JP2003259246A - Audio reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio reproducing device for automatically switching internal signal paths on the basis of identification results by identifying the type of an inputted digital audio signal. <P>SOLUTION: A DIR 3 extracts additional information from a digital audio signal inputted from a digital inputting part 1. A host microcomputer 12 identifies the type of the digital audio signal from the extracted additional information, switches an A/D switching selector 4 and an analog direct/DSP (digital signal processor) processing switching selector 7 so as to reproduce an analog audio signal inputted from an analog inputting part 9 when the inputted digital audio signal is a PCM (pulse code modulation) silent signal and a state in which the PCM silent signal is inputted continues as much as a predetermined period of time. The host computer 12 switches the A/D switching selector 4 and the analog direct/DSP processing switching selector 7 so as to reproduce the inputted digital audio signal in the other cases. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for selecting an internal signal path in an audio reproducing apparatus, for example, an analog audio signal and a digital signal from one external AV device (particularly a TV with a built-in BS digital tuner). A connected so that the audio signal is input to its own analog input terminal and digital input terminal
This is a technique suitable for selecting whether to reproduce an analog audio signal or a digital audio signal from the external AV device in the V control amplifier.

[0002]

2. Description of the Related Art Currently, TV broadcasting includes terrestrial broadcasting and BS.
There are analog broadcasting and BS digital broadcasting.

In the BS digital broadcasting, the video signal used in the analog method in the BS analog broadcasting becomes the MPEG2 method which is a digital compression method, and the audio signal is in the digital P used in the BS analog method.
MPEG2 ACC (MPEG2 Advan) which is a digital audio compression method from a CM (Pulse Code Modulation) signal
ced Audio Coding) signal. MPEG2 A
Since CC can compress and transmit multi-channel audio, unlike CC channel 2-channel reproduction of BS analog broadcasting, CC enables more realistic audio reproduction in movies and the like.

Since the BS analog broadcasting is scheduled to end due to the start of the BS digital broadcasting, the case where terrestrial broadcasting and BS digital broadcasting are handled as TV broadcasting will be described here.

In order to receive terrestrial broadcasts and BS digital broadcasts and reproduce video signals and audio signals, a TV with a built-in BS digital tuner, which has a BS digital tuner in addition to a tuner for receiving terrestrial broadcasts, is used.

In a TV with a built-in BS digital tuner,
When receiving terrestrial broadcasting, the broadcast wave is received by the terrestrial broadcasting receiving tuner and demodulated, and the obtained video signal is BS.
It is displayed on the screen of the TV with a built-in digital tuner. The audio signal is reproduced from the speaker built in the TV with the built-in BS digital tuner, or the analog output terminal of the TV with the built-in BS digital tuner is connected to the analog input terminal of the AV control amplifier and the speaker connected to the AV control amplifier. Play from.

When receiving a BS digital broadcast on a TV with a built-in BS digital tuner, the BS digital tuner receives and demodulates the BS digital broadcast wave, and the resulting video signal is displayed on the screen of the TV with a built-in BS digital tuner. To be done. The audio signal is reproduced from a 2-channel speaker built in the TV with a built-in BS digital tuner, or the digital output terminal of the TV with a built-in BS digital tuner is connected to the digital input terminal of the AV control amplifier and then connected to the AV control amplifier. Playback from the speaker. At this time, since the audio signal output from the digital output terminal of the TV with the built-in BS digital tuner becomes the MPEG2 ACC signal, the connected AV control amplifier is an AV control amplifier capable of decoding the MPAG2 ACC signal. Yes, with AV control amplifier MPAG2
The multi-channel audio signal obtained by decoding the ACC signal is reproduced from the speaker connected to the AV control amplifier.

As described above, when an audio signal from a TV with a built-in BS digital tuner compatible with terrestrial broadcasting and BS digital broadcasting is reproduced from a speaker connected to an AV control amplifier, analog audio signals for terrestrial broadcasting and In order to input the digital audio signal (MPEG2 ACC signal) for BS digital broadcasting, the analog output terminal and the digital output terminal of the TV with a built-in BS digital tuner are respectively
It is necessary to connect to the analog input terminal and digital input terminal of the V control amplifier at the same time. And AV
In the control amplifier, the internal signal path is determined depending on whether the terrestrial broadcasting analog audio signal input from the analog input terminal is reproduced or the BS digital broadcasting MPEG2 ACC signal input from the digital input terminal is reproduced. You have to choose.

As a first method for selecting a signal path, there is a method in which a user inputs from the operation section of the AV control amplifier whether to select a signal path corresponding to an analog or digital audio input. is there.

As a second method, when the analog audio signal and the digital audio signal from one AV device are connected to the analog input terminal and the digital input terminal of the device so that the analog audio signal and the digital audio signal are simultaneously input, , If a digital audio signal (digital interface signal conforming to the digital audio interface standard (IEC-60958)) is input from the digital input terminal, the digital audio signal is output by the digital-analog (DA) converter in the AV control amplifier. There is a method in which the DA conversion is performed and the obtained analog audio signal is reproduced from the speaker connected to the AV control amplifier.

In the second selection method, the digital audio signal input from the digital input terminal is preferentially output, but the audio signal obtained based on the digital signal is more analog. This is based on the general idea that the audio signal is less affected by the transmission path and the sound quality is better than that of the audio signal obtained from the signal.

Further, in Japanese Patent Laid-Open No. 2000-331431, information indicating the type of digital audio signal is received from a DVD player, and based on the received information,
An audio input switching device for switching an input system is disclosed.

That is, in the technique disclosed in Japanese Patent Laid-Open No. 2000-331431, a DVD player (audio reproduction unit section) uses the DV recorded data on the DV
The type of the digital audio signal recorded in D is identified, and the information indicating the identified type of the digital audio signal is sent to the AV control amplifier (amplifier unit section) via the transmitting / receiving section. Then, the AV control amplifier outputs D based on the information indicating the type of the digital audio signal received from the DVD player.
The digital audio signal input from the VD player is
If it is a digital audio signal that can be decoded by itself, if it is a digital audio signal that can be decoded, the signal path is switched so that the digital audio signal input from the DVD player is decoded and output, and the decoding is performed. If the digital audio signal is impossible, the signal path is switched so as to output the analog audio signal input from the DVD player.

[0014]

When a terrestrial broadcast is received by a TV with a built-in BS digital tuner, since the terrestrial broadcast is an analog audio signal, the digital output terminal of the TV with a built-in BS digital tuner outputs a digital audio signal. The PCM silent signal is output without outputting the signal.

In this case, when the second signal path selection method is adopted in the AV control amplifier, the digital audio signal input from the digital input terminal is preferentially reproduced, so that the terrestrial wave is transmitted. The analog audio signal of the broadcast is not reproduced by the AV control amplifier, and the PCM silent signal from the digital input terminal is reproduced.

Therefore, the user must operate the AV control amplifier by the first signal path selection method and switch again so that the signal path corresponding to the analog audio input from the TV with the BS digital tuner is selected. is there.

When the first signal path selecting method is adopted and the signal path corresponding to the analog audio input from the TV with the built-in BS digital tuner is selected,
BS with built-in digital tuner BS from terrestrial broadcasting to BS
When switching to receive digital broadcasting, the MPEG2 ACC signal of BS digital broadcasting is output from the digital output terminal of the TV with built-in BS digital tuner. In order to reproduce this with the AV control amplifier, the user operates the AV control amplifier according to the first signal path selection method to select the signal path corresponding to the digital audio input from the TV with the BS digital tuner. In this case, the MPEG2 ACC signal cannot be decoded by the AV control amplifier, and the multi-channel audio cannot be reproduced.

Furthermore, in the technique disclosed in Japanese Patent Laid-Open No. 2000-331431, a DVD player and an A
Both V control amplifiers must have a transmitting / receiving unit for transmitting and receiving information indicating the type of digital audio signal, and when an external AV device other than such a DVD player is connected to the AV control amplifier. Cannot automatically switch signal paths. Further, since the AV control amplifier does not have the function of identifying the type of the input digital audio signal, for example, the signal path corresponding to the digital audio input from the TV with the BS digital tuner is selected. Sometimes a TV with a built-in BS digital tuner
When the side is switched to receive the terrestrial broadcast from the BS digital broadcast, the analog audio signal of the terrestrial broadcast is not reproduced by the AV control amplifier, and the PCM silent signal from the digital input terminal is reproduced.

As described above, conventionally, in order to reproduce the audio signal desired by the user with the AV control amplifier, the AV control amplifier is operated every time the broadcast received on the TV side with the BS digital tuner is switched.
It is necessary to switch the signal path.

An object of the present invention is to provide an audio reproducing apparatus which identifies the type of an input digital audio signal and automatically switches the internal signal path based on the identification result.

In particular, when the type of the input digital audio signal is a PCM silent signal, the present invention prevents the PCM silent signal from being reproduced by switching the signal path according to the analog audio signal. It is a thing.

[0022]

In order to achieve the above object, the present invention provides an audio reproducing apparatus having an analog input terminal for inputting an analog audio signal and a digital input terminal for inputting a digital audio signal, The type of the digital audio signal input from the digital input terminal is identified, and as a result of the identification, the type of the digital audio signal input from the digital input terminal is a PCM silent signal, and the PCM signal is input. If the status continues for a predetermined time,
In order to reproduce the analog audio signal input from the analog input terminal, the internal signal path is switched to the signal path corresponding to the analog audio signal.

When the digital audio signal input from the digital input terminal is no longer a PCM silence signal, the internal signal path is changed according to the digital audio signal so that the digital audio signal input from the digital input terminal is reproduced. I am trying to switch to a different signal path.

For example, when the analog input terminal and the digital input terminal are respectively connected to the analog output terminal and the digital output terminal of one TV with a built-in BS digital tuner, a T with a built-in BS digital tuner is used.
When the V side is switched to receive the terrestrial broadcast from the BS digital broadcast, the MPEG2 ACC signal that has been input from the digital input terminal until then is changed to the PCM silent signal. However, according to the audio reproducing apparatus of the present invention, Since the signal path is automatically switched to the signal path corresponding to the analog audio signal, the analog audio signal for terrestrial broadcasting is not reproduced and the PCM silent signal is not reproduced. When the TV with the built-in BS digital tuner is switched to receive the BS digital broadcast from the terrestrial broadcast, the PCM silent signal that has been input from the digital input terminal until then is MPEG2.
Although it changes to an ACC signal, the audio reproducing apparatus of the present invention automatically switches to a signal path corresponding to the digital audio signal. Therefore, a digital audio signal for BS digital broadcasting (MPEG2 ACC signal)
Is played.

Therefore, the user does not need to operate the AV control amplifier every time the broadcast received on the TV with the BS digital tuner is switched.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of an AV control amplifier according to the embodiment of the present invention.

In FIG. 1, 1 is a digital input section, 2 is a digital input selector, and 3 is a DIR (Digital Interfac).
e Receiver), 4 is an analog / digital (A / D) selector, and 5 is a DSP (Digital Signal Processo)
r), 6 are digital-analog (DA) converters, 7
Is an analog direct / DSP processing switching selector,
8 is an analog output section, 9 is an analog input section, 10 is an analog input selector, and 11 is an analog / digital (AD).
A converter, 12 is a host microcomputer, 13 is an operation unit, 1
4 is a display unit.

First, the overall configuration of the AV control amplifier according to this embodiment will be described with reference to FIG.

In the AV control amplifier according to this embodiment, a digital audio signal and an analog audio signal from a TV (not shown) with a BS digital tuner are input to the digital input unit 1 and the analog input unit 9, respectively. As described above, the analog output terminal and the digital output terminal of the TV with the built-in BS digital tuner are connected.

In the AV control amplifier according to this embodiment, a digital audio signal from a TV with a built-in BS digital tuner is input through the digital input section 1. Multiple external AV devices (DVD player, video tape recorder, etc.) other than the TV with built-in BS digital tuner
When the digital audio signal from the digital input selector 2 is input, the digital audio signal selected by the digital input selector 2 is DIR according to an instruction from the host microcomputer 12.
Sent to 3.

In the DIR3, since the input digital audio signal is a signal modulated by the biphase mark system, the digital audio signal is demodulated,
Additional information sent with the digital audio signal (sampling, emphasis, preamble information, etc.)
To extract.

The digital audio signal demodulated by the DIR 3 is sent to the A / D switching selector 4, and the A / D switching selector 4 selects the digital input side according to the instruction of the host microcomputer 12 and inputs it to the DSP 5. .

The additional information extracted by DIR3 is
It is sent to the host microcomputer 12 and stored in the main memory inside the host microcomputer 12.

Digital audio signals handled by the AV control amplifier according to the present embodiment include PCM audio and non-PCM audio bit streams, and non-PCM audio bit streams include DOLBY.
DIGITAL (registered trademark), DTS (registered trademark),
There are MPEG2 ACC and the like.

Since the bitstream is compressed data, it is necessary to decode it. However, since the bitstream data has a plurality of types as described above, the type of the bitstream data is identified, and the bitstream data is identified. It is necessary to select the decoding process according to the type of stream data.

Therefore, the host microcomputer 12 identifies the type of the digital audio signal (bit stream data) from the additional information of the digital audio signal stored in the main memory, and based on the identification result, the digital audio signal is identified. Decide the decryption software according to
The determined decoding software is set in the DSP 5.

The DSP 5 decodes the digital audio signal by using the decoding software set by the host microcomputer 12, and sends the decoded digital audio signal to the DA converter 6.

In the DA converter 6, the decoded digital audio signal is converted into an analog audio signal by the DA converter 6.
The converted and DA-converted analog audio signal is sent to the analog direct / DSP processing switching selector 7.

In the analog direct / DSP processing switching selector 7, D
The analog audio signal DA selected by the SP processing side and DA-converted by the DA converter 6 is output from the analog output unit 8. The analog output unit 8 is usually connected to a speaker (not shown).

On the other hand, in the AV control amplifier according to this embodiment, the analog audio signal from the TV with the built-in BS digital tuner is inputted through the analog input section 9. When analog audio signals are input from a plurality of external AV devices other than the TV with built-in BS digital tuner,
The analog audio signal selected by the analog input selector 10 is sent to the AD converter 11 and the analog direct / DSP processing switching selector 7.

Here, when it is not necessary to add a sound effect to the input analog audio signal in the AV control amplifier, the host microcomputer 12 sets A / A
The D switching selector 4 is switched to the analog input side, and the analog direct / DSP processing switching selector 7 is switched to the analog direct side so that the input analog audio signal is directly output from the analog output section 8.

When it is necessary to add a sound effect to the input analog audio signal in the AV control amplifier, the host microcomputer 12 sets the A / D
The switching selector 4 is switched to the analog input side, the analog direct / DSP processing switching selector 7 is switched to the DSP processing side, and the AD converter 11 is temporarily operated.
After AD conversion in, and the sound effect is added in DSP5,
The analog audio signal DA-converted by the DA converter 6 is again output from the analog output unit 8.

Note that it is assumed that the user has previously set from the operation unit 13 whether or not to add the sound effect.

Next, a method for the host microcomputer 12 to identify the type of digital audio signal will be described.

As shown in FIG. 2, the digital audio signal input to the DIR3 has an interface according to the digital audio interface standard (IEC-60958), and is encoded in the bit 27 to bit 12 portions of FIG. The stored digital audio signal is stored.

The encoded digital audio signal includes a bit stream of PCM audio and a bit stream of non-PCM audio, and the bit stream is a standard (IEC-) specified for applying the bit stream to the IEC-60958 interface. 61937), the data burst format is obtained as shown in FIG.
It is arranged in the part of bit27 to bit12 in FIG. 2, and each data burst has 16 bits at the beginning (total 6 bits).
4-bit) preamble (Pa, Pb, Pc, Pd)
Has been added. Here, Pa and Pb are synchronization codes,
Pc represents information about the data burst, and Pd represents the length of the data burst.

In order to identify whether the digital audio signal transmitted based on IEC-60958 is a PCM audio or a non-PCM audio bit stream, a preamble (Pa, Pb) is included in a subframe of IEC-6095. , Pc, Pd) exists, and if the preamble exists, the non-PCM
It can be determined that it is an audio bit stream, and if there is no preamble, it can be determined that it is PCM audio. In addition, the preamble (Pa, Pb, Pc, Pd) in the subframe of IEC-60958.
Is not present, and if bit27 to bit12 of the IEC-60958 subframe are all 0, P
It can be determined that the CM is a silent signal.

Further, in this way, when it is determined that the bit stream is a non-PCM audio bit stream, dat recorded in bits 4 to 0 of Pc is further recorded.
By examining a_type, the type of non-PCM audio bitstream can be identified. That is, whether or not it is an MPEG2 ACC signal for BS digital broadcasting can be identified by checking the data_type of Pc in the case of a non-PCM audio bit stream.

Next, the signal path switching operation of the AV control amplifier according to this embodiment will be described.

In the AV control amplifier according to the present embodiment, the host microcomputer 12 identifies the type of digital audio signal as described above, and when it determines that the signal is not the PCM silent signal, the A / D switching selector 4
Is switched to the digital input side, the analog direct / DSP processing switching selector 7 is switched to the DSP processing side, demodulated by DIR3, decoded by DSP5, and then DA converted by DA converter 6 8 to output. The signal path that can be switched here is "digital"
Call.

Further, in the AV control amplifier according to the present embodiment, the host microcomputer 12 identifies the type of digital audio signal as described above, and when it determines that the PCM silent state is reached, the time is set by the internal clock. measure.

During this time, the additional information stored in the main memory inside the host microcomputer 12 is updated by the DIR 3 each time the additional information appears in the digital audio signal input from the digital input section 1. The host microcomputer 12 identifies the type of digital audio signal each time the additional information is updated.

Then, when the measurement time reaches 1 second in the PCM silent state, the host microcomputer 12 switches the internal signal path so as to reproduce the analog audio signal input from the analog input section 9. . That is, the host microcomputer 12 uses the A / D switching selector 4
Is switched to the analog side, and the analog direct / DSP processing switching selector 7 is switched to the analog direct side so that the input analog audio signal is directly output from the analog output section 8. The signal path that can be switched here is called “analog direct”.

When it is necessary to add a sound effect to the input analog audio signal in the AV control amplifier, the host microcomputer 12 sets the A / D
The switching selector 4 is switched to the analog input side, the analog direct / DSP processing switching selector 7 is switched to the DSP processing side, and the AD converter 11 is temporarily operated.
After AD conversion in, and the sound effect is added in DSP5,
The analog audio signal DA-converted by the DA converter 6 is again output from the analog output unit 8. The signal path that can be switched here is "Analog DS
"P" and "analog direct" and "analog DSP" are collectively called "analog".

Here, the measurement time of 1 second means that the PCM output from the digital audio output when the program channel of the BS digital broadcast is switched when the BS digital broadcast is received by the TV with the built-in BS digital tuner. This is the time provided to prevent the signal path from being switched by the silent signal. At this time, the user follows the instruction displayed on the display unit 14
It is also possible to input and change a desired value from the operation unit 13.

That is, in the AV control amplifier according to this embodiment, when the type of the digital audio signal is not in the PCM silent state during the measurement for one second (before the measurement time is less than one second). Is set so that the signal path inside the AV control amplifier is "digital" rather than "analog"
The signal path is not switched every time the program channel of the S digital broadcast is switched.

Now, the procedure for the host microcomputer 12 to switch the signal path is shown in the flowchart of FIG.

As described above, the main memory of the host microcomputer 12 stores the additional information extracted by DIR3.

Therefore, as shown in FIG. 4, the host microcomputer 12 first determines the type of the digital audio signal input from the digital input section 1 through the digital input selector 2 from the additional information stored in the main memory. Is identified (step S1). The types here include PCM and P
CM silence, DOLBY DIGITAL (registered trademark),
DTS (registered trademark), MPEG2 ACC, etc. are included.

Subsequently, the host microcomputer 12 confirms whether or not the identification result of step S1 is PCM silence, and PCM silence continues for 1 second or more (step S).
2).

If a positive result is obtained in step S2, the host microcomputer 12 sets the signal path inside the AV control amplifier to "analog" (step S2).
3) The signal path switching procedure is ended. In the AV control amplifier according to the present embodiment, since two types of signal paths, "analog direct" and "analog DSP", are prepared, which signal path is set is set in advance by the user. Follow the content.

When a negative result is obtained in step S2, the host microcomputer 12 sets the signal path inside the AV control amplifier to "digital" (step S2).
4) The signal path switching procedure ends.

As described above, according to the AV control amplifier according to the embodiment of the present invention, the type of the input digital audio signal is discriminated, and as a result of the discrimination, the PC
When it is determined that the M silence signal has continued for a predetermined time, the signal path inside the AV control amplifier is set to be "analog".
When the TV with a built-in digital tuner is switched to receive the terrestrial broadcast from the BS digital broadcast, the analog audio signal for the terrestrial broadcast is reproduced and the PCM silent signal is not reproduced. When the TV with the built-in BS digital tuner is switched to receive BS digital broadcasting from terrestrial broadcasting, the signal path inside the AV control amplifier is set to "digital", and digital audio for BS digital broadcasting is set. The signal (MPEG2 ACC signal) is reproduced.

Therefore, the user does not need to operate the AV control amplifier every time the broadcast received on the TV with the BS digital tuner is switched, and the desired reproduced sound can always be obtained.

[0066]

As described above, according to the audio reproducing apparatus of the present invention, the type of the input digital audio signal is identified and the internal signal path is automatically switched based on the identification result. Will always be able to obtain the desired playback sound.

In particular, since the internal signal path is switched so as to reproduce the analog signal even when the analog audio signal is input while the internal signal path is switched so as to reproduce the digital audio signal, It is possible to prevent the PCM silent signal from being reproduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an AV control amplifier according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an IEC-60958 interface format.

FIG. 3 is an explanatory diagram showing a data burst format.

FIG. 4 is a flowchart showing a signal path switching procedure according to the embodiment of the present invention.

[Explanation of symbols]

1: Digital input section 2: Digital input selector 3: DIR (Digital Interface Receiver) 4: Analog / digital (A / D) switching selector 5: DSP (Digital Signal Processor) 6: Digital-analog (DA) converter 7: Analog direct / DSP processing switching selector 8: Analog output section 9: Analog input section 10: Analog input selector 11: Analog-to-digital (AD) converter 12: Host microcomputer 13: Operation unit 14: Display

Claims (2)

[Claims] 1. An analog input terminal for inputting an analog audio signal, a digital input terminal for inputting a digital audio signal, identification means for identifying the type of digital audio signal input from the digital input terminal, and the identification means. As a result of identification by the PCM, the type of digital audio signal input from the digital input terminal is PCM.
(Pulse Code Modulation) An internal audio signal that is input from the analog input terminal is reproduced when the PCM audio signal is a silence signal and the state in which the PCM silence signal is input continues for a predetermined time. And a switching means for switching the internal signal path so as to reproduce the digital audio signal input from the digital input terminal, if not. 2. The audio reproducing apparatus according to claim 1, further comprising signal processing means for subjecting the digital audio signal input from the digital input terminal to signal processing according to the type identified by the identifying means. An audio reproducing device characterized by.