JPH056199B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is capable of displaying a note-shaped figure corresponding to the pitch of an audio signal in a corresponding part of a staff-shaped display figure on a display. The present invention relates to a musical note display device.

(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 lamp on a staff-shaped display board is turned on by a switch operated by pressing a keyboard, 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 uses the result of the pitch determination to determine the corresponding pitch in the staff notation on the display. The above-mentioned problem has been solved by providing a musical note display device that displays a desired display on the corresponding portion of the keyboard, or on a display. When creating a musical score by transcribing the sounds played by an instrument, the standard tone of the instrument (usually note A ₄ is taken as the standard tone) matches the standard tone on the note display device. When you don't,
It happens that the transcribed musical score ends up being inaccurate.

In other words, if a musical note display device uses, for example, note A ₄ (440Hz) as its reference tone, and the notes of other note names are tuned to the pitch of 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 provides an audio signal that is considered to be a reference sound with a predetermined pitch name for articulation, that is,
An audio signal obtained when a predetermined note name is sounded from a musical instrument (as already mentioned, this audio signal often has a frequency value that deviates from the original frequency value of the note name) ), convert it into a digital signal, and use that digital signal to perform frequency analysis. Performed at a sampling period suitable for frequency analysis of the audio signal of the reference sound to be
The pitch of the tone determined based on the frequency analysis result performed using the resulting digital signal is determined as the pitch of the reference tone corresponding to the predetermined note name for articulation. The present invention provides a musical note display device that does not suffer from the above-mentioned problems by setting the sampling period in the analog-to-digital conversion operation as shown in FIG.

(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 one embodiment of the musical note display device of the present invention. In this FIG. It is applied to the switch SWa of the selection switch SW via the buffer amplifier BA.

The selection switch SW is the switch SWa, SWb,
The switch is equipped with SWc, and according to the operation mode set in the operation unit OP, the above-mentioned switch is activated by a switching control signal sent from the operation control unit CLD.
The on/off states of SWa to SWc are controlled.

When the switch SWa in the selection switch SW is turned on, the input audio signal is converted to an analog-to-digital converter ADC (hereinafter referred to as analog) via a graphic equalizer GEQ and anti-aliasing filter AAF. - Digital conversion is referred to as AD conversion).

Also, switch SWb in selection switch SW
When it is turned on, the reference audio signal generated by the reference audio signal generator SSG is sent to the AD converter via the graphic equalizer GEQ, anti-aliasing filter AAF, etc.
Allow to be given to ADC.

Furthermore, the switch in the selection switch SW
SWc when it is turned on,
The reference audio signal generated by the reference audio signal generator SSG is provided to the speaker SP via the amplifier AMP.

Controls such as switching the characteristics of the graphic equalizer GEQ mentioned above and switching the frequency of the reference audio signal generated by the reference audio signal generator SSG are also controlled by the operation control unit CLD according to the operation mode set in the operation unit OP. This is done by a switching control signal generated by.

The reference audio signal generator SSG is, for example, pitch name A ₄
440Hz sine wave signal as the reference audio signal,
It is configured to be able to generate a 261.63 Hz sine wave signal as a reference audio signal with pitch name C ₄ and sine wave signals of other necessary frequency values in a switchable manner.

In Figure 1, the CPU is the central control unit,
The digital signal obtained by AD conversion by the above-mentioned AD converter ADC is stored in the main memory RMA under the control of the central control unit CPU, and is used for FFT calculation.

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 fs 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 an analysis result by FFT calculation at a frequency interval f of a spectrum of 10 Hz, 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 can be expressed by the note name of the three octaves that can be represented by the staff notation displayed on the display surface, that is, the position on the staff and keyboard corresponding to F ₂ to _{F 5} . If you want to display it in the upper position, as a result of frequency analysis,
If the fundamental tone of the input audio signal is determined to be, for example, 440Hz, the input audio signal is assumed to have the pitch of pitch name _A4 , and the staff notation on the display is
A musical note is displayed at position _A4 , and for example, as a result of frequency analysis of the input audio signal,
If it is determined that the fundamental tone of the input audio signal is 146.83Hz, the input audio signal is assumed to have the pitch of pitch name D ₃ , and a note is displayed at the position of D ₃ on the staff on the display. The display of the pitch of the input audio signal in a display mode such as
This can be done when audio signals of pitches corresponding to the pitch names from _F2 to _F5 are input.

By the way, the audio signals input to the musical note display device of the present invention are mainly acousto-electrical 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 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 is the fundamental tone the strongest, but also 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. Based on the result, the pitch of the fundamental tone of the input audio signal is determined, and the note corresponding to the pitch of the fundamental pitch is displayed at a predetermined position on the staff on the display surface, or the pitch of the fundamental tone of the input audio signal is determined. In order to display the mark at the display position of the corresponding key, the fundamental tone of the input audio signal is determined by looking at the relative relationship between the strengths of each frequency component obtained as a result of frequency analysis of the input audio signal. It is necessary to decide.

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 spectral value within a predetermined range than the spectral value of the frequency component exhibiting the largest spectral value is detected; Therefore, 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 When a frequency component is detected by the means, 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 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 the 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 the sound F ₅ is 698.46.
Higher harmonic (at least third harmonic) components of Hz must also be obtained as correct values through harmonic number 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. Performs predetermined control operations and arithmetic operations according to the program stored in ROM ₁ , and also operates the video display processor VDP.
Provides data to the video RAM via the VRAM. ROM ₂ is a high-speed read-only memory that stores programs for spectral analysis, but if the FFT calculation is not performed by the central controller CPU but is performed by the multiplier, the ROM in Figure 1 is used. The configuration is such that part ₂ is changed to 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. , use the Video Display Processor (VDP) from Texas Instruments, Inc., which was introduced in Nikkei McGraw-Hill's "Nikkei Electronics" March 30, 1981 issue (pages 156 to 164). The following explanation will be based on the video and video mentioned above.
A display 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 address 0 to 1023 are used as the sprite generator table (SGT), and 1024 bytes from address 1024 to 1791 are used as the sprite generator table (SGT).
768 bytes are used as the pattern name table (PNT), plus
128 bytes are used as the sprite attribute table (SAT), 32 bytes from addresses 1920 to 1951 are used as the color table (CT), and 96 bytes from addresses 1952 to 2047 are used as the color table (CT).
The bytes are unused and are from addresses 2048 to 4095.
2048 bytes 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
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 spot #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. The total number of displayed sections and the corresponding storage capacity are also included.

In the example shown in Figure 3, the total number of sections set on the display screen is {(32 columns) x (24 columns)} = 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,
Information stored in the pattern name table PNT in the video RAM V.RAM, information stored in the pattern generator table PGT, and information stored in the color table CT as necessary. A composite video signal is generated in accordance with a specific standard format whose image content is determined by the system, and is applied to the display CRT, so that 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 in a specific section among the sections, a so-called graphic mode. Since the position of the pattern is specified by the PNT, when one pattern is to be moved 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 PGT 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 PGT in the video RAM VRAM, the number of patterns stored in the sprite generator table SGT will be twice that of 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 V.RAM, and sends it to the display screen 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, as mentioned above, the pitch of the input audio signal can be accurately displayed using the note-shaped figure on the display surface of the display CRT using the staff-shaped figure on the display surface of the display CRT. This is a case where the pitch (frequency) of the reference tone employed in the musical note display device and the pitch (frequency) of the reference tone of the audio signal supplied to the input terminal 1 are the same.

Before a musical instrument is played, the standard tone is tuned using a tuning fork, for example, but it is rare that the pitch of the musical instrument's standard tone is adjusted to the original pitch of the standard tone. In addition, if the tuning of the reference tone is performed without using a standard tone from a tuning fork, etc., the pitch of the reference tone of the tuned instrument is the same as the pitch of the reference tone adopted by the note display device. Usually, there is a considerable gap between the two.

Therefore, in the musical note display device of the present invention, the height of the reference tone of the audio signal supplied to the input terminal 1 as a reference tone of a predetermined note name for articulation, and the pitch adopted in the musical note display device. When the pitch of the reference tone used is different from the pitch of the reference tone adopted by the note display device, the pitch of the reference tone of the audio signal supplied to input terminal 1 is displayed as the pitch of the reference tone adopted by the note display device. The sampling period in the AD converter ADC is automatically set so that The FFT calculation is performed so that the pitch of the reference tone corresponding to the signal (used as a reference tone for articulation) is displayed as the pitch of the reference tone adopted by the note display device. Under the condition that the number of data of the digital signal used is constant, the sampling period in the AD converter ADC is automatically set. Even if the pitch of the instrument (the same is true) is off from the original reference pitch, the pitch of the reference pitch of the instrument that is off is displayed on the display as being the original reference pitch. The display is made in this manner.

Now, the operation mode of the musical note display device shown in FIG. 1 is set by operating input means such as keys or switches provided on the operation section OP. When the input means is operated, a display indicating that the input means has been operated (for example, a display using a display device using an emitting element) is displayed on the operation unit OP, and a display indicating that the input means has been operated is displayed on the operation unit OP. The switch SWa in the selection switch SW corresponds to the operation mode selected.
The on/off switching state of SWc is determined.

That is, the pitch of the reference tone on the note display device is set to the pitch of the audio signal supplied to the input terminal 1 as a reference tone of a predetermined pitch name for articulation. If you want to operate in an operation mode in which the pitch of the input audio signal is determined and the shape of musical notes is displayed on the display screen, select the selection switch SW The switch SWa is turned on and the switches SWb and SWc are turned off, and the note display device changes the pitch of the reference audio signal generated by the reference audio signal generator SSG built into it. The pitch of the input audio signal is determined by matching the pitch of the reference tone on the display device, and the system operates in an operation mode in which musical note shapes are displayed on the display surface of the display. The on/off state of each of the selection switches SWa to SWc in the case of selection switch SW is such that switch SWa is first turned off, switch SWb (and switch SWc) is turned on, and then the built-in reference audio signal generator SSG is turned on. The pitch of the reference sound on the note display device is made to match the pitch of the reference sound signal using the reference sound signal generated in When the pitch of the reference tone is matched, switch SWa of selection switch SW is turned on, and the switch is turned on.
SWb (and switch SWc) is turned off.

Changes in the switching states of the switches SWa to SWc in the selection switch SW described above, which are performed in accordance with the operation mode set using the input means in the operation part OP, are performed according to the operation mode set by the input means in the operation part OP. This is performed by a switching control signal sent via the operation unit control unit CLD by the central control unit CPU, which operates accordingly.

As mentioned above, the height of the reference tone on the note display device is adjusted to the pitch of the audio signal that is supplied to the input terminal 1 and is to be used as the reference tone, or the pitch of the built-in reference audio signal is adjusted. To match the pitch of the reference sound signal generated by the generator SSG, operate the reference sound setting switch provided on the operation unit OP.

Next, the operation of the musical note display device will be explained with reference to the flowchart shown in FIG. In the flowchart shown in Figure 6, at the start, the power is turned on and the musical note display device is started, and at step (1), initialization (system initialization) is performed, and the AD converter ADC, main memory RAM , the video RAM VRAM, etc. are cleared, and registers in the video display processor VDP are set to determine which storage area in the video RAM VRAM is used for what table. Settings, operation mode settings, etc. are performed, and
The sampling period for AD conversion is set to a specific initial value, and _furthermore , predetermined types of pattern information (for example, 4) is transferred via the video display processor VDP,
Further, the sprite name, X and Y coordinates, and color data are transferred to the sprite attribute table SAT.

The central control unit CPU repeatedly executes each control operation of each step from step (2) to step (10) until an interrupt shown in the flowchart of FIG. 6 occurs. Device
When an interrupt occurs at each specific sampling period set in the internal counter provided in the CPU,
The central control unit CPU interrupts the control operation being executed at that time and performs the control operations shown in steps (11) to (13), and when the control operation is completed, the control operation is interrupted by the occurrence of an interrupt first. Continue execution of the control action that was being performed.

That is, the central control unit CPU performs the control operations of steps (2) to (10) at times other than when it performs control operations for the AD converter ADC.

Now, when the internal counter provided inside the central control unit CPU turns on in step (2) (A/D preset) and generates an interrupt at each sampling period set in the internal counter, the central control unit The CPU gives the AD converter ADC a start pulse for AD conversion operation, 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 returns to step (12). Proceed to step (13), turn off the internal counter (A/D preset), and return.

In step (2), perform switch scan and A/D preset, turn on the internal counter, check the input conditions set on the operation panel OP, and then proceed to step (2).
Proceed to (3).

When a predetermined number n of digital data is stored in the main memory RAM as described above,
In step (3), n pieces of digital data are used.
FFT evaluation is performed, and n/2 spectral data resulting from the evaluation are stored in the main memory RAM.

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. using 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 (4), power spectrum calculation is performed on the spectrum data obtained in step (3), and the calculation result is stored in the main memory RAM.

In step (5), set the reference tone (control section
In the OP, check whether the reference tone setting switch is operated or not. If YES, step (6) sets the pitch of the tone (in this case, the reference tone) based on the spectrum data stored in the main memory RAM. is determined, and in step (7), the sampling period in the AD converter ADC is set corresponding to the pitch of the sound described above, and the process returns to step (2).

Based on the result of the reference pitch determination in step (6), the sampling period set in step (7) is set to the specific initial sampling period set in step (1), That is, a predetermined standard sampling period is used as a sampling period suitable for frequency analysis of the audio signal of a reference tone corresponding to a predetermined pitch name for articulation (for example, A ₄ or C ₄ ). The pitch of the audio signal of the reference tone whose pitch was determined in step (6), that is, the pitch of the audio signal that is considered to be the reference tone of the predetermined pitch name for articulation, is the same as that for articulation. The sampling period is set such that a frequency analysis result determined as the pitch of a reference tone corresponding to a predetermined note name (for example, A ₄ or C ₄ ) can be generated.

For example, suppose that the predetermined pitch name for articulation is A ₄ , and the sampling period of the specific initial value for AD conversion that was set in step (1) is
Suppose that the pitch (frequency) of the audio signal, which is said to be the reference tone of the predetermined pitch name A ₄ for articulation, is from the original frequency of audio A ₄ , 440 Hz. Higher (or lower) by α%
If the sampling period for AD conversion to be set in step (7) is α% shorter (or longer) than the initial value sampling period Ts. It is.

Even if the predetermined reference tone for articulation is C ₄ (any other specific note name), the predetermined note name for articulation is C ₄ (any other specific note name). The pitch (frequency) of the audio signal that is said to be the reference tone of C ₄ (or any other specific note name) is only α% from the original frequency of 261.63Hz (each specific frequency). If the deviation is higher (or lower), the sampling period for AD conversion that should be set in step (7) is
Initial value sampling period Ts set in step (1)
It is made shorter (or longer) by α% than .

If the determination result in step (5) is NO, the pitch of the sound is determined in step (8) based on the spectrum data stored in the main memory RAM, and the process proceeds to step (9).

The details of the pitch determination carried out in step (6) and step (8) described above are as follows. That is, first, find the one showing the largest spectral value among the spectral data stored in the main memory RAM,
The next step is to select a spectral value that exists in a frequency region lower than the frequency of the spectrum showing the largest spectral value and is smaller within a predetermined range than the spectral size of the largest spectral value. The frequency value of the spectrum that shows the lowest frequency value among the spectra that it has is determined to be the pitch (fundamental tone) of the input audio signal, and if there is no spectrum that meets the above conditions. In this case, the frequency value of the spectrum showing 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 the table of frequencies versus pitch names provided in the main memory RAM. , when a plurality of predetermined pitch names for articulation are prepared, a plurality of them are often prepared.

Next, in step (9), data to be written in the pattern name table PNT is determined in correspondence with the data value indicating the pitch determined in step (8).
The data to be written to the sprite attribute table SAT is created, and then, in step (10), the data is transferred to the video RAM V.RAM via the video display processor VDP, and the video display processor VDP: Create a composite video signal using the data written to the video RAM V.RAM as described above, send it to the display CRT, and display it on the display surface of the display CRT.
The pitch of the sound is displayed by a musical note-like figure 5 as shown in the fourth figure.

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 shown in steps (2) to (5) and (8). It roughly corresponds to the repetition period of ~(10), for example, the display
When a maximum of 26 graphic displays 5 and 6 are displayed one after another in the horizontal direction on the display screen of a CRT, the repetition period of steps (2) to (5) and (8) to (10) described above is for example
If it was 200 milliseconds, the input audio signal would be
Corresponding to the length of 5.6 seconds, 26 display figures 5 and 6 are lined up on the display surface of the display CRT.

(Effects) As is clear from the detailed explanation above, in the musical note display device of the present invention, the AD conversion operation is performed on an audio signal that is considered to be a reference tone of a predetermined note name for articulation. using a digital signal obtained by performing this at a predetermined standard sampling period suitable for frequency analysis of the audio signal of a reference tone corresponding to a predetermined pitch name for articulation. Sampling in the AD conversion means so that frequency analysis is performed and the pitch determined based on the result is determined as the pitch of a reference tone corresponding to a predetermined pitch name for articulation. Since the cycle is set to a value shifted from the reference sampling cycle described above, the pitch of the input audio signal is displayed to the performer in accordance with the staff-shaped figure. Therefore, the above-mentioned conventional problems can be satisfactorily solved, and the device of the present invention is a musical note display device that does not have the above-mentioned problems with the conventional devices. can be easily provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the musical note display device of the present invention, FIG. 2 is an example of a memory map of a video RAM, FIG. 3 is an explanatory diagram of the divisions of the display surface, and FIG. 4 is a display An example of the screen display pattern, FIG. 5 is a spectral distribution diagram of musical instrument sounds, and FIG. 6 is a flowchart. 1...Input terminal, SW...Selection switch, SSG
...Reference audio 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 unit, OP
...Operation unit, V RAM...Video RAM, VDP
...video display processor, CRT
...Display, AMP...amplifier, SP...speaker.

Claims (1)

[Claims] 1 Perform FFT calculation using an analog-to-digital conversion means that converts an audio signal into a digital signal and a certain number of data of the converted digital signal, and perform frequency analysis by performing power spectrum calculation on the result of the calculation. means for determining the pitch of the audio signal based on the frequency analysis results; and means for determining the pitch of the sound at a portion corresponding to the pitch of the musical staff drawn on the display surface of the display. A musical note display device comprising means for displaying a determination result in a musical note shape,
Means for inputting an audio signal that is a reference tone of a predetermined pitch name for articulation, and a standard corresponding to the predetermined pitch name for articulation, and an analog-to-digital conversion operation for the audio signal. Frequency analysis performed using a standard sampling period predetermined as a sampling period suitable for frequency analysis of a sound audio signal, and a digital signal obtained by the analog-to-digital conversion operation. The sampling period in the analog-to-digital conversion means is set so that the pitch of the sound determined based on the result is determined as the height of the reference sound.
and means for setting a value shifted from the reference sampling period.