Abstract:
An automatic player piano prolongs acoustic sounds in playback as if a player pushes down a sostenuto pedal, and a controller is responsive to a first piece of music data information representative of key-on state, a second piece of music data information representative of key-off state, a third piece of music data information representative of pedal-on state and a fourth piece of music data information representative of pedal-off state so as to play a tune by using key actuators associated with the keys; when the first piece of music data information is supplied to the controller for a key, the controller instructs the key actuators to change associated the key from the key-off state to the key-on state; when the second piece of music data information is supplied to the controller without the third piece of music data information for a key, the controller instructs the key actuator to change the key from the key-on state to the key-off state; when the second piece of music data information is supplied to the controller in the presence of the third piece of music data information for a key, the controller instructs the key actuator to maintain the key in the key-on state; when the fourth piece of music data information is supplied to the controller after receipt of the second piece of music data information, the controller instructs the key actuator to change the key from the key-on state to the key-off state.

Description:
FIELD OF THE INVENTION 
     This invention relates to an automatic player piano and, more particularly, to an automatic player piano exactly reproducing an acoustic sound produced under manipulation of a sostenuto pedal. 
     DESCRIPTION OF THE RELATED ART 
     An automatic player piano is a compromise between an acoustic piano and an electric playing system, and either pianist or electric playing system plays a tune on the keyboard. The series of acoustic sounds produced through the fingering of the pianist is hereinbelow referred to as &#34;original performance&#34;, and a series of acoustic sounds produced by the electric playing system is referred to as &#34;playback&#34;. A key of the keyboard stays in a &#34;rest position&#34; due to the self-weight, and causes an associated hammer to be in a &#34;home position&#34;. On the other hand, when force is exerted on the key, the key is moved from the rest position toward an &#34;end position&#34;, and an associated key action mechanism rotates the hammer toward a set of strings. In the following description, term &#34;forward&#34; means a direction from the rest position or the home position toward the end position or the set of strings, and term &#34;backward&#34; indicates the direction opposite to the forward direction. 
     When the pianist depresses a key from the rest position toward the end position, the depressed key spaces the damper head from the set of strings, and the associated key action mechanism drives the hammer for rotation. The hammer strikes the set of strings, and the strings vibrate for producing the acoustic sound. When the pianist releases the depressed key, the key returns toward the rest position, and allows the damper head to be held in contact with the set of strings, again. The damper head takes up the vibrations of the strings, and extinguishes the acoustic sound. Thus, the acoustic piano repeats the key depressing, the striking at the strings, the releasing the key and the absorption of vibrations during the original performance. If the automatic player piano is instructed to record the original performance, a recording system, which is usually further incorporated therein, produces pieces of music data information representative of the original performance, and stores them in a suitable information storage medium. 
     When the automatic player piano is instructed to reproduce the original performance, the electric playing system reads out the pieces of music data information, and sequentially energizes solenoid-operated key actuators so as to move the keys for the playback. 
     The acoustic piano is equipped with a pedal system, and two or three pedals are incorporated in the pedal system. One of the pedals is called as a &#34;sostenuto pedal&#34;, which enables selected notes to be sustained independently of others. In detail, the sostenuto pedal is linked through a sostenuto pedal with the dampers. Assuming now that the player steps on the sostenuto pedal after depressing some keys, even if the player releases the depressed keys, the associated dampers are hold off, and the acoustic sounds are prolonged. Upon releasing the sostenuto pedal, the dampers are brought into contact with the strings, and extinguish the acoustic sounds. Thus, the sostenuto pedal allows the pianist to arbitrarily determine the timing to extinguish the sounds. 
     If the acoustic piano of the automatic player piano is equipped with the sostenuto pedal, the electric playing system is expected to reproduce the prolonged acoustic sounds produced under the manipulation of the sostenuto pedal. As described hereinbefore, the electric playing system reproduces the original performance on the basis of the pieces of music data information. The pieces of music data information represent forward key/hammer motions and a backward key motion. A final hammer velocity and an impact time describe the forward key/hammer motions, and a key releasing time and a backward key velocity describe the backward key motion. The key releasing time is defined by time when the released key passes a predetermined point on the trajectory of the key between the rest position and the end position, and the damper is brought into contact with the set of strings at the key releasing time. 
     The prior art automatic player piano reproduces the acoustic sound prolonged by depressing the sostenuto pedal without manipulation of the sostenuto pedal during the playback. Assuming now that a pianist releases the sostenuto pedal after releasing some keys, the recording system does not give the key releasing time to the released key at passing the predetermined position. When the pianist releases the sostenuto pedal, the recording system determines the pedal releasing time to be the key releasing time for the keys, and produces the pieces of music data information representative of the backward key motions. For this reason, when the electric playing system reproduces the original performance, the solenoid-operated key actuators allow those keys to return toward the rest position at the key releasing time equal to pedal releasing time. Thus, the prior art automatic player piano prolongs the acoustic sounds without manipulation of the sostenuto pedal in the playback. 
     However, a professional pianist uses the sostenuto pedal in more complicated manner. For example, if a pianist depresses a released key under the manipulation of the sostenuto pedal, the pianist can vary the resonance of the acoustic sound. If the recording system simply determines the pedal releasing time to be the key releasing time, the prior art automatic player piano does not reproduce the variation of resonance, and can not nuance the reproduced performance. 
     Another problem is poor data compatibility. The pieces of music data information are not available for another kind of automatic player piano, the electric playing system of which has a solenoid-operated pedal actuator for moving the sostenuto pedal. Although the automatic player piano equipped with the solenoid-operated pedal actuator has not been developed as a commercial product, the pieces of music data information for the solenoid-operated key actuators are not available for the automatic player piano equipped with the solenoid-operated pedal actuator. 
     SUMMARY OF THE INVENTION 
     It is therefore an important object of the present invention to provide an automatic player piano, which can express the delicate nuance during the playback. 
     It is also an important object of the present invention to provide an automatic player piano, which is improved in data compatibility. 
     In accordance with one aspect of the present invention, there is provided an automatic player piano comprising an acoustic piano including a plurality of each changed between key-on state and key-off state, a plurality of sets of strings respectively associated with the plurality of keys for producing acoustic sounds through vibrations thereof, a plurality of hammers respectively driven for rotation by the plurality of keys so as to strike the plurality of sets of strings, a plurality of damper mechanisms respectively linked with the plurality of keys so as to be spaced from the plurality of sets of strings during the key-on state and a sostenuto pedal changed between pedal-on state and pedal-off state by a player and selectively causing the plurality of damper mechanisms to be continuously spaced for prolonging the acoustic sounds and an electric playing system including a plurality of key actuators respectively associated with the plurality of keys so as to selectively change the plurality of keys between the key-on state and the key-off state without fingering of the player, a controlling means responsive to a first piece of music data information representative of the key-on state, a second piece of music data information representative of the key-off state, a third piece of music data information representative of the pedal-on state and a fourth piece of music data information representative of the pedal-off state so as to play a tune by means of the plurality of key actuators, and the controlling means gives instructions as follows: The controlling means supplies a first instruction to one of the plurality of key actuators so as to change associated one of the plurality of keys from the key-off state to the key-on state when the first piece of music data information is supplied thereto for the aforesaid one of the plurality of keys. The controlling means supplies a second instruction to the aforesaid one of the plurality of key actuators so as to change the aforesaid associated one of the plurality of keys from the key-on state to the key-off state when the second piece of music data information is supplied thereto without the third piece of music data information for the aforesaid one of the plurality of keys. The controlling means supplies a third instruction to the aforesaid one of the plurality of key actuators so as to maintain the associated one of the plurality of keys in the key-on state when the second piece of music data information is supplied thereto in the presence of the third piece of music data information for the aforesaid one of the plurality of keys. The controlling means supplies a fourth instruction to the aforesaid one of the plurality of key actuators so as to change the associated one of the plurality of keys from the key-on state to the key-off state when the fourth piece of music data information is supplied thereto after receipt of the second piece of music data information. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the automatic player piano will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which: 
     FIGS. 1A and 1B are partially cut-away side views showing the structure of an automatic player piano according to the present invention; 
     FIG. 2 is a block diagram showing functions of a preliminary treatment unit incorporated in the automatic player piano; 
     FIG. 3 is a view showing a note flag associated with a sostenuto flag; and 
     FIG. 4 is a flow chart showing the behavior of the preliminary treatment unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Structure of Automatic Player Piano 
     Referring to FIGS. 1A and 1B, an automatic player piano embodying the present invention largely comprises an acoustic piano 1, a recording system 2 and an electric playing system 3. In the following description, word &#34;front&#34; means a position closer to a pianist than a &#34;rear&#34; position. 
     The acoustic piano comprises a keyboard 1a, a plurality of key action mechanisms 1b, a plurality of damper mechanisms 1c, a plurality of hammer assemblies 1d and a plurality of sets of strings 1e. A plurality of keys 1f form the keyboard 1a, and notes of a scale are respectively assigned to the plurality of keys 1f. Each of the keys 1f is turnable between the rest position and the end position with respect to a balance key pin 1g, and stays at the rest position without force exerted on the front portion thereof. 
     The key action mechanisms 1b are provided between the plurality of keys 1f and the associated hammer assemblies 1d, respectively, and the key action mechanisms 1b are actuated by the keys 1f so as to drive the associated hammer assemblies 1d for rotation. The function of the key action mechanism 1b is well known to a person skilled in the art, and no further description is incorporated hereinbelow. 
     The damper mechanism 1c includes a damper head 1h connected through a damper wire 1j to a damper lever 1k, and the rear end portion 1m of the key 1f lifts the damper lever 1k during the forward key motion. On the other hand, while the key 1f is returning toward the rest position, the rear end portion 1m allows the damper head 1h to go down due to the self-weight thereof, and the damper head 1h is brought into contact with the set of strings 1e, again. 
     The acoustic piano further comprises a pedal system 1n for imparting effects to acoustic sounds. A sostenuto pedal 1o and a link mechanism 1p are incorporated in the pedal system 1n, and the link mechanism 1p is connected between the sostenuto pedal 1o and the damper mechanisms 1c. The sostenuto pedal 1o is pressed down by a pianist during an original performance, and the link mechanism 1p holds the damper heads 1c already spaced from the strings 1e off. Thus, the sostenuto pedal 1o prolongs the vibrations of the strings 1e by holding the damper heads 1h off. When the pianist releases the sostenuto pedal 1o, the link mechanism 1p allows the damper mechanisms 1c to bring the damper heads 1h into contact with the strings 1e, again, and the damper heads 1h take up the vibrations of the strings 1e. 
     The recording system 2 includes a plurality of key sensors 2a respectively associated with the keys 1f, a pedal sensor 2b associated with the sostenuto pedal 1o, a plurality of hammer sensors 2c respectively associated with the hammer assemblies 1d, a recording unit 2d connected to the sensors 2a/2b/2c for producing pieces of music data information representative of an original performance and a post treatment unit 2e connected to the recording unit 2d. 
     The key sensor 2a is implemented by a combination of shutter plate 2f and photo-interrupters 2g/2h, and supplies a two-bit key position signal KP to the recording unit 2d. The shutter plate 2f is attached to the lower surface of the associated key 1f, and is movable with respect to the key bed 1q. The photo-interrupters 2g/2h are spaced along the trajectory of the shutter plate 2f, and are stationary with respect to a key bed 1q where the keyboard 1a is mounted. The photo-interrupters 2k/2m radiate optical beams across the trajectory of the shutter plate 2f. The shutter plate 2f successively interrupts the optical beams during the forward key motion, and allows the optical beams to pass the trajectory during the backward key motion. Thus, the key sensor 2a changes the two-bit key position signal KP depending upon the current key position on the trajectory. 
     The hammer sensor 2c includes a shutter plate 2j attached to the hammer shank 1r of the associated hammer assembly 1d and photo-interrupters 2k/2m stationary with respect to the key bed 1q, and the photo-interrupters 2k and 2m are spaced along the trajectory of the shutter plate 2j. The hammer sensor 2c supplies a two-bit hammer position signal HP to the recording unit 2d. When the hammer assembly 1d is driven for rotation, the shutter plate 2j sequentially interrupts the optical beams of the photo-interrupters 2k/2m during the forward hammer motion. On the other hand, after rebounding on the strings 1e, the shutter plate 2j allows the photo-interrupters 2k/2m to successively bridge the optical beams between the photo-emitting elements and the photo-detecting elements. Thus, the hammer sensor 2c changes the two-bit hammer position signal HP depending upon the current hammer position. 
     The pedal sensor 2b is inserted between suitable link members of the link mechanism 1p, and supplies a pedal status signal PP to the recording unit 2d. In this instance, the pedal sensor 2b simply indicates depressed state (pedal-on state) or released state (pedal-off state), and is implemented by an electric switch provided at an intermediate position on the pedal trajectory. The pedal sensor may produce a multi-bit pedal position signal representative of a current pedal position. 
     The recording unit 2d periodically checks the key position signals KP, the hammer position signals HP and the pedal position signal PP to see whether or not a pianist moves the keys 1f and the sostenuto pedal 1o. When the pianist moves a key 1f, the key 1f is downwardly moved along the key trajectory, and the key action mechanism 1b drives the hammer assembly 1d for rotation. For this reason, the shutter plate 2f attached to the key 1f changes the bit pattern of the key position signal KP depending upon the current key position along the key trajectory, and the shutter plate 2j attached to the hammer assembly 1d changes the bit pattern of the hammer position signal HP depending upon the current hammer position on the forward hammer trajectory. 
     The recording unit 2d calculates the forward key velocity on the basis of the lapse of time between the interruption of the photo-interrupter 2g and the interruption of the photo-interrupter 2h, and determines a key depressing time at the interruption of the photon-interrupter 2h. The key depressing time is representative of occurrence of a key-on event. The recording unit 2d further calculates the forward hammer velocity on the basis of the lapse of time between the interruption of the photo-interrupter 2m and the interruption of the photo-interrupter 2k, and determines an impact time to be the interruption at the photo-interrupter 2m. The impact time is representative of occurrence of a hammer event. 
     On the other hand, when the pianist releases the depressed key 1f, the key 1f returns toward the rest position, and the key sensor 2a changes the bit pattern of the key position signal KP depending upon the current key position on the backward key trajectory. The recording unit 2d calculates a released key velocity on the basis of the lapse of time between the photo-interrupters 2h and 2g, and determines a key releasing time to be the interruption of the photo-interrupter 2g. The key releasing time is representative of occurrence of a key-off event. 
     If the pianist depresses the sostenuto pedal 1o during the original performance, the pedal sensor 2b changes the pedal status signal PP from the released state to the depressed state, and supplies the pedal status signal PP representative of the depressed state to the recording unit 2d. In this way, the key sensors 2a, the hammer sensors 2c and the pedal sensor 2b inform the recording unit 2d of the current key positions, the current hammer positions and the current pedal status during the original performance, and the recording unit 2d produces pieces of music data information representative of hammer motions, key motions and pedal status. The recording unit 2d supplies the pieces of music data information to the post treatment unit 2e. 
     The post treatment unit 2e normalizes the hammer motions, the key motions and the pedal status, and formats the normalized music data information into a music data code. In detail, a commercial product of the automatic player piano has individualities due to differences in sensor position, margins of the component parts and dimensions after the assemblage, and the individualities affect the key motions, the hammer motions and the pedal status. If a product of the automatic player piano is requested to reproduce an original performance on the basis of the pieces of music data information produced by another product, the reproduced performance is possibly different from the original performance due to the individualities. In order to eliminate influences of the individualities from the pieces of music data information, the post treatment unit 2e converts the pieces of music data information to pieces of music data information produced by an ideal automatic player piano, and the data conversion is called as &#34;normalization&#34;. 
     After the normalization, the post treatment unit 2e formats impact data GD such as the final hammer velocity and the impact time, released key data RD such as the released key velocity and the key releasing time, sostenuto data SD representative of the current pedal status and interval data TD representative of lapse of time between the events into music data codes ED. An identifier is added to the music data code ED so as to indicate the kind of data GD/RD/SD/TD. Thus, the recording system 2 produces the sostenuto data SD independently of the released key data RD. If an automatic player piano is equipped with a solenoid-operated pedal actuator, the electric playing system 3 controls the solenoid-operated pedal actuator in response to the sostenuto data SD so as to move the sostenuto pedal at appropriate timings. 
     The music data codes ED are supplied from the post treatment unit 2e to another electronic musical instrument or a suitable information storage medium such as, for example, a hard disk or a floppy disk. 
     The electric playing system 3 includes a preliminary treatment unit 3a, a motion controller 3b, a servo-controller 3c and solenoid-operated key actuators 3d. The solenoid-operated key actuators 3d are provided under the rear positions 1m of the keys 1f, respectively, and have respective plungers 3e projectable from respective solenoids 3f. Driving signals DR energize the solenoids 3f, and the electromagnetic force is exerted on the associated plungers 3e. As a result, the plungers 3e project from the solenoids 3f, and push the rear end portions 1m of the associated keys 1f. Though not shown in the drawings, built-in plunger sensors are respectively incorporated in the solenoid-operated key actuators 3d, and supply plunger position signals representative of current plunger positions to the servo-controller 3c. 
     The music data codes ED are supplied to the preliminary treatment unit 3a, and the preliminary treatment unit 3a determines a forward key trajectory for each key 1f to be depressed and a backward key trajectory for each key 1f to be released on the basis of the music data codes ED. The forward/backward key trajectories are represented by a series of positional data or a target position varied with time (t, X). If the music data codes ED are stored in an information storage medium, the preliminary treatment unit 3a in the order of events identified by the interval data TD. In this instance, any pedal actuator is not provided for the sostenuto pedal 1o, and the preliminary treatment unit 3a is responsive to the sostenuto data SD so as to modify the backward key trajectories for the keys released during the manipulation of the sostenuto pedal 1o. The key if on the modified backward trajectory prevents the vibrating strings 1e from the absorption with the damper head 1h during the pedal-on state. 
     The preliminary treatment unit 3a supplies the series of positional data (t, X) to the motion controller 3b, and the motion controller 3b produces a series of target plunger positions (X) from the series of positional data (t, X). The motion controller 3b supplies the series of target plunger positions (X) to the servo-controller 3c, and the servo-controller 3c regulates the magnitude of the driving signal DR in such a manner as to match the current plunger position with the target plunger position. 
     Preliminary Treatment Unit 
     FIG. 2 illustrates function blocks of the preliminary treatment unit 3a. The preliminary treatment unit 3a is functionally broken down into a keyboard data processing section 3aa, a sostenuto data processing section 3ab, a key status data table 3ac and a controlling section 3ad. The key status data table 3ac is illustrated in FIG. 3. Key numbers are respectively assigned to the keys 1f forming the keyboard 1a, and a note flag and a sostenuto flag are given to each of the key numbers. The sostenuto flag of &#34;0&#34; and the sostenuto flag of &#34;1&#34; are indicative of the pedal-off state and the pedal-on state, respectively, and the note flag of &#34;0&#34; and the note flag of &#34;1&#34; are representative of the key-off state and the key-on state, respectively. In the following description, a key 1f is identified by the key number. For example the key 1f with note number &#34;60&#34; is represented as key &#34;60&#34;. The note flag is rewritten by the keyboard data processing section 3aa, and the sostenuto data processing section 3ab changes the sostenuto flag between &#34;0&#34; and &#34;1&#34;. For example, the note flag &#34;1&#34; of the key &#34;60&#34; represents that the key &#34;60&#34; causes the associated hammer assembly 1d to strike the strings 1e. On the other hand, the sostenuto flag &#34;1&#34; of the key &#34;61&#34; represents that the sostenuto pedal 1o prevents the vibrating strings 1e from the damper head 1h after the release of the key &#34;61&#34;. The note flag and the sostenuto flag form in combination key status data JD for each key 1f. 
     Turning back to FIG. 2, the music data codes are supplied from the information storage medium to the keyboard data processing section 3aa and the sostenuto data processing section 3ab. The keyboard data processing section 3aa extracts the impact data GD and the released key data RD from the music data codes ED. The keyboard data processing section 3aa checks the key status data table 3ac to see what is current key status of a given key 1f, and rewrites the note flag. When the impact data GD is supplied to the keyboard data processing section 3aa, the keyboard data processing section 3aa changes the note flag from &#34;0&#34; to &#34;1&#34; at the impact time. On the other hand, when the released key data RD is supplied to the keyboard data processing section 3aa, the keyboard data processing section 3aa rewrites the note flag to &#34;0&#34; at the key releasing time. Thus, the keyboard data processing section 3aa reflects the impact/released data GD/RD on the key status data table. 
     The keyboard data processing section 3aa is further operative to produce an instruction for key releasing and an instruction for key depressing in response to the impact data GD and the released key data RD, and the instructions are supplied to the controlling section 3ad. Even though the released key data RD is received, the keyboard data processing section 3aa does not supply the instruction for key releasing in so far as the sostenuto flag is indicative of the pedal-on. 
     The sostenuto data processing section 3ab extracts the sostenuto data SD from the music data codes ED, and changes the sostenuto flag. In detail, when the sostenuto data SD is representative of the pedal-on, the sostenuto data processing section 3ab checks the key status data table 3ac to see what keys 1f have the note flag &#34;1&#34;, and gives the sostenuto flag &#34;1&#34; to the depressed keys 1f identified by the note flag of &#34;1&#34;. For example, when the sostenuto data processing section 3ab receives the sostenuto data SD representative of the pedal-on state, the sostenuto data processing section 3ab changes the sostenuto flag of the key &#34;60&#34; to &#34;1&#34; (see FIG. 3). On the other hand, when the sostenuto data processing section 3ab receives the sostenuto data SD representative of the pedal-off state, the sostenuto data processing section 3ab checks the key status data table 3ac to see what keys have both of the note flag &#34;0&#34; and the sostenuto flag &#34;1&#34;. The sostenuto data processing section 3ab changes the sostenuto flag of the selected keys 1f from &#34;1&#34; to &#34;0&#34;, and supplies the instruction for releasing the selected keys 1f to the controlling section 3ad. 
     Thus, the keyboard data processing section 3aa and the sostenuto data processing section 3ab cooperate with each other for controlling the key motions. Assuming now that the key &#34;60&#34; has the note flag &#34;1&#34; and the sostenuto flag &#34;0&#34; as shown in FIG. 3, the associated hammer assembly 1d is going to strike or has struck the strings 1e. When the sostenuto data processing section 3ab receives the sostenuto data SD representative of the pedal-on status, the sostenuto data processing section 3ab changes the sostenuto flag to &#34;1&#34;. Thereafter, the released key data RD for the key &#34;60&#34; arrives at the keyboard data processing section 3aa. The keyboard data processing section 3aa checks the key status data table to see whether the sostenuto flag is &#34;1&#34; or &#34;0&#34;, and acknowledges that the key &#34;60&#34; has the sostenuto flag of &#34;1&#34;. Then, the keyboard data processing section 3aa changes the note flag from &#34;1&#34; to &#34;0&#34; without generation of the instruction for releasing the key. For this reason, the key &#34;60&#34; remains depressed. Then, the key &#34;60&#34; has both of the note flag of &#34;0&#34; and the sostenuto flag of &#34;1&#34;. Subsequently, the sostenuto data SD for the pedal-off arrives at the sostenuto data processing section 3ab, and the sostenuto data processing section 3ab checks the key status data table 3ac to see what status the key &#34;60&#34; has. The sostenuto data processing section 3ab acknowledges that the key &#34;60&#34; has the note flag &#34;0&#34; and the sostenuto flag &#34;1&#34;. The sostenuto data processing section 3ab supplies the instruction for releasing key to the controlling section 3ad, and changes the sostenuto flag 3ab to &#34;0&#34;. The controlling section 3ab produces a series of positional data (t, X) representative of the backward key trajectory, and the key &#34;60&#34; is moved along the backward key trajectory. Then, the damper head 1h is brought into contact with the set of strings 1e, and takes up the vibrations of the strings 1e. 
     The controlling section 3ad is responsive to the instructions supplied from the keyboard data processing section 3aa and the instruction supplied from the sostenuto data processing section 3ab so as to produce the series of positional data (t, X) for each of the keys 1f to be depressed or released. 
     Program Sequence 
     FIG. 4 illustrates a program sequence executed by the preliminary treatment unit 3a. When a music data code ED arrives at the preliminary treatment unit 3a, the preliminary treatment unit 3a checks the identifier attached to the music data code ED to see whether or not the music data code ED represents the sostenuto data SD as by step SP1. If the answer at step SP1 is given affirmative, the preliminary treatment unit 3a checks the sostenuto data SD to see whether or not it represents the pedal-on state as by step SP2. 
     If the answer at step SP2 is given affirmative, the preliminary treatment unit 3a proceeds to step SP3, and selects the keys in the key-on state from the key status data table 3ac. Subsequently, the preliminary treatment unit 3a changes the sostenuto flag of the selected keys 1f to &#34;1&#34; as by step SP4, and returns to step SP1. The solenoid-operated key actuators 3d maintain the plungers 3e in projected state, and the selected keys 1f remain depressed. For this reason, the acoustic sounds are prolonged. 
     On the other hand, if the sostenuto data SD represents the pedal-off, the answer at step SP2 is given negative, and the preliminary treatment unit 3a proceeds to step SP5. The preliminary treatment unit 3a selects the keys 1f with the sostenuto flag of &#34;1&#34; at step SP5, and supplies the instruction for releasing key to the controlling section 3ad so as to release the selected keys with the note flag of &#34;0&#34; as by step SP6. The controlling section 3ad produces a series of positional data (t, X) representative of a backward key trajectory for each of the keys 1f to be released, and supplies the positional data (t, X) to the motion controller 3b. 
     After step SP6, the preliminary treatment unit 3a changes the sostenuto flag of each of the released keys 1f to &#34;0&#34; representative of the pedal-off state as by step SP7. In this way, when the music data code ED representative of the sostenuto data SD is supplied to the preliminary treatment unit 3a, the preliminary treatment unit 3a repeats the loop consisting of steps SP1 to SP7, and the loop SP1 to SP7 is realized by the sostenuto data processing section 3ab in FIG. 2. 
     On the other hand, if the music data code ED is representative of another kind of data, the answer at step SP1 is given negative, and the preliminary treatment unit 3a checks the music data code ED to see whether or not it represents the released key data RD as by step SP8. 
     If the answer at step SP8 is given affirmative, the preliminary treatment unit 3a selects one of the keys 1f specified by the released key data RD, and checks the key status data table 3ac to see whether or not the sostenuto flag of the specified key 1f represents the pedal-on state as by step SP9. If the answer at step SP9 is given affirmative, it is necessary to prolong the acoustic sound, and the preliminary treatment unit 3a ignores the released key data RD as by step SP10. In other words, the preliminary treatment unit 3a does not generate the instruction for releasing the key. After step SP10, the preliminary treatment unit 3a changes the note flag of the specified key 1f to &#34;0&#34; representative of the key-off state as by step SP11, and returns to step SP1. 
     On the other hand, if the sostenuto flag of the specified key 1f is &#34;0&#34; or in the pedal-off state, the answer at step SP9 is given negative, and the preliminary treatment unit 3a generates the instruction for releasing the key as by step SP12. The controlling unit 3ad is responsive to the instruction for releasing the key for producing a series of positional data (t, X) representative of a backward key trajectory. After step SP12, the preliminary treatment unit 3a proceeds to step SP11. 
     If the music data code ED does not represent the released key data RD, the answer at step SP8 is given negative, and the preliminary treatment unit 3a acknowledges the music data code ED to represent the impact data GD. Then, the preliminary treatment unit 3a proceeds to step SP13. The preliminary treatment unit 3a selects one of the keys specified by the impact data GD, and achieves the following jobs at step SP13. 
     First, the preliminary treatment unit 3a checks the key status data table 3ac to see whether the sostenuto flag of the specified key 1f represents the pedal-on state or the pedal-off state. If the sostenuto flag represents the pedal-on state, the specified key 1f remains in the end position, and it is impossible to depress it. For this reason, the preliminary treatment unit 3a supplies the instruction for releasing the key to the controlling section 3ad, and makes the specified key 1f ready for depressing. Thereafter, the preliminary treatment unit 3a supplies the instruction for depressing the key to the controlling section 3ad. Thus, the preliminary treatment unit 3a can reproduce the complicated key motion, i.e., releasing the key under the pedal-on state and immediately depressing it without releasing the sostenuto pedal. If the sostenuto data SD simply retards the release of the key as carried out by the prior art automatic player piano, the forward key motion under the pedal-on state is missing, because the key is still in the end position. 
     On the other hand, if the sostenuto flag represents the pedal-off state, the preliminary treatment unit 3a simply supplies the instruction for releasing the key to the controlling section 3ad. 
     After step SP13, the preliminary treatment unit 3a changes the note flag of the specified key to &#34;1&#34; as by step SP14, and returns to step SP1. Thus, the preliminary treatment unit 3a processes the released key data RD and the impact data GD through the loop consisting of steps SP1 and SP8 to SP14, and the execution through the loop is corresponding to the keyboard data processing section 3aa in FIG. 2. 
     As will be appreciated from the foregoing description, the automatic player piano according to the present invention records the pedal state of the sostenuto pedal 1o independently of the key motion, and both sostenuto and impact/releasing key data SD/GD/RD independently form parts of the music data codes ED. For this reason, the music data codes are available for both of an automatic player piano equipped with a pedal actuator and the automatic player piano without the pedal actuator. Thus, the automatic player piano according to the present invention enhances the data compatibility. 
     The electric player system 3 according to the present invention ignores the key releasing data RD in the presence of the sostenuto flag representative of the pedal-on state in the playback (see step SP10), and the associated solenoid-operated key actuators 3d maintains the key at the end position. If the electric player system 3 is supplied with the sostenuto data SD representative of the pedal-off state before the impact data GD, the electric player system 3 causes the key 1f to return toward the rest position (see step SP6). On the other hand, if the electric player system 3 is supplied with the impact data GD before receipt of the sostenuto data SD representative of the pedal-off state, the electric player system 3 supplements the instruction for releasing the key, and, thereafter, causes the key to be depressed (see step SP13). Thus, the automatic player piano faithfully reproduces the complicated key motion in the playback. 
     Although a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. 
     For example, the acoustic piano may be an upright piano, and the present invention may appertain to another kind of keyboard musical instrument such as, for example, an organ. 
     The key may be released until a deep position on the backward key trajectory such as, for example, 6 millimeters under the rest position so as to allow the electric player system 3 to depress the key before the damper head 1h is brought into contact with the strings 1e. 
     When the sostenuto data SD represents the pedal-on state, the electric player system 3 may maintain a key 1f at an intermediate position on the forward key trajectory such as 9 millimeters under the rest position so that a pianist conforms the pedal-on state through the position of the key 1f. 
     The pedal sensor 2b may measure the velocity of the sostenuto pedal 1o so as to record the pedal velocity. In this instance, the electric player system 3 may calculate a target backward key velocity on the basis of the pedal velocity in the playback so as to control the released key.