JPS6059569A - Digital sound converter - Google Patents

Abstract

PURPOSE:To transmit mutually digital sound signals also between different kinds of devices by coupling plural coding decoding device (codec) and executing the conversion of a coding/decoding system, rate conversion of coding, etc. on the basis of the combination of these codecs. CONSTITUTION:A digital sound conversion part selects the coupling of a PCM codec 51 and ADM codecs 52, 53 having different bit rates and a parallel/serial conversion circuit 66, a serial/parallel conversion circuit 63, etc. are enabled to operate in accordance with the combination of these codecs. ADM digital data of 32kb/S are decoded by the codec 52, encoded by the codec 53 and then converted into ADM digital data of 16kb/S, which are outputted from the circuit 63 in parallel. In the same manner, PCM data are converted into the ADM data. By executing the conversion of the coding/decoding system, coding rate conversion, etc., transmission of digital sound signals also between different kinds of terminal equipments are made possible.

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for encoding and decoding audio signals;
In particular, it is intended to enable conversion of at least one of encoding, decoding methods, and encoding rates.

Background: Conventional sound encoding and decoding devices have been constructed using a single type of encoder, decoder, or codec with a fixed encoding rate. For this reason, the encoding and decoding methods for digital sound are unique to each device, and are not compatible between different models, so it is not possible to transmit sound between different models using communication lines. Therefore, it is not possible to perform high-quality digital transmission that is not easily affected by noise, and it is necessary to transmit an analog signal, which is easily affected by noise. In addition, in current audio digital transmission, generally 64
The kb/sPCM method is used. Storing such high-speed, high-quality digital sound signals requires a storage device with a large capacity, which is expensive. In addition, in conventional digital transmission systems, the conversion method and encoding rate are fixed for the transmission path, so from the perspective of transmitting the recorded content, the quality may be excessive or low quality in some cases. There was a drawback that it was not possible to set an appropriate rate that was sufficient and minimally necessary for transmission.

<Summary of the Invention> The purpose of the present invention is to enable the transmission of digital sound signals even between different types of devices, and to store a relatively large amount of sound information even if a storage device with a relatively small storage capacity is used. It is an object of the present invention to provide a digital sound converting device which is capable of transmitting and storing data at a rate sufficient and minimum necessary for transmitting contents.

According to the present invention, a plurality of codecs (or encoders and decoders) that differ in at least one of the encoding and decoding methods and the quantization rate and the decoding rate are provided, and the control of the processor section It is possible to select one of these codecs and then feed its encoded output to the encoded input of the other codec.

<Embodiment> FIG. 1 shows an example of a digital sound conversion device according to the present invention, in which a digital sound conversion section 11 functionally includes a digital encoding section 12, an analog decoding section 13, and a conversion section 4. . An input device 15 such as a microphone or a pick-up coil of a telephone is connected to the digital sound converter 11. Output devices such as speakers 161 Communication line interface 1
7. Furthermore, a processor section 18 is connected. The processor section 18 functionally includes an arithmetic/control circuit 19. A magnetic disk including a storage circuit 21 and the like.

Magnetic tape storage section 221 display section 23. It is connected to a character/command input section 24 such as a keyboard.

The arithmetic/control circuit 19 of the processor section 18 is implemented by software as the digital sound converter section 112 and the communication line interface 1.
7 and the storage unit 22.

When inputting sound, the input sound is converted into an analog electrical signal by the input device 15, inputted to the digital encoding section 12, and converted into a digital signal. (C) The analog sound signal received by the communication line interface 17 through the communication line is converted into a digital signal by the digital encoding unit 12. The digital signal of the b voice received by the interface 17 through the processor section 18 is controlled by the arithmetic and control circuit 19 of the processor section 18, and is once transferred to the storage circuit 21, and further transferred to the storage section 22 and stored therein.

When outputting sound, the digital signal is read out from the storage section 22 under the control of the arithmetic/control circuit 19 of the processor section 18 and transferred to the analog decoding section 13, and the digital signal is converted into an analog signal and sent through the output device 16. Output. Alternatively, the analog signal converted from the analog decoding section 13 is output to the analog communication line through the communication line interface 17, or the digital signal read from the storage section 22 is output to the communication line through the communication line interface 17.

The processor section 18 converts the digital sound using the storage section 22.
The digital signal is read out from the digital sound converter 1.
Send to 1. Here, first, the digital signal is converted into an analog signal by the analog decoding section 13, and this analog signal is inputted to the digital encoding section 12 through the conversion circuit 14 to be converted to another encoding method and/or encoding rate. Convert to digital signal. The converted digital signal is stored again in the storage section 22.

The character/command input section 24 is used for starting and ending input/output of sounds, inputting conversion methods, and giving instructions. Further, the display unit 23 is used to monitor the execution state.

A specific example of the digital sound conversion section 11 is shown in FIG.

This example includes a 64 kb/s PCM codec 51, a 32 kb/SADM (Adaptive Delta Modulation) codec 52, and a 16 kb/s AD-PCM codec.
(Adaptive Differential-PCM) codec 53, the analog signals from the multiplexer 54 are connected to the codecs 51, 52, 53 through buffer amplifiers 55, 56, 57, respectively, and these codecs 51, 52, The digital data encoded in step 53 is sent to serial-to-parallel converter 61, respectively.
62 and 63, respectively. The digital data converted into serial data from these serial/parallel converters 61 , 62 , and 63 is input to the processor section 18 through a data line 64 .

On the other hand, the digital data input from the processor section 18 through the signal line 64 is transferred to parallel-to-serial converters 65, 66,
At 67, the parallel digital data is converted into parallel digital data, which is manually input to codecs 51, 52, and 53, and decoded into analog signal data by codecs 51, 52, and 53, respectively. One of these analog signals can be taken out by the multiplexer 68, and the taken out analog signal is sent to the multiplexer 69 and the p multiplexer 54. It is output to either the output device 162 or the communication line interface 17. Multiplexer 54 selects an analog signal from either input device 15 or multiplexer 69 and supplies it to buffer amplifiers 51 , 52 , 53 .

The processor section 18 includes multiplexers 54, 68, 6
9 can be controlled through signal lines 71, 72, and 73, respectively, and codecs 51, 52, and 53 can be controlled in enabled and disabled states through signal lines 74, 75, and 76, respectively. It can be done. Furthermore, a serial-parallel converter 61
, 62.

63, and the parallel-to-serial converters 65, 66, and 67 have three-state buffers, and are connected to signal lines 77, 78, 79, and 81, 82 from the processor section 18, respectively.
, 83, it is possible to control the output impedance of these converters to infinity and to put the output side in a substantially disconnected state and in an output enabled state, and also to send an operation clock and a pulse indicating the start position of the conversion. Can be done.

The control signals on the signal lines 77 and 81 are applied to the activation and clock terminals of the codec 51 through an OR circuit 84, and the control signals on the signal lines 78 and 82 are applied to the activation and clock terminals of the codec 52 through an OR circuit 85. 79. ．． The control signal 83 is applied to the activation and clock terminals of the codec 53 through an OR circuit 86.

Note that the multiplexers 54 , 68 , 69 are a kind of analog switches, and the buffer amplifiers 55 , 56 ,
57 is an analog signal codec 51 , 52 .

53 from influencing each other.

When encoding an analog signal, the processor section 18 connects the multiplexer 54 to the input device 15 side, and can also operate one coach, for example, a 64 kb/s codec 51, depending on the desired encoding format and encoding rate. At the same time, the serial-to-parallel converter 61 is brought into operation. The analog signal from the input device 15 is sent to the multiplexer 5.
4 and further input to codecs 51 , 52 , 53 via buffer amplifiers 55 , 56 , 57 .

The 64 kb/s PCM codec 51 activated by the processor section 18 in these codecs 51 , 52 , and 53 digitally encodes the human analog signal, and the digital data is transferred to the processor section 18 through the serial/parallel converter section 61 .

When outputting digital data, for example 64K, depending on the encoding format and encoding rate of the digital data.
The b/s PCM codec 51 is activated, the parallel-to-serial converter 65 is activated, and the multiplexer 68 is connected to the codec 51.

Digital data input from the processor section 18 through the data line 64 is converted into serial data by the parallel-to-serial converter 65, and further decoded into a digital analog signal by the codec 51. The analog signal is sent to the multiplexer 68
through the output device 16 depending on the connection state of the multiplexer.
Alternatively, it is output to the communication line interface 17.

Next, the conversion operation will be explained using an example in which 32 kb/s ADM digital data is converted to 16 kb/s AD-PCM digital data. multiplex 54
is connected to the multiplexer 69 side, and the multiplexer 68
is connected to the 32 kb/s ADM codec 52 side, the multiplexer 69 is connected to the multiplexer 54 side, and the coaches 52 and 53 as well as the parallel-serial converter 6
6. Make each of the serial-parallel converters 63 operational. The 32 kb/s ADM digital data from the processor section 18 is converted into 32 kb/s ADM digital data through the parallel/serial converter 66.
s is input to the ADM codec 52 and decoded into an analog signal. This analog signal is sent to multiplexer 6
8, 69, and 54 in sequence, and then the buffer amplifier 5.
Codec 51, 52 through 5, 56, 57
, 53 and operable codecs 52 , 53
Of these, 16 kb/s AD-PCM digital data is input to the processor unit 18 through the serial/parallel converter 63. The processor section 18 temporarily stores the input digital data in the storage circuit 21, and then stores it in the storage section 2.
2 and re-storage.

<Effect> As explained above, according to the digital sound conversion device of the present invention, a plurality of codecs are combined, and the combination performs at least one of encoding/decoding method conversion and encoding rate conversion. This has the advantage that digital communication of voice taking can be performed between terminals with different encoding/decoding methods and encoding rates. Also,
Since the audio encoding method and encoding rate can be set according to the service, efficient audio storage becomes possible.

In the above description, if the arithmetic/control circuit 19 has a function of serial-to-parallel conversion or its inverse conversion, in that case, the serial-to-parallel converter and the parallel-to-serial converter can be omitted in FIG. The storage section 22 can also be used as the storage circuit 21.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the device of the present invention, and FIG. 2 is a block diagram showing a specific example of a digital sound converter. 11: Digital sound conversion section, 12: Digital encoding section, 13: Analog decoding section, 15: Input device, 16: Output device, 17: Communication line interface, 18: Glossary section, 19: Arithmetic/control circuit, 21 :Memory circuit, 22
: Storage section, 23: Display section, 24: Character/command input section, 5
1: 64 kb/s PCM codec, 52
: 32 kb/s ADM codec, 53:
16kb/s AD-PCM Near Deck, 6
1 to 63: 3-state buffer serial/parallel converter,
65-67: Parallel-serial converter with 3-state buffer. Patent applicant: Takashi Kusano, agent of Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] (1) A/D that converts analog signals to digital signals
converter, converting digital signals to analog signals
A converter, an encoding/decoding section including a plurality of codecs that differ in at least one of the encoding method, decoding method, and encoding (decoding) rate, and selecting the decoding output side of these encoding/decoding sections. switch means that can be connected to the encoding input side of the plurality of encoding/decoding sections, and a switch means having at least an arithmetic control function, and the switching means that can be connected to the encoding input side of the plurality of encoding/decoding units; A digital sound conversion device comprising: a processor section for controlling the means;