JP2000197017A - Digital signal transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display the character of emergency information or the like together with video at a reception time, without expanding and decoding a digital video signal to be transmitted to a reception side, which has been already compressed and encoded with high performance, once at a transmission side. SOLUTION: A transmitter multiplexes digital information signal showing the character, which is generated by an information stream generating device 107 and to which N-stage priority information is added, on a digital video signal and a digital audio signal by a multiplexing device 110 and transmits them to a receiving device. In the receiving device, it is judged whether the character shown by the digital information signal is displayed or not based on priority information added to the digital information signal. When it is decided to be displayed, the character shown by the digital information signal is displayed together with the video which is shown by the digital video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for allocating a single bit string in which a plurality of digital signals are multiplexed to each of a plurality of frequency channels on a transmission path and transmitting the same.

[0002]

2. Description of the Related Art In the United States, many cable television (CA)
TV) companies and local telephone companies have announced interactive video service initiatives. Each company is experimenting with a multi-channel service as a preliminary step toward the concept of an interactive video service. On the other hand, in Japan, an experimental site for CATV interactive video service has been opened, and experiments on multi-channel services have begun.

FIG. 3 shows an example of a frequency arrangement in a CATV interactive video service.

In FIG. 3, reference numeral 301 denotes a CA from a subscribing household.
An uplink band to the TV station, 302 is an analog downlink band from the CATV station to the subscriber household, and 303 is a digital downlink band from the CATV station to the subscriber household.

[0005] The analog downstream band 302 corresponds to the existing CA.
It is used as a downlink channel in TV video services. Specifically, the analog downstream band 302 is a CAT
It is used to transmit analog video signals for a plurality of programs from the V station to the subscribing household.

The digital upstream band 301 is C
The digital downlink band 303 is used as an uplink channel in the ATV interactive video service, and the digital downlink band 303 is used as a downlink channel in the CATV interactive video service. More specifically, the digital upstream band 301 is used to transmit a digital control signal indicating a program or the like requested from the subscribing household to the CATV station, and the digital downstream band 303 is used to transmit a plurality of programs from the CATV station to the subscribing household. Used to transmit digital video signals for minutes. The digital downstream band 303 needs to transmit various kinds of digital video signals corresponding to requests from the subscriber households. Therefore, a multi-channel service in which digital video signals for a plurality of programs are multiplexed on one channel. Bandwidth.

[0007] The example of FIG. 3 utilizes the fact that the bandwidth of the analog downstream band 302 is narrow, and provides the CATV two-way video service using the transmission equipment used to provide the existing CATV video service. It is possible to provide.

FIG. 4 shows an example of a video multiplex transmission system for multiplexing and transmitting a plurality of digital video signals.

In the figure, 401 is a video server, 402 is a multiplexing device, 403 is a channel coding device, 404 is a digital modulator, 405 is an RF converter, 406 is a frequency multiplexing device, 407 is a receiver, 408 is a monitor,
09 is a tuner, 410 is a digital demodulator, 411
Is a waveform equalizer, 412 is a channel decoding device, 413 is a separation device, 414 is a digital video decompression device, and 415 is a transmission cable.

In FIG. 4, various digital video signals obtained from various information providers are stored in a video server 401, and these digital video signals are compressed and encoded with high efficiency.

The multiplexing device 402 multiplexes the digital video signals for a plurality of programs and multiplexes the digital video signals for the plurality of programs stored in the video server 402 in order to allocate them to one channel. Convert to one bit string. The single bit string is added with an error correction code by the channel coding device 403, digitally modulated by the digital modulation device 404, and then assigned to a channel by the RF conversion device 405. (A plurality of single bit strings) are frequency-multiplexed and transmitted to the receiver 407 via the transmission cable 415.

In the receiver 407, a program number indicating a program whose analog video signal is to be displayed on the monitor 408 and a channel number indicating a channel to which the program is assigned are input to the tuner 409 by an external operation. ing.

The tuner 409 selects a channel indicated by the input channel number from a plurality of channels transmitted via the transmission cable 415,
The digital demodulation device 410 digitally demodulates a single bit sequence assigned to the channel selected by the tuner 409, and the waveform equalization device 411 removes the ghost of the single bit sequence.
2 performs error correction based on the error correction code. on the other hand,
The tuner 409 converts the input program number into the separating device 41.
3 and the separation device 413 sends the tuner 409
The digital video signal of the program indicated by the program number notified from is separated. The separated digital video signal is converted into an analog video signal by the digital video decompression device 414 and displayed on the monitor 408.

As described above, in the video multiplex transmission system, digital video signals for a plurality of programs can be allocated to one channel and transmitted, so that new service possibilities can be found.

Now, CA having the frequency arrangement shown in FIG.
In the TV interactive video service, when it becomes necessary to display emergency information such as natural disasters or incidents on the receiving side receiving the analog video signal transmitted by the analog downstream band 302, the transmitting side Thus, an analog information signal representing a character for displaying the emergency information as a character is multiplexed with the analog video signal.

For example, Japanese Patent Application Laid-Open No. 60-65673 discloses a method of sequentially displaying characters on a television receiver by mixing a television signal and a character signal synchronized with the television signal. ing.

FIG. 5 is a block diagram showing a configuration of a character signal processing apparatus for realizing the method disclosed in Japanese Patent Application Laid-Open No. 60-65673.

In FIG. 5, reference numeral 501 denotes a television camera unit; 502, an output terminal of a television signal; 503, an output terminal of a horizontal / vertical synchronization signal synchronized with the television signal; and 504, a character signal synchronized with the television signal. 505 is a mixing circuit for mixing the television signal and the character signal, and 506 is a start signal generating circuit for generating a start signal for notifying the mixing circuit 505 of the timing of starting the mixing of the character signal. circuit,
Reference numeral 507 denotes a variable gate pulse circuit that generates a gate signal whose rising edge coincides with the input of a start signal and whose pulse width increases in the horizontal direction as time passes. Reference numeral 508 denotes a gate circuit that gates a character signal by a gate signal.

FIG. 6 shows a display screen of a television receiver on which characters are displayed by the method disclosed in Japanese Patent Application Laid-Open No. 60-65673.

In FIG. 6, reference numeral 601 denotes a display screen;
Is a gate start position which is a start position on the display screen 601 of the gate signal.

In the character signal processing device shown in FIG.
When the start signal is output from the start signal generation circuit 506, the variable gate pulse circuit 507 raises the gate signal from the gate start position 602 shown in FIG. Become larger. Further, the gate circuit 508 gates the character signal output from the character signal generation circuit 504 by the gate signal output from the variable gate pulse circuit 507, and the mixing circuit 505 outputs the character signal and the character signal output from the gate circuit 508. Mix with television signal.

As a result, as shown in FIG. 6, black characters 603 are displayed on the display screen 601 of the television receiver.
Is displayed. Then, as the pulse width of the pulse signal increases in the horizontal direction with the passage of time, the undisplayed characters 604 indicated by white characters are sequentially displayed as black characters.

[0023]

In a service for transmitting an analog video signal such as an existing CATV video service, as a method of displaying emergency information in characters on a receiving side receiving the analog video signal, the above-mentioned known example is described in the following. Are better.

However, when a multi-channel service such as video-on-demand (hereinafter, referred to as VOD) or near video-on-demand (hereinafter, referred to as NVOD) is to be performed, the transmission side receives the data. Since the video signal to be transmitted to the side is a digital video signal that has already been compressed and encoded with high efficiency, in order to apply the above-mentioned known example,
It is necessary to expand and decode the digital video signal once on the transmitting side, which is difficult to realize from the viewpoint of cost.

Here, the VOD is a function of interactively searching and transmitting a digital video signal of a program corresponding to a request of a subscriber household from a plurality of programs.
NVOD is a function for responding to a request from a plurality of subscribing households for one program. A plurality of digital video signals of the same program which can be supplied with a delay of about 10 to 15 minutes are prepared. This function transmits a digital video signal close to the request time.

In view of the above problems, it is an object of the present invention to provide a multi-channel service such as VOD, NVOD, etc., on the transmitting side, which should be transmitted to the receiving side, which has already been compressed and encoded with high efficiency. It is an object of the present invention to provide a technology that enables characters such as emergency information to be displayed together with a video on a receiving side without having to expand and decode a digital video signal once.

[0027]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides priority information addition for adding N stages (N is a positive number) of priority information to a digital information signal which is a digital signal representing a character. Means, first multiplexing means for creating a plurality of single bit strings multiplexing a plurality of compressed digital video signals representing video, and the digital information signal to which the priority information adding means has added the priority information. Second multiplexing means for multiplexing each of the plurality of single bit strings created by the first multiplexing means, and each of the plurality of single bit strings obtained by multiplexing the digital information signal by the second multiplexing means; Transmitting means for allocating a signal to each of a plurality of frequency channels on a transmission path, and transmitting one of the plurality of frequency channels transmitted from the transmitting apparatus. Separating means for separating any digital video signal from the single bit string assigned to the channel, and separating the digital information signal multiplexed with the single bit string; Determining means for determining whether or not the digital information signal should be reproduced based on priority information added to the digital information signal; and reproducing and displaying the digital video signal separated by the separating means on a video First reproducing means for reproducing the digital information signal separated by the separating means into a character when the determining means determines that the character should be reproduced, and displaying the reproduced character on the first reproducing means. And a receiving device having a second reproducing means for mixing with the video to be reproduced.

For example, the priority information can be N-level priority information whose value increases as the degree of importance increases.

At this time, the receiving apparatus further includes a set value storage means for storing a set value M (M is a positive number, M ≦ N) set in advance. If the level of the priority information added to the digital information signal separated by the separating means is smaller than the set value M stored in the set value storing means, the determining means reproduces the digital information signal. When the priority information added to the separated digital information signal by the separation means is equal to or greater than the set value M stored in the set value storage means, it is determined that the digital information signal should not be changed. It is determined that playback should be performed.

Further, for example, the priority information may be two-stage priority information indicating whether or not to perform forced display.

At this time, the receiving apparatus further includes a reproduction presence / absence information storage means for storing information indicating whether or not it is necessary to reproduce the digital information signal, which is set in advance. When the information stored in the reproduction presence / absence information storage means indicates that reproduction is necessary, the determination means determines whether the priority information added to the digital information signal separated by the separation means is sufficient. Regardless of the stage, if it is determined that the digital information signal should be reproduced, and the information stored in the reproduction presence / absence information storage means indicates that reproduction is not necessary, the separation means If the level of the priority information added to the digital information signal indicates that forced display is to be performed, it is determined that the digital information signal should be reproduced, and the digital information signal separated by the separation means is output. If the stage of the added priority information does not indicate that the forced display is to be performed, it is determined that the digital information signal should not be reproduced.

Further, the present invention provides identification information adding means for adding identification information indicating the contents of a character represented by a digital information signal to a digital information signal which is a digital signal representing a character, and a plurality of compressed information representing a video. Multiplexing means for creating a plurality of single bit strings obtained by multiplexing the digital video signals, and digital information signals to which identification information has been added by the identification information adding means. Multiplexing means for multiplexing each of the single bit strings into a single bit string, and each of the plurality of single bit strings obtained by multiplexing the digital information signal by the second multiplexing means into a plurality of frequency channels on a transmission path. A transmitting device having a transmitting means for allocating and transmitting each of them; and a transmitting device for allocating to any one of a plurality of frequency channels transmitted from the transmitting device. From a single bit string is devoted, with the separation of one of the digital video signal,
Separation means for separating the digital information signal multiplexed with the single bit string, and priority storage means for storing, for each type of the identification information, a priority set in advance according to the identification information And whether or not the digital information signal should be reproduced based on the priority stored in the priority storage according to the identification information added to the digital information signal separated by the separating means. Determination means, a first reproduction means for reproducing and displaying the digital video signal separated by the separation means as a video, and the separation means, when the determination means determines that it should be reproduced, And a second reproducing means for reproducing the separated digital information signal into characters and mixing the reproduced characters with the image displayed by the first reproducing means. It provides a signal transmission system.

In any of the digital signal transmission systems, the transmitting device may further include a creating unit for creating the digital information signal.

[0034] In this specification, the term "character" includes not only symbols but also graphic characters.

[0035]

In the transmitting apparatus, the priority information adding means adds N levels of priority information to a digital information signal representing a character. The digital information signal to which the priority information is added is multiplexed by the second multiplexing means into each of the plurality of single bit strings created by the first multiplexing means. Then, the transmitting means allocates each of the plurality of single bit strings obtained by multiplexing the digital information signal by the second multiplexing means to a plurality of frequency channels on a transmission path and transmits them.

On the other hand, in the receiving apparatus, the separating means selects one of the single bit strings transmitted from the transmitting apparatus to be assigned to any one of the plurality of frequency channels and transmitted. A digital video signal is separated, and a digital information signal multiplexed with the single bit string is separated. The determining means determines whether or not the digital information signal should be reproduced based on the priority information added to the digital information signal separated by the separating means.

The first reproducing means reproduces the digital video signal separated by the separating means into a video and displays it. At this time, the second reproducing means should reproduce the digital video signal by the judging means. If it is determined that the digital information signal is a digital information signal, the digital information signal separated by the separating means is reproduced as a character, and the reproduced character is mixed with the video displayed by the first reproducing means.

Therefore, in a digital signal transmission system that performs multi-channel services such as VOD and NVOD, the video signal to be transmitted from the transmitting device to the receiving device is a digital video signal that has already been compressed and coded with high efficiency. According to the present invention, characters such as emergency information can be displayed together with a video on a receiving device without the transmitting device decompressing and decoding the digital video signal once.

[0039]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described.

FIG. 1 is a block diagram showing a configuration of a transmission device in the digital signal transmission system according to the first embodiment.

In FIG. 1, reference numerals 101 to 103 designate Ks for inputting compressed digital video signals (hereinafter, referred to as video streams) obtained from K different video sources.
The video stream input terminals 104 to 106 are K audio stream input terminals for inputting compressed digital audio signals (hereinafter referred to as audio streams) obtained from different K audio sources.

Reference numeral 107 denotes an information stream creation device for creating a digital information signal (hereinafter, referred to as an information stream) representing characters for displaying emergency information in characters. The information stream creation device 107 includes an information creation device 108 for creating a digital information signal representing characters for displaying characters of emergency information, and a priority information addition device for adding priority information to the digital information signal created by the information creation device 108. 109 are provided.

Reference numeral 110 denotes K video streams input from the video stream input terminals 101 to 103;
K audio streams input from audio stream input terminals 104 to 106, information stream creation device 107
Is a multiplexing apparatus that multiplexes the information stream generated by the multiplexing method to generate a single bit stream (hereinafter, referred to as a single bit stream). The multiplexer 110 includes K video streams and audio stream input terminals 104 to 106 input from the video stream input terminals 101 to 103.
A program number adding device 114 for adding a program number to each of the K audio streams input from the MV and the information stream created by the information stream creating device 107; M program multiplexing devices 115-1 for multiplexing streams and information streams to create a single bit stream
17 are provided.

Also, 111-113 are multiplexing devices 11
Numeral 0 denotes M bit stream output terminals for outputting the created single bit stream. Each of the single bit streams output from the M bit stream output terminals 111 to 113 is transmitted from the transmitting device to the receiving device through a multi-channel digital downlink band including M channels.

Here, in order to explain the operation of the transmitting apparatus, K video stream and audio stream input terminals 1 input from video stream input terminals 101 to 103 are described.
The manner in which the K audio streams input from 04 to 106 and the information stream created by the information stream creation device 107 become M multiplexed single bit streams will be described with reference to FIG. .

In FIG. 7A, reference numerals 701 to 704 denote Ks input from the video stream input terminals 101 to 103.
Video streams 705 to 708 are K audio streams input from the audio stream input terminals 104 to 106.

Reference numeral 709 denotes the information stream creation device 1
Reference numeral 07 denotes the created information stream. In the information stream 709, the priority information adding device 108 has already
Priority information 721 is added.

Also, in FIG.
3 is a K video stream to which the program number adding device 114 has added the program number 719; 714 to 717 are K audio streams to which the program number adding device 114 has added the program number 719; This is an information stream to which a program number 720 is added.

In the example shown in FIG.
1 and the audio stream 705 are streams constituting the same program “Program 1”, and similarly, the video stream 704 and the audio stream 708 are streams constituting the same program “Program K”. It is assumed. Therefore, K video streams 710 to 710
713 are sequentially assigned “1” to “K” as program numbers 719, and K audio streams 714 to 717 are sequentially assigned “1” to “K” as program numbers 719. . The information stream 718 includes “X”
Is added as a program number 720.

In FIG. 7C, reference numeral 722 denotes a single bit stream multiplexed by the program multiplexer 115 and output from the bit stream output terminal 111, and 723 denotes a single bit stream multiplexed by the program multiplexer 117. This is a single bit stream output from the bit stream output terminal 113.

In the example shown in FIG. 7, the streams constituting “Program 1” and “Program 2” are “Channel 1 (CH
1) "and transmitted. Similarly," program K-
It is assumed that streams constituting "1" and "program K" are allocated to "channel M (CHM)" and transmitted. Therefore, the single bit stream 722 is composed of the video streams 710 and 711 and the audio stream 71.
4, 715 and the information stream 718 are multiplexed, and the single bit stream 723 is composed of the video streams 712, 713 and the audio stream 71.
6, 717 and the information stream 718 are multiplexed.

Returning to FIG. 1, in the information stream creating device 107, the information creating device 108 creates a digital information signal representing characters for displaying the emergency information in characters, and the priority information adding device 109 Since the priority information to be added to the digital information signal is created and the created priority information is added to the digital information signal, the information stream 709 shown in FIG. 7 is created.

Note that the priority information is N-stage (N is a positive number) information for the receiving apparatus to determine whether or not the character represented by the information stream is to be forcibly displayed.
"1" to "5" such that the priority information has a value that increases as the importance of the content of the character represented by the information stream increases.
The description will be made assuming that the information has five levels.

The information stream 709 created by the information stream creation device 107 is input to the video stream input terminal 10.
K video streams 701 input from 1 to 103
, 704 and K audio streams 705 to 708 input from the audio stream input terminals 104 to 106 are input to the program number adding device 114.

In the program number adding device 114, the input video streams 701 to 704 and the audio stream 7
05 to 708 and the information stream 709, a program number is added to each of the video streams 710 to 7 shown in FIG.
13, an audio stream 714 to 717, and an information stream 718.

The video streams 710 to 713 and the audio streams 7 to which the program number adding device 114 has added the program numbers
14 to 717 and the information stream 718 are multiplexed by the program multiplexers 115 to 117 to become single bit streams 722 and 723 shown in FIG.

Although FIG. 7 shows that the K video streams and the K audio streams respectively constitute the K programs, the program composed of only the audio streams is described. Alternatively, a program composed of only a video stream can be permitted. In this case, the number of video streams and the number of audio streams are not always equal.

FIG. 2 is a block diagram showing a configuration of a receiving apparatus in the digital signal transmission system according to the first embodiment.

In FIG. 2, reference numeral 201 denotes a bit stream input terminal for inputting a single bit stream assigned to any one of the M channels, and 202 denotes a bit stream input terminal 201 A separation device for separating a desired video stream and an audio stream and an information stream from a single bit stream; 203, a system decoder for extracting a program number and priority information from the information stream separated by the separation device 203; System decoder 203
Is a determination device for determining the extracted priority information.

An audio decoder 205 converts the audio stream separated by the separation device 203 into an analog audio signal, a video decoder 206 converts the video stream separated by the separation device 203 into an analog video signal,
An information decoder 208 converts an information stream separated by the separation device 203 into an analog information signal, and an information decoder 208 converts the analog video signal converted by the video decoder 206 into an analog video signal.
A mixing device for mixing the converted analog information signals;
An audio output terminal 209 outputs an analog audio signal converted by the audio decoder 205, and a video output terminal 210 outputs an analog video signal obtained by mixing the analog information signal by the mixing device 208.

Here, in order to explain the operation of the receiving apparatus, a state until a single bit stream input from the bit stream input terminal 201 is separated into a video stream, an audio stream, and an information stream will be described.
This will be described with reference to FIG.

In FIG. 8A, reference numeral 801 denotes a single bit stream input from the bit stream input terminal 201.

In FIG. 8B, reference numeral 802 denotes a video stream separated from the single bit stream 801, 803 denotes an audio stream separated from the single bit stream 801, and 804 denotes a single bit stream 80.
1 is an information stream separated from 1.

A single bit stream input from the bit stream input terminal 201 to the separation device 202 is a channel selected by a tuner (not shown) among the M channels received by the reception device. , And the single bit stream has already been subjected to predetermined signal processing by a digital demodulator or the like (not shown).

In the example shown in FIG. 8, the tuner is "CH
1 "has been selected. Therefore, the single bit stream 801 is composed of the video streams 710 and 711 and the audio streams 714 and 71 shown in FIG.
5 and the information stream 718 are multiplexed.

Returning to FIG. 2, first, the system decoder 203 extracts priority information and all program numbers from the single bit stream input from the bit stream input terminal 201 to the demultiplexer 202.

The determination device 204 is provided for the system decoder 20
3 determines whether it is necessary to display the character represented by the information stream multiplexed into the single bit stream input to the demultiplexer 202 from the bit stream input terminal 201 based on the extracted priority information. .

By the way, in the receiving device, the stage of the priority information for displaying the character represented by the information stream is input to the determining device 204 by an external operation. Here, it is assumed that “3” has been input.

Then, the judgment device 204 compares the stage (“3”) inputted by an external operation with the stage of the priority information extracted by the system decoder 203, and if the latter is smaller than the former, the bit Stream input terminal 2
It is determined that it is not necessary to forcibly display the character represented by the information stream multiplexed on the single bit stream input to the separation device 202 from 01. When the former is equal to the latter or the latter is larger than the former, it is determined that the forcible display is necessary.

As a result, the receiving apparatus can forcibly display only the urgent information of the degree of importance required by the subscribing household in which the receiving apparatus is installed, in characters.

When the determining device 204 determines that the forced display is necessary, the information decoder 20 determines that it is necessary.
Notify 7.

On the other hand, in the receiving apparatus, the program number of the program to be converted into the analog video signal and the analog audio signal and the channel number of the channel to which the program is assigned are input to the tuner by an external operation. The tuner notifies the system decoder 203 of the input program number.

The system decoder 203 notifies the separating device 202 of the program number so that the separating device 202 separates the video stream, the audio stream, and the information stream constituting the program of the program number.
Control.

Therefore, the separating device 202 outputs a video stream and audio stream to which a program number corresponding to the program number notified from the system decoder 203 is added from the single bit stream input from the bit stream input terminal 201. The stream and the information stream multiplexed into the single bit stream are separated.

In the example shown in FIG. 8, since the program number input by an external operation is “program 1”, the stream separated by the separation device 202 constitutes “program 1”. Video stream 802 and audio stream 803, and information stream 804
Becomes

The video stream separated by the separating device 202 is converted by a video decoder 206 into an analog video signal. Also, the information stream separated by the separation device 202 is converted into an analog information signal by the information decoder 207 only when the determination device 204 notifies that the forced display is necessary, and the converted analog information signal is , The mixer 208, the video decoder 20
6 is mixed with the converted analog video signal and output from the video output terminal 210 as an analog video signal. The audio stream separated by the separation device 202 is converted into an analog audio signal by the audio decoder 205 and output from the audio output terminal 209.

As described above, according to the present embodiment, when an emergency such as a natural disaster or an incident occurs, the transmitting apparatus transmits, to each channel, an information stream representing characters for displaying emergency information in characters. Since the video stream and the audio stream to be allocated and transmitted are multiplexed, the transmitting apparatus can perform high-efficiency compression / coding on the receiving apparatus receiving the bidirectional service using the multi-channel digital downlink. The information stream can be transmitted without expanding and decoding the converted digital video signal and digital audio signal (video stream and audio stream) once.

Further, even if the receiving apparatus receives the interactive service using the multi-channel digital system downstream band, it is added to the information stream transmitted from the transmitting apparatus and representing the characters for displaying the characters of the emergency information. It is possible to determine whether or not it is necessary to forcibly display the character represented by the information stream on the basis of the priority information that has been received. Emergency information can be forcibly displayed in characters.

Next, a second embodiment of the present invention will be described.

The block diagram showing the configuration of the transmitting device in the digital signal transmission system according to the second embodiment is the same as FIG. Further, the block diagram showing the configuration of the receiving device in the digital signal transmission system of the second embodiment is shown in FIG.
It is the same as FIG.

In the first embodiment, the priority information is five-level information "1" to "5" such that the value increases as the importance of the content of the character represented by the information stream increases. In the present embodiment, the priority information is, in particular, an example in which the priority information is two-stage information of “ON / OFF” indicating whether or not the character represented by the information stream is forcibly displayed. explain.

That is, in this embodiment, in the information stream creation device 107, the priority information addition device 109
When it is desired to forcibly display the character represented by the digital information signal created by the information creating device 108 on the receiving device, "ON" indicating that forced display is necessary is added to the digital information signal as priority information. To do.

In such a case, the operation of the determining device 204 in the receiving device is different from that of the first embodiment. Hereinafter, the operation of the determining device 204 when the priority information is two-stage information will be described. I do.

In the receiving device, information indicating whether or not it is necessary to display the character represented by the information stream is input to the determining device 204 by an external operation.

[0086] Therefore, when the information input by an external operation indicates that it is necessary to display the information, the determining device 204 determines whether the priority information extracted by the system decoder 203 is "ON" or not. Even if it is "OFF", it is determined that it is necessary to forcibly display. If the information input by an external operation indicates that there is no need to display, if the priority information extracted by the system decoder 203 is “OFF”, it is determined that the forced display is not necessary. If it is "ON", it is determined that the forcible display is not necessary.

Thus, even if the subscribing household in which the receiving device is installed does not need extra character display,
Special emergency information such as a major earthquake or a major incident can be forcibly displayed in characters on the receiving device.

As described above, according to the present embodiment, when an emergency such as a natural disaster or an incident occurs, the transmitting apparatus transmits an information stream representing characters for displaying emergency information in characters to each channel. Since the video stream and the audio stream to be allocated and transmitted are multiplexed, the transmitting apparatus can perform high-efficiency compression / coding on the receiving apparatus receiving the bidirectional service using the multi-channel digital downlink. The information stream can be transmitted without expanding and decoding the converted digital video signal and digital audio signal (video stream and audio stream) once.

Also, in the receiving apparatus, even if the receiving apparatus receives the interactive service using the multi-channel digital downstream band, it is added to the information stream transmitted from the transmitting apparatus and representing the characters for displaying the characters of the emergency information. Based on the priority information, it is possible to determine whether or not it is necessary to forcibly display the character represented by the information stream. Even when not required, special emergency information can be forcibly displayed in characters.

In the first embodiment and the second embodiment, all of the program multiplexing devices 115 to 117 use the video stream, the audio stream, and the information stream to which the program number adding device 114 has added the program number. In the description, the streams are multiplexed to create a single bit stream. Therefore, since the same information stream is multiplexed on all the channels, the receiving apparatus receiving the interactive service using the multi-channel digital downlink band receives the program assigned to any channel. However, the emergency information can be forcibly displayed in characters.

However, some program multiplexing apparatuses may multiplex only the video stream and the audio stream and do not multiplex the information stream.
That is, the same information stream may not be multiplexed on all channels.

Next, a third embodiment of the present invention will be described.

FIG. 9 is a block diagram showing a configuration of a transmission device in the digital signal transmission system according to the third embodiment.

In FIG. 9, reference numeral 901 denotes an identification information adding device, and other blocks are the same as those in FIG.

In this embodiment, the transmitting device adds identification information indicating the content of the character represented by the information stream to the information stream, and the receiving device performs the processing based on the identification information added to the information stream. Thus, it is determined whether the character represented by the information stream is forcibly displayed.

FIG. 10 shows an example of the identification information.

The identification information is classified into a major category 1101, a middle category 11
In the example shown in FIG. 10, “disaster” and “election” are prepared as the major classification 1101, and the major classification 1101 indicating “disaster” is provided.
“Earthquake” and “typhoon” are prepared as the middle class 1102 corresponding to
And the sub-category 1003 corresponding to the sub-category 1102 indicating “typhoon”, respectively, as areas where an “earthquake” or “typhoon” occurs or occurs
"Kyushu") is prepared.

FIG. 11 shows an example of an information stream to which identification information has been added.

In FIG. 11, reference numerals 1101, 1102, 1
103 corresponds to a major category 1001, a middle category 1002, and a minor category 1003, respectively, and the others are the same as the information stream 718 shown in FIG.

In the example of FIG. 11, the content of the information stream 718 indicates that "there is an earthquake among disasters in the Kanto region".

Returning to FIG. 9, in the information stream creating device 107, the information creating device 108 creates a digital information signal representing characters for displaying characters of the emergency information, and the identification information adding device 901 creates the digital information signal. Since the identification information indicating the contents of the digital information signal is created and the created identification information is added to the digital information signal, the program number 72 in the information stream 718 shown in FIG.
Parts other than 0 are created.

FIG. 12 is a block diagram showing a configuration of a receiving apparatus in the digital signal transmission system according to the third embodiment.

In FIG. 12, reference numeral 1201 denotes a priority order setting device, 1202 denotes a user input terminal, and other blocks are the same as those in FIG.

The priority order setting device 1201 determines, for each type of all identification information added to the information stream, a priority indicating whether or not the character represented by the information stream to which the identification information is added is forcibly displayed. The order is set in advance based on the content input from the user input terminal 1202 operated externally. In the present embodiment, the priority set by the priority setting device 1201 is a two-stage order of “ON” / “OFF” indicating whether or not the character represented by the information stream is forcibly displayed. There is.

FIG. 13 shows an example of two levels of priorities.

In FIG. 13, 1301 and 1302 are:
"Disaster" and "election" in the major category 1001 respectively
1303 and 1304 are the priorities of “earthquake” and “typhoon” in the middle category 1002, respectively, and 1305 are the priorities of each area in the small category 1003, respectively.

In the example shown in FIG. 13, the priority of “disaster” in the major category 1001 is “ON”,
The priority of “election” is “OFF”. Also,
The priority of “earthquake” in middle category 1102 is “ON”
And "typhoon" is "OFF". In addition, “Kanto” in the small classification 1103 is “ON”, and the other areas are “OFF”. That is, a portion corresponding to the large classification 1101 indicates “disaster”, a portion corresponding to the middle classification 1102 indicates “earthquake”,
Only for the information stream to which the identification information indicating that the portion corresponding to the minor classification 1103 indicates "Kanto" is assigned a priority order such that the character represented by the information stream is forcibly displayed.

Returning to FIG. 12, the system decoder 203 first extracts identification information and all program numbers from a single bit stream input from the bit stream input terminal 201 to the separation device 202.

The identification information extracted by the system decoder 203 is judged by the judging device 204 whether or not forced display is necessary. If it is judged that forced display is necessary, the information decoder informs the information decoder. 207 is notified.
More specifically, the determination device 204
When the priority set in advance by the priority setting device 1201 is "ON" for all of the large classification, the middle classification, and the small classification among the identification information extracted by the "?", The forced display is required. Is determined.

For example, when the priorities shown in FIG. 13 are set in advance, the determining device 204 forcibly deletes the character represented by the information stream shown in FIG. 11 only when the receiving device receives the information stream shown in FIG. If it is determined that the information stream needs to be displayed, and the receiving device receives another information stream, it is determined that the character represented by the information stream does not need to be forcibly displayed. Therefore, in the receiving apparatus, only the content indicating that "there was an earthquake in the Kanto region in the disaster" was forcedly displayed as emergency information.

As described above, according to the present embodiment, when an emergency such as a natural disaster or an incident occurs, the transmitting apparatus transmits an information stream representing characters for displaying emergency information to each channel. Since the video stream and the audio stream to be allocated and transmitted are multiplexed, the transmitting apparatus can perform high-efficiency compression / coding on the receiving apparatus receiving the bidirectional service using the multi-channel digital downlink. The information stream can be transmitted without expanding and decoding the converted digital video signal and digital audio signal (video stream and audio stream) once.

Further, in the receiving device, even if the interactive device receives the interactive service using the multi-channel digital downstream band, it is added to the information stream transmitted from the transmitting device and representing the characters for displaying the characters of the emergency information. It is possible to determine whether or not it is necessary to forcibly display the character represented by the information stream based on the identification information that has been received, so that the emergency information required by the subscribing household in which the receiving device is installed is required. Can be forcibly displayed.

Further, in the receiving apparatus, each type of all identification information added to the information stream is used as a criterion for determining whether the character represented by the information stream needs to be forcibly displayed. Since the priorities are set in advance, it is possible to change the content of the urgent information to be forcibly displayed in characters for each receiving device.

By combining any one of the first and second embodiments with the third embodiment, the transmitting device adds both priority information and identification information to the digital information signal. The receiving device may determine whether to display the character represented by the digital information signal based on both the priority information and the identification information added to the digital information signal.

For example, when the first embodiment and the third embodiment are combined, a block diagram showing the configuration of the transmitting apparatus is as shown in FIG. 14, where priority information and identification information are added. An example of the information stream thus obtained is as shown in FIG.

In this way, even for emergency information that is not required by the subscribing household that has set the receiving device, special emergency information such as a large earthquake or a large incident is forcibly sent to the receiving device. Can be displayed.

Next, a fourth embodiment of the present invention will be described.

The block diagram showing the configuration of the transmitting device in the digital signal transmission system of the fourth embodiment is the same as that of FIG.

FIG. 16 is a block diagram showing the configuration of a receiving apparatus in the digital signal transmission system according to the fourth embodiment.

In FIG. 16, reference numeral 1601 denotes an analog audio signal converted by the information decoder 206.
A mixing device 5 for mixing the converted analog audio signal with 1;
Reference numeral 602 denotes an information decoder, and other blocks are the same as those in FIG.

In this embodiment, the information stream includes a digital audio signal representing a voice for notifying the start of character display of emergency information before a digital information signal representing a character for displaying emergency information in characters. I have to be.

In FIG. 16, information decoder 1602
Converts an information stream containing a digital audio signal from a digital information signal portion into an analog information signal and converts a digital audio signal portion into an analog audio signal. The analog information signal converted by the information decoder 1602 is mixed by the mixing device 208 with the video decoder 20.
6 is mixed with the converted analog video signal and output from the video output terminal 210 as an analog video signal. The analog audio signal converted by the information decoder 1602 is mixed by the mixing device 1601 with the analog audio signal converted by the audio decoder 205 and output from the audio output terminal 209 as an analog audio signal.

As described above, according to the present embodiment, when the receiving apparatus receives the information stream including the digital audio signal indicating the audio for notifying the start of the character display of the emergency information, the emergency information is transmitted. In addition to forcibly displaying characters, a sound such as a dial tone for notifying the start of character display of emergency information can be output.

Further, according to the configuration of the receiving apparatus of the present embodiment, even if all of the information streams are digital audio signals representing audio for outputting emergency information as audio,
The digital audio signal can be converted to an analog audio signal by an information decoder.

In this embodiment, the configuration of the receiving apparatus is configured to receive the information stream to which the priority information described in the first embodiment and the second embodiment is added. In the case of receiving the information stream to which the identification information described in the third embodiment is added, the configuration of the receiving apparatus is as shown in FIG.

[0126]

As described above, according to the present invention,
When performing a multi-channel service such as VOD, NVOD, etc., the receiving side does not need to decompress and decode the digital video signal, which has already been compressed and encoded at high efficiency, to be transmitted to the receiving side once. And characters such as emergency information can be displayed together with the video.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a transmission device in a digital signal transmission system according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a receiving device in the digital signal transmission system according to the first embodiment.

FIG. 3 is an explanatory diagram showing an example of a frequency array in a CATV interactive video service.

FIG. 4 is a block diagram showing a configuration of a conventional video multiplex transmission system.

FIG. 5 is a block diagram showing a configuration of a character signal processing device for realizing a known example.

FIG. 6 is an explanatory diagram showing an example of a display screen of a television receiver in a known example.

FIG. 7 is an explanatory diagram showing a state of each stream in the transmission device of the first embodiment.

FIG. 8 is an explanatory diagram showing the state of each stream in the receiving device of the first embodiment.

FIG. 9 is a diagram illustrating a configuration of a transmission device in a digital signal transmission system according to a third embodiment.

FIG. 10 is an explanatory diagram showing an example of identification information in a third embodiment.

FIG. 11 is an explanatory diagram showing an example of an information stream in the third embodiment.

FIG. 12 is a block diagram showing a configuration of a receiving device in the digital signal transmission system according to the third embodiment.

FIG. 13 is an explanatory diagram showing an example of priorities of identification information in the third embodiment.

FIG. 14 is a block diagram showing a configuration of a transmission apparatus when the first embodiment and the third embodiment are combined.

FIG. 15 is an explanatory diagram showing an example of an information stream when the first embodiment and the third embodiment are combined.

FIG. 16 is a block diagram showing a configuration of a receiving device in the digital signal transmission system according to the fourth embodiment.

FIG. 17 is a block diagram showing another configuration of the receiving device in the digital signal transmission system according to the fourth embodiment.

[Explanation of symbols]

101 to 103: video stream input terminals, 104 to 1
06: audio stream input terminal, 107: information stream generating device, 108: information generating device, 109: priority information adding device, 110: multiplexing device, 111 to 113: bit stream output terminal, 114: program number adding device, 1
15 to 117: program multiplexing device, 201: bit stream input terminal, 202: separating device, 203: system decoder, 204: determining device, 205: audio decoder, 2
06 Video decoder, 207 Information decoder, 208
Mixing device, 209: audio output terminal, 210: video output terminal, 301: digital upstream band, 302: analog downstream band, 303: digital downstream band, 401 ...
Video server, 402: multiplexer, 403: channel coding device, 404: digital modulator, 405:
RF converter, 406 frequency multiplexing device, 407 receiver, 408 monitor, 409 tuner, 410 digital demodulator, 411 waveform equalizer, 412 channel decoding device, 413 demultiplexer, 414
... Digital video decompression device, 415 ... Transmission cable, 5
01: television camera unit; 502, 503: output terminal; 504: character signal generation circuit; 505: mixing circuit;
06 Start signal generation circuit, 507 Variable gate pulse circuit, 508 Gate circuit, 901 Identification information adding device, 1201 Priority setting device, 1202 User input terminal, 1601 Mixing device, 1602 Information decoder.

[Procedure amendment]

[Submission date] February 25, 2000 (200.2.2
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

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[0027]

SUMMARY OF THE INVENTION A plurality of compressed images representing an image are provided.
Single bit string with multiplexed digital video signals
To each of multiple frequency channels on the transmission path
Characters on digital signal transmitters
Digital information signal which is a digital signal
Priority information adding means for adding (N is a positive number) priority information
And the digit to which the priority information adding means has added the priority information.
Multiplexing the digital information signal into each of the single bit strings
Digital signal having multiplexing means
Provides a transmitting device .

[Procedure amendment 3]

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[0035]

In the transmitting apparatus, the priority information adding means adds N levels of priority information to a digital information signal representing a character. Digital information signal the priority information is added, the upper Kio duplex unit, are multiplexed into each of the single bit sequence.

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──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/173 610 (72) Inventor Keiro Shinkawa 292 Yoshidacho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Inside the Video Media Research Laboratory (72) Inventor Tsutomu Noda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Video Media Research Laboratory Hitachi Ltd. (72) Toshio Nagashima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Kenji Katsumata 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd. Inside Hitachi, Ltd. Visual Media Research Laboratories

Claims (11)

[Claims] A priority information adding means for adding priority information of N stages (N is a positive number) to a digital information signal which is a digital signal representing a character, and a plurality of compressed digital video signals representing a video are multiplexed. First multiplexing means for creating a plurality of multiplexed single bit strings, and a digital information signal to which the priority information adding means has added priority information is respectively converted into a plurality of single bit strings created by the first multiplexing means. Multiplexing means for multiplexing the digital information signal, and assigning each of the plurality of single bit strings obtained by multiplexing the digital information signal to each of a plurality of frequency channels on the transmission path, and transmitting the multiplexed signal. A transmitting device having transmitting means, and a single bit string assigned to any one of the plurality of frequency channels transmitted from the transmitting device, Separating means for separating any digital video signal and a digital information signal multiplexed with the single bit string, based on priority information added to the separated digital information signal by the separating means; Determining means for determining whether or not the digital information signal should be reproduced; first reproducing means for reproducing and displaying the digital video signal separated by the separating means on a video; A second reproducing means for reproducing the digital information signal separated by the separating means into characters when it is determined to be necessary, and mixing the reproduced characters with the video displayed by the first reproducing means; A digital signal transmission system comprising a receiving device. 2. The digital signal transmission system according to claim 1, wherein the priority information is N-level priority information whose value increases as the importance increases, and the reception device is set in advance. Setting means for storing a set value M (M is a positive number, M ≦ N), wherein the determining means stores priority information added to the digital information signal separated by the separating means. If the step is smaller than the set value M stored in the set value storage means, it is determined that the digital information signal should not be reproduced, and the separating means determines the priority information added to the separated digital information signal. A digital signal transmission system characterized in that it is determined that the digital information signal should be reproduced when the step is equal to or greater than the set value M stored in the set value storage means. 3. The digital signal transmission system according to claim 1, wherein said priority information is two-stage priority information indicating whether or not to perform forced display. A reproduction presence / absence information storage unit that stores information indicating whether or not the information signal needs to be reproduced, wherein the determination unit needs to reproduce the digital information signal by the reproduction presence / absence information storage unit If the information indicating that the digital information signal is to be reproduced is determined, regardless of the level of the priority information added to the separated digital information signal by the separation means, When the presence / absence information storage means stores information indicating that the digital information signal does not need to be reproduced, the presence / absence information is added to the separated digital information signal by the separation means. If the stage of the previous information indicates the fact that the forced display,
If it is determined that the digital information signal should be reproduced, and if the stage of the priority information added to the separated digital information signal by the separating means does not indicate that the forced display is to be performed, the digital information signal is output. A digital signal transmission system, which determines that reproduction should not be performed. 4. The digital signal transmission system according to claim 1, wherein said transmitting device adds identification information indicating the contents of a character represented by said digital information signal to said digital information signal. The receiving device further comprises priority order storing means for storing, for each type of the identification information, a priority order set in advance in accordance with the identification information, Priority information added to the digital information signal separated by the separating means, and priority information stored in the priority order storing means in accordance with identification information added to the digital information signal separated by the separating means. A digital signal transmission system, which determines whether or not the digital information signal should be reproduced based on the order. 5. An identification information adding means for adding identification information indicating the contents of a character represented by the digital information signal to a digital information signal which is a digital signal representing a character, and a plurality of compressed digital video signals representing an image. First multiplexing means for creating a plurality of single bit strings obtained by multiplexing the digital information signal, and the digital information signal added with the identification information by the identification information adding means is converted into a plurality of single bit strings created by the first multiplexing means. And multiplexing the digital information signal by the second multiplexing means, and assigning each of the plurality of single bit strings to each of the plurality of frequency channels on the transmission path. A transmitting device having transmitting means for transmitting, and a frequency channel assigned to any one of a plurality of frequency channels transmitted from the transmitting device. Separating means for separating any digital video signal from the single bit string and separating the digital information signal multiplexed with the single bit string; and for each type of the identification information, Priority storage means for storing a priority set in advance according to
In accordance with the identification information added to the digital information signal separated by the separation means, it is determined whether or not the digital information signal should be reproduced based on the priority stored in the priority storage means. Determining means, a first reproducing means for reproducing and displaying the digital video signal separated by the separating means as a video, and the separating means separates when the determining means determines that it should be reproduced. The digital information signal is reproduced into characters, and the reproduced characters are referred to as the first characters.
And a second reproducing means for mixing the image displayed by the reproducing means with the second reproducing means. 6. The digital signal transmission system according to claim 1, wherein said transmission device further comprises a creating means for creating said digital information signal. 7. The digital signal transmission system according to claim 1, wherein said digital information signal includes a digital audio signal representing audio, and said first multiplexing means includes a plurality of digital video signals. And a plurality of single bit strings obtained by multiplexing a plurality of digital voice signals representing voices, wherein the demultiplexing means allocates to any one of a plurality of frequency channels transmitted from the transmitting device. Separating any one of the digital video signal and the digital audio signal from the single bit stream, and separating the digital information signal multiplexed with the single bit stream; A third reproducing means for reproducing and outputting the separated digital audio signal to sound, And a fourth reproducing unit that reproduces the digital audio signal separated by the separating unit into a sound when it is determined that the separated sound is mixed with the sound output by the third reproducing unit. Characteristic digital signal transmission system. 8. A digital signal transmitting apparatus for allocating a single bit string in which a plurality of compressed digital video signals representing a video are multiplexed to each of a plurality of frequency channels on a transmission path and transmitting the same. A priority information adding means for adding priority information of N stages (N is a positive number) to the digital information signal as a signal; a digital information signal to which the priority information adding means adds the priority information; And a multiplexing means for multiplexing the digital signal. 9. A digital video signal representing an image is separated from a single bit string transmitted by being allocated to any one of a plurality of frequency channels on a transmission path. In the digital signal receiving apparatus for reproducing and displaying an image, a digital information signal which is a digital signal representing a character and to which priority information of N stages (N is a positive number) is added is added to the single bit string. A separating means for separating the multiplexed digital information signal from the multiplexed single bit sequence in which the separated digital signal is multiplexed, and a digital information signal separated by the separating means. Determining means for determining whether or not to reproduce the digital information signal based on the priority information; and determining that the digital information signal should be reproduced. If the, reproduced digital information signal in which the separating means to separate a character, a digital signal receiving apparatus characterized by having a second playback means for mixing the characters reproduced video to be displayed in the reproduction. 10. A digital signal transmitting apparatus for transmitting a single bit string in which a plurality of compressed digital video signals representing a video are multiplexed and assigned to each of a plurality of frequency channels on a transmission path. Identification information adding means for adding identification information indicating the content of the character represented by the digital information signal to the digital information signal being a signal; and the digital information signal to which the identification information adding means has added the identification information is converted into the single bit string. And a multiplexing means for multiplexing each of the signals. 11. A digital video signal representing an image is separated from a single bit string transmitted by being assigned to any one of a plurality of frequency channels on a transmission path. In the digital signal receiving apparatus for reproducing and displaying an image, each of the single bit strings is added with identification information indicating the content of the character represented by the digital information signal to the digital information signal which is a digital signal representing a character. Separating means for separating the multiplexed digital information signal from a single bit string in which the separated digital signal has been multiplexed; and identifying means for each type of the identification information. Priority order storage means for storing a priority order set in advance according to information; and a digital information signal separated by the separation means. Determining means for determining whether or not the digital information signal is to be reproduced, based on the priority stored in the priority storing means in accordance with the identification information which has been set; And a second reproducing means for reproducing the digital information signal separated by the separating means into a character when it is determined to be necessary, and mixing the reproduced character with the video to be reproduced and displayed. Digital signal receiver.