JPH10174080A - Data transmission method and transmission / reception device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable large-capacity data transmission while ensuring security. SOLUTION: A CPU 20 reads MPEG2 data from an HDD 26 or a removable HDD 27, extracts only an I picture, and extracts the I picture as basic data from a RAM2.
Store it in 2. Then, the I picture is deleted, and the remaining data is stored in the RAM 22 as dependent data. A common name is assigned to both, and the subordinate data is transmitted over a satellite line, and the basic data is transmitted over a terrestrial line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting data from a transmitting device to a receiving device, and more particularly to a transmitting method using a broadcasting means capable of simultaneously transmitting a large amount of data to a large number of receiving devices. .

[0002]

2. Description of the Related Art Conventionally, when large-sized data such as video data is distributed to receiving devices located in various places, the data is digitally encoded and further compressed to reduce the amount of transmission data. Is considered.
However, even if such processing is performed, the data amount is still large, and distribution using a communication line such as a telephone network or ISDN is far from practical in terms of cost and communication capacity. On the other hand, there is data transmission in a broadcast format using a communication / broadcast satellite, for example, which has a large communication capacity and can simultaneously transmit data to a plurality of receiving devices.

[0003]

However, when data transmission in such a broadcasting format is adopted,
Due to the characteristic of simultaneous transmission to a wide range of unspecified people called "broadcast", the broadcasted content is not only intended recipients on the distribution side, such as regular subscribers, but also other unintended recipients Can be received relatively easily, and there is a problem in terms of security such as maintaining confidentiality of data to be transmitted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a merit of simultaneously transmitting a large amount of data in a broadcast format, and a data transmission method capable of ensuring the security of transmitted data. It is an object of the present invention to provide a transmitting device and a receiving device for realizing a transmission method.

[0005]

Means for Solving the Problems and Effects of the Invention According to the present invention, there is provided a method for transmitting data from a transmitting apparatus to a receiving apparatus. A part of the data is extracted as basic data, and data other than the basic data is generated using data created using the basic data or data created using the basic data. Data is converted to dependent data, and the basic data is transmitted from the transmitting device through a communication unit capable of specifying and transmitting the receiving device, and the dependent data can be simultaneously transmitted to an unspecified number of devices. Transmitted from the transmitting device via broadcasting means, and in the receiving device, transmitted via the broadcasting means and the basic data transmitted via the communicating means. Characterized in that so as to restore the data based on the serial dependent data.

According to the data transmission method, a part of data to be transmitted from the transmitting device to the receiving device is extracted as basic data. At the same time, data other than the basic data is converted to dependent data, which is data created using the basic data or data created using the data created using the basic data. And
The basic data is transmitted from the transmitting device via a communication unit capable of transmitting a specified receiving device, and the dependent data is transmitted from the transmitting device via a broadcasting unit capable of transmitting an unspecified number of simultaneous data. On the other hand, the receiving device restores the data based on the basic data transmitted via the communication means and the dependent data transmitted via the broadcasting means.

[0007] As described above, when data is transmitted from a transmitting device to a receiving device, since data is transmitted via broadcasting means, data is individually transmitted to all receiving devices. In comparison with the above, the advantage of simultaneous transmission of large amounts of data in a broadcast format can be obtained. Therefore, it is very effective if adopted in a system or the like in which one transmitting device needs to transmit data to many receiving devices.

However, in the case of data transmission in a broadcast format, as described above as a problem of the prior art, the "broadcast"
Due to the characteristic of simultaneous transmission to a wide range of unspecified large numbers, not only intended recipients on the distribution side such as regular subscribers, but also other Since the data can be easily received, there is a problem in terms of security such as maintaining the confidentiality of the data to be transmitted.

This transmission method is also effective for such security. That is, instead of transmitting all of the data by the broadcasting means, the basic data is transmitted through the communication means capable of specifying the receiving device and transmitting,
Dependent data is transmitted via broadcast means. And
The relationship between the basic data and the dependent data has a factor for ensuring security. In other words, a part of the data is extracted as basic data, and dependent data other than the basic data is data created using the basic data or data created using the data created using the basic data. It is assumed that it was converted as.

Thus, even if the undesired receiver on the data transmitting side intercepts the dependent data transmitted by the above-described broadcasting means, for example, it is impossible to restore the original data using the dependent data alone. . And
For example, simply dividing data may make the divided data itself substantially meaningful data. However, in this method, data created using basic data or data further created using the data is used. Is dependent data, so dependent data alone does not become substantially meaningful data. That is, since data can be restored only by the receiving device that has received the transmission of the basic data, security of the data content can be ensured.

As described above, according to the data transmission method of the present invention, the security of transmitted data can be ensured while having the advantage of transmitting large-capacity data simultaneously in a broadcast format. In addition, as shown in claim 2, for the dependent data, information for identifying the data from which the dependent data is created is added and transmitted from the transmitting device, and in the receiving device, Based on the basic data and the dependent data, specify the data from which the dependent data is created by the added information,
The data may be restored.

[0012] In order to enable the receiving device to specify which basic data the dependent data was created on, the information for specifying the dependent data is added to the dependent data. Of course, there are cases where the receiver can specify which basic data was created based on the prescribed rules, but if it is added to the dependent data to be transmitted, it can be handled only by analyzing the dependent data. As a result, advantages in terms of the structure of the device can be obtained.

An example of such data is, for example, image data compressed based on the MPEG video coding system as described in claim 3. In this case, the basic data includes an I (Intra coded) picture, and the dependent data includes a P (Predictive coded) picture and a B (Bidirectiona).
lly Predictive coded), and information added to the dependent data may be header information of the I picture.

This is because the I picture is intra (in the screen)
The P picture is a forward predictive coding screen, whereas the coding screen is coded independently of other screens.
Motion-compensated predictive coding is performed from an I or P picture located in the past in time, and a B picture is a forward predictive coded picture using a preceding or succeeding I or P picture. Motion compensated predictive coding is performed from a screen in one direction, backward direction, or both directions.

That is, since the P picture and the B picture are coded with a difference from other frames,
If there is no I picture that encodes the original signal, the data becomes meaningless by itself. Therefore,
By transmitting an I picture as basic data by a communication means having a high degree of security and transmitting other P pictures and B pictures by a broadcasting means, there is an advantage of simultaneous transmission of large-capacity data in a broadcast format. In addition, security of transmission data can be ensured.

Of course, data applicable to the present method is not limited to MPEG data. For example, data is divided into data groups of a predetermined unit, a first data group is used as basic data, a difference from the basic data is obtained for a second data group, and a second data group is obtained for a third data group. It is also conceivable that the difference from the data is obtained, and the difference from the immediately preceding data group is used as the dependent data. Also in this case, the difference data alone has substantially no meaning, and eventually the original data cannot be created without the basic data.

[0017] As a transmission apparatus for realizing such a data transmission method, for example, the configuration described in claim 4 can be considered. That is, while extracting a part of data as basic data, data other than the basic data is
A data extraction / conversion means for converting data created using the basic data or dependent data that is data created using the data created using the basic data, and receiving the basic data, A first transmission unit that transmits the communication data via a communication unit that can specify and transmit the device; and a second transmission unit that transmits the dependent data via a broadcasting unit that can simultaneously transmit the dependent data to an unspecified number. It is characterized by the following.

Further, the receiving device may be, for example, a device according to claim 5
Can be considered. That is, first receiving means for receiving basic data as a part of data transmitted from the transmitting device via the communication means, and receiving data other than the basic data transmitted via the broadcasting means. A second receiving unit, wherein the data other than the basic data is data created using the basic data, or data created using data created using the basic data. Dependent data, comprising restoring means for restoring the data based on the basic data received by the first receiving means and the dependent data received by the second receiving means. .

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a transmission system as one embodiment for realizing the present data transmission method. This transmission system is composed of one center 2 as a "transmitting device" and a plurality of terminals 1 as a "receiving device". Two types of data transmission, “transmission by satellite line”, are possible via the transmission line 30. When the data is transmitted via the public line 50, the terminal 2 can be specified from the center 2 and data can be transmitted. For example, if the public line 50 is a telephone line, the center 2
The user can specify the telephone number of the terminal 1 and make a call to establish a connection to the desired terminal 1. On the other hand, when passing through the satellite 30, data can be simultaneously transmitted to an unspecified number of terminals 1 in a so-called broadcast format.

First, the terminal 1 will be described. FIG.
FIG. 2 is a block diagram illustrating an internal configuration of a terminal 1. As shown in FIG. 2, the terminal 1 includes a modem 13 for performing data communication with the center 2 via a public line 50, and a temporary storage means used for temporarily storing data captured through the modem 13. RAM 12 as center and center 2
And a tuner 15 for separating multiplexed data from the satellite broadcast wave, which is connected to a parabolic antenna 110 for receiving a satellite broadcast wave in which data broadcast from the satellite 30 is multiplexed. And a demodulator 14 for demodulating data. The data demodulated by the demodulator 14 is also temporarily stored in the RAM 12, and predetermined data is restored with the data temporarily fetched via the modem 13 and stored as a storage means. It is stored in the HDD 16. In the present embodiment, the data stored in the HDD 16 is image data compressed based on the MPEG2 video coding method. The processing related to the data restoration will be described later.

The terminal 1 also includes a remote control light-receiving unit 18 for receiving a request from the remote control 112 from a user, and M stored in the HDD 16.
MPEG2 decoder 1 for decoding PEG2 data
7 is provided. It should be noted that the image data decoded by the MPEG2 decoder 17 is stored in a CR
At T11, display output can be performed.

The modem 13 corresponds to "first receiving means", and the parabolic antenna 110, tuner 15 and demodulator 14 correspond to "second receiving means".
Further, the CPU 10 corresponds to “restoring means”. Next, the center 2 will be described. FIG. 3 is a block diagram showing the internal configuration of the center 2.

The center 2 communicates with the terminal 1 through the public line 50.
23 for performing data communication with the terminal 1, an HDD 26 and a removable HDD 27 as storage means for storing data to be transmitted to the terminal 1, and basic data transmitted from the data to be transmitted via a ground line. CPU 20 as control means for extracting predetermined data, performing predetermined processing on other data, and performing processing for converting the data into dependent data transmitted via a satellite line, and the like.
R storing a program to be executed by the CPU 20
An OM 21, a RAM 22 serving as a temporary storage means, a transmission control device 24 for controlling transmission of the dependent data via a satellite line, and a modulator 25 for modulating the data and multiplexing the data into a satellite broadcast wave. Have. Then, the satellite broadcast wave modulated by the modulator 25 is transmitted to the satellite 30 by the parabolic antenna 210.

The CPU 20 corresponds to "data extraction / conversion means". The modem 23 corresponds to a “first transmission unit”, and the transmission control device 24, the modulator 25, and the parabolic antenna 210 correspond to a “second transmission unit”. The data stored in the HDD 16 is an MPE
The image data is compressed based on the G2 video encoding method (hereinafter, referred to as MPEG2 data). Here, the MPEG2 data will be described.

As shown in FIG. 7, image data compressed in the MPEG2 format is I (Intra coded) encoded independently of other screens on a screen of intra (intra picture) encoding.
) A picture, a P (Predictive coded) picture obtained by performing motion compensation prediction coding from an I or P picture located in the past in the forward prediction coding screen, and a temporal prediction B (Bidirectionally Predicated) in which motion-compensated predictive coding is performed from a picture in a forward direction, a backward direction, or both directions using I or P pictures located before and after
tive coded) pictures.

That is, since the P picture and the B picture are coded with a difference from other frames,
If there is no I picture that encodes the original signal, the data becomes meaningless by itself. The transmission system of the present embodiment utilizes such a property of MPEG2 data, transmits an I-picture as "basic data" to the terminal 1 over a terrestrial line with a high degree of security, and transmits other P-pictures and B-pictures. Is transmitted to the terminal 1 via a satellite line which has an advantage of simultaneous transmission of large-capacity data in a broadcast format as "dependent data", thereby realizing both simultaneous transmission of large-capacity data and security of transmitted data. It is assumed that.

Processing relating to data transmission from the center 2 to the terminal 1 will be described with reference to the flowcharts of FIGS. First, a data transmission process in the center 2 will be described with reference to FIG. First step S
10, the HDD 26 or the removable HD
The MPEG2 data to be transmitted to the terminal 1 is read from D27, and an I picture is extracted. As shown in FIG.
PEG2 data is I1 → B3 → P2 → B5 → P4 → I6
→ B8 → P7 → B10 → P9 → I11 → B13 → P12
Assume that pictures are arranged in the order of → B15 → P14 → I16 →. Here, I, P,
The number attached after B indicates the order of encoding. Since the I and P pictures located behind in time are coded prior to the B picture, I1 → B3 → P2 → B
5 → P4... Note that the decoding process is also performed in this order, and when outputting an image, the image is displayed in the original order.

After all, only the I picture is extracted in S10, so as shown in FIG. 6, I1, I6, I11, I16
... "Basic data". The basic data extracted in this way is temporarily stored in the RAM 22. The following S
In step 20, in the original MPEG2 data, the I picture itself is deleted, leaving only the header for the I picture. Therefore, in this case, as shown in FIG.
Header, B3, P2, B5, P4, I6 header, B
8, P7, B10, P9, I11 header... "Dependent data". The dependent data thus obtained is temporarily stored in the RAM 22.

In S30, a common data name is assigned to the basic data consisting of only the I picture obtained by the processing of S10 and the dependent data consisting of the header, P picture and B picture of the I picture obtained by the processing of S20.
Then, in S40, the dependent data is transmitted via a satellite line,
In S50, the basic data is transmitted via the ground line.

When transmitting the dependent data via the satellite line, the dependent data is transmitted to the modulator 25 through the transmission control device 24.
And the modulator 25 modulates the dependent data and multiplexes the modulated data into satellite broadcast waves. The satellite broadcast wave modulated by the modulator 25 is transmitted to the satellite 30 by the parabolic antenna 210. When transmitting the basic data via the ground line, the basic data is transmitted after connecting to the destination terminal 1 via the modem 23 and the public line 50.

Next, with reference to FIG. 5, a data receiving process in the terminal 1 and a subsequent data restoring process will be described. In the first step S110, it is determined whether or not data having a common data name from the satellite line and the terrestrial line, that is, whether basic data and subordinate data have been received. The premise of this determination will be described. As described above, the transmission destination terminal 1 is designated from the center 2 via the ground line, that is, the public line 50, and the basic data is transmitted.
Therefore, terminal 1 receives the basic data via modem 13 and temporarily stores it in RAM 12. On the other hand, a satellite link, that is, a satellite 30, transmits satellite broadcast waves in which dependent data is multiplexed. Since this is a broadcast wave, it is transmitted simultaneously to an unspecified number of terminals 1. Therefore, if the terminal 1 is ready to receive, the data is appropriately received via the parabolic antenna 110, the tuner 15 and the demodulator 14, and the data demodulated by the demodulator 14 is temporarily stored in the RAM 12.

Therefore, the determination in S110 can be made based on whether the basic data and the subordinate data having the common data name are both received and stored in the RAM 12. If both data (basic data and dependent data) are stored in the RAM 12 (S110:
YES), proceeding to S120, based on the I picture header information included in both data, MPEG2 which is the original data.
Reconstruct the data. This explains the process of extracting and converting basic data and dependent data in the center 2.
The reverse process is performed. That is, as shown in FIG. 6, the header of I1, B3, P2, B5, P4, I6
At the position of the I-picture header of the dependent data consisting of the headers of B8, P7, B10, P9, I11,.
MPEG2 data is reconstructed so as to incorporate pictures.

At S130, the reconstructed MPEG2
The data is stored in the HDD 16. Thus, the processing of receiving, restoring, and saving the data in the terminal 1 ends.
As described above, in the transmission system of the present embodiment, when data is transmitted from the center 2 to the terminal 1, the data is multiplexed and transmitted to the satellite broadcast wave by the satellite line, The advantage of simultaneous transmission of large amounts of data in a broadcast format can be obtained as compared with the case where data is transmitted individually. Therefore, one center 2
Is very effective in a system that needs to transmit data to a large number of terminals 1.

However, in the case of data transmission in a broadcasting format, for example, the terminal 1 owned by a person other than the regular subscriber also receives a satellite broadcast wave due to the characteristic of simultaneous transmission to an unspecified large number of people in the "broadcast". Can be done.
In other words, not only the intended recipient on the distribution side, but also other unintended recipients can receive the broadcasted content relatively easily, so security such as maintaining the confidentiality of the transmitted data is important. There is a problem.

In the present system, such security is also taken into consideration. In other words, not all data is transmitted using a satellite line, but basic data is transmitted using a terrestrial line. Since the data is transmitted via the public line 50, the terminal 1 at the transmission destination can be specified to transmit data.

Further, there is a factor for ensuring security in the relationship between the basic data and the dependent data. That is,
A part of the data is extracted as basic data, and the dependent data other than the basic data is converted as data created using the basic data or data created using the data created using the basic data. It is supposed to have been done.

In the above example, the MPE as the original data
For G2 data, I picture is used as basic data,
P and B pictures are dependent data. An I picture is a screen of intra (intra-screen) coding and is coded independently of other screens, whereas a P picture is a forward prediction coding screen and is a picture which is located in the past in time. Or a motion compensated predictive coding performed from a P picture,
A picture is a forward prediction coded picture, which is obtained by performing motion compensated predictive coding from a picture in a forward direction, a backward direction, or both directions using I or P pictures located before and after in time. Therefore, since the P picture and the B picture are coded with a difference from other frames, if there is no I picture coded from the original signal, the data alone becomes substantially meaningless data. .

Although the basic data is transmitted via a terrestrial line, the terminal 1 needs to have a one-to-one connection / communication with the center 2 via a public line 50. Terminal 1 that is present and terminal 1 that is not,
For the process of removing devices that are not legally contracted,
For example, it can be realized relatively easily by a method such as distributing only to the terminal 1 having a telephone number registered by contract from the center 1 side.

Therefore, I-pictures as basic data are transmitted via a terrestrial line with a high security degree, and P-pictures and B-pictures as dependent data are transmitted by satellite broadcast waves over a satellite line, thereby making it possible to change the broadcasting format. While having the advantage of simultaneous transmission of large amounts of data, the security of transmitted data can be ensured.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above embodiment, MPEG2 data is adopted as data to be transmitted, but data applicable to the present invention is not limited thereto. For example, data is divided into data groups of a predetermined unit, a first data group is used as basic data, a difference from the basic data is obtained for a second data group, and a second data group is obtained for a third data group. It is also conceivable that the difference from the data is obtained, and the difference from the immediately preceding data group is used as the dependent data. An example of data obtained by taking such a difference will be described more specifically with reference to FIG.

As shown in FIG. 8 (A), the original data is represented by a numeral string of "43784854785349792890".
...... ". In this case, first, FIG.
, The data is divided into a data group composed of five numeric strings. Therefore, "43785", "4278"
5 "," 43799 "," 42890 ".... Next, data compression is performed.
785 ”alone is used as basic data. Then, a difference from the immediately preceding data group is obtained from the next data group.

Therefore, the second data group "4278"
For "5", difference data "1, -1" from the first data group "43785" is obtained. Note that the notation of the difference data will be described in this case.
As shown in (B), addresses 0, 1, 2, 3, and 4 are assigned to five numeric strings forming a data group. Therefore, the meaning of the difference data "1, -1" means that there is a difference of -1 with respect to the data at address 1.

Similarly, the third data group “4279”
For "5", difference data "3, +1" from the second data group "42785" is obtained, and the fourth data group "4
2890 ”is the third data group“ 42795 ”
Is obtained as difference data "2, +1; 4-5". The meaning of the difference data "2, +1; 4-5" means that the data at address 2 has a difference of +1 and the data of address 4 has a difference of -5.

In this case as well, the differential data, which is the dependent data, is transmitted in a broadcast format. However, since the differential data is meaningless without the basic data, even if only the differential data is illegally acquired. Therefore, the possibility that the contents of the original data string are known is greatly reduced.

In the above embodiment, the satellite 30
Data transmission by satellite line using
The same effect can be obtained even in the case of data transmission in a broadcast format using terrestrial waves without using the satellite 30.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a transmission system according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration of a terminal according to the embodiment.

FIG. 3 is a block diagram illustrating a configuration of a center according to the embodiment.

FIG. 4 is a flowchart illustrating an operation related to data transmission and the like executed in the center of the embodiment.

FIG. 5 is a flowchart illustrating an operation related to data reception and the like executed in the terminal of the embodiment.

FIG. 6 is an explanatory diagram of how to extract and convert basic data and dependent data.

FIG. 7 is an explanatory diagram of I, P, and B pictures of MPEG2 data.

FIG. 8 is an explanatory diagram showing another mode of the basic data and the dependent data.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Terminal 2 ... Center 13 ... Modem 14 ... Demodulator 15 ... Tuner 16 ... HDD 17 ... MPEG2 decoder 18 ... Remote control light-receiving part 23 ... Modem 24 ... Transmission control device 25 ... Modulator 26 ... HDD 27 ... Removable HDD 30 ... Satellite 50: Public line 110: Parabolic antenna 112: Remote control 210: Parabolic antenna

Claims (5)

[Claims] 1. A method for transmitting predetermined data from a transmitting device to a receiving device, comprising: extracting a part of the data as basic data;
The data other than the basic data is converted into dependent data that is data created using the basic data or data created using the data created using the basic data, and for the basic data, The receiving device is transmitted from the transmitting device via communication means capable of specifying and transmitting the receiving device, and the dependent data is transmitted from the transmitting device via broadcasting means capable of simultaneously transmitting an unspecified number to the receiving device; , A method of restoring the data based on the basic data transmitted via the communication means and the dependent data transmitted via the broadcasting means. 2. The device according to claim 1, wherein the dependent data is transmitted from the transmitting device with information for specifying data from which the dependent data is created, and transmitted by the transmitting device. 2. The data transmission method according to claim 1, wherein data based on which the dependent data is created is specified based on the dependent data and the added information is used to restore the data. 3. The data is image data compressed based on an MPEG video encoding method, wherein the basic data includes an I (Intra coded) picture, and the dependent data includes a P ( 3. The data transmission method according to claim 2, wherein the data includes a Predictive coded picture and a B (Bidirectionally Predictive coded) picture, and the information added to the dependent data is header information of an I picture. 4. A part of the data is extracted as basic data, and data other than the basic data is extracted using data created using the basic data or data created using the basic data. Data extraction / conversion means for converting to dependent data which is data to be created; first transmission means for transmitting the basic data via a communication means capable of identifying and transmitting a receiving device; And a second transmission means for transmitting via an unspecified number of simultaneous transmission broadcast means. 5. A first method for receiving basic data as a part of data transmitted from a transmitting device via communication means.
Receiving means, and second receiving means for receiving data other than the basic data transmitted via the broadcasting means, wherein the data other than the basic data is created using the basic data. Data, or dependent data that is data created using data created using the basic data, wherein the basic data received by the first receiving means and the second receiving means Receiving means for restoring the data based on the dependent data received by the receiving apparatus.