JP2002051335A - Data transmission method and data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit so as to reliably reproduce it at a reception side by a transmission system, which multiplexes a plurality of compressed digital image signals and transmits 8-bit word string data to which word synchronization data are added as serial data. SOLUTION: Based on a plurality of compressed digital image signals, in which a part in which compressed data is present and a part in which it is absent are alternately connected, so that each forms 8-bit word string data, a part in which the multiplexed compressed data is present and a part in which it is absent are alternately connected, and an additional word data group containing word synchronization data to which the predetermined code is allocated is inserted into the part in which the multiplexed compressed data is absent to form composite word string data. The composite word string data is converted into serial data output for transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The invention described in the claims of the present application forms 8-bit word string data obtained by subjecting a digital video signal to data compression in units of a predetermined section period. A plurality of compressed digital video signals, an additional word data group including word synchronization data to which a predetermined code is assigned is inserted between portions where multiplexed compressed data exists. The present invention relates to a data transmission method for obtaining word string data and transmitting the compound word string data for transmission, and a data transmission apparatus provided for implementing the method.

[0002]

2. Description of the Related Art In the field of transmission of digital data including information data representing various kinds of signal information such as image information, an electric signal based on digital data is obtained, and is used by a coaxial cable or twisted pair line or the like. A system for transmitting digital data through a transmission line formed by using an optical fiber, and a system for transmitting digital data to an optical signal and transmitting the same through a transmission line formed using an optical fiber have been put into practical use. The transmission format of digital data is an STM (Synchronous Transfer Mode) format in which a fixed frame period is set, and an ATM (Asynchronous Transport Mode) in which a fixed frame period is not set.
nsfer Mode) format.

[0003] The current digital network formed by adopting such a digital data transmission system has been developed based on a telephone line network. With the development of digital network transmission, multiplexing of data and high-speed broadening of signals based on data to be transmitted are inevitably pursued in order to realize efficient data transmission. As one of the techniques for multiplexing digital data and transmitting it as a high-speed wideband signal, SDH (Synchronous
A technology called Digital Hierarchy) has been established in ITU-T (formerly CCIR).

[0004] The SDH proposes a new STM format that is compatible with future high-speed broadband services.
A synchronous multiplexing structure having a basic unit called TM-1 is adopted. STM-1 is 270, as shown in FIG.
A transmission signal having a cycle of 9 rows, that is, 270 bytes x 9 = 2,430 bytes, based on the assumption that the data division of bytes (Byte; 1 byte = 8 bits (Bit)) constitutes each row. , Such a unit period division is called a “frame”. 2 in each of the nine rows forming each frame
The first 9 bytes of the 70 bytes form the section overhead (SOH) and the AU pointer, and the remaining 261 bytes of the 270 bytes form the information area.

[0005] The SOH and AU pointers consist of a total of 9 bytes x 9 = 81 bytes, which include A1, A2, B
1, B2, C1, D1 to D12, E1, E2, F1, K
1, K2, H1, H2, H3, Z1, and Z2 are included. These have the contents as shown in FIG. 19, respectively, of which A1 and A2
(Frame pattern) is 8-bit word synchronization data, and is a continuous 3-byte A1 at the beginning of the first row.
And the subsequent three bytes of A2 form a synchronization pattern in each frame. Each of the 8-bit word synchronization data A1 and A2 is assumed to have been assigned a predetermined code.
1 is assigned “11110110”, and A
2 is assigned “00101000”.

[0006] One cycle of the STM-1 is set to 125 µsec. Therefore, the transmission capacity is 270 bytes x 9 x 1/1.
25 × 10 ⁻⁶ seconds × 8 = 155.520 megabits / second (155.520 Mbps).

Further, transmission using STM-1 has been further developed, and high-speed transmission in which a plurality of STM-1s are multiplexed has been proposed.
It is called. The STM-N includes, for example, a plurality of STM-1 STM-1 # 1, ST as shown in FIG.
, STM-1 #n are formed by byte interleaving multiplexing in the data multiplexing unit 10.

As a communication service employing SDH as described above, SONET (Synchronous Optimal
A high-speed data transmission service called “cal Network” is known.

On the other hand, in the field of video signals, digitization has been attempted from the viewpoint of realizing diversification of transmitted information and high quality of reproduced images. For example, digital data (image data) representing video signal information has been developed. High-definition television (HDTV) systems that handle digital video signals formed by information data) have been proposed. The digital video signal (HD digital video signal) under the HDTV system follows, for example, a data format as shown in FIG.

The data format of the digital video signal shown in FIG. 21 is a brightness signal data sequence (Y data sequence) representing a brightness signal component in the video signal as shown in FIG. And a color difference signal data sequence (P _B / P _R data sequence) representing a color difference signal component in the video signal, and the Y data sequence and the P _B / P _R data sequence are
It represents luminance signal information data forming a digital video signal and color difference signal information data forming a digital video signal.

Each of the word data forming each of the Y data sequence and the P _B / P _R data sequence has a 10-bit configuration. That is, each of the color difference signal information data represented as luminance signal information data and the P _B / P _R data sequence represented as Y data sequence, quantization with 10-bit word is image information data has been made. FIG. 21A illustrates a line blanking period in each line period in the Y data series and a portion corresponding to a part of the video data period before and after the line blanking period.
In addition, the B in FIG. 21, there is shown a portion corresponding to a portion of the video data period in the line blanking period and before and after in each line period in the P _B / P _R data sequence.

In the Y data series, immediately before a portion corresponding to each video data period, four words (3FF (Y), 000 (Y), 000) each having a 10-bit configuration.
(Y), XYZ (Y)), timing reference code data (SAV: Start of Active Video) is provided, and each of them has a 10-bit configuration immediately after a portion corresponding to each video data period. Word (3FF (Y),
000 (Y), 000 (Y), XYZ (Y)), and timing reference code data (EAV: End of Active).
Video) is arranged. Similarly, P _B / P _R data be in sequence, just before the portion corresponding to the respective video data period, four words, each of which is a 10-bit configuration (3FF
(C), 000 (C), 000 (C), XYZ (C))
And a 4 word (3FF (C), 000 (C), 000) immediately after a portion corresponding to each video data period, each of which has a 10-bit configuration.
(C), XYZ (C)). Of course, Y data EAV and SAV Each of the in series arranged in a portion corresponding to the line blanking period in the Y data sequence and, EAV in P _B / P _R data sequence
And each of the SAV is arranged at a portion corresponding to each line blanking period in P _B / P _R data sequence.

[0013] In the digital video signal according to the data format consisting of such Y data sequence and P _B / P _R data sequence is transmitted, Y data sequence and P _B /
The P _R data sequence, the word multiplexing process at Moto the portion corresponding to the line blanking period, each of EAV and SAV are disposed has been made to the synchronization is performed, the word multiple data series as shown in FIG. 22 Is formed.

[0014] Such HD digital video signals include:
Interlaced scanning in which each frame image is formed by being divided into a first field image and a second field image, and sequential scanning in which each frame image is formed without being divided into a first field image and a second field image There is a business. The HD digital video signal for interlaced scanning is 10-bit word string data with a transmission rate of, for example, 148.5 MBps, and the HD digital video signal for progressive scanning has a transmission rate of H for interlaced scanning.
D digital video signal, for example, 148.
It is 10-bit word string data with 5 MBps × 2 = 297 MBps.

[0015] Further, the amount of image information data which forms an HD digital video signal for interlaced scanning or an HD digital video signal for progressive scanning usually has an enormous amount of data. In performing such operations, it is desired that data compression be performed so that the data amount can be reduced without substantially lowering the data quality. Therefore, various researches and developments have been made on data compression techniques for reducing the data amount of image information data. One of the results is, in particular, image information data representing moving image information. As a method of implementing data compression, MPEG (Moving), a working group under the technical committee under the International Standards Organization,
A standard scheme called MPEG has been proposed, which has been examined and approved as a standard by the Picture Experts Group.

In the standard method called MPEG, image information data is subjected to data compression by high-efficiency coding.
When data compression by high-efficiency encoding according to EG is performed, data compression with an extremely high compression rate can be realized.
In addition, there is obtained an advantage that an image reproduced based on digital image information data subjected to data compression can be of high quality. Digital image information data (MPEG image information data) that has been subjected to data compression by high-efficiency encoding according to MPEG generally forms 8-bit word string data.

When data compression processing using MPEG is performed on the above-described interlaced scanning HD digital video signal or progressive scanning HD digital video signal, for example, interlaced scanning HD digital video signal or sequential For HD digital video signals for scanning,
Data compression is performed in units of one frame period, which is the section period in that case. That is, data compression by high-efficiency coding according to MPEG is performed on image information data representing each frame period in the HD digital video signal for interlaced scanning or the HD digital video signal for progressive scanning. Compressed data as 8-bit word string data is sequentially formed.

As a result, based on the HD digital video signal for interlaced scanning, a compressed digital video signal (compressed digital video signal) in which a portion where compressed data is present and a portion where no compressed data is present are alternately connected to form 8-bit word string data. DCI) or a compressed digital video signal (compressed digital video signal DCP) based on an HD digital video signal for progressive scanning, in which a portion where compressed data exists and a portion where no compressed data exists alternately continue to form 8-bit word string data. ) Is formed. In such a compressed digital video signal DCI or DCP, one frame period corresponds to a portion where compressed data formed by data compression by high-efficiency coding according to MPEG exists and a portion where no subsequent compressed data exists. And will be formed by

FIG. 23 shows a compressed digital video signal DCI.
Alternatively, an example of DCP is shown. FIG. 23A shows a series of each frame period (one frame) in the compressed digital video signal DCI or DCP, and in each frame period, a portion where compressed data exists and a portion where compressed data does not exist (blank). Are connected.

FIG. 23B shows a sequence layer for forming compressed data. The sequence layer indicates that the sequence header code (SHC: 000001B3 (H), (H) is expressed in hexadecimal), and the same applies to the following. .), Followed by a plurality of group of pictures (GOP), and ends with a sequence end code (SEC: 000001B7 (H)). FIG.
C indicates a GOP constituting the sequence layer, and GOP
Is the group start code (GSC: 00000
1B8 (H)), and a plurality of pieces of picture data are formed continuously. FIG. 23D shows picture data constituting a GOP, and the picture data is a picture start code (PSC: 00000100).
(H)), and a plurality of slice data are connected to it.

Further, FIG. 23E shows slice data constituting picture data. The slice data starts with slice information, and is composed of a plurality of macroblock data connected thereto. F in FIG. 23 shows macroblock data constituting slice data. The macroblock data starts with macroblock information, and is configured by a plurality of block data connected thereto. G in FIG.
Indicates block data constituting macroblock data, and the block data is a discrete cosine transform (DCT).
Is obtained as DCT data.

A compressed digital video signal (MPE) formed by performing data compression processing using MPEG, such as the above-mentioned compressed digital video signal DCI or DCP.
For the transmission of the G compressed digital video signal), a predetermined code assignment such as the above-mentioned 8-bit word synchronization data A1 and A2 is made on the transmitting side based on the compressed digital video signal to be transmitted. Word string data to which the word synchronization data has been added is formed, and the word string data is transmitted so as to be transmitted as serial data, so that the data can be reliably reproduced on the receiving side. That
For example, in configuring a transmission / reception circuit, for example, an existing integrated circuit element (I
This is desired from the viewpoint that C element and the like can be used effectively.

[0023]

As described above, on the transmitting side, word string data to which word synchronization data to which a predetermined code is assigned is added based on a compressed digital video signal to be transmitted. In a situation where transmission of an MPEG compressed digital video signal is desired in a transmission system in which the word string data is formed and transmitted so as to be transmitted as serial data, a single MP
Not only EG compressed digital video signal but also multiple MPE
If the G-compressed digital video signal can be multiplexed and transmitted, the MPEG-compressed digital video signal can be used efficiently, and the range of use of the MPEG-compressed digital video signal can be expanded. And M
Efficient use of PEG-compressed digital video signals or expansion of the use range of MPEG-compressed digital video signals, for example, will result in further development of technology in the field of business or household electronic devices.

However, conventionally, a predetermined code, such as 8-bit word synchronization data A1 and A2, has been assigned on the transmitting side based on the compressed digital video signal to be transmitted. A plurality of MPEG-compressed digital video signals are multiplexed by a transmission method in which word string data to which word synchronization data is added and the word string data is transmitted so as to be transmitted as serial data is reliably transmitted to the receiving side. There is no concrete example that realizes a transmission system capable of transmitting to be reproduced. Further, there is no document or the like describing a technique relating to a transmission system capable of multiplexing a plurality of such MPEG compressed digital video signals and transmitting the multiplexed digital video signals so as to be surely reproduced on a receiving side.

In view of the above, according to the invention described in the claims of the present application, based on a compressed digital video signal to be transmitted, word synchronization data to which a predetermined code is assigned is added. A plurality of, for example, MPEG-compressed digital video signals are multiplexed by a transmission method in which word string data is formed and the word string data is transmitted to be transmitted as serial data, so that the data can be reliably reproduced on the receiving side. Provided is a data transmission method capable of transmission and a data transmission device provided for the implementation.

[0026]

The data transmission method according to any one of claims 1 to 7 in the claims of the present application provides a data transmission method in which each of the digital video signals has a predetermined division period. Multiplexing is performed on the basis of a plurality of compressed digital video signals, which are obtained by performing data compression in units of minutes and in which a portion where compressed data is present and a portion where no compressed data are present are alternately connected to form 8-bit word string data. An additional word data group including word synchronization data to which a predetermined code is assigned is inserted into a portion where the multiplexed compressed data does not exist and a portion where the compressed data exists and the portion where the multiplexed compressed data does not exist alternately. Forming the compound word string data, converting the compound word string data into serial data, and transmitting the serial data for transmission. It is things.

In particular, in the data transmission method according to the invention described in claim 2 of the present application, synchronous data is inserted into a plurality of compressed digital video signals in portions where no compressed data exists in each of the plurality of compressed digital video signals. After performing the multiplexing process, the compressed data in each of the plurality of compressed digital video signals is formed into multiplexed compressed data, and the compressed data in each of the plurality of compressed digital video signals is formed in a portion where the compressed data does not exist. The inserted synchronizing data forms an additional word data group including word synchronizing data to which a predetermined code is assigned, thereby obtaining composite word string data.

Further, in the data transmission apparatus according to the invention described in claim 8 or claim 9 of the present application, each of the data transmission apparatuses performs data compression on a digital video signal in units of a predetermined section period. There is multiplexed compressed data based on a plurality of compressed digital video signals, which are obtained by applying the compressed data existing portion and the non-existent portion alternately to form 8-bit word string data. A compound word sequence in which a portion and a non-existent portion are alternately connected, and an additional word data group including word synchronization data to which a predetermined code is assigned is inserted in a portion where multiplexed compressed data does not exist. A compound word string data forming means for forming data, and compound word string data obtained from the compound word string data forming means It converted to, and includes a data sending means for sending in order to transmit the serial data.

[0029] In particular, in the data transmission apparatus according to the ninth aspect of the present invention, the composite word string data forming means may be configured to convert each compressed data in each of the plurality of compressed digital video signals into parallel / compressed data. A serial / parallel conversion means for performing serial conversion to obtain a plurality of serial data in which a portion where serial compressed data is present and a portion where no serial compressed data is present are alternately connected; Synchronous data insertion means for forming a plurality of composite serial data by inserting synchronous data into a portion where serial compressed data does not exist in each of the plurality of serial data to be obtained, and a plurality of compressed digital videos obtained from the synchronous data inserting means. Multiple compound serial data based on each signal are multiplexed to form a compound word string data. And a data multiplexing means for obtaining is assumed to be constructed.

According to the data transmission method according to any one of the first to seventh aspects of the present invention as described above, for example, a plurality of data to be transmitted are transmitted. The composite word string data based on a plurality of compressed digital video signals, which is an MPEG compressed digital video signal, contains word synchronization data to which a predetermined code is assigned.
Such word synchronization data is, for example, 8-bit word synchronization data A1 and A2 used in SDH.
Are consecutively connected, and subsequently, three 8-bit word synchronization data A2 are consecutively connected.

The compound word string data including the word synchronization data to which the predetermined code is assigned and transmitted as the serial data is converted into the word synchronization data by the receiving side. That is to be properly detected as word synchronization data required for processing for converting data into parallel data and processing for reproducing a plurality of compressed digital video signals from composite word string data. Is done. Therefore, on the receiving side, a state in which the data synchronization state required for the reproduction processing of the plurality of compressed digital video signals based on the received composite word string data is reliably obtained.

That is, according to the data transmission method according to any one of the first to seventh aspects of the present invention, the predetermined method is based on the compressed digital video signal to be transmitted. A word string data to which word synchronizing data to which the assigned code is assigned is formed, and each of the word string data is transmitted to be transmitted as serial data, for example, by an MPEG compressed digital video. A plurality of compressed digital video signals can be multiplexed and transmitted to be reliably reproduced on the receiving side.

In particular, according to the data transmission method according to the invention described in claim 2 of the present application,
Each of the plurality of compressed digital video signals, which is, for example, an MPEG compressed digital video signal, is subjected to a process of multiplexing after inserting synchronization data into a portion of each of the compressed digital video signals where no compressed data exists, thereby performing a plurality of compression processes. It is assumed that the compressed data in each of the digital video signals forms multiplexed compressed data, and that the synchronization data inserted in the portion where the compressed data does not exist in each of the plurality of compressed digital video signals is predetermined. Forming a group of additional word data including the word synchronization data to which the code has been assigned, obtaining composite word sequence data, and transmitting the composite word sequence data for transmission as serial data. Is done.

According to the data transmission apparatus of the present invention described in claim 8 or claim 9 of the present application, the compression to be transmitted by the compound word string data forming means and the data sending means is performed. Based on the digital video signal, word string data to which word synchronizing data to which a predetermined code is assigned is added, and the word string data is transmitted to be transmitted as serial data. However, for example, a plurality of compressed digital video signals, which are MPEG compressed digital video signals, can be multiplexed and transmitted to be reliably reproduced on the receiving side.

The data transmitting means for transmitting the composite word string data based on a plurality of compressed digital video signals as serial data is constructed by effectively utilizing an existing IC element for SDH, for example. Can be done.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a data transmission method according to the present invention, which is an example of the data transmission method according to the present invention. An example of the data transmission device according to the invention described in claim 8 or claim 9 in the range of FIG.

In the example shown in FIG. 1, 8 channels of compressed digital video signals DCI0, DCI1, DC
I2, DCI3, DCI4, DCI5, DCI6 and D
The CI 7 is supplied to the composite word string data forming unit 10 as a compressed digital video signal to be transmitted.

Compressed digital video signals DCI0 to DCI
7 is subjected to data compression in units of a predetermined segment period for the interlaced scanning HD digital video signal, and thus, for example, one frame corresponding to the segment period in the interlaced scanning HD digital video signal is processed. A portion where compressed data exists and a portion where compressed data does not exist based on an HD digital video signal for interlaced scanning, obtained by performing data compression by high-efficiency coding according to MPEG on image information data representing a period. (Blanks) alternately form 8-bit word string data.
For example, it is a compressed digital video signal having a data structure as shown in FIG. In each of these compressed digital video signals DCI0 to DCI7, each of a set of a portion where compressed data exists and a portion where no compressed data exists exists,
One frame period is formed. Each of the compressed digital video signals DCI0 to DCI7 is 8-bit word string data having a word transmission rate of, for example, 74.25 MBps. Therefore, the word clock frequency of each of the compressed digital video signals DCI0 to DCI7 is For example, it is 74.25 MHz.

The composite word string data forming section 10 has compressed digital video signals DCI0 to DCI supplied thereto.
7, the horizontal synchronizing signals SH0 to SH7 and the vertical synchronizing signals SV0 to SV7 synchronized with the line period and the field period, respectively, and the compressed digital video signal DC.
The frequency for each of I0 to DCI7 is 74.25M
Hz, and a clock signal CA having a frequency of 311 MHz is also supplied.

In the composite word string data forming section 10, the parallel / serial (P / S) converting section 11 supplies the compressed digital video signal DCI0 and the word clock signal CL.
0, a horizontal synchronization signal SH0, a vertical synchronization signal SV0, and a clock signal CA. Similarly, the P / S converter 12
To 18 are compressed digital video signals DCI1 to DCI, respectively.
CI7, word clock signals CL1 to CL7, horizontal synchronization signals SH1 to SH7, and vertical synchronization signals SV1 to SV.
7, and the clock signal CA is supplied to all of the P / S converters 12 to 17.

The P / S converter 11 is configured, for example, as shown in FIG. Then, the P / S shown in FIG.
In the conversion unit 11, the compressed digital video signal DCI
0 is supplied to the switch 32. The switch 32
The control signal CSA from the switch control signal forming unit 33 is also supplied.

The switch control signal forming section 33 is supplied with the horizontal synchronizing signal SH0 and the vertical synchronizing signal SV0. , In synchronization with each frame period in the compressed digital video signal DCI0.

A memory section 34 and a memory section 35 are connected to the switch 32. Then, the switch 32 performs switching at the beginning of each frame period in the compressed digital video signal DCI0 in accordance with the control signal CSA synchronized with each frame period in the compressed digital video signal DCI0. Accordingly, the compressed digital video signal DCI0 is alternately supplied to the memory unit 34 and the memory unit 35 for one frame period, and the compressed digital video signal DCI0 is distributed and supplied to the memory unit 34 and the memory unit 35. A state is taken.

In connection with the memory units 34 and 35,
The memory control signal forming unit 36 is provided, and the word clock signal CL0 and the clock signal CA are supplied to the memory control signal forming unit 36. Then, based on the word clock signal CL0, the memory control signal forming unit 36 writes the write control signal QW having a frequency of 74.25 MHz.
, And generates a read control signal QR having a frequency of 311 MHz based on the clock signal CA, and supplies the write control signal QW and the read control signal QR to both the memory units 34 and 35.

Thus, in the memory section 34, during the period in which the compressed digital video signal DCI0 is supplied through the switch 32, the compressed digital video signal DCI0 is supplied.
The frequency for one frame period of I0 is 74.25 MHz.
Is written in a state where the word transmission rate is 74.25 MBps according to the write control signal QW. Also,
Even in the memory unit 35, during the period in which the compressed digital video signal DCI0 is supplied through the switch 32,
One frame period of the compressed digital video signal DCI0 corresponds to a write control signal QW having a frequency of 74.25 MHz.
Is written in a state where the word transmission rate is set to 74.25 MBps.

Therefore, writing at a word transmission rate of 74.25 MBps for one frame period of the compressed digital video signal DCI0 in the memory units 34 and 35 is performed at the beginning of each frame period of the compressed digital video signal DCI0. Switch 32 performed every time
Are performed alternately in accordance with the switching of.

One frame period of the compressed digital video signal DCI0 written in the memory unit 34 has a frequency of 311 MH during a period corresponding to one frame period of the compressed digital video signal DCI0 following the writing period.
In accordance with the read control signal QR as z, the data is read bit by bit from the memory unit 34 to form serial data DX0 '. In such a case, the end portion of the portion of the compressed digital video signal DCI0 written in the memory unit 34 where no compressed data exists during one frame period is not read out. Since there is no data, there is no particular problem.

As a result, the serial data DX0 'with a bit transmission rate of 311 Mbps is output from the memory unit 34.
And it is supplied to the switch 37.

Similarly, one frame period of the compressed digital video signal DCI0 written in the memory unit 35 is also stored in the compressed digital video signal DCI following the writing period.
In a period corresponding to one frame period of I0, one bit is read from the memory unit 35 one bit at a time in accordance with the read control signal QR having a frequency of 311 MHz to form serial data DX0 '. . At this time, the compressed digital video signal DCI written in the memory unit 35
Although a part of the end portion side of the portion where no compressed data exists during one frame period of 0 is not read out, since the portion not read out is a portion where no compressed data exists,
No other problems will occur.

As a result, the serial data DX0 'with a bit transmission rate of 311 Mbps is output from the memory unit 35.
And it is supplied to the switch 37.

The switch 37 is also supplied with a control signal CSA synchronized with each frame period of the compressed digital video signal DCI0 from the switch control signal forming unit 33. The switch 37 receives the serial data DX0 ′ obtained from the memory unit 34 in response to the control signal CSA.
And serial data DX0 'obtained from the memory unit 35
Alternately, thereby reducing the bit transmission rate to 31
The serial data DX0 of 1 Mbps is formed.

As described above, the P / S conversion section 11 performs the P / S conversion processing on the compressed digital video signal DCI0, and sets the bit transmission rate based on the compressed digital video signal DCI0 to 311 Mbps. DX0 is derived. The serial data DX0 is formed by converting compressed data formed by data compression by high-efficiency encoding according to MPEG as shown in FIG. 23 in the compressed digital video signal DCI0 into serial data. Become.

Each of the P / S converters 12 to 18 also
For example, the P / S converter 11 is configured in the same manner as the P / S converter 11 shown in FIG. 2, and the P / S converters 12 to 18 supply the compressed digital video signals DCI1 to DCI7, respectively, as described above. An operation similar to that performed when the P / S conversion processing is performed on the compressed digital video signal DCI0 in the / S conversion unit 11 to form the serial data DX0 is performed. Thereby, the P / S converter 1
2-18, the compressed digital video signal DCI1
To DCI7 to perform a P / S conversion process on the basis of the compressed digital video signals DCI1 to DCI7, each having a bit transmission rate of 311 Mbps.
1 to DX7 are derived respectively. These serial data D
X1 to DX7 are also compressed digital video signals DCI
As shown in FIG. 23, compressed data formed by data compression by high-efficiency encoding according to MPEG in each of 1 to DCI7 is converted into serial data and formed.

In this manner, the P / S converters 11 to 18
Are supplied to the synchronization data insertion units 20 to 27, respectively. The control signal CSB from the control signal forming unit 28 is also supplied to each of the synchronous data inserting units 20 to 27.

The synchronous data insertion unit 20 is configured, for example, as shown in FIG. In the synchronous data insertion unit 20 shown in FIG. 3, the serial data DX0 obtained from the P / S
It is supplied to the EC detection unit 42. The SEC detection unit 42 generates a sequence end code (SEC: 0000) as shown in FIG. 23B included in the serial data DX0.
01B7 (H)) detects the portion converted to serial data, and when the portion converted from SEC to serial data is detected, sends out the SEC detection output signal SE0 accordingly.

Further, the synchronous data insertion unit 20 is provided with a word data transmission unit 43, and a control signal CSB is supplied to each of the word data transmission unit 43 and the switch 41. The word data sending unit 43 outputs the control signal CSB
The bit transmission rate is set to 31
Synchronous data DW which is serial data at 1 Mbps
Sends S0 and supplies it to the switch 41. The switch 41 is controlled by the control signal CSB.
Is selectively extracted from the serial data DX0 from the P / S converter 11 and the synchronization data DWS0 from the word data transmitter 43, and the synchronization data DWS0 is partially inserted into the serial data DX0. The composite serial data DZ0 having a bit transmission rate of 311 Mbps is formed.

Each of the synchronization data insertion units 21 to 27 is also configured, for example, in the same manner as the synchronization data insertion unit 20 shown in FIG. 3, and in each of the synchronization data insertion units 21 to 27, the serial data DX1 to DX7 Are supplied, the control signal CSB is supplied from the control signal forming unit 28, and the synchronization data DWS1 to DWS7 are transmitted from the word data transmitting units provided in each of them.
As described above, the synchronous data insertion unit 20 sends the SEC detection output signal SE0 and performs the same operation as that performed when the composite serial data DZ0 is formed. As a result, the synchronous data insertion units 21 to 27 detect the portions where the SEC included in each of the serial data DX1 to DX7 is converted into the serial data, and transmit the SEC detection output signals SE1 to SE7, respectively. And synchronizing data DWS1 to DWS7 partially inserted into the serial data DX1 to DX7, respectively, to form composite serial data DZ1 to DZ7 each having a bit transmission rate of 311 Mbps.

The composite serial data DZ0 to DZ7 formed in the synchronous data insertion units 20 to 27 are supplied to the data multiplexing unit 29. Further, the SEC detection output signals SE transmitted from the synchronous data insertion units 20 to 27, respectively.
0 to SE7 are supplied to the control signal forming unit 28.

The SEC detection output signals SE0 to SE7 are obtained by detecting the SEC included in each of the serial data DX0 to DX7.
It is obtained in response to the end portion of the compressed data in each frame period portion in each of X0 to DX7. Then, the control signal forming unit 28 transmits the synchronization data
27, the SEC detection output signals SE0 to S respectively supplied from
Among the serial data DX0 to DX7 among the serial data DX0 to E7, the one obtained the latest (latest SEC detection output signal) in each frame period is detected, and the control signal C
The SB is formed as a signal corresponding to the detected latest SEC detection output signal, and is supplied to each of the synchronous data insertion units 20 to 27.

Under the circumstances, in the synchronous data insertion unit 20 shown in FIG. 3, the switch 41 converts the serial data DX0 from the P / S conversion unit 11 and the synchronous data DWS0 from the word data transmission unit 43. In selectively extracting the synchronization data DWS from the word data transmission unit 43 in response to the control signal CSB from the control signal formation unit 28
0, and the serial data DX0 from the P / S converter 11 at other times. Therefore, switch 4
According to 1, for each frame period portion of the serial data DX0, first, the compressed data included therein is extracted, and then, when the compressed data no longer exists, the synchronous data DWS0 is extracted immediately or at an interval. . As a result, the composite serial data DZ0 formed in the synchronous data insertion unit 20 including the switch 41 becomes the synchronous data DWS0 in the portion where the compressed data does not exist following the portion where the compressed data exists in each frame period portion of the serial data DX0. Is inserted.

In each of the synchronization data insertion units 21 to 27, the control signal CSB from the control signal forming unit 28 is also provided.
In response to this, the same operation as the operation in the synchronization data insertion unit 20 is performed, and the composite serial data DZ1 to DZ7 formed in the synchronization data insertion units 21 to 27 respectively become the serial data DX1 to DX7. Synchronization data DWS1 to DWS are added to a portion where compressed data does not exist following a portion where compressed data exists in a frame period portion.
7 are obtained as inserted.

Thus, the synchronous data insertion units 20 to 2
7, synchronous data DWS0 to DWS used respectively.
Numeral 7 denotes serial data each having a bit transmission rate of 311 Mbps. When they are bit-multiplexed under synchronization with each other to form 8-bit word string data, FIG. It is assumed that an additional word data group DWS including 8-bit word synchronization data A1 and A2 as shown in (elapsed time, hereinafter the same) is obtained.

The additional word data group DWS shown in FIG. 4 is composed of a plurality of 8-bit word data, and includes three 8-bit word synchronization data A1 (predetermined code: 1111011) at the start end thereof.
0 is allocated), followed by three 8-bit word synchronization data A2 (predetermined code: 00101000 is allocated), and a terminal portion thereof. In this case, three 8-bit word synchronization data A1 are continuous, and then three 8-bit word synchronization data A2 are continuous, that is, A1 A1 A1 A2 A2 A2.
... A1 A1 A1 A2 A2 A2 Then, in order to obtain such an additional word data group DWS, the synchronization data DWS0 to DWS7 are
As shown in FIG. 4, the synchronization data DWS0, DWS1,
Each of DWS3, DWS5 and DWS6 is "11100
... 111000 "and the synchronization data DWS
2 is “111111... 111111”,
When the synchronization data DWS4 is "000111 ... 000"
111 ”and the synchronization data DWS7 is“ 000000 ”.
·········· Selected to be 000000 ”.

As a result, a composite obtained by inserting the synchronous data DWS0 from the synchronous data inserting unit 20 into a part where the compressed data does not exist following the part where the compressed data exists in each frame period part of the serial data DX0 is obtained. As shown in FIG. 5, the serial data DZ0 has a portion in which the synchronous data DWS0 is inserted, as shown in FIG. 5, synchronous data DWS0: 111000... 11 sandwiched between bits X0 constituting the serial data DX0.
1000 will be provided. Also, in the composite serial data DZ1 to DZ7 obtained from the synchronization data insertion units 21 to 27, the portions where the synchronization data DWS1 to DWS7 are respectively inserted in the composite serial data DZ1 to DZ7 are the synchronization data sandwiched by the bits X1 constituting the serial data DX1. DWS1: 111000 ... 11100
Synchronous data DWS2: 111111 sandwiched between bits X2 constituting serial data DX2
.... In which 111111 is arranged, and synchronous data D sandwiched between bits X3 forming serial data DX3
WS3: 111000 ·········· 111000, synchronous data DWS4 sandwiched between bits X4 constituting serial data DX4: 000111 ·····
000111, synchronous data DWS5: 1 sandwiched between bits X5 constituting serial data DX5
111000, synchronous data DWS6 sandwiched between bits X6 forming serial data DX6: 111000... 11100
0, and synchronous data DWS7: 000 sandwiched between bits X7 forming serial data DX7.
... 0000000 will be provided.

In the data multiplexing section 29 to which the composite serial data DZ0 to DZ7 formed respectively in the synchronous data insertion sections 20 to 27 are supplied, the synchronization of each frame period portion is synchronized with the composite serial data DZ0 to DZ7. Bit multiplexing processing is performed under the condition that the composite serial data DZ0 to DZ7 have a word transmission rate of 31.
Composite 8-bit word string data DZ at 1 MBps
Converted to (8). At this time, the composite serial data D
As shown in FIG. 6, the portions where the synchronization data DWS0 to DWS7 are inserted in Z0 to DZ7 are bits X0 to X7 respectively constituting the serial data DX0 to DX7.
8-bit word based on 7 (X0 X1 X2 X3 X4X5 X6 X7)
Additional word data group DWS sandwiched between A1 and A1
A1 A2 A2 A2 ... A1 A1 A1 A2 A2 A2 A2
To form

Thus, the composite 8-bit word string data DZ (8) formed in the data multiplexing section 29
As shown in FIG. 7, frame serial portions (one frame) that are successively connected are composed of composite serial data DZ0 to DZ0.
7 includes a portion in which the multiplexed compressed data obtained by multiplexing the compressed data in each of the portions 7 exists, and an additional word data group DWS inserted in a portion in which the subsequent multiplexed compressed data does not exist. That is, in the composite 8-bit word string data DZ (8), a portion where multiplexed compressed data exists and a portion where multiplexed compressed data does not exist are alternately connected, and the 8-bit word synchronization data A1 and The additional word data group DWS including A2 is inserted.

The composite 8-bit word string data DZ (8) formed in the data multiplexing section 29 is sent from the composite word string data forming section 10 and supplied to the P / S converter 30. The P / S conversion unit 30 performs P / S conversion on the composite 8-bit word string data DZ (8) to convert parallel data into serial data, and converts the data into composite 8-bit word string data DZ (8). Based on this, serial data DZS having a bit transmission rate of 311 MBps × 8 = 2.488 Gbps is formed, and the serial data DZS is supplied to the transmission unit 31.

The transmitting section 31 converts the serial data DZS into
For example, in order to transmit through a data transmission line formed using a coaxial cable or an optical fiber, an electric signal suitable for a data transmission line formed using a coaxial cable or an optical fiber is used. The signal is converted into a transmission signal SZ which is an optical signal suitable for the data transmission path to be formed and transmitted. Thereby, transmission of the serial data DZS is performed.

In the data transmission apparatus shown in FIG. 1, the P / S conversion section 30 and the transmission section 31 perform bit transmission of the composite 8-bit word string data DZ (8) having a word transmission rate of 311 MBps. 2.488 Gb rate
Data transmission means for converting the data into ps serial data DZS, forming a transmission signal SZ based on the serial data DZS, and transmitting the transmission signal SZ is formed. Therefore, these P /
The data transmission unit formed by the S conversion unit 30 and the transmission unit 31 can be configured by an existing IC element for SDH, for example. Therefore, according to the data transmission method implemented by the data transmission apparatus shown in FIG. 1, a word to which word synchronization data to which a predetermined code is assigned is added based on a compressed digital video signal to be transmitted. Column data is formed, and 8-channel compressed digital video signals DCI0 to DCI7, each of which is an MPEG compressed digital video signal, are multiplexed by a transmission scheme in which the word row data is transmitted to be transmitted as serial data. At the same time, an additional word data group including the word synchronization data A1 and A2 can be inserted and transmitted. At this time, the data transmission means is replaced with an existing IC such as one for SDH.
It can be configured by effectively utilizing elements and the like.

FIG. 8 shows another example of the data transmission method according to the invention described in any one of claims 1 to 7 in the claims of the present application. 14 shows another example of the data transmission device according to the invention described in claim 8 or claim 9.

In the example shown in FIG. 8, four channels of compressed digital video signals DCP0, DCP1, DCP
P2 and DCP3 are supplied to the composite word string data forming unit 50 as compressed digital video signals to be transmitted.

Compressed digital video signals DCP0 to DCP
3 is subjected to data compression in units of a predetermined section period for the HD digital video signal for progressive scanning, for example, one frame corresponding to the section period in the HD digital video signal for progressive scanning. A portion obtained by subjecting image information data representing a period to data compression by high-efficiency coding in accordance with MPEG, based on an HD digital video signal for progressive scanning, a portion where compressed data exists and a portion where compressed data does not exist (Blanks) alternately form 8-bit word string data. For example, FIG.
3 is a compressed digital video signal having a data structure as shown in FIG. These compressed digital video signals DC
In each of P0 to DCP3, each set of a portion where compressed data exists and a portion where no compressed data exists forms one frame period. Each of the compressed digital video signals DCP0 to DCP3 is 8-bit word string data having a word transmission rate of, for example, 148.5 MBps.
Each word clock frequency of DCP4 is, for example, 1
48.5 MHz.

The composite word string data forming section 50 has compressed digital video signals DCP0 to DCP supplied thereto.
3 and the horizontal synchronizing signals SH0 to SH3 and the vertical synchronizing signals SV0 to SV3 synchronized with the line period and the frame period, respectively, and the compressed digital video signal DCP.
The frequency for each of 0 to DCP3 is 148.5 MH
Word clock signals CL0 to CL3 of z are supplied, and further, a clock signal CA of 622 MHz in frequency is also supplied.

In the composite word string data forming section 50, the P / S conversion section 51 supplies the compressed digital video signal DC
P0, word clock signal CL0, horizontal synchronization signal SH
0, a vertical synchronization signal SV0 and a clock signal CA. Similarly, the P / S converters 52 to 54 respectively provide the compressed digital video signals DCP1 to DCP3, the word clock signals CL1 to CL3, the horizontal synchronization signals SH1 to SH3,
The vertical synchronizing signals SV1 to SV3 are supplied, and the clock signals CA are supplied to all the P / S converters 52 to 54.
Is supplied.

The P / S converter 51 is configured, for example, as shown in FIG. Then, the P / S shown in FIG.
In the converter 51, the compressed digital video signal DCP
0 is supplied to the switch 71. Switch 71
The control signal CSXA from the switch control signal forming unit 72 is also supplied.

The switch control signal forming section 72 is supplied with the horizontal synchronizing signal SH0 and the vertical synchronizing signal SV0. The switch control signal forming section 72 generates the control signal CSXA in accordance with the horizontal synchronizing signal SH0 and the vertical synchronizing signal SV0. , In synchronization with each frame period in the compressed digital video signal DCP0.

The switch 71 is connected to a memory 73 and a memory 74. Then, the switch 71 performs switching at the beginning of each frame period in the compressed digital video signal DCP0 in accordance with the control signal CSXA synchronized with each frame period in the compressed digital video signal DCP0. As a result, the compressed digital video signal DCP0 is stored in the memory unit 73 for one frame period.
And the memory unit 74 are alternately supplied to the memory unit 73 so that the compressed digital video signal DCP0 is distributed and supplied to the memory unit 73 and the memory unit 74.

Further, in relation to the memory units 73 and 74,
A memory control signal forming unit 75 is provided, and the word clock signal CL0 and the clock signal CA are supplied to the memory control signal forming unit 75. Then, based on the word clock signal CL0, the memory control signal forming section 75 writes the write control signal QW having a frequency of 148.5 MHz.
X, and based on the clock signal CA,
A read control signal QRX having a frequency of 622 MHz is generated, and a write control signal QWX and a read control signal QRX are supplied to both the memory units 73 and 74.

As a result, in the memory section 73, during the period in which the compressed digital video signal DCP0 is supplied through the switch 71, the compressed digital video signal DCP0 is supplied.
The frequency for one frame period of P0 is 148.5 MHz.
Is written in a state where the word transmission rate is 148.5 MBps according to the write control signal QWX. Further, even in the memory section 74, during the period in which the compressed digital video signal DCP0 is supplied through the switch 71, one frame period of the compressed digital video signal DCP0 has a write control signal Q having a frequency of 148.5 MHz.
Word transmission rate of 148.5 MBps according to WX
It is written in the state as follows.

Therefore, the writing in the state where the word transmission rate for one frame period of the compressed digital video signal DCP0 in the memory units 73 and 74 is 148.5 MBps is performed at the beginning of each frame period of the compressed digital video signal DCP0. Switch 71 performed every time
Are performed alternately in accordance with the switching of.

One frame period of the compressed digital video signal DCP0 written in the memory unit 73 has a frequency of 622 MHz during a period corresponding to one frame period of the compressed digital video signal DCP0 following the writing period.
z is read out bit by bit from the memory unit 73 in response to the read control signal QRX as z.
0 '. In such a case, the memory unit 73
A part of the end portion of the portion of the compressed digital video signal DCP0 in which no compressed data is present during one frame period of the compressed digital video signal DCP0 is not read out. Therefore, no particular trouble occurs.

Thus, the serial data DXX having the bit transmission rate of 622 Mbps from the memory 73
0 'is obtained, which is supplied to the switch 76.

Similarly, the one-frame period of the compressed digital video signal DCP0 written in the memory 74 is the same as the compressed digital video signal DCP following the writing period.
In a period corresponding to one frame period of P0, according to a read control signal QRX having a frequency of 622 MHz,
The data is read out one bit at a time from the memory unit 74 to form serial data DXX0 ′. In such a case,
The compressed digital video signal D written in the memory 74
Part of the end portion of the portion where the compressed data does not exist during one frame period of CP0 is not read out. However, since the portion where the compressed data does not exist is the portion where the compressed data does not exist, no particular trouble occurs. .

Thus, the serial data DXX having the bit transmission rate of 622 Mbps from the memory unit 74
0 'is obtained, which is supplied to the switch 76.

The switch 76 is also supplied with a control signal CSXA from the switch control signal forming section 72 which is synchronized with each frame period of the compressed digital video signal DCP0. The switch 76 alternately takes out the serial data DXX0 ′ obtained from the memory 73 and the serial data DXX0 ′ obtained from the memory 74 in response to the control signal CSXA, and thereby sets the bit transmission rate to 622 Mbps. Data DXX
0 is formed.

As described above, the P / S conversion section 51 performs the P / S conversion processing on the compressed digital video signal DCP0, and sets the bit transmission rate based on the compressed digital video signal DCP0 to 622 Mbps. DXX0 is derived. This serial data DXX0
FIG. 23 shows the compressed digital video signal DCP0
The compressed data formed by data compression by high-efficiency coding according to MPEG as shown in FIG.

Each of the P / S converters 52 to 54 also
For example, the P / S converter 51 is configured in the same manner as the P / S converter 51 shown in FIG. 9, and the P / S converters 52 to 54 supply the compressed digital video signals DCP1 to DCP3, respectively, as described above. The same operation as that performed when P / S conversion processing is performed on the compressed digital video signal DCP0 in the / S conversion unit 51 to form serial data DXX0 is performed. Thus, the P / S converters 52 to 54 provide the compressed digital video signal DCP
P / S conversion processing is performed on DCP1 to DCP3 to derive serial data DXX1 to DXX3 based on the compressed digital video signals DCP # 1 to DCP3, each having a bit transmission rate of 622 Mbps. Each of the serial data DXX1 to DXX3 is also a compressed digital video signal DCP1 to DCP3, as shown in FIG. To be formed.

In this manner, the P / S converters 51 to 54
Are supplied to the synchronous data insertion units 55 to 58, respectively. The control signal CSXB from the control signal forming unit 59 is also supplied to each of the synchronization data insertion units 55 to 58.

The synchronous data insertion unit 55 is provided, for example, in FIG.
It is configured as shown in FIG. Then, in the synchronous data insertion unit 55 shown in FIG.
Serial data DXX0 obtained from the switch 77
And the SEC detection unit 78. SEC detector 78
Is the SEC (sequence end code:
00000B7 (H)) detects the portion converted to serial data, and when the SEC detects the portion converted to serial data, the SEC
The detection output signal SEX0 is transmitted.

Further, a word data transmitting section 79 is provided in the synchronous data inserting section 55, and a control signal CSXB is supplied to each of the word data transmitting section 79 and the switch 77. The word data sending unit 79 outputs the control signal CS
At timing corresponding to XB, synchronous data DWSX0, which is serial data with a word transmission rate of 622 Mbps, is transmitted, and supplied to the switch 77. Then, the switch 77 controlled by the control signal CSXB receives the serial data D from the P / S converter 51.
XX0 and the synchronization data DW from the word data transmission unit 79
SX0 and the serial data DXX
The composite serial data DZX0 having a bit transmission rate of 622 Mbps is formed by partially inserting the synchronization data DWSX0 into 0.

Each of the synchronization data insertion units 56 to 58 has the same configuration as, for example, the synchronization data insertion unit 55 shown in FIG. 10, and in each of the synchronization data insertion units 56 to 58, the serial data DXX1 to DXX3 Are supplied, and the control signal C from the control signal forming section 59 is supplied.
As the SXB is supplied and the synchronization data DWSX1 to DWXS3 are respectively transmitted from the word data transmission units provided in each of them, the SEC detection output signal SEX0 is transmitted from the synchronization data insertion unit 55 as described above. The same operation as that performed when the serial data DZX0 is formed is performed. Thereby, in the synchronous data insertion units 56 to 58, the serial data DXX1 to DXX1
The SEC included in each of the DXX3s detects a portion where the SEC is converted to serial data, and outputs SEC detection output signals SEX1 to SEX1.
SEX3 is transmitted, and serial data DX is transmitted.
X1 to DXX3 are partially synchronized data DWSX1 respectively.
~ DWSX3 are inserted to form composite serial data DZX1 to DZX3 each having a bit transmission rate of 622 Mbps.

The composite data DZX0 to DZX3 formed in the synchronous data insertion units 55 to 58 are supplied to the data multiplexing unit 60. Also, the synchronous data insertion unit 55
SEC detection output signals SEX0 sent from
To SEX3 are supplied to the control signal forming unit 59.

SEC detection output signals SEX0 to SEX3
Is obtained by detecting the SEC included in each of the serial data DXX0 to DXX3. become. Then, the control signal forming section 59 outputs the serial data DX of the SEC detection output signals SEX0 to SEX3 supplied from the synchronous data inserting sections 55 to 58, respectively.
In each of X0 to DXX3, the latest signal (latest SEC detection output signal) obtained in each frame period portion is detected, and the control signal CSXB is detected as the latest SE.
It is formed as a signal corresponding to the C detection output signal, and is supplied to each of the synchronization data insertion units 55 to 58.

Under the circumstances, in the synchronous data insertion unit 55 shown in FIG. 10, the switch 77 converts the serial data DXX0 from the P / S conversion unit 51 and the synchronous data DWSX0 from the word data transmission unit 79. Upon selective extraction, the control signal CS from the control signal forming unit 59
In response to XB, the synchronization data DWSX0 is extracted from the word data transmission unit 79, and at other times, the serial data DXX0 from the P / S conversion unit 51 is extracted. Therefore, the compressed data included in each frame period portion of the serial data DXX0 is first extracted by the switch 77, and thereafter, when the compressed data no longer exists, immediately or after a time interval, the synchronous data DXX0 is extracted.
WSX0 will be retrieved. Thus, the composite serial data DZX0 formed in the synchronous data insertion unit 55 including the switch 77 is converted into the serial data DZX0.
This is obtained by inserting synchronization data DWSX0 into a portion where compressed data does not exist following a portion where compressed data exists in each frame period portion of XX0.

In each of synchronous data insertion units 56 to 58, control signal CSX from control signal forming unit 59 is also output.
B, the same operation as the operation in the synchronization data insertion unit 55 is performed, and the composite serial data DZX1 to DZX3 formed in the synchronization data insertion units 56 to 58, respectively.
Of the serial data DXX1 to DXX3, the synchronous data DWS is added to the portion where the compressed data does not exist following the portion where the compressed data exists in each frame period portion.
X1 to DWSX3 are obtained by being inserted respectively.

Thus, the synchronous data insertion units 55-5
8 synchronous data DWSX0-DWSX respectively used
SX3 is serial data each having a word transmission rate of 622 Mbps. When they are word-multiplexed in synchronization with each other to form 4-bit word string data, SX3 is shown in FIG. 4-bit word synchronization data Aa: 1111, Ab:
It is assumed that an additional word data group DWSX containing 0110, Ac: 0010 and Ad: 1000 is obtained. 4-bit word synchronization data Aa and Ab
Is to form 8-bit word synchronization data A1 when word multiplexing is performed, and the 4-bit word synchronization data Ac and Ad are converted to 8-bit word synchronization data A1 when word multiplexing is performed. This is to form data A2.

The additional word data group DWSX shown in FIG. 11 is composed of a plurality of 4-bit word data, and a set of three 4-bit word synchronization data Aa and 4-bit word synchronization data Ab is provided at the beginning. Followed by a set of three 4-bit word synchronization data Ac and 4-bit word synchronization data Ad. Also, at the terminal side, three 4-bit word synchronization data Aa and A pair with the 4-bit word synchronization data Ab is linked, and subsequently, 3 bits.
A set of four sets of 4-bit word synchronization data Ac and 4-bit word synchronization data Ad, that is, Aa A
b Aa Ab Aa Ab Ac Ac Ad Ac Ad Ac Ad ...
・ Aa Ab Aa Ab Ab Aa Ab Ac Ac Ad Ad Ac Ad
It has been. Then, in order to obtain such an additional word data group DWSX, the synchronization data D
As shown in FIG. 11, the synchronization data DWSX0 is serial data: 10101001.
... 101010010101,
Synchronous data DWSX1 is serial data: 111111
... 1111110000000, and the synchronization data DWSX2 is serial data: 1111
11101010 ... 111111101010
And the synchronous data DWSX3 is serial data: 10
1010000000 ... 1010100000
00 is selected.

As a result, a composite obtained by inserting the synchronous data DWSX0 from the synchronous data inserting unit 55 into a part where the compressed data does not exist following the part where the compressed data exists in each frame period part of the serial data DXX0 is obtained. As shown in FIG. 12, the serial data DZX0 has a portion where the synchronization data DWSX0 is inserted, as shown in FIG. 12, synchronization data DWSX0: 101010 sandwiched between bits Y0 constituting the serial data DXX0.
010101... 101010010101.

The composite serial data DZX1 to DZX3 obtained from the synchronous data insertion units 56 to 58 are also:
The portions where the synchronization data DWSX1 to DWSX3 are respectively inserted in them are the synchronization data DWSX1: 111 interposed between the bits Y1 forming the serial data DXX1.
111,000,000 ・ ・ ・ ・ ・ ・ ・ 11111100000
0, synchronous data DWSX2: 1111 sandwiched between bits Y2 forming serial data DXX2
11101010 ... 111111101010
And synchronous data DWSX3: 10 sandwiched between bits Y3 forming serial data DXX3
1010000000 ... 1010100000
00 will be provided.

In the data multiplexing section 60 to which the composite serial data DZX0 to DZX3 formed respectively in the synchronous data insertion sections 55 to 58 are supplied, synchronization of each frame period portion with the composite serial data DZX0 to DZX3 is performed. Bit multiplexing processing is performed under the
The composite serial data DZX0 to DZX3 are converted to composite 4-bit word string data DZX (4) having a word transmission rate of 622 MBps. At this time, the synchronization data DWS in the composite serial data DZX0 to DZX3
As shown in FIG. 13, the portion where X0 to DWSX3 is inserted is additional word data sandwiched between 4-bit words (Y0 Y1 Y2 Y3) based on bits Y0 to Y3 constituting serial data DZX0 to DZX3, respectively. Group D
WSX: Aa Ab Aa Ab Ab Aa Ab Ac Ad Ac Ad A
c Ad ··· Aa Ab Aa Ab Aa Ab Ac Ac Ad Ac
AdAc forms Ad.

Thus, composite 4-bit word string data DZX formed in data multiplexing section 60 is obtained.
(4), as shown in FIG. 14, the successive frame period portion (one frame) is composed of composite serial data DZ.
X0 to DZX3 each include a portion where multiplexed compressed data is obtained by multiplexing the compressed data, and an additional word data group DWSX inserted in a portion where the multiplexed compressed data does not exist. You. That is, the composite 4-bit word string data DZX (4)
Means that the portion where the multiplex compressed data exists and the portion where the multiplex compressed data does not exist are alternately connected, and the 4-bit word synchronization data Aa, Ab,.
Additional word data group DWS including Ac and Ad
It is assumed that X is inserted.

Then, the compound 4 in which the word transmission rate formed in the data multiplexing section 60 is 622 MBps.
The bit word string data DZX (4) is sent from the compound word string data forming unit 50 and supplied to the P / S conversion unit 61. The P / S converter 61 performs P / S conversion on the composite 4-bit word string data DZX (4) to convert parallel data into serial data, to obtain composite 4-bit word string data DZX (4). Based on this, serial data DZXS with a bit transmission rate of 622 MBps × 4 = 2.488 Gbps is formed, and the serial data DZXS is supplied to the transmission unit 62.

The transmitting section 62 transmits the serial data DZXS
Is transmitted through a data transmission path formed using a coaxial cable or an optical fiber, for example, an electric signal suitable for the data transmission path formed using a coaxial cable or an optical fiber is used. The transmission signal SZX is converted to an optical signal suitable for a data transmission path formed and transmitted. Thereby, transmission of the serial data DZXS is performed.

In the data transmission apparatus shown in FIG. 8, the P / S conversion section 61 and the transmission section 62 perform bit transmission of the composite 4-bit word string data DZX (4) having a word transmission rate of 622 MBps. 2.488G rate
Data transmission means for converting the data into serial data DZXS of bps and forming and transmitting a transmission signal SZX based on the serial data DZXS is formed. Therefore, the data transmission means formed by the P / S conversion section 61 and the transmission section 62 can be constituted by an existing IC element for SDH, for example. Therefore, FIG.
According to the data transmission method implemented by the data transmission device described in (1), word string data to which word synchronization data to which a predetermined code is assigned is added is formed based on the compressed digital video signal to be transmitted. In accordance with a transmission method in which the word string data is transmitted to be transmitted as serial data,
It is possible to multiplex the compressed digital video signals DCP0 to DCP3 of four channels, which are the compressed digital video signals, and to insert and transmit an additional word data group including the word synchronization data Aa, Ab, Ac and Ad. In this case, the data transmission means can be configured by effectively using existing IC elements such as those for SDH.

FIG. 15 shows a transmitting unit 31 in the data transmitting apparatus shown in FIG. 1 according to an example of the data transmitting method according to the invention described in any one of claims 1 to 7 of the present application. FIG. 1 shows an example of a data receiving apparatus for receiving a transmission signal SZ based on serial data DZS obtained by converting composite 8-bit word string data DZ (8), which is transmitted from.

In the example of the data receiving apparatus shown in FIG. 15, the data is transmitted from the transmitting section 31 in the data transmitting apparatus shown in FIG. 1, and is formed using, for example, a coaxial cable or an optical fiber. A receiving unit 81 that receives the transmission signal SZ transmitted through the data transmission path is provided. When receiving the transmission signal SZ, the receiving unit 81 reproduces the serial data DZS whose bit transmission rate based on the received transmission signal SZ is 2.488 Gbps, and reproduces the reproduced serial data DZS.
S is supplied to the synchronous data detection / S / P converter 82.

In the synchronous data detection / S / P converter 82, the supplied bit transmission rate is set to 2.488 Gbp.
In the serial data DZS to be s, a portion where three 8-bit word synchronization data A1 and three 8-bit word synchronization data A2 are converted into serial data is detected as synchronization data, and based on the detected synchronization data. The serial data DZS is subjected to S / P conversion with word synchronization to obtain 8-bit word-structured parallel data based on the serial data DZS. The parallel data based on the serial data DZS thus obtained is
It is set as composite 8-bit word string data DZ (8) having a word transmission rate of 311 MBps.

The composite 8-bit word string data DZ (8) obtained from the synchronous data detection / S / P converter 82 includes an additional word data group DWS, and is added to the composite 8-bit word string data DZ (8). The part including the word data group DWS is, for example, a part A shown in FIG.
As shown in FIG. Additional word data group D
In the WS, three consecutive 8-bit word synchronization data A1 and three consecutive 8-bit word synchronization data A2 following it are arranged at each of the start end and the end. The composite 8-bit word string data DZ (8) obtained from the synchronous data detection / S / P converter 82 is
The data is supplied to the data separation unit 83.

The synchronous data detection / S / P converter 82
Detects three consecutive 8-bit word synchronization data A1 and the following three consecutive 8-bit word synchronization data A2 in the additional word data group DWS in the composite 8-bit word string data DZ (8). Then, the word synchronous data detection output signal SWS is transmitted.
The word synchronization data detection output signal SWS is, for example,
Three consecutive 8-bit word synchronization data A1 in the additional word data group DWS in the composite 8-bit word string data DZ (8) detected by the synchronization data detection / S / P conversion unit 82, and successive data following it 3
Of the 8-bit word synchronization data A2, that is, three 8-bit word synchronization data A1 and 3
1 corresponding to the last 8-bit word synchronization data A2 of the 8-bit word synchronization data A2.
6 as shown in B.

In this way, synchronous data detection / S / P
The word synchronization data detection output signal SWS obtained from the conversion unit 82 is supplied to the control signal forming unit 84. And
In the control signal forming section 84, a synchronization control signal CW based on the word synchronization data detection output signal SWS is formed.

The data separating section 83 to which the composite 8-bit word string data DZ (8) is supplied from the synchronous data detecting / S / P converting section 82 is also supplied with the synchronous control signal CW from the control signal forming section 84. You. Then, in the data separation unit 83, under the control of the word synchronization by the synchronization control signal CW, the composite 8-bit word string data DZ (8)
, Serial data DX0 to DX7 having a bit transmission rate of 311 Mbps are separated and extracted, and synchronous data DWS0 to DWS7, which are serial data having a bit transmission rate of 311 Mbps, are separated and extracted.

Then, the serial data DX0 to DX7 obtained from the data separation section 83 are supplied to the S / P conversion section 85. The S / P converter 85 performs S / P conversion on each of the serial data DX0 to DX7, and the serial data DX0 has a word transmission rate of 74.25 MBp.
s is converted into a compressed digital video signal DCI0 which is 8-bit word string data, and the serial data DX1 is a compressed digital video signal DCI1 which is 8-bit word string data having a word transmission rate of 74.25 MBps.
The serial data DX2 is converted to a compressed digital video signal DCI2 which is 8-bit word string data having a word transmission rate of 74.25 MBps, and the serial data DX3 is converted to a word transmission rate of 74.25 MBps.
ps is converted into a compressed digital video signal DCI3 which is 8-bit word string data, and serial data DX4
Is a compressed digital video signal DCI which is 8-bit word string data having a word transmission rate of 74.25 MBps.
The serial data DX5 is converted into a compressed digital video signal DCI5 which is 8-bit word string data having a word transmission rate of 74.25 MBps, and the serial data DX6 is converted into a word transmission rate of 74.25M.
Is converted into a compressed digital video signal DCI6, which is 8-bit word string data at Bps, and converted into serial data DX.
7 is a compressed digital video signal DC which is 8-bit word string data having a word transmission rate of 74.25 MBps.
Converted to I7. Thus, the S / P converter 85 outputs the compressed digital video signals DCI0 to DCI of eight channels.
I7 is derived.

FIG. 17 shows another example of the data transmission method according to any one of the first to seventh aspects of the present invention. Transmission signal SZX based on serial data DZXS obtained by converting composite 4-bit word string data DZX (4) transmitted from section 62
1 shows an example of a data receiving device that receives a message.

In the example of the data receiving apparatus shown in FIG. 17, the data is transmitted from the transmitting section 62 in the data transmitting apparatus shown in FIG. 8, and is formed using, for example, a coaxial cable or an optical fiber. A receiving unit 86 that receives the transmission signal SZX transmitted through the data transmission path is provided. When receiving the transmission signal SZX, the receiving unit 86 reproduces the serial data DZXS having a bit transmission rate of 2.488 Gbps based on the received transmission signal SZX, and detects the reproduced serial data DZXS as synchronous data. It is supplied to the P conversion unit 87.

In the synchronous data detection / S / P converter 87, the supplied bit transmission rate is set to 2.488 Gbp.
s in the serial data DZXS, a set of three 4-bit word synchronization data Aa and 4-bit word synchronization data Ab and a set of three 4-bit word synchronization data Ac and 4-bit word synchronization data Ad are serial data. Are converted into serial data from the three 8-bit word synchronous data A1 and the three 8-bit word synchronous data A2, and are detected as synchronous data. S / P conversion is performed on the serial data DZXS with word synchronization based on the synchronization data to obtain 4-bit word-structured parallel data based on the serial data DZXS. The parallel data based on the serial data DZXS obtained in this manner is compound 4-bit word string data DZX (4) having a word transmission rate of 622 MBps.

The composite 4-bit word string data DZX (4) obtained from the synchronous data detection / S / P converter 87 includes an additional word data group DWSX.
The portion including the additional word data group DWSX in the bit word string data DZX (4) is, for example, as shown in FIG.
8A. In the additional word data group DWSX, three consecutive 4-bit word synchronization data Aa and 4
A set of bit word synchronization data Ab and a set of three consecutive 4-bit word synchronization data Ac and 4-bit word synchronization data Ad are arranged. The composite 4-bit word string data DZX (4) obtained from the synchronous data detection / S / P converter 87 is supplied to the data separator 88.

The synchronous data detection / S / P converter 87
, The composite 4-bit word string data DZX (4)
, A set of three consecutive 4-bit word synchronization data Aa and 4-bit word synchronization data Ab in the additional word data group DWSX, followed by three consecutive 4-bit word synchronization data Ac and 4-bit word synchronization data Ad, and a word synchronous data detection output signal SWSX is sent out. This word synchronous data detection output signal SWSX is, for example, synchronous data detection / S / P
A set of three consecutive 4-bit word synchronization data Aa and 4-bit word synchronization data Ab in the additional word data group DWSX in the composite 4-bit word string data DZX (4) detected by the conversion unit 87 and succeeding thereto. Corresponding to the last set of 4-bit word synchronization data Ac and 4-bit word synchronization data Ad, which is the last of three consecutive 4-bit word synchronization data Ac and 4-bit word synchronization data Ad. , Are obtained as shown in FIG.

In this way, synchronous data detection / S / P
The word synchronization data detection output signal SWSX obtained from the conversion unit 87 is supplied to the control signal formation unit 89. Then, in the control signal forming section 89, a synchronization control signal CWX based on the word synchronization data detection output signal SWSX is formed.

Synchronous control signal CWX from control signal forming section 89 is also supplied to data separating section 88 to which composite 4-bit word string data DZX (4) is supplied from synchronous data detecting / S / P converting section 87. You. Then, the data separation unit 8
8, under the condition that the word synchronization control by the synchronization control signal CWX is performed, the composite 4-bit word string data DZ
X (4), the serial data DXX0 to DXX3 having a bit transmission rate of 622 Mbps are separated and extracted, and the bit transmission rate is 622 Mbps.
Synchronous data DWSX0 to DWSX-D
WSX3 is separated and taken out.

Then, serial data DXX0 to DXX3 obtained from data separation section 88 are supplied to S / P conversion section 90. In the S / P converter 90, each of the serial data DXX0 to DXX3 is subjected to S / P conversion, and the serial data DXX0 has a word transmission rate of 14%.
It is converted into a compressed digital video signal DCP0 which is 8-bit word string data of 8.5 MBps, and the serial data DXX1 has a word transmission rate of 148.5 MBps.
Is converted into a compressed digital video signal DCP1, which is 8-bit word string data, and the serial data DXX2 is a compressed digital video signal DCP2, which is 8-bit word string data having a word transmission rate of 148.5 MBps.
, And the serial data DXX3 is converted into a compressed digital video signal DCP3 which is 8-bit word string data with a word transmission rate of 148.5 MBps.
Thereby, the compressed digital video signals DCP0 to DCP3 of four channels are derived from the S / P converter 90.

In the example shown in FIGS. 1 and 8 described above, in the specific configuration example of the synchronous data insertion unit 20 shown in FIG. 3, compressed data in each frame period in the serial data DX0 exists. 10 is detected by detecting the SEC included in the compressed data in each frame period in the serial data DX0. The specific configuration of the synchronous data insertion unit 55 shown in FIG. In the example, the serial data D
The detection of the end of the portion where the compressed data in each frame period exists in XX0 is detected by the SE included in the compressed data in each frame period in the serial data DXX0.
C is performed by detecting a portion where C is converted into serial data, but serial data DX0 and DX
The end of the portion where the compressed data is present in each frame period in each of X0 is detected by detecting the serial data DX0.
And DXX0 included in the compressed data following the portion in which the compressed data exists in each frame period, as shown in FIG. 23C where GSC is converted into serial data, or in FIG. PSC as shown in
Can be performed by using a portion converted into serial data.

[0122]

As is apparent from the above description, in the data transmission method according to any one of the first to seventh aspects of the present invention, the data is to be transmitted. Sent, eg, multiple MPEs
Composite word string data based on a plurality of compressed digital video signals, which are G-compressed digital video signals, include word synchronization data to which predetermined codes are assigned. The compound word string data including word synchronization data to which a predetermined code has been assigned and transmitted as serial data is converted into word synchronization data from the serial data to the parallel data on the receiving side. It is to be properly detected as word synchronization data required for a process for converting to a composite word sequence and a process for reproducing a plurality of compressed digital video signals from composite word string data. Therefore, on the receiving side, a state in which the data synchronization state required for the reproduction processing of the plurality of compressed digital video signals based on the received composite word string data is reliably obtained.

Therefore, according to the data transmission method according to any one of the first to seventh aspects of the present invention, the predetermined method is based on the compressed digital video signal to be transmitted. A word string data to which word synchronizing data to which the assigned code is assigned is formed, and each of the word string data is transmitted to be transmitted as serial data, for example, by an MPEG compressed digital video. A plurality of compressed digital video signals can be multiplexed and transmitted to be reliably reproduced on the receiving side.

Further, according to the data transmission apparatus of the invention described in claim 8 or claim 9 of the present application, the compression to be transmitted by the compound word string data forming means and the data transmitting means is performed. Based on the digital video signal, word string data to which word synchronizing data to which a predetermined code has been assigned is added, and the word string data is transmitted to be transmitted as serial data. However, for example, a plurality of compressed digital video signals, which are MPEG compressed digital video signals, can be multiplexed and transmitted to be reliably reproduced on the receiving side.

A data transmitting means for transmitting composite word string data based on a plurality of compressed digital video signals as serial data is constituted by effectively utilizing an existing IC element or the like for SDH. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a data transmission method according to the present invention; FIG. 10 is a block diagram illustrating an example of a data transmission device according to claim 9.

FIG. 2 is a block diagram showing a specific configuration example of a P / S conversion unit (11) in the example of the data transmission device shown in FIG. 1;

FIG. 3 is a block diagram showing a specific configuration example of a synchronous data insertion unit (20) in the example of the data transmission device shown in FIG. 1;

FIG. 4 is a time chart for explaining data used in an example of the data transmission method according to any one of the first to seventh aspects of the present invention.

FIG. 5 is a time chart for explaining data used in an example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application.

FIG. 6 is a time chart for explaining data used in an example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application.

FIG. 7 is a time chart for explaining data used in an example of the data transmission method according to any one of the first to seventh aspects of the present invention.

And FIG. 8 is a diagram showing another example of the data transmission method according to the invention described in any one of claims 1 to 7 in the claims of the present application. FIG. 10 is a block diagram showing another example of the data transmission device according to the eighth or ninth aspect.

9 is a block diagram showing a specific configuration example of a P / S conversion unit (51) in the example of the data transmission device shown in FIG. 8;

FIG. 10 is a block diagram showing a specific configuration example of a synchronous data insertion unit (55) in the example of the data transmission device shown in FIG. 8;

FIG. 11 is a time chart for explaining data used in another example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application. .

FIG. 12 is a time chart for explaining data used in another example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application. .

FIG. 13 is a time chart for explaining data used in another example of the data transmission method according to the invention described in any one of claims 1 to 7 in the claims of the present application. .

FIG. 14 is a time chart for explaining data used in another example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application. .

FIG. 15 shows an example of a data receiving apparatus for receiving a transmission signal transmitted according to an example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application. It is a block block diagram.

FIG. 16 is a time chart used for describing an operation of the example of the data receiving device illustrated in FIG. 15;

FIG. 17 shows an example of a data receiving apparatus for receiving a transmission signal transmitted according to another example of the data transmission method according to any one of claims 1 to 7 in the claims of the present application. FIG. 3 is a block diagram showing the configuration.

18 is a time chart used for describing an operation of the example of the data receiving device illustrated in FIG. 17;

FIG. 19 is a conceptual diagram explaining STM-1 used for transmitting digital data.

FIG. 20 shows an STM-
FIG. 3 is a conceptual diagram serving to explain STM-N obtained by multiplexing 1s.

FIG. 21 is a conceptual diagram explaining an example of a data format of a digital video signal.

FIG. 22 is a conceptual diagram explaining an example of a data format of a digital video signal.

FIG. 23 is a conceptual diagram illustrating an example of a data format of a compressed digital video signal.

[Explanation of symbols]

10, 50... Compound word string data forming section, 11 to 11
18, 30, 51 to 54, 61... P / S converter,
20 to 27, 55 to 58: synchronous data insertion unit, 2
8, 59: control signal forming unit, 29, 60: data multiplexing unit, 31, 62: transmitting unit, 32, 3
7, 41, 71, 76, 77 ... switch, 33,
72... Switch control signal forming section, 34, 35, 7
3, 74 ... memory unit, 36, 75 ... memory control signal forming unit, 42, 78 ... SEC detection unit, 4
3, 79: Word data sending unit

Claims (9)

[Claims] 1. A part in which compressed data exists and a part in which said compressed data does not exist are obtained by subjecting a digital video signal to data compression in units of a predetermined segment period. On the basis of a plurality of compressed digital video signals forming 8-bit word string data, a portion where multiplexed compressed data exists and a portion where the multiplexed compressed data does not exist alternately continue, and the multiplexing is performed. In the portion where the compressed data does not exist, an additional word data group including word synchronization data to which a predetermined code is assigned is inserted to form composite word string data, and the composite word string data is converted into serial data. And transmitting the serial data for transmission. 2. A method according to claim 1, wherein said plurality of compressed digital video signals are subjected to a process of multiplexing after inserting synchronization data into a portion of each of said plurality of compressed digital video signals where no compressed data exists, thereby multiplexing said plurality of compressed digital video signals. The compressed data in each of the video signals forms multiplexed compressed data, and the synchronization data inserted in the portion where the compressed data does not exist in each of the plurality of compressed digital video signals is assigned a predetermined code. 2. The data transmission method according to claim 1, wherein an additional word data group including the synchronized word synchronization data is formed to obtain composite word string data. 3. A parallel / serial conversion is performed on each compressed data in each of a plurality of compressed digital video signals,
Obtain serial data in which a portion where the serial compressed data exists and a portion where the serial compressed data does not exist alternately, and form synchronous serial data by inserting synchronization data into the portion where the serial compressed data does not exist in the serial data. 3. The data transmission method according to claim 2, wherein composite word string data is obtained by multiplexing a plurality of said composite serial data based on each of said plurality of compressed digital video signals. 4. The data transmission according to claim 1, wherein the additional word data group is selected to include a portion in which a plurality of the same 8-bit word synchronization data continue. Method. 5. An additional word data group includes: a portion in which a plurality of first 8-bit word synchronization data are connected;
5. The data transmission method according to claim 4, wherein the data transmission method includes selecting a portion including a plurality of continuous portions of second 8-bit word synchronization data different from the 8-bit word synchronization data. 6. A compressed data constituting each of a plurality of compressed digital video signals is obtained by performing data compression by high-efficiency coding on image information data representing a predetermined section period of the digital video signal. 6. The data transmission method according to claim 1, wherein the data is 8-bit word string data. 7. An 8-bit word string data obtained by subjecting compressed data constituting a compressed digital video signal to image information data representing each frame period of the digital video signal and performing data compression by high efficiency coding. 7. The data transmission method according to claim 6, wherein: 8. A portion in which compressed data exists and a portion in which said compressed data does not exist are obtained by subjecting a digital video signal to data compression in units of a predetermined section period. On the basis of a plurality of compressed digital video signals forming 8-bit word string data, a portion where multiplexed compressed data exists and a portion where the multiplexed compressed data does not exist alternately continue, and the multiplexing is performed. Compound word string data forming means for forming compound word string data in which an additional word data group including word synchronization data to which a predetermined code is assigned is inserted into a portion where the compressed data does not exist; The compound word string data obtained from the compound word string data forming means is converted into serial data and transmitted to transmit the serial data. And a data transmission means. 9. A compound word string data forming means performs parallel / serial conversion on each of the compressed data in each of the plurality of compressed digital video signals, and a portion where each of the compressed digital video signals has serial compressed data and a portion where the serial compressed data exists. Parallel / serial conversion means for obtaining a plurality of serial data in which a portion not to be alternately connected is provided, and a portion where the serial compressed data does not exist in each of the plurality of serial data obtained from the parallel / serial conversion means Synchronous data inserting means for forming a plurality of composite serial data, and multiplexing a plurality of composite serial data respectively obtained from the synchronous data inserting means and based on the plurality of compressed digital video signals. Data multiplexing means for obtaining composite word string data Data transmission apparatus according to claim 8, wherein.