JPH01248775A - Variable speed reproduction device for time lapse vtr - Google Patents

Abstract

PURPOSE:To attain the recording of audio information and to facilitate the retrieval seeking an object location by providing a means applying time axis compression to the audio signal and using a rotary head so as to form an audio track between video recording tracks. CONSTITUTION:The audio signal IN is subject to time axis compression and the compressed audio signal is recorded between video recording tracks through the rotary head 4 at the halt of a magnetic tape. The operation is repeated for each intermittent feed at a prescribed time interval and the consecutive audio signals are recorded on the audio recording track one after another even with the intermittent feeding. While the magnetic tape is run continuously, it is possible to attain high speed reproduction and the audio signal for the only prescribed value or more of the reproduced signal envelope is fetched once in a semiconductor memory 8 and expanded after the fetch, then the audio signal is restored to the original signal (such as nearly for 1.5sec). While the audio signal is being decoded, the fetch of the audio signal into the memory 8 from the audio track is inhibited. Thus, the audio signal corresponding to the high speed reproduced pattern of the video signal is reproduced for nearly 1.5sec each and the retrieval to seek an object location is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable speed playback device for a time-lapse VTR that performs long-term recording and playback by intermittent recording and is used for monitoring purposes and the like.

[Conventional technology]

In a rotating head helical scan type VTR (video tape recorder), video signals are recorded as still images at a rate of one sheet every few seconds by intermittent feeding of magnetic tape.
An intermittent magnetic recording and reproducing device called a time-lapse VTR, which performs long-time recording and reproducing of about 40 to 480 hours, is widely used for monitoring purposes in financial institutions and the like.

An example of this intermittent recording time-lapse VTR is:

For example, it is disclosed in Japanese Patent Laid-Open No. 58-62985.

However, time-lapse VTR records intermittently.

The method of recording audio signals on a linear track, which is generally used for VTR audio recording, cannot be used, and the audio recording and playback function using the linear track is only available in an incidental continuous recording mode of about 2 to 12 hours. However, it was not possible to record and reproduce audio in the intermittent recording mode for about 24 to 480 hours, which is actually required for monitoring.

In addition, since time-lapse VTRs record video information over a very long period of time, it is important to have a search function to find the desired location. Search) is possible, but
In the above conventional technology, no consideration is given to the recording and reproducing function of audio signals in the intermittent recording method in which the magnetic tape is repeatedly run and stopped intermittently, and the search function is not searchable only using images. There was a problem in that it only considered search and was insufficient.

An object of the present invention is to enable the recording of audio information even in the intermittent recording method time-lapse VTH, and to facilitate searching for a target location by reproducing the corresponding audio information during high-speed video playback. Time lapse V that can be done
TR variable speed playback device The purpose of the above is to compress the audio signal in the time axis using a semiconductor memory even when the magnetic tape is stopped, and to reproduce the audio between one video recording track and the adjacent video recording track using a rotating head. In addition to providing a means for forming a track, while the magnetic tape is continuously running, only the portion where the signal output level obtained from the audio track exceeds a predetermined value is expanded using the above memory and restored to the original audio. This is achieved by inhibiting the capture of signals derived from audio tracks into the memory.

[Effect]

The audio signal is time-base compressed, and the compressed audio signal is recorded through a rotating head in a guard band area existing between video recording tracks while the magnetic tape is stopped. This operation is repeated every time the intermittent feed is performed at a predetermined time interval, and even in the case of intermittent feed, continuous audio is recorded one after another on the audio recording track.

High-speed video playback is possible while the magnetic tape is running continuously, but the audio signal is also restored to the original audio by first importing only the portion of the playback signal envelope that exceeds a predetermined value into semiconductor memory, and then decompressing it after importing. For example, about 1.5 seconds). Also, while audio is being restored, importing the audio signal from the audio track to memory is prohibited, so the audio corresponding to the high-speed video playback screen can be played for about 1.5 seconds at a time, making it easy to search for the desired location. Search can be made easier.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. .

FIG. 1 is a block diagram of a time-lapse RRX variable speed playback device according to an embodiment of the present invention, in which 1 is a magnetic tape, 4 is an audio rotary head, and 5 is a changeover switch for switching between recording and playback with black circles. The side indicates the playback mode. 6 is an A/D for digitizing the output ADIN of the changeover switch 5.
l) converter, 7 is a digital data bus, 8 is a memory for time axis compression/expansion, and 9 is a converter according to the mode command from the system control (display controller 1 not shown) of the time-lapse VRX (including the mechanism) according to the present invention. A controller for controlling the memory 8 and a PBG for capturing the playback signal from the audio head 4 during playback.
Let 16 be the control signal group including at-. 10 is Di A
(DigitalJtoA%aLogum) converter; 11 is an FM modulator for frequency modulating a compressed audio signal and writing it with the audio rotary head 4; 12 is a changeover switch for switching between recording and playback similar to 5;
3 is a preamplifier for amplifying the signal obtained from the audio rotary head 4 during reproduction; 14 is an FM demodulator for frequency demodulating the output E of the preamplifier to obtain a compressed demodulated audio signal.

15 is a comparator for detecting that the output E of the preamplifier is above a predetermined level, and the predetermined level is the power supply VC.
It is set by a variable resistor 16 connected between C and ground GND. 16 is a group of control signals for controlling the memory from the controller.

2 and 3 show an example of the rotating drum in the embodiment of FIG. 1, with FIG. 2 being a top view and FIG. 3 being a front view.

In the figure, the video rotary head 3.3' has a gap of the same azimuth angle, the audio rotary head 4 has a different azimuth angle from the video rotary head 3.5', and the video rotary head 3.5' has a gap of the same azimuth angle. 3' are at the same height (zero step), and the video rotary head 3.5' and the audio rotary head 4 have a predetermined step d as shown in FIG.

FIG. 4 is a recording pattern diagram recorded by this rotating drum 2, in which the magnetic tape 1 is intermittently
An audio recording track A is formed in a guard band portion between one video recording track V and an adjacent video recording track Vt by moving by a distance corresponding to the track pitch P. In this example, the head widths of the three rotating heads 5.5' and 4 are selected to be approximately half of the track pitch P, and the one step difference d is also selected to be approximately half of P.

Audio recording track A1 e At・Gart band part
... is formed.

Also, a video recording track and an audio recording track Vl.

Track A is created when the magnetic tape 1 is stopped.

FIG. 5 is a diagram showing a reproducing head locus 22 of the audio head 4 during a high-speed search when the magnetic tape 1 is continuously run at high speed in the direction of an arrow 21 for a search or the like.

Note that, in the reproduction of a normal time-lapse VTR, as shown in FIG. 4, the still image is reproduced in a stopped state by repeating intermittent stops and running in the direction of arrow 21 one track pitch P at a time.

Figure 5 shows the head trajectory when the tape running speed is approximately five times the tape running speed in the 2-hour recording mode (a mode in which 2 hours of continuous recording is performed on one VHS tape) of the current time-lapse VTR, and the audio recording Track pattern AHe
Due to the difference in the inclination angle between AHm AB... and the head trajectory 22, only the reproduced signal corresponding to the shaded area in the figure can be obtained.

FIG. 6 is a signal waveform diagram of each part of FIG. 1.

Hereinafter, the operation of the embodiment of the present invention will be explained using the block diagram in FIG. 1 and the signal waveform diagram of each part in FIG. 6.

Recording mode (when the changeover switches 5 and 12 are in white circles, the input audio signal IN passes through the changeover switch 5.

A/I) converter 6 digitizes it for 4 seconds (v
I) /A Convert to analog with converter 0, 1M
Audio recording track stones *AB*js... (FIG. 5) are formed on the tape by the head 4 through the modulator 11. After that, the above operation is repeated again.

In high-speed continuous playback mode (equivalent to 720 times the speed because 480 hours of recording is searched for 2 hours x -), the output signal E from the audio rotary head 4 through the changeover switch 12 and preamplifier 13 (playback shown in Figure 6) (shown in the head output envelope waveform) is demodulated by the 1M demodulator 14, passes through the changeover switch 5, and is digitized by the A/D converter 6 as ADIN. The digitized compressed audio passes through the data bus 7 and is stored in memory.

In Fig. 6, in 5rso, the rotating head 4 is
A signal that is “L” during the period when 1C is applied (approximately 180°) (
(usually corresponds to a head switching signal of a VTR), and the head output envelope E exhibits a diamond shape as shown in the figure only during the STF'50 "L" period. In this embodiment, each of these diamond-shaped portions 51, S2. SS,”r4.35.36
Part 5 of which the level of E is continuously equal to or higher than the predetermined level.
Detects only 2°35 and changes CPBGat- to °H° (approximately 1/
160 seconds) and is captured and stored in the memory 8. Immediately after that, the controller puts the memory into low-speed read mode and restores the audio compressed to about 1/160 seconds to the original audio signal of about 1.5 seconds.

The D/A converter converts the audio to analog and repeats the above steps to obtain the playback audio OUT, producing audio that corresponds to the high-speed video playback screen for about 1.5 seconds without noise.

can be played back at almost the same audio pitch as when it was recorded.

During audio restoration (low-speed reading from the memory 8), the controller 9 controls the capture of the head output E from the audio head 4 into the memory. is taken in, and other head outputs E are ignored during restoration.

The above-mentioned comparator 15 detects that the output level of the reproducing head is higher than a predetermined level.

The output LEV of the comparator 15 is at a predetermined level (a level at which the reproduced audio can be reproduced satisfactorily) or higher in the section @H1.

Next, the specific operation of the controller 9 composed of a micro combinator and the like will be explained using the flowchart shown in FIG.

In order to extract the part (52, 55, etc.) in which the level of E is the longest consecutively above a predetermined level (52, 55, etc.) from each part of the diamond-shaped shadow, and to prohibit the capture of head output to memory during audio restoration. The algorithm is shown in FIG.

First, the falling edge of 5W50 is detected (N is No and is not established.

Y indicates establishment with Yap) and LEV is “H” @L1
Determine whether When “Lo”, it is determined that EEE’ rises, and PBGata is set to 11 when LEV first rises.
” and starts loading into the memory (it may be determined that LEy once falls and then rises again).

Even when LEV is 1L”, determine that LEr rises and press P.
Let B Gat- be °H°. Thereafter, after a delay τ (determined by the tape speed, set to about 1/160 seconds in this example), P B Gate is set to 1L''.

In addition, the point at which this PBGat- is changed to @L” is PBGa
After setting t- to °H", first LEV changes from 1H° to "Lo".
It may be at the time when T (
5W50 again after a delay (about 1.5 seconds in this example).
This is to return to the fall routine.

FIG. 8 is a signal waveform diagram of each part of FIG. 1 for explaining another embodiment of the present invention, and is an example of high-speed playback at a faster tape speed. Note that the configuration is the same as in FIG. 1. In FIG. 8, the number of diamonds in the head output envelope is greater than in FIG. 6. In this case, since the information cannot be used effectively by only reproducing one diamond, the parts PBGat- of parts a, h, and a where the head output E is higher than a predetermined value are set to "H" and stored in the memory. Import it and when restoring 1! By successively reproducing the signals A, B, and c shown in OUT corresponding to eAec, better reproduced audio can be obtained than K.・tr
For example, the determination of ``eble'' may be made by importing only the period in which LEV is @H' for a predetermined length or longer.

In the above description, the comparator 15 is used to determine the predetermined level, but an inverted dropout output signal that is normally used in a video processing circuit (not shown) may also be used.

Further, in the recording pattern shown in FIG. 4, a set of video and audio is formed for each track pitch, but the same is true for other recording patterns such as two track pitches.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to record audio information even in the 1-intermittent recording type time lapse V'rR, and it is compatible with high-speed video playback screens, there is no noise and the audio pitch is almost the same as when recording. It is possible to easily search for a desired location by reproducing good audio information, and it is possible to provide a time-lapse VTR with excellent functions, except for the drawbacks of the above-mentioned prior art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a variable speed playback device for a time-lapse VTR according to an embodiment of the present invention, FIGS. 2 and 3 are top and front views of the rotating drum, respectively, and FIG. 4 is the rotating head of FIG. 2. Recording pattern diagram. FIG. 5 is a head trajectory diagram during high-speed playback, FIG. 6 is a signal waveform diagram of each part in FIG. 1, and FIG. 7 is a flowchart explaining the operation of the controller. FIG. 8 is a signal waveform diagram of each part for explaining another embodiment. 4...Audio head 6...A/
D converter 8...Memory 9...
...Controller 10...D/A converter 11...FM modulator, -1,14...-
・・FM return mHts・・・・・・Con Valley, C7j″
“Figure 1 from the system controller Figure 2 Figure 3 Figure 4 Figure 6 Figure

Claims (1)

[Claims] 1. Means for intermittently repeating running and stopping of the magnetic tape, a rotary head for recording video signals, and means for recording one field of video signals as one video recording track on the magnetic tape during the stop period. Time-lapse VTR with
In this variable speed playback device, a memory compresses and expands the audio signal on the time axis at predetermined intervals, and the time-compressed audio signal is recorded as one video recording track as an audio recording track by the video signal recording rotary head or a separately provided rotary head. means formed between a track and an adjacent video recording track; a means for continuously running the magnetic tape at various speeds during playback; and a means for continuously running the magnetic tape at various speeds; The present invention has a means for importing the video signal into the memory, a means for decompressing the audio after the import and restoring the original audio, and a means for prohibiting the audio signal playback head from importing the audio signal into the memory while the audio is being restored. 1. A variable transmission/reproduction device for a time-lapse VTR, characterized in that it is configured to enable high-speed retrieval of video signals using audio signals.