JPH04142191A - Time base correcting device - Google Patents

Abstract

PURPOSE:To accurately correct a time base to obtain a signal where a time base error is almost all eliminated by obtaining the time base error in the boundary part of a TCI signal by operation. CONSTITUTION:If a reproduced video signal is the TCI signal where plural kinds of signal out of plural color signals and luminance signals have time bases compressed and are multiplexed, a synchronizing signal separating circuit 2 separates a horizontal synchronizing signal or a burst signal from the reproduced TCI signal, and a time base error detection circuit 3 detects the time length of one horizontal scanning period to detect the time base error. A TCI signal boundary part time base error operating circuit 5 uses the output of the circuit 3 to obtain the time base error in the boundary part of the TCI signal. After the phase of a luminance signal read clock 16 is corrected to correct the time base error in the start part of the luminance signal, read from a memory 12 is started. Thus, the time base correction is accurately performed, and the time base error is almost all eliminated even in the case of the TCI signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a time axis correction device for removing time axis fluctuations included in a reproduced video signal.

2. Description of the Related Art A conventional general time axis correction device will be described with reference to FIG. In order to remove time axis fluctuations in the reproduced video signal of a VTR or the like, the synchronization signal separation circuit 21 extracts a horizontal synchronization signal from the reproduced video signal 2o.

Extracts reference signals such as burst signals, AFc circuit (automatic frequency control circuit), APC circuit (automatic phase control circuit)
The write clock generation circuit 23, which is composed of the following components, generates a write clock signal 30 whose phase is synchronized with the horizontal synchronization signal or burst signal of the reproduced video signal 20. Then, the playback video signal 20 is generated by the write clock signal 30.
is A/D converted by the A/D conversion circuit 27 and written into the memory 28 using the write clock signal 30 as a clock. Since the write clock signal 30 is phase-synchronized with the horizontal synchronization signal or burst signal of the reproduced signal, time axis fluctuations included in the reproduced video signal 20 are removed at the time it is written to the memory 28. However, since the time axis error is detected using the horizontal synchronization signal or burst signal separated from the playback signal, - the time axis error can only be detected for each horizontal scanning period; - the time axis within the horizontal scanning period; Changes will remain. In particular, large time axis fluctuations that occur when the tape and head come into contact remain unremoved.

Therefore, the time axis fluctuation within one horizontal scanning period is removed by the following procedure.

That is, the reference clock generation circuit 25 generates a reference clock synchronized with the external input synchronization signal 24, and the time axis error detection circuit 22 detects the length of one horizontal scanning period from the output of the synchronization signal separation circuit 21 to determine the time. After detecting the axis error, the phase modulation circuit 26 phase-modulates the output of the reference clock generation circuit 25 to correct the time axis error within the -horizontal scanning period to obtain the read clock 31. The video signal is sent to the memory 28 using the read clock 31 as a clock.
The data is read out from the data source and subjected to D/A conversion by the D/A conversion circuit 28. The video signal is processed by the D/A with the readout clock 31 modulated to correct the time axis error within the horizontal scanning period.
Since the D/A converted video signal is converted, the time axis error within the -horizontal scanning period is also removed.

Problems to be Solved by the Invention However, in the above conventional example, when the reproduced video signal is a signal (TCI signal) in which multiple types of signals among multiple color signals and luminance signals are time-base compression multiplexed, the conventional method cannot be used. Even if you try to adapt it as it is, in the conventional method, the time axis error is determined by detecting the length of one horizontal scanning period of the T(l signal, so the determined time axis error is calculated by detecting the length of one horizontal scanning period of the T(l signal). It is not the time axis error of .For this reason,
With conventional methods, it has been impossible to perform time axis correction of the TCI signal.

An object of the present invention is to provide a time axis correction device that accurately corrects time axis errors even when a reproduced video signal is a TCI signal.

Means for Solving the Problems In order to achieve the above object, the time axis correction device of the present invention comprises:
a synchronization signal separation circuit that separates a synchronization signal from a TCI signal in which a plurality of types of signals of a plurality of color signals and luminance signals including time axis fluctuations are time-axis compression multiplexed; a time axis error detection circuit that detects the time length of one horizontal scanning period of a signal and detects a time axis error; and a TCI signal that calculates a time axis error of a boundary portion of the TCI signal from the output of the time axis error detection circuit. a boundary portion time axis error calculation circuit; a write clock generation circuit that generates a memory write clock from the output of the synchronization signal separation circuit; and a standard for processing the first signal of the TCI signals from a synchronization signal input from an external source. A first clock generation circuit that generates a clock, and a synchronization signal input from the output of the first clock generation circuit or externally input to the TCI.
A second clock generation circuit generates a reference clock for processing a second signal among the signals, and the first clock is generated by the output of the time axis error detection circuit and the output of the TCI signal boundary portion time axis error calculation circuit. A first clock phase modulation circuit phase modulates the output of the generation circuit, and the output of the second clock generation circuit is phase-modulated by the output of the time axis error detection circuit and the output of the TCI signal boundary portion time axis error calculation circuit. A second clock phase modulation circuit that modulates the clock and the output of the write clock generation circuit as a clock.
an A/D conversion circuit that A/D converts a CI signal;
a memory that stores the output of the D conversion circuit; and a first memory that performs D/A conversion after reading the first signal from the memory using the output of the first clock phase modulation circuit as a clock.
a D/A conversion circuit, and a second D/A conversion circuit that reads the second signal from the memory using the output of the second clock phase modulation circuit as a clock and then performs D/A conversion. be done.

Then, the TCI signal boundary portion time axis error calculation circuit uses the output of the time axis error detection circuit to obtain the time axis error of the boundary portion of the TCI signal by linear approximation or polynomial approximation.

Effect With the above configuration, even when the reproduced video signal is a TCI signal, by calculating the time axis error at the boundary portion of the TCI signal, it is possible to accurately detect the time axis error for each signal of the TCI signal. As a result, time axis correction can now be performed accurately. Therefore, it has become possible to almost eliminate time axis errors even in the case of TCI signals.

Embodiments Hereinafter, embodiments of the time axis correction device of the present invention will be described. Figure 1 shows that the reproduced TCI signal is time-base compression multiplexed with a color signal (second signal) and a luminance signal (first signal) as shown in Figure 2 (A) or Figure 2 (B). FIG. 2 is a block diagram showing an example in which the signal is a TCI signal. below,
A case will be explained in which the reproduced TCI signal is a TCI signal in which a luminance signal (first signal) is multiplexed in the first half and a color signal (second signal) is multiplexed in the second half, as shown in FIG. 2(B). .

The synchronization signal separation circuit 2 separates a horizontal synchronization signal, a burst signal, etc. from the reproduced TCI signal 1.

The time axis error detection circuit 3 detects a time axis error by detecting the time length of the -horizontal scanning period using the output of the synchronization signal separation circuit 2. The write clock generation circuit 4 is composed of an AFC circuit (automatic frequency control circuit), an APC circuit (automatic phase control circuit), etc., and generates a write clock 15 that is phase-synchronized with the horizontal synchronization signal or burst signal of the reproduced video signal. . The TCI signal boundary portion time axis error calculation circuit 5 uses the output of the time axis error detection circuit 3 to obtain a time axis error at the boundary portion of the TCI signal by linear approximation or polynomial approximation. A luminance signal processing clock generation circuit (first clock generation circuit) 7 generates a reference clock for luminance signal processing synchronized with an external input synchronization signal 6, and a chrominance signal processing clock generation circuit (second clock generation circuit) 8. is the luminance signal processing clock generation circuit 7
The frequency of the output is divided to generate a reference clock for color signal processing. The luminance signal processing clock phase modulation circuit (first clock phase modulation circuit) 9 includes the luminance signal processing clock generation circuit 7
is modulated according to the output of the time axis error detection circuit 3 and the output of the TCI signal boundary portion time axis error calculation circuit 5 to generate a luminance signal read clock 16. In other words, TC in advance! After the phase of the luminance signal readout clock 16 is corrected so as to correct the time axis error of the start portion of the luminance signal determined by the signal boundary portion time axis error calculation circuit 5, reading from the memory 12 is started. Then, the luminance signal is read out from the memory 12 while gradually shifting the phase of the luminance signal readout clock 16, and the luminance signal readout clock is read out from the memory 12 until the time axis error in the horizontal scanning period determined by the time axis error detection circuit 3 is corrected. 1
Modulate the phase of 6. This situation is shown in FIG. The phase modulation of the luminance signal readout clock 16 is performed either by regarding the phase change as a straight line and performing phase modulation by linear approximation, or by obtaining a phase change curve by polynomial approximation and modulating it.

A color signal processing clock phase modulation circuit (second clock phase modulation circuit) 10 converts the output of the color signal processing clock generation circuit 8 into the output of the time axis error detection circuit 3 and the TCI signal boundary portion time axis error calculation circuit 5. It modulates according to the output and generates a color signal readout clock 17. That is, the phase of the color signal readout clock 17 is not modulated at the start of memory readout, and the color signal is read out from the memory 12 while gradually shifting the phase of the color signal readout clock 17, and the TCI signal boundary portion time axis error calculation circuit The color signal readout clock 17 is modulated until the time axis error in the end portion of the color signal determined by step 5 is corrected. This situation is shown in FIG. The phase modulation of the color signal readout clock 17 is carried out either by regarding the phase change as a straight line and performing phase modulation by linear approximation, or by finding and modulating a phase change curve by polynomial approximation.

The A/D conversion circuit 11 converts the reproduced TCI signal 1 into an A/D converter using the write clock 15 generated by the write clock generation circuit 4.
The converted and A/D converted TCI signal is written into the memory 12. Then, the luminance signal is read out from the memory 12 using the luminance signal readout clock 16, and the luminance signal D
D/A conversion is performed by the /A conversion circuit 13. The D/A converted luminance signal 18 is - within the horizontal scanning period,
Both the start phase and end phase are correctly corrected, and time axis errors are removed. The color signal is read out from the memory 12 using a color signal readout clock 17 and subjected to D/A conversion by a color signal D/A conversion circuit 14 . The D/A converted color signal 19 has both the start phase and the end phase corrected correctly within the -horizontal scanning period, and the time axis error is removed. Note that even if the TCI signal is a TCI signal as shown in Figure 2 (A) in which the color signal (first signal) is multiplexed in the first half and the luminance signal (second signal) is multiplexed in the second half, the same procedure can be applied. Needless to say, time axis errors can be removed. In this case, only the correction methods for the readout clocks for the chrominance signal and the luminance signal are reversed.

In addition, the TCI signal has one type of color signal (first signal) in the first half and one type (second signal) of the color signals in the second half as shown in FIG. 2(C). axis multiplexed TC
In the case of an I signal, the time axis error can be corrected using the same method, and in the case of a TCI signal in which multiple types of color signals and luminance signals are time axis compression multiplexed, the time axis error at the boundary portion of each signal can be corrected. It is also clear that the time axis error can be corrected in the same way by finding .

Effects of the Invention As described above, the present invention is capable of accurately detecting the time axis error of each signal by calculating the time axis error of the boundary portion of the TCI signal when the reproduced video signal is a TCI signal. This makes it possible to perform time axis correction accurately and obtain a signal with almost no time axis errors removed.

This is particularly effective in eliminating large time axis fluctuations that occur when the tape and head come into contact.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a time axis correction device in an embodiment of the present invention, and FIGS. 2(A) and 2(B). (C) is a waveform diagram showing an example of the TCI signal in the same embodiment, FIG. 3 is a characteristic diagram showing an example of time axis error in the same embodiment, and FIG. 4 is a diagram of the color signal readout clock in the same embodiment. A characteristic diagram showing an example of the correction amount; FIG. 5 is a characteristic diagram showing an example of the correction amount of the luminance signal readout clock in the same embodiment; FIG. 6 is a block diagram showing the configuration of a conventional time axis correction device. It is. 3... Time axis error detection circuit, 4... Write clock generation circuit, 5... TCI signal boundary portion time axis error calculation circuit, 7... Luminance signal processing clock generation circuit, 8... Color Signal processing clock generation circuit, 9...
・Luminance signal processing clock phase modulation circuit, 10...
Color signal processing clock phase modulation circuit, 11...A/
D conversion circuit, 12... Memory, 13... Luminance signal D/A conversion circuit, 4... Color signal D/A conversion circuit.

Claims (3)

[Claims] (1) a synchronization signal separation circuit that separates a synchronization signal from a TCI signal in which a plurality of types of signals among a plurality of color signals and luminance signals including time axis fluctuations are time-axis compression multiplexed; and the synchronization signal separation circuit. a time axis error detection circuit that detects the time length of one horizontal scanning period of the TCI signal from the output of the TCI signal and detects a time axis error; and a time axis error of the boundary portion of the TCI signal from the output of the time axis error detection circuit. a TCI signal boundary part time axis error calculation circuit that calculates the first TCI signal, a write clock generation circuit that generates a memory write clock from the output of the synchronization signal separation circuit, and a write clock generation circuit that generates a memory write clock from the output of the synchronization signal separation circuit; a first clock generation circuit that generates a reference clock for processing a signal; and a reference clock for processing a second signal of the TCI signal from an output of the first clock generation circuit or a synchronization signal input from the outside. a second clock generation circuit that generates a second clock, and a first clock phase that modulates the phase of the output of the first clock generation circuit by the output of the time axis error detection circuit and the output of the TCI signal boundary portion time axis error calculation circuit. a modulation circuit, an output of the time base error detection circuit, and the TCI
a second clock phase modulation circuit that phase modulates the output of the second clock generation circuit using the output of the signal boundary portion time axis error calculation circuit; D convert A/
a D-conversion circuit; a memory for storing the output of the A/D conversion circuit; and a D/A conversion after reading the first signal from the memory using the output of the first clock phase modulation circuit as a clock. After reading the second signal from the memory using the outputs of the first D/A conversion circuit and the second clock phase modulation circuit as a clock,
A time axis correction device including a second D/A conversion circuit that performs A conversion. (2) The time axis correction device according to claim 1, wherein the TCI signal boundary portion time axis error calculation circuit calculates the time axis error of the boundary portion of the TCI signal by linear approximation. (3) The time axis correction device according to claim 1, wherein the TCI signal boundary portion time axis error calculation circuit calculates the time axis error of the boundary portion of the TCI signal by polynomial approximation.