KR19980020289A - Subtitle Signal Format of Viewer Selective Subtitle Broadcasting - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caption signal format of a viewer-selective caption broadcasting, and more particularly to a caption signal format of a viewer-selective caption broadcasting in which a caption signal is transmitted on one scanning line of every field of a television signal. In a caption signal format of a viewer-selective closed caption broadcasting in which a caption signal is carried on a scanning line, the caption signal maintains a level of at least 50 ± 5 IRE to 90 ± 5 IRE, and divides the color subcarrier of the television signal by 4 divisions. A bit clock synchronization signal comprising a sinusoidal signal of 6 to 7 cycles having a frequency; A word start signal of a sine wave of one cycle having a frequency divided by the bit clock synchronization signal; And a digitally modulated data signal composed of at least 16 bits and 18 bits or less.

Therefore, in the present invention, the frequency of the color carrier is divided to form a caption signal, thereby facilitating phase synchronization, thereby reducing the cost of the receiver.

Description

Subtitle Signal Format of Viewer Selective Subtitle Broadcasting

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caption signal format of closed caption broadcasting. In particular, when a character and a control code are transmitted on a television signal, the reception apparatus receives the caption signal and displays the caption according to the viewer's selection. It is about.

The closed captioning method in television broadcasting includes an open caption method for superimposing news or notifications by the broadcaster's selection without supervising the viewer by superimposing a caption signal on the active section of the television signal, and a non-active section of the television signal. In other words, when a caption signal is transmitted in a vertical blanking section, there is a closed caption method in which a television screen and dialogue contents can be viewed as captions by a viewer's selection.

Closed captioning closed captioning has been implemented since 1978 in the United States for the hearing-impaired without the sign language, and is also very useful for foreign language learning.

US Pat. No. 5,294,982, published in March 1994, discloses a closed caption broadcasting method of Roman characters and syllable characters. In particular, the captioning method of Korean is explained in detail. In the invention of the U.S. patent, in order to broadcast Korean in a closed caption method, a Korean character is divided into each phoneme of a consonant, a neutral, and a consonant, and an ASC II code corresponding to each phoneme is transmitted. Korean characters are displayed by mapping, neutral and final.

Since the conventional Korean closed caption method uses at least 2 to 3 bytes to represent a Korean character, the transmission speed and display speed are slow, and the decoding process is required to find the position of one character by combining 3 to 4 bytes in the decoding process. There was a problem that the processing was complicated. The complexity of the decoding process raises the cost of the decoder. This causes a problem of increasing the cost of the decoder, which millions of viewers have to pay in comparison to the encoder that is required only by broadcasting stations.

In addition, simultaneous display of Chinese characters, Korean, Japanese, and English, Russian, and Greek was impossible, and special symbols could not be displayed.

In addition, since the control code is required to display the dialogue information in the middle of displaying the supplementary information and display the supplementary information again, there is no independence between the dialogue information and the supplementary information, and a control system for distinguishing the display mode of the dialogue information is provided. If the display mode control code is not received at the time when the receiver starts to operate, the metabolic information cannot be displayed until the next control code is received.

In addition, the above-mentioned invention was developed based on the television transmission environment of the United States, that is, the geographical environment with a lot of flat land. Therefore, in the geographical environment of Korea where the mountain area is 70% or more, the reception state of the receiver is poor and the quality of the caption display is pointed out. It is becoming.

Disclosure of Invention An object of the present invention is to provide a caption signal format of a viewer-selective caption broadcasting that can effectively perform Korean caption broadcasting in order to solve the problems of the prior art.

In order to achieve the above object, the caption signal format of the present invention is a caption signal format of a viewer-selective caption broadcasting in which a caption signal is carried on one scan line of every field of a television signal and transmitted. In a caption signal format of a viewer-selective caption broadcasting in which a signal is carried and transmitted, the caption signal maintains a level of at least 50 ± 5 IRE to 90 ± 5 IRE, and divides the frequency division of the color subcarrier of the television signal into four divisions. A bit clock synchronizing signal comprising a sinusoidal signal having 6 to 7 cycles; A word start signal of a sine wave of one cycle having a frequency divided by the bit clock synchronization signal; And a digitally modulated data signal composed of at least 16 bits and 18 bits or less.

1 is a block diagram showing the configuration of a television broadcasting system for viewer-selective closed captioning according to the present invention;

Fig. 2 is a block diagram showing the structure of a television receiver for receiving viewer-selective closed captioning according to the present invention.

3 is a signal diagram showing the configuration of a caption signal according to the present invention;

4 is a diagram showing a data packet structure of 18-bit caption data according to the present invention;

5 is a diagram showing a data packet structure of 16-bit caption data according to the present invention;

6 is a diagram showing a data packet structure of 17-bit caption data according to the present invention;

Hereinafter, with reference to the accompanying drawings will be described in more detail the present invention.

1 shows a configuration of a television broadcasting apparatus having a viewer-selective caption broadcasting function. The audio signal input through the microphone 10 is mixed and amplified by the voice signal processor 30 and transmitted to the television signal modulator 50. The video signal input through the video camera 20 is amplified and edited by the video signal processor 40 and transmitted to the television signal modulator 50. The television signal modulator 50 modulates the transmitted audio signal by FM, modulates the video signal by AM-modulation of the residual side wave method, and frequency-multiplexes and shifts the AM modulated signal and the FM modulated signal. The high frequency output unit 60 amplifies a high frequency signal and transmits a television signal to the air through an antenna.

In the subtitle encoding unit 70, the text information input unit 71 receives additional information such as dialogue information or urgent news or delivery information related to the television screen. Various control information for subtitle control is input through the control signal input unit 72. The character information input unit 71 includes a keyboard for inputting characters such as Korean, English, Chinese characters, Japanese, and special characters, and outputs the input character information as a two-byte Hangul completion code KSC5901. The control information input unit 72 includes keypads such as a mode selection key and a function selection key and outputs the input control information as a 7-bit binary code.

In the character code generator 73, the MSB of each byte of the input two-byte character code is used as the subtitle / additional information flag.In the case of additional information, the MSB is replaced with '0' and a parity bit is added to each byte. A data packet of a total of 18 bits of character code is generated.

The control code generator 74 divides the input 7-bit binary into the upper 4 bits, lower 3 bits, and adds a parity bit for the upper 4 bits, a control code identification bit for 2 bits, and a dialogue / addition flag to generate an upper byte. A lower byte is generated by adding a first parity bit, a second parity bit, a control code identification bit of two bits, and a subtitle subtitle / additional flag for the lower three bits. A parity bit is added to each generated byte to generate a data packet having a total of 18 bits of control code. Details of the above-described data packet will be described later.

The data packet modulator 75 modulates the data packet generated by the character code generator 73 or the control code generator 74 by a digital modulation method.

The synchronous counter unit 76 inputs the synchronous signal provided from the video signal processing unit 40 and is reset by the vertical synchronous signal and counts the horizontal synchronous signal to select the 262th scan line in the odd field, and the 525th scan line in the even field. You will be counting your choices. The window signal generator 77 inputs the count value of the sync counter 76 to generate a window signal. The window signal is a drive signal for switching the switching means 78 in order to superimpose the caption signal on a predetermined specific line of the video signal output from the video signal processor 40, for example, 262 and 525 scan lines.

2 shows the configuration of a television receiver for receiving viewer-selective closed captioning broadcasting. The tuner 110 demodulates a television signal of a channel selected from the high frequency signals received by the antenna and outputs a voice signal and a video signal. The voice signal is transmitted to the voice signal processor 120 to be equalized and amplified and output as voice through the speaker 130. The video signal is transmitted to the video signal processor 140, processed for luminance and color, and then output as an RGB signal. The RGB signal is transmitted to the display driver 160 through the mixer 150, and the display driver 160 drives the CRT 170 in response to the transmitted RGB signal to display a television screen on the screen.

The caption decoding unit 200 digitally converts the video signal through the A / D converter 210 and transmits the digital signal to the caption processing unit 230. In addition, the sync separator 220 separates the sync signal from the video signal and transmits the vertical and horizontal sync signals to the subtitle processor.

The caption processor 230 generates a clock signal synchronized with the color burst signal of the video signal processor 140 to extract the caption data packet from the digital signal. The extracted data packet is decoded to control caption processing in response to the decoded control code, and the character data is read from the font ROM 240 in response to the decoded character code and stored in the display RAM 250. Character data stored in the display RAM is converted into an RGB signal and transmitted to the mixer 150. The caption processing unit 230 exchanges control data with the system control unit 180 of the set. The system controller 180 transmits a caption-related command input through the command input unit 19 to the caption processing unit 180 and controls the system in response to control data transmitted from the caption processing unit 180.

The detailed configuration of the caption information intended to be used in the caption broadcasting transmission / reception system described above is as follows.

Korea uses M-NTSC TV signal of 525 lines and 60 fields / sec as a broadcast signal, and the vertical blanking period is specified from scan line 10 to scan line 20.

There are no standards set by the Ministry of Information and Communication on the use of signals in the vertical blanking period. For reference, ITU-R Recommendation Rec 473-2 and US FCC Report and Order 83-120.

The caption signal may use any one of the scan lines 10-20 or the odd field or even field or scan line 262 of the vertical blanking period for transmission of the caption data. One or more may be used for increased data transfer or for other purposes. However, full-field data transmission is not considered in closed captioning.

The transmission bit rate of closed caption data should be 447443.125 bps ± 125 bps, and the maximum long-term change rate should be within ± 196 (0.0125 bps). ± 10 Hz), which should be frequency synchronized to the color burst. It is preferable that the color carrier carrier has a continuous phase between the scan line and the scan line. If the phase of the color carrier is discontinuous due to screen editing, etc., at least phase synchronization should be performed on the color burst of the scan line.

In the data modulation method, the one corresponding to the logic value '1' is represented by a sine wave of one period having a phase of 0 degrees and the frequency of fsc / 8 (447.443 kHz), and the phase corresponding to the logic value '0' is 180 degrees. Digital modulation scheme called Binary Phase Shift Keying (BPSK), Non-Return-to-Zero (NRZ), or Phase Reversal Keying (PRK), which is expressed in one cycle of sine wave with frequency fsc / 8 (447.443 kHz). Use The maximum range of phase jitter is ± 10 degrees. The optimal signal waveform will be defined in the future as it may vary depending on the frequency spectrum characteristics of the TV channel. However, due to the fundamental band-limiting frequency, the BPSK waveform may experience severe distortion where logic transitions occur, so that the phase-corrected waveform can be used for broadcasting after passing through a second-order Butterworth filter with a cutoff frequency of 3.5 MHz. Shall be. The impulse response of the Butterworth filter used is

Among inspection items of radio station, number I-7 (TV station), item 4 (text multicasting) b) (superposition position of data line and amplitude of text signal) defines the test method and basis.The waveform of caption signal is not NRZ. Since it is a pure sinusoidal wave, it is not necessary to apply the above criteria. However, in order to expand the coverage area, which is more than 70% of mountainous areas like Korea, the sinusoidal wave level should be maintained between 50 ± 5 IRE and 90 ± 5 IRE. Although the maximum amplitude of the normal data signal is defined, the overshoot may be included due to filter passband characteristics, so the maximum value of the overshoot is 5 IRE.

Referring to FIG. 3, the data line of the caption signal is composed of a six-cycle bit clock synchronization signal 302, a weed start signal 304, and an 18-bit data string 306.

The bit clock synchronization signal 302 is a sinusoidal signal of 6 cycles and can be used by the caption decoding unit to extract the signal and read out the bit period of 18-bit data. The frequency is fsc / 4 (894.886 kHz). If the phase of the color carrier of the scan line is 0 degrees, it starts at the point 9.5usec (34 bursts of color burst) from the falling edge (0H) of the horizontal synchronization signal, and the phase of the color carrier of the scan line is If it is 180 degrees, it starts at a point separated by 9.64usec (34.5 cycles of color burst) from the falling edge midpoint (0H) of the horizontal synchronization signal. Since this signal is in frequency synchronization with the color burst of the corresponding line, it is also possible to extract the bit clock synchronization signal from the color burst.

The word start signal 304 is a period of a sinusoidal signal of fsc / 16 (223.722 kHz) and 180 degrees in phase, and serves to indicate the start of an 18-bit data packet. The data string of the word start signal may be one of 01, 001, 010, and 011.

The data signal 306 is composed of 18 bits, and the bit rate is fsc / 8 (447.443 kHz) and modulated in the BPSK method.

Referring to FIG. 4, the data packet is composed of three parts: a parity (p) in Weed, a subtitle caption / additional information flag (C / T), and a code value. D0 to D8 are referred to as lower words, and D9 to D17 are referred to as upper words. D17 represents even parity for D0 to D16. This parity bit is for first detecting errors in transmission. D7 and D16 are the subtitle caption / additional information flag, 0 for the subtitle and 1 for the additional information, and the values of D7 and D16 must match. This flag is used to maintain word priority. D0 to D6 and D9 to D15 together represent a code value. Code values are interpreted as control codes if D5, D6, D14, and D15 are mode 0, and as character codes otherwise.

The data signal may be composed of 16 bits as shown in FIG. In the 16-bit configuration, the caption / text bits defined in the 18-bit format described above are configured as control codes to reduce 2 bits. For example, the caption / text control code can be set to 7 of the LSB byte and A of the MSB byte.

In the case of using 17 bits as shown in FIG. 6, the parity is used for the LSB and the MSB in the 18 bits described above, but this is a format in which 1 bit is reduced by integrating all of the parity bits into one.

The data signal has a frequency of 32 times the horizontal frequency when the digital modulation method is set to NRZ.

As described above, according to the present invention, the sine wave obtained by digitally modulating the format of the caption signal by the BPSK method and dividing the color subcarriers of the television signal can not only improve the reception state of the receiving device, but also has a 70% production area. The quality of the closed caption signal can be improved by reducing the reception sensitivity and error rate of the closed caption signal in an area where the television radio wave reception condition is a bad condition. Further, since the subcarrier signal is formed by dividing the color carrier, the stability of the signal by the phase synchronization and the phase synchronization circuit of the preset color carrier can be easily obtained, thereby reducing the cost burden of the receiver.

As described above, according to the present invention, the sine wave obtained by digitally modulating the format of the caption signal by the BPSK method and dividing the color subcarriers of the television signal can not only improve the reception state of the receiving device, but also has a 70% production area. The quality of the closed caption signal can be improved by reducing the reception sensitivity and error rate of the closed caption signal in a region where the television radio wave reception condition is poor. Further, since the subcarrier signal is formed by dividing the color carrier, the stability of the signal by the phase synchronization and the phase synchronization circuit of the preset color carrier can be easily obtained, thereby reducing the cost burden of the receiver.

Claims (5)

In a caption signal format of a viewer-selective caption broadcasting in which a caption signal is carried on one scanning line of every field of the television signal, the caption signal is a sine wave signal maintained at a predetermined level and divided with the color carrier of the television signal. Bit clock synchronization signal; A word start signal having a frequency divided by the bit clock synchronization signal; And a digitally modulated data signal composed of predetermined bits. The modulation method of the data signal is one of Binary Phase Shift Keying (BPSK), Non-Return-to-Zero (NRZ), and Phase Reversal Keying (PRK). The word start signal is divided into two or four frequency divisions of the bit clock synchronization signal, and the data sequence is one of 01, 001, 010, and 011. And the data signal has a frequency obtained by dividing the frequency of the bit clock synchronization signal by two when the NRZ or BPSK is modulated. The data signal is a caption signal format, characterized in that when the NRZ modulation has a frequency of 32 times the horizontal frequency.