JPH05290510A - Digital audio recording device - Google Patents

Abstract

PURPOSE:To record audio signals regardless of the sampling frequency of digital audio signals. CONSTITUTION:Digital audio signals inputted from an optical input terminal 1 or a coaxial input terminal 2 are inputted to a discriminant circuit/decoder 10 through an input changeover switch 5. The sampling frequency of the digital audio signals is discriminated by the discriminant circuit/decoder 10. If the sampling frequency is judged to be different from 32kHz and 48kHz by a microcomputer 8, the connection of a selection switch 7 is switched over to a contact 7b. On the other hand, analog audio signals inputted from an L ch input terminal 3 and an R ch input terminal 4 are digitized by an AD converter 13 and inputted to a DSP 19 through the switch 7. The digital audio signals are transformed to recording signals by a recording section 9 and are recorded in a magnetic tape 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital voice recording device for recording voice in digital form.

[0002]

2. Description of the Related Art In recent years, digital audio processing technology has been improved, and its recording has become easy. Along with this, the development of digital recording devices for home use has been promoted and is being popularized to the general public. Hereinafter, a system including a reproducing device as a digital sound source and a recording device will be described.

As shown in FIG. 3, this system includes a satellite broadcasting tuner (hereinafter referred to as a BS tuner) 21 as a reproducing device and a laser disc player (hereinafter referred to as an LD).
22), a digital audio tape recorder (hereinafter referred to as DAT) 23, and a compact disc player (hereinafter referred to as CD player) 2
4 and a video tape recorder (hereinafter referred to as VTR) 25 as a recording device.

The system also includes an amplifier 26 having an AV selector function as an amplifier for connecting the above-mentioned devices.
Is equipped with. The amplifier 26 has a monitor output terminal M.
_OUT and speaker output terminals SP _L and SP _R are provided, and a television 28 as an output device and a pair of speakers 28 and 29 are connected to these terminals. Amplifier 26
Has an input selection switch (not shown) for selecting the input system of the audio signal and the video signal.

The video signal of the BS tuner 21 is the amplifier 2
_No. 6 BS video input terminal V _IN1 . The analog audio signal of the BS tuner 21 is input to the BS analog audio input terminal AA _IN1 of the amplifier 26. The digital audio signal of the BS tuner 21 has a sampling frequency of 32 kHz in the A mode and 48 kHz in the B mode.
And is input to the BS digital audio input terminal DA _IN1 (corresponding to, for example, a coaxial cable) of the amplifier 26.

The video signal of the LD player 22 is supplied to the amplifier 2
6 is input to the LD video input terminal V _IN2 . The analog audio signal of the LD player 22 is input to the LD analog audio input terminal AA _IN2 of the amplifier 26. The digital audio signal of the LD player 22 has a sampling frequency of 44.1 kHz and is input to the LD digital audio input terminal DA _IN2 (for example, optical cable compatible) of the amplifier 26.

The analog audio signal of DAT 23 is input to the DAT analog audio input terminal AA _IN3 of the amplifier 26. DAT23 digital audio signals have sampling frequencies of 32 kHz, 44.1 kHz and 48 kHz.
The frequency is kHz and is input to the DAT digital audio input terminal DA _IN3 (corresponding to, for example, a coaxial cable) of the amplifier 26.

The analog audio signal of the CD player 24 is
CD analog audio input terminal AA _{IN4 of} amplifier 26
Entered in. The digital audio signal of the CD player 24 has a sampling frequency of 44.1 kHz, and the CD digital audio input terminal DA of the amplifier 26.
Input to _IN4 (for example, optical cable compatible).

The VTR 25 is of the VHS system, for example, and is capable of digital recording and reproduction of audio signals. In this VTR 25, the sampling frequencies of recordable digital audio signals are 32 kHz and 48 kHz.
Is.

The video signal and the analog audio signal selected by the amplifier 26 are the VTR video output terminal V _OUT and the analog audio output terminal A _{OUT of the} amplifier 26, respectively.
And are input to the VTR video input terminal V _IN and the analog audio input terminal A _IN . The digital audio signal selected by the amplifier 26 is output from the coaxial output terminal CX _OUT and the optical output terminal OP _OUT of the amplifier 26, and the coaxial input terminal CX _IN and the optical input terminal OP _{IN of the} VTR 25 are output from the respective terminals. Entered in.

In the system configured as described above, in order to record the digital audio signal of each reproducing device by the VTR 25, first, the amplifier 26 selects one from the reproducing devices by the input selection switch. This allows
The digital audio signal from the reproducing device can be output to the VTR 25. On the VTR 25 side, when the input of the digital audio signal is selected, the digital audio signal is received and recorded.

The VTR 25 can also digitally record an analog voice signal. in this case,
The analog audio signal selected by the amplifier 26 is VT
In R25, for example, it is converted into a digital audio signal of 48 kHz and recorded.

On the VTR 25 side, the selection of the input of the analog voice signal or the digital voice signal is made by a switch or the like.

[0014]

However, the above-mentioned VT
When the digital audio signal of 44.1 kHz from the LD player 22, DAT 23 and CD player 24 is input to the R25, the digital audio signal cannot be recorded because the data rates are different. Therefore, in this case, recording is performed in a silent state by performing a process such as muting.

Further, in the VTR 25, there is no limitation as to the digital recording of the analog voice signal as in the digital voice signal. Therefore, the analog voice signal which has the same voice as the digital voice signal of 44.1 kHz is converted into the digital voice signal. Then, it is possible to eliminate the inconvenience as described above. However, V
If the input of the digital audio signal is still selected on the TR 25 side, the digital audio signal of 44.1 kHz is input, and again, the recording is performed in the silent state as described above.

The present invention has been made in view of the above circumstances, and when a digital audio signal having a sampling frequency that cannot be recorded by a recording device is input, the input of the analog audio signal is automatically selected. Thus, it is intended to enable the recording of voice.

[0017]

In the digital voice recording apparatus of the present invention, a digital voice input terminal for inputting a digital voice signal, an analog voice input terminal for inputting an analog voice signal, and an analog voice input terminal are used. Converting an analog voice signal into a digital voice signal having a predetermined sampling frequency, for example, selecting one of an analog / digital converting means by an AD converter and a digital voice signal having a sampling frequency from the digital voice input terminal or the analog / digital converting means. In the audio recording device, the audio recording device is provided with a selecting means for recording, and a recording means for recording only the digital audio signal selected by the selecting means with a predetermined sampling frequency on a recording medium,
In order to solve the above problems, the following means are taken.

That is, in the above digital audio recording device, the sampling frequency determining means for determining whether or not the digital audio signal input from the digital audio input terminal has a predetermined sampling frequency, and the input digital audio signal are Selection control means for controlling the selection means so that the digital audio signal output from the analog / digital conversion means is selected when the sampling frequency is different from the predetermined sampling frequency.

[0019]

In the above structure, the sampling frequency determining means determines whether or not the digital audio signal input from the digital audio input terminal has a predetermined sampling frequency. At this time, if it is determined that the sampling frequency is different from the predetermined one, the selection control means controls the selection means to select the digital audio signal output from the analog / digital conversion means. As a result, the digital audio signal is recorded on the recording medium by the recording means.

That is, in this case, the digital audio signal converted from the analog audio signal is automatically recorded. Therefore, if the audio signal from the same playback device is input to the digital audio input terminal and the analog audio input terminal, the analog audio signal will be recorded instead even if the sampling frequency of the digital audio signal is different from the predetermined one. Therefore, it is possible to avoid the situation in which recording cannot be performed.

When the above configuration is applied to a VTR capable of digitally recording / reproducing an audio signal, recording is performed as follows. This VTR is equipped with a CD player, etc. 44.1
When a kHz digital audio signal is input, an analog audio signal output from the same reproducing device converted into a 48 kHz digital audio signal is selected and recorded in place of the digital audio signal.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of an embodiment in which the present invention is applied to a VTR, with reference to FIG. 1 and FIG.

The VTR according to this embodiment is a VHS type VTR.
TR, which records digitally an analog voice signal and a digital voice signal input from the outside. Digital audio signals that can be recorded in this VTR have sampling frequencies of 32 kHz and 48.
It is for kHz.

As shown in FIG. 1, this VTR is provided with an optical input terminal 1 as a digital audio input terminal and a coaxial input terminal 2, and an Lch (left channel) input terminal 3 and an Rch (as an analog audio input terminal. The right channel) input terminal 4 is provided. Further, the VTR includes an input changeover switch 5, a signal processing unit 6, a selection switch 7, a microcomputer (hereinafter referred to as a microcomputer) 8, and a recording unit 9.

The input changeover switch 5 has contacts 5a to 5c, and the contacts 5a and 5b are the optical input terminals 1 respectively.
Is connected to the coaxial input terminal 2 and a contact 5c is connected to a sampling frequency discriminating circuit / DIF decoder 10 of a signal processing unit 6 described later. This input selector switch 5
Is manually switched, and the connection between the optical input terminal 1 or the coaxial input terminal 2 and the sampling frequency discrimination circuit / DIF decoder 10 is switched.

The signal processing unit 6 includes a sampling frequency discrimination circuit / DIF decoder (hereinafter referred to as discrimination circuit / decoder) 10 and a low-pass filter (LPF in the figure) 11
12 and AD converter 13.

The discriminating circuit / decoder 10 forming a digital audio signal processing system in the signal processing unit 6 determines the sampling frequency of the digital audio signal input from the optical input terminal 1 or the coaxial input terminal 2 as described in detail below. In addition to discriminating, a digital interface format is applied to the digital audio signal.

As shown in FIG. 2, the discrimination circuit / decoder 10 as the sampling frequency discrimination means includes a DIF decoding circuit 14 and a PLL (Phase Locked Loop) circuit 15.
And have.

The DIF decoding circuit 14 decodes the input digital audio signal in a digital interface format and outputs the result as decoded data. Further, the DIF decoding circuit 14 reads the sampling frequency from the digital interface format and generates a sampling frequency ID signal (hereinafter abbreviated as ID signal). The ID signal becomes "11", "10", "01" when the sampling frequency is 48 kHz, 32 kHz, and 44.1 kHz, respectively, and becomes "00" at other sampling frequencies.

The PLL circuit 15 is the DIF decoding circuit 1
4 is a circuit for generating a clock for operating 4 on the basis of an input digital audio signal.
And a low-pass filter 17 composed of a resistor R and a capacitor C, and a voltage controlled oscillator (VCO in the figure) 18. The PLL circuit 15 includes a phase comparator 1
At 6, the output pulse of the voltage controlled oscillator 18 and the digital audio signal are phase-compared, and the difference signal obtained as a result is averaged by the low-pass filter 17 into an error signal. The pulse of is output. That is, the PLL circuit 15
Generates a clock having the same frequency as the DIF transmission of the digital audio signal.

As shown in FIG. 1, in the signal processing unit 6, the low pass filters 11 and 12 and the AD converter 13 are provided.
Is an analog audio signal processing system. The low-pass filters 11 and 12 have a cut-off frequency of 22 kHz and remove high-frequency components from the analog audio signals input from the input terminals 3 and 4. analog/
The AD converter 13 as digital converting means converts the analog audio signal that has passed through the low-pass filters 11 and 12 into a digital audio signal having a sampling frequency of 48 kHz with a quantization bit number 16.

The selection switch 7 has contacts 7a to 7c. The contacts 7a and 7b are connected to the discrimination circuit / decoder 10 and the AD converter 13, respectively, and the contact 7c.
Are connected to a digital signal processor (hereinafter referred to as DSP) 19 of the recording unit 9 described later. The selection switch 7 is switched under the control of the microcomputer 8, and is used for the discrimination circuit / decoder 10 or AD.
The connection between the converter 13 and the DSP 19 is switched, and it has a function as selection means.

The microcomputer 8 controls each part of the VTR, and also switches the selection switch 7 in accordance with the sampling frequency of the digital audio signal discriminated by the discriminating circuit / decoder 10. That is, as shown in Table 1, the microcomputer 8 determines that the ID signal generated by the discrimination circuit / decoder 10 is "11" or "10".
When the ID signal is "01" or "00", the selection switch 7 is connected to the contact 7a side while the selection switch 7 is connected to the contact 7a side. The microcomputer 8 has a function as a selection control means by performing such switching control of the selection switch 7.

[0034]

[Table 1]

The recording unit 9 includes a DSP 19 and a memory 20.
2, a QPSK (Quadrature Phase Shift Keying) modulator 21, a recording amplifier 22, and a recording head 23.

The DSP 19 is a circuit that generates an error correction signal, adds the error correction signal to the digital voice signal that has passed through the selection switch 7, and performs processing such as interleaving on the digital voice signal. Memory 20
Is a storage device used as a working area when the DSP 19 performs the above processing.

The QPSK modulator 21 performs modulation according to the four-phase phase shift keying method to obtain the DSP 19
It is a modulator for converting the signal passed through to a recording signal. The recording amplifier 22 is an amplifier that amplifies the recording signal modulated by the QPSK modulator 21 to a level suitable for recording. The recording head 23 is attached to a rotary drum (not shown), and records the recording signal from the recording amplifier 22 on a magnetic tape 24 as a recording medium.

The operation of recording with the above configuration will be described.

For example, the digital audio signal output from the CD player is the optical input terminal 1 or the coaxial input terminal 2.
When input from any of the above, it is input to the discrimination circuit / decoder 10 via the input changeover switch 5. The discrimination circuit / decoder 10 discriminates the sampling frequency of the above digital audio signal, and outputs the result as an ID signal. In this case, the sampling frequency is 44.1.
Since the frequency is kHz, the ID signal becomes "01". Then, the sampling frequency is 32 kHz by the microcomputer 8.
When it is determined that z and 48 kHz are different, the connection of the selection switch 7 is switched to the contact 7b.

On the other hand, the analog audio signal output from the CD player is digitized by the AD converter 13 when input from the Lch input terminal 3 and the Rch input terminal 4. The digital audio signal output from the AD converter 13 is input to the DSP 19 via the selection switch 7 switched as described above. This digital audio signal is subjected to predetermined processing by the DSP 19 and Q
After being modulated by the PSK modulator 21 and converted into a recording signal, it is recorded on the magnetic tape 24 by the recording head 23 via the recording amplifier 22.

As described above, in the VTR of this embodiment, the sampling frequency of the input digital audio signal is 32.
If it is different from kHz and 48 kHz, the digital audio signal converted from the analog audio signal is recorded instead of the digital audio signal.
If an analog audio signal is input from the ch input terminal 3 and the Rch input terminal 4, recording will not be performed in a silent state.

In the present embodiment, an example in which the present invention is applied to a VTR has been described, but the present invention is not limited to this, and
Any recording device capable of selectively digitally recording the analog audio signal and the digital audio signal can be applied.

[0043]

As described above, the digital voice recording apparatus of the present invention has the sampling frequency discriminating means for discriminating whether or not the digital voice signal inputted from the digital voice input terminal has the predetermined sampling frequency, and the input. When the generated digital audio signal has a different sampling frequency, the selection control means for controlling the selection means is selected so that the digital audio signal output from the analog / digital conversion means is selected.

Thus, when the sampling frequency of the digital audio signal to be recorded is different from the predetermined frequency, the analog audio signal input from the analog audio input terminal is automatically digitally recorded. Therefore, even in the above case, it is possible to avoid the situation where the voice is not recorded. Further, in the above case, the operator does not have to bother to switch the input between the analog audio signal and the digital audio signal.

Therefore, if the digital audio recording apparatus of the present invention is adopted, it is possible to record audio regardless of the sampling frequency of the digital audio signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a VTR voice digital recording system according to an embodiment of the present invention.

2 is a block diagram showing a configuration of a sampling frequency discrimination circuit / DIF decoder in the digital recording system of FIG.

FIG. 3 is a block diagram showing a configuration of a system including a reproducing device when recording is performed by a conventional VTR.

[Explanation of symbols]

1 Optical input terminal (digital audio input terminal) 2 Coaxial input terminal (digital audio input terminal) 3 Lch input terminal (analog audio input terminal) 4 Rch input terminal (analog audio input terminal) 7 Selection switch (selection means) 8 Microcomputer (Selection control means) 9 Recording unit (recording means) 10 Sampling frequency discrimination means / DIF decoder (sampling frequency discrimination means) 13 AD converter (analog / digital conversion means)

Claims (1)

[Claims] 1. A digital audio input terminal for inputting a digital audio signal, an analog audio input terminal for inputting an analog audio signal, and an analog audio signal input from the analog audio input terminal into a digital audio signal of a predetermined sampling frequency. An analog / digital converting means for converting, a selecting means for selecting one of a digital audio signal having a sampling frequency from the digital audio input terminal or the analog / digital converting means, and a predetermined sampling of the digital audio signal selected by the selecting means. In a voice recording device provided with a recording means for recording only those having a frequency on a recording medium, a sampling frequency determining means for determining whether or not a digital audio signal input from a digital audio input terminal has a predetermined sampling frequency, The input data When the digital audio signal differs from the predetermined sampling frequency,
An audio recording apparatus comprising: a selection control means for controlling the selection means so that the digital audio signal output from the analog / digital conversion means is selected.