JP2001036999A - Voice signal processor and voice signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output a proper voice signal by preventing the generation of any shock noise or the head cutting of a voice accompanied by the switching of a surround mode. SOLUTION: A signal inputting circuit 10 successively transmits a digital signal inputted to a voice signal processor 1 to a memory circuit 11 so that the digital signals can be successively recorded, and the signal inputting circuit 10 also transmits the digital signal to a microcomputer 16. A mode designation processing part 20 of the microcomputer 16 judges the kind of the digital signal received from the signal inputting circuit 10, and specifies a surround mode for allowing a surround processing circuit 12 to reproduce a digital voice signal. The surround processing circuit 12 successively reads the digital signals from the memory circuit 11, and reproduces the digital voice signal in the surround mode specified by the mode designation processing part 20. When the mode designation processing part 20 detects that the kind of the digital signal is changed, a mute control part 21 allows a mute circuit 14 to mute it in a prescribed timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal processing apparatus and method for automatically setting a surround mode according to the type of digital signal, and more particularly to an audio signal processing apparatus and an audio signal processing apparatus capable of outputting an appropriate audio signal. About the method.

[0002]

2. Description of the Related Art In recent years, various techniques for compressing digitized audio and video information have been studied and proposed. For example, as a compression technique for audio information, DTS (Digital Th
eaterSystem), AC-3 (Audio Code Number 3; aka Dolby Digital), AAC (MPEG3 AAC), and the like are known.

With the development of various digital audio and video information compression techniques, DVD (Division)
A surround mode is switched according to the type of digital signal output from a digital signal reproducing device such as a gital video disc (Player) player.

FIG. 3 is a diagram showing a configuration of a conventional audio signal processing device 100 for switching a surround mode according to the type of digital signal. A conventional audio signal processing device 100 having a configuration as shown in FIG. 1 sends a digital signal fetched from the outside by a signal input circuit 110 to a surround processing circuit 111 and a microcomputer 115.
The type of digital signal received from 10 is specified, and a surround mode when the surround processing circuit 111 reproduces a digital audio signal is defined according to the type of the specified signal.

At this time, the microcomputer 115
When detecting that the type of signal has changed, the surround mode of the surround processing circuit 111 is switched, and
By controlling the mute circuit 113, the D / A conversion circuit 112
Mutes the analog audio signal output by.
As described above, by muting the output signal when the surround mode is switched, generation of noise (shock noise) accompanying the switch of the surround mode is suppressed. When the surround mode of the surround processing circuit 111 is switched, the microcomputer 115 causes the mute circuit 113 to release the mute and amplify the reproduced signal by the amplifier circuit 114 to output the amplified signal.

For example, Japanese Patent Application Laid-Open No. Hei 5-236388 discloses a technique for muting the PCM audio signal and the MUSE audio signal to prevent noise noise from being generated. I have.

[0007]

In the above-described conventional audio signal processing apparatus, in order to suppress the generation of noise (shock noise) due to the switching of the surround mode, if the mute is applied when the surround mode is switched, the initial sound signal And the audio signal immediately after the switching of the surround mode is not output, and a so-called audio break occurs.

Further, if there is a difference between the timing at which the output of the audio signal is started after switching the surround mode and the timing at which the mute is released, an inappropriate audio signal may be output. That is, if the timing of canceling the mute is earlier than the output start timing of the audio signal after switching the surround mode, noise (shock noise) accompanying the switching of the surround mode is output as an audio signal, which makes the listener uncomfortable. Had been given.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and it is possible to prevent an occurrence of a shock noise and a break in a sound due to switching of a surround mode, and to output an appropriate sound signal. It is an object to provide a processing device and method.

[0010]

To achieve the above object, an audio signal processing apparatus according to a first aspect of the present invention comprises:
Memory means for sequentially recording digital signals for reproducing an audio signal; identifying means for judging a type of the digital signal recorded in the memory means and identifying a surround mode for defining an audio signal reproduction method; Sequentially reading digital signals recorded in the memory means,
A signal reproducing means for reproducing an audio signal in the surround mode specified by the specifying means; and a mute for muting an audio signal output of the signal reproducing means at a predetermined timing when the surround mode specified by the specifying means changes. Means.

According to the present invention, a digital signal for reproducing an audio signal is sequentially recorded in the memory means, and when the surround mode specified by the specifying means changes,
It is possible to mute the audio signal output of the signal reproducing means at a predetermined timing. This makes it easy to adjust the output timing of the audio signal and the timing of muting, prevent the occurrence of shock noise and the interruption of the audio due to the switching of the surround mode, and output an appropriate audio signal.

It is preferable that the signal reproducing means suspends reading of the digital signal recorded in the memory means when switching the surround mode. As a result, the digital signal immediately after the switching of the surround mode is stored in the memory means, and the signal reproducing means can read out the signal after switching the surround mode and reproduce the audio signal. It can output a simple audio signal.

More specifically, the mute means includes an audio signal reproduced from the digital signal read from the memory means before the signal reproduction means temporarily stops reading the digital signal recorded in the memory means. It is desirable to mute the audio signal output of the signal reproducing means at the timing when the output of the signal reproduction ends.

Further, when the switching of the surround mode is completed, the signal reproducing means resumes reading of the digital signal recorded in the memory means to reproduce an audio signal, and the mute means reproduces the audio signal. When the switching of the surround mode is completed, the mute of the audio signal output of the signal reproducing unit may be released at a timing when the signal reproducing unit starts outputting the audio signal reproduced from the digital signal read from the memory unit. desirable.

Further, in the audio signal processing method according to the second aspect of the present invention, digital signals for reproducing the audio signals are sequentially recorded in a memory, and the type of the digital signal recorded in the memory is determined. When the surround mode for reproducing the audio signal is specified, the digital signal recorded in the memory is read out, the audio signal is reproduced in the specified surround mode, and the audio signal is changed at a predetermined timing when the surround mode is changed. Mute the output.

According to the present invention, the digital signal for reproducing the audio signal is sequentially recorded in the memory, and the audio signal output can be muted at a predetermined timing when the surround mode is changed. This makes it easy to adjust the output timing of the audio signal and the timing of muting, prevent the occurrence of shock noise and the interruption of the audio due to the switching of the surround mode, and output an appropriate audio signal.

When the surround mode is changed, it is desirable to temporarily stop reading of the digital signal recorded in the memory and store the digital signal in the memory in order to prevent the sound from being cut off.

Further, it is preferable to mute the audio signal output at the timing when the output of the audio signal reproduced from the digital signal read from the memory ends before the reading of the digital signal recorded in the memory is temporarily stopped. .

Further, when the change of the surround mode is completed, the reading of the digital signal stored in the memory is resumed to reproduce the audio signal, and the audio signal output is muted at the timing when the output of the audio signal is started. It is desirable to cancel.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An audio signal processing device according to an embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an audio signal processing device 1 according to an embodiment of the present invention. As shown in the figure, the audio signal processing device 1 includes a signal input circuit 10,
Memory circuit 11, surround processing circuit 12, D / A
(Digital / Analog) conversion circuit 13 and mute circuit 14
, An amplification circuit 15 and a microcomputer 16.

The signal input circuit 10 is, for example, a DVD (Digi
This is a circuit for inputting a digital signal from an external digital signal generation device such as a tal Video Disc player to the audio signal processing device 1. The signal input circuit 10 converts the input digital signal into a memory circuit 11
Is sent to the microcomputer 16.

The memory circuit 11 is composed of a semiconductor memory or the like, and is for temporarily recording a digital signal received from the signal input circuit 10 and adjusting output timing.

The surround processing circuit 12 is composed of an audio signal decoder and the like, and executes signal processing such as decoding of digital signals read from the memory circuit 11 and surround processing in a surround mode under the control of the microcomputer 16. This is for reproducing a digital audio signal. For example, the surround processing circuit 12
The digital signal encoded by the CM (Pulse Code Modulation) is processed by a pro-logic method, or the digital signal of the Dolby digital method is processed to reproduce a multi-channel digital audio signal. The surround processing circuit 12 sends the reproduced digital audio signal to the D / A conversion circuit 13.

The D / A conversion circuit 13 is for converting a digital audio signal received from the surround processing circuit 12 into an analog audio signal.

The mute circuit 14 is controlled by the microcomputer 16 to mute the analog audio signal output from the D / A conversion circuit 13.

The amplification circuit 15 is for amplifying the analog audio signal received from the D / A conversion circuit 13 via the mute circuit 14 and outputting the amplified audio signal as an audio signal. The sound is supplied to form a sound field corresponding to a predetermined surround mode.

The microcomputer 16 controls the entire operation of the audio signal processing device 1.
As a logical configuration, a mode designation processing unit 20, a mute control unit 21, and a signal reading control unit 22 are provided.

The mode designation processing section 20 includes the signal input circuit 1
The type of digital signal received from 0 is specified, and the surround processing circuit 12 executes signal processing such as digital signal decoding and surround processing in a surround mode corresponding to the specified type of signal. Further, the mode designation processing unit 20 detects that the type of the digital signal has changed, and notifies the mute control unit 21 and the signal reading control unit 22 that the type of the signal has changed.

When notified by the mode designation processing section 20 that the type of signal has changed, the mute control section 21 controls the mute circuit 14 to output a predetermined signal to the analog audio signal output from the D / A conversion circuit 13. When the surround processing circuit 12 starts outputting a digital audio signal, the mute is released.

The signal reading control unit 22 includes a position where the memory circuit 11 writes the digital signal received from the signal input circuit 10, a position where the digital signal recorded by the memory circuit 11 is read by the surround processing circuit 12, and a timing of reading. Is specified.

Next, the operation of the audio signal processing device 1 having the above configuration will be described. The audio signal processing device 1 sequentially records digital signals for reproducing the audio signals,
By muting the audio signal output according to the switching of the surround mode, by making it easier to match the output timing of the audio signal with the timing of releasing the mute,
This is an apparatus that can output an appropriate audio signal while preventing the generation of shock noise and the interruption of audio at the start of the surround mode.

When the audio signal processing device 1 receives a digital signal output from a DVD player or the like, the signal input circuit 1
0 distributes the signal, sends a digital signal for audio output to the memory circuit 11, and sends a digital signal for surround mode determination to the mode designation processing unit 20.

The mode designation processing section 20 includes the signal input circuit 1
The surround mode is specified by the digital signal received from 0, the operation of the surround processing circuit 12 is controlled according to the specified surround mode, and signal processing such as decoding and surround processing is executed. At this time, the mute control unit 21 controls the mute circuit 14 until the surround processing circuit 12 starts outputting the digital signal subjected to the signal processing.
To prevent the audio signal from being input from the D / A conversion circuit 13 to the amplification circuit 15. This prevents noise (shock noise) generated when the surround processing circuit 12 switches the surround mode.

The signal reading control section 22 defines the position where the memory circuit 11 writes the digital signal from the signal input circuit 10, the recording position of the digital signal read by the surround processing circuit 12 in the memory circuit 11, and the read timing. Is specified. Memory circuit 11
Records the digital signal received from the signal input circuit 10 under the control of the signal reading control unit 22.

The surround processing circuit 12 reads out the digital signal recorded in the memory circuit 11 by FIFO (First in First Out) under the control of the signal reading control section 22, and performs a surround mode operation under the control of the mode designation processing section 20. The digital audio signal is reproduced by executing signal processing such as decoding and surround processing. The surround processing circuit 12 sends the reproduced digital audio signal to the D / A conversion circuit 13.

The D / A conversion circuit 13 converts the digital audio signal received from the surround processing circuit 12 into an analog signal,
The signal is sent to the amplifier circuit 15 via the mute circuit 14. The amplification circuit 15 amplifies the analog audio signal received from the D / A conversion circuit 13 and outputs the signal to an external device such as a speaker.

When the type of digital signal input to the signal input circuit 10 changes, the mode designation processing unit 20 detects that the type of digital signal has changed, and communicates with the mute control unit 21 to read the signal. Notify the control unit 22.

When the signal reading control unit 22 is notified from the mode designation processing unit 20 that the type of signal has changed, the signal reading control unit 22 controls the surround processing circuit 12 to record the signal in the memory circuit 11 before the surround mode changes. When the reading of the read digital signal is completed, the reading of the digital signal is temporarily stopped. At this time, a digital signal is continuously input to the signal input circuit 10. This digital signal is sequentially recorded in the memory circuit 11 and stored until the surround processing circuit 12 finishes changing the surround mode. Will be done.

On the other hand, when the mute control unit 21 is notified from the mode designation processing unit 20 that the type of signal has changed, the mute control unit 21 operates in the surround mode before the change.
Until the output of the audio signal reproduced by 2 ends, the operation of the mute circuit 14 is stopped and the mute is released. When the surround processing circuit 12 temporarily stops outputting the audio signal to switch the surround mode, the mute control unit 21 activates the mute circuit 14 to mute the signal output from the D / A conversion circuit 13. Multiply.

When the output of the digital audio signal before the change of the surround mode ends, the mode designation processing section 20 causes the surround processing circuit 12 to switch the surround mode.

When the surround processing circuit 12 switches the surround mode, the signal reading control section 22 causes the surround processing circuit 12 to restart reading the digital signal from the memory circuit 11. The surround processing circuit 12 reads the digital signal after the change of the surround mode from the memory circuit 11, performs signal processing, and sends the reproduced digital audio signal to the D / A conversion circuit 13. At this time, the signal reading control unit 22 specifies the reading position of the digital signal read from the memory circuit 11 by the surround processing circuit 12 and reads the digital signal after the surround mode has been changed from the beginning. 12 is controlled.

The mute control unit 21 includes a mute circuit 14
And the mute is released at the timing when the audio signal after the change of the surround mode is output from the D / A conversion circuit 13. This makes it easy to match the output timing of the audio signal with the timing of switching on / off of the mute, so that an appropriate audio signal can be output. That is, noise (shock noise) generated when the surround processing circuit 12 switches the surround mode is not output as an audio signal.
In addition, it is possible to prevent a so-called audio cutoff caused by muting the audio signal immediately after the surround mode is switched.

Next, as a specific example, as shown in FIG. 2 (a), the digital input signal inputted to the signal input circuit 10 is changed from the PCM at the timing _{T A} Dolby digital, at a timing _{T D} The operation of the audio signal processing device 1 in the case where Dolby Digital changes to PCM will be described.

[0045] In this case, the surround processing circuit 12, as shown in FIG. 2 (d), in the previous time _{T A,}
It is assumed that the surround mode is set to the prologic mode, and a digital audio signal is reproduced by executing signal processing such as decoding of a digital signal encoded by PCM and surround processing.

[0046] At timing T _A, the digital input signal changes to Dolby Digital from PCM, mode designation processing unit 20 detects this, the mute control unit 21
To the signal reading control unit 22.

The signal reading control unit 22 to the timing T _B which surround processing circuit 12 shown in FIG. 2 (e) has finished surround processing of the PCM, the digital signal recorded in the memory circuit 11 in a surround processing circuit 12 The reading is performed and the reproduction of the digital audio signal is continued. On this occasion,
Digital input signal of Dolby digital input from the timing T _A to the signal input circuit 10 is started,
The data is sequentially written and stored in the memory circuit 11.

[0048] surround processing circuit at the timing _{T B} 1
2 finishes the PCM surround processing, the signal reading control unit 22 causes the surround processing circuit 12 to
The reading of the digital signal from is temporarily stopped. At this time, as shown in FIG.
Activates the mute circuit 14 to mute the audio signal input to the amplifier circuit 15.

Thereafter, the mode designation processing unit 20
(B), the send signals S ₁ indicating to switch the surround mode of surround processing circuit 12 from the PCM mode to the Dolby digital mode, surround processing circuit 12 switches the surround mode.

After the surround processing circuit 12 switches the surround mode, the signal reading control section 22 causes the surround processing circuit 12 to read out the digital signal recorded in the memory circuit 11 and restart reproduction of the digital audio signal.

[0051] As shown in FIG. 2 (e), a surround processing circuit 12 at the timing T _C, starts to output the digital audio signal reproduced by the Dolby digital mode. At this time, the mute control unit 21
Is stopped, and the mute applied to the analog audio signal output from the D / A conversion circuit 13 is released.

The surround processing circuit 12 operates at the timing T
_The digital audio signal is reproduced by performing a surround process or the like on the Dolby Digital digital signal stored in the memory circuit 11 from _A , and the D / A conversion circuit 1
Send to 3.

[0053] Thereafter, as shown in FIG. 2 (a), at the timing T _D, the digital input signal changes from Dolby Digital to PCM, the mode designation processing unit 20 detects this, the mute control unit 21 And signal reading control unit 2
Notify 2.

[0054] The signal reading control section 22, the surround processing circuit 12 to the timing T _E to end the surround processing of Dolby digital, digital signal surround processing circuit 12 which is recorded in the memory circuit 11 shown in FIG. 2 (e) And the reproduction of the digital audio signal is continued. At this time, the digital input signal of the PCM is sequentially input from the signal input circuit 10 to the audio signal processing device 1 and stored in the memory circuit 11.

[0055] surround processing circuit at the timing _{T E} 1
When 2 finishes the surround processing of the Dolby Digital digital signal, the signal reading control unit 22 causes the surround processing circuit 12 to temporarily stop reading the digital signal from the memory circuit 11. At this time, as shown in FIG. 2C, the mute control unit 21 activates the mute circuit 14 to mute the analog audio signal input from the D / A conversion circuit 13 to the amplification circuit 15.

Thereafter, the mode designation processing unit 20
(B), the send signal S ₂ indicating that switching the surround mode of surround processing circuit 12 from the Dolby digital mode to the PCM mode, the surround processing circuit 12 switches the surround mode.

After the surround processing circuit 12 switches the surround mode, the signal reading control section 22 causes the surround processing circuit 12 to read the digital signal recorded in the memory circuit 11 and restart the execution of the surround processing.

As shown in FIG. 2E, at timing _TF , the surround processing circuit 12 starts outputting a sound signal subjected to surround processing in the PCM mode. At this time, the mute control unit 21 stops the operation of the mute circuit 14 and cancels the mute applied to the output signal of the D / A conversion circuit 13.

The surround processing circuit 12 operates at the timing T
_D performs surround processing of Dolby Digital digital signals stored in the memory circuit 11 and sequentially sends the signals to the D / A conversion circuit 13.

The D / A conversion circuit 13 converts the digital audio signal received from the surround processing circuit 12 into an analog signal and sends it to the amplifier circuit 15 via the mute circuit 14.

The amplification circuit 15 amplifies the audio signal received from the D / A conversion circuit 13 and outputs the signal to an external device such as a speaker.

As described above, according to the audio signal processing device 1, digital signals input to the signal input circuit 10 are sequentially recorded in the memory circuit 11, and at the timing specified by the signal reading control unit 22. The data is read by the surround processing circuit 12. Therefore, the output timing of the audio signal can be adjusted. Thus, when the type of digital signal changes, the surround processing circuit 12
Stops the output of the audio signal at the timing when the surround mode is changed, so that the mute circuit 14 can mute the audio signal immediately after the surround mode is switched. Cutting can be prevented. In addition, since the timing for switching the surround mode and the timing for muting can be easily adjusted, generation of noise (shock noise) due to the change in the surround mode can be effectively suppressed.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, in the above-described embodiment, the description has been made assuming that an audio signal is reproduced from a digital signal. However, the present invention is not limited to this. That is, for example, when reproducing an audio signal and a video signal from a digital signal, the digital signal is recorded in a memory and the timing of outputting the video signal according to the switching of the surround mode is adjusted, so that the audio signal and the video signal are adjusted. Can be synchronized and output.

[0064]

As described above, according to the present invention, a digital signal for reproducing an audio signal is sequentially recorded,
An appropriate audio signal can be output by easily adjusting the timing of switching the surround mode and the timing of mute.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an audio signal processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a timing chart for explaining the operation of the audio signal processing device.

FIG. 3 is a diagram showing a configuration of a conventional audio signal processing device.

[Explanation of symbols]

 1,100 Audio signal processing device 10,110 Signal input circuit 11 Memory circuit 12,111 Surround processing circuit 13,112 D / A conversion circuit 14,113 Mute circuit 15,114 Amplification circuit 16,115 Microcomputer

Claims (8)

[Claims] A memory means for sequentially recording digital signals for reproducing an audio signal, a type of a digital signal recorded in the memory means is identified, and a surround mode for defining a reproduction method of the audio signal is specified. Specifying means; signal reproducing means for sequentially reading digital signals recorded in the memory means and reproducing the audio signal in the surround mode specified by the specifying means; and changing the surround mode specified by the specifying means Then, there is provided a mute means for muting the audio signal output of the signal reproduction means at a predetermined timing. 2. The audio signal processing apparatus according to claim 1, wherein said signal reproducing means temporarily stops reading digital signals recorded in said memory means when switching between surround modes. 3. The output of the audio signal reproduced from the digital signal read from the memory means before the signal reproducing means temporarily stops reading of the digital signal recorded in the memory means is terminated. The audio signal processing device according to claim 1, wherein a mute is applied to an audio signal output of the signal reproducing unit at a timing of performing the operation. 4. When the switching of the surround mode is completed, the signal reproducing means resumes reading of the digital signal recorded in the memory means, reproduces an audio signal, and the mute means reproduces the signal. When the means completes the switching of the surround mode, the signal reproducing means cancels the mute of the audio signal output of the signal reproducing means at a timing at which the output of the audio signal reproduced from the digital signal read from the memory means is started. The audio signal processing device according to claim 3, wherein: 5. A digital signal for reproducing an audio signal is sequentially recorded in a memory, a type of the digital signal recorded in the memory is determined, and a surround mode for reproducing the audio signal is specified. Reading a digital signal recorded in the surround mode, reproducing an audio signal in the specified surround mode, and muting the audio signal output at a predetermined timing when changing the surround mode. . 6. The digital camera according to claim 5, wherein when changing the surround mode, reading of the digital signal recorded in the memory is temporarily stopped, and the digital signal is stored in the memory. Audio signal processing method. 7. A mute is applied to the audio signal output at the timing when the output of the audio signal reproduced from the digital signal read from the memory is completed before the reading of the digital signal recorded in the memory is temporarily stopped. The audio signal processing method according to claim 6, wherein: 8. When the change of the surround mode is completed, reading of the digital signal recorded in the memory is resumed to reproduce the audio signal, and the output of the audio signal is muted at the timing when the output of the audio signal is started. The audio signal processing method according to claim 7, wherein the audio signal processing is canceled.