JPS63179486A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain accurate time information by using field sequence information recorded on a video track to correct a time code in the tape lengthwise direction. CONSTITUTION:A PLL circuit 4 reproducing a video signal superimposed with an ID signal recorded on a tape azimuth track to discriminate a field, a time code reader 23 reproducing the time code recorded on the lengthwise track of the tape, a flip-flop 14 separating the ID signal from a video signal superimposed with the ID signal and a CPU 15 receiving the reproduced time code and the ID signal to generate time information are provided. Moreover, a SMPTE time code is recorded on the track in the lengthwise direction of the magnetic tape. Then the field ID (identification) signal in the recording signal is reproduced to correct the time code reproduced from the track of the lengthwise direction of the tape. Thus, the time information corresponding accurately to the reproduced video signal is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal recording and reproducing device, and particularly to a technique for generating time information synchronized with a reproduced video signal.

[Summary of the invention]

The present invention provides a video signal recording and reproducing device that records/reproduces video signals on a tape using a rotating head.
The field [D (identification) signal inserted in the recording signal] is played back, and this field [[D] uses the pedestrian nature of the D signal to correct the time code played from the longitudinal track of the tape, By recording time code data in a track and reproducing this time code data by dynamic tracking, time information that accurately corresponds to the reproduced video signal can be obtained without the need for specialized hardware for time information reproduction. It will be done.

[Conventional technology]

In a rotary head type digital VTR, during low-speed playback, in which the magnetic tape is run at a slower speed than during recording, the playback video signal is stored in memory, and signal processing is performed to repeatedly read out the playback video signal of the same field from the memory. Ru. Therefore, even if an SMPTE time code or the like is recorded in the longitudinal direction of the magnetic tape, the reproduced video signal read from the memory and the time information do not correspond.

Conventionally, as shown in Japanese Unexamined Patent Publication No. 58-14390, there is a known technique that uses the count value of a control signal recorded at regular intervals in the longitudinal direction of a magnetic tape when the time code becomes unreadable. . However, the count value of the control signal becomes erroneous if even one control signal is missing, which has the drawback of low reliability.

As a highly accurate method, a method is known in which time code data (referred to as V ITC) is recorded within the vertical blanking period of the video signal.

However, when using VITC, there is a drawback that a dynamic tracking function for accurately scanning diagonal tracks even during low-speed playback and a reader/generator dedicated to VITC are required.

[Problem that the invention seeks to solve]

In the case of a digital VTR, a field ID signal indicating the field to which the data belongs is inserted into the recorded/reproduced data. In the case of NTSC system, 4
Since it is a sequence of fields, (Fl→F2→F
A field ID signal indicating a change (3→F4) is inserted.

An object of the present invention is to provide a video signal recording and reproducing apparatus that uses a field ID signal, has high accuracy, and does not require a dedicated reader/generator.

[Means for solving problems]

The present invention provides a video signal recording and reproducing device for recording and reproducing video signals on a tape using a rotating head, which includes a circuit for reproducing video signals recorded on diagonal tracks of the tape and superimposed with ID signals for identifying fields; A circuit for reproducing the time code recorded on the long track of the 3D, a circuit for separating the ID signal from the video signal superimposed with the ID signal, and a circuit for generating time information by supplying the reproduced time code and ID signal. It is equipped with a circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In this example, digital video signals are recorded on a magnetic tape as diagonal tracks using a rotary head, and SMPTE time codes are recorded on the longitudinal tracks of the magnetic tape.

In FIG. 1, l indicates a rotating head, and the rotating head l
The signal reproduced from the magnetic tape is transferred to the rotating transformer 2.
and is supplied to the PLL circuit 4 via the reproduction amplifier 3. The PLL circuit 4 reproduces a pit clock synchronized with the reproduction signal. The reproduced data from the PLL circuit 4 is supplied to a serial-to-parallel conversion circuit 5, where it is converted into, for example, 8-bit parallel data. This playback data is sent to the inner code decoder 6.
and is supplied to the field 10 detection circuit 7.

In order to deal with errors that occur during the recording/playback process of digital video signals, the recorded digital video signals are
An error correction code is encoded.

As the error correction code, a product code is used that encodes an error correction code for each of the vertical and horizontal directions of a two-dimensional array of data. The inner code is one error correction code of the product code, and the other error correction code is called the outer code.

Output data of inner code decoder 6 is supplied to field memory 8 . The field memory 8 has a memory capacity for, for example, three fields, and when a plurality of tracks are played back across multiple tracks during low-speed playback and video data of different fields is obtained in one scan. , field I
It is written to memory in its own field indicated by the D signal. Reading from the field memory 8 is performed for each field by a read start pulse RD from the terminal 9.

The reproduced digital video signal read from the field memory 8 is supplied to the digital flip circuit IO. The deshuffling circuit IO performs a process opposite to the shuffling process (rearrangement of the order of data) performed during recording.
The output data of the deshuffling circuit H1O is supplied to the outer code decoder 11, and error correction of the outer code is performed. An error-corrected reproduced digital video signal is taken out from an outer code decoder 11 to a terminal 12.

The data to be recorded/reproduced has a data structure in units of one block, as shown in FIG. 2, for example. At the beginning of the l block, a block synchronization signal is located, followed by a field ID signal, and furthermore, a block address signal and data are located.

In the case of a 4-field sequence, the field 10 signal consists of 2-bit signals IDO and IDI, as shown in FIG. 3, and these field 10 signals rD
o and fDl indicate the sequence (Fl→F2→F3→F4).

The field ID signals IDO and IDI detected by the field ID detection circuit 7 are transmitted to the field 10 memory 13.
supplied to This field ID memory 13 has the same amount of delay as the data in the field memory 8,
The 2-bit signal read from the field ID memory 13 is converted into a signal synchronized with the read start pulse RD by the flip-flop 14. This flip flop 1
The 2-bit signals IDIG and IDII from 4 are sent to the CPU
15.

Further, 21 indicates a fixed head for reproducing the SMPTE time code recorded on the longitudinal track of the magnetic tape.The reproduction signal of this fixed head 21 is supplied to the time code reader 23 via the reproduction amplifier 22. The output data of the time code reader 23 is supplied to the CPU 15.

The CPU 15 corrects the reproduction time code using a 2-bit field ID signal and generates a time code synchronized with the reproduction video signal. The time code from the CPLJ 15 is supplied to the display device 25 to display the time and is also used for editing processing by the editing device 25.

FIG. 4 is a flowchart showing the time code correction operation performed by the CPU 15 every frame. First, in step ■, it is determined whether low-speed playback is being performed,
During low-speed playback, the field ID of one frame before is compared with the current field ID (step ■).
If the two match (step ①), no correction operation is performed, and if they do not match, a correction operation is performed. In the case of a mismatch, the transients of the field ID are examined in steps - and -.

Field ID transient is (F2→F3) (
When it is found in step (2) that there is a change from field F2 to field F3) or (F4→Fl), 1 is added to the frame value TC of the reproduction time code (step (2)).

On the other hand, the transient of field ■D is (Fl→F4
) or (F3→F2), when it is found in step
is subtracted (step ■).

In the addition operation performed in step (2) or the subtraction operation performed in step (2), the drop frame of the time code and the format of the recorded/playback video signal (30 frames or 25 frames) are taken into consideration.

The time code correction operation will be explained in more detail with reference to the time chart shown in FIG.

FIG. 5 shows a reproducing operation in which the running speed of the magnetic tape is slower than that during recording.

FIG. 5A shows a field of a digital video signal that is reproduced by the rotary head l and written into the field memory 8. From the field memory 8, as shown in FIG. The converted digital video signal is read out. In this case, the fifth
A read start pulse RD shown in FIG. E, that is, a reference field synchronization signal is used. Field ID detection circuit 7
Field ID signals IDO and IDI detected by
is synchronized with the reproduced digital video signal, as shown in FIG. 5C.

From the flip-flop 14, the ID signal ID10°IDll shown in FIG. 5 is read out in synchronization with the digital video signal read out from the field memory 8 (FIG. 5B). This ID signal ID10. The correction operation shown in FIG. 4 is performed on the reproduction time code shown in FIG. 5F at the timing of each frame of ID1l. In the example shown in FIG. 5, the time code is corrected so that it changes from N to (N+1) at the transient when the field changes from F2 to F3.

Note that the present invention can also be applied to a case where low-speed playback is performed when a small amount of pre-roll is performed during an editing operation. Furthermore, the present invention can be applied to analog VTRs as well as video signal recording and reproducing apparatuses that insert field identification signals into reproduced video signals.

〔Effect of the invention〕

In this invention, the time code in the longitudinal direction of the tape is corrected using the field sequence information recorded on the video track, so the time code after correction matches the reproduced video signal. According to this invention, there is no need to record a time code such as VITC in a video track, there is no need to prepare a dedicated reader/generator for VITC, and accurate data can be obtained without increasing the scale of hardware. It has the advantage of being able to obtain time information.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIGS. 2 and 3 are route diagrams for explaining the data structure and field 10 signals in this embodiment, and FIG. 4 is a block diagram of this embodiment. A flowchart for explanation and FIG. 5 is a time chart for explanation of this embodiment. Explanation of main symbols in the drawings 1: Rotating head, 7: Field ID detection circuit, 8: Field memory, 13: Field fD memory, 15:
CPU, 21: Fixed head for time code reproduction.

Claims (1)

[Scope of Claims] In a video signal recording and reproducing device that records/reproduces video signals on a tape using a rotating head, a circuit that reproduces a video signal recorded on a diagonal track of the tape and on which an ID signal for identifying a field is superimposed. a circuit for reproducing the time code recorded on the longitudinal track of the tape; a circuit for separating the ID signal from the video signal superimposed with the ID signal; and a circuit for supplying the reproduced time code and the ID signal. and a circuit for obtaining time information.