KR19990028189A - Video signal recording method - Google Patents

Abstract

Disclosed is an object of the present invention to provide a video signal recording method capable of reliably recording a video signal in a predetermined format from an initial recording stage in a video signal recording apparatus for intermittently recording a video signal. According to the present invention, a signal of a predetermined format is recorded in the magnetic tape 7 in DVC format in advance, and a predetermined signal of the DVC format previously recorded in the magnetic tape 7 is detected at the time of recording the video signal, and image data on a signal of the predetermined format is detected. The video signals to be recorded in the recording area are sequentially overwritten. Accordingly, the present invention can reliably record the video signal to be recorded from the beginning to the end without disturbing the image, and can provide a high quality image even by intermittent proxy prevention.

Description

Video signal recording method

The present invention relates to a video signal recording method, and more particularly, to a video signal recording method in a video signal recording apparatus for intermittently recording a video signal.

Security cameras are installed in the banks and stores and in garages. Normally, an image captured by a surveillance camera is recorded in a VTR and can be reproduced as necessary.

24 hours of surveillance is required for the VTR for recording the image | photographed with such a surveillance camera. However, in the current VHS type VTR, only up to 9 hours of recording time is required, so that switching of the VTR, changing of the tape cassette, etc. are required, and the operability is poor.

Furthermore, in such a VTR, there is no need to record a moving picture when there is no problem in security, that is, when no person or the like is present and there is no motion on the screen. Therefore, as a VTR for recording a surveillance video, a so-called Time Lapse VTR, which greatly increases the time that can be recorded on a tape cassette by fragmenting the video signal recorded on the tape cassette, is often used. have.

In the time-lapse VTR, a method of intermittent recording while transmitting a magnetic tape at a speed corresponding to the length of a long time recording or a method of recording a video signal with the tape running stopped for each field of the video signal is used.

In the case of the normal VTR, it is not necessary to shift to the second recording operation immediately after the end of the recording operation, but when the second recording operation is performed, it takes some time and after the rotational speed of the drum and the tape running speed reach the prescribed speeds together. In this case, it is sufficient to execute the recording by shifting to the recording operation.

However, in the time-lapse VTR, intermittent recording is performed by repeating recording and stopping operations at short intervals. As a result, tape running is likely to be unstable. On the other hand, the VTR records the video signal on the magnetic tape in a predetermined format.

The format is mainly determined by the tape running speed and the rotating speed of the rotating drum to which the magnetic head is fixed. As a result, if tape running is unstable, the format may deviate and playback may not be possible. Therefore, stabilization of the initial speed of the tape running system and the drum drive system becomes important.

FIG. 4 is a diagram for explaining the format of the DVC, showing a format in which one recording track recorded in the DVC is viewed from the side where the magnetic head is scanned.

The magnetic head is scanned onto the magnetic tape from the lower side to the upper side of the recording track, that is, in the direction of the arrow. Blank areas are provided on the upper and lower ends of the magnetic tape. This area has a width of 0.55 mm at the top and a width of 0.56 mm at the bottom. Furthermore, a new recording track can be formed in this upper and lower regions toward the longer side, that is, in the direction of the arrow, of the magnetic tape.

In addition, the recording track is recorded at an angle in the center width of 5.240 mm. In the recording track, the insert data, track information, audio data, video data, and subcode data are sequentially recorded through a gap. Auxiliary (AUX) data is recorded in the audio data and the video data.

The AUX data of the sub code data, audio data and video data has a configuration capable of recording data other than audio and video data such as recording date and time. Information about the audio other than the audio data is written in the AUX data of the audio data section, and information about the video other than the video data is written into the AUX data of the video data section.

The insert data is data used as a reference when detecting portions recording video data, audio data, and subcode data, respectively. By calculating the predetermined timing after detecting the insert data, data of each of the recorded video data, audio data, and subcode data is detected. The track information is information for confirming the track width specification.

Moreover, azimuth recording is performed in the recording track to prevent crosstalk with adjacent recording tracks.

For example, if two recording heads are installed in a rotating drum with a diameter of 21.7 [mm] at intervals of 180 °, recording of one track and two tracks is performed. To obtain a DVC format, the winding angle is 174 ° and the drum rotation speed is set. It is set to 9000 [rpm]. At this time, the recording density of the magnetic tape was 41.85 Mbps and the track pitch was 10 占 퐉.

5 is a diagram illustrating a conventional operation. Fig. 5A shows the characteristic of the tape running speed, and Fig. 5B shows the pattern of the recording track.

As shown in Fig. 5A, the tape running speed V only needs time "a" until the predetermined tape running speed "vo" is reached when recording is performed, and the tape running speed "vo" to " Only time "c" is needed until it goes down to "0".

As a result, when recording starts from the tape running speed "0" at time "t0", the tape running speed V is slow for a time "a" until the predetermined tape running speed "vo" is reached. As shown in Fig. 5B, the recording track is recorded at a high density.

Similarly, when recording is executed until the time stops from the tape running speed "vo" at time "t1", the tape running speed is greater than the predetermined tape speed "vo" at time "b" during the time "c". Since (V) is late, the recording track is recorded at a high density as shown in Fig. 5B.

In the time-lapse VTR, since recording and stop are repeated, when the track pitch is as narrow as 10 µm as in the DVC format, the recording density increases when the tape is accelerated and decelerated, and the data of the adjacent track can be read and read. There will be no. This was not a problem, for example, with a track pitch of about 58 mu m, like the VHS format.

However, in the conventional video signal recording apparatus, when recording the video information intermittently, the magnetic tape is intermittently recorded, that is, traveling and stopping are repeatedly recorded. There is a problem that the recording track is not formed accurately in a predetermined format because it is not constant, and the recorded image is disturbed.

Accordingly, an object of the present invention has been made in view of the foregoing, and an object of the present invention is to provide a video signal recording method capable of reliably recording a video signal in a predetermined format from an initial recording stage.

1 is a block diagram showing a video signal recording apparatus to which the present invention is applied.

FIG. 2 is a flowchart for explaining an operation of the control circuit of FIG. 1.

3 is a diagram showing a recording pattern of a magnetic tape according to the present invention.

4 is a diagram for explaining a recording format of a DVC.

5A and 5B are operation explanatory diagrams illustrating an example of the related art.

<Description of Symbols for Main Parts of Drawings>

1: Video signal recording device 2: Analog / digital conversion circuit

3: signal processing circuit 4: error correction circuit

5 coding circuit 6 detecting circuit

7: magnetic tape 8: recording and reproducing section

9 control unit 10 digital / analog conversion circuit

11: magnetic head 12: rotating drum

13: drum motor 14: capstan motor

15: Capstan roller 21: Capstan motor drive circuit

22: drum motor drive circuit 23: control circuit

Claim 1 of the present invention for achieving the above object is a video signal recording method of a video signal recording apparatus for recording a video signal on a recording medium, comprising: (1) recording the signal in a predetermined format on the recording medium in advance; (2) detecting a signal previously recorded on the recording medium in a predetermined format at the time of recording the video signal, and (3) on the recording medium corresponding to the detected predetermined format signal. And sequentially recording the video signals.

According to claim 1, a signal is recorded in a predetermined format on a recording medium in advance, and when a video signal is recorded, a signal of a predetermined type recorded in advance on a recording medium is detected, and the video signal is sequentially recorded on the predetermined format of the signal. Since the video signal can be reliably recorded in a predetermined format, the video signal to be recorded can be reliably recorded from the beginning to the end without disturbing the video.

Claim 2 is characterized in that the video signal recording apparatus is an intermittent recording apparatus.

According to claim 2, it is possible to prevent deterioration of an image during recording / stopping operation and to significantly improve image quality by using it in an apparatus in which recording / stopping operation is frequently performed such as an intermittent recording apparatus. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a video signal recording apparatus to which the present invention is applied. The video signal recording apparatus 1 shown in Fig. 1 is an analog / digital conversion circuit (ADC) 2 for converting an analog input video signal into a digital video signal, and performs signal processing for recording / reproducing for the digital video signal. A signal processing circuit 3, an error correction circuit 4 for performing an error correction process, an encoding circuit 5 for encoding a recording digital video signal with a code suitable for a magnetic conversion characteristic, and a detection for detecting a playback digital video signal. The recording / reproducing section 8 and the recording / reproducing section 8 which record the recording digital video signal on the magnetic tape 7 and reproduce the playback digital video signal from the magnetic tape 7 are controlled. The control unit 9 comprises a digital / analog conversion circuit (DAC) 10 for converting a playback digital video signal into an analog playback video signal.

The analog video signal to be recorded is supplied to the video input terminal Tin. The video input terminal Tin is connected to the analog / digital conversion circuit 2, and the recording analog video signal supplied to the video input terminal Tin is supplied to the analog / digital conversion circuit 2. The analog / digital conversion circuit 2 converts the recording analog video signal supplied to the video input terminal Tin into a digital form. The recording digital video signal converted into the digital form by the analog / digital conversion circuit 2 is supplied to the signal processing circuit 3.

The signal processing circuit 3 is supplied with a recording digital video signal from the analog / digital conversion circuit 2 and a reproduction digital video signal from the error correction circuit 4. The signal processing circuit 3 performs signal processing such as 1/6 compression, shuffling, etc. on the recording digital video signal supplied from the analog / digital conversion circuit 2 during video recording. The signal processing circuit 3 also performs signal processing such as decompression and deshuffling on the reproduced digital image signal supplied from the error correction circuit 4 at the time of image reproduction.

The recording digital video signal processed by the signal processing circuit 3 is supplied to the error correction circuit 4. The error correction circuit 4 assigns and outputs a code for correcting an error during reproduction to the recording digital video signal processed by the signal processing circuit 3. The recording digital video signal to which the error correcting code is assigned in the signal processing circuit 3 is supplied to the coding circuit 5.

The encoding circuit 5 converts the recording digital video signal to which the error correction code is given by the error correction circuit 4 into a code suitable for the magnetic conversion characteristic. The recording digital video signal converted by the encoding circuit 5 into a code suitable for the magnetic conversion characteristic is supplied to the recording / reproducing section 8.

The recording and playback section 8 includes a rotating drum 12 for rotating the magnetic head 11 to scan the magnetic tape 7 at an angle, a drum motor 13 for rotating the rotating drum 12, and a magnetic tape 7. And a capstan roller 15 for pressing the capstan motor 14 and the magnetic tape 7 on the rotating shaft of the capstan motor 14. The recording and playback section 8 is connected to the control section 9, the rotation of the drum motor 13 is controlled by the control section 9 to control the rotation of the rotating drum 12 and at the same time the rotation of the capstan motor 14 It is controlled so that the traveling speed of the magnetic tape 7 is controlled.

The control unit 9 is a capstan motor driving circuit 21 for driving the capstan motor 14 of the recording and playback section 8, and a drum motor driving circuit 22 for driving the drum motor 13 of the recording and playback section 8. And a control circuit 23 for controlling recording and reproduction of information. The capstan motor drive circuit 21 drives the capstan motor 14 so that the traveling speed of the magnetic tape 7 becomes a preset speed in accordance with the drive control signal from the control circuit 23. In addition, the drum motor drive circuit 22 drives the drum motor 13 so that the scanning speed of the magnetic head 11 is constant in accordance with the drive control signal from the control circuit 23.

The control circuit 23 supplies drive control signals to the capstan motor drive circuit 21 and the drum motor drive circuit 22, as described later in the intermittent recording, and to the magnetic tape 7 as shown in FIG. Similarly, after a predetermined signal is read in DVC format and synchronized, the newly supplied video data in the video data area is sequentially overwritten.

In addition, the signal recorded on the magnetic tape 7 is magnetically detected by the magnetic head 11 and converted into a current. The signal converted into current by the magnetic head 11 is supplied to the detection circuit 6. The detection circuit 6 performs decoding processing on the signal from the magnetic head 11 to obtain a signal before encoding by the coding circuit 5. The signal decoded by the detection circuit 6 is supplied to the error correction circuit 4.

The error correction circuit 4 corrects an error in the reproduction signal on the basis of the error correction code previously given at the time of recording. The error corrected reproduction signal is supplied to the signal processing circuit 3. The signal processing circuit 3 performs processing such as deshuffling, stretching, etc., on the playback signal in reverse to that at the time of recording to restore the playback digital video signal. The reproduced digital video signal reconstructed by the signal processing circuit 3 is supplied to the digital / analog conversion circuit 10.

The digital / analog conversion circuit 10 converts the reproduced digital video signal restored by the signal processing circuit 3 into an analog video signal and outputs it from the output terminal Tout.

Further, the recording tape is recorded on the magnetic tape 7 in a predetermined format based on the DVC standard in advance, for example, as shown in FIG. In the DVC standard shown in FIG. 4, a video signal for one frame is divided and recorded into ten recording tracks shown in FIG. In addition, the audio signal can be recorded by selecting any of two channels and four channels.

In the case of two channels, quantization is 16 bits, and sampling frequencies of 48 kHz and 44.1 kHz can be selected. In the case of four channels, the quantization is 12 bits and the sampling frequency is 32 kHz.

Audio data is also divided into 10 recording tracks and recorded in the same manner as video data. At this time, in the case of two-channel recording, the first five tracks are divided into one channel of the first channel and the remaining five tracks are divided into one channel of the second channel. In the case of four-channel recording, two channels of the first and second channels are divided into the first five tracks, and two channels of the third and fourth channels are recorded in the remaining five tracks. Here, the intermittent write operation of the control circuit 23 will be described with reference to FIG.

FIG. 2 is a process flowchart for the control circuit 23 in the control unit 9 in FIG.

When recording the video signal on the magnetic tape 7, the control circuit 23 first supplies a drive control signal to the capstan motor driving circuit 21 and the drum motor driving circuit 22 to supply the capstan motor 14 and the drum. The motor 13 is driven (steps S1 and S2), and the detection circuit 6 detects a signal previously recorded on the magnetic tape 7 in a predetermined recording pattern by the magnetic head 11 (step S3). .

Then, the control circuit 23 generates drive control signals of the capstan motor drive circuit 21 and the drum motor drive circuit 22 based on the signals detected and decoded by the detection circuit 6, and the capstan motor drive circuit By supplying the furnace 21 and the drum motor driving circuit 22 to control the capstan motor 14 and the drum motor 13, synchronization with signals previously recorded in a predetermined recording pattern on the magnetic tape 7 is achieved. (Step S4). After synchronizing with a signal previously recorded in a predetermined recording pattern in step S3, the recording digital video signal is supplied from the encoding circuit 5 to the magnetic head 7 to overwrite the recording digital video signal (step S5). .

When the recording digital video signal is recorded on the magnetic tape 7 for a predetermined frame, the control circuit 23 connects the capstan motor 14 and the drum motor 13 to the capstan motor driving circuit 21 and the drum motor driving circuit 22. Generates a drive control signal to stop the operation, supplies it to stop the capstan motor 14 and the drum motor 13, and then waits for the intermittent recording information to be supplied (step S6).

FIG. 3 is an explanatory view of the operation of one embodiment of the present invention, showing a recording pattern of the magnetic tape 7.

As shown in Fig. 3, since the track of the DVC format as shown in Fig. 3 is already recorded on the magnetic tape 7, the magnetic head 11 can store the existing data of the part of Fig. 3 scattered. By detecting, it synchronizes with the DVC format and writes a video signal on it. Therefore, the video signal can be recorded in a predetermined format such as a DVC as shown in FIG.

Thus, the reproduced video signal can be reliably reproduced without being disturbed at the beginning and the end of the recording.

Furthermore, although the video signal has been described in this embodiment, it goes without saying that the audio signal is similarly recorded.

At this time, as a function of the DVC, after recording the video signal and the audio signal on the magnetic tape 7, there is an after recording which additionally records the audio signal different from the recorded information. The audio signal is overwritten by using the appreco function.

In addition, the magnetic tape once written by the above method has already been recorded with the insert data, and can be written thereon without formatting and fixing.

As described above, in the video signal recording method of the present invention, according to claim 1, a signal is recorded in a predetermined format on a recording medium in advance, and a signal of a predetermined format previously recorded on the recording medium is recorded when the video signal is recorded. By recording the video signals sequentially over a predetermined format, the video signals can be reliably recorded in a predetermined format. Therefore, the video signals to be recorded can be reliably recorded from the beginning to the end without disturbing the video. It has such features.

According to claim 2, it is possible to prevent the deterioration of an image during recording and stopping operations, and to achieve a significant improvement in image quality by using it in an apparatus in which recording and stopping operations are frequently performed, such as an intermittent recording apparatus. It has such features.

Claims (3)

In a video signal recording method of a video signal recording apparatus for recording a video signal on a recording medium, (1) recording a signal in a predetermined format on the recording medium in advance; (2) detecting a signal recorded in advance in a predetermined format on the recording medium when the video signal is recorded; And And (3) sequentially recording and recording the video signal on the recording medium corresponding to the detected predetermined format signal. The video signal recording method according to claim 1, wherein the video signal recording device is an intermittent recording device. The video signal recording method according to claim 1, wherein said step (1) records in advance a signal of a predetermined format based on the DVC format.