JP2001257995A - Video signal reproducer, video signal recorder and video signal recorder-reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video signal reproducer which can correct the time distortion even when the frequency and the number of scanning lines of video signals to be reproduced are much different from the normal ones. SOLUTION: In 1st operation mode, the reproduction operation of video signals is synchronized with the read operation of a memory and the memory read operation is synchronized with the reproduction operation of video signals in 2nd operation mode respectively. In normal reproduction mode, the 1st operation mode is selected. Then the 2nd operation mode is selected in the operation mode where the frequency and the number of scanning lines of video signals to be reproduced are much different from the normal ones.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal reproducing apparatus, a recording apparatus, and a recording / reproducing apparatus, and more particularly to a time axis correction process for a video signal.

[0002]

2. Description of the Related Art Generally, in a video signal reproducing apparatus, a reproduced video signal has time distortion. As a means for correcting this, there is known a so-called time base collector in which a video signal is once written into a memory and read out at a regular frequency. The correction range of the time distortion of the time base collector depends on the storage capacity of the memory, but it is desired that the storage capacity of the memory be as small as possible from the viewpoint of the scale and cost of the system.

[0005] For example, in normal speed reproduction in a reproduction apparatus such as a VTR, the number of scanning lines is controlled by controlling the reproduction speed so that the average field frequency of the reproduced video signal is adjusted to the normal field frequency by means of servo control or the like. A time-base collector can be realized with a memory having the same storage capacity.

[0004]

However, in the above-mentioned technique, no consideration has been given to time axis correction when performing special reproduction such as fast forward reproduction or rewind reproduction in a reproducing apparatus such as a VTR.

Further, in order to reproduce a non-standard signal, no consideration has been given to a time axis correction when a non-standard video signal is input to a time base collector. further,
As in the case of the reproduction, when recording the input video signal after correcting the time distortion, the time axis correction is not considered for the non-standard video signal.

The present invention provides a video signal reproducing apparatus capable of accurately correcting time distortion even when the frequency or the number of scanning lines of the reproduced video signal is significantly different from the regular frequency or the number of scanning lines. It is in.

Further, another object of the present invention is to record a video signal capable of correcting time distortion even when the frequency and the number of scanning lines of the video signal to be recorded are significantly different from the regular frequency and the number of scanning lines. It is to provide a device.

[0008]

According to the present invention, there is provided a first operation mode for synchronizing a video signal reproducing operation with a memory read operation, and a method for reproducing a video signal according to the present invention. And a second operation mode synchronized with the operation.

In the normal reproduction mode, the first operation mode is selected. That is, since the reproduced video signal is almost a regular video signal, the reproducing operation of the video signal recorded on the recording medium is synchronized with the reading operation of the memory running at the regular frequency. On the other hand, the second operation mode is selected for a reproduction mode in which the frequency and the number of scanning lines of the reproduced video signal are significantly different from the regular frequencies and the number of scanning lines. That is, the reading operation of the memory is synchronized with the reproducing operation of the video signal recorded on the recording medium.

By the above operation, even when the frequency of the reproduced video signal or the number of scanning lines is significantly different from the normal horizontal frequency or the number of scanning lines, the time distortion can be corrected.

When the frequency of the video signal or the number of scanning lines is significantly different from the normal frequency or the number of scanning lines When recording the video signal, the second operation mode is selected. That is, the read operation of the memory is synchronized with the write operation of the memory. On the other hand, at the time of reproduction, the first operation mode is selected.
That is, since the video signal once recorded on the recording medium in the second operation mode and reproduced next is almost a regular video signal, the reproducing operation is synchronized with the read operation of the memory which runs at the regular frequency. .

With the above operation, even when the frequency or the number of scanning lines of the video signal to be recorded or reproduced is significantly different from the normal horizontal frequency or the number of scanning lines, the time distortion can be corrected.

[0013]

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

FIG. 1 is a circuit block diagram showing one embodiment of the present invention. In FIG. 1, 101 is a video signal reproducing means for reproducing a video signal, 102 is a memory, 103 is a clock generation and synchronization separation circuit, 104 is a write control circuit, 105 is a clock generation circuit, 106 is a synchronization generation circuit, and 107 is read control. Circuit, 108 is a reproduction mode control circuit, 109 is a synchronization signal adding circuit, and 110 is an output terminal. Reference numerals 120 to 130 denote electric signals. Less than,
An outline of the operation will be described.

The memory 102 has a storage capacity capable of storing video signals for several scanning lines. The clock generation and synchronization separation circuit 103 receives the video signal 120 reproduced by the reproduction means 101 and outputs a clock signal and a horizontal synchronization signal 121 synchronized with the video signal 120. The writing clock signal is supplied to the writing circuit.
Not shown in FIG. The write control circuit 104 receives the horizontal synchronization signal 121 as an input, and every time the horizontal synchronization signal 121 is input, a predetermined address of the memory 102 is designated. After that, the video signal 120 is sequentially written to the memory 120 in order to write the video signal 120 to the memory 102. On the other hand, a signal 122 such as an address necessary for writing and a write enable is output. Accordingly, the reproduced video signal 120 is sequentially written into the memory 102 in units of scanning lines.

The clock generation circuit 105 generates a clock signal 123 having no fluctuation in frequency. Synchronous generation circuit 10
Reference numeral 6 denotes a field which counts the signal 123 as a clock to generate a horizontal synchronizing signal 124, generates a synchronizing signal 125 such as a horizontal synchronizing signal and a vertical synchronizing signal to be added to the video signal, and counts the number of regular scanning lines. It runs on a cycle and runs by itself. Self-propelled means that it is not synchronized from other parts. Therefore, in the normal playback mode,
A synchronizing signal and a read clock are generated at a field cycle in which the number of regular scanning lines is counted, and read control is performed. Note that the read-system clock signal 123 is also supplied to other circuits in the read system, but is not shown in FIG. The read control circuit 107 receives the horizontal synchronizing signal 124 as an input.
02, and the video signal 12
0 to be read from the memory 102 sequentially.
A signal 125 such as an address necessary for reading and a read enable signal is output for 0. Therefore, the memory 102
Thereafter, the video signal 126 is sequentially read out in units of scanning lines in synchronization with the synchronization generation circuit 106. Synchronous signal addition circuit 10
9 adds a synchronization signal 125 from the synchronization signal generation circuit 106 to the video signal 126 read from the memory 102, and outputs a video signal 127. Since the control circuit of the reading system uses the signal 123 having no fluctuation in frequency as a clock, the output video signal 127 has no time distortion.

The reproduction mode selection circuit outputs a reproduction mode signal 128 to the reproduction means 101. The reproduction mode signal 128 is also supplied to the synchronization generation circuit 106. In the normal reproduction mode, the frequency of the video signal 120 reproduced from the reproduction means 101 is almost a regular frequency. The reproduction means 101 receives the control signal 129 from the synchronization generation circuit 106 as input and controls the reproduction speed. For example, the average of the frequency and the phase of the field in the reproduced video signal is compared with the average of the frequency and the phase of the field in the synchronization generation circuit 106, and the reproducing speed of the reproducing means 101 is controlled so that the difference between them is reduced. When the video signal to be reproduced is a video signal recorded on a VTR, the reproduction speed of the reproducing means 101 can be controlled by changing the rotation speed of a head that reads the video signal of the VTR.

In the fast-forward playback mode or the reverse playback mode, unlike the normal playback mode, the video signal playback circuit does not perform control to change the playback speed according to the control signal from the synchronization generation circuit 106. The synchronization generation circuit 106 receives the clock generation and control signal 130 from the synchronization signal separation circuit 103 as input and does not circulate in the field cycle in which the number of regular scanning lines is counted, and is initialized in synchronization with the field cycle of the reproduction signal 120. During this period, only the horizontal synchronizing signal is output. Alternatively, the reproduction signal 120 may be circulated in a sufficiently long cycle as the number of scanning lines increases. Therefore, the synchronization generation circuit 106 generates a vertical synchronization signal following the increase or decrease in the number of scanning lines of the reproduction signal 120.

As a method of initialization in synchronization with the field period of the reproduction signal 120, a control signal 130 indicating a timing for adding a vertical synchronization signal is supplied from a clock generation and synchronization signal separation circuit 103 to the synchronization generation circuit 106.
Supply method. The control signal 130 indicating the timing for adding the vertical synchronizing signal may be the timing of the vertical synchronizing signal separated by the clock generation and synchronizing signal separating circuit 103, but may be any horizontal synchronizing signal that generates the vertical synchronizing signal. The timing may be before the synchronization period. If the vertical synchronizing signal is not supplied from the clock generation and synchronizing signal separation circuit 103, the timing of the vertical synchronizing signal of the reproduced video signal is not known. There is a possibility that a synchronization signal may be added. In this case, there is a case where a plurality of images are mixedly displayed on the screen. However, according to this embodiment, the control signal indicating the timing for adding the vertical synchronization signal is synchronized with the video signal to be specially reproduced or the vertical synchronization signal of the non-standard video signal. In addition, there is no problem described above, and it is possible to obtain a video signal on which time axis correction has been performed.

In the special reproduction mode, the clock generation and synchronization signal separation circuit 103 writes data into the memory 102 using a clock signal synchronized with the reproduction operation of the non-standard video signal, so that the frequency does not fluctuate. Since the reading from the memory 102 is performed by the clock signal 123, the write clock and the read clock are different. Therefore, when the memory 102 has only the storage capacity for two horizontal operation periods and the write clock is fast and the read clock is slow, the write operation may catch up with the read operation in some cases. It is not necessary to perform a complicated process, the read and the write may be reversed, and if the read operation is overtaken,
The reading operation may be performed while skipping the horizontal operation period.

By the above operation, a normal video signal output 127 synchronized with the self-running synchronization signal generating circuit 106 is obtained in the normal reproduction mode. In a special playback mode such as a fast-forward playback mode or a reverse playback mode, the playback signal 120
Can be obtained according to the increase or decrease in the number of scanning lines, but no time distortion occurs because the clock signal 123 having no fluctuation in frequency is used as a reference.

FIG. 2 is a circuit block diagram showing another embodiment of the present invention. 2, reference numeral 201 denotes a video signal recording / reproducing means for recording and reproducing a video signal; 202, a recording / reproduction mode control circuit for selecting a recording mode or a reproduction mode; 203, a switch; and 204, an input terminal. 220 to 223 are electric signals. Further FIG.
The same circuits, means and signals as those of the embodiment shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. Hereinafter, an outline of the operation will be described.

In the embodiment shown in FIG. 2, the present invention is also applied to recording of a video signal. The recording / reproduction mode control circuit 202 outputs a mode signal 223 indicating whether the mode is the recording mode or the reproduction mode to the video signal recording / reproduction means 201, the synchronization generation circuit 106, and the switch 203. The switch 203 receives the mode signal 223, selects the video signal input 221 from the input terminal 204 in the recording mode, and selects the video signal recording / reproducing means 201 in the reproduction mode.
From the video signal 220 reproduced from the
The signal 22 is output to the memory 102 and the clock generation and synchronization separation circuit 103. The subsequent operation of writing to the memory 102, the operation of reading from the memory 102, and the operation of adding synchronization are the same as those in the embodiment shown in FIG.

The video signal 127 read from the memory 102 and added with the synchronization signal is output to the output terminal 110 and the video signal recording / reproducing means 201. In the recording mode, the video signal 127 is used as the video signal recording / reproducing means 201.
Recorded by

Therefore, by the above operation, at the time of recording, the video signal 221 from the input terminal 204 is time-corrected and recorded in the video signal recording / reproducing means 201. The input video signal 221 is a regular video signal. Not necessarily.
Therefore, at the time of recording, as in the first embodiment, the synchronization generation circuit 106 outputs only the horizontal synchronization signal without circulating in the field cycle in which the number of regular scanning lines is counted. Alternatively, the reproduction signal 120 may be circulated in a sufficiently long cycle as the number of scanning lines increases. The synchronization signal generation circuit 106 receives the clock and the control signal 130 from the synchronization signal separation circuit 103 as inputs, and is initialized in synchronization with the field period of the input video signal 221. That is, a vertical synchronizing signal synchronized with the input video signal 221 is generated. The control signal 130 is, as in the first embodiment,
This signal indicates the timing for adding the vertical synchronization signal.

On the other hand, since the video signal 220 recorded by the above-described recording method is almost a regular video signal, the video signal recording / reproducing means 201 transmits the video signal from the synchronization generation circuit 106 as in the embodiment shown in FIG. The control signal 129 is input to control the reproduction speed. For example, the average of the frequency and the phase of the field in the reproduced video signal is compared with the average of the frequency and the phase of the field in the synchronization generation circuit 106, and the reproduction speed of the video signal recording / reproducing means 201 is reduced so that the difference between the two becomes small. Control.

According to the above-mentioned operation, in this embodiment, the recording can be performed by correcting the time distortion even for the input of an illegal video signal. If the correction circuit is also used as a correction circuit at the time of reproduction, the cost of the system can be reduced.

[0028]

According to the present invention, even when the frequency of the reproduced video signal or the number of scanning lines is significantly different from the normal frequency or the number of scanning lines, the time distortion can be corrected.

Further, according to the present invention, it is possible to use the time correction means used at the time of reproduction also at the time of recording to correct the time distortion with respect to an irregular video signal input and perform recording.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention.

FIG. 2 is a circuit block diagram showing another embodiment of the present invention.

[Explanation of symbols]

101: video signal reproducing means, 102: memory, 103 ...
Clock generation and synchronization separation circuit, 104: write control circuit, 105: clock generation circuit, 106: synchronization generation circuit, 107: read control circuit, 108: reproduction mode control circuit, 109: synchronization signal addition circuit, 110: output terminal.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eiji Moro 1410 Inada, Hitachinaka-shi, Ibaraki Pref. Digital Media Products Division, Hitachi, Ltd. F-term (reference) of Digital Media Products Division of Manufacturing Works 5C053 FA21 GB04 HA01 HA21 HC02 HC06 JA26

Claims (8)

[Claims] 1. A video signal reproducing means for reproducing a video signal from a recording medium, a storage means for storing a video signal, and a first synchronizing signal generating means for generating a synchronizing signal synchronized with the video signal from the reproducing means A second synchronization signal generation unit; a write control unit that writes a video signal from the video signal reproduction unit to the storage unit in synchronization with a synchronization signal generated by the first synchronization signal generation unit; Reading control means for reading out the video signal stored in the storage means in synchronization with the second synchronization signal generating means. In the first operation mode, the video signal reproducing means runs the video signal reproduced by itself. Synchronizing the video signal reproducing means in synchronization with the synchronizing signal generated by the second synchronizing signal generating means. In the second operation mode, the synchronizing signal generated by the second synchronizing signal generating means is synchronized. A second synchronizing signal generating means for synchronizing the second synchronizing signal with the synchronizing signal from the first synchronizing signal generating means. 2. The video signal reproducing apparatus according to claim 1, wherein said two operation modes are switched according to a reproduction mode of said video signal reproducing means. 3. The video signal reproducing device according to claim 1, wherein the horizontal frequency of the video signal reproduced by the video signal reproducing means and the number of scanning lines in one field are substantially the same as the normal horizontal frequency and one field. In the case of the reproduction mode in which the number of scanning lines is reproduced, the first operation mode is selected, and the horizontal frequency of the video signal reproduced by the video signal reproducing means or the number of scanning lines in one field is a regular horizontal line. A video signal reproducing device, wherein the second operation mode is selected in a reproduction mode in which reproduction is performed at a frequency different from the number of scanning lines in one field. 4. The video signal reproducing apparatus according to claim 1, wherein in the first operation mode, the second synchronizing signal generating means counts a normal horizontal frequency and the number of scanning lines in one field. In the second operation mode, the second synchronizing signal generating means is driven by a signal from the first synchronizing signal generating means.
A video signal reproducing apparatus, wherein synchronization is performed at a field cycle. 5. A video signal recording means for recording a video signal on a recording medium; a video signal reproducing means for reproducing a video signal from the recording medium; a storage means for storing a video signal; Selecting means for selecting and outputting a signal, and selecting and outputting a video signal from the reproducing means at the time of reproduction; first synchronizing signal generating means for generating a synchronizing signal synchronized with the video signal from the selecting means; A second synchronization signal generation unit; a write control unit that writes a video signal from the selection unit to the storage unit in synchronization with a synchronization signal generated by the first synchronization signal generation unit; Reading control means for reading out the video signal stored in the storage means in synchronization with the signal generation means and supplying the read out video signal to the video signal recording means; The second synchronizing signal generating means is synchronized so that the synchronizing signal generated by the generating means is synchronized with the synchronizing signal generated by the first synchronizing signal generating means. In the reproduction mode, the video signal reproducing means reproduces. A video signal recording / reproducing apparatus which synchronizes the video signal reproducing means so as to synchronize the video signal with a synchronizing signal generated by the second synchronizing signal generating means which runs by itself. 6. The video signal recording / reproducing apparatus according to claim 5, wherein in the reproducing mode, the second synchronizing signal generating means is free-running so as to count a regular horizontal frequency and the number of scanning lines in one field. In the recording mode, the second synchronization signal generating means is synchronized with a signal from the first synchronization signal generating means at a one-field cycle. 7. A video signal reproducing means for reproducing a video signal from a recording medium; a storage means for storing a video signal output from the video signal generation circuit; and a video signal output from the video signal reproduction circuit. First synchronizing signal generating means for generating a synchronized signal, second synchronizing signal generating means, and a video signal from the video signal reproducing means in synchronization with the synchronizing signal generated by the first synchronizing signal generating means And a read control unit for reading a video signal stored in the storage unit in synchronization with the second synchronization signal generation unit, wherein a video reproduced by the video signal reproduction circuit is provided. When the horizontal frequency of the signal or the number of scanning lines in one field is different from the normal horizontal frequency or the number of scanning lines in one field, the first synchronizing signal generation circuit A signal indicating the vertical scanning cycle of the video signal output from the second synchronization signal generating circuit is supplied to the second synchronization signal generation circuit, and the vertical scanning cycle of the second synchronization signal generation circuit is synchronized with the first synchronization generation circuit. A video signal reproducing device characterized by the above-mentioned. 8. A video signal recording means for recording a video signal on a recording medium; a storage means for storing a video signal; and a first synchronization signal generation for generating a synchronization signal synchronized with the video signal input from the outside. Means, second synchronizing signal generating means, writing control means for writing the video signal input from the outside into the memory in synchronization with a synchronizing signal generated by the first synchronizing signal generating circuit, Read-out control means for reading out the video signal stored in the memory in synchronization with the synchronizing signal generation circuit and supplying the video signal to the video signal recording circuit, wherein the horizontal frequency of the video signal supplied from the outside or one field If the number of scanning lines is the regular horizontal frequency or 1
By supplying a signal indicating a vertical scanning cycle of a video signal input from the outside from the first synchronization signal generation circuit to the second synchronization signal generation circuit when the number of scanning lines in the field is different from the number of scanning lines, A video signal recording apparatus, wherein a vertical scanning cycle of a second synchronization signal generation circuit is synchronized with a vertical scanning cycle generated by the first synchronization signal generation circuit.