JP2794567B2 - Digital recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a digital recording / reproducing apparatus suitable for being applied to a digital VTR, and in particular, enables previewing.

[Summary of the Invention]

The present invention relates to a digital recording / reproducing apparatus, and relates to an encoder to which an input digital information signal is supplied and a rotary head to which an encoded input digital information signal is supplied from the encoder and which is recorded on a tape so as to form an inclined track. A recording system, a rotary head for reproducing a recording signal recorded on a tape, and a reproduction system including a decoder that is supplied with a reproduction signal from the rotary head and obtains an output digital information signal, and is supplied to an encoder. A delay unit for supplying an input digital information signal and delaying the input digital information signal supplied to the encoder by a delay time of an output digital information signal obtained from a decoder; Digital information signal and output digital information obtained from decoder By No. provided with switching means for switching the preview mode of no deviation of the reproduced image at the time of switching from the playback state to the monitor state,
In addition, there is no deviation between the content of the reproduced image and the time code of the time code signal recorded along the longitudinal direction of the side edge of the tape.

[Conventional technology]

First, a conventional digital VTR will be described with reference to FIG. First, the recording system RK will be described. Analog color video signal from the input terminal T ₁ (monochrome video signal es) is supplied to A / D conversion circuit (1), for example, while being converted into 8-bit digital color video signal, the vertical blanking A time code signal is added during the line period (a time code signal can be added to an analog color video signal). The digital color video signal (not including the horizontal and vertical synchronization signals and the display signal indicating the phase of the carrier color signal) from the A / D conversion circuit (1) is
It is supplied to the encoder (2) and is coded. In the encoder (2), the digital color video signal is written into a memory having a capacity of about one field, and is read out by performing shuffling, error correction coding, and the like. This coded digital color video signal is
The magnetic tape (4) supplied to the rotating magnetic head (3)
Is recorded so as to form an inclined track. At this time, a time code signal is recorded on the side edge of the magnetic tape (4) by a fixed magnetic head.

Next, the reproduction PK will be described. The coded digital color video signal reproduced from the magnetic tape (4) by the rotating magnetic head (5) is supplied to the decoder (7) and decoded. In the decoder (7), the digital color video signal is written into a memory having a capacity of about one field, and is read out after performing deshuffling, error correction, and the like. At this time, the time code signal recorded on the side edge of the magnetic tape (4) is reproduced by the fixed magnetic head.

The decoded 8-bit digital color video signal from the decoder (7) is supplied to a signal addition and gain adjustment circuit (9), and a reference analog signal from an input terminal (13) from a signal generation circuit (12). A digital phase representing a digital vertical synchronizing signal, a digital horizontal synchronizing signal, and a digital carrier chrominance signal formed with an arbitrary phase based on the reference vertical synchronizing signal, the reference horizontal synchronizing signal, and the reference subcarrier signal of the color video signal RV. The display signal and the clock signal are added, and the gain of the digital luminance signal component and the digital carrier color signal component is adjusted. The digital color video signal from the signal addition and gain adjustment circuit (9) is supplied to a D / A conversion circuit (10), converted into an analog color video signal (including a time code signal), and output. is output to the terminal T _2.

Next, electronic editing (in the case of insert editing) in the VRT will be described. First, when the preview button of the VTR is pressed, the tape is driven to a predetermined location based on a time code signal recorded on the side edge of the tape along the longitudinal direction and then stopped. Thereafter, the tape is caused to run at a constant speed to reproduce a video signal of a predetermined inclined track, and to switch to monitor reproduction of a video signal to be inserted and recorded following the recording signal of the inclined track at an edit recording start point. Can be It should be noted that the tape is caused to run at a constant speed even during monitor reproduction. Then, when the monitor reproduction of the video signal to be insert-recorded ends, that is, when the end point of editing and recording of the tape has passed, the running of the tape is also stopped.

Next, when the edit button is pressed, the tape is stopped after being driven to the above-mentioned predetermined position based on the time code signal recorded on the side edge of the tape along the longitudinal direction. Thereafter, the tape is caused to run at a constant speed, the video signal of the above-mentioned predetermined inclined track is reproduced, and the recording mode is switched at the above-mentioned editing recording start point, and the recording signal of the inclined track is continued. The above-mentioned video signal is insert-recorded until the above-mentioned edit recording end point. And
When the insert recording is completed, that is, when the end point of editing and recording of the tape has passed, the running of the tape is also stopped.

Next, when the review button is pressed, the tape is stopped after being driven to a predetermined location based on a time code signal recorded on the side edge of the tape along the longitudinal direction. Thereafter, the tape is caused to run at a constant speed, and the video signal of the above-mentioned predetermined inclined track is reproduced, and subsequently, the video signal inserted and recorded after the edit recording start point is reproduced. Then, when the insert recording is completed, that is, when the end point of editing and recording of the tape has passed, the running of the tape is also stopped.

In the case of assemble editing, in the preview mode, after the tape is run at a constant speed and a video signal of a predetermined inclined track is reproduced, at the edit recording start point, assemble recording is performed following the recording signal of the inclined track. The monitor playback of the video signal to be attempted is not performed, and after the edit recording start point, the place where the tape is stopped is different from the insert edit described above, and the edit mode and the review mode are different from those in the case of insert edit. The same is true.

[Problems to be solved by the invention]

As described above, in the preview mode at the time of the electronic editing of the VTR, the tape is run at a constant speed, the video signal of the predetermined inclined track is reproduced, and the recording signal of the inclined track is recorded at the edit recording start point. It is switched to monitor playback of the video signal to be inserted continuously,
In the case of the digital VTR shown in FIG. 4, the following problem occurs. This will be described with reference to FIG.

FIG. 5 shows the timing relationship of the video signal of each section of the digital VTR shown in FIG. FIG. 5A shows an analog color video signal a supplied to the A / D conversion circuit (1). FIG. 5B shows an encoded digital color video signal b output from the encoder (2). FIG. 5C shows a digital color video signal c reproduced from the magnetic tape (4) by the rotating magnetic head (5). FIG. 5D shows an analog color video signal d output from the D / A conversion circuit (10). The number in each video signal in FIG. 5 indicates the number of the field.

In the preview mode, when switching from the reproduced digital color video signal c from the rotary magnetic head (5) to the digital color video signal (monitor signal) b from the encoder (2), as described above, the encoder (2) is used. ) Includes a memory having a capacity of about one field, so that the digital color video signal b from the encoder (2) is delayed by about one field as compared with the reproduced digital color video signal c from the rotary magnetic head (5). So
Such switching cannot be employed.

In this case, the delay of the digital color video signal by the encoder (2) can be compensated by selecting the scanning position of the rotary magnetic head (5) (actually, a rotary magnetic head for confidence is used) with respect to the tape. (The field numbers in that case are shown in parentheses in FIG. 5C), but doing so causes the following problem.

That is, regarding the time code signal recorded along the longitudinal direction at the side edge of the magnetic tape (4), the encoder (2) has a large-capacity memory and the reproducing rotary magnetic head (5) Since the rotating magnetic head for confidence is used, the content of the reproduced image does not match the time code of the obtained time code signal.

In view of this point, in the present invention, in the preview mode, there is no shift in the reproduced image at the time of switching from the reproduction state to the monitor state, and the content of the reproduction image and the longitudinal direction of the side edge of the tape are recorded. An object of the present invention is to propose a digital recording / reproducing apparatus in which a time code signal is not shifted from a time code.

[Means for solving the problem]

A digital recording / reproducing apparatus according to the present invention includes an encoder to which an input digital information signal is supplied, and a rotary head to which an encoded input digital information signal from the encoder is supplied and recorded on a tape so as to form an inclined track. A recording system, a rotary head for reproducing a recording signal recorded on a tape, and a reproduction system including a decoder that is supplied with a reproduction signal from the rotary head and obtains an output digital information signal, and is supplied to an encoder. A delay unit for supplying an input digital information signal and delaying the input digital information signal supplied to the encoder by a delay time of an output digital information signal obtained from a decoder; Digital information signal and output digital information obtained from decoder It is provided with a and switching means for switching the issue.

[Action]

According to the present invention described above, the input digital information signal supplied to the encoder is supplied to the delay means, and the input digital information signal supplied to the encoder is delayed by the delay time of the output digital information signal obtained from the decoder for the input digital information signal. In the preview mode, the switching means switches the input digital information signal delayed by the delay means and the output digital information signal obtained from the decoder.

〔Example〕

Hereinafter, an embodiment (digital VTR) of the present invention will be described in detail with reference to FIG. First, the recording system RK will be described. Analog color video signal from the input terminal T ₁ (monochrome video signal es) is supplied to A / D conversion circuit (1), for example, while being converted into 8-bit digital color video signal, the vertical blanking A time code signal is added during the line period (a time code signal can be added to an analog color video signal). The digital color video signal (not including the horizontal and vertical synchronizing signals and the display signal indicating the phase of the carrier color signal) from the A / D conversion circuit (1) is supplied to the encoder (2) to be coded. In the encoder (2), the digital color video signal is written into a memory having a capacity of about one field, and is read out by performing shuffling, error correction coding, and the like. The coded digital color video signal is supplied to the rotating magnetic head (3) and recorded on the magnetic tape (4) so as to form an inclined track. At this time, a time code signal is recorded on the side edge of the magnetic tape (4) by a fixed magnetic head.

Next, the reproduction PK will be described. The coded digital color video signal reproduced from the magnetic tape (4) by the rotating magnetic head (5) is supplied to the decoder (7) and decoded. In the decoder (7), the digital color video signal is written into a memory having a capacity of about one field, and is read out after performing deshuffling, error correction, and the like. At this time, the time code signal recorded on the side edge of the magnetic tape (4) is reproduced by the fixed magnetic head.

The decoded 8-bit digital color video signal from the decoder (7) is supplied to a signal addition and gain adjustment circuit (9) through a changeover switch (8), and an input terminal from a signal generation circuit (12). (13) The digital vertical synchronizing signal VS ₂ and the digital horizontal synchronizing signal HS ₂ formed with an arbitrary phase based on the reference vertical synchronizing signal, the reference horizontal synchronizing signal, and the reference subcarrier signal of the reference analog color video signal RV. , together with the digital phase indication signal NI ₂ and the clock signal CK ₂ represents the phase of the digital carrier chrominance signal is added, the gain adjustment digital luminance signal component and a digital carrier chrominance signal component are performed. The digital color video signal from the signal addition and gain adjustment circuit (9) is supplied to a D / A conversion circuit (10), converted into an analog color video signal (including a time code signal), and output. is output to the terminal T _2.

In this digital VTR, a digital color video signal obtained from a decoder (7) and a digital color video signal supplied to an encoder (2) are switched by a changeover switch (8). ,
When the digital color video signal from the decoder (7) is supplied to the signal addition and gain adjustment circuit (9) or when a monitor signal is to be obtained, the digital color video signal supplied to the encoder (2) is supplied. The changeover switch (8) is switched so that the video signal is supplied to the signal addition and gain adjustment circuit (9).

By the way, in this case, if the digital color video signal supplied to the encoder (2) is supplied to the signal addition and gain adjustment circuit (9) through the direct changeover switch (8), the following problem occurs. . That is, the signal generation circuit (12) outputs the phases of the digital horizontal synchronizing signal HS ₂ , digital vertical synchronizing signal VS ₂ and the digital phase display signal NI ₂ representing the phase of the digital carrier color signal to the input terminal (13 )) When the phases of the reference horizontal synchronization signal, the reference vertical synchronization signal, and the reference phase display signal of the analog reference color video signal are different (this can be set arbitrarily), or an A / D conversion circuit (1) The digital horizontal sync signal HS _{1 of} the digital color video signal output from
The digital vertical synchronizing signal VS ₁ and the digital phase display signal NI ₁ representing the phase of the digital carrier color signal are input to the input terminal (13).
If the reference horizontal sync signal, the reference vertical sync signal, and the reference phase display signal of the analog reference color video signal supplied to the signal generation circuit (12) are different from each other,
When the analog color video signal from the D / A conversion circuit (10) is supplied to the receiver and reproduced, the changeover switch (8)
At the time of switching, there is a possibility that the reproduced image may be out of synchronization or hue, or the reproduced image may be switched in the middle of the screen.

Therefore, in this embodiment, the digital color video signal supplied to the encoder (2) is supplied to the changeover switch (8) through a variable delay circuit and a time base collector (TBC) (14) as a synchronous circuit. I have.

Hereinafter, the time base collector (14) will be described. (15) is a first-in first-out memory (hereinafter abbreviated as FIFO), to which an 8-bit digital color video signal from the A / D conversion circuit (1) is supplied and written. The 8-bit digital color video signal read from the FIFO (15) is supplied to a delay unit (18) with a delay amount of one horizontal period (1H), and after being delayed, a changeover switch ( 8), the signal is supplied to a signal addition and gain adjustment circuit (9). A / D
The clock signal CK ₁ having a frequency (3.58 MHz × 4 = 14.32 MHz) four times the color subcarrier frequency from the conversion circuit (1).
Is supplied as a write clock signal to the write address counter of the FIFO (15). Also, a frequency (3.58 MHz × 4) four times the chrominance subcarrier frequency from the signal generation circuit (12).
= 14.32 MHz) clock signal CK ₂ (clock signal C
Phase for K ₁ is arbitrary) as a read clock signal supplied to the read address counter of the FIFO (15).

Further, the digital display signal NI ₂ representing the phase of the digital horizontal sync signal HS ₁ and the digital carrier color signal from the A / D converter (1) is supplied to the OR gate (16), the period obtained from this A write reset signal WR (see FIG. 2A) equal to two horizontal cycle periods (= 2H) is supplied to the write address counter of the FIFO (15) and reset, whereby the A / D conversion circuit (1) outputs The digital color video signal is written in the FIFO (15) in two consecutive horizontal periods, first, the positive-phase digital carrier chrominance signal and then the reverse-phase digital carrier chrominance signal are written in the FIFO (15). Also, the digital display signal NI ₂ representing the phase of the digital horizontal synchronizing signal HS ₂ and the digital carrier color signal from the signal generating circuit (12).
Is supplied to the OR gate (17), and the obtained cycle is equal to two horizontal cycle periods (= 2H), and has a phase difference equal to one horizontal cycle period with respect to the write reset signal WR in a steady state. The read reset signal RR (see FIG. 2B) is supplied to the read address counter of the FIFO (15) and reset. As a result, the digital carrier chrominance signal of the normal phase is read first, and then the digital chrominance signal of the opposite phase is read from the FIFO (15) in two consecutive horizontal period periods.

In such a TBC (14), in a steady state, the digital color video signal from the A / D conversion circuit (1) is
Delay by one horizontal period, and further by one delay unit (18)
The horizontal cycle is delayed, and eventually two horizontal cycles are delayed. A digital display representing the phases of the digital vertical synchronizing signal VS ₂ , the digital horizontal synchronizing signal HS _2, and the digital carrier color signal supplied from the signal generating circuit (12) to the signal adding and gain adjusting circuit (9). a signal NI ₂ of each of the phase, the signal generating circuit (12), a reference display representing the phase of the reference vertical synchronizing signal of the reference color video signal RV of the input terminal (13), the reference horizontal synchronizing signal and the reference carrier chrominance signal When the signals are changed individually or together, the phase of the read reset signal RR supplied to the FIFO (15) also changes accordingly, so that the digital color video signal obtained from the decoder (7) during reproduction is obtained. And a digital color video signal obtained from the TBC (14) at the time of monitoring by the changeover switch (8) or a digital signal output from the A / D conversion circuit (1). One or both of the phases of the vertical synchronization signal VS ₁ , the digital horizontal synchronization signal HS ₁ and the digital display signal representing the phase of the digital carrier color signal are the reference vertical synchronization signal of the reference color video signal from the input terminal (13), Even if the reference display signal is different from the reference display signal indicating the phase of the reference horizontal synchronization signal and the reference carrier color signal, when the changeover switch (8) is switched, the reproduced image may be disturbed in synchronization or hue, or may be reproduced from the middle of the screen. There is no danger of switching.

By the way, when the digital color video signal (reproduction signal) from the decoder (7) and the digital color video signal (monitor signal) from the TBC (14) are compared, the reproduced image of the reproduced image is larger than the reproduced signal. 2 horizontal cycle periods (=
2H) You will be late.

Therefore, the control signal from the control signal input terminal (7a) allows the reading address counter to start counting in two horizontal cycle periods (= 2
H) By delaying, the read start time of the memory having the capacity of about one field of the decoder (7) is delayed by two horizontal period periods (= 2H), so that the decoder (7) receives the signal from the decoder (7) in the preview mode. The digital color video signal (playback signal) is
The digital color video signal (reproduction signal) from the decoder (7) is delayed by two horizontal cycle periods (= 2H),
No deviation occurs between the reproduced image and the digital color video signal (monitor signal) from the TBC (14).

Therefore, in this case, when the changeover switch (8) is switched in the preview mode, the D / A conversion circuit (1
0), an analog color video signal (reproduction signal) d (FIG. 5D), and an analog color video signal (monitor signal) a (FIG. 5A) supplied to the A / D conversion circuit (1). There is no time delay between the two.

In the preview mode, the changeover switch (8) is automatically switched by a system controller (not shown). However, the digital color video signal from the A / D conversion circuit (1) is simply reproduced on a monitor. If so, it is sufficient to switch manually.

In the decoder (7), as shown in FIG. 3, in the preview mode, instead of delaying the reading start time of the memory having the above-mentioned capacity of about one field of the decoder (7) for two horizontal cycle periods (= 2H), , Decoder (7)
And a delay unit (20) comprising a glass delay line, a charge transfer device, a charge-coupled device, etc., having a delay amount of 2 horizontal cycle periods (= 2H), and an output of the decoder (7) and a delay unit. A changeover switch (21) for switching the output of (20) is provided, and the changeover switch (21) is normally set to a decoder (7).
May be switched to the delay unit (20) only by the control signal from the control signal input terminal (7a) in the preview mode.

According to the digital recording / reproducing apparatus described above, in the preview mode, the changeover switch (8) causes the digital color video signal (reproduction signal) from the decoder (7) and the digital color video signal (monitor) from the TBC (14). Signal), there is no deviation in the reproduced image during that time, there is no deviation between the content of the reproduced image and the time code of the obtained time code signal, and there is also a possibility that the reproduced image will be out of synchronization or hue. Disappears.

In each of the above embodiments, the case where the digital information signal is a digital color video signal has been described.
It may be a digital audio signal.

〔The invention's effect〕

According to the present invention described above, there is no displacement of the reproduced image at the time of switching from the reproduction state to the monitor state in the preview mode, and the recording is performed along the content of the reproduction image and the longitudinal direction of the side edge of the tape. It is possible to obtain a digital recording / reproducing apparatus in which the deviation of the time code signal from the time code is eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a timing chart showing a reset signal thereof, FIG. 3 is a block diagram showing a part of another embodiment of the present invention, and FIG.
FIG. 5 is a block diagram showing a conventional digital VTR, and FIG. 5 is a timing chart showing the relationship between signals of various parts of the digital VTR. (1) is an A / D conversion circuit, (2) is an encoder, (3) is a rotating magnetic head, (4) is a magnetic tape, (5) is a rotating magnetic head, (7) is a decoder, and (8) is switching. Switch, (9) signal addition and gain adjustment circuit, (10) D / A
Conversion circuit, (12) is a signal generation circuit, (14) is a TBC, (1
5) is a FIFO, (16) and (17) are OR gates, (18) is a delay unit, (20) is a delay unit, and (21) is a changeover switch.

Claims (1)

(57) [Claims] 1. A recording system comprising: an encoder to which an input digital information signal is supplied; and a rotary head to which an encoded input digital information signal from the encoder is supplied and recorded on a tape so as to form an inclined track. A rotating head for reproducing a recording signal recorded on the tape and a reproducing signal from the rotating head are supplied;
A reproduction system including a decoder for obtaining an output digital information signal, and an input digital information signal supplied to the encoder, and an output digital information signal obtained from the decoder for the input digital information signal supplied to the encoder And a switching means for switching between an input digital information signal delayed by the delay means and an output digital information signal obtained from the decoder in a preview mode. Recording and playback device.