EP3690873B1

EP3690873B1 - Music analysis device and music analysis program

Info

Publication number: EP3690873B1
Application number: EP17926141.7A
Authority: EP
Inventors: Hajime Yoshino; Toshihisa SABI
Original assignee: AlphaTheta Corp
Current assignee: AlphaTheta Corp
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2024-01-24
Anticipated expiration: 2037-09-25
Also published as: EP3690873A4; JP6847242B2; EP3690873A1; WO2019058543A1; JPWO2019058543A1

Description

TECHNICAL FIELD

The present invention relates to a music piece analyzer and a music piece analysis program.

BACKGROUND ART

It has been typically known to detect a kick position of a bass drum or a portion with a high acoustic energy in digital music piece data as a beat position (see, for instance, Patent Literature 1).
A method disclosed in Patent Literature 1 includes: acquiring bar positions in a music piece; equally dividing each of the acquired bar positions to calculate a plurality of frequency spectrograms; and comparing a pattern in which a common component in the plurality of frequency spectrograms appears with a predetermined rhythm pattern to determine a rhythm pattern of the music piece. GOTO, MASATAKA, "Real-time Beat Tracking for Musical Audio Signals", Proceedings of the First Meeting of Special Interest Group on AI Challenges, SIG-Challenge-9801-2, (19981107), pages 171 - 174, discloses a music piece analyzer.
Goto M. et al: "A beat tracking system for acoustic signals of music", PROCEEDINGS OF THE SECOND ACM INTERNATIONAL CONFERENCE ON MULTIMEDIA , MULTIMEDIA '94, ACM PRESS, NEW YORK, NEW YORK, USA, 15 October 1994 (1994-10-15), pages 365-372, DOI: 10.1145/192593.192700; ISBN: 978-0-89791-686-8, discloses a music piece analyzer according to the preamble of claim 1.
JP2008250008 discloses a technique to detect the beat point from a musical tone signal.

CITATION LIST

PATENT LITERATURE(S)

Patent Literature 1: JP 2015-079151 A

SUMMARY OF THE INVENTION

PROBLEM(S) TO BE SOLVED BY THE INVENTION

However, since half-time beats are present in some of music pieces, positions of the half-time beats are adversely detected as beat positions.
An object of the invention is to provide a music piece analyzer and a music piece analysis program that are configured not to erroneously detect a beat position even in a music piece including half-time beats.

MEANS FOR SOLVING THE PROBLEMS

According to an aspect of the invention, a music piece analyzer includes the features of claim 1. An advantageous embodiment is subject matter If claim 2.
According to another aspect of the invention, a music piece analysis program comprises the features of claim 3.

BRIEF DESCRIPTION OF DRAWING(S)

Fig. 1 is a block diagram showing a structure of a music piece analyzer according to an exemplary embodiment of the invention.
Fig. 2 is a schematic diagram illustrating an exemplary rhythm pattern in the exemplary embodiment.
Fig. 3 is a schematic diagram illustrating another exemplary rhythm pattern in the exemplary embodiment.
Fig. 4 is a schematic diagram illustrating still another exemplary rhythm pattern in the exemplary embodiment.
Fig. 5 is a schematic diagram showing that each of sounding positions of a snare drum coincides with corresponding one of temporary beat positions in the exemplary embodiment.
Fig. 6 is a schematic diagram showing that the sounding positions of the snare drum do not coincide with the temporary beat positions in the exemplary embodiment.
Fig. 7 is a flowchart for explaining operations in the exemplary embodiment.
Fig. 8 is a schematic diagram for explaining an effect of the exemplary embodiment.

DESCRIPTION OF EMBODIMENT(S)

Fig. 1 shows a music piece analyzer 1 according to an exemplary embodiment of the invention. The music piece analyzer 1 is in a form of a computer including a CPU 2 and a storage 3 (e.g., a hard disc).
The music piece analyzer 1 is configured to analyze beat positions of music piece data SD, analyzing the beat positions and bar positions of the music piece data SD.
The music piece data SD is in a form of digital data such as WAV or MP3. The music piece data SD may be provided by importing music piece data, which has been played in a music player (e.g., CD player and DVD player), into the music piece analyzer 1 through a USB cable and the like, or may be provided by playing the digital music piece data stored in the storage 3.
The music piece analyzer 1 includes a temporary beat position acquiring unit 20, a snare drum detector 22, a beat position determination unit 23, and a beat position setting unit 24, which function as a music piece analysis program to be run on the CPU 2.
The temporary beat position acquiring unit 20 is configured to acquire temporary beat positions analyzed by a typical technology that detects a kick position of a bass drum or a portion with a high acoustic energy in digital music piece data SD as a beat position. Although in the exemplary embodiment the temporary beat position is acquired from the music piece data SD having the temporary beat positions analyzed in advance, the temporary beat position acquiring unit 20 may detect the temporary beat positions through the FFT analysis and the like. The temporary beat positions may include a half-time beat position. The temporary beat position acquiring unit 20 is configured to output the acquired temporary beat positions of the music piece data SD to the beat position determination unit 23.
The snare drum detector 22 is configured to detect sounding positions of a snare drum in the music piece data SD. Specifically, the snare drum detector 22 is configured to subsequently exclude sounds of the bass drum in a low-pitched sound range by performing an HPF (High Pass Filter) process at a cutoff frequency of 300 Hz and, further, exclude sounds in a high-pitched sound range through an LPF at 2.5 kHz, thereby detecting sounds of the snare drum in a middle-pitched sound range.
The snare drum detector 22 is configured to output the detected sounding positions of the snare drum to the beat position determination unit 23.
It should be noted that the snare drum detector 22 detects the snare drum in the music piece data SD; however, the invention is not limited thereto and the snare drum detector 22 may acquire the sounding positions of the snare drum detected by an external device.
The beat position determination unit 23 (i.e., a position determination unit) is configured to determine whether the sounding positions of the snare drum detected by the snare drum detector 22 are the temporary beat positions of the music piece data SD acquired by the temporary beat position acquiring unit 20. Specifically, in a four-on-the-floor rhythm pattern as shown in Fig. 2, the beat position determination unit 23 determines that the sounding positions of the snare drum are present at the temporary beat positions.
Fig. 2 to Fig. 4 show typical rhythm patterns in respective musical genres. A typical technology, in which beat positions are detected on the basis of kick positions or the like, sometimes causes erroneous detection as in the following examples. In a POP rhythm pattern, for instance, the sounding position of the bass drum is sometimes present at a 2.5th beat with reference to a 1st beat of each of bars in the rhythm pattern as shown in Fig. 3. Similarly, in a Rock rhythm pattern, for instance, the sounding position of the bass drum is sometimes present at a 3.5th beat with reference to the 1st beat of each of bars in the rhythm pattern as shown in Fig. 4. In such cases, if the beat positions are determined simply on the basis of the temporary beat positions, the 2.5th beat and the 3.5th beat would be recognized as beat positions.
Accordingly, for all of the rhythm patterns in four-on-the-floor music, POP music, and Rock music, the beat position determination unit 23 is configured to determine the beat positions on a basis of whether the sounding positions of the snare drum are at the 2.0th beat and the 4.0th beat, that is, at two-beat intervals.
The beat position determination unit 23 is configured to determine the beat positions on the basis of the temporary beat positions and determine whether the determination of the beat positions on the basis of the temporary beat positions are correct.
Specifically, the beat position determination unit 23 is configured to determine whether the determination of the beat positions on the basis of the temporary beat positions is correct in accordance with a remainder of [the sounding positions of the snare drum with reference to the temporary beat positions] I [a sampling number for one beat]. When the remainder is zero, the sounding positions of the snare drum are not at half-time beats with reference to the temporary beat positions as shown in Fig. 5 and thus the determination of the beat positions on the basis of the temporary beat positions is correct. On the other hand, when the remainder is 1, the sounding positions of the snare drum are at half-time beats with reference to the temporary beat positions as shown in Fig. 6 and thus the determination of the beat positions on the basis of the temporary beat positions is not correct.
The beat position determination unit 23 is configured to output a determination result to the beat position setting unit 24.
The beat position setting unit 24 is configured to set the beat positions of the music piece data SD on the basis of the determination result from the beat position determination unit 23.
Specifically, when the beat position determination unit 23 determines that a rhythm pattern is the four-on-the-floor rhythm pattern as shown in Fig. 2, the beat position setting unit 24 sets the temporary beat positions as the beat positions. Subsequently, when the beat position determination unit 23 determines that a rhythm pattern is the POP rhythm pattern as shown in Fig. 3 or Rock rhythm pattern as shown in Fig. 4 and determines that the sounding position of the snare drum is at on-beat, the beat position setting unit 24 sets the temporary beat position as the beat position. On the other hand, when the beat position determination unit 23 determines that a rhythm pattern is the POP rhythm pattern as shown in Fig. 3 or Rock rhythm pattern as shown in Fig. 4 and determines that the sounding positions of the snare drum is at half-time beat, the beat position setting unit 24 sets the sounding position of the snare drum as the beat position.
Next, operations and effects in the exemplary embodiment will be described with reference to flowcharts shown in Fig. 7.
Firstly, the music piece data SD is inputted into the music piece analyzer 1 (Step S1).
The temporary beat position acquiring unit 20 acquires the temporary beat positions in the music piece data SD (Step S2).
The snare drum detector 22 detects the sounding positions of the snare drum in the music piece data SD (Step S3).
The beat position determination unit 23 determines beat positions on a basis of the temporary beat positions (Step S4).
When the sounding position of the snare drum is determined to be at half-time beat with reference to the corresponding temporary beat position, the beat position setting unit 24 determines and sets the sounding position of the snare drum as the beat position (Step S5).
When the sounding position of the snare drum is determined not to be at half-time beat with reference to the corresponding temporary beat position, the beat position setting unit 24 determines and sets the temporary beat position as the beat position (Step S6).
The beat position setting unit 24 writes the set beat positions into the music piece data SD (step S7).
The beat position setting unit 24 saves the music piece data SD, in which the beat positions have been written, in the storage 3 (Step S8).
According to the exemplary embodiment, the beat position determination unit 23 determines the acquired temporary beat positions as correct beat positions on the basis of the sounding positions of the snare drum, thus preventing erroneous detection of the beat positions of the music piece data SD.
For instance, in a case as shown in Fig. 8 where a temporary beat position at a 2.5th beat is detected as a first beat position as in an upper tier in Fig. 8, even when the detection of the temporary beat positions is based on the sounding positions of the bass drum as in a typical technology, the beat position determination unit 23 can determine that the temporary beat position at the 2.5th beat is at half-time beat (i.e., incorrect meter) with reference to the sounding position of the snare drum. Since the beat positions of the snare drum are thus identified at the second beat and the fourth beat, the erroneous detection of the beat positions is prevented by setting the beat positions with reference to the sounding positions of the snare drum.

EXPLANATION OF CODE(S)

1 ...music piece analyzer, 2...CPU, 3...storage, 20...temporary beat position acquiring unit, 22...snare drum detector, 23...beat position determination unit, 24...beat position setting unit, SD...music piece data

Claims

A music piece analyzer (1) comprising:
a temporary beat position acquiring unit (20) configured to detect temporary beat positions in music piece data or acquire the temporary beat positions detected by an external device;

a snare drum detector (22) configured to detect sounding positions of a snare drum in the music piece data or acquire the sounding positions of the snare drum detected by an external device; and

a position determination unit (23) configured to determine whether the detected sounding positions of the snare drum coincide with the temporary beat positions of the music piece data; and

a beat position setting unit (24); where

the beat position setting unit (24) is configured to set beat positions of the music piece data with reference to the sounding positions of the snare drum when the sounding positions of the snare drum is determined not to coincide with the temporary beat positions of the music piece data by the position determination unit, and

characterized in that:
the beat position setting unit (24) is further configured to set the temporary beat positions as beat positions of the music piece data for the temporary beat positions when the sounding position of the snare drum is determined not to be at a half-time beat with reference to the corresponding temporary beat position.
The music piece analyzer according to claim 1, wherein
the beat position setting unit (24) is configured to set the sounding positions of the snare drum as the beat positions of the music piece data at a two-beat interval.
A music piece analysis program to enable a computer, which is comprised in the music piece analyzer (1) of claim 1, to function as:
a temporary beat position acquiring unit configured to detect temporary beat positions in music piece data or acquire temporary beat positions detected by an external device;

a snare drum detector configured to detect sounding positions of a snare drum in the music piece data or acquire the sounding positions of the snare drum detected by an external device;

a position determination unit configured to determine whether the detected sounding positions of the snare drum coincide with the temporary beat positions of the music piece data; and

a beat position setting unit configured to set beat positions of the music piece data with reference to the sounding positions of the snare drum when the sounding positions of the snare drum is determined not to coincide with the temporary beat positions of the music piece data by the position determination unit, and

characterized in that

the beat position setting unit is further configured to set the temporary beat positions as beat positions of the music piece data for the temporary beat positions when the sounding position of the snare drum is determined not to be at a half-time beat with reference to the corresponding temporary beat position.