JP2972429B2 - Audio encoding / 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 a speech encoding / decoding apparatus used in a transmission system for transmitting not only speech signals but also facsimile signals.

[0002]

2. Description of the Related Art With the spread of digital exclusive lines, digital networks in companies have been actively constructed. At the same time, the economics of the line are being pursued, and the bit rate of the audio encoding / decoding device is also being reduced from this demand. However, the reduction of the bit rate is performed from the viewpoint of paying attention to the characteristics of the audio signal and not impairing its quality as much as possible. Therefore, there is no problem in encoding the audio signal, but there is a problem in that the transmission quality of a non-audio signal such as a facsimile signal is degraded. That is, such coding has been one obstacle when constructing a network that handles telephones and facsimiles without distinction.

In order to solve such a problem, there has been proposed a technique for switching an encoder according to a signal to be transmitted. In this proposal, the encoding unit includes a G3 facsimile demodulator in addition to the speech encoder. Here, G3
The facsimile demodulator is for converting a G3 facsimile signal specified by CCITT (International Telegraph and Telephone Consultative Committee) into digital data and transmitting the digital data.

[0004] Further, in the proposed device, the decoding unit includes a G3 facsimile modulator in addition to the speech decoder.
When the received digital data is G3 facsimile data, transmission of the G3 facsimile signal is realized by converting the digital data into a modem signal by a G3 facsimile modulator.

[0005]

However, in such a proposed device, it is necessary to add predetermined information to the frame data transmitted from the transmitting side and transmit the frame data. Such information includes information for identifying whether the frame data is voice parameter data or G3 facsimile data, and information indicating the type (for example, CCITT V21 or V29 / V27ter) in the case of G3 facsimile data. There is information indicating the number of data. Due to the addition of such information, there is a problem that, for example, even if the line speed is 8000 bps (bits / second), only facsimile high-speed data of 4800 bps or less can be actually transmitted.

An object of the present invention is to provide a speech encoding / decoding apparatus capable of transmitting a facsimile signal at a higher speed.

[0007]

According to the first aspect of the present invention, (a) signal discriminating means for discriminating whether an input signal is an audio signal or a facsimile signal, and an audio code for encoding the input audio signal. Encoding means, demodulating means for demodulating an input facsimile signal, and encoding or demodulating a signal one by one in a predetermined fixed-length frame.
Incorporated in the synchronizing signal generating means for generating a frame synchronizing signal as a separator in transmitting, fixed length frame signal identification data for distinguishing the observed sound signal and the when the signal discriminating means has determined that the facsimile signal to Prescribed
An encoding section that includes a data transmitting means for incorporating in transmitting the position, (b) this is connected with the encoding unit and the digital line, a frame synchronization detector for detecting frame synchronization, fixed length that each of the The place mentioned above of the frame
Detection means for determining whether or not identification data is incorporated in the fixed position ; voice decoding means; facsimile modulation means; and facsimile modulation means for a frame determined to have identification data incorporated by the detection means. A speech output unit for outputting a modulated signal and a signal output unit for outputting a signal decoded by the audio decoding unit for a frame in which the identification data is not incorporated, in the audio encoding / decoding apparatus. Let it.

That is, according to the first aspect of the present invention, an audio signal or a facsimile signal is incorporated in a frame of a predetermined fixed length one by one and transmitted in order, and the identification data indicating the facsimile signal is transmitted as an overhead frame. Is transmitted in a predetermined position .

According to the second aspect of the present invention, when facsimile high-speed data is incorporated in a frame to be transmitted later instead of facsimile low-speed data, a special frame in which the identification data is identification data for starting facsimile high-speed data transmission is transmitted. The frame transmission means for starting facsimile high-speed data transmission is arranged in the encoding section, and the decoding section is provided with frame discrimination means for discriminating this special frame from other frames.

That is, according to the second aspect of the present invention, immediately before a frame at which facsimile high-speed data transmission is started,
By transmitting a special control frame indicating the start of facsimile high-speed data transmission, it is possible to reduce the number of bits of identification data incorporated in each frame.

According to the third aspect of the present invention, it has been clarified that the present invention can be applied to, for example, a G3 facsimile signal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows the configuration of a speech encoding / decoding apparatus according to an embodiment of the present invention. This device comprises an encoding unit 12 connected to an input terminal 11 and an output terminal 1
3 and a digital line 15 connecting the encoding unit 12 and the decoding unit 14 to each other.

The encoding unit 12 includes a speech encoder 17, a G3 facsimile demodulator 18, a G3 facsimile signal detector 19 which receives a signal supplied from the input terminal 11, a frame synchronization generator 21, and a G3 control unit. A frame generator 22 and a multiplexer 23 are arranged. That is, if the signal input from the input terminal 11 is a speech signal, the signal is encoded by the speech encoder 17 into speech parameters and input to the multiplexer 23. The input signal is G3
If it is a facsimile signal, G3 facsimile demodulator 1
The data is converted into facsimile data by 8 and input to the multiplexer 23.

The G3 facsimile signal detector 19 detects the G3 facsimile signal.
The facsimile signal is detected, and predetermined control is performed according to the detection operation. That is, first, when the input signal is a voice signal, the multiplexer 23 is controlled so that the input from the voice encoder 17 is output to the digital line 15. In the case of a G3 facsimile signal, the multiplexer 23 is controlled so that the input from the G3 facsimile demodulator 18 is output to the digital line 15. Furthermore, a high-speed G3 facsimile signal (CCITT V29 / V2
7ter) or when the reception of the high-speed signal ends, the multiplexer 2 outputs the input from the G3 control frame generator 22 to the digital line 15.
3 is performed.

[0016] The frame synchronization generator 21
And the decoding unit 14 generate a synchronization signal for establishing frame synchronization and supply the synchronization signal to the multiplexer 23.

On the other hand, the decoding unit 14
5, the digital data received by the voice decoder 2
5, input to each of the G3 facsimile modulator 26, G3 control frame detector 27, and frame synchronization detector 28. A switch 29 is disposed on the output side of the audio decoder 25 and the G3 facsimile modulator 26, and the output is supplied to the output terminal 13.

Here, the frame synchronization detector 28 detects the frame synchronization of the digital data received from the digital line 15. The speech decoder 25, the G3 facsimile modulator 26, and the G3 control frame detector 27 operate based on the frame synchronization.

The switch 29 controls the input from the audio decoder 25 to be output to the output terminal 13 if the received digital data is an audio parameter. If the received digital data is G3 facsimile data, control is performed so that the input from the G3 facsimile modulator 26 is output to the output terminal 13.

Further, the G3 control frame detector 27
When a control frame is detected, the G3 facsimile modulator 2
6 is notified of the detection. Upon receiving this notification, the G3 facsimile modulator 26 handles the frame data as G3 facsimile high-speed data until receiving the notification of the next G3 control frame detection.

FIGS. 2 to 5 show the structures of various frame data having a fixed length. In these figures, the symbol "S" represents a frame synchronization signal.

FIG. 2 shows the structure of frame data for an audio frame. When an audio frame is received from the digital line 15 shown in FIG. 1, the frame synchronization detector 28 also shown in FIG. 1 detects the frame synchronization of the audio frame 31. Based on this,
The audio decoder 25 shown in FIG. 1 reproduces an original audio signal based on audio parameters using a built-in synthesis filter (not shown).

By the way, no overhead is arranged in the audio frame 31 to distinguish it from the other frames shown in FIGS. Therefore, the G3 facsimile modulator 26 shown in FIG. 1 cannot detect the overhead in the audio frame 31, and the switch 29 switches the audio decoder 25
Is selected and output to the output terminal 13.

FIG. 3 shows the structure of a G3 facsimile low-speed frame. The G3 facsimile low-speed frame 32 includes a frame synchronization signal S, G3 facsimile identification data, low-speed frame identification data, and G3 facsimile low-speed data.

The digital line 15 shown in FIG.
When a facsimile low speed frame 32 is received, FIG.
The frame synchronization detector 28 shown in (1) detects the frame synchronization. However, the G3 control frame detector 27
Facsimile identification data and low-speed frame identification data are detected. Therefore, in this case, the detection of the G3 facsimile low-speed frame 32 is determined.
In this state, the G3 facsimile modulator 26 modulates the received digital data into a modem signal, and the switch 29 selects this and sends it to the output terminal 13.

FIG. 4 shows the structure of the G3 control frame. The G3 control frame 33 includes a frame synchronization signal S, G3 facsimile identification data, G3 control frame identification data, and control data. The G3 control frame 33 is a frame for processing frame data received thereafter as a G3 facsimile high-speed data frame. That is, the G3 control frame 33 is inserted only when the encoding unit 12 shown in FIG. 1 switches from the low-speed data (CCITT: V21) frame to the high-speed data (CCITT: V29 / V27ter) frame or vice versa. It is supposed to be.

FIG. 5 shows the structure of a G3 facsimile high-speed frame. The G3 control frame 33 includes a frame synchronization signal S, G3 facsimile identification data, and G3 facsimile high-speed data. As described above, the G3 facsimile high-speed frame 34 itself does not have a data structure directly indicating that it is a high-speed frame, and the processing of the frame differs depending on whether the G3 control frame 33 is arranged before this frame.
Also in the case of the G3 facsimile high-speed frame 34, the G3 facsimile modulator 26 modulates the received digital data into a modem signal, and the switch 29 selects this and sends it to the output terminal 13.

In the embodiment described above, the G3 control frame is arranged at the head of the G3 facsimile high-speed frame. Therefore, the control overhead for the G3 facsimile high-speed frame can be reduced. In this embodiment, each of the frames 31 to 34 shown in FIGS. 2 to 5 is composed of 160 bits, and the G3 facsimile high-speed data is composed of 144 bits. As a result, 8000
G3 facsimile high-speed data of 7200 bps can be transmitted over a bps line.

[0029]

According to the invention of claim 1, wherein, as described above, according to the present invention, a predetermined voice signal or facsimile signal
Of frames of fixed length one by one.
Audio and facsimile signals
Even if the
It can be dealt with by changing. Moreover , since no overhead is arranged in the voice frame, there is an effect that voice parameters can be efficiently transmitted.

According to the second aspect of the present invention, a control frame indicating a high-speed data frame is transmitted only once, and all subsequent data frames are processed as facsimile high-speed frames.
The control overhead during the facsimile high-speed frame can be reduced, and the facsimile high-speed data can be transmitted at a high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an outline of a circuit configuration of a speech encoding / decoding device according to an embodiment of the present invention.

FIG. 2 is a frame configuration diagram showing a configuration of an audio frame in the present embodiment.

FIG. 3 is a frame configuration diagram showing a configuration of a G3 facsimile low-speed frame in the embodiment.

FIG. 4 is a frame configuration diagram showing a configuration of a G3 control frame in the present embodiment.

FIG. 5 is a frame configuration diagram showing a configuration of a G3 facsimile high-speed frame in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Input terminal 12 Encoding unit 13 Output terminal 14 Decoding unit 17 Voice encoder 18 G3 facsimile demodulator 19 G3 facsimile signal detector 22 G3 control frame generator 23 Multiplexer 25 Voice decoder 26 G3 facsimile modulator 27 G3 control frame detector 28 Frame synchronization detector 29 Switcher

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) H04M 11/00-11/10 H04J 3/00 H04N 1/00 102

Claims (3)

(57) [Claims] 1. A signal discriminating means for discriminating whether an input signal is a voice signal or a facsimile signal, a voice coding means for coding the input voice signal, and a demodulation means for demodulating the input facsimile signal. , not a one to a predetermined fixed length frame encoding or demodulated signal
One and synchronizing signal generating means for generating a frame synchronizing signal as a separator in transmitting incorporated in order, the identification data for distinguishing the observed speech signal when the signal discriminating means has determined that the facsimile signal of the fixed length frame signal of
An encoding section that includes a data transmitting means for transmitting incorporated into a predetermined position, this is connected with the encoding unit and the digital line, a frame synchronization detector for detecting frame synchronization, each of the
Detecting means for determining whether or not the identification data is incorporated in the predetermined position of the frame of a fixed length ; voice decoding means; facsimile modulation means; and determining that the identification data is incorporated by the detection means A signal output means for outputting a signal modulated by the facsimile modulation means for the decoded frame, and outputting a signal decoded by the voice decoding means for a frame in which the identification data is not incorporated. And a speech encoding / decoding device. 2. When facsimile high-speed data is incorporated in a frame to be transmitted thereafter, instead of facsimile low-speed data, facsimile high-speed data transmission for transmitting a special frame using the identification data as identification data for starting facsimile high-speed data transmission. 2. A speech encoding apparatus according to claim 1, wherein said encoding frame transmission means is arranged in said encoding section, and said decoding section is provided with frame discriminating means for discriminating said special frame from other frames. Decryption device. 3. The speech coding and decoding apparatus according to claim 1, wherein said facsimile signal is a G3 facsimile signal.