement result by the interrupt timer means. The transmission control data to be transmitted is selected as the multiplexed output.

When the amount of data stored in each of the multiplex buffer means is less than a predetermined amount, the transmission control data output from the transmission control data generating means is selected as the multiplex output, and the interrupt timer is selected. The means is set to the time counting start state.

The multiplex buffer means is provided with control signal output means for outputting a control signal of the generated code quantity of the input coded data based on the amount of data stored in each of the multiplex buffer means. is there.

Further, the multiplexing control means is provided with a control signal output means for outputting a control signal of the generated code amount of the input coded data on the basis of the amount of data accumulated in each of the multiplex buffer means. .

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 of the Invention An embodiment of a multiplexing device of the present invention will be described below with reference to the drawings. In FIG. 1, 10a
10n are n coding units that code various media information 20a to 20n such as video, audio, and data,
11a to 11n are multiplex buffers as n multiplex buffer means for accumulating the encoded data 21a to 21n output from the encoding units 10a to 10n, and 12 is accumulated in the multiplex buffers 11a to 11n. A multiplexing unit 13 as multiplexing means for multiplexing encoded data and outputting it as a multiplexed stream 24 is a multiplexing buffer 11
Based on the accumulated data amount of the coded data 21a to 21n in a to 11n, the coded data multiplexed and output by the multiplexing unit 13 is output from the plurality of multiplexing buffers 11a to 11a.
The multiplex control unit is a multiplex control unit that selects from the encoded data stored in 11n.

Next, the operation will be described. Various media information 20a to 20n such as video, audio, and data corresponding to various applications are individually taken into the encoding units 10a to 10n, and the information source encoding process is performed to obtain encoded data 21a to 21n. Is generated.
The individual encoded data 21a to 21n are input to the multiplexing buffers 11a to 11n, respectively, and accumulated until they are multiplexed.

In the multiplexing unit 12, each multiplexing buffer 11a
Coded data 22a to 22n output from -11n are multiplexed and output as a multiplexed stream 24. Here, each of the multiplexing buffers 11a to 11n includes an encoding unit 10a to.
Every time the encoded data 21a to 21n from 10n is accumulated or the accumulated data is output to the multiplexing unit 12,
Buffer storage amounts 23a to 23 indicating the remaining data storage amount
Output n.

The multiplex control unit 13 stores the buffer storage amount 23a to 23d input from each of the multiplex buffers 11a to 11n.
23n, one encoded data to be multiplexed is selected, and a multiplexing selection signal 25 is output.

The encoded data 2 input in the multiplexing unit 12
Of the data 2a to 22n, the coded data indicated by the multiplexing selection signal 25 is multiplexed one after another and output as a multiplexed stream 24.

Here, an example of a method of selecting encoded data performed by the multiplexing control unit 13 will be described with reference to FIG. In FIG. 2, 27 is a buffer storage amount 2 input from each of the multiplexing buffers 11a to 11n.
3a to 23n are compared, the coded data accumulated in the multiplexing buffer having the largest accumulation amount is selected, and the multiplexing selection signal 2 indicating the number (hereinafter referred to as the stream number) is selected.
5 is a buffer accumulation amount comparison unit that outputs 5.

Next, the operation will be described. The buffer storage amount comparison unit 27 compares the buffer storage amounts 23a to 23n from the multiplex buffers 11a to 11n, selects the one having the maximum storage amount, and outputs the corresponding stream number to the multiplex selection signal. Output as 25.

For example, at some point, the buffer storage amount 23a
, The stream number a is output as the multiplexing selection signal 25. As a result, the multiplexing buffer 11a having the largest buffer storage amount is selected, and the encoded data 22a from this multiplexing buffer 11a is transferred to the multiplexing unit 12
Is multiplexed and output, and the multiplexing buffer 11a
The amount of data accumulated in is reduced.

The operation from the selection of coded data to be multiplexed to the multiplexing will be described in more detail with reference to FIG. In FIG.
The number of coded streams to be multiplexed is three, and changes in the buffer storage amount of the multiplexing buffers 11a, 11b, and 11c over time are shown. That is, the time t
Buffer accumulation amount 23a of the multiplexing buffer 11a in
Is represented by Sa (t), and similarly, the buffer storage amounts 23b, 23c of the multiplexing buffers 11b, 11c are represented by Sb (t) and Sc (t), respectively.

At times t1, t2 ,. . Represents the timing of multiplexing. Here, for simplicity, it is assumed that the multiplexing selection signal 25 is selected at fixed time intervals and the coded data of the selected multiplexing selection signal 25 is multiplexed. To do.

Further, here, each encoded data 2
It is assumed that the information generation rates of 1a, 21b and 21c are constant, and that the sum of the information generation rates of the encoded data 21a, 21b and 21c is equal to the transmission rate of the multiplexed stream 24.

At time t1, the buffer storage amount comparison unit 30 stores the storage amount 23a of each multiplexing buffer at that time,
23b and 23c are compared. At time t1, as shown in FIG. 3, Sb (t1)> Sa (t1)> Sc (t
Since it is 1), the stream number b is selected and b is output as the multiplexing selection signal 25.

The multiplexing unit 12 reads m bits from the multiplexing buffer 11b by the multiplexing selection signal 25 and multiplexes them into the multiplexed stream 24. Here, for simplicity, it is assumed that the encoded data 22b is instantly read from the multiplexing buffer b11b. Therefore, at the next point in time when the storage amounts are compared at time t1, the storage amount Sb (t1) in the multiplexing buffer 11b decreases by m bits.

Actually, the m bits are output as the multiplexed stream 24 from time t1 to time t2 of the next multiplexing timing, and the transmission rate of the multiplexed stream 24 is constant (CBR: Constant Bit).
Rate), the transmission rate at that time is as follows: Transmission rate [bit / sec] = m [bit] / (t2-t
1) It is given in [sec].

Next, at time t2, as shown in FIG.
Since (t2)> Sb (t2)> Sc (t2), the stream number a is selected and a is output as the multiplexing selection signal 25. After that, similarly, at times t3, t4, t
At 5, t6, the buffer accumulation amounts are compared, and b, c, b, a are sequentially output as the multiplexing selection signal 25,
According to this, the encoded data is read from each multiplexing buffer.

When the storage amounts of the multiplex buffers are the same, a predetermined priority (for example, a stream number having a smaller number has a higher priority, or a code stream having a lower information generation rate has a higher priority. The coded stream number is selected based on the frequency, and the multiplexing selection signal 25 is output.

FIG. 4 shows an example of the encoded data 21a to 21n output from the encoding units 10a to 10n. Reference numeral 35 is a fixed length packet composed of fixed length (m bits), and 36 is a packet. Is a packet header that includes information for identifying, and 37 is a payload that includes encoded data and control information.

In the encoding units 10a to 10n, each encoded data is accommodated in the payload 37 of the fixed length packet 35, and the multiplexing buffer 1 in the form of the fixed length packet 35.
1a to 11n. Packet header 3 at that time
6 includes a unique packet identification number for each medium so that the contents of the payload 37 can be distinguished.

The multiplexing unit 12 multiplexes in m-bit fixed length packets 35 to generate a multiplexed stream 24. On the receiving side, the multiplexed stream 24 is separated into fixed packet length units of m bits, and each fixed length packet 3
Each media is separated by the packet header 36 of No. 5.

By the above operation, the coded data to be multiplexed is selected according to the accumulated amount in the multiplexing buffer and is multiplexed and output, so that it is not necessary to set a fixed multiplexing pattern in advance, and efficient multiplexing transmission is possible. Can be done.

Further, since a buffer having a large buffer storage amount is selected and multiplexed, the required capacity of the multiplexing buffer can be minimized and at the same time the delay time associated with the multiplexing can be shortened.

Furthermore, the selection of encoded data to be multiplexed is
Since the amount of data stored in the multiplex buffer is used, it is possible to control the amount of data stored in the multiplex buffer.

According to the control carried out by grasping the storage amount of the multiplex buffer of the present invention, assuming that one packet has m bits, as shown in the embodiment shown in FIG. 0 or 1 packets
The number of packets cannot be determined by comparing the number of packets. In order to make a decision by comparing the number of packets, the capacity of the multiplexing buffer must be made larger, which increases the delay in data transmission due to multiplexing.

If the control based on the storage amount of the multiplex buffer is performed as described above, fine control that reflects the data storage amount itself in the multiplex buffer becomes possible, the capacity of the multiplex buffer is suppressed, and the transmission delay is minimized. Can be suppressed.

In the above embodiment, the transmission rate (bit rate) of the multiplexed stream 24 is constant (CBR: C).
Although the present invention has been described as an instant bit rate, the present invention is a VBR (Variable) in which the transmission rate of actual data in the multiplexed stream 24 is variable.
e Bit Rate) is also applicable.

In the case of this VBR, the amount of encoded data generated is usually variable on the encoding unit side as well, and transmission by VBR is suitable for transmitting data in which the amount of generated data changes. At this time, if the multiplexing timing is fixed, the number of multiplexing bits becomes variable. That is, when the multiplexing timing is set at regular intervals as in the case of the above-described embodiment described with reference to FIG. 3, the number of bits to be read out for multiplexing is variable.

That is, since the amount of encoded data generated from the encoding unit is variable, the amount of accumulation in each multiplexing buffer does not increase in a constant manner with respect to the time axis, but for example, in a large amount in a certain interval. Data may be generated in the storage area, and the amount of storage may suddenly increase, but it is necessary to increase the capacity of the multiplexing buffer when reading a certain number of bits, and the stream is selected many times and the interval for multiple times Since the transmission is carried out by using, the transmission delay of the stream and other streams will be increased. Therefore, the number of bits read at a time is increased (that is, the number of multiplexed bits is increased) to suppress the transmission delay.

In the present invention, since the coded data to be multiplexed is selected by looking at the accumulated amount itself, it is possible to know how the accumulated amount increases, and the number of bits to be read at one time may be determined according to each accumulated amount. Such an operation is possible because the accumulated amount itself is used as a reference.

Also, the multiplexing timing is variable when multiplexing is performed with fixed m bits. That is, in the above-described embodiment described with reference to FIG. 3, the multiplexing timing is set at regular intervals, and the coded data to be multiplexed is selected by comparing the accumulated amounts at that time. The configuration can be made relatively simple. For this reason, when one of the multiplexing buffers reaches a predetermined storage amount, the coded data is selected and multiplexed. In this case, the multiplexing timing becomes variable. It is possible to perform such an operation at a fine level by grasping the accumulated amount.

Further, as shown in FIG. 4, each coding unit 10
When packetized by a to 10n, it is possible to multiplex in that unit, and the configuration of the multiplexing unit can be simplified. On the other hand, in the multiplexing buffer or multiplexing unit, a header indicating each stream is attached to each encoded data. By doing so, the delimiter of the accumulated data read from the multiplexing buffer can be freely added, so that it is possible to cope with the case of the above VBR.

For example, it is possible to determine the lower limit threshold value in the multiplexing buffer storage amount of FIG. 3 and read up to the lower limit threshold value as a multiplexed output at once for the selected stream. If you change this threshold for each buffer, each stream (media)
Can be used for transmission.

In the above description, each multiplexing buffer 1
Although the storage amounts 23a to 23n are output from 1a to 11n, the buffer remaining amount may be output instead of the storage amount, and the multiplexing control unit 13 may output the multiplexing buffers 11a.
A counter for counting the accumulated amount of 11 to 11n is provided, and the amount of incoming data from each of the multiplex buffers 11a to 11n,
A signal indicating the output data amount may be sequentially transmitted, and the counter of the multiplexing control unit 13 may grasp and judge the accumulated amount of each buffer. In short, the data accumulated amount of each of the multiplexing buffers 11a to 11n may be grasped. .

Embodiment 2 of the Invention In the first embodiment, the coded data to be multiplexed is selected by comparing the multiplex buffers 11a to 11n equally, but coded data of a specific medium may be preferentially multiplexed with a low delay time. At this time, the buffer storage amount for other coded data may be input to the multiplexing control unit 13 after being reduced from the actual value.

Further, in the case where the priority is given as a whole, each accumulation amount may be weighted and the selection may be made according to the weighted accumulation amount. An embodiment thereof will be described with reference to FIG. In FIG. 5, 50 is a weighting coefficient table, 51
Is a weighting unit, and 52 is a comparison unit, and the same reference numerals as those in FIG.

Next, the operation will be described. Multiplex controller 1
The buffer accumulation amounts 23a to 23n input to the 3 are the weighting coefficients 53 input from the weighting coefficient table 50.
The weighting unit 51 performs weighting according to a to 53n.

The values of the weighting factors 53a to 53n are determined, for example, by the delay allowable time of each medium (stream) for multiplexing, and the media having a small delay allowable time is heavily weighted.

As a result, the buffer storage amount after weighting is 5
When the comparison unit 52 performs the comparison of 4a to 54n, the medium having the shortest allowable delay time is preferentially selected, and the multiplexing selection signal 25 is output. In general, audio media have a smaller buffer size than video media, and the allowable delay time is shorter than that of video media. Therefore, the audio media is heavily weighted and controlled so that the delay time due to the multiplexing is reduced. In this way, using the value of the accumulated amount, fine weighting is performed and priority control is performed.

Embodiment 3 of the Invention FIG. 6 is a block diagram showing another embodiment of the present invention. In FIG. 6, 30
Is a multiplexing unit, 31 is an invalid data generating unit, and the same reference numerals as those in FIG.

Next, the operation will be described. When the sum of the information generation rates of the encoded data 22a to 22n is smaller than the transmission rate of the multiplexed stream 33, the invalid data generation unit 31.
More invalid (null) data 32 is generated, multiplexed in the multiplexing unit 30 into the multiplexed stream 33, and the multiplexed stream 3
The speed matching is performed at the transmission speed of 3.

That is, when the buffer storage amounts 23a, 23b, 23c of the multiplexing buffers 11a, 11b, 11c at the multiplexing timing as shown in FIG. A multiplexing selection signal 25 for selecting is output and multiplexing is performed. Further, as the invalid data 32, all bit values of the data are set to "1" or "0".

Embodiment 4 of the Invention FIG. 7 is a block diagram showing another embodiment of the present invention. In FIG. 7, 40
Is a transmission control data generating section as transmission control data generating means, 41 is an interrupt timer section as interrupt timer means, 42 is a multiplexing section, and the same reference numerals as in FIG.

Next, the operation will be described. The transmission control data generator 40 is required to periodically transmit the transmission clock synchronization information necessary for ensuring the synchronization of the transmission and reception clocks, the control information for the media information included in the multiplexed stream 45, and the auxiliary information. Data 43 is generated.

Multiplexed stream 4 of transmission control data 43
The multiplexing to 5 is performed by the interrupt signal 44 periodically generated from the interrupt timer unit 41. That is, when the interrupt signal 44 is generated in the multiplexing section 42, the selection of the encoded data by the multiplexing selection signal 25 is ignored and the control data 43 is selected and multiplexed into the multiplexed stream 45. When the interrupt signal 44 is generated, the timer of the interrupt timer unit 41 is set again, and the interrupt signal 44 is generated again after the elapse of a certain time. It should be noted that the ignored encoded data does not have a reduced storage amount, and is selected at the next multiplexing timing.

The transmission control data generating means and interrupt timer means shown in this embodiment may be combined with the invalid data generating means shown in the third embodiment.

FIG. 8 is an explanatory diagram for explaining the operation in such an embodiment. In FIG. 8, as in the case of FIG. 3, for simplicity, the number of coded streams is three, and the information generation rate and the multiplexing period of each medium are constant.

Times t0, t1, which are multiplexing timings,
At t2, each medium (multiplexing buffer 10a,
10b, 10c) comparing the accumulated amount of the multiplexing buffer,
Among them, the one having the largest storage amount is selected, and the multiplexed stream is generated as shown in FIG. However, the buffer storage amount Sa (t3), Sb (t3),
If Sc (t3) is less than the number of bits required for multiplexing, the multiplexing selection signal 2 from the multiplexing controller 13 indicates invalidity.
5 is output and the invalid data 42 is multiplexed.

In FIG. 8, at time t3, the buffer accumulation amounts Sa (t3), Sb (t3), Sc (t
Since 3) is less than m bits required for multiplexing, the multiplexing control unit 13 outputs the multiplexing selection signal 25 indicating invalidity and the invalidation data 42 is multiplexed. Next, at time t5, the stream number c is selected by comparing the accumulation amounts of the multiplexing buffers, but the generation of the interrupt signal 44 causes the multiplexing unit 42 to select the transmission control data 43, and the multiplexing is performed.

Fifth Embodiment of the Invention Further, the buffer storage amounts 23a, 2 of the multiplexing buffers 11a, 11b, 11c
When both 3b and 23c are less than m bits,
Multiplex selection signal 25 input to interrupt timer unit 41
Thus, if the interrupt signal 44 is generated regardless of the timer value, the transmission control data 43 can be multiplexed instead of the invalid data 42, and the multiplexing efficiency can be improved. After the transmission control data 43 is multiplexed, the timer of the interrupt timer unit 41 is set again.

Sixth Embodiment of the Invention FIG. 9 is a block diagram showing another embodiment of the present invention. In FIG. 9, FIG.
The same reference numerals as in FIG.

Next, the operation will be described. In FIG. 9, in each of the multiplex buffers 11a to 11n, the current buffer storage amount is subtracted from the capacity of each of the multiplex buffers to obtain the remaining buffer amounts 26a to 26n, which are calculated as the generated code amount of the encoded data. Control signal output means for outputting a control signal to each of the encoding units 10a to 10n is provided.

In the encoding unit 10a, the buffer remaining amount 26a
The information generation rate of the coded data 21a is controlled depending on the size of. That is, when the buffer remaining amount 26a is small, the information generation amount of the encoded data 21a is decreased, and conversely, when the buffer remaining amount 26a is large, the information generation amount of the encoded data 21a is increased.

As a result, the storage amount of the encoded data 21a can be prevented from overflowing the capacity of the multiplexing buffer 11a, and the multiplexing delay can be reduced by controlling the storage amount of the multiplexing buffer 11a. it can. Here, the encoding unit 10a has been described as an example, but the same operation is performed for the other encoding units 10b to 10n.

Seventh Embodiment of the Invention FIG. 10 is a block diagram showing another embodiment of the present invention. In FIG.
80a to 80n are encoding units, 81 is a multiplexing control unit,
The same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

Next, the operation will be described. In FIG. 10, the current buffer storage amounts 23a to 23n are input to the multiplexing control unit 81 from the multiplexing buffers 11a to 11n. As described in the first embodiment of the invention, the multiplexing control unit 81 selects an encoded stream to be multiplexed according to the size of the buffer storage amounts 23a to 23n, and outputs the multiplexed signal 25 to the multiplexing unit 12.

Further, the multiplexing control unit 81 obtains the total storage amount from the buffer storage amounts 23a to 23n, and according to the size, the coding control signal 82a to the coding control signal 82a to the control signal of the generated code amount of the coded data. 82n for each encoding unit 8
Control signal output means for outputting to 0a to 80n is provided.

For example, when the total amount of accumulated data is large, it indicates that a multiplexing delay has occurred in the entire multiplexer, so that the overall encoded data generation amount is controlled to be suppressed. On the contrary, when the total amount of accumulated data is small and a large amount of invalid data is generated, the overall encoded data generation amount is controlled to increase in order to increase the multiplexing efficiency.

As a result, the multiplexing delay time in the entire multiplexing device can be reduced and the multiplexing efficiency can be improved. Furthermore, since the amount of information generated in the encoding unit is controlled by the remaining amount of the multiplexing buffer, it is possible to adaptively follow the transmission rate of the multiplexed stream, and efficient and efficient multiplexing is always performed by effectively utilizing the transmission band.

[0082]

As described above, according to the present invention, coded data is selected and multiplexed based on the amount of data accumulated in each multiplexing buffer means, so that it is not necessary to predetermine the multiplexing pattern, It is possible to flexibly respond to changes in the transmission speed of the media and suppress the transmission delay.

Further, by selecting one having a large amount of accumulated data and multiplexing, the required capacity of the multiplexing buffer means can be minimized and at the same time the delay time associated with the multiplexing can be shortened. .

Further, by weighting the accumulated data amount, it is possible to preferentially multiplex the coded data with a small allowable delay time caused by the multiplexing, and to minimize the delay time. be able to.

Further, the speed of the multiplexed output generated by inserting invalid data can be adjusted.

Further, the interrupt timer means allows the transmission control data to be multiplexed periodically and preferentially regardless of the amount of data accumulated in the multiplexing buffer means.

Further, by transmitting the transmission control data instead of the invalid data, the multiplexing efficiency is improved.

Further, the generation amount of the encoded data is controlled by providing the multiplexing buffer means with a control signal output means for outputting a control signal for the generated code amount of the encoded data to be inputted, based on the accumulated data amount. Therefore, the storage amount can be prevented from overflowing the capacity of the multiplexing buffer means, the multiplexing buffer storage amount can be suppressed, and the multiplexing delay can be reduced.

Further, the multiplex control means is provided with a control signal output means for outputting a control signal of the generated code quantity of the above-mentioned coded data which is input based on the accumulated data quantity, so that the code quantity can be obtained from the delay quantity of the entire multiplexer. Since the amount of information generated by the multiplexing unit can be controlled, the multiplexing delay time in the entire multiplexing device can be reduced, and the multiplexing efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a multiplexing device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a multiplexing control unit of the multiplexing device according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an operation of the multiplexing device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration example of a fixed length packet according to the embodiment of the present invention.

FIG. 5 is a configuration diagram showing a multiplexing controller of the multiplexing device according to the embodiment of the present invention.

FIG. 6 is a configuration diagram showing a part of a multiplexing device according to an embodiment of the present invention.

FIG. 7 is a configuration diagram showing a part of the multiplexing device according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an operation of the multiplexing device according to the embodiment of the present invention.

FIG. 9 is a configuration diagram of a multiplexing device according to an embodiment of the present invention.

FIG. 10 is a configuration diagram of a multiplexing device according to an embodiment of the present invention.

FIG. 11 is a block diagram showing an example of a conventional multiplexing device.

FIG. 12 is an explanatory diagram showing a structure of a multiplexing frame in a conventional multiplexing device.

FIG. 13 is a configuration diagram showing another multiplexer of the conventional example.

[Explanation of symbols]

 10a to 10n Encoding section 11a to 11n Multiplexing buffer section 12 Multiplexing section 13 Multiplexing control section 27 Buffer storage amount comparing section 40 Transmission control data generating section 41 Interrupt timer section 42 Multiplexing section 50 Weighting coefficient table 51 Weighting section 52 Comparison section 80 Encoding unit 81 Multiplexing control unit

Claims (8)

[Claims] 1. A plurality of multiplexing buffer means for accumulating encoded data, a multiplexing means for multiplexing and outputting the encoded data accumulated in each of the multiplexing buffer means, and each of the multiplexing buffer means. Multiplexing control means for selecting the coded data to be multiplexed and output by the multiplexing means from the coded data stored in the plurality of multiplexing buffer means based on the accumulated data amount of the coded data. Multiplexing device characterized by. 2. The multiplexing control means preferentially selects, as the multiplexed output, the coded data accumulated in the multiplexing buffer means having the largest accumulation amount among the accumulated data amounts of the respective multiplexing buffer means. The multiplexing device according to claim 1, wherein 3. The multiplexing control means has a weighting means for weighting the accumulated data amount of each of the multiplexing buffer means, and selects the multiplexed output based on the accumulated data amount weighted by the weighting means. The multiplexing device according to claim 1, characterized in that. 4. An invalid data generating means for generating invalid data is provided, and the multiplexing control means is operable to generate the invalid data generating means when the accumulated data amount of each of the multiplexing buffer means is less than a predetermined amount. 4. The multiplexer according to claim 1, wherein the invalid data output by the above is selected as a multiplex output. 5. A transmission control data generating means for generating transmission control data, and an interrupt timer means for measuring an interval for transmitting the transmission control data are provided, wherein the multiplex control means is based on a time measurement result by the interrupt timer means. 5. The multiplexing apparatus according to claim 1, wherein the transmission control data output by the transmission control data generating means is selected as a multiplexed output. 6. The multiplexing control means uses the transmission control data output from the transmission control data generating means as multiplexed output when the amount of data stored in each of the multiplexing buffer means is less than a predetermined amount. 6. The multiplexing device according to claim 5, wherein the interrupt timer means is selected and set to a time counting start state. 7. The multiplex buffer means comprises control signal output means for outputting a control signal of the generated code amount of the input coded data, based on the accumulated data amount. 7. The multiplexing device according to any one of 1 to 6. 8. The multiplexing control means comprises control signal output means for outputting a control signal of the generated code amount of the input coded data, based on the amount of data stored in each of the multiplex buffer means. 7. The multiplexing device according to claim 1, which is characterized in that.