JP3125511B2 - Code decoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to code decoding in the case where a speech signal and a non-speech signal such as a facsimile or a modem, or speech signals having different frequency bands and audio signals are inputted alternately. It relates to improvement of the device.

[0002] In recent years, a line through which an audio signal has passed
When a non-speech signal such as an AX or a modem is passed, and encoding and decoding are performed, a speech uses an encoder and a decoder suitable for speech, and a non-speech uses an encoder and a decoder suitable for non-speech. It has become.

[0003] For voice, for example, for a voice in a 4 KHz band and an audio signal in an 8 KHz band, an encoder and a decoder suitable for each have come to be used. In this case, for example, when speech is switched to non-speech, it is desired that the period in which the encoder and the decoder are of different types be eliminated and no noise be output from the output of the decoding unit.

[0004]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional code decoder, and FIG. 5 is a time chart of each part in FIG.

FIGS. 4 and 5 show an encoding / decoding apparatus in which a speech signal and a non-speech signal are alternately inputted as shown in FIG. 5 (A). , And the non-speech signal is coded by the non-speech coder 33.

However, the audio signal encoded by the decoding section 40 must be decoded by an audio decoder 43, and the encoded non-audio signal must be decoded by a non-audio decoder 44. For this reason, the type of the audio signal or the non-audio signal must be notified to the decoding unit 40. As means for notifying, a separate synchronization signal is prepared for each of the audio and non-audio side, and the decoding unit 40 Is used to decode the code on the side where synchronization has been established.

That is, the output of the speech encoder 32 is provided with a synchronization signal adding unit 34 for adding a first synchronization signal, and the output of the non-speech encoder 33 is provided with a second synchronization signal different from the first synchronization signal.
Is provided, and the outputs of the synchronization signal adding units 34 and 35 are input to the selector 36.

On the other hand, the type detector 31 detects whether the input signal is an audio signal or a non-audio signal, and outputs an H-level signal when the input signal is an audio signal and an L-level signal when the input signal is a non-audio signal. Selector 36, speech encoder 32, non-speech encoder 3
3 and the synchronizing signal adding units 34 and 35. When the signal is at the H level, the speech encoder 32 and the synchronizing signal adding unit 34 are operated.
At the time of L level, the non-speech encoder 33 and the synchronization signal adding unit 3
5 is operated, and in the selector 36, as shown in FIG. 5B, in the case of an audio signal, the synchronization signal adding section 34 on the audio signal side is used.
Is selected, and in the case of a non-speech signal, the output of the synchronization signal adding unit 35 on the non-speech signal side is selected and output.

When the signal shown in FIG. 5 (B) is input from the code signal output unit 30 to the decoding unit 40, the synchronization detection unit 41, which synchronizes with the first synchronization signal, outputs the signal from the speech encoder 32 side.
Synchronization is established while the first synchronization signal is being input, but when switching to the second synchronization signal input on the non-speech encoder 33 side, the forward synchronization protection period shown in FIG. When the synchronization is detected through the first synchronization signal input on the voice encoder 32 side, synchronization detection is performed through the backward synchronization protection period shown in FIG. 5C. In FIG. 5C, an H level indicates a synchronization period, and an L level indicates an out-of-synchronization period.

[0010] The synchronization detecting section 42, which synchronizes with the second synchronization signal, detects out-of-synchronization while the first synchronization signal is being input on the speech encoder 32 side. When switching to the second synchronization signal input on the device 33 side, FIG.
(D) Synchronization is established after the backward synchronization protection period shown in a of FIG. 5, and when switching to the first synchronization signal input on the voice encoder 32 side occurs, the synchronization is lost through the forward protection period shown in b of FIG. To detect. In FIG. 5D, an H level indicates a synchronization period, and an L level indicates an out-of-synchronization period.

The audio decoder 43 receives the output of the synchronization detector 41 and decodes the encoded signal of the audio signal while the synchronization indicated by the H level in FIG.
5 and the non-speech decoder 44 receives the output of the synchronization detector 42 and decodes the non-speech-encoded signal while the synchronization indicated by the H level in FIG. 5D is established. It is input to the selector 45.

The selection signal output section 46 includes a synchronization detection section 41,
It monitors the detection signal at 42 and notifies the selector 45 to output the output of the decoder on the synchronization establishment side. That is, signal 4
When 1-1 is at the H level, the selection signal of the output of the selection signal output section 46 is at the H level as shown in FIG. 5E, and the selector 45 selects and outputs the output of the audio decoder 43, and outputs the signal. 4
When 2-1 is at the H level, the selection signal of the output of the selection signal output section 46 is at the L level as shown in FIG. 5E, and the selector 45 selects and outputs the output of the non-speech decoder 44.

When the signals 41-1 and 42-1 are both at the H level, the previous state is maintained.

[0014]

However, FIG.
The hatched portion in (F) indicates that the encoder of the code signal output unit 30 is for a speech signal, for example, and that the decoder of the decoding unit 40 is for a non-speech signal and is not a corresponding one. Therefore, there is a problem that noise is generated during this time.

An object of the present invention is to provide a code decoding apparatus which does not output noise from the output of the decoding unit.

[0016]

FIG. 1 is a block diagram showing the principle of the present invention. As shown in FIG.
A type detection unit 1 for detecting the type of the second type of signal and inputting the first and second types of detection signals to the delay signal output unit 7 and the first and second synchronization signal adding units 4 and 5 And first and second encoders 2 and 3 for encoding input first and second types of signals, respectively, and a first synchronization signal to an encoded output of the first encoder 2. And when the second type detection signal from the type detection unit 1 is input, the first synchronizing signal addition is stopped.
And a second synchronizing signal added to the encoded output of the second encoder 3, and when the first type detecting signal from the type detecting section 1 is input, the synchronizing signal is added. A second synchronizing signal adding unit that stops, a first selector that inputs and selects and outputs the outputs of the first and second synchronizing signal adding units, and an output of the type detecting unit; The first and second type detection signals are delayed by a forward synchronization protection period, and the delayed output is input to the first selector 6 to select an output, and the first and second encoders 2 are selected. , 3 to start coding when a corresponding type detection signal is input, and stop coding when a non-corresponding type detection signal is input; The output of the output unit 10 is input, and the input first and second synchronization signals are used. Decoding is started by the first and second synchronization detectors 21 and 22 for synchronizing and outputting the synchronization detection signal, respectively, and the synchronization detection signal input of the output of the first synchronization detector 21 to output the synchronization loss signal. , The decoding is started by the input of the synchronization detection signal of the first decoder 23 that outputs the decoded signal and the output of the second synchronization detection unit 22, and the decoding is performed by the out-of-sync signal. A second decoder 24 for stopping the decoding and outputting the decoded signal, and a second decoder 24 for inputting and selecting and outputting the outputs of the first and second decoders 23 and 24.
Selector 25 and the first and second synchronization detectors 21 and
And a decoding unit 20 having a selection signal output unit 26 that inputs a second synchronization detection signal and outputs a signal for selecting the output of the second selector 25.

[0017]

According to the present invention, for example, even if the input first type signal is switched to the second type signal, the forward synchronization protection period is encoded by the first type encoder 2, and During the forward synchronization protection period, the first synchronization signal is transmitted without being added by the synchronization signal adding unit 4.

In the synchronization detecting section 21 of the decoding section 20, the synchronization has been established, and the decoding of the first type of signal has been performed by the decoder 23. However, the synchronization is lost due to the lack of the first synchronizing signal. , And out of synchronization is established when the forward synchronization protection period elapses, and the decoder 23 stops decoding.

At this time, the selector 6 of the code signal output unit 10 converts the signal of the second type into a signal encoded by the encoder 3,
The synchronization signal adding unit 5 selects the signal side to which the second synchronization signal has been added, and inputs it to the decoding unit 20.

Then, synchronization is started to be pulled in by the synchronization detecting section 22 and synchronization is established after the backward synchronization protection period, and the decoder 24 starts decoding. At this time, the selector 25 outputs the output of the selection signal output section 26. The signal which has selected the output of the decoder 23 is switched to the selection of the output of the decoder 24 according to the signal.

That is, since the switching of the encoder is performed with a delay of the forward synchronization protection period even if the type of the input signal is changed, the signal coded by the encoder is decoded to decode different types of signals. The output from the decoding unit 20 does not generate noise.

[0022]

FIG. 2 is a block diagram of an encoding / decoding apparatus according to an embodiment of the present invention, and FIG. 3 is a time chart of each section in FIG.

FIG. 2 is also similar to FIG.
1 shows an encoding / decoding apparatus in which a speech signal and a non-speech signal are alternately input as shown in FIG. 1. The speech signal is encoded by the speech coder 2, and the non-speech signal is encoded by the non-speech encoder 3 I do.

A synchronization signal is added to the output of the speech coder 2 so that the decoding unit 20 informs whether the data has been coded by the speech coder 2 or the non-speech coder 3. The first synchronizing signal is added by the unit 4, and the second synchronizing signal different from the first synchronizing signal is added to the output of the non-speech encoder 3 by the synchronizing signal adding unit 5 and output. I have.

However, the timing of encoding by the speech encoder 2 and the non-speech encoder 3, the timing of adding the synchronization signal by the synchronization signal adding units 4 and 5, and the timing of selecting by the selector 6 will be described below. In this way, no noise is generated from the output of the decoding unit 20.

The type detector 1 detects whether the signal is a voice signal or a non-voice signal, and outputs a 1 signal when a voice signal is detected and a 0 signal when a non-voice signal is detected. These are sent to the synchronization signal adding units 4 and 5.

The timer 7 delays the input 1 or 0 signal for the forward synchronization protection period, and inputs it to the speech encoder 2, the non-speech encoder 3 and the selector 6, and the speech encoder 2 inputs the delayed 0 signal. In other words, the encoding is stopped as shown in FIG. 3B with a delay of the forward synchronization protection period from the input of the non-speech signal, the coding is started in the non-speech encoder 3, and the selector 6 is synchronized when the signal of 0 is input. The output of the signal adding section 5 is selected, and the output of the synchronization signal adding section 4 is selected when one signal is input.

On the other hand, when a signal of 0 for non-speech signal detection is input from the type detection unit 1 to the synchronization signal addition unit 4, the one to which the first synchronization signal is added is stopped, and the synchronization signal addition unit 5 stops.
When the signal of the audio signal detection 1 is input from the type detection unit 1, the one to which the second synchronization signal is added is stopped.
That is, the period shown by the diagonal lines in FIG. 3B is a period in which no synchronization signal is added.

That is, as shown in FIG. 3C, the output of the selector 6 is encoded by the audio encoder 2 during the forward synchronization protection period even if the input audio signal is switched to a non-audio signal.
The forward synchronization protection period is transmitted as a missing first synchronization signal. Even if the input non-speech signal is switched to a speech signal, the forward synchronization protection period is encoded by the non-speech encoder 3, The protection period is transmitted as a missing second synchronization signal and input to the decoding unit 20.

In the synchronization detecting section 22 of the decoding section 20, the synchronization is established when the backward synchronization protection period period shown in a of FIG. Although the non-speech coded signal is decoded by the speech decoder 24, the selection signal is output from the selection signal output unit 26, and the selector 25 selects the output of the non-speech decoder 24.
Loss-of-synchronization starts to be detected when the second synchronization signal is lost as shown by the hatched portion in FIG. 3B, and the loss of synchronization is determined when the forward synchronization protection period shown by b in FIG. 3C has passed. , The decoding of the non-speech decoder 24 is stopped.

In the synchronization detecting section 21, the first signal on the audio signal side is output.
3C, the synchronization is established after the backward synchronization protection period shown in FIG. 3C, the audio decoder 23 decodes the audio coded signal, and the selection signal output unit 26 The selector 25 outputs a selection signal, and the selector 25 selects the output of the audio decoder 23. However, when the first synchronization signal is lost as shown by the hatched portion in FIG. When the forward protection period indicated by b in FIG. 3C has passed, the loss of synchronization is determined, and the decoding of the audio decoder 23 is stopped.

That is, since the switching of the encoder is performed with a delay of the forward synchronization protection period even if the type of the input signal is changed, for example, the signal coded by the voice coder 2 decodes the non-voice signal. Is not decoded by the non-speech decoder 24, and no noise is emitted from the output of the decoding unit 20.

During the backward synchronization protection period, the output of the decoder is silent. The above description has been made with reference to the input of the audio signal and the non-audio signal. However, this can be applied to the case where the audio signal of the 4 kHz band and the audio signal of the 8 kHz band are alternately input. It is also possible to realize by taking in.

[0034]

As described above in detail, according to the present invention, when the type of the input signal changes, the encoder and the decoder in the code signal output section and the decoding section change the signal of the same type. Encoding and decoding can be performed, and there is an effect that noise generation can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention;

FIG. 2 is a block diagram of a code decoding apparatus according to an embodiment of the present invention;

3 is a time chart of each part in FIG. 2,

FIG. 4 is a block diagram of a conventional code decoding apparatus;

FIG. 5 is a time chart of each part in FIG. 4;

[Explanation of symbols]

 1, 31 is a type detection unit, 2 is an encoder and a speech encoder, 3 is an encoder and a non-speech encoder, 4, 5, 34, and 35 are synchronization signal addition units, 6, 25, 36, and 45 are selectors, 7, a delay signal output means, a timer, 10, 30 a code signal output unit, 20, 40 a decoding unit, 21, 22, 41, 42 a synchronization detection unit, 23 a decoder, a speech decoder, 24 a decoder , A non-speech decoder, 26 and 46 are selection signal output units, 32 is a speech coder, 33 is a non-speech encoder, 43 is a speech decoder, and 44 is a non-speech decoder.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-33454 (JP, A) JP-A-59-167138 (JP, A) JP-A-64-72637 (JP, A) JP-A-2- 211728 (JP, A) JP-A-3-172035 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04J 3/17 H04J 3/06 H04L 7/08 H04M 11/00 303

Claims (1)

(57) [Claims] A detecting means for detecting a type of the first and second types of signals which are alternately inputted, and outputting a detection signal of the first and second types to the delay signal output means (7) and the first and second signals; A type detecting unit (1) input to the synchronization signal adding unit (4, 5); a first and a second encoder (2, 3) for encoding the input first and second type signals, respectively; A first synchronization signal is added to the encoded output of the first encoder (2), and the addition of the synchronization signal is stopped when the second type detection signal from the type detection unit (1) is input. 1 synchronization signal adding section (4), and a second synchronization signal added to the encoded output of the second encoder (3), and a first type detection signal from the type detection section (1). , A second synchronizing signal adding unit (5) that stops adding a synchronizing signal, and inputs and selects and outputs the outputs of the first and second synchronizing signal adding units (4, 5). A first selector (6) that performs a forward synchronization protection period on the first and second type detection signals output from the type detection unit (1), and outputs the delayed output to the first selector (6). ) To select an output and to input to the first and second encoders (2, 3), the corresponding type detection signal input side starts coding, and the corresponding type detection signal input side Is a code signal output unit (10) having the delay signal output means (7) for stopping encoding, and the first and second synchronizations which input and output the output of the code signal output unit (10) First and second synchronization detectors (21, 2) that synchronize with each signal and output a synchronization detection signal, respectively.
2) and a first decoding that starts decoding by inputting a synchronization detection signal of the output of the first synchronization detection unit (21), stops decoding by an out-of-sync signal, and outputs a decoded signal. Container (2
3) and a second decoding that starts decoding by inputting a synchronization detection signal of the output of the second synchronization detection unit (22), stops decoding by an out-of-sync signal, and outputs a decoded signal. Container (2
4), a second selector (25) for inputting and selecting and outputting the outputs of the first and second decoders (23, 24); and the first and second synchronization detectors (21, And a selection signal output unit (26) for receiving the synchronization detection signal of (22) and outputting a signal for selecting the output of the second selector (25). Encoding / decoding device.