JP3854188B2 - Audio signal processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates generally to an audio signal processing apparatus applied to a digital audio communication system in the mobile communication field such as a mobile phone, and more particularly to a noise suppression function and an echo suppression function in audio encoding processing.
[0002]
[Prior art]
In general, in the mobile communication field such as a mobile phone, a digital voice communication system is applied. In the digital voice communication system, a voice coding (compression coding) system is used to compress voice data for transmission.
[0003]
In the mobile communication field, a low bit rate coding method called a CELP (Code Excited Linear Prediction) method is well known as a typical speech coding method. When speech coding is performed by such a method, not only a speech signal but also a speech signal including a noise component called high ambient noise is coded. However, it is known that when a speech signal including a noise component and an echo component is encoded as it is, speech encoded data with degraded quality is generated. For this reason, in general, a noise suppression circuit called a noise canceller is used in the speech coding circuit so that only a speech signal in which the noise component is suppressed is input, or a speech signal in which the echo component is suppressed is input. As described above, an echo suppression circuit such as an echo canceller or a voice switch is used.
[0004]
For example, when there is no audio signal, the noise canceller determines the state of only the ambient noise signal, analyzes the feature, and suppresses the noise component using the feature in a section where the audio signal and the noise component are mixed. It is configured as follows. The echo canceller learns the acoustic characteristics of wraparound from reception to transmission, for example, when a voice signal arrives at the reception side and the transmission side is not talking at all, that is, determines the single talk state of the reception. The echo component mixed in the signal on the transmission side is suppressed using the acoustic characteristics. The voice switch is configured to suppress the echo component by comparing the signal power between receiving and transmitting, for example, and putting a loss in the smaller power.
[0005]
In addition, the voice encoding method used in current mobile phones is mainly limited to a band in which a voice signal exists. In recent years, in order to obtain higher quality, a high-frequency audio encoding method that performs audio encoding in a wider band than the audio signal band is being standardized. Even in such a wideband speech coding system, the CELP system is used, so that a noise canceler for suppressing a noise component which is a high ambient noise is required, or an echo canceller or voice for suppressing an echo component. A switch is required.
[0006]
FIG. 17 is a block diagram showing a general configuration of an audio signal processing apparatus adopting a wideband audio encoding method using a noise canceller.
[0007]
The audio processing apparatus converts an audio signal input to the microphone 10 into a digital audio signal by the A / D converter 11 and generates audio encoded data (TX) from the digital audio signal, and an audio The encoded data (RX) is roughly divided into a reproduction system (decoding system) that converts audio signals into analog signals by the D / A converter 21 and outputs sound from the speaker 20.
[0008]
The encoding system includes a noise canceller 70, an encoder 71, and a multiplexer (data multiplexing unit) 14 in addition to the microphone 10 and the A / D converter 11. The noise canceller 70 is a circuit that suppresses a noise component that is high ambient noise from a digital audio signal. The encoder 71 is a speech encoding circuit that compresses and encodes a digital speech signal whose noise component is suppressed by a predetermined algorithm (for example, CELP method). On the other hand, the reproduction system usually includes a demultiplexer 23 and a decoder (audio decoding circuit) 22 in order to decode audio encoded data stored in a memory into original audio data.
[0009]
Here, in particular, the wideband encoder 71 includes a low-frequency speech encoder (sometimes referred to as an L coder) 700, and a high-frequency speech encoder (sometimes referred to as an H coder) 701. It is divided into. By the way, the digital audio signal that has passed through the noise canceller 70 is divided into a high frequency audio signal component that has no power as an audio signal and is not so important in terms of information, and other low frequency audio signal components. In a certain encoding mode, there is a method in which a high-frequency audio signal component is unnecessary and is previously removed from audio encoded data. Therefore, the multiplexer 14 outputs audio encoded data including only the low frequency audio signal component or outputs audio encoded data including the high frequency audio signal component.
[0010]
[Problems to be solved by the invention]
As described above, in the encoder divided into the low frequency speech encoder 700 and the high frequency speech encoder 701, only the L coder 700 may operate according to the encoding mode. In such an encoding mode, the noise canceller 70 does not need to perform noise suppression processing on the digital audio signals in all the bands output from the A / D converter 11, but only on the low frequency audio signal components. Noise suppression processing may be used.
[0011]
However, in the conventional method, even in the mode in which only the low-band speech encoder 700 operates, the noise canceller 70 performs processing on digital speech signals in all bands. Here, normally, the noise canceller 70, the encoder 71, and the multiplexer 14 are configured by a digital signal processor (DSP). For this reason, the conventional method has a problem that an excessive data processing amount and memory amount are required for the DSP to realize the function of the noise canceller 70.
[0012]
Accordingly, an object of the present invention is to reduce the amount of data processing and the amount of memory required for the noise canceller function particularly in the coding system without deteriorating the voice quality, and as a result, the voice signal processing efficiency can be improved. An object is to provide an audio signal processing apparatus.
[0013]
FIG. 18 is a block diagram showing a general configuration of an audio signal processing apparatus adopting a wideband audio encoding system using an echo canceller 72. When only the L coder 700 is operated, only the low frequency audio signal component is shown. In the same way, it is desirable to reduce the data processing amount and the memory amount.
[0014]
Further, the same is desired for the voice switch 73 as shown in FIG. Accordingly, an object of the present invention is to reduce the data processing amount and the memory amount required for the echo suppression function to improve the audio signal processing efficiency.
[0015]
[Means for Solving the Problems]
An aspect of the present invention is a high frequency noise canceller function particularly in a speech signal processing apparatus having a wideband speech encoding circuit (encoder) and a noise canceller in a mode in which the high frequency speech encoder included in the encoder is not operated. The present invention relates to an audio signal processing device that invalidates the sound. In other words, in the mode in which only the low frequency speech coder is operated, the speech signal processing device enables the low frequency noise canceller function.
[0016]
An audio signal processing device according to an aspect of the present invention is an audio signal processing device that encodes a digital audio signal, wherein the digital audio signal is divided into a high-frequency component signal and a low-frequency component signal; First encoding means for encoding the high-frequency component signal and a second code for encoding the low-frequency component signal in response to an operation mode signal instructing encoding of the high-frequency component signal And Before being encoded by the first and second encoding means, First suppression means for suppressing noise components included in the digital audio signal; Before being encoded by the second encoding means, A second suppression means for suppressing a noise component included in the low-frequency component signal; and when the operation mode signal does not instruct encoding of the high-frequency component signal, By the second encoding means And a control unit that encodes the low-frequency component signal and controls the first suppression unit not to operate.
[0017]
With such a configuration, noise suppression is performed only on the low frequency audio signal component when the audio encoding processing is performed only on the low frequency audio signal component without performing audio encoding processing on the high frequency audio signal component. Processing can be executed. Therefore, for example, in a configuration in which noise suppression processing is executed by a DSP, the amount of data processing and memory required for the function of the noise canceller can be reduced in a mode in which high frequency speech encoding processing is not executed. Therefore, as a result, an audio signal processing device that can improve the audio signal processing efficiency can be provided.
[0018]
Another aspect of the present invention is that in a speech signal processing apparatus having a wide-band encoder and echo suppression means (echo canceller, voice switch), in a mode in which the high-frequency speech encoder included in the encoder is not operated. The present invention also relates to an audio signal processing device that disables the function of high-frequency echo suppression means. In other words, in the mode in which only the low frequency speech coder is operated, the speech signal processing device validates the function of the low frequency echo suppression means.
[0019]
An audio signal processing apparatus according to an aspect of the present invention includes a dividing unit that divides a digital audio signal into a high-frequency component signal and a low-frequency component signal; In response to an operation mode signal that instructs encoding of the high-frequency component signal, A first encoding unit that encodes the high-frequency component signal; a second encoding unit that encodes the low-frequency component signal; First suppression means for suppressing an included echo component; and second suppression means for suppressing an echo component generated due to the received voice signal and included in the low-frequency component signal; When the operation mode signal does not instruct encoding of the high frequency component signal, The low frequency component signal with respect to the digital audio signal And And a control unit that controls the first suppression unit not to operate.
[0020]
With such a configuration, when the speech coding process is performed only on the low frequency speech signal component without performing the speech coding processing on the high frequency speech signal component, only the low frequency speech signal component is performed. Echo suppression processing can be executed. Therefore, for example, in a configuration in which echo suppression processing is executed by a DSP, the amount of data processing and memory required for the functions of the echo canceller and voice switch can be reduced in a mode in which high frequency speech encoding processing is not executed. Therefore, as a result, an audio signal processing device that can improve the audio signal processing efficiency can be provided.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The main configuration of the present invention is classified into four patterns as shown in FIGS. In FIG. 16A, the band signal is subjected to band division by the band dividing unit and then the low band signal is corrected, and then each of the high band and the low band is encoded. (B) divides the band of the coding system signal by the band dividing means, further encodes each of the high band and the low band, and then corrects the high band code. (C) also refers to the signal after low-frequency decoding when correcting the low-frequency encoding signal in (A). (D) also refers to the signal after high frequency decoding when correcting the signal of the high frequency encoding system in (B).
[0022]
With the configuration pattern as described above, correction processing can be performed at a lower sampling rate than before band division, and the amount of data processing and memory can be reduced.
[0023]
Based on this, an embodiment of the present invention will be described below with reference to the drawings.
[0024]
(First embodiment)
FIG. 1 is a block diagram showing a main part of the audio signal processing apparatus according to the first embodiment.
[0025]
As shown in FIG. 1, the present apparatus is roughly divided into an encoding system for generating speech encoded data (TX) from a digital speech signal, and speech encoded data (RX) normally stored in a memory 15 as an original. And a reproduction system (decoding system) that decodes the audio signal.
[0026]
The decoding system includes an A / D converter 11 that converts an audio signal input to the microphone 10 into a digital audio signal, a noise canceller 12, an encoder 13, and a multiplexer (data multiplexing unit) 14. On the other hand, the reproduction system includes a speaker 20, a D / A converter 21, a decoder (audio decoding circuit) 22, and a demultiplexer 23. The reproduction system is the same as the conventional one shown in FIG. In the encoding system, the noise canceller 12, the encoder 13, and the multiplexer 14 are usually configured by a digital signal processor (DSP).
[0027]
The encoder 13 is a speech coding circuit that performs speech coding processing on a digital speech signal using a predetermined algorithm (for example, CELP method) to generate speech coded data. The encoder 13 is a wideband speech encoding circuit, and is divided into a low-frequency speech encoder 130 and a high-frequency speech encoder (sometimes referred to as an H coder) 131. The multiplexer 14 converts the speech encoded data generated by the encoder 13 into a form according to the characteristics of the transmission path, modem unit, error correction unit, etc., and outputs it to the memory 15.
[0028]
The noise canceller 12 is controlled to enable or disable the noise suppression function according to a mode signal (HM) for setting the operation mode of the encoder 13. This mode signal (HM) is, for example, a signal output from a CPU of a mobile phone, and determines whether or not to operate the high frequency speech encoder (H coder) 131. Here, for convenience, it is assumed that the H coder 131 is operated when “HM = 1” and the H coder 131 is not operated when “HM = 0”.
[0029]
The noise canceller 12 operates when “HM = 1” and suppresses a noise component with respect to the digital audio signal output from the A / D converter 11. On the other hand, when “HM = 0”, the noise canceller 12 passes the digital audio signal (VS) output from the A / D converter 11 as it is without executing the noise suppression processing.
[0030]
As shown in FIG. 2, the low-frequency speech encoder 130 includes a module 200 including a down-sampling unit 201 and a low-frequency encoder (L coder) 202, and a noise canceller unit 203. The down-sampling unit 201 down-samples the digital audio signal (VS) output from the A / D converter 11 so as to reduce a predetermined number of samples in order to perform low-frequency processing.
[0031]
When “HM = 0”, the noise canceller unit 203 performs noise suppression processing on the digital audio signal (VS) downsampled by the downsampling unit 201 and outputs the result to the L coder 202. On the other hand, when “HM = 1”, the noise canceller unit 203 does not perform noise suppression processing on the digital audio signal (VS) downsampled by the downsampling unit 201 and passes it directly to the L coder 202.
[0032]
(Operation of the first embodiment)
The operation of the coding system according to this embodiment will be described below with reference to FIGS.
[0033]
For example, the mode signal HM is output from the CPU of the mobile phone, and the operation mode (HM = 1/0) of the encoder 13 is set. The A / D converter 11 converts the audio signal input to the microphone 10 into a digital audio signal.
[0034]
Here, it is assumed that the operation mode for operating the high frequency speech coder (H coder) 131 is set (HM = 1). The noise canceller 12 operates when “HM = 1”, suppresses the noise component of the digital audio signal output from the A / D converter 11, and then outputs it to the encoder 13.
[0035]
In the encoder 13, the H coder 131 executes an encoding process for the high frequency audio signal. On the other hand, in the low frequency speech encoder 130, when “HM = 1”, the noise canceller unit 203 does not perform noise suppression processing on the digital speech signal (VS) downsampled by the downsampling unit 201. It passes through the L coder 202 as it is. However, the downsampled digital audio signal (VS) is subjected to noise suppression processing by the noise canceller 12 in the previous stage. Outputs (voice encoded data) of the H coder 131 and the L coder 202 are multiplexed by the multiplexer 14 and stored in the memory 15.
[0036]
On the other hand, it is assumed that an operation mode in which the high frequency speech coder (H coder) 131 is not operated is set (HM = 0). The noise canceller 12 passes the digital audio signal (VS) output from the A / D converter 11 as it is without executing the noise suppression process when “HM = 0”. The H coder 131 is not operating.
[0037]
In the low frequency speech encoder 130, when “HM = 0”, the noise canceller unit 203 performs noise suppression processing on the digital speech signal (VS) downsampled by the downsampling unit 201, and the L coder 202. Output to. The L coder 202 generates low-frequency speech encoded data and outputs it to the multiplexer 14.
[0038]
As described above, according to the present embodiment, when the operation mode of the encoding system does not operate the H coder 131 (HM = 0), the noise canceller 12 provided in the previous stage of the encoder 13 also does not operate. Therefore, the digital speech signal (VS) output from the A / D converter 11 is passed through as it is and is supplied to the low frequency speech encoder 130 of the encoder 13.
[0039]
In the low frequency speech encoder 130, when “HM = 0”, the noise canceller unit 203 is in an operating state, and performs noise suppression processing on the digital speech signal (VS) downsampled by the downsampling unit 201. , Output to the L coder 202. Thereby, the low frequency speech coder 130 generates low frequency speech encoded data from the low frequency digital speech signal in which the noise component is suppressed.
[0040]
Therefore, in the operation mode in which the high frequency speech coder 131 is not operated, the noise canceller 12 provided in the preceding stage of the encoder 13 is deactivated. Therefore, the data processing amount and memory in the DSP necessary for the function of the noise canceller The amount can be reduced. On the other hand, in the low-frequency speech encoder 130, the low-frequency noise canceller unit 203 functions, so that low-frequency speech encoded data can be generated without causing deterioration of speech quality. In this case, the low-frequency noise canceller unit 203 performs noise suppression processing on the down-sampled digital audio signal (the number of samples is reduced). Therefore, the data processing amount and memory amount in the DSP necessary for the function of the noise canceller unit 203 can be relatively reduced as compared with the case where the high frequency noise canceller 12 is functioned.
[0041]
(Second embodiment)
FIG. 3 is a block diagram showing a main part of the audio signal processing apparatus according to the second embodiment.
[0042]
The encoding system of the present embodiment has no high frequency noise canceller, and includes a low frequency speech encoder 300 including a low frequency noise canceller (LNC) and a high frequency audio encoder including a high frequency noise canceller (HNC). The encoder 30 having 301 is provided. Note that the playback system (decoding system) is the same as that of the first embodiment (see FIG. 1), and thus description thereof is omitted.
[0043]
In the encoder 30, the low frequency speech encoder 300 includes a low frequency encoder (L coder) 400, a downsampling unit 401, and a low frequency noise canceller (LNC) 402 as shown in FIG. 4. . The down-sampling unit 401 down-samples the digital audio signal (VS) output from the A / D converter 11 so as to reduce a predetermined number of samples in order to perform low-frequency processing. The LNC 402 executes noise suppression processing for mainly suppressing low-frequency high ambient noise on the down-sampled digital voice signal (VS). The L coder 400 generates low-frequency speech encoded data from the digital speech signal (down-sampled signal) whose noise has been suppressed by the LNC 402 and outputs it to the multiplexer 14.
[0044]
On the other hand, the high frequency speech encoder 301 includes a high frequency encoder (H coder) 500 and a high frequency noise canceller (HNC) 501. Whether or not the H coder 500 operates according to the operation mode (HM = 1/0) set by the mode signal HM is determined. That is, when “HM = 1”, the H coder 500 operates and executes a coding process for the high frequency audio signal of the digital audio signal (VS) output from the A / D converter 11. The HNC 501 executes noise suppression processing that suppresses high ambient noise in a high frequency range. Each output (voice encoded data) of the HNC 501 and the L coder 400 is multiplexed by the multiplexer 14 and stored in the memory 15.
[0045]
Here, when “HM = 0”, the H coder 500 is in a non-operating state. In this operation mode, only the low frequency speech encoder 300 operates, and the speech encoded data that is the output of the L coder 400 is sent to the multiplexer 14.
[0046]
As described above, according to the present embodiment, when the operation mode of the encoding system does not operate the H coder 500 (HM = 0), the high frequency speech encoder 301 is inoperative and the low frequency speech code Only the generator 300 operates. Therefore, when “HM = 0”, only the LNC 402 included in the low-frequency speech encoder 300 operates to execute noise suppression processing on the digital speech signal (VS) downsampled by the downsampling unit 401. . Therefore, in the operation mode in which the high frequency speech encoder 301 is not operated, it is possible to reduce the data processing amount and memory amount in the DSP necessary for the function of the noise canceller.
[0047]
(VAD function)
By the way, as shown in FIG. 4, the low frequency speech encoder 300 has a VAD (Voice Activity Detection) function for determining whether speech input from a digital speech signal (VS) is sound or silence, Is detected, a predetermined flag (VADF) is output to the high frequency speech encoder 301.
[0048]
In the high frequency speech encoder 301, the output of the H coder 500 is speech encoded data mainly relating to the high frequency gain of the speech signal. The HNC 501 is a noise suppression unit that simply cancels noise by processing the speech encoded data. When there is no sound (VADF = 0), the HNC 501 determines that the high-frequency gain is the noise signal (noise) gain, subtracts a value corresponding to the gain from the output signal from the H coder 500, and the result is the multiplexer 14. Output to. On the other hand, when there is sound (VADF = 1), the HNC 501 subtracts the value subtracted when there is no sound (VADF = 0) from the input of the H coder 500 and outputs the result to the multiplexer 14.
[0049]
Here, in the low frequency speech encoder 300, the VAD function is provided inside the L coder 400. Specifically, the L coder 400 includes a VAD unit 50, a voice coder unit 51, and a silent coder unit 52, as shown in FIG. The silent coder unit 52 functions when a silent flag (VADF = 0) is output from the VAD unit 50. Further, the voice coder unit 51 functions when a flag (VADF = 1) indicating voice is output from the VAD unit 50. The VAD unit 50 outputs the flag (VADF = 1/0) to the HNC 501 of the high frequency speech encoder 301.
[0050]
Further, as shown in FIG. 5B, the L coder 400 may include a VAD unit 50, a voiced coder unit 51, a silent coder unit 52, and a switch unit 53. When the flag (VADF = 0) indicating silence is output from the VAD unit 50, the switch unit 53 transfers the digital audio signal (VS) to the silence coder unit 52.
[0051]
Further, the switch unit 53 transfers the digital voice signal (VS) to the voiced coder unit 51 when the flag (VADF = 1) indicating the voice is output from the VAD unit 50. The VAD unit 50 outputs the flag (VADF = 1/0) to the HNC 501 of the high frequency speech encoder 301.
[0052]
(Modification)
FIG. 6 is a block diagram relating to a modification of the second embodiment.
[0053]
In this modification, the high frequency speech encoder 301 controls the operation of the HNC 501 in accordance with, for example, an operation mode signal (MS) from a CPU of a mobile phone. Specifically, the operation mode signal (MS) is, for example, a signal for setting a mode for processing an audio signal for music.
[0054]
In the high frequency speech encoder 301, when the CPU performs high frequency encoding processing on the audio signal for music, the HNC 501 operates in accordance with the operation mode signal (MS = 1), and is effective for music. Performs noise suppression processing.
[0055]
Note that the operation mode signal (MS) set from the CPU is not limited to music, and can be applied to setting various modes.
[0056]
(Third embodiment)
FIG. 7 is a block diagram showing the main part of the speech signal processing apparatus according to the third embodiment, and FIG. 8 shows the configuration of the low frequency speech encoder 172 and the low frequency speech decoder 222 of FIG. FIG.
[0057]
As can be seen from the comparison between FIG. 1 and FIG. 7 and the comparison between FIG. 2 and FIG. 8, the present embodiment replaces the noise canceller with an echo canceller in the first embodiment, and receives speech from the encoder 22 to the wideband echo canceller 16. A speech signal (BR signal) input is added, and an LBR signal input from the low frequency speech decoder 222 to the low frequency speech encoder 172 (echo canceller 204) is added.
[0058]
Either one of the echo cancellers 16 and 204 operates. When the high frequency speech coder 171 operates, only 16 operates, and when 171 does not operate, only 204 operates. Therefore, when the high frequency speech encoder 171 is not operating, it is possible to reduce the data processing amount and memory amount in the DSP necessary for the function of the echo canceller.
[0059]
(Fourth embodiment)
FIG. 9 is a block diagram showing a main part of an audio signal processing apparatus according to the fourth embodiment, and FIG. 10 is a block diagram showing a configuration of the encoder 31 of FIG.
[0060]
As can be seen from the comparison between FIG. 3 and FIG. 9 and the comparison between FIG. 4 and FIG. 10, the present embodiment replaces the noise canceller with an echo canceller in the second embodiment, and The LBR signal input to the high frequency speech encoder 312 (low frequency echo canceller 403) is added, and the high frequency speech decoder 221 to the high frequency speech encoder 313 (high frequency echo canceller 502). The HBR signal input is added.
[0061]
When the high frequency speech encoder 500 is not operating, the high frequency echo canceller 502 is inactive, and only the low frequency echo canceller 403 operates. Therefore, when the high frequency speech encoder 500 is not operating, it is possible to reduce the data processing amount and memory amount in the DSP necessary for the function of the echo canceller.
[0062]
(Modification)
FIG. 11 is a block diagram relating to a modification of the fourth embodiment.
[0063]
In the present modification, the high frequency speech encoder 313 controls the operation of the HEC 502 in accordance with, for example, an operation mode signal (RBT) from a CPU of a mobile phone. Specifically, the operation mode signal (RBT) is a signal for setting a mode for processing a signal that is extremely biased in frequency, such as a telephone push sound, an incoming melody, or an alarm sound.
[0064]
The HEC 502 operates in response to the operation mode signal (RBT = 1), and stops learning the HEC 501 and the LEC 403.
[0065]
Note that the operation mode signal (RBT) set by the CPU is not limited to a push sound, a ringing melody, or an alarm sound, and can be applied when various modes such as an encoding mode are set.
[0066]
Also, embodiments as shown in FIGS. 12 to 15 can be considered by replacing the echo canceller in FIGS. 7 to 10 with a voice switch. 12 and 13 show a combination of a low-frequency voice switch LVS81 and a high-frequency voice switch HVS82, and FIGS. 14 and 15 show a combination of a high-frequency voice switch and a low-frequency voice switch. In either case, when the high frequency speech encoder does not operate, the data processing amount and the memory amount can be reduced by operating only the low frequency voice switch.
[0067]
【The invention's effect】
As described above in detail, according to the present invention, in an audio signal processing apparatus having a wideband audio encoding circuit (encoder) and at least one of a noise canceller, an echo canceller and a voice switch, voice quality is reduced. Without incurring this, it is possible to reduce the amount of data processing and the amount of memory required for the functions of the noise canceller, echo canceller or voice switch in the coding system. Therefore, as a result, it is possible to provide an audio signal processing device that can improve audio signal processing efficiency.
[0068]
Specifically, the noise component or echo contained in the low frequency audio signal component is not performed when the audio encoding processing is performed only on the low frequency audio signal component without performing the audio encoding processing on the high frequency audio signal component. Component suppression processing can be executed. Therefore, for example, in a configuration in which noise or echo suppression processing is executed by a DSP, the amount of data processing and memory required for the function of the noise canceller, echo canceller, or voice switch is reduced in a mode in which high-frequency speech encoding processing is not executed. can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of an audio signal processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a low-frequency speech encoder according to the embodiment.
FIG. 3 is a block diagram showing a main part of an audio signal processing apparatus according to a second embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of an encoder according to the embodiment.
FIG. 5 is an exemplary block diagram for explaining a VAD function according to the embodiment;
FIG. 6 is a block diagram relating to a modified example of the second embodiment.
FIG. 7 is a block diagram showing a main part of an audio signal processing apparatus according to a third embodiment of the present invention.
FIG. 8 is a block diagram showing a configuration of a low-frequency speech encoder according to the embodiment.
FIG. 9 is a block diagram showing a main part of an audio signal processing apparatus according to a fourth embodiment of the present invention.
FIG. 10 is a block diagram showing a configuration of an encoder according to the embodiment.
FIG. 11 is a block diagram relating to a modified example of the fourth embodiment.
FIG. 12 is a block diagram showing a main part of an audio signal processing apparatus according to a fifth embodiment of the present invention.
FIG. 13 is an exemplary block diagram showing the configuration of a low-frequency speech encoder according to the embodiment;
FIG. 14 is a block diagram showing a main part of an audio signal processing apparatus according to a sixth embodiment of the present invention.
FIG. 15 is a block diagram showing a configuration of an encoder according to the embodiment.
FIG. 16 is a block diagram showing the main configuration.
FIG. 17 is a block diagram showing a general configuration of a conventional first audio signal processing apparatus.
FIG. 18 is a block diagram showing a general configuration of a second conventional audio signal processing apparatus.
FIG. 19 is a block diagram showing a general configuration of a third conventional audio signal processing apparatus.
[Explanation of symbols]
1 ... Band division means
2. Correction means
3 ... Low frequency encoding means
4 ... High frequency encoding means
5 ... Low frequency decoding means
10 ... Microphone
11 ... A / D converter
12 ... Noise canceller
13, 17, 30, 32, 71... Encoder (speech encoder)
14 ... Multiplexer
15 ... Memory
16, 72 ... Wide area echo canceller
20 ... Speaker
21 ... D / A converter
22, 24... Decoder (voice decoding circuit)
23 ... Demultiplexer
50 ... VAD
73,82 ... Voice switch for wide area
80 ... High frequency voice switch
81 ... Low-range voice switch
130, 173, 202, 242, 320, 400... Low frequency coder (L coder)
131,171,241,321,500 ... high band encoder (H coder)
172, 300, 310 ... low-range speech encoder
200, 205 ... module
201, 401 ... down-sample part
203 ... Noise canceller
204 ... Low frequency echo canceller
221, 701... High frequency decoder (H decoder)
222, 223, 230, 702... Low band decoder (L decoder)
231 ... Upsample section
301, 311... High frequency speech encoder
402: Low frequency noise canceller (LNC)
403 ... Low frequency echo canceller (LEC)
501 ... High frequency noise canceller (HNC)
502 ... High frequency echo canceller (HEC)

Claims (8)

In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into a high-frequency component signal and a low-frequency component signal;
First encoding means for encoding the high-frequency component signal in response to an operation mode signal instructing encoding of the high-frequency component signal;
Second encoding means for encoding the low-frequency component signal;
First suppression means for suppressing noise components included in the digital audio signal before being encoded by the first and second encoding means;
Second suppression means for suppressing a noise component included in the low-frequency component signal before being encoded by the second encoding means;
When the operation mode signal does not instruct the encoding of the high frequency component signal, the digital encoding signal is encoded with the low frequency component signal by the second encoding means , and the first And a control means for controlling so as not to operate the suppression means. Detection means for detecting that the digital audio signal is a silence signal;
The audio signal processing apparatus according to claim 1, wherein the control unit performs control so that the first suppression unit is not operated when the detection unit detects a silence signal. In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into a high-frequency component signal and a low-frequency component signal;
Encoding the high-frequency component signal in accordance with an operation mode signal instructing encoding of the high-frequency component signal and encoding the low-frequency component signal independently of the operation mode signal Means,
A first suppression unit included in the encoding unit and configured to suppress a noise component included in the high-frequency component signal of the digital audio signal; and a second suppression unit configured to suppress a noise component included in the low-frequency component signal. Suppression means having the following suppression means,
Control means for controlling the first suppression means so that the suppression process for the high-frequency component signal is not executed when the encoding of the high-frequency component signal is not instructed by the operation mode signal; An audio signal processing apparatus comprising the audio signal processing apparatus. In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into a high-frequency component signal and a low-frequency component signal;
First encoding means for encoding the high-frequency component signal in response to an operation mode signal instructing encoding of the high-frequency component signal;
Second encoding means for encoding the low-frequency component signal;
First suppression means for suppressing an echo component that occurs due to a received voice signal and is included in the digital voice signal before being encoded by the first and second encoding means;
Before being encoded by the second encoding means, second suppression means for suppressing an echo component that occurs due to the received voice signal and is included in the low-frequency component signal;
When the operation mode signal does not instruct the encoding of the high frequency component signal, the digital encoding signal is encoded with the low frequency component signal by the second encoding means , and the first And a control means for controlling so as not to operate the suppression means. In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into a high-frequency component signal and a low-frequency component signal;
Encoding the high-frequency component signal in accordance with an operation mode signal instructing encoding of the high-frequency component signal and encoding the low-frequency component signal independently of the operation mode signal Means,
Suppression means for suppressing an echo component generated due to the received voice signal and included in the digital voice signal;
Control means for controlling the suppression means so that the suppression process for the high-frequency component signal is not executed when the operation mode signal does not instruct encoding of the high-frequency component signal. An audio signal processing device. In an audio signal processing method for encoding a digital audio signal,
In response to an operation mode signal indicating whether the high frequency component and low frequency component of the digital audio signal are encoded or only the low frequency component of the digital audio signal is encoded, the operation mode signal is a high frequency component In addition, when instructing the encoding of the low frequency component, the noise component contained in the high frequency component and the low frequency component of the digital audio signal is suppressed, and the operation mode signal indicates the encoding of only the low frequency component. If so, perform a suppression process of only the noise component included in the low frequency component of the digital audio signal,
When the operation mode signal indicates encoding of a high frequency component and a low frequency component, the high frequency component and the low frequency component of the digital audio signal in which the noise component is suppressed are encoded,
The audio signal processing method , wherein the low frequency component of the digital audio signal in which the noise component is suppressed is encoded when the operation mode signal instructs encoding of only the low frequency component . In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into signals of a plurality of bands;
In the digital audio signal for each band divided by the dividing means, encoding means for encoding a signal of at least one band in accordance with an operation mode signal instructing encoding;
Suppression means for suppressing an echo component generated due to the received voice signal and included in the digital voice signal;
An audio signal processing apparatus comprising: control means for controlling the suppression means so as not to execute a suppression process on a signal in a band excluding a band encoded by the encoding means. In an audio signal processing apparatus for encoding a digital audio signal,
Dividing means for dividing the digital audio signal into a high-frequency component signal and a low-frequency component signal;
First encoding means for encoding the high-frequency component signal in response to an operation mode signal instructing encoding of the high-frequency component signal;
Second encoding means for encoding the low-frequency component signal;
First suppression means for suppressing noise components included in the digital audio signal before being encoded by the first and second encoding means;
Second suppression means included in the second encoding means for suppressing noise components included in the low-frequency component signal before being encoded;
When the operation mode signal does not instruct the encoding of the high-frequency component signal, the digital audio signal is encoded by the second encoding means with the low-frequency component signal, and the first Control means for controlling so as not to operate the suppression means of
An audio signal processing apparatus comprising:

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