JPH0722360B2 - Video signal recording method - Google Patents

Description

The present invention relates to a video signal recording method. In particular, the present invention relates to a VTR signal processing method for recording a wideband video signal by a segment recording method.

Conventional technology With the advent of the new media era, the development of high-definition television has been actively carried out. Especially in Japan, the method called high-definition is well known.

This is what NHK plays a central role in promoting development,
There are provisional standards shown in Table 1.

Various methods for recording such a wideband video signal on a VTR have been studied.

In general, a helical scan type magnetic recording in which magnetic heads are mounted on a rotating drum at positions of 180 degrees to each other, (180 + α) degree (α is at most tens of degrees) tape is wound, and video signals are recorded as oblique tracks on the tape. In the reproducing apparatus, the rotating drum rotates at the frame frequency of the video signal. Therefore, the video signal of one field is recorded as one track.

In order to record the above wideband video signal using such a VTR, (1) the video signal is divided into multiple channels and recorded.

(2) Increase the tape / head relative speed.

There is a method. In fact, a method that combines both is also practical. In order to record without increasing the number of heads, it is necessary to adopt the method (2).

According to the method (2), the rotary head tram must be rotated N times in order to record a video signal having a band N times that of the standard VTR such as NTSC. When N is an integer, one field is recorded on N tracks. For example, if one frame of 1000 video signals is recorded by rotating the drum 4 times, 125 scanning lines are recorded per track. A video signal that can be recorded by a single scan of the magnetic head on the tape-in the above example, an image of 125 scanning lines-is called a segment.

The first segment 1S to the eighth segment 8S record different positions on the screen as shown in FIGS. 6A, 6B and 6C. In the figure, 1 is a magnetic tape. Recording in this way has the following two problems. The first problem is that when the reproducing head reproduces across multiple tracks during variable speed reproduction, only one part of each segment of the screen is reproduced by one scanning, and information of the entire screen is obtained. I can't. The second problem is that the output of the envelope of the reproduced signal becomes more unstable as it approaches the end of the tape. In the case of an envelope with reduced output on one side of the tape, the S / N at the center of the screen
A seam between a part where the image quality is deteriorated and a part where the image quality is not observed appears, and image quality deterioration is noticeable. To solve the above problems,
There is a method proposed in 61-34593 and Japanese Patent Application No. 61-39915. This is because the video signal of 1 field is sequentially sorted into each segment by 1H (shuffling),
All segments contain information about the entire screen. As a result, at the time of variable speed reproduction, the signal of the entire screen can be reproduced by one scanning regardless of how a plurality of segments are traversed, so that good variable speed reproduction can be performed. Further, since the upper and lower edges of the screen are always recorded at the tape end, no break in the envelope occurs in the middle of the screen, so image quality does not deteriorate.

Problems to be Solved by the Invention When the above method is adopted and the band of the video signal to be recorded is 2.5 times that of the standard method, the drum rotation speed is changed.
It cannot be 2.5 times. The reason is that when recording the video signal of the entire screen of one field on 2.5 tracks, the information of the entire one field should be recorded on the track scanned by the magnetic head from one end to the other end of the tape for two tracks. However, with respect to the remaining 0.5 tracks, the information over one field can be recorded only on one half of the tracks scanned by the magnetic head from one end to the other end of the tape. In the remaining 0.5 tracks, only the information of the second field will be recorded. Therefore, if the above method is applied, the number of rotations of the drum must be doubled or tripled. If you select 2 times, the recording wavelength will be shorter and the S / N of the reproduced image will be worse. If you select 3 times, the S / N will be
Is good, but the recording time per tape length is the same.

In order to solve the above problems, the present invention provides a video signal recording method capable of obtaining the same effect even when the number of rotations of the drum is n + 1/2 times the frame frequency (n is a positive integer). It is provided.

Means for Solving the Problems In order to solve the above problems, the present invention intends to eliminate the discontinuity of the image due to the field by performing shuffling in one frame as a unit.

Effect of the Invention With the above-described structure, the present invention makes it possible to obtain a good variable speed reproduction and a good image without the influence of head switching in the middle of the screen even if the drum rotation speed is selected to be n + 1/2 times the frame frequency. Is.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 5.

This embodiment relates to a case where a high-definition signal is divided into two channels and recorded at a drum rotation speed of 4500 rpm (1800 × 2.5), which is a combination of the above methods (1) and (2). . The HDTV signal consists of 1125 scanning lines per frame. Of these, 1000 are recorded excluding blanking. This is shown in FIG. The numbers are relative scan line numbers. Generally, signals to be recorded are input as signals of three channels of Y, Cw and Cn. In order to record these signals on the VTR, the color line sequential signal is time-axis compressed and multiplexed on the luminance signal for one channel.
It is handled as a TCI signal (time axis compression multiplexed signal).

Therefore, 1H of the signal to be recorded is as shown in FIG. This signal is expanded on the time axis every 1H and divided into 2 channels, and then 1 frame is divided into 5 by using the frame memory.
It is divided into segments. This is shown in FIG. N
Each segment from o.1 to No.5 consists of 2 channels of information of 110 lines per channel. In the figure, each number indicates a line number. FIG. 4 shows how these signals were actually recorded. In the figure, 1 is a magnetic tape, A is the tape running direction, and B is the head running direction. 1S is first
The segments, 2S to 5S, represent the second segment to the fifth segment, respectively. The signals of channels 1 and 2 of each segment are recorded by two heads scanning simultaneously. Recording of one frame is completed by sequentially recording 10 tracks and 5 segments of 1S to 5S. The structure of the rotary head drum for recording this tape pattern is shown in FIG. 2 is a rotating drum, 2'is a fixed drum,
3,3 'are magnetic heads for recording channel 1,4'
Is a magnetic head for recording channel 2. As the tape 1 advances in the A direction and the rotary drum 2 rotates in the B direction, the recording patterns of FIG. 4 are obtained by the heads 3, 3 ', 4, 4'.

Next, at the time of reproduction, 5 segments from 1S to 5S are sequentially reproduced, temporarily stored in the frame memory, and a process reverse to that at the time of recording is performed, so that the 1st to 1100th lines can be replaced in the original order.

Further, in the case of variable speed reproduction, one scan crosses a plurality of segments, but in all tracks, the position in the width direction of the tape and the position on the screen recorded in that part are substantially the same. Since they are associated with each other, information of each part can be obtained on average and a good image can be obtained.

In the above embodiments, the case of the time axis expansion 2-channel division method has been described, but it goes without saying that the same effect can be obtained by the same method even in the case of 1 channel or more channels.

Further, although the color signals of the TCI signal are described as line sequential, it goes without saying that the same applies to the case of the line simultaneous TCI signal.

As described above in detail, according to the present invention, by performing shuffling in units of one frame so as to eliminate the discontinuity of the image due to the field, the drum rotation speed is set to n + 1 of the frame frequency. Even if you select / 2 times, you can get good variable speed playback and good images without the effect of head switching in the middle of the screen.

[Brief description of drawings]

FIG. 1 is a simple explanatory diagram of segment division in one embodiment of the present invention, FIG. 2 is a simple explanatory diagram of a recording signal of one frame in one embodiment of the present invention, and FIG. 3 is one implementation of the present invention. FIG. 4 is a diagram showing a relationship between an input signal and a recording signal which is time-axis compression-multiplexed in units of H, FIG. 4 is a recording pattern diagram on a tape in an embodiment of the present invention, and FIG. FIG. 6 is a top view and a front view of the rotary head drum for recording the recording pattern shown in FIG. 6, and FIG. 6 is an explanatory diagram of normal segment recording.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Iwao Obata Inventor Iwao Obata 2-2-1 Jinnan, Shibuya-ku, Tokyo Inside the Japan Broadcasting Corporation Broadcasting Center (72) Ryoji Tsunoi 1-10-11 Kinuta, Setagaya-ku, Tokyo Within the Japan Broadcasting Corporation's Broadcast Technology Laboratory (72) Inventor Hiromichi Shibata 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Japan Broadcasting Corporation's Broadcast Technology Laboratory (56) Reference JP 62-43280 (JP, A) JP 62-245884 (JP, A) JP 62-145978 (JP, A) JP 61-77107 (JP, A) JP 61-77479 (JP, A) JP 62-190981 (JP, A)

Claims (1)

[Claims] 1. When scanning a magnetic tape with a magnetic head to record a video signal on the magnetic tape as a set of oblique tracks, thinning of scanning lines from one frame of the original video signal based on a predetermined regulation. By the operation, each frame is divided into N sets of video signals each of which is composed of about 1 / N (N is an odd number of 3 or more) scanning lines, and includes information over one frame. For each video signal, the information is recorded from the scanning start point to the scanning end point of the original video signal by one scan by the magnetic head, so that the video signal of one frame is sequentially scanned by N times. A video signal recording method characterized by the above.