JP2001350496A - Device and method for voice coding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital voice transmitting device using a real time voice coding device. SOLUTION: A voice coding device has switching control means 21 and 22 which output signals by switching the outputs of a spare coding means 18 and a currently used coding means 15. The means 18 and 15 are supplied with same input voice data and synchronized and coupled. When the means 21 and 22 receive signals for the switching, controls are made for coding so that respective virtual buffer values of the means 18, that virtually thinks an input buffer of a decoding side, and the means 15 become a prescribed value. When the prescribed value is obtained, the output of the means 15 is switched to the output of the means 18, no stopping is performed for the coding and code compatibility at the switching point is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coding apparatus, and more particularly, to a digital voice transmitting apparatus using a real-time voice coding apparatus.

[0002]

2. Description of the Related Art Conventionally, in audio broadcasting and the like, in order to perform maintenance or the like of a working encoder, it has been necessary to switch to a spare encoder without stopping encoding. Therefore, as shown in FIG. 7, switching from the working encoder 31 to the spare encoder 32 is performed under the control of the controller 35 to the switcher 34.

As an audio encoding method, MPEG1Lay, which is an encoding method conventionally used in video CDs and the like, is used.
In the case of erII, encoding is performed in units of linear PCM 1152 samples (frames), and the code amount generated for each 1152 samples is constant. In such a case, as shown in FIG. 6, if the coding rate is constant, the code amount (Nbits) generated in frame units is constant.

[0004]

However, MPEG2A
In the case of AC encoding, encoding is performed in units of PCM 1024 (frames), and even if the encoding rate is constant, as shown in FIG. 4, the amount of code generated for each frame is A1bits, A2bits, Different from A3bits, A4bits, ...

Therefore, as shown in FIG. 5, the control of the code amount using a virtual buffer assuming the input buffer of the decoder is performed for each frame, and the encoding is performed so that the input buffer of the decoder does not fail. Will be

For this reason, even if the encoding rate and the input PCM are the same, the state of the virtual buffer becomes a different value for each encoder depending on the number of encoded frames up to that point, and the switching of the encoder is simply performed. Then, the consistency of the code amount control at the switching point cannot be maintained, and the input buffer of the decoder may output a stream that causes an underflow or the like.

Therefore, as shown in FIG. 8, the virtual buffer value of the code amount control unit 68 of the working encoder 66 is supplied to the code amount control unit 71 of the spare encoder 69, and the spare encoder 69 However, there are problems such as an increase in the scale of the device, an increase in the number of input / output devices, and the occurrence of a delay in connection processing.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 operates synchronously when the same input voice data is supplied and a signal for switching is received, and a spare code Encoding apparatus having a switching control means for switching and outputting between the output of the encoding means and the output of the working encoding means, when the switching control means receives a signal for switching, for encoding, the decoding side The virtual buffer value of each of the preliminary encoding unit and the working encoding unit which imagined an input buffer is controlled so as to be a predetermined value, and when the virtual buffer value reaches the predetermined value, the output of the working encoding unit is Speech coding apparatus characterized in that it is possible to switch to the output of the preliminary coding means and to switch the coding means and maintain code consistency at a switching point without stopping coding. The present invention according to claim 2, comprising a plurality of working coding means and a spare coding means, wherein the working coding means and the preliminary coding means selected from the plurality of working coding means are provided. When the same input voice data is supplied and a signal for switching is received, synchronous operation is performed.
In a speech encoding device having switching control means for switching and outputting the output of the preliminary encoding means and the output of the selected working encoding means, when the switching control means receives a signal for switching, the code For this purpose, the virtual buffer values of the preliminary encoding means and the selected active encoding means, which imagined an input buffer on the decoding side, are controlled to be a predetermined value, and have reached the predetermined value. At this time, the output of the selected working encoder is switched to the output of the spare encoder, and the encoding unit is switched without stopping the encoding, and the code consistency at the switching point can be maintained. And a speech encoding apparatus characterized in that:
In the audio coding apparatus described in the above, upon receiving a signal for switching, the switching control means controls the code amount such that the buffer values of the preliminary coding means and the working coding means are each 0. Thus, the present invention provides a speech encoding apparatus characterized by shifting from code quantity control by normal encoding to code quantity control for completely fixed encoding. Speech encoding method having a switching control step of synchronously operating when audio data is supplied and receiving a signal for switching to switch and output between an output of a preliminary encoding step and an output of a working encoding step In the above, when the switching control step receives a signal for switching, a virtual buffer of the preliminary encoding step, which is a virtual input buffer on the decoding side, for encoding. The value is controlled to be a predetermined value of the virtual buffer in the working encoding step, and when the value reaches the predetermined value, the output is switched to the output of the preliminary encoding step, and the encoding is performed without stopping encoding. The present invention provides a speech encoding method characterized in that it is possible to switch between steps and to maintain code consistency at a switching point, and the invention according to claim 5 includes a plurality of active encoding steps and a preliminary encoding step. The same input voice data is supplied to the working coding step selected from the plurality of working coding steps and the preliminary coding step, and the synchronous operation is performed at the time when a signal for switching is received. And a switching control step of switching and outputting between the output of the preliminary encoding step and the output of the selected working encoding step. When the control step receives a signal for switching, controlling the virtual buffer value of the preliminary encoding step for encoding to be a predetermined value of the virtual buffer of the selected working encoding step, Switch to the output of the preliminary encoding step at the time when it reaches a predetermined value, without stopping encoding,
A speech encoding method is provided, wherein the encoding step can be switched and the code consistency at the switching point can be maintained.
In the audio encoding method described in the above, upon receiving a signal for switching, the switching control step controls the code amount such that the buffer values of the preliminary encoding step and the current encoding step are each 0. Therefore, it is an object of the present invention to provide a speech coding method characterized by shifting from code amount control by normal coding to code amount control for completely fixed coding.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a speech encoding apparatus and method according to the present invention. FIG. 1 is a block diagram showing an embodiment of a speech encoding apparatus according to the present invention.

One embodiment of the speech encoding apparatus according to the present invention comprises a working encoder 15 (encoding unit 16 and code amount control unit 17),
Preliminary encoder 18 (encoding unit 19, code amount control unit 2
0), a switcher 21, a controller 22, and a synchronization signal generator 23. The speech coding apparatus of the present invention is different from the conventional apparatus shown in FIG. 8 in that the code amount control unit of the current encoder is supplied to the code amount control unit of the spare encoder for buffer amount control. The difference is that the control lines that have been deleted have been deleted.

As shown in FIG. 1, input PCM data is input to a working encoder 15 and a spare encoder 18 in a similar state. Working encoder 15 and spare encoder 1
Reference numeral 8 denotes an encoder 16 and an encoder 19, and a code amount controller 1 respectively.
7 and 20 and performs coding on input PCM data at the same coding rate in synchronization with the audio frame signal supplied from the synchronization signal generator 23. The working encoder 15 and the spare encoder 18 are supplied with the output synchronization signal of the synchronization signal generator 23 and are synchronously coupled.

The changeover switcher 21 is connected to the controller 2
2 and normally outputs an output bit stream from the encoding unit 16 of the working encoder 15.

Here, the spare encoder 18 does not normally need to operate, but only needs to operate during a time period when switching is required, such as maintenance of the working encoder 15.

When performing maintenance or the like of the working encoder 15, the user issues a switching instruction to the controller 22. When the pre-encoder 18 receives this instruction, the pre-encoder 18 starts operating, and the pre-encoder 18
, An input PCM data and an audio frame signal as an output synchronization signal from the synchronization signal generator 23 are supplied.
The controller 22 supplies a switching signal to the code amount control units 17 and 20 of the working encoder 15 and the spare encoder 18 and the switching switcher 21.

When the code amount control units 17 and 20 of the working encoder 15 and the spare encoder 18 are supplied with the switching signal, both of the code amount control units 17 and 20 both operate on the decoding side (decoder). The code amount is controlled so that the virtual buffer value imagining the input buffer becomes a predetermined same value.

Here, from the audio frame immediately after the code amount control units 17 and 20 of the working encoder 15 and the spare encoder 18 have received the switching signal to N audio frames, the working encoder 15 and the working encoder 15 and 20 are used. Precoder 18
After controlling the code amount so that each of the virtual buffer values becomes 0, the control is shifted from the code amount control by the normal coding to the code amount control for the completely fixed coding.

FIG. 3 shows an embodiment of the transition of the virtual buffer value of the code amount control units 17 and 20 of the working encoder 15 and the spare encoder 18 at this time. The changeover switcher 21
After receiving the switching signal from the controller 22, N '
After the audio frame, the switching from the working encoder 15 to the spare encoder 18 is performed seamlessly.
Here, it is assumed that N ′ <N.

At this time, as shown in FIG. 3, the values of the virtual buffers of the working encoder 15 and the spare encoder 18 are the same, and the output of the working encoder 16 is changed to the output 18 of the spare encoder. , The consistency of the code amount control at the switching point can be maintained. Therefore, it is possible to maintain the consistency of the control of the code amount using a virtual buffer that is a virtual input buffer of the decoding side (decoder) performed for each frame, so that encoding is performed so that the input buffer of the decoder does not fail. Is performed.

When the used encoder is returned from the preliminary encoder 18 to the working encoder 15, the same method is used to stop the encoding and to adjust the code amount control at the switching point. Switching of encoders can be performed seamlessly while maintaining the performance.

Next, another embodiment of the speech encoding apparatus and method according to the present invention, in which one spare encoder is set for a plurality of M working encoders, will be described. This will be described below with reference to the drawings. Another embodiment of the speech encoding apparatus and method of the present invention shown in FIG.
2 is a case where the working encoder has 15A and 15B.

An embodiment of the speech encoding apparatus according to the present invention is composed of a working encoder 15A (an encoder 16A, a code amount controller 17A).
A), working encoder 15B (encoding unit 16B, code amount control unit 17B), spare encoder 18 (encoding unit 19, code amount control unit 20), switcher 21, controller 22,
It comprises a synchronization signal generator 23 and an input data switching unit 24.

The speech encoding apparatus of the present invention is different from the conventional apparatus shown in FIG. 8 in that the code amount control unit of the current encoder is changed from the code amount control unit of the spare encoder to the buffer amount control. The difference is that the supplied control line is deleted.

As shown in FIG. 2, input PCM data is supplied to the working encoders 15A and 15B and the spare encoder 18A.
Is input in a similar state. Working encoders 15A, 15
B and the pre-encoder 18 are encoding units 16A,
16B and 19 and code amount control sections 17A, 17B and 20. The input P at the same coding rate is synchronized with the audio frame signal supplied from the synchronization signal generator 23.
Encode the CM data. The working encoders 15A and 15B and the spare encoder 18 are supplied with the output synchronization signal of the synchronization signal generator 23 and are synchronously coupled.

The changeover switcher 21 includes the controller 2
2, the output bit stream from the encoding unit 16A of the working encoder 15A and the output bit stream from the encoding unit 16B of the working encoder 15B are normally output.

Here, the spare encoder 18 does not normally need to operate, but may operate only during a time period when switching is required, such as maintenance of the working encoder 15A or the working encoder 15B. Is enough.

First, when performing maintenance or the like of the working encoder 15A, the user instructs the controller 22 to perform switching. This instruction is sent to the preliminary encoder 18
, First, the preliminary encoder 18 starts operating, the input data switching unit 24 also receives an instruction, and converts the input PCM data supplied to the working encoder 15A for maintenance to the code of the preliminary encoder 18. The synchronization signal generator 2 which is also supplied to the encoding unit 19 and supplied to the working encoder 15A.
3 is also supplied to the encoding unit 19.

The controller 22 includes a working encoder 15A.
And the code amount control units 17A and 20 of the preliminary encoder 18;
A switching signal is generated for the switching switcher 21 and the input data switching unit 24.

Working encoder 15A and spare encoder 18
Upon receiving the switching signal, the code amount control unit 17A and the code amount control unit 20 respectively control the code amounts so that the virtual buffer value becomes a predetermined same value.

Here, from the audio frame immediately after receiving the switching signal to N audio frames,
After controlling the code amount so that the virtual buffer value becomes 0, the control is returned to the normal code amount control.

FIG. 3 shows an embodiment of the transition of the virtual buffer values of the working encoder 15A and the spare encoder 18 at this time. After receiving the switching signal from the controller 22, the switching switcher 21 performs seamless switching from the working encoder 15A to the spare encoder 18 after N ′ audio frames. Here, it is assumed that N ′ <N.

At this time, as shown in FIG. 3, the values of the virtual buffers of the working encoder 15A and the spare encoder 18 are the same, so that the switching from the encoder 16A to the encoder 18 It is possible to maintain the consistency of the code amount control at the point.

Next, when performing maintenance or the like of the working encoder 15B, the user issues a switching instruction to the controller 22. The controller 22 includes a code amount control unit 17 of the working encoder 15B and the spare encoder 18.
A switching signal is generated for B, 20, the switching switcher 21, and the input data switching unit 24. Subsequent steps are the same as in the case where the maintenance of the working encoder 15A is performed.

Since it is sufficient to provide one spare encoder for a plurality of encoders, the operating cost can be greatly reduced.

[0034]

As described above, according to the present invention,
An audio codec having switching control means for synchronously operating when the same input audio data is supplied and receiving a signal for switching, and for switching and outputting between the output of the preliminary encoding means and the output of the current encoding means. In the encoding device, when the switching control unit receives a signal for switching, a virtual buffer value of each of the preliminary encoding unit and the working encoding unit, which is a virtual input buffer on the decoding side, is encoded for encoding. By controlling the output from the working encoder to the output of the spare encoder when the predetermined value is reached. The means can be switched, and the consistency of the code amount control at the switching point can be maintained.

According to the present invention, when the switching control means receives a signal for switching, the switching control means controls the code amount so that the buffer values of the spare encoding means and the working encoding means become 0 each. Therefore, since the code amount control by the normal encoding is shifted to the code amount control for the completely fixed encoding, the encoding means can be switched without stopping the encoding, and the switching can be performed. It is possible to maintain the consistency of the code amount control at the point.

According to the present invention, if one spare encoding means is provided for a plurality of encoding means, the operating cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration of an embodiment of a speech encoding apparatus and a method thereof according to the present invention.

FIG. 2 is a diagram showing a block configuration of another embodiment of the speech encoding apparatus and method of the present invention.

FIG. 3 is a diagram illustrating an embodiment of a transition of a virtual buffer that virtually simulates an input buffer on the decoding side of each of the code amount control units of the active encoding unit and the spare encoding unit when switching between the audio encoding device and the method according to the present invention. It is a figure showing an example.

FIG. 4 is a diagram showing a generated code amount in MPEG2 AAC.

FIG. 5 is a diagram illustrating an example of a virtual buffer assuming an input buffer of a decoder used in the speech encoding apparatus and method according to the present invention.

FIG. 6 is a diagram showing a generated code amount in MPEG1 Layer II.

FIG. 7 is a diagram showing a block configuration of an example of a conventional speech encoding device and a method thereof.

FIG. 8 is a diagram showing a block configuration of another example of the conventional speech coding apparatus and method.

[Description of Code] 15, 15A, 15B Working encoder (working encoder) 16, 16A, 16B Encoder 17, 17A, 17B Code amount controller 18 Preliminary encoder (preliminary encoder) 19, 19A, 19B Encoding unit 20, 20A, 20B Code amount control unit 21 Switcher (switching control unit) 22 Controller (switching control unit) 23 Synchronous signal generator 24 Input data switching unit M Number of current encoding units N Switching signal is Number of frames from supply to switching N 'Number of frames from switching signal supply to actual switching

Claims (6)

[Claims] 1. Switching control in which the same input voice data is supplied and synchronously operated when a signal for switching is received to switch and output between the output of the spare encoding means and the output of the working encoding means. In the speech encoding apparatus having means, when the switching control means receives a signal for switching, for encoding, for the encoding, each of the preliminary encoding means and the working encoding means imagining a decoding-side input buffer. The virtual buffer value is controlled to be a predetermined value, and at the time when the virtual buffer value reaches the predetermined value, the output of the working encoding unit is switched to the output of the spare encoding unit, and the encoding is performed without stopping encoding. A speech encoding apparatus characterized in that it is possible to switch encoding means and maintain code consistency at a switching point. 2. The apparatus according to claim 1, further comprising a plurality of active encoding units and a preliminary encoding unit, wherein the same input voice data is selected as the active encoding unit and the preliminary encoding unit selected from the plurality of the active encoding units. Speech code having switching control means for switching and outputting between the output of the preliminary coding means and the output of the selected working coding means to be synchronously operated at the time of being supplied and receiving a signal for switching. In the encoding device, when the switching control unit receives a signal for switching, for encoding, the virtual buffers of the preliminary encoding unit and the selected active encoding unit, which virtualize an input buffer on the decoding side, for encoding. Controlling the value to be a predetermined value, and when the predetermined value is reached, switching from the output of the selected working coding means to the output of the spare coding means, and stopping the coding. A speech encoding device characterized in that the encoding means can be switched and code consistency at the switching point can be maintained. 3. The audio encoding apparatus according to claim 1, wherein said switching control means receives a signal for switching, and changes the buffer values of said preliminary encoding means and working encoding means. A speech coding apparatus, characterized in that the code amount is controlled so that each of them becomes 0, and then the code amount is controlled from normal code amount control to code amount control for completely fixed coding. 4. A switching control in which the same input voice data is supplied and synchronously operated upon receiving a signal for switching to switch and output between an output of a preliminary encoding step and an output of a current encoding step. In the speech encoding method having the steps, when the switching control step receives a signal for switching, for encoding, for each of the preliminary encoding step and the working encoding step, the input buffer on the decoding side is imagined. The virtual buffer value is controlled to be a predetermined value, and at the time when the virtual buffer value has reached the predetermined value, the output of the working coding step is switched to the output of the preliminary coding step, and the coding is performed without stopping coding. A speech coding method characterized in that it is possible to switch the coding step and to maintain the code consistency at the switching point. 5. A plurality of active encoding steps and a preliminary encoding step, wherein the same input voice data is selected in the active encoding step and the preliminary encoding step selected from the plurality of active encoding steps. A speech code having a switching control step of switching and outputting between the output of the preliminary coding step and the output of the selected working coding step, being synchronously operated at the time of being supplied and receiving a signal for switching. In the encoding method, when the switching control step receives a signal for switching, for encoding, a virtual buffer for each of the preliminary encoding step and a selected active encoding step, which is a virtual input buffer on the decoding side, is encoded. The value is controlled so as to be a predetermined value. A speech encoding method characterized in that it is possible to switch to the output of the pre-encoding step and to switch the encoding step and maintain code consistency at the switching point without stopping encoding. 6. The speech encoding method according to claim 4, wherein said switching control step, upon receiving a signal for switching, sets buffer values of said preliminary encoding step and working encoding step. A speech coding method, characterized in that the code amount is controlled to be 0, and then the code amount is controlled from normal code amount to code amount control for completely fixed coding.