JPH0636524A - Digital sound signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To make a dubbing tape exactly the same as a master tape at the time of digital dubbing. CONSTITUTION:The device is provided with a changeover circuit 3 for changing a reference signal of a recording counter circuit 6 on the recording side over to a reference signal from a reproducing counter circuit 11 on the reproducing side, and a digital sound recording signal is generated in the same field unit as a digital sound signal on the reproducing side, and is recorded. Then, the recording counter circuit 6 for outputting the reference signal to the outside is provided, and by making the outputted reference signal a reference signal of a recording counter of other device, when the same digital sound signal is inputted to be recorded, the same tape is produced. Then, the changeover circuit for changing the reference signal of the reproducing counter circuit 11 over to a reference signal from a reproducing counter circuit of other device is provided, and hence the digital sound signal is outputted from each individual device in the same timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording / reproducing an audio signal as a digital signal on a video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art In recent years, an audio signal recording / reproducing apparatus, once represented by a compact disc (CD), improves the sound quality and does not deteriorate due to dubbing. The method of recording and reproducing after conversion has become popular.

Also in the audio signal of the VTR, MR86-5, Magnetic Recording Research Society of the Institute of Electronics and Communication, June 19, 1986.
As announced in, the recording and reproduction of digital audio signals as well as video signals have come to be performed.

FIG. 7 shows an example of a recording signal format on a magnetic tape of a VTR. An audio signal converted into a digital signal is time-axis-compressed in units of one field,
It is recorded on the extension line of the video signal.

A conventional digital audio signal recording / reproducing apparatus will be described below. FIG. 8 is a block diagram showing the circuit configuration of this conventional digital voice recording / reproducing apparatus.
In FIG. 8, 31 is an analog / digital conversion (hereinafter referred to as AD conversion) circuit for converting an analog signal into a digital signal, 32 is a switching circuit for switching signals, and 33 is a code for correcting an error in a recording signal. An error correction code generation circuit for generation, 34 is a memory circuit for temporarily storing a recording signal, 35 is a counter circuit for controlling the memory circuit 34, 36 is a modulation circuit for modulating the recording signal into a signal most suitable for recording, and 37 is a reproducing circuit. Demodulation circuit for demodulating signals, 3
8 is an error correction circuit that corrects an error in the reproduced signal, 39 is a memory circuit that temporarily stores the reproduced signal, and 40 is the memory circuit 3
A counter circuit which controls 9 and 41 is a digital-analog conversion (hereinafter referred to as DA conversion) circuit which converts a digital signal into an analog signal.

The operation of the digital audio signal recording / reproducing apparatus configured as described above will be described below.

At the time of recording, an input audio signal which is an analog signal is input to the AD conversion circuit 31 and converted from an analog signal to a digital audio signal. The converted digital audio signal passes through the switching circuit 32 and is input to the memory circuit 34.

On the other hand, when performing digital dubbing,
An input digital audio signal that is directly input as a digital signal is selected by the switching circuit 32 and input to the memory circuit 34.

The digital voice signal input to the memory circuit 34 is temporarily stored in a unit of one field, the error correction code generating circuit 33 generates a code for error correction, and then the time axis compression is applied to the modulating circuit 36. Entered in. The control of the signal in the memory circuit 34 at this time is performed by the counter circuit 35.
By controlling the address signal of the memory circuit 34, and the counter circuit 35 operates in units of samples of the digital audio signal with the recording field signal of the video signal as a reference.

The digital voice signal input to the modulation circuit 36 is modulated into a signal most suitable for recording and output, and is recorded in the VTR as a digital voice recording signal.

During reproduction, the digital audio reproduction signal reproduced from the VTR is demodulated by the demodulation circuit 37 and input to the memory circuit 39.

The digital audio reproduction signal input to the memory circuit 39 is temporarily stored in units of one field, and after error correction is performed by the error correction circuit 38, it is expanded on the time axis to D.
The digital signal is input to the A conversion circuit 41 and is output as an output digital audio signal as it is as a digital signal for digital dubbing. The control of the signal in the memory circuit 39 at this time is performed by the counter circuit 40 controlling the address signal of the memory circuit 39.
Operates on a sample basis of a digital audio signal with reference to the reproduced field signal of the video signal.

The digital audio signal input to the DA conversion circuit 41 is converted from a digital signal to an analog signal and output as an audio signal.

Since the digital audio signal is recorded and reproduced together with the video signal, the sampling frequency of the digital audio signal must be synchronized with the field frequency of the video signal. Generally, a PLL circuit is used for the video signal. Generated.

FIG. 9 shows a timing chart of the above signal processing. The hatched portion of the input audio signal is an audio signal for one field, which is always in a constant time relationship with the recording field signal of the video signal. By operating the counter circuit 35 with the recording field signal as a reference, The digital audio signal of the portion (1) is stored in the memory circuit 34 as a signal for one field. Then, after generating the error correction code, the time axis compression is performed and the modulation is performed to obtain a digital voice recording signal.

On the other hand, the digital audio reproduction signal for one field (hatched portion) is demodulated and stored in the memory circuit 39. Then, after error correction, time axis expansion is performed and the output audio signal is obtained.

Here, the output audio signal must have the same temporal relationship between the input audio signal and the video signal at the time of recording as to the video signal output at the same time. Therefore, the counter circuit 40 is based on the reproduction field signal of the video signal.
, The audio signal can be output to the video signal in the same time relationship as that at the time of recording.

[0018]

However, when performing digital dubbing with the above-mentioned conventional configuration, the digital audio signal is a continuous signal, and there is no time reference signal such as the field signal of the video signal. On the reproducing side, the reproducing counter circuit is operated on the basis of the reproducing field signal of the video signal, and on the recording side, the recording counter circuit is operated on the basis of the recording field signal of the video signal. At this time, although the recording or reproducing field frequency of the video signal and the sampling frequency of the digital audio signal are synchronized in frequency, it is general that the phase relationship in sample units is not guaranteed. Particularly, in the case of the NTSC system, the field frequency of the video signal is 59.94 Hz, and the sampling frequency of the commonly used digital audio signal is 48 kHz.
And are not integer multiples in field units.

Therefore, there are cases where the first sample data of one field delimiter of the reproducing side digital audio signal is not necessarily the first sample data of one field delimiter of the recording side digital audio signal.

That is, a dubbing tape in which a digital audio signal is recorded in exactly the same field unit as that of the master tape on the reproducing side cannot be formed, and when dubbing is repeated, a time difference occurs with the video signal. Had.

When a plurality of VTRs are operated in synchronization and the same input digital audio signal is recorded, the counter circuit is operated with the recording field signal of the video signal as a reference. Therefore, each VTR is operated for the same reason as above. The recorded tape has a problem in that it may not be a tape in which digital audio signals are recorded in the same field unit.

When a plurality of VTRs use the same tape for synchronous operation, the reproduction counter circuit is operated by the reproduction field signals of both video signals. Therefore, the output digital audio signal of the output digital audio signal is output for the same reason as above. The timing may not match perfectly on a sample-by-sample basis.

Therefore, there is a problem that a discontinuity occurs due to a difference in sample data when switching both output digital audio signals, and appears as noise when converted to an analog audio signal.

The present invention solves the above-mentioned conventional problems, and when digital dubbing is performed, a dubbing tape completely the same as the master tape can be produced.

Further, when a plurality of VTRs are operated synchronously, the same input digital audio signal can be recorded on each VTR and the same tape can be produced, and the timing of each output digital audio signal can be perfectly controlled. It is an object of the present invention to provide a recording / reproducing apparatus for digital audio signals which can be matched.

[0026]

To achieve this object, a digital audio signal recording / reproducing apparatus of the present invention controls a memory circuit for storing an input digital audio signal at the time of recording and outputs a reference signal to the outside. The counter circuit includes a counter circuit and a switching circuit that switches between a reference signal from the inside and a reference signal from the outside and outputs the reference signal as the reference signal of the counter circuit.

Further, it has a circuit configuration provided with a circuit for outputting a field synchronization signal from the reproduction counter circuit to the outside.

Further, it has a circuit configuration provided with a switching circuit for switching a reproduction field signal of an internal video signal and a field synchronization signal inputted from the outside as a reference signal of the reproduction counter circuit.

[0029]

According to the present invention, when the digital dubbing is performed, the reference signal of the recording counter circuit on the recording side is switched to the reference signal from the reproducing counter circuit on the reproducing side to perform digital dubbing on the reproducing side. A digital audio recording signal can be generated and recorded in the same field unit as.

Further, when performing the synchronous operation and recording,
By inputting the reference signal of one recording counter circuit to another VTR and using it as the reference signal of the recording counter circuit, digital audio signals can be recorded at the same timing in all VTRs.

Further, in the case of performing the synchronous operation and the reproduction,
By inputting the reference signal of one reproduction counter circuit to another VTR and switching it to the reference signal from the reproduction counter circuit, all can output digital audio signals at the same timing.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the circuit arrangement of a digital audio signal recording / reproducing apparatus according to the first embodiment of the present invention. In FIG. 1, 1 is an AD conversion circuit, 2 and 3 are switching circuits, 4 is an error correction code generation circuit, 5 is a memory circuit, 6 is a counter circuit, 7 is a modulation circuit, 8 is a demodulation circuit, and 9 is an error correction circuit. Reference numeral 10 is a memory circuit, 11 is a counter circuit, and 12 is a DA conversion circuit.

The operation of the digital audio signal recording / reproducing apparatus of this embodiment constructed as above will be described below.

During recording, the input audio signal is the AD conversion circuit 1
Is input to and converted from an analog signal to a digital voice signal. The converted digital audio signal passes through the switching circuit 2 and is input to the memory circuit 5.

The digital voice signal input to the memory circuit 5 is temporarily stored in units of one field, and after the error correction code generation circuit 4 generates a code for error correction,
The time axis is compressed and input to the modulation circuit 7. The control of the signal in the memory circuit 5 at this time is performed by the counter circuit 6, and the counter circuit 6 operates based on the recording field signal of the video signal input through the switching circuit 3.

The digital audio signal input to the modulation circuit 7 is modulated into a signal most suitable for recording and output, and is recorded on the tape as a digital audio recording signal.

On the other hand, at the time of digital dubbing, the input digital audio signal is selected by the switching circuit 2 and input to the memory circuit 5, and the switching circuit 3 outputs a field synchronization signal synchronized with the input digital audio signal input from the outside. One is selected and output to the counter circuit 6.
The counter circuit 6 operates on the basis of this input field synchronizing signal, and the input digital audio signal is stored in the memory circuit 5.
Remember.

During reproduction, the reproduced digital audio reproduction signal is demodulated by the demodulation circuit 8 and input to the memory circuit 10.

The digital audio reproduction signal input to the memory circuit 10 is temporarily stored in a unit of one field, and after error correction is performed by the error correction circuit 9, it is expanded on the time axis and DA is added.
The digital signal is input to the conversion circuit 12 and is output as a digital signal as an output digital audio signal. At this time, the counter circuit 11 controls the signal in the memory circuit 10.
The counter circuit 11 operates on the basis of the reproduced field signal of the video signal and outputs a field synchronization signal synchronized with the output digital audio signal to the outside.

The digital audio signal input to the DA conversion circuit 12 is converted from a digital signal to an analog signal and output as an audio signal.

FIG. 2 shows a connection diagram of signals when digital dubbing is performed, and FIG. 3 shows a timing chart of the signals.
The recording / reproducing device 13 on the reproducing side outputs an output digital audio signal and a field synchronization signal indicating the position of the first sample data at the delimiter of one field of the output digital audio signal.

In the recording / reproducing apparatus 14 on the recording side, the same signal is input as an input digital audio signal and an input field synchronizing signal, and the counter circuit for recording uses the field synchronizing signal from the reproducing side as a reference to input the signal shown in FIG. It operates so that the sample data A of the digital audio signal is stored in the memory circuit as the first sample data of one field delimiter. As a result, the digital audio recording signal is generated and recorded at the same one-field division as the one-field division of the reproducing side digital audio signal.

As described above, according to the present embodiment, when performing digital dubbing, the reproducing side records the field synchronizing signal synchronized with the output digital audio signal from the counter circuit which controls the memory circuit for storing the digital audio reproducing signal. By providing a switching circuit for switching the reference signal of the counter circuit for controlling the memory circuit for storing the input digital audio signal on the recording side to the field synchronizing signal synchronized with the input digital audio from the reproducing side, the reproducing side is provided. It is possible to create a dubbing tape in which a digital audio signal is recorded in exactly the same field unit as the master tape of.

In FIG. 4, two VTRs perform synchronous operation,
By inputting the reference signal of one recording counter circuit to another VTR and using it as the reference signal of the recording counter circuit, 2
It is a connection diagram in the case of recording a digital audio signal at the same timing in a VTR of a stand. From the recording / reproducing device 15,
As shown in FIG. 1, a recording field synchronizing signal synchronized with the recording field signal which is the reference signal of the recording counter is outputted and inputted to the recording / reproducing apparatus 16. In the recording / reproducing apparatus 16, the field synchronization signal input as shown in FIG. 1 is switched to the recording field signal and used as the reference signal of the recording counter.

As a result, the recording / reproducing apparatus 15 and the recording / reproducing apparatus 16 can record the digital audio signals input at the same timing on the tape, and can prepare the same recording tape. .

FIG. 5 is a block diagram showing the circuit configuration of a digital audio signal recording / reproducing apparatus according to the second embodiment of the present invention. In FIG. 5, 21 is a demodulation circuit, 22 is an error correction circuit, 23 is a memory circuit, 24 is a counter circuit,
Reference numeral 25 is a DA conversion circuit, which has the same configuration as that of FIG. The difference from FIG. 1 is that a switching circuit 26 for switching the reference signal to the counter circuit 24 is provided.

The operation of the digital audio signal recording / reproducing apparatus configured as described above will be described below.
The digital audio reproduction signal from the VTR is subjected to the same signal processing as that of the first embodiment, and is output as an output audio signal or as an output digital audio signal as a digital signal.

At this time, the counter circuit 24 operates with the reproduction field signal of the video signal selected by the switching circuit 26 as a reference signal, but operates with the field synchronization signal from the outside also selected by the switching circuit 26 as a reference signal. You can also do it. Then, as in the first embodiment, a field sync signal synchronized with the output digital audio signal is output.

FIG. 6 shows a signal wiring diagram in the case of performing the synchronous operation. The recording / reproducing device 27 outputs a field sync signal synchronized with the output digital audio signal.

The field reproducing signal is input to the recording / reproducing device 28, and the reproducing counter circuit is the recording / reproducing device 27.
By using the field synchronization signal from the above as a reference, it operates in synchronization with the reproduction counter circuit of the recording / reproducing device 27. As a result, both output digital audio signals controlled by the counter circuit and output from the memory circuit are output at the same timing with the same division of one field.

As described above, according to the present embodiment, when the synchronous operation is performed, the field synchronizing signal synchronized with the output digital audio signal is output to the other device from the counter circuit which controls the memory circuit for storing the digital audio reproduction signal. However, in that device, a switching circuit for switching the reference signal of the counter circuit for controlling the memory circuit which also stores the digital audio reproduction signal to the field synchronization signal from another device is provided, so that both output digital audio signals for synchronous operation are output. The signal timing can be perfectly matched on a sample-by-sample basis.

[0053]

As described above, according to the present invention, by providing the switching circuit for switching the reference signal of the counter circuit at the time of recording and the counter circuit for outputting the reference signal to the outside at the time of reproduction, the reproduction is performed when the digital dubbing is performed. You can make a dubbing tape that is exactly the same as the master tape on the side.

Further, by switching the reference signal of the counter circuit at the time of recording and providing a counter circuit for outputting the reference signal to the outside, the same recording tape can be formed by a plurality of VTRs when performing the synchronous operation. it can.

Further, by providing a counter circuit for outputting a reference signal to the outside at the time of reproduction and a switching circuit for switching the reference signal of this counter circuit, when synchronous operation is performed, the timing of the output digital audio signals of a plurality of VTRs is provided. Can be matched exactly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a digital audio signal recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a connection diagram for digital dubbing in the first embodiment.

FIG. 3 is a timing chart in the case of digital dubbing in the first embodiment.

FIG. 4 is a connection diagram in the case of recording by synchronous operation in the second embodiment of the present invention.

FIG. 5 is a block diagram showing a circuit configuration of a recording / reproducing apparatus for a digital audio signal according to the second embodiment.

FIG. 6 is a connection diagram in the case of regeneration by synchronous operation in the second embodiment.

FIG. 7 is a diagram of a recording signal format on a conventional VTR magnetic tape.

FIG. 8 is a block diagram showing a circuit configuration of a conventional digital audio signal recording / reproducing apparatus.

FIG. 9 is a timing chart of signal processing in the conventional example.

[Explanation of symbols]

 3 switching circuit 5,10 memory circuit 6,11 counter circuit 24 counter circuit 26 switching circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G11B 20/10 F 7923-5D H04N 5/782 C 7916-5C 5/91 P 4227-5C

Claims (3)

[Claims] 1. A memory circuit for storing an input digital audio signal during recording, a counter circuit for controlling the memory circuit and outputting a reference signal to the outside, and a reference signal from the inside and a reference signal from the outside. And a switching circuit for switching and outputting as a reference signal of the counter circuit. 2. A memory circuit for storing a digital voice reproduction signal during reproduction, and a counter circuit for controlling the memory circuit and outputting a reference signal to the outside.
A digital audio signal recording / reproducing apparatus as described in. 3. A memory circuit for storing a digital audio reproduction signal during reproduction, a counter circuit for controlling the memory circuit and outputting a reference signal to the outside, a reference signal from the inside and a reference signal from the outside. 2. A digital audio signal recording / reproducing apparatus according to claim 1, further comprising a switching circuit which switches and outputs as a reference signal of the counter circuit.