KR20050093453A - Apparatus for restoring synchronizing signal - Google Patents

Abstract

Compensates for damaged horizontal and vertical sync signals to reliably decode the closed caption data and also reduces the parameters used to adjust the closed caption decoder.

The clock run-in signal detector detects the clock run-in signal from the video signal, the caption start bit detector detects the caption start bit signal from the video signal according to the detected clock run-in signal, and the horizontal synchronizing signal compensation value setting unit Detects the time error from the falling edge of the signal until the clock run-in signal is detected and sets a compensation value according to the detected time error. When the caption start bit signal is detected, the horizontal sync signal compensator A horizontal synchronizing signal having a width corresponding to the set compensation value is generated from the falling edge, and the horizontal synchronizing signal error value detection unit is horizontal from the falling edge of the vertical synchronizing signal until the caption start bit detecting unit detects the caption start bit signal. The error value of the vertical synchronization signal is detected by counting the number of synchronization signals, and starting from the falling edge of the vertical synchronization signal. A vertical sync signal with a width of the straight-sync signal error value by detecting a detection error value arises added vertical synchronizing signal compensation.

Description

Apparatus for restoring synchronizing signal

The present invention provides a broadcast signal receiver such as a digital television receiver and a set top box, in which a closed caption decoder can accurately decode the closed caption data when the synchronization signal is damaged. It relates to a synchronization signal compensation device.

In general, the NTSC (National Television Standards Committee) signal consists of 30 screens each consisting of a first field and a second field per second, and a vertical blanking interval, which is an empty space without any data between each field. blanking interval).

The closed caption data and the text are transmitted on the 21st line and the 284th line of the vertical blanking section (Y, Pb, Pr and S-video input system are loaded on the Y signal, and the analog RGB system Is displayed on all three signals), and also the data of extended data services (XDS) serving program names, start and end times, program ratings, and other information. It can be loaded on the transmission.

The signal used for the closed caption is a clock run in signal next to the horizontal synchronization signal and the color burst signal, a 3-bit start bit signal, and two 7-bit data (b0 to b6) as shown in FIG. ) And two-byte closed caption data consisting of two parity bits p1 and p2, that is, a character signal 1 and a character signal 2.

Among the signals of the closed caption data, the clock run-in signal is a sine wave burst signal having seven periods, and is frequency locked and phase locked to the closed caption data, which is synchronized with the closed caption decoder. As to provide a signal, the closed caption decoder determines whether there is closed caption data based on the clock run-in signal, and determines the frequency and phase of the closed caption data to be decoded.

2 is a block diagram showing the configuration of a general NTSC signal decoder and a closed caption decoder. Here, reference numeral 100 denotes an NTSC signal decoder for decoding an NTSC signal, and reference numeral 110 denotes a closed caption decoder for decoding closed caption data from a signal decoded by the NTSC signal decoder 100.

The NTSC signal decoder 100 is closed by processing a signal of the NTSC signal and a synchronization signal separator 101 which separates the horizontal synchronization signal HS and the vertical synchronization signal VS from the input NTSC signal. And a signal processor 103 for outputting image data including caption data.

The closed caption decoder 110 may include a noise removing unit 111 that receives image data including closed caption data processed and output by the signal processor 103 of the NTSC signal decoder 100 and removes noise; Caption data is loaded from a signal from which noise is removed from the noise canceling unit 111 by a horizontal sync signal HS and a vertical sync signal VS separated by the sync signal separator 101 of the NTSC signal decoder 100. Caption data determination to determine whether the caption data is included in the caption data line determination unit 113 for determining a line and the caption data determined by the caption data line determination unit 113 with the vertical synchronization signal HS. And a caption data extracting unit 117 for extracting caption data when the caption data determining unit 115 determines whether caption data is loaded.

In the NTSC signal decoder 100 and the closed caption decoder 110 having the above-described configuration, when the NTSC signal is input, the sync signal separator 101 of the NTSC signal decoder 100 is a horizontal synchronization signal ( HS) and the vertical sync signal VS are separated and output to the closed caption decoder 110, and the signal processor 103 of the NTSC signal decoder 100 processes an NTSC signal to process image data including caption data. Output to the closed caption decoder 110.

Then, the closed caption decoder 110 low-pass filters the image data including the caption data output from the signal processor 103 to remove noise and outputs the noise to the caption data line determiner 113. The caption data line determination unit 113 counts a horizontal synchronization signal HS according to the vertical synchronization signal VS to detect a line including caption data, that is, a 21st line and a 284th line.

When the caption data line determination unit 113 detects a line containing the closed caption data, the caption data determination unit 115 detects a section of the clock run in signal from the horizontal synchronization signal HS and detects the clock run in. Based on the signal, the caption data line determining unit 113 determines whether the closed caption data is included in the detected line, and if the closed caption data is loaded, the caption data extraction unit 117 notifies the caption data extraction. The unit 117 extracts caption data of 2 bytes.

In the closed caption decoder 110, the horizontal caption signal HS and the vertical synchronizing signal VS which are separated from the synchronizing signal separator 101 of the NTSC signal decoder 100 must exactly match the standard specifications. 110 may accurately extract the closed caption data. That is, during the period of the vertical synchronizing signal VS as shown in FIG. 3A, the horizontal synchronizing signal HS is composed of an equalization pulse signal, a separation pulse signal, and an equalization pulse signal as shown in FIGS. 3B and 3C. The closed caption decoder 110 detects the 21st line and the 284th line and counts the caption data while counting the horizontal sync signal HS from the falling edge of the vertical sync signal VS.

However, an NTSC signal is broadcasted by air over the airwaves, and when a broadcast signal receiver receives it, a bad reception occurs, or channel noise caused by a poor transmission over a cable, or a storage medium such as a video tape or an optical disk. In the process of storing and reproducing an NTSC signal, deterioration of the vertical synchronization signal VS and the horizontal synchronization signal HS of a standard standard cannot be performed correctly, and many cases are damaged and separated.

As such, when the vertical sync signal VS and the horizontal sync signal HS separated from the NTSC signal are greatly different from the standard standard, the closed caption decoder 110 accurately detects the 21st line and the 284th line. As a result, an error in which the closed caption data is not extracted accurately may occur. That is, the horizontal synchronizing signal HS and the vertical synchronizing signal VS separated by the synchronizing signal separator 101 of the NTSC signal decoder 100 do not achieve the standard as shown in FIGS. 4A and 4B. For example, when the vertical sync signal VS is separated as shown in FIG. 4C, the closed caption data is not positioned on the 21st line of the horizontal sync signal HS based on the falling edge of the vertical sync signal VS. As a result, a problem arises that the closed caption data cannot be extracted.

Therefore, in the related art, it is possible to determine whether there is closed caption data in a predetermined range, for example, the 19th to 23rd lines, based on the 21st line, so that the horizontal sync signal HS and the vertical sync signal VS are somewhat different. Although it is possible to extract closed caption data even if the standard is out of the standard, when the horizontal sync signal (HS) and the vertical sync signal (VS) are outside the standard of 3 lines or more, the closed caption data still cannot be extracted. In order to decode the caption data, there is an inconvenience and inconvenience that the user has to input an excessive value parameter for the synchronization signal to the closed caption decoder.

It is therefore an object of the present invention to provide a synchronization signal compensation device capable of stably decoding closed caption data by compensating a synchronization signal input to a closed caption decoder.

Another object of the present invention is to reduce the parameters used to adjust the closed caption decoder, to actively cope with the input of the distorted sync signal, to enhance user convenience, and to accurately detect the closed caption data. It is to provide a signal compensation device.

According to the synchronizing signal compensation device of the present invention having the above object, the original signal is severely damaged due to deterioration or transmission noise caused by the accumulation of images with closed caption data in the vertical blanking section due to excessive reproduction or copying. Hardware for improving the responsiveness to the distorted signal and adjusting the decoding timing interval of the caption decoder for the original video signal when the decoding is not suitable or the synchronization signal cannot be properly separated according to the characteristics of the caption decoder. Configure logic to reduce additional costs and improve the decoding performance of caption data.

The synchronization signal compensator of the present invention comprises logic capable of reconstructing vertical and horizontal synchronization signals separated from an NTSC signal, and logic for determining the presence of a clock run-in signal. The two logics work together to automatically determine the vertical blanking section search section, eliminating the need for the user to specify the search section.

Therefore, the synchronization signal compensating apparatus of the present invention includes a clock run-in signal detector for detecting a clock run-in signal from an image signal, and a caption start bit signal from the video signal when the clock run-in signal detector detects a clock run-in signal. A caption start bit detection unit for detecting a horizontal synchronization signal compensation for detecting a time error from the falling edge of the horizontal synchronization signal until the clock run-in signal detection unit detects a clock run-in signal and setting a compensation value according to the detected time error. When the value setting unit and the caption start bit detection unit detects a caption start bit signal, generating a horizontal synchronization signal having a width corresponding to the compensation value set by the horizontal synchronization signal compensation value setting unit from the falling edge of the horizontal synchronization signal. The caption start bit detecting unit starts from the falling edge of the horizontal synchronizing signal compensation unit and the vertical synchronizing signal. A vertical sync signal error value detector for counting the number of horizontal sync signals until the signal is detected to detect an error value of the vertical sync signal, and a vertical sync signal error value detector detected from a falling edge of the vertical sync signal And a vertical synchronizing signal compensator for generating a vertical synchronizing signal having a width according to the error value.

The horizontal synchronizing signal compensation value setting unit includes a falling edge detecting unit detecting a falling edge of the horizontal synchronizing signal, and the clock run in signal detecting unit is a clock run in when the falling edge detecting unit detects the falling edge of the horizontal synchronizing signal. A time error detection unit for detecting a time error of the horizontal synchronization signal by comparing a counter counting a clock signal until a signal is detected, a count value of the counter and a preset reference value, and outputting a compensation value to the horizontal synchronization signal compensation unit; Characterized in that consisting of.

The horizontal synchronizing signal compensator includes: a caption detection window generating unit for counting the horizontal synchronizing signal from a falling edge of the vertical synchronizing signal, and generating a caption detection window having a predetermined width according to the count value; and generating the caption detection window. Compensation set by the horizontal synchronizing signal compensation value setting unit from the falling edge of the horizontal synchronizing signal according to an AND gate for logically multiplying the additionally generated caption detection window and the detection signal of the caption start bit detection unit. Characterized in that it comprises a horizontal synchronization signal generator for generating a horizontal synchronization signal of the width according to the value.

The vertical synchronizing signal error value detecting unit includes a falling edge detecting unit detecting a falling edge of the vertical synchronizing signal, a horizontal synchronizing signal counter counting a horizontal synchronizing signal from the falling edge detecting unit detecting the falling edge of the vertical synchronizing signal; When the caption start bit detection unit detects a caption start bit signal, the caption start bit detector stores a count value of the horizontal synchronization signal counter and outputs the count value as an error value of the vertical synchronization signal.

The vertical synchronizing signal compensator may include a vertical synchronizing signal compensating value setting unit configured to set a compensation value for compensating the vertical synchronizing signal according to the error value of the vertical synchronizing signal detected by the vertical synchronizing signal error value detecting unit; And a vertical synchronizing signal generator for generating a vertical synchronizing signal having a width corresponding to the compensation value set by the vertical synchronizing signal compensation value setting unit from the falling edge.

Hereinafter, the synchronization signal compensation apparatus of the present invention will be described in detail with reference to the accompanying drawings of FIGS. 5 to 7.

5 is a block diagram showing the configuration of the synchronization signal compensation apparatus of the present invention. As shown in the figure, the caption start bit in the video signal when the clock run-in signal detector 200 detects the clock run-in signal from the video signal and the clock run-in signal detector 200 detects the clock run-in signal. A caption start bit detection unit 210 for detecting a signal and a time error from the falling edge of the horizontal synchronizing signal HS to the clock run-in signal detection unit 200 detecting a clock run-in signal. The horizontal synchronization signal compensation value setting unit 220 for setting a compensation value according to the horizontal direction, and when the caption start bit detection unit 210 detects a caption start bit signal, the horizontal synchronization signal HS falls from the falling edge of the horizontal synchronization signal HS. The caption start bit check is performed from the falling edge of the vertical synchronizing signal VS and the horizontal synchronizing signal compensator 230 generating a horizontal synchronizing signal having a width corresponding to the compensation value set by the synchronizing signal compensation value setting unit 220. A vertical sync signal error value detector 240 for counting the number of horizontal sync signals until the unit 210 detects a caption start bit signal to detect an error value of the vertical sync signal, and the vertical sync signal VS The vertical synchronization signal compensator 250 generates a vertical synchronization signal having a width corresponding to the error value detected by the vertical synchronization signal error value detection unit 240 from the falling edge of.

The horizontal synchronizing signal compensation value setting unit 220 includes a falling edge detecting unit 221 for detecting a falling edge of the horizontal synchronizing signal, and a time when the falling edge detecting unit 221 detects a falling edge of the horizontal synchronizing signal. The counter 223 counts the clock signal CLK until the clock run in signal detection unit 200 detects the clock run in signal, and compares the count value of the counter 223 with a preset reference value to perform horizontal synchronization. The time error detector 225 detects a time error of the signal.

The horizontal synchronizing signal compensator 230 counts the horizontal synchronizing signal HS from the falling edge of the vertical synchronizing signal 231 and generates a caption detection window having a predetermined width according to the count value. An AND gate 233 which logically multiplies a generation unit 231, a caption detection window generated by the caption detection window generation unit 231, and a detection signal of the caption start bit detection unit 210, and the AND gate ( Horizontal sync signal generator for generating a horizontal sync signal of the width according to the compensation value set by the horizontal sync signal compensation value setting unit 220 from the falling edge of the horizontal sync signal (HS) according to the output signal of the (233) ( 235).

The vertical synchronization signal error value detector 240 includes a falling edge detector 241 for detecting the falling edge of the vertical synchronization signal VS and a falling edge detector 241 for the falling edge of the vertical synchronization signal VS. The horizontal synchronizing signal counter 243 which counts the horizontal synchronizing signal HS from the time of detection, and the count of the horizontal synchronizing signal counter 243 when the caption start bit detecting unit 210 detects the caption start bit signal. The count value storage unit 245 stores the value and outputs the error value of the vertical synchronization signal.

The vertical synchronizing signal compensator 250 is configured to set a compensation value for compensating the vertical synchronizing signal according to the error value of the vertical synchronizing signal detected by the vertical synchronizing signal error value detecting unit 240. 251 and a vertical synchronization signal generator 253 for generating a vertical synchronization signal having a width corresponding to the compensation value set by the vertical synchronization signal compensation value setting unit 251 from the falling edge of the vertical synchronization signal VS. It consisted of.

In the synchronization signal compensating apparatus of the present invention configured as described above, the clock run in signal detecting unit 200 detects the clock run in signal from the input image signal, and the detection signal of the clock run in signal is the horizontal synchronizing signal compensation value setting unit 220. Is applied to the disable terminal DIS of the counter 223, and the caption start bit detection unit 210 performs the caption start bit in the video signal when the clock run in signal detection unit 200 detects the clock run in signal. The signal is detected to determine whether or not it is a horizontal synchronization signal line carrying caption data.

The falling edge detector 221 of the horizontal synchronizing signal compensation value setting unit 220 detects the falling edge of the horizontal synchronizing signal HS, and the detection signal of the falling edge of the horizontal synchronizing signal HS is a counter 223. Is applied to the reset terminal RST. Then, the counter 223 counts the clock signal CLK after the count value is reset according to the detection signal of the falling edge of the horizontal synchronization signal HS, and the clock run in signal detection unit 200 performs the clock run in signal. Stops counting the clock signal CLK. That is, the counter 223 counts the clock signal CLK for a time from the falling edge of the horizontal synchronization signal HS until the clock run-in signal is detected.

The count value of the counter 223 is input to the time error detector 225, and the time error detector 225 detects a time error by comparing the count value of the counter 223 with a preset reference value. That is, the time from the falling edge of the horizontal synchronization signal HS to the time when the clock run-in signal is generated is defined as 10.50 ms. The time error detection unit 225 determines the count value and the preset reference value of the counter 223. By comparison, time error is detected and the detected time error value is output as a compensation value of the horizontal synchronization signal.

The vertical synchronization signal error value detector 240 detects the falling edge of the vertical synchronization signal VS and outputs a detection signal by the falling edge detector 241. The output signal is output by the horizontal synchronization signal compensation unit 230. The caption detection window generator 231 outputs the caption detection window.

Then, the caption detection window generator 231 counts the horizontal synchronization signal HS while being reset according to the detection signal of the falling edge of the vertical synchronization signal VS, and the caption data when the count value is a predetermined value. For example, when the number of counted horizontal synchronization signals HS is 19 to 23, a high potential is output and applied to one input terminal of the AND gate 233, and the AND gate 233 is generated. The caption start bit detector 210 detects the caption start bit signal by the caption start bit detector 210, and thus the caption start bit detector 210 during the window period generated by the caption detection window generator 231. When AND detects the caption start bit signal, the AND gate 233 outputs a high potential and is input to the horizontal synchronization signal generator 235.

The horizontal synchronizing signal generator 235 is a horizontal synchronizing device having a predetermined width corresponding to a time error, that is, a compensation value, detected by the time error detecting unit 225 since the falling edge detecting unit 221 detects the falling edge. A signal is generated, and the generated horizontal synchronizing signal is output when the AND gate 233 outputs a high potential to compensate for the horizontal synchronizing signal.

For example, when the horizontal synchronization signal of the standard standard as shown in FIG. 6A is damaged and the horizontal synchronization signal HS is input as shown in FIG. 6B, the horizontal synchronization signal generator 235 is shown in FIG. When the horizontal synchronization signal is generated and compensated as shown in FIG. 6C, and the horizontal synchronization signal HS is input as shown in FIG. 6D, the horizontal synchronization signal generator 235 is shown in FIG. 6E. As described above, the horizontal synchronization signal is generated and compensated.

Since the falling edge signal of the vertical synchronizing signal VS detected by the falling edge detector 241 is input to the horizontal synchronizing signal counter 243, the vertical synchronizing signal error value detecting unit 240 receives the horizontal synchronizing signal counter 243. The number of horizontal sync signals HS is counted from the falling edge of the vertical sync signal VS, and the count value is counted to the count value storage unit 245 when the caption start bit detector 210 detects the caption start bit signal. It is entered and stored. That is, the count value storage unit 245 stores the count value of the horizontal sync signal HS from the falling edge of the vertical sync signal VS until the caption start bit signal is detected in the video signal containing the closed caption data. .

The count value stored in the count value storage unit 245 is input to the vertical synchronizing signal compensation value setting unit 251 of the vertical synchronizing signal compensating unit 250, and the vertical synchronizing signal compensating value setting unit 251 performs the count value. And a compensation value of the vertical synchronization signal are set in comparison with the line of the horizontal synchronization signal, that is, the twenty-first line, containing the closed caption data, and the set compensation value is input to the vertical synchronization signal generator 253.

Then, the vertical synchronizing signal generator 253 starts the compensation value set by the vertical synchronizing signal compensation value setting unit 251 when the falling edge detector 241 detects the falling edge of the vertical synchronizing signal VS. Compensate by generating a vertical synchronizing signal of the corresponding width.

That is, in the present invention, the vertical synchronization signal of the standard standard as shown in FIG. 7B is not input to the horizontal synchronization signal of the standard standard as shown in FIG. 7A, for example, as shown in FIG. 7C. When the synchronization signal is input slowly, the caption data is located on the 18th line and cannot be decoded. Also, as shown in FIG. 7E, the caption data is located on the 24th line and decoded even when the vertical synchronization signal is input quickly. You will not be able to. In this case, the present invention compensates for the vertical synchronizing signal as shown in Figs. 7D and 7F, so that the closed caption data is correctly positioned on the 21st line, thereby accurately decoding the closed caption data.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and changes of the present invention without departing from the spirit or field of the invention provided by the claims below It can be easily understood by those skilled in the art.

As described above, the present invention accurately decodes closed caption data included in an image signal by compensating for the horizontal and vertical sync signals when the horizontal and vertical sync signals for detecting the closed caption data are damaged. It is possible to reduce the parameters used to adjust the closed caption decoder.

1 is a diagram showing a signal configuration of general closed caption data.

2 is a block diagram showing the configuration of a general NTSC signal decoder and a closed caption decoder.

3A to 3C are diagrams for explaining a line in which caption data is loaded on a horizontal synchronization signal;

4A to 4C are diagrams for explaining a case in which caption data cannot be separated by an abnormal vertical synchronization signal.

Figure 5 is a block diagram showing the configuration of a synchronization signal compensation device of the present invention.

6A to 6E are diagrams for explaining that horizontal synchronization signals are compensated according to the synchronization signal compensation device of the present invention.

7A to 7F are diagrams for explaining that a vertical synchronization signal is compensated according to the synchronization signal compensation apparatus of the present invention.

Explanation of symbols on the main parts of the drawings

200: clock run-in signal detector 210: caption start bit detector

220: horizontal sync signal compensation value setting unit 221, 241: falling edge detection unit

223: counter 225: time error detection unit

230: horizontal synchronization signal compensation unit 231: caption detection window generation unit

233: AND gate 240: vertical sync signal error value detector

243: horizontal synchronizing signal counter 245: count value storing unit

250: vertical sync signal compensation unit 251: vertical sync signal compensation value setting unit

253: vertical synchronization signal generator

Claims (5)

A clock run-in signal detector for detecting a clock run-in signal from the image signal; A caption start bit detector for detecting a caption start bit signal from the video signal when the clock run-in signal detector detects a clock run-in signal; A horizontal synchronization signal compensation value setting unit configured to detect a time error from the falling edge of the horizontal synchronization signal to the clock run-in signal detection unit detecting a clock run-in signal and to set a compensation value according to the detected time error; When the caption start bit detection unit detects a caption start bit signal, a horizontal synchronizing signal compensator for generating a horizontal synchronizing signal having a width corresponding to a compensation value set by the horizontal synchronizing signal compensation value setting unit from the falling edge of the horizontal synchronizing signal; ; A vertical sync signal error value detector for counting the number of horizontal sync signals from the falling edge of the vertical sync signal until the caption start bit detector detects the caption start bit signal; And And a vertical synchronizing signal compensator for generating a vertical synchronizing signal having a width corresponding to the error value detected by the vertical synchronizing signal error value detecting unit from the falling edge of the vertical synchronizing signal. The method of claim 1, wherein the horizontal synchronization signal compensation value setting unit; A falling edge detector for detecting a falling edge of the horizontal synchronization signal; A counter counting a clock signal from the falling edge detector to the falling edge of the horizontal synchronization signal until the clock run-in signal detector detects the clock run-in signal; And And a time error detector for detecting a time error of the horizontal synchronization signal by comparing the count value of the counter with a preset reference value and outputting the compensation value to the horizontal synchronization signal compensator. The apparatus of claim 1, wherein the horizontal synchronization signal compensator; A caption detection window generation unit for counting the horizontal synchronization signal from the falling edge of the vertical synchronization signal and generating a caption detection window having a predetermined width according to the count value; An AND gate which logically multiplies the caption detection window generated by the caption detection window generator and the detection signal of the caption start bit detector; And And a horizontal synchronizing signal generating unit for generating a horizontal synchronizing signal having a width corresponding to a compensation value set by the horizontal synchronizing signal compensation value setting unit from the falling edge of the horizontal synchronizing signal according to the output signal of the AND gate. Compensator. The method of claim 1, wherein the vertical synchronization signal error value detector; A falling edge detector detecting a falling edge of the vertical synchronization signal; A horizontal synchronizing signal counter for counting a horizontal synchronizing signal from when the falling edge detecting unit detects a falling edge of the vertical synchronizing signal; And And a count value storage unit for storing the count value of the horizontal synchronization signal counter and outputting the count value of the horizontal synchronization signal counter when the caption start bit detection unit detects a caption start bit signal. The method of claim 1, wherein the vertical synchronization signal compensation unit; A vertical synchronization signal compensation value setting unit configured to set a compensation value for compensating the vertical synchronization signal according to the error value of the vertical synchronization signal detected by the vertical synchronization signal error value detector; And And a vertical synchronizing signal generating unit for generating a vertical synchronizing signal having a width corresponding to a compensation value set by the vertical synchronizing signal compensation value setting unit from the falling edge of the vertical synchronizing signal.