JP2911314B2 - Audio expansion and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing a voice by reading a voice code signal compressed and recorded on a recording medium and performing expansion processing.

[0002]

2. Description of the Related Art A sound expansion / reproduction apparatus that expands and reproduces an audio signal (musical sound) compressed and recorded on a recording medium has been used. In this audio expansion playback device,
As means for performing high-efficiency compression / expansion (high-efficiency encoding) processing of an audio signal, a digital signal processor (hereinafter referred to as DSP) that can execute complicated arithmetic processing on various digital signals at high speed is used. .

[0003] In an audio expansion / reproduction apparatus using such a DSP, a digital audio signal subjected to expansion processing generally has a sampling frequency of 44.1 to 48 k.
Hz, the quantization number is 16 to 18 bits, the number of channels is 2 channels (stereo), and the data amount is large.

Therefore, in order for the DSP to perform decompression arithmetic processing in real time, a high-speed processing is required for the DSP LSI, and a high-performance (for example, a long processing word length) is required. .

However, in the above-mentioned DSP, as a general feature of the semiconductor, there is a problem that the chip size of the LSI increases as the function becomes higher, and as a result, the LSI becomes more expensive. To solve this problem, D
Although it is conceivable to reduce the functions of the SP, when reducing the functions of the DSP, it is necessary to greatly increase the clock frequency in order to compensate for the reduction in processing capability due to the reduction in the functions.

However, the power consumption of an LSI increases proportionally as the clock frequency increases. Since the upper limit of the clock frequency is limited by the power supply voltage, the power supply voltage must be increased in order to increase the clock frequency, but the power consumption increases in proportion to the square of the power supply voltage. In recent years, portable audio expansion / reproduction apparatuses have been promoted, and it is important to reduce power consumption of audio expansion / reproduction apparatuses in order to enable long-time reproduction with limited power such as batteries. It has become a challenge.

[0007]

However, in the above-described conventional audio decompression / playback apparatus, it is difficult to reduce the power consumption because the reduction in power consumption causes a decrease in the function of the apparatus. Was.

The present invention has been conceived in view of such circumstances, and has as its object to provide an audio decompression / reproduction apparatus capable of reducing power consumption.

[0009]

According to the present invention, there is provided an audio decompression / reproduction apparatus for decompressing a compressed audio code signal, comprising: an arithmetic processing unit; a sound quality selection unit; and a power supply voltage supply unit. And clock signal supply means, operation program supply means, and control means.

The arithmetic processing means is driven by a given power supply voltage, and executes a given arithmetic program in response to a given clock signal to expand the compressed audio code signal. The sound quality selection means selects either reproduction with the first sound quality or reproduction with the second sound quality lower than the first sound quality. The power supply voltage supply means selectively supplies a first power supply voltage and a second power supply voltage lower than the first power supply voltage to the arithmetic processing means. The clock signal supply means includes a first clock signal having a first frequency, and a second clock signal having a second frequency lower than the first frequency.
And a second clock signal having a frequency of .times. The operation program supply means selectively supplies a first operation program and a second operation program having lower operation accuracy than the first operation program to the operation processing means.

When the first sound quality is selected by the sound quality selecting means, the control means sends the first power supply voltage, the first clock signal and the first arithmetic program to the arithmetic processing means. Said power supply voltage supply means to provide
Controlling the clock signal supply means and the arithmetic program supply means, and when the second sound quality is selected by the sound quality selection means, the second power supply voltage, the second clock signal and the second The power supply voltage supply means, the clock signal supply means, and the operation program supply means are controlled so as to supply an operation processing program to the operation processing means.

According to a second aspect of the present invention, there is provided an audio expanding / reproducing apparatus for expanding a compressed audio code signal, comprising: an arithmetic processing unit; a sound quality selecting unit;
Clock signal supply means, arithmetic program supply means,
Control means.

The arithmetic processing means is driven by the applied power supply voltage, and executes the applied arithmetic program in response to the applied clock signal, thereby expanding the compressed audio code signal. The sound quality selection means selects either reproduction with the first sound quality or reproduction with the second sound quality lower than the first sound quality. The power supply voltage selectively supplies a first power supply voltage and a second power supply voltage lower than the first power supply voltage to the arithmetic processing means. The clock signal supply means includes a first clock signal having a first frequency, and a second clock signal having a second frequency lower than the first frequency.
And a second clock signal having a frequency of .times. The operation program supply means selectively supplies the first operation program and a second operation program having a narrower band of the audio code signal to be operated than the first operation program to the operation processing means.

When the first sound quality is selected by the sound quality selecting means, the control means sends the first power supply voltage, the first clock signal and the first arithmetic program to the arithmetic processing means. Said power supply voltage supply means to provide
Controlling the clock signal supply means and the operation program supply means, and when the sound quality selection means selects the second sound quality, the second power supply voltage, the second clock signal and the second operation The power supply voltage supply means, the clock signal supply means, and the arithmetic program supply means are controlled so as to supply a processing program to the arithmetic processing means.

[0015]

According to the first aspect of the present invention, when the high sound quality first sound quality is selected by the sound quality selecting means, the control means controls the power supply voltage supply means and the clock to the arithmetic processing means. A first power supply voltage of a high voltage and a first power supply voltage of a high frequency from the signal supply means and the arithmetic program supply means, respectively.
And a first arithmetic program with high arithmetic accuracy. As a result, in the arithmetic processing means, a decompression process for high sound quality is performed. On the other hand, when the low sound quality second sound quality is selected by the sound quality selection means, the control means controls the second processing voltage and the low frequency second clock signal to the arithmetic processing means. , A second arithmetic processing program having a low arithmetic precision (the number of arithmetic processing steps is small). Thereby, in the arithmetic processing means,
Decompression processing for low-quality sound reproduction is performed with low power consumption.

According to the second aspect of the present invention, when the first sound quality having a high sound quality is selected, the expansion processing for the high sound quality is performed by the arithmetic processing means in the same manner as the operation according to the first aspect. Is performed. On the other hand, when the low sound quality second sound quality is selected by the sound quality selection means, the control means controls the second power supply voltage and the second clock signal of the hand frequency to the arithmetic processing means. And a second operation program in which the band of the audio code signal to be operated is narrow (the number of operation processing steps is small). As a result, in the arithmetic processing means, the low-quality sound expansion processing is performed with low power consumption.

[0017]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the audio expansion / reproduction device.

On a disk 1 as a recording medium, a compressed audio code signal and its additional information are modulated and recorded. The servo device 2 reads the audio code signal and its additional information from the disk 1 and supplies them to the signal demodulation device 3 and the system control device 4.

The signal demodulating device 3 demodulates the audio code signal and the additional information provided from the servo device 2 and converts the demodulated audio code signal into an audio expansion signal as an arithmetic processing means.
The information is supplied to the SP 5 and the demodulated additional information is supplied to the system control device 4 as control information for controlling the system.

A power supply voltage supply device 10 serving as a power supply voltage supply means, based on a control signal supplied from the system control device 4, controls either a high voltage for high-quality sound reproduction or a low voltage for low-quality sound reproduction. It is supplied to the audio expansion DSP 5 as a power supply voltage. A clock supply device 9 serving as a clock signal supply device outputs one of a high-frequency clock signal for high-quality sound reproduction and a low-frequency clock signal for low-quality sound reproduction based on a control signal given from the system control device 4. Supply to extension DSP5.

The program ROM 11 serving as an arithmetic program supply means stores two types of arithmetic programs for arithmetic processing of the audio decompression DSP 5, and the system controller 4
Out of the two types of operation programs based on the control signal given by
Give to SP5. The first operation program of the two types of operation programs is an expansion operation program having a large number of operation steps for performing wideband and high-precision expansion processing for high-quality sound reproduction, and the second operation program has a low sound quality. This is a decompression calculation program with a small number of calculation steps for performing narrow-band and low-precision decompression processing for reproduction.

The audio decompression DSP 5 is provided with a power supply 1
0, and operates in accordance with a clock signal supplied from a clock supply device 9 to control a program ROM.
The operation program read from 11 is executed, and its operation is controlled based on a control signal given from the system control device 4. Such audio expansion D
The SP 5 performs a decompression operation on the compressed audio code signal supplied from the signal demodulation device 3 and supplies the audio code signal subjected to the expansion operation to the DA converter 6.
The DA converter 6 is controlled by a control signal provided from the system control device 4, converts the provided voice code signal from a digital voice signal to an analog voice signal, and supplies the analog voice signal to the voice output device 7.

The audio output device 7 amplifies and filters the analog audio signal supplied from the DA converter 6, and outputs the amplified signal to the outside.

Sound quality selection switch 8 as sound quality selection means
Is a switch for selecting whether to operate the voice expansion / reproduction device for high-quality sound expansion or low-quality sound expansion, and sends a selection signal indicating the selection information to the system control device 4. give.

The system control device 4 serving as control means includes a servo device 2, a signal demodulation device 3, and a sound quality selection switch 8.
Based on the information read from the
A control signal is supplied to each of the A-converter 6, the audio output device 7, the clock supply device 9, the power supply device 10, and the program ROM 11, and control operations such as reading and judging data and control of the entire system are performed.

Next, the operation of the audio decompression / playback apparatus having such a configuration will be described. FIG. 2 is a flowchart showing an operation based on the selection of the sound quality selection switch 8 of the audio expansion / reproduction device.

First, step S (hereinafter simply referred to as S) 1
Then, the selection information of the sound quality selection switch 8 is read. Then
At S2, it is determined whether or not the sound quality selection switch 8 has been selected for the low sound quality reproduction side, and if it has been selected for the low sound quality reproduction side, the process proceeds to S3, and the low sound quality reproduction side has not been selected ( If it is selected on the high-quality sound reproduction side), S
Go to 7.

In S3, a control signal for generating a low voltage for reproducing low sound quality is supplied to the power supply voltage supply device 10. As a result, the power supply voltage supply device 10
Supply low voltage to P5. Next, at S4, a control signal for generating a low frequency clock signal for reproducing low sound quality is supplied to the clock supply device 9. Thereby, the clock supply device 9 supplies a low frequency clock signal to the audio decompression DSP 5.

Next, at S5, a control signal for selecting the second arithmetic program is given to the program ROM 11. As a result, the program ROM 11 provides the audio expansion DSP 5 with the second arithmetic program.

Next, in S6, a control signal is supplied to the audio expansion DSP 5, and the audio expansion DSP 5 is operated under the conditions for low sound quality expansion set in S3 to S5. As a result, the audio decompression DSP 5 performs an audio decompression operation with low sound quality.

When the process proceeds from S2 to S7, in S7, a control signal for generating a high voltage for high-quality sound reproduction is provided to the power supply voltage supply device 10. Thereby, the power supply voltage supply device 10 supplies a high voltage to the audio decompression DSP 5. Next, in S8, a control signal for generating a high-frequency clock signal for reproducing high-quality sound is given to the clock supply device 9. Thereby, the clock supply device 9 supplies a high-frequency clock signal to the audio decompression DSP 5.

Next, in S9, a control signal for selecting the first arithmetic program is given to the program ROM 11. As a result, the program ROM 11 provides the audio expansion DSP 5 with the first arithmetic program. Then, the process proceeds from S9 to S6, where the same processing as described above is performed.

As described above, the audio decompression / reproduction apparatus shown in FIG. 1 can selectively perform low-quality and high-quality decompression reproduction. The low-quality extended reproduction can reduce power consumption in a use state, for example, in a case where a high-quality reproduction sound is not required and a battery needs to be used as a power source in, for example, outdoor reproduction.

[0034]

According to the first aspect of the present invention, it is possible to select between low-quality sound reproduction and high-quality sound reproduction. Since the arithmetic processing means operates with a lower power supply voltage, a lower frequency clock signal and an arithmetic program with lower arithmetic accuracy,
When reproduction with low sound quality is selected, power consumption can be reduced.

According to the second aspect of the present invention, it is possible to select between reproduction with low sound quality and reproduction with high sound quality. At the time of reproduction with low sound quality, the reproduction is higher than at the time of reproduction with high sound quality. Since the arithmetic processing means operates with an arithmetic program having a narrow arithmetic bandwidth for a low power supply voltage, a low frequency clock signal and a voice code signal, power consumption can be reduced when reproduction with low sound quality is selected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an audio decompression / reproduction apparatus.

FIG. 2 is a flowchart showing an operation based on selection of a sound quality selection switch in the audio expansion / reproduction device.

[Explanation of symbols]

 Reference Signs List 4 System control device 5 Voice expansion DSP 8 Sound quality selection switch 9 Clock supply device 10 Power supply voltage device 11 Program ROM

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03M 7/30 G10L 3/02

Claims (2)

(57) [Claims] 1. An audio decompression / reproduction apparatus for decompressing a compressed audio code signal, the apparatus being driven by a supplied power supply voltage and executing a given arithmetic program in response to a supplied clock signal. Arithmetic processing means for expanding the compressed audio code signal, reproduction with a first sound quality, and a second sound quality lower than the first sound quality.
Sound quality selection means for selecting one of the following reproductions with a sound quality of: a first power supply voltage; and a second power supply voltage lower than the first power supply voltage.
A power supply voltage for selectively supplying the power supply voltage to the arithmetic processing means; a first clock signal having a first frequency;
Clock signal supply means for selectively providing a second clock signal having a second frequency lower than the first frequency to the arithmetic processing means; a first arithmetic program; and arithmetic accuracy higher than the first arithmetic program An arithmetic program supply means for selectively providing a second arithmetic program with a low sound quality to the arithmetic processing means; and a case where the first sound quality is selected by the sound quality selecting means.
Controlling the power supply voltage supply unit, the clock signal supply unit, and the operation program supply unit to supply the first power supply voltage, the first clock signal, and the first operation program to the operation processing unit; When the second sound quality is selected by the sound quality selecting means, the second sound quality is selected.
Control means for controlling the power supply voltage supply means, the clock signal supply means, and the operation program supply means so as to supply the power supply voltage, the second clock signal, and the second operation processing program to the operation processing means; An audio decompression / playback device comprising: 2. An audio expansion / reproduction apparatus for expanding a compressed audio code signal, the apparatus being driven by an applied power supply voltage and executing an applied arithmetic program in response to an applied clock signal. Arithmetic processing means for expanding the compressed audio code signal, reproduction with a first sound quality, and a second sound quality lower than the first sound quality.
Sound quality selection means for selecting one of the following reproductions with a sound quality of: a first power supply voltage; and a second power supply voltage lower than the first power supply voltage.
A power supply voltage for selectively supplying the power supply voltage to the arithmetic processing means; a first clock signal having a first frequency;
Clock signal supply means for selectively providing a second clock signal having a second frequency lower than the first frequency to the arithmetic processing means; a first arithmetic program; and arithmetic operations performed by the first arithmetic program An arithmetic program supply means for selectively providing a second arithmetic program having a narrow band of an audio code signal to be provided to the arithmetic processing means; and when the first sound quality is selected by the sound quality selecting means,
Controlling the power supply voltage supply means, the clock signal supply means, and the operation program supply means to supply the first power supply voltage, the first clock signal, and the first operation program to the operation processing means; When the second sound quality is selected by the sound quality selection means, the second sound quality is selected.
Control means for controlling the power supply voltage supply means, the clock signal supply means, and the operation program supply means so as to supply the power supply voltage, the second clock signal, and the second operation processing program to the operation processing means; An audio decompression / playback device comprising: