TECHNICAL FIELD
[0001] The present invention relates to a music piece analyzer and a music piece analysis
program.
BACKGROUND ART
[0002] 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).
[0003] 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.
CITATION LIST
PATENT LITERATURE(S)
SUMMARY OF THE INVENTION
PROBLEM(S) TO BE SOLVED BY THE INVENTION
[0005] However, since half-time beats are present in some of music pieces, positions of
the half-time beats are adversely detected as beat positions.
[0006] 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
[0007] According to an aspect of the invention, a music piece analyzer includes: a temporary
beat position acquiring unit configured to detect temporary beat positions of 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
determined not to coincide with the temporary beat positions of the music piece data
by the position determination unit.
[0008] According to another aspect of the invention, a music piece analysis program enables
a computer to function as: a temporary beat position acquiring unit configured to
detect temporary beat positions of 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 determined not to coincide with the temporary
beat positions of the music piece data by the position determination unit.
BRIEF DESCRIPTION OF DRAWING(S)
[0009]
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)
[0010] 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).
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] The snare drum detector 22 is configured to output the detected sounding positions
of the snare drum to the beat position determination unit 23.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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] / [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.
[0023] The beat position determination unit 23 is configured to output a determination result
to the beat position setting unit 24.
[0024] 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.
[0025] 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.
[0026] Next, operations and effects in the exemplary embodiment will be described with reference
to flowcharts shown in Fig. 7.
[0027] Firstly, the music piece data SD is inputted into the music piece analyzer 1 (Step
S1).
[0028] The temporary beat position acquiring unit 20 acquires the temporary beat positions
in the music piece data SD (Step S2).
[0029] The snare drum detector 22 detects the sounding positions of the snare drum in the
music piece data SD (Step S3).
[0030] The beat position determination unit 23 determines beat positions on a basis of the
temporary beat positions (Step S4).
[0031] 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).
[0032] 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).
[0033] The beat position setting unit 24 writes the set beat positions into the music piece
data SD (step S7).
[0034] 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).
[0035] 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.
[0036] 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)
[0037] 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
1. A music piece analyzer comprising:
a temporary beat position acquiring unit 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 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 determined not to coincide
with the temporary beat positions of the music piece data by the position determination
unit.
2. The music piece analyzer according to claim 1, wherein the beat position setting unit
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.
3. A music piece analysis program to enable a computer 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 determined not to coincide
with the temporary beat positions of the music piece data by the position determination
unit.