Method and electronic apparatus for processing a digital musical file

Abstract

 Method and electronic apparatus (1) for processing a digital musical file (F), whereby a related chord progression (CP) is extracted defining the harmony of the musical file; such a chord progression (CP) being then displayed on a screen (4) in real time and in synchronization with the playback of the musical file (F) .

Description

[0001] The present invention relates to a method and an apparatus for processing a digital musical file.

[0002] one preferred embodiment of the present invention consists in processing musical files of SMF-type (i.e. Standard MIDI File) and the description of the present invention clearly refers to this preferred embodiment, without therefore loosing its general scope.

[0003] SMF-type musical files are commonly used as musical bases during concerts performed by a small number of musicians (typically one or two musicians) for a restricted audience or on any occasion in which requiring a large number of musicians to play would be too costly. During such kind of use, the musician plays his/her own musical instrument while an SMF-type musical file is played back by an SMF player and thus used as a musical base. Obviously, earlier on the musician must have studied the SMF-type musical file to determine a chord progression defining the harmony of the musical file, so that he/she can play this chord progression by his/her own musical instrument while the SMF-type musical file is played back. Studying SMF-type musical files to be able to determine their corresponding chord progressions is very time-consuming for musicians, because during their performances musicians need to be able to play a wide selection of songs to meet all the various requests they may receive from the audience. In addition it happens quite often that the audience ask a musician to play a song, which he/she can't play because he/she hasn't studied it earlier on, even though he/she's got the corresponding SMF-type musical file available.

[0004] To determine the song progression of an SMF-type musical file, some software products have been released, which are capable of analyzing an SMF-type musical file and working out the corresponding chord progression. However, this kind of software products work out the full chord progression of a musical file, which results to be extremely complicated and practically impossible to play for a musician, unless the musician carries out a hard simplification work on it. Basically, this kind of software products results to be useful only to analyze SMF-type musical files subsequently for educational and composition purposes as well as to transcribe musical sequences.

[0005] To try and solve the above explained inconveniences, the proposal has been forwarded to enclose the corresponding chord progression in text format with every SMF-type musical file. Such a proposal, however, hasn't ever been successful with professional musicians and, at present, it's still rare to find an SMF-type musical file having its own chord progression in text format enclosed.

[0006] The scope of the present invention is to provide a method and an electronic apparatus to process a digital musical file without the above described inconveniences and whose implementation is easy and cost-effective at the same time.

[0007] According to the present invention, a method is provided to process a digital musical file as stated in claim 1.

[0008] According to the present invention, a method is provided to process a digital musical file as stated in claim 28.

[0009] According to the present invention, an electronic apparatus is also provided to process a digital musical file as stated in claim 41.

[0010] The present invention is herein described with reference to the enclosed drawings, which show an example of its non-restrictive embodiment, wherein:

■ Fig. 1 shows an electronic apparatus for playing back and processing SMF-type musical files according to the present invention;

■ Fig. 2 schematically shows two images visualized by a liquid crystal display provided in the electronic apparatus shown in Fig. 1.

[0011] Number 1 in Fig. 1 shows a synthesizer device to play back and process SMF-type musical files. An SMF-type musical file comprises a plurality of channels (typically 16 channels), which are either divided into their corresponding tracks (format "1") or into one single track (format "0"). Each channel contains a note sequence, wherein each note is associated with its corresponding code (referred to as "Program Change") identifying the tone and with its corresponding value (referred to as "Hold") identifying its possible duration extension.

[0012] With reference to the "General MIDI Sound Set" specifications, an SMF-type musical file F can contain tones belonging to 128 different musical instruments, that are divided into 16 families, each family consisting of 8 different musical instruments. Consequently, each musical instrument is identified by a progressive number ranging from 1 up to 128. For a clear reference, the 16 families are the following:

FAMILY	PROGRESSIVE NUMBER	NAME
1	1-8	Piano
2	9-16	Chromatic Perc.
3	17-24	Organ
4	25-32	Guitar
5	33-40	Bass
6	41-48	Orchestra
7	49-56	Ensemble
8	57-64	Brass
9	65-72	Reed
10	73-80	Pipe
11	81-88	Synth Lead
12	89-96	Synth Pad
13	97-104	Synth Effects
14	105-112	Ethnic
15	113-120	Percussive
16	121-128	Sound Effects

[0013] The synthesizer apparatus 1 comprises a box device 2 housing a processing unit 3; a display 4, that is driven by the processing unit 3; a 3.5" floppy disk drive 5 (or any other mass-storage memory like Smart Media, Compact Flash, Hard Disk, etc.), that is connected with the processing unit 3; and a keyboard 6, that is connected with the processing unit 3.

[0014] In particular, the processing unit 3 comprises a microprocessor, ROM-type memories containing the operative system of the microprocessor, RAM-type memories used by the microprocessor, and a group of controllers for controlling the display 4, the drive 5, the keyboard 6, and other external devices that can be connected with the synthesizer apparatus 1.

[0015] The synthesizer apparatus 1 is typically connected with an amplifier 7, which is capable of amplifying a musical signal coming out from the synthesizer apparatus 1 and drive it to a pair of speaker boxes 8.

[0016] Usually a user inserts a floppy disk 9 containing an SMF-type musical file F into the floppy disk drive 5 and commands the processing unit 3 by means of the keyboard 6 to play back the SMF-type musical file F and transmit the related musical signal to the amplifier 7. While playing it back, the processing unit 3 processes the SMF-type musical file F to extract its related chord progression CP defining the harmony of the very musical file F and to visualize such a chord progression CP on the display 4 simultaneously with the playback of the musical file F. In other words, while the musical file F is played back by the synthesizer apparatus 1, its related chord progression CP is visualized on the display 4 in synchronization with the playback of the very musical file F. Therefore, during the playback of the musical file F, on the display 4 the user can watch what chord progression CP is associated with the musical file F and play some notes by using his/her instrument 9 (typically his/her instrument 9 is also connected with the amplifier 7) consistently with the visualized chord sequence.

[0017] It becomes obvious that a user can play his/her instrument 9 by using an SMF-type musical file as his/her accompaniment, even if he/she hasn't ever studied it earlier on, since simultaneously and in synchronization with the playback of the musical file F the synthesizer apparatus 1 visualizes the chord progression CP that is associated with the musical file F and that defines the harmony of the very musical file F.

[0018] According to alternative embodiments, the synthesizer apparatus 1 may be either independent, as shown in Fig. 1, or integrated into one musical instrument, typically a keyboard.

[0019] As shown in Fig. 2, while the chord progression CP is visualized, the display 4 visualizes the current chord CC and one of the subsequent chords SC at least. In particular, the number of the visualized subsequent chords SC coming after the current chord CC can be chosen by the user by means of the keyboard 6 and it ranges from one up to a maximum number, that depends on the size of the display 4. Of course, if the same chord is repeated subsequently several times, then this chord appears as both current chord CC as well as subsequent chord SC.

[0020] By means of the keyboard 6 the user can choose what kind of visualization of the CC and SC chords he/she likes. For example, the CC and SC chords can be Visualized by using the alphanumeric representation according to the Anglo-Saxon convention (as shown in Fig. 2), the alphanumeric representation according to the Italian convention, a standard music score, or guitar strings. Depending on user's preferences and on the size of the display 4, it is also possible to use different kinds of representations at the same time. It should also be noticed that the graphic representation of the current chord CC is preferably different from that of the subsequent chords SC so as to help the user when reading the CC and SC chords on the display 4.

[0021] As it will be described in detail later on, the visualization of the CC and SC chords on the display 4 is updated at visualization time intervals whose duration is constant, predetermined and linked with the time duration of the rhythmic division of the playing back musical file F. In other words, between two subsequent modifications of the CC and SC chords, which are visualized on the display 4, a time interval lapses, which is constant and equal to a predetermined visualization time interval. Consequent to the above explanation, it is obvious that the CC and SC chords visualized on the display 4 are not updated exactly as they occur in the playback of the musical file F, but they are updated only at certain visualization time intervals, whose duration is predetermined.

[0022] How the processing unit 3 extracts the chord progression CP corresponding to the musical file F is described here below.

[0023] First, all tracks related to non-harmonic sounds are eliminated (alternatively, if the SMF-type musical file F is codified in format "0" the corresponding channels are eliminated), for example drum tracks, tracks that may potentially include non-harmonic parts, and tracks containing several transitory and accessory notes that are not needed to determine the harmony, such as the solo track. In an SMF-type musical file F, the drum track is usually the track number 10 and the solo track is usually the track number 4, so the processing unit 3 is going to eliminate these two tracks. If the musical file F is not an SMF-type musical file, the processing unit 3 has to analyze the musical file F in advance according to known state-of-the-art procedures SO as to identify non-harmonic tracks. Alternatively the user can communicate to the processing unit 3 which non-harmonic tracks are to be eliminated by means of the keyboard 6.

[0024] Then, from the musical file F, that is deprived of the non-harmonic tracks and the solo track, all those notes are eliminated that are associated with non-harmonic instruments (or tones), with solo instruments (or tones), and with instruments (or tones) frequently used for transitory or accessory notes. In other words, all those notes are eliminated, which have a "Program Change" value belonging to a non-harmonic, solo instrument (or tone) or to an instrument (or tone) that is frequently used for transitory or accessory notes. For this purpose, the table 1 shown here below is stored in the processing unit 3. The table 1 shows which instruments are useful to determine the harmony and can therefore be referred to as harmonic instruments and which instruments are not useful to determine the harmony and can therefore be referred to as non-harmonic instruments. The table 1 has been worked out by combining a theoretical analysis with a series of experimental tests; consequently it is subject to changes depending on the desired final effect.

TABLE 1:

INSTRUMENTS REFERRED TO AS HARMONIC INSTRUMENTS
HARMONIC INSTRUMENTS	FAMILY
1-8	Piano
12	Chromatic Perc.
17-22 e 24	Organ
25-28	Guitar
33-40	Bass
41-47	Orchestra
49-55	Ensemble
59 e 61-64	Brass
66-68 e 73-75	Reed
---	Pipe
82	Synth Lead
89-96	Synth Pad
97 e 99-104	Synth Effects
---	Ethnic
---	Percussive
---	Sound Effects

[0025] In other words, according to the Table 1 all those notes are eliminated, which belong to instruments having the following "Program Change": 9-11, 13-16, 23, 29-32, 48, 56-58, 60, 65, 69-72, 76-81, 83-88, 98, 105-128.

[0026] Once the SMF-type musical file F has been deprived of the non-harmonic tracks and the notes having non-harmonic tones, it's transmitted to a chord recognition algorithm. Such kind of algorithms are known in the state-of-the-art literature and, for instance, the chord recognition algorithm described in the patent US-5235126-A1 can be used.

[0027] The chord recognition algorithm outputs a chord sequence, which is still too complicated for a musician to use it in real time. This is the reason why two subsequent filtering processes are applied to the outputted chord sequence.

[0028] The first filtering process aims at simplifying some complex chords, since some complex chords can be reduced into simpler chords without causing any substantial difference in what the listener perceives. For example, if a chord is recognized as C5b, 7, 10b, this very chord is reduced into the chord C5b, which has got the same substantial features. For this purpose the Table 2 shown here below is stored in the processing unit 3. The Table 2 shows the principles adopted to simplify complex chords, as it indicates every complex chord and its corresponding simplified chord. The processing unit 3 scrolls the chord sequence provided by the chord recognition algorithm and replaces each complex chord with its corresponding simplified chord by using the Table 2. The Table 2 results from a theoretical analysis combined with a series of experimental tests and is, therefore, subject to variations depending on the desired final effect.

TABLE 2:

RULES FOR SIMPLIFYING COMPLEX CHORDS
COMPLEX CHORD	SIMPLIFIED CHORD
12#	Maj
2, 6, 9b	9
5b,12	5b
5b,7,10b	5b
5b,7,12	5b
5b,7,9,12	5b
5b, 9	5b
6, 13#	6
6,9	6
6,9b	6
7,10b	7
7,12#	7
7,14	7
7,9	7
7,9,11,11#	7,9
7,9,12#	7,9
9,11	9
Dim 12	Dim
Dim 13#	Dim
Maj7 11	Maj7
Maj 7 11#	Maj7
Maj7,6,9	Maj7 9
min 11#	min
min 6,13#	min 6
min 6,9b	min 6
Sus 10	Sus
Sus 11#	Sus
Sus 7,14	Sus 7
Sus 7,9	Sus 7
Sus Maj7	Sus

[0029] The second filtering process is aimed at avoiding an excessive number of chord changes, since it has been noticed that the chord sequence obtained from the musical file F usually features numerous chord changes and some of such chord changes are usually too fast for musicians to be able to actually use them. As a matter of fact, the second filtering process eliminates the suspended chord (Sus), whose key note is seven semitones higher than the key note of the immediately previous chord (e.g. in the chord progression CMaj, GSus, the Gsus chord is the one to be eliminated).

[0030] In addition, the filtering process eliminates the subsequent chord whenever the sound of the previous chord is very similar to the sound of the subsequent chord. For this purpose, the Table 3 shown here below is stored in the processing unit 3. Whenever a pair of chords (first chord and second chord) belonging to the Table 3 shown here below is found in sequence inside a chord progression, then the second chord is eliminated. The Table 3 results from a theoretical analysis combined with a series of experimental tests and is, therefore, subject to variations depending on the desired final effect.

TABLE 3:

RULES FOR ELIMINATING SUBSEQUENT CHORDS
FIRST CHORD	SECOND CHORD
CHORDN_MAJ	CHORDN_MAJ7
CHORDN_MAJ	CHORDN_SUS
CHORDN_MIN	CHORDN_MIN7
CHORDN_7	CHORDN_SUS
CHORDN_MAJ7	CHORDN_6
CHORDN_MIN7	CHORDN_MIN9
CHORDN_SUS	CHORDN_9
CHORDN_6	CHORDN_MAJ
CHORDN_6	CHORDN_7
CHORDN_9	CHORDN_6
CHORDN_9	CHORDN_MAJ7
CHORDN_MIN6	CHORDN_MIN7
CHORDN_MIN9	CHORDN_MIN7

Finally, the second filtering process eliminates all those chords which are not held for a predetermined time interval at least, such a predetermined time interval being preferably 100 CPT (Clock Pulse Time). In particular, 1 CPT is an internal time calculation unit of the processing unit 3. Its time length results from the following formula:

wherein BPM stands for Beat Per Minute, namely the Beats Per Minute used to play back the musical file F; TB stands for Time Base, namely the temporal resolution of the processing unit 3. The typical time length of 100 CPT may range from 200 msec up to 500 msec.

[0031] At end of the above simplification processes, chords are aligned along a time line that is divided into a sequence of windows, wherein each window has a time length equal to the visualization time interval described further above and comprises all the chords starting on a instant contained in that very window. Obviously, each window has its own initial instant, which necessarily coincides with the final instant of the previous window, and its own final instant, which necessarily coincides with the initial instant of next window. Inside every window the processing unit 3 moves the chords contained in the window, so as to make the initial instants of the chords coincide with the initial or final instant of the window. In particular, inside every window a threshold is established, which is typically positioned at 75% of the window time length. The chords contained in the window having their initial instants before the threshold are moved to the initial instant of the window and the chords contained in the window having their initial instants after the threshold are moved to the final instant of the window. Whenever several chords result to be in the same either initial or final instant, only the chord is kept which was previously performed as the last one. In other words, only the chord is kept whose initial instant previously resulted to be the last one, whereas all the other chords are eliminated.

[0032] According to the above description, it is obvious that the time length of every window is equal to the visualization time interval described further above and every window comprises no more than one chord whose initial instant coincides with the initial instant of the window (and therefore with the final instant of the previous window) as well as no more than one chord whose initial instant coincides with the final instant of the window (and therefore with the initial instant of next window). The processing unit 3 updates the content of the display 4 to show the current chord CC and the subsequent chords SC at time intervals coinciding with the visualization time intervals. Consequently, the content of the display 4 is updated by showing the chords whose initial instants coincide with either the initial or the final instants of the windows.

[0033] The duration of each window, namely the time length of a visualization time interval, results from the time duration of the Time Signature of the musical file F. In other words the time duration of each window results from the Time Signature TS of the musical file F and the BPM value relating to the playback of the musical file F. Time Signature stands for the fraction N/D, wherein N stands for the number of movements and D stands for the value of every movement related to the rhythmic unit called musical Measure. The duration of each window, which is the time length of a visualization time interval, is preferably equal to the time duration of the musical Measure, which is defined by the Time Signature TS of the musical file F whenever either the playback BPM value of musical file F is higher than 145 or the N value of the Time Signature TS relating to the musical file F is 1, 2, 3 and 5. In all the other cases, the duration of each window, which is the time length of a visualization time interval, amounts to half time duration of the musical measure defined by the Time Signature TS of the musical file F.

[0034] Obviously, as described above, the processing unit 3 can extract the chord progression CP from the musical file F both in real time, namely while the musical file F is played back, as well as before the musical file F is played back. In the second event, the chord progression CP is stored in a temporary memory of the processing unit 3 to be then visualized on the display 4 while the musical file F is played back.

[0035] Of course, the above described method for extracting the corresponding chord progression CP from an SMF-type musical file F can be applied to any other type of digital musical file having either a structure similar to that of MIDI files (i.e. including a series of notes and their related tones) or a structure with the representation of audio signals (e.g. Mp3 format and RealAudio format). As far as these second types Of digital musical file are concerned, some algorithms have to be used (these algorithms are known and available in the-state-of-the-art literature) to convert the audio signals into a sequence of notes and their corresponding tones.

[0036] Several field tests proved that the above described method for extracting the chord progression CP from a musical file F is extremely reliable and enables a musician to use an SMF-type musical file F as an accompaniment in his/her performance without any preliminary study being necessary. Moreover, the method used for visualizing the chord progression CP on the display 4 in real time and in synchronization with the playback of the musical file F proved also to be very effective and easy-to-use for users.

Claims

1. A method for processing a digital musical file (F) in order to extract a related chord progression (CP) defining the harmony of the musical file (F); such a method applying a chord recognition algorithm to the musical file (F) in order to provide a chord progression (CP) relating to the chords contained in the musical file (F); the method being characterized in submitting the musical file (F) to a first filtering process before applying the chord recognition algorithm in order to eliminate non-harmonic elements from the musical file (F), to a second filtering process in order to simplify complex chords without modifying the substantial chord perception by the user, and to a third filtering process in order to eliminate non-significant chords, which may not be played without the substantial chord perception by the user being altered.

2. The method according to claim 1, wherein the first filtering process on the musical file (F) eliminates non-harmonic tracks, i.e. non-harmonic elements, from the very musical file (F).

3. The method according to claim 2, wherein non-harmonic tracks consist of drum and solo tracks.

4. The method according to claim 3, wherein the musical file (F) is an SMF-type musical file and non-harmonic tracks are track 4 and track 10.

5. The method according to any of the above claims from 1 through 4, wherein the first filtering process on the musical file (F) eliminates notes coming from non-harmonic tones.

6. The method according to claim 5, wherein the musical file (F) is an SMF-type musical file for musical generators complying with the sound set stated in the General MIDI standard; and wherein notes having a "Program Change" value included in the following list are eliminated: 9-11, 13-16, 23, 29-32, 48, 56-58, 60, 65, 69-72, 76-81, 83-88, 98, 105-128.

7. The method according to any of the above claims from 1 through 6, wherein the second filtering process on the musical file (F) replaces every complex chord included in the chord progression (CP) related to the musical file (F) with a corresponding simplified chord.

8. The method according to claim 7, wherein complex chords and their corresponding simplified chords are listed in the enclosed table entitled RULES FOR SIMPLIFYING COMPLEX CHORDS (Table 2).

9. The method according to any of the above claims from 1 through 8, wherein the third filtering process on the chord progression (CP) related to the chords contained in the musical file (F) eliminates the Suspended chord (Sus), whose key note is seven semitones higher than the key note of the previous chord.

10. The method according to any of the above claims from 1 through 9, wherein the third filtering process reduces the number of chord changes in the chord progression (CP) related to the musical file (F).

11. The method according to claim 10, wherein the third filtering process on the chord progression (CP) related to the musical file (F) eliminates the subsequent chord whenever the sound of the previous chord is similar to the sound of the subsequent chord.

12. The method according to claim 11, wherein the second chord is eliminated, whenever a sequence of a couple of chords, respectively a first and a second chord, is detected inside the chord progression (CP) related to the musical file (F), such couple of chords being listed in the enclosed table RULES FOR ELIMINATING SUBSEQUENT CHORDS (Table 3).

13. The method according to any of the above claims from 10 through 12, wherein the third filtering process on the chord progression (CP) related to the musical file (F) eliminates all those chords that are not held for a predetermined time interval, at least.

14. The method according to claim 13, wherein said predetermined time interval amounts to 100 CPT.

15. The method according to any of the above claims from 1 through 14, wherein the chord progression (CP) is visualized on a display (4) in synchronization with the playback of the musical file (F).

16. The method according to claim 15, wherein to visualize the chord progression (CP) the current chord (CC) and at least one of the subsequent chords (SC) are visualized on the display (4).

17. The method according to claim 16, wherein the graphic representation of the current chord (CC) is different from the graphic representation of subsequent chords (SC).

18. The method according to any of the above claims from 15 through 17, wherein the visualization of the (CC) and (SC) chords on the display (4) is updated and the pause lapsing between one update and the next is equal to the a visualization time interval, whose duration is constant and predetermined.

19. The method according to claim 18, wherein the duration of each visualization time interval depends on the time duration of the rhythmic division of the playing back musical file (F).

20. The method according to claim 19, wherein the duration of each visualization time interval depends on the performance tempo (i.e. the BPM value) of the playing back musical file (F) as well as on the Time Signature TS of the musical file (F).

21. The method according to claim 20, wherein the duration of each visualization time interval is equal to the time duration of the musical measure that is defined by the Time Signature TS of the musical file (F).

22. The method according to claim 20, wherein the duration of each visualization time interval is equal to half time duration of the musical measure defined by the Time Signature TS of the musical file (F).

23. The method according to claim 20, wherein the duration of each visualization time interval is equal to the time duration of the musical measure defined by the Time Signature TS of the musical file (F) whenever the BPM (beat per minute) value is higher than 145 or the numerator in the fraction indicating Time Signature TS of the musical file (F) is 1, 2, 3 and 5. The duration of each visualization time interval being equal to half time duration of the musical measure defined by the Time Signature TS of the musical file (F) in all the other cases.

24. The method according to any of the above claims from 18 through 23, wherein the chords included in the chord progression (CP) are aligned along a temporal line, which is divided into a sequence of windows. The duration of each one of such windows is equal to the visualization time interval, has an initial and a final instant, and includes the chords having their initial instant inside the very window. Inside each window, the chords included in one window are moved so as to make the initial instants of the chords coincide with either the initial or the final instant of the window. The visualization of chords (CC, SC) on the display (4) is updated in correspondence with the initial and final instants of every window.

25. The method according to claim 24, wherein inside each window a threshold is established and the chords contained in the window whose initial instant is temporally located before the threshold are moved to the initial instant of the window, and the chords contained in the window whose initial instant is temporally located after the threshold are moved to the final instant of the window.

26. The method according to claim 25, wherein said threshold is placed at 75% of the duration of the window.

27. The method according to claim 24, 25 or 26, wherein whenever several chords result to be located at the same visualization instant, only the chord is kept whose original initial instant was the latest whereas all the other chords are eliminated.

28. The method for processing a digital musical file (F) in order to extract a chord progression (CP) from the very musical file (F) defining the harmony of the musical file (F). Such a method comprising the step of applying a chord recognition algorithm to the musical file (F), which is capable of providing a chord progression (CP) related to the chords contained in the musical file (F); the method being characterized in simplifying the chord progression (CP) related to the chords contained in the musical file (F) and visualizing the simplified chord progression (CP) on a display (4) in synchronization with the playback of the musical file (F).

29. The method according to the claim 28, wherein the current chord (CC) and at least one subsequent chord (SC) is visualized on display (4) to visualize the chord progression (CP).

30. The method according to the claim 29, wherein the graphic representation of the current chord (CC) is different from the graphic representation of the subsequent chords (SC).

31. The method according to any of the above claims from 28 through 30, wherein the visualization of the (CC) and (SC) chords on the display (4) is regularly updated with a pause between one update and the next one that is equal to a visualization time interval, whose time length is constant and predetermined.

32. The method according to the claim 31, wherein the duration of every visualization time interval depends on the time duration of the rhythmic division of the playing back musical file (F).

33. The method according to the claim 32, wherein the duration of every visualization time interval depends on the performance tempo (i.e. BPM value) of the playing back musical file (F) as well as on the Time Signature TS of the musical file (F).

34. The method according to the claim 33, wherein the duration of every visualization time interval is equal to the time duration of the musical measure defined by the Time Signature TS of the musical file (F).

35. The method according to the claim 33, wherein the duration of every visualization time interval is equal to half time duration of the musical measure defined by the Time Signature of the musical file (F).

36. The method according to the claim 33, wherein the duration of every visualization time interval is equal to the time duration of the musical measure defined by the Time Signature TS of the musical file (F) whenever the beat per minute BPM value relating to the playback of the musical file (F) is higher than 145 or the numerator in the fraction indicating the Time Signature TS of the musical file (F) is 1, 2, 3 and 5. The duration of every visualization time interval being equal to half time duration of the musical measure defined by the Time Signature TS of the musical file (F) in all the other cases.

37. The method according to any of the above claims from 31 through 36, wherein the chord progression (CP) relating to the chords of the musical file (F) are aligned along a temporal line, which is divided into a sequence of windows. Each one of such windows has a duration that is equal to the visualization time interval, has an initial and a final instant, and comprises all the chords whose initial instants are included inside the window. Inside each window chords are moved so as to make their initial instants coincide with either the initial or the final instant of the window, the visualization of the chords (CC) and (SC) being updated in correspondence with the initial and the final instants of every window.

38. The method according to claim 37, wherein a threshold is established inside each window and the chords included inside the window whose initial instants are temporally located before said threshold are moved to the initial instant of the window, whereas the chords included inside the window whose initial instants are temporally located after said threshold are moved to the final instant of the window.

39. The method according to claim 38, wherein said threshold is placed at 75% of the window duration.

40. The method according to claim 37, 38 or 39, wherein whenever several chords result to be in the visualization instant, only that chord is kept, whose original initial instant was the latest, while all the other chords are eliminated.

41. An electronic apparatus (1) for processing a digital musical file (F) in order to extract a chord progression (CP) relating to the chords defining the harmony of the musical file (F). Such an electronic apparatus (1) comprising playback means (3) for playing back the musical file (F) and calculation means (3) for applying a chord recognition algorithm to the musical file (F), such a chord recognition algorithm being capable of providing a chord progression (CP) relating to the chords contained in the musical file (F); the electronic apparatus (1) being characterized in comprising calculation means (3) capable of simplifying the chord progression (CP) resulting from the chord contained in the musical file (F) as well as a display (4) capable of visualizing the simplified chord progression (CP) in synchronization with the playback of the musical file (F).

42. The electronic apparatus (1) according to claim 41, comprising a musical instrument.

43. The electronic apparatus (1) according to claim 41 or 42, implementing the method described in the above claims from 1 through 40.

Drawing