JPH0575963A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a video signal recording and reproducing device where the picture quality of a moving picture part at the time of search reproducing is improved by preventing video information of many frames from existing together in the reproduced picture for search reproducing. CONSTITUTION:The video signal of one field is divisionally recorded on plural recording tracks, and this frame memory consists of a first memory 6 and a second memory 7 where odd fields and even fields are written respectively at the time of normal reproducing. At the time of search reproducing, a write control circuit 8 and a read control circuit 9 are so controlled that first and second memories 6 and 7 are alternately selected as write and read memories at intervals of the N-frame time by a memory selecting circuit 10, and N is selected in accordance with the reproducing speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing device (hereinafter referred to as VTR) for special reproduction.

[0002]

2. Description of the Related Art In recent years, a VTR for recording / reproducing a wideband video signal has adopted a multi-track system in which video information of one field is divided into a plurality of tracks for recording. In this case, SN due to crosstalk between tracks
In order to avoid a decrease in R, it is common practice to perform shuffling processing to distribute each line so that correlated signals are arranged on a tape pattern. VT like this
In R, deshuffling processing that is the reverse of playback and recording is performed, so lines are rearranged using the frame memory, and special playback of fast forward and rewind (hereinafter referred to as search playback) is performed. It is possible to use this frame memory also.

Further, in a VTR equipped with a frame memory, in order to realize noiseless search reproduction, it is sufficient to set a tape pattern so that all video information in the memory can be rewritten once at a certain fixed cycle. For example, reproducing one field by performing two head scans 2
In the case of segment recording, n + 0.5 (n is an integer) double speed is appropriate.

FIG. 3 shows a recording pattern on a 1-channel 2-segment type tape. Segments 1 and 2 make up an odd field, and segments 3 and 4 make up an even field. Hereinafter, this method will be described as an example.

FIG. 4 shows a conventional VTR reproducing circuit. Further, (FIG. 5) shows the timing of each part during reproduction at 2.5 times speed. In FIG. 4, 1 is a magnetic recording tape, 2
Is a reproducing head, 3 is a reproducing processing circuit for processing a reproduced signal, 4 is a segment detecting circuit for detecting a segment number from the reproduced signal, 5 is a frame pulse generating circuit, and 6 is for writing and reading an odd field. First memory, 7 is a second memory for writing and reading even fields, 8 is a write control circuit for controlling writing to the memory, 9 is a read control circuit for controlling reading of the memory, and 11 is This is a video signal output terminal.

At the time of reproducing at a speed of 2.5 times, the reproducing head 1 follows a locus like (31) in (FIG. 3).
An intermittent output as shown in (b) is obtained. here,
(A) of FIG. 5 is a head switch signal for switching heads, and represents one field time in one cycle. In the write control circuit 8, the segments 1 and 2 are transferred to the first memory 6 and the segments 3 and 4 are transferred to the second memory 7 in accordance with the segment number detected by the segment detection circuit 4 ((d) in FIG. 5). And write like (e). The read control circuit 9 alternately reads the first memory 6 and the second memory 7 as shown in (g) and (h) of FIG. In this case, in order to completely rewrite the video information of one frame, it is necessary to carry out eight times of head scanning, which is twice as much as that in normal reproduction. Further, in the case of 2.5 times speed, as shown in (FIG. 5), the frame information advances by 2.5 frames by two head scans, so that the image information is
It crosses the frame.

As described above, according to the conventional method, at the time of n + 0.5 times speed, 2 × (n + 0.5) is contained in one frame of the reproduction screen.
The video information for the frame was supposed to be mixed. Therefore, in the moving image portion, the image quality is deteriorated such that the images are overlapped many times, which is a problem.

[0008]

As described above, in the conventional configuration, since the video information of many frames are mixed on the playback screen at the time of search playback, there is a problem that the image quality in the moving image portion is deteriorated. It was In particular, when the reproduction speed is increased, there is a problem that the number of mixed frames increases and the image quality deteriorates.

It is an object of the present invention to provide a VTR which solves the above-mentioned drawbacks and improves the image quality of moving images during search reproduction.

[0010]

In order to solve the above problems, the present invention divides a video signal of one field into a plurality of recording tracks for recording, and writes a video signal of an odd field during normal reproduction. And a second memory for writing the video signal of the even field are provided, and during search playback, only one memory is written during the N frame time, and read is performed only from the other memory. The memory is alternately switched every time, and the value of N is selected according to the reproduction speed.

[0011]

The present invention has the above-mentioned structure,
Since the number of frames of video information mixed in the playback screen is half that of the conventional example, the image quality deterioration in the moving image part is reduced to about half by very simple control without adding a complicated control circuit. It becomes possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a VTR reproducing circuit of the present invention. Also (Fig. 2), 1 channel 2 segment system,
The following shows the timing of each part during reproduction at 2.5 times speed. Further, (FIG. 3) shows a tape pattern of the 1-channel 2-segment system.

In FIG. 1, 1 is a magnetic recording tape, 2
Is a reproducing head, 3 is a reproducing processing circuit for processing a reproduced signal, 4 is a segment detecting circuit for detecting a segment number from the reproduced signal, 5 is a frame pulse generating circuit, 6
Is a first memory for writing an odd field video signal during normal reproduction, and 7 is a second memory for writing an even field video signal. The first memory 6 and the second memory 7 form a frame memory. .. 8 is a write control circuit for controlling the writing of the memory, 9 is a read control circuit for controlling the reading of the memory, 10 is a special playback such as fast-forwarding and rewinding, and writing to only one of the memories during the N frame time, Read only from the other memory,
Reference numeral 11 denotes a video signal output terminal, which is a memory selection circuit that alternately switches the memory every N frame times and selects the value of N according to the reproduction speed.

At the time of reproducing at a speed of 2.5 times, the reproducing head 1 follows a locus like (31) in (FIG. 3).
An intermittent output as shown in (b) is obtained. here,
(A) of (FIG. 2) is a head switch signal for switching heads, and represents one field time in one cycle. The write control circuit 8 writes in each memory as shown in (d) and (e) of FIG. 2 according to the segment number detected by the segment detection circuit 4 and (c) of the memory selection signal (FIG. 2). The reading control circuit 9 performs reading according to the reading memory selection signal (FIG. 2) (f). In the memory selection circuit 10, (c) of the write memory selection signal (FIG. 2) and (f) of the read memory selection signal (FIG. 2) so that the memory for writing and the memory for reading are alternately selected for each frame time. To control. Therefore, it is possible to rewrite all the video information of one frame of the video signal output by the same four head scans as in the normal reproduction, and the video information is 2.5 as shown in FIG.
Since it only extends to the frame, the image quality of the moving image portion can be improved.

Here, the time for switching the memory may be longer than the time when all the video information in the memory is rewritten, and can be obtained from the speed and the tape pattern.
In the case of quintuple speed, one frame or more. Further, in the above-mentioned embodiment, only the 2.5 times speed search reproduction with the two-segment VTR is shown, but it is clear that the same effect can be obtained with all the speeds of the VTRs of all the multi-track recording. ..

[0017]

As is apparent from the above embodiments, according to the present invention, it is possible to shorten the period of the frame information mixed in the reproduction screen during the search reproduction, and improve the image quality of the moving image portion of the VTR. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a VTR according to an embodiment of the present invention.

FIG. 2 is a timing chart of each part of the VTR.

FIG. 3 is a tape pattern diagram of 1-channel 2-segment recording.

FIG. 4 is a block diagram of a conventional VTR.

FIG. 5 is a timing chart of each part of a conventional VTR.

[Explanation of symbols]

 4 segment detection circuit 5 frame pulse generation circuit 6 first memory 7 second memory 8 write control circuit 9 read control circuit 10 memory selection circuit

Claims (1)

[Claims] 1. A first memory for recording a 1-field video signal by dividing it into a plurality of recording tracks, and writing an odd-field video signal during normal reproduction, and a second memory for writing an even-field video signal. Equipped with a frame memory, during special playback such as fast forward and rewind, only one memory is written and read from the other memory during N frame time, and the memory is switched alternately every N frame time, depending on the playback speed. A video signal recording / reproducing apparatus characterized by selecting a value of N.