Apparatus for displaying musical notes indicative of pitch and time value

What is claimed is:

1. A musical note display device for displaying musical notes each indicative of pitch and time length of each sound of an input audio signal on a displayed staff, comprising:

(a) analog-to-digital converting means for converting said input audio signal into digital data by using sampling pulses having a sampling frequency;

(b) computing means for effecting FFT operation by using said digital data, for executing power spectrum calculation by using a result of sid FFT operation, for determining a pitch of each sound by using spectrum data obtained by said power spectrum calculation, for determining a time value of each sound by measuring time length of each sound, and for determining a pattern to be displayed in accordance with the pitch and time value of each sound;

said computing means determining the pitch by obtaining a fundamental tone by obtaining a frequency component whose level is lowest within a predetermined level range from a highest level, and whose frequency is lower than a frequency at which the level is the highest, and, in case such a frequency component is not detected, determining the pitch by regarding the frequency component, whose level is the highest, as the fundamental tone;

said computing means determining the time value by measuring time length for which each sound is regarded as continuous, where each sound is regarded as continuous when frequency difference and level difference between two consecutive detections are both within predetermind ranges, and when the level of said sound is above a predetermined level; and

(c) display means including a video display processor, a video RAM and a display unit, said video display processor being controlled by said computing means to store data indicative of said pattern into said video RAM, and said display unit being responsive to a video signal from said video display processor for indicating musical notes displayed at appropriate position on a display staff.

2. A musical note display device as claimed in claim 1, wherein said computing means is arranged to execute said FFT operation, said power spectrum calculation and the pitch determination within a time period which is one-half a time length of a musical note having a shortest time value so that another set of FFT operation, power spectrum calculation and pitch determination is continuously effected immediately after a first set of these operations only when said input sound is determined as noncontinuous and the number of times of execution of said second set of operations is of an odd number.

3. A musical note display device as claimed in claim 1, wherein said computing means is arranged to display a musical note indicating only the sound pitch when the sound pitch has been determined, and to change the pattern of said musical note so that time value is indicated when said sound is continuous for a predetermined period of time.

4. A musical note display device as claimed in claim 3, wherein said computing means is arranged to change the pattern of said musical note such that a musical note indicating a shortest time value is displayed first in place of said musical note indicating only the sound pitch and then a musical note indicating a longer time value is displayed in sequence in place of a previous musical note so that the time value indicated by a newest musical note increases as long as the sound is regarded as a continuous sound.

5. A musical note display device as claimed in claim 4, wherein said computing means is arranged to finally determine the pattern of said musical note when it is regarded that said input sound is regarded as noncontinuous so that the time value indicated by said musical note represents a time length for which said input sound has been continued with the frequency and level differences thereof being maintained within said predetermined ranges, and to display a next musical note indicating only the sound pitch thereof at a position next to said first-mentioned musical note in response to the change in pitch and/or level of said input sound.

6. A musical note display device as claimed in claim 1, wherein said computing means is arranged to wait given time length while executing one cycle of a program so that said determination of sound pitch is effected with a time delay.

7. A musical note display device as claimed in claim 6, further comprising means for manually changing said time length for selecting a desired tempo.

8. A musical note display device as claimed in claim 1, wherein said computing means is arranged to execute an interrupt service routine at an interval equal to a sampling period of analog-to-digital (AD) conversion for causing said AD converting means to start AD conversion.

9. A musical note display device as claimed in claim 8, wherein said computing means is arranged to wait a given time length while executing one cycle of said interrupt service routine after a predetermined number of AD converted data is obtained so that subsequent AD conversion is effected with a time delay.

10. A musical note display device as claimed in claim 9, further comprising means for manually changing said time length for selecting a desired tempo.

11. A musical note display device as claimed in claim 10, further comprising means responsive to said computing means for emitting rhythm sounds at an interval of said AD conversion.

12. A musical note display device as claimed in claim 11, wherein said means for emitting rhythm sounds comprises a synchronous pulse generator responsive to said computing means, a monostable multivibrator responsive to a pulse signal from said synchronous pulse generator for producing a pulse of a predetermined width, an oscillator for generating an output signal of an audio frequency, and a gate circuit responsive to said pulse from said monostable multivibrator for outputting said output signal from said oscillator.

13. A musical note display device as claimed in claim 10, further comprising means responsive to said computing means for visually indicating a marker which flashes at an interval of said AD conversion.

14. A musical note display device as claimed in claim 13, wherein said marker is a pattern intermittently displayed on said display unit.

15. A musical note display device as claimed in claim 10, wherein said computing means is arranged to produce data indicative of said tempo in terms of a number so that said tempo is displayed on said display unit.

16. A musical note display device as claimed in claim 1, further comprising a graphic equalizer responsive to said input audio signal for changing frequency response prior to analog-to-digital conversion.

17. A musical note display device as claimed in claim 1, further comprising a low pass filter for limiting frequency range of said input audio signal so that a frequency limited signal is fed to said analog-to-digital converting means.

18. A method of detecting pitch and time length of a sound of an input audio signal, comprising the steps of:

(a) converting said input audio signal into digital data;

(b) effecting an FFT operation by using said digital data;

(c) executing a power spectrum calculation by using a result of said FFT operation;

(d) obtaining a fundamental tone to determine the pitch of of said sound of said input audio signal by using spectrum data obtained by said power spectrum calculation, the step of obtaining said fundamental tone including the steps of:

obtaining a frequency value of a frequency component whose level is lowest within a predetermined level range from a highest level and whose frequency is lower than a frequency at which the level is highest; and

obtaining a frequency value at which the level is highest in case no frequency component is detected within said predetermined level range in the above step;

(e) repeating said steps (a) to (d) again so that two frequency data of said fundamental tone, and two level data are obtained for representing the results of two consecutive detections;

(f) determining time length of said sound by using said result of two consecutive detections, the step of determining time length including the steps of:

detecting whether a difference between two frequency data of said results of two consecutive detections is or is not within a predetermined frequency range;

detecting whether a difference between two level data of said results to said two consecutive detections is or is not within a predetermined level range;

detecting whether the level of the latter data of said results of said two consecutive detections is or is not above a predetermined value;

regarding said sound as a continuous sound only when all determinations is said three steps of time length determination are affirmative; and

regarding said sound as a noncontinuous sound if one or more determinations in said three steps is negative.

19. A method as claimed in claim 18, further comprising a step of displaying musical notes in accordance with the pitch and time length of each sound, said step of displaying musical notes comprising the steps of:

(a) selecting a musical note pattern data from a memory in accordance with the pitch and time length of said sound when the time length is finally determined; and

(b) sending said note pattern data via a video display processor to a video RAM so that said note pattern is displayed on a display unit when a subsequent sound is detected.

20. A method as claimed in claim 18, further comprising a step of displaying musical notes in accordance with the pitch and time length of each sound, said step of displaying musical notes comprising the steps of:

(a) selecting musical note pattern data from a memory in accordance with the pitch of said sound, where said note pattern is indicative of only the sound pitch;

(b) sending said note pattern data via a video display processor to a video RAM so that said note pattern is displayed on a display unit;

(c) selecting another musical note pattern indicative of both sound pitch and time value when said sound is detected as a continuous sound;

(d) sending said note pattern data obtained in said step (c) via said video display processor to said video RAM so that said note pattern indicative of both sound pitch and time value is displayed on said display unit in place of said note pattern indicative of only sound pitch;

(e) repeating said steps (b) and (c) as long as said sound is detected as a continuous sound so that said time value becomes longer;

(f) selecting musical note pattern data from said memory in accordance with the pitch of a subsequently determined sound, where said note pattern is indicative of only the sound pitch of said subsequent sound; and

(g) repeating the preceeding steps so that musical notes are displayed in sequence on said display unit.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

This invention relates generally to audio signal processing, and more particularly the present invention relates to a display device which indicates musical notes representing varying pitch of an input audio signal on a screen of a display unit where each note shows time value.

Musical note display devices, which are capable of indicating musical notes on a staff of a music sheet in accordance with input audio signals from a musical instrument, have been desired since such a device is useful for composing or writing music and for music education. Various devices have been made hitherto for indicating musical notes, and a conventional device of this sort is simply arranged to selectively energize lamps on a board on which a staff of musical sheet is indicated, in accordance with electrical signals produced by a keyboard. However, such a conventional display device cannot handle sounds emitted from musical instruments having no keyboard, such as stringed instruments or wind instruments. Therefore, in an other conventional display device, sounds from musical instruments are first converted into an electrical signal, and frequency analysis is effected by a number of band pass filters so as to determine the pitch to be displayed by way of a lamp selected from a plurality of lamps on a staff-like board or a display panel. However, such a conventional musical note display device requires a number of band pass filters, and therefore it suffers from a complex structure.

The inventors of the present invention have invented a musical note display device which is capable of displaying musical notes indicative of only sound pitch, and filed a patent application prior to the present application. The present invention is an improvement of the prior invention, and the apparatus according to the present invention is capable of displaying musical notes indicative not only of sound pitch but also of time value. In the case of sounds from a keyboard, detection or analysis of time value of each musical note to be displayed may be readily effected by measuring time length of a continuous signal produced when a given key of the keyboard is depressed. However, in the case of sounds emitted from various musical instruments or in the case of vocal sounds, determination of time value has hitherto been considered extremely difficult since the frequency and the level of such sounds varies in various manners as time passes.

SUMMARY OF THE INVENTION

The present invention has been developed in order to remove the above-described drawbacks inherent to the conventional musical note display devices.

It is, therefore, an object of the present invention to provide a new and useful musical note display device, which is capable of accurately indicating musical notes on a staff of music sheet displayed on a display unit screen without requiring a complex structure, where each note on the staff represents not only the pitch of an input audio signal but also the time length thereof.

According to a feature of the present invention an input audio signal is AD converted to obtain digital data which are used in Fast Fourier Transform (FFT) operation, and the results of FFT operation are used for power spectrum calculation, and then spectrum data obtained in this way are used to determine a fundamental tone in a particular way so that the pitch of the input audio signal is accurately detected. After the pitch is obtained, it is determined whether the sound is continuous or not. When it is determined that the sound is noncontinuous, the time value of a note representing the sound detected immediately before the detection of noncontinuousness is determined, and is indicated by way of a corresponding note, such as a quarter note, eighth note or the like. In order to indicate a note on a staff, pattern data indicative of a musical note are produced and transmitted via a video display processor to a video RAM, thereby producing a video signal for indicating a staff and musical notes at appropriate position in the displayed staff on a display unit screen.

In accordance with the present invention there is provided a musical note display device for displaying musical notes each indicative of pitch and time length of each sound of an input audio signal on a displayed staff, comprising: analog-to-digital converting means for converting said input audio signal into digital data by using sampling pulses having a sampling frequency; computing means for effecting FFT operation by using said digital data, for executing power spectrum calculation by using result of said FFT operation, for determining a pitch of each sound by using spectrum data obtained by said power spectrum calculation, for determining time value of each sound by measuring time length of each sound, and for determining a pattern to be displayed in accordance with the pitch and time value of each sound; said computing means determining the pitch by obtaining a fundamental tone by obtaining a frequency component whose level is lowest within a predetermined level range from a highest level, and whose frequency is lower than a frequency at which the level is the highest, and determining the pitch, in the case such a frequency component is not detected, by regarding the frequency component, whose level is the highest, as the fundamental tone; said computing means determining the time value by measuring time length for which each sound is regarded as continuous, where each sound is regarded as continuous when frequency difference and level difference between two consecutive detections are both within predetermined ranges, and when the level of said sound is above a predetemined level; and display means including a video display processor, a video RAM and a display unit, said video display processor being controlled by said computing means to store data indicative of said pattern into said video RAM, and said display unit being responsive to a video signal from said video display processor for indicating musical notes displayed at appropriate position on a displayed staff.

In accordance with the present invention there is also provided a method of detecting pitch and time length of a sound of an input audio signal, comprising the steps of: (a) converting said input audio signal into digital data; (b) effecting FFT operation by using said digital data; (c) executing power spectrum calculation by using result of said FFT operation; (d) obtaining a fundamental tone to determine the pitch of said sound of said input audio signal by using spectrum data obtained by said power spectrum calculation, the step of obtaining said fundamental tone having the steps of: obtaining a frequency value of a frequency component whose level is lowest within a predetermined level range from a highest level and whose frequency is lower than a frequency at which the level is highest; and obtaining a frequency value at which the level is highest in the case no frequency component is detected within said predetermined level range in the above step; (e) repeating said steps (a) to (d) again so that two frequency data of said fundamental tone, and two level data are obtained for representing the results of two consecutive detections; determining time length of said sound by using said result of two consecutive detections, the step of determining time length having the steps of: detecting whether the difference between two frequency data of said results of two consecutive detections is or is not within a predetermined frequency range; detecting whether the difference between two level data of said results of said two consecutive detections is or is not within a predetermined level range; detecting whether the level of the latter data of said results of said two consecutive detections is or is not above a predetemined value regarding said sound are a continuous sound only when all determinations in said three steps of time length determination have resulted in YES; and regarding said sound as a noncontinuous sound if one or more determinations in said three steps has resulted in NO.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and features of the present invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings in which:

FIG. 1A is a schematic block diagram of a first embodiment of the musical note display device according to the present invention;

FIG. 1B is a diagram showing a microcomputer used as the control unit of FIG. 1A;

FIGS. 2A and 2B are flow charts showing the operation of the central processing unit used in the embodiment of FIG. 1A;

FIGS. 3A to 3P are diagrams showing various musical note patterns to be displayed in the first embodiment device;

FIG. 4 is an explanatory diagram showing level of an input audio signal whose pitch and time length are to be indicated by way of the musical note patterns of FIGS. 3A to 3I;

FIG. 5 is a diagram showing an example of a music sheet displayed on a screen of the display unit of FIG. 1A;

FIG. 6 is an example of a memory map of a video RAM used in the device according to the present invention;

FIG. 7 is an explanatory diagram of sections on a display unit screen of the musical note display device of FIG. 1A;

FIGS. 8A and 8B are flow charts showing the operation of the central processing unit used in a second embodiment of the invention;

FIG. 9 is a diagram showing the addresses of the RAM used in the device according to the present invention;

FIGS. 10A through 10R are diagrams showing various musical note patterns to be displayed by the second embodiment device;

FIG. 11 is an explanatory diagram showing level of an input audio signal whose pitch and time length are to be indicated by way of the musical note patterns of FIGS. 10A to 10R;

FIG. 12 is a diagram showing an example of a music sheet displayed on a screen of the display unit of the second embodiment device;

FIG. 13 is an explanatory diagram showing how an initially displayed musical note changes its pattern for indicating longer time value in the second embodiment device;

FIG. 14 is a schematic block diagram of a third embodiment of the musical note display device according to the present invention;

FIG. 15 is a flow chart showing the operation of the central processing unit used in the third embodiment of FIG. 14;

FIGS. 16A through 16I are diagrams showing various musical note patterns to be displayed in the third embodiment device;

FIG. 17 is an explanatory diagram showing level of an input audio signal whose pitch and time length are to be indicated by way of the musical note patterns of FIGS. 16A through 16I;

FIG. 18 is a diagram showing an example of a music sheet displayed on a screen of the display unit of FIG. 14;

FIG. 19 is an explanatory diagram showing how an initially displayed musical note changes its pattern for indicating longer time value in the third embodiment device;

FIGS. 20A and 20B are diagrams showing the change in time value due to the change in tempo;

FIG. 21 is a schematic block diagram of a fourth embodiment of the musical note display device according to the present invention;

FIGS. 22A and 22B are flow charts showing the operation of the central processing unit used in the fourth embodiment of FIG. 21;

FIGS. 23A and 23B are time charts showing operations by the microcomputer used in the fourth embodiment device; and

FIG. 24 is a diagram showing an example of a music sheet displayed on a screen of the display unit of FIG. 21;

The same or corresponding elements and parts are designated at like reference numerals throughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1A a schematic block diagram of a first embodiment of the present invention is shown. An input audio signal applied from a sound source to an input terminal 1 is then fed to a graphic equalizer 2 in which frequency response of the input audio signal is changed so that frequency analysis will be readily made. Then an output signal from the graphic equalizer 2 is fed to an anti-aliasing filter 3 for removing unnecessary high frequency components threfrom so that aliasing noises would not occur on analog-to-digital (AD) conversion effected by an AD converter 4 to which an output signal from the anti-aliasing noise filter 3 is applied. The anti-aliasing filter 3 comprises a low pass filter for limiting the frequency range of the input audio signal so that frequency limited signal is fed to the AD converter 4. A control unit 5, which may be a microcomputer as will be described hereinlater, is responsive to digital output data from the AD converter 4 for processing the digital data representing each audio signal thereby determining the pitch as well as time value or time length of each sound. The AD converter 4 is controlled by a control signal generated by the control unit 5 where the sampling period of AD conversion is determined by the control signal.

The control unit 5 may comprise a microcomputer as shown in FIG. 1B, and is shown by various blocks in FIG. 1A for the description of the function thereof. The microcomputer used as the control unit 5 of FIG. 1A comprises a central processing unit CPU 80, a read-only memory (ROM) 82, a random-access memory (RAM) 7, and an input-output device (I/O) 84 in the same manner as well known.

The circuit arrangement of FIG. 1A also comprises a video display processor (VDP) 12, a video RAM (V.RAM) 13, and a display unit 14, such as a CRT. The VDP 12 is responsive to data from the control unit 5 for temporarily storing the same in the V.RAM 13, so that various patterns are displayed by the CRT 14 for indicating one or more staffs and musical notes. In addition, as will be described in connection with other embodiments, other information such as information indicative of tempo and rhythm may also be displayed on the screen of the CRT 14.

FIGS. 2A and FIG. 2B are flow charts showing the operation of the microcomputer of FIG. 1B. The flow chart of FIG. 2A shows a main routine, while the other flow chart of FIG. 2B shows an interrupt service routine. In a first step 100 of the main routine, system initialization is effected. A program interruption is arranged to occur at an interval equal to a sampling period at which sampling of the input analog signal from the anti-aliasing noise filter 3 is effected by the AD converter 4. To this end an internal counter of the microcomputer is used so that program interruption periodically occurs, and when an interruption occurs, operation of the main routine is interrupted so that the interrupt service routine of FIG. 2B is executed for effecting AD conversion. In the interrupt service routine, a conversion-commanding and digital signal outputting portion 6 of the control unit 5 produces a conversion-command signal which is fed to the AD converter 4 for causing the same to start AD conversion. The AD converter 4 starts converting the input analog signal into a digital signal in response to the conversion-command signal in a step 200 of the interrupt service routine, and a digital data word obtained from one sample is fed via the portion 6 to the RAM 7 to be stored therein. Therefore, a predetermined number of AD converted digital data words, such as 256 data words, are stored in the RAM 7 when the interrupt service routine has been executed the predetermined number of times. In a following step 202, it is determined whether the number of times of AD conversion has or has not reached the predetermined number. This is done by watching the count of another internal counter to which the predetermined number is preset. If NO, the operational flow goes to a RETURN step 206. On the other hand, if YES, the above-mentioned internal counter for indicating the number of AD converted data is stopped and presetting of the predetermined number is effected in a step 204, and then the operational flow goes to the RETURN step 206.

In this way the predetermined number of digital data words are stored in the RAM 7, and these digital data words are processed to determine the pitch by way of a calculation and sound pitch analyzing portion 8 of the control unit 5. In detail, the digital data words are used for effecting Fast Fourier Transform (FFT) operation in a step 102 of the main routine. The result of FFT operation is stored in the RAM 7, and then power spectrum calculation is effected in a step 104 so that the result thereof is also stored in the RAM 7. Then a maximum spectrum value is obtained, and then a frequency at which the maximum spectrum value is shown within the spectrum is obtained. However, this frequency cannot be simply determined as representing the fundamental tone. Therefore, the fundamental tone is determined by obtaining a frequency component whose level is lowest within a predetermined level from a highest level, i.e. the maximum spectrum value, and whose frequency is lower than the frequency at which the level is the highest. If such a frequency does not exist, the frequency component, whose level is the highest, is regarded as the fundamental tone. In this way the pitch of the input sound is determined and data indicative of the sound pitch or tone is stored in the RAM 7. The above-described determination of a sound pitch is executed in a step 106.

The above-described technique for determining sound pitch was invented by the present inventors prior to the present invention, and was described in the prior application as previously described. Since the pitch of the present invention relates to determination and display of time length of each sound rather than determination and display of each sound, the following description will be made in this connection mainly.

FIGS. 3A to 3P show various musical note patterns which will be displayed on a staff also displayed on the screen of the CRT 14 as shown in FIG. 5. A time length required for the execution of the steps 102, 104 and 106 of FIG. 2A is set to be one half a time period corresponding to an eighth note (quaver) shown in FIG. 3A.

FIG. 4 shows an example of a level variation of an input audio signal with respect to time. In FIG. 4, it is assumed that a sound having a time value equal to a quarter note is first received, and then another sound having a time value equal to an eighth note is received. The references t1, t2 . . . t8 are for indicating time length corresponding to one half the eighth note. Since the steps 102 to 106 are executed within a period of time equal to one half the eighth note, the sound pitch of the first sound is analyzed within a time period t1.

Let us assume that music sounds, each of which attenuates as time passes like the sound from the piano, are received as shown in FIG. 5. When a first sound of pitch name C and having a time value of quarter note is received, after the sound pitch analysis by the steps 102 to 106, other steps 108, 110 and 112, which are substantially the same as the steps 102, 104 and 106, are executed immediately thereafter. Thus, these steps 108 to 112 are executed within a time interval indicated at t2 in FIG. 4. Then the number of times of the sound pitch analysis by the step 112 is counted. To this end a step 114 is executed in which a count of a counter, which may be actualized by the software of the microcomputer, is increased by one. Then in a next step 116, it is determined whether the sound is a continous sound or not. This is performed by a continuous sound detecting portion 9 of the control unit 5. In order to determine whether the sound is continuous or not, comparison between two consecutive results of sound pitch analysis is performed. In this comparison, it is determined whether the sound pitch of a previous result equals that of a subsequent result, and whether the difference between the levels obtained from these two consecutive analyses is within a predetermined level range. Furthermore, it is detected whether the level of the sound just analyzed is or is not above a predetermined threshold L (see FIG. 4). In the above, in order to check whether the sound pitch just detected equals the former sound pitch, the frequency of the fundamental tone is checked such that the frequency difference between two consecutive analyses is within a predetermined frequency range. Furthermore, the level of the input sound is detected by obtaining a sum of levels at respective frequencies within the detected spectrum, which have been obtained by the above-mentioned power spectrum operation.

In the illustrated embodiment, a shortest musical note to be displayed is a quarter note, and frequency or pitch analysis is effected within a time period equal to one half the time value of the shortest musical note so that sound pitch analysis is effected at an interval corresponding to one half the shortest note. Therefore, even if a continuous input sound slightly varies in connection with its frequency or level as time passes, it can be determined if the variation is within a predetermined frequency range or predetermined level range so that the continuousness and sound pitch of the input sound can be accurately detected.

Assuming that a continuous sound having a time length equal to a quarter note is received as shown in FIG. 4, this sound is detected as a continuous sound by the continuous sound detecting portion 9, and then an analysis number detection and pattern data detection portion 10 determines whether the count has reached 16, which is or is not a maximum count, (see step 118 of FIG. 2A). When the time t2 has elapsed, since the count is only 1, the step 108 is again executed for performing FFT operation. Then steps 110 and 112 are executed to determine the pitch, and then the count is increased by one in the step 114.

The above operations of the steps 108 to 114 are repeatedly executed as long as the sound is determined as a continuous sound by the step 116. When time t4 has elapsed, where the count is now 3, let us assume a subsequent sound of pitch name E, whose time length equals that of an eighth note as shown in FIG. 5, is inputted. Then the steps 108 to 112 are executed to determine the sound pitch, and then the count of the counter is increased by one to be 4.

In a following step 116, the sound is detected as a noncontinuous sound since the sound pitch and the level thereof differ from those of the previous sound, i.e. the sound of pitch name C of a quarter note. As a result, the determination in the step 116 becomes NO, and then musical note pattern data is produced in a step 120. This is effected by the analysis number detection and pattern data detection portion 10 of the control unit 5, and pattern data designating instruction is derived therefrom to be supplied to a pattern data determining portion 11. This operation is actually done by designating a selected address of the ROM 82 of the microcomputer for reading out a predetermined pattern data.

FIGS. 3A to 3P respectively show the relationship between the count and the sort of musical notes whose pattern data are prestored in the ROM 82. In detail, data indicative of various musical notes including from eighth note to whole note are stored in correspondence with the count whose value is from 1 to 16. In the above example, since the count is 4, pattern data corresponding to a quarter note is selected (see FIG. 3D). Furthermore, since the pitch of the sound has been determined as pitch name C, the pattern data is selected so that a head of the note indicates pitch name C in the staff as shown in FIG. 5. The pattern data from the pattern data determining portion 11 is fed via the VDP 12 to the V.RAM 13 so as to be written in a predetermined table thereof. A horizontal position of a note to be displayed is determined by a count of a counter, which may be actualized by the program of the microcomputer, so that sequential notes are displayed at predetermined horizontal positions at an interval or space between two consecutive notes. In the illustrated embodiment, the number of musical notes to be displayed equals 26, and therefore, after the staff is filled with 26 notes, all the notes previously shown may be cleared to provide an empty staff so that following notes can be continuously displayed from the left end of the staff. If it is desired, however, the twenty-seventh note may be displayed at the right end with the 26 notes being shifted to the left such that the oldest note at the left end is cancelled each time a new note is added to the right end.

The VDP 12 functions as an interface between the V.RAM 13 connected thereto via a data bus 94, and the CPU 80, and is constructed such that it is capable of determining the contents of pictures to be displayed by using various data stored in the above-mentioned V.RAM 13, and of generating a composite video signal of a predetermined standard system. As this VDP 12, for instance, may be used a video display processor of Texas Instruments, Inc., of the United States, introduced in ELECTRONICS, Nov. 20, 1980 (pages 123-126) or an integral composite video generator disclosed in U.S. Pat. No. 4,262,302 issued to Texas Instruments and known as TI's TMS9918, and it is assumed that the above-mentioned video display processor is used in the following description.

In FIG. 1B, although no address-decoder is shown, in actual structure an address-decoder responsive to address data from the CPU 80 is provided so as to respectively designate the addresses of the RAM 7 and ROM 82. The CPU 80 is preferably of high-speed and capable of commanding signed multiplication, which is a basic calculation for FFT. As the CPU 80 may be used an integrated circuit TMS9995 manufactured by Texas Instruments.

FIG. 6 is a drawing showing an example of a memory map of the V.RAM 13 connected via the bus 94 to the VDP 12. In the memory map of the V.RAM 13 of FIG. 6, 1024 bytes from address 0 to address 1023 are used as a sprite generator table (SPG); 768 bytes from address 1024 to address 1791 being used as a pattern name table (PNT); 128 bytes from address 1792 to address 1919 being used as a sprite attribute table (SAT); 32 bytes from address 1920 to address 1951 being used as a color table (CT); and 96 bytes from address 1952 to address 2047 being unused yet; and 2048 bytes from address 2048 to address 4095 being used as a pattern generator table (PGT).

The pattern generator table PGT is capable of storing a specific pattern of 8 pixels by 8 pixels by using 8 bytes respectively for instance, and therefore 256 patterns of 8 by 8 pixels can be stored. The pattern information stored in the pattern generator table PGT is transmitted from the ROM 82 at an initial state of the device by the operation of the CPU 80. However, the pattern generator table PGT may of course be a read-only memory.

In the storing region including 8-byte portions of the pattern generator table PGT specific patterns of 8 by 8 pixels are respectively stored, and respective specific patterns can be designated by pattern names assigned to respective storing regions in which the specific patterns are respectively stored. In the case of the pattern generator table PGT of FIG. 6, 256 patterns can be designated by way of 256 pattern names from pattern name #0 through pattern name 255.

Nextly, the pattern name table PNT comprises a storing capacity corresponding to a total number of displaying sections imagined on the screen of the display unit CRT so as to store information indicating which section is of which pattern name of the pattern generator table PGT.

In an example of FIG. 7, the total number of sections set in the display unit screen is [32 columns.times.24 rows]=768, and since 1 byte is used as the amount of informtion for indicating 1 section, the pattern name table PNT has a storing capacity of 768 bytes as mentioned in the above.

In the case that a necessary number of patterns are stored in the pattern generator table PGT of the V.RAM 13, and that necessary pattern names assigned in correspondence with respective patterns are stored in the respective sections of the display unit screen of the pattern name table PNT, the VDP 12 produces a composite video signal complying with a specific standard system where the contents of the picture are determined by information stored in the pattern name table PNT of the V.RAM 13, information stored in the pattern generator table PGT, and information stored in the color table CT when necessary, and the produced composite video signal being fed to the CRT 14 for displaying a specific pattern on the screen of the CRT 14.

The above description is related to a case of displaying under a display mode in which a specific one of patterns stored in the pattern generator table PGT is displayed at a specific section among 768 sections, namely, so called graphic mode. When displaying a pattern with such a graphic mode, the position of the pattern is designated by the pattern name table PNT, and therefore, when it is intended to move a pattern on the display unit screen, the pitch of pattern movement on the display unit screen is 1 section (distance of 8 pixels).

In order to cause the pattern to move smoothly with the pitch of pattern movement on the display unit screen being made small, the pattern stored in the sprite generator table SGT is moved on the display unit screen at a pitch of 1 pixel with a change in co-ordinates.

The pattern to be stored in the sprite generator table SGT is sprite data which may be of either 8 pixels by 8 pixels or 16 pixels by 16 pixels. Respective patterns stored in the sprite generator table SGT are given sprite names separately as #0, #1 . . . #N, a sprite surface corresponding to a pattern with respective sprite names are arranged so that smaller numerical values indicated by the sprite names have higher priority.

In the memory map of the V.RAM 13 shown in FIG. 6, since 1024 bytes from address 0 to address 1023 are used as the sprite generator table SGT as described in the above, 128 patterns (sprite name #0 through #127) can be stored in the case of 8 pixels by 8 pixels in this case, and also 32 patterns (sprite name #0 through #31) can be stored in the case of 16 pixels by 16 pixels. In the case that 2048 bytes are assigned to the sprite generator table SGT of the V.RAM 13, it is a matter of course that the number of patterns which can be stored in the sprite generator table SGT is twice as much as the above example.

Since sprite position (1 byte for designating each of vertical position and horizontal position), name of display sprite (1 byte), color code and display sprite termination code (1 byte) and the like are set in the sprite attribute table SAT by using 4 bytes for each one sprite, in the case that 128 bytes are used as the sprite attribute table SAT, information of 32 sprites is stored in the sprite attribute table SAT.

The position of a sprite is determined with a vertical position (a numerical value indicating the vertical order of picture point) and a horizontal position (a numerical value indicating the horizontal order of pictue point) being written in the sprite attribute table SAT, where a co-ordinate of 49,152 picture points determined by 256 picture points (8 pixels by 32 sections) of horizontal direction (X direction) and 192 picture points (8 pixels by 24 sections) of vertical direction (Y direction) is provided wherein an origin of the sprite is set to the left top end, and the movement of the sprite is effected with a pitch of 1 pixel.

In the musical note display device for audio signals according to the present invention, musical notes of an audio signal are displayed on the screen of the CRT 14 by way of a staff, for instance as shown in FIG. 5 by an arrangement such that the selection of a pattern to be displayed on the screen of the CRT 14 and the designation of the way of movement of the pattern are effected by data written in the pattern name table PNT and the sprite attribute table SAT wit