JPH0521760Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a video signal recording device, and is particularly suitable for use in a VTR for tape editing work.

When editing a tape with a helical scan VTR, you can check the editing points of the video in slow playback or still playback, but the audio is recorded on the longitudinal track of the tape. , it is difficult to confirm with slow playback or still playback. One of the conventional methods for checking audio editing points is so-called preview, in which the editing points (cut-in point, cut-out point) of the video are determined first, and then the editing VTR is used before the cut-in point and after the cut-out point. (Recording VTR)
The playback signal of the playback VTR is electrically switched and monitored from the cut-in point to the cut-out point, respectively, and the audio editing point can be detected by performing a preview playback that reproduces the edited state without actually editing. I've confirmed it. Other ways to play
This is a so-called sync play in which the VTR and recording VTR are rewound before the editing point and then played back to check the splicing state of the audio editing point.

When checking the audio editing points like this, if the audio at the seam point is unnatural, try audio splitting to move the audio editing point forward or backward relative to the video editing point. Confirm again.

Confirming the audio editing points as described above cannot be performed in slow motion or still mode, and therefore requires a lot of time and is extremely complicated.

The present invention aims to improve editing efficiency by making it possible to check the sound at editing points even during slow playback or still playback.

The video signal recording device of the present invention is a video signal recording device that records video signals on a tape using a rotating head and records audio signals in the longitudinal direction of the tape. a time code generator that generates a time code signal indicating the address of each field of a video signal; and a time code generator that receives the audio signal and detects at least one audio signal sample value for each field period of the video signal, and detects the presence or absence of the audio signal. a conversion circuit for converting the output into digital data representing , and a superimposition circuit for superimposing the output of the conversion circuit together with the corresponding time code signal on a predetermined horizontal scanning section of the vertical blanking section of the corresponding field of the video signal. It is characterized by the fact that it is equipped with

With this configuration, when editing, data indicating the presence or absence of an audio signal can be obtained by reproducing the time code of the video signal as well as the data indicating the presence or absence of the audio signal, even in still or slow playback, and thereby the audio before and after the video editing point can be obtained. Since the status can be known, editing work becomes easier. Note that when digitizing and recording audio signal sample values for each field period, a time code recording circuit, etc. can be used, so a relatively simple sampling circuit, analog/digital conversion circuit, and digital signal superimposition circuit can be used. The above purpose can be achieved just by adding.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block circuit diagram of an audio information recording system showing an embodiment of the present invention. FIG. 2 is a time chart showing the operation of FIG. 1.

In this embodiment, a portion of the audio information is recorded on a portion of the video track using a rotating magnetic head. Vertical blanking intervals are used as recording positions on the video track, and VITC (Vertical Interval
Audio information is inserted into empty bits (for example, user bits) of the time code.

FIG. 3 shows the waveform and time chart of this VITC signal.

The VITC signal is inserted continuously, for example, in one horizontal period located further after the last equalization pulse period in the vertical blanking of the video signal. One horizontal period (1H) is shown in FIG. 3A. In FIG. 3A, HD indicates a horizontal sync signal, and BS is a burst signal. Horizontal sync signal
The period of 1.54 [μs] before the leading edge of HD and the period of 9.56 [μs] after this leading edge are the horizontal blanking period, and the VITC signal of that field is inserted in the video period that is 1H minus the horizontal blanking period. The bit frequency _b of the VITC signal is set to _b = 455/ _4h ≈ 1.79 [MHz] when the horizontal frequency is _h , and the period of 1H is equivalent to 113.75 bits. The VITC corresponding to one recording track
The signal is 90 bits and its code structure is
As shown in FIG. 2B, the first two bits and two bits every 10 bits are set as synchronization bits, as shown by the diagonal lines, and the synchronization bits are set as [10]. The four bits after the first synchronization bit and the two bits after the second synchronization bit are set as [10].
The bits are frame codes F1 and F2.
The frame code F1 represents the first digit of the frame address (0, 1, 2...9), and the frame code F2 represents the tenth digit (10, 20, 30). The bit following the frame code F2 is a drop frame bit D, and the bit following that is a field code FL. The first field in a frame is defined as (FL="0"), and the second field in that frame is defined as (FL="1").

each 4 after the 3rd and 4th sync bit
The 4 bits after the 5th and 6th sync bits are the minute codes M1 and M2, and the 4 bits after the 7th and 8th sync bits are the seconds codes S1 and S2. When code H1 and H2
It is said that Furthermore, eight units BG1 to BG8 each consisting of bits are used as user bits. After these synchronization bits, time code, and user bits, an error detection code such as a 7-bit CRC is added.
(Cyclic Redundancy Check) code is attached.

FIG. 3C shows a specific example of the VITC signal, and FIG. 3D shows the signal waveform in that case. In this example, the time code is "23:59:59.29".
frame", the drop frame bit D is "1", and the field code FL is "0".

In this embodiment, the audio signal is recorded on a track along the length of the videotape, and
Part or all of the audio information is inserted into the user bits BG1 to BG8 of the VITC signal.

In the block circuit diagram of FIG. 1, a voice signal (audio signal) is supplied from a terminal 1 to a low-pass filter 2, where high-frequency noise components are cut and band limits are performed. The output of the low-pass filter 2 is supplied to a peak value detection circuit 3 (or an absolute value averaging circuit), and the peak value or the average value of the absolute values of the output is stored in a hold capacitor 4. The hold capacitor 4 is discharged at the beginning of each field by the discharge switch 5 which is instantaneously turned on by the reset pulse g shown in FIG. 2G. The reset pulse g is generated by a timing pulse generator (not shown) in synchronization with the vertical synchronizing signal V-SYNC included in the video signal of FIG. 2A.

The audio level information stored in the hold capacitor 4 is supplied to an n-bit A/D converter 7 via a buffer amplifier 6 and converted into digital data. Note that the above-mentioned low-pass filter 2,
The peak value detection circuit 3, the hold capacitor 4, the discharge switch 5, the buffer amplifier 6, and the A/D converter 7 provide at least one signal at one field interval.
It constitutes a conversion circuit that converts two audio signal sample values into digital data. The A/D converter 7 does not have to have particularly linear conversion characteristics, and may have band compression characteristics. A/D converter 7
The upper m bits of the n-bit output are stored in RAM8.
and is written to a predetermined address in the RAM according to the write address given from the address counter 9. By cutting off the lower bits,
The user bits of the VITC signal can be used effectively, and the minute level audio signal containing noise can be cut out, so the noise margin can be improved.

The 4-bit address counter 9 is cleared in the first half of each frame by the delayed frame pulse c shown in FIG. Steps from 0 to 3 every latch pulse e and f in FIG. 2 E and F. Therefore, the clock input CK of the counter 9 is given a clock pulse h (=e.f) shown in FIG. 2H. In a timing pulse generator (not shown), the delayed frame pulse c is generated in synchronization with the frame pulse shown in FIG. 2B, and the latch pulses e, f
are formed at the falling edge (leading edge) and rising edge (trailing edge) of the vertical blanking pulse shown in FIG. 2D. Further, the clock pulse h is formed by ANDing the latch pulses e and f.

Each time the write address formed by the address counter 9 increments, the audio data output from the A/D converter 7 is loaded into the RAM 8.
As shown in FIG. 2F, the audio level data of the odd field period of the nth frame is stored in the RAM. Also, in address 1, as shown in FIG. 2F, the audio level data of the vertical blanking section between the odd field and the even field of the nth frame is stored. Similarly, in address 2, the audio level data of the nth frame is stored.
Even field period of the frame (see FIG. 2E)
The audio level data of the nth address is
The first vertical blanking period of a frame (the second
The voice level data of FIG. F is stored.

The audio level data sequentially stored in the RAM 8 is read out based on the read address given from the VITC generator 10 and sent to the VITC generator 10. The read address is formed according to the timing of the user bits of the VITC signal (BG1, BG2...BG8 in Figure 3B), for example, BG1, BG2.
A read address of address 0 of RAM 8 is formed at the location. Note that the RAM 8 and the read address for each user bit given from the VITC generator 10 constitute a superimposition circuit for inserting audio digital data into the vertical blanking section. The audio level data read from RAM8 is
The signal is taken into the shift register in the VITC generator 10, inserted into the user bit section of the VITC signal shown in FIG. 3D, and output as a serial signal to the video recording circuit.

Thereafter, in the same manner, the audio level information of the field section and vertical blanking section of each frame is sequentially taken in and read out.

During editing, audio level data can be played back from the VITC signal even when the VTR is in still playback or slow playback, so when you are determining the editing point of the video, you can check the state of the audio signal at this editing point. (presence or absence) can be confirmed. In other words, the work of determining the video editing point and the work of determining the audio editing point can be performed simultaneously while checking the mutual relationship. The reproduced audio level data may be converted into an analog signal and displayed, for example, as a bar graph, or may be modulated into an audible frequency signal and reproduced as a signal tone by a speaker.

Note that since the vertical blanking interval is the video switching point, the vertical blanking interval (second
By referring to the reproduced signal of the audio level data extracted and recorded in (Figures, etc.),
It is possible to detect the presence or absence of audio at a video editing point.

In addition, tape editing work is performed while referring to the track address display displayed based on the reproduced VITC signal, so as in the above embodiment, audio level data is inserted into the VITC signal to determine the audio editing point. If this is done, it will be extremely convenient in terms of both the hardware and software of the editing device, and in particular, the existing VITC system can be used to implement the audio level data recording and reproducing system according to the present application. The circuit does not become complicated, and practical effects can be obtained with an extremely simple circuit.

In the embodiment, the VITC signal is used, but this may be other track address data or time code.

As described above, the present invention inserts a time code signal indicating the field address of a part of the vertical blanking section of the video signal and records it on the video track, and also digitally records at least one audio signal sample value for each field period. This is a video signal recording device that records data in a vertical blanking section of a corresponding field in a superimposed manner together with a time code signal as data indicating the presence or absence of an audio signal.

Therefore, according to the present invention, even if slow or still playback is performed while determining the editing point of a video, information indicating the presence or absence of an audio signal can be obtained by playing back. Since the state of the audio before and after the video editing point can be checked, video editing work becomes extremely reliable and easy. especially,
Since data indicating the presence or absence of an audio signal can be obtained together with the time code, it is extremely easy to set editing points for both video and audio using these data.

Furthermore, since digital data indicating the presence or absence of an audio signal is recorded in the vertical blanking section along with the time code, the recording circuit for the time code signal, which is editing information, etc. can be shared, which avoids complicating the system. The above effects can be obtained with a simple additional circuit.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an audio information recording system showing an embodiment of the present invention, Fig. 2 is a time chart showing the operation of Fig. 1, and Fig. 3 is a waveform diagram and time chart showing the VITC signal. . In addition, in the symbols used in the drawings, 3...Peak value detection circuit, 4...Hold capacitor, 7...
A/D converter, 8...RAM, 10...VITC generator.

Claims (1)

[Scope of Claim for Utility Model Registration] A video signal recording device that records a video signal on a tape using a rotating head and records an audio signal in the longitudinal direction of the tape, the video signal being recorded on the tape. a time code generator that generates a time code signal indicating the address of each field; A conversion circuit for converting into data, and a superimposition circuit for superimposing the output of the conversion circuit together with the corresponding time code signal on a predetermined horizontal scanning section of the vertical blanking section of the corresponding field of the video signal. A video signal recording device characterized by: