JP2919501B2 - Video recording or playback system - Google Patents

Description

The present invention relates to a video recording or reproducing system for recording a video signal retroactively from the start of recording.

(B) Conventional technology When recording an audio signal, a configuration in which the audio signal is stored via a delay unit when the audio signal is recorded before the recording start time is awarded.

(C) Problems to be Solved by the Invention However, when a video signal is recorded, an enormous capacity of memory is required to delay the video signal for several seconds. is there.

Therefore, it is necessary to skillfully utilize the limited memory capacity to retroactively record video.

(D) Means for Solving the Problems The present invention provides a video storage unit that intermittently stores input video information and reads video information at a shorter cycle than the storage cycle at the start of recording, A recording system for recording the video information to be read in advance, and recording means for recording the input video information after the reading of the video information stored immediately before the recording start time is completed; And a reproduction system for intermittent slow reproduction of the data.

(E) Action According to the present invention, the video information stored before the start of recording is time-compressed and recorded at the start of recording.

(F) Example Hereinafter, the present invention will be described in accordance with an example that illustrates the present invention.

In this embodiment, the input video information is stored in a video memory having a storage capacity of 16 fields at a 0.5 second cycle, and at the start of recording, each video information is sequentially read from the video memory six times at a time, and is sequentially read from the video memory. The same video information is recorded on the tape recorder every 6 fields, and about 10 fields are recorded.
It records high-speed intermittent video information for about 20 fields per second in about 2 seconds in six tracks.

In the present embodiment, the audio information corresponding to the video information is compressed on the time axis by 1/5 and recorded on the Hi-Fi track.

Further, in the present embodiment, the identification signal is recorded during this time-axis compression recording period, and during the period during which the identification signal is detected during the reproduction, the intermittent slow reproduction at the 1 / 5x speed is performed. The reproduction audio information in the unit of field is extended five times in time axis.

FIG. 1 is an explanatory diagram showing the relationship between the recording and reproduction of the above-mentioned video information. In FIG. 1, A schematically shows the storage information of the video memory at the start of the recording.
Input video information before the field is 16 in 30 field cycle
Indicates that the data is stored for the field. At the time of recording, in view of the fact that the video information 510 fields ago is immediately updated, reading is started from the video information 480 fields ago. This reading is performed six times for each piece of video information in field units.

Therefore, the video information of 480 fields before is recorded on the six tracks from the start of recording, and the video information of 450 fields before is recorded on the next six tracks, respectively. Is updated.

B in FIG. 1 shows information stored in the video memory at the time when 114 tracks have been recorded from the start of recording. At this point, the reading of the latest updated video information (the 90th field from the recording start point) is completed. When the end of the reading is detected, the input video signal is directly recorded thereafter.

In the recording start portion recorded in this manner, the video tape recorder falls into a 1/5 intermittent slow reproduction state by the detecting means described later. As a result, each track is scanned 5 times, and about 10 seconds (114 × 5 fields) corresponding to real time
Is reproduced as intermittent video information. This video is the same video as in the flash playback state. When the intermittent slow reproduction state is completed, the normal reproduction state is set. Note that the audio signal is stored as new field-compressed audio information for one field period every time the reproduction track is updated during the intermittent slow reproduction period, and is formed as the original continuous audio information by expanding the time axis by a factor of five. Derived.

Hereinafter, a recording circuit for performing the above-described operation will be described with reference to FIG.

First, input video information and input audio information are generated from a video information source 1 and an audio information source 2 which constitute an information source such as a tuner or a video camera.

In this state, the input video information is continuously and intermittently stored in the video memory 18 every 30 fields, and the input audio information is continuously and continuously stored in the audio memory 26 for about 8 seconds.

The video storage means 3 including the video memory 18 digitizes input video information by the AD converter means 16 and further compresses the data by the code compression means 17. With this data compression, the capacity of the video memory 18 that was
It has been reduced to bits. The storage of this input video information
Must be done in synchronization with the simultaneous signal of the input video information,
A synchronizing signal obtained from the synchronizing separation circuit 10 for inputting input video information is input to the first write control means 21.
Timing pulses for conversion and code compression and a write address signal are derived. The first memory access means 22 continues to supply the write address signal to the video memory 18 and always keeps the intermittent storage of the input video information.

Further, the audio storage means 4 including the audio memory 26 supplies an AD conversion pulse to the second AD conversion means 25 while changing the write address cyclically so as to function as audio information compression means. Accordingly, the input audio information is digitized in synchronization with the fixed clock, and is sequentially stored at the corresponding write address in the audio memory 26.

When a recording operation is performed in the above-mentioned circulating storage state, the video tape recorder is activated, and the servo circuit 11 of the cylinder capstan is activated in synchronization with the synchronous separation output. When the servo circuit 11 enters the synchronization pull-in state, a phase lock detection signal is generated and the recording start state is set.

At the start of recording, the video storage means 3 sends a write address signal to specify video information to start reading,
Also, a phase lock detection output synchronizing signal for specifying the read timing of the read start video
It is supplied to the reading control means 23. Therefore, the read control means 23 derives a read address signal synchronized with the rotation of the video head 7 after the generation of the phase lock detection signal and a timing pulse for processing the read data. The data read from the video memory 18 is expanded to the original data by the code expansion unit 19, and is converted to analog video information by the first DA conversion unit 20.

The voice information storage means 4 inputs a write address signal to the second read control means 30 in order to specify a read start address. Therefore, the second read control means 30
Generates a read address signal and a timing pulse that is five times as large as that in storage when synchronized with the phase lock detection signal. The data read out from the audio memory 26 in the order from the oldest in accordance with the read address is converted into analog compressed audio information by the second DA converter 27 and is derived.

In this state, the video selection switch 14 and the audio selection switch
15 is set on the storage means side, and the video information is input to the well-known video recording processing means 5 and converted into recorded video information, supplied to the rotating video head 7 and recorded on the video track. The compressed audio information is input to a well-known audio recording processing means 6, converted into recording audio information, and supplied to a rotary audio head 8, where a Hi-Fi track preceding a video track is recorded.

This recording state is ended when the read video information catches up with the write video information in the video storage means 3 . Therefore, the comparing means 24 generates a coincidence output as an end detection signal of the compression recording mode when the write address and the read address coincide with each other.
Is switched to the input information side to enter the normal recording mode.

On the other hand, a control signal generating means for inputting a periodic signal
The control signal 12 is input to the pulse width modulation means 13 and is in a pulse width modulation state from when the phase lock detection output is generated to when the coincidence output is generated. Accordingly, during the compression recording period, the control head 9 records a control signal having a narrow pulse width.

In this embodiment, the control signal is pulse width modulated as the identification signal. However, it goes without saying that the identification signal may be multiplex-recorded during the blanking period of the video information.

Further, it is sufficiently possible to configure the video storage means so that the fields of the video information read from the video storage means as required are odd fields and even fields alternately combined.

In the reproducing circuit shown in FIG. 2 for reproducing a video tape recorded as described above, a control signal having a narrow pulse width reproduced by the control head 9 is used as a recording start end detecting means.
34, the detection output is input to the system control circuit 35. As a result, the system controller 35 sets the video tape recorder to the 1/5 intermittent slow reproduction mode during the detection output generation period.

The playback video information is processed by the playback video processing means 31,
It is directly derived as video information.

The reproduced audio information is processed by the reproduced audio processing means 32 and is input to the audio storage means 4 functioning as the audio decompression means. Since the compressed audio information is intermittently stored in the audio memory 26 at a 5-field cycle, the second write control unit 28
The rotation detection pulse of the rotary audio head and the tape drive pulse of a 5-field cycle generated by the system controller 35 are input. Therefore, the second write control means generates a timing pulse and a write address signal for AD-converting and storing the compressed audio information for one field immediately after the tape drive by the second AD conversion means 25. As a result, the voice memory 26
Stores audio information for five fields in one field period. The second read control means 30 inputs a write address signal for specifying an address where audio information is written, and generates a read address signal and a timing pulse corresponding to the stored address immediately after the end of the write. doing. As a result, the compressed audio information stored in the audio memory 26 is read out after being expanded by a factor of 5 on the time axis by the second reading control means 30 and converted into an analog signal by the second DA conversion means 27.

The audio information derived from the audio storage means 4 is selectively derived through an audio selection switch 33 set on the storage means side during the intermittent slow reproduction period. The derived voice information is selectively derived.

Therefore, at the time of reproduction, intermittent slow reproduction is performed for about 10 seconds during the period in which the pulse width modulated control signal is reproduced at the start of recording, after which normal reproduction is permitted.

When the identification signal is multiplexed in the video information,
Needless to say, it is only necessary to detect the identification signal and perform intermittent slow reproduction.

Further, instead of recording the intermittent storage information in a long cycle as in the present embodiment, the video is compressed, the intermittent storage information in a short cycle is recorded, and a small time is displayed on the monitor while performing the slow playback with the short playback time. It goes without saying that the compressed image on the screen may be displayed as a smoother continuous image.

The recording means and the recording / reproducing means of the present invention correspond to a video tape recorder including a system controller in this embodiment.

(G) Effects of the Invention According to the present invention, video information before recording can be recorded in a memory having a small capacity, and the effect is great.

[Brief description of the drawings]

FIG. 1 is an operation explanatory diagram according to one embodiment of the present invention, FIG. 2 is a block diagram of the recording circuit, and FIG. 3 is a block diagram of the reproducing circuit. 1 ... video information source 3 ... video storage means 4 ... audio storage means

Claims (2)

(57) [Claims] An image storage means for reading out input image information in a field unit at a predetermined cycle for a plurality of fields and reading the video information at a time shorter than the predetermined cycle in order from the video information stored earlier at a recording start time; Recording means for recording the readout output of the video storage means in advance, and after reading out the video information stored immediately before the recording start time, and subsequently recording the input video information. Recording system. 2. A video storage means for reading out input video information in a field unit at a predetermined cycle for a plurality of fields, and reading the video information at a time shorter than the predetermined cycle in order from the video information stored earlier at the start of recording; The readout output of the video storage means is recorded at a constant speed together with the identification signal, and after the readout of the video information stored immediately before the start of the recording is completed, the input video information is subsequently recorded at a constant speed, and during normal playback, A video recording / reproducing system in which recording / reproducing means for performing low-speed reproduction only during an identification signal generation period are arranged.