JP2000049726A - Multiplexing device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the simplicity of a control method for the operation of data after multiplexing, while reducing delay generated in multiplex buffers and improving the multiplex efficiency. SOLUTION: In plural multiplex buffers 32, streams 31 of PES of plural channels are respectively temporarily stored. A channel selection control part 43 controls the selection of multiplex channels from among the plural channels, read from the multiplex buffers 32 and the changeover of a switch 44. Thus, the multiplex streams of TP are outputted from the switch 44. At generating of the multiplex streams from the leading byte of a PES start code to the final byte of DTS for instance among the streams 31 of the PES of the plural channels, multiplexing is performed without performing division into packets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multiplexing apparatus and method for inputting stream data such as video and audio of a plurality of programs, packetizing the data, and multiplexing the data into a single bit stream.

[0002]

2. Description of the Related Art In recent years, in a moving image signal transmission system, a so-called MPEG (Moving Picture Expert Group) has been used.
2 and the like, perform coding and multiplexing using image and audio compression technology and multiplexing technology, and transmit a high-quality image signal of a plurality of programs using a single bit stream under a limited transmission band. Widely known.

As described above, encoded data of a plurality of encoded video and audio programs are packetized and multiplexed, and at the same time, each program is indispensable for normal decoding on the receiving side of these programs. Program clock reference (hereinafter referred to as PCR) data, which is a program time reference reference value unique to each program, and program specific information (hereinafter referred to as PSI) required to separate and decode a desired program. Write)
A multiplexing device that packetizes data, multiplexes the data, and outputs the multiplexed data is known.

As the multiplexing device, a multiplexing device as shown in FIG. 10 has already been proposed and will be described below.

[0005] The packetized elementary stream (Pa)
A stream 101, which is a cketized Elementary Stream (hereinafter, referred to as PES), is supplied from a plurality of encoding devices, and is read by the input control unit 103 one byte at a time. P
The ES is obtained by encoding an image or audio data into an elementary stream (hereinafter, referred to as ES) by an encoding device and packetizing the data with a certain data length. The header part of the PES includes an elementary stream clock reference (Elem) which is a reference clock.
entary Stream Clock Reference (hereinafter abbreviated as ESCR), and a presentation time stamp (hereinafter abbreviated as P) which is playback output time management information.
TS), and data of a decode time stamp (DTS), which is decoding time management information. PTS and DTS are access units (Access Uniform) which are coding units for decoding.
t, hereinafter referred to as AU), and a presentation unit (Presentation Unit,
This is data indicating when to decode or display the “PU”, and is important data for synchronization management.

[0006] The input control unit 103 controls each multiplex buffer 10
2, a control unit that supplies the input PES stream 101 as it is, extracts the PES header and the information of the ES header of video and audio, and transmits the information to the channel selection control unit 113.

Each multiplexing buffer 102 has a PES
Is a buffer memory of a FIFO (first-in first-out) format for temporarily storing the stream 101, and data is transport packets therein.
) And waited until multiplexed. When a plurality of streams are input to the multiplexer at asynchronous timing, the multiplexing buffer 102 is necessary for packetizing the plurality of streams into a predetermined length within the multiplexer and multiplexing them. Buffer.

[0008] The control data generation unit 105 includes a PSI, which is program specification information necessary for selecting and decoding a desired program on the receiving side, and a service, which is various service information on the whole or a part of the program. Information (Service Information,
(Hereinafter referred to as SI) is generated and converted to TP. In some cases, a PCR unique to each program is generated as a reference value using a system time generated from a basic clock in the multiplexer. Then, a transmission interval for each control data is managed by a timer, and when it is time to transmit certain control data, a multiplexing request for the control data is sent to the channel selection control unit 113, and at the same time, The TP is made to wait in an output register in the control data generation unit 105.

In the null packet generation unit 106, when the PES data and the control data cannot be multiplexed,
Although it is a code having no meaning as data, a TP as a code for filling a gap in a bit stream is generated and is kept on standby.

When the PES stream 101 is read from each multiplexing buffer 102 for multiplexing, the TP header generating unit 109 generates a TP header that needs to be multiplexed prior to the multiplexing.

The channel selection control unit 113 determines which channel code of the control data generation unit 105, each multiplex buffer 102 and the null packet generation unit 106
A control unit that determines whether or not to select P and sends a selection signal to the switch 114 to control the multiplex channel. The control data is important data for decoding on the receiving side, and explicit restrictions are set for the transmission interval, and control is performed so that multiplexing is preferentially performed. That is,
The channel selection control unit 113 controls the control data generation unit 10
5, when a multiplex request is received for certain control data, control is performed to multiplex the control data. If control data is not multiplexed,
Multiplex buffer 102 in which stream data is occupied
When either one of the above is selected, the switch 114 is controlled so that reading from the TP header generating unit 109 is performed prior to reading from the multiplex buffer 102. In this case, of the contents described in the TP header, parameters that change depending on the channel to be read and the timing are sent. The contents to be sent at this time include the packet ID
(Packet ID, hereinafter referred to as PID) and adaptation field control (adaptation_field_contro
l), stuffing byte (stuffing_byte), adaptation field data (adaptation_field_dat)
a) and so on.

The code multiplexed by the switch 114 is sent to the multiplexed data operation unit 116 as a TP code.

In the multiplex data operation unit 116, if the PTS or DTS value of the multiplexed PES stream is not appropriate for the PCR of the program,
The PTS or DTS value is replaced, and the output control unit 119
Send to For example, when the PCR is generated from a value according to the system time of the multiplexing device, the input control unit 103 acquires the ESCR based on the information of the PTS and the DTS in the PES stream together with the PTS and the DTS, and After clarifying the phase relationship of
PTS or DTS with proper phase relationship with PCR actually sent
Replace with a value.

The output control unit 119 measures the timing in accordance with the system clock of the multiplexer, and
A TS (Transport Stream) 120 is read and output.

The multiplexing process is performed as described above. However, in the multiplexing buffer 102, a delay occurs in the transmission of data such as images and sounds. If the delay increases, the multiplexing buffer may be broken unless the multiplexing buffer size for each channel in the multiplexing device is made sufficiently large. There's a problem. In addition, an increase in delay may cause the proper synchronization phase relationship of the bit stream originally possessed to be broken. For example, at the moment when the receiving side attempts to decode the AU corresponding to the received PTS or DTS, if the necessary data is not completely transmitted, the AU cannot be decoded. Occurs.

Therefore, the channel selection controller 113 sets the multiplexing buffer 10 in a cycle for multiplexing one packet.
When selecting a channel to be actually multiplexed from the stream data stored in the multiplex buffer 2, the delay amount in the multiplex buffer 102 is reduced as much as possible, that is, the data occupation amount in the multiplex buffer 102 is not increased. By the method, a multiplex channel is determined before multiplexing of one packet is started.

As an example of such a multiplex channel determination method, the applicant of the present application has disclosed in the specification and the drawings of Japanese Patent Application No. 10-148137, when determining a channel to be multiplexed for a plurality of stream data, A method is proposed in which the occupancy of the buffer 102 is monitored and control is performed to select the channel having the largest occupancy. Further, when the occupation amount of the channel selected in this manner is less than the data amount of one packet, the data amount of the overhead is forcibly increased, that is, dummy bytes are added to the data amount of less than the size of one packet. A method of multiplexing data into one packet format by packing is used. In this way, a control method for channel selection that minimizes the size of the multiplexing buffer 102 and minimizes the delay that occurs during multiplexing can be considered.

[0018]

However, for example, in a multiplexing apparatus as shown in FIG. 10, when a multiplex channel is determined from a plurality of stream data, the multiplex buffer 102 stores only a data amount of less than one packet. Even if the data is not stored, if even one byte is stored in the buffer, there is a method in which dummy data is forcibly packed and multiplexed in the form of one packet. If an operation is to be performed on the contents, the control for this operation is complicated.

FIG. 11 shows the structure of a PES in MPEG2. PES consists of PES header and PES
It consists of payload data. PES payload data is usually composed of ES data. The PES header is
As shown in FIG. 11, if it is a video PES, an optional PES header exists. The optional PES header may, but not always, include PTS and DTS that are synchronization management information. If the DTS is included, all the codes of the DTS can be expressed by 19 bytes counted from the first byte of the PES. MPE
According to the provisions of G2, the beginning of the PES and the beginning of the payload byte of the TP must be aligned. Therefore, when packetizing into a TP, to fit the entire DTS code from the beginning of the PES into one TP, the PES must be aligned. When multiplexing the head, at least 19 bytes must be multiplexed.

If the PES head code is multiplexed and multiplexed as a TP payload of 20 bytes or more, control by the multiplexed data operation unit 116 is easy. If the head code of PES is detected, if PT
When S or DTS is included in the PES header, its code position can be determined, and PTS or DTS can be replaced at a time.

However, if the head code of the PES is multiplexed and only less than 19 bytes are multiplexed as a TP payload, the multiplexed data operation unit 1
The control at 16 becomes complicated. Control cannot be performed in the same way as when multiplexing over 20 bytes, and PTS and DT
It is necessary to independently detect at which timing the S code is multiplexed. Furthermore, PTS and DT
If only a part of the entire S code is multiplexed,
There is a problem that bit manipulation must be performed over a plurality of packets, and the control becomes complicated.

Accordingly, the present invention has been made in view of such a situation, and has a control for operating data after multiplexing while reducing a delay generated in a multiplexing buffer and improving multiplexing efficiency. It is an object of the present invention to provide a multiplexing apparatus and method capable of maintaining the simplicity of the method.

[0023]

SUMMARY OF THE INVENTION A multiplexing apparatus and method according to the present invention divides a plurality of stream data into predetermined packets and multiplexes them, and temporarily stores a plurality of stream data, respectively. When a multiplex channel to be multiplexed among the channels is selected and stored stream data is read and controlled as packet data, and the packet data obtained by the selection and read control is multiplexed to generate a multiplex stream, a plurality of streams are generated. By multiplexing certain continuous data strings in the same packet among data,
The above-mentioned problem is solved.

In the multiplexing apparatus and method according to the present invention, the channel storing the most stream data is selected as a multiplex channel candidate, and the storage amount of the stream data of the channel selected as the candidate is determined by a predetermined threshold value. If this is the case, multiplexing is determined, and if it is less than the threshold, the procedure of excluding the channel from multiplex channel candidate targets is repeated.

Also, the multiplexing apparatus and method of the present invention outputs the detection of a start code of data that needs to be multiplexed at the beginning of a packet as a start code input detection signal, Is used to output a storage start code detection signal indicating whether or not the start code is stored as stream data of the corresponding channel, and control the multi-channel selection based on the storage start code detection signal.

Further, the multiplexing apparatus and method of the present invention detects a position of a specific continuous data string in stream data, and sets a flag synchronized with the stream data to designate a byte position of the specific continuous data string. The data is output, combined with the stream data, and the flag data is stored in correspondence with each byte of the stream data. Multiple channel selection is controlled based on the flag data.

More specifically, according to the present invention, when performing some operation on the multiplexed data when reading the payload data from the multiplexing buffer when multiplexing the packets, the payload to be multiplexed is read. Of the data, a limit on the length of the payload data to be read is always set so as to be multiplexed from the beginning to the code portion for performing the operation.

Alternatively, the constraint condition on the payload data length to be read is changed according to the situation. That is, if no operation is performed on the multiplexed data,
Eliminates restrictions on multiplexed payload data length,
When any operation is performed, a restriction is imposed on the payload data length to be multiplexed so that the data length required for performing the operation is always multiplexed.

Alternatively, 1-bit division multiplexing inhibition flag data is stored in synchronization with the data stored in the multiplexing buffer so that a specific continuous data string to be read is always multiplexed in one packet. By evaluating the flag data, it is determined whether multiplexing is possible.

In this way, the multiplexing efficiency is improved by reducing the delay generated in the multiplexing buffer.
The simplicity of the control method for operating data after multiplexing is maintained.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

Before describing the multiplexing apparatus and method of the present invention, a specific example system to which the multiplexing apparatus and method of the present invention is applied will be described with reference to FIGS.
FIGS. 1 and 2 show an example in which the multiplexing apparatus and method of the present invention are applied to, for example, a digital satellite broadcasting system.

First, a schematic configuration of the digital satellite broadcasting system 1 will be described.

The digital satellite broadcasting system 1 comprises a transmitting device 2 and a receiving device 4. The transmitting device 2 encodes and multiplexes video and audio signals to generate a transmission signal. A transmission signal transmitted to the satellite 3 is received by the receiving device 4 and a video / audio signal is reproduced.

The transmitting apparatus 2 performs an encoding process on video and audio information by using an information compression technique such as MPEG2 to generate a PES stream, and generates n PES stream generators 10 and n PES streams. The stream is decomposed into transport packets in a relatively short transmission unit of, for example, 188 bytes, and the plurality of transport packets are connected by time-division multiplexing. Device 1
An error correction unit 12 that performs encoding for error correction in advance so that a correct code can be restored on the receiving side even if transmission noise is superimposed on TS from No. 1 and an output code from the error correction unit 12 A modulation unit 13 for performing digital modulation processing by so-called QPSK or the like;
And

The n PES stream generators 10 include:
As shown in FIG. 2A or FIG. 2B, an encoding device (encoder) is built in, and this encoding device performs, for example, compression encoding by MPEG2. In FIG. 2A, the video signal and the audio signal generated by two data generators 20 including, for example, an optical disk playback device and a hard disk device are compression-encoded by MPEG2 by the corresponding encoders 21 and multiplexed. 3 shows an example of the configuration of a PES stream generation unit that generates one program (program) by multiplexing in a unit 22 and generates a PES stream from an output terminal 23. FIG. 2B shows a configuration example of a PES stream generation unit that compresses and encodes, for example, an image signal from the data generation device 24 by the encoder 25 using MPEG2 and generates a PES stream.

A plurality of output codes (PES streams) from such n PES stream generators 10
Is input to the multiplexing device 11 of the present embodiment, packetized into a TP, multiplexed, and output as a TS. The error correction unit 12 performs encoding for error correction in advance so that the receiving side can correct a correct code even if noise generated during transmission is superimposed on the TS. The output code of the error correction unit 12 is
The signal is digitally modulated by SK or the like, output, and transmitted from the transmitting antenna 14 to the artificial satellite 3.

Next, an outline of the receiving device 4 will be described. The RF signal emitted from the artificial satellite 3 is received by the receiving antenna 16, and is received by the LNB (Low Noise Block Converte).
r) 15, the IF signal is subjected to frequency conversion to an intermediate frequency, and is called an integrated receiver / decoder (so-called set-top box).
r; hereinafter referred to as IRD). IRD17
Then, an IF signal is input, demodulation, separation of video / audio code into a desired program, and decoding signal processing are performed.
A video / audio signal that can be reproduced by the V receiver 18 is output.

In the digital satellite broadcasting system 1 whose outline has been described above, the multiplexer 11 according to the embodiment of the present invention includes n (n-channel) PESs of, for example, 1 PES.
The packet is decomposed into transport packets in a relatively short transmission unit of 88 bytes, these transport packets are time-division multiplexed and connected, and output as TS.

Next, a first example of the multiplexing apparatus and method of the present invention will be described.
Embodiment (multiplexing apparatus 11 in FIG. 1) is described in FIG.
This will be described with reference to FIG.

The PES stream 31 is supplied from a plurality of encoding devices (PES stream generators 10) as shown in FIG. 1 and is read by the input controller 33 one byte at a time. In FIG. 3, the PES stream 31
Are set to three (three channels).

The input control unit 33 supplies the input PES stream 31 to each multiplexing buffer 32 as it is, extracts the PES header and the information of the video and audio ES header, and transmits the information to the channel selection control unit 43. Department.

Each multiplexing buffer 32 is a buffer memory of a FIFO format for temporarily storing the stream 1 of the PES, in which data is packetized as a TP and waited until multiplexed.

The control data generator 35 generates PSI, which is information necessary for selecting and decoding a desired program on the receiving side, and SI, which is various information about the whole or a part of the program, and I will make it.
In some cases, using the system time generated from the basic clock inside the multiplexer of the present embodiment,
A PCR unique to each program is generated as the reference value. Then, a transmission interval for each control data is managed by a timer, and when it is time to transmit certain control data, a multiplexing request of the control data is sent to the channel selection control unit 43, and at the same time, the control data The TP is made to wait in an output register in the control data generator 35.

The null packet generator 36 generates a TP as a code that has no meaning as data at a timing when neither the PES data nor the control data can be multiplexed, and fills a gap in the bit stream and waits. Let it be.

When the PES stream 31 is read out from the multiplexing buffer 32 for multiplexing, the TP header generator 39 needs to multiplex the TES prior to the multiplexing.
Generate a P header.

The channel selection control unit 43 determines which channel code is to be selected as the TP among the channels of the control data generation unit 35, each multiplex buffer 32, and the null packet generation unit 36, and selects the switch 44. It is a control unit that controls multiplex channels by sending signals. The control data is important data for decoding on the receiving side, and explicit restrictions are set for the transmission interval, and control is performed so that multiplexing is preferentially performed. That is, the channel selection control unit 43
5, when a multiplex request is received for certain control data, control is performed to multiplex the control data. If control data is not multiplexed,
When any one of the multiplex buffers 32 in which the stream data is occupied is selected, the switch 44 is controlled so as to read from the TP header generation unit 39 prior to reading from the multiplex buffer 32. In this case, of the contents described in the TP header, parameters that change depending on the channel to be read and the timing are sent. The contents to be transmitted include PDI, adaptation field control (adaptation_field_control), stuffing byte (stuffing_byte), adaptation field data (adaptation_field_data), and the like.

The code multiplexed by the switch 44 is
The TP code is sent to the multiplex data operation unit 46.

In the multiplexed data operation unit 46, if the value of the PTS or DTS of the multiplexed PES stream is not appropriate for the PCR of the program, the PT
The S and DTS values are replaced and sent to the output control unit 49. For example, when the PCR is generated from a value according to the system time of the multiplexing apparatus, the channel selection control unit 43 uses the PTS or DT in the channel selection control unit 43 based on the PTS or DTS information in the PES stream.
After acquiring with S, clarifying the phase relationship with the ESCR, the PTS with the proper
Or a DTS value.

The output control section 49 measures the timing in accordance with the system clock of the multiplexer of this embodiment, reads out and outputs the TS.

Here, in the first embodiment of the present invention, the channel selection control unit 43 actually multiplexes the stream data stored in the multiplex buffer 32 at a cycle of multiplexing one packet. When selecting a channel, the multiplexing channel is reduced by the time that multiplexing of one packet is started in such a manner that the amount of delay in the multiplexing buffer 32 is minimized, that is, the amount of data occupied in the multiplexing buffer 32 is not increased. decide.

In order to realize this, the channel selection control unit 43 has a configuration as shown in FIG. 3 and performs a procedure as shown in a flowchart in FIG.
Note that the internal configuration of the channel selection control unit 43 actually represents a software operation as a functional block. The flowchart of FIG. 4 shows a channel selection algorithm when multiplexing a PES stream in the channel selection control unit 43.

The channel selection control unit 43 first reads the occupation amount of the multiplex buffer 32 of each channel in step S1. The occupancy data of each of these multiplex buffers 32 is sent to the search and comparison block 51.

In step S2, the search comparison block 51 of the channel selection control section 43 searches for the largest channel among the occupancy data obtained from each channel. In this case, the occupancy data may be raw data of the obtained occupancy or data weighted by a channel. When multiplexing stream data such as audio (audio) data that is input at a very low rate compared to the output bit rate, other multiplexing channel determination methods that use the occupancy itself as a comparison target of the occupancy are other methods. Since there is a possibility that the amount of delay may increase as compared with channel data of a high rate such as video data, occupancy data may be used as data for weight comparison of occupancy depending on the channel.

As described above, when a certain channel is selected as one candidate (hereinafter, referred to as candidate selection), the search comparison block 51 of the channel selection control unit 43
Then, in step S3, the raw data of the occupancy of the channel selected as the candidate is evaluated, and it is determined whether or not the value is equal to or larger than the threshold Th. The threshold value Th is supplied from, for example, a Th generation block 52 constituted by a memory or the like, and the comparison result in the search comparison block 51 is sent to a control block 53.

Step S in the search / comparison block 51
If the occupation amount is determined to be equal to or greater than the threshold Th in the determination process of step 3, the control block 53 proceeds to step S
4, a multiplexing buffer 3 for actually performing multiplexing
2 and the switching control of the switch 44. In this case, if the occupation amount is less than the number of bytes of one packet, the information of the number of bytes of the stuffing bytes to be multiplexed prior to the payload data from the multiplexing buffer 32 is also sent to the TP header generation unit 39. Keep it.

On the other hand, if the occupation amount is less than the threshold value Th as a result of comparing the occupation amount with the threshold value Th in the determination processing of step S3 in the search / comparison block 51, the control block 53 proceeds to step S5. Is excluded from the channels to be multiplexed and multiplexing is not performed on the channel, and control is performed so as to compare with the threshold value Th in the same manner as described above for the channel having the second largest occupancy.

That is, the control block 53 determines, at step S6, whether or not the number of channels to be multiplexed is one or more. Search for the largest channel, and then step S
Return to 3. If it is determined in step S6 that the number of channels to be multiplexed has disappeared, that is, if the occupation amounts of all the channels are all equal to or smaller than the threshold Th, the control block 53 determines in step S7 that the null packet from the null packet generation unit 36 The switch 44 is controlled so as to multiplex.

By the way, as for the threshold value Th, if only reduction of the multiplex buffer size is considered, Th = 1.
(Byte), but as described above, in order to facilitate control for operating the content of the multiplexed data, the value of the threshold Th is
Set as the smallest value under the condition that all the data to be operated are always included. That is, since the PTS and DTS codes as the synchronization management information are included at the most within the first byte of the PES, that is, within 19 bytes counted from the first byte of the TP payload, a value of 19 bytes or more (the first embodiment) In the embodiment, for example, it is set to Th = 20, which is obtained by adding 1 to 19 bytes, and it is determined whether or not the data of the channel selected as the candidate is actually multiplexed.
Therefore, of the packet data obtained by multiplexing the stream data, 20 bytes are always payload data for the TP, and the multiplexed data operation unit 46 can easily replace PTS and DTS which are data for synchronization management. Become.

The threshold value Th can be set to a different value for each channel. For example, the threshold value is set to Th = 20 for the first channel, the threshold value is set to Th = 30 for the second channel, and the threshold value is set to Th = 30 for the third channel. For example, if the threshold is T
h = 25, the threshold value of the fourth channel is, for example, Th = 1
It is also possible to perform threshold control for each channel such as 9,. In this case, the Th generation block 52 stores, for example, the threshold value Th for each channel, and the threshold value Th corresponding to the channel selected as the candidate is extracted.

Next, the second embodiment of the multiplexing apparatus and method of the present invention will be described.
The embodiment will be described with reference to FIGS. 5 and 6. FIG.

FIG. 5 shows a configuration example of a multiplexing apparatus according to the second embodiment. 5 that are substantially the same as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. The following mainly describes different parts.

In FIG. 5, the channel selection control section 43
In order to determine the channel to be actually multiplexed from the stream data stored in the multiplexing buffer 32 before starting the multiplexing of one packet, the delay amount in the multiplexing buffer 32 is reduced as much as possible. The channels to be multiplexed are selected in such a way that the data occupancy at 32 is not increased. For this purpose, as in the first embodiment, the following procedure is performed to determine a multiplex channel.

First, the occupancy of the multiplex buffer 32 of each channel is read. Next, the maximum data is searched for the occupancy data obtained from each channel. In this case, the occupancy data may be raw data of the obtained occupancy, or data weighted by the channel as described in the first embodiment. Next, the raw data of the occupancy of the channel selected by the candidate is evaluated, and it is checked whether or not the value is equal to or larger than a threshold Th. If so, a multiplexing buffer for actually performing multiplexing Read control and switch 4
4 is controlled. If the occupancy is less than the number of bytes of one packet, the TP header generator 39 also sends information on the number of bytes of the stuffing bytes to be multiplexed prior to the payload data from the multiplex buffer 32.

However, in the case of the second embodiment, the threshold T
h is different from the first embodiment and is changed as follows depending on the time.

That is, when the head data of the packet including the data to be operated in the multiplex data operation unit 46 actually exists in the multiplex buffer 32, the first threshold Th1 is applied as the threshold Th. For example, P
Since the codes of TS and DTS are always multiplexed within 19 bytes from the first byte of the TP payload, a value of 19 bytes or more (for example, Th1 = 1 in the second embodiment)
Set to 9). On the other hand, if the head portion of the data is not in the multiplex buffer 32 selected as the candidate, the second threshold Th smaller than the first threshold Th1 is set as the threshold Th.
Apply 2. For example, Th as the second threshold value Th2
= 1 is used. If multiplexing is controlled by using the channel selection algorithm as shown in FIG. 4 using the threshold value Th that fluctuates in such a packet multiplexing cycle, when performing data operation in the multiplexed data operation unit 46, one packet The data can always include the entire target code.

A method for variably setting the threshold value Th as in the second embodiment will be described below.

The input control section 33 has a head byte detection block 38 for always detecting the input of the head byte of the PES. In the first byte detection block 38, the PE
If it detects that the first byte of S has been input, it outputs a start code input detection signal 65 notifying that. The leading byte detection block 38 also superimposes the input channel number on the start code input detection signal 65.

The start code detecting unit 63 in the buffer
The start code input detection signal 65 and the multiplexed data (multiplexed stream) 64 selected by the switch 44 are input, and the P data stored in the multiplexing buffer 32 of each channel is input.
The number of head codes of the ES is counted, and the count value 66 for each channel is output to the channel selection control unit 43.

Here, the in-buffer start code counting section 63 has a specific configuration as shown in FIG.

In FIG. 6, a start code input detection signal 65 is sent to an input channel identification filter 67, and the multiplexed data 64 is sent to a channel identification filter 68.

The input channel identification filter 67 identifies the input channel from the start code input detection signal 65, and counts up to the counter corresponding to the input channel among the plurality of start code counters 70 every time the head of the PES is detected. Input the signal. The start code counter 70 counts up each time a count-up signal is input.

The channel identification filter 68 identifies which channel data has been multiplexed from the multiplexed data 64 and sends the multiplexed data 64 to the start code detector 69.

The start code detector 69 detects the start code of the multiplexed data 64 from the channel identification filter 68, that is, the head code of the PES. Each time the head code of the PES is detected, the start code detector 69 detects the start code of the plurality of start code counters 70. The countdown signal is input to the counter corresponding to the channel. The start code counter 70 counts down every time a countdown signal is input.

In this way, the start code counter 70 corresponding to each channel can hold the number of PES head codes stored in the multiplex buffer 32.

Then, each start code counter 70
The held count value is output, and the
Send to 1.

The multiplexer 71 multiplexes the count value from each start code counter 70, that is, the count value 66 of the number of head codes of the PES present in the multiplexing buffer 32 of each channel, and multiplexes the channel once at every packet multiplexing cycle. It is sent to the selection control unit 43.

When the output (count value) from the start code counter 70 of a certain channel is 1 or more, the channel selection control section 43 can regard that the head code of the PES exists in the multiplex buffer 32 of the channel. Therefore, the channel selection control unit 43 performs the first comparison if the output (count value) from the start code counter 70 corresponding to the channel to be evaluated is 1 or more when performing the magnitude comparison with the threshold Th. The threshold value Th1 is set, and if not, the second threshold value Th2 is set.
Note that the data (count value) output from the start code counter 70 is not the count value itself, but 1 indicating only whether the start code exists in the multiplex buffer.
It is also possible to use only a bit start code flag.

As described above, in the second embodiment,
The threshold value Th can be changed, and a buffer start code counting unit 63 is provided as a configuration for that. That is, the channel selection control unit 43 sets the threshold value Th output from the Th generation block 52 based on the count value 66 from the in-buffer start code counting unit 63 by the first threshold value Th and the second threshold value Th. I try to switch. In this case, T in the channel selection control unit 43
The h generation block 52 includes a first threshold Th and a second threshold T
The threshold value stored in the Th generation block 52 is read out based on the count value 66.

In the case of the second embodiment, as in the case of the first embodiment, the first and second threshold values Th are used.
1 and Th2 can be set to different values for each channel. For example, in the first channel, the threshold value is set to Th1.
= 19, Th2 = 1, threshold values are, for example, Th1 = 20, Th2 = 1 for the second channel, threshold values are, for example, Th1 = 30, Th2 = 2 for the third channel, and threshold values are, for example, Th1 = 25, Th2 for the fourth channel. = 0,... Can be controlled for each channel. In this case, the Th generation block 52 stores the first and second threshold values Th1 and Th2 for each channel,
First and second threshold values Th according to the channel selected as the candidate
1, Th2 is taken out.

Next, the third embodiment of the multiplexing apparatus and method according to the present invention will be described.
The embodiment will be described with reference to FIGS.

FIG. 7 shows a configuration example of a multiplexing apparatus according to the third embodiment. In addition, in each component in FIG. 7, substantially the same as each component in FIG. 3 is denoted by the same reference numeral, and the description thereof is omitted, and the following description will focus on different parts.

In FIG. 7, on the output side of the input control unit 33, a 1-bit data line 62 different from the line 61 for outputting the PES stream 31 in byte units is provided, and these data lines 61 and 62 are multiplexed. Connect to buffer 32. That is, in the third embodiment, the input control unit 33 has a flag generation block 37 that generates a division multiplexing prohibition flag for the purpose of multiplexing a specified data string within the same TP, This division multiplexing inhibition flag is sent to the corresponding multiplexing buffer 32 via the data line 62.

Here, the flag generation block 37 of the input control unit 33 generates the above-mentioned division multiplexing inhibition flag and controls the output as follows. That is, when one byte of input stream data is a part of a data string to be multiplexed collectively in the same TP, the division multiplexing inhibition flag is set to "1" in a bit synchronized with the data byte. If it is not the last byte of the data string or if it is not such a data string, the division multiplexing inhibition flag is set to "0". For example, as shown in FIG. 8, in order to easily operate the PTS or DTS after multiplexing, the flag “1” is synchronized with the data in which the PES start code multiplexed before the PTS or DTS is located.
Is set, and the flag “1” is continued until a position synchronized with the byte immediately before the last byte of the PTS or DTS thereafter. When the PTS and DTS flags are extracted and it is determined that the PTS or DTS is not included in the PES header, the division multiplexing inhibition flag is immediately set to “0”.

In each of the multiplexing buffers 32 to which the division multiplexing inhibition flag is supplied as described above, like the PES data,
The division multiplexing inhibition flag is also stored so that the correspondence relationship with the PES data in byte units can be understood. For example, each multiplexing buffer 32 is provided with a line buffer 34, and by storing a division multiplexing prohibition flag in the line buffer 34, the correspondence between the division multiplexing prohibition flag and the PES data in a byte unit can be understood. To

In the case of the third embodiment, the channel selection control section 43 performs a procedure as shown in the flowchart of FIG. The flowchart in FIG. 9 shows a channel selection algorithm when the channel selection control unit 43 performs control using the division multiplexing inhibition flag.

The channel selection control unit 43 of the third embodiment reads the occupancy of the multiplexing buffer 32 of each channel at the same time as step S11, and at the same time, of the occupied data, The division multiplexing inhibition flag corresponding to the data byte to be read is read.
The occupancy data of each of the multiplex buffers 32 is sent to the search / comparison block 51 of FIG.

Next, in the search / comparison block 51 of the channel selection control section 43, as in step S12, the largest channel among the occupancy data obtained from each channel is selected as described above. If one channel is determined to be a candidate selection channel in this way, the search and comparison block 51 determines in step S13 that the occupancy of the multiplex buffer 32 of the candidate selected channel is equal to or greater than the byte length of one packet. It is determined whether or not there is.

In the discriminating process of step S13,
If the occupation amount of the multiplex buffer 32 of the channel selected as the candidate is equal to or more than the byte length of one packet, the control block 5
3 performs multiplex control of one packet on the channel in step S14. That is, the control block 53
Performs read control of the multiplexing buffer 32 and switching control of the switch 44 for actually performing multiplexing.

On the other hand, if the occupancy of the multiplex buffer 32 of the channel selected as a candidate is less than the byte length of one packet in the determination processing of step S13, the control block 53 determines in step S15 that the It is checked whether "1" is set in the division multiplexing inhibition flag.

If it is determined in step S15 that the division multiplexing inhibition flag is not set to "1",
The control block 53 performs multiplex control of one packet on the channel as step S16.

On the other hand, if the division multiplexing inhibition flag is set to "1" in the determination processing of step S15, the control block 53 removes the channel at that time from the multiplexing target channel as step S17, and Avoid multiplexing on channels. Thereby, it is possible to prevent a data sequence to be multiplexed in the same TP from being multiplexed over a plurality of TPs.

Next, the control block 53 executes step S1.
At S8, it is determined whether or not the number of multiplexing target channels is one or more. If there is one or more, at step S20, the channel having the largest occupancy data is selected from those channels, and then the process returns to step S15. If it is determined in step S18 that the number of channels to be multiplexed has been exhausted, the control block 53 proceeds to step S19.
, The switch 44 is controlled so as to multiplex null packets from the null packet generator 36.

In the third embodiment, as for the control of the division multiplexing inhibition flag in the input control section 33, as shown in FIG. 8, the flag is set to "1" from the position synchronized with the PES start code. Not PT
Control may be performed so that a flag is set from a position synchronized with the first byte of S. By doing so, the data range of the multiplex division prohibition flag is reduced, and the multiplexing efficiency is further improved.

The method of setting the division multiplexing prohibition flag is not limited to the method described above. Of the series of data strings for which division multiplexing is to be prohibited, the first byte and the last byte are indicated so as to indicate the first byte and the last byte. The flag “1” may be set only at the bit position corresponding to the byte.

Also, the flag "1" is set only at the start byte of the data string which must not be subjected to division multiplexing, for example, the first byte of the PES start code prefix, and the first byte of the channel selected as a multiplex channel is set. If the division multiplexing inhibition flag is set to "1", the threshold Th in the second embodiment is set as the first threshold Th1, and the same algorithm as in the second embodiment is executed. The channel selection control may be performed by using this.

In the above, the threshold value Th has been described as using the threshold value Th in the first embodiment and the first threshold value Th1 and the second threshold value Th2 in the second embodiment. When operating on data, if there are a plurality of data lengths in a data range operated by a packet, a threshold value corresponding to each data length may be given. Accordingly, in the second embodiment, the in-buffer start code counting unit 63
, The number of counters that count the number of times data requiring operation of multiplexed data is detected is (number of channels) ×
It is necessary to increase the threshold value by an amount corresponding to the increase number. Further, in the third embodiment, it is necessary to increase the number of bits of data indicating the data detection timing for operating the multiplexed data output from the input control unit 33 to the multiplexing buffer 32.

As described above, according to each of the embodiments of the present invention, it is possible to perform multiplexing so that a specific data sequence is not packetized and multiplexed over a plurality of packets. Therefore, even when it is necessary to control the multiplexed stream data to change the code content of a part of the data, it is possible to maintain the simplicity of the control and maximize the multiplexing efficiency. Improvement can be achieved.

[0099]

According to the multiplexing apparatus and method of the present invention, a plurality of stream data are temporarily stored, a multiplex channel among a plurality of channels is selected, and the stored stream data is read out and controlled as packet data, and the selection and selection are performed. When multiplexing packet data by read control to generate a multiplexed stream, a specific continuous data string is multiplexed in the same packet among a plurality of stream data, so that a specific continuous data string is generated. , It is possible to perform multiplexing so as not to packetize and multiplex multiple packets. Therefore, according to the present invention, it is possible to keep the simplicity of the control method for operating the multiplexed data while reducing the delay generated in the multiplexing buffer and improving the multiplexing efficiency. In other words, even when control is required to change the code content of a part of the multiplexed stream data, simplicity of the control can be maintained and multiplexing efficiency can be maximized. It is possible to improve.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a digital satellite broadcasting system in which a multiplexing device according to an embodiment is provided on a transmitting device side as an example of a system to which the multiplexing device and method of the present invention are applied; .

FIG. 2 is a diagram showing a P on a transmitting device side of a digital satellite broadcasting system.
It is a block circuit diagram showing a specific example of an ES stream generation unit.

FIG. 3 is a block circuit diagram illustrating a schematic configuration of a multiplexer according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating a channel selection algorithm when multiplexing a PES stream in a channel selection control unit of the multiplexer according to the first embodiment;

FIG. 5 is a block circuit diagram illustrating a schematic configuration of a multiplexing device according to a second embodiment of the present invention.

FIG. 6 is a block circuit diagram illustrating a specific configuration example of a start code counting unit in a buffer of the multiplexer according to the second embodiment.

FIG. 7 is a block circuit diagram illustrating a schematic configuration of a multiplexing device according to a third embodiment of the present invention.

FIG. 8 is a diagram used for describing a division multiplexing inhibition flag.

FIG. 9 is a flowchart illustrating a channel selection algorithm when control is performed using a division multiplexing inhibition flag in a channel selection control unit of the multiplexer according to the third embodiment.

FIG. 10 is a block circuit diagram showing a schematic configuration of a conventional multiplexer.

FIG. 11 is a diagram used to describe the configuration of a PES stream.

[Explanation of symbols]

11 multiplexer, 32 multiplex buffer, 33 input control unit, 35 control data generation unit, 36 null packet generation unit, 39 TP header generation unit, 43 channel selection control unit, 44 switch, 46 multiplex data operation unit, 49 system control Department

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // H04N 7/24 F term (reference) 5C059 MA00 RB02 RB16 RC07 SS02 TA71 TC20 TD12 UA34 5C063 AB03 AB07 CA34 DA07 DA13 5K028 EE03 EE08 KK32 NN00 SS24 5K030 GA02 HA08 HB01 HB02 JA01 JA05 KA03 KX12 LA15 MB15

Claims (28)

[Claims] 1. A multiplexing device for dividing and multiplexing a plurality of stream data for each predetermined packet, a plurality of storage means for temporarily storing the plurality of stream data, and multiplexing among a plurality of channels. Control means for controlling selection of a multiplex channel to be read and reading from the storage means; and multiplex stream generation means for multiplexing packet data obtained by the selection of the multiplex channel and read control of the storage means to generate a multiplex stream. A multiplexing apparatus, wherein a specific continuous data string among the plurality of stream data is multiplexed in the same packet. 2. The control unit selects a channel corresponding to a storage unit having the largest data occupancy among the plurality of storage units as a candidate for the multiplex channel, and assigns a channel selected as the candidate to the multiplex channel. If the data occupation amount of the corresponding storage means is equal to or more than a predetermined threshold, multiplexing is determined. The multiplexing device according to claim 1, wherein 3. The multiplexing apparatus according to claim 2, wherein said threshold value is equal to or more than one byte and less than one byte of one packet. 4. The threshold value is set to 1 from the number of bytes from the first byte of the stream data to the last byte of a predetermined unit.
3. The multiplexing device according to claim 2, wherein the number of bytes is equal to the number of bytes. 5. The multiplexing apparatus according to claim 2, wherein a null packet is transmitted when the number of channels to be a candidate for the multiplex channel becomes zero. 6. A start code input detecting means for outputting, as a start code input detection signal, a detection of a start code of data that needs to be multiplexed at the beginning of the packet, and a start code input detection signal and the multiplexed stream. A start code detecting means for outputting a start code detection signal in the storage means for indicating whether the start code is present in the storage means of the corresponding channel. 2. The multiplexing apparatus according to claim 1, wherein said multiplex channel selection is controlled based on an in-means start code detection signal. 7. The control unit selects a channel corresponding to the storage unit having the largest data occupation amount among the plurality of storage units as a multiplex channel candidate, and corresponds to the channel selected as the candidate. If the data occupancy of the storage means to be performed is equal to or greater than a predetermined threshold, multiplexing is determined. The multiplexing device according to claim 6, wherein 8. The apparatus according to claim 7, wherein said threshold value is changed based on said start code detection signal in said storage means.
The multiplexing device of any of the preceding claims. 9. The multiplexing method according to claim 8, wherein the first threshold value is larger than the second threshold value, and the first threshold value is equal to or more than one byte and less than one byte of one packet. apparatus. 10. The first threshold value is the number of bytes obtained by adding 1 to the number of bytes from the first byte of the stream data to the last byte of a predetermined unit, and the second threshold value is 1
10. The multiplexing device according to claim 9, wherein the number is a byte number. 11. The multiplexing apparatus according to claim 7, wherein a null packet is transmitted when the number of channels targeted for the multiplex channel becomes zero. 12. Detecting the position of the specific continuous data string in the stream data, and outputting flag data synchronized with the stream data designating the byte position of the specific continuous data string to the storage means. Flag data generating means, and flag data storing means for storing the flag data in a state where the flag data is associated with each byte of the stream data, wherein the control means performs the multiplex channel selection based on the flag data. 2. The multiplexing apparatus according to claim 1, wherein the multiplexing is controlled. 13. The control means selects a channel corresponding to the storage means having the largest data occupancy among the plurality of storage means as a multiplex channel candidate, and selects a channel corresponding to the channel selected as the candidate. When multiplexing from the packet data in the storage means, the flag data at the bit position corresponding to the stream data byte to be read last is evaluated. If the flag is not set, multiplexing is determined. 13. The multiplexing apparatus according to claim 12, further comprising: a multiplexing control unit that repeats a procedure of excluding the from a candidate for a multiplex channel. 14. The multiplexing apparatus according to claim 13, wherein a null packet is transmitted when the number of channels to be a candidate for the multiplex channel becomes zero. 15. A multiplexing method for dividing and multiplexing a plurality of stream data for each predetermined packet, wherein: a storage step of temporarily storing each of the plurality of stream data; A control step of reading and controlling channel data selected and stored as packet data, and a multiplex stream generating step of multiplexing packet data obtained by the multiplex channel selection and read control to generate a multiplex stream. A multiplexing method, wherein a specific continuous data string of the plurality of stream data is multiplexed in the same packet. 16. In the control step, a channel in which the most stream data is stored is selected as the multiplex channel candidate, and if the storage amount of the stream data in the channel selected as the candidate is equal to or more than a predetermined threshold, the multiplexing is performed. 16. The multiplexing method according to claim 15, further comprising: a multiplexing control step of repeating a procedure for determining a channel and excluding the channel from multiplex channel candidates if the value is less than the threshold value. 17. The system according to claim 16, wherein the threshold value is equal to or more than 1 byte and less than the number of bytes for one packet.
The multiplexing method as described. 18. The method according to claim 16, wherein the threshold value is a number of bytes obtained by adding 1 to the number of bytes from the first byte of the stream data to the last byte of a predetermined unit.
The multiplexing method as described. 19. The multiplexing method according to claim 16, wherein a null packet is transmitted when the number of candidate channels for the multiplex channel becomes zero. 20. A start code input detecting step of outputting, as a start code input detection signal, the detection of a start code of data that needs to be multiplexed at the beginning of the packet; A storage start code detection step of outputting a storage start code detection signal indicating whether or not the start code is stored as part of the stream data of the corresponding channel. The multiplexing method according to claim 15, wherein the multiplex channel selection is controlled based on a code detection signal. 21. In the control step, a channel storing the most stream data is selected as a multiplex channel candidate. If the storage amount of the stream data of the channel selected as the candidate is equal to or larger than a predetermined threshold, multiplexing is performed. 21. The multiplexing method according to claim 20, further comprising a multiplexing control step of repeating a procedure of determining and excluding the channel from candidates for a multiplex channel if the value is less than the threshold. 22. The multiplexing method according to claim 21, wherein said threshold value is changed based on said storage start code detection signal. 23. The method of claim 23, wherein the first threshold is greater than the second threshold,
23. The multiplexing method according to claim 22, wherein the first threshold is equal to or greater than one byte and less than one packet. 24. The first threshold value is the number of bytes obtained by adding 1 to the number of bytes from the first byte of the stream data to the last byte of the predetermined unit, and the second threshold value is one byte number. The multiplexing method according to claim 23, wherein: 25. The multiplexing method according to claim 21, wherein a null packet is transmitted when the number of channels targeted for the multiplex channel becomes zero. 26. A flag data generating step of detecting a position of said specific continuous data string in said stream data and outputting flag data synchronized with stream data designating a byte position of said specific continuous data string. And a flag data storing step of storing the flag data in a state where the flag data is associated with each byte of the stream data. In the control step, the multi-channel selection is controlled based on the flag data. 16. The multiplexing method according to claim 15, wherein: 27. In the control step, when a channel storing the most stream data among the plurality of channels is selected as a multiplex channel candidate, and multiplexing is performed from packet data corresponding to the selected channel. A procedure of evaluating the flag data at the bit position corresponding to the stream data byte to be read last, determining multiplexing if the flag is not set, and excluding the channel from multiplex channel candidate targets if the flag is set 27. The multiplexing method according to claim 26, further comprising a multiplexing control step of repeating the above. 28. The multiplexing method according to claim 27, wherein a null packet is transmitted when the number of channels targeted for the multiplex channel becomes zero.