tracking beat tracking beat Mcgill university :: music technology :: mumt 611>>
Transcript of tracking beat tracking beat Mcgill university :: music technology :: mumt 611>>
trackingtrackingbeatbeat
trackingtrackingbeatbeat
Mcgill university :: music technology :: mumt 611>>
trackingtrackingbeatbeat
What is beat tracking?
… magic box …… magic box …
Input audio
output tatum locations
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What is beat tracking?
“…Estima(tion) of the possibly time-varying tempo and locations of each beat. In Engineering
terms, this is the frequency and Phase of a time-varying signal, the phase Of Which
is zero at a beat location (I.e., where One would tap one’s foot).”
Hainsworth, 2006
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Overview
Motivation & definitions …
early work …
Discrete vs. continuous detection functions …
canonical work: scheirer …
autocorrelation versus comb filtering …
Exemplar Methods …
Persistent problems …>>
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Motivation & definitionsAuto accompaniment
Synchronization of 2 streams
Cd skipping recovery
Time-scaling algorithms
Tempo-synchronous effects/control
Database retrieval
similarity
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Motivation & definitionsBlimes divisions of musical timing… metrical structure… tempo variation… timing deviations… arrhythmic sections
3 hierarchal levels of metrical structure… Tempo… tactus… tatum
Beat tracking / Tempo induction
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Approach overview
Rule based… steedman (1977)… parncutt (1994)
Autocorrelation … Brown (1993)… *Davies & Plumbley (2005)
Oscillating filters… *Large (1994)… *Scheirer (1998)
histogramming… *seppanen (2001)
Multiple agent… *goto (1995)… Dixon (2001)
probabilistic… hainsworth & macleod (2003)… *klapuri (2003)
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Red audioBlack symbolic* causal
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Early Work
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>> music perception and comp sci (1980’s)
Most early work with midi/symbolic data
Rule based
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Early Work
steedman (1977)
large (1994)
Goto (1995)
Scheirer (1998)
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>> MIDI
AUDIO
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Discrete df vs. continuous df
Discrete detection function
… localized onset points, or IOI (inter-onset intervals)
… Suited for monophonic signals
… step 1: Created by various comparative time or time-freq techniques
… step 2: peak picking technique
Continuous detection function
… better for unknown onset densities
… same as step 1 above
… further processing required for important results
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Scheirer
Input audio
Filt_1Filt_2Filt_3Filt_4Filt_5Filt_6
Env_1
frequencyfilterbank
Continuousenveloping
...
Combfilterbank
. . .
. . .
. . .
. . .
. . . ...
...
Sumfltbks
Peakpick
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ACF vs Comb filt
Automatic phase alignment
Possible tempi at multi & fracs
Meter estimation directly avail
Phase Alignment in 2nd step
Commonality not given directly
Meter estimation via decim. & sum
Less expensive
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.Comb filters*
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goto
Input audio Dscrt
Onsetdet
Acf
period
Prior knowledge: 1) frequent ioi is likely ibi 2) sounds likely to occur on beats 3) rhythmic pattern templates 4) chord templates for non-perc music
Priorkn0w
Sub_1Sub_2Sub_3
Sub_7
freqfltrbk
...Crosscorr
alignMulti agents
winner
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klapuri
Input audio
Filt_01Filt_02Filt_03
Filt_36
freqfltrbk
...
Chan_1
Chan_2
Chan_3
Chan_4
...
Combfltrbk
...
...norm
Pwr envPeriod &
Align estim Bar
beat
tatum
Sn-1
Bar
beat
tatum
Sn
HMM
P(sn qn)| Observable variable conditioned by current state=
Traindata
Training data rhythmic pattern templates=
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Davies & plumbley
Input audio
ContDetectfunc
acf
periodicity alignment
Contdep
stateGenstate
2 state model
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Combfltrbk
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Combfltrbk
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comparison
Davies & plumbley
klapuri
scheirer
55.9 61.4 71.2 80.9
23.8 38.9 29.8 48.5
54.8 61.2 68.1 78.9
raw allowedCml% Tot% Cml% Tot%
Raw Cml correct metrical level, continuity requiredraw tot correct metrical level, continuity not requiredAllowed cml 1/2 & 2x tempo allowed, continuity requiredAllowed cml 1/2 & 2x tempo allowed, continuity not required
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Persistent problems
Periodicity switching
Half/double time
Alignment issues
Expressive timing
Non-percussive music
Areas for future work
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conclusions
much progress has been made through several approaches
Possible New methods of extracting periodicity and phase
we need to work on improving the robustness of calculations
Thank you for your time!
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referencesDavies, M.E.P., M. Plumbley. “Context-dependent beat tracking of musical Audio,” IEEE Transactions on Audio, Speech and Language Processing, 15(3), 2007, pp. 1009-20.
Goto, M. “A study of real-time beat tracking for musical audio signals.” PhD thesis, waseda university, 1998.
Hainsworth, s.w. “beat tracking and musical metre analysis,” in Signal processing methods for music transcription, edited by a. Klapuri, and M. Davy, 101-129.New york: Springer science and business media, 2006
Hainsworth, s.w. “techniques for the automated analysis of musical audio”,PhD thesis, department of engineering, university of cambridge, 2004.
KLAPURI, A. “SIGNAL PROCESSING METHODS FOR THE AUTOMATIC TRANSCRIPTION OF MUSIC” PHD THESIS, TAMPERE UNIVERSITY OF TECHNOLOGY, 2004.
Scheirer, e. “music listening systems”, PhD thesis Massachusetts institute ofTechnology, 2000.