Chord judging apparatus and chord judging method

• US 10,410,616 B2
• Filed: 08/15/2017
• Issued: 09/10/2019
• Est. Priority Date: 09/28/2016
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Minamitaka, Junichi
• Primary Examiner(s): Warren, David S
• Assistant Examiner(s): Schreiber, Christina M
• Application Number:
  US15/677,672
• Publication Number:
  US 20180090118A1
• Time in Patent Office: 756 Days
• Field of Search: 84613
• CPC Class Codes: G10H 1/0066 using a MIDI interface
• CPC Class Codes: G10H 1/383 Chord detection and/or recognition, e.g. for correction, or automatic bass generation
• CPC Class Codes: G10H 1/40 Rhythm
• CPC Class Codes: G10H 2210/076 for extraction of timing, tempo; Beat detection
• CPC Class Codes: G10H 2210/081 for automatic key or tonality recognition, e.g. using musical rules or a knowledge base
• CPC Class Codes: G10H 2210/395 Special musical scales, i.e. other than the 12-interval equally tempered scale; Special input devices therefor
• CPC Class Codes: G10H 2210/576 Chord progression
• CPC Class Codes: G10H 2250/021 Dynamic programming, e.g. Viterbi, for finding the most likely or most desirable sequence in music analysis, processing or composition

Abstract

A chord judging apparatus for judging chords of a musical piece, is provided with a processor and a memory for storing data of the musical piece, wherein the processor specifies plural segments in the data of the musical piece, estimates a tonality of each of the specified segments based on component tones included in the segment, and judges a chord of the plural segments of the musical piece based on modulation in tonality, when modulation is introduced in the estimated tonalities of the plural segments.

Claims

1. A chord judging method performed by a processor to judge chords of a musical piece whose data is stored in a memory, the method comprising executing, with the processor, processes of:

estimating a first tonality based on component tones included in a first segment having a first length, the first segment being specified in the data of the musical piece;

estimating a second tonality based on component tones included in a second segment having a second length different from the first length, the second segment being specified in the data of the musical piece and at least partially overlapping with the first segment;

comparing the estimated first tonality with the estimated second tonality to judge a tonality or a chord of the first segment of the musical piece;

comparing the estimated first tonality with the estimated second tonality to decide an appropriate tonality; and

judging a chord of the first segment of the musical piece based on the decided appropriate tonality.

2. The chord judging method according to claim 1, wherein

the first segment has a first segment length equivalent to one measure and the second segment has a second segment length equivalent to multiples of one measure;

and

the processor executes a process of;

comparing the first tonality and the second tonality judged for each measure in which the first segment and the second segment overlap each other to determine an appropriate tonality of the measure.

3. The chord judging method according to claim 2, wherein the processor executes a process of:

sequentially specifying the first segments having the first segment length or the second segments having the second segment length in the data of the musical piece, each with a starting position shifted by one measure.

4. The chord judging method according to claim 1, wherein the processor executes a process of:

displaying the judged chord on a displaying unit.

5. A chord judging method performed by a processor to judge chords of a musical piece whose data is stored in a memory, the method comprising executing, with the processor, processes of:

estimating a first tonality based on component tones included in a first segment having a first length, the first segment being specified in the data of the musical piece;

estimating a second tonality based on component tones included in a second segment having a second length different from the first length, the second segment being specified in the data of the musical piece and at least partially overlapping with the first segment;

comparing the estimated first tonality with the estimated second tonality to judge a tonality or a chord of the first segment of the musical piece;

judging component tones of each beat in a measure of the musical piece; and

determining a chord of the beat based on the component tones judged at the beat.

6. The chord judging method according to claim 5, wherein the processor executes processes of:

deciding a value of power information of each of musical tones of the musical piece which is made note-on within a time period of the first segment, the second segment or the beat, based on the musical tone'"'"'s velocity and sounding time length in the time period in judging component tones respectively in the first segment, the second segment or the beat; and

accumulating the decided values of power information for pitch classes corresponding respectively to pitches of the musical tones to calculate accumulative values of power information respectively for the pitch classes in the first segment, the second segment or the beat.

7. The chord judging method according to claim 6, wherein

when the pitch classes corresponding to the pitches of the musical tones coincide respectively with scale tones in the candidates for the first tonality, scale tones in the candidate for the second tonality or component tones in the candidate for a chord, correspondingly to candidates for the first tonality of the first segment, the second tonality of the second segment or a chord of a beat, the processor executes a process of

(a) accumulating the calculated accumulative values of power information for the pitch classes to find first power evaluation values;

when the pitch classes corresponding to the pitches of the musical tones do not coincide with the scale tones in the candidates for the first tonality, the scale tones in the candidate for the second tonality or the scale tones in the candidate for a chord,

the processor executes a process of;

(b) accumulating the accumulative values of power information calculated in the pitch classes to find second power evaluation values; and

the processor executes a process of;

(c) comparing the first power evaluation values and the second power evaluation values found respectively for the candidates for the first tonality and the second tonality or the chord to judge the first tonality, the second tonality or the chord respectively in the first segment, the second segment, or the beat.

8. A non-transitory computer-readable recording medium with an executable program stored thereon, the executable program, when installed on a computer, making the computer execute processes of:

specifying plural segments in data of the musical piece stored in a memory;

estimating a tonality of each of the specified segments based on components tones included in the segment;

judging a chord of the plural segments of the musical piece based on modulation in tonality, when modulation is introduced in the estimated tonalities of the plural segments;

specifying a first segment having a first length in the data of the musical piece;

estimating a first tonality of the first segment based on component tones included in the first segment;

specifying a second segment having a second length different from the first length in the data of the musical piece, the second segment at least partially overlapping with the first segment;

estimating a second tonality based on component tones of the second segment;

comparing the estimated first tonality with the estimated second tonality to judge a tonality of the first segment of the musical piece; and

judging a chord of the first segment of the musical piece based on the judged tonality of the first segment.

9. A chord judging apparatus for judging chords of a musical piece, the apparatus comprising:

a processor; and

a memory for storing data of the musical piece;

wherein the processor executes processes of;

estimating a first tonality based on component tones included in a first segment having a first length, the first segment being specified in the data of the musical piece;

estimating a second tonality based on component tones included in a second segment having a second length different from the first length, the second segment being specified in the data of the musical piece and at least partially overlapping with the first segment;

comparing the estimated first tonality with the estimated second tonality to judge a tonality or a chord of the first segment of the musical piece;

comparing the estimated first tonality with the estimated second tonality to decide an appropriate tonality; and

judging a chord of the first segment of the musical piece based on the decided appropriate tonality.

10. The chord judging apparatus according to claim 9, wherein the processor:

specifies plural segments in the data of the musical piece including the first segment and the second segment;

estimates a tonality of each of the specified segments based on component tones included in the segment; and

judges a chord of the plural segments of the musical piece based on modulation in tonality, when modulation is introduced in the estimated tonalities of the plural segments.

11. The chord judging apparatus according to claim 9, wherein the processor:

judges component tones at each beat in a measure of the musical piece; and

determines a chord of the beat based on the component tones judged at the beat;

decides a value of power information of each of musical tones of the musical piece which is made note-on within a time period of the first segment, the second segment or the beat, based on the musical tone'"'"'s velocity and sounding time length in the time period in judging component tones respectively in the first segment, the second segment or the beat; and

accumulates the decided values of power information for pitch classes corresponding respectively to pitches of the musical tones to calculate accumulative values of power information respectively for the pitch classes in the first segment, the second segment or the beat.

12. The chord judging apparatus according to claim 11, wherein

when the pitch classes corresponding to the pitches of the musical tones coincide respectively with scale tones in the candidates for the first tonality, scale tones in the candidate for the second tonality or component tones in the candidate for a chord, correspondingly to candidates for the first tonality of the first segment, the second tonality of the second segment or a chord of a beat, the processor

(a) accumulates the calculated accumulative values of power information for the pitch classes to find first power evaluation values;

and

when the pitch classes corresponding to the pitches of the musical tones do not coincide with the scale tones in the candidates for the first tonality, the scale tones in the candidate for the second tonality or the scale tones in the candidate for a chord, the processor

(b) accumulates the accumulative values of power information calculated in the pitch classes to find second power evaluation values; and

the processor

(c) compares the first power evaluation values and the second power evaluation values found respectively for the candidates for the first tonality and the second tonality or the chord to judge the first tonality, the second tonality or the chord respectively in the first segment, the second segment, or the beat.

13. The chord judging apparatus according to claim 9, wherein the first segment has a first segment length equivalent to one measure and the second segment has a second segment length equivalent to multiples of one measure;

and

the processor compares the first tonality and the second tonality decided for each measure in which the first segment and the second segment overlap each other to determine an appropriate tonality of the measure.

14. The chord judging apparatus according to claim 13, wherein the processor sequentially specifies the first segments having the first segment length or the second segments having the second segment length in the data of the musical piece, each with a starting position shifted by one measure.

15. The chord judging apparatus according to claim 9, wherein the processor displays the judged chords on a displaying unit.

16. A chord judging apparatus for judging chords of a musical piece, the apparatus comprising:

a processor; and

a memory for storing data of the musical piece;

wherein the processor executes processes of;

estimating a first tonality based on component tones included in a first segment having a first length, the first segment being specified in the data of the musical piece;

estimating a second tonality based on component tones included in a second segment having a second length different from the first length, the second segment being specified in the data of the musical piece and at least partially overlapping with the first segment;

comparing the estimated first tonality with the estimated second tonality to judge a tonality or a chord of the first segment of the musical piece;

judging component tones of each beat in a measure of the musical piece; and

determining a chord of the beat based on the component tones judged at the beat.