music21.tempo¶
This module defines objects for describing tempo and changes in tempo.
Functions¶
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music21.tempo.
interpolateElements
(element1, element2, sourceStream, destinationStream, autoAdd=True)¶ Assume that element1 and element2 are two elements in sourceStream and destinationStream with other elements (say eA, eB, eC) between them. For instance, element1 could be the downbeat at offset 10 in sourceStream (a Stream representing a score) and offset 20.5 in destinationStream (which might be a Stream representing the timing of notes in particular recording at approximately but not exactly qtr = 30). Element2 could be the following downbeat in 4/4, at offset 14 in source but offset 25.0 in the recording:
>>> sourceStream = stream.Stream() >>> destinationStream = stream.Stream() >>> element1 = note.Note('C4', type='quarter') >>> element2 = note.Note('G4', type='quarter') >>> sourceStream.insert(10, element1) >>> destinationStream.insert(20.5, element1) >>> sourceStream.insert(14, element2) >>> destinationStream.insert(25.0, element2)
Suppose eA, eB, and eC are three quarter notes that lie between element1 and element2 in sourceStream and destinationStream, as in:
>>> eA = note.Note('D4', type='quarter') >>> eB = note.Note('E4', type='quarter') >>> eC = note.Note('F4', type='quarter') >>> sourceStream.insert(11, eA) >>> sourceStream.insert(12, eB) >>> sourceStream.insert(13, eC) >>> destinationStream.append([eA, eB, eC]) # not needed if autoAdd were true
then running this function will cause eA, eB, and eC to have offsets 21.625, 22.75, and 23.875 respectively in destinationStream:
>>> tempo.interpolateElements(element1, element2, sourceStream, destinationStream, autoAdd = False) >>> for el in [eA, eB, eC]: ... print(el.getOffsetBySite(destinationStream)) 21.625 22.75 23.875
if the elements between element1 and element2 do not yet appear in destinationStream, they are automatically added unless autoAdd is False.
(with the default autoAdd, elements are automatically added to new streams):
>>> destStream2 = stream.Stream() >>> destStream2.insert(10.1, element1) >>> destStream2.insert(50.5, element2) >>> tempo.interpolateElements(element1, element2, sourceStream, destStream2) >>> for el in [eA, eB, eC]: ... print("%.1f" % (el.getOffsetBySite(destStream2),)) 20.2 30.3 40.4
(unless autoAdd is set to false, in which case a Tempo Exception arises...)
>>> destStream3 = stream.Stream() >>> destStream3.insert(100, element1) >>> destStream3.insert(500, element2) >>> eA.id = "blah" >>> tempo.interpolateElements(element1, element2, sourceStream, destStream3, autoAdd = False) Traceback (most recent call last): ... TempoException: Could not find element <music21.note.Note D> with id ...
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music21.tempo.
convertTempoByReferent
(numberSrc, quarterLengthBeatSrc, quarterLengthBeatDst=1.0)¶ Convert between equivalent tempi, where the speed stays the same but the beat referent and number chnage.
>>> tempo.convertTempoByReferent(60, 1, 2) # 60 bpm at quarter, going to half 30.0 >>> tempo.convertTempoByReferent(60, 1, .25) # 60 bpm at quarter, going to 16th 240.0 >>> tempo.convertTempoByReferent(60, 1.5, 1) # 60 at dotted quarter, get quarter 90.0 >>> tempo.convertTempoByReferent(60, 1.5, 2) # 60 at dotted quarter, get half 45.0 >>> tempo.convertTempoByReferent(60, 1.5, 1/3.) # 60 at dotted quarter, get trip 270.0
MetronomeMark¶
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class
music21.tempo.
MetronomeMark
(text=None, number=None, referent=None, parentheses=False)¶ A way of specifying a particular tempo with a text string, a referent (a duration) and a number.
The referent attribute is a Duration object, or a string duration type or a floating-point quarter-length value used to create a Duration.
MetronomeMarks, as Music21Object subclasses, also have .duration object property independent of the referent.
The text attribute will usually return a unicode string. If you use “from __future__ import unicode_literals” this will not be a problem at all.
>>> a = tempo.MetronomeMark("slow", 40, note.Note(type='half')) >>> a.number 40 >>> a.referent <music21.duration.Duration 2.0> >>> a.referent.type 'half' >>> print(a.text) slow
Some text marks will automatically suggest a number.
>>> mm = tempo.MetronomeMark('adagio') >>> mm.number 56 >>> mm.numberImplicit True
For certain numbers, a text value can be set implicitly
>>> tm2 = tempo.MetronomeMark(number=208) >>> print(tm2.text) prestissimo >>> tm2.referent <music21.duration.Duration 1.0>
Unicode values sometimes are hard to work with. Here’s an example that works...
>>> marking = u'très vite' >>> print(marking) très vite >>> print(tempo.defaultTempoValues[marking]) 144 >>> tm2 = tempo.MetronomeMark(marking) >>> tm2.text.endswith('vite') True >>> tm2.number 144
MetronomeMark
bases
MetronomeMark
read-only properties
Read-only properties inherited from Music21Object
:
MetronomeMark
read/write properties
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MetronomeMark.
number
¶ Get and set the number, or the numerical value of the Metronome.
>>> mm = tempo.MetronomeMark('slow') >>> mm.number 56 >>> mm.numberImplicit True >>> mm.number = 52.5 >>> mm.number 52.5 >>> mm.numberImplicit False
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MetronomeMark.
numberSounding
¶ Get and set the numberSounding, or the numerical value of the Metronome that is used for playback independent of display. If numberSounding is None, number is assumed to be numberSounding.
>>> mm = tempo.MetronomeMark('slow') >>> mm.number 56 >>> mm.numberImplicit True >>> mm.numberSounding == None True >>> mm.numberSounding = 120 >>> mm.numberSounding 120
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MetronomeMark.
referent
¶ Get or set the referent, or the Duration object that is the reference for the tempo value in BPM.
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MetronomeMark.
text
¶ Get or set a text string for this MetronomeMark. Internally implemented as a
TempoText
object, which stores the text in aTextExpression
object.>>> from __future__ import unicode_literals
>>> mm = tempo.MetronomeMark(number=123) >>> mm.text == None True >>> mm.text = 'medium fast' >>> print(mm.text) medium fast
Read/write properties inherited from Music21Object
:
MetronomeMark
methods
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MetronomeMark.
durationToSeconds
(durationOrQuarterLength)¶ Given a duration specified as a
Duration
object or a quarter length, return the resultant time in seconds at the tempo specified by this MetronomeMark.>>> from music21 import tempo >>> mm1 = tempo.MetronomeMark(referent=1.0, number=60.0) >>> mm1.durationToSeconds(60) 60.0 >>> mm1.durationToSeconds(duration.Duration('16th')) 0.25
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MetronomeMark.
getEquivalentByNumber
(number)¶ Return a new MetronomeMark object that has an equivalent speed but different number and referent values based on a supplied tempo number.
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MetronomeMark.
getEquivalentByReferent
(referent)¶ Return a new MetronomeMark object that has an equivalent speed but different number and referent values based on a supplied referent (given as a Duration type, quarterLength, or Duration object).
>>> mm1 = tempo.MetronomeMark(number=60, referent=1.0) >>> mm1.getEquivalentByReferent(.5) <music21.tempo.MetronomeMark larghetto Eighth=120.0> >>> mm1.getEquivalentByReferent(duration.Duration('half')) <music21.tempo.MetronomeMark larghetto Half=30.0>
>>> mm1.getEquivalentByReferent('longa') <music21.tempo.MetronomeMark larghetto Imperfect Longa=3.75>
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MetronomeMark.
getMaintainedNumberWithReferent
(referent)¶ Return a new MetronomeMark object that has an equivalent number but a new referent.
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MetronomeMark.
getQuarterBPM
(useNumberSounding=True)¶ Get a BPM value where the beat is a quarter; must convert from the defined beat to a quarter beat. Will return None if no beat number is defined.
This mostly used for generating MusicXML <sound> tags when necessary.
>>> mm = tempo.MetronomeMark(number=60, referent='half') >>> mm.getQuarterBPM() 120.0 >>> mm.referent = 'quarter' >>> mm.getQuarterBPM() 60.0
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MetronomeMark.
getTextExpression
(returnImplicit=False)¶ If there is a TextExpression available that is not implicit, return it; otherwise, return None.
>>> mm = tempo.MetronomeMark('presto') >>> mm.number 184 >>> mm.numberImplicit True >>> mm.getTextExpression() <music21.expressions.TextExpression "presto"> >>> mm.textImplicit False
>>> mm = tempo.MetronomeMark(number=90) >>> mm.numberImplicit False >>> mm.textImplicit True >>> mm.getTextExpression() == None True >>> mm.getTextExpression(returnImplicit=True) <music21.expressions.TextExpression "maestoso">
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MetronomeMark.
secondsPerQuarter
()¶ Return the duration in seconds for each quarter length (not necessarily the referent) of this MetronomeMark.
>>> from music21 import tempo >>> mm1 = tempo.MetronomeMark(referent=1.0, number=60.0) >>> mm1.secondsPerQuarter() 1.0 >>> mm1 = tempo.MetronomeMark(referent=2.0, number=60.0) >>> mm1.secondsPerQuarter() 0.5 >>> mm1 = tempo.MetronomeMark(referent=2.0, number=30.0) >>> mm1.secondsPerQuarter() 1.0
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MetronomeMark.
secondsToDuration
(seconds)¶ Given a duration in seconds, return a
Duration
object equal to that time.>>> from music21 import tempo >>> mm1 = tempo.MetronomeMark(referent=1.0, number=60.0) >>> mm1.secondsToDuration(0.25) <music21.duration.Duration 0.25> >>> mm1.secondsToDuration(0.5).type 'eighth' >>> mm1.secondsToDuration(1) <music21.duration.Duration 1.0>
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MetronomeMark.
setQuarterBPM
(value, setNumber=True)¶ Given a value in BPM, use it to set the value of this MetroneMark. BPM values are assumed to be refer only to quarter notes; different beat values, if definded here, will be scaled
>>> mm = tempo.MetronomeMark(number=60, referent='half') >>> mm.setQuarterBPM(240) # set to 240 for a quarter >>> mm.number # a half is half as fast 120.0
Methods inherited from TempoIndication
:
Methods inherited from Music21Object
:
MetronomeMark
instance variables
Instance variables inherited from TempoIndication
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Instance variables inherited from Music21Object
:
TempoText¶
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class
music21.tempo.
TempoText
(text=None)¶ >>> import music21 >>> tm = music21.tempo.TempoText("adagio") >>> print(tm.text) adagio
TempoText
bases
TempoText
read-only properties
Read-only properties inherited from Music21Object
:
TempoText
read/write properties
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TempoText.
text
¶ Get or set the text as a string.
Depending on whether “from __future__ import unicode_literals” is turned on, this might give a unicode literal (u’adagio’)
>>> import music21 >>> tm = music21.tempo.TempoText("adagio") >>> print(tm.text) adagio >>> tm.getTextExpression() <music21.expressions.TextExpression "adagio">
Read/write properties inherited from Music21Object
:
TempoText
methods
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TempoText.
applyTextFormatting
(te=None, numberImplicit=False)¶ Apply the default text formatting to the text expression version of of this repeat
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TempoText.
getMetronomeMark
()¶ Return a MetronomeMark object that is configured from this objects Text.
>>> tt = tempo.TempoText("slow") >>> mm = tt.getMetronomeMark() >>> mm.number 56
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TempoText.
getTextExpression
(numberImplicit=False)¶ Return a TextExpression object for this text.
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TempoText.
isCommonTempoText
(value=None)¶ Return True or False if the supplied text seems like a plausible Tempo indications be used for this TempoText.
>>> tt = tempo.TempoText("adagio") >>> tt.isCommonTempoText() True
>>> tt = tempo.TempoText("Largo e piano") >>> tt.isCommonTempoText() True
>>> tt = tempo.TempoText("undulating") >>> tt.isCommonTempoText() False
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TempoText.
setTextExpression
(value)¶ Given a TextExpression, set it in this object.
Methods inherited from TempoIndication
:
Methods inherited from Music21Object
:
TempoText
instance variables
Instance variables inherited from TempoIndication
:
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Instance variables inherited from Music21Object
:
MetricModulation¶
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class
music21.tempo.
MetricModulation
¶ A class for representing the relationship between two MetronomeMarks. Generally this relationship is one of equality, where the number is maintained but the referent that number is applied to changes.
The basic definition of a MetricModulation is given by supplying two MetronomeMarks, one for the oldMetronome, the other for the newMetronome. High level properties, oldReferent and newReferent, and convenience methods permit only setting the referent.
The classicalStyle attribute determines of the first MetronomeMark describes the new tempo, not the old (the reverse of expected usage).
The maintainBeat attribute determines if, after an equality statement, the beat is maintained. This is relevant for moving from 3/4 to 6/8, for example.
>>> s = stream.Stream() >>> mm1 = tempo.MetronomeMark(number=60) >>> s.append(mm1) >>> s.repeatAppend(note.Note(quarterLength=1), 2) >>> s.repeatAppend(note.Note(quarterLength=.5), 4)
>>> mmod1 = tempo.MetricModulation() >>> mmod1.oldReferent = .5 # can use Duration objects >>> mmod1.newReferent = 'quarter' # can use Duration objects >>> s.append(mmod1) >>> mmod1.updateByContext() # get number from last MetronomeMark on Stream >>> mmod1.newMetronome <music21.tempo.MetronomeMark animato Quarter=120.0>
>>> s.append(note.Note()) >>> s.repeatAppend(note.Note(quarterLength=1.5), 2)
>>> mmod2 = tempo.MetricModulation() >>> s.append(mmod2) # if the obj is added to Stream, can set referents >>> mmod2.oldReferent = 1.5 # will get number from previous MetronomeMark >>> mmod2.newReferent = 'quarter' >>> mmod2.newMetronome <music21.tempo.MetronomeMark animato Quarter=80.0>
Note that an initial metric modulation can set old and new referents and get None as tempo numbers...
>>> mmod3 = tempo.MetricModulation() >>> mmod3.oldReferent = 'half' >>> mmod3.newReferent = '16th' >>> mmod3 <music21.tempo.MetricModulation <music21.tempo.MetronomeMark Half=None>=<music21.tempo.MetronomeMark 16th=None>>
test w/ more sane referents that either the old or the new can change without a tempo number
>>> mmod3.oldReferent = 'quarter' >>> mmod3.newReferent = 'eighth' >>> mmod3 <music21.tempo.MetricModulation <music21.tempo.MetronomeMark Quarter=None>=<music21.tempo.MetronomeMark Eighth=None>> >>> mmod3.oldMetronome <music21.tempo.MetronomeMark Quarter=None> >>> mmod3.oldMetronome.number = 60
New number automatically updates...
>>> mmod3 <music21.tempo.MetricModulation <music21.tempo.MetronomeMark larghetto Quarter=60>=<music21.tempo.MetronomeMark larghetto Eighth=60>>
MetricModulation
bases
MetricModulation
read-only properties
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MetricModulation.
number
¶ Get and the number of the MetricModulation, or the number assigned to the new MetronomeMark.
>>> s = stream.Stream() >>> mm1 = tempo.MetronomeMark(number=60) >>> s.append(mm1) >>> s.repeatAppend(note.Note(quarterLength=1), 2) >>> s.repeatAppend(note.Note(quarterLength=.5), 4)
>>> mmod1 = tempo.MetricModulation() >>> mmod1.oldReferent = .5 # can use Duration objects >>> mmod1.newReferent = 'quarter' >>> s.append(mmod1) >>> mmod1.updateByContext() >>> mmod1.newMetronome <music21.tempo.MetronomeMark animato Quarter=120.0> >>> mmod1.number 120.0
Read-only properties inherited from Music21Object
:
MetricModulation
read/write properties
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MetricModulation.
newMetronome
¶ Get or set the right
MetronomeMark
object for the new, or following value.>>> mm1 = tempo.MetronomeMark(number=60, referent=1) >>> mm1 <music21.tempo.MetronomeMark larghetto Quarter=60> >>> mmod1 = tempo.MetricModulation() >>> mmod1.newMetronome = mm1 >>> mmod1.newMetronome = 'junk' Traceback (most recent call last): MetricModulationException: newMetronome property must be set with a MetronomeMark instance
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MetricModulation.
newReferent
¶ Get or set the referent of the new MetronomeMark.
>>> mm1 = tempo.MetronomeMark(number=60, referent=1) >>> mmod1 = tempo.MetricModulation() >>> mmod1.newMetronome = mm1 >>> mmod1.newMetronome <music21.tempo.MetronomeMark larghetto Quarter=60> >>> mmod1.newReferent = .25 >>> mmod1.newMetronome <music21.tempo.MetronomeMark larghetto 16th=240.0>
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MetricModulation.
oldMetronome
¶ Get or set the left
MetronomeMark
object for the old, or previous value.>>> mm1 = tempo.MetronomeMark(number=60, referent=1) >>> mm1 <music21.tempo.MetronomeMark larghetto Quarter=60> >>> mmod1 = tempo.MetricModulation() >>> mmod1.oldMetronome = mm1
Note that we do need to have a proper MetronomeMark instance to figure this out:
>>> mmod1.oldMetronome = 'junk' Traceback (most recent call last): MetricModulationException: oldMetronome property must be set with a MetronomeMark instance
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MetricModulation.
oldReferent
¶ Get or set the referent of the old MetronomeMark.
>>> mm1 = tempo.MetronomeMark(number=60, referent=1) >>> mmod1 = tempo.MetricModulation() >>> mmod1.oldMetronome = mm1 >>> mmod1.oldMetronome <music21.tempo.MetronomeMark larghetto Quarter=60> >>> mmod1.oldReferent = .25 >>> mmod1.oldMetronome <music21.tempo.MetronomeMark larghetto 16th=240.0>
Read/write properties inherited from Music21Object
:
MetricModulation
methods
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MetricModulation.
setEqualityByReferent
(side=None, referent=1.0)¶ Set the other side of the metric modulation to an equality; side can be specified, or if one side is None, that side will be set.
>>> mm1 = tempo.MetronomeMark(number=60, referent=1) >>> mmod1 = tempo.MetricModulation() >>> mmod1.newMetronome = mm1 >>> mmod1.setEqualityByReferent(None, 2) >>> mmod1 <music21.tempo.MetricModulation <music21.tempo.MetronomeMark larghetto Half=30.0>=<music21.tempo.MetronomeMark larghetto Quarter=60>>
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MetricModulation.
setOtherByReferent
(side=None, referent=1.0)¶ Set the other side of the metric modulation not based on equality, but on a direct translation of the tempo value.
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MetricModulation.
updateByContext
()¶ Update this metric modulation based on the context, or the surrounding MetronomeMarks or MetricModulations. The object needs to reside in a Stream for this to be effective.
Methods inherited from TempoIndication
:
Methods inherited from Music21Object
:
MetricModulation
instance variables
Instance variables inherited from TempoIndication
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Instance variables inherited from Music21Object
:
TempoIndication¶
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class
music21.tempo.
TempoIndication
¶ A generic base class for all tempo indications to inherit. Can be used to filter out all types of tempo indications.
TempoIndication
bases
TempoIndication
read-only properties
Read-only properties inherited from Music21Object
:
TempoIndication
read/write properties
Read/write properties inherited from Music21Object
:
TempoIndication
methods
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TempoIndication.
getPreviousMetronomeMark
()¶ Do activeSite and context searches to try to find the last relevant MetronomeMark or MetricModulation object. If a MetricModulation mark is found, return the new MetronomeMark, or the last relevant.
>>> s = stream.Stream() >>> s.insert(0, tempo.MetronomeMark(number=120)) >>> mm1 = tempo.MetronomeMark(number=90) >>> s.insert(20, mm1) >>> mm1.getPreviousMetronomeMark() <music21.tempo.MetronomeMark animato Quarter=120>
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TempoIndication.
getSoundingMetronomeMark
(found=None)¶ Get the appropriate MetronomeMark from anu sort of TempoIndication, regardless of class.
Methods inherited from Music21Object
:
TempoIndication
instance variables
Instance variables inherited from Music21Object
: