JPH0982046A - Digital audio signal reproduction apparatus and digital audio signal reproduction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mute reproduction digital audio signals when a recording state of digital audio signals on a magnetic tape is changed. SOLUTION: A channel decoder and ECC circuit 6 separates AUX data in data reproduced from a magnetic tape 1 and sends the data to a microcomputer 9. The microcomputer 9 detects a changing position of each recording state of digital audio signals on the magnetic tape 1 (a recording start position, a recording end position, a recording mode change position) from the AUX data, and controls a muting operation at a DSP 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records / records digital video signals, digital audio signals, etc. on a magnetic tape.
The present invention relates to a reproducing device, and more particularly, to mute control of a digital audio signal.

[0002]

2. Description of the Related Art A digital video tape recorder for recording / reproducing a digital audio signal on a magnetic tape together with a digital video signal subjected to data compression processing is under development (for example, issued on October 1, 1993). Nikkei Electronics Books "Data compression and digital modulation" PP.137-150).

[0003]

SUMMARY OF THE INVENTION According to the present invention, in the digital video tape recorder as described above, when the recording state of the digital audio signal on the magnetic tape changes, the reproduced digital audio signal is surely muted. It is an object of the present invention to provide a digital audio signal reproducing device and a digital audio signal reproducing method.

It is another object of the present invention to provide a digital audio signal reproducing apparatus and a digital audio signal reproducing method which can freely set the mute characteristic of a reproduced digital audio signal from the outside.

[0005]

In order to solve the above-mentioned problems, a digital audio signal reproducing apparatus according to the present invention comprises:
First to reproduce digital audio signals from magnetic tape
Means, second means for reproducing auxiliary data from the magnetic tape, third means for detecting a change in the recording state of the digital audio signal from the auxiliary data reproduced by the second means, and first means. And a fourth means for muting the digital audio signal reproduced by the means under the control of the third means.

Here, the third means is constituted by a microcomputer and the fourth means is constituted by a digital signal processor, and when the microcomputer detects a change in the recording state, a predetermined data is stored in a memory in the digital signal processor. Is preferably written and the digital signal processor is configured to mute the data when it sees the data.

Also, in the digital audio signal reproducing method according to the present invention, when the magnetic tape on which the digital audio signal and the auxiliary data are recorded is reproduced, the recorded state of the digital audio signal is changed from the reproduced auxiliary data. Is detected, and when the change is detected, the digital audio signal is muted.

The digital audio signal reproducing apparatus and the digital audio signal reproducing method according to the present invention mean at least an apparatus and a method for reproducing a digital audio signal. That is, for example, an apparatus and method for reproducing a digital video signal together with a digital audio signal.
It also includes an apparatus and method for recording / reproducing a digital audio signal or a digital video signal together with a digital audio signal.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a magnetic reproducing apparatus to which the present invention is applied. This magnetic reproducing apparatus includes magnetic heads H0 and H1 for reproducing digital data recorded on a magnetic tape 1,
A switch SW that alternately switches the outputs of the magnetic heads H0 and H1 to form a time series, and an RF reproduction amplifier 2 that amplifies the output of the switch SW are provided. Magnetic heads H0, H
Reference numerals 1 are provided on the outer circumference of a rotary drum (not shown) at positions opposite to each other by 180 degrees and have different azimuth angles. Then, the digital data on the magnetic tape 1 is alternately reproduced by the magnetic heads H0 and H1.

The magnetic reproducing apparatus of FIG. 1 further includes an equalizer 3 for performing waveform equalization (equalizing) and level adjustment for the output of the RF reproducing amplifier 2, and a PLL circuit 4 for generating a clock signal CLK from the output of the equalizer 3. When,
Equalizer 3 at the timing of this clock signal CLK
A / D converter 5 for digitizing the output of A, the channel decoder and ECC circuit 6 for performing demodulation and error correction processing of the data output from the A / D conversion circuit 5, and the channel decoder and ECC circuit 6 are separated. A deinterleave / interpolation circuit 7 for performing deinterleave / interpolation processing on the demultiplexed audio data, a digital signal processor (hereinafter referred to as DSP) 8 for muting the output audio data of the deinterleave / interpolation circuit 7, and a channel Based on auxiliary data (hereinafter referred to as AUX data) sent from the decoder and the ECC circuit 6, various recording state change positions (recording start position, recording end position, etc.) of the digital audio signal on the magnetic tape 1.
A microcomputer 9 (hereinafter referred to as a microcomputer) that detects a recording mode change position) and controls a mute operation in the DSP 8 is provided.

Since the present invention relates to the processing of reproduced audio data, the channel decoder and EC
From the C circuit 6 onward, only circuits related to audio data processing are shown.

Next, the operation of the magnetic reproducing apparatus shown in FIG. 1 will be described. The RF signal alternately reproduced from the magnetic tape 1 by the magnetic heads H0 and H1 passes through the head changeover switch SW, and after being amplified by the RF reproduction amplifier 2,
It is input to the equalizer 3. The equalizer 3 equalizes these RF signals so that they can be processed in the next stage, and also applies AGC to make the levels constant.

The output of the equalizer 3 is the PLL circuit 4 and A
It is sent to the / D conversion circuit 5. The A / D conversion circuit 5 digitizes the output of the equalizer 4 and sends it to the channel decoder and ECC circuit 6. This digitization is performed by the PLL circuit 4
Is performed at the timing of the clock signal CLK generated by.

The channel decoder and ECC circuit 6 records and demodulates the input data and performs error correction processing. Then, the audio data is separated and sent to the deinterleave and interpolation circuit 7. At this time, a predetermined error code is added to the audio data that cannot be error-corrected. The channel decoder and ECC circuit 6 further separates the AUX data and supplies it to the microcomputer 9. Details of the AUX data will be described later.

The deinterleave circuit and the interpolation circuit 7 are
The interleave processing at the time of recording is restored, and the audio data in error is interpolated and sent to the DSP 8.

The audio data input to the DSP 8 is output after being muted under the control of the microcomputer 9. Next, the mute control of the microcomputer 9 will be described in detail.

The microcomputer 9 is a channel decoder and an ECC.
By looking at the AUX data received from the circuit 6, the change position of various recording states on the magnetic tape is detected. AUX data is added to video data, audio data, etc. recorded on the magnetic tape 1. For example, the video auxiliary data (hereinafter referred to as VAUX data) added to the video data includes the television signal system, recording date and time,
There are channels, recording start frames, recording end frames, and the like. Similarly, the audio auxiliary data (hereinafter referred to as AAUX data) added to the audio data includes
There are audio modes (2 channels, 4 channels, sampling frequency, etc.), recording date and time, recording start frame, recording end frame, and the like. The formats of these AUX data are described in, for example, P. 142, and will not be described here.

In the present embodiment, the microcomputer 9 is the AAUX
When a recording start frame is detected from the data, a recording end frame is detected, and a change in the audio mode is detected, a predetermined value is written in the mute flag memory 13 in the DSP 8. The DSP 8 reads the contents of the mute flag memory 13, and depending on the contents, the mute processing unit 1
Control 2 The audio data input to the DSP 8 is delayed by the delay processing unit 11 before the mute process. The reason is that the microcomputer 9 detects the change position of the recording state on the magnetic tape 1 and the delay time until the mute process is activated by the DSP 8 is dealt with. This delay processing is performed using the DRAM in the DSP 8.

FIG. 2 shows a flowchart of the mute process. FIG. 3 is a timing chart of the mute process. The microcomputer 9 and D will be described below with reference to FIGS. 2 and 3.
The operation of SP8 will be described.

First, the microcomputer 9 looks at the AAUX data sent from the channel decoder 6 and detects the mute factor. That is, as described above, it is detected whether there is a recording start frame, a recording end frame, or a change in the audio mode. Then, when this is detected, the mute flag memory 13 in the DSP 8 is rewritten.
This rewriting is, for example, as shown in FIG. 3, rewriting from 0001 to 0000 when a mute factor is detected.

When the DSP 8 reads the mute flag memory 13 and detects that it has reached 0000, it mutes in for a predetermined time and then holds the mute state (steps S1 and S2). At this time, the mute processing section 12 lowers the level of the input signal by 90B as shown in FIG.

When the DSP 8 reads out the mute lag memory 13 and detects that it has changed from 0000 to 0001, it mutes out for a predetermined time and then holds the normal state (steps S3 and S4).

The mute-in time and the mute-out time are changed according to the sampling frequency of audio data. For example, 0 ms for 32 kHz,
It is 5 ms for 44.1 kHz and 3 ms for 48 kHz. The mute time, which is the sum of the mute hold time, the mute in / out time, and the mute hold time, is determined according to the mute factor and the like. These are set by the microcomputer 9.

Step S which is the processing of the DSP 8 described above.
1 to S4 are executed for each sample of the digital audio data input to the DSP 8.

As described above, in the present embodiment, D
Since SP is used for mute, the mute characteristic can be freely set from the outside.

[0026]

As described above in detail, according to the present invention, by detecting the auxiliary data added to the audio data or the like, the change in the recording state on the magnetic tape is detected and the muting is performed. Therefore, the mute can be surely applied.

Further, since the mute processing is performed by the DSP, the mute characteristic can be freely set from the outside.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a magnetic reproducing device to which the present invention is applied.

2 is a microcomputer and DSP in the magnetic reproducing apparatus of FIG.
6 is a flowchart showing the processing of FIG.

FIG. 3 is a timing chart showing a mute operation in the DSP.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic tape, 6 ... Channel decoder and ECC circuit, 8 ... DSP, 9 ... Microcomputer, 12 ... Mute processing part, 13 ... Mute flag memory, H0, H1 ... Magnetic head

Claims (4)

[Claims] 1. A first means for reproducing a digital audio signal from a magnetic tape, a second means for reproducing auxiliary data from the magnetic tape, and the digital audio from the auxiliary data reproduced by the second means. Third to detect changes in signal recording status
And a fourth means for muting the digital audio signal reproduced by the first means under the control of the third means. 2. The digital audio signal reproducing apparatus according to claim 1, wherein the fourth means is a digital signal processor. 3. A third means is constituted by a microcomputer, and when a change in recording state is detected,
3. The digital audio signal reproducing apparatus according to claim 2, wherein predetermined data is written in a memory in the digital signal processor, and the digital signal processor performs mute by watching the data. 4. When reproducing a magnetic tape on which a digital audio signal and auxiliary data are recorded, a change in the recording state of the digital audio signal is detected from the reproduced auxiliary data, and when the change is detected. A method for reproducing a digital audio signal, characterized in that the digital audio signal is muted.