JPH03220884A - Level correction device for video signal - Google Patents

Abstract

PURPOSE:To attain level correction with high accuracy by adding sequentially a level change data to a just preceding data when missing takes place in a data of a reproduction reference signal and sending a data of the reproduced reference signal subject to addition processing for each addition to a level correction data generating means. CONSTITUTION:When a reproduction reference signal is missing due to dropout or the like, a level change data generated by a data arithmetic circuit 10 based on a reference signal data is added to a reproduced reference signal data just before missing via a latch 6 and inputted to a level correction data generating circuit 7 and written to an address succeeding to an address in which a data just before missing is written. Moreover, the above interpolation data is inputted to the level correction data generating circuit 7 and led again to an adder 11 and a succeeding level change data outputted from the data arithmetic circuit 10 is added. Thus, the continuity before and after the missing part is remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in a video recording and reproducing device such as a VTR, and is used to generate a reproduced video signal based on a reference signal inserted into a part of the recorded video signal. The present invention relates to a level correction device for a video signal that corrects the level.

[Conventional technology]

In video recording and playback devices such as VTRs, mainly FM
In analog transmission systems such as modulation/demodulation circuits, tape running systems, and head systems, DC offset, nonlinear distortion,
Alternatively, when multiple channel recording is performed, waveform distortion may occur due to gain between channels.

Therefore, conventionally, as a means to remove such waveform distortion, a reference signal is inserted into a part of the recorded video signal sequence (for example, during the blanking period), and the reference signal extracted during playback, that is, the playback reference signal, is converted into the original. A method has been proposed that performs level conversion to return the signal to the same level as the reference signal. In this method, a level correction table in which the level correction data obtained from the playback reference signal and the playback video signal data correspond to each other is created in a dedicated memory, and this level correction table is used to correct the level of the playback video signal. is now being carried out.

However, with the above method, if the reproduced reference signal becomes discontinuous due to the influence of noise etc., the level correction data in the level correction table corresponding to the missing part will have no correlation with the adjacent data. There was a risk that the level correction would not be performed correctly. Therefore, in order to avoid such inconveniences, a video signal level correction device as described below has been proposed.

In the video signal level correction device shown in FIG. 2, reproduced video signal data obtained by converting an analog reproduced video signal into digital data is manually inputted to an input terminal 21. The reproduced video signal data is a gate signal from the reproduced reference signal detection circuit 23 by the gate circuit 22, and the digital data of the reproduced reference signal is extracted as reproduced reference signal data. This reproduction reference signal data is used by the level correction data generation circuit 24 as level data on which the level correction data is based.
and is temporarily stored in the memory of the level correction data generation circuit 24. This level correction data generation circuit 24 generates a reference signal and a reproduction reference signal from the data of the reference signal (same as the reference signal inserted at the time of recording) outputted from the reference signal generation circuit 25 and the reproduction reference signal data. Level correction data is generated by determining the level difference.

By the way, during the blanking period when the reproduction reference signal of the reproduced video signal exists, the switch 26 is controlled by the reproduction reference signal detection circuit 23 so that the level correction data generation circuit 2
4 side, the address signal output from the level correction data generation circuit 24 is input to the level correction memory 27 via the switch 26. This address signal is generated such that the level correction data corresponds to appropriate reproduced video signal data one by one. Therefore, in the level correction memory 27, the level correction data is written to the address corresponding to the address signal, thereby creating a level correction table in which the reproduced video signal data and the level correction data correspond.

On the other hand, during the non-blanking period (video signal period) of the reproduced video signal, the reproduced video signal data is transferred to the level correction memory via the switch 26 whose connection is switched to the input terminal 21 side under the control of the reproduction reference signal detection circuit 23. 27 people will be employed. Then, the level correction data held in the level correction memory 27 is read out at the corresponding address using the input reproduced video signal data as an address signal, and is outputted to the output terminal 28. Then, level correction of the reproduced video signal is performed by adding the level correction data thus obtained to the reproduced video signal data and converting it into analog data.

In the level correction device described above, when reproduction reference signal data is missing due to noise or the like, reproduction reference signal data corresponding to immediately before the missing portion is generated from a plurality of consecutive addresses starting from the address written in the memory in the level correction data generation circuit 24. It is designed to be written successively to the address of .

In this way, missing reproduction reference signal data is interpolated by replacing it with the immediately preceding data.

[Problem to be solved by the invention]

However, with the above conventional technology, although it is possible to interpolate missing reproduction reference signal data with the data immediately before it, when a signal whose level changes, such as a ramp signal, is inserted as a reference signal into the recorded video signal, However, even if the above-mentioned interpolation processing is applied to the reproduction reference signal data in which the missing reproduction reference signal data has occurred, the reproduction reference signal data is not reproduced correctly. That is, in the above-mentioned interpolation processing, the data immediately before the missing portion of the reproduction reference signal data is used, so that the interpolated portions are aligned at the same level. Therefore, if a dropout occurs in a portion of the reproduction reference signal data where the level is changing, the reproduction reference signal data will not change continuously before and after the omission. When a large number of missing portions occur, this phenomenon becomes most noticeable, and it becomes almost impossible to reproduce the reproduced reference signal data.

In this way, with conventional video signal level correction devices, when interpolating playback reference signal data whose level changes with the data immediately before the missing part, the reproducibility of the playback reference signal data deteriorates significantly. It was difficult to perform level correction.

[Means to solve the problem]

In order to solve the above problems, the video signal level correction device according to the present invention includes a reproduction reference signal extraction means for extracting a reference signal inserted into a part of a recorded video signal sequence during recording as a reproduction reference signal during reproduction. , a level correction data generation means for generating level correction data by determining the difference in level between a reference signal that is the same as the reference signal inserted during recording and a reproduction reference signal; and a level correction data generating means that corresponds to reproduction video signal data. A level correction device for a video signal, comprising a level correction data holding means for holding the level correction data in a state where the
It is characterized by being configured as shown below.

Level change data generation means for generating data regarding changes in the level of the reproduction reference signal based on changes in the level of the reference signal, and when data of the reproduction reference signal is missing;
The level change data is sequentially added to the immediately preceding data, and addition means is provided for sending the data of the reproduced reference signal subjected to addition processing to the level correction data generation means for each addition.

[For production]

According to the above configuration, when data in the reproduction reference signal is missing due to discontinuity in the reproduction reference signal, the level change data output from the level change data generation means is added to the reproduction data immediately before the missing part by the addition means. It is added to the reference signal data, and the reproduced reference signal data subjected to the addition process is sent to the level correction data generation means. The level change data is again added to the reproduction reference signal data and sent to the level correction data generating means. By repeating such processing, the level correction data generation means is sequentially inputted with the data of the reproduction reference signal including level change data corresponding to each one, and interpolation of the missing portion is performed.

In this way, since the reproduction reference signal data supplemented with the level change data is used for interpolation of the reproduction reference signal data, a signal whose level changes, such as a ramp signal, is inserted into the recorded video signal sequence as a reference signal. Even in the case where the reproduction reference signal is reproduced with high fidelity, the interpolation process described above makes it possible to reproduce the data of the reproduction reference signal with high fidelity.

〔Example〕

An embodiment of the present invention will be described below based on FIG.

As shown in FIG. 1, reproduced video signal data obtained by digitizing an analog reproduced video signal is input from the input end of the video signal level correction device, and is sent to one terminal of a gate circuit 2 and a switch 4. Sent out. Note that during recording, a reference signal is inserted in advance into the blanking period of the recorded video signal sequence, and the reproduced video signal is a reproduction of the recorded video signal.

The gate circuit 2 serving as reproduction reference signal extraction means is a circuit that extracts reproduction reference signal data from the blanking period of reproduced video signal data using a gate signal output from the reproduction reference signal detection circuit 3. The reproduction reference signal detection circuit 3 is a circuit that generates the gate signal and sends it to the gate circuit 2 based on the blanking period of the reproduced video signal. Further, the reproduction reference signal detection circuit 3 connects the input terminal 1 to the address input of the level correction memory 9 (described later) during the blanking period, and connects the input terminal 1 to the address input of the level correction data generation circuit 7 (described later) during the non-blanking period. It has a function of controlling switching of the switch 4 so as to connect the output and the address input of the level correction memory 9.

The reproduction reference signal data output from the gate circuit 2 is input to the lunch 6 via the buffer 5. The reproduction reference signal data is temporarily held by the latch 6 and sent to the level correction data generation circuit 7 at a predetermined timing. The level correction data generation circuit 7 as a level correction data generation means has a memory, and sequentially writes the reproduction reference signal data as level data of the reproduction reference signal into appropriate addresses of the memory, and also writes the reproduction reference signal data and the reference This circuit generates level correction data by determining the difference in level between both signals from the reference signal data output from the signal generation circuit 8. Further, the level correction data generation circuit 7 outputs an address signal when writing the level correction data to the level correction memory 9. This address signal is generated such that the level correction data corresponds to appropriate reproduced video signal data one by one.

The reference signal generation circuit 8 is a circuit that generates the same reference signal as the reference signal inserted into the recorded video signal sequence during recording as digital reference signal data. Reference signal generation circuit 8
The reference signal data output from the data calculation circuit 10
is also entered. The data calculation circuit IO, which serves as a level change data generation means, calculates level change data indicating how much a certain reproduction reference signal has increased or decreased from the immediately preceding reproduction reference signal, based on the reference signal data. This is the circuit that generates it.

The level change data output from the data calculation circuit 10 is input to the adder 11. The adder 11 serving as an adding means is a circuit in which the reproduction reference signal data that has passed through the latch 6 is input manually, and adds the level change data to the reproduction reference signal data and outputs the result. Adder 1
The addition-processed reproduction reference signal data output from 1 is
It is input to the lunch 6 via the buffer 12. Therefore,
The above addition-processed reproduction reference signal data is stored in buffer 1.
2, the level change data is sequentially added in a loop formed by the latch 6 and the adder 11, and is input to the level correction data generation circuit 7 for each addition.

The level correction data output from the level correction data generation circuit 7 is sent to the level correction memory 9, while the address signal output from the same level correction data generation circuit 7 is sent to the other terminal of the switch 4. be done. The level correction memory 9 as a level correction data holding means is
By writing the level correction data to an address corresponding to the address signal, a level correction table in which the reproduced video signal data and the level correction data correspond is created. Further, when the reproduced video signal data is input, the level correction memory 9 uses this as a read address signal to read out the level correction data and output it to the output terminal 13.

In the above configuration, when reproduced video signal data is input to the input terminal 1, the gate circuit 2 extracts the reproduced reference signal data existing in the blanking period of the reproduced video signal data. This reproduced AL signal data is passed through a buffer 5 and a latch 6 to a level correction data generation circuit 7.
The level correction data calculation circuit 7 inputs the data manually and writes it to a certain address in the memory in the level correction data calculation circuit 7. Then, the level correction data generation circuit 7 generates level correction data from the reproduced reference signal data and the reference signal data from the reference signal generation circuit 8.

At this time, since the switch 4 connects the level correction data generation circuit 7 and the level correction memory 9, the address signal output from the level correction data generation circuit 7 is input to the level correction memory 9. Then, the level correction data output from the level correction data generation circuit 7 is written to the address corresponding to the address signal of the level correction memory 9, and a level correction table is created.

Here, when the reproduced video signal data of the non-blanking period is manually input from the input terminal 1, the switch 4 connects the input terminal 1 and the level correction memory 9, so that the reproduced video signal data is stored in the level correction memory. Input as address signal. As a result, the level correction data held as a level correction table is sequentially read out and output to the output terminal 13. Then, level correction is performed on the reproduced video signal data by adding corresponding level correction data.

By the way, when the reproduction reference signal data is missing due to dropout or the like, the reproduction reference signal data immediately before the omission after passing through the latch 6 is generated by the data calculation circuit IO based on the reference signal data from the reference signal generation circuit 8. level change data is added. Further, this reproduction reference signal data is input as interpolation data to the level correction data generation circuit 7 via the buffer 12 and the latch 6, and the data immediately before the above-mentioned loss in the memory in the level correction data calculation circuit 7 is written. will be written to the address following the current address. Also, the above interpolated data is
The data is input to the level correction data generation circuit 7, and is again led to the adder 11, where the next level change data output from the data calculation circuit 1O is added.

In this way, during the period when the playback reference signal data is missing, the level change data is sequentially added to the playback reference signal data as described above, and the playback reference signal data subjected to the addition process is level-corrected each time. Since the data is input as interpolation data to the data generation circuit 7, the level correction data generation circuit 7 interpolates the continuously changing reproduction reference signal data into the missing portion of the reproduction reference signal data. Therefore, when a signal whose level changes, such as a ramp signal, is inserted into the recorded video signal string, even if a loss occurs in the playback reference signal data, the missing portion is interpolated with interpolation data of the same level. Furthermore, the continuity of data before and after the missing part can be greatly improved.

〔Effect of the invention〕

As described above, the video signal level correction device according to the present invention includes a level change data generation means for generating data regarding a change in the level of a reproduction reference signal based on a change in the level of the reference signal, and a level change data generation means for generating data regarding a change in the level of a reproduction reference signal. addition means for sequentially adding the level change data to the immediately preceding data when a loss occurs in the data, and sending the data of the reproduced reference signal subjected to addition processing to the level correction data generation means for each addition; This configuration has the following features.

As a result, if data loss occurs in the reproduction reference signal,
The level change data is sequentially added to the previous data, and the reproduction reference signal data subjected to the addition process is input to the level correction data generation means for each addition. Even when a signal whose level changes, such as a ramp signal, is inserted into the video signal sequence as a reference signal, the data of the reproduced reference signal can be reproduced with high fidelity. Therefore, by generating level correction data using this playback reference signal data, it becomes possible to perform level correction of the playback video signal more accurately, and it is possible to improve the image quality of the playback video image. be effective.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and is a block diagram showing the configuration of a main part of a video signal level correction device. FIG. 2 shows a conventional example, and is a block diagram showing the configuration of the main parts of a video signal level correction device. 2 is a gate circuit (reproduction reference signal extraction means), 3 is a reproduction reference signal detection circuit, 7 is a level correction data generation circuit (level correction data generation means), 8 is a reference signal generation circuit, 9 is a level correction memory (level correction data retention means), 10
is a data calculation circuit (level change data generation means), 11
is an adder (addition means).

Claims (1)

[Claims] 1. Reproduction reference signal extraction means for extracting a reference signal inserted into a part of a recorded video signal sequence during recording as a reproduction reference signal during reproduction, and a reference signal that is the same as the reference signal inserted during recording. and a level correction data holding means for holding the level correction data in correspondence with the playback video signal data. A video signal level correction device comprising: level change data generation means for generating data regarding a change in the level of the reproduction reference signal based on a change in the level of the reference signal;
Adding means for sequentially adding the level change data to the immediately preceding data and sending the data of the reproduced reference signal subjected to addition processing to the level correction data generating means for each addition. Features: Video signal level correction device.