JPS62190981A - Video signal recording method and recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform excellent variable speed reproduction by dividing a video signal of one field into N groups of video signals which are continuous in terms of time while combining mutually discontinuous horizontal scanning line signals, and recording them on N tracks in order so that one group of video signals corresponds to one track. CONSTITUTION:A frame memory 5 consists of field memories 16 and 17 and switches SW1 and SW4. A signal of the 1st field is inputted to the field memory 16 and written in 1/2 field memories 18 and 19, line by line. The SW1 is inverted after writing from a period of one field, and the 2nd field is written in the field memory 17. The output of the frame memory 5 is inputted to a DA converter 6 and converted into an analog video signal, which is recorded on a tape 1. When reproduction is performed four times as fast as usual, respective parts of signals G1-G4 by the 1st scan and G5-G8 by the 2nd scan are reproduced and displayed as shown by (d). Therefore, normal picture are reproduced even at the time of the four-fold speed reproduction by the same signal processing with normal-speed reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a helical scan type video tape recorder (hereinafter abbreviated as VTR), and particularly to a helical scan type video tape recorder (hereinafter abbreviated as VTR), which provides good variable speed playback especially when recording one field by dividing it into multiple tracks. It provides a method to make it possible.

Conventional technology The rotating two-head helical scan VTR is used as a basic system in many VTRs, typified by VTR1d, VH3, and β system. The basic recording format of this VTR is shown in FIG. 6a. In the figure, 1 is the magnetic tape, 2 is the recording track, T is the tape running direction, H is the head moving direction, and P is the distance the magnetic tape runs during one frame (two fields). (In the case of 2:1 interlace) A, B, C, and D correspond to the positions shown in FIG. 6 on the screen. The number of revolutions of a rotary head drum equipped with a magnetic head of a VTR having a mechanical system capable of forming such a recording format is equal to the frame frequency.

In order to record a wider band video signal using this VTR, it is necessary to increase the relative speed between the head and the tape. For example, to record a signal with twice the band of the original video signal, it is necessary to rotate the rotary drum at twice the number of rotations and also to double the tape running speed.

In this case, A of the recording track in FIG. 6a.

Points B, C, and D appear on the screen as shown in Figure 6C.

Further, in this case, P is the distance that the magnetic tape travels during one field.

The method of dividing one field of image into a plurality of parts (segments) on the time axis and recording each part on a separate track is called a segment recording method.

The disadvantages of this method are (1) the presence of head switching points within the screen; (2) Since the head crosses the track during variable speed reproduction, segment positions within the screen are not reproduced correctly and a normal screen cannot be obtained.

Among them, (1) can be solved by forming a blanking part near the head switching point in the screen by time axis shift processing for recording and reproduction (Television Society Technical Report TEBSas-1).

less than? ) will be explained in detail. FIG. 6 is a recording pattern diagram for the segment method shown in FIG. 5.

-Here, 3 and 3' are the trajectories drawn on the tape by the two heads located at 180 degrees, respectively, when the tape feed speed is 4 times faster. Figure 6: F.

~F8 shows how the first to fourth fields are reproduced at normal tape speed. Furthermore, the hatched portions 81 to S8 in this figure are the trajectories 3 and 3' of a at 4x speed.
indicates the part to be played. FIG. 6C shows one screen that is played back at 4x speed. This screen is a unit of A-width band-shaped images of the entire screen, with the upper half image and lower half image alternately exchanged, and it is difficult to distinguish the image contents.

The above is an example of 4x high-speed playback, but any n
The same is true in the case of variable speed reproduction of double speed or 1/n times speed, and a screen is reproduced in which the locations on the screen are mixed in segment units.

Problems to be Solved by the Invention In a VTR that records using the segment method as described above, the segment positions on the screen change during variable speed playback, making it impossible to obtain a normal screen.

Means for Solving the Problems In order to solve the problems described in the present invention, one field of video signal is divided into N consecutive scanning lines, and all of the divided groups are divided into N scanning lines. The video signals are divided into N sets of consecutive video signals such that each scanning line belongs to a different set from the other, and each set is sequentially recorded as one track of video signals.

Operation The present invention, with the above-described configuration, makes it possible to obtain a normal screen by performing relatively simple processing during variable speed playback.

Embodiment An embodiment of the present invention is shown in FIG. In this embodiment, scanning line 1
126 lines, field frequency 60)1. This is an example in which a (2:1 interlaced) high-vision signal is recorded on a rotating two-head helical scan VTR with a drum count of 801-1x.

Figure 1a shows the recording pattern on the magnetic tape, A, B
, C, and D correspond to the position indicated by b on the screen. In this embodiment, two tracks constitute one field, as in the conventional example. G4. G2... indicates each track. C indicates the horizontal constant strain line number constituting each track. In order to record in such a format, it is necessary to rearrange the order of video signals in units of horizontal scanning lines.

FIG. 2a shows an example of a hardware configuration for performing such signal processing. Vi is a video signal input terminal, 4 is an AD converter, 5 is a frame memory, 6 is an LIA converter,
7 is an FM modulator, 8 is a recording amplifier, and 9 is a recording head. 10 is a playback head, 11 is a playback amplifier, 12 is an FM
Demodulator, 13 is an AD converter, 14 is a frame memory, 1
5 is a DA converter, and vo is a video signal output terminal.

This operation will be explained below. Input video signal is at terminal ■1
and is digitized by the AD converter 4.

This signal is input to frame memory 6. Details of the frame memory 5 are shown in FIG. The frame memory 6 is
It consists of field memories 16 and 17, switches SW1 and SW4.

Field memory 16 is % field memory 18°19
, SW2. It consists of SWa. Field memory 17 has a similar configuration to field memory 16.

An input to the frame memory 6 is given to an input terminal F. SWl is a switch that is inverted for each field.

The first field signal is input to field memory 16. SW2 is a switch that is inverted for each horizontal scanning line, and data is written into the % field memory 18 and the % field memory 19 alternately for each line. After completing writing for one field period, SW1 is inverted, and the second field is written to field memory 1T. During the second field period, the field memory 16 is in a read state. First, the field memory 18 is read out for a % field period, and the field memory 19 is read out for the next % field period. SWa is inverted for each % field according to the above operation. A timing chart regarding the operation of the field memory 16 is shown in FIG.

Data is written to the field memory 17 during the second field period, and data is read out during the next first field period in the same manner as described above. The timing chart will be omitted.

SW4 always reverses in the opposite direction to SWl. Through the above signal processing, a time-series signal that is to be recorded as an output of the frame memory 6 in the format shown in FIG. 1 is obtained. The output of the frame memory 5 is input to a DA converter 6 and becomes an analog video signal. This signal is recorded on the tape 1 via an FM modulator 7, a recording amplifier 8, and a recording head 9.

During playback, the signal recorded on tape 1 is transferred to playback head 1.
0.0, reproduction amplifier 11.2M After being converted into an analog video signal via a demodulator 12, it is digitized by an AD converter 13 and input to a frame memory 14. The configuration of the frame memory 14 is similar to that of the frame memory 6, but the operation is different because it is necessary to obtain the original signal through reverse processing. That is, SWl is inverted every field, and SW2
is per % field, SWa is per line, SW4
are respectively inverted in the opposite direction to SWl.

As a result, the same video signal as the input video signal is obtained as a digital signal at the output of the frame memory 14. This signal is converted into an analog video signal by the DA converter 15 and output. Note that in the above description, the low-pass filter, clock generator, memory control circuit, etc. that are naturally considered necessary for performing such signal processing are omitted. Also A/D,
Since the D/A converter and frame memory can be used in common during recording and playback, one each may be sufficient.

Although the 1126th line is not recorded in FIG. 1 C1 and FIG. 3, the last line of one frame is normally within the vertical retrace period, so there is no particular problem.

Next, the case where a tape recorded in such a format is played back at variable speed will be explained in comparison with the case at normal speed.

Figures 4a and 4b show the case of normal speed playback. G1 of a.
G2 is a rough image reproduced by each head (an image skipping one line as shown in Figure 1C), and a normal reproduction signal is obtained by processing this with the reproduction circuit in Figure 2, but b The figure shows a reproduced image when output without reproduction processing. In this case, information for one complete field can be obtained by applying constant head distortion twice, but both G1 obtained in the first scan and G2 obtained in the second scan contain information for the entire screen. If the video signal reproduced by two scans is displayed as is on a CRT, a screen like that shown in b will be displayed.

On the other hand, in the case of 4x speed playback, the heads 3, 3 in Figure 1a,
31, it runs on the tape. In this case, Fig. 4C
G1 to G4 in the first scan, % to G4 in the second scan, like
Each part of the G8 signal is reproduced. If this reproduced signal is displayed on a CRT in the same manner as above, it will be displayed as shown in d. This is a signal similar to b in the case of normal speed. Therefore, even in the case of quadruple speed playback, a normal screen can be reproduced by the same signal processing as in the case of normal speed playback. It is clear that the above idea holds true in the case of other variable speeds as well.

In addition, in the method of recording in this format, if the horizontal synchronization signal positions of adjacent tracks are physically arranged on the tape, the information of adjacent scanning lines on the screen can be recorded adjacently. Adverse effects on image quality due to crosstalk can be avoided.

This type of recording is not possible with the segment recording method, and a better reproduced image can be obtained than with the segment recording method.

In the above explanation, the video signal system was not specifically defined, but the TCI signal, which time-axis multiplexes the luminance signal and chrominance signal, the composite signal, which performs quadrature two-phase modulation, and frequency multiplex the luminance signal, and the luminance signal and chrominance signal. Various types of signals can be considered, such as a component signal in which the signal is recorded on a separate track.

In addition, in this embodiment, the case where the drum rotation speed is twice the frame frequency has been explained, but in general, when the drum rotation speed is set to N times the frame frequency, by distributing N consecutive scanning lines to different tracks, it is possible to completely Similar effects can be expected.

Effects of the Invention As described above, according to the present invention, in a helical scan VTR, segment recording is not performed even though the rotary head drum is rotated at N times the frame frequency to record a wideband signal. During variable speed playback, normal images can be obtained through the same processing as in normal speed playback.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a method according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing a hardware configuration for implementing the method of the present invention, and Fig. 3 is an explanation of the operation of the hardware shown in Fig. 2. FIG. 4 is an explanatory diagram of variable speed playback in one embodiment of the present invention, FIG. 5 is an explanatory diagram of the conventional example, and FIG.
The figure is an explanatory diagram regarding conventional variable speed reproduction. 1...Magnetic tape, 2...Recording track, 3゜3'...Head trajectory during variable speed playback,
4,13・kawa・AD converter, 6,15・・・・D
A converter, 7, river...FMLJ [, jtl 4...
・・Frame memory, 12・・FM demodulator, 16,
17...Field memory, IQ, 19...
...Ifield memory. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure (Eng. 2 AC

Claims (4)

[Claims] (1) One field of video signal is divided into N sets of temporally continuous video signals by combining mutually discontinuous horizontal scanning line signals, and the above set of video signals is used as one track, A video signal recording method characterized by sequentially recording on N tracks. (2) Divide one field of video signals into N consecutive scanning line signals, and divide them into N groups of consecutive video signals such that all the scanning lines belong to different groups from each other. A video signal recording method according to claim 1, characterized in that: (3) One field of video signal is divided into N sets of consecutive scanning line signals, and one field of video signal is divided into N sets of consecutive scanning lines, and the consecutive scanning lines are recorded in adjacent tracks. 2. The video signal recording method according to claim 1, wherein each video signal is divided into consecutive video signals. (4) means for digitizing the input video signal; first memory means for temporarily storing the digitized video signal; first memory control means for controlling the first memory means; The output of the memory means of
DA conversion means for analog conversion, FM modulation means for FM modulating the output of the DA conversion means, recording means for recording the FM modulated signal on a magnetic tape, and FM demodulation of the FM signal reproduced from the magnetic tape to produce analog video. FM to get signal
demodulating means; means for digitizing the analog video signal; second memory means for temporarily storing the digitized video signal; second memory control means for controlling the second memory means; DA conversion means for digital-to-analog conversion of the output of the second memory means, and the first memory control means sequentially writes the digitized input video signal into the first memory means (N-
1) By repeating the operation of continuously reading out the signals of every other scanning line for approximately 1/N field's worth of scanning lines N times, the video signal of one field is output as N sets of consecutive video signals. , the recording means is a digital
The above-mentioned one set, which has been analog-converted and FM-modulated, is sequentially recorded as one track on a magnetic tape, and the second memory control means reproduces the N sets which are reproduced from the magnetic tape, FM demodulated, and then digitized. A video signal recording and reproducing apparatus characterized in that a signal is written in the second memory, and then read out by controlling the memory so as to restore the original horizontal scanning line arrangement.