JPH0817472B2 - Video signal recording / playback method - Google Patents

Description

The present invention relates to a video signal recording / reproducing method. In particular, the present invention relates to a recording method that can increase the speed of VTR high-speed search.

2. Description of the Related Art Various methods for recording video signals on a VTR have been studied.

Magnetic heads on top of each other on the most common rotating drum
In a helical scan type magnetic recording / reproducing apparatus which is mounted at a position forming 180 degrees, and a (180 + α) degree (α is at most several tens degrees) tape is wound around and a video signal is recorded as an oblique track on the tape, the rotating drum is It rotates at the frame frequency of the video signal. Therefore, the video signal of one field is recorded as one track. This is shown in FIG. In the figure, 1 is a tape, T is a tape running direction, H is a head running direction, and 2, 3, 4, and 5 are tracks on which one field is recorded.

In order to search the recorded tape at high speed while monitoring the reproduced image, it is necessary to reproduce the image from the recording track while running the tape at a speed sufficiently higher than the tape speed at the time of recording. At this time, the head reproduces across each track as in A. Therefore, each part of the image of a plurality of fields is reproduced in one field period. However, since a video signal at a fixed location on the screen is recorded at a fixed position in the tape width direction, it is possible to reproduce a comfortable image even if images from a plurality of fields are combined.

Then, in order to search at a higher speed, it suffices to increase the tape running speed. However, since the VTR generally runs with a tape wound around a large-diameter rotating drum and a fixed drum, the friction resistance between the fixed drum and the tape is particularly large, and the speed during high-speed search is limited.

Problems to be Solved by the Invention As described above, in the rotary head type VTR, the speed of high-speed search cannot be too fast, so that there remains a great dissatisfaction in terms of access time. The present invention provides a video signal recording method that improves this drawback and enables a search speed several times higher than that of the conventional VTR.

Means for Solving the Problems In order to solve the above problems, the present invention reduces frictional resistance by significantly reducing the tape winding angle on the drum during high-speed search, and reduces the winding angle within the range. By recording the information of the entire one screen, the reproduction screen can be identified.

Action The present invention has the above-described configuration to increase the tape running speed and improve the search speed while maintaining the discriminability of the reproduced image during high-speed search.

Example 1 An example of the present invention will be described with reference to FIGS. The present embodiment is applied to a case where an NTSC signal is recorded by a rotating two-head VTR. FIG. 2 shows a tape loading state when recording / reproducing at a normal speed. 6 is a rotary head drum, 7 is a cassette, 8 is a supply reel, 9 is a take-up reel, 10 is a guide roller, and 11 is a capstan. The tape pulled out from the cassette is loaded in this way, is wound on the drum 180 degrees, and is recorded in the format shown in FIG. The signal processing for producing the recording signal at this time will be described with reference to FIG. In the figure, a is an input video signal, and numbers are scanning line numbers. After this signal is digitized, it is once stored in the field memory and read out in the order of b in the next field period.
That is, this signal is obtained by reading the odd-numbered scan lines in the first half of the field and reading the even-numbered scan lines in the latter half of the field and returning them to analog signals. This signal is FM-modulated and recorded like a normal VTR. Therefore, in the recording format shown in FIG. 3, information of one entire screen is recorded in both the lower half and the upper half of the track. Next, FIG. 1 shows a tape loading state during high speed retrieval. The tape is wrapped 90 degrees around the drum, with only the lower half of the recording track in contact with the head.

When the tape is run at high speed in this state and played back, the signal obtained is only from the lower half of the tape, but since the signal processing described above has been performed, all odd lines are played back and the signal for the entire screen is obtained. . From this signal, an even-numbered scanning line signal is generated by interpolation processing, stored again in the field memory, and then read out to obtain a signal close to a normal reproduction signal.

Thus, by making the tape winding angle during high-speed search smaller than that during normal reproduction, the friction resistance between the tape and the drum can be reduced, the tape speed can be increased, and the search speed can be increased.

Further, in order to increase the search speed, it is also possible to thin out one line from each of the continuous n scanning lines and record in the lower 1 / n to make the wrap angle at high speed reproduction 180 / n degrees.

In the above embodiments, the most general rotary 2-head analog recording VTR has been described, but the input signal is time-axis expanded and divided into a plurality of channels for analog recording.
The same idea holds for VTRs and segment-recorded VTRs.

Further, in the case of a digital VTR that records a video signal as a digital signal, generally, shuffling is performed in which the signal of the entire screen is dispersed and recorded on each part of the tape in order to effectively perform error correction. The same effect can be obtained by performing the recording signal processing so that the signals of the entire screen thinned out in a part of the width direction of the tape are recorded.

EFFECTS OF THE INVENTION As described in detail above, according to the present invention, the tape winding angle on the drum during high-speed search is significantly reduced, and the information of one entire screen is recorded in the reduced winding angle range. It is possible to increase the tape running speed and improve the search speed while maintaining the discriminability of the reproduced image at the time of high-speed search.

[Brief description of drawings]

FIG. 1 is a plan view showing a tape loading state during high-speed search in one embodiment of the present invention, and FIG. 2 is a plan view showing a tape loading state during recording or normal reproduction in one embodiment of the present invention. FIG. 3 is an explanatory diagram of a recording pattern on a tape according to an embodiment of the present invention, and FIG. 4 is a simple explanatory diagram of recording signal processing according to an embodiment of the present invention.
The figure is an illustration of a recording pattern on a tape in a conventional rotary 2-head VTR.

Claims (1)

[Claims] 1. At the time of normal recording / reproducing, almost the entire width of the tape is wound around a rotating drum to record / reproduce the video signal as an oblique track on the tape, and at high speed reproduction, the winding angle of the tape around the drum is a normal n minutes. By setting it to about 1, in the video signal recording / reproducing method in which a width of about 1 / n of the tape is wound around the rotating drum to be reproduced, when the video signal is recorded, the winding angle of the tape around the drum during high-speed reproduction is set. The information of the whole screen made by thinning the input signal is recorded on a part of the diagonal track where the tape contacts the head when it is set to about 1 / n of a normal value, and it is recorded on a part of the diagonal track at the time of high speed reproduction. A video signal recording / reproducing method characterized by reproducing the information of the entire screen from the recorded information.