JP2007264515A - Digital signal processor and digital signal processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adapt a digital signal processor with simple constitution to a one-bit audio signal. <P>SOLUTION: When switches 5 and 6 are turned on to A sides, a signal processing section 30 supplies a processed signal generated through signal processing to a D/A converter 90 for PCM based upon a coefficient supplied from a coefficient generation section 40 and a PCM signal from a decimation filter 100 to allow monitoring. When the switches 5 and 6 are turned on to B sides, on the other hand, the signal processing section 30 outputs the processed signal subjected to the signal processing to an output filter 80 based upon the coefficient supplied from the coefficient generation section 40 and an n-bit signal from a bit length converter 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique capable of executing monitor output of a 1-bit audio signal and output to a file while reducing the processing load.

  Conventionally, there has been proposed an audio apparatus that converts a 1-bit signal that has been subjected to delta-sigma modulation into a plurality of bits, and that has been subjected to necessary signal processing, and again outputs the signal after performing sigma-delta modulation (for example, Non-Patent Document 1). FIG. 2 shows the configuration of this conventional apparatus. A signal from the input file 100 storing a 1-bit signal sequence that has been subjected to sigma-delta modulation in advance is converted into a multi-bit signal sequence (n-bit signal) by the bit length converter 110, which is processed by the signal processing unit 130. Is done. The signal processing unit 130 performs a required operation such as a product-sum operation based on the coefficient supplied from the coefficient generation unit 140 and the n-bit signal, and outputs the operation result signal. Then, the sigma delta modulator 150 performs sigma delta modulation again on the n-bit operation result signal and outputs it as a 1-bit signal. When the switch 160 is turned on on the B side, this 1-bit re-sigma delta modulation signal is stored as a 1-bit signal sequence in the output file 180, while when the switch 160 is turned on on the A side. The re-sigma delta modulation signal is converted from digital to analog by the D / A converter 190 for 1-bit signal, and the audio signal can be monitored by the analog audio signal monitor 170.

P. Eastty et al., “DSD-Wide Practical Implementation for Professional Audio”, “Audio Engineering Society, Convention Paper 5377”, Amsterdam, Netherlands, 12-15 May 2001, p3 ~ P12

  Certainly, the conventional apparatus shown in FIG. 2 is a useful apparatus that can easily monitor the analog audio signal that is finally output. However, generally, a 1-bit audio signal has a high sampling frequency, and high-speed arithmetic processing must be performed. For this reason, a processor capable of high-speed processing must be provided, and a D / A converter 190 capable of handling 1-bit audio signals is also required, and a conventional apparatus can be easily realized on a PC (personal computer). There was a problem that we couldn't.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a digital signal processing device and a digital signal processing program capable of handling a 1-bit audio signal with a simple configuration.

In order to achieve the above object, the present invention comprises sampling frequency conversion means for receiving a 1-bit input signal subjected to sigma delta modulation processing and outputting a PCM (pulse code modulation) signal with a lower sampling frequency. The input signal is converted into an n-bit signal which is an n-bit (n is an integer of 2 or more) signal and output, and a predetermined signal processing is performed using a coefficient supplied from a coefficient generator. A signal processing unit for executing, a digital-to-analog conversion unit for digital-to-analog conversion of the PCM signal from the signal processing unit, and a sigma-delta modulation unit for performing sigma-delta modulation on the n-bit signal from the signal processing unit again With
The signal processing means includes
When the first mode is designated, a processing result generated as a result of performing signal processing based on the first group of coefficients supplied from the coefficient generator and the PCM signal from the sampling frequency conversion means While supplying a signal to the digital-analog converter for monitoring,
When the second mode is designated, processing generated as a result of performing signal processing based on the second group of coefficients supplied from the coefficient generator and the n-bit signal from the bit length conversion means The result signal can be output to an output file.

  According to the present invention, when the first mode is designated, the signal processing means performs signal processing based on the first group of coefficients supplied from the coefficient generator and the PCM signal from the sampling frequency conversion means. The processing result signal generated as a result of performing the processing is supplied to the D / A converter for monitoring, and when the second mode is selected, the second group of coefficients supplied from the coefficient generating unit And a processing result signal generated as a result of signal processing based on the n-bit signal from the bit length conversion means can be output to an output file. Therefore, the conventional 1-bit D / A converter is not required and it is not necessary to increase the capacity of the processor. For this reason, it is possible to realize such a digital signal processing apparatus using, for example, a personal computer having a low throughput. .

  Further, in this apparatus, when the signal processing means continues to have the same calculation result by the instructed calculation, the input signal can be directly output to the output file, and the execution of useless processing is reduced as much as possible. It becomes possible.

Further, according to the present invention, there is provided a digital signal processing program executable by a computer,
A digital signal processing program executable by a computer,
A sampling frequency conversion function for receiving a 1-bit input signal that has been subjected to sigma delta modulation processing and outputting a PCM (pulse code modulation) signal with a lower sampling frequency corresponding thereto;
A bit length conversion function for converting the input signal into an n-bit signal which is an n-bit (n is an integer of 2 or more) signal and outputting the signal,
A signal processing function for performing predetermined signal processing using a coefficient supplied from a coefficient generator;
A digital-analog conversion function for converting a PCM signal from the signal processing function into a digital-analog converter by a digital-analog converter;
A sigma delta modulation function for performing sigma delta modulation again on the n-bit signal from the signal processing function, and a program that can be realized on a computer,
The signal processing function is
When the first mode is designated, a processing signal generated as a result of performing signal processing based on the first group of coefficients supplied from the coefficient generator and the PCM signal from the sampling frequency conversion means To the digital-analog converter to enable monitoring,
When the second mode is designated, processing generated as a result of performing signal processing based on the second group of coefficients supplied from the coefficient generator and the n-bit signal from the bit length conversion means A computer-executable digital signal processing program is also provided, which is a function that enables output of a signal to an output file.

  According to the present invention, it is possible to provide a digital signal processing apparatus and a digital signal processing program that can handle a 1-bit audio signal with a simple configuration.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Constitution)
FIG. 1 is a block diagram of a digital signal processing apparatus 1 which is a preferred embodiment of the present invention. The input file 10 stores a 1-bit sigma-delta modulated signal that has been previously subjected to sigma-delta modulation. The switches 5 and 6 of the apparatus 1 are synchronously controlled, and when the switch 5 is turned on to the A side, the switch 6 is also turned on to the A side (first mode designation). On the other hand, when the switch 5 is turned on to the B side, the switch 6 is also turned on to the B side (second mode designation). When the switch 6 is turned on to the A side or the B side, different coefficients are supplied from the coefficient generator 40 in both modes.

  The digital signal processing apparatus 1 accepts a 1-bit input signal subjected to sigma delta modulation processing stored in the input file 10 and outputs a PCM (pulse code modulation) signal with a lower sampling frequency. A decimation filter 100, a bit length converter 20 that converts a 1-bit input signal into an n-bit signal (for example, 32 bits) of n bits (n is an integer of 2 or more) and outputs, and predetermined signal processing A signal processing unit 30 that is executed using a coefficient supplied from the coefficient generation unit 40, a PCM D / A converter 90 that performs digital / analog conversion on the PCM signal from the signal processing unit 30, and a signal processing unit 30 and a sigma delta modulator 50 for performing sigma delta modulation on the n-bit signal again.

  The output signal from the PCM D / A converter 90 can be monitored (audited) via the analog audio signal monitor 70. Further, when the switch 9 is turned on to the A side, the 1-bit re-sigma delta modulation signal from the sigma delta modulator 50 can be sequentially stored in the output file 80. The switches 5 and 6 are controlled by a control unit (not shown).

  In addition, the signal processing unit 30 has a control function of the switch 9 and is usually configured to turn on the switch 9 to the A side and store the signal processing result in the output file 80, while the signal processing unit 30 has the same calculation. When an instruction of a predetermined calculation that can obtain a result (for example, a calculation process such as multiplying a signal by a coefficient “1.0”) is given, the switch 9 is turned on to the B side, and the input file 10 Can be stored in the output file 80 as it is, so that unnecessary execution of processing is omitted as much as possible.

(Function)
First, when the switches 5 and 6 are turned on to the A side (when the first mode is designated), the 1-bit sigma delta modulation signal stored in the input file 10 is supplied to the decimation filter 100. The decimation filter 100 supplies a PCM signal with a reduced sampling frequency (for example, 1/64) to the signal processing unit 30. The signal processing unit 30 executes a predetermined operation such as a product-sum operation based on the coefficient supplied from the coefficient generation unit 40 and the input PCM signal, and outputs the calculation result as a PCM signal. Since the PCM D / A converter 90 performs digital-analog conversion processing on the PCM signal output from the signal processing unit 30, the analog audio signal monitor 70 listens to the reproduced analog audio signal. It becomes possible to do.

  On the other hand, when the switches 5 and 6 are turned on to the B side (when the second mode is designated), the 1-bit sigma delta modulation signal stored in the input file 10 is supplied to the bit length converter 200. The The bit length converter converts the given 1-bit signal into an n-bit signal (n is an integer of 2 or more: for example, 32 bits), and supplies the n-bit signal to the signal processing unit 30. The signal processing unit 30 executes a predetermined calculation result such as a product-sum calculation based on the coefficient supplied from the coefficient generation unit 40 and the n-bit signal, and outputs the calculation result as an n-bit signal. The sigma delta modulator 50 performs sigma delta modulation on the n-bit signal output from the signal processing unit 30 to form a 1-bit signal, which is stored in the output file 80.

  As described above, when the switches 5 and 6 are turned on to the A side (first mode designation), the signal processing unit 30 uses the coefficients supplied from the coefficient generation unit 40 and the PCM from the decimation filter 100. A processing result signal generated as a result of performing signal processing based on the signal is supplied to the PCM D / A converter 90 for monitoring. On the other hand, when the switches 5 and 6 are turned on to the B side (second mode designation), the signal processing unit 30 uses the coefficient supplied from the coefficient generation unit 40 and the n-bit signal from the bit length converter 20. A processing result signal obtained by performing signal processing based on the above is output to the output file 80. Accordingly, it is unnecessary to provide a conventional 1-bit D / A converter and it is not necessary to increase the capacity of the processor. For example, the digital signal processing apparatus 1 can be realized by a personal computer having a low throughput. It becomes possible.

  Note that the above processing can be realized, for example, by the CPU executing a program stored in the ROM. That is, the processing according to the present invention can be realized by executing a program on a personal computer system including a PCM D / A converter.

  As described above, the present invention can provide an apparatus and a program that can perform 1-bit audio signal processing with a simple configuration.

1 is a configuration diagram of a digital signal processing device 1. FIG. It is explanatory drawing of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital signal processor 5 Switch 6 Switch 9 Switch 10 Input file 20 Bit length converter 30 Signal processing part 40 Coefficient generation part 50 Sigma delta modulator 70 Analog audio signal monitor 80 Output file 90 D / A converter 100 for PCM 100 Decimation filter

Claims (3)

Sampling frequency conversion means for receiving a 1-bit input signal that has been subjected to sigma delta modulation processing and outputting a PCM signal with a lower sampling frequency for the input signal, and the input signal as an n-bit signal (n is an integer of 2 or more) A bit length converting means for converting the signal into an n-bit signal and outputting the signal; a signal processing means for executing a predetermined signal processing using a coefficient supplied from a coefficient generating section; and a PCM signal from the signal processing means is digitally converted. Digital-to-analog conversion means for analog conversion; and sigma-delta modulation means for performing sigma-delta modulation on the n-bit signal from the signal processing means,
The signal processing means includes
When the first mode is designated, a processing result generated as a result of performing signal processing based on the first group of coefficients supplied from the coefficient generator and the PCM signal from the sampling frequency conversion means While supplying a signal to the digital-analog converter for monitoring,
When the second mode is designated, processing generated as a result of performing signal processing based on the second group of coefficients supplied from the coefficient generator and the n-bit signal from the bit length conversion means A digital signal processing apparatus capable of outputting a result signal to an output file. The apparatus of claim 1.
The signal processing means includes
A digital signal processing apparatus characterized in that when the calculation result by the instructed calculation continues to be the same, the input signal can be directly output to an output file. A digital signal processing program executable by a computer,
A sampling frequency conversion function for receiving a 1-bit input signal that has been subjected to sigma delta modulation processing and outputting a PCM (pulse code modulation) signal with a lower sampling frequency corresponding thereto;
A bit length conversion function for converting the input signal into an n-bit signal which is an n-bit (n is an integer of 2 or more) signal and outputting the signal,
A signal processing function for performing predetermined signal processing using a coefficient supplied from a coefficient generator;
A digital-analog conversion function for converting a PCM signal from the signal processing function into a digital-analog converter by a digital-analog converter;
A sigma delta modulation function for performing sigma delta modulation again on the n-bit signal from the signal processing function, and a program that can be realized on a computer,
The signal processing function is
When the first mode is designated, a processing result generated as a result of performing signal processing based on the first group of coefficients supplied from the coefficient generator and the PCM signal from the sampling frequency conversion means While supplying a signal to the digital-analog converter for monitoring,
When the second mode is designated, processing generated as a result of performing signal processing based on the second group of coefficients supplied from the coefficient generator and the n-bit signal from the bit length conversion means A computer-executable digital signal processing program, which is a function that enables output of a result signal to an output file.

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