JPH09275391A - Information coder and information decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain communication with high quality when a transmission line state is excellent and not causing interruption even when the transmission line state is not excellent. SOLUTION: A line state calculation circuit 11 estimates a state of line based on a switch signal to select a decoding system A or B of a voice signal from a decoding system selection circuit 21, a CRC error presence signal from a transmission decoding circuit A24, and a CRC error presence signal from a transmission decoding circuit B26, generates the switch signal to select a voice signal coding system A or B and gives the signal to changeover circuits 12, 13. Concretely, the circuit 11 uses four discrimination methods to grasp the state of line and applies selection control to an optimum voice signal coding system A or B. The voice signal coding system A conducts coding placing emphasis onto voice coding performance and the voice signal coding system B conducts coding placing emphasis onto error immunity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information coding apparatus and an information decoding apparatus, and is suitable for, for example, an apparatus for transmitting information using a wireless line in which the transmission line state is likely to change.

[0002]

2. Description of the Related Art At present, VSELP is used as an encoding / decoding system for audio signals in mobile phones and mobile phones.
(Vector Sum Excited Linea
r Predictive Coding: Vector sum excitation linear prediction) and PSI-CELP (Pitch S)
ynchronous Innovation-Cod
eExcited Linear Predictio
(n: pitch synchronization noise excitation linear prediction) and the like are standardized.

In these systems, in order to reduce transmission line errors, transmission line coding information is added in addition to voice coding information for transmission. For example, in VSELP, CRC (Cy) is added to speech coded information of 6.7 kbit / s.
The transmission channel coding information of 4.5 kbit / s is added by the code Redundancy Check) code and the convolutional code, and the information is transmitted as a total of 11.2 kbit / s of information.

[0004]

However, in the above-mentioned method, when the transmission path error exceeds a certain amount, the error cannot be corrected by decoding the transmission path encoded information. In such a case, the audio signal cannot be restored on the receiving side, and in the worst case, it is interrupted.

Therefore, generally, by increasing the amount of transmission coded information, the resistance to a transmission path error becomes stronger.
When the total amount of information is fixed, the amount of speech coded information has to be reduced accordingly, so that there is a problem that the speech coding performance deteriorates.

From the above, an information code which enables high quality communication when the transmission line condition is good and enables communication without interruption even when the transmission line condition is bad There is a demand for realization of an encryption device and an information decoding device.

[0007]

Therefore, the information coding apparatus of the present invention is an apparatus for changing the coding performance for input information according to the code error state in the transmission line, and Coding performance determination control means for determining and controlling the coding performance of the information source coding means and the transmission coding means from the state information, and the information source coding means for coding the input information as the information source based on the above control, Transmission coding means for performing transmission coding for adding transmission error detection information to the information source coded signal based on the above control.

Further, the information decoding device of the present invention performs transmission decoding from the transmission line encoded signal of the information encoding device to generate a transmission decoded signal and detects a state of a code error in the transmission line. A transmission decoding means for outputting information on the state of code error to the encoding performance determination control means of the information encoding device, and an information source decoding means for performing information source decoding from the transmission decoded signal to restore and output the information. Prepare

By adopting such a configuration, the transmission / decoding means performs transmission / decoding, detects the state of the code error in the transmission line, and determines the information on the state of the code error to determine the coding performance of the information coding apparatus. Since it is given to the control means and the coding performance of the information source coding means and the transmission coding means is determined and controlled,
According to the state of the transmission line, the information source coding performance and the transmission coding performance can be changed optimally to enable high quality communication when the transmission line state is good, and the transmission line state is bad. It can even be possible to communicate without interruption.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. Therefore, in the present embodiment, a mode that emphasizes speech coding performance and a mode that emphasizes error resilience are adaptively selected to encode a speech signal.
It is configured to perform decryption.

Specifically, in an audio signal encoding / decoding system in which the sum of the audio encoded information amount and the transmission error detection / correction information amount is constant, the input audio signal is encoded at Sa bits / second. , Ca bit / second error detection / correction code is added to the audio signal encoding system A, and the input audio signal is S
Encoded at b bits / second, Cb bits / second error detection
A voice signal coding system B to which a correction code is added (however, Sa
> Sb, Sa + Ca = Sb + Cb) and a circuit for adaptively selecting the audio signal encoding system A or B, and using the encoding information of the other side sent from the transmission line and the output information of the decoder, A voice signal coding apparatus is configured so that a voice signal coding system A or B can be adaptively selected to code / transmit an input voice signal.

Further, in a voice signal coding / decoding system in which the sum of the voice coded information amount and the transmission error detection / correction information amount is constant, the Sa bit / s voice encoded information and the Ca bit / sec. A voice signal decoding system A that decodes a voice signal from the transmission error detection / correction information, and a voice signal decoding from the Sb bit / sec voice coding information and the Cb bit / sec transmission error detection / correction information. Audio signal decoding system B
And a circuit for selecting the audio signal decoding system A or B based on the encoding information of the other side obtained from the transmission path, and the audio signal decoding system A based on the transmission information from the above audio signal encoding device. Alternatively, the audio signal decoding apparatus is configured to adaptively select B and decode the audio signal.

Next, the configurations and operations of the above speech signal coding apparatus and speech signal decoding apparatus will be described in detail. FIG.
It is a functional block diagram of a speech signal encoding device and a speech signal decoding device. In FIG. 1, the speech signal coding apparatus includes a line state calculation circuit 11, switching circuits 12 and 13, a speech signal coding circuit A14, a transmission coding circuit A15, a speech signal coding circuit B16, and a transmission circuit. It is composed of an encoding circuit B17. The audio signal encoding circuit A14 and the transmission encoding circuit A15 form an audio signal encoding system A. The audio signal encoding circuit B16 and the transmission encoding circuit B17 form an audio signal encoding system B.

The audio signal decoding apparatus includes a decoding system selection circuit 21.
, Switching circuits 22 and 23, and transmission decoding circuit A24
, Audio signal decoding circuit A25, and transmission decoding circuit B26
And an audio signal decoding circuit B27. The transmission decoding circuit A24 and the audio signal decoding circuit A25 form an audio signal decoding system A. Transmission decoding circuit B2
6 and an audio signal decoding circuit B27 form an audio signal decoding system B.

The voice signal encoding circuit A14 encodes an input voice signal (for example, 64 kbit / sec) to generate a Sa bit / sec (for example, 8 kbit / sec) voice code Csa, and a transmission encoding circuit. Give to A15.

The transmission encoding circuit A15 outputs from Sa bits / second (for example, 8 k bits / second) speech code Csa to Ca bits / second (for example, 8 k bits / second) from the speech signal encoding circuit A14.
A CRC / convolutional code of 3.2 kbit / sec) is added to generate a transmission code Cat of Sa + Ca bits / sec (for example, 11.2 kbit / sec) and output to the transmission line 3b.

With such a configuration, the audio signal encoding system A
Is a configuration for placing importance on speech coding performance rather than error resilience.

The voice signal encoding circuit B16 encodes an input voice signal (for example, 64 kbit / sec) to generate an Sb bit / sec (for example, 4 kbit / sec) voice code Csb, and a transmission encoding circuit. Give to B17.

The transmission coding circuit B17 adds a CRC / convolutional code of Cb bits / sec (for example, 7.2 kbits / sec) from the speech code Csb from the speech signal coding circuit B16 and adds Sb + Cb bits / sec. (For example, 11.
2 kbit / sec) transmission code Cbt is generated to generate the transmission line 3
to b.

With such a configuration, the voice signal coding system B
Is a configuration for emphasizing error resilience in the transmission path rather than speech coding performance.

The coding speed S of the audio signal coding system A
a> the coding rate Sb of the voice signal coding system B, and the total coding amount in the voice signal coding system A and the voice signal coding system B is constant in both systems in the relationship of Sa + Ca = Sb + Cb.

The decoding system selection circuit 21 uses the audio signal decoding system A based on the encoding information of the other side obtained from the upstream transmission line 3a.
Alternatively, a switching circuit 2 for switching the switching signal for selecting B
2, 23 and the line state calculation circuit 11.

When the switching circuit 22 is given a switching signal for selecting the audio signal decoding system A, the switching circuit 22 gives the encoding information of the other side obtained from the upstream transmission line 3a to the transmission decoding circuit A24. Further, when the switching circuit 22 is given a switching signal for selecting the audio signal decoding system B, the switching circuit 22 gives the coding information of the other side obtained from the upstream transmission path 3a to the transmission decoding circuit B26.

When the switching circuit 23 is given a switching signal for selecting the audio signal decoding system A, the switching circuit 23 selectively outputs the audio signal from the audio signal decoding circuit A25. Also,
When the switching circuit 23 is given a switching signal for selecting the audio signal decoding system B, the audio signal decoding circuit B2.
The audio signal from 7 is selectively output.

The transmission decoding circuit A24 performs transmission decoding from the transmission line code from the upstream transmission line 3a, confirms the presence or absence of a CRC error, and determines the presence or absence of this CRC error by the line state calculation circuit 1
1, and the transmission decoded signal of Sa bits / second is given to the audio signal decoding circuit A25. The audio signal decoding circuit A25 restores the audio signal by performing audio signal decoding from the Sa decoded bits / second transmission decoded signal from the transmission decoding circuit A24.

With such a configuration, the audio signal decoding system A is
Performs speech signal decoding with emphasis on speech coding performance rather than error resilience.

The transmission decoding circuit B26 performs transmission line decoding from the transmission code from the upstream transmission line 3a, confirms the presence or absence of a CRC error, and checks the presence or absence of this CRC error for the line state calculation circuit 1
1 and the transmission decoded signal of Sb bits / second is given to the audio signal decoding circuit B27. The audio signal decoding circuit B27 restores the audio signal by performing audio signal decoding from the Sb bit / sec transmission decoded signal from the transmission decoding circuit B26.

With such a configuration, the audio signal decoding system B is
Performs speech signal decoding that emphasizes error resilience rather than speech coding performance.

The line state calculation circuit 11 receives a switching signal from the decoding system selection circuit 21 for selecting the audio signal decoding system A or B, a CRC error presence signal from the transmission decoding circuit A 24, and a transmission decoding circuit B 26. The line state is estimated from the CRC error presence / absence signal of (1) and a switching signal for selecting the audio signal coding system A or B is generated and given to the switching circuits 12 and 13.

Specifically, the line state calculation circuit 11 grasps the line state by the following four methods and selectively controls the optimum audio signal coding system A or B. That is, (1) In the decoding system selection circuit 21, "the audio signal decoding system A is selected"
If no CRC error is detected by the transmission / decoding circuit A24, a switching signal is given to the switching circuits 12 and 13 so as to select the audio signal coding system A.

(2) In the decoding system selection circuit 21, when "speech signal decoding system A is selected" and a CRC error is detected by the transmission decoding circuit A24, switching is made to select the speech signal coding system B. Signal switching circuit 12,
Give to 13.

(3) When the audio signal decoding system B is selected in the decoding system selection circuit 21 and no CRC error is detected by the transmission decoding circuit B26, when no CRC error is detected continuously more than once. Gives a switching signal to the switching circuits 12 and 13 so as to select the speech signal coding system A, and otherwise switches the switching signal so as to select the speech signal coding system B.
Give to 2 and 13.

(4) When the voice signal decoding system B is selected in the decoding system selecting circuit 21 and a CRC error is detected by the transmission decoding circuit B26, the voice signal encoding system B is switched to the selected one. Signal switching circuit 12,
Give to 13.

The switching circuit 12 is the line state calculation circuit 1
When the switching signal is given from 1 so as to select the voice signal encoding system A, the input voice signal is given to the voice signal encoding circuit A14. Further, when the switching circuit 12 is given a switching signal from the line state calculation circuit 11 so as to select the voice signal coding system B, it gives the input voice signal to the voice signal coding circuit B16.

The switching circuit 13 is the line state calculation circuit 1
When a switching signal is given from 1 to select the audio signal encoding system A, the transmission code Cat from the transmission encoding circuit A15 is selectively output to the downlink transmission line 3b. Further, when the switching circuit 13 receives a switching signal from the line state calculation circuit 11 so as to select the voice signal coding system B, the transmission code Cbt from the transmission coding circuit B17.
Is selectively output to the downlink transmission line 3b.

(Operation): Next, the operation of FIG. 1 will be described. First, for example, when information encoded by the voice signal encoding system B from the other side voice signal encoding device side (same configuration as in FIG. 1) is given to the voice signal decoding device 1 from the upstream transmission path 3a, decoding is performed. The switching signal for judging the selection of the system by the system selection circuit 21 and selecting the audio signal decoding system B is the switching circuits 22 and 23 and the line state calculation circuit 11
And given to.

As a result, the switching circuit 22 gives the encoded information from the upstream transmission line 3a to the transmission / decoding circuit B26. The result of the CRC check by the transmission decoding circuit B26 is given to the line state calculation circuit 11 and the transmission decoded signal is given to the voice signal decoding circuit B27. The audio signal decoded and restored by the audio signal decoding circuit B27 is output as synthetic audio through the switching circuit 23.

Further, in the line state calculation circuit 11, since the switching signal for selecting the voice signal decoding system B is given from the decoding system selecting circuit 21, the transmission decoding circuit B26.
If there is no error according to the result of the CRC check in the above, the switching signal is switched so as to select the audio signal coding system A when no error is continuously detected by the determination method of (3). Switching signals are supplied to the circuits 12 and 13, and in other cases, switching signals are supplied to the switching circuits 12 and 13 so as to selectively maintain the audio signal coding system B. Also, the audio signal decoding system B is selected in the decoding system selection circuit 21, and C is selected by the transmission decoding circuit B26.
Even when an RC error is detected, the switching signals are switched to the switching circuits 12 and 1 so as to selectively maintain the audio signal coding system B.
3 given.

When no error is continuously detected, the audio signal encoding system A is selected and the input audio signal is encoded with emphasis on the audio encoding performance rather than the error resilience. The encoded information is output to the downlink transmission line 3b. On the other hand, when a CRC error is detected, the audio signal encoding system B is selectively maintained, and the input audio signal is encoded by placing more importance on error resilience than speech encoding performance and encoding information. Is output to the downlink transmission line 3b.

(Effects of the Embodiment of the Present Invention) According to the above-described embodiments of the present invention, the transmission decoding circuit performs transmission decoding and detects the presence (or state) of a code error in the transmission line. And give it to the line state calculation circuit of the encoder,
When the audio signal coding system A or B is determined and switching control is performed, the information source coding performance and the transmission coding performance are optimally changed according to the status of the transmission line, and the transmission path condition is good. Can communicate with high quality and can communicate without interruption even when the state of the transmission path is bad.

(Other Embodiments): (1) In the above embodiments, the line status is determined from the CRC check result by transmission decoding, receiving the coding information from the other party, selecting the decoding system. Is determined and the audio signal encoding system A or B of the own device is selected from this determination result.
As another configuration, receiving the coding information from the other party, selecting the decoding system, and selecting the voice signal coding system A or B of the own device from the result of judging the line state from the CRC check result by transmission decoding. It is also preferable that the determination result is sent back to the speech coding apparatus of the partner apparatus to optimally switch the coding system A or B of the partner speech coding apparatus, instead of performing.

(2) In addition to VSELP, PSI-CELP, RPE-LT can be used as a voice encoding / decoding system.
P (equal-interval pulse excitation with long-term prediction: Regular P
ulse excitation with long
Term Prediction), LD (Low
Delay) -CELP (low delay CELP), CS (C
onjugate Structure) -CELP
A hybrid coding method such as (conjugate structure CELP) can also be applied. In addition, as waveform encoding methods, ADPCM (adaptive difference PCM), Em (Embed)
ed) -ADPCM (embedded ADPCM), AP
C (Adaptive Predictive Cod
ing) -AB (with Adaptive Bit)
Allocation (adaptive bit allocation adaptive prediction), SB (Sub-Band) -ADPCM (band division ADPCM), SBC (Sub-Band Cod)
ing) + ATC (Adaptive Transfer)
rm Coding) (band division + transform coding) can also be applied. In addition, as a spectrum coding method, PARCOR (Partial Autocorr) is used.
relation: partial autocorrelation), LSP (Line
Spectrum Pair: line spectrum pair) or the like can also be applied.

(3) Further, as the error correction coding / decoding method, a block coding / decoding method can be applied in addition to the convolutional coding / decoding method. For example, as a code suitable for random error correction, for example, BCH (Bo
se-Chaudhuri-Hocquenghem)
A code, a majority logic code or the like can also be used. In addition, as a coding method suitable for burst error correction, for example, a Reed-Solomon coding method, a Fire coding method,
A shortened cyclic code or the like can also be applied.

(4) Furthermore, in the above-described embodiment, the encoding system and the decoding system each have two stages of two stages, but it is also preferable to have three systems of three stages or more.

(5) Further, in the configuration of FIG. 1 described above, the line state calculation circuit 11 is provided in the voice signal encoding device 1,
In another form, it is also preferable to provide a circuit for analyzing the line state on the side of the audio signal decoding device 2 and select the audio signal encoding circuit A or B from this circuit.

[0046]

As described above, according to the present invention, the coding performance of the information source coding means and the transmission coding means is determined and controlled. Therefore, according to the state of the code error of the transmission line, the information source coding is performed. By changing the performance and the transmission coding performance optimally, it is possible to perform high quality communication when the transmission line condition is good, and to perform communication without interruption even when the transmission line condition is bad. You can enable it.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of a voice signal encoding device and a voice signal decoding device according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Voice signal encoding device, 2 ... Voice signal decoding device, 3 ...
Transmission line, 11 ... Line state calculation circuit, 12, 13 ... Switching circuit, 14 ... Voice signal coding circuit A, 15 ... Transmission coding circuit A, 16 ... Voice signal coding circuit B, 17 ... Transmission coding circuit B , 21 ... Decoding system selection circuit, 22, 23 ... Switching circuit, 24 ... Transmission decoding circuit A, 25 ... Voice signal decoding circuit A, 26 ... Transmission decoding circuit B, 27 ... Voice signal decoding circuit B.

Claims (5)

[Claims] 1. An information coding apparatus for changing coding performance for input information according to a code error state in a transmission line, comprising: information source coding means and a transmission code based on information of a code error state in the transmission line. Coding performance determination control means for determining and controlling the coding performance of the coding means, information source coding means for coding the input information based on the above control, and transmission error detection for this information source coded signal. An information encoding device, comprising: a transmission encoding unit that performs transmission encoding for adding usage information based on the above control. 2. The coding performance determination control means, when there are few code errors in the transmission line, increases the information source coding speed and lowers the coding speed of the error detection information so that the coding error in the transmission line is reduced. The information encoding device according to claim 1, wherein when the number is large, the information source encoding speed is controlled to be low and the error detection information encoding speed is to be increased. 3. An information coding device for changing coding performance for input information according to a code error state in a transmission line, wherein the information source code is for coding the input information as a source based on a control signal for coding performance. An information coding device comprising: a coding means; and a transmission coding means for carrying out transmission coding for detecting a transmission error on the information source coded signal based on a control signal for the coding performance. 4. A code error state is detected by performing transmission decoding from the transmission coded signal of the information coding apparatus according to claim 1 or 2 to generate a transmission decoded signal and detecting a code error state in a transmission line. The information decoding means for outputting the information to give to the coding performance determination control means of the information coding device, and the information source decoding means for performing information source decoding from the transmission decoded signal to restore and output the information. A characteristic information decoding device. 5. The transmission coded signal of the information source coding apparatus according to claim 3 is transmitted and decoded to generate a transmission decoded signal, and a state of a code error in a transmission line is detected to detect this code error. A transmission decoding means for generating and outputting a control signal for the coding performance of the information source coding device from the state information; and an information source decoding means for performing information source decoding from the transmission decoded signal and restoring and outputting the information. A characteristic information decoding device.