JPH0730497A - Voice data processing circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide an audio data processing circuit capable of avoiding the generation of annoying audible popping noise even when the broadcast audio mode or the audio output mode is switched. [Structure] The output selection control signal transition detection means 14 detects the presence or absence of a change in the output selection control signal. When there is a change in the output selection control signal, the soft mute means 6 performs a fade-out in which the audio data is gradually attenuated, and a fade-in in which the mute state is restored after the fade-out. The mute state detecting means 13 detects whether the soft mute means 6 has entered the mute state. Switching means 3
Transmits the output selection control signal to the channel number converting means 5 and the speaker selecting means 9 when the mute state is established. The channel number converting means 5 and the speaker selecting means 9 switch the contents of the audio data processing while in the mute state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PCM voice receiver, and more particularly, it inputs PCM voice data, sequentially processes the voice data by a plurality of voice data processing means, converts the voice data into analog or digital voice data and outputs the voice data. The present invention relates to an audio signal processing circuit.

[0002]

2. Description of the Related Art Recently, PCs using broadcasting satellites and communication satellites
Along with the spread of M music broadcasting, digital signal processing aimed at improving the performance related to sound has been rapidly progressing. Specific examples of the audio PCM broadcasting currently performed include audio of BS (satellite) broadcasting of the current NTSC television system and audio of high-definition broadcasting. Among these broadcasts, as a conventional example of digital signal processing for receiving PCM audio of high-vision broadcast, for example, Proceedings 1 of the 1992 Annual Conference of the Television Society of Japan
6-6. There is a MUSE receiving audio processing LSI described in "Second Generation MUSE Audio Decoder IC" on pages 305 to 306.

In this conventional example, voice data time-division-multiplexed with a MUSE signal is extracted, and voice LPF processing, time extension of voice data, frame deinterleave, voice synchronization and control signal detection, bit deinterleave, error. After each process such as correction and word deinterleaving, the obtained PCM voice data is demodulated, and the demodulated voice data is selected as the voice output mode specified by the user, and the voice for the digital audio interface is selected. Performs various processing such as conversion to output.

[0004]

[Problems to be Solved by the Invention] By the way, the current NTS
In BS broadcasts and high-definition broadcasts of the C television system, there are many broadcast audio modes (for example, there are modes for performing bilingual broadcasts, modes for performing stereo broadcasts, etc.).
Are planned, and their broadcast audio modes can be switched on the transmission side (broadcasting station side). On the other hand, the receiving side (PCM
On the audio receiver side, the user can select the audio output mode according to the speaker format (for example, for bilingual broadcasting, output only the main audio [Japanese] or only the sub audio [English]). There is a mode for outputting, a mode for outputting both voices, etc.), and those voice output modes can be switched according to the designation by the user.

However, in the above-mentioned conventional example, when the broadcast audio mode or the audio output mode is switched in such a manner, the contents of the audio data processing are switched according to the switching, and the output signal format is switched. Therefore, there is a problem in that the reproduced sound is discontinuous at the time of the switching, and an audible jarring noise is generated.

An object of the present invention is to solve the above-mentioned problems of the prior art and to avoid the generation of a jarring audible audible noise even when the broadcast audio mode or the audio output mode is switched. It is to provide an audio data processing circuit.

[0007]

In order to achieve the above object, the present invention combines an audio mode signal representing a broadcast audio mode and an audio output mode control signal representing an audio output mode designated by a user. Output selection control signal transition detection means for detecting the presence or absence of a change in the output selection control signal generated by the above, and when the output selection control signal transition detection means detects that there is a change in the output selection control signal. First, soft mute means for gradually attenuating the level of the audio data to make it into a mute state, and then gradually amplifying it to restore the original state, and detecting whether or not the soft mute means is in the mute state Mute state detecting means and switching means for switching whether or not to transmit the output selection control signal to a specific audio data processing means are provided, When the soft state mute means detects that the soft mute means is in the mute state, the switching means transmits the output selection control signal to the sound data processing means, and the sound data processing means The processing contents are changed.

[0008]

In the present invention, when the output selection control signal is switched, it is detected by the output selection control signal transition detection means that the output selection control signal has changed, and the soft mute means immediately outputs the audio data. Fades out by gradually decreasing the level of. When the mute state detecting means detects that the soft mute means is in the mute state, the switching means transmits the output selection control signal to the audio data processing means, and the processing of the audio data processing means. Change the content. That is, in the state where the audio data is completely muted, the contents of the audio data processing are switched according to the output selection control signal. After that, the soft mute means
Fade-in is performed in which the mute state is released, and the audio data level is gradually amplified to restore the original state.

As a result, even if the output selection control signal is switched, the content of the audio data processing in the audio data processing means is switched when the reproduced sound is completely muted by the soft mute means, so that the audio data processing is switched. It is possible to avoid generation of pop noise caused by discontinuity of audio data due to switching of data processing contents.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an audio data processing circuit as a first embodiment of the present invention. In this example,
It is an audio data processing circuit in a receiver that receives MUSE broadcasting. In FIG. 1, 1 is an input terminal for PCM audio data, 2 is a PCM decoder, 4 is an input terminal for an output selection control signal, which will be described later, and 3 is whether or not to transmit an output selection control signal input from the input terminal 4. Switching means for switching,
Is. Reference numeral 5 designates a 3-1 system 4-channel stereo sound of high definition broadcasting according to the MUSE system, for example, a general 2
Channel number conversion means 6 having a function of converting to channel stereo sound, and 6 is a soft mute means.
7 is a digital audio interface (EIAJ /
CP-120 1) digital audio interface conversion unit for converting into digital audio data, 8 is an oversampling digital filter, 9 is speaker selection means for deciding reproduced sound to a speaker (not shown), 10
Is a DA (digital / analog) converter, 11 is an output terminal for analog audio data, 12 is an output terminal for digital audio data, 13 is a mute state detecting means for detecting the mute state of the soft mute means 6, and 14 is an input terminal 4
An output selection control signal transition detecting means for detecting a change in the output selection control signal input from the device 101, a data processing unit 101 for analog voice, and a data processing unit 102 for digital voice.

Here, the output selection control signal input from the input terminal 4 is an audio mode signal representing a broadcasting audio mode in MUSE broadcasting (for example, a mode for performing bilingual broadcasting or a mode for performing stereo broadcasting. And a voice output mode control signal indicating a voice output mode designated by the user.

Now, the circuit operation of FIG. 1 will be described.
The PCM decoder 2 receives the PCM input from the input terminal 1.
PCM decoding processing such as bit or word deinterleaving and error correction is performed on the audio data to convert it into normal audio data (audio digital signal). In the channel number converting means 5, the switching means 3 described later from the input terminal 4 is used.
Output selection control signal transmitted through the PCM
For example, when the audio output mode designated by the user is switched, the decoded audio data is matrix-converted from the 4-channel audio data into general left and right 2-channel stereo audio data to perform analog audio data processing. It leads to the speaker selection means 9 in the unit 101 and the digital audio interface conversion unit 7 in the data processing unit 102 for digital voice. The speaker selection means 9 determines the reproduced sound in each speaker from the 4-channel audio data according to the output selection control signal transmitted from the input terminal 4 via the switching means 3 described later, and the soft mute means 6 is determined. Lead.

On the other hand, the output selection control signal transition detecting means 14
Detects whether there is a change in the output selection control signal input from the input terminal 4 and guides the detection result to the soft mute means 6. In the soft mute means 6, when the detection result indicating that there is a change in the output selection control signal is introduced, first, the audio data introduced from the speaker selection means 9 to the oversampling digital filter 8 is gradually attenuated. After fading out and muting,
To cancel the mute state of this audio data again,
Fade in to restore.

At this time, the mute state detecting means 13 detects whether or not the soft mute means 6 enters the mute state, and guides the detection result to the switching means 3. The switching means 3 transmits the output selection control signal input from the input terminal 4 to the channel number converting means 5 and the speaker selecting means 9 when the detection result indicating that the mute state is set is introduced. Thereby, the channel number converting means 5 and the speaker selecting means 9 switch the contents of the audio data processing while in the mute state.

The DA converter 10 converts the digital audio data from the oversampling digital filter 8 into analog audio data and guides it to the output terminal 11. On the other hand, in the digital audio interface conversion unit 7 in the digital audio data processing unit 102, the audio data from the channel number conversion unit 5 is added with a channel status indicating prohibition / permission of digital copy, and the result is led to the output terminal 12. .

As described above, the soft mute means 6 is used for the analog audio data output from the output terminal 11.
When the reproduced sound is completely muted by, the content of the audio data processing in the channel number converting means 5 and the speaker selecting means 9 is switched, so that the discontinuity of the audio data accompanying the switching of the content of the audio data processing is performed. It is possible to avoid the generation of noises caused by noise.

Next, the structure and operation of the main part of this embodiment will be described in detail with reference to FIGS.
2 is a block diagram showing a specific configuration of a main part of FIG. 1, and FIG. 3 is a flowchart showing a flow of operations when the output selection control signal changes from the steady state.

In FIG. 2, 201 is an audio data processing unit, 202 is a coefficient multiplying unit, 203 and 207 are selectors, 204 is a control signal decoding unit, 205 is a coefficient value detecting unit, 206 is an output selection control signal fetching unit, and 20.
8, 209 and 210 are latch means, 211 is comparison means,
212 is a switch. Here, the voice data processing unit 2
Reference numeral 01 comprises the channel number converting means 5 and the speaker selecting means 9 in FIG. Further, the output selection control signal transition detection means in FIG. 1 includes latch means 209, 210,
Comparing means 211, soft mute means 6 is composed of coefficient multiplying means 202 and selector 203, mute state detecting means 13 is composed of coefficient value detecting means 205, and switching means 3 is output selection control signal fetching means 20.
6, a switch 212, and a control signal decoding means 204. The output selection control signal fetching means 206
Is composed of a latch means 208 and a selector 207.

Of these, the latch means 208, 20
Reference numerals 9 and 210 are for fetching the output selection control signal.
The comparison means 211 compares the output selection control signals before and after the latch means 210. Further, the coefficient multiplying means 202 uses u
It has a p / down counter and its up / down
The output of the n counter is multiplied by the audio data as a coefficient for fading out and fading in. The selector 203 selects and outputs one of the audio data faded out or faded in by the coefficient multiplication means 202 and the audio data from the audio data processing unit 201.

The coefficient value detecting means 205 detects the coefficient value multiplied by the coefficient multiplying means 202. Further, the switch 212 outputs the output selection control signal to the control signal decoding means 20.
4 is a switch that transmits or cuts off to the voice data processing unit 201 via 4, and is turned on when the coefficient value detected by the coefficient value detection means 205 is minimum, and is turned off when it is not minimum. The selector 207 is a coefficient multiplication means 202
It is a selector that transmits or cuts off the clock to the latch means 208 according to the coefficient value of, and selects the ◯ mark when the coefficient value is the maximum and the  mark when the coefficient value is not the maximum. The control signal decoding means 204 decodes the output selection control signal into a control signal for the audio data processing unit 201.

Now, when the circuit of FIG. 2 is in a steady state (step a of FIG. 3), the selector 203 and the selector 207 select the one marked with a circle, and the switch 212 is turned off.
is doing.

First, when the output selection control signal is switched to the latch means 208 (step b in FIG. 3), the comparison means 211 detects that there is a change in the output selection control signal (FIG. 3). Step c).

The selector 203 of the soft mute unit 6 is switched to the mark ● by the control signal from the comparison unit 211, and the coefficient of the coefficient multiplication unit 202 is generated up /
The down counter counts down the output and fades out the audio data output from the soft mute means 6 (step d in FIG. 3). When the fade-out is started, the value of the coefficient which is the output of the up / down counter is not the maximum value, and the selector 207 is switched to the mark ●.
The latch means 208 stops taking in the output selection control signal (step e in FIG. 3).

When the coefficient value output from the up / down counter reaches the minimum value, the switch 212 is turned on.
Therefore, the output selection control signal is converted into the control signal decoding means 20.
4 and the control signal decoding means 204 newly decodes the control signal (step f in FIG. 3), whereby the content of the audio data processing in the audio data processing unit 201 is switched and the output signal format is switched. (Step g in FIG. 3). The up / down counter holds the value for a certain period (holding period) after the value of the output coefficient reaches the minimum value, and here, outputs the holding period to the control signal decoding means 204. The time is from the transmission of the selection control signal to the switching of the contents of the audio data processing by the audio data processing unit 201.

In order to perform fade-in by the soft mute means 6 after a lapse of a fixed time required for switching the contents of the audio data processing in the audio data processing unit 201, u
The p / down counter starts counting up the output and performs fade-in (step h in FIG. 3). At this time, when the count-up is started, the value of the coefficient output from the up / down counter is not the minimum value, the switch 212 is turned off, and the control signal decoding means 20
The output selection control signal transmitted to 4 is cut off.

When the value of the coefficient which is the output of the up / down counter reaches the maximum value, the selector 207 and the selector 203 select the one marked with a circle, and the latch means 20.
8 can take in a new output selection control signal (step i in FIG. 3). Then, the audio data corresponding to the changed output selection control signal is output from the soft mute means 6, and the circuit of FIG. 2 returns to the steady state (step j of FIG. 3).

When there is a change in the output selection control signal in this way, the above series of operations 1 to 3 are performed. As a result, the content of the audio data processing in the audio data processing unit 201 is changed (switched) when the reproduced sound is completely muted, so that the discontinuity of the audio data accompanying the switching of the content of the audio data processing is discontinued. It is possible to avoid the generation of noises caused by noise.

In this embodiment, the switching means 3, the soft mute means 6 and the like have been described as circuits, but the present invention is not limited to this, and it is also possible to realize them by software using a microcomputer or the like.

Further, in this embodiment, the soft mute means 6 is arranged between the speaker selecting means 6 and the oversampling digital filter 8, but the soft mute means 6 is arranged.
The arrangement of is not limited to this. Next, an embodiment in which the arrangement of the soft mute means 6 is different from that of this embodiment will be described.

FIG. 4 is a block diagram showing an audio data processing circuit as a second embodiment of the present invention. 4, the same components as those in FIG. 1 are denoted by the same symbols. The configuration of this embodiment is different from that of FIG. 1 in that the arrangements of the speaker selecting means 9 and the soft mute means 6 in the analog audio data processing unit 101 are interchanged, and other configurations are the same as those of FIG. It is similar to the embodiment of.

As described above, even if the arrangements of the speaker selecting means 9 and the soft mute means 6 are interchanged, the output selection control signal transition detecting means 14, the soft mute means 6, the mute state detecting means 13, and the switching means 3 are shown in FIG. By performing the same operation as that of the embodiment, the same effect as that of the embodiment of FIG. 1 can be obtained. That is, regarding the analog audio data output from the output terminal 11, when the reproduced sound is completely muted by the soft mute means 6, the contents of the audio data processing in the channel number converting means 5 and the speaker selecting means 9 are switched. Since it is performed, it is possible to avoid generation of a clicking sound or the like caused by the discontinuity of the audio data due to the switching of the content of the audio data processing.

Next, FIG. 5 is a block diagram showing an audio data processing circuit as a third embodiment of the present invention. 5, the same components as those in FIG. 1 are designated by the same symbols. The configuration of this embodiment is different from that of the embodiment of FIG. 4 in that the data output port of the digital audio data processing unit 102 to the digital audio interface conversion unit 7 is between the soft mute means 6 and the speaker selection means 9. The other configuration is the same as that of the embodiment of FIG.

In this way, the data output port for the digital audio interface conversion section 7 is provided between the soft mute means 6 and the speaker selection means 9, so that the audio data through the soft mute means 6 is for analog audio, The output selection control signal transition detection means 14, the soft mute means 6, the mute state detection means 13, and the switching means 3 perform the same operations as in the embodiment of FIG. Output terminal 1
In addition to the analog audio data output from 1, the digital audio data output from the output terminal 12 can be faded out and attenuated to gradually attenuate the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of noise.

Next, FIG. 6 is a block diagram showing an audio data processing circuit as a third embodiment of the present invention. 6, the same components as those in FIG. 1 are designated by the same symbols. The configuration of this embodiment is different from that of FIG. 5 in that the arrangements of the soft mute means 6 and the channel number converting means 5 are interchanged, and other configurations are the same as those of the embodiment of FIG.

As described above, even when the arrangements of the soft mute means 6 and the channel number conversion means 5 are interchanged, the output selection control signal transition detection means 14, the soft mute means 6, the mute state detection means 13, and the switching means 3 are shown in FIG. By performing the same operation as that of the embodiment, the same effect as that of the embodiment of FIG. 5 can be obtained. That is, for both the analog audio data output from the output terminal 11 and the digital audio data output from the output terminal 12, a fade-out that gradually attenuates the audio data and a fade-in that restores the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of humming noise.

Next, FIG. 7 is a block diagram showing an audio data processing circuit as a fifth embodiment of the present invention. 7, the same components as those in FIG. 1 are designated by the same symbols. The configuration of this embodiment is different from that of the embodiment of FIG. 6 in that the data output port of the digital audio data processing unit 102 to the digital audio interface conversion unit 7 is the speaker selection means 9 and the oversampling digital filter 8. The other points are the same as those in the embodiment of FIG.

As described above, even if the data output port to the digital audio interface conversion unit 7 is provided between the speaker selection unit 9 and the oversampling digital filter 8, the output selection control signal transition detection unit 14 and the soft mute unit 6 are provided. , Mute state detecting means 13, switching means 3
By performing the same operation as that of the embodiment of FIG. 1, it is possible to obtain the same effect as that of the embodiment of FIG. That is, for both the analog audio data output from the output terminal 11 and the digital audio data output from the output terminal 12, a fade-out that gradually attenuates the audio data and a fade-in that restores the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of humming noise.

Next, FIG. 8 is a block diagram showing an audio data processing circuit as a sixth embodiment of the present invention. 8, the same components as those in FIG. 1 are designated by the same symbols. 7 is different from the embodiment of FIG. 7 in that the arrangements of the soft mute means 6 and the channel number converting means 5 are interchanged, and other configurations are the same as those of the embodiment of FIG.

As described above, even if the arrangements of the soft mute means 6 and the channel number conversion means 5 are interchanged, the output selection control signal transition detection means 14, the soft mute means 6, the mute state detection means 13, and the switching means 3 are shown. By performing the same operation as that of the first embodiment, the same effect as that of the embodiment of FIG. 7 can be obtained. That is, for both the analog audio data output from the output terminal 11 and the digital audio data output from the output terminal 12, a fade-out that gradually attenuates the audio data and a fade-in that restores the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of humming noise.

Next, FIG. 9 is a block diagram showing an audio data processing circuit as a seventh embodiment of the present invention. 9, the same components as those in FIG. 1 are designated by the same symbols. The configuration of this embodiment is different from that of FIG. 8 in that the arrangements of the soft mute means 6 and the speaker selection means 9 are interchanged, and other configurations are the same as those of the embodiment of FIG.

As described above, even if the arrangements of the soft mute means 6 and the speaker selection means 9 are interchanged, the output selection control signal transition detection means 14, the soft mute means 6, the mute state detection means 13, and the switching means 3 are shown in FIG. By performing the same operation as that of the embodiment described above, the same effect as that of the embodiment of FIG. 8 can be obtained. That is, for both the analog audio data output from the output terminal 11 and the digital audio data output from the output terminal 12, a fade-out that gradually attenuates the audio data and a fade-in that restores the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of humming noise.

Next, FIG. 10 is a block diagram showing an audio data processing circuit as an eighth embodiment of the present invention. Figure 1
0, the same components as those in FIG. 1 are denoted by the same symbols. When the configuration of the present embodiment is compared with the embodiment of FIG. 6 described above, the configuration of the present embodiment is different from the embodiment of FIG. 6 in that the digital audio interface conversion unit 7 in the data processing unit 102 for digital voice is used. The data extraction port is provided between the soft mute means 6 and the channel number conversion means 5, and the other structure is the same as that of the embodiment of FIG.

As described above, even if the data output port to the digital audio interface conversion unit 7 is provided between the soft mute unit 6 and the channel number conversion unit 5, the output selection control signal transition detection unit 14 and the soft mute unit 6 are provided. The same effect as that of the embodiment of FIG. 6 can be obtained by the mute state detecting means 13 and the switching means 3 performing the same operation as that of the embodiment of FIG. That is, for both the analog audio data output from the output terminal 11 and the digital audio data output from the output terminal 12, a fade-out that gradually attenuates the audio data and a fade-in that restores the audio data when the output selection control signal changes. Therefore, it is possible to avoid the generation of humming noise.

[0045]

According to the present invention, when the broadcast audio mode or the audio output mode is switched and the output selection control signal changes, the audio data processing is performed when the reproduced sound is completely muted by the soft mute means. Since the contents of voice data processing by means are switched,
It is possible to avoid generation of pop noise caused by discontinuity of audio data due to switching of contents of audio data processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing an audio data processing circuit as a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of a main part of FIG.

FIG. 3 is a flowchart showing a flow of operation when an output selection control signal changes from a steady state.

FIG. 4 is a block diagram showing an audio data processing circuit as a second embodiment of the present invention.

FIG. 5 is a block diagram showing an audio data processing circuit as a third embodiment of the present invention.

FIG. 6 is a block diagram showing an audio data processing circuit as a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing an audio data processing circuit as a fifth embodiment of the present invention.

FIG. 8 is a block diagram showing an audio data processing circuit as a sixth embodiment of the present invention.

FIG. 9 is a block diagram showing an audio data processing circuit as a seventh embodiment of the present invention.

FIG. 10 is a block diagram showing an audio data processing circuit as an eighth embodiment of the present invention.

[Explanation of symbols]

1 ... PCM audio data input terminal, 2 ... PCM decoder,
3 ... Switching means, 4 ... Output selection control signal input terminal, 5 ... Channel number converting means, 6 ... Soft mute means, 7 ... Digital audio interface converting section, 8 ... Oversampling digital filter, 9 ... Speaker selecting means,
10 ... DA converter, 11 ... Analog audio data output terminal, 12 ... Digital audio data output terminal, 13 ... Mute state detecting means, 14 ... Output selection control signal transition detecting means, 101 ... Analog audio data processing section, 102 ...
Data processing unit for digital audio, 201 ... Audio data processing unit, 202 ... Coefficient multiplying means, 203, 207 ... Selector, 204 ... Control signal decoding means, 205 ... Coefficient value detecting means, 206 ... Output selection control signal fetching means, 20
8, 209, 210 ... Latch means, 211 ... Comparison means,
212 ... Switch.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroaki Takagishi, 5-20-1 Josuihoncho, Kodaira-shi, Kodaira, Tokyo Inside the Semiconductor Design and Development Center, Hitachi, Ltd. (72) Inventor Shinya Aizawa, Kodaira, Tokyo Honcho 5-chome No. 20-1 Incorporated company Hitachi Ltd. Semiconductor Design Development Center

Claims (1)

[Claims] 1. A plurality of audio data processing means are provided, PCM audio data is input, sequentially processed by the plurality of audio data processing means, converted into analog or digital audio data and output. An audio data processing circuit including at least an audio data processing means (hereinafter, referred to as a specific audio data processing means) for changing the processing content according to the change of the output selection control signal transmitted among the plurality of audio data processing means. In addition, an output selection control signal transition detection means for detecting the presence or absence of a change in the output selection control signal is provided, and it is detected by the output selection control signal transition detection means that the output selection control signal has changed. In this case, the audio data level is gradually attenuated, put into a mute state, and then gradually amplified to restore the original state. And a mute state detecting means for detecting whether or not the soft mute means is in a mute state, and the output selection control signal for the specific voice data processing. Switching means for switching whether or not to transmit to the means, and when at least the mute state detecting means detects that the soft mute means is in the mute state, the switching means outputs the output. An audio data processing circuit, characterized in that a selection control signal is transmitted to the specific audio data processing means to change processing contents of the specific audio data processing means.