JP3487158B2 - Audio coding transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voice encoding transmission system by which high quality voice transmission is attained when a transmission network where silence compression is executed is connected to an existing transmission network without silence compression. SOLUTION: This system is provided with a transmission end 10 for processing the sound section of an original voice signal by encoding and also outputting a first voice code generated by silence compression to a first transmission path A, a relay node 20 for outputting to a second transmission path B a second voice code which is generated by interpolating background noises in the silence section of the original voice signal based on the first voice code received from the first transmission path A, and a reception end 30 for processing the second voice code received from the second transmission path B by decoding and reproducing the original voice signal. Here, an internal state at the time of a processing by encoding in the transmission end 10 is made to coincide with the internal state at the time of the processing by decoding in the reception end 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coding transmission system for compressing and transmitting a voice signal with high efficiency, and more particularly to a voice coding transmission system capable of improving voice quality.

[0002]

2. Description of the Related Art Conventionally, a digital transmission technique of a voice signal using a high-efficiency voice encoding technique for encoding a voice signal with high efficiency by eliminating redundant components is used for communication cost of internal communication and international communication. It is widely used in fields where reduction is strongly desired. ITU (Inte
rnational Telecommunications Union) Recommendation G.726 ADPC
Predictive differential coding schemes such as M (Adaptive Differential Pulse Code Modulation) coding schemes and ITU Recommendation G.728 LD-CELP (Low-De
lay Code Excited Linear Prediction: low delay code excitation linear prediction) coding method (see FIG. 21) and ITU recommendation
G.729CS-ACELP (Conjugate-Structure Algebraic-Code-E
xcited Linear Prediction: There is a coding method based on "Analysis-by-Synthesis" as represented by a conjugate structure algebraic code excitation linear prediction) coding method.

For details of these encoding methods, refer to the following documents.・ CCITT Recommendation G.726, 40, 32, 24, 16kbit / s
adaptive differential pulse code modulation (ADPCM)
■ ・ ITU-T Recommendation G.728, ■ Coding of speech a
t 16kbit / s using Low-Delay Code Excited Linear Pre
diction (LD-CELP) ■ ・ ITU-T Recommendation G.729, ■ Coding of speech a
t 8kbit / s using conjugate-structure algebraic-code
-excited linear prediction ■

Here, the predictive differential encoding system is a system in which a current signal is predicted from a past signal sequence, and a differential signal between the prediction parameter and the actual signal is quantized and transmitted. In addition, the encoding method based on "analysis by synthesis"
Using the parameters obtained by analyzing the past and present voice signals, combine multiple patterns of signals as candidates, select the signal pattern that is closest to the input voice from among them, and then select This is a method in which the parameter that is the basis of the synthesized signal thus obtained is quantized as an optimum parameter and transmitted.

Each of these methods is realized by an encoder provided on the transmitting side and a decoder provided on the receiving side. There is no means for the decoder to obtain the information about the parameters of the encoder obtained by so-called forward adaptation based on the current input speech signal component. Therefore, in order for the encoder and the decoder to hold the same parameter, it is necessary to transmit information from the encoder to the decoder. On the other hand, regarding the parameters obtained by so-called backward adaptation based on the past speech signal, both the encoder and the decoder have a common parameter calculation means, so that the encoder and the decoder can operate normally. .

That is, in the predictive differential encoding method, the past signal sequence is shared as the internal state of the encoder and the decoder, so that the audio encoding and decoding operations based on this are realized. In addition, in the coding method based on "analysis by synthesis", the same set of parameters is shared as the internal state of the encoder and the decoder in the transmission and reception obtained by the backward adaptation, so that the speech based on these parameters is shared. Encoding and decoding of is realized. Therefore, it is premised that the decoder executes the audio decoding process while keeping the same internal state as the encoder.
On the contrary, if the past audio signal is different between the transmitting side and the receiving side for some reason, the internal states will not match, and the accuracy of the audio reproduced by the decoding section may not be guaranteed.

On the other hand, in the communication network, there is an increasing demand for multimedia transmission such as transmission of images and computer data in addition to voice represented by a telephone. Asynchronous transfer mode (ATM: Asynchronous Transfer Mode) is used so that such multiple services can be handled comprehensively on the network.
In recent years, a communication method called sfer mode) has been actively introduced. In an ATM transmission network, an information signal (voice, image, etc.) to be transmitted is digitally encoded, the obtained bit string is divided into fixed length blocks called cells, and asynchronously sent to a communication path. This makes it possible to handle information signals having different transmission rates in a multidimensional manner.

Recently, in order to further improve the efficiency as described above, a silence compression technique (a method of discarding a silent portion of a voice signal and transmitting it, which utilizes the features of the ATM network such as asynchronism and variable speed). ) Is becoming more common.
This silence compression technique can reduce the total amount of voice signals sent to the transmission path without deteriorating the voice quality in the voiced section, and enables the more efficient voice transmission by the statistical multiplexing effect.

However, in this silence compression voice transmission system, since there is no voice information transmitted at the time of silence, the operation of the decoder for receiving and decoding the voice code which is the voice signal encoded with high efficiency is silent. Sometimes undefined. Therefore, the backward adaptation described above will not work properly,
An encoder that generates a voice code when transitioning from a silent state (sometimes called a state with no talk spurt) to a voiced state (sometimes called a state with talk spurt “present”) The internal state and the internal state of the decoder that decodes the voice code do not match. Therefore, the decoding unit cannot always correctly decode the audio signal even if the correct high-efficiency code having no transmission path error is given. This phenomenon often appears as an unpleasant noise in the reproduced sound at the receiving end, such as a click sound or an oscillating sound.

FIG. 22 is a block diagram showing the structure of a first voice coding transmission system for solving this problem.
This figure is based on the configuration diagram shown in Japanese Patent Laid-Open No. 2-181552. In this voice transmission system, a transmitting end 60 and a receiving end 70 form a pair. In the state where there is talk spurt, that is, in the voiced section, the transmission end 60 encodes the voice signal by the high-efficiency voice encoder 601 and sends the voice code to the transmission path A via the changeover switch 604. Since the changeover switch 604 of the transmission end 60 is switched so that nothing is transmitted to the transmission line A in the absence of talk spurt, that is, in the silent section, the transmission end 60 outputs a silence-compressed voice code. Become. The voice detector 603 detects the presence / absence of voice in the voice signal and switches the changeover switch 604.

On the other hand, at the receiving end 70, the voice code from the transmission path A is decoded into a voice signal by the decoder 702 and output. While the silence is being compressed, the changeover switch 705 is switched to the pseudo background noise generation unit 706 side, and from the receiving end 70, a pseudo signal imitating the background noise of the speaker (hereinafter referred to as a pseudo background noise signal). ) Is output. The voice / non-voice information extraction unit 707 detects voice / non-voice based on the voice code and switches the changeover switch 705.

In this system, an encoder 60 is provided at the transmitting end 60.
1 has a memory 630 that stores a predetermined internal state, and the receiving end 70 has a memory 730 that stores the same contents.
have. Then, at the time of transition from the silent section of the audio signal where the above-mentioned problem occurs to the sound section,
The voice detector 603 and the presence / absence information extraction unit 70
7 synchronously detects, and at the transmitting end 60, the memory 63
The initial value of the internal state for the encoding process is set from 0 to the encoder 601, and the initial value of the internal state for the decoding process is set from the memory 730 to the decoder 702 at the receiving end 70.

As described above, the timings at which the talk spurt is detected are synchronized with each other at the transmitting end 60 and the receiving end 70, and the internal states of both are reset to the same state at that time. Therefore, the internal states of the encoder 601 and the decoder 702 are always the same in the voiced section of the voice, and it is possible to avoid the generation of abnormal noise at the beginning of the talk spurt.

By using such a technique, it is possible to realize silence compression transmission using high efficiency coding. However, at present, there is already a transmission network constructed so far that does not perform silence compression. These transmission networks are often constructed as infrastructures at a high cost, and it is economically difficult to immediately replace or improve them with silent compression transmission networks. Therefore, when it is desired to construct a large network that covers the range covered by these conventional transmission networks, the network that does not perform silence compression must be coexisted with the network that performs silence compression for the time being.

That is, the coexistence of a network that does not perform silence compression and a network that does not perform silence compression is realized by connecting these two types of networks by relay nodes. As the method, FIG.
There are two methods shown in FIG. These figures illustrate transmission from a network with silence compression to a network without silence compression.

FIG. 23 is a block diagram of a transmission system in which two types of networks are connected in tandem via a relay node. In this figure, constituent elements having the same functions as those in FIG. 22 are assigned the same reference numerals and explanations thereof are omitted. The encoder 601 included in the transmission end 60 of this system performs silence compression and then outputs the voice code to the transmission path A.

The relay node 80 receives the voice code (only the voiced portion) of the transmission end 60 from the transmission path A, and the decoder 802 decodes this. Since the signal at the transmitting end 60 is silence-compressed, the voice signal to be decoded is only the voice part. A pseudo background noise signal is inserted in the silent section of this voice signal, and is encoded again by the encoder 801 and transmitted to the receiving end 70.

Here, the processing of the voice signal between the transmitting end 60 and the relay node 80 is performed by, for example, the silent compression transmission system using the synchronous reset explained in FIG. In this way, since the relay node 80 once decodes and re-encodes, from the standpoint of speech encoding processing, a so-called tandem connection in which two mutually independent transmission paths A and B are connected in series is provided. It will be called form.

On the other hand, FIG. 24 is a block diagram of a transmission system in which two types of networks are connected by a digital 1 link via a relay node. In this figure, constituent elements having the same functions as those in FIG. 23 are assigned the same reference numerals and explanations thereof are omitted.

The silence-compressed voice code sent from the transmission end 60 to the transmission line A is supplemented with the silence code by the relay node 80 and transmitted to the reception end 70 via the transmission line B. The audio signal input to the transmitting end 60 is encoded by the encoder 601.
High efficiency coding. The voice detector 603 detects a sound / silence (presence / absence of talk spurt) based on the voice signal and controls the changeover switch 604. Changeover switch 6
04 is an encoder 601 only when there is a talk spurt.
The voice code from is transmitted to the transmission path A. When there is no talk spurt, the voice code is discarded and nothing is output to the transmission path A. As a result, the silence-compressed voice code is transmitted to the transmission path A.

The relay node 80 receives the silence-compressed voice code transmitted from the transmission end 60 via the transmission path A. The presence / absence information extraction unit 807 constantly monitors the reception status of the voice code from the transmission path A, and controls the changeover switch 804 according to the result. That is, when the voice code is input from the transmission path A, the changeover switch 804 is tilted to the 804b side and the received voice code is relayed to the transmission path B as it is.

On the other hand, if reception of a signal from the transmission path A is not detected (that is, a section determined to be a silent part), there is
The silence information extraction unit 807 switches the changeover switch 804 to the pseudo background noise generation unit 806 side to supplement the signal in the silent section with the pseudo background noise signal. In addition, the delay device 209 has the transmission path A for the processing time in the presence / absence information extraction unit 807.
The voice code from the voice code is delayed and the changeover switch 804 is operated in synchronization with the input of the voice code.

At the receiving end 70, the decoder 702 is connected to the transmission line B.
The audio code from is decoded and the audio signal is extracted. A pseudo signal is inserted at the relay node 80 in the signal in the silent section, so that it seems that a continuous voice signal is input to the receiving end 70.

In this way, the relay node 80 merely executes switching depending on the presence or absence of voice. For this reason, the voice code transmitted to the receiving end 70 is nothing but the one transmitted from the transmitting end 60 for the voiced segment which is the main information, although the silent node is interpolated in the relay node. Then, the transmission lines A and B
Since the signal passing between the two is relayed to the other party's network without being processed as a digital signal, this inter-network transmission method is generally called a digital 1 link.

[0025]

However, the above-mentioned tandem connection and the connection of the transmission lines A and B by the digital 1 link have the following problems. That is,
In the tandem connection, the voice code compressed silently at the transmitting end 60 is decoded into a voice signal at the relay node 80, a noise signal is inserted, and then the voice signal is encoded again and transmitted to the transmission line B. Therefore, the internal state of the encoder 801 of the relay node 80 and the internal state of the decoder 702 of the receiving end 70 always match, and the above-described abnormal noise is prevented.

However, in the relay node 80, since the voice code is decoded and then encoded again, the voice signal input to the transmission end is output twice from the reception end. Encoding / decoding processing will be performed. Therefore, there is a problem that the quantization error accumulates and the quality of the audio signal output from the receiving end 70 deteriorates. This voice quality degradation is due to the high bit rate (l6kbit
/ s or more), it is hardly noticeable, but the higher the compression rate, the more noticeable the deterioration tendency.
In particular, voice transmission systems have low bit rates,
This deterioration of voice quality cannot be ignored.

On the other hand, in the case of connection by the digital 1-link, the situation is completely opposite. In this case, the voice code in the sound part transmitted to the receiving end 70 is the same as the voice code generated in the transmitting end 60, so that the quality deterioration of the voice signal due to the accumulation of the quantization error is prevented. But,
The internal state of the encoder 601 of the transmitting end 60 and the internal state of the decoder 702 of the receiving end 70 generally do not match at the timing of transition from the silent state to the voiced state.

That is, even though the voice code itself is the same, the internal state is different in the encoding / decoding process.
The audio signal decoded by the decoder 702 is different from the signal intended by the encoder 601, and there is a problem that the above-mentioned abnormal noise may occur. The generation of this abnormal sound not only makes the receiver uncomfortable, but also usually occurs at the beginning of the talk spurt, which causes a problem that the understanding level of the call contents is significantly lowered.

Due to the above problems, it has been difficult in the past to connect a silence compression transmission network to this transmission network without improving the existing voice communication system on the transmission network side which does not perform silence compression.

The present invention solves such a problem and enables high-quality voice transmission in a voice coding transmission system in which a transmission network in which silence compression is performed is connected to an existing transmission network in which silence compression is not performed. It is an object of the present invention to provide a speech coded transmission system that operates.

[0031]

According to a first aspect of the present invention, there is provided a voice coded transmission system, wherein a voiced section of an original voice signal is coded and a first voice code generated by silence compression is first transmitted. The second voice code generated by interpolating the background noise in the silent section of the original voice signal based on the transmission end output to the channel and the first voice code received from the first transmission line. In a voice coding transmission system including a relay node for outputting to a transmission line and a receiving end for decoding a second voice code received from a second transmission line to reproduce an original voice signal, the transmitting end has a background. A transmitting-side background noise generating means for generating a first pseudo signal simulating noise, and a first part for a silent section of the original speech signal.
Of the transmission side background noise insertion means for inserting the pseudo signal of, the transmission side encoding means for encoding the voice signal obtained by the transmission side background noise insertion means, and the voice code encoded by the transmission side encoding means. And a transmission side voice code generation means for compressing the silent section to generate a first voice code, and the relay node, a relay side decoding means for decoding the first voice code,
Relay-side background noise generation means for generating a second pseudo signal imitating background noise, and relay-side background noise insertion for inserting the second pseudo signal in the silent section of the voice signal decoded by the relay-side decoding means. Means, the relay side encoding means for encoding the voice signal obtained by the relay side background noise inserting means, and the voice code encoded by the relay side encoding means are inserted into the silent section of the first voice code. And a relay side voice code generating means for generating a second voice code.

According to a second aspect of the present invention, there is provided a voice coding / transmission system in which a voice end section of an original voice signal is coded and a first voice code generated by silence compression is outputted to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that reproduces an original voice signal by decoding a second voice code received from a second transmission path, the transmitting end has a first noise imitating background noise. A background noise generating means for generating a pseudo signal, a background noise inserting means for inserting a first pseudo signal in a silent section of an original speech signal, and a voice signal obtained by the background noise inserting means for transmitting. Transmitting side encoding means for encoding and transmitting side code And a transmitting side voice code generating means for compressing a silent section of the voice code encoded by the encoding means to generate a first voice code, wherein the relay node is a relay side for decoding the first voice code. Decoding means, relay side background noise generation means for generating a second pseudo signal simulating background noise,
The relay side encoding means for encoding the second pseudo signal and the pseudo code encoded by the relay side encoding means are inserted into the silent section of the first voice code to generate the second voice code. The relay side speech code generating means is provided, and the relay side encoding means inputs the internal parameter of the relay side decoding means and holds the internal state equivalent to that of the relay side decoding means by using this internal parameter. It is characterized by being

According to a third aspect of the present invention, there is provided a voice encoding / transmission system in which a voice end section of an original voice signal is encoded and a first voice code generated by performing silence compression is outputted to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that reproduces an original voice signal by decoding a second voice code received from a second transmission path, the transmitting end has a first noise imitating background noise. A background noise generating means for transmitting, a transmitter background noise inserting means for inserting the first pseudo signal in a silent section of the original voice signal, and a voice signal obtained by the background noise transmitting means for transmitting. Transmitting side encoding means for encoding and transmitting side code And a transmitting side voice code generating means for compressing a silent section of the voice code encoded by the converting means to generate a first voice code, and the relay node outputs a second pseudo signal simulating background noise. The relay-side background noise generating means for generating, the interpolation signal generating means for decoding the first speech code and the second pseudo signal, and the pseudo code encoded by the interpolation signal generating means are And a relay side voice code generating means for generating a second voice code by inserting the voice signal into a silent section of the voice code of the interpolation code generating means, and the interpolation signal generating means holds an internal state common to the decoding process and the encoding process. It is characterized by doing.

According to a fourth aspect of the present invention, there is provided a voice coding / transmission system in which a voice end section of an original voice signal is coded and a first voice code generated by silence compression is outputted to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that reproduces an original voice signal by decoding a second voice code received from a second transmission path, the transmitting end has a first noise imitating background noise. Background noise generation means for generating the pseudo code of, the transmission side decoding means for decoding the first pseudo code, and the pseudo signal decoded by the transmission side decoding means to the silent section of the original speech signal. Transmitting side background noise inserting means to be inserted,
A first voice code is generated by compressing a voice coding section that encodes the voice signal obtained by the background noise inserting section and a silent section of the voice code encoded by the transmitter side coding means. And a relay side background noise generating means for generating a second pseudo code imitating background noise, and a second pseudo code in a silent section of the first voice code. And a relay side voice code generating means for generating a second voice code, and the transmitting side decoding means inputs the voice code encoded by the transmitting side encoding means, and outputs the voiced section. Is characterized by decoding this voice code and decoding the second pseudo code for the silent section.

According to a fifth aspect of the present invention, there is provided a voice coding transmission system in which a voice end section of an original voice signal is coded, and a first voice code generated by silence compression is outputted to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that reproduces an original voice signal by decoding a second voice code received from a second transmission path, the transmitting end has a first noise imitating background noise. Of the transmission side background noise generating means for generating the pseudo code, the transmission side decoding means for decoding the first pseudo code, the transmission side encoding means for encoding the original speech signal, and the transmission side encoding means. The first voice is generated by compressing the silent section of the encoded voice code. And a relay side background noise generating means for generating a second pseudo code imitating background noise, and a second side in a silent section of the first voice code. And a relay side voice code generating means for generating a second voice code by inserting the pseudo code of
The transmitting side encoding means is characterized in that it receives an internal parameter of the transmitting side decoding means and holds an internal state equivalent to that of the transmitting side decoding means by using this internal parameter.

According to a sixth aspect of the present invention, there is provided a voice coding / transmission system in which a voice end section of an original voice signal is coded and a first voice code generated by performing silence compression is outputted to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that reproduces an original voice signal by decoding a second voice code received from a second transmission path, the transmitting end has a first noise imitating background noise. Background noise generation means for generating a pseudo signal of, a transmission side encoding means for encoding an original voice signal while maintaining an internal state based on the first pseudo signal, and a transmission side encoding means. The first voice code is obtained by compressing the silent section of the voice code. The relay node includes a transmission side voice code generating means for generating the second pseudo code, and a relay side background noise generating means for generating a second pseudo code imitating background noise, and a second pseudo code in a silent section of the first voice code. And a relay side voice code generating means for inserting a code to generate a second voice code.

According to a seventh aspect of the present invention, there is provided a voice encoding / transmission system in which a voice end section of an original voice signal is encoded and a first voice code generated by performing silence compression is output to a first transmission line. And a relay for outputting to the second transmission path the second speech code generated by interpolating the background noise in the silent section of the original speech signal based on the first speech code received from the first transmission path. In a voice coding transmission system including a node and a receiving end that decodes a second voice code received from a second transmission line to reproduce an original voice signal, a transmitting end encodes the original voice signal. A transmitting side encoding means and a transmitting side speech code generating means for compressing a silent section of the speech code encoded by the transmitting side encoding means to generate a first speech code,
The relay node decodes the first voice code to generate a voice signal, a relay side decoding unit, a relay side background noise generating unit to generate a pseudo signal simulating background noise, and a relay side decoding unit. A relay side background noise inserting means for inserting a pseudo signal into a silence section of the voice signal, a relay side encoding means for encoding the voice signal obtained by the relay side background noise inserting means, and a relay side encoding means. The encoded speech code,
It is characterized by comprising a relay side voice code generation means for generating a second voice code by inserting the first voice code into a silent period and a transition period immediately after switching from a voice to a voice.

In the eighth aspect, the relay node further comprises a timer for counting the transition section, and the relay side voice code generation means determines the end timing of the transition section based on the count value of the timer. Characterize.

In the ninth aspect, the relay node further comprises a comparison means for comparing the internal state of the relay side decoding means and the internal state of the relay side encoding means, and the relay side voice code generation means includes the comparison means. It is characterized in that the end timing of the transition section is determined based on the comparison result.

In the tenth aspect, the relay node includes a timer for counting the transition section, a comparison means for comparing the internal state of the relay side decoding means and the internal state of the relay side encoding means, a count value of the timer, and The relay side voice code generation means determines the end timing of the transition section based on the determination result of the determination means. It is characterized by

In the eleventh aspect, the transmitting-side background noise generating means and the relay-side background noise generating means generate a digital signal imitating background noise in a silent section as pseudo voice.

In the twelfth aspect, the transmitting-side background noise generating means and the relay-side background noise generating means are memories that store predetermined digital signals.

In the thirteenth aspect, the transmission side background noise generation means and the relay side background noise generation means are random signal generators.

[0044] In Claim 14, further comprising a synchronization signal transmitting means for transmitting a synchronization signal indicating the start of the silent section of the original voice signal from the transmission end to the relay node, the relay node receiving the synchronization signal and transmitting the synchronization signal. The background noise generating means and the relay side background noise generating means are synchronized.

In the fifteenth aspect, the transmitting end further comprises an identification pattern generating means for generating an identification pattern to be superimposed on the silent section of the original voice signal, and the relay node recognizes the identification pattern to generate the transmission side background noise. The means and the background noise generating means on the relay side are synchronized with each other.

The speech coded transmission system according to claim 16 is
A transmitting end for encoding a voiced section of an original voice signal and outputting a first voice code generated by performing silence compression to a first transmission line, and a first voice received from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise in a silent section of the original voice signal to a second transmission line based on the code, and a second relay node that receives the second voice code from the second transmission line. In a voice coding transmission system including a receiving end that decodes a voice code to reproduce an original voice signal, the transmitting end has a transmitting side parameter generating means for generating a first parameter signal for generating pseudo background noise, The transmitting side encoding means for encoding the original speech signal while maintaining the internal state based on the first parameter signal, and the silence section of the speech code encoded by the transmitting side encoding means are compressed to Transmitter voice code generator that generates voice code The relay node includes a relay-side parameter generating unit that generates a second parameter signal for generating pseudo background noise, a relay-side encoding unit that generates a pseudo code based on the second parameter signal, and And a relay side voice code generation means for generating a second voice code by inserting a pseudo code into a silent section of the first voice code.

According to a seventeenth aspect, the transmitting side parameter generating means and the relay side parameter generating means are memories that store predetermined digital signals.

In the eighteenth aspect, the transmitting-side parameter generating means and the relay-side parameter generating means are random code generators.

In the nineteenth aspect, the transmitting end further comprises a synchronizing signal transmitting means for transmitting a synchronizing signal indicating the start of the silent section of the original voice signal, and the relay node receives the synchronizing signal and generates a transmitting side parameter. The means and the relay side parameter generating means are synchronized.

In the twentieth aspect, the transmitting end further comprises an identification pattern generating means for generating an identification pattern to be superimposed on the silent section of the original voice signal, and the relay node recognizes the identification pattern and the transmitting side parameter generating means. And the relay side parameter generating means are synchronized.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a voice coded transmission system according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1. FIG. 1 is a block diagram showing the configuration of the speech coded transmission system according to the first embodiment. In FIG. 1, reference numeral 10 is a transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by silence compression to a transmission path A (first transmission path), and 20 is a transmission end. The second voice code generated by interpolating the voice code corresponding to the silent section of the original voice signal based on the first voice code received from the path A is output to the transmission path B (second transmission path). The relay node 30 is a receiving end for decoding the second voice code received from the transmission path B and reproducing the original voice signal.

Further, 101 is an encoder (transmission side encoding means) for highly efficient encoding the input voice signal based on a predetermined algorithm, and 103 is a control signal 1A for controlling the operation mode of the transmission end 1. Voice detector for outputting 10
4 compresses the voice code encoded by the encoder 101,
A changeover switch (transmission side voice code generation means) for generating a first voice code, and a changeover switch (transmission side background noise insertion means) 105 for inserting a background noise signal (first pseudo signal) in a silent section of the original voice signal. ), 106 is a pseudo background noise generation unit (transmission side background noise generation means) that generates this background noise signal in a pseudo manner.

Further, 201 is a coder (relay side coding means) for high-efficiency coding the input speech signal based on a predetermined algorithm, and 202 is decoding the first speech code sent from the transmitting end 10. A decoder (relay side decoding means) 204 for converting a background noise signal (second pseudo signal) into a silent section of the voice signal decoded by the decoder 202 (relay side background noise inserting means) ), 206 is a pseudo background noise generation unit (relay side background noise generation means) that generates this background noise signal in a pseudo manner.

Furthermore, 207 is a presence / absence information extraction unit that constantly monitors the reception status of the voice code from the transmission path A and outputs a control signal according to the result, 209 is a delay device, 2
Reference numeral 14 is a changeover switch (relay side voice code generating means) for inserting the voice code encoded by the encoder 201 into the silent segment of the first voice code to generate the second voice code, and 205 is the encoder 201. A changeover switch for interpolating the silent section of the first voice code by using the voice code encoded in 1., and 302 is a decoder for decoding the second voice code.

The pseudo background noise generators 106 and 206
It is preferable that a digital signal imitating background noise in a silent section is generated as a pseudo voice.

Next, the operation of this voice transmission system will be described. The transmitting end 10 generates a voice code by efficiently encoding the original voice signal. This voice code is sent to the transmission line A in the voiced section and is not sent to the transmission line A in the silent section according to the determination result of the voice detector 103. In this way, so-called silence compression is performed at the transmitting end 10,
The transmission path A is a transmission path of a voice code in which silence is compressed. On the other hand, the transmission line B to which the receiving end 30 is connected is a transmission line through which a voice code that has not been silence-compressed is transmitted. And
The relay node 20 connects these two transmission lines, receives the voice code from the transmission end 10 from the transmission line A, inserts the pseudo voice code in the silent section, and outputs the pseudo voice code to the transmission line B. The receiving end 30 decodes this voice code and outputs a voice signal.

At the transmitting end 10, the voice detector 103
Identifies the voiced section / silent section based on the input original audio signal, and outputs a control signal 1A for controlling the operation mode of the transmitting end 10 based on the result. When the voice detector 103 determines that there is "sound," the changeover switch 105 is set to the 105B side and the changeover switch 104 is set to 104
Defeat to the B side. As a result, the original audio signal input to the transmission end 10 is input to the encoder 101, is subjected to high-efficiency encoding, and is then output to the transmission path A via the changeover switch 104.

On the other hand, when the voice detector 103 determines that there is "silence", the changeover switch 105 is turned to the 105A side and the changeover switch 104 is turned to the 104A side. As a result, the pseudo background noise signal output from the pseudo background noise generation unit 106 is input to the encoder 101. However, since the signal in which the pseudo background noise signal output from the encoder 101 is encoded is cut off by the changeover switch 104, nothing is output to the transmission path A.

Here, the pseudo background noise generator 106 will be described. At the timing when the determination of the voice detector 103 transits from “voiced” to “silent”, the voice detector 103
Outputs an initialization signal 1B for controlling the initialization of the pseudo background noise generation unit 106. Pseudo background noise generator 10
The initialization signal 1B is input to 6, and the pseudo background noise generator 106 resets the internal state at the input timing of the initialization signal 1B. This operation is indispensable for realizing the operation synchronized with the pseudo background noise generation unit 206 in the relay node 20 described below.

In the relay node 20, the first node transmitted from the transmission end 10 after being silence-compressed and transmitted through the transmission line A
Receive the voice code of. The presence / absence information extraction unit 207
The reception status of the first voice code from the transmission path A is constantly monitored, and the changeover switches 204, 205, 2 are selected according to the result.
The control signal 2A for controlling 14 is output. That is,
When a voice code is input from the transmission line A, it is determined that the voiced section is present, and the changeover switch 204 is set to the 204B side, the changeover switch 205 is set to the 205B side, and the changeover switch 214 is set to two.
Defeat each to 14B side.

The first voice code received by the relay node 20 is relayed to the transmission line B as it is via the delay unit 209 and the switch 214. The first voice code is also given to the decoder 202 via the switch 205.
The decoder 202 executes a decoding process based on the input first voice code to decode a voice signal. The decoded audio signal is supplied to the encoder 201 via the changeover switch 204. The encoder 201 executes an encoding process based on the input audio signal.

Here, there is a difference between the encoder 101 of the transmitting end 10 and the encoder 201 of the relay node 20 in which the input signals are the original speech signal and the decoded speech signal decoded by the decoder 202, respectively. However, the nature of speech is very similar. Therefore, the internal state of the encoder 101 of the transmission end 10 and the internal state of the encoder 201 of the relay node 20, which correspond to the digitized nature of the voice signal, are:
It is a very close approximation.

On the other hand, in the presence / absence information extraction unit 207, when the reception of the signal from the transmission path A is not detected, that is, in the section judged as "silence", the changeover switch 204 is changed over to the 204A side. Switch 205 to 2
The selector switch 214 is turned to the side of 05A and the switch 214 is turned to the side of 214A.

The output signal of the pseudo background noise generator 206 is
It is input to the encoder 201 via the switch 204.
The encoder 201 performs an encoding process based on the input pseudo background noise signal and outputs a pseudo background noise code. The pseudo background noise code output from the encoder 201 is sent to the transmission line B via the switch 214.

By this series of operations, the signal in the silent section can be supplemented with the pseudo background noise signal. Here, the delay device 209 delays the voice code received from the transmission path A and transmitted to the transmission path B by the time required for the processing in the voice / non-voice information extraction unit 207 and the processing in the encoder 201. This delay operation realizes synchronization between the voice code of the voiced section output from the delay unit 209 and the pseudo background noise code output from the encoder 201.

At the timing when the judgment of the sound / silence information extraction unit 207 transits from “sound” to “silence”, the sound / silence information extraction unit 207 controls the initialization of the pseudo background noise generation unit 206. An initialization signal 2B for outputting is output. The initialization signal 2B is input to the pseudo background noise generation unit 206, and the pseudo background noise generation unit 206 resets the internal state at the input timing of the initialization signal 2B.

The pseudo background noise generation unit 206 realizes the same operation as the pseudo background noise generation unit 106 of the transmission end 10. The pseudo background noise generation of the transmission end 10 is also performed in the above initialization operation. It is the same as the unit 106. The initialization operation is performed in synchronization with the presence / absence of a voice signal input from the transmission path A, and by extension, with the determination signal of the voice detector 103 of the transmitting end 10, the encoder 101 of the transmitting end 10 and the relay node 2
The same pseudo background noise signal is supplied at the same timing as that of the encoder 201 of 0.

Further, in the voiced section, the internal state of the encoder 101 at the transmitting end 10 and the encoder 20 at the relay node 20
Since the internal state of 1 is almost the same, the pseudo background noise codes output from these encoders 101 and 201 can take extremely approximate values in the silent section.

The pseudo background noise code output from the encoder 201 passes through the changeover switch 205 to the decoder 2
02 is also supplied. The decoder 202 executes a decoding process based on the input pseudo background noise code. By this operation, the internal state of the encoder 101 of the transmitting end 10 and the internal state of the decoder 202 of the relay node 20 are always kept the same. Therefore, it is determined again as "voiced" and the decoder 20
Even if the voice code from the transmission path A is input to 2, the internal state is the same in transmission and reception, so that the voice can be decoded normally.

The receiving end 30 receives the second voice code which is continuously transmitted from the relay node 20 via the transmission line B and in which the silent section is interpolated by the pseudo background noise code. The decoder 302 performs a decoding process based on the input second voice code, decodes the voice signal, and outputs the voice signal from the receiving end 30.

Since the second voice code input to the receiving end 30 is the output of the encoder 101 of the transmitting end 10 in the voiced section, the encoder 101 of the transmitting end 10 is in the voiced section. And the internal state of the decoder 302 of the receiving end 30 match. In the silent section, the receiving end 30
Since the second voice code input to the relay node 20 is the output of the encoder 201 of the relay node 20,
The internal state of 01 matches the internal state of the decoder 302 of the receiving end 30. As described above, even in the silent section, the internal state of the encoder 101 of the transmitting end 10 and the relay node 2
Since it matches the internal state of the encoder 201 of 0,
From the appearance of the receiving end 30, it is possible to obtain an effect as if the receiving end 30 were directly receiving a voice code that was not subjected to silence compression.

As described above, the encoder 10 of the transmitting end 10
Since the internal state of 1 and the internal state of the decoder 302 of the receiving end 30 are always matched, it is possible to avoid the possibility that an offensive voice is decoded due to the mismatch of the internal states.

Embodiment 2. Next, a second embodiment will be described with reference to FIG. In the present embodiment, the relay node 20 in the voice coding transmission system of the first embodiment is improved to be a relay node 21. In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

The relay node 21 receives the first voice code transmitted from the transmission end 10 after being silence-compressed and transmitted through the transmission path A. The presence / absence information extraction unit 207 constantly monitors the reception status of the voice code from the transmission path A, and controls the changeover switch 214 according to the result of the control signal 2A.
Is output.

That is, when a voice code is input from the transmission path A, it is determined to be a voiced section and the changeover switch 214 is set to 2
Defeat to the 14B side. The first voice code received by the relay node 21 is relayed to the transmission line B as it is via the switch 214. In addition, the first speech code is simultaneously decoded by the decoder 2
02 is also supplied. The decoder 202 executes a decoding process based on the input first voice code.

Here, since the encoder 101 of the transmission end 10 and the decoder 202 of the relay node 21 perform adaptive processing based on the same voice code for both voiced parts, the transmission end encoder 101. Internal state of the relay encoder 20
The internal state of 1 is kept at a matched value.

Next, at the timing when the judgment of the sound / silence information extraction unit 207 transits from “sound” to “silence”, the sound / silence information extraction unit 207 controls the initialization of the pseudo background noise generation unit 206. Output an initialization signal 2B. The pseudo background noise generation unit 206 resets the internal state at the timing of receiving the initialization signal 2B and starts transmitting the pseudo background noise signal.

The pseudo background noise generation unit 206 realizes the same operation as the pseudo background noise generation unit 106 of the transmission end 10, and the above initialization operation is also performed by the transmission end 1.
It is the same as the pseudo background noise generation unit 106 of 0. The initialization operation is performed in synchronization with the presence / absence of a voice signal input from the transmission path A, and further, in synchronization with the determination signal of the voice detector 103 of the transmission end 10. Therefore, the encoder 101 of the transmission end 10 and the relay node 2
The same pseudo background noise signal can be supplied to one encoder 201 at the same timing.

At the same time, the initialization signal 2B is also supplied to the encoder 201 and the decoder 202. The decoder 202 that has received the initialization signal 2B sends the internal parameters to the encoder 201 and stops the operation. The encoder 201 receives internal parameters from the decoder 202 by the initialization signal 2B,
Based on this, the encoding process of the pseudo background noise signal supplied from the pseudo background noise generation unit 206 is started.

Here, in the voiced section, the internal state matched between the encoder 101 of the transmitting end 10 and the decoder 202 of the relay node 21 is directly inherited by the encoder 201 of the relay node 21, Even though the information is not directly exchanged with each other, the pseudo background noise codes output from both the encoder 101 of the transmitting end 10 and the encoder 201 of the relay node 21 match in the silent section.

In the section where the signal from the transmission path A is determined to be "silent" in the presence / absence information extraction unit 207, the changeover switch 214 is tilted to the 214A side. The pseudo background noise code output from the encoder 201 in response to the output signal of the pseudo background noise generation unit 206 is sent to the transmission path A via the switch 214. By this series of operations,
The signal in the silent section can be supplemented with a pseudo background noise signal.

Finally, the presence / absence is determined at the timing when the determination of the presence / absence information extraction unit 207 transits from "silence" to "voice".
The silence information extraction unit 207 outputs the control signal 2C.
The encoder 201 that receives the control signal 2C sends the internal parameter to the decoder 202 and stops the operation. Decoder 2
02 receives the internal parameter from the encoder 201 by the control signal 2C, and based on this, starts the decoding process of the first voice code received from the transmission path A. By a series of these operations, the encoder 101 of the transmitting end 10 in the silent section.
Although the internal state is kept the same even though no information is exchanged between the decoder 202 of the relay node 21 and the decoder 202 of the relay node 21, the decoding process can be normally restarted.

The receiving end 30 receives the second voice code which is continuously transmitted from the relay node 21 via the transmission path B and in which the silent section is interpolated by the pseudo background noise code. The decoder 302 performs a decoding process based on the input second voice code, decodes the voice signal, and outputs the voice signal from the receiving end 30.

Since the second speech code input to the receiving end 30 is the output of the encoder 101 of the transmitting end 10 in the voiced section, the encoder 101 of the transmitting end 10 is in the voiced section. And the internal state of the decoder 302 of the receiving end 30 match. In the silent section, the receiving end 30
Since the second speech code input to the relay node 21 is the output of the encoder 201 of the relay node 21,
The internal state of 1 and the internal state of the decoder 302 of the receiving end 30 match.

As described above, since the internal state of the encoder 101 of the transmitting end 10 and the internal state of the encoder 201 of the relay node 21 are made to coincide with each other even in the silent period, it is apparent from the receiving end 30. In addition, it is possible to obtain an effect as if the voice code which is not silence-compressed is directly received from the transmitting end 10.

As described above, the encoder 10 of the transmitting end 10
Since the internal state of 1 and the internal state of the decoder 302 of the receiving end 30 are always matched, the risk of decoding annoying voice due to the mismatch of the internal states is avoided.
Further, in the relay node 21, the encoder 201 operates only in the silent section and the decoder 202 operates only in the voiced section, so that these do not execute the processing at the same time, and the load on the processor is reduced. Cost reduction and power consumption reduction are realized by reduction.

Third Embodiment Next, a third embodiment will be described with reference to FIGS. The present embodiment is the same as the voice coding transmission system according to the first embodiment.
The relay node 20 is improved to form a relay node 22. Here, 208 is an interpolation signal generator (interpolation signal generation means) that encodes the first voice code sent from the transmission end 10 and also encodes the background noise signal (second pseudo signal). In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

The relay node 22 receives the first voice code transmitted from the transmission end 10 after being silence-compressed and transmitted via the transmission path A. The presence / absence information extraction unit 207 constantly monitors the reception status of the voice code from the transmission path A, and controls the changeover switch 214 according to the result of the control signal 2A.
Is output. An initialization signal for controlling the initialization of the pseudo background noise generation unit 206 from the presence / non-voice information extraction unit 207 at the timing when the determination of the presence / non-voice information extraction unit 207 transits from “voiced” to “silence”. Output 2B.

The pseudo background noise generator 206 resets the internal state at the timing of receiving the initialization signal 2B and starts transmitting the pseudo background noise signal. The pseudo background noise generation unit 206 realizes the same operation as the pseudo background noise generation unit 106 of the transmission end 10, and the initialization operation is also performed in the pseudo background noise generation unit 1 of the transmission end 10.
It is the same as 06. Since the initialization operation is performed in synchronization with the presence / absence of an audio signal input from the transmission path A, and by extension, with the determination signal of the transmitting end audio detector 103, the encoder 10 of the transmitting end 10 is operated.
1 and the interpolation signal generator 208 are supplied with the same pseudo background noise signal at the same timing. The operation up to this point is almost the same as in the first embodiment.

Next, a specific structure of the interpolation signal generator 208 will be described with reference to FIG. The interpolated signal generator 208 shown in FIG.
It applies Recommendation G.728. As can be seen by comparing FIG. 4 and FIG. 21, this is an encoder based on ITU Recommendation G.728 with changeover switches 421, 422, 423 added.

ITU Recommendation G.728 LD-CELP system and G.729 CS standard
-In the speech coding method based on "analysis by synthesis" typified by the ACELP method, in order to select the optimum speech code, decoding processing is performed on all the possible speech code candidates, and these are input. The synthesized signal that is closest to the input speech signal is selected, and the speech code that is the basis of the synthesized signal is transmitted to the decoder as the optimum code. The encoder of this system has a function corresponding to a decoder usually called a local decoder in order to realize this decoding process. The functional block 420 shown in FIG. 4 is a portion corresponding to the local decoder.

In the section where the signal from the transmission path A is determined to be "voiced" by the voice / non-voice information extraction unit 207, the changeover switch 421 is switched to 421 by the control signal 2A.
The changeover switch 422 is turned to the 422B side and the changeover switch 423 is turned to the 423B side on the B side. At this time, the local decoder unit 420 receives the signal from the transmission path A and performs a normal decoding operation.

The purpose of this operation is the backward type gain adaptation section 410 and the backward type synthesis filter adaptation section 4.
11 is operated to keep the internal states of the gain multiplier 404 and the synthesis filter 405 consistent with the internal states of the transmission end encoder 101, not to obtain a decoded speech signal.

Here, the output path of the synthesis filter 405,
That is, since the output path of the decoded audio signal is cut off by the switch 423, the output of the local decoder 420 is not referred to by other functional blocks. Further, in the interpolation signal generator 208, functional blocks other than the local decoder 420, that is, the PCM decompression unit 401,
The vector buffer unit 402, the adder 406, the perceptual weighting filter 407, and the least square error search unit 408 are
Holds stopped because there is no signal to input.

In the section where the signal from the transmission path A is determined to be a silent section by the sound / silence information extraction unit 207, the changeover switch 421 is switched to 421 by the control signal 2A.
The changeover switch 422 is turned to the 422A side and the changeover switch 423 is turned to the 423A side to the A side. At this time, the structure of the interpolation signal generator 208 is exactly the same as the structure of the encoder. Its operation is also exactly the same as that of the encoder.
That is, the pseudo background noise signal output from the pseudo background noise generation unit 206 is used as an input, and the closest synthesized signal is selected from the candidates of the synthesized speech signals synthesized by the local decoder, and the background that is the source of the synthesized signal is selected. The noise code is output as the optimum code from the interpolation signal generator 208.

Here, in the voiced section, the gain multiplier 40
4 and the synthesizing filter 405 match the internal states of the transmitting end encoder 101, and the signal input from the pseudo background noise generation unit 206 is the pseudo background noise of the transmitting end 10 even in the silent section. Since it is exactly the same as the generation unit 106, the pseudo background noise code output from the interpolation signal generator 208 is output from the transmission end encoder 101 (however, it is not output to the transmission path A by the changeover switch 104). It is exactly the same as the random code. Through these series of operations, the transmitting end encoder 101 in the silent section.
And the interpolating signal generator 208 does not directly exchange signals, but the internal states are always kept in agreement.

At the receiving end 30, the second voice code which is continuously transmitted from the relay node 22 via the transmission path B and in which the silent section is interpolated by the pseudo background noise code is received. The decoder 302 performs a decoding process based on the input second voice code, decodes the voice signal, and outputs the voice signal from the receiving end 30.

Since the second speech code input to the receiving end 30 is the output of the encoder 101 of the transmitting end 10 in the voiced section, the encoder 101 of the transmitting end 10 is in the voiced section. And the internal state of the decoder 302 of the receiving end 30 match. In the silent section, the receiving end 3
The second voice code input to 0 is the interpolation signal generator 208.
, The internal state of the interpolation signal generator 208 and the internal state of the receiving end decoder 302 match.

As described above, even in the silent section, the internal state of the transmitting end encoder 101 and the interpolation signal generator 2
Since the internal states of 08 are matched, it is possible to obtain an effect as if the voice from the receiving end 30 was directly received from the transmitting end 10 as if the uncompressed voice code was directly received.

As described above, since the internal state of the transmitting end encoder 101 and the internal state of the receiving end decoder 302 are always matched, the annoying voice resulting from the mismatch of the internal states is decoded. The risk of doing so is avoided. Furthermore, the number of functional blocks added in the relay node 22 is small, and economically high-quality voice transmission can be realized.

Fourth Embodiment Next, a fourth embodiment will be described with reference to FIG. In the present embodiment, the transmission end 10 and the relay node 20 in the voice coding transmission system of the first embodiment are improved to form a transmission end 11 and a relay node 23.

Here, 102 is a decoder (transmission side decoding means) for decoding the voice code highly efficient encoded by the encoder 101 into a voice signal, and 112 is a pseudo background noise signal encoded by the high efficiency encoding system. A pseudo background noise generation unit (transmission side background noise generation means) for generating a coded code (first pseudo signal), 114 is a switch for switching the input to the decoder 102, and 212 is a high efficiency code for the pseudo background noise signal. It is a pseudo background noise generation unit (relay side background noise generation means) that generates a code (second pseudo code) coded by the coding method. In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

This voice transmission system is the relay node 2 in the voice coding transmission system according to the first embodiment.
By applying the improvement implemented in No. 0 to the transmitting end 11, an attempt is made to construct a voice coding transmission system capable of high quality voice transmission that solves the above problems.

Next, the operation of the speech coded transmission system according to this embodiment will be described. At the transmitting end 11, the voice detector 103 discriminates the voiced section / silent section based on the input original audio signal, and outputs a control signal 1A for controlling the operation mode of the transmitting end 11 based on the result. To do. When the voice detector 103 determines that there is "sound", the changeover switch 114 is set to 114B side, the changeover switch 105 is set to 105B side, and the changeover switch 104 is set to 104B.
Defeat each side. As a result, the audio signal input to the transmission end 11 is input to the encoder 101 via the changeover switch 105, is subjected to high-efficiency coding, and is then output to the transmission path A via the changeover switch 104. .

At the same time, the speech code output from the encoder 101, which is obtained by highly efficient encoding the input speech, is also supplied to the decoder 102 via the changeover switch 114. The decoder 102 receives the audio signal from the encoder 101 as input and performs a normal decoding operation. The purpose of this operation is to keep the internal state of the decoder 102 consistent with the internal state of the transmission end encoder 101, not to obtain a decoded voice signal. Then, the changeover switch 115 is switched so as to prevent the obtained decoded voice signal from being output to another functional block.

At the timing when the judgment of the voice detector 103 transits from "voiced" to "silent", the voice detector 103
Outputs an initialization signal 1B for controlling the initialization of the pseudo background noise generation unit 112. The pseudo background noise generation unit 112
The internal state is reset at the timing when the initialization signal 1B is received. This operation is performed for the same purpose as that described in the first embodiment.

If the voice detector 103 determines that the sound is "silent", the changeover switch 114 is set to the side 14A, the changeover switch 105 is set to the side 105A, and the changeover switch 104 is set to 104.
Defeat each to the B side. As a result, the pseudo background noise code output from the pseudo background noise generation unit 112 is input to the decoder 102 via the changeover switch 114 and subjected to decoding processing, and then the obtained decoded pseudo background noise signal is changed over to the changeover switch. It is output to the encoder 101 via 105. The encoder 101 receives the pseudo background noise signal decoded by the decoder 102 as an input and performs a normal encoding operation. The purpose of this operation is to keep the internal state of the encoder 101 consistent with the internal state of the decoder 102, not to obtain the encoded speech signal. Then, in order to prevent the obtained voice code from being output to the transmission path A,
The changeover switch 104 is switched. Through these series of operations, the internal state of the encoder 101 and the internal state of the decoder 102 are always kept in a matched state.

Here, in the encoder 101 and the decoder 102, although there are differences in the input signals, that is, the original speech signal and the speech code once encoded by the encoder 101, the nature of speech is extremely high. It is similar.
Therefore, the internal state of the encoder 101 and the internal state of the decoder 102, which correspond to the digitized nature of the audio signal, are held at extremely similar values.

The relay node 23 receives the silence-compressed first voice code transmitted from the transmitting end 11 via the transmission path A. The presence / absence information extraction unit 207 constantly monitors the reception status of the first voice code from the transmission path A, and outputs the control signal 2A for controlling the changeover switch 214 according to the result. That is, when the first voice code is input from the transmission path A, it is determined to be a voiced section and the changeover switch 214 is tilted to the 214B side. The first voice code received by the relay node 23 passes through the switch 214 as it is to the transmission line B.
Will be relayed to.

On the other hand, in the presence / absence information extraction unit 207, when the reception of the signal from the transmission path A is not detected, that is, in the section judged as "silence", the changeover switch 214 is turned on by the control signal 2A. Turn it down to 214A. The data in which the pseudo background noise signal is encoded is supplemented and output to the transmission line B. Of course, as in the first embodiment,
At the timing when the judgment of the sound / silence information extraction unit 207 transits from “sound” to “silence”, the sound / silence information extraction unit 20 is performed.
7 outputs an initialization signal 2B for controlling the initialization of the pseudo background noise generator 212. Pseudo background noise generator 212
Resets the state at the timing of receiving the initialization signal 2B.

The receiving end 30 receives the second voice code which is continuously transmitted from the relay node 23 via the transmission line B and in which the silent section is interpolated by the pseudo background noise code. The decoder 302 performs a decoding process based on the input second voice code, decodes the voice signal, and outputs the voice signal from the receiving end 30.

Since the second speech code input to the receiving end 30 is the output of the encoder 101 of the transmitting end 11 in the voiced section, the encoder 101 of the transmitting end 11 is in the voiced section. And the internal state of the decoder 302 of the receiving end 30 match. Also, in the silent section, the receiving end 30
The second voice code input to is the output of the pseudo background noise generation unit 212 of the relay node 23. As described above, since the output of the pseudo background noise generation unit 212 of the relay node 23 matches the output of the pseudo background noise generation unit 112 of the transmission end 11, it is apparently transmitted from the reception end 30 as if it were transmitted. It is possible to obtain an effect as if the pseudo background noise code which is not silence-compressed is directly received from the end 11.

Moreover, the second speech code which is changed from "silent" to "voiced" and input to the decoder 302 is the encoder 101.
Even if the output signal is switched to the output signal of the encoder 10,
Since the internal state of No. 1 and the internal state of the decoder 302 of the receiving end 30 match very well, it is possible to prevent the generation of abnormal noise from the signal output from the decoder 302 due to the difference in the internal state. .

As described above, the encoder 10 of the transmitting end 11
Since the internal state of 1 and the internal state of the decoder 302 of the receiving end 30 are always matched, the risk of decoding annoying voice due to the mismatch of the internal states is avoided.
Further, the number of functional blocks added in the relay node 23 is small, and economically high-quality voice transmission can be realized.

Embodiment 5. Next, a fifth embodiment will be described with reference to FIG. The present embodiment is different from the transmitting end 11 shown in the fourth embodiment in the second embodiment.
In addition to the improvements in the relay node 21 shown in FIG.
2 is set. The same or equivalent components as in the fourth embodiment will be assigned the same reference numerals and explanations thereof will be omitted.

At the transmitting end 12, the voice detector 103
Identifies the voiced section / silent section based on the input original voice signal, and outputs a control signal 1A for controlling the operation mode of the transmission end 12 based on the result. Voice detector 10
If it is determined to be “voiced” in 3, the changeover switch 104
To the 104B side. As a result, the voice signal input to the transmission end 12 is input to the encoder 101, is subjected to high-efficiency encoding, and is output to the transmission path A via the changeover switch 104.

Next, the judgment of the voice detector 103 is "voiced".
From the sound detector 10 to the "silence" transition timing
3 outputs an initialization signal 1B that controls initialization of the pseudo background noise generation unit 112. Pseudo background noise generator 112
Resets the internal state at the timing when this initialization signal 1B is received, and the pseudo background noise code (first pseudo code)
To start sending.

The pseudo background noise generation unit 112 realizes the same operation as the pseudo background noise generation unit 212 of the relay node 23, and the initialization operation is also performed by the pseudo background noise generation unit of the relay node 23. It is the same as 212.
The initialization operation is performed in synchronization with the presence / absence of a voice signal input from the transmission path A, and by extension, with the determination signal of the voice detector 103 of the transmitting end 12, the decoder 102 of the transmitting end 12 and the changeover switch of the relay node 23. The same pseudo background noise code can be supplied to 214 at the same timing.

At the same time, the initialization signal 1B is also supplied to the encoder 101 and the decoder 102. The encoder 101 that has received the initialization signal 1B sends internal parameters to the decoder 102 and stops its operation. The decoder 102 receives the internal parameters from the encoder 101 by the initialization signal 2B,
Based on this, the decoding process of the pseudo background noise code supplied from the pseudo background noise generation unit 112 is started.

Finally, the voice detector 103 outputs the control signal 1C at the timing when the judgment of the voice detector 103 transits from "silent" to "voiced". The decoder 102 having received the control signal 1C sets the internal parameters to the encoder 10
1 to stop the operation. The encoder 101 receives the internal parameter from the decoder 102 by the control signal 1C, and starts the encoding process of the original audio signal based on the internal parameter. Through a series of these operations, the internal state of the encoder 101 and the internal state of the decoder 102 are always kept in a matched state, so that the encoding process can be normally restarted.

In the relay node 23, the fourth embodiment
Performs the same operation as the operation indicated by. Furthermore, the receiving end 30
Then, the second node is continuously transmitted from the relay node 23 via the transmission line B, and the silent section is interpolated by the pseudo background noise code.
Receive the voice code of. The decoder 302 receives the second input
The decoding process is performed based on the voice code of No. 1, and the voice signal is decoded and output from the receiving end 30.

Since the second speech code input to the receiving end 30 is the output of the encoder 101 of the transmitting end 12 in the voiced section, the encoder 101 of the transmitting end 12 is in the voiced section. And the internal state of the decoder 302 of the receiving end 30 match. In the silent section, the receiving end 30
The second voice code input to is the output of the pseudo background noise generation unit 212 of the relay node 23. As described above, since the output of the pseudo background noise generation unit 212 of the relay node 23 matches the output of the pseudo background noise generation unit 112 of the transmission end 12, it is apparently transmitted from the reception end 30 as if it were transmitted. It is possible to obtain an effect as if the voice code which is not silence-compressed is directly received from the end 12.

As described above, the encoder 10 of the transmitting end 12
Since the internal state of 1 and the internal state of the decoder 302 of the receiving end 30 are always matched, the risk of decoding annoying voice due to the mismatch of the internal states is avoided.
Further, since the encoder 101 operates only in the silent section and the decoder 102 operates only in the sound section at the transmitting end 12, they do not execute the processing at the same time, and the load on the processor is reduced. Cost reduction and power consumption reduction are realized by reduction. Further, the number of functional blocks added in the relay node 23 is small, and economically high-quality voice transmission can be realized.

Sixth Embodiment Next, a sixth embodiment will be described with reference to FIGS. In the present embodiment, the transmitting end 11 shown in the fourth embodiment is modified to a transmitting end 13 by improving the relay node 22 shown in the third embodiment. Here, 108 is an encoder with an internal state holding function (transmission side encoding means) having the same function as the interpolation signal generator 208 in the third embodiment. The same or equivalent components as in the fourth embodiment will be assigned the same reference numerals and explanations thereof will be omitted.

First, the encoder with internal state holding function 108
The operation of will be described with reference to FIG. In order to show a specific configuration of the encoder 108 with an internal state holding function, this is an example in which ITU Recommendation G.728 is applied to a high-efficiency speech coding system. As can be seen by comparing FIG. 8 and FIG. 4, this is the interpolation signal generator 208 in the third embodiment.
There is no difference from the structure of. Therefore, the description of each functional block is omitted.

Next, the operation of the voice transmission system according to the sixth embodiment will be described with reference to FIG. Voice detector 10
3, in the section where the signal from the transmission path A is determined to be "sound", the changeover switch 421 is set to the 421B side and the changeover switch 422 is set to 422B by the control signal 1A.
Switch 423 to side 423B. The structure and operation of the encoder with internal state holding function 108 at this time are the same as the structure and operation of the encoder 101 in the first embodiment. That is, with the input original speech signal as an input, the most approximate synthesized signal is selected from the candidates of the synthesized speech signal synthesized by the local decoder, and the background noise code that is the source of the synthesized signal is set as the optimal code.
It is output from the encoder 108 with the internal state holding function. This output signal is sent to the transmission line A.

In the section where the signal from the transmission line A is determined to be "silent" in the voice detector 103, the control signal 1A causes the changeover switch 421 to the 421A side, the changeover switch 422 to the 422A side, and the changeover switch. 423
To the 423A side. Local decoder unit 4
20 receives the signal from the pseudo background noise generator 112 and performs a normal decoding operation. The purpose of this operation is to operate the backward type gain adaptation section 410 and the backward type synthesis filter adaptation section 411 so that the gain multiplier 404,
The internal state of the synthesizing filter 405 is calculated by the receiving end decoder 302.
To keep it in a state that always matches the internal state of
Not to get the decoded audio signal.

Since the output of the synthesis filter 405, that is, the output path of the decoded audio signal is cut off by the switch 423, the output of the local decoder 420 is not referred to by other functional blocks. . Further, in the encoder with internal state holding function 108, functional blocks other than the local decoder 420, that is, the PCM decompression unit 401, the vector buffer unit 402, and the adder 40
6. The auditory weighting filter 407 and the least square error search unit 408 are stopped because there is no signal to be input.

The relay node 23 according to the fourth embodiment.
Performs the same operation as the operation indicated by. Furthermore, the receiving end 30
Then, the second node is continuously transmitted from the relay node 23 via the transmission line B, and the silent section is interpolated by the pseudo background noise code.
Receive the voice code of. The decoder 302 receives the second input
The decoding process is performed based on the voice code of No. 1, and the voice signal is decoded and output from the receiving end 30.

Since the second voice code input to the receiving end 30 is the output of the encoder 108 with the internal state holding function of the transmitting end 13 in the voiced section, the second voice code is transmitted in the voiced section. The internal state of the encoder with internal state holding function 13 of 13 and the internal state of the decoder 302 of the receiving end 30 match. The second voice code input to the reception end 30 in the silent section is the output of the pseudo background noise generation unit 212 of the relay node 23. Since this is the same as the output of the pseudo background noise generator 112 of the transmitting end 13, the internal state of the encoder 108 with the internal state holding function of the transmitting end 13 and the internal state of the decoder 302 of the receiving end 30 match. . As described above, apparently from the receiving end 30, it is as if the transmitting end 13
It is possible to obtain an effect as if the voice code which is not silence-compressed is directly received from.

As described above, since the internal state of the encoder 108 with the internal state holding function of the transmitting end 13 and the internal state of the decoder 302 of the receiving end 30 are always matched, the internal state does not change. The risk of decoding offensive speech due to matching is avoided. Furthermore, the number of functional blocks added in the relay node 23 is small, and economically high-quality voice transmission can be realized.

Seventh Embodiment Next, a seventh embodiment will be described with reference to FIGS. In this embodiment, in addition to the transmitting end 13 shown in the sixth embodiment, the relay node 22 shown in the third embodiment is improved,
This is the transmission end 14. Further, the relay node 23 shown in the sixth embodiment is modified to be a relay node 24.

Here, 110 is an encoder with internal state holding function (transmission side encoding means) obtained by improving the encoder with internal state holding function 108 of the transmitting end 13 in the sixth embodiment, and 111 is pseudo background noise. A generation parameter generation unit (transmission side parameter generation means), 211 is a pseudo background noise generation parameter generation unit (relay side parameter generation means), and 210 is a simple encoder having a partial function of the encoder in the sixth embodiment. is there. In addition, the same reference numerals are given to the same or equivalent components as in the sixth embodiment, and the description thereof will be omitted.

First, the encoder 110 with the internal state holding function
The operation will be described with reference to FIG. This shows a specific configuration of the encoder 110 with an internal state holding function, and therefore, as an example, ITU Recommendation G.728 is adopted as a high-efficiency speech coding method.
Is applied. As can be seen by comparing FIG. 10 and FIG. 8, this is almost the same as the structure of the encoder 108 with the internal state maintaining function in the sixth embodiment except that the position of the changeover switch 421 is different. Therefore, the description of each functional block is omitted.

[0136] In addition, ITU Recommendation G.728 LD-CELP is used as an encoding method.
When the method is used, an excitation signal for driving the synthesis filter is used as an example of the signal output from the pseudo background noise generation parameter generation unit 111. A decoder based on the LD-CELP speech coding system has a structure that exactly models a human generation mechanism. That is, the structure is such that an excitation signal corresponding to a human vocal cord sound source is used as a driving source, a synthetic filter that models human vocal tract information is used for articulation, and voice is synthesized. A waveform codebook obtained by vector-quantizing the excitation signal is used as the voice code. The pseudo background noise generation parameter generation unit 111 is a functional block that generates an excitation signal before being quantized by some means.

Next, the operation of the voice transmission system according to the seventh embodiment will be described with reference to FIG. Voice detector 10
3, in the section where the voice signal is determined to be “voiced”, the changeover switch 421 is switched to 4 by the control signal 1A.
The selector switch 422 is tilted to the 422B side, and the selector switch 423 is tilted to the 423B side on the 21B side. The structure and operation of the encoder 110 with the internal state maintaining function at this time are the same as the structure and operation of the normal encoder 101 in the first embodiment. That is, with the input original speech signal as an input, the closest synthesized signal is selected from the synthesized speech signal candidates synthesized by the local decoder, and the background noise code that is the source of the synthesized signal is used as the optimum code. It is output from the encoder 110 with a state holding function. This output signal is sent to the transmission line A.

In the section in which the voice detector 103 determines that the voice signal is "silent", the control signal 1A causes the changeover switch 421 to the 421A side, the changeover switch 422 to the 422A side, and the changeover switch 423 to 423.
Defeat each to the A side. The local decoder unit 420 receives the excitation signal (first parameter signal) output from the pseudo background noise generation parameter generation unit 111, and performs a decoding operation using this signal. This decoding process is the same as the normal decoding process except that the inverse quantizing means 403 is skipped.

The purpose of this operation is the backward type gain adaptation section 410 and the backward type synthesis filter adaptation section 4.
11 to operate the gain multiplier 404 and the synthesis filter 4
05 is the internal state of the receiving end decoder 302,
It is for the purpose of always maintaining the matched state, not for obtaining the decoded voice signal. Then, the synthesis filter 405
, The output path of the decoded audio signal is cut off by the switch 423.
The output of 20 is not referred to by other functional blocks. Further, in the encoder 110 with the internal state holding function, the functional blocks other than the local decoder 420, that is, the PCM decompression unit 401, the vector buffer unit 402, the adder 406, the perceptual weighting filter 407, and the least square error search unit 408 are input as inputs. Stop because there is no signal to do.

The relay node 24 includes the same pseudo background noise generation parameter generation unit 211 as the transmission end 14, and operates in synchronization with the pseudo background noise generation parameter generation unit 111 of the transmission end 14. This method is realized by using the same method as the pseudo background noise generation units 106 and 206 in the first embodiment. Relay node 2
In order to interpolate the voice code of the silent section which is missing in 4, the simple encoder 210 having a function of encoding the excitation signal (second parameter signal) output from the pseudo background noise generation parameter generation unit 211 is simulated by the simple encoder 210. The background noise code is interpolated.

Next, the structure of the simple encoder 210 is shown in FIG. In the vector buffer 431, the time-continuous excitation signal is accumulated for 5 samples, vectorized, and output to the adder 434. On the other hand, all the code candidates accumulated in the waveform codebook are inversely quantized by the inverse quantizer 432 to generate excitation signal candidates. All of these excitation signal candidates are input to the adder 434, the squared error from the input excitation signal is taken, and the code that generated the most approximate excitation signal candidate is output as the optimum code. This makes it possible to generate a pseudo background noise code equivalent to a code based on the LD-CELP method.

Further, at the receiving end 30, the relay node 24
To the second voice code which is continuously transmitted through the transmission path B from which the silent section is interpolated by the pseudo background noise code. The decoder 302 performs a decoding process based on the input second voice code, decodes the voice signal, and outputs the voice signal from the receiving end 30.

Since the second voice code input to the receiving end 30 is the output of the encoder 110 with the internal state holding function of the transmitting end 14 in the voiced section, the second voice code is transmitted in the voiced section. The internal state of the encoder 110 with the internal state holding function 14 and the internal state of the decoder 302 of the receiving end 30 match. The second voice code input to the receiving end 30 in the silent section is the output of the pseudo background noise generation parameter generation unit 211 of the relay node 24. Since this is the same as the output of the pseudo background noise generation parameter generation unit 111 of the transmission end 14, the internal state of the encoder 110 with the internal state holding function of the transmission end 14 and the decoder 30 of the reception end 30.
The internal states of 2 are in agreement. As described above, it is possible to obtain an effect as if the receiving end 30 were directly receiving from the transmitting end 14 an uncompressed voice code.

As described above, since the internal state of the encoder 110 with the internal state holding function of the transmitting end 14 and the internal state of the decoder 302 of the receiving end 30 are always matched, the internal state does not change. The risk of decoding offensive speech due to matching is avoided. Furthermore, the number of functional blocks added in the relay node 24 is small, and economically high-quality voice transmission can be realized.

Eighth Embodiment Hereinafter, the eighth embodiment will be described with reference to FIGS. In the present embodiment, the transmitting end 10 and the relay node 20 in the voice coding transmission system of the first embodiment are improved to form a transmitting end 15 and a relay node 25. Here, 213 is a timer that counts the transition section immediately after the first audio signal output from the transmitting end 15 is switched from "silent" to "speech". In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

Next, the operation of the eighth embodiment will be described. At the transmitting end 15, the voice detector 103 discriminates the voiced section / silent section based on the input original audio signal, and outputs a control signal 1A for controlling the operation mode of the transmitting end 15 based on the result. To do. When the voice detector 103 determines that there is "sound", the changeover switch 104 is tilted to the 104B side. As a result, the original voice signal input to the transmission end 15 is input to the encoder 101, is subjected to high-efficiency encoding, and is output to the transmission path A via the changeover switch 104.

On the other hand, when the voice detector 103 determines "silence", the changeover switch 104 is tilted to the 104A side. At this time, the voice code output from the encoder 101 is cut off by the changeover switch 104, and nothing is output to the transmission path A. Also, at the timing when the voice detector 103 detects the transition from the “silent” state to the “voiced” state,
The initialization signal 1B for initializing the encoder 101 is output to the encoder. The encoder 101 executes the initialization operation of the internal state at the timing of receiving the initialization signal 1B.

Regarding the present embodiment, the operation of the relay node 25 has three modes depending on the state of the control signal output from the sound / silence information extraction unit 207. This operation mode will be described with reference to FIG. FIG.
FIG. 4 is a waveform diagram of an original audio signal input to the encoder 101 of the transmission end 15. The vertical axis represents the signal level and the horizontal axis represents time. The voiced / unvoiced information extraction unit 207 constantly monitors the reception status of the voice code from the transmission path A, which reflects the operation of the voice detector 103 of the transmission end 15, and as a result, divides it into three sections corresponding to the operation mode. Then, the operation of the relay node 25 is controlled.

First, the period in which the talk spurt is not detected from the high-efficiency voice code input to the relay node 25.
The (silent section) is set to mode 1. Second, the relay node 25
Mode 2 is defined as a period from several tens msec to several hundreds msec (referred to as a transition period or a transition period) after the talk spurt is detected from the high-efficiency speech code input to the. Third
In addition, after the mode 2, the period during which the talk spurt is continuously detected is set to the mode 3. The voiced / unvoiced information extraction unit 207 and the timer 213 output the control signals 2A and 2F reflecting the above-described operation mode determination result, and supply the control signals 2A and 2F to each functional block of the relay node 25.

Here, the duration of mode 2 (transition period)
The value of several 10 msec to 100 msec was presented as
The basis of this value is based on the following rules of thumb. First, as a prerequisite, ITU Recommendation G.728 (LD-CE
It is assumed that the internal state of the encoder 201 of the relay node 25 and the internal state of the decoder 302 of the receiving end 30 are completely different by using the LP system). Under this precondition, the encoder 2
01 and the decoder 302 perform encoding / decoding via the transmission path. Since the stability of all the filters used in the LD-CELP method is guaranteed, the internal states of the transmitter and receiver gradually converge in the same direction.

While the encoding / decoding is continued as it is, the internal states are sufficiently coincident with each other to such an extent that there is no possibility of generating abnormal noise. The time required from the mode transition until the internal states are sufficiently matched is several tens of msec to 100 msec. Needless to say, this value is expected to change depending on the high-efficiency coding method used, and it is important to set the transition period according to each coding method.

FIG. 14 is a mode transition diagram summarizing the transition of each mode described above. The transitions between the three modes are allowed only in the directions indicated by the arrows, and the other transitions are prohibited transitions or physically impossible transitions.

Next, the operation of the relay node 25 will be described for each mode. First, in mode 1, that is, in the section where it is determined that the sound / silence information extraction unit 207 is “silent”, the changeover switch 205 is turned to the 205A side and the changeover switch 214 is turned to the 214A side. At this time, the output signal from the pseudo background noise generation unit 206 is the changeover switch 205.
Is input to the encoder 201 via. The encoder 201 executes an encoding process based on the input pseudo background noise signal and outputs a pseudo background noise code. The pseudo background noise code output from the encoder 201 is sent to the transmission path A via the changeover switch 214. By this series of operations,
The signal in the silent section can be supplemented with a pseudo background noise signal. Then, at this time, the decoder 202 loses the input signal and thus stops its operation.

When the mode 1 is transited to the mode 2, that is, when the voice code starts being detected in the voiced / unvoiced information extraction section 207, the reset signal 2 is sent to the decoder 202.
Issue B. Since the operation of the voiced / unvoiced information extraction unit 207 faithfully reflects the operation of the voice detector 103,
This is executed in synchronization with the initialization of the encoder 101 of the transmitting end 15.

In mode 2, the changeover switch 205
Is pushed down to 205B, and the changeover switch 214 remains connected to 214A. The voice code received by the relay node 25 is supplied to the decoder 202. The encoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded voice signal is transferred to the changeover switch 205.
Is supplied to the encoder 201 via. Encoder 201
Performs encoding processing based on the input audio signal.
This voice code is output to the transmission line B via the changeover switch 214. That is, the relay node 25 has the same form as the tandem connection.

In mode 3, the changeover switch 214, which has received the control signal 2F from the timer 213, changes to 214B.
Fall to the side. Further, the changeover switch 205 remains connected to the 205B side. The voice code received by the relay node 25 passes through the changeover switch 214 as it is to the transmission path B.
Will be relayed to. The voice code is also supplied to the decoder 202. The decoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded voice signal is passed through the changeover switch 205 to the encoder 2
01 is supplied. The encoder 201 executes an encoding process based on the input audio signal.

Here, there is a difference between the encoder 101 of the transmitting end 15 and the encoder 201 of the relay node 25, in which the input signals are the original audio signal and the decoded audio signal decoded by the decoder 202, respectively. However, the nature of voice is very similar. Therefore, the internal state of the transmission end encoder 101 and the internal state of the relay encoder 201, which correspond to the digitized nature of the voice signal, are held at extremely similar values.

In this embodiment, the case where the mode 1 is suddenly changed to the mode 3 will be considered. For the time being, it is guaranteed that the internal state of the transmission end encoder 101 and the relay decoder 202, and the internal state of the relay encoder 201 and the internal state of the reception end decoder 302 are the same. However, the internal states of the transmitting end encoder 101 and the receiving end decoder 302 are not guaranteed at all. Therefore, when the mode 1 jumps to the mode 3 in a jump, it becomes just like the form of the digital 1 link shown in the conventional example, and an abnormal sound is generated due to the mismatch of the internal states. Here, by providing the mode 2 as the transition section during the transition from the mode 1 to the mode 3, the internal state of the transmission end encoder 101 and the internal state of the reception end decoder 302 are sufficiently coincident with each other. It is possible to avoid the generation of abnormal noise even if the mode 3 is entered.

In the voice coded transmission system according to this embodiment, the period for permitting tandem connection, which is known to cause voice quality deterioration, is set to a short time in the transition period from the silent state to the voiced state. By restricting and connecting most of the talk spurts with one-link encoding / decoding, it is possible to avoid quality deterioration and to fully bring out the performance of the high-efficiency speech encoding system. Further, it is possible to reduce the processing load of the processor and the hardware scale at the relay node. Although the present embodiment has described the system in which the ITU recommendation G.728 LD-CELP system is applied to the high efficiency coding system, it is shown that the application example of the present invention is limited to this coding system. However, it can be easily inferred that the present invention can be applied to all speech coding methods that use past coding / decoding results.

Ninth Embodiment The ninth embodiment will be described below with reference to FIG. In the present embodiment, with respect to the relay node 25 shown in the eighth embodiment,
The relay node 26 is obtained by replacing the timer 213 with a comparator (comparing means) 215. Here, the comparator 215 numerically compares the internal state of the decoder 202 and the internal state of the encoder 201. The same or equivalent components as in the eighth embodiment will be assigned the same reference numerals and explanations thereof will be omitted.

Next, the operation of the relay node 26 will be described.
First, in mode 1, that is, in the section where it is determined that the voiced / silent information extraction unit 207 is “silent”, the changeover switch 205 is set to the 205A side and the changeover switch 214 is set to 214.
Defeat each to the A side. At this time, the pseudo background noise generator 2
The output signal on the 06 side is input to the encoder 201 via the changeover switch 205. The encoder 201 executes an encoding process based on the input pseudo background noise signal and outputs a pseudo background noise code. The pseudo background noise code output from the encoder 201 is sent to the transmission path A via the changeover switch 214. Through this series of operations, the signal in the silent section can be supplemented with the pseudo background noise signal. Then, at this time, the decoder 202 loses the input signal and thus stops its operation.

When the mode 1 transits to the mode 2, that is, when the voice code / voiceless information extraction section 207 starts to detect a voice code, the reset signal 2 is sent to the decoder 202.
Issue B. Since the operation of the voiced / unvoiced information extraction unit 207 faithfully reflects the operation of the voice detector 103,
This is executed in synchronization with the initialization of the encoder 101 of the transmitting end 15.

In mode 2, the changeover switch 205
Is pushed down to 205B, and the changeover switch 214 remains connected to 214A. The voice code received by the relay node 25 is supplied to the decoder 202. The encoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded voice signal is transferred to the changeover switch 205.
Is supplied to the encoder 201 via. Encoder 201
Performs encoding processing based on the input audio signal.
This voice code is output to the transmission line B via the changeover switch 214. That is, the relay node 25 has the same form as the tandem connection.

In the mode 3, the internal parameters of the encoder 201 and the internal parameters of the decoder 202 are given to the comparator 215. The comparator 215 determines whether these internal parameters match within a predetermined level,
When they match within this level, the control signal 2D is output to the changeover switch 214. And this control signal 2F
The changeover switch 214 that has received the message is tilted to the side of 214B.
Further, the changeover switch 205 remains connected to the 205B side.

The voice code received by the relay node 25 is relayed to the transmission path B as it is via the changeover switch 214. The voice code is also supplied to the decoder 202. The decoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded audio signal is supplied to the encoder 201 via the changeover switch 205. The encoder 201 executes an encoding process based on the input audio signal.

Here, there is a difference between the encoder 101 of the transmitting end 15 and the encoder 201 of the relay node 25, in which the input signals are the original speech signal and the decoded speech signal decoded by the decoder 202, respectively. However, the nature of voice is very similar. Therefore, the internal state of the transmission end encoder 101 and the internal state of the relay encoder 201, which correspond to the digitized nature of the voice signal, are held at extremely similar values.

As described above, by controlling the determination of the transition timing from mode 2 to mode 3 according to the determination result of the comparator 215, the internal state of the encoder 101 of the transmitting end 15 and the decoder of the receiving end 30 are controlled. The internal state of 302 can be more surely matched, and there is an effect of further reducing the risk of abnormal noise.

[Embodiment 10] The tenth embodiment will be described below with reference to FIG. In the present embodiment, a comparator (comparing means) 215 and a judging circuit (judging means) are provided for the relay node 25 shown in the eighth embodiment.
216 is added to form a relay node 27. Here, the comparator 215 numerically compares the internal state of the decoder 202 and the internal state of the encoder 201, and the determination circuit 216 includes the control signal 2F output from the timer 213 and the comparator 215. Control signal 2 output from
The transition timing to the mode 3 is determined based on D and. The same or equivalent components as in the eighth embodiment will be assigned the same reference numerals and explanations thereof will be omitted.

Next, the operation of the relay node 27 will be described.
First, in mode 1, that is, in the section where it is determined that the voiced / silent information extraction unit 207 is “silent”, the changeover switch 205 is set to the 205A side and the changeover switch 214 is set to 214.
Defeat each to the A side. At this time, the pseudo background noise generator 2
The output signal on the 06 side is input to the encoder 201 via the changeover switch 205. The encoder 201 executes an encoding process based on the input pseudo background noise signal and outputs a pseudo background noise code. The pseudo background noise code output from the encoder 201 is sent to the transmission path A via the changeover switch 214. Through this series of operations, the signal in the silent section can be supplemented with the pseudo background noise signal. Then, at this time, the decoder 202 loses the input signal and thus stops its operation.

When the mode 1 is switched to the mode 2, that is, when the voice code is detected by the voice / silence information extraction unit 207, the reset signal 2 is sent to the decoder 202.
Issue B. Since the operation of the voiced / unvoiced information extraction unit 207 faithfully reflects the operation of the voice detector 103,
This is executed in synchronization with the initialization of the encoder 101 of the transmitting end 15.

In mode 2, the changeover switch 205
Is pushed down to 205B, and the changeover switch 214 remains connected to 214A. The voice code received by the relay node 25 is supplied to the decoder 202. The encoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded voice signal is transferred to the changeover switch 205.
Is supplied to the encoder 201 via. Encoder 201
Performs encoding processing based on the input audio signal.
This voice code is output to the transmission line B via the changeover switch 214. That is, the relay node 25 has the same form as the tandem connection.

In the mode 3, the internal parameters of the encoder 201 and the internal parameters of the decoder 202 are given to the comparator 215. The comparator 215 determines whether these internal parameters match within a predetermined level,
If they match within this level, the control signal 2D is output to the determination circuit 216. Further, the timer 213 counts the transition timing to the mode 3 and outputs the control signal 2F to the determination circuit 216 with a predetermined count value.

The decision circuit 216 outputs these control signals 2
D, 2F input is accepted and both control signals 2D, 2F are received.
When F is input, the control signal 2E is switched to the switch 2
It outputs to 14. Then, the changeover switch 214 that has received the control signal 2E falls to the 214B side. Further, the changeover switch 205 remains connected to the 205B side.

The voice code received by the relay node 25 is relayed to the transmission line B as it is via the changeover switch 214. The voice code is also supplied to the decoder 202. The decoder 202 executes a decoding process based on the input voice code to decode a voice signal. The decoded audio signal is supplied to the encoder 201 via the changeover switch 205. The encoder 201 executes an encoding process based on the input audio signal.

Here, there is a difference between the encoder 101 of the transmitting end 15 and the encoder 201 of the relay node 25, in which the input signals are the original audio signal and the decoded audio signal decoded by the decoder 202, respectively. However, the nature of voice is very similar. Therefore, the internal state of the transmission end encoder 101 and the internal state of the relay encoder 201, which correspond to the digitized nature of the voice signal, are held at extremely similar values.

As described above, by controlling the determination of the transition timing from mode 2 to mode 3 according to the determination result of this determination unit, the internal state of the encoder 101 of the transmitting end 15 and the decoding of the receiving end 30 are controlled. It is possible to more surely match the internal state of the container 302. As a result, it is possible to prevent the sound quality from being deteriorated due to a long tandem time while reducing the possibility of generating abnormal noise.

Eleventh Embodiment FIG. 17 shows the first embodiment.
~ 6,8 ~ 10 pseudo background noise generator 106,2
06, an example of the structure of the pseudo background noise generation parameter generation units 111 and 211 according to the seventh embodiment is described in detail. The interpolation signal is stored in the cyclic memory shown in FIG. The pseudo background noise signal sequence is sequentially stored at a predetermined address in the memory space in units of samples (or in units of frames for pseudo background noise codes). When outputting the pseudo background noise signal, the sample indicated by the address pointer is output and the pointer is advanced by one address.

By making the memory a cyclic type, it is possible to cope with silent sections of any length. However, if the memory size is made small, the pseudo background noise signal has a signal component of a specific frequency due to the periodicity of the cyclic memory. The memory size should be large enough, as it will have a negative effect. Here, these pseudo background noise generation units 106,
206 or pseudo background noise generation parameter generation unit 11
When 1 and 2111 receive the initialization signal 2B, the position of the pointer is reset to address 0. By this operation, even if the disconnection state due to the silent compression occurs between the transmission ends 10 to 15 and the pseudo background noise generation units 106 and 206 of the relay nodes 20 to 27, the operation synchronized at both ends can be realized.

Twelfth Embodiment FIG. 18 shows the first to the first embodiments.
Pseudo background noise generators 106, 20 in 6, 8-10
6, a detailed example of the structure of the pseudo background noise generation parameter generation units 111 and 211 according to the seventh embodiment is shown. 441 is a white noise generation unit (random signal generator), and 442 is a filter. White noise generator 441
Is the background noise component that occurs in normal voice communication,
Paying attention to the strong whiteness (randomness), the background noise signal to be interpolated in the silent section is artificially realized by the output signal of the random number generator. The random number generation method is
For example, there are a PN pattern method and a method of taking a remainder.

Here, these pseudo background noise generators 10
6, 206 or the pseudo-background noise generation parameter generation units 111, 211 receive the initialization signal 2B, the seeds which are the initial value of the random number generator, the transmission ends 10 to 15, the relay node 20. The preset values are given to both of ~ 27. By this operation, even if a disconnection state occurs due to silent compression between the transmission ends 10 to 15 and the pseudo background noise signal generation units 106 and 206 of the relay nodes 20 to 27, operations that are synchronized at both ends can be realized. . Further, by inserting a filter 442 having a characteristic close to the frequency characteristic of natural background noise (for example, a filter having a 1 / f characteristic) at the output end of the random number generator, a pseudo background noise signal that is more comfortable Can be obtained.

Thirteenth Embodiment Next, a thirteenth embodiment will be described with reference to FIG. The present embodiment is the same as the voice detector 10 of the transmitting end 10 shown in the first embodiment.
3 and the voiced / unvoiced information extraction unit 207 of the relay node 20 between the signaling channel (synchronous signal transmission means) 103.
A (for example, ISDN D channel) is connected. In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

As described in the first embodiment, there is a method of checking the presence / absence of a voice code as a criterion for determining the voiced section and the silent section. For example, when the transmission path A is an ATM network, it is also one method to determine that the cell has transited to the silent section if the cell transmitted from the transmission end 10 has not arrived.

However, if cell discard, which is a deterioration factor peculiar to the network, occurs in the ATM network, the relay node 20 may erroneously recognize it as a silent section. In order to avoid this, the voice detector 1 of the transmitting end 10
03 and the voice / silent information extraction unit 207 of the relay node 20 to connect the signaling channel 103A. Then, by notifying the transmission end 10 to the relay node 20 separately using the signaling channel 103A, the information notifying that the transition from the voiced section to the silence section is performed, which is more effective in preventing erroneous recognition of the silence transition. It is possible to realize quality voice transmission.

Also in the second to ninth embodiments, the voice detector 103 at the transmitting end 10 to 15 and the relay nodes 21 to 2 are also included.
It goes without saying that the present system in which the signaling channel 103A is connected to the voiced / unvoiced information extraction unit 207 of No. 7 and the information is separately notified from the transmission ends 10 to 15 to the relay nodes 21 to 27 can be applied.

Fourteenth Embodiment Next, a fourteenth embodiment will be described with reference to FIG. In this embodiment, an identification pattern generation unit (identification pattern generation means) 217 is added to the transmission end 10 shown in the first embodiment to form a transmission end 16. Here, the identification pattern generation unit 217 generates a signaling transmission code pattern indicating the end of the voiced section.
In addition, the same reference numerals are given to the same or equivalent components as in the first embodiment, and the description thereof will be omitted.

The present embodiment is an improvement of the method of transmitting signaling for notifying the transition from the voiced section to the silent section from the transmission end 10 to the relay node 20. In this embodiment, this signaling information is transmitted in the in-channel. That is, at the transmitting end 10,
At the timing when the voice detector 103 detects the transition from the voiced section to the silence section, after the final voice code transmission,
The changeover switch 104 is switched to the 104C side. By this switching, the signaling transmission code pattern generated by the identification pattern generation unit 217 is transmitted to the relay node 20. After sending the code pattern for signaling transmission, the changeover switch 104 is switched to the 104A side, and the sending of the code pattern for signaling transmission is stopped.

Sound / silence information extraction unit 2 of relay node 20
07 constantly monitors the signal input from the transmission path A, and outputs the control signal 2A notifying that the transition from "voiced" to "silent" is performed at the timing when the signaling transmission code pattern is recognized. By using this method, it is possible to prevent erroneous recognition of silent transitions and realize high-quality voice transmission, and it is also possible to realize by simply adding functional blocks without changing the signal method. .

Also in the second to ninth embodiments, the identification pattern generating section 217 is added to the transmitting ends 10 to 15,
It goes without saying that the present method of transmitting signaling information by in-channel can be applied.

[0189]

With the voice coding and transmission system according to the present invention, it is possible to avoid deterioration of voice quality due to tandem connection, and the internal state at the time of coding processing at the transmitting end and the decoding processing at the receiving end. Since it is always matched with the internal state at the time of performing, it is possible to reduce abnormal noise and annoyance due to the mismatch of the internal state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a voice coding transmission system according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a speech coded transmission system according to a second embodiment.

FIG. 3 is a block diagram showing a configuration of a speech coding transmission system according to a third embodiment.

FIG. 4 is a block diagram showing in detail a configuration of an interpolation signal generator according to a third embodiment.

FIG. 5 is a block diagram showing a configuration of a voice coding transmission system according to a fourth embodiment.

FIG. 6 is a block diagram showing a configuration of a speech coded transmission system according to a fifth embodiment.

FIG. 7 is a block diagram showing a configuration of a speech coded transmission system according to a sixth embodiment.

FIG. 8 is a block diagram showing in detail a configuration of an encoder with an internal state holding function according to a sixth embodiment.

FIG. 9 is a block diagram showing a configuration of a speech coded transmission system according to a seventh embodiment.

FIG. 10 is a block diagram showing in detail the configuration of an encoder with an internal state holding function according to a seventh embodiment.

FIG. 11 is a block diagram showing in detail a configuration of a simple encoder according to a seventh embodiment.

FIG. 12 is a block diagram showing a configuration of a voice coding transmission system according to an eighth embodiment.

FIG. 13 is a waveform diagram of an original speech signal input to the encoder at the transmitting end according to the eighth embodiment.

FIG. 14 is a state transition diagram showing transitions between operation modes according to the eighth embodiment.

FIG. 15 is a block diagram showing the configuration of a speech coded transmission system according to a ninth embodiment.

FIG. 16 is a block diagram showing the configuration of a voice coding transmission system according to a tenth embodiment.

FIG. 17 is a diagram showing the configuration of a pseudo background noise signal generation unit according to the eleventh embodiment.

FIG. 18 is a diagram showing a configuration of a pseudo background noise signal generation unit according to the twelfth embodiment.

[Fig. 19] Fig. 19 is a block diagram showing the configuration of the speech coded transmission system according to the thirteenth embodiment.

FIG. 20 is a block diagram showing the configuration of a speech coded transmission system according to a fourteenth embodiment.

[Fig. 21] ITU-T Recommendation G.728 LD- which is an example of an encoding method
FIG. 1 is a block diagram showing a system configuration of a CELP speech coding system.

FIG. 22 is a block diagram showing a configuration of a conventional voice coding transmission system.

[Fig. 23] Fig. 23 is a block diagram illustrating a configuration of a conventional voice coding transmission system by tandem connection.

FIG. 24 is a block diagram showing a configuration of a conventional voice coding transmission system by digital 1-link connection.

[Explanation of symbols]

1 to 16 ... Transmission end, 20 to 27 ... Relay node, 30 ... Reception end, 101 ... Encoder (transmission side encoding means), 102 ...
Decoder (transmission side decoding means), 103A ... Signaling channel (synchronization signal transmission means), 104 ... Changeover switch (transmission side voice code generation means), 105 ... Changeover switch (transmission side background noise insertion means), 106, 112 ... Pseudo background noise generating section (transmitting side background noise generating means), 108, 1
10 ... Encoder with internal state holding function (transmission side encoding means), 111 ... Pseudo background noise generation parameter generation section (transmission side parameter generation means), 201 ... Encoder (relay side encoding means), 202 ... Decoding , Switch (relay side background noise insertion means), 206, 212 ... Pseudo background noise generator (relay side background noise generator), 208 ... Interpolation signal generator (interpolation signal generation) Means), 210 ... Simple encoder (relay side encoding means), 211 ... Pseudo background noise generation parameter generation section (relay side parameter generation means), 213 ... Timer, 21
4 ... Changeover switch (relay side voice code generation means) 215
Comparator (comparison means), 216 ... Judgment circuit (judgment means), 217 ... Identification pattern generation section (identification pattern generation means), A ... Transmission line (first transmission line), B ... Transmission line (second) Transmission line).

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Ebisawa 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. (56) References JP-A-9-321783 (JP, A) JP-A-5 -49054 (JP, A) JP-A-4-362830 (JP, A) JP-A-9-331330 (JP, A) JP-A-6-69950 (JP, A) JP-A-4-249446 (JP, A) ) JP-A-4-923 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/28 H03M 7/30 H04L 12/56 H04L 12/66

Claims (20)

(57) [Claims] 1. A transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by silently compressing the voice signal to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system comprising a receiving end for decoding the second voice code received from a transmission path and reproducing the original voice signal, the transmitting end transmits a first pseudo signal simulating background noise. Transmitting-side background noise generating means for generating, transmitting-side background noise inserting means for inserting the first pseudo signal in a silent section of the original speech signal, and encoding the speech signal obtained by the transmitting-side background noise inserting means Transmitting side encoding means for converting And a transmitting side voice code generating means for compressing a silent section of the voice code encoded by the side encoding means to generate the first voice code, wherein the relay node is configured to transmit the first voice code. Relay-side decoding means for decoding, relay-side background noise generating means for generating a second pseudo signal simulating background noise, and the first portion in the silent section of the voice signal decoded by the relay-side decoding means. 2 relay-side background noise inserting means for inserting the pseudo signal of No. 2, relay-side encoding means for encoding the voice signal obtained by the relay-side background noise inserting means, and the relay-side encoding means for encoding. A voice coding transmission system comprising: a relay side voice code generating means for inserting a voice code into a silent section of the first voice code to generate the second voice code. 2. A transmitting end for encoding a voiced section of an original voice signal and outputting a first voice code generated by silence compression to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system comprising a receiving end for decoding the second voice code received from a transmission path and reproducing the original voice signal, the transmitting end transmits a first pseudo signal simulating background noise. Transmitting-side background noise generating means for generating, transmitting-side background noise inserting means for inserting the first pseudo signal in a silent section of the original speech signal, and encoding the speech signal obtained by the transmitting-side background noise inserting means Transmitting side encoding means for converting And a transmitting side voice code generating means for compressing a silent section of the voice code encoded by the side encoding means to generate the first voice code, wherein the relay node is configured to transmit the first voice code. Relay side decoding means for decoding, relay side background noise generation means for generating a second pseudo signal imitating background noise, relay side encoding means for encoding the second pseudo signal, and the relay A relay side voice code generating means for generating the second voice code by inserting the pseudo code encoded by the side encoding means into a silent section of the first voice code; The means for inputting the internal parameter of the relay side decoding means, and using the internal parameter, holds an internal state equivalent to that of the relay side decoding means, the voice coding transmission system. 3. A transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by silently compressing the voice signal to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system comprising a receiving end for decoding the second voice code received from a transmission path and reproducing the original voice signal, the transmitting end transmits a first pseudo signal simulating background noise. Transmitting-side background noise generating means for generating, transmitting-side background noise inserting means for inserting the first pseudo signal in a silent section of the original speech signal, and encoding the speech signal obtained by the transmitting-side background noise transmitting means Transmitting side encoding means for converting And a transmitting side voice code generating means for compressing a silent section of the voice code encoded by the side encoding means to generate the first voice code, wherein the relay node is a second node imitating background noise. Background noise generation means for generating a pseudo signal of the above, interpolation signal generation means for decoding the first voice code, and encoding the second pseudo signal, and encoding by the interpolation signal generation means. And a relay side voice code generating means for generating the second voice code by inserting the generated pseudo code into a silent section of the first voice code, wherein the interpolation signal generating means performs a decoding process and a code. An audio coding and transmission system characterized by holding an internal state common to the encoding processing. 4. A transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by silence compression to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system including a receiving end that decodes a second voice code received from a transmission path and reproduces the original voice signal, the transmitting end uses a first pseudo code that imitates background noise. Transmitting-side background noise generating means for generating, transmitting-side decoding means for decoding the first pseudo code, and the pseudo signal decoded by the transmitting-side decoding means is inserted into the silent section of the original speech signal. Transmitting-side background noise inserting means, and the transmitting-side background A transmitting side encoding means for encoding the voice signal obtained by the sound inserting means, and a silent section of the voice code encoded by the transmitting side encoding means are compressed to generate the first voice code. A transmission side voice code generation means, wherein the relay node generates a second pseudo code that imitates background noise, and a relay side background noise generation means; and a second interval in a silent section of the first voice code. And a relay side voice code generation means for inserting the pseudo code to generate the second voice code, wherein the transmission side decoding means inputs the voice code encoded by the transmission side encoding means. The voice coding transmission system is characterized in that the voice code is decoded for a voiced section and the second pseudo code is decoded for a voiceless section. 5. A transmitting end for encoding a voiced section of an original voice signal and outputting a first voice code generated by performing silence compression to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system including a receiving end that decodes a second voice code received from a transmission path and reproduces the original voice signal, the transmitting end uses a first pseudo code that imitates background noise. Transmitting-side background noise generating means for generating, transmitting-side decoding means for decoding the first pseudo-code, transmitting-side encoding means for encoding the original speech signal, and encoding by the transmitting-side encoding means The first segment is compressed by compressing the silent section of the encoded voice code. A transmission side voice code generating means for generating a voice code, wherein the relay node, a relay side background noise generating means for generating a second pseudo code imitating background noise, and a silent section of the first voice code. And a relay side voice code generating means for generating the second voice code by inserting the second pseudo code into the relay side voice code generating means, wherein the transmitting side coding means inputs internal parameters of the transmitting side decoding means. Then, the voice coding transmission system is characterized in that the internal state equivalent to that of the transmitting side decoding means is held by using this internal parameter. 6. A transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by performing silence compression to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; In a voice coding transmission system comprising a receiving end for decoding the second voice code received from a transmission path and reproducing the original voice signal, the transmitting end transmits a first pseudo signal simulating background noise. Transmitting-side background noise generating means for generating, transmitting-side encoding means for encoding the original speech signal while maintaining an internal state based on the first pseudo signal, and encoding by the transmitting-side encoding means The first voice is generated by compressing the silent section of the voice code. A transmission side voice code generating means for generating a code, wherein the relay node, a relay side background noise generating means for generating a second pseudo code imitating background noise, and a silent section of the first voice code. A voice coding transmission system, comprising: a relay side voice code generating means for inserting the second pseudo code to generate the second voice code. 7. A transmission end for encoding a voiced section of an original voice signal and outputting a first voice code generated by performing silence compression to a first transmission line, and from the first transmission line. A relay node that outputs a second voice code generated by interpolating background noise to a silent section of the original voice signal based on the received first voice code to a second transmission path; A voice coding transmission system comprising a receiving end for decoding the second voice code received from a transmission path to reproduce the original voice signal, wherein the transmitting end is a transmitter code for encoding the original voice signal. And a transmission side voice code generation unit that compresses a silent section of the voice code encoded by the transmission side encoding unit to generate the first voice code, wherein the relay node comprises: Decode the first speech code to produce a speech signal Relay-side decoding means, relay-side background noise generation means for generating a pseudo signal simulating background noise, and relay-side background for inserting the pseudo signal in the silent section of the voice signal generated by the relay-side decoding means. Noise inserting means, relay side encoding means for encoding the voice signal obtained by the relay side background noise inserting means, voice code encoded by the relay side encoding means, and the first voice code And a relay side voice code generating means for generating the second voice code by inserting into the silent period and the transition period immediately after switching from the voice to the voice. 8. The relay node further comprises a timer for counting the transition section, and the relay-side voice code generation means determines the end timing of the transition section based on the count value of the timer. The voice coding transmission system according to claim 7, characterized in that. 9. The relay node further comprises comparison means for comparing an internal state of the relay side decoding means and an internal state of the relay side encoding means, and the relay side speech code generation means comprises the comparison means. 8. The speech coded transmission system according to claim 7, wherein the end timing of the transition section is determined based on the comparison result of the means. 10. The relay node includes a timer that counts the transition section, a comparison unit that compares an internal state of the relay side decoding unit and an internal state of the relay side encoding unit, and a count of the timer. Further comprising a determining means for determining the end timing of the transition section based on the value and the comparison result of the comparing means, the relay side voice code generating means, based on the determination result of the determining means, 8. The voice coding transmission system according to claim 7, wherein the end timing is determined. 11. The transmission-side background noise generation means and the relay-side background noise generation means generate a digital signal imitating background noise in a silent section as a pseudo voice. Item 10. The voice coding transmission system according to any one of items 10. 12. The transmission-side background noise generation means and the relay-side background noise generation means are memories that store predetermined digital signals, according to any one of claims 1 to 10. The voice coded transmission system described. 13. The voice code according to claim 1, wherein the background noise generation means on the transmission side and the background noise generation means on the relay side are random signal generators. Transmission system. 14. A synchronization signal transmission means for transmitting a synchronization signal indicating the start of a silent section of the original audio signal from the transmission end to the relay node, wherein the relay node receives the synchronization signal, 2. The transmission-side background noise generation means and the relay-side background noise generation means are synchronized with each other.
0. The voice coding transmission system according to any one of 0. 15. The transmitting end further comprises an identification pattern generating means for generating an identification pattern to be superimposed on a silent section of the original audio signal, wherein the relay node recognizes the identification pattern, and the transmission side background. 11. The voice coding transmission system according to claim 1, wherein the noise generating means and the relay side background noise generating means are synchronized. 16. A first voice code generated by encoding a voiced section of an original voice signal and silently compressing the first voice code.
A second voice code generated by interpolating background noise in a silent section of the original voice signal based on a transmission end output to the first transmission line and a first voice code received from the first transmission line. In a voice coding transmission system, comprising: a relay node for outputting to the second transmission line; and a receiving end for decoding the second voice code received from the second transmission line to reproduce the original voice signal. A transmitting side parameter generating means for generating a first parameter signal for generating pseudo background noise; and a transmitting step for encoding the original speech signal while maintaining an internal state based on the first parameter signal. A side encoding means; and a transmission side speech code generating means for compressing a silent section of the speech code encoded by the transmitting side encoding means to generate the first speech code. , Pseudo background noise Relay-side parameter generating means for generating a second parameter signal for use; relay-side encoding means for generating a pseudo code based on the second parameter signal; and a silent section of the first voice code in the silent section. A voice coding transmission system comprising: a relay side voice code generating means for inserting a pseudo code to generate the second voice code. 17. The voice coded transmission system according to claim 16, wherein the transmission side parameter generation means and the relay side parameter generation means are memories that store predetermined digital signals. 18. The voice coded transmission system according to claim 16, wherein the transmission side parameter generation means and the relay side parameter generation means are random code generators. 19. The transmission end further comprises a synchronization signal transmission means for transmitting a synchronization signal indicating the start of a silent section of the original audio signal, wherein the relay node receives the synchronization signal and transmits the synchronization signal to the transmission side. 17. The voice coding transmission system according to claim 16, wherein the parameter generating means and the relay side parameter generating means are synchronized. 20. The transmission end further comprises an identification pattern generating means for generating an identification pattern to be superimposed on a silent section of the original audio signal, wherein the relay node recognizes the identification pattern and transmits the transmission side parameter. 17. The generation means and the relay side parameter generation means are synchronized with each other.
The voice coded transmission system described.