JPS603518A - Display device of musical note - Google Patents

Abstract

PURPOSE:To use an inexpensive one as an analog-to-digital converter by controlling automatically by an automatic gain controlling circuit so that a signal level is held in a roughly prescribed range such as it can be contained in a dynamic range in an analog-to-digital converter used in a device. CONSTITUTION:A sound signal supplied to an input terminal 1 is amplified by an amplifier, and thereafter, applied to an anti-aliasing-filter 4 through an automatic gain controlling circuit 3. The anti-aliasing-filter 4 eliminates an unnecessary frequency component of a high band so that a turning-back noise is not generated, and applies an output signal from said filter to a sample holding circuit 5. An output signal from the sample holding circuit 5 is supplied to an analog-to- digital converter 6, and converted to a digital signal by the analog-to-digital converter 6. The digital signal outputted from the analog-to-digital converter 6 is supplied to a latching circuit (LC) 7. An operation of the analog-to-digital converter 6, the latching circuit 7, etc. is controlled by a controlling circuit CPU.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is directed to displaying a note-like figure in a corresponding part of a musical staff-like display figure on a display, which corresponds to the pitch of an audio signal. The present invention relates to a musical note display device capable of displaying musical notes.

(Conventional Examples and Problems) For example, if it were possible to immediately display the song being played on the staff when playing a musical instrument,
This makes it easy for anyone to record a composed piece of music on a musical score, and it is also expected to be used in music education, so the song being played is now displayed as musical notes on the staff display screen. Various types of display devices have been tried in the past, but in the past, for example, a device was constructed in which a lamp on a staff-shaped display board was turned on by a switch activated by a key pressed on a keyboard. However, the problem is that it cannot be applied to instruments other than keyboard instruments, such as string instruments and wind instruments.
In addition, conventional devices with other configurations, such as converting the sound of a musical instrument into an electrical signal using an acousto-electrical transducer, frequency-analyzing it using a number of bandpass filters, and displaying the analysis results on a staff-shaped display board. In the configuration in which the lamp is turned on at different times, a large number of bandpass filters are required, resulting in a complicated configuration.

Therefore, the applicant company performs an FFT calculation using an analog-to-digital conversion means that converts an input audio signal into a digital signal, and audio signal data based on the digital signal, and performs a power spectrum calculation using the calculation result. means for performing frequency analysis; means for determining the pitch of the audio signal based on the frequency analysis results; The above-mentioned problem has been solved by providing a musical note display device equipped with a means for displaying a figure of the shape of a musical note. The means used to make the determination is to obtain a spectrum value by calculating using audio signal data converted into a digital signal, then calculate the maximum value among the spectrum values, and calculate the maximum value. Find the frequency value of the spectrum that shows the lowest frequency among the spectrum that has a frequency lower than the frequency of the spectrum that shows the maximum value, and that shows a smaller spectral value within a predetermined range than the spectrum that shows the maximum value, and calculate it. The pitch of the input audio signal is determined to be the pitch of the input audio signal, and if there is no spectrum that meets the above conditions, the frequency value of the spectrum showing the maximum spectral value is determined to be the pitch of the input audio signal. , the determination result is transferred to the video RAM (hereinafter sometimes referred to as V-RAM) via a video display processor (hereinafter sometimes referred to as VDP), and the display screen of the display, For example, a method of displaying on the display surface of a cathode ray tube CRT has been adopted. For example, the above-mentioned VDP is "Nikkei Electronics" of Nikkei McGraw-Hill.
March 30, 1981 issue (pages 156-164)
You can use the Texas Instruments video display processor introduced in . 1 Now, in the previously proposed musical note display device described above, even if the signal level of the audio signal whose pitch is to be determined varies over a wide range, the pitch of the input audio signal In order to be able to determine well, it is necessary to use an analog-to-digital converter with a wide dynamic range as the analog-to-digital converter used in the device; Since instruments are expensive, solutions were sought to provide an inexpensive display device for musical notes.

(Means for Solving the Problems) The present invention provides automatic gain control means for automatically adjusting the signal level of an input audio signal to a predetermined level;
An analog-to-digital conversion means converts the analog signal that has passed through the automatic gain control means into a digital signal, and FFT calculation is performed using the audio signal data from the digital signal, and a power spectrum calculation is performed using the calculation result to perform frequency analysis. a means for determining the pitch of the audio signal based on the frequency analysis result, and a means for determining the pitch of the audio signal based on the frequency analysis result, and a means for determining the pitch of the audio signal on the display surface of the display corresponding to the pitch of the pitch at 4- The above-mentioned problems are solved by providing a musical note display device comprising means for displaying musical note-shaped figures.

(Example) Hereinafter, specific contents of the musical note display device of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an embodiment of the musical note display device of the present invention. In FIG. 2
After being amplified by automatic gain control circuit 1 circuit 3 (AGC circuit 3
) and anti-aliasing filter 4 (AAF
4) is given.

The anti-aliasing filter 4 removes unnecessary high-frequency components to prevent aliasing noise, and the output signal is sent to the sample-and-hold circuit 5 (SH5).
give to The output signal from the sample hold circuit 5 is
The signal is supplied to an analog-to-digital converter 6 (A, DC6) and converted into a digital signal by the analog-to-digital conversion means.

The digital signal output from the analog-to-digital converter 6 is supplied to a latch circuit 7 (LC7).

(In practice, a logarithmic compression circuit using a digital signal may be provided instead of the latch circuit 7. Also, a logarithmic amplifier using an analog signal may be used as the amplifier 2 described above. When a logarithmic compression circuit or a logarithmic amplifier is used, as in the case of FIG. The operations of the analog-to-digital converter 6, latch circuit 7, etc. described above are controlled by the control circuit CPU. In the control circuit CPU, 8 is a conversion command unit and digital signal output unit, 9 is a main memory (MM), 10 is a calculation and pitch analysis unit, and 11 is a pattern data determination unit,
In FIG. 1, 12 is a video display processor (VDP12), and 13 is a video display processor (VDP12).
14 is a display (CRT 14). Figure 2 is.

FIG. 3 is a functional block diagram of a control circuit CPU portion.

Next, referring to the flowchart shown in FIG. 3, the musical note display device of the present invention is operated by the control circuit CP TJ.
To explain how the pitch determination operation is performed, in the flowchart shown in Figure 3, the power is turned on at the start, the note display device is started, and the initialization (system Initialization) is performed, and the analog-to-digital converter 6, main memory 9,
In addition to clearing the video RAM 13, etc., setting of the used area of which storage area in the video display processor 12 is used for what table,
Operation mode settings, read-only memory input to main memory 9, pattern generator table, sprite generator table, etc.
A predetermined type of pattern information (graphic information) is transferred via the video display processor 12, and a sprite attribute table t: *t L, ″″″″″″ (t4
+*'PX・Y)'Ij,'m'=t':=t
F L Near 1L data is transferred.

7- After the device is brought into the normal state, the control circuit CPU repeatedly executes each control operation of steps (2) to (6) until an interrupt shown in the flowchart of FIG. 3 occurs. However, when an interrupt occurs at each specific sampling period set in the internal counter provided in the control circuit CPU, the control circuit CPU interrupts the control operation being executed at that time and The control operations shown in (7) to (9) are performed, and when they are completed, the execution of the control operations that were previously interrupted due to the occurrence of the interrupt are continued.

When the interrupt occurs, the control circuit CPU gives a start pulse for analog-to-digital conversion operation to the analog-to-digital converter 6, performs the analog-to-digital conversion operation in step (7), and stores the output digital signal in the main memory MM. do.

In step (8), it is checked whether the analog-to-digital conversion operation performed in the analog-to-digital converter 6 has been performed a predetermined number of times (whether a predetermined number of digital data has been obtained), and if NO, return is made, and if YES, return is made. Then, proceed to step (9), turn off the internal counter (preset the analog-to-digital converter...A/D preset +-) using the chip (9), and return.

When the initialization in step (1) described above is completed, FFT calculation is performed in step (2), the calculation result is stored in the main memory MM, and the process proceeds to step (3).

In step (3), power spectrum calculation is performed on the spectrum data obtained in step (2), and the calculation result is stored in the main memory.

In step (4), the pitch of the sound is determined based on the spectrum data stored in the main memory MM, and the details of the determination of the pitch are as follows. That is,
First, among the spectral data stored in the main memory MM, the one exhibiting the largest spectral value is selected, and in the next step, the one that exists in a frequency region lower than the number of frequencies of the largest spectrum, and Determine the frequency value of the spectrum that indicates the lowest frequency value among the spectra that exhibit a smaller spectral value within a predetermined range than the spectrum size of the largest spectral value, and use it as the sound of the input audio signal. In addition, if there is no spectrum that meets the above conditions, the frequency value of the spectrum with the largest spectral value is determined to be the pitch of the input audio signal. be.

The pitch of the audio signal described above is determined by the main memory M
This can be easily done by referring to the table of frequencies versus pitch names provided in M. Next, in step (5), data to be written in the pattern name table and data to be written in the sprite attribute table are written in correspondence with the data value indicating the pitch determined in step (4) above. and then, in step (6), the said data is sent to the video display processor 12 as a video display processor.
The video display processor 12 creates a composite video signal using the data written to the video RAM 13 as described above, sends it to the display CRT, and displays it on the display surface of the display CRT. ,
The pitch of the sound is displayed using a musical note-like figure 15 as shown in the fourth figure. In FIG. 4, 16.17 is a staff-shaped figure, 15.15... is a note-shaped figure, and 18 is a rest mark-shaped figure.

Now, in the musical note display device of the present invention, 1. The pitch of the audio signal supplied to the input terminal 1 is determined by the operation of the control circuit CPU as described above, and the determination result is displayed on the displays CR and T. In the musical note display device of the present invention, the signal level of the audio signal supplied to the input terminal 1 is controlled by the automatic gain control circuit 3 to be used in the device. The system is automatically controlled to stay within a predetermined range that falls within the dynamic range of the analog-to-digital converter, so even if you use an analog-to-digital converter that does not have a wide dynamic range, it will not be possible to convert notes. Display operations can be performed satisfactorily. In the apparatus of the embodiment shown in FIG.
- The automatic gain control signal used in the automatic gain control circuit 3 may be created based on an analog signal, although the automatic gain control signal is shown as being generated based on a signal converted into an analog signal. Of course.

(Effects) As is clear from the detailed explanation above, in the musical note display device of the present invention, the signal level of the input signal to be the target of musical note display is adjusted to the level of the analog signal used in the device. Since it is automatically controlled by an automatic gain control circuit that operates to maintain approximately a predetermined range within the dynamic range of the digital converter, and then is applied to the analog-to-digital converter, it can be used as a musical note display device. As an analog-to-digital converter used,
An inexpensive device can be used, and according to the present invention, problems with conventional devices can be satisfactorily solved.

[Brief explanation of the drawing]

Fig. 1 is a 12-block diagram of an embodiment of the musical note display device of the present invention, Fig. 2 is a functional block diagram, Fig. 3 is a flowchart, and Fig. 4 is an example of figures displayed on the display surface of the display. It is a diagram. 1... Audio signal input terminal, 2... Amplifier, 3...
- Automatic gain control circuit, 4... Anti-aliasing filter, 5... Sample bold circuit, 6...
Analog-digital converter, 7...Latch circuit, 8...
- Conversion command unit and digital signal output unit, 9... Main memory, 10... Calculation and wave height analysis unit, 11... Pattern data determination unit, 12... Video display processor, 13... Video Ram, 14...Display, Patent Applicant: Japan Victor Co., Ltd., Patent Attorney, Takao Konma

Claims (1)

[Claims] automatic gain control means for automatically adjusting the signal level of the input audio signal to a predetermined level; analog-to-digital conversion means for converting the analog signal passed through the automatic gain control means into a digital signal; means for performing FFT calculation using audio signal data based on a digital signal, and performing frequency analysis by performing a power spectrum 1-her calculation using the calculation result; A musical note display device comprising a means for determining, and a means for displaying a musical note-shaped figure at a portion corresponding to the pitch of a musical staff-like display figure on a display surface of a display.