JPH0310118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention displays an indication corresponding to the pitch of an audio signal in a note-like figure on a corresponding part of a staff-like display figure on a display. The present invention relates to a musical note display device that is capable of displaying musical notes.

(Conventional Examples and Problems) If it were possible to immediately display the song being played on the musical staff when playing an instrument, anyone could record the music they composed on the musical score. Various types of display devices have been tried in the past for displaying the music being played as musical notes on a staff-shaped display surface, because it is easy to use and can also be used in music education. However, in conventional devices, for example, in which a switch operated by a key pressed on a keyboard lights up a lamp on a staff-shaped display board, instruments other than keyboard instruments, that is, stringed instruments, cannot be used. or,
The problem is that it cannot be applied to wind instruments, etc., and conventional devices with other configurations, such as converting the sound of an instrument into an electrical signal using an acousto-electrical transducer, and converting it into an electrical signal using a large number of bandpass filters, are problematic. In the configuration, the frequency is analyzed and a lamp is lit on a staff-shaped display board based on the analysis result.
The disadvantage is that the configuration is complicated because a large number of bandpass filters are required.

Therefore, the applicant company converts the audio signal into a digital signal, performs frequency analysis, determines the pitch of the audio signal based on the analysis result, and displays the corresponding part of the staff on the display based on the pitch determination result. Alternatively, the above problem has been solved by providing a note display device that displays the required information on the corresponding part of the keyboard on the display. When creating a musical score by transcribing the performance sounds of a musical instrument, the standard tone of the instrument (usually note _A4 is taken as the standard tone) and the standard tone on the note display device do not match. Sometimes it happens that the transcribed score ends up being inaccurate.

In other words, if a musical note display device uses, for example, pitch name A ₄ (440 Hz) as its reference tone, and the pitch of other pitch names is set to the state where the notes are tuned to 440 pitches. In addition, as a result of an instrument being tuned to use the note _A4 as the standard tone, it is not uncommon for the note _A4 to be tuned as a note with a frequency that is different from the original 440Hz. Even if the musical instrument's performance is transcribed, the resulting music may be different from what the composer had in mind, and there was a need for an improvement measure.

(Means for Solving the Problems) The present invention performs an FFT operation using an analog-to-digital conversion means that converts an audio signal into a digital signal, and a certain number of data of the digital signal described above, and uses the result of the operation. means for performing frequency analysis by performing power spectrum calculation; means for determining the pitch of the audio signal based on the frequency analysis results; In the corresponding part,
A musical note display device comprising: a means for displaying a determination result by the above-mentioned note pitch determination means in a note-shaped figure; a means for generating a reference tone for articulation; A reference tone signal generating means is capable of supplying an arbitrary reference tone signal to the user, and even if the pitch of the reference tone for articulation deviates from the regular reference tone, the performance can be performed using the regular reference tone as a reference. A clock signal source for generating a clock signal with a variable repetition period, which is provided in the reference sound signal generating means, so that the sound is displayed in the same display manner as when the sound is displayed on the display surface of the display. The above-mentioned problems can be satisfactorily solved by providing a musical note display device equipped with means for changing and setting the sampling period in the analog-to-digital conversion means in accordance with the repetition period of the generated clock signal. This is how it was done.

(Example) Hereinafter, 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 apparatus of the present invention, and FIG. 7 shows an overall configuration diagram (functional block diagram) of the musical note display apparatus of the present invention.

In FIG. 1, 1 is an audio signal input terminal, BA is a buffer amplifier, and the audio signal supplied to input terminal 1 is passed through the buffer amplifier BA, the graphic equalizer GEQ, and the anti-aliasing filter AAF. via analog
The signal is supplied to a digital converter ADC (hereinafter referred to as analog-to-digital conversion as AD conversion), converted into a digital signal, and supplied to the central control unit (microcomputer) CPU.

The repetition period of the AD conversion operation in the AD converter ADC described above, that is, the sampling period, is the repetition period of the AD conversion operation, that is, the sampling period. This is determined by the central control unit CPU in accordance with the repetition period of the clock signal generated by the clock signal source in the reference sound signal generating means, and the details of this point will be described later.

In FIG. 1, the aforementioned sound source is a speaker SP indicated by the symbol SP in the figure, and the reference sound signal generating means is a reference sound signal generator SSG indicated by the symbol SSG in the figure. , reference sound signal generator
SSG is a clock signal generator CSG and frequency dividing means
DIV (for example, an up-down counter may be used).

The clock signal generator CSG is such that the repetition period of the clock signal generated therefrom can be manually varied;
In FIG. 1, the repetition period of the clock signal is variably adjusted by adjusting the slider of the variable resistor VR. The clock signal Sc output from the clock signal generator CSG is sent to the central control unit.
The central control unit CPU sets the repetition period of the AD conversion operation in the AD converter ADC according to the repetition period of the clock signal Sc, which is supplied to the input port CRU of the CPU. do.

In addition, the clock signal Sc generated by the clock signal generator CSG is frequency-divided by the frequency dividing means DIV to form multiple types of signals Sh, Ss, and Sl, which are sent to the fixed contacts b to d of the changeover switch SW. given to. Therefore, by sequentially switching the movable contact a of the changeover switch SW to the fixed contacts b to d, one selected signal among the plurality of types of signals Sh, Ss, and Sl can be sequentially taken out.

Now, when the slider of the variable resistor VR is placed at the midpoint of the variable resistance range, the clock signal Sc (frequency is fs) generated from the clock signal generator CSG , three signals Sh, Ss, and Sl, which are divided by the frequency dividing means DIV and have frequencies of fs/n, fs/2n, and fs/4n, are each 1
Means of producing standard tones with different pitches in octaves
A signal that can be generated from SP, for example, signal Ss is a signal with a frequency of 440 Hz that can cause the sound of pitch name A ₄ to be produced from sound generating means SP, and signal Sh is one octave higher than the above-mentioned signal Ss. It is a signal with a frequency of 880 Hz that allows the sounding means SP to produce a high pitched tone (pitch name A ₅ ), and furthermore, the signal Sl is an octave lower than the above-mentioned signal Ss (pitch name A ₃ ).
is a signal with a frequency of 220 Hz that can be generated from the sound generating means SP, and by shifting the slider of the variable resistor VR from the midpoint position of the variable resistance range, the clock signal generator CSG The frequency of the clock signal Sc generated from
Δf) or frequency (fs−Δf), the three signals Sh, Ss, and Sl obtained as the output of the frequency dividing means DIV also maintain their harmonic relationship as follows: The frequency will shift upward or downward from the above-mentioned value.

And, as mentioned above, in the central control unit CPU,
When the slider of the variable resistor VR is placed at the midpoint of the resistance variable range and the frequency of the clock signal Sc is fs, that is, in the above example, the frequency dividing means DIV
For example, the signal Ss output from is 440Hz of pitch name _A4 .
indicates the frequency of the AD
Sampling period Ts based on the sampling period of converter ADC
Also, when the frequency of the clock signal Sc mentioned above deviates higher (or lower) by α% from the frequency value fs, the sampling period of the AD converter ADC is changed from the standard sampling period Ts. The setting is made to shorten (or lengthen) by α%.

Since the frequency of the clock signal Sc generated by the clock signal generator CSG in the reference tone signal generator SSG is variable by adjusting the variable resistor VR, musical instrument players or singers can The reference sound used can be arbitrarily set to a specific frequency by adjusting the slider of the variable resistor VR mentioned above.

Also, when the movable contact a of the changeover switch SW is switched from the fixed contact c to the fixed contact b (or d),
From the speaker SP connected to the movable contact a via the filter F and the amplifier AMP, the speaker SP is connected to the movable contact a through the fixed contact c.
Since a tone is produced that is one octave higher (or one octave lower) than the pitch of the tone obtained from the SP, it becomes easy to produce a tone that is convenient for articulation from the speaker SP. This means that
For example, the articulation of bass instruments such as the double bass,
It is also effective for the articulation of male singers.

In FIG. 1, OP is an operating section, and this operating section OP includes various information input means such as push button switches for specifying each operating mode of the device, and various indicators (for example, an indicator using a light emitting element). ), etc., and CLD is the operation unit control unit. In Figure 1, RAM is main memory,
ROM ₁ and ROM ₂ are read-only memories,
Also, VDP is a video display processor, V.RAM is a video ram, and CRT is a display.

In Figure 1, the CPU is the central control unit,
The digital signal obtained by AD conversion by the AD converter ADC as described above is
Main memory under the control of central controller CPU
Stored in RAM and used for FFT calculations.

In addition, the above-mentioned graphic equalizer GEQ
The anti-aliasing filter AAF is designed to enable the frequency characteristics of the input signal to be changed depending on the type of musical instrument, and to enable frequency analysis of various musical instruments to be performed well. is a low-pass filter for limiting the frequency band of a signal so that so-called aliasing noise does not occur.

The anti-aliasing filter mentioned above
If the cutoff frequency of AAF is fc, then the AD converter
It is well known that the sampling frequency fc in an ADC should be 2fc or higher, and
When frequency analysis is performed by FFT calculation, the frequency interval f of the spectrum obtained as the analysis result is the AD used to obtain the digital signal.
It is also well known that f=fs/N depending on the sampling frequency fs of the converter ADC and the number N of digital signal data used when performing the FFT operation.

For example, an anti-aliasing filter
When the AAF cutoff frequency fc is 20KHz, the sampling frequency fs in the AD converter ADC is 40KHz (fs=
2fc), and if it is desired to obtain a spectrum at a frequency interval f of 10 Hz as an analysis result by FFT calculation, the number N of digital signal data to be used for FFT calculation is 4000.

In the FFT operation described above, the more data N used for the operation, the longer the time required for frequency analysis. If the time is long and it is difficult to display the pitch in real time, use a multiplier to perform only the FFT operation, so that the pitch of the input signal is close to that in real time. It is desirable that it be displayed as shown in .

Now, the musical note display device of the present invention sequentially displays the pitch of the input audio signal on the display surface of the display CRT, for example, as shown in FIG. The input audio signal is converted to a digital signal so that it can be displayed as musical notes, and the digital signal is used to perform frequency analysis using FFT calculations to determine the pitch of the input audio signal. A predetermined figure is displayed at a specific position on the display surface of the display determined by the judgment result, but as a criterion for judging the pitch of the input audio signal, for example, The pitch name of the 12-equal temperament pitch can be used.

Now, the pitch of the input audio signal is displayed as the note names of three octaves that can be represented by the staff displayed on the display surface, that is, the positions on the staff corresponding to F ₂ to F ₅ . If the fundamental tone of the input audio signal is determined to be 440Hz, for example, as a result of frequency analysis,
Assuming that the input audio signal has the pitch of note name A ₄ , a note is displayed at the A ₄ position on the staff notation on the display, and for example, as a result of frequency analysis of the input audio signal, the input audio If the fundamental tone of the signal is determined to be 146.83Hz, the input audio signal is assumed to have the pitch of pitch name D ₃ ,
In a display format where a note is displayed at position D ₃ on the staff notation on the display, the pitch of the input audio signal is displayed as the pitch corresponding to each note name from F ₂ to F ₅ . This can be done when a certain audio signal is input.

By the way, the audio signals input to the musical note display device of the present invention are mainly acoustoelectrically converted sounds emitted from various musical instruments and electronic musical instruments, but musical instrument sounds vary depending on the type of musical instrument. The relationship between the strength of the overtones and the fundamental tone and the way the fundamental tone and overtones are combined are different.

Figures a to d are diagrams showing the results of frequency analysis of the sounds of various musical instruments (a in Figure 5 is the sound of a flute, b in Figure 5 is the sound of a clarinet, and c in Figure 5 is the sound of a violin ( d in Figure 5 is the sound of the contrabass (the E string of the contrabass)}, but for example, wind instruments such as the flute and clarinet shown in a and b of Figure 5. In this case, frequency analysis shows that the fundamental tone is stronger than any overtone (piano, guitar, etc. show the same tendency as wind instruments), and that in the case of violin and double bass, there are overtones that are stronger than the fundamental tone. This is the result.

As can be seen from the frequency analysis results of various musical instrument sounds illustrated in a to d of FIG. 5, the frequency components that make up the musical instrument sounds are Not only are there cases where the fundamental tone is the strongest, but there are also cases where the overtones are stronger than the fundamental tone, as shown in Figure 5 c and d.
Even if we frequency-analyze the input audio signal and extract the largest frequency component among the frequency components obtained as a result of the analysis, it does not necessarily mean that it is the fundamental tone, so we analyzed the frequency of the input audio signal. In order to determine the pitch of the fundamental tone of the input audio signal based on the result, and to display the note corresponding to the pitch of the fundamental tone at a predetermined position on the staff on the display surface, the pitch of the input audio signal must be determined. It is necessary to determine the fundamental tone of the input audio signal by looking at the relative relationship between the intensities of each frequency component obtained as a result of frequency analysis.

Therefore, in the musical note display device of the present invention, an FFT operation is performed using digital data obtained by converting an input audio signal into a digital signal by an AD converter ADC, and then a power spectrum calculation is performed. , Once each frequency component of the input audio signal has been obtained, it is determined in the frequency region lower than the frequency of the frequency component showing the largest spectral value among all the frequency components obtained by the frequency analysis means. Among the existing frequency components, a frequency component exhibiting a smaller spectrum value within a predetermined range than the spectrum value of the frequency component exhibiting the largest spectrum value is detected, and the detection means If the corresponding frequency component is not detected, the frequency of the frequency component showing the largest spectral value is determined to be the pitch (fundamental tone) of the input audio signal, and the detection means If a frequency component is detected by , the frequency of the lowest frequency component among the detected frequency components is determined to be the pitch (fundamental tone) of the input audio signal, The fundamental tone of the input audio signal is determined.

The fact that the fundamental tone of an input audio signal can be correctly found by the above-described method of determining the fundamental tone of an input audio signal will be explained with reference to a to d of FIG. 5.

If the frequency analysis results for the input audio signal indicate that the fundamental tone is the strongest, as shown in a and b in FIG. 5, it is natural that the fundamental tone is determined to be the fundamental tone of the input audio signal. In other words, the fundamental tone has the lowest frequency among the many frequency components obtained as a result of frequency analysis, so in this case, the frequency region lower than the fundamental tone, which has the largest spectral value, contains the frequencies generated by frequency analysis. There is no such component, and therefore, among the many frequency components obtained as a result of frequency analysis, the frequency value of the fundamental tone exhibiting the largest spectral value is determined as the fundamental tone.

In addition, if the result of frequency analysis of the input audio signal is that the spectral value of the overtone is larger than the spectral value of the fundamental tone, as shown in c and d in Figure 5, the frequency analysis result for the input audio signal is The largest of the many resulting frequency components {violin G shown in Figure 5c
In the case of a line, the third harmonic (3rd harmonic), d in Figure 5
The spectrum of the frequency component that exhibits the largest spectral value among the frequency components that exist in a frequency region lower than the frequency of the double overtone (second harmonic) in the case of the double bass E line shown in The frequency of a frequency component that exhibits a smaller spectral value within a predetermined range than the fundamental tone is determined as the fundamental tone.

In the case of the G-line sound (open string sound) of the violin shown in FIG.
In the case of the sound of the E string of the contrabass (open string) shown in d of FIG. 5, the above-mentioned "predetermined range" may be about 30 dB.

In the case where the frequency analysis result of the sound of a normal musical instrument shows that the spectral value of the overtone is larger than the spectral value of the fundamental tone, the spectral value of the harmonic with the largest spectral value and the spectral value of the fundamental tone are calculated. The level difference is within 10 dB, and the sound of the E line of the contrabass shown in d in FIG. 5 is an exception.

Therefore, when determining the fundamental tone, the frequency value of the frequency component with the largest spectral value is, for example, 100
Hz or less, there is a frequency component in the frequency region lower than the frequency of the frequency component with the largest spectral value that exhibits a level difference of, for example, within 30 dB compared to the spectral value of the frequency component with the largest spectral value. In cases other than the above, that is, the frequency value of the frequency component with the largest spectral value is, for example,
In the case of 100Hz or more, there is a frequency component in a frequency region lower than the frequency of the frequency component with the largest spectral value that shows a level difference of, for example, within 10 dB compared to the spectral value of the frequency component with the largest spectral value. If you check whether there is a sound or not, the fundamental tone in the input audio signal will always be correctly determined based on the above-mentioned criteria.

By the way, if the musical note display device is configured to be able to display the pitches of note names F ₂ to F ₅ , as shown in the example above, the above-mentioned display target Even when the highest-pitched pitch name _F5 is input, the display device must display a display corresponding to the pitch name _F5 , but as mentioned above, the input When determining the pitch (fundamental tone) of an audio signal, the spectral value or frequency value of the frequency component that indicates the largest spectral value obtained as a result of frequency analysis is required. In order for the sound of pitch name F ₅ to be determined based on the result of frequency analysis of the input audio signal, the frequency of the fundamental tone of pitch name F ₅ is 698.46.
Higher harmonic (at least third harmonic) components of Hz must also be obtained as correct values through frequency analysis.

Therefore, in a display device that also displays the pitch name _F5 , as in the example described above, anti-aliasing technology that limits the frequency band of the input audio signal is used.
As a filter AAF, its cutoff frequency fc is
The frequency value of pitch name F ₅ , which is 698.46Hz, must be set at least three times as high.

When configuring an actual device, it is desirable to use an anti-aliasing filter AAF whose cutoff frequency fc is set as high as other conditions allow (the anti-aliasing filter AAF's cutoff frequency Frequency fc and AD converter
The sampling frequency fs in the ADC, the frequency interval f of the spectrum obtained as a frequency analysis result,
The relationship with the number of pieces of data N, the relationship with the time required for FFT calculation, etc. have already been described).

In Figure 1, the digital signal output from the AD converter ADC is stored in the main memory RAM and used for FFT calculations, as described above, and the central control unit CPU is a read-only memory. It performs predetermined control operations and arithmetic operations according to the program written in ROM ₁ , and also operates the video display processor.
Provides data to the video RAM VRAM via the VDP. ROM ₂ is a high-speed read-only memory that stores programs for spectrum analysis, but FFT calculations are performed by the central controller CPU.
If the multiplier is used instead of the ROM 2 in FIG. 1, the configuration is such that the ROM ₂ in FIG. 1 is replaced with a multiplier.

The CRT in Figure 1 is a display, and in the following explanation, the display uses a cathode ray tube.
For example, if the pitch of the input audio signal is displayed,
This is done as shown in the figure.

Video display processor VDP is
It operates as an interface between the video ram V-RAM connected to it via the data bus 4 and the central control unit CPU, and also operates as an interface between the video ram V-RAM and the central control unit CPU. Therefore, the video display processor VDP is configured such that the image content is determined and can generate a composite video signal according to a predetermined standard method. , Nikkei McGraw-Hill, “Nikkei Electronics” March 30, 1981
It is possible to use the video display processor (VDP) manufactured by Texas Instruments, Inc., introduced in the Japanese issue (pages 156 to 164).・A processor is said to be used.

Figure 2 shows a video ram V.
FIG. 2 is a diagram showing an example of a memory map of RAM,
In the video RAM memory map shown in Figure 2, 1024 bytes from addresses 0 to 1023 are used as the sprite generator table SGT, and 768 bytes from addresses 1024 to 1791 are used as the pattern name table PNT. used,
Furthermore, 128 bytes from address 1771 to address 1919 are used as the sprite attribute table SAT,
Furthermore, 32 bytes from address 1920 to address 1951 are used as color table CT, and
96 bytes from addresses 1952 to 2047 are unused, and 2048 bytes from addresses 2048 to 4095 are used as the pattern generator table PGT.

The pattern generator table PGT is
For example, one specific pattern can be stored in 8 pixels x 8 pixels using 8 bytes each, so 8 x
It can store 256 types of patterns with 8 pixels.
The pattern information stored in this pattern generator table PGT is stored in the central controller
The pattern generator table is transferred from the read-only memory ROM in the initial state of the device by the operation of the CPU.
Of course, the PGT may be a read-only memory.

As mentioned above, each 8-byte storage area in the pattern generator table PGT individually stores specific patterns of 8×8 pixels. To enable a specific pattern to be specified by a pattern name given to each storage area in which a specific pattern is stored. Pattern generator table PGT of the example shown in the second diagram
In this example, 256 types of patterns can be specified using 256 pattern names from pattern name #0 to pattern name 255.

Next, the pattern name table PNT is used to store information indicating which pattern name in the pattern generator table PGT each of the display sections assumed on the display surface of the display CRT corresponds to. It has a storage capacity corresponding to the total number of displayed display sections.

In the example shown in Figure 3, the total number of sections set on the display screen is {(32 columns) x (24 rows)} = 768, and since 1 byte is used as the amount of information indicating one section, as described above Pattern name table like PNT
is said to have a storage capacity of 768 bytes.

As mentioned above, the required number of patterns are stored in the pattern generator table PGT in the video RAM VRAM, and the required pattern names assigned to each pattern are as follows. Pattern name table PNT
When the video display processor VDP is stored in each section of the display screen in
Information stored in the pattern name table PNT in the video RAM VRAM described above,
Generates a composite video signal according to a specific standard format whose image content is defined by the information stored in the pattern generator table PGT and, if necessary, the information stored in the color table CT. A specific pattern is displayed on the display surface of the display CRT.

The discussion so far has focused on pattern generators and
The specific pattern stored in the table PGT is 768 on the display screen.
This relates to the case where a pattern is displayed in a display mode in which it is displayed on a specific section of a section, a so-called graphic mode. Since the position of the pattern is specified by the table PNT, when an attempt is made to move one pattern on the display screen, the pitch of pattern movement is one section (distance of 8 pixels) on the display screen.

Therefore, in order to reduce the pitch of movement of the pattern on the display surface and make the pattern move smoothly, it is necessary to use the sprite generator table.
The pattern stored in the SGT is moved within the display screen by one pixel pitch by changing the coordinates.

The patterns stored in the sprite generator table SGT may be 8 pixel x 8 pixel sprite data or 16 pixel x 16 pixel sprite data.
Each pattern stored in the sprite generator table SGT is individually given a sprite name such as #0, #1...#N, but the sprite surface corresponding to the pattern with each sprite name is The smaller the numerical value indicated by the sprite name, the higher the priority.

In the memory map of the video RAM VRAM illustrated in FIG. 2, 1024 bytes from address 0 to address 1023 are assumed to be used as the sprite generator table SGT, as described above. In this example, if the pattern is 8 pixels x 8 pixels, 128 patterns (sprite names #0 to #127) can be stored, and if the pattern is 16 pixels x 16 pixels, 32 Patterns (sprite names #0 to #31) can be stored. It goes without saying that if 2048 bytes are allocated to the sprite generator table SGT in the video RAM A RAM, the number of patterns stored in the sprite generator table SGT will be twice as large as in the previous case. Not even.

The sprite attribute table SAT uses 4 bytes for each sprite, and contains the sprite's position (1 byte each for specifying vertical and horizontal positions), display sprite name (1 byte), color code, and Since the end code (1 byte) of the displayed sprite is set, if 128 bytes are used as the sprite attribute table SAT, information for 32 sprites is stored in this sprite attribute table SAT.

The position of the sprite is determined by 256 pixels (8 pixels x 32 sections) in the horizontal direction (X direction) and 192 pixels (8 pixels x 24 sections) in the vertical direction (Y direction) on the display screen.
49152 The coordinates of the pixel, the vertical position (the number that indicates the number of pixels in the vertical direction) and the horizontal position (the number that indicates the number of the number of pixels in the horizontal direction) are stored in the sprite attribute table SAT. (The origin of the sprite is set to the upper left corner of the sprite), and the sprite can be moved at a pitch of one pixel.

In the musical note display device of the present invention, the pattern generator table PGT and the sprite
Multiple types of patterns are stored in the generator table SGT, and the selection of the pattern to be displayed on the display surface of the display CRT and the specification of pattern movement are performed in the pattern name table PNT and sprite attribute table SAT. Based on the written data, a display as shown in FIG. 4, for example, is displayed on the display surface of the display CRT.

In FIG. 4, which shows the display mode on the display screen of a display CRT, figures such as staff notation, treble clef, bass clef, and other musical symbols are stored and prepared in advance in read-only memory ROM ₁ . When the note display device starts operating, the above-mentioned read-only memory
The various patterns stored in ROM ₁ are transferred to the pattern generator table PGT in the video RAM VRAM via the central controller CPU and the video display processor VDP.
It is transferred and stored in the sprite generator table SGT and used for display operations on the display surface of the display. Further, the musical note-shaped mark S shown on the musical staff in FIG. 4 is displayed on the display surface of the display CRT in correspondence with the pitch of the input audio signal.

The central control unit CPU creates the data necessary to display the pitch of the input audio signal, provides it to the video display processor VDP and video RAM VRAM, and displays it on the display surface of the display. 4. The pitch of the sound is displayed using a musical note-like figure as shown in the figure.

The way the notes are displayed on the display surface of the display CRT is that they are arranged sequentially from left to right on the staff by a predetermined number (for example, 26), and are cleared each time they are finished, or they are displayed on the staff. After a predetermined number of notes have been arranged sequentially from left to right, the next note is always displayed at the rightmost edge of the display screen, and the display position of the previously displayed note is may be displayed in such a way that each of the images is moved one by one to the left, a so-called scroll display, or any other suitable display form may be adopted.

Now, the operation mode of the musical note display device shown in FIG.
Settings are made by operating an information input means such as keys, but when the information input means provided on the operation unit OP is operated, the input information is given to the central control unit CPU, and A display indicating that the information input means has been operated (for example, a display using a light emitting element) is displayed on the operation unit OP.

When the reference tone generation push button switch provided in the operation section OP of the musical note display device is operated, the reference tone signal generator SSG starts operating, and the clock signal Sc generated by the clock signal generator CSG is activated. is applied to the input port CRU of the central control unit CPU, and also to the frequency dividing means DIV.

Signals Sh, Ss, Sl output from frequency dividing means DIV
The signal selected by the changeover switch SW is supplied to the speaker SP via the filter F and the amplifier AMP. The performer uses the reference tone emitted from the speaker SP to tune an instrument or tune for chorus.

The central control unit CPU determines the frequency (or period) of the clock signal Sc given to the input port CRU.
Look at this and set the sampling period for AD conversion. When the push button switch for displaying musical notes on the operation section OP is operated, the push button switch for generating the reference tone is restored, and the display of musical notes changes in accordance with the pitch of the audio signal supplied to input terminal 1. done on the display surface.

Next, the operation of the musical note display device of the present invention will be explained with reference to the flowchart shown in FIG. 6th
In the illustrated flowchart, the power is turned on at the start, the musical note display device is started,
In step 1, initialization (system initialization) is performed to clear the AD converter ADC, main memory RAM, video RAM VRAM, etc., and also to clear which storage area in the video display processor VDP is used for what purpose. The area used for the table is set, the operation mode _is set, and the sampling period for AD conversion is set to a specific initial value. Transfers predetermined types of pattern information (for example, various graphic information shown in FIG. 4) to the generator table PGT, sprite generator table SGT, etc. via the video display processor VDP. , Also, for the sprite attribute table SAT, the sprite name,
The Y coordinate and color data are transferred.

After the device is brought into the normal operating state, the central control unit CPU executes steps 2, 3, and 6 until an interrupt shown in the flowchart of FIG. 6 occurs.
Each of the control operations in steps 1 to 10 is repeatedly executed, but when an interrupt occurs at each specific sampling period set in the internal counter provided in the central control unit CPU, the central control unit CPU teeth,
The control operation being executed at that time is interrupted and the control operations shown in steps 11 to 13 are performed, and when the control operations are completed, the execution of the control operation that was previously interrupted due to the occurrence of the interrupt is continued.

That is, the central control unit CPU performs the control operations of steps 2 to 10 within the time period in which it performs the control operations for the AD converter ADC.

Now, the internal counter provided inside the central control unit CPU is turned on in step 2 (A/D preset), and when an interrupt is generated every sampling period set in the internal counter, the central control unit CPU gives a start pulse for AD conversion operation to the AD converter ADC, and in step 11, the AD converter ADC starts
Performs AD conversion and stores the output digital signal in the main memory RAM.

In step 12, it is checked whether the AD conversion operation in the AD converter ADC has been performed a predetermined number of times (whether a predetermined number of digital data have been obtained), and if NO, the process returns, and if YES, the process proceeds to step 13. , the internal counter is turned off (A/D preset) in step 13, and the process returns.

After the initialization in step 1 described above is completed,
In step 2, perform switch scan and A/D preset, turn on the internal counter, and turn on the operation section.
Check the input conditions set in OP and proceed to step 3
Proceed to. In step 3, the push button switch for generating the reference sound is operated and it is checked whether the reference sound is being generated. If YES, proceed to step 4 and measure the frequency (or period) of the clock signal Sc. In step 5, the clock signal Sc
The sampling period of AD conversion is set according to the frequency (period may also be used) value, and the process returns to step 2.

If NO in step 3, that is, the reference sound is not generated, the process proceeds to step 6. When a predetermined number n of digital data is stored in the main memory RAM, an FFT operation is performed using the n digital data in step 6, and n/2 spectral data as a result of the operation is stored in the main memory RAM. Store in.

The FFT operation can be performed in a short time by the central control unit CPU according to a program stored in the high-speed read-only memory ROM ₂ , or by using a multiplier. It's okay. Either of the above methods
Whether or not to perform FFT calculations can be determined depending on how closely the display on the display device needs to approximate real time.

In step 7, a power spectrum calculation is performed on the spectrum data obtained in step 6, and the calculation result is stored in the main memory RAM.

In step 8, the pitch of the sound is determined based on the spectrum data stored in the main memory RAM, and the details of the determination of the pitch are as follows. That is, first, one of the spectrum data stored in the main memory RAM that exhibits the largest spectral value is found, and in the next step, the one that exists in the frequency range lower than the frequency of the spectrum that shows the largest spectral value is determined. Then, find the frequency value of the spectrum that shows the lowest frequency value among the spectra that have a smaller spectral value within a predetermined range than the spectrum size of the largest spectral value, and use it as an input. Pitch of audio signal (fundamental tone)
If there is no spectrum that satisfies the above conditions, the frequency value of the spectrum with the largest spectral value is determined to be the pitch (fundamental tone) of the input audio signal. .

The pitch of the audio signal described above can be easily determined by referring to a table of frequencies versus pitch names provided in the main memory RAM.

In the musical note display device of the present invention, as described above, the AD
Since the sampling frequency (or period) of the conversion operation is variably set, even if the reference sound generated by the reference sound signal generator SSG deviates from the frequency vs. sound name table provided in the device, Since the deviation is automatically corrected by the deviation in the sampling period of the AD conversion operation mentioned above, the pitch of the audio signal can be determined based on the frequency versus pitch name table provided in the main memory RAM. By reference you can always do it right.

Next, in step 9, data to be written in the pattern name table PNT, corresponding to the data value indicating the pitch determined in step 8, is determined.
The data to be written to the sprite attribute table SAT is created, and then, in step 10, the above data is transferred to the video RAM VRAM via the video display processor VDP, and the video display processor VDP performs the above process. In this way, a composite video signal is created using the data written to the video RAM VRAM, and it is sent to the display CRT, and a musical note-shaped figure 5 as shown in Figure 4 is displayed on the display surface of the display CRT. to display the pitch of the sound.

In Fig. 4, 2 and 3 are staff-shaped figures, 5, 5... are musical note-shaped figures, 6 is a rest-like figure, and one musical note-shaped figure 5 is displayed.
The time interval from when it is displayed on the display screen of the CRT until the next musical note-shaped figure 5 is newly displayed on the display screen is the repetition period of steps 2, 3, 6 to 10. For example, if a maximum of 26 graphic displays 5 and 6 are displayed one after another in the horizontal direction on the display surface of a display CRT, the repetition period of steps 2, 3, 6 to 10 described above is, for example, 200 milliseconds, the length of the input audio signal is 5.6 seconds, and the display CRT
26 display figures 5 and 6 are lined up on the display screen.

FIG. 7 shows an overall configuration diagram of a musical note display device of the present invention which operates as described above.

(Effects) As is clear from the above detailed explanation, the musical note display device of the present invention uses an analog-to-digital conversion means for converting an audio signal into a digital signal, and a certain number of data of the digital signal. means for performing FET calculation using the FET calculation and power spectrum calculation using the calculation result to perform frequency analysis; means for determining the pitch of the audio signal based on the frequency analysis result; A musical note display device comprising: means for displaying a determination result by the pitch determining means in a note-shaped figure in a part corresponding to the pitch of the musical staff-like display figure; , means for generating a reference tone for articulation, means for generating a reference tone signal capable of supplying an arbitrary reference tone signal to the sound generation means, and a means for generating a reference tone for producing an articulation whose pitch is normal. The reference tone signal generating means is provided in such a way that even if the sound deviates from the standard tone, the sound is displayed on the display surface of the display in the same manner as if the performance were performed based on the regular reference tone. and means for changing and setting the sampling period in the analog-to-digital conversion means in accordance with the repetition period of a clock signal generated by a clock signal source that generates a clock signal with a variable repetition period. Therefore, when a reference tone for articulation is emitted and the emitted reference tone is used to tune a musical instrument, etc., it is provided in the generator of the reference tone signal that is supplied to the sound generation means. Depending on the repetition period (or frequency) of the clock signal generated by the clock signal generator, the AD
Since the sampling period of the conversion means is variable, even if the reference tone used for articulation deviates from the regular reference tone and the performance is performed based on the deviated reference tone, the note In this display device, the pitch of the pitch is displayed in the same display manner as when the performance is performed based on the correct reference tone, at the correct corresponding position of the staff-shaped figure on the display surface of the display. Therefore, according to the device of the present invention, it is possible to easily provide a musical note display device that does not have the problems of the conventional devices described above.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the musical note display device of the present invention, FIG. 2 is an example of a memory map of a video ram, and FIG. 3 is an explanatory diagram of the divisions of the display surface.
FIG. 4 is an example of a display pattern on a display surface, FIG. 5 is a spectral distribution diagram of musical instrument sounds, FIG. 6 is a flowchart, and FIG. 7 is an overall configuration diagram of the apparatus of the present invention. 1...Input terminal, SW...Selection switch, CSG
...Clock signal generator, SSG...Reference tone signal generator, GEQ...Graphic equalizer,
AAF...Anti-aliasing filter,
ADC: AD converter, CPU: central control unit (microcomputer), RAM: main memory, ROM ₁ , ROM ₂ : read-only memory,
CLD...Operation control section, OP...Operation section, V.
RAM...Video RAM, VDP...Video display processor, DIV...Divide means,
CRT...display, AMP...amplifier, SP
...Speaker, F...filter, BA...buffer amplifier.

Claims (1)

[Claims] 1. Performing an FFT operation using an analog-to-digital conversion means for converting an audio signal into a digital signal and a certain number of data of the digital signal,
Means for performing frequency analysis by performing power spectrum calculation based on the result of the calculation; means for determining the pitch of the audio signal based on the result of the frequency analysis; and a staff-like display figure on the display surface of the display. A musical note display device comprising means for displaying the judgment result of the above-mentioned pitch judgment means in a note-shaped figure in a portion corresponding to the pitch of the note, the standard for articulation. a sound generating means; a reference sound signal generating means capable of supplying an arbitrary reference sound signal to the sound generating means; In order to display the sound on the display surface in the same manner as when the performance is performed using the regular reference tone as a reference, the repetition period of the reference tone signal generating means is variable. A musical note display device comprising means for changing and setting a sampling period in an analog-to-digital converting means in accordance with a repetition period of a clock signal generated by a clock signal source that generates a clock signal. 2. A patent that allows a standard tone emitting means for articulation to selectively emit a tone one octave higher and lower than the pitch of a specific standard tone. Claim 1
The musical note display device described in Section 1.