JPS61234679A - Signal processing device for video signal - Google Patents

Abstract

PURPOSE:To compensate the levels of all reproduced video signals by detecting the drop-out position of level compensation data and inserting data before or after the drop-out position to this position. CONSTITUTION:A level compensation data string is generated from a reference index signal data string and a reproduced index signal data string by a level compensation data generating circuit 4 and is stored in a storage circuit 5 with the reproduced index signal data string as the address. The position where level compensation data is not recorded due to address discontinuity is detected and the data of one address before or after is inserted to this position to generate a level compensation data string corresponding to all reproduced signal data. Level compensation data is read out from the circuit 5 with reproduced video signal data subjected to level compensation as the address and is supplied to a reproduced video signal level compensating circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to converting a video signal into F when recording and reproducing the video signal.
Nonlinear distortion of the playback level, gain fluctuations, and D
The present invention relates to a signal processing device having a function of automatically correcting C variation.

Conventional Technology When a video tape recorder (hereinafter referred to as VTR) records and plays back video signals on a magnetic tape, it generally converts at least the luminance signal into an FM signal before recording and playing back, so an FM modulator, FM demodulator, etc. are required. I will intervene. These FM modulators and FM demodulators are required to have a proportional or inversely proportional relationship between signal level and frequency, but in reality, nonlinear distortion of several coefficients often occurs. DC fluctuations due to fluctuations in the gain of the twisted amplifier and fluctuations in the clamp potential also occur. However, with conventional VTRs, almost no measures have been taken to proactively eliminate the above-mentioned problems, which has been an obstacle to improving the quality of reproduced images.

Problems to be Solved by the Invention As described above, in actual FM modulators and FM demodulators, non-linear distortion of several orders of magnitude often occurs, resulting in whitening or darkening of the luminance signal. This poses a problem in broadcast VTRs where dubbing is performed several times during editing, as the non-linear distortion is accumulated each time dubbing is performed, resulting in deterioration of image quality. Furthermore, when a video signal is divided into multiple channels of video signals using methods such as frequency division 9 time axis extension, Hadamard transform, and dot division for recording and playback, not only the above-mentioned nonlinear distortion but also the amplifier caused by the division occur. There is a problem in that characteristics between channels become unbalanced due to gain fluctuations due to variations in characteristics, DC fluctuations due to shifts in clamp potential, etc., resulting in line crawling and changes in frequency characteristics in the reproduced video signal, greatly deteriorating the image quality of the reproduced video.

Means for Solving the Problems The present invention solves the above-mentioned problems by inserting and recording a reference index signal within the vertical blanking period of the video signal during recording and reproducing the video signal. , means for generating level correction data by extracting a reproduced index signal within a vertical blanking period of a reproduced video signal, and comparing a data sequence obtained by A/D converting the reproduced index signal with a data sequence representing the reference index signal; , storage means for storing the level correction data using the reproduction index signal data string as an address; means for detecting a location where the level correction data is not stored, which is caused by address discontinuity caused by the shape of the reproduction index signal; Means for inserting data one address before or after the detected location to create level correction data corresponding to playback signal data of all levels, and means for level correction of the playback video signal based on the data. This is a signal processing device for video signals.

According to the present invention, the above-described configuration automatically corrects non-linear distortion, gain fluctuations, and DC fluctuations of a recording/reproducing device such as a VTR, and corrects white smearing, black smearing, and channel correction in the case of split recording and reproducing. It is possible to prevent various deteriorations in reproduced image quality such as line crawling due to unbalanced characteristics between images.

That is, after each of the reference index signal and reproduction index signal is converted into digital quantities, the two data strings are compared to create level correction data for level correction, and the level is adjusted using the reproduction index signal data string as an address. Store the correction data in the storage device. At that time, the shape of the signal waveform itself selected as the reference index signal and the address discontinuity caused by waveform distortion of the reproduced index signal received during recording and reproduction, etc., cause the level correction data to be unstored. By inserting data one address before or after the location, level correction data corresponding to the reproduced signal data of all levels is created. By correcting the level of the reproduced video signal based on the data, deterioration of the reproduced image quality can be prevented.

Embodiment In this embodiment, a level correction method is used in which the difference between the reference index signal and the reproduction index signal is used as a level correction value, and the level correction value is added to the reproduction video signal. Further, as the reference index signal, a ramp signal covering the levels from the black level to the white level of the video signal is used. FIG. 2 shows a waveform diagram for explaining the basic operation of the above system. In FIG. 2 (7), 1 is a reference index signal, and 2 is a reproduction index signal obtained by inserting the reference index signal 1 into the vertical blanking period of the video signal, recording it on a recording medium, and reproducing it again. It is. The levels of the reference index signal 1 and the reproduced index signal 2 are compared, and a level difference A indicated by diagonal lines in FIG. 2(A) is detected. The level correction value 3 indicates this level difference A on the horizontal axis and the level of the reproduction index signal 2 on the vertical axis. The level of the reproduced video signal is corrected in accordance with the level correction value 3 indicating the amount of level change accompanying this recording and reproduction. For example, if the video signal is at the B level, level correction is performed by reading out the level correction value C corresponding to the B level in the level correction value 3 and adding it to the reproduced video signal.

A block diagram of one embodiment of the present invention is shown in FIG.

A level correction data generation circuit 4 creates a level correction data sequence from the reference index signal data sequence and the reproduction index signal data sequence converted into digital quantities, and stores it in the storage circuit 5 with the reproduction index signal data sequence as an address. Next, the detection circuit 6 and data correction circuit 7 generate level correction data caused by address discontinuity caused by the shape of the signal waveform itself selected as the reference index signal and waveform distortion of the reproduced index signal received during recording and reproduction. An unrecorded location is detected, and data from one address before or after the detected location is inserted to create a level correction data string corresponding to reproduced signal data of all levels. Using the reproduced video signal data whose level is to be corrected as an address, level correction data corresponding to the level of the reproduced video signal data is read from the storage circuit 5, and the reproduced video signal level correction circuit 8 reads it and the reproduced video signal data. By adding them, level-corrected reproduced video signal data is obtained.

FIG. 1 shows a block diagram for explaining an embodiment of the present invention in more detail. In FIG. 1, first, the switch 14 is set to the B side and the switch 15 is set to the B side, addresses are counted by the address generator 16, and data ○ is stored in the sub storage circuit 11, that is, initialized.

Next, the switch 12 is set to the B side, the switch 13 is set to the A side, the difference between the signal data and the reproduction index signal data is taken as level correction data, and this is set as the reproduction index signal data as an address, and the main memory circuit 10 and the sub memory circuit 1
Store it in 1.

Next, set the switch 12 to the A side, the switch 13 to the B side, and the switch 16 to the B side, count the addresses with the address generator 16, and read out the data stored in the main memory circuit 1o and the sub memory circuit 11. . However, main memory circuit 1
The address of o is delayed by one address than the address of the sub-memory circuit 11 by the delay circuit 17, and therefore the output data is also read out with a delay of one data from the output data of the sub-memory circuit 11. At this time, the sub memory circuit 1
1, where the level correction data was not stored due to the discontinuity of the playback index data string, which was used as the address when storing the data, data 0 is stored in advance, so the output data value of the storage circuit is The storage location indicated by the address when the value becomes 0 is the location where the level correction data is not stored.

0 data detector 1 while reading the data of the 1 o beno storage circuit.
8, it is determined whether the output data of the sub-memory circuit 11 is 0 or not. If the data is 0, the 0-data detector 18 generates a data latch signal, and the value of the output data of the main memory circuit 1o at that time is determined. The data is latched by the data latch circuit 2o. Since the data read address of the main memory circuit 1o is delayed by one address than the data read address of the sub memory circuit 11, this latched data is stored one address earlier than the address of the location where the level correction data is not stored. This is the data indicated by the address.

Then, after the address generator 16 counts only one address from the above state, a data write pulse is sent from the write pulse generator 19 to the main memory circuit 1o, and is sent to the data latch circuit 20 to the location where the level correction data is not stored. The latched data, that is, the data indicated by the address immediately before the address of the unstored location is stored.

If the address generator 16 performs the above correction operation while counting addresses to cover the level of the playback index data, level correction corresponding to the playback video signal data having all levels within the level of the playback index data can be performed. You can create data columns.

Finally, the switch 13 is set to the C side, the level correction data corresponding to the level is read out from the main memory circuit 1o using the reproduced video signal data as an address, and the adder 21 adds this level correction data and the reproduced video signal data. By combining, level-corrected reproduced video signal data is obtained.

As mentioned above, this device eliminates non-linear distortion due to FM modulation and demodulation during recording and reproduction of video signals, gain fluctuations, and DC
Fluctuations can be corrected and a high-quality reproduced video signal can be obtained.

If the level correction data is missing due to the waveform of the reproduction index signal, data before or after the missing location can be inserted as a substitute.
Data missing locations can be detected and replacement data inserted at the same time, and data correction can be performed relatively easily and at high speed.

Effects of the Invention According to the present invention, non-linear distortion caused by FM modulation and FM demodulation when recording and reproducing a video signal, and amplifier gain that occurs when recording and reproducing a distorted video signal by dividing it into a plurality of channels. Since it is possible to remove DC fluctuations due to fluctuations and shifts in clamp potential, it is possible to combine the reproduced video signals of multiple channels to create the original reproduced video of one channel. When the signal is restored, it is possible to obtain a high-quality reproduced video signal without line crawling, etc., which occurs due to unbalanced characteristics between channels. To solve the problem that level correction data is missing due to the shape of the waveform itself selected as the reference index signal and the waveform distortion of the reproduced index signal received during recording and playback, the missing location can be detected and 13, or by inserting later data into that location. This allows level correction of reproduced video signals of all levels.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining in detail an embodiment of the present invention, Fig. 2 is a waveform diagram for explaining the basic operation of the present invention, and Fig. 3 is a block diagram showing an embodiment of the present invention. It is. 1...Reference index signal, 2...
Reproduction index signal, 3...Level correction value,
4...Level correction data creation circuit, 5...
...Memory circuit, 6...Detection circuit, 7...
・Data correction circuit, 8... Playback video signal level correction circuit, 9... Subtractor, 10... Main memory circuit, 11... Sub-memory circuit , 12, 13° 14.15...Switch, 16...-address generator, 17...Delay circuit, 18...
...0 data detector, 19...write pulse generator, 20"-"°° data latch circuit, 21...
...Adder.

Claims (1)

[Claims] In recording and reproducing video signals, a reference index signal is inserted and recorded within the vertical blanking period of the video signal at the time of recording, and during playback, the reproduction index signal within the vertical blanking period of the reproduced video signal and the reference inserted at the time of recording are recorded. A video signal recording and reproducing apparatus that determines a level correction value for level correction by comparing the level correction value with an index signal, and reproduces the original video signal by level-correcting the reproduced video signal according to the level correction value, the apparatus comprising: means for generating level correction data from a data string obtained by converting the index signal and the reproduced index signal into digital quantities; storage means for storing the level correction data using the reproduced index signal data string as an address; The means includes a means for detecting a location where level correction data is not stored due to address discontinuity caused by the shape of the reproduction index signal, and a means for inserting data one address before or after the detected location so that all levels are 1. A signal processing device for a video signal, comprising means for generating a level correction value corresponding to a reproduced signal of 1, and level-corrects a reproduced video signal of all levels.